Experimental Study And Simulation Analysis On External Heated Gasification Of Biomass Micron Fuel

Recently,there has been a serious shortage of fossil fuels.A series of environmental pollution caused by fossil fuels has seriously damaged the living environment of human beings.It is urgent to seek a clean and renewable energy to take place of the fossil fuels.Biomass is widely used because of the advantages of wide source,large reserves,and zero carbon dioxide emissions.Biomass pyrolysis and gasification technology are the most promising among many biomass utilization technologies.Because it have high energy conversion rate and the syngas can be transported by the pipelines,it can solves the problems about the utilizations of biomass and have caused more and more concerned by scholars.In this thesis paper,an external heated biomass gasification system was built by ourselves.It was used to conduct experiments to study the parameters of biomass gasification.The effects of reaction temperature,raw material particle size and S/B value on the gasification process were taken into consideration.A biomass baking system was established to explore the influence of baking pretreatment on the low heat value of biomass raw materials and the overall gasification efficiency.The experimental results show that with the increase of pyrolysis temperature,the volume fraction of H₂ and CO,carbon conversion rate,and gasification efficiency will all increase.With the decrease of the particle size of the raw material,the production of H₂ increases.It can promote the increase of low heat value of gas production,carbon conversion,and gasification efficiency.The introduction of proper amount water vapor will increase gas yield,carbon conversion,and gasification efficiency,but excess water vapor will reduce the temperature of gasification furnaces and reduce the gas quality.When S/B is 1.2,the carbon conversion rate will reach a maximum value of 83.64%,and the gasification efficiency will reach a maximum value of 90.36%.As the baking temperature increases and time extends,the low heat value of biomass,the fraction of H₂ and CO,carbon conversion rate increases and the gasification efficiency decreases.In order to accurately understand the reaction behavior in the gasification furnace,a kinetics model biomass gasification reaction was established based on software Ansys Fluent.The results show that the model can accurately predict the changing trend of production gas with different operating conditions.Through the analysis of temperature,composition and chemical reaction rate in the furnace,it is found that the temperature has a great influence on the reaction rate of the homogeneous phase.The change of S/B value will affect the reaction rate of methane recombination,carbon monoxide conversion,and the temperature in the furnace.Through the simulation,it is also found that the micron fuel is heated rapidly.The gas and biomass are mixed well in the furnace and the reaction happens quickly.The composition in the furnace tends to be stable at the distance of 0.5m away from the inlet and the gasification efficiency is better.The above results can provide theoretical guidance for the design of gasification device in the later stage of industrial demonstration project.