LG&E Services Company LG&E Services Company

Contract No. 501654 Contract No. 501654

Mill Creek FGD Performance Upgrade Study Mill Creek FGD Performance Upgrade Study

February 2011

Assess the feasibility of upgrading the Mill Creek Units 1 & 2 ing the Mill Creek Units 1 & 2 

FGD’s and upgrading the existing Mill Creek 4 FGD and and upgrading the existing Mill Creek 4 FGD and 

utilizing it for Mill Creek Unit 3 utilizing it for Mill Creek Unit 3
 

 

LG&E Services Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

“Assess the feasibility of upgrading the Mill Creek 

Units 1&2 FGD’s and upgrading the existing Mill Creek 

4 FGD and utilizing it for Mill Creek Unit 3” 
LG&E Services Company 

Contract No. 501654 

Mill Creek FGD Performance Upgrade Study 

Table of Contents

February 15, 2011 

1.0 Executive Summary 

2.0 BPEI WFGD Technology Features and Benefits 

2.1 Extensive 3-D Modeling Technology 

2.2 Dual Flow Nozzles 

2.3 Wall Baffles 

2.4 Agitators 

2.5 Mist Eliminators 

2.6 Recycle Pumps 

3.0 Base Case – Existing Absorber Design and Operation 

3.1 Executive Summary – Base Case 

3.2 System Description 

3.3 Current Process Operation 

3.4 Spray Header Arrangement / Spray Nozzle Coverage 

3.5 Recycle Pump Performance 

3.6 Absorber Inlet Design 

3.7 Predicted Absorber Performance 

3.8 Predicted Absorber Performance 

3.9 Construction 

4.0 Case 2 – Required Equipment Modifications to Reliably Achieve 96% SO2 Removal 

4.1 Executive Summary – Case 2, 96% SO2 Removal 

4.2 Case 2 – Work Scope 

4.3 Spray Header Arrangement / Spray Nozzle Coverage 

4.4 Wall Baffles 

4.5 Liquid-to-Gas Ration 

4.6 Absorber Solids / Liquid Residence Time 

4.7 Oxidation Air Blowers and Agitators 

4.8 Construction 

5.0 Case 3 – Maximum Achievable SO2 Removal Efficiency 

5.1 Executive Summary 

5.2 Case 3 – Scope of Work 

5.3 Optimization of Absorber General Arrangement 

5.4 Impact of Reagent Grind Size 

5.5 Impact of Organic Acid 

5.6 Performance Testing and Modeling 

5.7 Construction 
6.0 Construction Plan 

7.0 Budget Price 

8.0 Project Schedule 

Attachments 

– Basis of Design Description 

– Process Flow Diagrams 

– Absorber System General Arrangement Drawings 

– Description of Equipment being Modified 

– Work Breakdown Structure 

– Overall Project Schedule 

– Construction & Outage High Level Schedule 

– Budget Engineering Procurement and Construction Estimate 
1 EXECUTIVE SUMMARY 

Babcock Power Environmental Inc. (BPEI) has conducted an extensive evaluation of the existing 

Wet Flue Gas Desulfurization (WFGD) Systems at Louisville Gas and Electric’s (LG&E’s) Mill 

Creek Generating Station, Units 1, 2 and 4. The purpose of the evaluation was to determine the 

feasibility of modifying the existing WFGD equipment to enhance the overall SO2 emissions 

performance. BPEI was requested to prepare three primary options for LG&E’s consideration, 

as follows: 

o Base Case – Current SO2 Removal Efficiency 

o Case 2 – System Upgrade – Target: 96% SO2 Removal Efficiency 

o Case 3 – System Optimization Upgrade: 98% SO2 Removal Efficiency 

BPEI evaluated multiple alternatives to accomplish LG&E’s objectives, from minimal change to 

extensive retrofit, and presents in this report the most favorable options for LG&E’s 

consideration. BPEI utilized proprietary process software modeling as well as graphical 

depictions of each phase and any required process infrastructure upgrades. Discussions with 

plant engineers and reviews of existing plant equipment provided the necessary information to 

develop a baseline performance model from which to launch the analysis of each option. 

The report also includes the following Project Deliverables: 

 Basis of Design Description 

 Process Flow Diagrams 

 Absorber System General Arrangement Drawings 

 Description of Equipment being Modified 

 Work Breakdown Structure 

 Overall Project Schedule 

 Construction and Outage High Level Schedule 

 Budget Engineering, Procurement and Construction Estimate 

The evaluation was based on the flue gas from Unit 3 being routed to the existing Unit 4 WFGD 

and a new WFGD installed to condition the flue gas from Unit 4. For the purposes of this report 

and in regard to scrubber modifications, “Unit 3” refers the Unit 3 boiler train ducted to the 

current Unit 4 WFGD system. 

Unit Descriptions

Mill Creek Units 1 and 2 are 330 MW each, controlled circulation, pulverized coal fired boilers, 

manufactured by Combustion Engineering. They have been in service since 1972 and 1975, 

respectively. During operation, flue gas exits the air heaters and passes through the ESP, Booster 

Fans and WFGD and then exits through the stack. The original WFGD systems were provided by 

Combustion Engineering and have been modified multiple times throughout their operational 

Page 1 of 59
history. Recently, spray headers were modified and perforated trays added between spray levels 

1 and 2. Today, Units 1 and 2 operate with all spray levels in service. 

Mill Creek Unit 3 is a 425 MW pulverized coal fired boiler, manufactured by Babcock & Wilcox 

Co. It has been in service since 1978. Flue gas exits the air heaters and passes through the ESP, 

ID Fan and WFGD and then exits through the stack. This unit also includes an SCR System that 

was designed and supplied by Riley Power Inc. (RPI), a Babcock Power Inc. Company. 

Today, Units 1 and 2 operate with all spray levels in service. The Units burn bituminous coal 

with an SO2 level of 5.4 lb./MMBtu. The reported SO2 removal is 90-92%, with the reaction 

tank pH normally set to 5.7. 

This evaluation will utilize a design coal that has an SO2 level of 6.3 lb./MMBtu. 

Base Case - Current SO2 Removal Efficiency

Technical Description – The task objective of the Base Case is to determine the maximum 

achievable SO2 efficiency without performing modifications to the existing equipment, based on 

a specified design coal with an SO2 level of 6.3 lb./MMBtu. The work associated with the Base 

Case has been completed by BPEI and is presented in this report. 

Engineering Scope of Work – The mechanisms for achieving the required performance are 

optimization of the spray coverage and droplet distribution, while maintaining droplet size for 

peak liquid-to-gas interaction. This is performed by modifying some of the existing equipment 

and adding new equipment. 

BPEI modeled the existing absorber systems on Mill Creek Units 1, 2, and 3 (Unit 3 flue gas to 

be redirected to existing Unit 4 WFGD system) using proprietary software and data obtained 

from plant personnel to create a realistic baseline performance model. BPEI analyzed 

performance of the model, altering key variables such as flue gas flow, coal sulfur content, 

recycle pump flow and pressure, recycle spray nozzle type, nozzle spray angles, nozzle coverage, 

etc. to determine what modifications to the existing systems would provide the most economical 

reliable performance enhancements for each system. The base model also provides critical 

feedback to the design engineers to confirm that theories and calculations used in the model are 

accurate and appropriate as a starting point for performance enhancement using BPEI’s proven 

techniques. The evaluation was based on the flue gas from Unit 3 being routed to the existing 

Unit 4 WFGD and a new WFGD installed to condition the flue gas from Unit 4. 

Performance – Based on BPEI’s evaluation of the existing equipment and performance 

capabilities, it has been determined that Units 1 and 2 can be expected to achieve a maximum 

88% SO2 removal. Unit 3 can be expected to achieve a maximum 91% SO2 removal. Both of 

these values are based on a design coal that has an SO2 level of 6.3 lb./MMBtu. The results are 

based on the spray nozzles and recycle pumps operating as designed. Also, the results reflect a 

plant modification to route the flue gas from Unit 3 to the Unit 4 WFGD, which has an absorber 

with 25% additional capacity. The higher removal in Unit 3 is attributed to this modification. 

Page 2 of 59
Case 2 – System Upgrade – Target: 96% SO2 Removal Efficiency

Technical Description – The task objective of Case 2 was to provide to LG&E the most 

economical, reliable method to obtain 96% SO2 removal for each of the Mill Creek Units. BPEI 

modeled the existing absorber systems on Mill Creek Units 1, 2, and 3 (Unit 3 flue gas to be 

redirected to existing Unit 4 WFGD system) using proprietary software and data obtained from 

plant personnel to create a realistic baseline performance model. The process parameters were 

then modified using BPEI’s historical experience as follows: 

Units 1 and 2: 

 Change Spray Level 1 nozzles from down-only to dual-flow, double-down nozzles. 

 Change Spray Level 2 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 3 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 4 nozzles from down-only to dual-flow, double-down nozzles. 

 Change spray nozzle angle on Units 1 and 2 from 80o to 120o. 

 Add wall baffles to Spray Levels 2 and 3. 

Unit 3 

 Change Spray Level 1 nozzles from down-only to dual-flow, double-down nozzles. 

 Change Spray Level 2 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 3 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 4 nozzles from down-only to dual-flow, double-down nozzles. 

 Add wall baffles to Spray Levels 2 and 3. 

The model was then used to determine the required recycle pump flow to achieve 96% SO2

removal. 

Units 1 and 2 

 Increase the recycle pump capacity from all at 600 hp to 3 pumps at 500 hp and 5 pumps 

at 700 hp resulting in a change to the Liquid-to-Gas (L/G) ratio, from 112 gal/kacf to 141 

gal/kacf. The recycle pump capacity change in Units 1 and 2 will alter the Liquid-to-Gas 

(L/G) ratio. Generally L/G ratio trends with removal rate, therefore increasing the flow 

through the recycle pumps and nozzles corresponds to greater SO2 removal. 

Unit 3 

 No change to the recycle pump capacity is required. 

BPEI will install agitators on each reaction tank, replacing the existing sparger system, which has 

a tendency to clog and hinder performance. 

Page 3 of 59
Unit 1 

 Install six (6) agitators on each reactor tank. 

Unit 2 

 Install five (5) agitators on each reactor tank. 

 Several chemical and reaction rate modifications were analyzed, namely liquids residence time 

and solids residence time. Optimum values for each of these reaction rate parameters have been 

worked into the existing scrubber operation by revising current ranges for operational level in the 

reaction tanks, absorber slurry solids ranges, and limestone grind fineness. Finally the forced 

oxidation system was evaluated with emphasis on achieving superior mixing of injected 

oxidation air, suspension of slurry in the vessel, and complete oxidation of SO2 removed by the 

absorber. The results of this analysis recommend the following operating changes: 

Units 1 and 2 

 Increase absorber slurry solids from 10-12% to 14-16% RETURN TO ORIGINAL 

DESIGN 

 Increase absorber reaction tank level from 31.5’ to 35.5’ RETURN TO ORIGINAL 

DESIGN 

Unit 3 

 Increase absorber slurry solids from 10-12% to 14-16% 

 Increase absorber reaction tank level from 15’ to 18’ 

Performance – Based on BPEI’s evaluation of the existing equipment and performance 

capabilities and the modeling effort described above, it has been determined that all three units 

can be expected to achieve the 96% SO2 removal target. These values are based on a design coal 

that has an SO2 level of 6.3 lb./MMBtu. Also, the results reflect a plant modification to route the 

flue gas from Unit 3 to the Unit 4 WFGD, which has an absorber with 25% additional capacity. 

Engineering Scope of Work – BPEI will perform engineering activities associated with the 

changes noted above. BPEI will also perform CFD modeling to determine the modifications 

required to the absorber inlet and confirm the spray nozzle layout and coverage area. 

Page 4 of 59
Procurement Scope of Work – The materials required to modify the WFGD and achieve the 

target performance of 96% SO2 removal efficiency are detailed in the table below: 

CASE 2 LIST OF MATERIALS Unit 1 Unit 2 Unit 3 

Description Size Qty Units Qty Units Qty Units 

Slurry Recycle System 

Recycle Pumps 700 HP 3 ea. 3 ea. 

Recycle Pumps 800 HP 5 ea. 5 ea. 

Recycle Discharge Piping 30" 2000 LF 2000 LF 

Recycle Suction Pipe/Flanges 30" 8 ea. 8 ea. 

Recycle System Valves and Inline Equipment 30" TBD TBD 

Spray Nozzles (double down) 120o spray 168 ea. 168 ea. 288 ea. 

Spray Nozzles (bi-directional) 120o spray 168 ea. 168 ea. 288 ea. 

Wall Baffles 

Wall Baffles 4 ea. 4 ea. 8 ea. 

Oxidation Air System 

Oxidation Air Lances 8" x 40" lg. 6 ea. 6 ea. 10 ea. 

Air Lance Supports 6 ea. 6 ea. 10 ea. 

Air Piping External to Sump 20" C.S. 1000 LF 1000 LF TBD LF 

Air Piping Hangers 59 ea. 59 ea. TBD ea. 

Agitators 6 ea. 6 ea. 10 ea. 

Construction Plan – Prior to construction BPEI will integrate engineering and fabrication into a 

detailed fabrication plan. The plan will consider constructability, value engineering, estimating, 

scheduling, safety, quality, project controls and execution. The objective is to assure that 

construction is a seamless part of the project delivery. 

Following mobilization, BPEI will perform pre-construction activities, including receipt of 

materials, erection of scaffolding and installation of the recycle pump foundations. The 

remaining activities will be completed during the outage, which is considered of sufficient 

duration to complete all of the work. The major work activities include the following: 

Units 1 and 2 

 Replace existing recycle pumps and piping with new recycle pumps and associated 

piping 

 Replace existing spray nozzles with new spray nozzles 

 Install new wall baffles at Spray Levels 2 and 3 

 Remove existing spargers 

 Install new agitators and oxidation air lances, and associated piping 

Page 5 of 59
Unit 3 

 Replace existing spray nozzles with new spray nozzles 

 Install new wall baffles at Spray Levels 2 and 3 

 Remove existing spargers 

 Install new agitators and oxidation air lances, and associated piping 

Construction will entail four (4) months of pre-outage activity followed by a 3-week outage. 

 The pre-outage construction utilizes one (1) shift, ten (10) hours per shift, five (5) 

days per week. 

 The outage construction utilizes two (2) shifts, ten (10) hours per shift, six (6) 

days per week. 

Cost – The Rough Order of Magnitude (ROM) estimate for labor, materials and construction for 

each unit is as follows: 

 Unit 1 - $10,541,512 

 Unit 2 - $10,632,006 

 Unit 3 - $14,035,835 

Case 3 – System Optimization Upgrade: 98% SO2 Removal Efficiency 

Technical Description – The task objective of Case 3 was to provide to LG&E the most 

economical, reliable method to obtain 98% SO2 removal for each of the Mill Creek Units, which 

considered the maximum attainable performance. BPEI modeled the existing absorber systems 

on Mill Creek Units 1, 2, and 3 (Unit 3 flue gas to be redirected to existing Unit 4 WFGD 

system) using proprietary software and data obtained from plant personnel to create a realistic 

baseline performance model. The process parameters were then modified using BPEI’s 

historical experience. 

Spray header layout and nozzle selection are optimized based on the overall absorber shell 

dimensions for absolute maximum performance based on the existing reactor tower dimensions. 

For Units 1 & 2, recycle pumps are pushed further and piping is resized for greater flow to 

increase L/G significantly over the original and 96% removal option. 

Unit 3 does not require higher L/G ratio to maximize SO2 removal. Spray header spacing is 

increased and placement is altered to allow for multiple levels of bidirectional nozzles, which 

have proven to be superior in performance compared to down-only nozzles. Spray header layout 

is altered to provide added spray density and prevent any holes in spray coverage by moving the 

position of individual nozzles on the headers.

Page 6 of 59
Units 1 and 2: 

 Move Spray Level 1 from below the tray to 5’ above the tray 

 Space all 4 spray levels 5’ apart 

 Stagger spray header layout 

 Increase spray density by increasing the number of nozzles per spray level from 42 to 54 

 Change Spray Level 1 nozzles from down-only to dual-flow, double-down nozzles. 

 Change Spray Level 2 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 3 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 4 nozzles from down-only to dual-flow, double-down nozzles. 

 Change interior nozzle spray angle from 80o

 to 120o

 Change wall nozzle spray angle from 80o

 to 90o

 Decrease spray pressure from 10 psig to 8 psig 

 Add wall baffles to Spray Levels 2 and 3. 

Unit 3 

 Move Spray Level 1 from below the tray to 5’ above the tray 

 Space all 4 spray levels 5’ apart 

 Stagger spray header layout 

 Increase spray density by increasing the number of nozzles per spray level from 36 to 52 

 Change Spray Level 1 nozzles from down-only to dual-flow, double-down nozzles. 

 Change Spray Level 2 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 3 nozzles from down-only to dual-flow, up-down nozzles. 

 Change Spray Level 4 nozzles from down-only to dual-flow, double-down nozzles. 

 Change wall nozzle spray angle from 120o to 90o

 Decrease spray pressure from 10 psig to 8 psig 

 Add wall baffles to Spray Levels 2 and 3. 

The model was then used to determine the required recycle pump flow to achieve 96% SO2

removal. 

Units 1 and 2 

 Increase the recycle pump capacity from all at 600 hp to 3 pumps at 500 hp and 5 pumps 

at 700 hp resulting in a change to the Liquid-to-Gas (L/G) ratio, from 112 gal/kacf to 144 

gal/kacf. The recycle pump capacity change in Units 1 and 2 will alter the Liquid-to-Gas 

(L/G) ratio. Generally L/G ratio trends with removal rate, therefore increasing the flow 

through the recycle pumps and nozzles corresponds to greater SO2 removal. 

Unit 3 

 Replace the recycle pump gear boxes to increase capacity. 

Page 7 of 59
BPEI will install agitators on each reaction tank, replacing the existing sparger system, which has 

a tendency to clog and hinder performance and add new mist eliminators. 

Unit 1 

 Install six (6) agitators on each reactor tank. 

 Install mist eliminators 

Unit 2 

 Install five (5) agitators on each reactor tank. 

