煤粉燃烧中添加改性高岭土脱除Pb和V实验研究
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摘要
采用盐酸和醋酸钙两种方法改性高岭土。分别将原高岭土和两种改性高岭土与煤粉按照3:100的比例混合均匀,送入高温沉降炉中进行1500°C条件下的燃烧实验。利用低压撞击器(LPI)取样系统收集粒径小于10?m的颗粒物,通过微波消解、ICP-MS测试测定各粒径颗粒物中重金属Pb和V的含量。结果表明:原高岭土、盐酸改性高岭土和醋酸钙改性高岭土减排超细颗粒物(PM0.2)中Pb的效率分别为20.9%、30.8%和35.6%;减排超细颗粒物中V的效率分别为24.4%、37.3%和41.9%。盐酸处理后,高岭土晶体结构部分遭到破坏,比表面积和孔体积增加,为捕集重金属提供更多的活性位点;醋酸钙改性后,高岭土中混入醋酸钙,增强了与重金属的反应,并且高岭土颗粒在高温下能够部分与氧化钙反应,生成熔融颗粒,促进液相捕集过程。
Two kinds of typical modification methods were selected to modify kaolin, namely, the hydrochloric acid modification and the calcium acetate modification. Then,pulverized coal was burned with raw and modified kaolin separately in an electrical heated drop-tube furnace, and the mass yield of Pb and V were obtained. The results indicate that the mass yield of Pb in PM0.2(particulate matters less than 0.2μm in aerodynamic diameter) reduction by adding raw kaolin and two modified kaolin are 20.9%, 30.8% and 35.6%; and the mass yield of V in PM0.2 reduction are 24.4%, 37.3% and41.9%. It is found that the modification by hydrochloric acid can increase the specific surface area and pore volume of kaolin, and provide more active sites to capture heavy metals.The kaolin modified by calcium acetate enhances reaction between kaolin and heavy metals; at the same time, the kaolin particles can partially react with calcium acetate at high temperature to generate molten particles, which promotes the liquid phase capture process.
Two kinds of typical modification methods were selected to modify kaolin, namely, the hydrochloric acid modification and the calcium acetate modification. Then,pulverized coal was burned with raw and modified kaolin separately in an electrical heated drop-tube furnace, and the mass yield of Pb and V were obtained. The results indicate that the mass yield of Pb in PM0.2(particulate matters less than 0.2μm in aerodynamic diameter) reduction by adding raw kaolin and two modified kaolin are 20.9%, 30.8% and 35.6%; and the mass yield of V in PM0.2 reduction are 24.4%, 37.3% and41.9%. It is found that the modification by hydrochloric acid can increase the specific surface area and pore volume of kaolin, and provide more active sites to capture heavy metals.The kaolin modified by calcium acetate enhances reaction between kaolin and heavy metals; at the same time, the kaolin particles can partially react with calcium acetate at high temperature to generate molten particles, which promotes the liquid phase capture process.
引文
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[24]Wang Xinye,Huang Yaji,Zhong Zhaoping,et al.Control of inhalable particulate lead emission from incinerator using kaolin in two addition modes[J].Fuel Processing Technology,2014,119:228-235.
[25]Davis S B,Wendt J O L.Mechanism and kinetics of lead capture by kaolinite in a downflow combustor[J].Proceedings of the Combustion Institute,2000,28(2):2743-2749.
[26]张小锋,姚强,宋蔷,等.燃烧中铅元素排放特性的实验研究[J].中国电机工程学报,2007,27(32):18-23.Zhang Xiaofeng,Yao Qiang,Song Qiang,et al.Experimental study on the emission characteristics of lead during combustion[J].Proceedings of the CSEE,2007,27(32):18-23(in Chinese).
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[28]Gale T K,Wendt J O L.High-temperature interactions between multiple-metals and kaolinite[J].Combustion and Flame,2002,131(3):299-307.
[2]Vejahati F,Xu Zhenghe,Gupta R.Trace elements in coal:associations with coal and minerals and their behavior during coal utilization-A review[J].Fuel,2010,89(4):904-911.
[3]张英,周长民.重金属铅污染对人体的危害[J].辽宁化工,2007,36(6):395-397.Zhang Ying,Zhou Changmin.Hazards of Pb pollution to health[J].Liaoning Chemical Industry,2007,36(6):395-397(in Chinese).
[4]Environmental Protection Agency.EPA-HQ-OAR-2009-0234 Mercury and air toxics standards[S].Wasington:Federal Register,2016.
[5]吴涛,兰昌云.环境中的钒及其对人体健康的影响[J].广东微量元素科学,2004,11(1):11-15.Wu Tao,Lan Changyun.Vanadium in environment and its harm to human health[J].Guangdong Trace Elements Science,2004,11(1):11-15(in Chinese).
[6]曹蕃,郭婷婷,金绪良,等.湿式电除尘器冲洗废水排入脱硫系统的影响分析[J].中国电机工程学报,2018,38(6):1743-1750.Cao Fan,Guo Tingting,Jin Xuliang,et al.Influence analysis of wet electrostatic precipitator washing wastewater piping in desulfurizing absorption tower[J].Proceedings of the CSEE,2018,38(6):1743-1750(in Chinese).
