CIESC Journal ›› 2022, Vol. 73 ›› Issue (1): 362-375.DOI: 10.11949/0438-1157.20211244

• Energy and environmental engineering • Previous Articles     Next Articles

Comparison of reaction characteristics and kinetics between tar thermal cracking and steam reforming in a micro fluidized bed reaction analyzer

Peng WU1,3(),Fang WANG2,3(),Xi ZENG2,3,Hongren ZHAN1,Junrong YUE3,Tingting WANG3,Guangwen XU1,3   

  1. 1.School of Mechanical and Power Engineering, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China
    2.School of Ecology and Environment, Beijing Technology and Business University, Beijing 100048, China
    3.State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-08-27 Revised:2021-10-19 Online:2022-01-18 Published:2022-01-05
  • Contact: Fang WANG

微型流化床中焦油热裂解和水蒸气重整的反应特性及动力学对比

武鹏1,3(),王芳2,3(),曾玺2,3,战洪仁1,岳君容3,王婷婷3,许光文1,3   

  1. 1.沈阳化工大学机械与动力工程学院,辽宁 沈阳 110142
    2.北京工商大学生态环境学院,北京 100048
    3.中国科学院过程工程研究所多相复杂系统国家重点实验室,北京 100190
  • 通讯作者: 王芳
  • 作者简介:武鹏(1995—),男,硕士研究生,peng_w123@163.com
  • 基金资助:
    国家重点研发计划项目(2018YFF01011400);国家自然科学基金项目(21808227)

Abstract:

In this study, a micro fluidized bed reaction analyzer (MFBRA) was used to examine the reaction characteristics of tar steam reforming and thermal cracking in the temperature range of 750—950℃ and steam partial pressure (SP) of 10%—30%. The production of gaseous products and the conversion of total carbon in the gaseous products and the conversion of tar were completely analyzed. The reaction kinetics was also calculated. The results show that during tar thermal cracking, with the increase of reaction temperature, the yields of H2, CH4, CO and CO2 and the conversion of total carbon in the gaseous products increased, and the reaction time decreased. However, in the process of tar steam reforming, by raising the reaction temperature, the reaction time was prolonged largely, and the yields of H2, CH4, CO and the conversion of total carbon in the gaseous products increased significantly, while that of CO2 reached the maximum value at 850℃. During this process, it included not only tar thermal cracking but also the reforming reaction between tar components and the reaction intermediates. At 950℃ and SP of 30%, the conversion of total carbon in the gaseous products reached 92.34%. For the tar steam reforming, with the increase of SP, although the yields of gas components and the conversion of total carbon in the gaseous products increased, the corresponding reaction rate decreased. At the same reaction temperature, with the increase of SP, the generation rates of CO, CH4 and the rate of total carbon conversion in the gaseous products increased, the H2 reaction rate gradually decreased with a long stable zone, while the CO2 reaction rate reached its maximum value at 850℃. The activation energy (Ea) of the gaseous products (H2, CO, CO2 and CH4), the conversion of total carbon in the gaseous products and the tar conversion were 90.10, 42.01, 58.56, 64.92, 61.44 and 63.26 kJ/mol, respectively. The corresponding values were obviously less than that of tar thermal cracking. It indicated the promotion effect of steam on tar conversion. Finally, the tar thermal cracking kinetics data was compared with the literature data to verify the feasibility of the MFBRA tar steam reforming reaction test and the accuracy of the analysis results.

Key words: biomass, tar, thermal cracking, steam reforming, micro fluidized bed

摘要:

采用微型流化床反应分析仪(MFBRA)考察了不同温度(T,750~950℃)和水蒸气分压(SP,10%~30%)下生物质焦油水蒸气重整过程中的气体生成、气体产物中总碳转化和焦油转化等反应特性,求算反应动力学,并与焦油热裂解特性进行比较。在热裂解过程中,随温度增加,各气体(H2、CH4、CO、CO2)产率和气体产物中的总碳转化率增加,反应时间缩短。而在焦油水蒸气重整过程中,等温下的反应时间明显延长,且H2、CH4、CO产率和气体产物中的总碳转化率显著提升,而CO2产率在850℃时有最大值。在焦油水蒸气重整过程中,不仅有焦油裂解,还有裂解产物与水蒸气的反应,促进碳转化。在950℃、SP=30%条件下,气体产物中的总碳转化率达到92.34%。水蒸气作用下,气体组分的产率和气体产物中的总碳转化率增加,而等温条件下的反应速率下降。水蒸气分压对各气体组分的影响具有差异性。随分压增加,CO、CH4的生成速率和气体产物中的总碳转化的反应速率增加;H2生成速率逐渐下降,速率稳定段扩大;CO2生成速率在850℃时有最大值。采用均相模型求取焦油水蒸气重整反应过程中的活化能,气体产物的生成活化能(H2、CO、CO2和CH4)、气体产物中的总碳转化及焦油转化的活化能明显偏低,分别为90.10、42.01、58.56、64.92、61.44和63.26 kJ/mol,对应数值明显小于焦油热裂解,说明水蒸气对焦油重整反应的促进作用。最后,将焦油热裂解动力学数据与文献数据对比,验证了MFBRA对焦油水蒸气重整反应测试的可行性和分析结果的准确性。

关键词: 生物质, 焦油, 热裂解, 水蒸气重整, 微型流化床

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