 Install mist eliminators 

Several chemical and reaction rate modifications were analyzed, namely liquids residence time 

and solids residence time. Optimum values for each of these reaction rate parameters have been 

worked into the existing scrubber operation by revising current ranges for operational level in the 

reaction tanks, absorber slurry solids ranges, and limestone grind fineness. Finally the forced 

oxidation system was evaluated with emphasis on achieving superior mixing of injected 

oxidation air, suspension of slurry in the vessel, and complete oxidation of SO2 removed by the 

absorber. The results of this analysis recommend the following operating changes: 

Units 1 and 2 

 Increase absorber slurry solids from 10-12% to 14-16% RETURN TO ORIGINAL 

DESIGN 

 Increase absorber reaction tank level from 31.5’ to 35.5’ RETURN TO ORIGINAL 

DESIGN 

Unit 3 

 Increase absorber slurry solids from 10-12% to 14-16% 

 Increase absorber reaction tank level from 15’ to 18’ 

Performance – Based on BPEI’s evaluation of the existing equipment and performance 

capabilities and the modeling effort described above, it has been determined that all three units 

can be expected to achieve the 98% SO2 removal efficiency These values are based on a design 

coal that has an SO2 level of 6.3 lb./MMBtu. Also, the results reflect a plant modification to 

route the flue gas from Unit 3 to the Unit 4 WFGD, which has an absorber with 25% additional 

capacity. 

Engineering Scope of Work – BPEI will perform engineering activities associated with the 

changes noted above. BPEI will also perform CFD modeling to determine the modifications 

required to the absorber inlet and confirm the spray nozzle layout and coverage area. 

Page 8 of 59
Procurement Scope of Work – The materials required to modify the WFGD and achieve the 

target performance of 98% SO2 removal efficiency are detailed in the table below: 

CASE 3 LIST OF MATERIALS Unit 1 Unit 2 Unit 3 

Description Size Qty Units Qty Units Qty Units 

Slurry Recycle System 

Recycle Pumps 700 HP 3 ea. 3 ea. 

Recycle Pumps 800 HP 5 ea. 5 ea. 

Gear Boxes 8 ea. 

Recycle Discharge Piping 30" TBD LF TBD LF 

Recycle Suction Pipe/Flanges 30" 8 ea. 8 ea. 

Recycle System Valves and Inline Equipment 30" TBD TBD 

Spray Nozzles (double down) 120o spray 324 ea. 324 ea. 624 ea. 

Spray Nozzles (bi-directional) 120o spray 108 ea. 108 ea. 208 ea. 

Spray Headers 8 ea. 8 ea. 16 ea. 

Spray Pipe Hangers TBD TBD TBD 

Wall Baffles 

Wall Baffles 4 ea. 4 ea. 8 ea. 

Oxidation Air System 

Oxidation Air Lances 8" x 40" lg. 6 ea. 6 ea. 10 ea. 

Air Lance Supports 6 ea. 6 ea. 10 ea. 

Air Piping External to Sump 20" C.S. 1000 LF 1000 LF TBD LF 

Air Piping Hangers 59 ea. 59 ea. TBD ea. 

Agitators 6 ea. 6 ea. 10 ea. 

Absorber Shell and Ductwork Modifications 

Outlet Expansion Joint 88 LF 88 LF TBD 

317L Absorber Shell 16,744 sq. ft. 16,744 sq. ft. 

Absorber Reheater Section 1 Lot 1 Lot 1 Lot 

DV210 Mist Eliminator and Spray Wash System TBD TBD TBD 

Construction Plan – Prior to construction BPEI will integrate engineering and fabrication into a 

detailed fabrication plan. The plan will consider constructability, value engineering, estimating, 

scheduling, safety, quality, project controls and execution. The objective is to assure that 

construction is a seamless part of the project delivery. 

Following mobilization, BPEI will perform pre-construction activities, including receipt of 

materials, erection of scaffolding and installation of the recycle pump foundations. The 

remaining activities will be completed during the outage, which is considered of sufficient 

duration to complete all of the work. The major work activities include the following: 

Page 9 of 59
Units 1 and 2 

 Replace existing recycle pumps and piping with new recycle pumps and associated 

piping 

 Replace existing spray nozzles with new spray nozzles 

 Install new wall baffles at Spray Levels 2 and 3 

 Remove existing spargers 

 Install new agitators and oxidation air lances, and associated piping 

 Perform absorber shell and duct modifications 

Unit 3 

 Replace existing spray nozzles with new spray nozzles 

 Install new wall baffles at Spray Levels 2 and 3 

 Remove existing spargers 

 Install new agitators and oxidation air lances, and associated piping 

 Perform absorber shell and duct modifications 

Construction will entail six (6) six months of pre-outage activity followed by a 3-week outage. 

 The pre-outage construction utilizes one (1) shift, ten (10) hours per shift, five (5) 

days per week. 

 The outage construction utilizes two (2) shifts, ten (10) hours per shift, seven (7) 

days per week. 

Cost – The Rough Order of Magnitude (ROM) estimate for labor, materials and construction for 

each unit is as follows: 

 Unit 1 - $20,428,467 

 Unit 2 - $20,567,445 

 Unit 3 - $32,944,117 

Summary

Table 1 summarizes all planned modifications for each option analyzed in the feasibility study. 

Differences between Units 1, 2 and 3 are noted where applicable. 

Page 10 of 59
Base Case 

As Installed 

Case 2 

96% Removal 

Case 3 

Maximum Removal 

Spray Header 

Location 

No Change (1 spray 

header below the tray) No Change 

All 4 headers installed 

above the tray spaced 5’ 

apart 

Spray Header 

Arrangement Stacked (As installed) Stacked (As installed) Staggered Layout 

Spray Nozzle 

Layout As installed No Change Increase Spray Density 

Type of Spray 

Nozzles No Change 

Level 1: Double-Down 

Level 2: Up/Down 

Level 3: Up/Down 

Level 4: Double-Down 

Level 1: Up/Down 

Level 2: Up/Down 

Level 3: Up/Down 

Level 4: Double-Down 

Spray Angle U1&2: All 80o

U3: All 120o

U1&2&3:Interior: 120o

Wall: 120o

U1&2&3:Interior: 120o 

Wall: 90o

Spray Pressure 10 psig 10 psig 8 psig 

Wall Rings None Installed at Spray 

Levels 2 & 3 

Installed at Spray Levels 

2 & 3 

Absorber Tray No Change No Change No Change 

Absorber Solids 10-12% 14-16% 14-16% 

Absorber Level U1&2: 31.5’ 

U3:15’ 

U1&2: 35.5’ 

U3:18’ 

U1&2: 35.5’ 

U3:18’ 

L/G Ratio U1&2: 112 gal/kacf 

U3: 151 gal/kacf 

U1&2: 141 gal/kacf 

U3: 151 gal/kacf 

U1&2: 144 gal/kacf 

U3: 151 gal/kacf 

Recycle Pumps U1&2: No Change 

U3: U4 No Change 

U1&2: New Pumps and 

Piping or Alternative 

U3: No Change 

U1&2: New Pumps and 

Piping 

U3: New Gear Boxes 

Absorber Inlet 

Duct No Change Modify, as required, 

based on modeling 

Modify, as required, 

based on modeling 

ME/Reheater No Change No Change Remove reheat section 

and supply ME section 

Oxidation Air 

Blower/Agitators No Change 

No change to blower. 

Modify piping to match 

air lances w/ agitators 

No change to blower. 

Modify piping to match 

air lances w/ agitators 

Predicted SO2 

Removal 

Performance 

U1&2: 88% 

U3: 91% (in U4 abs) 96% +98% 

Table 1: Mill Creek Upgrades Summary

Page 11 of 59
2 BPEI WFGD Technical Features and Benefits 

All WFGDs utilize the same fundamental technology for SO2 absorption. Where BPEI’s design 

and performance differ from others is in the amount of power and liquid required to achieve the 

maximum SO2 removal efficiency. BPEI maximizes the contact between the gas and the 

absorptive liquid by optimizing the design of the spray zone and using wall rings to eliminate 

“gas sneakage.” This maximizes the utilization of each droplet, while minimizing power 

consumption from the draft and recycle systems. 

BPEI utilizes both co-current and counter-current spray nozzles, in addition to absorber wall 

rings, to continuously achieve high SO2 removals. This performance has been demonstrated at 

multiple installations. While many of these components and features are common to open spray 

tower technologies, the unique design configurations employed by BPEI provide the ability to 

reliably produce high removal efficiencies. To identify how BPEI achieves these results, each of 

the critical design components is described below: 

2.1 Extensive 3-D Modeling Technology 

BPEI uses an absorber flue gas inlet configuration that effectively introduces the flue gas to the 

absorber below the first spray level and distributes it uniformly over the entire cross-sectional 

area of the absorber. This avoids excessive deposits of solids in the ‘wet-dry’ zone where the 

incoming hot gases contact the slurry spray flow. 

Hood Location 

Spray Flowing

Down Absorber 

Wall and Away

from Inlet Duct 

Inlet Gas Flow 

Floor of Inlet

BPEI makes extensive use of 3-D modeling technology. From past experience, BPEI has 

discovered that physical and/or computational models are an important tool in developing the 

design of WFGD systems. Applications of modeling include: 

 The prediction of gas distribution at the absorber inlet and into the first spray level. 

Page 12 of 59
 The prediction of recirculation tank agitator performance as it relates to both suspension of 

solids and distribution of oxidation air for maximum effectiveness. 

 Optimization of gas and spray nozzles droplet distribution and interaction through the 

absorber.

Without Droplets Droplets With Droplets 

The liquid film resistance in the liquid-to-gas (L/G) interface is the limiting factor that regulates 

the rate at which the SO2 absorption occurs. Beyond the (L/G) ratio, the absorption section of the 

WFGD system must also be designed to maximize the contact between the liquid and the 

incoming flue gas. High efficiencies are accomplished by designing the spray zone with dualdirectional, wide-angle, hollow-cone spray nozzles. This arrangement provides: 

 Excellent liquid distribution over the entire spray level cross-sectional area, ensuring that all 

the flue gas is treated. 

 A staggered spray pattern from one level to the next, avoiding flue gas ‘laning’ through paths 

of low liquid flow; i.e., paths of least resistance. 

 A hydrodynamic ‘ring’ along the absorber wall, formed by the use of high liquid flow, 

narrower spray angle nozzles around the full perimeter. This ring counters the ‘wall effect’ 

and ensures that the gas flowing upward along the walls is fully treated. It also reduces the 

amount of water lost’ by being directly sprayed on the absorber wall. 

 A physical wall ring plate, which diverts and mixes the gas flow at the wall around the full 

inside perimeter of the absorber. 

The advantage BPEI has over other suppliers of dual-flow nozzles and wall rings is the ability to 

accurately model the performance and minimize the L/G ratio necessary to achieve high SO2

removal efficiencies. 

2.2 Dual Flow Nozzles 

The features of dual flow nozzles are as follows: 

 Liquid flow is both counter-current and co-current with respect to gas flow, providing good 

gas-spray mixing and gas-liquid contact. 

 The number of nozzle liquid discharge holes doubles over a down-flow only design, yielding 

smaller droplet size at same pump power, thereby improving performance. 

Page 13 of 59
 With the ‘hourglass’ shaped spray pattern, the flue gas must travel through twice the number 

of slurry spray cones as there are levels, insuring better gas-slurry contact. 

 Also, with the hourglass shape the number of spray-to-spray intersections between adjacent 

spray cones is greatly increased. The intersections of adjacent spray cones further enhances 

SO2 removal by: 

o Generating small ‘mist’ droplets as the droplets collide, providing increased liquid 

surface-to-mass ratio. 

o Mixing and reforming droplets, providing ‘fresh’ droplet surface for gaseous 

absorption. 

o Increasing the gas-liquid mass transfer at low liquid flow rates, thereby reducing 

pump power.

Dual-Flow Nozzles 

0

200

400

600

800

1000

1200

1400

1600

1800

0 10 20 30 40 50 60

Pressure, psig

Sauter Mean Diameter, 



m

Droplet size without collision 

Smaller droplets as a result of collision 

70

Page 14 of 59
Double-Down Nozzles 

2.3 Wall Rings 

Features of wall rings are as follows: 

 A physical barrier by which untreated gas along the wall is driven into the spray zone for 

treatment. 

 Full perimeter coverage with no direct spray impact on the ring itself. 

 Excellent gas-liquid mixing and re-distribution. 

 Low gas side pressure drop. 

Absorber Wall Wall Ring Outer Spray Nozzles 

Page 15 of 59
Wall Rings Installed at Ghent 

2.4 Agitators and Oxidation Air System 

Side mounted agitators are designed to provide complete dispersion of air and suspension of 

solids. In order to provide high reliability, these systems are designed such that any one of the 

agitators can be off-line for maintenance while the absorber remains online for operation. The 

agitator seal between the rotating shaft and the absorber wall can be replaced with the tank full of 

slurry, thereby providing additional flexibility and minimal need to drain the tank. 

The oxidation air system piping delivers air to each agitator. The agitator slurry flow is towards 

the center of the tank, slightly off radial and slightly downward. The moving slurry ‘sweeps’ the 

Page 16 of 59
floor and provides ‘off bottom suspension’; i.e., no accumulation of solids on the tank floor. The 

slurry reaches the center of the tank in a slightly off radial direction and turns upward in a helical 

pattern to the slurry surface. It then travels radially outward, turns down at the tank wall and 

returns to the agitators. This is a long and useful travel path, providing good mixing and a long 

time for all the chemical reactions to reach completion. 

Each agitator is equipped with an oxidation air injection lance. The air exits the end of this lance 

in the fast moving slurry at the ‘backwash’ of the agitator. This causes the air to be striped into 

small bubbles, which follow the slurry flow path. This path, as described above, is long and 

allows time for the oxygen to be absorbed into the slurry. 

2.5 Mist Eliminators 

DV210 Mist Eliminators (shown in the photo below) are an alternative to traditional flat mist 

eliminator arrangements. The installation of a single layer benefits installation time and requires 

only one layer of support beams instead of two. The other advantages of DV210 Mist 

Eliminators are: 

 Minimal pressure loss 

 Good elimination performance at medium velocities 

 Suitable for retrofit with existing washers 

 Provides a higher net face area than any other design 

 Mist Eliminator System 

Page 17 of 59
2.6 Recycle Pumps 

BPEI works with all the major recycle pump suppliers to provide the best fit in terms of: 

 Application, 

 Reliability 

 Power requirements 

 Maintenance 

 Noise 

 Cost 

 Delivery 

The predominant difference between the major suppliers is the design of wetted elements. Weir 

pumps have a replaceable natural rubber liner insert with a high chrome iron impeller and throat 

bushing. The liner is a robust fitted insert that is specifically designed and formulated for WFGD 

slurry service. Duchting pumps have an iron shell with a cast-in-place liner and impeller made of 

a composite of silicon carbide grains with an epoxy binder. The GIW pumps are designed with 

high chrome iron for all wetted surfaces. Each project requires are thorough evaluation of the 

recycle pump vendors to determine the best fit in the specific application. 

High-Volume Direct-Drive Recycle Pumps

Page 18 of 59
3 BASE CASE - Current SO2 Removal Efficiency 

3.1 Technical Summary – Base Case 

A thorough understanding of current plant operational characteristics and an accurate baseline 

model are required to complete a performance enhancement study for the Mill Creek WFGD 

systems. BPEI modeled the existing absorber systems on Mill Creek Units 1, 2, and 3 (Unit 3 

flue gas to be redirected to existing Unit 4 WFGD system) using proprietary software and data 

obtained from plant personnel to create a realistic baseline performance model. BPEI analyzed 

performance of the model, altering key variables such as flue gas flow, coal sulfur content, 

recycle pump flow and pressure, recycle spray nozzle type, nozzle spray angles, nozzle coverage, 

etc. to determine what modifications to the existing systems would provide the most economical 

reliable performance enhancements for each system. The base model also provides critical 

feedback to the design engineers to confirm that theories and calculations used in the model are 

accurate and appropriate as a starting point for performance enhancement using BPEI’s proven 

techniques.

Absorber Tower “A” Absorber Tower “B”

Existing WFGD 

Reactor Towers 

and Internals 

(See Fig. 2) 

Inlet 

Ductwork

ID Fan 

Reaction 

Tank

Figure 1: Mill Creek Units 1 & 2, Current 

Page 19 of 59
Mist Eliminator 

Levels 1 & 2 

Abandoned 

Reheater Section 

Perforated plate 

installed between 

spray level 1 and 2

6’ 

As-installed, 4 spray levels, 

down only spray nozzles 

4’ 

5’ 

Flue Gas Inlet

Figure 2: Mill Creek Units 1 & 2, Current Reactor Tower Arrangement 

Page 20 of 59
3.2 System Description 

Flue gas production is directed by means of two ID fans in parallel feeding the unit A and B 

absorbers. 

 

The absorbers share a single reaction tank. Eight recycle pumps four feeding each absorber 

provide the total slurry from the tank to the absorbers. 

Oxidation air is introduced thru a sparger type system. The sparger is arranged as a single header 

located above the floor introducing air evenly throughout the absorber. 

Flue gas vertically moves through each of the four spray headers. Above the first spray header 

LG&E has installed a perforated plate or tray for the purpose of providing even flue gas 

distribution. 

The flue gas exits the absorbers through the mist eliminators to the stack. 

 

 Figure 3: Mill Creek Units 1 & 2 

Page 21 of 59
3.3 Current Process Operation 

Discussions held with onsite engineers and operators as well as reviews of historical data were 

used to better understand current operation of the three absorber units. On average the units burn 

a coal with sulfur content of 5.4 lb SO2/MBtu. Limestone used in the WFGD process to 

neutralize SO2 is finely ground to 95% passing 325 mesh. The absorbers reliably maintain 90-

92% SO2 removal by maintaining an absorber slurry pH in the reaction tank of 5.7-5.8. Absorber 

slurry solids is maintained between 10-12 wt% and controlled with a bleed system. An oxidation 

air sparger ring is designed to oxidize the SO2 removed from the flue gas and maintain agitation 

in the reaction tank. 

