基于TG-FTIR的造纸污泥热转化特性研究

Thermal Conversion of Paper Mill Sludge Based on TG-FTIR

目前对有机工业污泥在不同热转化过程中的反应特性和产物性质缺少系统对比研究.利用热重和红外光谱联用方法(TG-FTIR)对高挥发分造纸污泥在不同热转化过程中的反应特性进行了研究.氮气、空气和CO_(2)气氛分别对应热解、燃烧和气化反应.3种热转化过程在400℃前的热失重和反应特性相似,主要为水分和挥发分析出的热分解反应.500℃以上高温段反应主要为热分解反应生成焦炭的进一步反应,但3种热转化过程的反应特性差异明显.气化和燃烧反应都有较大失重峰,焦炭与CO_(2)气化反应发生在700℃以上,焦炭的燃烧反应在450~750℃之间完成,而此阶段热解反应速度则较慢、失重率较小.热转化过程中反应产物的红外谱图表明,污泥热转化产物中包含C—O、C—C、C=O、O—H、C—H、N—H等多种吸收峰,其中热解产物官能团尤其多且复杂.气化反应生成CH_(4)、CO_(2)、CO、NH3等主要气相产物,固体残余率也较低,适用于高挥发分有机污泥的处理.

There is a lack of systematic comparative study on the reaction characteristics and product properties of organic industrial sludge in different thermal conversion processes.The thermo-chemical conversion mechanism of paper mill sludge under different atmospheres was studied by the TG-FTIR method.Different atmospheres of N2,air and CO_(2) corresponded to pyrolysis,combustion and gasification,respectively.In the three thermal conversion processes,the behaviors of weight loss and thermal reaction at low temperature(<400℃)were similar,which were mainly water evaporation,volatile release and the generation of pyrolysis char.In the high temperature range(>500℃),the reaction was the further conversion of pyrolysis char,and significant difference in reaction characteristics were shown for the three processes.Gasification reaction between CO_(2) and char happened with a big weight loss when temperature was higher than 700℃.Char combustion happened between 450℃and 750℃,with a significant weight loss as well.However,the reaction rate and weight loss of pyrolysis were relatively low.The FTIR spectrum showed that there were many absorption peaks in reaction products,such as C—O,C—C,C=O,O—H,C—H,and N—H.There were more complex functional groups in pyrolysis products.CH_(4),CO_(2),CO and NH3 were the main components in gasification syngas.Gasification was considered to be more suitable for the thermal treatment of paper mill sludge with high volatile.