Transformation of Organically Bound Chromium during Oxy-coal Combustion: the Influence of Steam and Mineralv
Transformation of Organically Bound Chromium during Oxy-coal Combustion: the Influence of Steam and Mineralv
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富氧煤燃烧过程中有机结合铬的转化：蒸汽和矿物的影响
DOI：
10.1021/acs.energyfuels.7b03123
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发表时间：
--
期刊：
影响因子：
5.3
通讯作者：
Hong Yao
中科院分区：
文献类型：
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作者：
Xiaoyu Li;Hui Dong;Juan Chen;Chunmei Lu;Guangqian Luo;Hong Yao
在1273K的落管式炉中研究了水蒸气和矿物质对富氧煤燃烧过程中Cr转变的影响。另外，还向烟气中添加了500 ppmv HCl和1000 ppmv SO2，以研究H2O、HCl和SO2对富氧煤燃烧过程中烟气中杂质再循环时Cr行为的竞争。结果表明，CaO和Fe_2O_3对燃烧过程中含铬蒸气的捕集能力优于石灰石和高岭土。改空气为富氧煤燃烧明显削弱了CaO的作用，但促进了Fe2O3与Cr蒸气的反应。烟气中H2O的存在促进了三价Cr（III）在短的秒级时间尺度内氧化成高价Cr蒸气。CaO，特别是在煤燃烧过程中的H2O共存，显着提高了有毒的Cr（VI）在固体灰中的分数。H2O影响矿物与Cr的反应行为。富氧煤燃烧过程中，水蒸气对CaO与Cr的反应有抑制作用，对Fe2O3有促进作用。富氧煤燃烧过程中，随着H_2O含量从5%增加到20%，Cr在灰中的保留率降低。HCl通过氯化反应显著促进Cr的释放。当H2O与HCl共存时，H2O的存在抵消了HCl对铬回收率的负面影响。SO2通过硫酸化反应生成Cr2（SO4）3凝聚成固体灰，有利于Cr的保留。此外，还发现在燃烧过程中，Cr蒸气更倾向于与HCl反应而不是与SO2反应。
The influence of steam and minerals on Cr transformation during oxy-coal combustion has been examined in a drop tube furnace at 1273 K. An extra 500 ppmv HCl and 1000 ppmv SO2were also added to flue gas to examine the competition of H2O, HCl, and SO2on Cr behaviors during oxy-coal combustion upon the recirculation of impurities in flue gas. It was found that CaO and Fe2O3exhibited high capability on capturing Cr-bearing vapors during combustion compared to limestone and kaolin. Changing air to oxy-coal combustion obviously weakened the role of CaO, whereas it promoted reaction between Fe2O3and Cr vapors. The existence of H2O in flue gas facilitated the oxidation of trivalent Cr(III) to high valence Cr vapors in a short second time scale. CaO, particularly in the coexistence of H2O during coal combustion, remarkably enhanced the toxic Cr(VI) fraction in solid ash. H2O affected the behavior of minerals reacted with Cr. CaO was inhibited and Fe2O3was enhanced by steam to react with Cr during oxy-coal combustion. The retention of Cr in ash reduced with a H2O increase from 5% to 20% during oxy-coal combustion. HCl significantly promoted the release of Cr through chlorination reaction. The presence of H2O offset the negative effect of HCl on Cr recovery when H2O was coexistent with HCl in flue gas. SO2favored the retention of Cr via sulfation reaction to form Cr2(SO4)3condensed into solid ash. Moreover, it was found that Cr vapors preferred to react with HCl than SO2during combustion.