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煤的加压气化是煤清洁利用的关键,作为气化反应的初始阶段,煤热解特性对煤气化过程有着重要的意义。为了深入了解煤的加压热解机制,该文采用加压热重分析仪研究了我国的一种典型烟煤——神府煤在不同压力下的热解失重特性,采用挥发分释放综合特性指数(D)与非等温法,结合不同的扩散机制函数分析了神府煤加压热解动力学机制。研究发现神府煤的热解主要包括煤样的干燥脱水、挥发分的析出以及大分子焦油的二次裂解;加压对神府煤的热解过程有明显的影响,热解压力小范围的升高(<0.8MPa)有利于挥发分的析出,然而过高的压力不利于挥发分的快速析出,挥发分释放综合特性指数可很好地表征神府煤加压热解过程中挥发分的析出特性。热动力学分析表明,三维球扩散模型比较适合神府煤的加压热解机制,低温段活化能随热解压力增大先增大后减小,但明显高于高温段热解活化能。
Pressurized gasification of coal is the key to clean utilization of coal. As the initial stage of gasification reaction, pyrolysis of coal has an important significance for coal gasification process. In order to further understand the mechanism of pressurized pyrolysis of coal, the pyrolysis weight loss characteristics of a typical bituminous coal-Shenfu coal under different pressures in China are studied by using a pressurized thermogravimetric analyzer. The volatile release characteristics index (D) and non-isothermal method, combined with different diffusion mechanism function analysis of Shenfu coal pyrolysis kinetic mechanism. It is found that the pyrolysis of Shenfu coal mainly includes the dehydration of coal sample, the precipitation of volatile matter and the secondary cracking of macromolecule tar. The pyrolysis has obvious influence on the pyrolysis process of Shenfu coal. The pyrolysis pressure is in a small range Elevated (<0.8MPa) is conducive to the precipitation of volatile components, however, the excessive pressure is not conducive to the rapid precipitation of volatile components. The integrated characteristic index of volatile matter release can well characterize the volatile components during the pressure pyrolysis of Shenfu coal Precipitation characteristics. Thermodynamic analysis shows that the three-dimensional spherical diffusion model is more suitable for the pressurized pyrolysis mechanism of Shenfu coal. The activation energy of low temperature increases firstly and then decreases with the increase of pyrolysis pressure, but it is obviously higher than pyrolysis activation energy of high temperature.