ULTRACLEAN COMBUSTION OF COAL IN AHLSTROM PYROFLOW PCFB COMBUSTORS

摘要

Current coal-based energy conversion systems focus on improved environmental performance and efficiency enhancement. Circulating fluidized bed (CFB) combustion technology has demonstrated its potential in achieving excellent emission control capabilities. Ahlstrom Pyropower is developing pressurized circulating fluidized bed combustors (PCFB) to enhance energy conversion efficiency by incorporating the proven advantages of CFB technology. In its 10 MW{sub}(th) pilot plant, Ahlstrom has tested many types of coal with and without the addition of sorbents. Recently tested coals include Western subbituminous, Kentucky bituminous and Illinois No.6 bituminous coals. This paper will present SO{sub}2 and NO{sub}x emissions from testing of these fuels and techniques used to control the pollutants. A NO{sub}x emission model has been developed showing that the oxygen to nitrogen ratio in the fuel plays a major role in the overall NO{sub}x emission. Inherent alkali in coal ash has shown to be very effective in absorbing fuel sulfur. Using the emission control techniques developed, it is possible to reduce SO{sub}2 emissions 95-99% of the uncontrolled value and NO{sub}x emissions to less than 30 ppmvd. The potential for meeting very strict emission regulations in the foreseeable future will be highlighted.