GE Energy 

Progress Energy 

Robinson Unit 1 

Furnace Sorbent Injection 

Demonstration Project 

Final Report, Rev. 02 

Contract No. 10023-WA169 GE Job Number 6900 

25 February 2009 

GE Energy and Environmental Research Corporation 

1831 East Carnegie Ave 

Santa Ana, CA 92705
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page ii 

GE Energy

Table of Contents 

Section Page 

1.0 Executive Summary...................................................................................................... 1-1 

1.1 Project Objectives .................................................................................................. 1-1 

1.2 Process Design....................................................................................................... 1-2 

1.3 Engineering Design................................................................................................ 1-4 

1.4 Field Test Program................................................................................................. 1-5 

1.5 FSI System Performance........................................................................................ 1-6 

1.6 Recommendations for Permanent Operation at Robinson..................................... 1-8 

1.7 Transferability of Results to Other Boilers.......................................................... 1-10 

2.0 Introduction................................................................................................................... 2-1 

2.1 Furnace Sorbent Injection Technology Overview ................................................. 2-1 

2.2 Project Objectives .................................................................................................. 2-4 

2.3 Program Overview................................................................................................. 2-5 

3.0 Unit Description............................................................................................................ 3-1 

4.0 Furnace Sorbent Injection Process Design ................................................................... 4-1 

4.1 Overview................................................................................................................ 4-1 

4.1.1 Baseline Operating Conditions ...................................................................... 4-1 

4.1.2 Boiler Temperature Field............................................................................... 4-2 

4.2 Sorbent Injection Process Design .......................................................................... 4-5 

4.2.1 Sorbent Injection Requirements and Constraints........................................... 4-6 

4.2.2 Computation Fluid Dynamics Studies ........................................................... 4-9 

4.2.3 Isothermal Model Studies ............................................................................ 4-10 

4.2.4 Thermal Model Studies................................................................................ 4-12 

4.2.5 Sulfation Model Studies............................................................................... 4-13 

4.3 Sorbent Characterization...................................................................................... 4-14 

4.4 Process Design of FSI Injection System.............................................................. 4-16 

4.4.1 Baseline Study ............................................................................................. 4-16 

4.4.2 Injection Elevation Selection ....................................................................... 4-18 

4.4.3 Injection Configuration Selection................................................................ 4-21 

4.5 FSI Impact on Boiler Thermal Performance........................................................ 4-28 

4.5.1 Coal Firing at 188 MWg.............................................................................. 4-28 

4.5.2 Coal Firing at 61 MWg................................................................................ 4-32 

4.6 Sulfur Capture...................................................................................................... 4-35 

4.7 Design Specification ............................................................................................ 4-36 

5.0 Furnace Sorbent Injection Engineering Design ............................................................ 5-1 

5.1 General Description ............................................................................................... 5-1 

5.2 Silo Fill System...................................................................................................... 5-2 

5.3 Silo Discharge and Metering Feeder System......................................................... 5-2 

5.4 Injection System..................................................................................................... 5-3 

5.5 Controls and Instrumentation................................................................................. 5-7 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page iii 

GE Energy

6.0 ESP Upgrades ............................................................................................................... 6-1 

6.1 Analysis Assumptions............................................................................................ 6-1 

6.2 Estimated Electrostatic Precipitator Performance ................................................. 6-2 

6.3 Short Term Electrostatic Precipitator Upgrades .................................................... 6-2 

6.3.1 Vertical and Hopper Anti-Sneak Baffles ....................................................... 6-2 

6.3.2 Lower Frame Stabilizers................................................................................ 6-3 

6.3.3 Addition of Four (4) T/R Sets to the Inlet Fields........................................... 6-3 

7.0 Field Test Program........................................................................................................ 7-1 

7.1 Test Objectives....................................................................................................... 7-1 

7.2 Test Plan................................................................................................................. 7-1 

7.2.1 Equipment Performance Tests ....................................................................... 7-4 

7.2.2 Parametric Tests............................................................................................. 7-4 

7.2.3 Long-Term Tests............................................................................................ 7-5 

7.3 Measurement Plan.................................................................................................. 7-6 

7.3.1 Boiler Operating Data.................................................................................... 7-7 

7.3.2 Emissions Data............................................................................................... 7-7 

7.3.3 Coal & Ash Sampling .................................................................................... 7-7 

7.4 Test Results............................................................................................................ 7-8 

7.4.1 Start-Up Performance and Demonstrations ................................................... 7-8 

7.4.2 Coal Sample Analysis.................................................................................. 7-13 

7.4.3 Baseline SO2 Emissions............................................................................... 7-15 

7.4.4 SO2 Removal Results................................................................................... 7-17 

7.4.5 Impacts of Boiler Operation on Sulfur Capture........................................... 7-19 

7.4.6 Impacts of Sorbent Injection on SO2 Removal............................................ 7-22 

7.4.7 Ash Analyses ............................................................................................... 7-23 

7.4.8 Mercury Emissions ...................................................................................... 7-24 

7.5 Operating Curves ................................................................................................. 7-25 

7.5.1 Sorbent Flow Rate........................................................................................ 7-26 

7.5.2 Injection Air................................................................................................. 7-28 

7.5.3 Diverter Valve Position................................................................................ 7-29 

7.5.4 Excess Oxygen Curve.................................................................................. 7-30 

7.6 Impact of FSI on Boiler ....................................................................................... 7-31 

7.6.1 Ash Deposition............................................................................................. 7-31 

7.6.2 Boiler Performance ...................................................................................... 7-36 

7.6.3 Opacity......................................................................................................... 7-38 

7.6.4 ESP Performance ......................................................................................... 7-44 

8.0 Recommendations for System Improvements .............................................................. 8-1 

8.1 Sorbent Injection System ....................................................................................... 8-1 

8.2 Boiler Deposit Management System ..................................................................... 8-3 

8.3 Electrostatic Precipitator........................................................................................ 8-3 

8.4 Byproduct Management System............................................................................ 8-5 

9.0 Future FSI Application ................................................................................................. 9-1 

9.1 FSI Technology Viability ...................................................................................... 9-1 

9.2 FSI Performance Projections ................................................................................. 9-2 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page iv 

GE Energy

9.3 FSI Cost Effectiveness........................................................................................... 9-3 

9.4 FSI Schedule .......................................................................................................... 9-4 

9.5 Application of FSI to Other Boilers....................................................................... 9-5 

10.0 Conclusions................................................................................................................. 10-1 

11.0 References................................................................................................................... 11-1 

Appendices.................................................................................................................................1 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page v 

GE Energy

List of Figures 

Figure Page 

1-1. SO2 reduction as a function of Ca/S ratio for parametric tests....................................... 1-6 

2-1. FSI system schematic. .................................................................................................... 2-1 

3-1. Robinson Unit 1.............................................................................................................. 3-1 

3-2. Side view of Robinson Unit 1......................................................................................... 3-2 

3-3. Burner firing angle.......................................................................................................... 3-2 

3-4. Burner arrangement. ....................................................................................................... 3-3 

3-5. Unfolded view of Robinson Unit 1 ROFA system......................................................... 3-5 

3-6. ROFA system plan view................................................................................................. 3-6 

4-1. HVT measurement elevations. ....................................................................................... 4-3 

4-2. HVT measurements for 188 MW load at Elevation 78′................................................. 4-4 

4-3. HVT measurements for 188 MW load at Elevation 107′............................................... 4-4 

4-4. HVT measurements for 62 MW load at Elevation 78′................................................... 4-5 

4-5. Process design methodology. ......................................................................................... 4-6 

4-6. CFD design model geometry........................................................................................ 4-10 

4-7. Lab scale isothermal physical flow model of Robinson Unit 1.................................... 4-11 

4-8. Schematic of Robinson Unit 1 thermal model.............................................................. 4-13 

4-9. Comparison of SO2 capture for four different sorbents in the BSF.............................. 4-15 

4-10. Vertical velocity profiles at the nose plane elevation of 188 MWg load. .................. 4-16 

4-11. Robinson Unit 1 upper furnace flow field at 188 MWg load..................................... 4-17 

4-12. Upward velocity profile of 62 MWg load at 87'-2".................................................... 4-18 

4-13. Average gas temperature profile at a nominal full load injection elevation............... 4-19 

4-14. Average gas temperature profile at a nominal low load injection elevation. ............. 4-19 

4-15. Robinson front wall injection accessibility. ............................................................... 4-20 

4-16. Mixing time as a function of sorbent air for various jet diameter sizes. .................... 4-21 

4-17. Smoke sketch of 12-double simple jet with LFW-RFW-SW configuration. ............. 4-23 

4-18. Smoke sketch of 12-double simple jet with LFW-CFW-SW configuration. ............. 4-23 

4-19. Dispersion profiles at nose plane................................................................................ 4-25 

4-20. Dispersion profiles at nose plane of various location injection systems. ................... 4-25 

4-21. Dispersion profiles at nose plane of various sorbent air flow rates............................ 4-26 

4-22. Dispersion profiles at nose plane of various ROFA flow rates. ................................. 4-27 

4-23. Dispersion profiles...................................................................................................... 4-28 

4-24. Predicted bulk furnace gas temperature at full load. .................................................. 4-32 

4-25. Predicted bulk furnace gas temperature at low load................................................... 4-35 

4-26. SO2 Capture as a function of Ca/S at full load operation. .......................................... 4-36 

4-27. Front view of the sorbent injector locations. .............................................................. 4-38 

4-28. Side view of the sorbent injector locations................................................................. 4-38 

4-29. Plan view of sorbent injector locations at the Elevation 87′-2′′ (± 6′′). ...................... 4-39 

4-30. Plan view of sorbent injector locations at the Elevation 77′-0′′ (± 6′′). ...................... 4-39 

4-31. Conceptual design of an injection box. ...................................................................... 4-40 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page vi 

GE Energy

4-32. Process flow diagram for Robinson Unit 1. ............................................................... 4-42 

5-1. System overview............................................................................................................. 5-1 

7-1. Injection labels for upper elevation injectors. ................................................................ 7-9 

7-2. Comparison of theoretical SO2 and measured baseline SO2 emissions........................ 7-16 

7-3. SO2 removal as a function of Ca/S during the parametric tests.................................... 7-18 

7-4. SO2 removal as a function of Ca/S for all tests. ........................................................... 7-18 

7-5. Sorbent removal rate at two different loads during parametric testing. ....................... 7-20

7-6. Sorbent utilization for 158 MWg and 78 MWg loads. ................................................. 7-20 

7-7. Impact of ROFA on SO2 removal and calcium utilization........................................... 7-21 

7-8. Impact of sorbent air flow rate on the FSI performance............................................... 7-23 

7-9. Loss on ignition during the tests................................................................................... 7-24 

7-10. Mercury emissions as a function of unit gross load. .................................................. 7-25 

7-11. Mercury emissions as a function of Ca/Hg. ............................................................... 7-25 

7-12. Sorbent flow rate as function of steam flow............................................................... 7-27 

7-14. Injection air flow rate as a function of steam flow..................................................... 7-29 

7-13. Diverter valve position as a function of steam flow................................................... 7-30 

7-14. Sketch of ash deposition on secondary superheater and reheat pendants................... 7-33 

7-15. Photographs of airheater inspection. .......................................................................... 7-34 

7-16. Inspection photographs of A & B airheaters. ............................................................. 7-34 

7-17. Primary superheater and primary reheat pendants inspection photographs. .............. 7-35 

7-18. Photograph of the ash deposit analysis....................................................................... 7-36 

7-19. Boiler efficiency as a function of exit O2. .................................................................. 7-37 

7-20. Impact of FSI on main steam temperature as a function of the boiler load................ 7-37 

7-21. Impact of FSI on NOX emission. ................................................................................ 7-38 

7-22. Opacity as a function of SO2 emission at baseline conditions. .................................. 7-39 

7-23. Sample data on September 29, 2008 showing opacity increase................................. 7-41 

7-24. Fish bone analysis for causes of opacity increase. ..................................................... 7-42 

7-25. Impact of load on opacity. .......................................................................................... 7-42 

7-26. Impact of flue gas flow rate on opacity. ..................................................................... 7-43 

7-27. Impact of dust loading on opacity. ............................................................................. 7-43 

7-28. Impact of exit oxygen on opacity. .............................................................................. 7-44 

7-29. Impact of air heater outlet temperature on opacity..................................................... 7-44 

9-1. Projected FSI performance as a function of coal sulfur content..................................... 9-3 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page vii 

GE Energy

List of Tables 

Table Page 

1-1. Furnace Sorbent Injection Design Basis......................................................................... 1-3 

2-1. Failure Modes and Effects Analysis............................................................................... 2-2 

3-1. Design Data For Sootblowing Air Compressor.............................................................. 3-7 

3-2. Sootblower Design Data................................................................................................. 3-7 

3-3. Precipitator Information ................................................................................................. 3-8 

3-4. Electrostatic Precipitator Configuration ......................................................................... 3-1 

3-5. Electrostatic Precipitator Operating Condition............................................................... 3-1 

4-1. Coal Firing Operating Conditions .................................................................................. 4-1 

4-2. Furnace Sorbent Injection Design Basis......................................................................... 4-7 

4-3. Sorbent Injection System Operating Range.................................................................... 4-8 

4-4. Sorbent Particle Size Distribution ................................................................................ 4-15 

4-5. Baseline Performance Predictions at Full Load ........................................................... 4-30 

4-6. Sorbent Injection Performance Predictions at Full Load............................................. 4-31 

4-7. Baseline and Sorbent Injection Performance Predictions at Low Load ....................... 4-34 

4-8. Sorbent Injection System Design Specification ........................................................... 4-41 

4-9. Material Balance For Maximum Operation At 5.5% Sorbent Air ............................... 4-43 

4-10. Material Balance For Nominal Full Load Operation At 5% Sorbent Air .................. 4-44

4-11. Material Balance For Nominal Low Load Operation At 5% Sorbent Air.................. 4-45 

4-12. Material Balance For Minimum Operation At 4% Sorbent Air ................................. 4-46 

5-1. Operation Specifications................................................................................................. 5-4 

6-1. ESP Coal Design Specifications..................................................................................... 6-1 

6-2. Robinson Unit #1 Stack Test Results for 2006............................................................... 6-1 

6-3. Robinson Unit #1 Estimated Stack Emissions w/FSI..................................................... 6-2 

6-4. New T/R sETS Specifications ........................................................................................ 6-3 

7-1. Progress Energy FSI Test Matrix ................................................................................... 7-2 

7-1. Progress Energy FSI Test Matrix (Contd)...................................................................... 7-3 

7-2. Emission Measurements Procedures .............................................................................. 7-7 

7-3. Clean Air Test Results for Upper Elevation Injections .................................................. 7-9 

7-4. Solid Flow Distribution Results for Upper Elevation Injections.................................. 7-10 

7-5. Sorbent Feed Rate test sequence .................................................................................. 7-12 

7-6. Equipment Performance Test Results........................................................................... 7-13 

7-7. Coal Ultimate And Proximate Analysis ....................................................................... 7-14 

7-7. Coal Ultimate And Proximate Analysis (Contd).......................................................... 7-15 

7-8. Test Conditions For Varying Injection Air Rate .......................................................... 7-23 

7-9. Sorbent Flow Rate As A Function Of Steam Flow ...................................................... 7-28 

7-10. FSI Excess Oxygen Curve As A Function Of Steam Flow........................................ 7-31 

8-1. Compositions of Flyash, Sorbent Byproduct, and Portland Cement.............................. 8-6 

9-1. Comparison of Cape Fear and Robinson Coal Properties .............................................. 9-1 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page viii 

GE Energy

Revision History 

Revision Date Author(s) Approver Description of 

Changes 

00 December 30, 2008 Joy Brooks/Pete Maly Wei Zhou First Release 

01 January 30, 2009 

Joy Brooks/Pete 

Maly/Santosh Nareddy 

Wei Zhou Second Release 

02 February 25, 2009 

Joy Brooks/Pete 

Maly/Santosh Nareddy 

Wei Zhou Third Release 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page ix 

GE Energy

Nomenclature 

2DHT Two-dimensional heat transfer and combustion model 

APH Air preheater 

Baseline Without sorbent injection 

Boost Air Injection air 

BSF Boiler Simulator Furnace 

Ca/S Calcium to sulfur molar ratio 

CEMS Continuous emission monitoring system 

CFD Computational Fluid Dynamics 

CFW Center front wall 

COV Coefficient of Variation

ESP Electrostatic Precipitator 

FMEA Failure Modes and Effects Analysis 

FW Front wall 

FSI Furnace sorbent injection 

HHV Higher heating value 

HVT High velocity thermocouple 

Injection Air Airflow from the injection air blower for injecting sorbent to furnace 

LFW Left front wall 

MWe Net boiler load 

MWg Gross boiler load 

PLC Programmable logic controller 

PSH Primary superheater 

PM Particular matter 

RFW Right front wall 

RH Reheater 

ROFA Rotating over fire air 

SH Superheater 

SR Stoichiometric ratio 

Sorbent Air Sum of sorbent transport air and injection air 

SW Sidewall 

Transport Air Airflow that transport sorbent from silo to injectors 

WC Water column 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-1 

GE Energy

1.0 Executive Summary 

This report is organized into 11 major sections, plus appendices. Section 1 is an Executive 

Summary that provides an overview of project objectives, activities, and results. It can be 

used as a stand-alone summary of the project. Section 2 provides an introduction to the 

project. Section 3 provides a description of the Robinson plant. Section 4 describes the 

process design for the FSI system. Section 5 describes the FSI equipment. Section 6 

describes the recommendations for ESP upgrades. Section 7 describes the test plans and 

results of the FSI test program. Section 8 provides recommendations for system 

improvements for potential permanent application of the technology. Section 9 describes 

implications for applying the FSI technology on a commercial basis to Robinson or other 

coal-fired boilers in Progress Energy’s fleet. Section 10 provides project conclusions. Section 

11 provides project references. 

1.1 Project Objectives 

Progress Energy contracted GE Energy (GE) to perform a multi-phase project to demonstrate 

Furnace Sorbent Injection (FSI) technology for SO2 control on Unit 1 at the H.B. Robinson 

plant in Hartsville, South Carolina. From an overall strategic standpoint, project objectives 

were to define technical performance and cost-effectiveness of FSI as a potential means of 

meeting current and pending regulatory emissions control requirements. While the project 

was conducted in South Carolina, Progress Energy also operates boilers in North Carolina 

and has a potential interest in implementing SO2 control methods to comply with the State of 

North Carolina’s “Clean Smokestacks Act.” This act, officially titled the Air Quality/Electric 

Utilities Act (SB 1078), requires significant actual emissions reductions from coal-fired 

power plants in North Carolina. From a Federal regulatory standpoint, while proposed Clean 

Air Interstate Rule (CAIR) legislation was remanded in 2007, it is widely expected that 

similar regulations for control of SO2 and other species will be enacted in the near future. 

The FSI project was designed to provide a basis for technology evaluation as a potential 

means of meeting these regulations. 

Specific technical objectives of the project were as follows: 

• To achieve 40%-50% SO2 reduction 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-2 

GE Energy

• To effectively manage furnace and convective pass deposits, allowing the FSI system 

to be operated for an extended period of time with manageable impact upon boiler 

efficiency and without causing boiler shutdown 

• To meet air permit requirements for particulate matters (PM) emissions and opacity 

• To effectively and safely manage byproduct materials 

• To provide process data to allow an accurate assessment of the feasibility of the FSI 

technology 

Programmatic objectives were to complete the test work in 2008 and to provide Progress 

Energy with summary results in a timely manner to allow the FSI technology to be assessed 

for potential permanent application to Progress Energy boilers. Environmental, health, and 

safety objectives were to manage all project materials and operate project equipment in a safe 

manner, and to meet all plant permit requirements. 

To accomplish these objectives, a multi-phase project was conducted. Initial tasks included 

conceptual and process design, followed by engineering design, equipment procurement and 

installation (not in GE’s scope), and the FSI test program. 

1.2 Process Design 

The primary objectives of the Process Design task were to characterize the operation of the 

boiler, to define Progress Energy’s objectives and constraints for the sorbent injection 

technology, and to develop a FSI design basis, including injection location, injector design, 

sorbent injection air requirements, and required sorbent flow rate. Tools used to complete the 

Process Design included pilot-scale sorbent performance tests, physical flow modeling 

studies, and computational modeling, including computational fluid dynamic, thermal, and 

sulfation modeling. The primary output from the process design task was a Design Basis 

Memorandum [1] summarizing results and conclusions. 

The FSI system was designed for a load range from 62 to 188 MWg. Robinson Unit 1 is 

equipped with a rotating overfire air (ROFA) system for NOX control. The FSI system was 

designed for optimum performance with the ROFA system in operation. The design coal 

sulfur content was 1.6 lb/MMBtu, although the FSI system was designed to be robust enough 

to accommodate the normal range of sulfur contents experienced at Robinson, which is 

approximately 1.4 to 2.6 lb/MMBtu. Objectives were to maximize SO2 reduction while 

minimizing impacts upon upper furnace fouling and ESP performance. Of primary 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-3 

GE Energy

importance in the Process Design was to optimize mixing between the sorbent stream and the 

furnace gas. The FSI system was designed considering the following critical parameters: 

• Flue gas temperature at sorbent injection locations 

• Sorbent type 

• Sorbent to sulfur stoichiometric ratio 

• Sulfur content in coal 

• Injection configurations and locations 

• Sorbent air flow rates 

Table 1-1 summarizes the design basis for the FSI system. 

TABLE 1-1. FURNACE SORBENT INJECTION DESIGN BASIS 

Parameter Design Basis

Sorbent Type Ca(OH)2

Injection Elevation Between Burners and Convective Pass Entrance

Injection Type Wall Injection

Injection Pressure 10 - 30" WC

Ca/S Ratio 1.0 - 3.5

Burner SR Same as Baseline

ROFA Flow Same as Baseline

Sorbent Air 4% - 6% of Total Combustion Air

To avoid the need for burner or overfire air adjustments, the basis for the trial system was for 

the sorbent air to add to the total boiler air. That is, as sorbent injection air was added, a 

proportionate amount of air was not reduced from other boiler input streams. 

For effective SO2 control, hydrated lime has an optimum injection temperature of 

approximately 2100 – 2200oF. Based on furnace temperature and flow field data, the process 

design work found that the optimum injection approach was to have two injector elevations, 

including one optimized for full load operation and one for low load operation. 

Along with the sorbent injection system, deposit management and ESP performance were 

also evaluated during the Process Design phase. The deposit management studies developed 

recommendations that included restoring existing sootblowers to design operating conditions, 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-4 

GE Energy

installing new sootblowers, and installing sonic horns to control ash-sorbent deposits in the 

upper furnace. These upgrades were coupled with an Intelligent Sootblowing system 

furnished to Progress Energy by Emerson. Regarding the ESP, the objective was to make 

nominal upgrades to allow the test project to be completed, with the understanding that 

further measures might be required if it was decided to permanently retain the FSI system. To 

this end, it was recommended to install new Transformer/Rectifier sets in the inlet fields of 

the ESP. A series of physical repairs was also recommended, including washing the unit, 

repairing and adding anti-sneak baffles, repairing support insulators, and installing lower 

frame stabilizers and hopper baffles. 

1.3 Engineering Design 

The FSI system was designed to store hydrated lime sorbent, transport it to the upper furnace, 

and inject it into the boiler with sufficient air to provide good mixing with the furnace gas. 

The system was designed to include the following major components: bulk storage silos, a 

weigh hopper, rotary air lock feeder, sorbent transport system, boiler penetrations, sorbent 

injectors, and boost air fan / ductwork. The system is of a semi-permanent design, meaning 

that it is designed to accommodate a continuous trial several months in duration. 

The system was designed for sorbent delivery to the facility in self-unloading bulk transport 

trucks, which unload into three identical, prefabricated bulk storage silos. Each silo was 

designed to have a capacity of approximately 150 tons of Ca(OH)2. Combined, the three silos 

provide approximately five days capacity at full load operation. The silos were designed with 

a cone bottom, air activation to ensure the good flow of material, bin vent filter, and humidity 

monitors. The silos are skirted and have an enclosed base. The bases of the silos house all of 

the sorbent metering and transport equipment. The sorbent is discharged from the silos into a 

day hopper via a rotary feeder. 

The sorbent was designed to be fed by means of a rotary airlock feeder with a capacity of 

approximately 15,000 lb/hr. The feeder discharges the solids into a dilute phase transport 

line. The sorbent transport blower then transports the sorbent in dilute phase from the silo up 

to the furnace sorbent injectors. The sorbent transport lines from the silo to the furnace are 

reinforced rubber hose. Near the boiler the sorbent is conveyed through a splitter and is sent 

to the furnace injectors. The furnace injectors are located at two elevations, with one 

optimized for full load and one for low load. The injection nozzles have a coaxial design. The 

sorbent is injected through the inner nozzle, and propelled into the furnace via injection air 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-5 

GE Energy

from the outer annulus. New waterwall penetrations were made in the furnace to allow for 

the installation of the sorbent injectors. 

Injection air is supplied to each sorbent injector via a new injection air supply system. This 

system consists of a injection air fan/blower, flow control instrumentation and a system of 

ductwork/piping to supply the air to each of the sorbent injectors. There is a flexible 

connection and isolation valve to each injector. Progress Energy directly managed FSI 

system installation work, with GE support on system commissioning and checkout. 

1.4 Field Test Program 

FSI performance tests began after completion of installation and checkout. FSI test tasks 

included equipment performance tests, parametric tests, and the long-term trial. The 

equipment performance tests were designed to ensure that FSI system sorbent and air flow 

rates were able to meet specifications with regard to capacity and accuracy. The system was 

generally found to meet flow rate objectives. 

A parametric and long-term test plan was defined to meet the major technical requirements 

for performance of the installed FSI system. The primary objectives of the testing were to: 

• Characterize the performance of the FSI system relative to key parameters that 

influence boiler thermal performance and operability, SO2 reduction performance, 

particulate emissions and ash handling. 

• Define operating curves for integration into the distributed control system (DCS). 

• Optimize FSI operation over the normal boiler load range. 

• Demonstrate the ability to operate the sorbent injection system over a long-term test 

period while maintaining SO2 reduction and acceptable boiler operability and 

particulate emissions. 

• Identify any problems and suggest corrective actions. 

Key test parameters included sorbent flow rate, Ca/S ratio, boiler load, sorbent injection air 

flow rate, coal sulfur content, injector elevation, and ROFA system operation. Approximately 

three weeks of parametric tests were conducted. The long-term trial lasted approximately 

nine weeks. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-6 

GE Energy

1.5 FSI System Performance 

The primary focus of the project was to reduce SO2 emissions from the Robinson boiler. 

Other technical objectives were to maintain boiler operability, to comply with air permit 

requirements, to effectively manage byproducts, and to define impacts upon emissions of 

other species, notably NOX and mercury. Primary measurements and performance indicators 

included stack CEMS measurements for SO2, O2, CO2, NOX and mercury, stack opacity, unit 

temperatures and steam conditions, boiler load and heat rate, burner tilts, ROFA conditions, 

and sorbent feed rate. 

The test work revealed that SO2 reduction levels were generally consistent with projections 

made during the Process Design phase of the project. Figure 1-1 summarizes SO2 reduction 

as a function of Ca/S ratio for the parametric test runs, along with initial performance 

projections. At the design Ca/S ratio of 2.5, SO2 reduction ranged from approximately 40% 

to 55%. The parametric tests were more well-controlled than the long-term tests in terms of 

isolating process variables. In particular, baseline SO2 measurements were obtained each test 

day during the parametric tests. For the long-term trial, baseline sulfur measurements were 

taken from coal analyses. Generally multiple coal sources were fired during each long-term 

test day, leading to a higher margin of uncertainty with regard to baseline sulfur levels. The 

highest SO2 reduction achieved during the long-term trial was 71.6%, at a Ca/S ratio of 3.8 at 

70 MWg. 

0

10

20

30

40

50

60

70

0 1 2 3 4

Ca/S

SO2 Reduction, %2007 Prediction

~159 MWg

~134 MWg

~76 MWg

Figure 1-1. SO2 reduction as a function of Ca/S ratio for parametric tests. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-7 

GE Energy

Regarding dependence of system performance upon operating parameters, SO2 reduction 

increased with increasing sorbent injection air flow rate. This is attributed to improve mixing 

between the sorbent and furnace gas. The system was configured such that increasing sorbent 

air caused overall furnace gas flow rate and oxygen concentration to increase, decreasing 

boiler efficiency and causing opacity to increase. Therefore, for the scope of the 

demonstration project it was not feasible to maximize sorbent air for all test runs. However, 

system modifications could be made to improve mixing and penetration with reduced amount 

of sorbent air for potential permanent application. 

It was found that SO2 reduction was higher at low load than at full load. This is attributed to 

better sorbent-furnace gas mixing, as the sorbent stream can more readily penetrate the 

furnace flow field when overall furnace flow rates and velocities are lower. FSI system sulfur 

reduction was slightly better with ROFA on than with ROFA off, although the effect was 

small. This is consistent with the system design basis, which involved optimizing 

performance with ROFA on. 

FSI provided approximately 80% mercury reduction during the trial. Possible mechanisms 

for this performance are direct capture of mercury by the lime sorbent or improved mercury 

capture by fly ash carbon due to SO3 reduction by the sorbent. 

