Numerical Simulation Of Biomass Gasification Using High Temperature Air/Steam

Biomass,as an renewable and clean energy resource,how to achieve its efficient utilization,has received more and more widespread attention from counties all over the world.Among the biomass utilization technology,biomass gasification with highly preheated agent possesses the advantages such as making full use of low-rank fuel,high calorific value of gas,low tar content and low pollution characteristics,which has enormous potential and broad prospects.Therefore,study on simulation of biomass gasification with high-temperature air/steam is significant to its theoretical development and industrial application.In this paper,firstly of all,with corn straw char and Chinese fir char,the investigations of biomass char gasification with high temperature steam were preformed using Thermogravimetric analysis at 800℃～1000℃.The homogeneous volume model(VM),grain model(GM)and random pore model(RPM)was chose to describe the conversion process of corn straw char and Chinese fir char steam gasification.Compared with the VM model,GM model and RPM model fitted well with the experimental results.It is worth mentioning that the results of RPM model accorded with that of the experiment best.Secondly,with the principle of biomass gasification using high-temperature air/steam and the principle of Gibbs free energy minimization,based on the process smulation software Aspen Plus,the models of biomass gasification process has been establisheid and the experimental data was to validate the model.The simulation results exhibited a reasonable agreement with the experimental data,which showed that these models are of certain reliability and applicability.Finally,the characteristics of biomass gasification with high temperature air/steam were researched.With corn straw and Chinese fir sawdust as raw material,with the model of biomass gasification using high-temperature air/steam,the effects of main gasification technological parameters,ER value,preheated temperature of gasifiying agents and S/B value,on gas components,calorific value,and carbon conversion rate are researched according to the sensitivity analysis block of the software.The results showed that once increasing the ER value,the gas volume fraction of CH4 and H2 decreased while the carbon conversion rate accelerated.Simultaneously,the proportion of CO content in the syngas existed optimum values under the condition.In addition,the elevation of air/steam preheating temperature resulted in the increase of the gas volume fraction of H2 and CO,CO/CO2 values,gas calorific value,as well as carbon conversion rate.But the elevation of preheating temperature had negative effects on the yield of CH4.At last,increasing the biomass ratio(S/B)of the steam led to the increase of the proportion of H2 content,H2/CO values in the syngas and the increase of carbon conversion rate.By the way,the HHV of the syngas existed an optimum value of the S/B under this condition.