The Ultimate ESP Rebuild: Casing Conversion 

 To a Pulse Jet Fabric Filter, a Case Study

 Presented at the Electric Power Conference, Rosemont, IL, May 2009 

 Published in the March 2010 Issue of Power Magazine 

 

 Thomas W. Lugar 

 Vice President 

 Buell Division 

 Fisher Klosterman 

 A CECO Environmental Company 

 

 Jeff Endrizzi 

 Plant Manager 

 Stu Schreurs 

 Principal Engineer 

 DJ Haggerty 

 Plant Engineer 

 Otter Tail Power Company 

 Big Stone Plant 

 Big Stone City, South Dakota 

Abstract

An Electrostatic Precipitator (ESP) may require major upgrade or replacement due to present and 

future emissions considerations such as the ESP is not meeting outlet emissions/opacity 

requirements due to fuel switching to a lower sulfur coal, addition of mercury emissions control 

by sorbent injection upstream of the ESP, addition of a wet or dry FGD system, and compliance 

with upcoming fine particulate control (PM2.5) regulations. A lower cost option to consider for 

compliance strategy is the conversion of the existing ESP casing to a pulse jet fabric filter. 

This paper discusses the decision making process, design, installation and performance of the 

electrostatic precipitator casing conversion to intermediate pressure, long bag pulse jet fabric 

filter at Otter Tail Power Company’s Big Stone Plant Unit #1, a 475MW cyclone-fired boiler 

burning PRB coal. The conversion was completed in late December, 2007. Also discussed is 

the criteria that makes an existing ESP a candidate for conversion to a fabric filter and the 

advantages and disadvantages of conversion. 
2

Introduction

In response to the Clean Air Act of 1970, hundreds of electrostatic precipitators (ESPs) were 

installed on coal-fired boilers throughout the U.S. The long established technology of the ESP 

was considered the best choice to meet the particulate emission requirements. The precipitator’s 

collection efficiency could be maintained within the normal variations in boiler operation but it is 

sensitive to the electrical characteristics of the fly ash as related to the type and source of the coal 

burned. These ESPs are now 25 to over 35 years old. Many have been rebuilt with new and 

improved plate and emitting electrode systems, power supplies and control systems. 

Today, there are new challenges for existing ESPs whether they have been rebuilt in the past or 

not. These challenges go beyond just meeting outlet emissions and stack opacity requirements 

and in some cases may require the replacement of the precipitator with a fabric filter baghouse. 

A cost saving alternative is conversion of the existing ESP casing to a pulse jet fabric filter if the

unit meets the criteria for conversion. 

Considerations for Replacement/Conversion to Fabric Filter

Present and future considerations that may include the option of replacing or converting the 

existing ESP with a baghouse include: a) the ESP is currently not meeting outlet emissions or 

opacity requirements, b) fuel switching has adversely effected ESP performance, c) adding a 

scrubber upstream or downstream of the ESP for SO2 reduction, d) control of mercury emissions, 

and e) control of PM2.5, future fine particulate control legislation. 

If the ESP is not consistently meeting outlet emission or opacity requirements due to aged 

internals and close electrical clearances between electrodes, then a rebuild is required. In some 

cases, the performance problems are compounded if the ESP is treating a higher than original 

design gas volume. When considering future emission requirements, this ESP may be a 

candidate for replacement or conversion with a fabric filter. 

Switching to a low sulfur coal, especially a sub-bituminous PRB, will result in a higher 

resistivity ash and degradation in ESP performance with de-rating required in many cases to 

maintain emission and/or opacity requirements. Depending on the severity of the performance 

deterioration, upgrade requirements may include the addition of sections to the ESP, gas 

conditioning, or replacement /conversion to a fabric filter. 

With the addition of a spray dryer FGD system for SO2 reduction, a pulse jet baghouse 

downstream is a logical addition due to the additional adsorption of SO2 in the baghouse filter 

cake reducing lime consumption requirements of the spray dryer. If a wet limestone forced 

oxidation FGD system is to be added producing commercial grade gypsum, the existing ESP’s 

performance needs to be evaluated. Depending on the amount of ash exiting the ESP and its 

chemical composition, potential problems could occur with the gypsum quality byproduct and 

the chemistry of limestone dissolution affecting SO2 removal efficiency. The role of the existing 

ESP, when adding a WFGD system, thus extends beyond achieving the stack opacity 

requirements. Depending on the mechanical condition of the ESP and whether it can consistently 
3

meet the required fly ash loading limitations to the scrubber, may require the consideration of 

adding a baghouse. 