Regarding boiler performance during FSI operation, furnace deposits were found to be 

manageable by the unit sootblower/sonic horn system. While upper furnace deposits were 

visually observed to increase during FSI operation, the deposits could be readily removed by 

operating the unit deposit management system, which consisted of operating the sonic horns 

continuously and the sootblowers in a cyclic manner. Boiler thermal efficiency decreased 

slightly during full load FSI operation. However, most of this effect is attributed to the 

increased air flow rate associated with FSI operation. For permanent application, system 

operations could be made to maintain constant total air flow rate during FSI by reducing 

burner air and ROFA air flows. A study of impacts upon parameters such as CO emissions 

and tube wastage would be required prior to reducing burner air. 

Opacity and particulate matter emissions increased during FSI operation. This effect was 

expected, since FSI increases fly ash mass loading and resistivity and decreases mean particle 

size. The plant’s opacity limit is 40%, and the guideline during the project was to reduce FSI 

operation when opacity exceeded 35%. At certain full load conditions, opacity limited the 

amount of sorbent that could be injected into the boiler. The single most important parameter 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-8 

GE Energy

upon opacity was found to be ESP gas temperature. Other parameters such as dust loading 

and coal sulfur content were found to be secondary factors. Coal sulfur content appeared to 

be less important to opacity during FSI operation than during baseline coal firing, possibly 

due to SO3 capture by the sorbent. The extra air associated with FSI operation caused ESP 

temperature to increase, leading to an increase in opacity. Lower sorbent air flow rates led to 

lower ESP temperatures and lower opacity readings. Also, the test work began in summer 

and concluded in late fall. It was found that as ambient temperatures decreased through the 

fall, ESP temperatures and thus opacity decreased. 

Opacity was also found to increase with increasing sorbent flow rate and flue gas volumetric 

flow rate. From an operational standpoint, during the course of the test work several ESP 

operational modifications were made, including restoring the inlet field to nameplate power 

input and implementing an FSI-specific rapping program. These modifications provided 

moderate improvements to performance. PM mass emissions were measured during three 

series of manual method sampling runs and were found to be well below permit limits but 

above pre-FSI historic values. Sorbent particles are relatively fine and reflective, and thus 

have higher impact upon opacity than upon mass emissions. 

1.6 Recommendations for Permanent Operation at Robinson 

While the FSI system allowed the demonstration tests to be completed, a series of system 

modifications and upgrades would be required for potential permanent application. First, the 

basis for the trial system was for the sorbent air to add to the total boiler air. That is, as 

sorbent injection air was added, a proportionate amount of air was not reduced from other 

boiler input streams. Therefore, furnace oxygen concentration and flow rate increased during 

FSI operation, which caused boiler thermal efficiency to decrease, back-end system 

temperatures to increase, and ESP collection efficiency to decrease. For permanent 

application it is recommended to reconfigure the system to allow total air flow rate to remain 

constant during FSI operation. This would require a study of burners and other system 

components to define the range of allowable operation and to evaluate any impacts upon 

other species such as NOX and CO. 

As mentioned above, opacity had the potential to limit FSI operation at full load boiler 

conditions. Several system upgrades could be made to facilitate potential a permanent FSI 

application. Options include: 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-9 

GE Energy

• Reduce sorbent injector size or number of injectors to minimize injection air 

requirements. 

• Humidification. A humidification system would consist of a series of atomization 

nozzles to spray water into the ductwork upstream of the ESP. Through evaporative 

cooling, the system would reduce gas temperature, reduce dust resistivity, and reduce 

flue gas volume. Such a system would present operating risks as it would be 

necessary to ensure complete evaporation, since interactions between sorbent 

byproducts and liquid water could generate cement-like deposits. 

• Field Addition. An inlet field could be added to the Robinson ESP. This approach 

would greatly upgrade ESP capture efficiency, although at significant cost. 

• Fabric Filter Baghouse. A conventional fabric filter baghouse or advanced system 

such as GE’s Max-9 electrostatic fabric filter could be installed to replace the existing 

ESP. This approach might be of interest relative to potential future PM2.5 

regulations. 

• Ash Dropout Box. A louver plate system could be installed upstream of the ESP, 

using inertial separation principles to act as a pre-collection device, at a significant 

cost due to the Robinson boiler configuration, space, and support steel structures. 

While the FSI equipment itself generally performed as intended during the test program, 

several issues were noted. Feeding from a silo proved difficult at times, possibly due to 

residual sorbent that may have gotten wet or otherwise agglomerated. A detailed checkout 

and cleaning of the affected silo is recommended. The reinforced rubber sorbent transport 

hoses experienced erosion problems just downstream of the splitter. It is believed that the 

splitter outlet hose barbs had smaller diameter than the hoses, causing a region of high 

velocity and flow recirculation, leading to erosion. It is recommended to change this 

configuration such that the diameter of the hose barbs is close to that of the hose via crimpon hose fittings similar to what was used on the 6" hose or replace with hard piping. Erosion 

areas were also noted in other constrained areas of the hoses. The distribution system design 

parameters need to be reviewed and potentially the hose distribution system needs redesign. 

In addition to prevent erosion, the hose distribution system improvement should also 

consider an air cleanout system to clear lines as they plug. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-10 

GE Energy

As a final recommendation, it is suggested to consider using the sorbent-ash byproduct 

stream as an input stream to production of construction materials. For purposes of the 

demonstration the byproduct was shipped to a landfill. To improve process economics other 

reuse applications should be pursued. 

1.7 Transferability of Results to Other Boilers 

In general the FSI process could be applied to a wide range of boilers. In past applications, 

FSI has been applied to pulverized coal-fired boilers with tangential, wall, and cyclone firing 

configurations. The primary technology requirement is to have boiler access and sufficient 

mixing and residence time for sorbent sulfation in the optimum furnace gas temperature 

window of approximately 2100–2200oF. These requirements are achievable in a wide range 

of boilers. The parameters that impact potential FSI performance on a specific boiler include: 

• Coal sulfur concentration 

• Boiler design and furnace flow field characteristics 

• Boiler access for sorbent injectors in the optimum temperature window 

• Availability of space at the plant to locate FSI equipment 

Other factors also define the level of plant upgrades that may be required to accommodate 

FSI. These factors include ESP design and specific collection area, ash handling system 

design and capacity, ash pond capacity (if wet ash management is utilized), and upper 

furnace ash deposit management system design. These parameters require plant-specific 

evaluation to evaluate potential FSI performance for a given boiler. 

Regarding potential application of FSI to other Progress Energy boilers, boilers of potential 

interest are Cape Fear Unit 5 & 6. Cape Fear 6 is virtually identical to Robinson 1 and also 

has ROFA. Before the current project settled upon Robinson Unit 1 as the FSI application 

site, GE performed an initial assessment of FSI application to Cape Fear Unit 5. This unit is 

slightly smaller than the Robinson boiler, but has many design similarities. Cape Fear Unit 5 

is a 153 MWe, four-corner tangentially fired boiler that is located in Moncure, NC. The unit 

was installed by Combustion Engineering in 1957. It is equipped with four levels of burners. 

A ROFA system was installed in 2000. The unit is equipped with a cold-side ESP. Cape Fear 

Unit 5 fires eastern bituminous coals from the Fola and Camp Creek mines. These coals have 

similar analyses to the Robinson coals. Therefore, in terms of furnace gas flow field 

characteristics and furnace gas sulfur levels, Cape Fear 5 is similar to the Robinson boiler. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1-11 

GE Energy

While more detailed evaluation of sootblowers, the ESP, and the ash management system 

would be required to accurately estimate total FSI project costs and performance, in general 

FSI performance at Cape Fear Unit 5 would be expected to be similar to that obtained at 

Robinson. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-1 

GE Energy

2.0 Introduction 

2.1 Furnace Sorbent Injection Technology Overview 

The Furnace Sorbent Injection (FSI) process involves injection of dry sorbents into the upper 

furnace of a boiler for reduction of SO2 emissions, forming solid products that are captured in 

the plant particulate control equipment. Figure 2-1 is a schematic of the FSI technology. 

Primary equipment includes sorbent storage silos, feeders, transport lines and injectors. 

Along with sorbent reactivity towards SO2, other important FSI design considerations include 

impacts upon boiler deposit management, ESP performance, and byproduct management. To 

characterize potential operational impacts and to develop recommended corrective actions, a 

detailed Failure Modes and Effects (FMEA) analysis was developed. The FMEA was 

compiled during a series of meetings between GE and Progress Energy. Potential failure 

modes were grouped into four categories. Each failure mode was assigned a Relative Priority 

Number based on the likelihood, detectability, and severity of the failure. As summarized in 

Table 2-1, a total of 341 potential failure modes were identified. The FMEA was updated 

throughout the course of the project. 

Stack

ESP

Upgrades APH

Coal

Air

FSI storage 

and transport 

equipment

Management of upper 

furnace deposits

Byproduct management:

Usage/disposal

Sorbent Delivery

Sorbent

Storage

Stack

ESP

Upgrades APH

Coal

Air

FSI storage 

and transport 

equipment

Management of upper 

furnace deposits

Byproduct management:

Usage/disposal

Sorbent Delivery

Sorbent

Storage

Figure 2-1. FSI system schematic. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-2 

GE Energy

Calcium-based sorbents are most commonly used in the FSI process because they have 

relatively high reactivity and generate manageable boiler deposits. Magnesium- and sodiumbased sorbents have also been applied to the FSI process. However, magnesium sorbents tend 

to be less reactive than calcium sorbents, and sodium sorbents can generate extensive fouling 

deposits. The FSI process typically provides 40%-60% SO2 control. As compared to wet 

scrubbing and spray drying techniques, FSI has higher operating costs due to lower sorbent 

utilization (hence greater sorbent requirements for comparable levels of control), but has 

lower capital cost. FSI is best suited to smaller boilers (i.e. less than 300 MWe), shorter life 

cycles, and moderate SO2 control. FSI is also suited to requirements for emissions control on 

a plant-by-plant basis as opposed to a cap-and-trade approach. 

FSI emission reduction performance is site-specific due to differences in boiler geometry, 

fuel properties, time-temperature history through the boiler, sorbent characteristics, injection 

configuration, and other factors. Sorbent utilization is a measure of the efficiency of the 

process, and achieving maximum utilization reduces the quantity of sorbent required and 

waste produced in a given installation. To achieve maximum utilization, the injection system 

must be designed carefully, with appropriate mixing to disperse the sorbent into the boiler 

flow field and to maximize sorbent residence time within the reaction temperature window 

without deactivating the sorbent due to sintering. GE has experience in more than 20 FSI 

installations worldwide and is one of the original innovators of the process. GE’s design 

TABLE 2-1. FAILURE MODES AND EFFECTS ANALYSIS 

Relative Priority 

Number Range

Material 

Handling Boiler Emissions Control

Byproduct 

Removal Total

0-100 3 71 7 1 82

101-200 17 39 5 4 65

201-300 9 69 4 1 83

301-400 9 29 9 3 50

401-500 2 28 0 1 31

501-600 0 21 6 1 28

601-700 0 1 1 0 2

701-800 0 0 0 0 0

Total 40 258 32 11 341
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-3 

GE Energy

methodology includes computational and physical modeling tools to achieve maximum 

sorbent utilization. 

The most reactive sorbents, such as hydrated lime, typically have the smallest particle sizes. 

These are challenging materials from a handling and transport perspective. They can cause 

storage and feed problems such as fluidization, bridging and surging. Sorbent is typically 

injected into the boiler furnace pneumatically. Discharge of static electricity and surging in 

pneumatic transport systems also can occur if appropriate designs and materials are not used. 

In the current project GE designed FSI injectors providing variable injection velocities to 

maximize sorbent utilization over the boiler load range. 

Sorbents can alter both the quantity and the characteristics of ash deposits on boiler heat 

transfer surfaces. If not properly mitigated, these deposits can affect boiler thermal 

performance and efficiency. For example, significantly increased use of retractable 

sootblowers in the superheat and reheat sections has often been required to maintain steam 

temperatures, which in turn increases tube wastage rate. Sorbent materials can interact with 

fly ash and change ash properties, such as by decreasing fusion temperatures and emissivity, 

which can change deposit patterns, shift heat transfer within the boiler and reduce the 

effectiveness of sootblowers. Interactions between sorbent and ash are coal- and boilerspecific. Proper characterization and planning is required to ensure that acceptable boiler 

operability, availability and efficiency are retained. A number of techniques are available to 

evaluate and control particulate deposition. Detailed sorbent and ash analyses can be 

obtained and used in conjunction with boiler performance indices and ash chemistry 

predictions to characterize the potential impacts of sorbent injection on boiler slagging and 

fouling. Boiler physical and computational flow modeling techniques can be used to evaluate 

particulate deposition in more detail. Pilot-scale combustion test work can also be performed 

to evaluate sorbent-ash interactions and deposit characteristics with specific fuels. The results 

of each of these analyses can be used to estimate site-specific potential particulate deposition 

effects and to define mitigating measures, such as modifications to the number, type, and 

operating frequency of sootblowers. These analyses can also be used to evaluate the potential 

impacts of changing coal type on particulate deposition. Bottom ash and economizer hopper 

ash handling systems need to be evaluated for capacity to handle this increased ash volume 

and to avoid plugging. 

The FSI process can adversely affect particulate control device efficiency, leading to 

increased PM10 and PM2.5 emissions, by changing fly ash properties in several ways. The 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-4 

GE Energy

most significant impacts are greatly increased dust loading faced by the ESP. Even if control 

efficiency is maintained, this results in increased particulate emissions. The other factors 

impacting ESP performance include: 

• The alkaline sorbent materials increase fly ash resistivity, which can quickly degrade 

electrical power in precipitator fields. This may potentially require electrostatic 

precipitator upgrades such as installing a humidification system, upgrading controls, 

or increasing specific collection area. 

• Fly ash size distribution can be affected. In particular hydrated lime sorbents typically 

have mass mean diameters of less than 5 microns, which is much smaller than typical 

fly ash. This can affect control device efficiency, again potentially requiring 

upgrades. 

• Ash volume is increased, potentially requiring modifications to ESP rapping cycles. 

At the nominal full-load system design point, fly ash loading to the precipitator 

increased by about 40%. Further, the collected material can become cement-like upon 

contacting moisture, which can lead to hard deposits on collection plates, ducts, and 

hoppers. 

Each of these factors must be carefully considered to ensure that plant opacity and particulate 

matter emissions remain within acceptable bounds. 

Furnace sorbent injection increases the volume of byproducts generated. FSI also changed 

waste characteristics, potentially increasing leachate pH and the concentration of calcium 

compounds. If a wet ash management system such as an ash pond is used, impermeable pond 

liners and/or neutralization may be required. Robinson plant installed and used a dry ash 

system to avoid these issues. Also, collected sorbent byproducts are typically found in a 

calcined state. In this state the materials are reactive with water and the hydration process 

generates heat and steam and must be properly managed. 

2.2 Project Objectives 

The primary focus of the project was to measure, evaluate and assess the efficiency and costeffectiveness of FSI as a potential means of meeting current and pending regulatory SO2

emissions control requirements. Specific technical objectives of the project were as follows: 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-5 

GE Energy

• To achieve 40%-50% SO2 reduction, 

• To effectively manage furnace and convective pass deposits, allowing the FSI system 

to be operated for an extended period of time with manageable impact upon boiler 

efficiency and without causing boiler shutdown, 

• To meet air permit requirements for PM emissions and opacity, 

• To effectively and safely manage byproduct materials, and 

• To provide process data to allow an accurate assessment of the feasibility of the FSI 

technology. 

Programmatic objectives were to complete the test work in 2008 and to provide Progress 

Energy with summary results in a timely manner to allow the FSI technology to be assessed 

for potential permanent application to Progress Energy boilers. Environmental, health, and 

safety objectives were to manage all project materials and operate project equipment in a safe 

manner, and to meet all plant permit requirements. 

To accomplish these objectives, a multi-phase project was conducted. Initial work focused on 

conceptual and process design, followed by engineering design, equipment installation (not 

in GE’s scope), and the FSI test program. 

2.3 Program Overview 

The FSI program was structured into a multi-phase approach. Major phases and the schedule 

for the project were as follows: 

• Phase 1. Conceptual Design and Failure Modes & Effects Analysis (FMEA): April 

2006 – September 2006 

• Phase 2. Pilot-Scale Testing: October 2006 – December 2006 

• Phase 3. Process Design and Detailed Design: September 2006 – June 2007 

• Phase 4. FSI System Procurement and Installation: November 2007 – July 2008 

• Phase 5. Field Trial and Performance Evaluation: July 2008 – December 2008 

• Phase 6. System Recommendations and Reporting: December 2008 – February 2009 

GE specifically performed all design and pilot test work in Phases 1-3. Progress Energy 

directly managed the Phase 4 procurement and installation work, with technical review by 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 2-6 

GE Energy

GE. Phase 5 was a joint effort in which Progress Energy provided operations personnel to run 

the FSI system, with GE on-site engineering and technical support to define test plans, obtain 

and reduce data, and collect samples. GE completed the Phase 6 recommendations and 

reporting. 

Project reviews and decision points were in place after Phase 1 and Phase 2 of the project. 

GE’s past experience with FSI indicated that along with sorbent reactivity, secondary 

impacts upon boiler operability with regard to managing furnace deposits, ESP performance, 

and byproduct management were of direct importance to the potential success of the 

technology. To evaluate, rank, and define how to address these impacts, a detailed Failure 

Modes and Effects Analysis was performed. 

After the Process Design work projected that boiler impacts could be effectively mitigated 

and that sorbent reactivity objectively could be met, the project proceeded to the design and 

construction phases. From standpoint of both permitting and project scope, the plan was to 

run the long-term trial for several months and then shut down system operation. However, 

the equipment was designed to allow conversion to a permanent installation should this be of 

interest. In particular, the FSI system foundation, silos, feeders, and injectors are suitable for 

permanent operation. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-1 

GE Energy

3.0 Unit Description 

Robinson Unit 1 is a 188 MWg, tangentially fired boiler located in Hartsville, South Carolina 

(Figure 3-1). It was installed by Combustion Engineering, Inc. in 1963 and is owned and 

operated by Progress Energy. This section of the report describes the boiler design and 

operating characteristics. 

Robinson Unit 1 is a plain-tube tangentially fired twin-furnace boiler, which has a width of 

42' 2-3/8", a depth of 24' 1-1/2", and a gross furnace volume of 102,400 cubic feet. A side 

view of the unit is shown in Figure 3-2. The unit is equipped with five CE-Raymond No. 633 

bowl mills and five levels of tilting tangential burners on each eight corners. The burner 

firing angles and nozzle arrangement are shown in Figure 3-3 and Figure 3-4, respectively. 

The superheater temperature can be controlled by spray attemperator or burner tilt. The boiler 

uses the burner tilts as a primary method for superheat control. The unit has a multistage 

superheater with platens, an inter-stage reheater, a CF-S type economizer and two 

Ljungstrom generative air heaters.

Figure 3-1. Robinson Unit 1. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-2 

GE Energy

Figure 3-2. Side view of Robinson Unit 1. 

32o 22o 32o

22o

32o 22o 32 22o

o

Front Wall

Figure 3-3. Burner firing angle. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-3 

GE Energy

Robinson Unit 1 is equipped with a rotating overfire air (ROFA) system for NOx control. 

The system consists of 14 injection boxes located at four different elevations from 77 to 92 

feet as shown in Figure 3-5. The injection angle of each injector is shown in Figure 3-6. The 

ROFA fan capacity is 174,000 ACFM at 570oF and 40 in. WC. All 14 injector boxes are 

designed to operate up to 30 in. WC. The upper boxes of ROFA system are not being used in 

order to reduce erosion in the secondary superheater. Some injectors within a given box are 

partially blocked. The blocked injectors are UR1 center injector, UFR2 lower injector, UFL2 

lower injector, UFL1 upper injector and UL1 center injector. The baseline study in this 

project is based on a full load and a low load operating condition with the ROFA system in 

place. At full load operating condition (188 MWg), the amount of ROFA flow is estimated to 

be up to 25% of total combustion air. At low load operating condition (61 MWg), the ROFA 

flow rate is approximately up to 38% of total combustion air. The ROFA flow rate is 

estimated based on the ROFA box pressure measurements that were provided by Progress 

Energy and GE site visit. The sorbent injection system is designed to operate at various 

ROFA flow rates. 

Top Air

Coal

Oil/Auxiliary Air

Coal

Coal

Coal

Coal

Oil/Auxiliary Air

Auxiliary Air

Auxiliary Air

Bottom Air

Figure 3-4. Burner arrangement. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-4 

GE Energy

The sootblower system in the Robinson unit consists of twelve long retractable blowers 

(IK’s), thirty-two furnace wall blowers (IR’s), and two air preheater sootblowers. Two 300-

psig sootblowing air compressors and an air receiver tank supply compressed air to the 

sootblowing system through a pressure reducing station. The design data for the sootblowing 

air compressors, wall sootblowers and retractable soot blowers are listed in Table 3-1 to 

Table 3-2. The sootblower arrangement is shown in Figure 3-7. 

The original electrostatic precipitator (ESP) was installed by Buell in the 1970’s and had 

eight (8) transformers. The precipitator was rebuilt by Environmental Elements Corporation 

in 1997. Prior to the FSI demonstration program, the precipitator had six transformers. All 

six precipitator transformers remained at 100% power to reduce opacity as low as needed (or 

required). In the existing system, if opacity is below 20%, power-off rapping is utilized 

below 120 MW by changing the I&C. The precipitator has a collection area of approximately 

330 ft2/kacfm. The precipitator information is summarized in Table 3-3 through Table 3-5. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-5 

GE Energy

Figure 3-5. Unfolded view of Robinson Unit 1 ROFA system.
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-6 

GE Energy

SW

NW

SE

NE

112′′

A=10o

B=5o

C=0o

A=-10o

B=-5o

C=0o

A=0o

B=0o

C=0o

A=0o

B=0o

C=0o

156′′

192′′

48′′

96′′

168′′

UFR2

168′′

96′′

84′′

48′′

A=-6o

B=-3o

C=0o

A=-4o

B=-2o

C=0o

A=-18o

B=-12o

C=0o

A=18o

B=18o

C=18o

A=-18o

B=-18o

C=-18o

A=18o

B=12o

C=0o

A=4o

B=2o

C=0o

A=6o

B=3o

C=0o

LFL2 LFL1 UFL1 UFL2 UFR1 LFR1 LFR2

LBL1 LBL2 LBR2 LBR1

UL UR

112′′

84′′

192′′

156′′

Figure 3-6. ROFA system plan view. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-7 

GE Energy

TABLE 3-1. DESIGN DATA FOR SOOTBLOWING AIR COMPRESSOR 

Parameters Units Value

Manufacturer Worthington

Type 3 Stage Vertical Angle

Discharge Pressure psig 300

Capacity cfm 690

Mechanical Power bhp 188

Compressor Speed rpm 500

Motor Data

Manufacturer General Electric

Motor Horsepower hp 200

Motor Speed rpm 505

Electrical Ratings volt 440

amp 282

phase 3

Power Supply Large 480 volt Load Center

TABLE 3-2. SOOTBLOWER DESIGN DATA 

Parameters Units Wall Sootblower Retractable Sootblower

Manufacturer and Model Diamond Model IR Diamond Model IK Series 300

Motor Size hp 1.6 1.5

Motor Speed rpm 1800 1750

Motor Starter

Limit Switches

Located Remotely in a Separate Cabinet

Located on Each End of the Blower Assembly
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-8 

GE Energy

EL. 35′ 3′′

EL. 66′ 0′′

EL. 77′ 11′′

EL. 106′ 6′′

EL. 111′ 0′′

EL. 92′ 11′′

Figure 3-7. Sootblower arrangement. 

TABLE 3-3. PRECIPITATOR INFORMATION 

Parameters Information

Year Built 1997

Type Cold Side

Manufacturer Environmental Element

Rectifier Transformer Location Top

Dielectric Fluid Type Mineral Oil
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 3-1 

GE Energy

TABLE 3-4. ELECTROSTATIC PRECIPITATOR CONFIGURATION 

Parameters Unit Value

Number of casings - 1

Chambers per casing - 2

Gas passage width in 12 1⁄2

Pas passage per field - 29

Number of mechanical fields - 3

Field 1 ft-in 12'-11⁄2" x 36'-0"

Field 2 ft-in 12'-11⁄2" x 36'-0"

Field 3 ft-in 12'-11⁄2" x 36'-0"

Electrical field -

Field 1A mA-kV 1,400-50

Current Density μA/ft2

55

Field 1B mA-kV 1,400-50

Current Density μA/ft2

55

Field 2A mA-kV 1,400-50

Current Density μA/ft255

Field 2B mA-kV 1,400-50

Current Density μA/ft255

Field 3A mA-kV 1,400-50

Current Density μA/ft255

Field 3B mA-kV 1,400-50

Current Density μA/ft2

55

TABLE 3-5. ELECTROSTATIC PRECIPITATOR OPERATING CONDITION 

Parameters Unit

Total collecting plate area ft2

151,902

Treatment length ft2

36.38

Aspect ratio - 1.01

Specific collecting area, SCA ft2

/1000 acfm, actual 249

ft2/1000 acfm @ 12" GP 260

Gas velocity ft/s 4.67

Treatment time s 7.8

Number of electrical fields - 6

current density μA/ft2

55

applied voltage kV/inch 8

Value
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-1 

GE Energy

4.0 Furnace Sorbent Injection Process Design 

4.1 Overview 

Furnace sorbent injection (FSI) technology consists of injecting calcium-based sorbent such 

as limestone (CaCO3) or hydrated lime (Ca(OH)2) into the upper portion of the furnace. Once 

injected, the sorbent is calcined and reacts with SO2 to form calcium sulfate under fuel lean 

conditions. Numerous studies have shown that the capture of SO2 depends on flue gas 

temperature at injection elevation, initial SO2 concentration, sorbent type, sorbent particle 

size, quench rate, and the mixing rate of the injected sorbent. 

The design of an FSI system for a utility boiler requires careful examination of the boiler 

structural configuration, process parameters, operational characteristics, and gas-side flow 

field characteristics. The primary design objectives are to: 

• Maximize sorbent utilization, and 

• Maintain acceptable boiler operation performance and emissions. 

Achieving these objectives requires rapid and uniform mixing of the sorbent with the flue gas 

while maintaining near-baseline boiler performance. The Robinson FSI process design study 

applied several design tools, including physical flow modeling, computational fluid dynamics 

(CFD) modeling, thermal modeling, and sulfation modeling, to simulate the boiler and FSI 

system performance. The results from the study were used to define FSI system design 

specifications, which served as the basis for the engineering design phases of this project. 

4.1.1 Baseline Operating Conditions 

The operating parameters for Robinson Unit 1 in Table 4-1 are based on information provided 

by Progress Energy and GE site visit findings. The information provided by Progress Energy 

is based on an average plant data during the period of August 2005 to March 2006. The 

available operating data includes the flow rates, temperatures, and pressures of steam and flue 

gas. The burner tilt positions range from –30 to +30 degrees range. At low load, the bottom 

Mills D and E are out of service to maintain steam temperature. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-1 

GE Energy

TABLE 4-1. COAL FIRING OPERATING CONDITIONS 

Gross MW MW 188 188 62 62

Exit O2* % wet 3.34 3.34 7.23 7.23

Steam/Water Flows

Steam Flow Klb/hr 1382 1382 469 469

Feed Water Flow Klb/hr 1382 1382 469 469

Steam/Water Pressure

Throttle Pressure psig 1802 1802 1802 1802

Feed Water Pressure psig 2451 2451 2657 2657

Cold Reheat Pressure psig 489 489 185 185

Hot Reheat Pressure psig 440 440 178 178

Drum Pressure psig 1959 1959 1824 1824

Steam/Water Temperatures

Main Steam Temperature °F 1003 1003 937 937

Cold Reheat Steam Temperature °F 665 665 419 419

Hot Reheat Steam Temperature °F 966 966 731 731

Feed Water Temperature At Eco Inlet °F 461 461 379 379

Feed Water Temperature At Eco Outlet °F 499 499 435 435

Steam Drum Temperature °F 633 633 623 623

amps 61 61 40 40

amps 60 60 41 41

amps 162 162 94 94

amps 160 160 107 107

degrees -1.2 to 16.4 -1.2 to 16.4 9.9 to 25 9.9 to 25

Air Temperature

Air Heater Air In °F 73 73 81 81

Air Heater Air Out °F 492 492 448 448

Mill Temperature °F 165 165 165 165

Ambient Temperature °F 58 58 59 59

Flue Gas - Temperature

Gas to Air Heater °F 612 612 513 513

Gas out from Air Heater °F 264 264 240 240

Wind Box Pressure in WC 3.61 3.61 0.42 0.42

Furnace Pressure in WC -0.26 -0.26 -0.27 -0.27

* GE site visit

Minimum 

Design Case

Maximum 

Design Case

Nominal Full 

Boiler Parameters Load

FD Fan A Power Per Fan 

ID Fan A Power Per Fan

Burner Tilt Position

Nominal Low 

Load

ID Fan B Power Per Fan

FD Fan B Power Per Fan 

The boiler exit O2 concentrations on a wet basis are shown to be 2.64% and 6.13% for the 

188 MWg and 62 MWg load, respectively. GE’s site visit and evaluation have shown that at 

188 MWg and 62 MWg, the boiler exit O2 concentrations are slightly higher than the plant 

report by 0.7% and 1.1% (wet). Thus, the boiler exit O2 concentrations on a wet basis that are 

used in the sorbent system design are 3.34% (wet) and 7.23% (wet) for the 188 MWg and the 

62 MWg load conditions, respectively. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-2 

GE Energy

4.1.2 Boiler Temperature Field 

The furnace sorbent injection (FSI) technology typically delivers sorbent into a temperature 

window of approximately 2,100 to 2,400oF, where sorbent is calcined without deadburning 

and reacts with SO2. The temperature window in this range is typically located between the 

burners and the convective pass. The location of the window also varies with boiler load. The 

optimal temperature window at full load is located at a higher elevation than that at low load. 

