Numerical Simulation Study Of Combustion Characteristics Of Low Calorific Value Gas In Porous Media Burner

With the rapid development of China’s economy and the increasing level of industrialization,the demand for energy continues to grow,while at the same time,the environmental problems caused by industrial production are becoming increasingly serious,and how to use energy efficiently and reduce pollutant emissions is the problem facing social development.Low calorific value gas as an associated gas in industrial production process,due to the low calorific value,there are difficulties in ignition and stable combustion,which leads to its low utilization rate and is usually directly discharged by enterprises,which not only causes waste of resources,but also damages the surrounding ecological environment.As a new combustion technology,porous media combustion technology has the advantages of combustion efficiency,wide range of load regulation,high combustion stability and low pollutant emission,which is in line with the characteristics of low calorific value gas.The application of porous media combustion technology to the combustion of low calorific value gas will hopefully improve the combustion of low calorific value gas.This paper takes blast furnace gas in low calorific value gas as the research object,establishes a three-dimensional model according to the physical parameters of the designed test boiler,and numerically simulates the combustion process of low calorific value gas in the model under different positions of porous medium by Fluent numerical simulation software.Six models of porous medium base at the position of L=0.1m,L=0.12m,L=0.14m,L=0.16m,L=0.18m and no porous medium were selected for the study.The change of velocity field and reflux zone in the burner,the change of ignition point and temperature field in the chamber were compared and analyzed by numerical simulation.The changes of combustible gas composition,oxygen composition and carbon dioxide composition in the low calorific value gas were analyzed under the conditions of different positions of porous media.The numerical simulation results show that with the backward movement of the porous media matrix,the influence of the porous media matrix on the disturbance of the reflux zone decreases.The physical structure of the porous media matrix and its own viscous resistance make the flue gas in leaving the porous media velocity from 15.5m/s to about 5.3m/s,which increases the residence time of the flue gas in the furnace chamber.As the porous media matrix moves backward,the peak flame temperature in the furnace chamber increases first and then decreases,and the location of the ignition point moves backward from 0.10084m at L=0.1m of the porous media matrix to 0.13765m at L=0.18m of the porous media matrix.when the porous media matrix is located at L=0.12m,the area of high temperature radiation in the furnace chamber is the largest,and the axial peak temperature is the highest.At this time,the combustion of blast furnace gas is the most adequate,the molar fraction of oxygen and combustible gas components at the exit of the furnace is the lowest,the molar fraction of carbon dioxide is the highest,and the combustion efficiency is the highest.