The Clean Air Mercury Rule (CAMR) was vacated in early 2008 by the DC Circuit Court of 

Appeals followed by the same decision in July to vacate the Clean Air Interstate Rule (CAIR) 

that required significant reductions of sulfur dioxide and NOx in the eastern states. Despite the 

invalidation of the Mercury Rule, many states are moving forward with their own plans to limit 

mercury emissions from coal-fired plants. The Clean Air Interstate Rule was reinstated in 

December of 2008 while the EPA fixes flaws in the implementation/compliance plan. 

Reinstating the Mercury Rule is also expected. Thus, the requirements of the Mercury Rule are 

not going to go away, they are most likely to become more stringent. 

Mercury removal efficiency with sorbent injection is highly dependent on coal type, LOI, flue 

gas temperature, chlorine content in the coal, and SO3 content of the flue gas. A number of test 

programs with injection upstream of an ESP of various sorbents and enhanced sorbents 

conducted by a number of sorbent suppliers with funding from the DOE, show mercury removal 

rates of 30 - 90%. For many coal-fired plants, the best option presently for consistent, high 

mercury removal efficiencies (> 90%) is sorbent injection followed by a fabric filter. 

In the future, standards will likely be enacted for stationary sources limiting particulate matter of 

2.5 micron diameter and less. Solid particulate, as <PM2.5, would likely be limited to 0.01 or 

0.015 lb/MMBtu. Utilities may also need to control air toxics with particulate matter becoming 

the surrogate for a group of Hazardous Air Pollutants (HAPS) in the form of heavy metals, a 

large percentage of which are emitted from coal-fired boilers as fine particulates. For many 

older, relatively smaller SCA (collecting plate area/1000 acfm of flue gas treated) ESPs, 

performance upgrades required to achieve PM2.5 emission limits could be extensive with 

replacement or conversion of the existing ESP with a baghouse being a viable option. 

Due to the considerations discussed above, the conversion of an existing ESP casing to a pulse 

jet fabric filter, where applicable, is a process that is becoming increasingly common as more 

power plants seek air quality control system retrofitting to minimize emission and improve air 

quality. Many conversions have successfully been completed over the past 20 years in Europe, 

Australia, South Africa and in the U.S. A key to successfully applying this retrofit technology is 

using long filter bags and perfecting the ability to clean effectively the full length of these long 

bags which are typically over 25 feet long and presently up to 30 foot in length. 

Advantages of ESP to Fabric Filter Conversion

The advantages of converting an ESP casing to a pulse jet fabric filter include: 

• Lower cost option than replacing with a new ESP or new baghouse 

• Installed in the existing ESP footprint 

• Minimal ductwork modifications/additions 

• Reuse of existing hoppers and ash conveying system 

• Fuel Flexibility - a fabric filter is more forgiving than an ESP 
4

• Ready for more efficient and consistent mercury emissions reduction with sorbent 

injection 

• Ready for future PM2.5 legislated particulate emissions standards 

There are two basic criteria that must be met for an ESP to be a good candidate for conversion. 

The casing must be large enough in volume to accommodate the required cloth area and the 

casing should be structurally sound with a minimum of corrosion. Other considerations for 

conversion that must be evaluated include the additional pressure drop with a fabric filter, 

approximately 8” W.G., that may require the ID fans to be rebuilt or replaced and potential 

structural reinforcement of the ESP casing and ductwork if the original design pressure is 

exceeded. 

ESP to Pulse Jet Fabric Filter Conversion Case Study 

An ESP to fabric filter conversion was completed by Buell APC in December 2007 on Otter Tail 

Power Company, Big Stone Plant, Unit #1. The Big Stone Plant is located in Big Stone City, 

South Dakota. 

History

The Big Stone Plant was bought on line in 1975 with a Wheelabrator designed electrostatic 

precipitator for particulate emissions control. The 475MW cyclone-fired boiler originally burned 

North Dakota lignite coal. In 1995 the unit converted to burning sub-bituminous Powder River 

Basin coal. The precipitator consists of four chambers in parallel each with four electrical fields. 

Each field measured 40 ft high x 45 ft wide x 14’ deep. The plate spacing is 12” with 45 gas 

passages across each field. Guillotine type inlet and outlet dampers are used to close off a 

chamber if necessary. The discharge electrodes are ‘star’ wires mounted on pipe frame supports. 

