引用本文:武亚凤,陈建华,蒋靖坤,邓建国,马子珍,钟连红,等.燃煤电厂细颗粒物排放粒径分布特征[J].环境科学研究,2017,30(8):1174-1183.
WU Yafeng,CHEN Jianhua,JIANG Jingkun,DENG Jianguo,MA Zizhen,ZHONG Lianhong,et al.Size Distribution Characteristics of Fine Particles from a Coal-Fired Power Plant[J].Reserrch of Environmental Science,2017,30(8):1174-1183.]
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燃煤电厂细颗粒物排放粒径分布特征
武亚凤1, 陈建华1, 蒋靖坤2, 邓建国2, 马子珍2, 钟连红3
1.中国环境科学研究院环境标准研究所, 北京 100012 ;2.清华大学环境学院, 北京 100084 ;3.北京市环境保护科学研究院, 北京 100037
摘要:
目前细颗粒物区域污染已成为普遍现象,控制燃煤电厂细颗粒物的排放是控制大气中细颗粒物的重要途径之一,而了解燃煤电厂细颗粒物的排放粒径分布及其形成的可能原因和影响因素显得尤为重要. 针对浙江某电厂660 MW燃煤机组,在120、100、90和85 ℃四种不同运行工况下,采用Dekati ELPI+对电除尘器入口和出口以及烟囱60 m横断面处烟尘进行多平台同步采样测试,以研究该电厂所排放细颗粒物的粒径分布特征、不同工况下细颗粒物的排放浓度及其变化规律. 结果表明:①不同工况下,电除尘器出口和烟囱60 m横断面处颗粒物数浓度都主要集中在亚微米态(粒径<1 μm),并随粒径增大而数浓度快速减小. ②随着烟冷器出口烟气温度的降低,烟气经过除尘装置后,无论是颗粒数浓度还是质量浓度均有一定程度的下降,但当烟气温度降至90 ℃时,继续降温对电除尘器除尘效果的影响基本趋于恒定. ③无论燃用设计煤还是校验煤,当烟冷器出口烟气温度相对较低时,经脱硫后积聚模态颗粒物质量浓度较除尘后有明显增加;而烟气温度较高时,呈现出脱硫后较除尘后粗模态颗粒物质量浓度增长的现象. ④当原烟气稀释倍数从7倍增至10倍时,6~27 nm粒径段颗粒物数浓度呈指数倍增长,说明稀释过程主要影响纳米级颗粒物的数浓度. ⑤燃用设计煤,烟冷器出口烟气温度90 ℃时,电除尘器对PM1的去除效果最明显为63.9%~99.8%,可见降低电除尘器入口运行烟温,可促进其对亚微米态颗粒物的捕集率.
关键词:  细颗粒物(PM2.5)  粒径分布  稀释比  烟冷器
DOI:
分类号:
基金项目:国家环境保护公益性行业科研专项(201309046);国家自然科学基金项目(21277132);北京市环境保护科学研究院院基金项目(2013-B-02)
Size Distribution Characteristics of Fine Particles from a Coal-Fired Power Plant
WU Yafeng1, CHEN Jianhua1, JIANG Jingkun2, DENG Jianguo2, MA Zizhen2, ZHONG Lianhong3
1.Research Institute of Environmental Standard, Chinese Research Academy of Environmental Sciences, Beijing 100012, China ;2.School of Environment, Tsinghua University, Beijing 100084, China ;3.Beijing Municipal Research Institute of Environmental Protection, Beijing 100037, China
Abstract:
Abstract: Regional fine particulate matter pollution has become a common phenomenon recently. Controlling the emissions of fine particulate matter from coal-fired power plants is one of the most important ways to control fine particulate matter in the atmosphere. It is especially important to determine the size distribution of fine particles from coal-fired power plants and the possible causes of formation and influencing factors. Based on one 660 MW coal-fired power unit in Zhejiang Province, the Dekati ELPI+ was applied to do multi-platform sampling testing for smoke at the inlet and outlet of the electrostatic precipitator, as well as the cross section of the chimney (60 m) at different operating conditions of 120,0, 90 and 85 ℃. The goal was to study the size distribution characteristics of fine particles discharged from the power plant and how the emission concentrations of fine particulate matter is affected by different operating conditions. The results showed that:(1) Number concentration of particles was mainly concentrated on submicron modal (aerodynamic diameter smaller than 1 μm); with the increase of particle size, the number concentration rapidly decreased. (2) Both number concentration and mass concentration of fine particles at the outlet of the electrostatic precipitator decreased somewhat with the fall of flue gas temperature at the low-temperature economizer exit; nevertheless, when the temperature was reduced to 90 ℃, collection efficiency of the electrostatic precipitator tended to be roughly constant. (3) Mass concentration of particles at accumulation modal after the desulfurization device was higher than at the outlet of the electrostatic precipitator when the flue gas temperature at the low-temperature economizer exit was lower, regardless of whether designed coal or checked coal was burned. On the contrary, when the temperature was higher, the mass concentration of particles at coarse mode was relatively higher after the desulfurization device. (4) In the dilution ratio range chosen in this study, number concentrations of particles with aerodynamic diameter between 6 nm and 27 nm exponentially increased when the dilution ratio was increased from 7 to 10 times; the conclusion was that the number concentration of nanoparticles was affected mainly during dilution. (5) The removal efficiency (63.9%-99.8%) of the electrostatic precipitator was the highest for PM1 when the flue gas temperature was 90 ℃ after low-temperature economizer when the designed coal was burned. Thus, the trapping of PM1 was promoted when the temperature of flue gas was low at the outlet of the electrostatic precipitator.
Key words:  fine particles (PM2.5)  size distribution  dilution ratio  low-temperature economizer