SULFUR OXIDE EMISSION AND LIMESTONE UTILIZATION IN 2-STAGE SWIRL-FLOW FLUIDIZED-BED COMBUSTION OF SEWAGE-SLUDGE

Sewage sludge combustion experiments are carried out to investigate the effect of operating parameters on SO2 capture and limestone utilization in a two-stage swirl-flow fluidized-bed combustor. Operating parameters investigated in the study are the Ca/S molar ratio, superficial gas velocity, bed temperature, air-fuel ratio, and particle size of limestone. The experimental results show that the increase of the Ca/S molar ratio results in the increase of SO2 capture, whereas it causes the decrease of the limestone utilization. The SO2 capture tends to increase with the superficial gas velocity and total air-fuel ratio, but has a maximum value at a temperature of about 800-degrees-C. It is also noted that a smaller limestone size significantly enhances the SO2 capture and the limestone utilization.