| OCR Text |
Show rate the average stack particulate emission rate was 0.1992 lb/10 Btu heat input which represented a 33 percent reduction from the unmodified emission rate. Recent design changes to incorporate "hopper evacuation" from the cyclone dust collector into the SGR process promise to reduce even further the particulate emission rate. The potential for SO emission control exists with the use of a limestone coal pellet and SGR. In laboratory tests on a 20-lb per hour coal stoker firing a coal/limestone pellet, 50 percent reduction in the S0~ emission were measured with the use of SGR. The SGR allows the fuel bed to operate at the lower temperatures necessary to "trap" the sulfur as a solid sulfide or sulfate and be disposed with the ash. CONCLUSIONS Combustion modifications to coal-fired stoker boilers have been implemented and tested on a 100,000 pph spreader stoker. The most promising modification is the use of flue gas recirculation into the main combustion air and the overfire air to control fuel bed clinker formation. This in turn allowed lower excess air combustion and resulted in boiler efficiency improvement thus saving fuel. The SGR process also reduces stack emissions of particulate, nitric oxide, and opacity as well as having the potential to reduce SO emission when used in conjunction with a limestone coal/pellet fuel. CI h y3^tf> , J^_ U ^XC cJ-J^Jx j^t^. ^ A o 7K, |