Collecting plates are rapped with tumbling hammer rappers while the discharge electrodes use a 

falling hammer/cam-drop style of rapper. 

 ESP Inlet Flue Gas Design Conditions

 Gas Volume 2,100,000 acfm 

 Inlet Temperature 340oF 

 Inlet Loading 0.9 to 1.7 gr/acf 

 Mean Particle Size 6 microns 

With the switch to PRB coal, performance problems occurred with the ESP due to the higher 

resistivity ash and subsequent back corona formation resulting in problems meeting the 20% 

stack opacity limit. A humidification system was added to condition the ash but did not prevent 

back corona formation and performance problems persisted. A decision was then made in 1997 

to consider a potential ESP retrofit technology, the Advanced Hybrid Particulate Collector, being 

developed by the University of North Dakota’s Energy and Environmental Research Center 

(EERC). The Advanced Hybrid Particulate Collector (AHPC) technology development was 
5

initially supported by the Innovations for Existing Plants component of the DOE Fossil Energy 

R&D Program and then demonstrated under the Power Plat Improvement Initiative. 

The AHPC concept combines fabric filtration and electrostatic precipitation in the same housing. 

Fabric filter bags are interspersed with 45% open area perforated ESP collecting plates and 

emitting electrodes as shown in Figures 1 and 2. Flue gas first flows through the ESP charging 

and collection zone and then through the perforated collecting plates to the filter bags. During 

bag cleaning, a majority of the dust cake that is released from the bags during pulsing, is 

projected through the perforated plates and captured in the ESP zone. Optimum particulate 

collection is achieved by removing over 90% of the flyash in the electrostatic precipitator zone 

with final ash collection by the filter bags. With a majority of ash collected in the ESP zone, the 

fabric filter zone can be a high A/C ratio of 12 ft/min. Charge on the particulate enhances 

collection and minimizes pressure drop in the filtration zone of the AHPC since charged 

particulate tends to form a more porous dust cake. The barrier that limits operation at a high airto-cloth ratios is not so much the dislodging of ash from the bags as it is the transferring of the 

dislodged ash to the hoppers. The AHPC would overcome this limitation by trapping the 

released dust cake during pulsing in the electrostatic zone after being projected through the 

perforated plates. 

 

 

 

 Figure 1: AHPC Concept Plan View Figure 2: AHPC ESP & Filter Zones 

Following successful slipstream pilot testing (9,000 scfm) at the Big Stone Plant in 2001, the 

decision was made to retrofit the AHPC full scale into the three outlet ESP fields in each of the 

four ESP chambers with the inlet field in each chamber left in place but not energized. Each ESP 

chamber had 1226 filter bags of 6” diameter and 23’ long. The A/C ratio was 12.0 ft/min. with 

on-line cleaning used. The retrofit was completed in October 2002. 
6

Shortly after startup of the retrofit, performance problems began to occur and continued for the 

next two years. These problems included a high tubesheet differential pressure exceeding 10” 

W.G., continuous cleaning with pulse pressures raised to between 100 to 110 psi and bag failures 

occurring within 6 months. The result of these problems were boiler derates of 30 to 50 MW due 

to ID fan limitations with the high bag pressure drops and the stack opacity exceeding the 20% 

limit due to bag failures. During this two year period, a number of different bag types were tried 

as well as alternate bag cleaning strategies. Also, the ESP inlet field of each chamber was 

energized to pre-collect a portion of the ash loading before it entered the AHPC sections. 

In the spring of 2005, the inlet electrical field of each of the four ESP chambers was converted to 

AHPC to reduce the air-to-cloth ratio to 9.0 ft/min to reduce tubesheet pressure drops and the 

intensity of pulse cleaning to extend bag life. However, the same problems persisted and the 

AHPC technology was then abandoned. The key point of failure of this technology was that 

applying it to the Big Stone application would not eliminate the high resistivity ash condition and 

back corona formation which severely limited the effectiveness of the electrostatic zone of the 

AHPC. A decision was made by Otter Tail Power Company to replace the collector with a new 

conventional design pulse jet baghouse that would be built alongside the existing collector. The 

existing ESP would be demolished after tie-in of ductwork to the new baghouse. 

