Kinetics of char gasification at high temperature and pressure

In this paper,the char sample was made by the rapid pyrolysis of coal at different temperatures and pres- sures. The kinetics of CO2 / char gasification reaction was measured by a thermogravimetric analyzer to get the data in- trinsic reactions. The Thiele modulus was employed to characterize the relation of reaction / diffusion and to predict the effects of diffusion and intrinsic reaction in the apparent reaction at high temperature and pressure. The char sample made with a higher pyrolysis temperature or lower pressure has a faster apparent gasification reaction rate. With the in- crease of reaction temperature or the decrease of reaction pressure (CO2 partial pressure),the value of Thiele modulus increases,and the apparent reaction moves from kinetic control to diffusion control. With the increase of pyrolysis pres- sure,the Thiele modulus of the whole reaction decreases,which makes the apparent reaction stay in kinetic control are- a;while the pyrolysis temperature has little influence on the Thiele modulus. At the same reaction temperature,for the char sample with smaller pore size,the diffusion is more likely to affect the apparent reaction ( the Thiele modulus above 0. 4).