本文關(guān)鍵詞：燃煤電站砷、鉛、鎘、鉻的遷移規(guī)律　出處：《華北電力大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

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【摘要】：燃煤電站是重金屬污染的主要排放源之一,由于不同重金屬的物理化學(xué)特性的差別,燃燒過(guò)程中重金屬元素有些以氣相形式排入大氣,有些富集于飛灰和底渣中。砷、鉛、鎘、鉻屬于煤燃燒過(guò)程中易揮發(fā)的元素,燃煤電站先進(jìn)的環(huán)保裝置(SCR、 ESP、FGD)不能有效的捕獲,任由重金屬無(wú)控制的排放入自然環(huán)境中,會(huì)對(duì)環(huán)境產(chǎn)生巨大的危害。本論文選取四家典型燃煤電站,對(duì)燃燒過(guò)程中砷、鉛、鎘、鉻四種重金屬元素的分布、以及賦存形態(tài)進(jìn)行了較為系統(tǒng)的研究。針對(duì)煤的復(fù)雜結(jié)構(gòu),重金屬元素含量低,揮發(fā)性強(qiáng)等特點(diǎn),本文采用先進(jìn)的微波消解技術(shù),建立了適用于批量檢測(cè)且高效、準(zhǔn)確分析各種原煤、飛灰、煙氣等樣品中砷、鉛、鎘、鉻的測(cè)定方法,為深入研究重金屬元素的遷移轉(zhuǎn)化規(guī)律奠定了良好的基礎(chǔ)。對(duì)三家典型燃煤電站燃燒過(guò)程中砷、鉛、鎘、鉻四種重金屬元素的分布、以及賦存形態(tài)進(jìn)行了較為系統(tǒng)的研究。對(duì)煤燃燒產(chǎn)物飛灰、底渣,以及FGD過(guò)程中使用脫硫石灰石、脫硫石膏、廢水進(jìn)行了研究,并采用EPA方法29對(duì)2個(gè)燃煤電站ESP前后煙氣、FGD后煙氣排放特征進(jìn)行分析。研究表明砷主要以飛灰形式釋放,靜電除塵器對(duì)砷有很強(qiáng)的捕獲能力,FGD對(duì)砷也有一定的捕獲能力,脫硫廢水中砷的濃度不高,經(jīng)處理后排放不會(huì)斷環(huán)境造成影響,FGD后煙氣中砷的含量很低；鉛極大部分釋放于飛灰中,在底渣中沒(méi)有檢測(cè)到鉛；鎘主要富集在飛灰和底渣中,約有30%存在于底渣中,70%存在于飛灰中,在ESP煙氣中均沒(méi)有檢測(cè)到鎘；鉻主要富集在飛灰和底渣中,飛灰和底渣中鉻的濃度近似相同,在除塵后煙氣中只檢測(cè)到微量的鉻。對(duì)某燃煤電站飛灰進(jìn)行篩分,探索砷在飛灰中的分布規(guī)律的因素。研究發(fā)現(xiàn)飛灰中砷含量隨粒徑增大顯著下降,飛灰中砷的富集并不是由于飛灰中碳的物理吸附造成；砷在飛灰中的富集與飛灰中的鈣、鎂、鐵含量的走勢(shì)近似相同,推斷飛灰中鈣基物質(zhì)的化學(xué)吸附是砷在飛灰中富集的原因。
[Abstract]:Coal fired power plant is one of the main sources of heavy metal pollution, due to the physical and chemical properties of different heavy metals, different heavy metal elements in the combustion process to form some gas into the atmosphere, some enriched in fly ash and slag in. Arsenic, lead, cadmium and chromium belong to volatile elements in coal combustion process. The advanced environmental protection devices (SCR, ESP and FGD) of coal-fired power plants can not be effectively captured. Allowing heavy metals to be discharged into the natural environment without any control will cause great harm to the environment. In this paper, four typical coal-fired power plants were selected, and the distribution and occurrence patterns of four heavy metals, including arsenic, lead, cadmium and chromium, were systematically studied. In view of the complex structure of coal, heavy metal content is low, and the characteristics of strong volatility, using advanced microwave digestion technology, set up suitable for batch testing and efficient and accurate analysis of various coal, fly ash, flue gas and other methods of determination of arsenic, lead, cadmium and chromium in the sample, and laid a good foundation for further migration study on the transformation of heavy metals. The distribution and occurrence of arsenic, lead, cadmium and chromium in the combustion process of three typical coal-fired power plants were systematically studied. For coal combustion fly ash, slag, and FGD in the process of using limestone and gypsum, desulfurization wastewater was studied by using EPA method, and 29 of the 2 coal-fired power plant flue gas before and after ESP and FGD characteristics of flue gas emission analysis. Research shows that the main arsenic in fly ash release, electrostatic precipitator has strong ability to capture the arsenic, FGD also has the ability to capture some of the arsenic concentration of arsenic in wastewater, desulfurization is not high, after treatment discharge will not break the environmental impact, the FGD content of arsenic in flue gas is very low; the great part of lead release in fly ash, slag not detected in the lead; cadmium mainly enriched in fly ash and bottom ash, about 30% in the bottom ash, 70% in fly ash, flue gas in the ESP were not detected cadmium; chromium mainly enriched in fly ash and slag, fly ash and bottom ash concentration chromium in approximately the same, after the dust in flue gas was only detected in trace amounts of chromium. The fly ash of a coal-fired power plant is screened and the factors of the distribution of arsenic in fly ash are explored. The study found that the arsenic content of fly ash increases with the particle size decreased significantly, and the enrichment of arsenic in fly ash is not caused by physical adsorption of carbon in fly ash; calcium, magnesium and iron content of arsenic in fly ash and fly ash concentration in the same trend, chemistry deduction of calcium based materials in fly ash the adsorption is arsenic enrichment in fly ash.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X773

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

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本文編號(hào)：1341854