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EVALUATION OF EMISSIONS AND CONTROL TECHNOLOGY FOR INDUSTRIAL STOKER BOILERS
Citation:
Giammar, R., R. Barnes, D. Hopper, P. Webb, AND A. Weller. EVALUATION OF EMISSIONS AND CONTROL TECHNOLOGY FOR INDUSTRIAL STOKER BOILERS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/7-81/090.
Description:
The report gives results of a three-phase program to evaluate emissions and control technology for industrial stoker boilers. In Phase I, emission characteristics were determined for a variety of coals fired in a 200-kW stoker boiler. It was observed that significant amounts of sulfur were retained in the lignite and western subbituminous coals. Fuel nitrogen conversion to NO was found to be between 10 and 20%. In addition, a limestone/coal fuel pellet was developed and found effective in capturing 80% of the fuel sulfur. Phase II focused on identifying and evaluating potential control concepts. Using an 8-MW spreader stoker boiler, it was found that improved control of combustion air (i.e., underfire and overfire air) resulted in lower excess air operation (improved efficiency), reduced particulate loading, smoke, CO and NO emissions, and no effect on SO2 levels. The limestone/coal pellet (Ca/S=7) was successfully fired, achieving 75% SO2 reduction. In Phase III, the limestone/coal fuel pellet was refined. A pellet was produced that had physical properties that could survive an industrial coal handling system. This pellet (Ca/S=3.5) was fired in the 8-MW boiler, achieving sulfur captures of 50%. The cost of this pellet would add approximately $1/million Btu to the cost of the raw high-sulfur coal.