The level in the absorber reaction tanks are controlled at lower set points compared to original 

design conditions. The absorber slurry solid concentration is also controlled at a lower density 

than is typical for limestone, forced-oxidation wet FGD systems. Reported unreliability of the 

absorber bleed system to maintain absorber slurry density resulted in the reduced density control 

range. It may also be problematic to maintain absorber slurry solids concentration because of the 

lack of agitation in the absorber reaction tank. Currently the only mixing in the reaction tank is 

an air sparger ring which has been reported to plug up whenever an oxidation air blower trips out 

of service and slowly plug up over time with regular operation. The air sparger ring assembly 

appears to be the highest cause of unreliability in the scrubber process operation. Operating at 

reduced absorber slurry density and absorber levels reduces the liquids and solids retention time 

in the absorber reaction tank, which may have the following consequences: 

 Negative impact on the gypsum quality - smaller crystal size impacting dewatering 

operations 

 Increase the amount of excess limestone required for SO2 removal - higher pHs required 

to maintain SO2 removal efficiency 

 Reduced Hydrocyclone performance – decreased solids in the underflow to the 

dewatering process and increased fraction of gypsum fines removed in the overflow 

purge stream 

 Flue gas off-gassing between the absorber module and the absorber reaction tank causing 

area corrosion issues - no seal is maintained 

3.4 Spray Header Arrangement / Spray Nozzle Coverage 

The high-flow, hollow-cone spray nozzles currently installed in the absorber are designed to 

produce small droplets with a high spray pressure of 20 psig at a spray angle of 80o

 on Units 1 

and 2 and a spray pressure of 10 psig at a spray angle of 120o

 on Unit 3. Figure 5 shows the 

spray coverage with the existing spray header and nozzle configuration. As can be seen there is 

very little spray coverage along the absorber wall and between the absorber nozzles. The four 

spray headers are identical in layout such that some channeling of the flue gas through the 

absorber is likely to occur. 

Page 22 of 59
Reaction tank 

Existing spray header 

coverage, second layer 

Plan view from above 

Mist Eliminators

Figure 4: Mill Creek Units 1 & 2 Plan View, Base Case 

Spray coverage 

gaps in current 

system 

Figure 5: Mill Creek Units 1 & 2 Plan View, Base Case 

Page 23 of 59
BPEI recommends testing the spray nozzle performance of each nozzle type to fully understand 

the current nozzle performance. This is especially critical for Units 1 and 2 because 

understanding the improvement in performance between current operation and Case 2 might 

make the difference between utilizing the existing recycle pumps or replacing the recycle pumps. 

This is covered in more detail in Section 4. 

3.5 Recycle Pump Performance 

A generic pump curve was provided for the recycle pumps installed on Units 1 and 2 absorbers. 

Nozzle data was provided regarding the total number of spray nozzles, nozzle flow rate, spray 

angle, and spray pressure. The recycle pump total dynamic head (TDH) does not correspond to a 

spray pressure of 20 psig when recycle pumps and piping were modeled. Instead the spray 

pressure appears to correspond closer to 10 psig spray nozzles. At the lower supply pressure the 

nozzle performance in terms of spray angle and droplet size and flow rate will not be at design. 

Conservative assumptions will have to be made regarding the current pump performance and 

change in pump performance when changing spray header elevations. 

Pump curves were provided for the recycle pumps installed on the future Unit 3 absorbers 

(currently absorber is treating Unit 4 flue gas) and nozzle data corresponds to the pump 

performance. 

BPEI recommends testing recycle pump performance on all three units to fully understand 

current pump performance. The pump performance testing would be similar to what was 

conducted at Trimble County in terms of measuring motor amperage, pump rpm, pump flow 

rates, and pressure at each pump suction and discharge to locate the actual operating point on the 

pump curve. The data will be used to evaluate the possibility of utilizing the current recycle 

pumps with dual spray nozzles for high SO2 removal and determining if new gear boxes on Unit 

3 recycle pumps will be appropriate for maximum SO2 removal. 

3.6 Absorber Inlet Design 

On all units the absorber flue gas inlet is shorter and has a larger surface area than typical for 

new absorber designs. The length of the absorber inlet is designed to minimize splash back of 

absorber slurry into the carbon steel ductwork. Flue gas velocity in the absorber is controlled 

with the size of the absorber inlet to evenly distribute flue gas prior to the first spray level, to 

eliminate any reverse flow in the duct, and to maintain the wet/dry interface in the absorber area. 

Otherwise, a large, shallow absorber inlet may result in corrosion of the ductwork upstream of 

the absorber. Computational flow modeling will determine if the installed tray offsets the 

negative impact of the current absorber inlet design or if modifications are required to the 

absorber inlet. Physical flow modeling is recommended at a minimum for Unit 3 since ductwork 

would need to be re-routed to Unit 4 absorbers. 

Turning vanes, a perforated plate, and modifications to the inlet duct at Trimble County are an 

example of how to optimize flue gas flow through the absorber and eliminate the potential for 

Page 24 of 59
reverse flow into the ductwork. Figure 6 shows some of the modifications completed to Trimble 

County absorber inlet. These modifications were completed based on CFD modeling. 

Original scrubber inlet duct shown in 

red. Modifications for improved gas 

flow shown in green. 

Elevation view of inlet 

duct modifications Plan view of inlet duct 

modifications 

Figure 6: Inlet Ductwork Modifications at LG&E Trimble County 

3.7 Design Basis 

Table 2 provides a summary of coal analyses for the Mill Creek Station. The first set of data is a

summary of the average fuel burned at Mill Creek in 2009. On average Mill Creek burned a coal 

with an inlet SO2 concentration of 5.4 lb/MBtu based on the average coal sulfur content and high 

heating value. The specified fuel for this study is a design coal similar to what was used for 

Ghent Station Units 1,3 & 4 and Brown Station WFGD Systems with an inlet SO2 concentration 

of 6.3 lb/MBtu and heating value of 12,500 Btu’s/lb used to evaluate current absorber 

performance and absorber performance for Cases 2 and 3. The higher sulfur content is designed 

to represent future operation at Mill Creek Station. 

Page 25 of 59
Fuel Units 2009 Average Design 

Coal Ultimate Analysis 

Carbon (C) wt.% 61.61 60.30 

Hydrogen (H) wt.% 4.22 4.50 

Oxygen (O2) wt.% 7.01 6.80 

Nitrogen (N2) wt.% 1.28 1.17 

Sulfur (S) wt.% 3.02 3.47 

Chlorine (Cl) wt.% 0.06 0.07 

Fluorine (Fl) wt.% 0.01 0.01 

Moisture (Water, H2O) wt.% 11.43 9.56 

Ash wt.% 11.36 14.12 

Total wt.% 100.0 100.0 

Volatile wt.% 35.68 33.00 

Fixed Carbon wt.% 41.54 42.00 

Higher Heating Value Btu/lb 11,115 11,000 

Inlet SO2 lb/MBtu 5.4 6.3 

 

Table 2: Summary of Coal Quality 

3.8 Predicted Absorber Performance 

Absorber performance was predicted using design coal sulfur conditions of 6.3 lb SO2/MBtu, 

assuming no change to Units 1 and 2 absorbers, and directing Unit 3 flue gas to Unit 4 absorbers. 

Approximately 88% removal is predicted with the existing absorber configuration for Units 1 

and 2. Approximately 91% removal is predicted with the existing Unit 4 absorber configuration 

for Unit 3 flue gas. The higher removal is attributed to the larger recycle pumps. 

Figure 7 shows the existing spray level spacing for the three units. The existing spray header 

layout is also used in the Case 2 evaluation. 

3.9 Construction 

3.9.1 Construction – BPEI has no construction for the base case. 

3.9.2 Schedule – No outage scheduled.

3.9.3 Pricing – No price included.

Page 26 of 59
 

4’ 

3’4”

5’ 3’5” 

4’10” 

Tray 

6’ 

Units 1 & 2 Unit 3 

Figure 7: Existing Spray Header Spacing 

Page 27 of 59
4 CASE 2 - 96% SO2 Removal Efficiency 

4.1 Technical Summary – Case 2 

In this section of the report, BPEI’s task objective was to provide to LG&E the most 

economical, reliable method to obtain 96% SO2 removal for Mill Creek Units 1, 2 and 3. The 

process models were taken from the baseline condition and modified using a variety of 

techniques in several stages. Multiple variables were adjusted by application of BPEI’s 

experience in WFGD and experimental results from the process model. Nozzle spray angle, type, 

pressure, flow, and arrangement were fine-tuned to provide optimum spray coverage and droplet 

distribution while maintaining droplet size for peak liquid to gas interaction. Addition of wall 

rings, a BPEI licensed and patented technology, was evaluated to improve flue gas distribution 

and prevent laning of gas along the perimeter of the vessels. Changes to the Liquid-to-Gas (L/G) 

ratio were evaluated via changes in recycle pump flow, pressure, and nozzle flow. Generally L/G 

ratio trends with removal rate, therefore increasing the flow through the recycle pumps and 

nozzles corresponds to greater SO2 removal. Several chemical and reaction rate modifications 

were analyzed, namely liquids residence time and solids residence time. Optimum values for 

each of these reaction rate parameters have been worked into the existing scrubber operation by 

revising current ranges for operational level in the reaction tanks, absorber slurry solids ranges, 

and limestone grind fineness. Finally the forced oxidation system was evaluated with emphasis 

on achieving superior mixing of injected oxidation air, suspension of slurry in the vessel, and 

complete oxidation of SO2 removed by the absorber. A summary of the planned modifications 

respective to each vessel is shown on Table 1. 

Page 28 of 59
120 Degree Spray 

Nozzles Throughout 

Wall Rings 

installed at 

Level 2 & 3 

spray header 

elevation 

Side mount 

Agitators with 

Oxidation Air 

Lances for 

enhanced 

mixing and 

oxidation 

Level 1 & 4 – 

Double-Down 

Spray Nozzles 

Level 2 & 3 – 

Up/Down Spray 

Nozzles 

Figure 9: Mill Creek Units 1&2, Case 2 Upgrades

4.2 Case 2 – Work Scope 

The Case 2 work scope consists of the following: 

 Type of spray nozzles – up/down & double down. 

 Spray angle – changed. 

 Wall Rings – installed at spray levels 2 & 3. 

 Recycle pumps – Unit 1 & 2 new pumps, Unit 3 no change. 

 Side mounted agitators with oxidation air lances. 

 

4.3 Spray Header Arrangement / Spray Nozzle Coverage 

Spray nozzle coverage can be significantly improved utilizing wider spray angle nozzles on the 

existing spray header arrangement. Spray nozzle coverage more than doubles by utilizing wider 

spray angle nozzles on Units 1 and 2. The nozzle coverage doubles by increasing the nozzles 

spray angle to 120 deg. from the existing 80 deg. nozzles. Utilizing dual-flow nozzles on all 

three units produces an even larger surface area. Dual-orifice spray nozzles increase the number 

Page 29 of 59
of droplets and the number of droplet collisions. Increasing the number of droplet collisions 

results in smaller droplets and a significant improvement in SO2 removal efficiency because the 

area available for SO2 absorption has been increased. Spray level 1 will utilize double-downward 

nozzles since this spray header is located just below the tray. Dual direction nozzles proposed for 

spray levels 2 and 3 also have additional benefit of increasing the number of collisions and 

increasing the residence time of droplets in the absorber. Spray level 4 utilizes double-downward 

nozzles to minimize carryover into the mist eliminator section. Figure 10 is example of a bidirectional spray nozzle being tested. 

BPEI proposes increasing the spray angle from 80o to 120o on Units 1 and 2. Figures 11, 12, and 

13 show the additional coverage achieved with the dual flow nozzles. 

Figure 10: Bi-directional spray nozzle testing 

Page 30 of 59
 Figure 11: Mill Creek Units 1 & 2, Case 2 Elevation View 

Dual flow 

nozzles installed 

on levels 2 & 3 

Original header 

and perforated 

tray 

Mist Eliminators 

Wall Rings 

installed at levels 

2 and 3

Double-down spray 

nozzles installed on 

level 1 

Double-down spray 

nozzles installed on 

level 4 

Flue Gas Inlet Duct

Page 31 of 59
Overall view with 120 

degree spray nozzles 

Figure 12: Mill Creek Units 1 & 2 Plan View, Case 2 Upgrades 

Gaps in spray 

coverage eliminated 

by wide-angle 

nozzles. Additional 

droplet collisions 

further enhance SO2

removal 

Wall Ring 

shown in 

Blue

Figure 13: Mill Creek Units 1 & 2 Plan View, Case 2 Upgrades 

Page 32 of 59
120 Degree nozzles, 

double down on 

levels 1 & 4, dual 

flow on levels 2 & 3 

Spray Headers 

Absorber Agitators and 

Oxidation Air Lances

Figure 14: Mill Creek Units 1 & 2 Elevation View, Case 2 Upgrades 

4.4 Wall Rings 

There is a physical limit to the degree of spray coverage along the wall of the absorbers 

especially in the corners of square reactor modules. Increased flue gas flow is expected along the 

wall because of the decreased resistance from this reduced coverage. BPEI will add wall rings to 

deflect flue gas from the absorber wall into the interior of the absorber where there is a greater 

chance of interaction with recycle spray droplets. This also promotes more thorough mixing of 

the flue gas, ensuring no areas of high SO2 concentration along the walls are allowed to bypass 

the effective spray zones. Figure 15 below shows a typical wall ring installation in a circular, 

tile-lined vessel. 

Page 33 of 59
Typical wall ring 

arrangement (circular 

vessel shown) 

Recycle spray nozzle 

Flue gas is forced away from the vessel 

wall, back towards the interior where it 

is more likely to have liquid to gas 

interaction, increasing SO2 removal 

efficiency Recycle Spray Header 

and vessel flange

Figure 15: Typical Wall Ring Arrangement (Ghent Plant) 

Wall rings will be added at spray levels 2 and 3 to maximize the benefit of contacting flue gas 

with the slurry spray while minimizing the impact on pressure drop across the absorber. 

Preliminarily, the pressure drop increase is expected to be minimal. Figure(s) 16 is a graphic 

representation of the wall rings proposed for Mill Creek absorbers. 

Wall Ring: typically 

corrosion resistant 

alloy construction 

Figure 16: Proposed Wall Ring, typical arrangement 

Page 34 of 59
Dual-flow 

nozzles installed 

on levels 2 & 3 

Original header 

and perforated 

tray 

Wall Rings 

installed at levels 

2 and 3

Mist 

Eliminators 

Double-down 

spray nozzles 

installed on levels 

1 & 4 

 

Figure 17: Mill Creek Unit 3 Elevation View, Case 2 Upgrades 

4.5 Liquid-to-Gas Ratio 

The Liquid-to-Gas Ratio (L/G) is a sizing criteria for absorbers that compares the slurry 

recirculation rate to the flue gas flow rate. Presently the L/G ratio for Units 1 and 2 is estimated 

to fall between 112 gal/kacf and 129 gal/kacf based on available recycle pump data. The L/G of 

112 gal/kacf assumes a design flue gas flow rate based on Ghent and Brown flue gas flow rates 

and scaled down for Mill Creek Units 1 and 2. This flue gas flow rate results in a gas velocity 

through the absorber of 15.5 ft/sec which is close to what plant personal reported for these units. 

The higher L/G ratio of 129 gal/kacf is calculated when the original absorber design flue gas 

flow rates are modeled. The reduced flue gas flow rate results in a reduced flue gas velocity of 

13.3 ft/sec through the absorber. For the purpose of this study, the worst-case high flue gas flow 

rates/reduced L/G ratios were used to evaluate improvements to these units. 

Page 35 of 59
The L/G ratio for Unit 3 is 153 gal/kacf. There is more data available for Unit 3 flue gas flow 

rates as a result of baseline testing completed on Unit 3. Unit 4 absorber cross-sectional area is 

approximately 23% greater than the original Unit 3 absorbers and as a result the flue gas velocity 

is reduced compared to Units 1 and 2 at 10.8 ft/sec (versus the original flue gas velocity of 13.4 

ft/sec through the existing Unit 3 absorbers). The higher L/G is also a result of the higher recycle 

pump flow rates for the current Unit 4/future Unit 3 absorber. The design basis for the flue gas is 

summarized in Appendix Basis of Design Description. 

The units were modeled with the dual spray nozzles and wall rings installed. Unit 3 is expected 

to achieve 96% removal provided other process issues are addressed as discussed in the 

following sections. Units 1 and 2 will require a higher L/G ratio of 141 gal/kacf to achieve 96% 

removal. The higher L/G ratio is equivalent to a pump flow rate of 19,000 gpm requiring new 

recycle pumps to be able to achieve 96% removal. The slurry velocity through the recycle piping 

for Units 1 and 2 is already 50% higher than what BPEI would recommend to minimize erosion 

issues. Utilizing higher flow pumps would also require replacing the recycle piping, pump 

isolation valves, and larger spray headers. The higher pump flow rate will also increase the 

pressure drop across the absorber and impact ID fan performance. This is why a thorough 

understanding of the existing recycle pump and spray nozzle performance through physical 

testing is required to determine if this is necessary. 

In addition, more cost effective options are available as an alternative to replacing recycle pumps 

to achieve 96% SO2 removal on Units 1 and 2. Alternative options include utilizing limestone 

slurry with a finer grind and the addition of organic acid to these absorbers. Either of these 

options will increase SO2 removal efficiency without a negative impact on current absorber 

layout and ID fan performance. The absorber design is not very far off from making the 96% 

removal mark based on current absorber performance. While replacing recycle pumps may be 

desirable to achieve maximum removal efficiency with these absorbers. BPEI recommends 

maximizing SO2 removal in Unit 1 and 2 absorbers with modifications of dual-flow nozzles and 

wall rings and then making process changes if necessary to achieve 96% SO2 removal. 

4.6 Absorber Solids/Liquid Residence Time 

As previously mentioned the WFGD systems at Mill Creek are normally operated at reduced 

slurry solids concentration and reduced reaction tank levels compared to original design set 

points. These operating conditions coupled with higher inlet SO2 concentrations and higher SO2

removals to be considered for this retrofit reduces the solids and liquid residence time in the 

absorbers. New limestone, forced-oxidized absorber systems are traditionally designed to 

maintain a solids residence time of 15 hours and a liquid residence time of 5 minutes. Solids 

residence time is necessary to provide adequate time in the reaction tank for gypsum crystal 

growth. The purpose of liquid residence time is to minimize the amount of excess limestone 

required to maintain SO2 removal by allowing adequate time for the limestone to dissolve. This 

is especially important in the production of wallboard grade gypsum. Five minutes is standard 

liquid residence time for the limestone grind fineness and the limestone reactivity typical of 

limestone used at Mill Creek. In retrofit projects BPEI tries to maintain at minimum 12 hours 

solids residence time and 4.5 minutes liquid residence time. The absorber trays are designed to 

Page 36 of 59
add to the liquid residence time because of slurry holdup on the tray itself. However, BPEI does 

not have data available to evaluate the benefit of the tray on liquid residence time. 

