氯盐改性堇青石吸附剂氧化烟气中Hg^(0)的试验  

Experimental study on oxidation removal of elemental mercury from flue gas by chloridesalts modified cordierite adsorbents

作　　者：邢向文 方蓓蓓 张肖阳 崔琳[1,2] 董勇[1,2] XING Xiangwen;FANG Beibei;ZHANG Xiaoyang;CUI Lin;DONG Yong(School of Energy and Power Engineering,Shandong University,Jinan 250061,China;National Engineering Laboratory for Reducing Emissions from Coal Combustion,Shandong University,Jinan 250061,China)

机构地区：[1]山东大学能源与动力工程学院,山东济南250061 [2]山东大学燃煤污染物减排国家工程实验室,山东济南250061

出　　处：《洁净煤技术》2022年第4期51-58,共8页Clean Coal Technology

基　　金：国家自然科学基金资助项目(51976108)。

摘　　要：汞具有挥发性且有剧毒,是煤中有害痕量重金属元素之一。在燃烧过程中,燃煤中的汞主要以Hg^(0)的形式释放到烟气中。烟气中的Cl元素可将Hg^(0)高效氧化成Hg^(2+),Hg^(2+)可在下游的除尘和湿法脱硫设备中被捕集脱除。然而,我国燃煤大部分属于低氯煤,燃煤电厂烟气中Hg^(0)比例较高,造成电厂现有烟气污染物控制单元对Hg^(0)的协同脱除效率较低。针对我国燃煤氯含量较低,烟气中Hg^(0)氧化效果差,Hg^(0)含量高的问题,提出利用4种氯盐对堇青石进行浸渍改性,制备成MCl_(x)/Cord吸附剂,对该吸附剂进行较宽温度窗口的Hg^(0)氧化试验,探究氯盐改性堇青石对Hg^(0)的氧化性能。结果表明:在0~8%O_(2)体积分数和150~350℃时,堇青石载体Hg^(0)脱除效率最高仅8%;而用CaCl_(2)、MgCl_(2)、FeCl_(3)和CuCl_(2)改性后堇青石吸附剂的Hg^(0)脱除效率分别达30%、95%、97%和98%。可见,氯盐改性极大提高了堇青石吸附剂氧化Hg^(0)的性能。温度和O_(2)体积分数对MgCl_(2)/Cord、CaCl_(2)/Cord和FeCl_(3)/Cord吸附剂中的氯元素析出影响很大,造成Hg^(0)脱除效率波动较大。CuCl_(2)/Cord的Hg^(0)脱除效率受温度和O_(2)体积分数影响不大,Hg^(0)脱除效率稳定在93%以上,表现出非常稳定的氧化Hg^(0)性能,适合作为氧化烟气中Hg^(0)的潜在吸附剂。氯盐浸渍改性可提高堇青石对Hg^(0)的氧化性能,CuCl_(2)浸渍改性堇青石具有最佳的Hg^(0)氧化效果,且几乎不受温度和O_(2)体积分数变化的影响。Mercury is one of the harmful trace heavy metal elements in coal with strong volatility and toxicity.During coal combustion,mer⁃cury is mainly released into the flue gas in the form of Hg^(0).The element Cl in flue gas can efficiently oxidize Hg^(0) to Hg^(2+),and then Hg^(2+)can be removed in downstream dust removal and wet desulfurization facilities.However,most of the coal in China belongs to low-chlorine coal,resulting in a high proportion of Hg^(0) in flue gas,and the low mercury removal efficiency of existing flue gas pollu⁃tant control units in power plants.In order to solve the problems of low chlorine content,poor oxidation effect and high content of Hg^(0) in flue,it was proposed to impregnate cordierite with four kinds of chlorine salts to prepare MCl_(x)/Cord adsorbent.The Hg^(0) oxidation experi⁃ment of the adsorbent with a wide temperature window was carried out to explore the oxidation performance of cordierite modified by chlo⁃rine salts to Hg^(0).The results show that in the range of 0-8%O_(2) content and 150-350℃,the highest Hg^(0) removal efficiency of cordierite is only 8%,while that of cordierite sorbents modified with CaCl_(2),MgCl_(2),FeCl_(3) and CuCl_(2) reach 30,95,97 and 98%,respectively.It can be seen that the chlorine salts greatly improve the performance of cordierite sorbents for removal of Hg^(0).The temperature and oxygen content have great influence on the Hg^(0) removal performance of MgCl_(2)/Cord,CaCl_(2)/Cord and FeCl_(3)/Cord.The temperature and O_(2) content have little influence on the Hg^(0) removal efficiency of CuCl_(2)/Cord,which is always more than 93%.CuCl_(2)/Cord shows a stable performance on mercury oxidation removal,so it is suitable to be used as a potential oxidation sorbent for oxidation and adsorption removal of Hg^(0) from flue gas.Chlorine salt impregnation modification can improve the oxidation performance of cordierite to Hg^(0).Cordierite modified by CuCl_(2) impregnation has the best Hg^(0) oxidation effect,and it is almost not affected by the

关 键 词：单质汞 堇青石 氯盐 浸渍改性 Hg^(0)脱除 

分 类 号：X701[环境科学与工程—环境工程]