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The Experimental Study Of Coal Pyrolysis Kinetics And Pyrolysis Mechanism

Posted on:2003-12-13Degree:MasterType:Thesis
Country:ChinaCandidate:S Y SongFull Text:PDF
GTID:2121360092496893Subject:Mineral prospecting and exploration
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In this paper, the kinetics of coal pyrolysis has been investigated on 7 kinds of different rank coals by non-isothermal thermogravimetric method. The effect of particle size, heating rate, coal rank on coal pyrolysis has been analyzed. Coal rank and the data of coal ultimate analysis have something to do with coal pyrolysis. But there is no regular relation. So it is indicated that the coal pyrolysis is very complicated, the whole pyrolysis process can not be described by one step reaction. Based on this, the author puts forward two step reaction model i. e. two dimensional diffusion model and chemical reaction model. The regress analysis on the most loss weight temperature and activation energy with Vdaf, Cdaf, the atom ratio of 0 to C, the atom ratio of H to C, ash has been discussed. The author found that the most loss weight temperature increases with the carbon content of coal, the activation energy reaches the maximum value about the 85% carbon content of coal. In addition the compensation effect has been found between the activation energy and pre-exponential factors, the compensation effect in the kinetics parameter of different particle size coal pyrolysis follows the linear rule.The enthalpy and entropy that has come into being in the process of pyrolysis decide the compensation effect. The coal structure has been studied by pyrolysis-XRD, the crystallite structural parameter has been attained. At last characteristic of evolved gas in the pyrolysis process has been investigated by py-ft.ir, it has been found that constitute and structure of coal decide the constitue of evolved gas, the release of pyrolysis gas has been dependent on the pyrolysis temperature, the coal rankand the constitute of coal. According to the kinetics analysis of coalpyrolysis, py-XRD analysis and py-FT. IR analysis, the author discusses the mechanism of coal pyrolysis and the chemical reaction of coal pyrolysis.
Keywords/Search Tags:non-isothermal thermogravimetric analysis, the kineticsparameter of coal pyrolysis, two step reaction model, the compensation effect, pyrolysis x-ray diffraction analysis, the crystallite structural parameter, py-FT. IR, the mechanism of coal pyrolysis
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