Sulfur behavior during coal combustion in oxy-fuel circulating fluidized bed condition by using TG-FTIR

The sulfur behaviors of coal pyrolysis and combustion in air and oxy-fuel circulating fluidized bed (CFB) conditions showed that during coal pyrolysis, a significant increase of weight loss and CO emission were presented in CO2 atmosphere at temperature above 900 K, then the increase of CO emission promoted the transformation of H2S and other sulfur compounds to COS, and led more SO2 emission by reduction of CaSO4. The main sulfur-containing gas changed from H2S in N2 atmosphere to COS in CO2 atmosphere. In oxy-fuel combustion, less SO2, more H2S and COS released compared with those in air combustion, the SO2 became the main sulfur-containing gas. With the O2 concentration increasing, more SO2, COS and H2S released at lower temperature by faster burning. As the particle size and heating rate increasing, the SO2 and H2S emission increased, and the COS emission decreased. Finally the comprehensive characteristics of sulfur behavior were proposed.