To better understand the furnace temperature profile, a series of High Velocity 

Thermocouple (HVT) tests were conducted. The locations of the measurements are shown in 

Figure 4-1. Figure 4-2 through Figure 4-4 show plots of the HVT measurements in Robinson 

Unit 1 for both full load and low load operating conditions conducted on October 10, 2006. 

The data plotted were obtained with the ROFA system in operation. 

Since the optimal temperature window for the sorbent injection only spans between 200-

300oF, the residence time in the window is usually short. The estimated bulk residence time 

in Robinson Unit 1 from the ROFA elevations to the convective pass entrance ranges from 

1.2 to 2 seconds. Good mixing between the sorbent and flue gas within the available 

residence time is critical to achieve high removal rates of SO2. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-3 

GE Energy

Figure 4-1. HVT measurement elevations. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-4 

GE Energy

2000

2100

2200

2300

2400

2500

0 2 4 6 8 10 12

Distance from Wall, ft

Temperature, deg.F

From East Wall

From West Wall

Figure 4-2. HVT measurements for 188 MW load at Elevation 78′. 

1500

1600

1700

1800

1900

2000

0 10 20 30 40

Distance from West Wall, ft

Temperature, deg.F

Figure 4-3. HVT measurements for 188 MW load at Elevation 107′. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-5 

GE Energy

1500

1600

1700

1800

1900

2000

2100

2200

0 10 20 30 40

Distance from West Wall, ft

Temperature, deg.F

Burner Tilts Up 30 degrees

Figure 4-4. HVT measurements for 62 MW load at Elevation 78′. 

4.2 Sorbent Injection Process Design 

An integrated process design methodology, combining several modeling tools, was used to 

evaluate and optimize the performance of the FSI system for Robinson Unit 1. The 

methodology applies thermal and CFD modeling to identify the optimum injection elevation 

at different operational loads. The isothermal (physical model) and CFD modeling tools were 

employed to optimize the mixing performance of the sorbent injection system. A sulfation 

model was then used to predict SO2 capture. Figure 4-5 illustrates the process design 

methodology. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-6 

GE Energy

Boiler

Design/Operating Details

Boiler

Isothermal

Flow Modeling

Isothermal Boiler

Thermal Performance

Modeling/CFD

Boiler

Flow

Field

Flow

Field Temperature

Field Field

Sorbent

Injection &

Mixing

Sorbent

Mixing

Reaction

Modeling

Reaction

Thermal

History

Thermal

History

SO2 Removal

System 

Performance

SO2 Removal

System 

Calcination

Sulfation Sulfation

Experimental

Sorbent 

Characterization

Experimental

Sorbent 

Sorbent

Reactivity

Sorbent

Computational 

Fluid 

Modeling

Computational 

Fluid 

Sorbent Alternatives Sorbent Alternatives

Final Injection 

System Design

Final Injection 

Figure 4-5. Process design methodology. 

4.2.1 Sorbent Injection Requirements and Constraints 

This section describes the design basis for the Robinson Unit 1 sorbent injection system. The 

FSI system was designed for a load range from 62 to 188 MWg with the ROFA system in 

operation. The designed system has to reach a high SO2 capture rate with a minimum impact 

on ESP performance and upper furnace fouling. The FSI system was designed considering 

the following critical parameters: 

• Flue gas temperature at injection elevations, 

• Sorbent type, 

• Sorbent to sulfur stoichiometric ratios, 

• Sulfur content in coal, 

• Injection configurations and locations, and 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-7 

GE Energy

• Sorbent air flow rates. 

Table 4-2 summarizes the design basis for the FSI system. 

TABLE 4-2. FURNACE SORBENT INJECTION DESIGN BASIS 

Parameter Design Basis

Sorbent Type Ca(OH)2

Injection Elevation Between Burners and Convective Pass Entrance

Injection Type Wall Injection

Injection Pressure 10 - 30" WC

Ca/S Ratio 1.0 - 3.5

Burner SR Same as Baseline

ROFA Flow Same as Baseline

Sorbent Air 4% - 6% of Total Combustion Air

The baseline study in this project is based on 188 MWg and 62 MWg load operating 

conditions with the ROFA system in operation. The FSI system was designed to operate 

between the maximum and the minimum design conditions. The operating range is 

summarized in Table 4-3. 

The maximum design case represents the maximum injection air flow rate, sorbent flow rate 

(Ca/S mole ratio of 3.5), and coal sulfur content (1.99 lbSO2/MMBtu) when operating at 188 

MWg. The minimum design case represents the minimum sorbent air flow rate, minimum 

sorbent rate (Ca/S mole ratio 2.0), and nominal coal sulfur content (1.6 lbSO2/MMBtu) when 

operating at 61 MWg. The nominal full load (188 MWg, Ca/S = 2.5, 1.6 lbSO2/MMBtu) and 

nominal low load (61 MWg, Ca/S = 2.5, 1.6 lbSO2/MMBtu) design cases also are listed in 

Table 4-3. The sorbent air for full load operating condition was estimated to be at a 

maximum flow rate of 5.5% of the total combustion air. 

The design approach of the system was to maintain the burner stoichiometric ratio and the 

amount of ROFA flow as they are currently operated prior to the installation of the SO2

injection system. The addition of the sorbent air would result in an increased boiler exit O2. 

The material balance for nominal full load conditions with sorbent injection assumed that 

burner air and ROFA air flow rates are maintained at baseline conditions, resulting in an 

increase in boiler exit gas O2 concentration due to the added sorbent air. Alternatively, in 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-8 

GE Energy

order to avoid significant boiler derating, the ROFA air flow rate could be reduced slightly 

such that the total of ROFA plus sorbent injection air equals the baseline ROFA air flow. 

TABLE 4-3. SORBENT INJECTION SYSTEM OPERATING RANGE 

Parameters

Total Boiler Heat Input MW 188 188 61 61

Sulfur Content lb SO2

/mmBtu 1.99 1.60 1.60 1.60

Ca/S mole ratio - 3.50 2.50 2.50 2.00 

ROFA Flow % Total Comb. Air 25 25 38 38

Sorbent Total Transport Air* % Total Comb. Air 5.5 5 5 4

Main Fuel - Coal Coal Coal Coal

Burner zone Stoichiometry - 0.887 0.887 0.950 0.950

Burnout Zone Stoichiometry - 1.254 1.247 1.623 1.607

Exit Stoichiometry - 1.270 1.263 1.642 1.627

Windbox Pressure in WC 3.61 3.61 0.42 0.42

Furnace Pressure in WC -0.26 -0.26 -0.27 -0.27

Fuel Content

Carbon wt % 68.77 68.77 68.77 68.77

Hydrogen wt % 4.50 4.50 4.50 4.50

Nitrogen wt % 1.70 1.70 1.70 1.70

Sulfur wt % 1.19 0.96 0.96 0.96

Oxygen wt % 4.98 4.98 4.98 4.98

Chlorine wt % 0.08 0.08 0.08 0.08

Ash wt % 12.34 12.34 12.34 12.34

Moisture wt % 6.44 6.67 6.67 6.67

 100.00 100.00 100.00 100.00

Higher Heating Value Btu/lb (wet) 11,976 11,946 11,946 11,946

Btu/lb (dry) 12,800 12,800 12,800 12,800

Steam/Water Flow

Main Steam Production klb/hr 1,382 1,382 469 469

Feed Water Flow klb/hr 1,382 1,382 469 469

Boiler Excess O2 %, wet 4.21 4.13 7.85 7.74

* Percent in addition to the total combustion air

Nominal 

Full Load

Nominal 

Low Load

Minimum 

Design Case

Maximum 

Design Case
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-9 

GE Energy

4.2.2 Computation Fluid Dynamics Studies 

A full-scale three-dimensional CFD computer simulation model was developed for Robinson 

Unit 1. The model mesh was constructed based on the boiler drawings provided by Progress 

Energy. The CFD geometry, shown in Figure 4-6, includes hopper, burner fronts, nose, and 

convective pass, and ends at the economizer entrance. 

A commercial mesh generation tool, ICEMCFD, was used to generate high quality 

hexahedral meshes for both the baseline and the FSI retrofit models. Special attention was 

paid to the grid density near the burners and injectors to resolve the detailed flow structures. 

The mesh size was controlled to allow a reasonable run time for design optimization. The 

mesh size for the baseline model was 550,000 cells and the mesh size for the design model 

was increased to 688,000 cells. 

A commercial software package, FLUENT 6.2, was used to solve the transport equations in 

each cell. The transport equations along with physical models accounting for turbulence, 

combustion, coal devolatilization, and char burnout were solved for coal-firing conditions in 

Robinson Unit 1. The model inputs for CFD studies were based on material balances for the 

baseline and the design operating points. The wall temperatures and exchanger heat duties 

were defined by the thermal model, which ensures that the CFD gas-phase furnace heat 

transfer was properly coupled to the unit steam generation and steam superheating 

characteristics. 

Once the Robinson Unit 1 CFD model was developed and run successfully, it was calibrated 

against field data taken during the period of August 2005 to March 2006. After the baseline 

calibration, the mesh was revised slightly to accommodate the new FSI system. 

Full-scale three-dimensional CFD computer simulations were then performed to evaluate the 

impacts of the FSI system on the furnace gas flow field and CO emissions. The model results 

and analyses along with the isothermal modeling study results helped establish the sorbent 

injector design configuration, front-wall/side-wall flow split ratio, and injector placement 

leading to effective furnace mixing and minimum CO emissions. Through each step of this 

process, the CFD model was compared and validated against the isothermal flow model 

results. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-10 

GE Energy

Burners Packs

ROFA

Convective 

Passes

Figure 4-6. CFD design model geometry. 

4.2.3 Isothermal Model Studies 

An isothermal physical flow model of the Robinson Unit 1 furnace was built to study the 

furnace flow field, evaluate the mixing performance of the FSI system, and validate the CFD 

model prediction. The subscale (1/12) physical flow model was constructed using transparent 

acrylic to allow visualization of the boiler flow field, sorbent jet penetration, and subsequent 

mixing. The model was designed to be an exact geometric replica of the full-scale furnace, 

simulating the flow path from the burners in the furnace through the first few banks of the 

convective pass. A photograph of the model is shown in Figure 4-7. 

To ensure similarity of the flow patterns between model and prototype, the Robinson model 

was scaled geometrically, the burners and ROFA and sorbent injectors were scaled using the 

Thring-Newby method, and the convective pass sections were scaled to match the full-scale 

pressure loss coefficients. The FSI systems were also evaluated using Thring-Newby scaling 

criteria to account for thermal expansion in the boiler. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-11 

GE Energy

Burners

Convective passes

ROFA

Figure 4-7. Lab scale isothermal physical flow model of Robinson Unit 1. 

Several visualization and measurement techniques were used to characterize the furnace flow 

field and evaluate the mixing performance of various FSI injection configurations. Velocity 

profiles measured at the overfire air and nose elevations were used to guide sorbent injector 

placement and jet penetration. Smoke and bubble tracers were injected through one or more 

burners to visualize the flow patterns and characterize the flow field inside the furnace. 

Mixing performance, based on jet penetration and flow coverage, was examined using smoke 

visualization. Dispersion measurements of tracer concentration were conducted to quantify 

the flow distribution in the upper furnace. To take dispersion measurements, a gas tracer was 

added to the air stream feeding the sorbent injectors. Point measurements of the tracer 

concentration then were made across a grid at the nose and ROFA planes. The variation in 

tracer concentration over each measurement plane was evaluated using the Coefficient of 

Variation (COV), which is the standard deviation of the concentration measurements divided 

by the mean concentration. In general, low COVs reflect good mixing performance: the 

closer the COV is to zero, the more uniformly the jet fluid is dispersed. All of these 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-12 

GE Energy

measurements were used in conjunction with CFD results to define the process and hardware 

design specifications. 

4.2.4 Thermal Model Studies 

Furnace heat transfer and boiler performance models were developed to investigate the 

impacts of the FSI system on Robinson Unit 1 thermal performance. These models, which 

close the heat balance between the steam and gas sides of the boiler, were calibrated using 

field data supplied by Progress Energy. The calibrated model was used to simulate boiler 

operation with the retrofitted FSI system and develop operating scenarios that minimize the 

impact of the FSI system on boiler thermal performance. The heat transfer analysis focused 

on determining the furnace gas temperature profile and exchanger heat duties, and 

identifying any factors associated with FSI system that may prevent the boiler from operating 

at full-load conditions within the current operational design limits (e.g., steam temperatures 

and attemperation flow rates). 

The thermal analysis was performed with a two-dimensional furnace heat transfer and 

combustion (2DHT) model (as shown in Figure 4-8) applied in conjunction with a 

one-dimensional steam path and boiler performance model. First, the furnace heat transfer 

code was used to predict the flue gas temperature profile and heat absorption to the furnace 

waterwall and upper furnace radiant exchangers. A converged solution of the furnace heat 

transfer code yielded heat transfer parameters required to evaluate overall boiler 

performance, such as furnace wall and radiant exchanger heat absorption and economizer 

exit gas temperature. These values were subsequently used in the boiler performance code to 

predict steam-side performance parameters (e.g. attemperation flow rates and water/steam 

temperatures). The models provided an estimate of the impacts that sorbent injection has on 

the furnace flue gas temperature profile and boiler steam-side performance. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-13 

GE Energy

23

SCR Tubes

RH

Platen SH

24

25

ROFA

ROFA

11

12

Burner

Pack

}

Burner

Pack

{

ROFA

Burner

Pack

10

13

14

15

16

17

18

19

20

21

22

23

24

25 26 2728

9

8

7

6

5

4

3 

2 

1

11

12

10

13

14

15

16

17

18

19

20

9

8

7

6

5

4

3 

2 

1

21

22

26

27

28

23

SCR Tubes

RH

Platen SH

24

25

ROFA

ROFA

11

12

Burner

Pack

}

Burner

Pack

{

ROFA

Burner

Pack

10

13

14

15

16

17

18

19

20

21

22

23

24

25 26 2728

9

8

7

6

5

4

3 

2 

1

11

12

10

13

14

15

16

17

18

19

20

9

8

7

6

5

4

3 

2 

1

21

22

26

27

28

Furnace Division into Layers Model Configuration

Figure 4-8. Schematic of Robinson Unit 1 thermal model. 

4.2.5 Sulfation Model Studies 

Sulfation of alkaline sorbents, such as limestone (calcium carbonate, CaCO3), and lime 

(calcium hydroxide, Ca(OH)2), is the end result of a series of physical and chemical 

processes. When a sorbent is injected into a hot environment, it calcines to form calcium 

oxide (CaO) by either of the reactions: 

CaCO3 = CaO + CO2,

Ca(OH)2 = CaO + H2O. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-14 

GE Energy

Before SO2 can react with CaO it must first diffuse from the surrounding gas to the particle 

surface, diffuse through the porous CaO structure, and diffuse through a product layer of 

CaSO4. Then, the SO2 reacts according to the first order reaction: 

CaO + SO2 + 1⁄2 O2 = CaSO4. 

Calcium sulfate, CaSO4, has greater molar volume than CaO, results in a product layer that 

fills the calcine pore structure as the reaction proceeds. As a consequence, the pore structure 

can become plugged and sorbent utilization rate can be reduced. 

GE developed a sulfation model that takes into account of sorbent mixing characteristic and 

local flue gas quench rates. The sorbent mixing characteristics were obtained from the 

isothermal modeling of tracer concentration measurements. The quench rates and the 

injection temperature were predicted from thermal analysis. The sulfation model was applied 

to predict the sulfur capture for the proposed system. 

4.3 Sorbent Characterization 

Sorbent utilization varies among different sorbent types, as illustrated in Figure 4-9 for three 

different pressure hydrated limes and limestone considered for the Robinson project. The 

experimental results were obtained from GE’s Boiler Simulator Facility (BSF). SO2 captured 

by the hydrated limes is markedly higher than by the limestone. Performance varies for 

products from different commercial sources. The Chemical Lime product demonstrated the 

highest sorbent utilization in these tests. 

The hydrated lime used in this study is estimated to have a purity of 95%. The sorbent 

particle size distribution is listed in Table 4-4. Figure 4-9 shows that as Ca/S increases, the 

SO2 capture also increases. The pilot-scale results show that the SO2 capture objective (40% 

to 50% SO2 capture) can be achieved with a Ca/S between approximately 2.0 to 3.5. 

Flue gas SO2 concentration will also affect the sulfation process by influencing the rates of 

external mass transfer, pore diffusion, product layer diffusion and chemical reaction. The 

SO2 concentrations evaluated for this design are 1.99 lb/MMBtu and 1.6 lb/MMBtu for the 

maximum and nominal cases, respectively. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-15 

GE Energy

0

10

20

30

40

50

60

70

80

0 1 2 3 4

Ca/S

SO2 Capture, %

Chem Lime, CaCO3

Carmeuse, Ca(OH)2

Chem Lime, Ca(OH)2

Mississippi, Ca(OH)2

Figure 4-9. Comparison of SO2 capture for four different sorbents in the BSF. 

Optimum sorbent reaction with SO2 occurs in a limited temperature window (2,100 to 

2,400oF), thus it is important for sorbent to be injected to the furnace at the elevation where 

the sulfation temperature window lies. The furnace temperature profile is predicted from 

thermal and CFD analysis, which were validated against the HVT data provided by Progress 

Energy. 

TABLE 4-4. SORBENT PARTICLE SIZE DISTRIBUTION 

Particle Size Weight Fraction

(micron)

0.800 0.050

1.500 0.100

2.100 0.125

2.800 0.150

3.700 0.200

4.600 0.150

5.500 0.100

6.500 0.075

7.700 0.040

9.500 0.010
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-16 

GE Energy

4.4 Process Design of FSI Injection System 

4.4.1 Baseline Study 

This section describes the study findings of the baseline operation conditions. The furnace 

flow field was established with the aid of CFD and isothermal modeling. Figure 4-10 shows 

the isothermal (top) and CFD (bottom) results of the vertical component velocity profiles at 

the nose plane elevation at 188 MWg. Both profiles show a high velocity gradient around the 

front wall region and low velocity gradient around the left corner of the boiler rear wall 

region. Such an unevenly distributed flow pattern would have a major effect on sorbent 

injector performance. 

Figure 4-11 shows an upper furnace flow field of the 188 MWg by tracing path lines released 

from the top burner row colored by temperature. The flow field is typical of the T-fired 

boilers with a rotating flow moving upward. The flow field shows an acceleration of the flow 

leaving the furnace due to the area contraction at nose elevation. The flow field within the 

ROFA elevation region is highly complex. The flow from the ROFA jets dominates the 

upper furnace flow field to create high velocity vortex, angular flow near the wall and slow 

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.10

2.20

2.30

2.40

2.50

Isothermal 

model

CFD

Figure 4-10. Vertical velocity profiles at the nose plane elevation of 188 MWg load. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-17 

GE Energy

vertical flow in the center. The CFD result also shows strong tangential flow concentration at 

rear and division wall corners. 

At low load (62 MWg), the ROFA flow distribution is different from the full load condition 

(188 MWg). Figure 4-12 shows an upward velocity profile of 62 MWg load at 87'-2" 

elevation plane. 

Figure 4-11. Robinson Unit 1 upper furnace flow field at 188 MWg load. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-18 

GE Energy

At Elevation 87'-2", the vertical velocity profile indicates strong vortex in the counterclockwise direction. Strong tangential flows concentrate along the front wall and the rear 

wall, and around the center of the boiler half. The high velocity gradient results from the high 

ROFA velocity head. Similar to the full load condition, the flow field within the ROFA 

elevation region for low load is highly complex. The flow from ROFA jets dominates the 

upper furnace flow field to create a high velocity vortex. 

4.4.2 Injection Elevation Selection 

Once the flow field is mapped, the injection elevation can be identified. The flue gas 

temperature profile through the boiler furnace is one of the most important considerations for 

identifying the optimum sorbent injection elevation. 

The computer simulations provide the average gas temperature profiles for the full load and 

low load operation conditions (See Figure 4-13 and Figure 4-14). Considering accessibility 

of locations for injectors on the boiler (Figure 4-15), the optimal injection elevations are 87'-

2" and 77'-0" for full load and low load operating conditions, respectively. 

Figure 4-12. Upward velocity profile of 62 MWg load at 87'-2". 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-19 

GE Energy

2000

2100

2200

2300

2400

2500

2600

2700

2800

50 60 70 80 90 100 110

Elevation, ft

Average Gas Temperature, oF

Optimum 

Injection 

Temperature

ROFA

Injection 

Temperature

Window

Figure 4-13. Average gas temperature profile at a nominal full load injection elevation. 

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

50 60 70 80 90 100 110

Elevation, ft

Average Gas Temperature, oF

Optimum 

Injection 

Temperature

ROFA

Injection 

Temperature

Window

Figure 4-14. Average gas temperature profile at a nominal low load injection elevation.
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-20 

GE Energy Figure 4-15. Robinson front wall injection accessibility.
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-21 

GE Energy

4.4.3 Injection Configuration Selection 

Preliminary jet calculations were performed to estimate an appropriate injector diameter. 

Then, CFD and isothermal model results were employed to evaluate mixing performance of 

the injection system. Finally, sulfation analysis was applied to predict the SO2 removal with 

the optimal configuration. 

Using empirical jet entrainment and jet trajectory models, the initial number of injectors, 

injector diameters, and injection velocity head can be identified. Previous experience shows 

that 200-300 ms of mixing time is typically required to achieve good mixing. Figure 4-16 

shows mixing time as a function of sorbent air for various jet diameter sizes using 12 jets at a 

full load operation condition. For the sorbent air of 3-7% of total combustion air, the jet 

diameter is required to be in a range of 4 to 6 inches in diameter in order to provide a good 

mixing at reasonable pressure requirement (less than 40" WC). 

The jet injection studies in the isothermal model were designed to evaluate the mixing and 

dispersion characteristics of jets in a simulated boiler flow field. First, screening studies were 

carried out by introducing smoke into the jet fluid. This allowed visual observations of how 

the jets mixed and dispersed within the furnace flow. Selected test cases, which showed good 

visual dispersion of the jets, were studied in detail by making gas tracer measurements at a 

10

100

1000

10000

2 3 4 5 6 7 8

Sorbent Air, % Total Combustion Air

Mixing Time, ms

7 inch

6 inch

5 inch

4 inch

3 inch

Good Mixing 

Region

Figure 4-16. Mixing time as a function of sorbent air for various jet diameter sizes. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-22 

GE Energy

downstream location from the injection point in the model. This involved introducing a small 

amount of CO2 into the jet fluid and taking measurements of the tracer concentrations over a 

grid plane downstream of injection locations. This facilitated comparisons of the dispersion 

patterns from the smoke traces and concentration measurements. The distributions of the 

normalized tracer concentrations were also used later to predict the sulfur capture potential 

for any specific injection configurations. 

Preliminary Location: Smoke Screening

A sample of smoke screening is shown in Figure 4-17. This is a smoke sketch of 12-double 

simple jets with LFW-RFW-SW configuration. With evenly distributed air through each port, 

the left-front-wall ports penetrate toward center along the front wall of the furnace. The rightfront-wall ports and the sidewall ports combine to over-penetrate the left corner along the 

rear wall of the boiler. This configuration results in excessive amount of sorbent at the left 

rear corner and a lack of coverage on the right front corner of the furnace. Figure 4-18, 

however, shows that the 12-double simple jet with LFW-RFW-SW configuration provides 

better mixing. With evenly distributed air though each port, the left-front-wall ports penetrate 

toward center along the front wall of the furnace. The right-front-wall ports provide the 

coverage to the front right corner. The sidewall ports effectively penetrate the left corner 

along the rear wall of the boiler. This configuration results in better mixing at nose plane 

elevation. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-23 

GE Energy

Figure 4-17. Smoke sketch of 12-double simple jet with LFW-RFW-SW configuration. 

Figure 4-18. Smoke sketch of 12-double simple jet with LFW-CFW-SW configuration. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-24 

GE Energy

Quantitative Analysis: Trace Injection Mixing Performance

Dispersion measurements made for the test conditions are presented as isopleths of tracer 

concentration normalized against the well-mixed tracer concentration. The smaller the 

deviation of this ratio from 1.0, the more uniformly the tracer is dispersed. A measurement of 

the non-uniformity of the tracer concentration over the measurement plane is the coefficient 

of variation (COV), which is the standard deviation of the concentration measurements 

divided by the mean concentration. This has been calculated for the dispersion profile and is 

a measure of the degree of well-mixedness produced by the injection system. In general, 

good mixing is indicated by low COV’s. The closer the COV is to zero, the more uniformly 

the jet fluid is dispersed. 

Comparison of Single Simple Jet and Double Simple Jet Configurations: 

Figure 4-19 shows dispersion profiles at a nose plane of single simple jet (top) and double 

simple jet (bottom) configuration. The single simple jet configuration consists of 6 simple 

jets at Elevation 87'-2", three jets on each side of the boiler. Figure 4-19 shows study of a 

half furnace. The double simple jet configuration consists of 12 simple jets at the same 

elevation, six jets on each side of the boiler. At each injection location, 2 injectors are located 

staggered on top of the other. The COV for the single simple jet and the double simple jet 

configurations are 36% and 30%, respectively, as shown in Figure 4-19. Therefore, it is 

concluded that the double simple jet configuration provides better mixing than the simple 

single jet configuration. 

Comparison of Jet Locations: 

Figure 4-20 shows dispersion profiles of various injection locations at the full load operating 

condition. All of the profiles were tested at 5% sorbent air, 25% ROFA with 12-double 

simple jets. Figure 4-20c shows a configuration with the best mixing performance (COV = 

27%) while Figure 4-20d shows a configuration with the worst mixing performance (COV = 

45%). The only difference between the two profiles is that the configuration in Figure 4-20c 

has left and center front wall injectors while the configuration in Figure 4-20d has center and 

right front wall injectors. The previous velocity profile study reveals that the high velocity 

flue gas flow around the right front wall greatly impacts the sorbent dispersion 

characteristics. Because of the high flue gas flow rate around the left front wall, the jets have 

difficulty penetrating into the boiler and because of the strong counter-clockwise vortex, the 

injected sorbent was swept to the right rear wall of the boiler (Figure 4-20d). 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-25 

GE Energy

Single Simple Jets

Double Simple Jets

COV = 36%

COV = 30%

Figure 4-19. Dispersion profiles at nose plane. 

COV = 30% COV = 35% COV = 27%

COV = 45% COV = 32%

(a) LFW-RFW-SW (b) LFW-CFW-RFW (c) LFW-CFW-SW

(d) CFW-RFW-SW (e) 2LFW-SW

Figure 4-20. Dispersion profiles at nose plane of various location injection systems. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-26 

GE Energy

Other injection configurations such as shown in Figure 4-20a b, and d provide acceptable 

mixing performance but not as good as that shown in Figure 4-20c. Therefore, the 

configuration in Figure 4-20c was selected for the FSI system. 

Sorbent Air Flow: 

The amount of sorbent air required to achieve good mixing in previous FSI applications was 

typically 3% to 7% of total combustion air. The quantitative analysis shows that the amount 

of sorbent air at 7%, 5%, and 3% of total combustion air will provide COV of 20%, 24%, and 

46%, respectively, at a nose plane measurement (Figure 4-21) for full load conditions. While 

the 7% sorbent air has a COV of 4% better than the 5% sorbent air case, sulfation analysis 

shows that both conditions provide similar predicted SO2 capture. Since smaller amount of 

sorbent air requires less injection fan power and has smaller impact on ID fan limitation, 5% 

sorbent air flow was selected for design specification. 

7% Transport Air

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

5% Transport Air

3% Transport Air

COV = 20%

COV = 24%

COV = 46%

Figure 4-21. Dispersion profiles at nose plane of various sorbent air flow rates. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-27 

GE Energy

ROFA Flow Effect: 

Because of the uncertainty in the amount of ROFA flow, mixing was evaluated over a range 

of ROFA flow rates. Figure 4-22 shows study results for ROFA flow of 15% to 25% of total 

combustion air at full load operation. While the COVs for each case (24%, 42%, and 33% for 

the 25%, 20% and 15% ROFA, respectively) are different, sulfation results show that the 

predicted SO2 capture is similar for all three cases. 

25% ROFA

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

20% ROFA

15% ROFA

COV = 24%

COV = 42%

COV = 33%

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Figure 4-22. Dispersion profiles at nose plane of various ROFA flow rates. 

Front Wall/Side Wall Flow Split: 

Additional studies to evaluate unequal flow distribution to the injectors were also performed. 

