富氧燃烧下水蒸气对矿物捕集铬的影响  

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

作　　者：李箫玉 董卉 赵小平 陈娟[1] 路春美[1] 姚洪[2] LI Xiaoyu1, DONG Hui1, ZHAO Xiaoping1, CHEN Juan1, LU Chunmei1, YAO Hong2(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, Chin)

机构地区：[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

出　　处：《化工学报》2018年第6期2714-2721,共8页CIESC Journal

基　　金：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)~~

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Fe_2O_3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Fe_2O_3,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H_2O促进Cr(III)快速转化为高价Cr蒸气Cr O(OH)2、CrO_2(OH)及CrO_2(OH)2。富氧燃烧下H_2O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H_2O与CaO同时存在时,灰中43%的铬为六价铬。水蒸气促进了Fe_2O_3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H_2O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。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 Cr O（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.

关 键 词：铬 吸附剂 水蒸气 煤燃烧 动力学 

分 类 号：TK16[动力工程及工程热物理—热能工程]