2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

Study of the full implementation of the SmartCleanTM System 

at SRP Navajo Power Generation Unit 3

Ati Manay, PMP, P.E. - Clyde Bergemann, Inc, Atlanta, GA, USA 

Danny S. Tandra, Ph.D. - Clyde Bergemann, Inc, Atlanta, GA, USA 

ABSTRACT 

Reliable power generation and optimum plant heat rate are the two most important targets that 

will determine the profitability of a coal fired power plant. Uncontrolled fouling and incorrect 

cleaning strategy in the convection sections will not only increase the plant heat rate, but may 

also lead to costly forced-outages due to sootblowing induced tube erosion. Conventional 

sootblowing systems, which are typically operated with a pre-determined sequence based on past 

experiences, cannot be efficiently tuned to keep up with the dynamic changes in the slagging and 

fouling conditions inside the boiler. Unlike conventional systems, SmartCleanTM Intelligent 

SootBlowing optimizes the plant heat rate and prevents heavy fouling by detecting the location 

and tenacity of the fouling in real-time and uses this information to dynamically manage the 

sootblower operation. The system also prevents over cleaning of the boiler tubes by triggering 

cleaning operations only when there is decay in the heat transfer performance of the heat 

exchangers. This paper discusses a case study of the full implementation of the SmartCleanTM 

Intelligent SootBlowing (ISB) system at SRP NAVAJO power generation station Unit 3. The 

newly installed (i) Super-Heater Fouling Monitor (SHFM) and the Thermo Dynamic Model 

(TDM) in the convection sections, is used to continuously monitor the cleanliness of the heating 

surfaces, and to evaluate the effect of sootblowing and resulting plant performance. (ii) 4 Smart 

USX adjustable cleaning intensity sootblowers are used to reduce the jet progression time on the 

areas where sootblowing related tube erosion has been experienced. The decreases in the 

Economizer Exit Gas Temperature (EEGT) and the reheat spray flow indicate that the thermal 

efficiency of the boiler was increased following the implementation of the ISB system and the 

plant heat rate has been improved by approximately 0.7%. The corresponding reduction in the 

CO2 emission was 4.29 tons/hr. The improvements in reliability and boiler availability by the 

SmartCleanTM system implementation will be evaluated in the next few years as Unit 3 was 

reconditioned in February 2009 with a major boiler overhaul. 

INTRODUCTION 

SRP Navajo Generating Station unit 3 is an 800 MW gross (750 MW net) sub-bituminous coal 

fired boiler. In the past the plant has experienced sootblower induced tube erosion at the nose 

arch, Superheater and Reheater Pendant sections of the boiler. Prior to the installation of the 

SmartCleanTM ISB system, all of the cleaning devices were manually operated according to the 

boiler operator’s discretion and the plant standard practices. The clearance for sootblowing at the 

nose arch area between the sootblower nozzle and the tube bank is less than 24” with a required 

40 feet travel length. Unit 3 has also experienced tube damage due to condensate purge at the 

first few feet of the travel. Forced boiler shutdowns took place due to sootblower related tube 

damage in the past years. As a result, Unit 3 was reconditioned in February 2009 with a major 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

boiler overhaul. Figure 1 shows the main challenges that SRP Navajo Station has dealt with on 

Unit 3 in the past years. 

Extensive research by both university and industry has revealed that over and under cleaning of 

boilers can significantly increase the risk of premature tube failure [1,2]. Over-cleaning causes 

sootblower-induced-tube erosion, while under-cleaning promotes coal ash corrosion, localized 

heat transfer increase and tube overheating. In addition, over and under cleaning will adversely impact 

the boiler thermal efficiency and most importantly impose a heavy penalty on the overall plant heat rate. 

Clyde Bergemann, Inc. SmartCleanTM ISB system was installed and commissioned in June 2009 

along with 4 Smart USX sootblowers on Unit 3 to reduce tube erosion as a reliability 

improvement project. 

The SmartCleanTM ISB system at SRP Navajo unit 3 consists of (i) 4 Smart USX 

adjustable/targeted cleaning intensity sootblowers, 28 conventional retractable sootblowers, 4 

SHFM (Zones 1 to 4), and 11 TDM (Zones 5 to 15) cleaning zones in the convection sections. 

Figure 2 shows an overview of the system. 

Figure 1: SRP Navajo Unit 3 Main Challenges 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

Figure 2 SRP Navajo Unit 3 SmartCleanTM ISB System 

SHFM (SuperHeater Fouling Monitor) is a network of strain gauges, mounted on the hanger 

rods of a boiler convection section, whose main purpose is to detect the change in the load 

experienced by the rod due to the accumulation of deposit in the convection section. 

Every time a sootblower is operated, the SHFM measures how much deposit is removed, in term 

of lb deposit removal. This information is then used by the ISB system to manage sootblower 

operation and to rank them according to its effectiveness in removing deposits. SHFM can also 

provide early detection of clinker formation and prevent it to grow to a larger size by selecting 

and sending appropriate sootblowers to control the formation. 

TDM (ThermoDynamic Model) is a thermodynamic program that uses boiler operating 

parameters to dynamically calculate the cleanliness factor (CF) of boiler convection sections. CF 

is the normalized heat transfer efficiency of the heat exchanger in real time. In other words, CF 

equals to one is the condition where the heat exchanger is clean and free from deposits. The CF 

information is used by the SmartCleanTM ISB system to determine whether to send sootblowers 

to clean the exchanger or to let it fouls to a certain level and achieve balanced heat transfer rate 

that benefits the overall boiler and plant performance. 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

ISB PERFORMANCE EVALUATION 

A performance evaluation of the SmartCleanTM ISB operation was conducted to compare it with 

that of the conventional SEQUENTIAL system on the overall boiler operating condition, thermal 

efficiency, and plant heat rate. The SEQUENTIAL runtime was selected for a 5 day period just 

before commissioning of the ISB system. The evaluation for the ISB counterpart was conducted 

for another 5 days period in the following year after 1 year of ISB operations. Similar seasons 

with similar ambient temperatures were selected to have a fair evaluation. No heat transfer 

surface additions or other system upgrades took place in between the two evaluation periods 

which can affect plant heat rate and boiler efficiency. 

