Steam gasification kinetics of Binxian chars prepared at different conditions

The steam gasification reactivity of 3 chars from rapid pyrolysis, slow pyrolysis of raw coal and rapid pyrolysis of demineralized coal was studied at 900℃～1050℃ and atmospheric pressure in thermal balance. At the same time, the kinetic parameters of three chars were calculated and the specific surface area was determined with carbon dioxide absorption at 273K. The results show that gasification rate increases with increasing temperature which is an important factor influencing the gasification rate. The gasification rate doubles with an increasing temperature of 50℃. The reactivity of demineralized char increases at the beginning of gasification and subsequently decreases at higher temperature. The reactivity of two rapid pyrolysis chars is far higher than that of char prepared at low heating rate. Ash in the char can catalyze the gasification reaction at early stage and obstructs the reaction at higher carbon conversion. For the activation energy values, the slow pyrolysis char is the smallest and the rapid pyrolysis char is the biggest. The original gasification reactivity shows independence on the specific surface area.