Buell Division of Fisher-Klosterman proposed to the Big Stone Plant management and 

engineering staff the cost saving alternate approach of converting the existing ESP casings to an 

intermediate pressure, long bag pulse jet fabric filter. The ESP met the criteria for conversion to 

a fabric filter. The casing volume was large enough to accommodate the required air-to-cloth 

ratio and the casing mechanical integrity was good. The ESP conversion to fabric filter would be 

less than half the turnkey cost of a total replacement with a new baghouse. With the ESP 

configuration of four independent chambers, an added benefit for a conversion was that each 

chamber could be blanked off during a short outage and then converted while on-line at a 

reduced boiler load. After competitive bidding, Buell was awarded a contract for engineering and 

material supply for the ESP to fabric filter conversion. Otter Tail Power Company contracted the 

construction scope directly. 

Big Stone Pulse Jet Fabric Filter Design Parameters

The pulse jet conversion design parameters are as follows. 

 A/C Gross: 3.4 A/C Net 1: 3.6 with Off-line cleaning 

 16 Compartments total, 4 compartments in each ESP Chamber 

 Interstitial/Can Velocity = 178 ft/min 

 Filter Bags: 21 oz. Woven fiberglass with PTFE membrane, 

 acid resistant coating, 6” diameter, 25’ long 

 Cages: Split cage, carbon steel, 24 wire 

 Bags/chamber = 4028, Total Bags = 16,112 

 27 bags per blowpipe, two (2) blowpipes per bag row 
7

 Guarantees

 Opacity - 10% 

 Outlet Loading - 0.01 lb/MMBtu 

 Bag Life - 3 years 

 Maximum ∆P - 8” W.G. 

Conversion Design and Construction

The ESP chambers were partially converted to a pulse jet with retrofit of the AHPC technology. 

The walk-in outlet plenums, vaned outlet dampers, and outlet ductwork installed with the AHPC 

retrofit were retained, Figures 3, 4, and 5. The ESP chambers were gutted with the removal of 

precipitator plates and emitters, support channels, rappers, bags, cages and tubesheets from the 

hybrid design. Gas flow baffle plates were removed from the inlet pyramidal nozzles. After all 

internals were removed, new tubesheets were installed supported by a shelf angle around the 

perimeter of each chamber. Three partition walls were installed in each chamber to 

compartmentalize each chamber into 4 pulse jet compartments. Each compartment utilizes offline cleaning by closing off the existing vaned damper located on the roof of the outlet walk-in 

plenum. No damper was added to the inlets of the compartments. An inlet transition duct with 

turning vanes was added to each inlet pyramidal nozzle that fed the gas flow to a pulse jet 

compartment inlet plenum that extended down the lower center of the chamber its full length. 

Gas flow entered each of the four compartments via a vaned opening on either side of the inlet 

plenum, Figures 6, 7, and 8. The top of the rectangular inlet plenum has a peaked ‘roof’ at the 

top to prevent buildup of ash from bag cleaning. 

For bag cleaning, a total of 32 completely shop assembled air header assemblies were installed 

utilizing a 4” Goyan solenoid valve for each blowpipe. Each row of 54 bags each on the 

tubesheet has two blowpipe assemblies with 27 bags per blowpipe and 19 rows per compartment, 

Figure 9. The blowpipe pulse discharge hole sizes vary along the length of the blowpipe to 

assure equalized pulse air cleaning volume to each bag from the intermediate pressure pulsing 

design. For access to the header assemblies and solenoid valves, three new platforms were 

installed: two outboard of the end precipitator chambers (with weather cover) and one under the 

existing control room located between the two pairs of ESP casings. For bottom access to each 

pulse jet compartment a walkway was added with a new side access door. 

A new control system was provided using an Allen Bradley PLC with a Control Logix 5561 

Controller to control the 608 pulse valves and 16 compartment outlet dampers, Figure 10. A 

cleaning cycle for the 16 compartments would be initiated when the integrated average of the 

four chambers’ pressure drop reaches a setpoint or by a timer control with a pressure drop 

setpoint over-ride. The pulse cleaning mode, with pulse pressures of 45 to 55 psi, is off-line 

cleaning but with the capability of on-line cleaning for outlet vaned damper maintenance if 

required. Each pair of blowpipes on either side of a row of 54 bags will be pulsed 

simultaneously in sequence from row 1 through 19. In the on-line cleaning mode, a staggered 

blowpipe pulsing sequence would be used. The individual compartment tubesheet differential 
8

pressures are monitored and compared to the before cleaning values to display the bag cleaning 

effectiveness. 

