化工学报 ›› 2018, Vol. 69 ›› Issue (9): 3859-3868.doi: 10.11949/j.issn.0438-1157.20180450

• 催化、动力学与反应器 • 上一篇    下一篇

H2O和SO2对CFB内石灰石同时煅烧/硫化反应中煅烧动力学的协同作用

陈亮, 赵帆, 闫广精, 王春波   

  1. 华北电力大学能源动力与机械工程学院, 河北 保定 071003
  • 收稿日期:2018-04-26 修回日期:2018-06-11
  • 通讯作者: 陈亮 E-mail:c211205@163.com
  • 基金资助:

    国家重点研发计划项目(2016YFB0600701);中央高校基本科研业务费重大项目(2018ZD03)。

Synergetic effect of H2O and SO2 on calcination kinetics of limestone during simultaneous calcination/sulfation reaction in CFB boilers

CHEN Liang, ZHAO Fan, YAN Guangjing, WANG Chunbo   

  1. School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, Hebei, China
  • Received:2018-04-26 Revised:2018-06-11
  • Supported by:

    supported by the National Key R&D Program of China (2016YFB0600701) and the Fundamental Research Funds for the Central Universities (2018ZD03).

摘要:

采用自制恒温热重分析仪,研究了CFB工况下石灰石同时煅烧/硫化反应中H2O和SO2对石灰石煅烧动力学和孔结构的协同作用。煅烧环境中的H2O能够促进石灰石的分解,但SO2会减慢石灰石分解速度,且测试发现SO2使煅烧后颗粒的孔容积下降,分解反应的效率因子减小。基于此提出SO2减缓煅烧反应的机理:高温下,石灰石颗粒外层首先分解并生成多孔CaO层,其中的孔隙作为内部CaCO3分解产生CO2的外扩散通道,当煅烧气氛中含有SO2时,颗粒的CaO层与SO2反应生成CaSO4,堵塞了CaO中的孔隙,增加了CO2扩散的阻力,从而减缓了其分解速度。当石灰石在含有15% H2O和0.3% SO2的环境中分解时,其分解速度比不含二者的环境下快,而比含15% H2O但不含SO2的环境下慢,说明H2O和SO2对改变石灰石分解的速度有协同效应,但15% H2O的作用比0.3% SO2的作用更大。对效率因子的计算表明,该现象可能由于石灰石煅烧反应的速度控制步骤中本征反应速度的影响比扩散阻力的作用更大,而H2O能够直接加速煅烧反应的本征速度。温度、粒径等均能够影响石灰石同时煅烧/硫化反应的中的煅烧速度。H2O还能够促进CaO的烧结,并且H2O和SO2在降低石灰石煅烧产物的孔面积和孔容积上具有叠加效应。

关键词: 吸附剂, 动力学, 循环流化床, 石灰石, 煅烧, 硫化, 孔结构, H2O

Abstract:

The simultaneous calcination/sulfation reaction is the real reaction process of limestone in circulating fluidized bed (CFB) boiler. To obtain the true calcination process of limestone in CFB, the combined effect of H2O and SO2 on the calcination kinetics and pore structure of limestone during simultaneous calcination/sulfation reaction under CFB conditions was studied in a constant-temperature reactor. H2O (0-15%) can accelerate the calcination of CaCO3. The SO2 in flue gas decreased the calcination rate of limestone particles. This phenomenon was explained by a mechanism based on the measurement of pore structure, namely that SO2 reacted with CaO layer, and the formed CaSO4 would fill or block the pore in CaO layer, decrease the pore volume, increase the diffusion resistance of CO2, and consequently impede the calcination reaction. H2O and SO2 can work synergistically on changing the calcination rate,and an increase of the calcination rate was found under 15% H2O and 0.3% SO2 compared to that without either. This may be because intrinsic reaction played a major role in the rate controlling step of calcination, and H2O accelerated the intrinsic calcination directly. The effect of other factors like temperature and particle size on the calcination rate in the presence of H2O and SO2 were also tested. H2O also accelerated the sintering of CaO significantly, and along with SO2, the pore volume and surface area of CaO decreased further.

Key words: sorbents, kinetics, circulating fluidized bed, limestone, calcination, sulfation, pore structure, H2O

中图分类号: 

  • TK221

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