生物质热解、加氢热解及其与煤共热解的热重研究

STUDY ON PYROLYSIS AND HYDROPYROLYSIS OF BIOMASS AND COPYROLYSIS BETWEEN BIOMASS AND COAL

在加压热天平上用非等温热重法进行生物质（锯末、稻壳）在Ｎ２气氛下的热解和加氢热解研究。考察了升温速率（５～２５℃／ｍｉｎ）和压力（０．１～７ＭＰａ）的影响，求取了热解动力学参数，并研究了生物质与煤在常压Ｎ２气下的共热解过程。研究结果表明：生物质在４００℃左右即完成热解反应，总失重率大于７０％（Ｗ％，ｄａｆ．），热解时仅一个峰位于３００℃左右；与煤热解行为相同，随升温速率及压力的升高，转化率下降，ＤＴＧ峰移向高温，但由于热解反应在较低温度下进行，氧气的存在对生物质热解ＴＧ和ＤＴＧ的影响远小于煤热解。证明生物质热解以其内部氢对自由基的饱和及分子重排反应为主。生物质热解可用一级反应动力学处理，主要热解阶段及表现活化能分别为：锯末，２６７～３１４℃，６９．６６ｋＪ／ｍｏｌ；稻壳，２８３～３１０℃，５３．４５ｋＪ／ｍｏｌ；生物质由于与煤的热分解温度相差很大，因而在其共热解过程中无协同作用。

Pyrolysis and hydropyrolysis of biomass (sawdust and rice husk) have been investigated by non-isothermal thermogravimetry in a pressurized thermobalance,The effect of heating rate(5-25k/min)and pressures(0.1-7MPa) were analyzed and the kinetic parameters were also obtained.In addition,the copyrolysis between biomass and coal in N_2 atmosphere was studied.The results show that the pyrolytic reaction of biomass is complete at about 400℃ with conversion greater than 70%(wt.%,daf) and only one peak in DTG curve is observed at 300 ℃.With increasing heating rate and pressure,the conversion decreases and the peak in DTG curve moves toward high temperature; However,the effect of hydrogen on the pyrolysis of biomass is much less than coal because the pyrloytic reaction of biomass is carried out in relative low temperature.This suggests that the pyrolytic reaction of biomass is mainly due to the saturation of intrinsic hydrogen with the free radicals and the rearrangement of molecules.The kinetic analysis in pyrolysis of biomass can be handled with the first order reaction.The temperature range of pyrolysis and apparent activation energy are 267-314℃, 69.66kJ/mol for sawdust and 283.310℃,53.54kJ/mol for rice husk respectively.