Research On Gasification Characteristics Of Pyrolyzed Low-rank Coal And Strengthening The Gasification Reaction In Fluidized Bed

Pyrolysis and gasification polygeneration based on coal pyrolysis is the future development trend of sub-quality coal utilization; it is possible to achieve efficient use of non-polluting. It includes coal pyrolysis and char gasification process. At present,there has been carried out a large number of studies for coal pyrolysis, but few research on char, and there are not a mature char gasification technology. Therefore,the study of char gasification behavior becomes particularily important. In this study,with Mongolia as raw material, we analyzed its basic properties and do fixed-bed experiment to know its properties and pyoperties behavior; char gasification behavior and its strengthening process were investigated in a fluidized bed. Here is the mainly research content and results:(1) we find Mongolia coal as a kind of non-coking coal with high volatile content,which is suitable for doing pyrolysis experiments in a fixed bed. In the pyrolysis experiments, higher oil yield and better quality of oil can be realized. The effective component in the pyrolysis gas is high; when the content of CO and CO2 reach to30 vol. %, Pyrolysis gas contains more H2 and CH4.(2) With the increase of ER, the yield of CO and CO2 increased, after reaching 0.31,the yield of CO began to fall, the yield of CO2 increase rapidly. In the whole process,the yield of H2 kept declining, the yield of CH4 remained at a low level. The highest carbon conversion rate is only 47.1%.With the increasing of gasification temperature,the gas production rate of each component has increased, but not obviously. Moreover,this coal would be easily sintered at high temperature. With the increase of residence time, the yield of effective components is increased, and the carbon conversion rate is increased, but the gradient becomes smaller. The degree of graphitization will deepen.(3) With the concentration of oxygen increasing, the internal diffusion can be strengthened, the yield of CO and CO2 increased, the yield of H2 are significantly reduced, the carbon conversion rate increased from 59.2% to 81.4%; Increasing the amount of water vapor, the yield of H2 increased nearly three-fold, the yield of CO and CO2 were firstly increased and then decreased, but not obviously. Addition of the catalyst can significantly improve the yield of gas in each component; the yield of H2 is particularly evident. But too much catalyst will reduced the gasificationefficiency, and the carbon conversion will decline. XRD analysis of semi-coke further confirms catalytic effect of shale ash.