Figure 4-23 shows dispersion profiles at evenly distributed flow and 60/40 front 

wall/sidewall (FW/SW) split distribution for the 5%-sorbent air, 25%-ROFA, and RFWCFW-SW configuration. Although the 60/40 FW/SW split may provide slightly better SO2

capture, the added complexity of the sorbent injection system (i.e., multiple feeders and 

transport systems) probably would not be justified. Sulfation analysis for these cases predicts 

only small differences in SO2 capture. Therefore, evenly distributed flow is preferred 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-28 

GE Energy

considered optimum for SO2 capture commensurate with ease of operation and low capital 

and maintenance cost. 

Evenly 

Distributed Flow

60/40 

FW/SW Split

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

COV = 24%

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00

2.00

4.00

6.00

8.00

10.00

12.00

COV = 27%

Figure 4-23. Dispersion profiles. 

4.5 FSI Impact on Boiler Thermal Performance 

The boiler thermal models were calibrated against the HVT test data to ensure they properly 

simulated boiler performance. Field data that were matched in the model during calibration 

include the exit flue gas temperature and O2, the steam generation rate and temperature, and 

heat duties for each of the major heat transfer components. The parameters adjusted during 

the model calibration were waterwall and heat exchanger fouling characteristics, the 

convective heat transfer coefficients, char reactivity, and the fuel flow rate. 

4.5.1 Coal Firing at 188 MWg 

HVT sequence 8 data were used to calibrate the models at the full load (188 MWg) 

condition. Table 4-5 summarizes the predicted overall boiler performance with 20% ROFA 

and 1.96% flue gas O2 (wet). The table compares the results obtained for the calibration case 

with available field data. In general, the predicted steam- and gas-side performance 

parameters agree well with field data, confirming the model calibration at the full load 

baseline. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-29 

GE Energy

The calibrated full load baseline was then scaled to the 2.64% flue gas O2 (wet), which is 

specified as the full load operating condition in the project Design Basis Memorandum [1]. 

The scaled baseline was used as the basis when evaluating the impacts of the sorbent air 

injection. The sorbent air was injected at the elevation of 87′-2′′. The percentage of the 

sorbent air was fixed at 5%. For the sorbent injection case, the fuel flow rate was slightly 

adjusted (1% increase) to match the baseline main steam flow rate and/or temperature. Table 

4-6 lists the scaled baseline performance and the simulation results for the sorbent injection 

case. Figure 4-24 plots the mean gas temperature profile predicted by the furnace heat 

transfer code (2DHT) for the furnace zones. 

It can be found that the injection of sorbent air slightly changes the furnace temperature 

profile. The gas temperature at the injection elevation becomes lower. The flue gas 

temperature at the economizer exit increases from 612oF (scaled baseline) to 621oF. 

Generally, the waterwall heat absorption decreases, while the convective backpass heat 

absorption increases. The change of the heat duties in the boiler impacts the steam side 

performance. In order to maintain the main steam flow rate, the fuel consumption needs to be 

increased by 1%. On the other hand, the main steam temperature becomes 10oF higher than 

that of the scaled baseline case. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-30 

GE Energy

TABLE 4-5. BASELINE PERFORMANCE PREDICTIONS AT FULL LOAD 

188 MW 188 MW

Sequence 8 Baseline Model

20% ROFA 20% ROFA

9-Oct-06 Data 1.96% O2

 wet

Flue Gas O2 (% wet) 2.0 2.0

Fuel Flow Rate (klb/hr) 154.1

Sorbent Carrier Air Flow Rate (klb/hr) n/a n/a

Flue gas Temperature (oF) Leaving

77 ft Mean Temperature 2,392 2,405

Backpass Inlet 1,470

Economizer 605 606

Air Heater 285 285

Flow Rates (klb/hr)

Feedwater 1407 1407

Main Steam 1407 1407

Reheat Steam* 1266 1266

Attemperation flow (klb/hr)

SH Att. 0.0 0.0

RH Att. 0.0 0.0

Water/Steam Temperatures (oF)

Economizer In 458 458

Economizer Out 498 498

Waterwall Out 634 634

Primary SH Out 833

Platen SH Out 972 973

RH In 665 665

RH Out 969 971

Heat Absorption (kW)

Economizer 18,673 18,654

Waterwall 270,011 269,968

PSH + Platen SH 132,685 132,897

RH 62,224 62,670

Total Heat Absorption (kW) 483,593 484,189

* Assumed to be 90% of the steam flow rate
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-31 

GE Energy

TABLE 4-6. SORBENT INJECTION PERFORMANCE PREDICTIONS 

AT FULL LOAD 

188 MW 188 MW

Scaled Baseline ROFA Sorbent Injection

20% ROFA 20% ROFA + 5% FSI Air

2.64% O2 wet 3.46% O2 wet

Flue Gas O2 (% wet) 2.6 3.5

Fuel Flow Rate (klb/hr) 154.1 155.6

Sorbent Carrier Air Flow Rate (klb/hr) n/a 86.6

Flue gas Temperature (oF) Leaving

77 ft Mean Temperature 2,419 2,393

Backpass Inlet 1,473 1,475

Economizer 612 621

Air Heater 288 293

Flow Rates (klb/hr)

Feedwater 1408 1407

Main Steam 1408 1407

Reheat Steam* 1267 1266

Attemperation flow (klb/hr)

SH Att. 0.0 0.0

RH Att. 0.0 0.0

Water/Steam Temperatures (oF)

Economizer In 458 458

Economizer Out 500 504

Waterwall Out 634 634

Primary SH Out 842 856

Platen SH Out 987 997

RH In 665 665

RH Out 975 975

Heat Absorption (kW)

Economizer 19,656 21,207

Waterwall 269,274 267,494

PSH + Platen SH 136,649 139,209

RH 63,373 63,404

Total Heat Absorption (kW) 488,953 491,314

* Assumed to be 90% of the steam flow rate
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-32 

GE Energy

1,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

2,800

0 25 50 75 100 125 150 Furnace Elevation, ft

Mean Gas Temperature, 

o

F

Scaled Full Load Baseline, 2.64% O2, 20% ROFA

Sorbent Injection, 3.46% O2, 20% ROFA + 5% Transport 

Air

Burner Rows

ROFAROFA

ROFA+Sorbent

ROFA

Figure 4-24. Predicted bulk furnace gas temperature at full load. 

4.5.2 Coal Firing at 61 MWg 

The models were calibrated for the low load (61 MWg) condition using HVT sequence 5 

data. Table 4-7 summarizes the overall boiler performance predicted at low load with 29% 

ROFA and 5.9% flue gas O2 (wet). The table compares the results obtained for the 

calibration case with the sequence 5 data. In general, the predicted steam- and gas-side 

performance parameters agree well with field data, confirming the baseline calibration at the 

low load baseline. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-33 

GE Energy

The calibrated low load model was then used to simulate the sorbent air injection at the 

elevation of 77′. The percentage of the sorbent air was 5%. In this case, the fuel flow rate was 

slightly increased by 0.6% to avoid boiler derate. Table 4-7 lists the modeling results for the 

sorbent injection at low load. Figure 4-25 plots the predicted mean gas temperature profile in 

the furnace zones. 

The injection of the sorbent air at low load generally impacts the boiler performance in the 

similar trend as it does at full load. The gas temperature at the injection elevation becomes 

lower than the baseline value (86oF lower at 77′ elevation). The flue gas temperature at the 

economizer exit increases to 520oF, which is 7oF higher than the baseline value. The 

waterwall heat absorption decreases, while the convective backpass heat absorption generally 

increases. The change of the boiler heat duties requires a slight adjustment of the fuel flow 

rate to match the baseline main steam flow at low load. However, the predicted main steam 

temperature change is very slight (1oF). The overall boiler performance at low load is not 

significantly impacted by the injection of the sorbent air. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-34 

GE Energy

TABLE 4-7. BASELINE AND SORBENT INJECTION PERFORMANCE 

PREDICTIONS AT LOW LOAD 

61 MW 61 MW 61 MW

Sequence 5 Baseline Model Sorbent Injection

29% ROFA 29% ROFA 29% ROFA + 5% FSI Air

9-Oct-06 Data 5.9% O2

 wet 6.9% O2 wet

Flue Gas O2 (% wet) 5.9 5.9 6.9

Fuel Flow Rate (klb/hr) 52.5 52.9

Sorbent Carrier Air Flow Rate (klb/hr) n/a n/a 37.2

Flue gas Temperature (o

F) Leaving

77 ft Mean Temperature 1,891 1,928 1,842

Backpass Inlet 981 974

Economizer 511 513 520

Air Heater 253 254 258

Flow Rates (klb/hr)

Feedwater 492 494 494

Main Steam 492 494 494

Reheat Steam* 443 444 445

Attemperation flow (klb/hr)

SH Att. 0.0 0.0 0.0

RH Att. 0.0 0.0 0.0

Water/Steam Temperatures (o

F)

Economizer In 370 370 370

Economizer Out 431 430 434

Waterwall Out 624 624 624

Primary SH Out 693 695

Platen SH Out 826 826 827

RH In 427 427 427

RH Out 768 766 765

Heat Absorption (kW)

Economizer 9,061 9,075 9,765

Waterwall 106,665 107,086 106,431

PSH + Platen SH 31,097 31,150 31,273

RH 23,465 23,447 23,379

Total Heat Absorption (kW) 170,288 170,758 170,848

* Assumed to be 90% of the steam flow rate
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-35 

GE Energy

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

0 25 50 75 100 125 150 Furnace Elevation, ft

Mean Gas Temperature, 

o

F

Low Load Baseline, 5.9% O2, 29% ROFA

Sorbent Injection, 6.9% O2, 29% ROFA + 5% Transport 

Air

Burner RowsLower Two OOSROFA+Sorbent

ROFAROFAROFA

Figure 4-25. Predicted bulk furnace gas temperature at low load. 

4.6 Sulfur Capture 

Results of extensive studies, including measurements on the boiler at Robinson Unit 1, 

isothermal modeling, CFD modeling, and heat transfer computational modeling, were 

presented in previous sections. This information provides a basis for the prediction of SO2

capture expected in the Robinson Unit 1 furnace. The prediction of SO2 removal potential 

requires a combination of all of the engineering tools used to specify the injection system 

design. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-36 

GE Energy

In the evaluation of the impact of dispersion upon SO2 capture, a simple methodology is 

employed which is based upon dispersion profiles obtained in the isothermal flow model. In 

this approach, the boiler cross-section is divided into a grid system, and sorbent dispersion 

profiles are used to identify local variation in Ca/S ratio. These may then be translated into 

local SO2 capture, normalized by the local velocity, and then integrated across the flow to 

yield total SO2 capture. The empirical method was used to predict amount of SO2 capture. 

The prediction of SO2 capture at full load as a function of Ca/S ratio is shown in Figure 4-26. 

About 40 to 50 percent of SO2 reduction at Ca/S of 2.5 is predicted. 

0

10

20

30

40

50

60

1 1.5 2 2.5 3 3.5 4

Ca/S

SO2 Capture, %

Figure 4-26. SO2 Capture as a function of Ca/S at full load operation. 

4.7 Design Specification 

The process design specifications for nominal full load conditions (188 MWg) and nominal 

low load conditions (61 MWg) derived from the studies are described in this section. 

The maximum design case represents the maximum sorbent injection air flow rate, maximum 

sorbent injection rate (Ca/S mole ratio of 3.5), and maximum coal sulfur content (1.99 

lbSO2/mmBtu) when operating at 188 MW (Gross). The minimum design case represents the 

minimum sorbent injection air flow rate, minimum sorbent rate (Ca/S mole ratio 2.0), 

minimum coal sulfur content (1.6 lbSO2/mmBtu) when operating at 61 MW (Gross). The 

nominal full load (188 MW gross, Ca/S = 2.5, 1.6 lbSO2/mmBtu) and nominal low load (61 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-37 

GE Energy

MW gross, Ca/S = 2.5, 1.6 lbSO2/mmBtu) design cases also are listed in Table 1. Additional 

information used in developing this process design specification can be found in the Progress 

Energy Robinson Unit 1 Furnace Sorbent Injection Project Design Basis Memorandum Rev 

1.0 [1]. 

The FSI injection system consists of 12 injection boxes. Six injection boxes are located at 

Elevation 87′-2′′ (±6′′) and the other six are located at Elevation 77′-0′′ (±6′′), as shown in 

Figure 4-27 and Figure 4-28. At each injection elevation, two injection boxes are located on 

the sidewalls and four boxes on the front wall. The plan views of the injection locations at the 

Elevation 87′-2′′ (±6′′) and 77′-0′′ (±6′′) are shown in Figure 4-29 and Figure 4-30, 

respectively. Each injection box contains two round coaxial injectors, as conceptually shown 

in Figure 4-31. The nozzle diameter for all injectors is 4.026′′ (4-inch Sch 40 pipe). At full 

load, all of the jets at the upper elevation are fully in use and the flow rate of the lower 

elevation injectors will be reduced to cooling air flow rate. At low load, the air flow rate 

through the lower injectors of each injection box at the lower elevation will be in full use and 

the air flow rate through the rest of the injectors will be reduced to cooling air flow rate. The 

lower injectors on each injection box at the lower elevation will be sized to provide an 

alternative flow injection for full load. 

The sorbent will be transported in a dense phase and injection air will be added at the injector 

to enhance mixing. The sorbent injectors are designed to allow 5±0.5% of total air for 

injection (sum of transport and injection air) at full load. Additional cooling air is required 

and should be taken into consideration when sizing equipment. Both nominal full load and 

nominal low load operating points are at 5% of total air. The minimum design condition 

requires 4% of total air. The design specifications of the sorbent injectors are summarized in 

Table 4-8. This injector design specification is for the overall transport sorbent injection, i.e. 

including sorbent, transport air, and injection air. The process flow diagram (PFD) for this 

system is shown in Figure 4-32. The material balances for various design conditions are 

shown in Table 4-9 to Table 4-12. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-38 

GE Energy

ROFA

El. 87'-2"

El. 77'-0"

Front Wall Sorbent Injector

Buckstay

4' 4'

4' 4'

8'-9" 8'-9"

10'-6 5/8" 10'-6 5/8"

Figure 4-27. Front view of the sorbent injector locations. 

Rear WallFront Wall

El. 87'-2"

El. 77'-0"

Left Wall

Front Wall

Rear Wall

Right Wall

ROFA

Sorbent Injector

6'

9'-4 1⁄2" 

6'

9'-4 1⁄2" 

9'-4" 9'-4" 

Buckstay

Figure 4-28. Side view of the sorbent injector locations. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-39 

GE Energy

Front Wall

10'-6 5/8"±6"

4'±6" 4'±6"

6'-0"±6"

Division Wall

10'-6 5/8"±6" 10'-6 5/8 "±6"

6'-0"±6"

10'-6 5/8"±6"

Figure 4-29. Plan view of sorbent injector locations at the Elevation 87′-2′′ (± 6′′). 

Front Wall

12'-4 7/8 "±6"

4'±6" 4'±6"

9'-4"±6"

Division Wall

8'-9 "±6" 8'-9 "±6"

9'-4"±6"

12'-4 7/8 "±6"

Figure 4-30. Plan view of sorbent injector locations at the Elevation 77′-0′′ (± 6′′). 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-40 

GE Energy

10.026 in

Sorbent and 

Transport Air

Boost Air

4.026 in

Figure 4-31. Conceptual design of an injection box. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-41 

GE Energy

TABLE 4-8. SORBENT INJECTION SYSTEM DESIGN SPECIFICATION 

Parameters

Sorbent Air Design Capacity % 5.5 5 5 4

Sulfur Content lb SO2

/mmBtu 1.99 1.60 1.60 1.60

molar ratio 3.5 2.5 2.5 2.0

Boiler Excess O2 %, wet 4.21 4.13 7.85 7.74

Front Wall Injector

Sorbent Mass Flow Split % 66.67 66.67 66.67 66.67

Air Mass Flow Split % 66.67 66.67 66.67 66.67

Sorbent Flow Rate lb/hr 10,417 6,012 2,048 1,638

Sorbent Air Flow Rate lb/hr, wet 63,286 57,584 25,507 20,405

Number of Jets - 8 8 4 4

Injection Elevation1

- 87'-2" 87'-2" 77'-0" 77'-0"

Jet Inside Diameter2

inch 4.026 4.026 4.026 4.026

Injection Temperature oF 58 ± 30 58 ± 30 58 ± 30 58 ± 30

Velocity Head in WC 28.0 ± 1.6 22 ± 1.4 16.9 ± 1.0 10.8 ± 0.7

Injection Velocity ft/s 330 ± 18 295 ± 18 261 ± 16 209 ± 13

Side Wall Injector

Sorbent Flow Split % 33.33 33.33 33.33 33.33

Air Mass Flow Split % 33.33 33.33 33.33 33.33

Sorbent Flow Rate lb/hr 5,209 3,006 1,024 819

Sorbent Air Flow Rate lb/hr, wet 31,643 28,792 12,753 10,203

Number of Jets - 4 4 2 2

Injection Elevation1

- 87'-2" 87'-2" 77'-0" 77'-0"

Jet Inside Diameter2

inch 4.026 4.026 4.026 4.026

Injection Temperature oF 58 ± 30 58 ± 30 58 ± 30 58 ± 30

Velocity Head in WC 28.0 ± 1.6 22 ± 1.4 16.9 ± 1.0 10.8 ± 0.7

Injection Velocity ft/s 330 ± 18 295 ± 18 261 ± 16 209 ± 13

Minimum 

Design Case

Nominal Full 

Load

Maximum 

Design Case

Ca/S

Nominal Low 

Load
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-42 

GE Energy Figure 4-32. Process flow diagram for Robinson Unit 1.
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-43 

GE Energy

TABLE 4-9. MATERIAL BALANCE FOR MAXIMUM OPERATION AT 5.5% 

SORBENT AIR 

1 Coal 154,217

2 Inlet Air 1,873,757 58

3 APH Leakage 170,342 58

4 Combustion Air 1,392,952 492 3.61

5 Primary Combustion Air 310,463 492

6 ROFA 431,493 492

7 Secondary Burner Air 961,459 492

8 PA/Coal 464,680 165

9 Casing Leakage 22,558 58

10 Sorbent 15,626

11 Transport Air 3,146 58

12 Sorbent/Air 15,626 3,146 58

13 Boost Air 91,783 58 28.01

14 Flue Gas at Economizer Outlet 28,581 1,957,406 612

15 Bottom Ash 3,806

16 Economizer Ash 952

17 Duct Humidication Inlet Gas 28,581 2,127,748

18 Duct Humidication Outlet Gas 28,581 2,131,924 41,760

19 Humidication Inlet Water 41,760

20 Compressed Air 4,176

21 Fly Ash 28,581

22 Stack Gas 2,131,924 41,760

23 Feed Water 1,382,000 461

24 Superheat Steam Out 1,382,000 1003

25 Reheat In 1,243,800 665

26 Reheat Out 1,243,800 966

Assumptions:

Wet Basis: Humidity = 0.00658 lb H2O/lb Dry Air

Load: 188 MW, Gross; HHV = 12,800 lb/hr (dry)

95% Sorbent Purity

Ca/S = 3.5; 1.99 lbSO2/mmBtu

SR1 = 0.89, SRT = 1.27

Exit O2%, wet = 4.21%

Stream Description Stream 

No.

Temperature 

°F

Pressure 

Solid Gas Water in WC

Flow Rate (lb/hr)
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-44 

GE Energy

TABLE 4-10. MATERIAL BALANCE FOR NOMINAL FULL LOAD OPERATION AT 

5% SORBENT AIR 

1 Coal 154,603

2 Inlet Air 1,875,295 58

3 APH Leakage 170,481 58

4 Combustion Air 1,393,574 492 3.61

5 Primary Combustion Air 311,240 492

6 ROFA 431,877 492

7 Secondary Burner Air 961,697 492

8 PA/Coal 465,842 165

9 Casing Leakage 22,693 58

10 Sorbent 9,017

11 Transport Air 1,815 58

12 Sorbent/Air 9,017 1,815 58

13 Boost Air 84,560 58 21.99

14 Flue Gas at Economizer Outlet 23,094 1,949,638 612

15 Bottom Ash 3,816

16 Economizer Ash 954

17 Duct Humidication Inlet Gas 23,094 2,120,119

18 Duct Humidication Outlet Gas 23,094 2,124,295 41,760

19 Humidication Inlet Water 41,760

20 Compressed Air 4,176

21 Fly Ash 23,094

22 Stack Gas 2,124,295 41,760

23 Feed Water 1,382,000 461

24 Superheat Steam Out 1,382,000 1003

25 Reheat In 1,243,800 665

26 Reheat Out 1,243,800 966

Assumptions:

Wet Basis: Humidity = 0.00658 lb H2O/lb Dry Air

Load: 188 MW, Gross; HHV = 12,800 lb/hr (dry)

95% Sorbent Purity

Ca/S = 2.5; 1.60 lbSO2/mmBtu

SR1 = 0.89, SRT = 1.26

Exit O2%, wet = 4.13%

Pressure 

Solid Gas Water in WC

Stream 

No. Stream Description

Flow Rate (lb/hr) Temperature 

°F
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-45 

GE Energy

TABLE 4-11. MATERIAL BALANCE FOR NOMINAL LOW LOAD OPERATION AT 

5% SORBENT AIR 

1 Coal 52,671

2 Inlet Air 831,105 58

3 APH Leakage 75,555 58

4 Combustion Air 649,514 448 0.42

5 Primary Combustion Air 106,036 448

6 ROFA 290,777 448

7 Secondary Burner Air 358,737 448

8 PA/Coal 158,708 165

9 Casing Leakage 9,653 58

10 Sorbent 3,072

11 Transport Air 618 58

12 Sorbent/Air 3,072 618 58

13 Boost Air 37,642 58 16.88

14 Flue Gas at Economizer Outlet 7,868 849,714 513

15 Bottom Ash 1,300

16 Economizer Ash 325

17 Duct Humidication Inlet Gas 7,868 925,269

18 Duct Humidication Outlet Gas 7,868 927,096 18,270

19 Humidication Inlet Water 18,270

20 Compressed Air 1,827

21 Fly Ash 7,868

22 Stack Gas 927,096 18,270

23 Feed Water 469,000 379

24 Superheat Steam Out 469,000 937

25 Reheat In 422,100 419

26 Reheat Out 422,100 731

Assumptions:

Wet Basis: Humidity = 0.00658 lb H2O/lb Dry Air

Load: 61 MW, Gross; HHV = 12,800 lb/hr (dry)

95% Sorbent Purity

Ca/S =2.5; 1.6 lbSO2/mmBtu

SR1 = 0.95, SRT = 1.64

Exit O2%, wet = 7.85%

Stream 

No. Stream Description

Flow Rate (lb/hr) Temperature 

°F

Pressure 

Solid Gas Water in WC
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 4-46 

GE Energy

TABLE 4-12. MATERIAL BALANCE FOR MINIMUM OPERATION AT 4% SORBENT 

AIR 

1 Coal 52,671

2 Inlet Air 831,105 58

3 APH Leakage 75,555 58

4 Combustion Air 649,514 448 0.42

5 Primary Combustion Air 106,036 448

6 ROFA 290,777 448

7 Secondary Burner Air 358,737 448

8 PA/Coal 158,708 165

9 Casing Leakage 9,653 58

10 Sorbent 2,458

11 Transport Air 495 58

12 Sorbent/Air 2,458 495 58

13 Boost Air 30,113 58 10.81

14 Flue Gas at Economizer Outlet 7,395 841,920 513

15 Bottom Ash 1,300

16 Economizer Ash 325

17 Duct Humidication Inlet Gas 7,395 917,475

18 Duct Humidication Outlet Gas 7,395 919,302 18,270

19 Humidication Inlet Water 18,270

20 Compressed Air 1,827

21 Fly Ash 7,395

22 Stack Gas 919,302 18,270

23 Feed Water 469,000 379

24 Superheat Steam Out 469,000 937

25 Reheat In 422,100 419

26 Reheat Out 422,100 731

Assumptions:

Wet Basis: Humidity = 0.00658 lb H2O/lb Dry Air

Load: 61 MW, Gross; HHV = 12,800 lb/hr (dry)

95% Sorbent Purity

Ca/S =2.0; 1.6 lbSO2/mmBtu

SR1 = 0.95, SRT = 1.63

Exit O2%, wet = 7.74%

Pressure 

Solid Gas Water in WC

Stream 

No. Stream Description

Flow Rate (lb/hr) Temperature 

°F
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-1 

GE Energy

5.0 Furnace Sorbent Injection Engineering Design 

GE designed the sorbent injection system for Progress Energy Robinson Station Unit No. 1. 

The detailed engineering design of the sorbent injection system is based on the design 

specifications described in Section 4.7. Progress Energy issued a contract to Nol-Tec 

Systems for the supply of the sorbent injection system major equipment and materials. 

5.1 General Description 

Figure 5-1 shows a system overview of the sorbent injection system. The sorbent injection 

system can be divided into the following subsystems: 

1. Silo fill system - Unloading the sorbent (hydrated lime) from trucks into silos. 

2. Silo discharge and metering feeder system – Transferring the sorbent from silos to the 

day bin and feeding the sorbent from day bin into the convey line. 

3. Injection system – Injecting the sorbent into the upper or lower injectors. 

Figure 5-1. System overview. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-2 

GE Energy

5.2 Silo Fill System 

The sorbent (hydrated lime) is delivered to the Robinson site via pneumatically-unloaded 

truck trailers. The trailers are totally enclosed tankers with a capacity of 20-25 tons. The 

trailers are unloaded at the sorbent silo truck unloading station. Truck unloading is 

accomplished using a truck mounted blower to convey the sorbent pneumatically via a 

pipeline to one of the three sorbent storage silos, each silo having a separate unloading 

connection - station. Conveying air is vented from the top of each storage silo through a silo 

vent cartridge type of filter equipped with replaceable elements. Each silo vent filter operates 

continuously during truck unloading – silo filling with the silo’s vent filter’s electrical power 

and compressed air is to be automatically turned on by the truck unloading station controls. 

During sorbent transfer operations, sorbent flow from one of the three conical bottom storage 

silos is enhanced by fluidizing bin bottoms. Each storage silo has an automatic slide gate 

isolation valve (butterfly valve approved substitution) located in the silo discharge pipe 

between the storage silo and a silo sorbent positive flow rotary feed valve which feeds 

sorbent into the pneumatic conveyor transfer system. Only one silo discharges sorbent at a 

time. 

The dilute phase pneumatic transfer system conveys sorbent from the storage silos to a day 

silo. The weigh hopper is mounted on four load cells, which is to continuously monitor the 

sorbent quantity (weight) in the silo. Pneumatic conveying transfer air is vented from the top 

of the weigh hopper silo through a cartridge type of vent filter equipped with replaceable 

elements. In order for the vent type of filter to operate properly during filling of the weigh 

hopper silo, electrical power and compressed air to the vent filter are automatically turned on 

by the pneumatic conveying loading station controls. 

5.3 Silo Discharge and Metering Feeder System 

Sorbent flows by gravity out of the weigh hopper’s conical bottom and is enhanced by 

fluidizing air slides. Sorbent out of the weigh hopper flows through a knife gate or butterfly 

isolation valve and into a sorbent positive flow rotary feed valve which is used to control the 

amount of sorbent feed to the boiler via a variable frequency drive sorbent out of the speed 

controlled rotary feed valve is gravity fed into a second rotary feed valve to provide an air 

lock from the boiler delivery pneumatic conveying – transport system. This second rotary 

feed valve operates at a constant speed with a higher throughput capacity than the first 

variable speed controlled rotary feed valve to prevent any buildup of sorbent between the two 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-3 

GE Energy

rotary valves. Any air leakage from the transport line back through the airlock rotary valve is 

vented through a vent pipe back into the top of the weigh hopper. 

The boiler sorbent delivery utilizes pneumatic conveying. Transport air is provided by a 

rotary positive displacement blower (Transport Blower), which operates at a constant volume 

output. Transport air is monitored by an arrangement of flow meters, pressure and 

temperature sensors. 

Pressurized transport air from the Transport Blower is delivered to the discharge of the 

second rotary valve airlock beneath the weigh hopper where sorbent is fed into the pneumatic 

conveying transport line. The sorbent is pneumatically conveyed via a heavy wall rubber 

hose to a Diverter Valve. The Diverter Valve controls sorbent flow to either the lower 

furnace sorbent injectors or the upper furnace sorbent injectors, depending on boiler steam 

flow. After the diverter valve, sorbent flows into flow splitter(s) which divide the sorbent 

flow into twelve (12) equal outlet streams which are connected to the twelve (12) furnace – 

boiler injectors. 

At the sorbent injectors, the pneumatically transported sorbent is mixed with a high volume 

of sorbent injection air supplied from a centrifugal fan located near the boiler. The sorbent 

injection air fan is used to provide a high mass flow of air to mix with the sorbent upon 

entering the boiler furnace to aid in the penetration and mixing with the furnace combustion 

gas for efficient control of SO2 from the coal combustion process. 

5.4 Injection System 

The intent of the sorbent injection system is to capture sulfur dioxide (SO2) and produce 

calcium sulfate and calcium oxide, which are captured by the electrostatic precipitator. 

The Sorbent Injection System is designed with the following parameters: 

1) Sorbent transfer rate from silo to weigh hopper 32,000 lbs/hr minimum. 

