Study On The Reaction Characteristics Of Biomass Gasification

The country’s economic aggregate has exceeded 100 trillion yuan.The rapid economic growth has been accompanied by higher energy demand.my country’s economy has entered a stage of high-quality development.However,local regions of the world are turbulent,energy supply is extremely unstable,and energy problems are Under the double crisis of environmental issues,the country needs clean and stable energy to support development.Biomass energy is a clean energy with zero carbon emissions.Biomass fuel gasification has become the main trend of clean biomass energy applications.The large-scale application of material energy is of great significance.The innovation of this paper is to study the gasification process of biomass briquettes at geometric scale.Based on CFD software,it simulates the influence of the thickness of briquette layer and the density of briquette fuel on the gasification effect,and the coupling of biomass semi-coke gasification The combustion boiler is tested to verify the accuracy of the simulation results.The main contents and conclusions of the research are as follows:Combining the mechanism and influencing factors of the molding process of biomass briquettes,and according to the characteristics of briquettes,summarize the performance indicators of briquettes suitable for gasification,and conclude that the density requirements for biomass briquettes for gasification should be less than 1000kg/m3,the crushing rate should be less than 5%,the water content of the briquette fuel should be controlled below 15%,and the ash content of the briquette fuel should not exceed 20%.Establish a biomass briquette fuel gasification chamber model,and use Fluent to perform simulation to study the gasification effect of briquette fuel layer under different deposition thicknesses.The fuel layer deposition thickness is 0.2m,0.25m,0.3m,0.35m,0.4m,respectively.By comparing the outlet flow rate and the generated amount of the effective components in the gasification gas during the gasification process,the results show that the amount of the effective components in the gasification gas does not achieve the desired doubling effect with the doubling of the fuel.The stacking thickness of the fuel layer needs to be controlled within a certain range.When the density of the forming fuel is 700kg/m3,the stacking thickness during gasification should be controlled at about 25cm-30cm.Under the same working conditions,set the stacked thickness of the formed fuel layer to 30cm,and the simulated formed fuel density is 600 kg/m3,700 kg/m3,800 kg/m3,900 kg/m3,respectively,from the gasified combustible gas Analyze the direction of the effective components of the fuel,the calorific value of the gas,and the carbon conversion rate of different densities.When the density of the fuel is from 600kg/m3 to 900kg/m3,the carbon conversion rate drops from 79.15%to 76.49%,indicating that the fuel The gasification reaction is insufficient,and the density of the briquettes should not be too high or too low.When the bulk thickness is 30cm,the appropriate density of the biomass briquettes should be controlled at 700-800kg/m3.The experimental study was carried out through the biomass semi-coke gasification coupled combustion boiler,and the simulation results were in good agreement with the experimental results.The gasification yield and gasification efficiency under different working conditions were calculated,and the carbon content of semi-coke and boiler ash was calculated.Analysis has verified that the coupled combustion of semi-coke gasification can effectively improve the fuel utilization rate.Finally,based on the economic evaluation,by comparing the system investment,operating cost and annual value of the biomass semi-coke gasification coupled combustion boiler,coal-fired boiler,gas boiler and electric boiler,it is concluded that biomass boiler It is less affected by changes in fuel prices,and has the lowest annual cost,which is more economical.