[7]徐婧,顾煜炯,王仲,等.基于数据挖掘的煤电机组能效特征指标及其基准值的研究[J].中国电机工程学报,2017,37(7):2009-2015.Xu Jing,Gu Yujiong,Wang Zhong,et al.Research on indexes of energy efficiency and its reference-value for coal-fired power units based on data-mining[J].Proceedings of the CSEE,2017,37(7):2009-2015(in Chinese).
[8]Uberoi M,Shadman F.Sorbents for removal of lead compounds from hot flue gases[J].AIChE Journal,1990,36(2):307-309.
[9]Yao Hong,Mkilaha I S N,Naruse I.Screening of sorbents and capture of lead and cadmium compounds during sewage sludge combustion[J].Fuel,2004,83(7-8):1001-1007.
[10]Zhao Yi,Lin W C.Multi-functional sorbents for the simultaneous removal of sulfur and lead compounds from hot flue gases[J].Journal of Hazardous Materials,2003,103(1-2):43-63.
[11]LEE S R,Wu Changyu.Study of vanadium emission control in combustion systems by thermodynamic equilibrium analyses[J].Advances in Environmental Research,2002,7(1):1-10.
[12]Lee S R,Wu Changyu,Andino J M.A mechanistic study of vanadium-sorbent surface interaction at high temperature[J].Aerosol Science and Technology,2007,41(12):1063-1075.
[13]Sun Wei,Liu Xiaowei,Xu Yishu,et al.Effects of the modified kaolin sorbents on the reduction of ultrafine particulate matter(PM0.2)emissions during pulverized coal combustion[J].Fuel,2018,215:153-160.
[14]Belver C,Mu?oz M A B,Vicente M A.Chemical activation of a kaolinite under acid and alkaline conditions[J].Chemistry of Materials,2002,14(5):2033-2043.
[15]Wang Chao,Liu Xiaowei,Li Dong,et al.Effect of H2O and SO2 on the distribution characteristics of trace elements in particulate matter at high temperature under oxy-fuel combustion[J].International Journal of Greenhouse Gas Control,2014,23:51-60.
[16]Davison R L,Natusch D F S,Wallace J R,et al.Trace elements in fly ash.dependence of concentration on particle size[J].Environmental Science&Technology,1974,8(13):1107-1113.
[17]徐鸿,骆仲泱,王鹏,等.石灰石对煤燃烧产生颗粒物及重金属影响实验研究[J].工程热物理学报,2004,25(5):871-874.Xu Hong,Luo Zhongyang,Wang Peng,et al.Experimental research of limestone effect on particulates and heavy metals emitted from coal combustion[J].Journal of Engineering Thermophysics,2004,25(5):871-874(in Chinese).
[18]Wang Xinye,Huang Yaji,Pan Zhigang,et al.Theoretical investigation of lead vapor adsorption on kaolinite surfaces with DFT calculations[J].Journal of Hazardous Materials,2015,295:43-54.
[19]Jiang Mingqin,Wang Qingping,Jin Xiaoying,et al.Removal of Pb(II)from aqueous solution using modified and unmodified kaolinite clay[J].Journal of Hazardous Materials,2009,170(1):332-339.
[20]许英梅,张秋民,姜慧明,等.由木醋液制醋酸钙镁盐类环保型融雪剂研究[J].大连理工大学学报,2007,47(4):494-496.Xu Yingmei,Zhang Qiumin,Jiang Huiming,et al.Preparation of environment friendly calciummagnesium acetate deicers from pyroligneous liquid[J].Journal of Dalian University of Technology,2007,47(4):494-496(in Chinese).
[21]Zeng Xianpeng,Yu Dunxi,Liu Fangqi,et al.Scavenging of refractory elements(Ca,Mg,Fe)by kaolin during low rank coal combustion[J].Fuel,2018,223:198-210.
[22]Si Junping,Liu Xiaowei,Xu Minghou,et al.Effect of kaolin additive on PM2.5 reduction during pulverized coal combustion:importance of sodium and its occurrence in coal[J].Applied Energy,2014,114:434-444.
[23]Chen J C,Wey M Y,Lin Yaochi.The adsorption of heavy metals by different sorbents under various incineration conditions[J].Chemosphere,1998,37(13):2617-2625.
[24]Wang Xinye,Huang Yaji,Zhong Zhaoping,et al.Control of inhalable particulate lead emission from incinerator using kaolin in two addition modes[J].Fuel Processing Technology,2014,119:228-235.
[25]Davis S B,Wendt J O L.Mechanism and kinetics of lead capture by kaolinite in a downflow combustor[J].Proceedings of the Combustion Institute,2000,28(2):2743-2749.
[26]张小锋,姚强,宋蔷,等.燃烧中铅元素排放特性的实验研究[J].中国电机工程学报,2007,27(32):18-23.Zhang Xiaofeng,Yao Qiang,Song Qiang,et al.Experimental study on the emission characteristics of lead during combustion[J].Proceedings of the CSEE,2007,27(32):18-23(in Chinese).
[27]张小锋,姚强,宋蔷,等.燃烧中吸附剂捕集铅的实验研究[J].中国电机工程学报,2008,28(2):61-65.Zhang Xiaofeng,Yao Qiang,Song Qiang,et al.Experimental study on lead capture by sorbents during combustion[J].Proceedings of the CSEE,2008,28(2):61-65(in Chinese).
[28]Gale T K,Wendt J O L.High-temperature interactions between multiple-metals and kaolinite[J].Combustion and Flame,2002,131(3):299-307.