Unit 1 and 2 reaction tanks are appropriately sized. At the reduced solids density and reduced 

tank levels the solids residence time is 15.1 hours and the liquid residence time 7.0 minutes. At 

minimum BPEI recommends increasing the reaction tank level set point from 31.5’ to the 

original design level of 35.5’ to maintain a liquid seal between the absorber modules and the 

reaction tanks and eliminate the potential for flue gas corrosion above the reaction tank. There 

are several other areas in inlet and outlet ductwork where flue gas leakage is occurring. The 

corrosion and gas leakage issues are not discussed in this report. 

Unit 3 reaction tanks are very small and were originally designed for a lime-slurry, naturaloxidation process. Lime slurry has a faster dissolution rate compared to limestone slurry so 

reaction tanks are normally designed with reduced liquid residence times. Also, higher solids 

residence times did not improve the dewatering properties of calcium sulfite hemi-hydrate 

crystals. Even though Unit 3 is a larger unit compared to Units 1 or 2 (425 MW vs 330 MW), the 

total reaction tank volume is 25% less than Units 1 and 2 reaction tank volumes. At the reduced 

solids density and reduced tank levels the solids residence time is 8.3 hours and the liquid 

residence time 3.2 minutes. BPEI recommends increasing the reaction tank level set point from 

15’ to original design level of 18’ to increase these residence times and to maintain a liquid seal 

between the absorber modules and the reaction tanks. 

BPEI also recommends improving the reliability of the absorber bleed system so that absorber 

slurry density can be maintained within controlled limits. Improving the reliability of the bleed 

system requires an evaluation of the bleed control valves and bleed logic. Brown has a similar 

bleed system design as Mill Creek with a Hydrocyclone assembly installed at the absorber. This 

system operates with high reliability and BPEI believes the reliability of the bleed system at Mill 

Creek can be improved to maintain a solids concentration approximately 15 wt%, which is 

typical of limestone forced-oxidation systems. Increasing the reaction tank level and absorber 

slurry solids increases the solids residence time to 13.8 hours and the liquid residence time to 3.8 

minutes. 

The liquid residence time is still below minimum recommendations for this process. The 

negative impact is increased excess limestone required (higher absorber slurry pH) to maintain 

SO2 removal. The absorber tray may eliminate this issue however alternatives to increasing 

liquid residence time were evaluated. One way to increase liquid residence time is to increase the 

volume of the reaction tanks. This is a less desirable solution and would require changing the 

geometry of the transition from absorber to the reaction tank and increasing the level of the 

reaction tank. Additionally, liquid residence time can be increased by reducing recycle pump 

flow to 25,000 gpm. As a result SO2 removal will be close but may not necessarily be maintained 

at 96%. Reducing pump flow rates will also require modifications to the recycle pump impellers. 

Alternatively, limestone grind fineness can be increased to offset the decreased liquid residence 

time. This option will be discussed in more detail in Section 5 of this report. 

Page 37 of 59
4.7 Oxidation Air Blowers and Agitators 

Poor mixing of air and absorber slurry can reduce the performance of the absorber. The oxidation 

air sparger ring currently installed requires higher oxygen to SO2 (O:SO2) ratios to provide 

enough excess air to complete the reaction of SO2 removed by the absorber to gypsum. The air 

sparger ring is also a source of high unreliability in the absorber system causing forced unit 

outages whenever the oxidation air system is out of service greater than 30 minutes or the 

sparger ring plugs up over time. BPEI recommends adding agitator and air lance assemblies 

which will reduce the O:SO2 requirements, increase agitation in the absorber allowing the 

absorber to be maintained at design solids concentration, improve reactivity by decreasing excess 

limestone in the absorber, and most importantly improve reliability of the WFGD system. 

Oxidation air lances will be between 8” and 10” in diameter, which will eliminate issues with 

pluggage even if the oxidation air blower is out of service for several hours. Figures 18 and 19 

show graphically agitators and oxidation air lances on one of the reaction tanks. The agitators 

will be appropriately spaced from the recycle pumps to avoid entraining air in the recycle pump 

suction and causing cavitation issues. The number and size of agitators and air lances required is 

a function of the reaction tank diameter, absorber slurry level in the reaction tank, and volume of 

oxidation air required to maintain full oxidation. 

Plan view of Absorber 

Agitators and OA Lances 

showing radial distribution 

on Absorber Tank Wall

Figure 18: Mill Creek Units 1 & 2 Plan View, Case 2 Upgrades 

Absorber Agitators: 

Completely suspend 

slurry solids and 

disperse oxidation 

air for forced 

oxidation of >99% 

Sulfites

Oxidation Air Lance: 

Injects air directly in 

front of agitator impeller 

for maximum dispersion 

Page 38 of 59
Agitator Mechanical 

Seal, Vessel Penetration

Side Mounted 

Absorber Agitator Oxidation Air Injection 

Lances (One paired 

with each agitator) 

Figure 19: Absorber Agitator/Lance 

Oxidation air rates required for the high sulfur, high SO2 removal on Units 1 and 2 is 10,300 

scfm with a supply pressure of 14.6 psig per unit. At present conditions the oxidation air blowers 

run at minimum levels to maintain the airflow necessary for high oxidation. Oxidation air is 

provided to Units 1 and 2 with a common blower. Based on present blower operation and the air 

compressor size (Atlas Copco HA10) it is believed the existing blowers can be used with the new 

agitator/lance design. The oxidation air rate required for Unit 3 is 14,000 scfm with a supply 

pressure of 7.2 psig. Unit 3 oxidation air is provided by a dedicated blower. The existing air 

compressor is capable of maintaining adequate airflow for Unit 3 with the blower operating at 

minimum load. However, with the relatively short reaction tank levels the blower discharge 

pressure is relatively low. The piping system may require an orifice to keep the air compressor 

operating on its curve. 

Page 39 of 59
Figure 20: Oxidation Air Lance and Agitator Impeller 

Additional modeling is recommended to verify mixing and ensure the oxidation air can be 

dispersed in the reaction tanks to complete oxidation. Unit 3 may require a higher O:SO2 ratio 

than is typical for WFGDs but preliminarily the blower appears to have the capacity to 

accommodate higher air flows if necessary. 

4.8 Construction 

The Case 2 construction will consist of replacing the unit 1&2 recycle pumps and piping to the 

spray headers unit 3 will not be changed. BPEI will be adding spray nozzles, wall rings and 

agitators to units 1,2 &3. 

BPEI is planning to work four months at 1-10-5 shifting to install recycle pump foundations on 

units 1&2 and receive materials and set up scaffolding for the outage work. 

During the three week outage BPEI will replace the recycle pumps and pipes on units 1&2 only. 

The unit 3 recycle pumps and pipes will not be changed out. All three units will have wall rings, 

spray nozzles and agitators added. 

The ROM estimate for BPEI to provide engineering, materials and construction is as follows: 

o Case 2: Unit 1 - $10,541,512 

o Case 2: Unit 2 - $10,632,006 

o Case 2: Unit 3 - $14,035,835 

Page 40 of 59
4.9 Schedule 

Our preliminary schedule included in the attachments section is based on the following: 

 

 Case 2: Units 1, 2, & 3:4 

- (4) Month construction schedule working (1-10-5) 

One shift, ten hours per day for five days 

- (3) week outage schedule working (2-10-6) 

Two shifts, ten hours per shift, six days per week 

Page 41 of 59
5 CASE 3 +98% SO2 Removal Efficiency 

5.1 Technical Summary – Case 3 

In the final stage of analysis all available methods for performance enhancement are brought into 

play. Spray header layout and nozzle selection are optimized based on the overall absorber shell 

dimensions for absolute maximum performance based on the existing reactor tower dimensions. 

For Units 1 & 2, recycle pumps are pushed further and piping is resized for greater flow to 

increase L/G significantly over the original and 96% removal option. Unit 3 does not require 

higher L/G ratio to maximize SO2 removal. Spray header spacing is increased and placement is 

altered to allow for multiple levels of bidirectional nozzles, which have proven to be superior in 

performance compared to down-only nozzles. Spray header layout is altered to provide added 

spray density and prevent any holes in spray coverage by moving the position of individual 

nozzles on the headers.

5’ 

5’

5’ Perforated 

Tray

Figure 21: Mill Creek Units 1 and 2, Case 3 Upgrades

Page 42 of 59
Wall Rings 

installed at 

levels 2 and 3 

Absorber 

Inlet 

Duct

Figure 22: Mill Creek Unit 3, Case 3 Upgrades 

Chemical changes including addition of an organic acid and increasing limestone grind fineness 

are considered as additional methods to improve the removal reaction rate. Finalizing the 

maximum removal upgrade options is a series of recommendations for process optimization 

involving control hardware and logic modifications. Over many iterations of design and control 

philosophy BPEI has refined WFGD control logic to provide to our clients a simple and efficient 

means of reliably removing SO2 from flue gas. Modifications to the existing control scheme and 

potential hardware changes are addressed in this final section. 

5.2 Case 3 – Scope of work 

The Case 3 work scope consists of the following: 

 Spray header location – All four headers above the tray spaced 5’ apart. 

 Spray header arrangement – Staggered layout. 

 Spray nozzle layout – Increase spray density. 

 Type of spray nozzles – up/down & double down. 

Page 43 of 59
 Spray angle – changed. 

 Wall Rings – installed at spray levels 2 & 3. 

 Side mounted agitators with oxidation air lances 

 Recycle pumps – U1&2: new pumps, U3: new gearboxes. 

 Mist eliminator – Install new DV210. 

5.3 Optimization of Absorber General Arrangement 

The current arrangement of the tray and spray headers is less than optimal for maximum SO2

removal. The spray headers are spaced closely together and the tray is currently installed 

between spray levels 1 and 2 eliminating the use of dual-flow bi-directional spray nozzles on the 

first spray level. Additionally, the nozzle arrangement is identical between spray levels which 

can result in flue gas channeling (“laning”) through the absorber, reducing SO2 removal 

potential. BPEI proposes the following to maximize SO2 removal efficiency across the absorber: 

 Relocate bottom spray header above the perforated tray 

 Space the spray levels 5 ft apart 

 Stagger nozzle layout between spray levels 

 Increase spray density 

Originally trays were installed in open spray towers with a spray header installed below the tray 

to quench the flue gas and minimize scaling on the tray. This was especially an issue on natural 

oxidation systems. Research has since been completed to demonstrate a quench spray header is 

not necessary for limestone, forced-oxidation systems. BPEI proposes leaving the installed tray 

in its existing location and rearranging the spray headers so that they are all located above the 

tray. Relocating the first spray header will also allow the use of dual-flow, bi-directional spray 

nozzles on an additional spray header. 

Spray Header Spacing 

 The spray headers will be relocated 5 ft apart to match current design practices for 

high efficiency absorbers. 

 To create the extra space required in the spray zone section, BPEI proposes 

removing the abandoned re-heater section and relocating the mist eliminator section 

in this unused section. 

 Moving the spray headers in this manner allows the use of bi-directional nozzles on 

all but the top level spray header. Further, this spray header spacing provides for a 

providing more uniform distribution of slurry to the entire spray zone with enhanced 

droplet formation for more intimate contact between SO2 molecules and slurry 

droplets. 

Figures 22 through 26 show the original and proposed spray header spacing for Units 1 and 2 

and Unit 3. 

Page 44 of 59
Existing spray header 

spacing. 

Modified spray header 

spacing. 

ME System moved 

up into abandoned 

reheater section

Tray remains at 

present elevation 

Figure 23: Units 1 and 2 Modified Elevation View

Figure 24: Units 1 and 2 Spray Header Spacing simplified sketch 

Page 45 of 59
ME System moved 

up into abandoned 

reheater section

Modified spray header 

spacing. 

Existing spray header 

spacing. 

Figure 25: Unit 3 Modified Elevation View

Figure 26: Unit 3 Spray Header Spacing simplified sketch 

Page 46 of 59
Staggered Nozzle Layout & Increased Spray Density 

 Staggering the nozzle layout between spray headers minimizes the potential of gas 

channeling or ‘laning’ through paths of low liquid flow, i.e. paths of least resistance. 

 Wall Rings along the full inner perimeter of the vessel counteract the ‘wall effect’ 

ensuring that the gas flowing upward along the walls is fully treated and reduces the 

amount of ‘lost’ slurry that is sprayed onto the wall by redirecting that slurry out into 

the spray zone. 

 Good liquid distribution over the entire spray level cross-section ensures all flue gas 

that passes through the absorber is treated. 

 On smaller absorbers with a standard nozzle layout as Mill Creek the flow rate per 

nozzle is higher than typical for high efficiency scrubber designs therefore to 

maintain a small droplet profile with high flow nozzles requires increasing the spray 

pressure, resulting in a higher TDH for the recycle pumps. 

 Alternately, increasing the number of spray nozzles per spray header, thus increasing 

spray density, is the most effective use of the low spray pressure nozzles proposed 

for the Mill Creek upgrade. 

 Increasing the spray density has the potential additional benefits of increasing the 

removal of particulate and acid gas (SO3) in the absorber. 

Nozzle placement is 

now staggered to 

provide full coverage 

of flue gas and 

preventing laning. 

Wall rings 

Figure 27: Unit 3 Modified Spray Header Layout 

Page 47 of 59
Plan View 

Wall Ring 

Nozzle density 

is increased 

from 42 per 

level to 54 per 

Elevation View level 

Nozzle coverage has been 

modified to provide 

maximum overlap in the 

spray zone. 

Down only, dual-flow 

nozzles on level 4

Wall Rings

Bi-directional nozzles 

on level 1, 2 and 3

Figure 28: Mill Creek Units 1 & 2 Modified Nozzle Arrangement 

Page 48 of 59
Spray headers 

are now 

staggered to 

provide better 

spray coverage 

Spray Header 

Level 1 

Spray Header 

Level 2 

Spray Header 

Level 3 

Spray Header 

Level 4 

Perforated Tray 

 

Figure 29: Mill Creek Unit 3 Modified Nozzle Arrangement 

Page 49 of 59
Figures 30 and 31 are Process Flow Diagrams with the new spray header layout for Units 1 

and 2 and Unit 3. 

 

Figure 30: Unit 1 Process Flow Diagram 

Page 50 of 59
Figure 31: Unit 3 Process Flow Diagram 

Optimization of Absorber Process Conditions 

The units were modeled with the above referenced spray header arrangement modifications. 

The recycle pump curves were used to estimate pump performance with the increased TDH 

(from the higher spray level elevation). Utilizing the existing recycle pumps for Units 1 and 

2, the decreased pump flow rate with the new TDH is approximately 12,000 gpm, decreasing 

the L/G ratio to 89 gal/kacf. SO2 removal efficiency is predicted to drop below 95% with the 

high sulfur coal. To achieve +98% SO2 removal the existing recycle pumps will have to be 

replaced with pumps that can achieve 19,400 gpm flow which results in a L/G ratio of 144 

gal/kacf. An additional case was considered leaving recycle spray levels 2 through 4 in the 

present location and only relocating spray header 1 to the top of the absorber area. To 

achieve 98+% SO2 removal with the overall spray height reduced 2 ft requires increasing the 

L/G ratio from 144 to 151 gal/kacf. 

Page 51 of 59
Utilizing Unit 4 recycle pumps for Unit 3, the decreased pump flow rate with the new TDH 

is approximately 24,000 gpm (12,000 gpm/header), decreasing the L/G ratio to 134 gal/kacf. 

High SO2 removal efficiency (>97%) is still predicted for this operating case. However, to 

maximize SO2 removal potential, BPEI recommends increasing the recycle pump flow to the 

current rate of 27,500 gpm, returning the L/G ratio to 151 gal/kacf. Preliminary review of the 

Unit 3 recycle pumps indicates it may be possible to maintain the pump capacity to operate 

at the higher TDH by utilizing new gear boxes. A liquid residence time of 4.2 minutes is 

calculated for Unit 3 at this L/G ratio. Options available to address issues with the decreased 

residence time include using limestone slurry with a finer grind or adding organic acid to the 

process. These options are discussed in more detail below. The additional liquid residence 

typically achieved with the use of a tray should be enough to offset the physical limits of the 

reaction tanks. 

An additional case was considered leaving recycle spray levels 2 through 4 in the present 

location and only relocating spray header 1 to the top of the absorber area. The distance 

between spray headers on Unit 3 absorbers are much shorter (~3.5 ft apart) compared to 

Units 1 and 2. To achieve 98+% SO2 removal with the overall spray height reduced 6 ft 

requires increasing the L/G ratio from 151 to 174 gal/kacf. It may be possible to still utilize 

the recycle pumps utilizing new gear boxes and possibly impellers, however the higher L/G 

has a negative impact on liquid residence time. The residence time is reduced to 3.6 minutes 

which may or may not be offset with the absorber tray and chemical adjustments such as 

finer ground limestone slurry or the addition of organic acid. The reduced spray height also 

impacts the benefits of the dual-dual flow nozzles. 

 The overall recycle pump flow rate does not change on Unit 3. The recycle piping is 36” in 

diameter. The slurry velocity of 8.7 ft/sec is within the limits of 5 to 10 ft/sec recommended 

by BPEI. When the recycle piping splits between the two absorbers the slurry velocity 

increases to 9.8 ft/sec. No modifications to the recycle piping is anticipated. 

The required recycle pump flow rate increases 30% for Units 1 and 2. The recycle piping 

diameter is 20”. The line velocity with the current recycle pump flow is already high at 15 

ft/sec . High slurry velocities will result in increased erosion of the recycle piping especially 

in piping bends. It is recommended to increase the recycle piping diameter to 30” to bring the 

slurry velocity down to 9 ft/sec with the higher pump flows. The three branches at each spray 

level will increase from 14” to 18” to maintain slurry velocity. These modifications also 

require replacing the recycle pump suction valves and installing new nozzles on the absorber 

recycle tank for the larger pump suctions. Since recycle piping and headers require 

modification there is no benefit leaving spray levels 2 through 4 in their present location but 

proceeding with maintaining the optimal spray header distance of 5 ft between spray headers 

to maximize SO2 removal. 