2) Sorbent transport rate from weigh hopper to boiler 

a) 9,017 lbs/hr nominal full load; 

b) 3072 lbs/hr nominal low load; 

c) 15,626 lbs/hr maximum; 

d) 2458 lbs/hr minimum. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-4 

GE Energy

3) Sorbent transport rate minimum system turndown capacity 6.4:1. 

4) Sorbent to air mass ratio for dilute phase transport 4:1 ratio. 

5) Minimum transfer and transport line velocity 3500 feet / minute. 

The sorbent feed system delivers the selected sorbent and total sorbent air (transport air plus 

injection air) from the weigh hopper to the boiler at specified delivery rates corresponding to 

four system operating conditions: nominal full load, nominal low load, maximum and 

minimum (see Table 5-1). 

TABLE 5-1. OPERATION SPECIFICATIONS 

Parameter Units Nominal 

Full Load

Nominal 

Low Load Maximum Minimum

Sorbent Feed Rate to Boiler 

(hydrated lime) lb/hr 9,017 3,072 15,626 2,458

Total Injection Air to Boiler 

(transport air plus boost air) lb/hr 86,375 38,260 94,929 30,608

In this regard, the following specific performance guarantees were established using the 

measurement systems identified (or equivalent.). 

• The feed rate of sorbent from each of the storage silos shall conform to the set point 

feed rates (for each of the four operating conditions noted above) with an accuracy of 

±10%. This shall be measured using the time required to fill the weigh bin feeder silo. 

The system shall demonstrate an ability to maintain the set point feed rates for a 

minimum of a 2-hour test period. 

• The total sorbent flow delivered to the injectors shall conform to the four set points 

with an hourly average accuracy not to exceed ±5%. This average hourly feed rate 

shall be determined based on weigh bin measurements. Three separate runs shall be 

made at each load condition with each run having a duration of 2 hours. (Total of 12 

test runs) During these tests feed rate data shall be gathered on a 2 minute rolling 

average basis to determine the 1-hour block average feed rate. To assure temporal 

stability of sorbent feed, the 2-minute rolling average shall not deviate from the set 

point by more than 7%. To determine the precision of the feed system, each 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-5 

GE Energy

subsequent 2-hour test shall be performed at a different load condition. The system 

precision shall not exceed 5% as determined by the standard deviation of the 1-hour 

average feed rate for each load condition. 

• There shall be no significant pressure pulsing or flow surges in the sorbent transport 

lines during continuous steady-state operation. The instantaneous static pressure in 

the transport line immediately downstream of the feeder shall not deviate from the 2- 

minute rolling average pressure by more than ±20%. This shall be verified using an 

appropriately scaled pressure gage or transmitter installed in the transport line within 

10 diameters downstream of the point where solids are introduced into the transport 

line. The test shall be conducted at all four operating conditions for a period of 2 

hours each. 

• The total clean transport airflow rate must remain stable. The flow rate shall be 

continuously measured for a test period of at least one hour at conditions equivalent 

to nominal full load and nominal low load. From each data set, 2-minute rolling 

average flow rates shall be determined. The standard deviation in the flow rate shall 

not exceed 3%. 

• The splitters shall be designed to distribute solids and transport air uniformly to each 

injector at each injection elevation. 

• The uniformity of transport air shall be determined by installing a calibration section 

immediately upstream of each injector. The calibration section is a piece of straight 

pipe that is at least 10 diameters long and with a port located 2/3 of the way down the 

test piece. The injector air velocity shall be measured using a terminal velocity probe 

or a pitot probe inserted through the port in the test section. The maximum variation 

in clean air transport velocity shall not exceed ±5% from the mean. 

• The splitter must also uniformly distribute the flow of sorbent solids. The maximum 

variation in solids flow among the different injectors shall not exceed 10% relative 

standard deviation. The solids flow shall be determined by placing filter socks over 

each of the 12 injectors and then weighing the amount of material collected in each 

filter sock following the test. This test shall be performed at the nominal full load 

condition only. Transport air flow rate shall be established at the test condition prior 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-6 

GE Energy

to commencing sorbent feed. The sorbent feed test duration shall be 5 to 10 minutes, 

or other duration as determined by mutual agreement between Supplier and Buyer. 

• There is concern that moisture in the airflow used to transport the solids will cause 

the sorbent to agglomerate and potentially to cause bridging or plugging of the feed 

system. The vendor shall demonstrate that such a potential problem will not occur by 

examining the particle size distribution of sorbent in the weigh bin hopper 

immediately following a rain or following a simulated rain shower. Rain may be 

simulated using hose to spray water in the immediate vicinity of the fan inlets. 

Sorbent in the day bin shall be evacuated and examined for presence of agglomerated 

pellets and a sample collected for determination of the particle size distribution as 

compared to material delivered to the main storage silo. If agglomeration is present, 

the situation must be remedied by an appropriate corrective action up to and including 

addition of either a heater or desiccant dryer at the appropriate fan or blower air inlet. 

• Static electricity discharge is a key safety concern. No electrical shocks or visible 

sparking shall be permitted in any portion of the sorbent delivery system. 

• No visible solids leaks shall be permitted in any portion of the sorbent delivery 

system, especially in the region between the weigh hoppers and the injectors. 

• Different types of valves may be acceptable for isolation purposes on the main 

storage silos and the weigh hopper. The vendor shall be responsible for selecting and 

installing isolation systems that provide zero discharge of solids from the storage 

device(s). Since isolation of storage containers is intended for period when the 

storage silo is not in use, the zero discharge condition shall be demonstrated when the 

hopper feed enhancer (aeration system of vibrating bottom) is not in operation. 

• In the event the system cannot be designed to economically achieve these 

performance specifications at all four operating conditions without equipment 

changes: performance at the nominal full load operating condition shall take 

precedence over the other conditions, followed by the nominal low load, maximum 

and minimum operating conditions (in descending order of precedence). 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 5-7 

GE Energy

5.5 Controls and Instrumentation 

A control system is designed for the proposed material handling system. The control system 

includes the features requested below as well as the features that would add to the reliability 

or functionality of the controls and operation of this system.

The following control documents were provided for the project: 

1. P&ID – Detailed P&ID of sorbent storage, transport and injection system. 

2. I/O List – List of all I/Os that are added, and modified was identified, documented, and 

submitted. 

3. Equipment List – List of all field equipment including instrument and valves was

supplied. 

4. Instrument Datasheets – Data sheets for all supplied equipment was submitted. 

Equipment list contains the identification numbers of relevant datasheet index number, 

which corresponds to the supplied instrument datasheet. 

5. Instruction Manual – Instruction manuals of the supplied equipment and instrument was 

supplied. 

6. System Functional Description – Detailed functional description of the sorbent injection 

system was supplied. The document is the basis of detailed logic configuration 

development. It describes the sequence of operation, operator controls, alarm and fault 

conditions and alarm and fault actions. 

7. SAMA and Ladder Logic Drawing – Actual logic configuration completed for complete 

operation of the system with interfaces to existing plant Delta V DCS control system via 

Ethernet. 

8. Wire Termination Drawings – complete wire termination drawings for any

interconnections required or interfaces to existing plant systems. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 6-1 

GE Energy

6.0 ESP Upgrades 

Based on the number of changes that have occurred in the course of the furnace sorbent 

injection demonstration program design, the electrostatic precipitator performance estimate 

has been reviewed. The analysis has been done with assumptions discussed in the following 

section. 

6.1 Analysis Assumptions 

The design coal utilized for the emission estimate is shown in the Table 6-1. Based on the 

design coal, 25% excess air, 9% in-leakage and an ESP inlet temperature of 270°F, a 

combustion calculation defines the gas volume as 609,372 ACFM or 402,688 DSCFM. 

Stack test data was provided for the years 2004, 2005, and 2006. The data showed mass 

emission levels and the corresponding opacity measurements. For the purpose of calibrating 

a performance-estimating model, the 2006 test results shown in Table 6-2 were used.

TABLE 6-1. ESP COAL DESIGN SPECIFICATIONS 

Parameter Unit Value

Carbon % 68.77 

Hydrogen % 4.5 

Sulfur % 1.19 

Oxygen % 4.98 

Nitrogen % 1.70 

Moisture % 6.44 

Ash % 12.34 

Heating Value (AR) BTU/lb 11,976 

TABLE 6-2. ROBINSON UNIT #1 STACK TEST RESULTS FOR 2006 

Run # Opacity (%) PET 

(lb/MMBtu) 

MMBtu/hr SO2 (%) Ash (%) BTU 

Test 1 6.3 0.068 1,633 2.46 11.34 11,619 

Test 2 6.4 0.069 1,632 2.86 12.42 11,624 

Test 3 5.7 0.078 1,625 2.50 11.62 12,024 

Average 6.1 0.072 1,630 2.61 11.79 11,756 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 6-2 

GE Energy

6.2 Estimated Electrostatic Precipitator Performance 

For the purpose of estimating the outlet dust loading during furnace sorbent injection, a 

hydrated lime injection rate of 11,700 lb/hr was utilized. When the design coal is applied to 

the calibrated electrostatic precipitator model, the estimated emissions with sorbent injection 

are indicated in Table 6-3. 

TABLE 6-3. ROBINSON UNIT #1 ESTIMATED STACK EMISSIONS W/FSI 

Opacity (%) PET (lb/MMBtu) MMBtu/hr 

16.0 0.17 1,800 

Therefore, relative to the 2006 stack test results, the performance projection was for opacity 

to increase by approximately a factor of 2.6 and PM emissions by a factor of 2.4. 

This estimated performance level incorporates basic maintenance upgrades such as: 

• Internal alignment 

• Internal water wash 

• Removal of accumulated dust on inlet distribution devices 

• Removal of accumulated dust on discharge electrodes 

• Repair of high voltage rapper trains 

• Optimize rapping program 

• Cleaning insulators. 

6.3 Short Term Electrostatic Precipitator Upgrades 

There are specific activities that can be implemented to improve the existing electrostatic 

precipitator capabilities. These are activities that do not modify collecting plate area, but 

improve collection efficiency by restoring control of exhaust that is currently bypassing the 

treatment zone. The value of many of these activities was demonstrated during electrical 

testing performed in January 2007. These activities include the followings. 

6.3.1 Vertical and Hopper Anti-Sneak Baffles 

Vertical baffles will be designed for the leading and trailing edge of each field between the 

casing and the first panel assembly, to prevent gas bypassing the treatment zone along the 

walls. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 6-3 

GE Energy

Horizontal hopper baffles will be designed for the bottom of the leading and trailing edge of 

each field to prevent gas from bypassing the treatment zone into the hopper region. All 

baffles will be designed using nominal 10 Ga. sheet steel. They are typically shop fabricated. 

6.3.2 Lower Frame Stabilizers 

Lower frame stabilizers help maintain the electrical clearances between the voltage 

electrodes and the collecting plates during the operation of the ESP. Each anti-sway assembly 

is composed of a single alumina rod and brackets to attach to the bottom of the lower highvoltage frame and the bottom of the collecting plates. The anti-sways are typically installed 

in opposite corners of the lower high voltage stabilizer frames, two (2) per frame. Without 

proper alignment, clearances will be compromised, and the fields will not be charged to their 

full potential without prematurely sparking. GE typically stocks the alumina insulator rods, 

reducing the lead time when compared to purchasing directly from the vendor. 

If the electrical clearance can be restored to like new condition, then it would be possible to 

energize each field to 55 Kvavg. The current T/R sets are only capable of delivering 50 

Kvavg. Simply adding 5 Kvavg can dramatically improve the collection efficiency of the 

ESP. 

6.3.3 Addition of Four (4) T/R Sets to the Inlet Fields 

It is recommended to replace the two (2) existing T/R sets on the inlet fields and add two (2) 

additional T/R sets, which will provide a total of four (4) T/R sets on the inlet field. These 

T/R sets will have a higher secondary voltage, which will impart a greater charge on the 

plates, thus increasing the collection performance of the inlet field. The T/R set addition 

would also require the following associated equipment: bus and guard, key interlock 

modifications, control cabinets, SQ-300 AVC's and VI-CLR's (Variable Inductance Current 

Limiting Reactors). The new T/R sets will have the specifications shown in Table 6-4. 

TABLE 6-4. NEW T/R SETS SPECIFICATIONS 

QTY Description Volts Amps KV (avg.) kV (p) mA kVA kW FF 

4 T/R set 1A/1B 

w/single gnd. 

switch 

400 104 65 102 450 41.8 37.6 1.2 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-1 

GE Energy

7.0 Field Test Program 

GE performed an evaluation of Furnace Sorbent Injection (FSI) on the Robinson Unit 1 

boiler. The evaluation included equipment performance tests, parametric tests, and a longterm trial. This section of the report describes the test objectives, plan, procedure, and results. 

7.1 Test Objectives 

The overall goal of the FSI demonstration program was to provide a comprehensive 

evaluation of FSI technology performance on the Robinson Unit 1 boiler. The primary 

objectives of the field test program were to: 

• Characterize the performance of the FSI system relative to key parameters that 

influence SO2 reduction performance, boiler thermal performance and operability, 

particulate emissions, and ash handling; 

• Optimize FSI operation over the normal range of boiler operating conditions; 

• Demonstrate the ability to operate the sorbent injection system over a long-term test 

period while maintaining SO2 reduction and acceptable boiler operability and 

particulate emissions; and 

• Define operating curves for integration into the distributed control system (DCS). 

7.2 Test Plan 

In order to meet the test objectives, a test plan and a test matrix were prepared to guide the 

equipment performance checkout, FSI system parametric optimization, and long-term trial. 

The equipment performance checkout was designed to ensure proper operation of the FSI 

system. Following system checkout, a comprehensive parametric test program was conducted 

to optimize the FSI operation by varying the sorbent flow rate, injection airflow rate, and 

injection elevation and configuration. The key metric was SO2 reduction, however, boiler 

thermal performance, boiler slagging, loss on ignition (LOI), CO emissions, opacity, ash 

handling and particulate matter (PM) emissions were evaluated to determine the overall 

impacts on boiler operation. Once the FSI system was characterized, a long-term test was 

conducted to demonstrate the performance of the boiler and FSI system over long-term 

operation. Table 6-1 lists the project test matrix. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-2 

GE Energy

TABLE 7-1. PROGRESS ENERGY FSI TEST MATRIX 

Test Description 

Date 

Completed 

Test No. 

# of 

Injections 

Load, 

MWg 

ROFA 

Flow 

Total 

Injection 

Air, lb/hr 

Exit O2, % 

wet 

Injection 

Elevation 

Sorbent 

Flow Rate, 

lb/hr 

Ca/S, 

mol/mol 

1. FSI Start Up 1.1 

9/15/2008 2.0 N/A 154 On N/A 3.0 N/A 0 0 

 2.1 12 153 On 77,928 4.2 Upper 7200 2.4 

9/16/2008 2.2 N/A 137 On N/A 3.4 N/A 0 N/A 

 2.3 12 137 On 77,928 4.2 Upper 5000 1.8 

 2.4 12 138 On 77,928 4.2 Upper 5000 1.8 

 2.5 12 138 On 77,928 3.9 Upper 5000 1.8 

9/17/2008 2.6 N/A 165 On N/A 2.9 N/A 0 N/A 

 2.7 12 162 On 77,928 4.2 Upper 3100 0.9 

9/18/2008 2.8 N/A 171 On N/A 2.9 N/A 0 N/A 

 2.9 12 171 On 77,432 4.2 Upper 3109 0.9 

 2.10 12 171 On 75,847 4.2 Upper 3109 0.9 

9/19/2008 2.11 N/A 139 On N/A 3.2 N/A 0 N/A 

 2.12 12 139 On 74,113 4.2 Upper 7010 2.6 

2. Preliminary 

Test 

 2.13 12 139 On 74,418 4.2 Upper 6912 2.5 

9/22/2008 B N/A 154 On N/A 3.0 N/A 0 N/A 

 11R1 12 154 On 74,568 4.2 Upper 3118 0.9 

9/23/2008 B N/A 123 On N/A 3.5 N/A 0 N/A 

 12R1 12 144 On 70,856 4.1 Upper 8951 2.6 

 10R1 12 164 On 79,362 4.2 Upper 2513 0.7 

9/24/2008 B N/A 134 On N/A 3.1 N/A 0 N/A 

 12R1 12 134 On 71,797 4.0 Upper 9003 2.7 

 11R1 12 134 On 72,041 4.1 Upper 3100 0.9 

 10R1 12 134 On 72,225 4.2 Upper 2579 0.8 

 12 134 On 73,974 4.3 Lower 3050 0.9 

 B N/A 132 On N/A 3.3 N/A 0 N/A 

9/25/2008 B N/A 98 On N/A 4.4 N/A 0 N/A 

 10R3 12 99 On 58,987 5.0 Upper 2564 0.9 

3. Equipment 

Performance 

Tests 

 11R3 12 126 On 72,932 4.0 Upper 3077 0.9 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-3 

GE Energy

TABLE 7-1. PROGRESS ENERGY FSI TEST MATRIX (CONTD) 

Test Description 

Date 

Completed 

Test No. 

# of 

Injections 

Load, 

MWg 

ROFA 

Flow 

Total 

Injection 

Air, lb/hr 

Exit O2, % 

wet 

Injection 

Elevation 

Sorbent 

Flow Rate, 

lb/hr 

Ca/S, 

mol/mol 

9/29/2008 4.0 N/A 159 On N/A 3.0 N/A 0 0 

 4.1 12 159 On 77,746 4.16 Upper 2498 0.8 

 4.2 12 158 On 76,713 4.18 Upper 6904 2.2 

 4.3 12 158 On 76,088 4.14 Upper 8218 2.6 

9/30/2008 4.4 N/A 159 On N/A 2.94 N/A 0 N/A 

 4.5 12 161 On 69,455 4.13 Upper 7204 2.6 

 4.6 12 161 On 77,414 4.19 Upper 6677 2.5 

 4.7 12 158 On 81,993 4.15 Upper 6566 2.4 

 4.7.1 12 158 On 87,076 4.15 Upper 6011 2.2 

10/01/2008 4.8 N/A 159 On N/A 2.9 N/A 0 N/A 

 4.9 12 159 On 76,272 4.31 Lower 6950 2.6 

 4.10 12 159 On 78,379 4.26 Lower 5031 1.9 

 4.11 12 159 On 79,836 4.26 Lower 2565 1.0 

10/02/2008 4.16 N/A 76 On N/A 5.66 N/A 0 N/A 

 4.18 12 77 On 39,510 5.8 Lower 1519 1.0 

 4.17 6 76 On 45,961 5.91 Lower 1428 0.8 

 4.18.1 8 77 On 47,781 5.89 Lower 3050 1.9 

 4.19 10 76 On 49,558 5.9 Lower 3140 2.0 

 4.19.1 12 76 On 50,654 5.93 Lower 3099 2.0 

10/03/2008 4.12 N/A 158 Off N/A 2.85 N/A 0 N/A 

 4.13 12 159 Off 82,166 3.67 Upper 2590 0.9 

 4.14 12 159 Off 77,044 3.68 Upper 4987 1.7 

 4.15 12 159 Off 68,623 3.68 Upper 7043 2.4 

10/06/2008 4.20 N/A 157 Off N/A 2.97 N/A 0 N/A 

 4.21 12 159 Off 82,166 3.63 Upper 7009 2.37 

 4.22 12 159 Off 77,044 3.65 Upper 7044 2.38 

10/07/2008 4.24 12 178 Off N/A 2.75 N/A 0 N/A 

 4.25 12 176 Off 69,781 3.67 Upper 0 N/A 

 4.26 12 178 Off 69,833 3.24 Upper 0 0.03 

 4.27 12 178 Off 73,223 3,23 Upper 2535 0.5 

 4.28 12 181 Off 73,610 3.28 Upper 2530 0.5 

 4.29 12 182 Off 78,673 3.28 Upper 3873 0.8 

4. Parametric 

Tests 

 4.30 12 181 Off 78,413 3.26 Upper 4985 1.0 

5.0 Long Term 

Test 

12/12/2008 

 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-4 

GE Energy

7.2.1 Equipment Performance Tests 

The equipment performance guarantees cover various aspects of the FSI system: sorbent 

storage, transport and injection system as well as the transport and boost air system. The 

detail equipment performance guarantee can be found in Progress Energy Robinson Unit 1 

Technical Specification, Rev. E [7] and Progress Energy Furnace Sorbent Injection FSI 

Equipment Performance Test Plan, Revision 0.0 [3]. 

The objectives of the equipment performance tests were to ensure that the following 

components worked properly at the designed operating conditions. 

• Sorbent injection system, 

• Sorbent feed system, 

• Transport air supply, 

• Splitters, 

• Moisture in air, and 

• Miscellaneous aspects such as electricity discharge and valve operation. 

The equipment performance tests were conducted in two phases. During the first phase of the 

tests, visual inspections and splitter uniformity tests were conducted. The splitter uniformity 

tests were conducted in two steps; first with just clean transport air and second with a mixture 

of sorbent and transport air. Prior to the splitter clean air uniformity tests, preliminary visual 

inspections were performed to check for air leaks especially at the joints such as at camlok 

fittings, flange connections, diverter, and splitter connections. Splitter clean air uniformity 

tests were conducted on both upper and lower furnace injectors. The uniformity of transport 

air was determined by installing a calibration section immediately downstream of the 

splitters. 

Immediately following the sorbent injection system shakedown, the second phase of the 

equipment performance test program was performed. During these tests, sorbent was injected 

into the boiler and careful attention was taken to define and mitigate any detrimental effects 

on the boiler performance. 

7.2.2 Parametric Tests 

The parametric tests facilitated the evaluation of the most promising injection test conditions 

and identified the conditions for the subsequent long-term testing. As shown in the test plan, 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-5 

GE Energy

the impacts of sorbent injection rate, injection air flow rate, injection elevation, and ROFA 

operation were evaluated systematically during the parametric testing. While not specifically 

listed as a test parameter, coal sulfur content also varied during the parametric tests, allowing 

this variable to be characterized as well. The purpose of parametric testing was to determine 

optimum FSI operating conditions without impacting the boiler operation at all loads. 

However, due to additional air addition to the furnace and considering safety aspects of the 

boiler especially at high loads, GE and Progress Energy jointly agreed to conduct the desired 

Ca/S of 2.5 tests up to 159 MWg, which is 86% of the maximum boiler capacity. Loads 

above 159 MWg were tested at Ca/S of 1.0. Each parametric test condition was conducted 

for 2 to 3 hours. The typical test day was 0900 hrs to 1600 hrs. During this period, a total of 

three test conditions were typically tested. 

After the parametric tests were completed, analysis of the results identified additional test 

conditions of interest and gaps in the data set. The initial parametric tests focused on the 

impacts of sorbent injection on the boiler and ESP. At the completion of the parametric tests, 

all test results were reviewed and summarized. During the testing, increase in stack opacity 

became a concern and was a limiting factor in increasing sorbent rates at higher loads. From 

the analyses it was understood that additional tests were required to characterize opacity. For 

this purpose, a recommended operating strategy for the long-term test was jointly developed 

with Progress Energy’s plant and engineering staff based on the parametric test results. The 

basis of this strategy was to maximize sorbent injection to the extent possible while 

maintaining boiler operability and opacity. A specific guideline was to reduce sorbent system 

operation whenever opacity reached 35%. In the early part of the long-term trial this 

guideline limited FSI system operation at high load boiler operation. By the end of the trial, 

the combination of ESP operational changes, control of injection air flow rate, cooler 

ambient weather, and firing of higher sulfur coal allowed the FSI system to be operated for 

longer periods of time at higher sorbent flow rates. 

7.2.3 Long-Term Tests 

In general a long-term trial is desirable to allow the FSI system and boiler response to reach 

steady state and to allow performance to be defined over the range of operating conditions 

that would normally be encountered at the Robinson boiler, such as changes in boiler load 

and coal composition. After the parametric tests, the long-term trial was conducted. The 

objective of the long-term trial was to assess performance and long-term impacts of the 

sorbent injection process. At the beginning of the long-term testing, the FSI system was 

optimized to operate continuously and to maximize injection rates to the extent possible at 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-6 

GE Energy

high loads. The extended optimization test analyses revealed that several factors such as dust 

loading, flue gas flow rate, boiler excess oxygen, air heater gas outlet temperature, sulfur 

content in coal and ESP conditions showed influence on opacity. GE also applied Six-Sigma 

tools and performed regression analysis to identify the direct impact of these parameters on 

opacity. The regression analysis identified that air heater gas outlet temperature has a 

dramatic impact on opacity, especially when the gas outlet temperature is above 275 oF. The 

typical air heater gas outlet temperature at Robinson varies between 250 and 270 oF at full 

load conditions, but with FSI in operation these temperatures increased to a maximum of 290 

o

F. Since air heater gas outlet temperature is not a directly controllable parameter, it was 

determined that adding additional ambient sorbent injection air to the furnace caused back 

end temperatures to increase. Since the sorbent injection air is not pre-heated, the flue gas 

leaving the air heater increases during FSI. If the same air were to be pre-heated in the air 

heaters, the increase in flue gas temperature would be very low. To maintain the air heater 

gas outlet temperature within the limits, the optimum injection air condition was determined 

for the loads above 120 MWg. The remaining parameters were also optimized to the extent 

possible. Various ESP rapping programs were also developed and tested. These rapping 

programs showed minimal to moderate effect on opacity. Further ESP field tuning might help 

to further mitigate the opacity. 

After the long-term optimization testing, the opacity levels were brought under control and 

allowed continuous sorbent injection at Ca/S of 2.5 up to 160 MWg load and Ca/S of 1.5 

from 160 MWg to 188 MWg. 

Boiler thermal performance was documented over the range of boiler and FSI operation. The 

impact of FSI and sootblowing on sectional heat absorptions and fouling factors were 

established. Projected SO2 capture trends were validated. 

7.3 Measurement Plan 

The detailed measurement test plan was described in Progress Energy Robinson Unit 1 

Furnace Sorbent Injection Project Sorbent Injection Test Plan, Revision 5.0 [4]. Table 6-2 

summarizes the emissions measurement procedures. The data that were collected during the 

sorbent injection tests included: 

• Operating conditions from the boiler data acquisition and control system, 

• Sorbent and injection air flow rate and temperature, 

• Plant O2 at the economizer outlet, 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-7 

GE Energy

• NOX, CO2, SO2, and mercury from the plant CEMS at the stack, 

• Furnace gas temperature (SpectraTemp) near the nose elevation, 

• Observations of furnace slagging patterns, 

• Fuel samples, 

• Sorbent samples, and 

• Fly ash samples. 

7.3.1 Boiler Operating Data 

Boiler control room data were recorded by GE personnel several times during each test. In 

addition, boiler operating data were collected and logged automatically by the plant PI 

system. These electronic data included all boiler, mill, air flow, air heater, and plant CEMS 

data available on the network. During the parametric tests, the data were retrieved at oneminute intervals. During the long-term tests, the data were retrieved at six-minute intervals 

from the beginning of the test day to the end of the final tests. 

7.3.2 Emissions Data 

Emissions data were collected from the existing CEMS system. Data were retrieved every 

minute during the parametric tests and every six minutes during to the long-term trial. The 

collected data at stack include NOX, CO2, SO2, mercury, flue gas flow rate and temperature. 

Table 7-2 summarizes the emission measurement procedures. 

TABLE 7-2. EMISSION MEASUREMENTS PROCEDURES 

Parameter Method Sampling 

Location 

SO2, NOX, O2, CO2, Hg Continuous Monitoring System Stack 

Total Particulate EPA Method 201A and 202 Stack 

SO2 EPA Method 6 Stack 

7.3.3 Coal & Ash Sampling 

Coal samples were taken from the coal feeder outlet daily by GE personnel. Approximately 

one cup of coal was collected every few hours, then blended into a composite sample and 

sent out to be analyzed as a representative coal sample of the day. Fly ash samples were 

collected at the economizer outlet duct. Selected fly ash samples were shipped to an 

independent laboratory by PGN for analysis of LOI, calcium, and sulfur content. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-8 

GE Energy

7.4 Test Results 

This section reports the test results obtained from start up, parametric and long term testing. 

The equipment performance is evaluated. The impacts of the boiler operating conditions as 

well as the sorbent injection system operating parameters on SO2 capture rate and calcium 

utilization are discussed. The long-term sorbent injection performance and its impact on 

boiler performance are reviewed. The test data is also used to validate the process model 

predictions derived from earlier process design studies. 

7.4.1 Start-Up Performance and Demonstrations 

During the first phase of the test program, visual inspection and splitter uniformity tests were 

conducted. The splitter performance guarantee tests were divided into two sections: clean air 

and sorbent injection. During the first part, the test apparatus was installed to measure flow 

from each line. Then, the sorbent flow was determined by placing sorbent filter device over 

each injector and the sorbent is collected and weighed from each filter following the test. 

Both tests were performed at the nominal full load. The test results are summarized in GE’s 

Sorbent Distribution Test Results, dated 10 July 2008 [8]. 

Clean Air Test Results

During the initial test, orifice plates were installed based on system design. After taking the 

flow readings, the velocities from each line were compared. A modified set of orifices was 

installed to balance the flows. This process was repeated until the lines were all balanced. 

Figure 7-1 and Table 7-3 show flow label and corresponding pressure drop, flow rates and 

velocities for each line of the upper elevation injectors. The operating air temperature was 

140 oF. The total flow rate was 5,417 lb/hr. The variation in clean air transport velocity was 

6.1% from the mean. 

