Influence of High-Temperature and High-Pressure Pyrolysis Conditions on Gasification Reactivity of Coal Chars with Carbon Dioxide

Abstract

IGCC processes have been actively developed domestically and overseas to reduce carbon dioxide emission. Gasifiers in these processes are operated at high temperature and pressure. For example, the pressure is about 3 MPa and the temperature peaks at 2000 K. In order to discuss the properties of rapid pyrolysis, which is the initial reaction in coal gasification, rapid pyrolysis tests were performed for four coals using a pressurized drop tube furnace facility (PDTF) operated at high temperatures and pressures. The results indicated that pyrolysis temperature rather than pressure had a great influence on char reactivity of the product char. The higher the pyrolysis temperature, the lower the gasification reactivity for some coals. The reactivity of these chars had a good correlation with the graphitization of carbon in char. On the other hand, the pyrolysis temperature had little influence on the reactivity for coal with high ion-exchangeable calcium content, which maintained its reactivity at high temperatures.