The new pump flow rates will also increase the pressure drop across the absorbers impacting 

ID fan performance. Based on conversations with plant personal, it is understood that the ID 

fans are already operating at their maximum capacity and that either new ID fans or booster 

Page 52 of 59
fans are planned to accommodate a future SCR and fabric filter for Units 1 and 2. Increase 

pressure drop across the absorbers to accommodate higher L/G ratios for maximum SO2

removal should be considered in the new fan design. If the planned absorber modifications 

are to be completed prior to any modifications/additions to the upstream fans there is an 

alternative option to increase SO2 removal while minimizing the impact of absorber pressure 

drop. This option requires removal of the absorber tray and increasing the L/G ratio from 144 

gal/acf to 172 gal/acf. Further review to understand the pressure drop across the absorber tray 

versus maintaining a higher L/G ratio would have to be completed prior to following this 

recommendation. If the tray is removed from the absorber, the first absorber spray level 

would be located at the elevation of the tray and the subsequent spray levels spaced 5 ft apart 

from each other. 

BPEI recommends adding pressure instrumentation on the pump suctions and discharges to 

monitor pump performance and adding logic to protect the recycle pumps from cavitation if 

there is a sudden loss of suction pressure. It is also recommended to add control valves to the 

pump flush water connections and pumps drain to incorporate an automatic flush and drain 

sequence. 

The absorber control logic at Mill Creek controls limestone slurry feed by maintaining an 

absorber reaction tank pH set point. To maintain high SO2 removal efficiency and optimize 

limestone consumption BPEI recommends going to a feed-forward logic loop with feedback 

trims to control limestone slurry feed to the reaction tanks. Feed-forward logic, calculates 

limestone slurry rate based on inlet SO2, an SO2 removal or emissions set point, limestone 

slurry concentration, and unit load or flue gas flow rate. There are two feedback trims to the 

calculated limestone slurry feed rate. The first feedback trim looks at the actual SO2 removal 

or emissions rate and adds more limestone slurry if the unit is under-scrubbing or decreases 

limestone slurry feed rate if unit is over-scrubbing. The second feedback trim looks at 

reaction tank pH and will override SO2 trim, if necessary, to maintain the reaction tank pH 

between 5 and 6. This type of feed-forward logic allows for tighter control because the 

limestone slurry feed rate is adjusted as inlet conditions (such as unit load) change instead of 

a system that is reactive and swinging up and down around the set point. BPEI recommends 

a review of the absorber control logic and to consider using CEMs instrumentation, if 

abandoned on the old Unit 3 system, to measure inlet SO2 on Units 1 and 2. 

5.4 Impact of Reagent Grind Size 

The limestone grind maintained at Mill Creek is consistently finer than 95% passing 325 mesh 

which is the minimum grind BPEI recommends for high SO2 removal efficiency absorbers. 

Increasing the limestone grind to greater than 99% passing 325 mesh increases the rate the 

limestone dissolves in the reaction tank. Increasing the rate of limestone dissolution will offset 

the short liquid residence time in Unit 3 reaction tanks. This would only be necessary if the 

excess limestone required for high SO2 removal has a negative impact on gypsum quality. In 

reality if Unit 3 hydrocyclone underflow is being mixed with the underflow slurries from the 

other three operating units, it is unlikely there will be an overall negative impact gypsum quality. 

Page 53 of 59
Finer grind can also be utilized to improve SO2 removal performance on Units 1 and 2 to achieve 

96% removal reliably in place of replacing recycle pumps for this phase. 

Mill Creek is currently looking to increase the capacity of their reagent preparation system. 

Producing ultra fine grind limestone slurry results in diminished capacity of the reagent 

preparation system thus increasing the power required per ton of limestone processed through the 

reagent preparation system. This cost can be weighed against the benefit of maintaining SO2

removal and/or avoiding a unit de-rate if recycle pumps have to be taken out of service for 

maintenance. 

5.5 Impact of Organic Acid 

An organic acid, sodium formate, is currently added to the existing Unit 3 absorber system. Unit 

3 reaction tanks are odd shaped with very poor mixing. Because of the poor mixing excess 

limestone is required to maintain SO2 removal. The organic acid buffers the pH in the reaction 

tank reducing the amount of excess limestone required to maintain SO2 removal and gypsum 

quality. Organic acid is already piped the new reaction tanks to be used when treating Unit 3 gas. 

Similar to the benefit of finer ground limestone, the organic acid can be used to offset any 

negative impact the small reaction tanks may have on liquid residence time or to improve Units 1 

and 2 absorber performance in Case 2. Additional piping and logic is required to implement 

organic acid addition to Units 1 and 2. 

At other WFGD system organic acid is utilized as a “spare” recycle pump to maintain high SO2

removal efficiencies if a recycle pump has to be taken out of service. The benefit of organic acid 

over ultra fine grind limestone is that the effect is immediate. There is no turnover of a slurry 

tank prior to the organic acid impacting absorber performance. 

If there are no permit restrictions on the organic acid in the water purge from the WFGD system, 

BPEI recommends completing a cost/benefit analysis of operating with 4 recycle pumps versus 

adding organic acid and operating with 3 recycle pumps in the three absorber units. 

5.6 Performance Testing and Modeling 

BPEI recommends a standard baseline performance test as well as advanced Computational 

Fluid Dynamics (CFD) and physical modeling of planned modifications. Changes to ductwork 

(Unit 3 into Unit 4 Scrubber) can result in unforeseen gas dynamics that could be detrimental to 

the process if the appropriate internal flow control devices are not installed. BPEI makes 

extensive use of modeling technology retrofit modifications such as those proposed for Mill 

Creek Generating Station. Some of the applications of this modeling are as follows: 

 Prediction of gas distribution at the absorber inlet and into the first spray level 

 Prediction of gas distribution and slurry spray distribution within the absorber spray zone, 

including advanced CFD droplet analysis for enhanced accuracy at predictions of liquidto-gas interaction 

Page 54 of 59
 Prediction of absorber sump recirculation for agitator performance as it relates to both 

suspension of solids and distribution of oxidation air for maximum effectiveness 

Typical physical models are scaled for geometry and operate at full gas velocity, with the mist 

eliminators modeled in full scale. For this type of model, BPEI is able to analyze gas flow 

behavior at the gas inlet, entering, within the absorber, leaving the spray zone, and entering and 

leaving the mist eliminators. The results of these model tests are incorporated into the actual 

absorber design (ductwork layout, spray header layout, nozzle spacing, etc.) to ensure controlled 

gas behavior, uniform gas flow, high liquid-gas contact for maximum efficiency with installed 

components, and uniform gas flow to the mist eliminators for consistent mist elimination from 

the flue gas. 

Computational Fluid Dynamics (CFD) is also relied upon for design input. The below model was 

created to study the effects of retrofitting an additional spray level to an absorber to 

accommodate the use of higher sulfur coal at higher unit load, while maintaining the same outlet 

emission. Once again, uniformity of flow for high performance with a low gas side pressure drop 

was achieved in the model and then replicated in the actual unit. The plant is E.ON’s Schkopau, 

and the change was executed on four absorbers at 240MW each. 

Figure 32: Sample of CFD Model Output 

Gas distribution, as predicted at the absorber inlet, in the spray zone, and through the mist 

eliminators is shown modeled with four spray levels in service. The geometry of the added fifth 

spray level, shown on the right, was tested and confirmed to improve SO2 efficiency, with no 

adverse effect on the existing absorber or mist eliminator configuration. 

Page 55 of 59
A similar approach could be taken to Mill Creek Units 1, 2, and 3 for predictions of gas 

distribution with modifications to inlet ductwork, spray header spacing, spray header layout, 

number and type of nozzles. CFD modeling would be especially advantageous on Unit 3 because 

of the shift to a different absorber unit and all the ductwork modifications associated with that 

change. 

5.7 Construction 

The Case 3 construction will consist of replacing the unit 1&2 recycle pumps, piping and spray 

headers, unit 3 spray pipes, spray headers and recycle gearboxes will be replaced. BPEI will be 

adding spray nozzles, wall rings and DV210 mist eliminators on units 1,2 &3. 

BPEI is planning to work six months at 1-10-5 shifting to install recycle pump foundations on 

units 1&2 and receive materials and set up scaffolding for the outage work. The Case 3 outage is 

based on installing mist eliminator, spray headers, spray nozzles and wall rings into a new 

absorber module. This will allow the ground fabrication of the absorber and internals to take 

place before the outage. 

During a six week outage working 2-10-7 BPEI will replace the recycle pumps on units 1&2 

only. On unit 3 BPEI will replace the recycle gearboxes. All three units will have the absorbers 

and new internals changed out as modules to reduce the outage schedule. 

The ROM estimate for BPEI to provide engineering, materials and construction is as follows: 

o Case 3: Unit 1 - $20,428,467 

o Case 3: Unit 2 - $20,567,445 

o Case 3: Unit 3 - $32,944,117 

5.8 Schedule 

Our preliminary schedule included in the attachments section is based on the following: 

 

Case 3: Units 1, 2, & 3:4 

- (6) month construction schedule working (1-10-5) 

One shift, ten hours per day, five days per week 

- (6) week outage schedule working (2-10-7) 

Two shifts, ten hours per shift, seven days per week 

 

Page 56 of 59
6. Construction Plan 

6.1 Organization Overview 

Babcock Power Environmental, Inc. has developed a preliminary Construction Plan that 

capitalizes on its engineering, product fabrication, installation, and startup expertise to provide 

LG&E services with an efficient retrofit design to provide low project price and short outage 

schedule. 

6.2 Execution 

Pre-Construction 

Upon Notice to proceed BPEI will develop a pre-construction team that will integrate BPEI 

engineering and fabrication with construction and develop a detailed design, project plan, and 

schedule. We will develop the details for constructability, value engineering, estimating, and 

scheduling. During this period we will refine our budgets, safety, quality, project controls, 

and execution plans to reflect more detailed design information. Our objective will be to 

assure the construction phase in a seamless part of the project delivery method. The 

integration of our proposal, pre-construction and construction teams will facilitate the most 

effective transfer of ownership and job knowledge, ensuring project safety and timely 

completion of construction and startup. 

Construction 

Following the integrated project schedule, BPEI will mobilize on the Mill Creek site and 

prepare for the receipt of WFGD components. We will construct the Recycle Pump 

foundations before the outages begin in order to reduce the outage lengths. 

Outage 

The duration of the outage on Case 2 or Case 3 is based on work being completed during the 

construction phase. It is BPEI’s intention to minimize the outage duration to assist LG&E 

services in keeping the Mill Creek boilers operating. 

Page 57 of 59
7. Budget Price 

LG&E Services Company 

Contract No. 501654 

Mill Creek FGD Performance Upgrade Study 

Budget Engineering, Procurement and Construction Estimate

February 15, 2011 

Description Engineering Equipment Construction Total

Case 2: Unit 1 $1,922,629 $5,365,667 $3,253,216 $10,541,512

Case 2: Unit 2 $1,922,629 $5,365,667 $3,343,710 $10,632,006

Case 2: Unit 3 $1,922,629 $6,735,206 $5,378,000 $14,035,835

Case 3: Unit 1 $2,949,580 $10,573,006 $6,905,881 $20,428,467

Case 3: Unit 2 $2,949,580 $10,573,006 $7,044,859 $20,567,445

Case 3: Unit 3 $2,949,580 $17,504,859 $12,489,678 $32,944,117

Note: The estimate for the Mill Creek WFGD Study is a ROM (rough order of magnitude) 

estimate. The accuracy is based on +25% to – 10%. The pricing is based on current 2011 dollars 

with no escalation. 

 The scope of the pricing for the Mill Creek Study is limited to WFGD Performance retrofit 

improvements. There are no other maintenance upgrades to the absorber structure or reaction 

tank included. 

Page 58 of 59
Page 59 of 59

8. Project Schedule 

Our preliminary schedule included in the attachments section is based on the following: 

 

 Case 2: Units 1, 2, & 3:4 

- (4) Month construction schedule working (1-10-5) 

One shift, ten hours per day for five days 

- (3) week outage schedule working (2-10-6) 

Two shifts, ten hours per shift, six days per week 

Case 3: Units 1, 2, & 3:4 

- (6) month construction schedule working (1-10-5) 

One shift, ten hours per day, five days per week 

- (6) week outage schedule working (2-10-7) 

Two shifts, ten hours per shift, seven days per week 

 
Flue Gas Desulfurization 

Design Basis Spreadsheet

100524

Rev. 0

LG&E Energy

Mill Creek Units 1, 2, and 3

Kosmodale, KY

WFGD Upgrade

Prepared Name Suzette Puski

Prepared Date 1/25/11

Checked Name Matt Quitadamo

Checked Date 1/25/2011

Customer Signed Name

Customer Signed Date

Remarks:

This technical data is proprietary technology of BPEI, Inc. P.O. Box 15040,

Worcester, MA 01615-0040, and is submitted, lent and furnished to recipient

in strict confidence with the express understanding that the recipient shall not 

reproduce, copy, loan, dispose of or disclose to anyone outside recipient's 

organization, directly or indirectly, or use said proprietary material for any purpose

other than that for which it is furnished and submitted. Recipient by receiving 

said proprietary material agrees not to use the same in any way injurious to the

interest of BPEI, Inc., and agrees to return same upon request. 

Copyright BPEI, Inc. 2011.

Project Number:

Revision Number:

Customer Name:

Project Name:

Report Title (shown on printed sheets)

 Email changes to

Location, City, State

Description

1 of 8 Date: 2/15/2011
FGD Design Basis Spreadsheet

Scope of Supply

Plant Name:

Plant Location

U1&U2 Case 2 U3 Case 2 U1&U2 Case 3 U3 3 Case 3

Flue Gas Path

Equipment for Partical Removal

Equipment for Draft System

Inlet Duct Modifications xxxx

Equipment for SO2 Removal

Install Wall Rings on Spray Levels 2 and 3 8 Wall Rings 8 Wall Rings 8 Wall Rings 8 Wall Rings

Install Up/Down Interior Spray Nozzles 160 128 336 336

Install Up/Down Interior Wall Ring Nozzles 176 160 312 288

Install Double-Down Interior Spray Nozzles 160 128 112 112

Install Double-Down Wall Ring Spray Nozzles 176 160 104 96

Replace Recycle Pumps 8 Pumps 8 Pumps

Replace Recycle Pump Piping x x

Replace Recycle Pump Gear Boxes 8 Pumps

Add Agitators and Air Lances 12 10 12 10

Equipment for SO3 Removal

Equipment for Hg Removal

Equipment for NOx Removal

Equipment for Mist Removal

Replace ME Section w/ DV210 x x

other

Waste Water Treatment

Utilities

Reagent

Equipment for Reagant Unloading

Equipment for Reagent Storage

Equipment for Reagent Day Storage

Equipment for Reagent Slurry Preparation

Increase Limestone Grind Possible Alternative May be Required

Organic Acid

Equipment for Organic Acid System

Add organic feed system to Units 1 and 2 Possible Alternative

Byproduct

Equipment for Byproduct Treatment

Equipment for Byproduct Storage

Equipment for Byproduct Loading

Fly Ash

Equipment for Flyash Treatment

Equipment for Flyash Storage

Equipment for Flyash Loading

Balance of Plant

Water Supply

Service Air Supply

Instrument Air Supply

Cooling Water Supply

Process Control

Evaluate revising control logic for SO2 removal xxxx

Electrical Equipment

Structural Steel

Civil

Construction

Process Equipment

Balance of Plant Equipment

Process Control incl. Wiring

Electrical Equipment incl. Wiring

Structural Steel

Civil

Commissioning Yes

Performance Test No

Mill Creek Units 1, 2, and 3

Rev. 0

2 of 8 Date: 2/15/2011
Mill Creek Units 1, 2, and 3

Rev. 0

Plant Data Sheet Units DESIGN

Plant Name: Mill Creek Units 1, 2, and 3

Plant Location Kosmodale, KY

Site Conditions

Seismic Zone (Av/Aa) 0.09/0.07

Design Ambient Temp o

F 68

Maximum Summer Ambient Temp o

F 105 (per Trimble County Design)

Minimum Winter Ambient Temp oF -10 (per Trimble County Design)

Indoor Temperature Design / Range oF

Plant Elevation @ Grade ft 460

Elevation @ Absorber Inlet ft above TOC Units 1 & 2: 39.5, Unit 3: 28.2

Atmospheric Pr. @ Absorber Inlet Elevation psia Units 1 & 2: 14.43, Unit 3: 14.44

Absolute Humidity Average % max 100%

Average Rainfall inches/year 50 (per Trimble County Design)

Wind Speed CRM 780 section 1611.0 MPH 70 (per Trimble County Design)

Snow Load CMR 780 Section 1610.0 lb/sf 15 (per Trimble County Design)

Earthquake Loads CMR 780 Section 1612.0

FGD Operation

Mode Part/Continuous Continuous

Months of FGD operation/yr - Design Mon/yr 12

Months of FGD operation/yr - Future Mon/yr 12

Number of Boilers served by one Scrubber # Each Unit has a dedicated mult-module absorber system

Bypass Operation required Yes / No No Bypass Allowed

Equipment Installation Indoor/Outdoor

FGD Design Basis 

Spreadsheet

3 of 8 Date: 2/15/2011
Mill Creek Units 1, 2, and 3

Rev. 0

Boiler Data Sheet Units DESIGN

Units 1 & 2 Unit 3

LOAD % MCR 100 100

Nominal Rating MW, Gross 350 410

MW, Net 386

Boiler Manufacturer - Combustion Engineering Babcock & Wilcox

Fuel Fired Coal/Gas/Oil Coal Coal

Firing Method Dry Bot/Wet Bot/Cyclone Opposed Wall Fired Boiler (5x4 high) w/ LNB

