Numerical Simulation Of Combustion Characteristics Of High Temperature Biomass Cyclone Flow

As a kind of clean new energy,biomass gas can be used in rural cooking and substitute for traditional fossil fuel for boiler and industrial industry.Biomass gas can not only reduce the global greenhouse effect and air pollution caused by the burning of fossil fuels,but also can become the power demand of human life and development.The problem of high tar content in biomass gas is the main problem of pyrolysis gasification of biomass.The tar problem of biomass gasification process can be effectively so lved by high temperature gasification.Based on the above ideas,this paper presents a new combustion equipment for burning high temperature biomass gas,that is,high temperature biomass gas obtained by direct combustion through high temperature gasificat ion.The main characteristics of the burner are: the use of biomass gas is high-temperature gas,because the biomass gas used in this paper is made by gasification of biomass through high temperature,the reason of using high temperature gasification is that it can solve the coking problem in the biomass gasification process,and direct the gasification gas at high temperature directly into the burner and the ambient air mixture combustion,Make full use of the heat after gasification,gas for pressurized gas,because biomass gasification process of low calorific value biomass gas volume is larger,not conducive to transport,reasonable pressure for gas transmission and save the transmission pipeline material.The high temperature biomass gas was simulated b y Aspen Plus software,then the structure of the swirl burner was calculated,and the structure size was determined by using fluent software.The flow characteristics of a swirl burner are simulated by the burner structure with different expanding cone angles and the length-diameter ratio of the combustor,the results show that when the angle of expanding cone is gradually increased from 70° to 110°,the size of the central Backflow zone formed in the double swirl combustor increases gradually,but the structure size of the burner changes less when it increases from 90° to 110°.When the length diameter ratio of the combustor is increased from 1.15 to 1.6,the size line of the central reflux region formed in the center return area decreases,and when the length diameter ratio is 1.3,the Central return zone formed in the combustor is the largest.According to the flow characteristics of the burner simulation results,the combustion characteristics of high temperature biomass gas were simulated by the double swirl burner with 1.3 combustion chamber length-diameter ratio(110°),and the temperature of combustion chamber and the distribution of NOx emission under different heat load conditions were investigated,and the results showed that: With the increase of the excess air coefficient,the temperature in the combustion chamber rises first and then decreases,and when the excess air coefficient is 1 o'clock,the temperature reaches the highest.The emission of NOx increases first and then decreases with the increase of excess air coefficient,and when the excess air coefficient is 1.1,the emission of NOx is the largest.With the increase of heat load,the range of high temperature zone in combustion chamber increases gradually,and the NOx emission increases gradually.