| 小型燃煤机组烟气重金属排放特征研究 |
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| 引用本文： | 左朋莱,王晨龙,佟莉,高佳佳,张晓曦,王堃,岳涛.小型燃煤机组烟气重金属排放特征研究[J].环境科学研究,2020,33(11):2599-2604. |
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| 作者姓名： | 左朋莱 王晨龙 佟莉 高佳佳 张晓曦 王堃 岳涛 |
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| 作者单位： | 北京市劳动保护科学研究所, 北京 100054 |
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| 基金项目： | 国家重点研发计划项目（No.2016YFC0203701，2016YFC0208103）；创新团队计划项目（NO.IG201804N） |
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| 摘 要： | 100 MW以下燃煤机组呈单台容量小、总台数大的特点，是燃煤重金属污染的主要排放源之一.选择7台12 MW燃煤机组，采用美国环境保护局Method 29法现场检测燃煤机组烟气重金属排放浓度，分析烟气中Hg、Pb、Cr、As的排放特征；采集机组产生的飞灰和底灰，分析除尘技术对重金属的富集特性.结果表明:100 MW以下燃煤机组烟气中重金属经脱硝除尘脱硫装置协同控制后，ρ（Hg）为0.20~0.44 μg/m3，烟气Hg以气态形式存在，其占比为100.0%；ρ（Pb）为0.5~2.6 μg/m3，烟气Pb主要以气态形式存在，其占比为38.7%~92.1%；ρ（As）为0.6~3.0 μg/m3，烟气As主要以气态形式存在，其占比为67.8%~100.0%；ρ（Cr）为3.6~23.9 μg/m3，烟气Cr主要以颗粒态形式存在，其占比为65.8%~99.2%.飞灰富集Hg、Pb、Cr、As的能力大于底灰.重金属主要富集于飞灰中的细颗粒物中，采取除尘技术可有效协同控制烟气中的Hg、Pb、Cr、As；飞灰中重金属元素Hg、Pb相对富集系数均与煤中硫含量呈负相关，半干法脱硫+袋式除尘技术对飞灰富集Hg有促进作用.小型燃煤机组烟气重金属Hg、Pb、Cr、As的排放因子分别为0.002 2~0.005 1、5~17、42~160、7~24 mg/t.研究显示，100 MW以下燃煤机组与100 MW及以上燃煤机组烟气重金属Hg、Pb、Cr、As排放特征不同，100 MW以下燃煤机组烟气Hg排放浓度较小，二者烟气Pb、Cr、As排放浓度相近，选用湿式电除尘技术可进一步降低烟气Hg、Pb、Cr、As的排放浓度.
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| 关 键 词： | 燃煤机组 烟气排放特征 协同控制 重金属 |
| 收稿时间： | 2019/11/24 0:00:00 |
| 修稿时间： | 2020/5/27 0:00:00 |
Emission Characteristics of Heavy Metal in Flue Gas of Small Coal-Fired Units |
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| ZUO Penglai,WANG Chenlong,TONG Li,GAO Jiajia,ZHANG Xiaoxi,WANG Kun,YUE Tao.Emission Characteristics of Heavy Metal in Flue Gas of Small Coal-Fired Units[J].Research of Environmental Sciences,2020,33(11):2599-2604. |
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| Authors: | ZUO Penglai WANG Chenlong TONG Li GAO Jiajia ZHANG Xiaoxi WANG Kun YUE Tao |
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| Affiliation: | Beijing Municipal Institute of Labour Protection, Beijing 100054, China |
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| Abstract: | The coal-fired units below 100 MW have the characteristics of small capacity and large total number, and they are one of the main emission sources of heavy metal pollution from coal-burning. US EPA Method 29 is used to detect the emission concentration of heavy metals in the flue gas of coal-fired units, analyze the emission characteristics of Hg, Pb, Cr and As in the flue gas; collect the fly ash and bottom ash produced by the units, and analyze the heavy metals from dust removal technology the enrichment characteristics. Based on the field-measurement data, the emission characteristics of Hg, Pb, Cr and As in the flue gas of seven 12 MW coal-fired units are analyzed. The results showed that under the cooperative control of denitrification, dust removal and desulfurization devices, the emission concentrations of Hg, Pb and As in flue gas are 0.20-0.44 μg/m3, 0.5-2.6 μg/m3 and 0.6-3.0 μg/m3, respectively. These three heavy metals mainly exist in the form of gases, accounting for 100.0%, 38.7%-92.1% and 67.8%-100%, respectively. While Cr mainly exists in particulate form, accounting for 65.8%-99.2%, and the emission concentration in flue gas is 3.6-23.9 μg/m3. The relative enrichment factors (REF) of Hg, Pb, Cr and As in fly ash are higher than in bottom ash. Heavy metals are mainly concentrated in fine particles in fly ash, and dust removal device can control Hg, Pb, Cr and As in flue gas synergistically. The relative enrichment factors (REF) of Hg, and Pb in fly ash are negatively correlated with the sulfur content in coal. Semi-dry desulfurization plus fabric filter dust removal technology can promote the enrichment of Hg in fly ash. The emission factors of Hg, Pb, Cr, Pb, As in flue gas of small coal-fired units are 0.0022-0.0051, 5-17, 42-160, and 7-24 mg/t, respectively. This study shows that the emission characteristics of heavy metals in flue gas of coal-fired units below 100 MW are different from those of coal-fired units above 100 MW, the emission concentration of Hg in flue gas is low, the emission concentrations of Pb, Cr and As in flue gas are similar, the wet electrostatic precipitation technology can further reduce the emissions of Hg, Pb, Cr and As from flue gas. |
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| Keywords: | coal-fired units characteristics of flue gas emission cooperative control heavy metals |
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