MCR Steam Flow (Design) pph 2,326,000 3,144,000

Boiler Type Balanced Draft/Pressurized Balanced Draft Balanced Draft

Plant Capacity Factor Percent of Year 74.9 Gross/ 73.6 Net

Hours of operation per year Hours in 2000 7447 hrs

Number of Cold Starts per year Target/Actual 2 actual

Number of Hot Restarts per year Target / Actual 22 actual

Ignition Fuel Fired Oil/Gas Oil Oil

Ignition Fuel Fired Hours/Year 800,000 gal

Minimum Load for FGD Operation MWnet 193 MW net

Flue Gas Recirculation Y/N N N

SCR

SCR Reactor - Number Installed N/A 2

Catalyst Type Hitachi Plate

NOx inlet / outlet lbs/Mbtu 0.347 / 0.035

NH3 Slip ppmdv @ ref O2 < 2.0 @ the End of Life

Air Heater

Air Heater - Number Installed - 2 2

Air Heater Type Rotary/Tubualr Ljungstrom Rotary Ljungstrom Rotary

Air Heater Orientation V-Shaft or H-S V-Shaft V-Shaft

Will Air Heater be changed? Y/N & to what? N N

Air Heater Surface configuration Model Numbers & Materials 27-VI-63 29-VI-54

Air Heater Cleaning Device - Steam Soot Blowers Steam Soot Blowers

Air Heater Leakage Percent 8 @ as-found condition Baseline Test

ESP

ESP's - Number Installed Number 2 2

ESP Info - Configuration Single layer or Stacked TBD by LG&E

ESP Info - Location Cold or Hot Cold Cold

ESP Dust Loading @ ESP Temp grains/ACF @°F 3.375 @ 300o

F

Dust Loading @ Eco. Out Temp grains/ACF @°F 2.294 @ 648o

F

ESP Info - Outlet Dust Loading grains/ACF @°F TBD by LG&E

ESP Efficiency % TBD by LG&E

WFGD

WFGD - Original Supplier Name Combustion Engineering American Filter

WFGD - Number Absorbers Operating / Installed Number 2 / 2 4 / 4

WFGD Info - Type Single Loop or Double Loop Single Single

WFGD Info - Spray Configuration Co-Current or Counter Current Counter Current Counter Current (Co-Current on Level 2)

WFGD Info - Spray Level Configuration Operating + Spare 4+0 + Tray 4+0 + Tray

WFGD Info - Reagent Lime or Limestone Limestone Limestone

WFGD Info - Original Design SO2 Loading lbs/Mbtu 6.3 6.3

WFGD Info - SO2 Removal Efficiency % Phase 1: 96, Phase 2: 98+ Phase 1: 96, Phase 2: 98+

Other

Ash Reinjection Yes or No No No

Draft System

FD Fan, Existing Number 2 / American Standard (595 rpm @ 110o

F)

Design Pressure IWG

Fan HP HP

ID Fan, Existing Number 2/ American Standard (690,000 cfm @ 300o

F) 2 / American Standard (834,950 cfm @ 300oF)

Design Pressure IWG 20 45

Fan HP HP

ID Booster Fan, Existing Number N/A N/A

Design Pressure IWG N/A N/A

Booster Fan HP HP N/A N/A

FGD Design Basis 

Spreadsheet

4 of 8 Date: 2/15/2011
LG&E Mill Creek

Rev. 0

FGD Load Data Sheet Units

Load Name Brown Units 1 & 2 Unit 3 Units 1 & 2 Unit 3

Load MW 750 330 425 330 425

Fuel Flow Rate lb/hr 676,790 148,894 148,894 128,049 95,879

Firing Rate Gross10^6 BTU/Hr 5,400 5,400 5,400 5,400 5,400

Excess Air % 25.0 25.0 21.5 25.0 25.0

In-Leakage % 20.0 20.0 23.5 20.0 20.0

Flue Gas Conditions @ Inlet Scope of Supply Ratio SCR Test Old Mat Bal Ratio

Flow Basis per Absorber 1 1 of 2 1 of 4 1 of 2 1 of 4

Flue Gas Flow Rate lbs/h wet 9,676,853 2,128,908 1,418,869 1,832,990 1,370,888

Flue Gas Flow Rate lbs/h dry 9,252,111 2,035,464 1,356,591 1,752,535 1,310,716

Flue Gas Flow Rate scfm wet 1,971,997 433,839 289,144 373,536 279,366

Flue Gas Flow Rate scfm dry 1,830,923 402,803 268,459 346,813 259,381

Flue Gas Flow Rate acfm 3,159,481 695,086 463,259 598,469 447,593

Flue Gas Temperature °F 330 330 313 330 313

Flue Gas Pressure I.W.G. 14.73 14.43 14.44 14.43 14.44

Flue Gas O2 % vol, dry 7.9 7.9 7.9 7.9 7.9

Flue Gas CO2 % vol, dry 11.0 11.0 11.0 11.0 11.0

Flue Gas H2O % vol wet 7.1 7.1 7.1 7.1 7.1

Flue Gas reference O2 % vol dry 6.0 6.0 6.0 6.0 6.0

Flue Gas SO2 *) ppmdv @ act O2 / lbs/MBTu 2,623 / 6.9 2,395 / 6.3 2,395 / 6.3 2,395 / 6.3 2,395 / 6.3

Flue Gas SO3 *) ppmdv @ act O2 / lbs/MBTu 26 8888

Flue Gas HCl *) ppmdv @ act O2 / lbs/MBTu 44 44 44 44 44

Flue Gas HF*) ppmdv @ act O2 / lbs/MBTu 99999

Flue Gas NOx *) ppmdv @ act O2 / lbs/MBTu

Flue Gas NH3 *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Dust *) grains/ dcfm lbs/MBTU 0.07 / 0.41 0.07 / 0.41 0.07 / 0.41 0.07 / 0.41 0.07 / 0.41

Flue Gas Hg *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Cd *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Heavy Metals *) ppmdv @ act O2 / lbs/MBTu

*) Concentration range is independent of the boiler load

Flue Gas Conditions @ outlet Scope of Supply expected values

Flue Gas Flow Rate lbs/h wet 10,356,857 2,278,509 1,518,574 1,961,796 1,467,221

Flue Gas Flow Rate lbs/h dry 8,704,210 1,914,926 1,276,255 1,648,751 1,233,096

Flue Gas Flow Rate scfm wet 2,184,799 480,656 320,346 413,845 309,513

Flue Gas Flow Rate scfm dry 1,861,975 409,635 273,012 352,695 263,780

Flue Gas Flow Rate acfm 2,624,304 577,347 384,789 497,096 371,776

Flue Gas Temperature °F 128 128 128 128 128

Flue Gas Pressure I.W.G. 14.62

Flue Gas O2 % vol wet 11.1 11.1 11.1 11.1 11.1

Flue Gas CO2 % vol wet 88888

Flue Gas H2O % vol wet 14.8 14.8 14.8 14.8 14.8

Flue Gas SO2 *) ppmdv @ act O2 / lbs/MBTu 52 / 0.14 47 / 0.13 47 / 0.13 47 / 0.13 47 / 0.13

Flue Gas SO3 *) ppmdv @ act O2 / lbs/MBTu 82222

Flue Gas HCl *) ppmdv @ act O2 / lbs/MBTu 00000

Flue Gas HF*) ppmdv @ act O2 / lbs/MBTu 00000

Flue Gas NOx *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Dust *) grains/ dcfm lbs/MBTU 0.02 / 0.12 0.02 / 0.12 0.02 / 0.12 0.02 / 0.12 0.02 / 0.12

Flue Gas Hg *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Cd *) ppmdv @ act O2 / lbs/MBTu

Flue Gas Heavy Metals *) ppmdv @ act O2 / lbs/MBTu

*) Concentration range is independent of the boiler load

FGD Design Basis 

Spreadsheet

5 of 8 Date: 2/15/2011
Coal & Reagent Data Sheet Units Unit 1 & 2 Unit 3 Unit 1 & 2 Unit 3

Design Coal Name Must be filled in

Coal Source: Coal Mine 2009 2009

Date Sample Taken: Date Average Average Design Design

Coal Ultimate Analysis As Received

Carbon (C) Wt% 61.61 61.61 60.30 60.30

Hydrogen (H) Wt% 4.22 4.22 4.50 4.50

Oxygen (O2) Wt% 7.01 7.01 6.80 6.80

Nitrogen (N2) Wt% 1.28 1.28 1.17 1.17

Sulfur (S) Wt% 3.02 3.02 3.47 3.47

Chlorine (Cl) Wt% 0.06 0.06 0.07 0.07

Fluorine (Fl) Wt% 0.01 0.01 0.01 0.01

Moisture (Water H2O) Wt% 11.43 11.43 9.56 9.56

Ash Wt% 11.36 11.36 14.12 14.12

Total Wt% 100.00 100.00 100.00 100.00

Wt. % Volatile Wt% 35.68 35.68 33.00 33.00

Wt % Fixed Carbon Wt% 41.54 41.54 42.00 42.00

Higher Heating Value Btu/lb, As Recvd 11,115 11,115 11,000 11,000

Reagent Name:

Reagent Source:

Date Sample Taken:

Reagent Analysis

CaCO3 wt.%

reactive CaCO3 wt.%

CaO wt.%

Ca(OH)2 wt.%

Fe2O3 wt.%

Al2O3 wt.%

SiO2 wt.%

MgCO3 wt.%

MgO wt.%

Mg(OH)2 wt.%

Chlorine (Cl) ppm

Fluorine (Fl) ppm

Moisture wt%

Inert wt%

FGD Design Basis 

Spreadsheet

LG&E Mill Creek

Rev. 0

6 of 8 Date: 2/15/2011
Process Water Data Sheet Units Design Min Max

Mist Eliminator Wash Water Analysis

pH

Conductivity mS/m

Total hardness mg/l

Carbonate hardness mg/l

Temperature °F

Suspended solids mg/l

Calcium as Ca2+ mg/l

Magnesium as Mg2+ mg/l

Sodium as Na+ mg/l

Chloride as Cl- mg/l

Sulphate SO4

2- mg/l

Sulphite SO3

2- mg/l

Make-Up Water Analysis

pH

Conductivity mS/m

Total hardness mg/l

Carbonate hardness mg/l

Temperature °F

Suspended solids mg/l

Calcium as Ca2+ mg/l

Magnesium as Mg2+ mg/l

Sodium as Na+ mg/l

Chloride as Cl- mg/l

Sulphate SO4

2- mg/l

Sulphite SO3

2- mg/l

Reclaim Water Analysis

pH

Conductivity mS/m

Total hardness mg/l

Carbonate hardness mg/l

Temperature °F

Suspended solids mg/l

Calcium as Ca2+ mg/l

Magnesium as Mg2+ mg/l

Sodium as Na+ mg/l

Chloride as Cl- mg/l

Sulphate SO4

2- mg/l

Sulphite SO3

2- mg/l

Service Water Analysis

pH

Conductivity mS/m

Total hardness mg/l

Carbonate hardness mg/l

Temperature °F

Suspended solids mg/l

Calcium as Ca2+ mg/l

Magnesium as Mg2+ mg/l

Sodium as Na+ mg/l

Chloride as Cl- mg/l

Sulphate SO4

2- mg/l

Sulphite SO3

2-

FGD Design Basis 

Spreadsheet

Mill Creek Units 1, 2, and 3

Rev. 0

7 of 8 Date: 2/15/2011
Gypsum Slurry Data Sheet Units U1&2 - Case 2 U1&2 Case 3 U3 Case 2 U3 Case 3

Recycle Slurry Analysis

Mass Flow Rate, per pump lb/hr 10,363,636 10,581,818 15,000,000 15,000,000

Volume Flow rate, per pump gpm 19,000 19,400 27,500 27,500

Estimated TDH

 Spray Level 1 ft, H2O 47.3 54.7 56.4 59.7

 Spray Level 2 ft, H2O 53.3 59.7 61.2 64.7

 Spray Level 3 ft, H2O 58.3 64.7 64.6 69.7

 Spray Level 4 ft, H2O 62.3 69.7 68.0 74.7

Specific Gravity 1.08-1.11 1.08-1.11 1.08-1.11 1.08-1.11

Density lb/ft3 66.8-69.3 66.8-69.3 66.8-69.3 66.8-69.3

Temperature °F 125-135 125-135 125-135 125-135

pH 5 to 6 5 to 6 5 to 6 5 to 6

Chloride as Cl- mg/l 5,000 5,000 5,000 5,000

Viscosity cp 7.00 7.00 7.00 7.00

Solids Content wt.% 14-18 14-18 14-18 14-18

Solids Stream

 Gypsum wt.% dry 85-95 85-95 85-95 85-95

 Limestone wt.% dry 1-3 1-3 1-3 1-3

 Inert wt.% dry 5-15 5-15 5-15 5-15

Special Notes:

FGD Design Basis 

Spreadsheet

Mill Creek Units 1, 2, and 3

Rev. 0

Pump TDH calculations are preliminary for cost estimate purposes only

Compressed air is injected in the reaction tank to complete oxidation reaction

No Change to existing Unit 3 pumps in Phase 1


 

 

LG&E Services Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Units 1 & 2
 

 

LG&E Services Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Units 3 & 4


Mill Creek Units 1, 2 and 3

Rev. 0

Unit 1 Unit 2 Unit 3

Materials Qty Comments Qty Comments Qty Comments

Recycle Pumps

Replace existing 8 recycle 

pumps and motors with gear 

driven centrifugal pumps, 3 at 

700 HP, 5 at 800 HP

Replace existing 8 recycle 

pumps and motors with gear 

driven centrifugal pumps, 3 at 

700 HP, 5 at 800 HP No Modifications

Recycle Discharge 

Piping 2000 LF

Increase diameter of all 

external recycle piping to 30" 2000 LF

Increase diameter of all 

external recycle piping to 30" No Modifications

Recycle suction 

pipe/flanges 8 pcs

Increase diameter of all 

external recycle pump suction 

piping to 30" 8 pcs

Increase diameter of all 

external recycle pump suction 

piping to 30" No Modifications

Recycle System 

Valves and inline 

equipment TBD

Replacement of all inline 

equipment in recycle system 

with 30" Dia. Includes valves, 

gaskets, replacement bolting, 

fittings. TBD

Replacement of all inline 

equipment in recycle system 

with 30" Dia. Includes valves, 

gaskets, replacement bolting, 

fittings. No Modifications

Spray Nozzles 336

Replace all spray nozzles with 

120 degree spray patter, 

Levels 1 & 4 will use doubledown nozzles, Levels 2 & 3 

will use bi-directional nozzles, 

all will be bolted connection 

type to connect to existing 

spray header, all alloy 

hardware for bolting. 336

Replace all spray nozzles with 

120 degree spray patter, 

Levels 1 & 4 will use doubledown nozzles, Levels 2 & 3 

will use bi-directional nozzles, 

all will be bolted connection 

type to connect to existing 

spray header, all alloy 

hardware for bolting. 576

Replace all spray nozzles with 

120 degree spray patter, 

Levels 1 & 4 will use doubledown nozzles, Levels 2 & 3 

will use bi-directional nozzles, 

all will use victaulic couplings 

to connect to existing spray 

header, with alloy pin and bolt 

on coupling.

Wall Baffles

Wall Baffles 4

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one 

at Spray level 3 centerline, 

with cutouts as necessary for 

nozzle installation. 4

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one 

at Spray level 3 centerline, 

with cutouts as necessary for 

nozzle installation. 8

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one 

at Spray level 3 centerline, 

with cutouts as necessary for 

nozzle installation. 

Oxidation Air Lances 240 LF

Install one Oxidation Air lance 

per absorber agitator (6 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material. 240 LF

Install one Oxidation Air lance 

per absorber agitator (6 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material. 10 pcs

Install one Oxidation Air lance 

per absorber agitator (5 Per 

absorber sump, 10 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material.

Air Lance Supports 6 pcs

High Nickel Alloy Material to 

be used consistent with 

process and Stress analysis 6 pcs

High Nickel Alloy Material to 

be used consistent with 

process and Stress analysis 10 pcs

High Nickel Alloy Material to 

be used consistent with 

process and Stress analysis 

Air piping external to 

sump 1000 LF

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header 

for distribution of Oxidation air 

to all lances. 20" Dia CS 

Piping material for ring 

header, down to 8" external 

feeding each lance. 1000 LF

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header 

for distribution of Oxidation air 

to all lances. 20" Dia CS 

Piping material for ring 

header, down to 8" external 

feeding each lance. TBD

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header 

for distribution of Oxidation air 

to all lances. 20" Dia CS 

Piping material for ring 

header, down to 8" external 

feeding each lance.

Air Piping hangers 59 pcs

External Oxidation Air pipe 

supports to be installed on 

vessel 59 pcs

External Oxidation Air pipe 

supports to be installed on 

vessel TBD

External Oxidation Air pipe 

supports to be installed on 

vessel 

Agitators 6

Install (6) side mount absorber 

agitators, new vessel 

penetration, external supports 

to grade required for each. 

Ekato, 2M blades anticipated 

for use. 6

Install (6) side mount absorber 

agitators, new vessel 

penetration, external supports 

to grade required for each. 

Ekato, 2M blades anticipated 

for use. 10

Install (5) side mount absorber 

agitators per sump (10 total), 

new vessel penetration, 

external supports to grade 

required for each. Ekato, 

1.6M blades anticipated for 

use.

FGD Upgrades - Equipment to be Modified

Slurry Recycle System

Oxidation Air System

Case 2

1 of 3 Date: 2/9/2011
Mill Creek Units 1, 2 and 3

Rev. 0

Unit 1 Unit 2 Unit 3

Materials Qty Comments Qty Comments Qty Comments

 Recycle Pumps 8

Replace existing 8 recycle 

pumps and motors with gear 

driven centrifugal pumps, 3 at 

700 HP, 5 at 800 HP 8

Replace existing 8 recycle 

pumps and motors with gear 

driven centrifugal pumps, 3 at 

700 HP, 5 at 800 HP 8 Gear Boxes regeared

 Recycle Discharge 

 Piping 2000 LF

Increase diameter of all 

external recycle piping to 30" 2000 LF

Increase diameter of all 

external recycle piping to 30" N/A

 Recycle suction 

 pipe/flanges 8 pcs

Increase diameter of all 

external recycle pump suction 

piping to 30" 8 pcs

Increase diameter of all 

external recycle pump suction 

piping to 30" No Modifications

 Recycle System 

Valves 

 and inline equipment

Replacement of all inline 

equipment in recycle system 

with 30" Dia. Includes valves, 

gaskets, replacement bolting, 

fittings. 