 

 

 

 

 Figure 3: Four ESP Chambers Figure 4: AHPC Walk-in Plenums, Vaned Dampers, 

 Outlet Tie-in Ducts Reused 

 

 

 Figure 5: Vaned Outlet Dampers on Walk-in Plenum Roofs 

 
9

 Figure 6: Side Elevation, Transition Duct and Inlet Plenum 

 

 Figure 7: Pan View of 4 Chambers, New Inlet Transition Duct and Plenum 

 

 

 Figure 8: Front Elevation, Inlet 
10

 

 Figure 9: Dual Blowpipe Arrangement per Bag Row, 27 Bags /Blowpipe 

 

 Figure 10: New Pulse Jet Baghouse Control Cabinet 

The outboard two ESP chambers were converted during the spring of 2007, one at a time, 

starting in early March. The first chamber was taken out of service in a short outage to allow 

blanking plates to be installed in the chamber’s inlet and outlet rectangular ducts. The first 

chamber was converted during a six week period, with the unit at reduced load, and started up in 

April 2007 followed by conversion of the second outboard chamber during a six week period 

with startup of the converted chamber in June 2007. During the summer and early fall, the unit 

operated with the two converted pulse jet chambers and the two chambers with the Advanced 

Hybrid Design. The remaining two ESP chambers were converted to pulse jet during a scheduled 

late fall outage and the complete conversion was on-line in December 2007. Construction 

pictures are included in Figures 11 through 18. 
11

 

 Figure 11: ESP Chamber Side Cut-Outs Figure 12: Compartment Tubesheet Shelf Installation 

 Figure 13: Pre-Assembly of Inlet Plenum Sections 

 

 Figure 14: Blowpipe Fabrication 

 

 Figure 15: Inlet Nozzle Transition Installation 
12

 

 Figure 16: Pulse Header Assemblies Figure 17: Pulse Header Assemblies Installed 

 Figure 18: Completed Compartment Tubesheet 

A number of steps were taken during the design, fabrication and construction phases of the 

conversion to assure the optimum performance of the baghouse. During fabrication, very tight 

tolerances were required and demonstrated for tubesheet flatness, tubesheet holes and spacing, 

blowpipe hole alignment and spacing, perpendicularity vertical centerline of attached split cages 

with the tubesheet, and filter bag width and length. During construction, Buell technical advisors 

provided daily QA/QC inspections to insure the required installation tolerances were achieved. 

During the design phase, both a numerical model study and physical model study were 

performed of the pulse jet gas flow configuration. To assure optimum pulse cleaning of the 27, 

25’ long bags on a blowpipe, blowpipe design and optimization tests were conducted by the 

pulse valve supplier in a series of laboratory tests. 
13

Model Study 

Buell contracted Airflow Sciences Corporation (ASC) to perform a flow model study to ensure 

that the new baghouse conversion configuration met the Institute of Clean Air Companies 

(ICAC) standards for flow uniformity. The flow study utilized both numerical and physical 

modeling techniques. The computational model of the Big Stone conversion scope was from the 

guillotine damper just upstream of the inlet nozzle to the induced draft fan inlets, Figure 19, 20 

and 21. 

 

 

 Figure 19: Numeric Model Scope Figure 20: Numeric Model Scope, Inlet Plenum 

 Figure 21: Sample Inlet Manifold and Plenum Numeric Run 
14

The goals of the numerical modeling were to assure the flow split between compartments in a 

chamber met ICAC F-7 criteria (within +/-10%) and to optimize gas flow distribution and 

minimize losses in the inlet transition to the fabric filter inlet manifold. The results of the 

computational model were that the flow split between the four compartments in a chamber met 

the ICAC criteria and several changes were made to the inlet transition vanes which improved 

the flow distribution and reduced the losses in this section over that of the baseline design. 

The physical model was 1/12 scale and, since the four chambers of the baghouse are identical, 

only a single chamber was modeled, Figure 22. The physical model scope extended from the 

inlet transition nozzle of the baghouse, through the outlet ducts to the common duct that leads to 

the ID fan inlets. The goals of the physical modeling were to confirm the numerical modeling 

results, ensure that no significant ash buildup occurred in the ductwork and inlet manifold floor 

through dust deposition tests and to quantify the system pressure losses. 

 

 Figure 22: 1/12 Scale Physical Model

The results of the physical modeling showed that there was good agreement between the 

numerical and physical model results and in the dust deposition tests, the majority of dust was 

swept clean from the inlet manifold floor at 75% of full load flow velocity and no significant 

buildup of dust was observed at 100% flow. The flow split between the four compartments was 

as follows. 

