化工学报 ›› 2018, Vol. 69 ›› Issue (6): 2714-2721.DOI: 10.11949/j.issn.0438-1157.20171460

• 能源和环境工程 • 上一篇    下一篇

富氧燃烧下水蒸气对矿物捕集铬的影响

李箫玉1, 董卉1, 赵小平1, 陈娟1, 路春美1, 姚洪2   

  1. 1. 山东大学能源与动力工程学院, 山东 济南 250061;
    2. 华中科技大学煤燃烧国家重点实验室, 湖北 武汉 430074
  • 收稿日期:2017-11-02 修回日期:2018-01-15 出版日期:2018-06-05 发布日期:2018-06-05
  • 通讯作者: 陈娟
  • 基金资助:

    国家自然科学基金项目(51406062,51776112);国家国际科技合作专项(2015DFA60410);山东大学基本科研业务费专项资金(2016TB001)。

Influence of steam on chromium retention by minerals under oxy-fuel combustion

LI Xiaoyu1, DONG Hui1, ZHAO Xiaoping1, CHEN Juan1, LU Chunmei1, YAO Hong2   

  1. 1. School of Energy and Power Engineering, Shandong University, Jinan 250061, Shandong, China;
    2. State Key Laboratory of Coal Combustion, Huazhong University of Science & Technology, Wuhan 430074, Hubei, China
  • Received:2017-11-02 Revised:2018-01-15 Online:2018-06-05 Published:2018-06-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51406062, 51776112), the International Science & Technology Cooperation Program of China (2015DFA60410) and the Fundamental Research Funds of Shandong University (2016TB001).

摘要:

通过沉降炉煤燃烧实验及动力学模拟研究了水蒸气对Cr转化行为的作用及水蒸气对矿物吸附剂捕集Cr的影响。研究表明,CaO及Fe2O3在空气及富氧燃烧下均能较好地捕获Cr蒸气,石灰石的作用远差于CaO及Fe2O3,高岭土无论空气还是富氧燃烧下对捕集Cr均无效果。动力学模拟表明H2O促进Cr(Ⅲ)快速转化为高价Cr蒸气CrO(OH)2、CrO2(OH)及CrO2(OH)2。富氧燃烧下H2O抑制了CaO与Cr的反应,但燃烧灰中六价铬化合物大量增加,特别是当H2O与CaO同时存在时,灰中43%的铬为六价铬。水蒸气促进了Fe2O3捕集铬化合物使其固定在灰中。富氧燃烧下水蒸气促进Cr在煤灰中富集,随着H2O浓度由8%升高至20%,灰中铬的富集率又下降,主要由于水蒸气对CaO捕集Cr的抑制作用。

关键词: 铬, 吸附剂, 水蒸气, 煤燃烧, 动力学

Abstract:

Coal combustion experiments and kinetic simulations were conducted to investigate the effect of H2O on chromium behaviors and the influence of H2O on the ability of absorbents in terms of capturing chromium vapors. It was found that, both in air and oxy-fuel combustion, CaO and Fe2O3 showed high reactivity with chromium vapor. Limestone exhibited lower Cr solidification effect compared to CaO and Fe2O3. Kaolin had little effect on Cr retention in solid ash both in air and oxy-fuel combustion. H2O promoted the oxidation of trivalent Cr(Ⅲ) to high valance Cr vapors such as CrO(OH)2, CrO2(OH) and CrO2(OH)2 in a short second time scale. The capability of Fe2O3 was enhanced, while the capability of CaO was inhibited by steam on capturing Cr during oxy-fuel combustion. CaO, particularly in the coexistence of H2O, remarkably enhanced the formation of toxic Cr(VI) in solid ash, up to 43% of the total Cr. The presence of H2O in flue gas promoted the retention of Cr in solid ash, which decreased again with the increase of H2O from 8% to 20% during oxy-fuel combustion, attributing to the inhibition of CaO by steam in terms of capturing Cr vapors.

Key words: chromium, adsorbents, steam, coal combustion, kinetics

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