基于热重分析的油菜秸秆热解特性研究

Study on the pyrolysis characteristics of rape straw based on TG analysis

采用热重及热重红外光谱联用技术(TG-FTIR)研究油菜秸秆在不同升温速率和粒径状态下的热解特性。结果表明:升温速率越高,油菜秸秆热解起始温度及失重峰所在温度越高;样品的粒径越小越有利于热解反应;使用电镜观察,热解前后秸秆内外层有明显变化,热解后的物料表面会出现大量褶皱和晶体状颗粒物质;热解分阶段进行,在20℃/min的升温速率下,FTIR检测出的主要热解气态产物为H2O、CH4、CO2、CO和部分气化状态的羰基类化合物、芳香族类化合物、胺类化合物。

The paper is aimed at presenting the pyrolysis and pyrolysis products＇ producing characteristics of rape straw by using the method of TG and TG-FTIR with specified heating rates and particle sizes. The results show that the higher the heating rate was, the higher the starting pyrolysis temperature and the weight loss temperatures were, and the smaller the particle size was, the more beneficial to pyrolysis process it was. At the heating rate of 20 ℃/min, with the hating temperature rising to 245.15 ℃, the material began to appear sharp reaction, and later on reached the maximum pyrolysis rate at 342.13 ℃, the maximum pyrolysis rate was 1.09%/℃. However, when the particle size reduced to 100 mesh, the maximum pyrolysis temperature reduced to 337.98 ℃, meanwhile the maximum pyrolysis rate kept on 1.087%/℃. So for the sake of promoting the pyrolysis of rape straw, the small size state is strongly recommended. And via observation of electron microscopy before and after the pyrolysis, there would be found obvious change on the inner and outer layer of rape straw, a large number of wrinkles and crystal particulate matters would appear on the surface of the materials after the pyrolyzing. Although the pyrolysis of rape straw has different stages, the time when gaseous products of epidermis and inner core came out was consistent. The only obvious difference was that the absorption curve of epidermis had only one absorption peak while the absorption curve of inner core had two. At heating rate of 20 ℃/min, the main gaseous products of epidermis and inner core during pyrolysis detected by the FTIR was H 2 O, CH 4 , CO 2 , CO and some carbonyl compounds, aromatic compounds, amine compounds in gasification state. Among these substances, CH 4 and CO are the main combustible gas generated by the straw gasification device, and aromatic compounds and amine compounds are widely used in chemical engineering and medicine.