稻壳和稻草的热重-质谱分析及其反应动力学

采用热重-质谱(TG-MS)联用对比研究了氮气气氛中稻壳和稻草在升温速率分别为5,20℃/min时的热解行为,分析得到了稻壳和稻草热裂解过程产生的小分子气相产物(CO,CO_2,CH_4,H_2)随温度和升温速率变化的释放规律.结果表明:稻壳和稻草的热解过程可分为脱水干燥预热解阶段、挥发分析出快速热解阶段和残余物裂解炭化阶段;稻草热解总失重率约为75%,稻壳约为55%,而且稻草的热解特性指数高于稻壳;稻草热解释放生物质燃气主要成分(CO,CH_4,H_2)的离子流强度明显高于稻壳;用Coats-Redfern法计算生物质的热解动力学参数,表观活化能和挥发分初始析出温度均是稻草稻壳,这与实验结果吻合,表明相同条件下稻草的热解性能优于稻壳.

Thermogravimetric-Mass Spectrometry Analysis and Pyrolysis Kinetic of Rice Husk and Rice Straw

In the nitrogen atmosphere， thermogravimetry-mass spectrometry(TG/MS) was used in combination to compare the pyrolysis behavior of rice husk and rice straw at the heating rates of 5℃/min and 20℃/min， and the release rule of small molecule gas (CO，CO₂，CH₄，H₂) product with the change of temperature and heating rates was obtained. The results show that the pyrolysis process of rice husk and rice straw can be divided into dewatering and drying warm-up solution stage， volatile component precipitation fast pyrolysis stage and residue pyrolysis carbonization stage. The total weight loss rate of rice straw pyrolysis is about 75%， while rice husk is about 55%， and the index value of rice straw pyrolysis characteristics is higher than that of rice husk. The release intensity of ion current of main biomass gas composition (CO， CH₄ and H₂) in the rice straw pyrolysis process is obviously higher than that of rice husk. The pyrolysis kinetic parameters were calculated by using Coats-Redfern method. The apparent activation energy and volatile component initial precipitation temperature of rice straw are lower than those of rice husk， which accord with the results of experiment， and indicate that the pyrolysis performance of rice straw is better than that of rice husk under uniform conditions.