 % of Total Flow

 Compartment 1 (inlet) 23.1 

2 22.8 

3 26.6 

4 27.5 
15

Blowpipe Design and Optimization Tests

Blowpipe design optimization laboratory tests were conducted on the Big Stone blowpipe by 

Goyen Controls Co. Pty Ltd, Sydney, Australia. A 27 outlet blowpipe was fabricated per Buell’s 

specification with the addition of pressure tapping locations. Due to the pulse cleaning air flow 

required for 27 bags per blowpipe, 4” blowpipes and valves were selected. The goals of the 

blowpipe optimization tests were to determine the staggered pipe orifice sizes along the pipe to 

provide equal pulse air volume to each bag within +/-10%, determine the optimum blowpipe air 

straightening nozzle diameter, length, and height above the tubesheet and to determine the air 

consumption required per blowpipe. 

When testing a blowpipe system, the use of a clean filter bag is generally not very indicative of 

the cleaning performance with dust-laden filter bags. Rather than using a clean filter bags, 

Goyan accurately simulates a dust-laden filter bag using a jump pump duct. A significant 

advantage of the jet pump duct is that it is possible to simulate a range of dust loadings by 

altering the position of the blastgate (therefore altering the resistance to the pulse). This mimics 

the effect of varying dust loads on the filter bags. The jet pump duct is 3m long with a diameter 

of 150mm. A blastgate is located 1m from the entry of the duct. An orifice plate flow meter 

arrangement is located at the exit of the duct. Pressure taps are located halfway between the duct 

entry and the blastgate. Test runs along the blowpipe outlets were conducted at 45 and 60 psi 

pulse pressure. Results of the Flowrate Tests are plotted in Figure 23. A good distribution of 

cleaning flow along the blowpipe was achieved with cleaning flows within +/-10% of the 

average. 

 

 Figure 23: Flow Rate Distribution Along the Blowpipe 

Flowrate Distribution Along Blowpipe

0

50

100

150

200

250

1 3 6 9 12 15 18 21 24 27

Blowpipe Outlet

Flowrate (L/s)

45psi

60psi
16

Pulse Jet Conversion Operation

The conversion of the first two chambers was completed in the spring of 2007 and the 

conversion of the remaining two chambers was completed in December 2007. All performance 

guarantees have been met, i.e. stack opacity and pressure drop. The stack opacity has been 

essentially zero which prompted the Big Stone Plant to forego the outlet emission tests. In 2008, 

Big Stone Plant Unit #1 achieved its highest generation ever, since the plant came on-line in 

1975. Restrictions to generating capacity due to problems with meeting the opacity limit and/or 

exceeding the ID fans pressure drop limit are now in the past. 

Conclusion

Based on the many successful ESP casing conversions to pulse jet fabric filter including the Big 

Stone Plant discussed in this paper, the option of conversion of an existing ESP which is large 

enough to accommodate the required cloth area can, for many applications, provide a significant 

cost savings when compared to complete replacement. Each case will be different, no two ESP 

installation configurations are alike. With emphasis applied during the design phase to maximize 

shop assembly of components and minimize existing ductwork modifications, and with proper 

planning for demolition and installation during construction, a conversion of an existing ESP to 

fabric filter can, for most cases, be completed during a typical outage duration. Therefore, a 

conversion of an existing ESP can be a viable, cost effective option to consider to solve a current 

particulate emissions/opacity problem, for consistent and efficient mercury emissions control 

with sorbent injection, for particulate removal with the addition of a wet or dry FGD system and 

as a future compliance strategy for PM2.5 fine particulate control. 

References

Durham, M., Chang, R., Renninger, S., Monroe, L., Johnson, D.Chang. “Full Scale Results of 

Mercury Control by Injecting Activated Carbon Upstream of ESPs and Fabric Filters”. Presented 

at POWERGEN International, 2003. 

Gaikwad, R., Boward, W.L., “Economic Evaluation of Controls for PM2.5 - A Case Study”. 

Presented at the EPRI-DOE-EPA Combined Utility Mega Symposium, August 1999. 

Hrdlicka, T., Swanson, W., Demonstration of a Full-Scale Retrofit of the Advanced Hybrid 

Particulate Collector Technology, Final Report, 2006. Prepared for the United States 

Department of Energy, National Energy Technology Laboratory, DOE Award No. DE-FC26-

02NT41420. 

Precipitator Newsletter, May 2006, Issue 364, The McIlvaine Company.