Investigation on Coal Pyrolysis in CO2 Atmosphere

Considerable Studies have been reported oil the coal pyrolysis process and the formation of SO2 and NOx processors such as H2S, COS, SO2, HCN, and NH3, in inert atmospheres. Similar Studies in CO2 atmosphere also need to be accomplished for better understanding of the combustion characteristics and the SO2/NOx formation mechanism of oxy-fuel combustion, which is one of the most important technologies for CO2 capture. In this study, thermogravimetry coupled with Fourier Transform Infrared (TG-FTIR) analysis was employed to measure the volatile yield and gas evolution features during coal pyrolysis process in CO2 atmosphere. Results show that replacing N-2 with CO2 does not influence the starting temperature of volatile release but seems to enhance the volatile releasing rate even at 480 degrees C. At about 760 degrees C, CO2 prevents the calcite from decomposing, In CO2 atmosphere. the volatile yield increases as the temperature increases and decreases as the heating rate increases. COS is monitored during coal pyrolysis in CO2 atmosphere while there are only H2S and SO2 formed in N-2 atmosphere. The COS is most likely formed by the reaction between CO2 and H2S. No NH3 was monitored in this Study. In CO2 atmosphere, the gasification of char elevates the conversion of char-N to HCN. The HCN yield increases as the temperature increases and decreases as the heating rate increases.