A model was developed using process simulation software Aspen Plus and verified based on the onsite data.The results fit the current situation well

with the maximal error less than 7.05%.The model was used to optimize the operating condition of a fixed bed gasifier.The effects of three important parameters on evaluating index were investigated in this study: the flow rates of air and steam

the preheating temperatures of air and steam

and the actual air flow rates in summer and in winter with the same volume flow rate.The results show that when the air flow rate is 18 kg·s-1

under the current operational condition

the gasification index is the best

and all the factors should be taken into account to obtain the steam flow rate.In the simulation temperature range

the gasification index is improved with a rise of temperature.The gasification index in winter is better than in summer.