RESULTS & DISCUSSIONS 

The convection sections consist of (i) SH Pendant Division Panel, (ii) Platen Superheater, (iii) 

Final Reheater, (iv) Finishing Superheater Pendant, and (v) Economizer, as depicted in Figure 1. 

The Final Reheater, and the Finishing Superheater Pendant were equipped with both the SHFM 

and TDM. The other sections of the boiler were equipped with just the TDM. Figure 3 compares 

the CF of the Platen 2nd Superheater when the boiler was run under ISB and SEQUENTIAL 

sootblower control. Both Sequential and ISB control resulted in similar number of sootblower 

operations per day. However, ISB initiated 92% of the cleaning operations below the clean level 

of 0.9 CF, reducing the risk of over cleaning and tube erosion. 

Figure 3. SmartCleanTM ISB Preventing Over Cleaning
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

BOILER THERMAL EFFICIENCY AND PLANT HEAT RATE 

The improvement of boiler thermal efficiency can be detected through at least two parameters: 

 Decrease in Reheat Spray Flow 

 Decrease in Economizer Exit Gas Temperature (EEGT) 

During the performance test period, the Reheat Spray Flow of the ISB system was 9 – 15 KPPH 

lower than that under SEQUENTIAL mode (Figure 4). 

Figure 4 – Comparison of Reheat Spray flow under Non-ISB and ISB modes

Decrease in Economizer Exit Gas Temperature (EEGT)

Figure 5 compares the ISB and SEQUENTIAL Economizer Exit Gas Temperature (EEGT) 

trends. The EEGT of the boiler run under ISB system is lower than that of the SEQUENTIAL 

mode in all boiler MW loads. The temperature under ISB mode was approximately 20 °F lower 

than the temperature under SEQUENTIAL mode. 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

Figure 5 – Comparison of Economizer Exit Gas Temperature under Non-ISB and ISB

Boiler Efficiency

The calculated improvement in the boiler efficiency is approximately 0.6% as a result of the 20 o

F improvement in the EEGT. 

Plant Heat Rate

The calculated improvement in the plant heat rate is approximately 0.7% (67btu/kwh) as a result 

of the 20 oF improvement in the EEGT and 15 kpph reduction in the reheat spray flow. 

This improvement can be written in terms of energy input savings as 

hr

Btu MW CapacityFactor

MWh

KWh

KWh

Btu 6 800 85%( ) 45.56 10

1

1000 67 =

ENVIRONMENTAL ANALYSIS 

CO2 Reduction by 0.7% Plant Heatrate Improvement

The reduction in the CO2 emission can be calculated directly by the reduction in the required 

energy input to produce the same power output. 

The energy input saved by the plant heat rate improvement was calculated to be 45,560,000 

btu/hr assuming a 85% capacity factor. 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

For the sub-bituminous fuel, if we use a Carbon content of 61% (as received) and a Higher 

Heating Value of 10,767 btu/lb (as received), the total reduction in Mass Fuel Carbon Flow Rate 

can be computed as 

hr

Tons

lb

Tons carbon content

btu

lb

hr

btu 1.17

2200

1 61%( ) 10,767

1 45,560,000 = 

Thus, the total reduction in mass CO2 emission can be derived as: 

hr

Tons

hr

Tons Total duction in Mass Fuel Carbon Flow 1.17 4.29

12

44 Re

Molecular Mass of C

Molecular Mass of CO2 = =

ECONOMIC ANALYSIS 

Fuel Savings through Plant Heat Rate Improvement:

Figure 6 illustrates the yearly savings in fuel cost by the 0.7% improvement in the plant heat rate. 

Figure 6 –Savings as a result of 0.7% Plant Heat Rate Improvement (arranged per Direct 

Cost of Power Generation) 
2010 CoalGen Conference – Pittsburgh, PA 

Aug 10 – 12, 2010

Potential Savings through CO2 Reduction:

Figure 7 shows the potential yearly savings as a result of the reduction of CO2 emissions with the 

implementation of the SmartCleanTM ISB System. The graph is arranged per $ penalty on ton of 

CO2 emission. 4.29 tons/hr CO2 reduction was used as the baseline for the calculation. 

Figure 7 –Potential Savings from CO2 Reduction 

 

BOILER RELIABILITY AND AVAILABILITY 

There were no forced outages caused by sootblower related tube erosion since June 2009. The 

improvements in reliability and boiler availability by the SmartCleanTM system implementation 

will be evaluated in the next few years as Unit 3 was reconditioned in February 2009 with a 

major boiler overhaul.

REFERENCES 

1. Coleman, K., Overcash, D. “Tube repair and protection from damage caused by 

sootblower erosion”. EPRI, Palo Alto, CA, 2004, Technical Report 1008037 

2. “Steam: Its generation and used” Edition 41, Babcock & Wilcox Company.2005 

3. Tandra, D.S., Shah, S. “Advanced Intelligent SootBlowing System using 

SmartSootblower” EPRI Sixth Intelligent Sootblowing Workshop, May 16 - 17, 2006.