Influence Of Reaction Condition On The Entrained-flow Coal Gasification And Its Ash Fusion Characteristics

The coal electricity will still dominate in China’s future electricity energyformation. With the increase of requirements for environment protection, we need todevelop new coal cleaning combustion technologies. IGCC is a good choice, especiallycombined with CO2removal technology. IGCC has an evident cost advantage withother coal burning technologies. The gasifier and the waste heat boiler are the keyequipments of IGCC plants, but they have high manufacturing cost and have manyproblems during actual operation process. So it is very important to know the keysuccess factor of gasification process and the fusion mechanism of slag in entrained-flow pulverized coal gasification technology.Through analysis the gasification principles and theoretical calculation, we knowthe coal powder’s diameter and weight are the main influences of gasification result.The technology reformation directions of test bed make certain. The screw feeder’suniformity and stability are be concerned about. Through experimental validation, weknow several important conditions must be satisfied to reach the ideal performancewhen screw feeder used in micro-feeding. The mixing problems of the burner andgasification agent preheating are also being considered.The commissioning work follows with the modification of the test bed. The valueof the oxygen-coal ratio influences the gasification result. Through analyze the resultswe optimize the gasification condition and know the best oxygen-coal ratio is about0.93on this experiment’s condition.The slag experiment is taken place in the optimization condition. The slag in thegasification process is being collected. The slag’s appearance has many differentcharacters in different temperature and reaction process. There is lots of melted slagappear in the1200℃. The compact melted slags attach the surface when thetemperature higher than the melting point about100℃. The SEM and EDS are used toanalysis the microstructure of the slag, and compare the influence of differenttemperature and find the driving factor to the fusion mechanism. The different residencetime is also considered. And compare the similarities and differences reality salg withthe slag form in the fixed bed of reducing atmosphere. From the result, we know thatthe structures of melted slag in the drop tube furnace are determined by the fusionmechanism. But the structure of melted slag in the fixed bed are determined both by theprimal forms of the slag flake and the fusion mechanism.This may be because of the slag granules in bondage to eachother so the fusion mechanism only can influence theindividual granule or the adjacent granules.This thesis offers a way to analysis the slag’s melting mechanism in the drop tubefurnace. It’s also can anlysis the melting process and speculate the slag tendency ofevery specifically coal.