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January 26, 2011

To: Bansari Saha, ICF International

From: Jim Staudt, Andover Technology Partners

Re: DSI and Fabric Filter System Installation Labor Estimate

DSI

A dry sorbent injection system (DSI) has many of the same components as an activated carbon 

injection (ACI) system. The principal difference is that a DSI system generally injects a higher 

quantity of materials.

In Engineering and Economic Factors Affecting Installation of Control Technologies for 

Multipollutant Strategies (EPA-600/R-02/073, October 2002), the following estimates were 

developed for installation of an ACI system for a 500 MW boiler with a full load activated 

carbon injection rate of 815 lb/hr.

Labor Elements - ACI Manhours

Off site Engineering and On Site Testing 1600

Installation, Except Silo 1200

Erection of Silo 2000

Total 4800

Engineering and Economic Factors Affecting Installation of Control Technologies for 

Multipollutant Strategies (EPA-600/R-02/073, October 2002)

Thus, for a facility that injects at full load 815 lb/hour of activated carbon, the one-time labor 

needed for these labor elements totals about 4800 manhours. This does not include the labor 

associated with manufacturing the various components of the system – steel, piping, blowers, 

etc. It also does not include the sales, general, and administrative effort of the company that is 

supplying and installing the hardware, or some of the costs of general facilities or utilities 

needed for the ACI system. As a result, this estimate is a conservatively low estimate of the 

one-time jobs created by the installation of an ACI system. Also, this estimate does not account 

for the recurring jobs created by the need to operate and maintain the ACI system and to 

supply it with carbon each year.

For a DSI system, you would have many of the same cost elements as ACI, however, the 

material rate would be much higher, resulting in larger equipment. The engineering and testing 

element would not change dramatically. Although the sizing of an ACI system is largely 

associated with the gas flowrate, to maintain a prescribed sorbent injection concentration 

measured in lb/million actual cubic feet of flue gas, the material flowrate for a DSI system is a 
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function of the gas flowrate and the sulfur content of the fuel. This is because testing by Solvay 

has shown a relationship between HCl capture and SO2 capture. 1

A crude method of extrapolating the labor needed for such a DSI system from the estimates for 

an ACI system is to scale the labor elements to the material flow. Certainly, as the flowrates go 

up, the sizing of the equipment and effort needed to install it will increase. The off-site 

engineering and on-site testing will likely increase somewhat from the larger size equipment, 

but not to the degree of the installation labor. If the installation labor increases in proportion 

to the flowrate and the off-site engineering stays roughly the same, for that 500 MW 

bituminous coal unit injecting 80,000 lb/hr of Trona the labor would be 1600 

+(80,000/12,700)*(1200+2000) = 21,760 manhours, or about 43.5 manhours per MW. This, of 

course, is a rough estimate, but should be good for a start. Also, in estimating job benefit it 

should be conservatively low since it does not incorporate the benefit of jobs produced from 

manufacture of steel, pipe, blowers, valves, controllers, etc., or the sales, general and 

administrative jobs produced from suppliers.

Assuming an NSR of 2.0 for 

the sorbent injection rate (this is conservatively high), the injection rate of Trona for a 500 MW 

plant would be roughly 12,700 lb/hr at full load for a boiler firing PRB coal and roughly 80,000

lb/hr of Trona (sodium bicarbonate injection rate would be less) for a boiler firing 1.5% sulfur 

bituminous coal with a high chlorine content of 0.38% by weight. The particular bituminous 

coal example is chosen because it is the most likely type of facility to have the need for DSI 

under a MACT scenario because PRB coals have very low chlorine content and because boilers 

using high sulfur bituminous coals are likely to be scrubbed.

Fabric Filter

To develop a rough estimate the manhours for a fabric filter, I recommend that we estimate the 

amounts based upon information on SCR’s in EPA-600/R-02/073. My opinion is that a fabric 

filter, like an SCR, entails mostly erection of steel without the amount of process equipment 

(pumps, limestone preparation, etc.) or need for special alloys that are the case for a wet 

scrubber. An SCR can be somewhat more complex than a fabric filter and may require less 

structural steel because of the need for boiler integration that causes the SCR to frequently be 

installed at elevations-; however, that would be addressed by the somewhat lower cost of the 

fabric filter.

From EPA-600/R-02/073, total labor man-hours of construction and engineering labor for an 

SCR are about 365,000 man-hours for a single 500 MWe unit, or about 730 manhours per MW. 

Estimates developed by the Utility Air Regulatory Group2

 1 Davidson, Heidi, “Dry Sorbent Injection for Multi-pollutant Control Case Study”, CIBO IECT VIII, Portland, ME, 

August 2 –5, 2010

suggest possibly higher numbers, but 

nevertheless a wide range of estimates for labor demand due to the wide range of complexity 

of SCR projects. Fabric filter retrofits will also range in cost depending upon the amount of 

ductwork that is necessary.

2 Cichanowicz, J.E., Hein, M., Marchetti, J., “Analysis of CAIR Compliance Schedule: A Response to ICAC Estimates,” 

July 26, 2004.
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CUECost was used to estimate the capital cost of SCR and Fabric Filters. For a 500 MW plant, an 

SCR was estimated to be $153/KW in 2009 dollars escalating with the Chemical Engineering 

Plant Cost Index. For the same boiler, a fabric filter retrofit was estimated to be $87/KW, or 

about 57% of the cost of the SCR. Using the ratio of the capital cost as a gauge of the relative 

use of labor (both technologies involve a great deal of erected structural steel and steel plate), 

the labor demand for a fabric filter can be estimated to be roughly 416 manhours per MW. 

This, of course, is a rough estimate and may be well off for a particular application depending 

upon the amount of ductwork needed for the fabric filter. In estimating job benefit of a fabric 

filter installation it should be conservatively low since it does not incorporate the benefit of jobs 

produced from manufacture of steel, pipe, blowers, valves, controllers, etc., or the sales, 

general and administrative jobs at the fabric filter suppliers.