Analysis On Biomass Pyrolysis-gasification And Gas Combustion Cycle Process

Under the background of gradual depletion of fossil energy,air pollution becoming more and more serious and increasing global climate change,biomass energy suddenly rises and receives extensive attention of the worldwide for its many advantages-renewable,carbon neutral and environmental friendly.The development of biomass energy has been included in the national energy development strategy.By analyzing the current research status of biomass pyrolysis-gasification,this paper puts forward a kind of internal heating process-biomass pyrolysis-gasification and combustible gas combustion cycle process,in terms of defects of high tar yield,secondary pollution and low efficiency of gasification,which existing in biomass pyrolysis-gasification process.First biomass pyrolysis-gasification characteristics are analyzed under different atmosphere for air,air/H₂O and air/CO₂ using Aspen plus simulation software.Results show that adding the right amount of water or CO₂ to gasification agent will enhance the volume fraction of CO and H₂,then improve the calorific value of gas.So the new technology can effectively improve the efficiency of pyrolysis-gasification and gas calorific value,while gasification agent is mixtuer of N₂?CO₂?H₂O and O₂.The kinetic parameters are different for different types of biomass and gasification agent.In order to improve the accuracy of the model,kinetics of maize straw under the atmosphere of simulate flue gas are analyzed using STA 6000 thermal analyzer and AKTS dynamic analysis software.Activation energy changes as reaction proceed,so The pyrolysis process and gasification process follow different reaction mechanism,and each process has different activation energy.Then process simulation are put forward for the new technology and the conservation of energy and mass are calculated for whole circulation process.Through the exergy analysis of the circulation system to evaluate the performance of thermal equipment.Although mass and energy conservation,the circulation process exists exergy loss,and exergy efficiency is 86.67%.The pyrolysis-gasification process is the main reason for the exergy loss.Finally optimize analysis of the circulation process are conducted and the influence of flow rate of biomass and the volume flow of circulation flue gas on heat output are studied.With the increases of flow rate of biomass,heat output increases,but growth rate gradually decreases;Best proportion of circulation flue gas is 23%³1%to total flue gas.The more oxygen-enriched air,the greater the proportion of CO₂ in flue gas while N₂concentration of the combustible gas decreases,CO and H2 concentration increase,the energy output of the cycle process increases.The simulation results of this paper provide a favorable data and theoretical guidance for the practical production of biomass pyrolysis-gasification and combustion cycle process.