Results of the PDF{trademark} test burn at Clifty Creek Station

Abstract

Process Derived Fuel (PDF{sup TM}) from the ENCOAL process is different from other coals used to generate steam for the power industry. Although PDF{sup TM} is currently produced from Powder River Basin (PRB) subbituminous coal, the coal structure changes during processing. Compared to the parent coal, PDF{sup TM} contains much less moisture and slightly lower volatile matter resulting in a higher heating value and higher ash per million Btu. These coal properties can potentially benefit utility boiler performance. Combining the high combustion reactivity typical of PRB coals with significantly reduced moisture should produce higher flame zone temperatures and shorter flames. As a result, some boilers may experience increased steam production, better burnout, or lower excess air. The objective of the work contracted to Quinapoxet Engineering was to quantify the impacts of burning PDF{sup TM} on boiler performance at Clifty Creek Unit 3. A unique optical temperature monitor called SpectraTemp was used to measure changes in furnace exit gas temperature (FEGT) with time and boiler operating parameters for both PDF{sup TM} blends as well as a baseline coal blend consisting of 60% PRB coal, 20% Ohio coal, and 20% low-volatile eastern bituminous coal from Virginia. FEGT was then related to net plant heat rate, NO{sub x} emissions, and electrostatic precipitator performance.