Experiment And Simulation Research Of Burner For High Temperature Low Calorific Value Gas

Widely used in metallurgy, cement industry, steel industry and building materials,high temperature gas is expected to make full use of low quality coal to save energy andreduce emissions. The State Key Laboratory of Coal Combustion developed a newgeneration of ultra-high temperature gas system, which combined the fluidized bed coalgasification and fluidized bed combustion. Based on this technology, and according to theresults of preliminary research on a kiln burner accumulated in cold tests, an experimentalplatform for high temperature low calorific value gas burner has been developed in ourstudy. Based on the methods of numerical simulation and hot tests, the combustionperformance of the burner has been studied and improved.First, an experimental platform for high temperature low calorific value gas burner hasbeen developed and constructed. The experimental platform consists of low calorific valuegas preparation system, oxygen-containing flue gas preparation system, gas preheatingsystem, burner for high temperature LCV gas, combustion chamber, heat exchanger andexhaust system. And we focus on the thermal modeling design of the burner andcombustion chamber, which is key point of the whole design.Second, a three-dimensional model for the burner and made numerical calculation isdesigned using Fluent software, which enables to make detailed description of velocityfield, temperature field, the shape of the flame. In doing this, the impacts of the lowcalorific value gas and oxygen-containing flue gas preheating temperature on the maximumand average temperature of the combustion chamber and the flame length have beenanalyzed in detail.Third, the internal resistance of the burner is investigated under different loads in coldtests. The results show that the internal resistance of the burner is very low. By measuringthe axial velocity distribution at the central axis, it is found that it`s failed to form a stablecentral recirculation zone at the nozzle of burner. Testing the electric stoves and electricwires, it is found that the maximum preheat temperature of the gas side and the oxygencontaining flue gas side are670℃and645℃respectively, with the air flow of10m~3/h. Fourth, the hot tests indicates that the flame will blow off when combusting a highvalue calorific gas of methane. When combusting a mixture of methane and nitrogen withthe total heat value of16.31MJ/m~3, the flame is seriously blown off the burner and veryunstable. In this condition, if continuing to increase the nitrogen flow, the flame isextinguished immediately. It is concluded that the original burner can`t combust lowcalorific value gas.Fifth, according to the thermal state experimental phenomena and problems, weoptimized and improved the original burner. Improved burner can continue to combust thelow calorific value gas of4.0MJ/m~3. The flame is stable and distributed properly under thepreheating temperature of660℃. The structure of the improved burner is reasonable andfits the process requirements of ultra high temperature flue gas. Our research provides agood foundation for the industrial applications of high temperature and low calorific valuegas burner.