化工进展 ›› 2023, Vol. 42 ›› Issue (S1): 498-509.DOI: 10.16085/j.issn.1000-6613.2023-0325

• 资源与环境化工 • 上一篇    下一篇

HBr改性飞灰对Hg0的动态吸附及动力学模型

顾永正1(), 张永生2   

  1. 1.国电电力发展股份有限公司,北京 100101
    2.华北电力大学能源动力与机械工程学院,北京 102206
  • 收稿日期:2023-03-03 修回日期:2023-05-10 出版日期:2023-10-25 发布日期:2023-11-30
  • 通讯作者: 顾永正
  • 作者简介:顾永正(1991—),男,博士,高级工程师,研究方向为清洁低碳发电技术研究及工程实践。E-mail:yongzheng.gu@chnenergy.com.cn
  • 基金资助:
    中国科协青年人才托举工程资助项目(2021QNRC001);国家能源集团科技创新项目(GJNY-19-56)

Dynamic behavior and kinetic model of Hg0 adsorption by HBr-modified fly ash

GU Yongzheng1(), ZHANG Yongsheng2   

  1. 1.GD Power Development Co. , Ltd. , Beijing 100101, China
    2.North China Electric Power University, School of Energy, Power and Mechanical Engineering, Beijing 102206, China
  • Received:2023-03-03 Revised:2023-05-10 Online:2023-10-25 Published:2023-11-30
  • Contact: GU Yongzheng

摘要:

为清晰描述HBr改性飞灰(HBr-FA)对Hg0吸附的全过程,基于固定床动态吸附实验,在同时考虑扩散和表面吸附氧化的条件下,建立了固定床中HBr-FA对Hg0的吸附动力学模型,讨论了Hg0吸附氧化过程的关键影响因素,探究了Hg0在扩散区域和表面活性位上的动力学行为。结果表明:该模型综合考虑了轴向返混、内外扩散和本征动力学过程,能够较好地拟合实验穿透曲线,并可求得相应的动力学参数,对气膜扩散系数更加敏感;初始Hg0浓度的提高可提供更高的能量克服扩散阻力,适当提高流量和床层厚度可减小外扩散阻力,进而表现出更优越的表观吸附氧化效果;该模型还可得到床层内和颗粒内(扩散和动力学区域)的Hg0浓度分布,发现在吸附初期,外扩散阻力对改性飞灰吸附氧化Hg0的过程影响更大。

关键词: HBr改性飞灰, 汞, 吸附氧化, 动力学, 外扩散, 固定床

Abstract:

In order to clearly describe the whole process of Hg0 adsorption by HBr-modified fly ash (HBr-FA), an adsorption kinetic model was established including diffusion and surface adsorption and oxidation based on the dynamic adsorption experiment on a fixed-bed column. The key influence factor of the adsorption and oxidation process of Hg0 was discussed, and the dynamic behavior of Hg0 in the diffusion region and surface active site was investigated. The model takes into account the processes of axial backmixing, internal and external diffusion, and intrinsic kinetics, which hence can fit well with the experimental breakthrough results with the corresponding kinetic parameters. The sensitivity analyses indicate that axial dispersion, gas film diffusion, and inner efficiency diffusion have dominant impacts on Hg0 adsorption, and the model is more sensitive to the gas film diffusivity. Furthermore, the increasing of initial Hg0 concentration is beneficial to decreasing the diffusion resistance and promoting the Hg0 adsorption-oxidation due to the improvement of mass transfer driving force. The external diffusion resistance can be reduced with the increase of inlet flow rate and bed thickness. In addition, the Hg0 concentration profiles inside the particle can be obtained from the model, which shows the external diffusion resistance has greater influence at the initial stage of Hg0 adsorption and oxidation by HBr-FA.

Key words: HBr-modified fly ash, mercury, adsorption and oxidation, kinetics, external diffusion, fixed-bed

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