Replacement of all inline 

equipment in recycle system 

with 30" Dia. Includes valves, 

gaskets, replacement bolting, 

fittings. No Modifications

 Spray Nozzles 432

Replace all spray nozzles with 

120 degree spray patter, Level 

4 will use double-down 

nozzles, Levels 1, 2 & 3 will 

use bi-directional nozzles, all 

will be bolted connection type 

to connect to existing spray 

header, all alloy hardware for 

bolting. 432

Replace all spray nozzles with 

120 degree spray patter, Level 

4 will use double-down 

nozzles, Levels 1, 2 & 3 will 

use bi-directional nozzles, all 

will be bolted connection type 

to connect to existing spray 

header, all alloy hardware for 

bolting. 832

Replace all spray nozzles with 

120 degree spray patter, Level 

4 will use double-down 

nozzles, Levels 1, 2 & 3 will 

use bi-directional nozzles, all 

will use victaulic couplings to 

connect to existing spray 

header, with alloy pin and bolt 

on coupling.

 Spray Headers 8

Spray headers will be modified 

by addition of nozzles to each 

level and relocation of the 

levels to BPEI specified 

elevations above the 

perforated tray 8

Spray headers will be modified 

by addition of nozzles to each 

level and relocation of the 

levels to BPEI specified 

elevations above the 

perforated tray 16

Spray headers will be modified 

by addition of nozzles to each 

level and relocation of the 

levels to BPEI specified 

elevations above the 

perforated tray

Spray pipe hangers TBD

Additional pipe hangers will be 

installed to accommodate the 

additional nozzles and spray 

header piping added. TBD

Additional pipe hangers will be 

installed to accommodate the 

additional nozzles and spray 

header piping added. TBD

Additional pipe hangers will be 

installed to accommodate the 

additional nozzles and spray 

header piping added.

 Wall Baffles 4

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one 

at Spray level 3 centerline, 

with cutouts as necessary for 

nozzle installation. 4

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one at 

Spray level 3 centerline, with 

cutouts as necessary for 

nozzle installation. 8

Install 2 Wall Baffles, one at 

Spray level 2 centerline, one at 

Spray level 3 centerline, with 

cutouts as necessary for 

nozzle installation. 

Oxidation Air Lances 6pcs

Install one Oxidation Air lance 

per absorber agitator (6 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material. 6pcs

Install one Oxidation Air lance 

per absorber agitator (6 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material. 10 pcs

Install one Oxidation Air lance 

per absorber agitator (5 Per 

absorber sump, 10 total). 

Requires new vessel 

penetration, internal and 

external supports. 8" Dia 

Nickel Alloy Piping material.

Air Lance Supports 6 pcs

High Nickel Alloy Material to 

be used consistent with 

process and Stress analysis 6 pcs

High Nickel Alloy Material to be 

used consistent with process 

and Stress analysis 10 pcs

High Nickel Alloy Material to be 

used consistent with process 

and Stress analysis 

Air piping external to 

sump 1000 LF

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header 

for distribution of Oxidation air 

to all lances. 20" Dia CS 

Piping material for ring header, 

down to 8" external feeding 

each lance. 1000 LF

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header for 

distribution of Oxidation air to 

all lances. 20" Dia CS Piping 

material for ring header, down 

to 8" external feeding each 

lance. TBD

Modify existing Oxidation Air 

Piping external to absorber to 

accommodate a ring header for 

distribution of Oxidation air to 

all lances. 20" Dia CS Piping 

material for ring header, down 

to 8" external feeding each 

lance.

Air Piping hangers 59 pcs

External Oxidation Air pipe 

supports to be installed on 

vessel 59 pcs

External Oxidation Air pipe 

supports to be installed on 

vessel TBD

External Oxidation Air pipe 

supports to be installed on 

vessel 

Case 3 FGD Upgrades - Equipment to be Modified

Slurry Recycle System

Oxidation Air System

Wall Baffles

2 of 3 Date: 2/9/2011
Agitators 6

Install (6) side mount absorber 

agitators, new vessel 

penetration, external supports 

to grade required for each. 

Ekato, 2M blades anticipated 

for use. 6

Install (6) side mount absorber 

agitators, new vessel 

penetration, external supports 

to grade required for each. 

Ekato, 2M blades anticipated 

for use. 10

Install (5) side mount absorber 

agitators per sump (10 total), 

new vessel penetration, 

external supports to grade 

required for each. Ekato, 1.6M 

blades anticipated for use.

Outlet expansion joint 88 lf

Outlet Duct Expansion joints 

will be replaced. 88 lf

Outlet Duct Expansion joints 

will be replaced. TBD

Outlet Duct Expansion joints 

will be replaced.

317L Absorber shell 16,744 sf

Absorber shell will be modified 

with relocation of Spray 

Headers. Original 

penetrations will be filled while 

new ones are cut. 16,744 sf

Absorber shell will be modified 

with relocation of Spray 

Headers. Original penetrations 

will be filled while new ones 

are cut. 

Absorber shell will be modified 

with relocation of Spray 

Headers. Original penetrations 

will be filled while new ones 

are cut. 

Absorber Reheater 

Section

Reheater section will be 

removed and new ME section 

will be installed in its place

Reheater section will be 

removed and new ME section 

will be installed in its place

Reheater section will be 

removed and new ME section 

will be installed in its place

DV 210 Mist Eliminator 

and spray wash 

system TBD

In the previous Reheat section 

new Munters DV210 modular 

Mist Eliminator sections will be 

installed along with new ME 

wash piping system to supply 

wash water. TBD

In the previous Reheat section 

new Munters DV210 modular 

Mist Eliminator sections will be 

installed along with new ME 

wash piping system to supply 

wash water. TBD

In the previous Reheat section 

new Munters DV210 modular 

Mist Eliminator sections will be 

installed along with new ME 

wash piping system to supply 

wash water.

Absorber Shell and Ductwork Modifications

3 of 3 Date: 2/9/2011
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

A Oxidation Air System

Oxidation Air Compressor By Others By Others By Others By Others By Others By Others By Others Oxidation Air Agitators BPEI BPEI BPEI BPEI BPEI BPEI BPEI Oxidation Air Pressure Relief Valves BPEI BPEI BPEI BPEI BPEI BPEI BPEI External Headers BPEI BPEI BPEI BPEI BPEI BPEI BPEI Internal Lances BPEI BPEI BPEI BPEI BPEI BPEI BPEI Spray Nozzles BPEI BPEI BPEI BPEI BPEI BPEI BPEI Inlet Silencer By Others By Others By Others By Others By Others By Others By Others Inlet Filter By Others By Others By Others By Others By Others By Others By Others Instrumentation By Others By Others By Others By Others By Others By Others By Others Control Valves By Others By Others By Others By Others By Others By Others By Others Actuated Valves By Others By Others By Others By Others By Others By Others By Others Manuel Valves By Others By Others By Others By Others By Others By Others By Others PLC Controls By Others By Others By Others By Others By Others By Others By Others 

Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations By Others By Others By Others By Others By Others By Others By Others Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply By Others By Others By Others By Others By Others By Others By Others Motor Starters and Control Centers By Others By Others By Others By Others By Others By Others By Others Motors low Voltage By Others By Others By Others By Others By Others By Others By Others Motors medium Voltage By Others By Others By Others By Others By Others By Others By Others Pipes > 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes < 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm By Others By Others By Others By Others By Others By Others By Others Raceway, Conduit, Pullboxes, Wiring, Cabling on Skids By Others By Others By Others By Others By Others By Others By Others Heat Tracing (Freeze Protection) By Others By Others By Others By Others By Others By Others By Others Cathodic Protection By Others By Others By Others By Others By Others By Others By Others Plant Electrical and Mechanical Tie-In By Others By Others By Others By Others By Others By Others By Others 

A Absorber Recycle Pumps System

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 2 : Units 1, 2 & 3:4

1 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 2 : Units 1, 2 & 3:4

Absorber Recycle Pumps incl Gear Box BPEI BPEI BPEI BPEI BPEI BPEI BPEI Oil Circulation and Coolers BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Recycle Pipes External BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Recycle Pipes Internal BPEI BPEI BPEI BPEI BPEI BPEI BPEI expansion Joints BPEI BPEI BPEI BPEI BPEI BPEI BPEI Spray Nozzles BPEI BPEI BPEI BPEI BPEI BPEI BPEI Instrumentation BPEI BPEI BPEI BPEI BPEI BPEI BPEI Actuated Valves By Others By Others By Others By Others By Others By Others By Others Manuel Valves By Others By Others By Others By Others By Others By Others By Others PLC Controls BPEI BPEI BPEI BPEI BPEI BPEI BPEI Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations BPEI BPEI BPEI BPEI BPEI BPEI BPEI Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motor Starters and Control Centers BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motors low Voltage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motors medium Voltage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes > 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes < 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

Raceway, Conduit, Pullboxes, Wiring, Cabling on Skids BPEI BPEI BPEI BPEI BPEI BPEI BPEI Heat Tracing (Freeze Protection) BPEI BPEI BPEI BPEI BPEI BPEI BPEI Cathodic Protection BPEI BPEI BPEI BPEI BPEI BPEI BPEI Plant Electrical and Mechanical Tie-In BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

A Absorber Tower

Flow Models By Others By Others By Others By Others By Others By Others By Others Absorber Material By Others By Others By Others By Others By Others By Others By Others Side-Mounted Agitators BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminators Blades By Others By Others By Others By Others By Others By Others By Others Mist Eliminators Support Structure By Others By Others By Others By Others By Others By Others By Others Mist Eliminator Wash Headers internal By Others By Others By Others By Others By Others By Others By Others 

2 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 2 : Units 1, 2 & 3:4

Mist Eliminator Wash Headers external By Others By Others By Others By Others By Others By Others By Others Mist Eliminator Wash Headers internal Support By Others By Others By Others By Others By Others By Others By Others Absorber Internals BPEI BPEI BPEI BPEI BPEI BPEI BPEI Inspection Access Doors By Others By Others By Others By Others By Others By Others By Others Gas Sample Test Ports By Others By Others By Others By Others By Others By Others By Others Instrumentation By Others By Others By Others By Others By Others By Others By Others Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations By Others By Others By Others By Others By Others By Others By Others Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply By Others By Others By Others By Others By Others By Others By Others Motor Starters and Control Centers By Others By Others By Others By Others By Others By Others By Others Motors low Voltage By Others By Others By Others By Others By Others By Others By Others Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm By Others By Others By Others By Others By Others By Others By Others Plant Electrical and Mechanical Tie-In By Others By Others By Others By Others By Others By Others By Others 

Project / Construction AdministrationEnviromental Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Building Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Limestone Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Project Master Schedule BPEI BPEI BPEI BPEI BPEI BPEI BPEI Project Schedule- Design,Procure,Fabricate&Deliver BPEI BPEI BPEI BPEI BPEI BPEI BPEI Construction Safety Program BPEI BPEI BPEI BPEI BPEI BPEI BPEI Project Labor Plan BPEI BPEI BPEI BPEI BPEI BPEI BPEI QA/QC Program BPEI BPEI BPEI BPEI BPEI BPEI BPEI Start-up Field Service, Equipment Commisioning & Turnover BPEI BPEI BPEI BPEI BPEI BPEI BPEI Personnel Training BPEI BPEI BPEI BPEI BPEI BPEI BPEI O & M Manuals BPEI BPEI BPEI BPEI BPEI BPEI BPEI Optimization & Acceptance Testing BPEI BPEI BPEI BPEI BPEI BPEI BPEI Equipment Storage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Equipment Precommision Maintenance BPEI BPEI BPEI BPEI BPEI BPEI BPEI Construction Facilities - Temporary BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

3 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 2 : Units 1, 2 & 3:4

Construction Facilities - Permanent By Others By Others By Others By Others By Others By Others By Others Site Clean-up BPEI BPEI BPEI BPEI BPEI BPEI BPEI Asbestos Testing & Removal By Others By Others By Others By Others By Others By Others By Others Lead Paint Testing & Removal By Others By Others By Others By Others By Others By Others By Others Finish Painting and Field Touch-up BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

4 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

C Gas Path

Inlet Ductwork By Others By Others By Others By Others By Others By Others By Others Outlet Ductwork By Others By Others By Others By Others By Others By Others By Others Flow Models By Others By Others By Others By Others By Others By Others By Others Expansion Joints BPEI BPEI BPEI BPEI BPEI BPEI BPEI Ductwork Internals (flow screen, hoist beam) By Others By Others By Others By Others By Others By Others By Others New ID & Booster Fans By Others By Others By Others By Others By Others By Others By Others 

New ID & Booster Fan Motors By Others By Others By Others By Others By Others By Others By Others Inspection Access Doors By Others By Others By Others By Others By Others By Others By Others Gas Sample Test Ports By Others By Others By Others By Others By Others By Others By Others Insulation & Lagging For All Components By Others By Others By Others By Others By Others By Others By Others 

Instrumentation By Others By Others By Others By Others By Others By Others By Others 

Actuated Valves/Dampers By Others By Others By Others By Others By Others By Others By Others Manuel Valves/Dampers By Others By Others By Others By Others By Others By Others By Others 

Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply By Others By Others By Others By Others By Others By Others By Others Motor Starters and Control Centers By Others By Others By Others By Others By Others By Others By Others Motors low Voltage By Others By Others By Others By Others By Others By Others By Others Pipes > 2 in incl Support By Others By Others By Others By Others By Others By Others By Others Pipes < 2 in incl Support By Others By Others By Others By Others By Others By Others By Others Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm By Others By Others By Others By Others By Others By Others By Others Heat Tracing (Freeze Protection) By Others By Others By Others By Others By Others By Others By Others Cathodic Protection By Others By Others By Others By Others By Others By Others By Others Plant Electrical and Mechanical Tie-In By Others By Others By Others By Others By Others By Others By Others 

A Oxidation Air System

Oxidation Air Compressor By Others By Others By Others By Others By Others By Others By Others Oxidation Air Agitators BPEI BPEI BPEI BPEI BPEI BPEI BPEI Oxidation Air Pressure Relief Valves BPEI BPEI BPEI BPEI BPEI BPEI BPEI External Headers BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 3 : Units 1, 2 & 3:4

1 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 3 : Units 1, 2 & 3:4

Internal Lances BPEI BPEI BPEI BPEI BPEI BPEI BPEI Spray Nozzles BPEI BPEI BPEI BPEI BPEI BPEI BPEI Inlet Silencer By Others By Others By Others By Others By Others By Others By Others Inlet Filter By Others By Others By Others By Others By Others By Others By Others Instrumentation By Others By Others By Others By Others By Others By Others By Others Control Valves By Others By Others By Others By Others By Others By Others By Others Actuated Valves By Others By Others By Others By Others By Others By Others By Others Manuel Valves By Others By Others By Others By Others By Others By Others By Others PLC Controls By Others By Others By Others By Others By Others By Others By Others Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations By Others By Others By Others By Others By Others By Others By Others Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply By Others By Others By Others By Others By Others By Others By Others Motor Starters and Control Centers By Others By Others By Others By Others By Others By Others By Others Motors low Voltage By Others By Others By Others By Others By Others By Others By Others Motors medium Voltage By Others By Others By Others By Others By Others By Others By Others Pipes > 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes < 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm By Others By Others By Others By Others By Others By Others By Others Raceway, Conduit, Pullboxes, Wiring, Cabling on Skids By Others By Others By Others By Others By Others By Others By Others Heat Tracing (Freeze Protection) By Others By Others By Others By Others By Others By Others By Others Cathodic Protection By Others By Others By Others By Others By Others By Others By Others Plant Electrical and Mechanical Tie-In By Others By Others By Others By Others By Others By Others By Others 

A Absorber Recycle Pumps System

Absorber Recycle Pumps incl Gear Box - Unit 3 Gear Boxes only BPEI BPEI BPEI BPEI BPEI BPEI BPEI Oil Circulation and Coolers BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Recycle Pipes External BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Recycle Pipes Internal BPEI BPEI BPEI BPEI BPEI BPEI BPEI expansion Joints BPEI BPEI BPEI BPEI BPEI BPEI BPEI Spray Nozzles BPEI BPEI BPEI BPEI BPEI BPEI BPEI Instrumentation BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

2 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 3 : Units 1, 2 & 3:4

Actuated Valves By Others By Others By Others By Others By Others By Others By Others Manuel Valves By Others By Others By Others By Others By Others By Others By Others PLC Controls BPEI BPEI BPEI BPEI BPEI BPEI BPEI Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations BPEI BPEI BPEI BPEI BPEI BPEI BPEI Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motor Starters and Control Centers BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motors low Voltage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Motors medium Voltage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes > 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Pipes < 2 in incl Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

Raceway, Conduit, Pullboxes, Wiring, Cabling on Skids BPEI BPEI BPEI BPEI BPEI BPEI BPEI Heat Tracing (Freeze Protection) BPEI BPEI BPEI BPEI BPEI BPEI BPEI Cathodic Protection BPEI BPEI BPEI BPEI BPEI BPEI BPEI Plant Electrical and Mechanical Tie-In BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

A Absorber Tower

Flow Models BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Material BPEI BPEI BPEI BPEI BPEI BPEI BPEI Side-Mounted Agitators BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminators Blades BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminators Support Structure BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminator Wash Headers internal BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminator Wash Headers external BPEI BPEI BPEI BPEI BPEI BPEI BPEI Mist Eliminator Wash Headers internal Support BPEI BPEI BPEI BPEI BPEI BPEI BPEI Absorber Internals BPEI BPEI BPEI BPEI BPEI BPEI BPEI Inspection Access Doors By Others By Others By Others By Others By Others By Others By Others Gas Sample Test Ports By Others By Others By Others By Others By Others By Others By Others Instrumentation BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

Access Steel (including handrails, platforms, stairs, flooring, grating e By Others By Others By Others By Others By Others By Others By Others 

3 of 4
AREA ITEM DESCRIPTION Basic Engrg Detail Design Procure Fab Deliver Erect Consult Erection 

LG&E Service Company

Contract No. 501654

Mill Creek FGD Performance Upgrade Study

Case 3 : Units 1, 2 & 3:4

Structural Steel By Others By Others By Others By Others By Others By Others By Others Foundations By Others By Others By Others By Others By Others By Others By Others Electrical Hoists By Others By Others By Others By Others By Others By Others By Others Electrical Power Supply By Others By Others By Others By Others By Others By Others By Others Motor Starters and Control Centers By Others By Others By Others By Others By Others By Others By Others Motors low Voltage By Others By Others By Others By Others By Others By Others By Others Raceway, Conduit, Pullboxes, Wiring, Cabling (excludes skid equipm By Others By Others By Others By Others By Others By Others By Others 

