Coal char gasification with steam and H_2:II Modified random pore model

The characteristics of gasification reaction with steam or H2O/H2 mixed gases for Shenfu coal char pyrolyzed at 1 200 ℃ was studied at 875 ℃~950 ℃ and ambient pressure by TGA.The curves of gasification rate and carbon conversion of coal char gasification with steam and H2O/H2 mixed gases are quite different.The gasification rates with steam decrease steadily.However,the gasification rates with H2O/H2 mixed gases decreases rapidly at lower carbon conversion and then slowly at higher carbon conversion,which is fitted difficultly by the existed models.A new gasification kinetics model was proposed based on the random pore model.Comparing the experimental data and the curve fitted by the new models,it can be seen that the experimental data of coal char gasification with H2O/H2 mixed gases can be fitted perfectly and the correlation coefficients are all above 0.996.The kinetics parameters of coal char gasification with H2O/H2 mixed gases for the new model are: Ea(activity energy)=251.990 kJ/mol,k0(pre-exponential factor)=5.978 77×109 min-1.