Solid Flow Distribution Results

After the clean air test was concluded, the appropriate orifice plates were left in the flow line. 

Sorbent solids flow distribution was measured using drum/filter assemblies. Each apparatus 

was first installed according to the test plan. Each empty sorbent drum and air filter was 

weighed. Then the transport blower air was turned on to allow flow to stabilize for 15 

minutes. The total sorbent feed rate was set at 9,018 lb/hr. From the PLC, the weigh hopper 

indicated total sorbent feed was approximately 700 lbs. The test was conducted over 6 

minutes and 15 seconds. Then the transport air blower was run for 10 minutes to purge the 

sorbent in the lines. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-9 

GE Energy

Table 7-4 shows test results. On average, each drum weighed 53 lbs. The variation in sorbent 

transport velocity was 20% from the mean. 

1 9 10 11 12 3

H

L

Figure 7-1. Injection labels for upper elevation injectors. 

TABLE 7-3. CLEAN AIR TEST RESULTS FOR UPPER ELEVATION INJECTIONS 

Line Orifice 

Diameter

Venturi 

∆P

Static P Flow Density Flow Velocity

in in H2O in H2O scfm lb/ft3 lb/hr ft/s

1H 1.478 7.424 46 82 0.0753 378 412 107.61

1L 1.478 7.146 47 81 0.0753 371 405 105.55

3H none 8.453 46 88 0.0752 403 439 114.76

3L none 8.456 45 88 0.0751 403 439 114.85

9H 1.149 9.634 38 94 0.0739 429 468 124.40

9L 1.149 9.565 38 93 0.0739 427 466 123.94

10H 1.117 9.456 36 93 0.0735 425 464 123.84

10L 1.086 9.489 34 93 0.0733 426 464 124.48

11H 1.117 9.915 36 95 0.0735 435 474 126.83

11L 1.117 9.593 35 93 0.0734 728 467 124.89

12H 1.086 9.127 34 91 0.0732 418 456 122.37

12L 1.055 9.474 31 93 0.0727 425 464 125.44

Total 1083 5268 5417

Average 8.978 39 90 0.074 439 451 119.91

Standard Deviation 0.910 6 5 0.001 93 23 7.33

COV, % 6.12

Corrected 

Flow

lb/hr
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-10 

GE Energy

TABLE 7-4. SOLID FLOW DISTRIBUTION RESULTS FOR UPPER ELEVATION 

INJECTIONS 

Line Orifice 

Diameter

Tare 

Weight

Flange 

Weight

Initital 

Weight

Final 

Weight

Sorbent 

Weight

in lbs lbs lbs lbs lbs

1H 1.478 53.5 2.5 56.0 95.0 39.0

1L 1.478 49.0 2.5 51.5 91.0 39.5

3H none 43.0 2.5 45.5 90.0 44.5

3L none 52.0 2.5 54.5 99.5 45.0

9H 1.149 50.5 2.5 53.0 107.5 54.5

9L 1.149 49.5 2.5 52.0 99.5 47.5

10H 1.117 43.5 2.5 46.0 108.5 62.5

10L 1.086 48.0 2.5 50.5 117.0 66.5

11H 1.117 48.0 2.5 50.5 119.0 68.5

11L 1.117 52.0 2.5 54.5 120.0 65.5

12H 1.086 49.0 2.5 51.5 105.5 54.0

12L 1.055 44.5 2.5 47.0 95.5 48.5

Total 635.50

Average 104.00 52.96

Standard Deviation 10.63 10.61

COV, % 20.03

Injection Equipment Tests

During the second phase of the equipment performance test program, sorbent was injected 

into the boiler. The test program began with a transport airflow stability test as shown in 

Table 7-5. Transport airflow stability test was conducted at just transport air of 1,000 ACFM. 

The test was performed as prescribed in the guarantee section for one-hour. During this onehour test period, the transport airflow was recorded online from the flow transmitter installed 

downstream of the transport air blower (BL4). The results were collected and reduced for 

standard deviation. Prior to sorbent feed rate tests, visual inspection was performed along the 

system transport line for any sorbent leaks. Any identified sorbent leaks were rectified before 

commencing the feed rate tests. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-11 

GE Energy

The sorbent feed rates were conducted at four different flow conditions. The four different 

flow conditions are shown in Table 5-1. According to the guarantees, there were three 

different equipment performance tests to be conducted to evaluate the sorbent feed rate. The 

three different performance tests were 1) when the sorbent from the storage silo is transferred 

to daily silo, 2) when the sorbent from the daily silo is injected into the furnace from injectors 

and 3) static pressure stability in the transport line. For the purpose of minimizing the total 

test time, these tests were carried out simultaneously. 

The test sequence included test runs for the sorbent feed rates is summarized in Table 7-5. 

The test sequence started with filling the daily silo bin by transferring sorbent from storage 

silo 1, which has the capacity of 630,000 lbs. The rotary airlocks under the storage silos were 

driven by constant feed motor to deliver the constant sorbent feed rate of 32,000 lb/hr. The 

rotary airlocks were designed in such a way that the daily silo bin, which has a capacity of 

20,000 lbs filled in 1⁄2 hour. After filling the daily silo bin, the control valve under the storage 

silo was open to fill the weigh hopper, which has a capacity of 7,000 lbs. The sorbent weight 

of the weigh hopper from the load cell indicator after closing the control valve was recorded. 

This operation was followed each time the control valve under the day bin silo is closed and 

open. A total of 12 test runs were conducted, including 3 test runs at each sorbent flow 

condition. To determine the precision of the feed system, each subsequent 2-hour test was 

performed at a different sorbent feed condition. 

Table 7-6 shows the equipment performance results. Overall most tests met the guarantee 

criteria. A few tests marginally passed the test. For example, during test 10R2, the total 

sorbent flow to injector stability exceeded 7% of the set point over a few minutes during the 

test period. The deviation values eventually decreased over the course of the test, which 

could indicate that the system was still stabilizing. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-12 

GE Energy

TABLE 7-5. SORBENT FEED RATE TEST SEQUENCE 

Sequence Sorbent Flow Condition (4) Test Date Test & Run Duration Designed Flow Transferred

Total Sorbent 

Available Discharged

Remained in 

Weigh 

hopper

# # hrs:mins lb/hr lb/hr lb/hr lb/hr lb/hr

1 Transfer - Silo 1 to Day Silo Fill - 1 0:30 32,000 16,000 16,000

2 Injection - Minimum 10 R1 2:00 2,458 4,916

3 Injection - Nominal Low 11 R1 2:00 3,072 6,144 4,940

4 Transfer - Silo 2 to Day Silo Fill - 2 0:30 32,000 16,000 20,940

5 Injection - Nominal Full 12 R1 2:00 9,017 18,034 2,906

Total Number of Hours 7:00

6 Transfer - Silo 3 to Day Silo Fill - 3 0:30 32,000 16,000 18,906

7 Injection - Maximum 13 R1 1:00 15,626 15,626 3,280

8 Transfer - Silo 1 to Day Silo Fill - 4 0:20 32,000 10,667 13,947

9 Injection - Minimum 10 R2 2:00 2,458 4,916

10 Injection - Nominal Low 11 R2 2:00 3,072 6,144 2,887

Total Number of Hours 5:50

11 Transfer - Silo 2 to Day Silo Fill - 5 0:30 32,000 16,000 18,887

12 Injection - Nominal Full 12 R2 2:00 9,017 18,034 853

13 Transfer - Silo 3 to Day Silo Fill - 6 0:30 32,000 16,000 16,853

14 Injection - Maximum 13 R2 1:00 15,626 15,626 1,227

15 Transfer - Silo 1 to Day Silo Fill - 7 0:20 32,000 10,667 11,893

16 Injection - Minimum 10 R3 2:00 2,458 4,916

Total Number of Hours 6:20

17 Injection - Nominal Low 11 R3 2:00 3,072 6,144 833

18 Transfer - Silo 2 to Day Silo Fill - 8 0:40 32,000 21,333 22,167

19 Injection - Nominal Full 12 R3 2:00 9,017 18,034 4,133

20 Transfer - Silo 3 to Day Silo Fill - 9 0:30 32,000 16,000 20,133

21 Injection - Maximum 13 R3 1:00 15,626 15,626 4,507

Total Number of Hours 6:10

Total Sorbent Consumption (lb/hr) 159,725

(4) Sorbent should be transferred to daily silo only after the daily silo is completely empty.

3-Jul-08

4-Jul-08

Expected

1-Jul-08

2-Jul-08
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-13 

GE Energy

TABLE 7-6. EQUIPMENT PERFORMANCE TEST RESULTS 

Test 

Comment Date Duration Load Sorbent Feed Rate

Injection 

Air

Total Sorbent Flow 

Test

Sorbent Flow 

Stability Test

Sorbent Flow 

Precision

Pressure in 

Transport Line 

Stability

mm/dd/yy hour MW net lb/hr CFM

11R1 9/22/2008 2.0 145 3100 16000 PASS PASS PASS PASS

12R1 9/23/2008 2.0 145 9000 16000 PASS PASS PASS PASS

10R1 9/23/2008 2.0 158 2500 18000 PASS PASS PASS PASS

12R2 9/24/2008 1.0 125 2500 16000 PASS PASS PASS PASS

11R2 9/24/2008 1.0 125 3100 16000 PASS PASS PASS PASS

10R2 9/24/2008 1.0 125 9000 16000 PASS Marginal Marginal PASS

10R3 9/25/2008 1.0 145 2500 16000 PASS PASS Marginal PASS

11R3 9/25/2008 0.5 145 3100 16000 PASS PASS PASS PASS

12R3 9/25/2008 1.0 145 9000 16000 Data Mision Due to PI-DCS Problem

7.4.2 Coal Sample Analysis 

Coal samples were taken daily during the tests. Ultimate and proximate analyses are 

summarized in Table 7-7. Average coal moisture content was 5.5% and average ash content 

was about 12%. Coal heating value was around 12,233 Btu/lb. Coal sulfur content was 

specifically measured and used to calculate the theoretical SO2 emissions, as discussed in 

next section. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-14 

GE Energy

TABLE 7-7. COAL ULTIMATE AND PROXIMATE ANALYSIS 

Date Proximate Analysis As Received, % Ultimate Analysis As Received, % 

Sampled 

Moisture Ash Volatile 

Fixed 

Carbon 

Sulfur BTU Carbon Hydrogen Nitrogen Oxygen 

07/11/08 6.73 12.5 33.40 47.37 0.99 11,884 67.50 4.36 1.34 6.58 

07/26/08 6.83 9.96 35.65 47.56 0.85 12,333 68.21 4.78 1.42 7.95 

09/17/08 7.54 12.51 33.69 46.26 1.09 11,774 65.73 4.50 1.28 

09/18/08 5.48 12.53 33.99 48.00 1.11 12,050 67.57 4.60 1.36 7.35 

09/18/08 5.27 12.49 35.57 46.67 1.76 12,089 67.60 4.55 1.32 7.01 

09/19/08 5.02 13.34 33.86 47.78 1.03 11,993 67.07 4.64 1.33 7.57 

09/19/08 5.88 10.85 34.29 48.98 1.35 12,276 68.59 4.74 1.33 7.26 

09/24/08 5.93 12.28 34.48 47.31 1.18 12,042 67.14 4.60 1.19 7.68 

09/24/08 4.97 11.59 35.09 48.53 1.31 12,267 67.98 4.61 1.25 8.29 

09/24/08 4.94 12.22 35.31 47.53 1.25 12,207 67.15 4.91 1.38 8.15 

09/25/08 4.03 11.34 36.47 48.16 1.28 12,505 68.75 5.14 1.46 8.00 

09/25/08 3.71 12.30 35.42 48.57 1.30 12,363 67.87 4.93 1.37 8.52 

09/29/08 4.83 12.16 34.75 48.26 1.17 12,266 68.08 4.54 1.62 7.60 

09/29/08 5.02 12.01 33.48 49.29 1.2 12,121 67.98 4.56 1.61 7.62 

09/29/08 4.91 11.82 33.98 49.29 1.39 12,074 67.38 4.49 1.57 8.44 

09/29/08 5.62 12.34 33.89 48.15 1.23 12,055 67.51 4.50 1.60 7.20 

10/01/08 5.41 11.59 33.52 49.48 1.02 12,028 68.35 4.36 1.30 7.97 

09/30/08 5.58 13.10 33.79 47.53 1.10 11,861 66.78 4.52 1.27 7.65 

09/30/08 6.22 12.76 34.29 46.73 0.95 11,949 66.66 4.56 1.29 7.56 

09/30/08 5.56 13.58 34.01 46.85 1.06 11,718 65.86 4.46 1.25 8.23 

10/02/08 5.03 10.27 34.25 50.45 0.98 12,493 70.48 4.29 1.76 7.19 

10/02/08 4.49 13.25 33.86 48.40 0.99 12,144 68.74 4.28 1.69 6.56 

10/03/08 4.83 13.28 33.39 48.50 1.21 12,128 68.53 4.38 1.70 6.06 

10/03/08 4.50 9.43 35.52 50.55 0.92 12,661 71.74 4.55 1.81 7.05 

10/06/08 5.25 11.75 34.09 48.91 1.00 12,336 68.57 4.64 1.53 7.26 

10/07/08 4.16 12.05 35.59 48.20 1.27 12,437 69.19 4.68 1.32 7.33 

10/08/08 3.88 11.24 35.44 49.44 1.33 12,531 70.01 4.58 1.33 7.63 

10/17/08 5.01 11.64 33.72 49.63 1.28 12,304 68.35 4.48 1.43 7.81 

10/16/08 4.44 11.05 35.37 49.14 1.37 12,525 69.75 4.61 1.41 7.37 

10/20/08 3.81 12.25 35.41 48.53 1.16 12,352 69.03 4.57 1.37 7.81 

10/21/08 4.06 11.39 35.42 49.13 1.38 12,541 68.92 4.68 1.35 8.22 

10/22/08 3.74 12.22 34.73 49.31 1.19 12,390 68.71 4.71 1.39 8.04 

10/23/08 5.69 11.16 34.75 48.40 1.42 12,289 68.20 4.58 1.33 7.62 

10/23/08 5.80 10.54 35.54 48.12 1.63 12,391 68.39 4.66 1.35 7.63 

10/28/08 5.17 10.48 35.70 48.65 1.70 12,537 69.65 4.81 1.27 6.92 

10/29/08 5.15 11.88 34.68 48.29 1.59 12,230 67.45 4.63 1.29 8.01 

10/31/08 5.95 11.93 34.19 47.93 1.52 12,177 67.44 4.66 1.33 7.17 

10/30/08 5.71 13.17 34.30 46.82 1.54 11,932 66.48 4.64 1.32 7.14 

11/03/08 5.71 11.86 33.85 48.58 1.48 12,198 68.00 4.59 1.32 7.04 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-15 

GE Energy

TABLE 7-7. COAL ULTIMATE AND PROXIMATE ANALYSIS (CONTD) 

Date Proximate Analysis As Received, % Ultimate Analysis As Received, % 

Sampled 

Moisture Ash Volatile 

Fixed 

Carbon 

Sulfur BTU Carbon Hydrogen Nitrogen Oxygen 

11/04/08 4.60 13.97 33.08 48.35 1.38 11,964 66.68 4.59 0.94 7.84 

11/04/08 5.31 12.93 32.80 48.96 1.36 12,077 67.03 4.57 0.95 7.85 

11/04/08 4.95 12.43 33.08 49.54 1.40 12,189 67.72 4.58 0.92 8.00 

11/04/08 4.59 11.09 34.28 50.04 1.62 12,444 69.03 4.75 1.00 7.92 

11/04/08 4.97 12.62 33.34 49.07 1.38 12,141 67.95 4.64 0.92 7.52 

11/05/08 6.09 12.00 33.93 47.98 1.33 12,092 66.85 4.49 1.37 7.87 

11/05/08 4.70 12.37 33.76 49.17 1.54 12,199 67.93 4.60 1.36 7.50 

11/05/08 6.69 11.54 33.54 48.23 1.25 12,200 66.76 4.63 1.23 7.90 

11/05/08 7.45 10.92 33.89 47.74 1.17 12,198 67.71 4.58 1.37 6.80 

11/06/08 6.61 11.63 34.24 47.52 1.10 12,085 67.46 4.63 1.35 7.22 

11/07/08 5.61 11.14 34.99 48.26 1.26 12,356 68.45 4.77 1.33 7.44 

11/10/08 5.55 11.88 35.10 47.47 1.20 12,220 67.49 4.75 1.46 7.67 

11/11/08 3.80 11.04 35.96 49.20 1.30 12,606 70.46 4.85 1.44 7.11 

11/12/08 4.52 10.89 34.86 49.73 1.31 12,508 69.71 4.67 1.37 7.53 

11/13/08 5.24 9.75 35.20 49.81 1.35 12,607 69.25 4.79 1.56 8.06 

11/14/08 4.15 10.91 35.23 49.71 1.58 12,563 69.99 4.54 1.51 7.32 

11/17/08 6.17 10.92 34.08 48.83 1.51 12,307 67.74 4.64 1.11 7.91 

11/20/08 5.22 11.97 34.59 48.22 1.14 12,339 68.52 4.57 1.44 7.14 

11/21/08 5.05 11.27 35.72 47.96 1.51 12,366 67.88 4.62 1.45 8.22 

11/25/08 5.59 11.99 34.48 47.94 1.25 12,194 67.47 4.81 1.25 7.64 

11/26/08 5.85 11.69 33.75 48.71 1.21 12,143 67.96 4.60 1.38 7.30 

12/02/08 6.13 10.07 35.32 48.48 1.25 12,410 68.50 4.70 1.31 8.04 

12/03/08 6.06 11.97 34.39 47.58 1.22 12,166 67.80 4.71 1.29 6.95 

12/04/08 5.58 11.75 33.86 48.81 1.22 12,236 68.12 4.53 1.39 7.41 

12/08/08 6.33 10.95 34.13 48.59 1.27 12,257 68.21 4.53 1.48 7.23 

12/08/08 7.25 10.60 34.32 47.83 1.20 12,204 68.09 4.54 1.47 6.85 

12/09/08 6.94 11.29 34.06 47.71 1.33 12,098 64.87 5.32 1.49 8.76 

12/09/08 5.73 11.75 34.25 48.27 1.39 12,257 

12/09/08 5.63 12.74 34.10 47.53 1.47 12,154 

12/10/08 6.80 11.94 34.20 47.05 1.13 12,011 66.94 4.41 1.32 7.46 

12/10/08 5.91 11.05 34.59 48.45 1.33 12,355 68.48 4.85 1.38 7.00 

12/10/08 6.14 11.82 34.43 47.61 1.26 12,127 66.66 5.02 1.43 7.67 

7.4.3 Baseline SO2 Emissions 

During the parametric tests, flue gas SO2 concentration at the stack was measured daily prior 

to sorbent injection. The measured SO2 concentration was used for establishing the baseline 

SO2 emission and calculating SO2 reduction. Coal samples were also taken daily for the 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-16 

GE Energy

analysis of the coal sulfur content as shown in Table 6-3. Coal sulfur was then used to 

calculate the theoretical SO2 emission, which was compared to the measured baseline SO2

emission. 

For the long-term tests, sorbent was injected around-the-clock to the extent possible, and 

therefore baseline SO2 emissions were not measured each day. However, periodically sorbent 

injection was suspended due to issues associated with the injection system. The SO2

measured during no-sorbent injection time was then used as baseline data to compare with 

the theoretical SO2 emission. 

Figure 7-2 shows a comparison between the theoretical SO2 emission calculated from the 

coal sulfur content and the measured baseline SO2 emission. Results from both parametric 

and long-term tests are shown. The coal sulfur content ranged from approximately 1.0% to 

1.7% and the SO2 emissions ranged from 1.5 to 2.8 lb/MMBtu during the testing. Due to 

plant coal sourcing plans, the coal sulfur content in the long-term tests was higher than that in 

the parametric tests. In general, the measured SO2 emission is consistent with the theoretical 

calculations. Since there were no daily baseline SO2 measurements during the long-term 

tests, the theoretically calculated SO2 emission was used to estimate the SO2 removal rate for 

the assessment of the FSI performance in the long-term tests. 

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0.5 1 1.5 2

Coal Sulfur Content, %

SO2 Emission, lb/ MMBtu

Measured SO2, Parametric Test

Measured SO2, Long Term

Theoretical SO2

Figure 7-2. Comparison of theoretical SO2 and measured baseline SO2 emissions. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-17 

GE Energy

7.4.4 SO2 Removal Results 

SO2 removal rates measured from the preliminary and parametric tests are shown in Figure 

7-3 as a function of Ca/S ratio. The SO2 capture values are derived from SO2 concentrations 

measured with and without sorbent injection. The capture values are therefore not based on a 

theoretical SO2 yield, and take no credit for inherent SO2 capture. Typically coal mineral 

matter captures a few percent of the SO2 generated during combustion. 

The preliminary and parametric tests were conducted for a load range of 76 MWg to 156 

MWg. The calcium-to-sulfur ratio was varied from 1 to 3. Figure 7-3 shows that the SO2

removal rate increased with Ca/S as expected for the load range tested. The trend is 

consistent with GE’s model predictions made in 2007. About 45% to 50% SO2 removal was 

achieved with Ca/S ratio of 2.5. The scattering of the data is due to the variations in boiler 

and FSI injection system operations, which will be discussed in the next section. 

The results from the long-term tests further confirm the achieved SO2 removal performance 

from the preliminary and parametric tests as shown in Figure 7-4. Since there were no daily 

baseline SO2 measurements as discussed in the previous section, the removal rate is derived 

using the theoretical SO2 emissions. The removal rate calculated might therefore include the 

inherent SO2 capture. The long-term test data are presented in two groups. One group was 

obtained before October 19 when the FSI system was shut down for repairing the tube leaks. 

The second group was obtained after the FSI system was resumed for testing. The scatter in 

the data set may largely be due to the fact that SO2 reduction values are calculated based on a 

single composite coal sample that was taken each day, while coal composition (and the ratio 

of coals taken from different source piles) was known to have varied throughout each test 

day. In general, the SO2 removal rates through out the months long tests were consistent with 

the model predictions made in 2007. High reduction rate (> 60%) was achieved at Ca/S ratio 

of 3 with manageable impacts on boiler operation and performance. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-18 

GE Energy

0

10

20

30

40

50

60

70

0 1 2 3 4

Ca/S

SO2 Reduction, %

2007 Prediction

~159 MWg

~134 MWg

~76 MWg

Figure 7-3. SO2 removal as a function of Ca/S during the parametric tests. 

0

10

20

30

40

50

60

70

80

0 1 2 3 4

Ca/S

SO2 Reduction, %

2007 Prediction

~159 MWg

~134 MWg

~76 MWg

Long Term Before 10/19

Long Term After 10/19

Figure 7-4. SO2 removal as a function of Ca/S for all tests. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-19 

GE Energy

7.4.5 Impacts of Boiler Operation on Sulfur Capture

One project objective was to minimize boiler impacts during FSI operation. The burner zone 

stoichiometric ratio, ROFA flow rate and the ROFA operating mode during FSI operation 

were maintained at baseline settings. Therefore, the boiler load and the ROFA operating 

mode (on/off) were two of the primary boiler operation changes evaluated in the test 

program. 

The FSI system was designed to inject sorbent through the upper elevation injectors for 

medium and high boiler loads. The lower elevation injectors were designed for low load 

operation. Figure 7-5 shows three groups of test data: (1) lower elevation sorbent injection at 

76 MWg load; (2) upper elevation sorbent injection at 158 MWg; and (3) lower elevation 

sorbent injection at 158 MWg load. The data indicate that at lower Ca/S ratios, i.e., Ca/S ~1, 

the SO2 reduction rate is comparable for both loads. However, when Ca/S ratio is increased 

to a higher value, SO2 removal is more efficient for low load conditions than for higher load 

conditions. The difference can be explained by the mixing and penetration effectiveness of 

the sorbent injection. At low load, the furnace velocity is relatively low and the sorbent 

stream can more readily penetrate the furnace flow field to provide good mixing. The flue 

gas flow rate and velocity increase with increasing load, making it more difficult for the 

sorbent stream to penetrate and mix with the furnace gas. Therefore, as expected based on the 

Process Engineering work, the SO2 removal rate increases at decreasing boiler load. 

The sorbent utilization rate is also calculated for these tests, as shown in Figure 7-6. The 

sorbent or calcium utilization rate is calculated by taking the ratio of SO2 removal rate to the 

Ca/S ratio. As shown in the plot, the calcium utilization rate stays relatively constant at 24% 

in the low load tests and drops from 27% to 17% for the high load tests. Improving the 

sorbent injection penetration and mixing for high load operation could improve the sorbent 

utilization rate, although this would require higher sorbent air flow rate and velocity, 

potentially magnifying impacts upon boiler operation. 

A test was also performed to investigate the performance of lower elevation injections at 158 

MWg (Figure 7-5). The data show that at this load, the lower elevation injection is not as 

effective as the upper elevation injection. This is consistent with the system design basis. At 

high load, the furnace temperature at lower elevation is above of the optimal SO2 reaction 

window. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-20 

GE Energy

0

10

20

30

40

50

60

0 1 2 3 4

Ca/S

SO2 Reduction, %

158 MW Upper Elevation

158 MW Lower Elevation

76 MW Lower Elevation

Figure 7-5. Sorbent removal rate at two different loads during parametric testing. 

0

5

10

15

20

25

30

0 1 2 3

Ca/S

Ca Utilization, %

158 MWg 78 MWg

Figure 7-6. Sorbent utilization for 158 MWg and 78 MWg loads. 

Robinson Unit 1 is equipped with a ROFA system for NOX control. The FSI system was 

designed to operate with the ROFA system on. However, to examine the impact of ROFA 

operation on FSI performance, one of the parametric test series was conducted with the 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-21 

GE Energy

ROFA system off. Figure 7-7 compares the SO2 reduction rate and the calcium utilization for 

the ROFA on and off conditions. ROFA appears to have a small impact on the FSI 

performance. The ROFA off condition has slightly lower SO2 reduction and calcium 

utilization rates, consistent with the design basis. 

0

10

20

30

40

50

60

0 1 2 3

Ca/S

SO2 Reduction, %

ROFA On

ROFA Off 

(a) SO2 reduction as a function of Ca/S. 

0

10

20

30

0 1 2 3

Ca/S

Calcium Utilization, %

ROFA On

ROFA Off

(b) Calcium utilization as a function Ca/S. 

Figure 7-7. Impact of ROFA on SO2 removal and calcium utilization. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-22 

GE Energy

7.4.6 Impacts of Sorbent Injection on SO2 Removal 

The key design parameters of the FSI system, such as injector size and injection angle were 

optimized during the earlier process design phase. Along with injection elevation, parameters 

that can be adjusted during the FSI tests include sorbent flow rate and transport air flow rate, 

both of which have a upper limits due to system specifications. Within system constraints, 

tests were conducted to evaluate the impact of the injection air flow rate and Ca/S ratio on 

the SO2 removal rate during the parametric testing. 

The Ca/S ratio has a first order impact on SO2 removal as shown in previous plots. The 

measured SO2 reduction vs. Ca/S ratio throughout the testing program generally follows the 

model predictions derived by considering chemical kinetics, boiler quench rate and sorbent 

mixing. Typically 45% to 50% SO2 reduction at a Ca/S ratio of 2.5 was achieved in the tests. 

Sorbent injection air flow rate was designed to be around 5% of the total combustion air. A 

set of parametric tests was conducted to vary the sorbent air flow rate and to observe the 

response of the FSI performance. As shown in Table 7-8, the sorbent air flow rate was varied 

from 5% to about 6.2% of total combustion air, while the boiler load was maintained at 158 

MWg. The fuel flow rates shown in the table are calculated based on the steam generation. 

The total air flow rates are calculated from a material balance by using the measured exit 

oxygen. The test results are illustrated in Figure 7-8. Both SO2 removal rate and the calcium 

utilization are found to increase with the sorbent air flow rate. Higher sorbent air flow rate 

corresponds to higher the injection velocity and better mixing and penetration. However, a 

side impact of increasing the sorbent air is the increase in boiler excess air if the burner air 

and ROFA air remain unchanged. Another adverse impact of increasing sorbent air flow rate 

is increasing the air heater outlet gas temperature, which is one of the factors leading to 

opacity increase. Therefore, an objective of FSI system design is to minimize the sorbent air 

flow while maintaining good mixing and penetration. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-23 

GE Energy

TABLE 7-8. TEST CONDITIONS FOR VARYING INJECTION AIR RATE 

Parameter Note Unit Test 1 Test 2 Test 3 Test 4 

Load CEMS MWg 160.73 160.57 158.32 158.39 

Exit O2 CEMS % wet 4.13 4.19 4.15 4.15 

Fuel Flow Rate Calculated lb/hr 134,630 134,810 132,130 133,026 

Total Air Flow Rate Calculated lb/hr 1,499,521 1,501,523 1,473,500 1,483,475 

Sorbent air Flow Rate 

 Flow Rate Measured Lb/hr 74,344 82,287 86,860 91,962 

 % of Total Combustion Air Calculated % 4.96 5.48 5.89 6.2 

Ca/S Calculated % 2.63 2.45 2.42 2.23 

0

10

20

30

40

50

60

70

4 5 6 7

Total Injection Air, % of Combustion Air

Calcium Utilization, %

0

10

20

30

40

50

60

70

SO2 Reduction, %

Ca Utilization

SO2 Reduction

 Figure 7-8. Impact of sorbent air flow rate on the FSI performance. 

