Kinetics Of Coal Gasification At High Temperature And Modeling Of Two-stage Entrained Flow Coal Gasifier

Coal gasification is a key issue of Clean Coal Technology. Non-slaggingand slagging two-stage coal gasification is a promising technology withindependent intelligent right. Model study is one of the effective methods forresearchers on coal gasification, and investigation on the kinetics of coalgasification at high temperature is the foundation of modeling.Using thermogravimetric analysis (TGA), the gasification kinetics of 7kind coals at high temperature were studied under programmed temperaturecondition. Kinetic parameters of these coals while reacting with O₂ and CO₂were obtained after processing data gained from TGA with Coats-Redfernmethod. The TG curve showed that the reaction between coal and O₂ waseasier than that between coal and CO₂, and the reaction rate was faster and thereaction time was shorter. The kinetic characteristic of coal gasification wasclosely linked to the coal chemical composition. The activation energydecreased linearly as the volatile content and the ratio of hydrogen to carbonincreased.A kinetic model of two-stage coal gasifier was established base on theanalysis of the flow, combustion and gasification in the gasifier. This modelreflected the reaction process in the gasifier and considered the influence ofgeometrical structure on the gasification.A series of calculations for 3 kinds two-stage gasifiers with differentstructure were carried out and the distribution of temperature, composition ofsyngas and carbon conversion along the height of the gasifiers are obtained.The effects of different operating parameters on the performance of thetwo-stage gasifiers were predicted. The operating parameters included themass ratio of oxygen to coal, the concentration of coal water slurry, the ratio ofthe secondary oxygen and the position where it was fed in.