Plant Electrical and Mechanical Tie-In By Others By Others By Others By Others By Others By Others By Others 

Project / Construction AdministrationEnviromental Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Building Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Limestone Licensing and Permits By Others By Others By Others By Others By Others By Others By Others Project Master Schedule BPEI BPEI BPEI BPEI BPEI BPEI BPEI Project Schedule- Design,Procure,Fabricate&Deliver BPEI BPEI BPEI BPEI BPEI BPEI BPEI Construction Safety Program BPEI BPEI BPEI BPEI BPEI BPEI BPEI Project Labor Plan BPEI BPEI BPEI BPEI BPEI BPEI BPEI QA/QC Program BPEI BPEI BPEI BPEI BPEI BPEI BPEI Start-up Field Service, Equipment Commisioning & Turnover BPEI BPEI BPEI BPEI BPEI BPEI BPEI Personnel Training BPEI BPEI BPEI BPEI BPEI BPEI BPEI O & M Manuals BPEI BPEI BPEI BPEI BPEI BPEI BPEI Optimization & Acceptance Testing BPEI BPEI BPEI BPEI BPEI BPEI BPEI Equipment Storage BPEI BPEI BPEI BPEI BPEI BPEI BPEI Equipment Precommision Maintenance BPEI BPEI BPEI BPEI BPEI BPEI BPEI Construction Facilities - Temporary BPEI BPEI BPEI BPEI BPEI BPEI BPEI Construction Facilities - Permanent By Others By Others By Others By Others By Others By Others By Others Site Clean-up BPEI BPEI BPEI BPEI BPEI BPEI BPEI Asbestos Testing & Removal By Others By Others By Others By Others By Others By Others By Others Lead Paint Testing & Removal By Others By Others By Others By Others By Others By Others By Others Finish Painting and Field Touch-up BPEI BPEI BPEI BPEI BPEI BPEI BPEI 

4 of 4
Activity Name Contract 

Number

Orig

Dur

LG&E Mill Creek Units 1-4 WFGD Upgrade Study 771

0

No Mill Creek Unit # 0

Engineering 0

Case - 2 714

Unit #1 337

Engineering 80Procurement 93Fabrication & Delivery 253Construction 80Outage 19Startup & Commissioning 20

Unit #2 337

Engineering 80Procurement 93Fabrication & Delivery 253Construction 80Outage 19Startup & Commissioning 20

Unit #3 274

Engineering 80Procurement 80Fabrication & Delivery 200Construction 21Outage 23Startup & Commissioning 20

Case - 3 771

Unit #1 391

Engineering 80Procurement 93Fabrication & Delivery 258

3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

LG&E Mill Creek Units 1-4 WFGD Upgrade St

No Mill Creek Unit # 

Engineering

Case - 2

Unit #1

Engineering

Procurement

Fabrication & Delivery

Construction

Outage

Startup & Commissioning

Unit #2

Engineering

Procurement

Fabrication & Delivery

Construction

Outage

Startup & Com

Un

Engineering

Procurement

Fabrication 

Case - 3

Unit #1

Engineering

Procurement

Fabrication & Delivery

Remaining WorkCritical Remaining WorkMilestoneSummary

Babcock Power Environmental Inc

Mill Creek FGD EPC Summary

Page 1 of 2
Activity Name Contract 

Number

Orig

Dur

Construction 105Outage 31Startup & Commissioning 20

Unit #2 412

Engineering 80Procurement 93Fabrication & Delivery 258Construction 100Outage 32Startup & Commissioning 20

Unit #3 331

Engineering 80Procurement 80Fabrication & Delivery 210Construction 35Outage 31Startup & Commissioning 20

3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Construction

Outage

Startup & Commissioning

Unit #2

Engineering

Procurement

Fabrication & Delivery

Construction

Startu

Engineering

Procurement

Fabrication 
Activity Name Orig

Dur

0

No Mill Creek Unit # 0

Engineering 0

Babcock Power Receive Notice to Proceed 0

Case - 2 714

Unit #1 337

Engineering 80

Design Calculations 20Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 93

Issue P.O. Recycle Pumps 10Issue P.O. Agitators 10Issue P.O. Spray Nozzles 10Issue P.O. Recycle Piping 10Issue P.O. Wall Rings 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 253

Fabricate Recycle Pumps 210Fabricate Agitators 180Fabricate Spray Nozzles 130Fabricate Wall Rings 150Fabricate Recycle Piping 180Fabricate Spray Piping Hangers & Hardware 120Fabricate Modified Oxidation Air Lances 140Fabricate Air Piping, Hangers & Hardware 100Deliver Spray Nozzles 10

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

No Mill Creek Unit # 

Engineering

Babcock Power Receive Notice to Proceed

Case - 2

Unit #1

Engineering

Procurement

Fabrication & Delivery

Remaining WorkCritical Remaining WorkMilestoneSummary

Babcock Power Environmental Inc

Mill Creek FGD EPC Detailed

Page 1 of 11
Activity Name Orig

Dur

Deliver Agitators 10Deliver Air Piping, Hangers and Hardware 10Deliver Spray Piping Hangers and Hardware 10Deliver Recycle Pumps 20Deliver Wall Rings 10Deliver Modified Oxidation Air Lances 10Deliver Recycle Piping 10

Construction 80

Mobilze Construction 10Excavate Recycle Pump Foundations 30Form & Pour Recycle Pump Foundations 30Run New Electrical Cables to Recycle Pumps 20Unload Outage Materials 5Set Up Scaffolding for Outage 10Inventory and Store Outage Material 10Set Up Recycle Line Rigging 10

Outage 19

Commence Outage 1Remove Electrical Recycle Pump & Motor 5Remove Misc. Electrical Interferences & Instrumentation 5Demo Recycle Pump and Motors 6Demo Recycle Outlet Lines to Spray Headers 5Set Recycle Pumps 5Install Wall Rings 5Remove Recycle Spray Nozzles 4Install Recycle Piping 10Install Agitators 7Align Recycle Pumps 10Install Oxidation Air Nozzles 10Reinstall Electrical Removed for Access. 3Reinstall Instrumentation Removed for Access. 3Outage Complete 1

Startup & Commissioning 20

Start Up and Commissioning 20

Unit #2 337

Engineering 80

Design Calculations 20

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Construction

Outage

Startup & Commissioning

Unit #2

Engineering
Activity Name Orig

Dur

Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 93

Issue P.O. Recycle Pumps 10Issue P.O. Agitators 10Issue P.O. Spray Nozzles 10Issue P.O. Recycle Piping 10Issue P.O. Wall Rings 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 253

Fabricate Recycle Pumps 210Fabricate Agitators 180Fabricate Spray Nozzles 130Fabricate Wall Rings 150Fabricate Recycle Piping 180Fabricate Spray Piping Hangers & Hardware 120Fabricate Modified Oxidation Air Lances 140Fabricate Air Piping, Hangers & Hardware 100Deliver Spray Nozzles 10Deliver Agitators 10Deliver Air Piping, Hangers and Hardware 10Deliver Spray Piping Hangers and Hardware 10Deliver Recycle Pumps 20Deliver Wall Rings 10Deliver Modified Oxidation Air Lances 10Deliver Recycle Piping 10

Construction 80

Mobilze Construction 10Excavate Recycle Pump Foundations 30Form & Pour Recycle Pump Foundations 30Run New Electrical Cables to Recycle Pumps 20Unload Outage Materials 5Set Up Scaffolding for Outage 10Inventory and Store Outage Material 10

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Procurement

Fabrication & Delivery

Construction
Activity Name Orig

Dur

Set Up Recycle Line Rigging 10

Outage 19

Commence Outage 1Remove Electrical Recycle Pump & Motor 5Remove Misc. Electrical Interferences & Instrumentation 5Demo Recycle Pump and Motors 6Demo Recycle Outlet Lines to Spray Headers 5Set Recycle Pumps 5Install Wall Rings 5Remove Recycle Spray Nozzles 4Install Recycle Piping 10Install Agitators 7Align Recycle Pumps 10Install Oxidation Air Nozzles 10Reinstall Electrical Removed for Access. 3Reinstall Instrumentation Removed for Access. 3Outage Complete 1

Startup & Commissioning 20

Start Up and Commissioning 20

Unit #3 274

Engineering 80

Design Calculations 20Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 80

Issue P.O. Agitators 10Issue P.O. Wall Rings 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Spray Nozzles 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 200

Fabricate Agitators 180Fabricate Wall Rings 150Fabricate Modified Oxidation Air Lances 140

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Outage

Startup & Com

U

Engineering

Procurement

Fabrication 
Activity Name Orig

Dur

Fabricate Spray Piping Hangers & Hardware 120Fabricate Spray Nozzles 130Fabricate Air Piping, Hangers & Hardware 100Deliver Air Piping, Hangers and Hardware 10Deliver Agitators 10Deliver Spray Piping Hangers and Hardware 10Deliver Wall Rings 10Deliver Spray Nozzles 10

Construction 21

Mobilze Construction 10Remove Electrical and I&C Interferences 15Unload Outage Materials 5Inventory and Store Outage Material 10

Outage 23

Commence Outage 1Install Wall Rings 5Remove Recycle Spray Nozzles 15Set New Recycle Pump Gear Boxes 20Install Agitators 7Install Oxidation Air Nozzles 10Reinstall Electrical Removed for Access. 10Reinstall Instrumentation Removed for Access. 10Align Recycle Pump Gear Boxes 5Outage Complete 1

Startup & Commissioning 20

Start Up and Commissioning 20

Case - 3 771

Unit #1 391

Engineering 80

Design Calculations 20Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 93

Issue P.O. Recycle Pumps 10Issue P.O. Agitators 10

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Case - 3

Unit #1

Engineering

Procurement
Activity Name Orig

Dur

Issue P.O. Spray Nozzles 10Issue P.O. Recycle Spray Headers 10Issue P.O. Recycle Spray Bull Horns 5Issue P.O. Mist Eliminator 5Issue P.O. Absorber Shell 10Issue P.O. Outlet Expansion Joint 5Issue P.O. Recycle Piping 10Issue P.O. Wall Rings 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 258

Fabricate Recycle Pumps 210Fabricate Agitators 180Fabricate Spray Nozzles 130Fabricate Recycle Spray Headers 200Fabricate Mist Eliminator 160Fabricate Recycle Spray Bull Horns 180Fabricate Absorber Shell 190Fabricate Outlet Expansion Joint 160Fabricate Wall Rings 150Fabricate Recycle Piping 180Fabricate Spray Piping Hangers & Hardware 120Fabricate Modified Oxidation Air Lances 140Fabricate Air Piping, Hangers & Hardware 100Deliver Spray Nozzles 10Deliver Agitators 10Deliver Air Piping, Hangers and Hardware 10Deliver Spray Piping Hangers and Hardware 10Deliver Recycle Pumps 20Deliver Mist Eliminator 10Deliver Wall Rings 10Deliver Modified Oxidation Air Lances 10Deliver Outlet Expansion Joint 10Deliver Recycle Spray Bull Horns 10Deliver Recycle Spray Headers 10Deliver Absorber Shell 20Deliver Recycle Piping 10

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Fabrication & Delivery
Activity Name Orig

Dur

Construction 105

Mobilze Construction 10Excavate Recycle Pump Foundations 30Run New Electrical Cables to Recycle Pumps 20Form & Pour Recycle Pump Foundations 30Set Up Scaffolding for Outage 10Set Up Recycle Line Rigging 10Unload Outage Materials 5Inventory and Store Outage Material 10Ground Fab Absorber Assembly 40

Outage 31

Commence Outage 1Remove Electrical Recycle Pump & Motor 5Remove Misc. Electrical Interferences & Instrumentation 5Demo Existing Absorber 5Demo Recycle Pump and Motors 6Demo Recycle Outlet Lines to Spray Headers 5Set Recycle Pumps 5Install Wall Rings 5Remove Recycle Spray Nozzles 4Install Recycle Piping 10Raise & Rig Absorber Section 2Install Agitators 7Align Recycle Pumps 10Weld Absorber Section 7Install Oxidation Air Nozzles 8Reinstall Electrical Removed for Access. 3Reinstall Instrumentation Removed for Access. 3Install New Outlet Expansion Joint 3Connect Exist. Outlet Ductwork to New Absorber 4Install Insulatation and Lagging to Absorber 8Outage Complete 1

Startup & Commissioning 20

Start Up and Commissioning 20

Unit #2 412

Engineering 80

Design Calculations 20

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Construction

Mobilze Construction

Outage

Startup & Commissioning

Unit #2

Engineering
Activity Name Orig

Dur

Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 93

Issue P.O. Recycle Pumps 10Issue P.O. Agitators 10Issue P.O. Spray Nozzles 10Issue P.O. Recycle Spray Headers 10Issue P.O. Absorber Shell 10Issue P.O. Recycle Spray Bull Horns 5Issue P.O. Mist Eliminator 5Issue P.O. Outlet Expansion Joint 5Issue P.O. Recycle Piping 10Issue P.O. Wall Rings 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 258

Fabricate Recycle Pumps 210Fabricate Agitators 180Fabricate Spray Nozzles 130Fabricate Recycle Spray Headers 200Fabricate Mist Eliminator 160Fabricate Recycle Spray Bull Horns 180Fabricate Absorber Shell 190Fabricate Outlet Expansion Joint 160Fabricate Wall Rings 150Fabricate Recycle Piping 180Fabricate Spray Piping Hangers & Hardware 120Fabricate Modified Oxidation Air Lances 140Fabricate Air Piping, Hangers & Hardware 100Deliver Spray Nozzles 10Deliver Agitators 10Deliver Air Piping, Hangers and Hardware 10Deliver Spray Piping Hangers and Hardware 10Deliver Recycle Pumps 20Deliver Modified Oxidation Air Lances 10

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Procurement

Fabrication & Delivery
Activity Name Orig

Dur

Deliver Mist Eliminator 10Deliver Outlet Expansion Joint 5Deliver Recycle Spray Bull Horns 10Deliver Absorber Shell 10Deliver Recycle Piping 10Deliver Recycle Spray Headers 10

Construction 100

Mobilze Construction 10Excavate Recycle Pump Foundations 30Run New Electrical Cables to Recycle Pumps 20Form & Pour Recycle Pump Foundations 30Set Up Scaffolding for Outage 10Set Up Recycle Line Rigging 10Unload Outage Materials 5Inventory and Store Outage Material 10Ground Fab Absorber Assembly 40

Outage 32

Commence Outage 1Remove Electrical Recycle Pump & Motor 5Remove Misc. Electrical Interferences & Instrumentation 5Demo Existing Absorber 5Demo Recycle Pump and Motors 6Demo Recycle Outlet Lines to Spray Headers 5Install Wall Rings 5Set Recycle Pumps 5Remove Recycle Spray Nozzles 4Install Recycle Piping 10Raise & Rig Absorber Section 2Install Agitators 7Align Recycle Pumps 10Weld Absorber Section 7Install Oxidation Air Nozzles 8Reinstall Electrical Removed for Access. 3Reinstall Instrumentation Removed for Access. 3Install New Outlet Expansion Joint 3Connect Exist. Outlet Ductwork to New Absorber 4Install Insulatation and Lagging to Absorber 8Outage Complete 1

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Construction

Mobilze Co
Activity Name Orig

Dur

Startup & Commissioning 20

Start Up and Commissioning 20

Unit #3 331

Engineering 80

Design Calculations 20Conduct CFD Modeling 40Conduct Physical Modeling 60Develop Equipment D&R Sheets 10Develop Mechanical Drawings 60

Procurement 80

Issue P.O. Agitators 10Issue P.O. Wall Rings 10Issue P.O. Spray Nozzles 10Issue P.O. Spray Piping Hangers & Hardware 10Issue P.O. Modified Oxidation Air Lances 10Issue P.O. Air Piping, Hangers & Hardware 10

Fabrication & Delivery 210

Fabricate Agitators 180Fabricate Wall Rings 150Fabricate Spray Piping Hangers & Hardware 120Fabricate Spray Nozzles 130Fabricate Modified Oxidation Air Lances 140Fabricate Air Piping, Hangers & Hardware 100Deliver Air Piping, Hangers and Hardware 10Deliver Agitators 10Deliver Spray Piping Hangers and Hardware 10Deliver Spray Nozzles 10Deliver Wall Rings 10

Construction 35

Mobilze Construction 10Unload Outage Materials 5Remove Electrical and I&C Interferences 15Inventory and Store Outage Material 10Ground Fab Absorber Assembly 20

Outage 31

Commence Outage 1Remove Electrical Recycle Pump & Motor 5

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month

Star

Engineering

Procurement

Fabricatio
Activity Name Orig

Dur

Remove Misc. Electrical Interferences & Instrumentation 5Demo Existing Absorber 5Raise & Rig Absorber Section 2Remove Recycle Spray Nozzles 4Install Wall Rings 5Weld Absorber Section 7Install Agitators 7Install Oxidation Air Nozzles 8Install New Outlet Expansion Joint 3Reinstall Electrical Removed for Access. 3Reinstall Instrumentation Removed for Access. 3Connect Exist. Outlet Ductwork to New Absorber 4Install Insulatation and Lagging to Absorber 8Outage Complete 1

Startup & Commissioning 20

Start Up and Commissioning 20

1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 

Month
LG&E Services Company 

Contract No. 501654 

Mill Creek FGD Performance Upgrade Study 

Budget Engineering, Procurement and Construction Estimate

February 15, 2011 

Description Engineering Equipment Construction Total

Case 2: Unit 1 $1,922,629 $5,365,667 $3,253,216 $10,541,512

Case 2: Unit 2 $1,922,629 $5,365,667 $3,343,710 $10,632,006

Case 2: Unit 3 $1,922,629 $6,735,206 $5,378,000 $14,035,835

Case 3: Unit 1 $2,949,580 $10,573,006 $6,905,881 $20,428,467

Case 3: Unit 2 $2,949,580 $10,573,006 $7,044,859 $20,567,445

Case 3: Unit 3 $2,949,580 $17,504,859 $12,489,678 $32,944,117