7.4.7 Ash Analyses 

Daily ash samples were taken for analysis. The ash mineral content and other ash indices are 

summarized in Appendix A. Loss on ignition (LOI) from the ash analyses is plotted in Figure 

7-9. LOI ranged from 0.5% to 13% for medium to high load with an average of 6.5%. Low 

load tests (76 MWg) conducted on October 2nd (not shown in the plot) yielded an average 

LOI of 16%. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-24 

GE Energy

7.4.8 Mercury Emissions 

This section of the report describes the effect of furnace sorbent injection on mercury (Hg) 

emissions. Figure 7-10 shows the total Hg emission levels with and without FSI as a function 

of unit gross load. Figure 7-10 also shows the total Hg reduction with the load. As shown in 

figure, baseline total Hg emissions ranged widely, from 3.0 to 7.5 μg/m3 at all unit loads. 

During sorbent injection the Hg emission levels decreased to between 0.3 and 1.5 μg/m3. The 

high variation in baseline Hg emissions could be due to changes of several parameters such 

as fuel composition, unburned carbon levels and air heater outlet temperature. The total Hg 

removal with sorbent injection was approximately 80% at all unit loads. 

Figure 7-11 represents Hg emissions as a function of calcium to mercury molar ratio for all 

loads. Mercury reduction increased with increasing sorbent feed rate. One possible 

mechanism for mercury control is direct capture of mercury by the lime sorbent. It is also 

known that SO3 can poison mercury absorption by carbon, so another possible mechanism is

that by capturing flue gas SO3, the sorbent allowed the fly ash carbon to more effectively 

control mercury. 

0

2

4

6

8

10

12

14

16

6/21 7/21 8/20 9/19 10/19 11/18 12/18

Date

LOI, %

Before FSI Test

Preliminary Test

Parametric Test

Long Term Test

Average 6.51%

Figure 7-9. Loss on ignition during the tests. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-25 

GE Energy

7.5 Operating Curves 

After optimizing the FSI system, operating curves were established to integrate into the plant 

DCS to allow operators to run the system 24/7 in automatic mode. The purpose of the 

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 50 100 150 200

Load, MWg

Hg-T, μg/m

3

0

10

20

30

40

50

60

70

80

90

100

Total Hg Reduction, %

 Baseline Hg-T

 Hg-T w ith FSI

 Hg Reduction

Figure 7-10. Mercury emissions as a function of unit gross load. 

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 20 40 60 80 100 120

Ca/Hg-T, 103 lbmol/lbmol

Hg-T, μg/m3

0

10

20

30

40

50

60

70

80

90

100

Total Hg Reduction, %

 Baseline Hg-T

 Hg-T w ith FSI

 Hg Reduction

Figure 7-11. Mercury emissions as a function of Ca/Hg. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-26 

GE Energy

operating curves was to specify the optimized sorbent flow and injection air rate, diverter 

valve position and excess oxygen set point when FSI is in service as a function of boiler 

steam generation. In order to achieve these parameters, a total of four operating curves were 

developed. The four operating curves developed as function of steam flow were as follows: 

• Sorbent flow rate, 

• Injection air, 

• Diverter valve position, and 

• Excess oxygen set point. 

7.5.1 Sorbent Flow Rate 

Figure 7-12 shows sorbent flow rate as a function of steam flow rate at different baseline-SO2

emission levels. The figure is plotted using the data shown in Table 7-9. The Table contains 

calculated sorbent flow rate at Ca/S of 2.5 up to 1200 KPPH of steam, which is 150 MWg 

and above 150 MWg the limit of maximum injection was established from the optimized 

conditions such that opacity levels do not exceed the plant allowable limit. The plant 

allowable opacity limit was 33%, which is 7% lower than the state limit of 40%. 

The plant control system is designed to incorporate either a direct equation or set of data for 

the logic output. Here in this case, Progress Energy opted to use one single set of data at 

baseline-SO2 of 2.2 lb/mmBtu instead of a wide range of baseline SO2 sorbent injection data 

shown in Table 7-9. The sorbent flow rate can also be calculated using Equation 6.1. 

( )( ) ( ) 











= +

S

Ca Sorbent Flow Rate(lb / hr) .1 364 SteamFlow 192.455 baseline SO t arg et 2 6.1 

Where: 

• Steam Flow is in KPPH 

• Baseline SO2 is in lb/mmBtu 

• Target Ca/S ratio ranges from 0 to 3.0 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-27 

GE Energy

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 400 800 1200 1600 2000

Steam Flow, KPPh

Sorbent Rate, lb/hr

SO2 = 1.6 lb/mmBtu

SO2 = 2.0 lb/mmBtu

SO2 = 2.2 lb/mmBtu

SO2 = 2.4 lb/mmBtu

SO2 = 2.6 lb/mmBtu

Max. limit of injection

Load Limit : 1200 KPPH 

Figure 7-12. Sorbent flow rate as function of steam flow. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-28 

GE Energy

7.5.2 Injection Air 

Figure 6-14 shows the injection air control curve as a function of steam flow. As shown in 

Figure 6-14, the injection airflow is linear up to a steam flow of 700 KPPH (94 MWg). 

Above 700 KPPH the injection airflow remains constant at 13,000 CFM. The limit of 

maximum injection air of 13,000 CFM was established because any further increase in 

injection air leads to increase air heater gas outlet temperatures due to air heater energy 

balance, which in turn has a detrimental effect on opacity. However, limiting injection 

airflow, especially at full load, reduces SO2 reduction, which is believed to be due to poor 

TABLE 7-9. SORBENT FLOW RATE AS A FUNCTION OF STEAM FLOW 

Steam Flow Load

KPPH MW g SO2 :1.6 SO2 : 2.0 SO2 : 2.2 SO2 : 2.4 SO2 : 2.6

400 54 2956 3695 4065 4434 4804

450 60 3229 4037 4440 4844 5248

500 67 3503 4378 4816 5254 5692

550 74 3776 4720 5192 5664 6136

600 80 4049 5061 5568 6074 6580

650 87 4322 5403 5943 6484 7024

700 94 4596 5745 6319 6894 7468

750 101 4869 6086 6695 7303 7912

800 107 5142 6428 7071 7713 8356

850 114 5416 6769 7446 8123 8800

900 121 5689 7111 7822 8533 9000

950 127 5962 7453 8198 8943 9000

1000 134 6235 7794 8574 9000 9000

1050 141 6509 8136 8949 9000 9000

1100 147 6782 8477 9000 9000 9000

1150 154 6000 6000 6000 6000 6000

1200 161 6000 6000 6000 6000 6000

1250 168 6000 6000 6000 6000 6000

1300 174 6000 6000 6000 6000 6000

1350 181 6000 6000 6000 6000 6000

1400 188 6000 6000 6000 6000 6000

1450 194 6000 6000 6000 6000 6000

1500 201 6000 6000 6000 6000 6000

Sorbent Injection @ Ca/S of 2.5 up to 150 MWg, lb/hr
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-29 

GE Energy

mixing of sorbent stream with the flue gas. The design injection air at 100% load condition 

was initially supposed to be 19,000 CFM. 

7.5.3 Diverter Valve Position 

The purpose of the diverter valve is to switch sorbent injection from lower to upper injectors 

or vice versa when required. In order to make the control system to shift the location 

automatically, logic was written as a function boiler steam generation. As shown in Figure 

7-13, the diverter valve position remains to lower injectors up to 670 KPPH (90 MWg) and 

above 670 KPPH the logic outputs to switch to upper injectors. The point of shift was 

determined from both parametric and long term testing. The both test data revealed that 

below 90 MWg load, the SO2 reduction was reduced when sorbent was injected from upper 

injectors. Consequently, when sorbent was injected from lower injectors above 90 MWg, 

SO2 reduction dropped about 4% to 5%. 

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

0 50 100 150 200 250

Load, MWg

Injection Air, CFM

Injection Air Curve

Max. Limit : 13,000 

Figure 7-14. Injection air flow rate as a function of steam flow. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-30 

GE Energy

7.5.4 Excess Oxygen Curve 

The other important operating curve when the FSI system is in operation is the excess 

oxygen set point curve. Here as well, Progress Energy opted to use set of data instead of 

curve equation in the control logic scheme. Two excess oxygen set point data sets were 

developed: 1) when FSI in service with coal only and 2) with FSI in service when ROFA is 

in function. The two FSI excess oxygen data set points are based on the injection air curved 

described in the section 6.5.2. These two sets of oxygen set point data are shown in Table 

7-10 along with the baseline excess oxygen levels. 

Since the injection air is added to the total boiler air rather than taking air from burners or 

ROFA, the total excess oxygen set point was needed to increase by about 0.6% at full load 

condition. The increase in excess oxygen leads to reduced boiler thermal efficiency and 

causes increased back-end flue gas temperatures, especially when the injection air is not preheated in the air heaters. Increase in back-end temperature has adverse effect on ESP 

efficiency. For permanent application it is recommended to use either pre-heated ROFA or 

burner air for sorbent injection air so that total combustion air remains constant, however, 

biasing burner or ROFA airflow to the injection air required to evaluate the impacts on boiler 

performance and boiler exit gas emissions such as NOX and CO. 

0 250 500 750 1000 1250 1500

Steam Flow, KPPH

Diverter valve Position

 Low er Injection

 Upper Injection 670 KPPH

upper injectors

Figure 7-13. Diverter valve position as a function of steam flow. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-31 

GE Energy

7.6 Impact of FSI on Boiler 

7.6.1 Ash Deposition 

During FSI injection, a daily walk-down of the boiler was performed to inspect ash 

deposition that resulted from sorbent injection. The inspections were made on the front wall, 

superheater pendants, bottom of the reheat pendants and nose arch from the rectangular 

observation ports that are located on the 6th level at El. 106’-6”. The eight front wall 

observation ports located at equidistance on the front wall were used to see the secondary 

superheater pendants & division wall tubes. The two sidewall ports on either side of the 

sidewall were used to see the front wall, division wall, nose arch and bottom of the reheat 

pendants. Similar to the 6th level ports, there are also 12-observation ports available at the 7th

level at El. 120’, 8 on the front wall and 2 on either side of the side wall, but these ports are 

prone to furnace puffing, hence were not used often. 

No significant evidence of ash deposition was observed on these heat transfer sections during 

the entire program of sorbent injection. There were slight ash deposits observed on the 

TABLE 7-10. FSI EXCESS OXYGEN CURVE AS A FUNCTION OF STEAM FLOW 

Load Steam Flow COAL O2 St. Pt.

COAL/ROFA 

O2 St. Pt.

COAL/ROFA/FSI

 O2 St. Pt.

COAL/FSI O2 

St. Pt.

MWg KPPH 0-10% 0-10% 0-10% 0-10%

0.0 0 7.73 8.00 9.00 8.50

13.4 100 7.40 7.50 8.20 7.70

26.8 200 7.02 7.10 7.80 7.30

40.2 300 6.61 6.70 7.35 6.85

53.6 400 6.00 6.12 7.00 6.50

67.0 500 5.35 5.62 6.50 6.00

80.4 600 4.80 5.09 5.80 5.30

93.8 700 4.35 4.57 5.20 4.70

107.2 800 4.00 4.10 4.60 4.10

120.6 900 3.60 3.63 4.10 3.60

134.0 1000 3.25 3.27 4.00 3.50

147.5 1100 2.90 2.99 3.77 3.50

160.9 1200 2.60 2.80 3.54 3.36

174.3 1300 2.60 2.80 3.49 3.30

187.7 1400 2.60 2.80 3.45 3.26

201.1 1500 2.60 2.80 3.41 3.22
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-32 

GE Energy

secondary superheater pendants and on the backside of the division wall as shown in Figure 

7-14 when sorbent injection rates at high loads were above Ca/S of 1.5. The ash deposits 

were solid flaky particles and not a molten ash. The particles were accumulated over the 

duration of the sorbent injection and formed approximately 10” thick and 24” high in an 8-

hour injection period. These ash deposits were easily manageable with the retractable 

sootblowers located at the nose arch elevation. The sootblowers that were used to remove 

these deposits were IK9, 10, 11, 12, 15 & 16. These sootblowers were used three times in 24 

hours of FSI operation. There were some locations, especially on the backside of the division 

wall, where sootblowers were not able to reach and had signs of ash accumulation during 

high loads but were removed when the loads dropped to minimum due to low furnace 

temperatures. The front wall always appeared to be clean and has no significant ash 

deposition at any time. 

Routine furnace observations were also made from 5th level ports for ash accumulation. 

Some slag buildup was noted on the sidewalls & eyebrows on ROFA ports. It appeared that 

these deposits were typical of normal operation, and were not believed to be caused by 

sorbent because the sorbent was injected at higher elevation. 

Air-heater observations were also made during FSI operation and sorbent accumulations 

were noted in the corners where soot blowers were not able to reach. During the course of 

sorbent injection, air heater sootblowers were continuously in operation to blow off the 

sorbent to avoid plugging. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-33 

GE Energy

Two boiler inspections were conducted to assess the effect of sorbent injection on boiler 

components. The first inspection was performed with a team of four engineers on 10/25/2008 

after one month of sorbent injection. Two team members inspected the boiler backpass and 

airheaters and the other two inspected the ESP. The detailed investigation report of the ESP 

is described in the Section 6.6.4 of this document. The secondary superheater, reheat 

pendants and radiant heat surfaces were inspected from the observation doors. 

The airheater inspection photographs are shown in Figure 7-15. The inspection crew reported 

the airheater appeared normal except few locations especially the corners and outer ring of 

the baskets were found ash deposits. It seems the findings are consistent with the airheater 

differential pressure. Zero to marginal increase in airheater differential pressure was observed 

during sorbent injection. 

Ash Deposition

Width = 10′′

Height = 24 ′′

Observation 

Ports (8)

Figure 7-14. Sketch of ash deposition on secondary superheater and reheat pendants. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-34 

GE Energy

The second inspection was performed on 12/16/2008, approximately two months after the 

first inspection. During this period of two months, sorbent was injected continuously for 24 

hours for most of the days. During this outage only radiant pendants, convective pendants 

and airheaters were inspected. An ESP inspection was not performed. 

The inspection team reported that the radiant and convective pass appeared to be in relatively 

good condition. However, alpha and bravo airheaters were an area of concern. As shown in 

Figure 7-16, the cold air side of the alpha air heater had two to three inches in width of the 

outer baskets plugged and three to four inches deep of cold end corrosion near the center 

baskets. The cold air side of the bravo air heater had a six to eight inches deep of cold end 

corrosion on the center baskets. The reason for the corrosion of the baskets was not fully 

known. 

Figure 7-15. Photographs of airheater inspection. 

Figure 7-16. Inspection photographs of A & B airheaters. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-35 

GE Energy

Primary superheater and primary reheater pendants appeared normal. The inspection 

photographs of these pendants are shown in Figure 7-17. As shown in the pictures, both the 

primary superheater and reheat pendants have slight ash accumulation, which is typical of 

coal-fired boilers. 

An ash deposit sample was also collected from primary superheater pendants for analyses. 

About 3 feet of ash deposit was found on the top of the horizontal run of tubes between the 

up-leg supports and the front convection wall. This was a small area of ash deposits on the 

total convection surface. Deposits were crusty and formed a pyramid shape on top of the 

tube. The analyses of ash deposits were performed at the Progress Energy metallurgical 

laboratory. Representative samples of the lumps of deposit were prepared and analyzed using 

two analytical techniques. An energy dispersive x-ray spectrometer (EDS) attached to a 

scanning electron microscope (SEM) was used for an elemental chemical composition 

characterization. An X-ray diffraction technique was used to determine what types of 

compounds were present in the analyzed deposit samples. The obtained EDS/SEM results 

revealed that the analyzed deposit sample consisted primarily of oxygen, calcium, and sulfur 

(most likely calcium sulfate) with lesser and varying amounts of sodium, magnesium, 

aluminum, silicon, phosphorous, potassium, calcium, titanium, and iron. The iron 

concentration was greater in the pinkish-red layers than those of the pinkish-white layers as 

shown in Figure 7-18. Some of the layers contained more silicon and aluminum. The X-ray 

diffraction analysis results revealed that the analyzed sample consisted of calcium sulfate 

with minor amount of non-crystalline material. 

Figure 7-17. Primary superheater and primary reheat pendants inspection photographs. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-36 

GE Energy

7.6.2 Boiler Performance 

Boiler performance was monitored during each test. Due to the injection of additional air into 

the boiler, the exit O2 increased, which resulted in a boiler efficiency reduction. Figure 7-19 

plots the calculated boiler efficiency as a function of exit O2 for the parametric tests. The 

unfilled symbols are for baseline boiler conditions; the filled symbols are for sorbent 

injection conditions. Results for each test day are plotted in the same color. The results show 

that the boiler efficiency linearly decreases with increase of exit O2 over the load range. For 

the same load tests, the boiler efficiency dropped about 0.1% to 0.8% during sorbent 

injection. The loss in boiler efficiency is mainly from dry gas losses, which is due to increase 

in exit gas temperature and boiler excess oxygen. However, the decrease of the boiler 

efficiency can be minimized by maintaining exit O2 via reducing either burner air or ROFA 

flow. A study of the impacts upon parameters such as CO emissions and tube wastage would 

be required to evaluate potential impacts of reducing burner air upon boiler performance. 

During sorbent injection, small changes in heat absorption were seen, as evidenced by steam 

temperature, attemperation flow rates, or sootblowing requirements. Figure 7-20 shows that 

the main steam temperature increases slightly (about 20oF) with sorbent injections. The 

sorbent injection also did not necessitate any changes in procedures in remove ash from the 

boiler or ESP. 

Boiler NOX emissions also remained unchanged during FSI tests. Even though exit O2

increased with sorbent injection, NOX emissions did not increase as evidenced in Figure 

7-21, since boiler stoichiometric ratio was not disturbed. 

Figure 7-18. Photograph of the ash deposit analysis. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-37 

GE Energy

85

86

87

88

89

90

2 3 4 5 6 7

Exit O2, % wet

Boiler Efficiency, %

180MW Baseline

180MW W ith Sorbent Injection

158MW Baseline

158MW W ith Sorbent Injection

77MW Baseline

77MW With Sorbent Injection

Figure 7-19. Boiler efficiency as a function of exit O2. 

800

900

1000

1100

60 80 100 120 140 160 180

Boiler Load, MWg

Main Steam Temperature, deg. F

Baseline

Sorbent Injection

Figure 7-20. Impact of FSI on main steam temperature as a function of the boiler load. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-38 

GE Energy

7.6.3 Opacity 

The test results from the parametric and long-term tests demonstrated that the FSI system is 

capable of achieving expected SO2 reduction while maintaining minimal impact on boiler 

performance. However, opacity was observed to increase during the sorbent injection and 

was at times a limiting factor during the FSI tests. Figure 7-23 shows a representative group 

of test data obtained on September 29, 2008. With the increase of sorbent feed rate, opacity 

continuously increased throughout the test and reached 25% at the end of the test. 

To better understand and control the opacity increase, dedicated tests and data analyses were 

conducted during the long-term trial. GE applied a Six-Sigma methodology to understand 

and mitigate opacity issues. The potential factors that might cause an increase of opacity are 

related to boiler conditions, ESP performance, sorbent injection and fuel properties. A 

fishbone analysis (Figure 7-24) was used to list all the potential factors. Four groups of 

causes are listed in the chart: Boiler conditions including load, flue gas flow rate, exit O2, air 

heater outlet temperature, dust loading, and ROFA operation; ESP conditions including 

outlet field voltage, inlet field voltage, form factor and rapping scheme; fuel properties; and 

sorbent impact. The study and improvement on ESP performance will be discussed in next 

section. Fuel property impact includes the variation of coal sulfur content. Sorbent impact 

includes sorbent feed rate, sorbent injection location, injection airflow rate and particle size. 

0

0.1

0.2

0.3

0.4

0.5

0.6

0 20 40 60 80 10

0

12

0

14

0

16

0

18

0

20

0

Boiler Load, MWg

NOx, lb/MMBtu

Baseline

Sorbent Injection

Figure 7-21. Impact of FSI on NOX emission. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-39 

GE Energy

During baseline operation, i.e., no sorbent injection, field observation indicated coal sulfur 

content has an impact on opacity. To understand the effect, opacity as a function of baseline 

SO2 emission is plotted as shown in Figure 7-22. The data are grouped according to the 

boiler gross load. The plot shows a trend of opacity decrease as the baseline SO2 emission 

increases. This observation may somewhat contribute to the lower opacity obtained during 

the latter stages of the long-term trial, when higher sulfur coal was fired. However, according 

to results of the regression analysis, coal sulfur content is not a first order parameter 

impacting opacity. 

To better understand the impacts of boiler and sorbent injection parameters on opacity, 

Figure 7-25 to Figure 7-28 plot the opacity as a function of boiler load, flue gas flow rate, 

dust loading, air heater outlet temperature, sorbent feed rate, and sorbent air flow rate. The 

plots indicate that the above parameters have somewhat of an impact on opacity. However, 

these parameters are not independent. For example, the flue gas flow rate increases with load 

and exit O2. To sort out the key parameters that have the most impact on opacity, GE 

performed a regression analysis by using both the average data over a test period and the 

transient one-minute data throughout the test day. The parameters evaluated in the regression 

analysis included boiler load, sorbent feed rate, sorbent air flow rate, air heater outlet 

temperature, ambient temperature, exit O2, flue gas flow rate, baseline SO2 emission and dust 

loading. Both regression analyses identify the air heater (AH) outlet temperature as a 

0

5

10

15

20

25

30

35

40

1 1.5 2 2.5 3 3.5

Baseline SO2, lb/MMBtu

Opacity, %

180 - 185 MWg

160 - 170 MWg

150 - 160 MWg

130 - 150 MWg

100 - 130 MWg

< 100 MWg

Figure 7-22. Opacity as a function of SO2 emission at baseline conditions. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-40 

GE Energy

dominant factor for opacity increase. Figure 7-29 plots the opacity as a function of the air 

heater outlet temperature for all parametric tests. The data follow a consistent trend, which 

indicates a strong relationship between the opacity and the AH outlet temperature. When the 

AH outlet temperature is greater than 270oF, the opacity increases exponentially. 

A second regression analysis was conducted to find out the causes for AH outlet temperature 

increase during the course of sorbent injection. The parameters included in the analysis were 

sorbent feed rate, flue gas flow rate, exit O2, sorbent airflow rate and ambient temperature. 

The analysis identified two parameters other than load are the leading factors for the increase 

of AH outlet temperature. One is the ambient temperature. During a typical testing day, the 

ambient temperature starts rising in the morning and increases about 20oF in the afternoon. 

As the ambient temperature increases, the AH outlet temperature increases accordingly, even 

at steady boiler operating condition. It was also observed that as the test program moved to 

the fall and winter, the ambient temperature was lower than that in the beginning of the test 

phase. The air heater outlet temperature and opacity were lower in the cooler fall weather 

than in the summer. The second important factor is the sorbent injection air. The addition of 

5% total air to the furnace increases the flue gas flow rate through air heater and therefore 

increases the gas temperature at the outlet of the air heater. 

Based on the analysis, at the later stage of the long term testing, the sorbent injection air flow 

rate was maintained at 13,000 ACFM or lower. Meanwhile with a cooler ambient 

temperature, the opacity issue was eased. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-41 

GE Energy

Figure 7-23. Sample data on September 29, 2008 showing opacity increase. 

 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-42 

GE Energy

ESP Performance

Sorbent Impact

Sorbent Feed Rate

Boiler Condition

Exit O2 Change

Flue Gas Flow Rate Increase

Fuel Properties

Ash Content

Sulfur Content

Mineral Content

AH Outlet Temperature Increase

Opacity Increase

Boiler Load

Moisture Content

Sorbent Feed Location

Injection Air Flow Rate

ROFA Impact

Inlet Field Voltage

Outlet Field Voltage

Form Factor

Rapping Scheme

Particle size

Dust Loading

Figure 7-24. Fish bone analysis for causes of opacity increase. 

 

0

5

10

15

20

25

30

0:00 4:48 9:36 14:24 19:12

Time

Opacity, %

Ca/S=0, 155 MW

Ca/S=0.8, 155 MW

Ca/S=2.2, 155 MW

Ca/S=2.6, 155 MW

Ca/S =0, 77 MW

Ca/S = 0.97, 77 MW

Ca/S=1.94, 77 MW

Ca/S=2.02, 77 MW

Ca/S=2.0, 77 MW

Figure 7-25. Impact of load on opacity. 

 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-43 

GE Energy

0

5

10

15

20

25

30

35

1550 1600 1650 1700 1750 1800

Flue Gas Flow Rate, lb/hr

Opacity, %

09/15 Clean Air Test

Figure 7-26. Impact of flue gas flow rate on opacity. 

0

5

10

15

20

25

30

35

0 5000 10000 15000 20000 25000 30000

Dust Loading, lb/hr

Opacity, %

Figure 7-27. Impact of dust loading on opacity. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-44 

GE Energy

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6

Exit O2, %wet

Opacity, %

09/29, Baseline

10/01, Baseline

09/29 Vary Sorbent Flow

10/01 Lower Injection

Figure 7-28. Impact of exit oxygen on opacity. 

0

5

10

15

20

25

30

35

40

200 220 240 260 280 300

Air Heater Outlet Temperature, deg. F

Opacity, %

Baseline

09/29 Vary Sorbent Flow

09/30 Vary Injection Air

10/01 Lower Injection

10/02 Low Load

10/03 ROFA OFF

77 MW g 158 MWg

Figure 7-29. Impact of air heater outlet temperature on opacity. 

7.6.4 ESP Performance 

As reviewed in Section 6.2, the predicted ESP performance during FSI operation would 

result an opacity increase from an average of 6.1% to 16% at a sorbent injection rate of 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-45 

GE Energy

11,700 lb/hr, a factor of 2.6 increase. The ESP performance tests during September show that 

after initiating sorbent injection, opacity increased steadily from about 19% to over 30%, a 

factor of 1.6 increase (although opacity was still increasing). Actual opacity readings during 

FSI operation were found to be highly dependent upon baseline opacity and flue gas 

temperature in the ESP. 

The opacity increase occurred when the load was experiencing a small increase. Unit load 

increased from about 159 MW to about 173 MW over the four-hour period. This 10% change 

would account for an increase in the gas volume treated by the electrostatic precipitator. 

Stack gas temperature also increased gradually over the test period. The initial stack 

temperature was about 259oF at the beginning of the test and increased to about 277oF at the 

end. This represents an increase of about 18oF. Based on the predicted dust resistivity, the 

temperature change represents one half order of magnitude increase in dust resistivity. The 

dust resistivity does not appear to increase to unacceptable levels, but an increase in 

resistivity is associated with a decrease in collection efficiency. The ESP outlet temperature 

showed an increase on the “A” side from 258oF to 270oF and the “B” side from 249oF to 

256oF. Neither side showed the magnitude of temperature increase exhibited by the stack 

temperature. 

If gas flow, temperature, dust loading, and internal conditions are equivalent between the east 

and west chambers, their electrical characteristics would be expected to be the same. It would 

also be expected for the spark rate to decrease and the secondary current to increase when 

progressing through the electrical fields. From the data it can be seen that the secondary 

current does not increase appreciably from the A to B fields. In addition, the spark rate is 

relatively constant from the A to B fields. This indicates that the dust loading is not 

decreasing significantly from the first to second electrical field. 

Current densities start out at strong values then degrade to minimum values for the duration 

of the test. Generally when the secondary current degrades over time, it is an indication of 

increasing dust layer thickness or possibly increased resistivity of the dust layer. 

Based on the electrical trends gathered during sorbent injection, several recommendations 

were made: 

• Perform air load and gas load VI curves to define the corona onset voltage and the 

relationship between secondary voltage and secondary current. The data does not show 

indications of back corona, but the VI curve can be used to confirm the data. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 7-46 

GE Energy

• Revise the collecting plate rapping program on the A, B, and C fields to decrease the 

cycle time and increase force. The gradual decline in secondary current indicates that dust 

is building up at a rapid rate. Rapping more aggressively can reduce the build up rate and 

maintain acceptable conditions for a longer period of time. 

• Consider reduced power rapping for the A and possibly B collecting fields. The power 

reduction will make rapping more effective, but possibly increase re-entrainment of dust 

during the cycle. Initially, the power can be reduced to about 50% of nameplate when the 

A field raps and 70% of nameplate when the B field cleans. Instantaneous and average 

opacity should be monitored to define the impact of reduced power rapping. The impact 

of reduced power rapping should also be reviewed on the C and D fields. 

• The spark rate exhibited in the West chamber is higher than the East chamber. It should 

be verified that comparable gas volumes are reaching each chamber. 

• The fact that the C field does not show a significant change in secondary current and that 

the spark rate increases dramatically indicates that rapping may be too aggressive. 

Review the C field program and consider decreasing lift height or increasing cycle time. 

• Similarly, the D and E fields show an increase in secondary current during sorbent 

injection. This may indicate that the rapping program is too aggressive. Decreasing the 

rapping may reduce dust re-entrainment. 

• The F field does exhibit a decrease in secondary current during sorbent injection. This 

indicates that the rapping program can be modified to increase lift height and decrease 

cycle time. 

