Influences of coal size and coal-feeding location in co-firing with rice husks on performance of a short-combustion-chamber fluidized-bed combustor (SFBC)

Combustion efficiency in an excess of 98% was readily achievable. CO and SO2 emissions (at 6% O2) were in the range 64-104 and 10-22 ppm, respectively, while NOx emissions were in the range of 208-281 ppm. Although the CO and SO2 emissions were acceptable, combustion of 100% rice husks and co-combustion with < 20% coal failed to comply with Thai NOx emission limits. Therefore, to minimize NOx emissions (208-244 ppm, at 6% O2), coal of both sizes was introduced below the recirculating ring. The results demonstrated that the thermal percentage of coal in the fuel mixture should be 20-25%.