Study On Combustion Characteristics And Numerical Simulation Of Biomass Gasification Gas

Energy crises and environmental issues have accelerated the development and research of new energy sources.China's biomass energy reserves are abundant,and it is the only energy source that can stabilize the Internet among the three major renewable energy sources.The use of biomass power generation has broad development prospects.In this paper,the low calorific value biomass gas obtained by air gasification of circulating fluidized bed gasifier is taken as the research object,and the gas calorific value is 1260kcal/Nm³.Since the gasification process affects the composition of the gasification gas and thus affects the combustion characteristics of the biomass gas,it is necessary to study the effects of different components on the combustion characteristics of the biomass gas.Because the low calorific value biomass gasification gas studied in this paper has higher inert gas content and lower flame velocity,in order to better study the influence of different gas components on the flame velocity of biomass gas laminar flow at different speed levels,this paper firstly The laminar flame velocity of H₂/CH₄/CO synthesis gas with inert gas CO₂ and N₂ was studied by using the heat furnace test bench and Chemkin software to explore the effect of different components on the laminar flame velocity of syngas.Data support can also be provided for the test of the flame velocity of the biomass gasification gas laminar flow.It is found that both CO and H₂ can increase the laminar flame speed of syngas,and the higher the flame speed,the more obvious the lifting effect.When exploring the relationship between the equivalence ratio and the laminar flame velocity,it is found that increasing the CO and H₂ content,the equivalent ratio of the maximum flame velocity of the syngas increases,and the CO lifting effect is more obvious.For both inert gases,the inhibition of laminar flame velocity by CO₂ is more pronounced than that of N₂,the flame velocity of the gas is lower,and the equivalent flame ratio of the maximum flame velocity of the syngas is smaller.Then,using the thermal furnace test bench and the tube furnace high temperature reaction test bench,combined with the numerical simulation software Chemkin,the laminar flame velocity and NO emission characteristics of the typical low calorific biomass gas were studied.It was found that when the H₂ content is increased,the laminar flame speed of the biomass gas is increased and the NO emission is reduced.This is because the addition of H₂ increases the concentration of H radicals,increases the reaction rate of the relevant chain reaction,thereby increasing the laminar flame velocity of the biomass gas;meanwhile,the H radical promotes N+OH<=>The NO+H reaction occurs in the reverse direction,thereby reducing NO.When the CO₂ content is increased,the laminar flame velocity of the biomass gas is decreased,and the N₂content is relatively reduced,thereby reducing the source of the thermal NO.Therefore,when the ratio of CO₂ is increased,the NO emission is decreased.Finally,using Fluent to model the actual boiler,calculate the combustion state of low calorific biomass gas in practical industrial applications,and analyze the laminar flame velocity and combustion state of low calorific biomass gasification gas..The calculation results show that the temperature distribution in the furnace is uniform,and the air disturbance is more severe,and the mixing is good.However,when the H₂/CO ratio was changed,it was found that when the relative content of H₂was increased,the concentration of NO at the outlet of the furnace was slightly decreased and the concentration of CO was significantly increased.When the content of CO₂ was increased,the concentration of NO at the outlet of the furnace was lowered,and the concentration of CO was increased.The higher the combustion efficiency of the laminar flame,the higher the combustion stability.For the biomass gasification gas studied in this paper,the H₂ content in the gas is increased,and the proportion of CO₂ in the inert gas is controlled at about 40%,which can simultaneously consider the combustion performance and pollutant emission of the boiler.