• Fields C, D, E. and F are all secondary voltage limited. The current density associated 

with the applied secondary voltage is very low. Increasing the secondary voltage 

nameplate rating would increase current density. Increased current density reduces dust 

re-entrainment and improves particle removal efficiency.

• During the next opportunity for an internal review, inspect the C and D fields for a close 

clearance. The high spark rate observed in these fields may be related to an internal 

clearance in addition to the increased dust burden.
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-1 

GE Energy

8.0 Recommendations for System Improvements 

8.1 Sorbent Injection System 

While the FSI demonstration system generally met performance expectations, a series of 

system modifications and upgrades can be suggested to improve system performance and 

boiler operability for a permanent application. The basis for the trial system was for the 

sorbent air to add to the total boiler air. That is, as sorbent injection air was added, a 

proportionate amount of air was not reduced from other boiler input streams. Therefore, 

furnace oxygen concentration and flow rate increased during FSI operation. This caused 

boiler thermal efficiency to decrease, back-end system temperatures to increase, and ESP 

collection efficiency to decrease. For permanent application it is recommended to reconfigure 

the system such that total air flow rate remains constant during FSI operation. The sorbent air 

could potentially be taken either from the burner air or from the ROFA air. Such an action 

would require a study of burners and other system components to define the range of 

allowable operation and to evaluate any impacts upon other species such as NOX and CO. 

Furthermore, SO2 reduction was observed to increase with increasing sorbent air, which is 

believed to be due to better mixing between the sorbent stream and the furnace gas. This 

result suggests that increasing either the total sorbent air or the momentum of the sorbent air 

stream (by increasing stream velocity) could lead to higher levels of SO2 reduction. For 

permanent application, the injection system design can be reviewed in the context of the test 

results to quantify costs and benefits of either adding more sorbent air or increasing the 

sorbent stream velocity. 

From an operational standpoint, several relatively minor issues were noted with the FSI 

system. Feeding from a silo proved difficult throughout the test project. This may be due to 

the fact that sorbent was stored for a long period of time in the silo, and may have gotten wet 

or otherwise agglomerated. A detailed cleaning of the silo is recommended. Also, the 

reinforced rubber sorbent transport hoses experienced erosion problems just downstream of 

the splitter. The splitter outlet hose barbs had smaller diameter than the hoses, which is 

believed to have caused a region of high velocity and flow recirculation, leading to erosion. It 

is recommended to change this configuration such that the diameter of the hose barbs is close 

to that of the hose. This would alleviate the issue with high velocity and erosion. Hard pipe 

could also be considered for high-erosion areas. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-2 

GE Energy

Additional recommendations from the testing team if the FSI were to be operated on a long 

term or continuous basis include: 

1. Sorbent Injection Hoses – the current hoses would not be suitable for long term 

operation. They erode and leak. The majority of the problem occurs close to the 

distribution header but has been observed in other areas as well. The feed hoses could 

be redesigned to allow service air to be blown through plugged lines. 

2. FSI Controls – This area gave the most difficulty during the testing and continuous 

operation of the system. 

a. The PLC has communication issues and crashed repeatedly during testing. It 

would lock up with no remote alarm and require rebooting. 

b. There are several routine functions which could only be done at the HMI

station. Examples of this are putting the system in Maintenance Mode to 

manually fluidize silos when the sorbent is not feeding properly. All of the 

remote functions should be accessible to the control operator. 

c. The Loss In Weight and Volumetric modes of Sorbent Feeder control need 

revamping. The system uses LIW as the normal control method and then

defaults to volumetric when the weigh hopper is filling. The variation in flow 

caused by the change in density and the consistency of the material often 

caused the system to transfer to the volumetric mode at an excessively high or 

excessively low feed rate. This feed rate was locked in until the weigh hopper 

was full. This caused large variations in the sorbent flow and caused the 

operator to be conservative in the maximum feed rate, especially during high 

loads with high opacities. The system needs to have a characterized curve for 

the volumetric flow that would allow it to set feeder speed during the fill cycle 

on the characterized feed rate vs. the current set point. This would reduce the 

variation in sorbent feed. 

3. Sorbent Silos- Need to add fluidizing air rings or vibrators at several levels of the 

cone. Flow of the sorbent from these silos was a continuous issue especially when 

trying to run the silo empty. The possibility should be considered of installing a 

grinder on the discharge of the day bin discharge valve to eliminate any clumping 

before it enters the airlock valve. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-3 

GE Energy

4. DFA Controls – Need the same functions available to the operator as is available at 

the remote HMI. Several logic changes need to be made concerning the flushing and 

shutdown cycles. The operator should be able to interrupt the shutdown cycle. 

8.2 Boiler Deposit Management System 

In previous FSI projects, significant problems were encountered with particulate matter 

deposition in the upper furnace. In the most severe instances, fouling deposits actually 

bridged the spacing between tubes and caused a boiler shutdown. In the current project, 

deposit management studies were performed that developed a series of recommendations, 

including restoring existing sootblowers to design operating conditions, installing new 

sootblowers, and installing sonic horns to control ash-sorbent deposits in the upper furnace. 

These upgrades were coupled with an Intelligent Sootblowing system furnished to Progress 

Energy by Emerson. This system effectively managed furnace deposits during the FSI trial. 

For Robinson Unit 1, no further upgrades are suggested. For application to other units, a 

case-by-case review would be required to develop recommendations for deposit 

management. Based on the experience at Robinson, it is anticipated that a combination of 

sootblowers and sonic horns would be recommended, potentially with the addition of pulse 

detonation technology such as the GE Powerwave process to provide more aggressive 

cleaning. In future applications it is also recommended to place more emphasis on air 

preheater cleaning, both to optimize thermal efficiency and to reduce flue gas temperature, 

which would have benefits on ESP performance. 

8.3 Electrostatic Precipitator 

The methodology for the trial was to make sufficient ESP upgrades to allow the tests to be 

completed. Opacity proved to be a limiting factor in allowable sorbent flow rate under certain 

conditions, and therefore more extensive PM control upgrades might be needed for 

permanent application of the FSI technology. As shown in Figure 7-22, baseline opacity 

values during the trial ranged widely, from 2% to 27%, and generally increased with 

increasing boiler load. As described in Section 6.2, the performance projection was for 

opacity to increase by approximately a factor of 2.6. Actual opacity readings during FSI 

operation were found to be highly dependent upon baseline opacity and flue gas temperature 

in the ESP. 

GE personnel accompanied Progress Energy personnel on an ESP inspection during a 

weekend outage on October 25, 2008. Detailed findings and recommendations were

presented in a memo issued by GE Technical Advisor Doug Wamble. In summary, a series 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-4 

GE Energy

of mechanical repairs are recommended such as centering rapper anvils, replacing bowed 

discharge electrodes, and installing anti-sway insulators. These recommendations would 

improve ESP performance and reduce maintenance requirements, but would likely have only 

nominal impact upon opacity and PM emissions. 

Based on a review of ESP electrical conditions during FSI, an analysis and series of 

operating recommendations was also developed by Bob Taylor of GE and summarized in a 

memo dated October 13, 2008. Some of the recommendations made, such as changing 

secondary voltage limits on the four new inlet field transformer rectifier sets to nameplate 

rating, were performed during the test work. An additional measure that is recommended for 

permanent application is to implement an FSI-specific rapping program. Specifically, it is 

recommended to revise the collecting plate rapping program on the A, B, and C fields to 

decrease the cycle time and increase force. The gradual decline in secondary current indicates 

that dust is building up at a rapid rate. Rapping more aggressively will reduce the build up 

rate and maintain acceptable conditions for a longer period of time. An assessment would be 

required as to the impacts of increasing rapping force upon ESP maintenance and life cycle. 

The upgrades listed above would be expected to provide nominal improvements to ESP 

performance, and more extensive measures would likely be needed for permanent FSI 

application. A listing of options, approximately ranked from least to most expensive, is as 

follows: 

• Humidification. A humidification system would consist of a series of atomization nozzles 

to spray water into the ductwork upstream of the ESP. Through evaporative cooling the 

system would reduce gas temperature, reduce dust resistivity, and reduce flue gas 

volume. Each of these effects would have a beneficial impact upon ESP operation. With 

such a system it would be necessary to ensure complete evaporation, since interactions 

between sorbent byproducts and liquid water could generate cement-like deposits. 

Evaluation of duct gas flow and temperature patterns is recommended to define the 

optimum design of humidification lances. 

• ESP Field Addition. An inlet field could be added to the Robinson ESP. While further 

validation would be needed, GE’s preliminary technical assessment indicated that inlet 

field addition would roughly cut PM emissions and opacity in half. Significant cost 

would be involved with field addition. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-5 

GE Energy

• Fabric Filter: A conventional fabric filter or advanced system such as GE’s Max-9 

electrostatic fabric filter could be installed to replace the existing ESP. Along with 

facilitating FSI operation, this approach might also be of interest relative to potential 

future PM2.5 regulations. 

• Ash Dropout Box. A louver plate system could be installed upstream of the ESP, using 

inertial separation principles to act as a pre-collection device. One potential issue to be 

considered is the spatial requirement for such a system. An initial assessment of a 

dropout system at Robinson revealed difficulty in installing the system in the available 

space. Another issue is that as an inertial separation system, the dropout box would 

preferentially remove larger flyash particles rather than finer sorbent particles, and thus 

the burden of fine, high-resistivity particles to the ESP might remain high. Nevertheless, 

for sites that have adequate installation space the dropout box would potentially merit 

consideration. 

8.4 Byproduct Management System 

A dry ash management system was installed at Robinson prior to the FSI trial. This system 

generally worked as intended for the duration of the project. For purposes of the trial, the 

flyash-spent sorbent byproduct material was disposed in a landfill. For permanent FSI 

application, it is recommended to consider using the byproduct material as an input stream to 

the manufacture of construction materials. While potentially providing economic benefits, 

the viability of a beneficial reuse application is highly dependent upon the existence of an 

available market near the plant. One reuse approach would be to use the byproduct to make a 

low-strength aggregate material. This would be a simple approach involving grinding, 

hydration, addition of stabilizers, and compaction into bricks or briquettes. The treatment 

process could be performed either on-site or at a remote location. The resulting product 

would be a low-strength aggregate that would be suitable for applications such as roadbed 

fill. 

Another alternative for byproduct management would be to use the material as an input to 

concrete manufacture. Two of the main input materials to cement manufacture are flyash and 

CaO. Table 8-1 summarizes the composition of the Robinson coal flyash, flyash-spent 

sorbent byproduct, a byproduct-CaO blend, and Portland cement. It can be seen that the 

byproduct CaO blend bears strong similarities to Portland cement. Therefore, for a permanent 

FSI application it is recommended to evaluate the potential to ship the flyash-sorbent 

byproduct to a cement plant to be reused. Such an approach could have a significant effect 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 8-6 

GE Energy

upon overall FSI process economics by converting a cost stream into a neutral or value 

stream. While the above options could prove to be an economic benefit it must be recognized 

that such benefit is highly dependent on the presence of a viable market. Assessment of the 

market potential in the area of the Robinson plant is outside the scope of the current study. 

TABLE 8-1. COMPOSITIONS OF FLYASH, SORBENT BYPRODUCT, AND 

PORTLAND CEMENT 

Component 

(wt%) 

Typical 

Bituminous Fly 

Ash* 

Robinson Coal 

Fly Ash 

Nominal FlyashSorbent By 

Product 

Ash-Sorbent 

+CaO Blend** 

Portland 

Cement*** 

SiO2 20 – 60 53.5 35.5 17.7 20.3 

Al2O3 5 – 35 23.9 15.8 7.9 4.3 

Fe2O3 10 – 40 7.0 4.6 2.3 2.6 

CaO 1 – 12 1.2 26.9 63.6 63.6 

MgO 0 – 5 1.0 0.9 0.5 2.2 

K2O 0 – 3 2.3 1.5 0.7 Not specified 

Na2O 0 – 4 0.3 0.2 0.1 0.2 

SO3 0 – 4 0.2 0.1 0.1 Not specified 

CaSO4 Not specified 0.0 6.5 3.3 Not specified 

Unburned C 0 – 15 8.0 5.3 2.6 < 3.0 

Other Not specified 2.6 2.6 1.3 Not specified 

* From US Department of Transportation specifications. 

** Blend of 50% flyash-sorbent byproduct with 50% CaO. 

** *Type 1 Portland Cement from DOE Coal Utilization By-Product Report, August 2006. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-1 

GE Energy

9.0 Future FSI Application 

9.1 FSI Technology Viability 

The FSI trial program at Robinson generally met technical and programmatic objectives. 

Reduction of SO2 was approximately 45% - 50% at a Ca/S ratio of 2.5. Notably, no 

technology show-stoppers were encountered. Boiler deposits were effectively managed 

during FSI operation. While opacity was high under certain conditions, ESP performance 

was adequate for the purposes of the trial, and further PM control upgrades can be made to 

facilitate a permanent FSI application. The byproduct material was effectively handled by the 

dry ash system. No safety or environmental problems were encountered during the trial. In 

summary, all process subsystems worked as intended during the FSI test program. Since no 

technical flaws were revealed for the FSI technology, the viability of the technology for a 

given boiler is largely a function of the following factors: 

• Cost effectiveness. The dominant factor in assessing overall net cost of the FSI process is 

sorbent cost, as described in more detail in section 9.3. 

• SO2 control requirements. FSI is capable of providing approximately 50% SO2 control, 

and thus is best suited to a regulatory framework that requires moderate control and/or 

plant-level control. 

• Boiler size. Other SO2 control technologies such as wet or dry FGD systems have greatly 

higher capital cost than that of FSI. Furthermore, on a $/kW basis, FGD system cost 

increases with decreasing boiler size. A 2007 scrubber benchmarking study by the EUCG 

estimated wet FGD capital costs of $444/kW for units less than 300 MW, as compared to 

$315/kW for units in the 300-600 MW range (reference). FSI is potentially a lower 

capital cost technology depending on upgrades required for PM control (dictated by air 

permit modification) and might be favored for smaller boilers (i.e., less than 300 MW) 

for which an FGD system might be cost prohibitive. 

• Project life cycle. FSI is a lower capital cost technology and therefore is favored for 

shorter project life cycles, where the high capital cost of a technology such as FGD might 

not be justified. 

• Multipollutant control requirements. FSI can control SO3, HCl, and mercury along with 

SO2. Specifically, approximately 80% mercury control was achieved during the Robinson 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-2 

GE Energy

trial. Regulatory requirements and technology capabilities to control these species, along 

with PM, arsenic, selenium and other species of concern, need to be considered in 

defining an overall emissions control strategy. It is noted that wet and dry scrubbing 

technologies can also provide some level of multipollutant control. 

Regulatory requirements for emissions control also directly impact the potential viability of 

the FSI process. The previous CAIR provisions allowed for a cap-and-trade approach to 

emissions control on a National level. Future regulations may or may not include cap-andtrade provisions. Any regulations that require plant-level control improve the viability of low 

capital cost, moderate control technologies such as FSI, particularly for small to medium size 

boilers where wet or dry FGD systems may be cost prohibitive. 

9.2 FSI Performance Projections 

To accurately project SO2 control for a given boiler it is necessary to study boiler 

temperature profile, gas flow field, coal composition, and injector accessibility, as well as to 

define constraints with regard to allowable sorbent and air flow rates. Such a study was 

performed during the initial stages of the Robinson project, and should be repeated for other 

boilers of interest. Nevertheless, results from the Robinson trial can be used to make general 

performance assessments and projections. Robinson Unit 1 is a 188 MWg tangentially fired 

boiler that fires low sulfur bituminous coals. SO2 control at Robinson was approximately 

45% - 50% at a Ca/S ratio of 2.5. While site-specific assessment is needed, performance 

would generally be expected to be in this range for similar boilers, such as Cape Fear Unit 5 

or 6. 

Coal sulfur content is one of the primary factors defining FSI performance. For a given Ca/S 

ratio, SO2 reduction generally increases with increasing coal sulfur content (i.e., sorbent 

utilization increases with increasing coal sulfur content). At the same time, higher sulfur 

coals also require more sorbent on a mass flow basis, which can impact boiler deposition and 

PM control device performance. Figure 9-1 provides a curve of SO2 reduction as a function 

of coal sulfur content at a Ca/S ratio of 2.5. This curve is based on GE’s database of FSI 

performance results. The range of data obtained at Robinson is shown for comparison. Figure 

9-1 can be used to roughly estimate FSI performance for different coal sulfur contents, 

although it is noted that boiler-specific process engineering studies are require for accurate 

projections. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-3 

GE Energy

0

10

20

30

40

50

60

70

80

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Coal S, %dry

SO2 Reduction, %

Approximate Range of 

Performance at 

Robinson

Ca/S = 2.5

Figure 9-1. Projected FSI performance as a function of coal sulfur content. 

9.3 FSI Cost Effectiveness 

As described above, compared to other SO2 control technologies such as wet FGD, the FSI 

process has much lower capital cost, but also higher operating cost due to less effective 

utilization of the sorbent material. FSI is generally most advantageous for: 

• Smaller boilers 

• Shorter life cycles 

• Moderate SO2 control levels (up to 60%) 

• Multi-pollutant control (SO2, SO3, HCl, and mercury) 

• Plant-level emissions control requirements as opposed to regional requirements that have 

cap-and-trade provisions 

In developing the overall net cost of SO2 reduction, factors that need to be considered 

include: 

• Project capital cost 

• Project amortization life 

• Sorbent unit cost, including sorbent utilization and required feed rate 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-4 

GE Energy

• FSI operating labor cost 

• FSI utilities cost 

• Impacts upon boiler thermal efficiency and cost of power generation 

• Maintenance cost 

• Byproduct disposal cost (or income if recycled) 

• Value of any emission reduction credits generated 

A detailed review of these parameters is needed to determine the cost effectiveness of the FSI 

process on a site-specific basis. To place a lower boundary on the FSI cost of SO2 reduction, 

the sorbent cost alone can be evaluated based on results of the Robinson trial. For the range 

of conditions tested, typical SO2 control at a Ca/S ratio of 2.5 was approximately 47%, 

corresponding to a sorbent utilization of 18.8%. Assuming a delivered sorbent cost of 

$110/ton and 95% sorbent purity, sorbent cost to remove one ton of SO2 is as follows: 

( )

2

2

2

2

47.6 1

95%

1

18 8. %

1

64

74

1

ton Sorbentrequired to remove ton SO

SorbentUtilization Purity lbmol SO

lbm

lbmolCa OH

lbm

ton SO

=

⋅ ⋅ ⋅

2

$712 cos

$110 16 47. sorbent tot remove one ton SO

ton sorbent

ton sorbent ⋅ =

This value provides an estimate of FSI cost for the sorbent component only. Estimation of 

overall process cost requires evaluation of the set of factors listed above. 

9.4 FSI Schedule 

The FSI development work performed by GE and Progress Energy was not conducted in a 

directly linear fashion, for example the project basis shifted from Cape Fear Unit 5 to 

Robinson Unit 1. Nevertheless, the FSI experience at Robinson can be used to estimate 

schedule requirements for a permanent FSI installation. For purposes of schedule estimation, 

it is assumed that the task structure will be similar to that of the Robinson project, that 

nominal ESP upgrades will be made rather than field addition or baghouse installation, and 

that the existing ash management system will be retained. Given these assumptions, 

estimated project phases and durations are as follows: 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-5 

GE Energy

• Phase 1. Failure Modes & Effects Analysis, Pilot-Scale Testing, and Process Design: 3 

months 

• Phase 2. Detailed Engineering Design and Specification Development: 6 months 

• Phase 3. FSI System Procurement and Installation: 12 months 

• Phase 4. Commissioning and Equipment Performance Tests: 3 months 

• Phase 5. System Documentation and As-Built Drawings: 3 months 

Therefore it is estimated that approximately 27 months would be required for a complete 

project. Duration would be extended significantly if a baghouse installation or major ESP 

modifications were required. It is also noted that the installation work would need to be 

integrated with a boiler outage. 

9.5 Application of FSI to Other Boilers 

While well suited to tangentially fired boilers due to good furnace mixing, the FSI process 

can be applied to a wide range of boilers. In past applications, GE has applied FSI to 

pulverized coal-fired boilers with tangential, wall, and cyclone firing configurations. The 

primary technology requirement is to have boiler access for injectors, spatial availability for 

equipment, and sufficient residence time for sorbent sulfation in the optimum furnace gas 

temperature window of approximately 2100 – 2200 oF. Parameters impacting the viability of 

applying FSI to a specific boiler include: 

• Coal sulfur concentration: Higher sulfur coals have higher SO2 reduction for a given Ca/S 

ratio, but also require a higher sorbent mass flow rate. 

• Boiler design and furnace flow field characteristics: Stratifications in furnace gas 

temperature and composition can impact mixing between the sorbent stream and the 

furnace gas. 

• Boiler access for sorbent injectors in the optimum temperature window: Optimum FSI 

performance is typically obtained at an injection temperature of 2100 – 2200 oF. If the 

boiler does not have access for injectors in the temperature range, FSI performance may 

be degraded. Multiple injector elevations may also be required to accommodate different 

boiler loads. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-6 

GE Energy

• Availability of space at the plant to locate FSI equipment: Major equipment includes 

sorbent silos, a day hopper, feeder equipment, and blowers. Truck or rail access is also 

required for sorbent delivery. 

Other plant factors also impact the cost effectiveness of FSI at a given plant. These factors 

include ESP design and specific collection area, ash handling system design and capacity, 

ash pond capacity (if wet ash management is utilized), and upper furnace ash deposit 

management system design. The parameters require plant-specific evaluation to evaluate FSI 

performance and cost for a given boiler. 

Regarding specific application of FSI to other Progress Energy boilers, boilers of potential 

interest are Cape Fear Units 5 and 6. Before the current project settled upon Robinson Unit 1 

as the FSI application site, GE performed an initial assessment of FSI application to Cape 

Fear Unit 5. This unit is slightly smaller than the Robinson boiler, but has many design 

similarities. Cape Fear Unit 5 is a 165 MWg, four-corner tangentially fired boiler that is 

located in Moncure, NC. The unit was installed by Combustion Engineering in 1957. It is 

equipped with four levels of burners. Similar to Robinson Unit 1, Cape Fear Unit 5 is 

equipped with a ROFA system, a cold-side ESP, and fires eastern bituminous coals from the 

Fola and Camp Creek mines. As summarized in Table 9-1, these coals have similar analyses 

to the Robinson coals. Therefore, in terms of furnace gas flow field characteristics and 

furnace gas sulfur levels, Cape Fear 5 is similar to the Robinson boiler. While more detailed 

evaluation of sootblowers, the ESP, and the ash management system would be required to 

accurately estimate total FSI project costs and performance, in general FSI performance at 

Cape Fear Units 5 and 6 would be expected to be similar to that obtained at Robinson. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 9-1 

GE Energy

TABLE 9-1. COMPARISON OF CAPE FEAR AND ROBINSON COAL PROPERTIES 

Boiler Coal ID SO2

 (lb/MMBtu) Ash 

(% dry)

Cape Fear Unit 5 Fola 1.5 13.50%

Cape Fear Unit 5 Camp Creek 1.29 10.30%

Robinson Unit 1 Minimum from trial* 1.36 9.90%

Robinson Unit 1 Maximum from trial* 2.67 14.60%

* Minimum and maximum values from daily coal analyses performed during 

FSI trial, October-December 2008
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 10-1 

GE Energy

10.0 Conclusions 

The FSI project was designed to provide a basis for technology evaluation as a potential 

means of meeting upcoming regulations. Specific technical objectives of the project were as 

follows: 

• To achieve 40%-50% SO2 reduction, 

• To effectively manage furnace and convective pass deposits, allowing the FSI system 

to be operated for an extended period of time with manageable impact upon boiler 

efficiency and without causing boiler shutdown, 

• To meet air permit requirements for PM emissions and opacity, 

• To effectively and safely manage byproduct materials, and 

• To provide process data to allow an accurate assessment of the feasibility of the FSI 

technology. 

The primary focus of the project was to reduce SO2 emissions from the Robinson boiler. 

Other technical objectives were to maintain boiler operability, to comply with air permit 

requirements, to effectively manage byproducts, and to define impacts upon emissions of 

other species, notably NOX and mercury. Primary measurements and performance indicators 

included stack CEMS measurements for SO2, O2, CO2, NOX and mercury, stack opacity, unit 

temperatures and steam conditions, boiler load and heat rate, burner tilts, ROFA conditions, 

and sorbent feed rate. 

The test work revealed that SO2 reduction levels were generally consistent with projections 

made during the Process Design phase of the project. At the design Ca/S ratio of 2.5, SO2

reduction ranged from approximately 40% to 55%. The highest SO2 reduction achieved 

during the long-term trial was 71.6%, at a Ca/S ratio of 3.8. 

Regarding dependence of system performance upon operating parameters, SO2 reduction 

increased with increasing sorbent injection air flow rate. This is attributed to improved 

mixing between the sorbent and furnace gas. The system was configured such that increasing 

sorbent air caused overall furnace gas flow rate and oxygen concentration to increase, 

decreasing boiler efficiency and causing opacity to increase. Therefore, for the scope of the 

demonstration project it was not feasible to maximize sorbent air for all test runs. However, 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 10-2 

GE Energy

system modifications could be made to allow sorbent air to be maximized for potential 

permanent application. 

It was found that SO2 reduction was higher at low load than at full load. This is attributed to 

better sorbent-furnace gas mixing, as the sorbent stream can more readily penetrate the 

furnace flow field when overall furnace flow rates and velocities are lower. FSI system sulfur 

reduction was slightly better with ROFA on than with ROFA off, although the effect was 

small. This is consistent with the system design basis, which involved optimizing 

performance with ROFA on. 

Regarding boiler performance during FSI operation, furnace deposits were found to be 

manageable by the unit sootblower/sonic horn system. While upper furnace deposits were 

visually observed to increase during FSI operation, the deposits could be readily removed by 

operating the sootblowers and sonic horns. Boiler thermal efficiency decreased slightly 

during full load FSI operation. However, most of this effect is attributed to the increased air 

flow rate associated with FSI operation. For permanent application, system modifications 

could be made to maintain constant total air flow rate during FSI. 

Opacity and particulate matter emissions increased during FSI operation. This effect was 

expected, since FSI increases fly ash mass loading and resistivity and decreases mean particle 

size. The plant’s opacity limit is 40%, and the guideline during the project was to reduce FSI 

operation when opacity exceeded 35%. At certain full load conditions, opacity limited the 

amount of sorbent that could be injected into the boiler. The single most important parameter 

upon opacity was found to be ESP gas temperature. The extra air associated with FSI 

operation caused ESP temperature to increase, leading to an increase in opacity. Lower boiler 

loads and sorbent air flow rates led to low ESP temperatures and lower opacity readings. 

Also, the test work began in summer and concluded in late fall. It was found that as ambient 

temperatures decreased through the fall, ESP temperatures and thus opacity decreased. 

In general, results of the test project indicated that FSI was able to achieve the target level of 

SO2 reduction while allowing boiler operability to be maintained. Fouling deposits were 

effectively mitigated using the upgraded sootblower-sonic horn system that was installed for 

the project. The FSI technology has the potential to be successfully applied to a range of 

boiler types and fuel specifications. Ultimate decision as to the best SO2 control technology 

for a specific boiler is dependent upon regulatory requirements, boiler size, project duration, 

and plant financial considerations. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 11-1 

GE Energy

11.0 References 

[1] GE Energy and Environmental Research Corporation; Progress Energy Robinson Unit 1 

Furnace Sorbent Injection Project: Design Basis Memorandum, Rev. 1; 1 March 2007; 

Santa Ana, CA. 

[2] GE Energy and Environmental Research Corporation; Progress Energy Robinson Unit 1 

Furnace Sorbent Injection Project: Process Design Report, Rev. 0; 6 April 2007; Santa 

Ana, CA. 

[3] GE Energy and Environmental Research Corporation; Progress Energy Furnace Sorbent 

Injection FSI Equipment Performance Test Plan, Rev. 0; 7 March 2008; Santa Ana, CA. 

[4] GE Energy and Environmental Research Corporation; Progress Energy Robinson Unit 1 

Furnace Sorbent Injection Project: Sorbent Injection Test Plan, Rev. 5.0; 27 August 

2008; Santa Ana, CA. 

[5] GE Energy and Environmental Research Corporation; Progress Energy Furnace Sorbent 

Injection Splitter Test Report, Rev. 0; 06 August 2008; Santa Ana, CA. 

[6] GE Energy and Environmental Research Corporation; Robinson Sorbent Injection System 

Equipment Performance Guarantee Results Memorandum; 26 September 2008; Santa 

Ana, CA. 

[7] GE Energy and Environmental Research Corporation; Progress Energy Robinson Unit 1 

Technical Specification, Rev E; Santa Ana, CA. 

[8] GE Energy and Environmental Research Corporation; Sorbent Distribution Test Result, 

10 July 2008; Santa Ana, CA. 
Progress Energy Robinson Unit 1 Furnace Sorbent Injection Demonstration Project Final Report, Rev. 02 

Contract No. XM10023-WA169, GE JN 6900 25 February 2009 

GE Proprietary Information Page 1 

GE Energy

Appendices 

A. Ash Mineral Analysis 

B. Test Data Summary 

C. Project Environmental, Health, and Safety Plan