低低温系统中粉尘颗粒团聚特性研究
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摘要
由于低低温条件下粉尘颗粒物的团聚效应,实际运行中低低温省煤器和电除尘器容易出现积灰堵塞问题。本文搭建固定床吸附实验台,研究了颗粒物吸附硫酸酸雾后的团聚现象,以及各因素对团聚的影响程度。结果表明:吸附反应后单个颗粒物存在4种表面形态,颗粒物间存在4种团聚形态;硫酸酸雾在颗粒物表面产生一层液膜,使颗粒物间黏附力增强,强化了团聚效果;初始阶段主要发生小颗粒在大颗粒表面的黏附以及小颗粒之间的凝并,随后发生大颗粒之间的团聚;温度降低会提升颗粒物团聚的效果,但提升程度与吸附时间有关;在低低温系统中,温度的小幅变动将会引起团聚效果很大的改变;随着颗粒物粒径的增大,颗粒物的团聚效果减弱,粒径增大至91μm以上时几乎不发生团聚。
Due to agglomeration of ash particles under low-low temperature conditions, ash deposition block occurs very easily in low-low temperature economizer and electrical static precipitator during actual operation. To deal with this issue, the authors built up a fixed-bed adsorption experimental bench and studied the agglomeration of particles adsorbed by sulfuric acid mist and the influence of various factors on the agglomeration. The results show that, there are four kinds of surface morphology of the individual particle and four kinds of agglomeration morphology between the particles. A layer of acid liquid film is formed on the particles' surface, which enhances the adhesion between particles and strengthens the agglomeration effect. In the initial stage, the small particles adhere onto the surface of large particles or the agglomeration between small particles occurs, followed by the agglomeration between large particles. The drop of adsorption temperature improves the agglomeration, but the improvement degree depends on the adsorption time. In the low-low temperature flue gas system, small variations in temperature will cause significant change of the agglomeration. The agglomeration effect decreases with the increasing particle size, and almost no agglomeration occurrs when the particle size increases to above 91 μ m.
Due to agglomeration of ash particles under low-low temperature conditions, ash deposition block occurs very easily in low-low temperature economizer and electrical static precipitator during actual operation. To deal with this issue, the authors built up a fixed-bed adsorption experimental bench and studied the agglomeration of particles adsorbed by sulfuric acid mist and the influence of various factors on the agglomeration. The results show that, there are four kinds of surface morphology of the individual particle and four kinds of agglomeration morphology between the particles. A layer of acid liquid film is formed on the particles' surface, which enhances the adhesion between particles and strengthens the agglomeration effect. In the initial stage, the small particles adhere onto the surface of large particles or the agglomeration between small particles occurs, followed by the agglomeration between large particles. The drop of adsorption temperature improves the agglomeration, but the improvement degree depends on the adsorption time. In the low-low temperature flue gas system, small variations in temperature will cause significant change of the agglomeration. The agglomeration effect decreases with the increasing particle size, and almost no agglomeration occurrs when the particle size increases to above 91 μ m.
引文
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[15]刘宇钢,罗志忠,陈刚,等.低温省煤器及MGGH运行中存在典型问题分析及对策[J].东方电气评论,2016,30(2):31-35.LIU Yugang,LUO Zhizhong,CHEN Gang,et al.Cause analyse(i)s on typical operational problems of low temperature economizer and MGGH and proposed countermeasures[J].Dongfang Electric Review,2016,30(2):31-35.
[2]KATO M,TANAKA T,NISHIMURA Y,et al.Method and system for handling exhaust gas in a boiler:US5282429 A[P].1994-02-01.
[3]MISAKAT,YOSHIHIKO M.Recent application and running cost of moving electrode type electrostatic precipitator[C]//11th International Conference on Electrostatic Precipitation.Hangzhou:Zhejiang University Press,2008:518-522.
