CIESC Journal ›› 2019, Vol. 70 ›› Issue (8): 3142-3150.DOI: 10.11949/0438-1157.20190234

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Pyrolysis and combustion characteristics and kinetics of torrefied traditional Chinese medicine waste

Shanzhi XIN1(),Fang HUANG1,Xiaoye LIU1,Qingli XU2,Tie MI1()   

  1. 1. Hubei Key Laboratory of Industrial Fume and Dust Pollution Control, Jianghan University, Wuhan 430056, Hubei, China
    2. School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2019-03-12 Revised:2019-05-17 Online:2019-08-05 Published:2019-08-05
  • Contact: Tie MI

烘焙中药渣的热解与燃烧特性及其动力学分析

辛善志1(),黄芳1,刘晓烨1,许庆利2,米铁1()   

  1. 1. 江汉大学工业烟尘污染控制湖北省重点实验室,湖北 武汉430056
    2. 华东理工大学资源与环境工程学院,上海200237
  • 通讯作者: 米铁
  • 作者简介:辛善志(1984—),男,博士,讲师,<email>szxin@jhun.edu.cn</email>
  • 基金资助:
    湖北省自然科学基金项目(2017CFB370);江汉大学工业烟尘实验室项目(HBIK2018-02)

Abstract:

After the torrefied traditional Chinese medicine waste (TCMW) is baked, it is a solid fuel with potential application. However, little is known about the thermal decomposition of torrefied TCMW. In this study, the effects of torrefaction on the pyrolysis and combustion characteristics of torrefied TCMW were investigated and the kinetic parameters were evaluated. The indexes of combustible, burnout characteristic and integrated combustion performance were also evaluated. It was found that the pyrolysis of torrefied TCMW can be divided into two distinct stages, which is governed by two different reaction mechanisms. The pyrolysis of torrefied TCMW was mainly concentrated between 250—500℃ with mass loss of 57%—65%. The two DTG peaks of the torrefied TCMW are superimposed by four peaks: 265.8℃, 318℃, 364.2℃ and 412.3℃. The first three peaks were due to the thermal decomposition of hemicellulose, cellulose and lignin, respectively. The decomposition of lignin and the carbonization of solid residues gave rise to the peak at 412.3℃. The apparent activation energy of the first stage is 76.1—94.0 kJ/mol, while that is 26.8—38.8 kJ/mol for the second stage. The torrefied TCMW was easy to ignite and burnout. The ignition temperature of torrefied TCMW is in the range of 280.3—294.8℃. In general, the torrefied TCMW in 10% O2 shows the best combustion performance. The combustion of torrefied TCMW can be divided into three stages. The first stage is mainly due to the release and combust of volatiles with the activation energy of 80.5—97.3 kJ/mol. However, the TCMW under CO2 and 10% O2 torrefaction has higher activation energy (99—97 kJ/mol). The second stage is attributed to the combustion of volatiles and residue char with the activation energy of 18.3—28.5 kJ/mol. The main reaction of the third stage reaction is the combustion of the char, and the activation energy is 41.8—50.6 kJ/mol. The results of this paper are helpful to understand the pyrolysis and combustion of torrefied TCMW under different conditions and develop an effective utilization process.

Key words: torrefied traditional Chinese medicine waste, waste treatment, pyrolysis, combustion characteristic, kinetics

摘要:

中药废渣经过烘焙后是一种具有应用潜力的固体燃料。采用热重分析仪对烘焙中药渣的热解及燃烧特性进行了研究,利用Kissinger-Akahira-Sunose (KAS)法及Coats-Redfern法对热解及燃烧的动力学进行求解,评估了烘焙中药渣的燃烧特性。研究发现烘焙中药渣的热分解分为2个阶段,第一阶段的活化能为76.1~94.0 kJ/mol,第二阶段的活化能为26.8~38.8 kJ/mol。烘焙中药渣的燃烧分为3段反应过程,第一阶段主要是挥发分的析出及燃烧,活化能为80.5~97.3 kJ/mol;第二阶段属于挥发分及部分焦炭的燃烧,活化能为18.3~28.5 kJ/mol;第三阶段的主要反应为残余焦炭的燃烧,活化能为41.8~50.6 kJ/mol。不同烘焙条件下制得的中药渣都较易着火燃烧,着火温度在280.3~294.8℃。经O2烘焙的中药渣前期可燃性以及综合燃烧特性最好,最易燃尽,表明燃烧烟气烘焙中药渣是可行的。

关键词: 烘焙中药渣, 废物处理, 热解, 燃烧特性, 动力学

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