富氧燃烧气氛下酸性气体对磁性生物焦脱汞性能影响  

Mercury removal performance of magnetic biochar by acid gas during oxyfuel combustion atmosphere

作　　者：张军峰 魏书洲 孙道荣 周煜明 肖日宏 熊卓[3] 张军营[3] 赵永椿[3] ZHANG Junfeng;WEI Shuzhou;SUN Daorong;ZHOU Yuming;XIAO Rihong;XIONG Zhuo;ZHANG Junying;ZHAO Yongchun(National Energy Sanhe Power Generation Co.,Ltd.,Langfang 065201,China;Hebei Province Coal-fired Power Station Pollution Prevention and Control Technology Innovation Center,Langfang 065201,China;National Key Laboratory of Coal Combustion and Low Carbon Utilization,Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]国能三河发电有限责任公司,河北廊坊065201 [2]河北省燃煤电站污染防治技术创新中心,河北廊坊065201 [3]华中科技大学煤燃烧与低碳利用全国重点实验室,湖北武汉430074

出　　处：《洁净煤技术》2024年第10期198-206,共9页Clean Coal Technology

基　　金：国家自然科学基金资助项目(42030807)。

摘　　要：磁性生物焦已被证明是一种高效脱除单质汞(Hg^(0))的吸附剂。然而,SO_(2)、NO和HCl是富氧燃烧烟气中的酸性成分,其在磁性生物焦脱除Hg^(0)中的作用尚未确定。研究通过模拟富氧燃烧气氛实验装置,深入探讨了不同反应温度下酸性气体浓度对Hg^(0)吸附、氧化效率的影响,以及磁性生物焦的热再生循环性能。结果表明:120℃下,体积分数为0.4%的SO_(2)可促进磁性生物焦对Hg^(0)的吸附,脱汞率达93.5%,但较高体积分数SO_(2)(>0.4%)则产生抑制作用,且少量Hg^(0)被氧化,部分缓解SO_(2)对Hg^(0)的吸附抑制;同时,NO在富氧燃烧气氛中也表现出类似的规律;气态HCl是一种重要的促进剂,在体积分数为0.02%的HCl存在下脱汞率接近100%,可抵消烟气组分带来的不利影响。然而较高温度下,SO_(2)对磁性生物焦脱汞的作用规律与120℃时相似。350℃,体积分数为1.6%的SO_(2)对Hg^(0)吸附抑制作用更强,吸附效率只有19.5%,低于Hg^(0)氧化效率,主要生成更多的C=O等含氧官能团;NO在较高温度下也表现出较强的抑制作用,随着NO浓度增加脱汞率逐渐降低,最终降至50%左右。可见,高温、高浓度SO_(2)及NO不利于磁性生物焦脱汞。此外,脱汞后失活的磁性生物焦具有优异的热再生稳定性,在450℃下热再生并循环4次后仍有80%左右的脱汞效率。Magnetic biochar has been proven to be an efficient adsorbent for the removal of elemental mercury(Hg^(0)).However,SO_(2)、NO and HCl are acid components of the oxyfuel combustion flue gas,and their roles in magnetic biochar removal of Hg^(0)have not been determined.By simulating an experimental setup with oxyfuel combustion atmosphere,the effects of acidic gas concentration on the adsorption and oxidation efficiencies of Hg^(0)at different reaction temperatures,as well as the thermal regeneration cycling performance of magnetic biochar,were thoroughly investigated.The results showed that 0.4%SO_(2)promoted the adsorption of Hg^(0)by magnetic biochar with 93.5%Hg^(0)removal at 120°C,but higher concentrations of SO_(2)(>0.4%)produced an inhibitory effect and promoted the oxidation of a small amount of Hg^(0),which partially alleviated the inhibitory effect of SO_(2)on the adsorption of Hg^(0).Meanwhile,NO shows a similar pattern in oxyfuel combustion atmosphere.Gaseous HCl is an important accelerator,and the mercury removal rate in the presence of 0.02%HCl is close to 100%,which counteracts the adverse effects of flue gas components.However,the pattern of action of SO_(2)on Hg^(0)removal from magnetic biochar at high temperatures was similar to that at 120℃.At 350℃,1.6%SO_(2)inhibited Hg^(0)adsorption even more,with an adsorption efficiency of only 19.5%,which was lower than the efficiency of Hg^(0)oxidation,and mainly generated more oxygen-containing functional groups such as C=O;NO also showed strong inhibition at high temperatures,and the rate of mercury removal gradually decreased with increasing NO concentration,with the lowest rate dropping to about 50%.It can be seen that high temperature and high concentration of SO_(2)and NO are unfavorable for magnetic biochar mercury removal.In addition,the magnetic biochar deactivated by mercury removal has excellent thermal regeneration stability,with about 80%mercury removal efficiency after thermal regeneration at 450°C and cycling four times.

关 键 词：单质汞 磁性生物焦 富氧燃烧 酸性气体 吸附效率 氧化效率 

分 类 号：X701[环境科学与工程—环境工程]