[4]STEPHEN L F,ANDREAS B,JOHANSSON P.Reduction of rapping losses to improve ESP performance[C]//11th International Conference on Electrostatic Precipitation.Hangzhou:Zhejiang University Press,2008:45-49.
[5]QI L Q,YUAN Y T.Influence of SO3 in flue gas on electrostatic perceptibility of high-alumina coal fly ash from a power plant in China[J].Powder Technology,2013,245(8):163-167.
[6]NAKAYAMA Y,NAKAMURA S,TAKEUCHI Y,et al.MHI high efficiency system:proven technology for multi pollutant removal[R].Hiroshima Research&Development Center,2011:1-11.
[7]郦建国.低低温电除尘技术及其工程应用[C]//第十七届中国电除尘学术会议论文集.安徽:中国环境保护产业协会电除尘委员会,2017:7.LI Jianguo.Low-low temperature ESP technology and its engineering application[C]//Proceedings of 17th Conference of ESP.Anhui:China Environmental Protection Industry,2017:7.
[8]任海聪.火力发电厂超低排放改造低低温省煤器[C]//燃煤电厂超低排放形势下SCR脱硝系统运行管理及氨逃逸监测、空预器堵塞与低温省煤器改造技术交流研讨会论文集.南京:中国节能协会热电产业联盟,2016:7.REN Haicong.Ultra-low emission reform of low-low temperature system in power plants[C]//Conference of the operation and management of SCR denitrification system and monitoring of ammonia slip in the case of ultra-low emission of coal-fired power plants.Nanjing:China Energy Conservation Association,2016:7.
[9]罗如生.不同烟温下低低温电除尘器粉尘脱除能力的比较分析[C]//第十七届中国电除尘学术会议论文集.安徽:中国环境保护产业协会电除尘委员会,2017:4.LUO Rusheng.Comparison and analysis of dust removal ability of low-low temperature ESP at different flue gas temperatures[C]//Proceedings of 17th Conference of ESP.Anhui:China Environmental Protection Industry,2017:4.
[10]蒋俊.低低温电除尘器的应用及其存在的问题[C]//第十五届中国电除尘学术会议论文集.合肥:中国环保产业协会电除尘委员会,2013:410-413.JIANG Jun.The application and existing problem of low-low temperature flue gas system[C]//Proceedings of15th Conference of ESP.Hefei:China Environmental Protection Industry,2013:410-413.
[11]罗陨飞,李文华,姜英,等.中国煤中硫的分布特征研究[J].煤炭转化,2005,28(3):14-18.LUO Yunfei,LI Wenhua,JIANG Ying,et al.Distribution of sulfur in coals of China[J].Coal Conversion,2005,28(3):14-18.
[12]SHEN Y M,DONG K,CUI Z Y,et al.The theoretical calculation of designed temperature of flue gas in low-low temperature electrostatic precipitator and the existing problems[J].Electric Power,2016,49(7):151-156.
[13]ANDREAS B.Enhancing ESP efficiency for high resistivity fly ash by reducing the flue gas temperature[C]//11th International Conference on Electrostatic Precipitation.Hangzhou:Zhejiang University Press,2008:406-411.
[14]陆军,刘永强,周飞,等.高硫煤机组低低温省煤器SO3协同脱除试验研究[J].热力发电,2016,45(12):30-36.LU Jun,LIU Yongqiang,ZHOU Fei,et al.Experimental research on simultaneous removal of SO3 by low-low temperature economizer in units firing high-sulfur coal[J].Thermal Power Generation,2016,45(12):30-36.
[15]刘宇钢,罗志忠,陈刚,等.低温省煤器及MGGH运行中存在典型问题分析及对策[J].东方电气评论,2016,30(2):31-35.LIU Yugang,LUO Zhizhong,CHEN Gang,et al.Cause analyse(i)s on typical operational problems of low temperature economizer and MGGH and proposed countermeasures[J].Dongfang Electric Review,2016,30(2):31-35.