發(fā)布時(shí)間：2018-06-28 23:54

  本文選題：燃煤電廠 + 汞排放�。� 參考：《南京師范大學(xué)》2014年碩士論文

【摘要】：汞污染控制是繼燃煤電廠控制煙塵、SO2和NOX排放之后一個(gè)亟待解決的問題,本文依托環(huán)保部公益項(xiàng)目和國電集團(tuán)重點(diǎn)科技項(xiàng)目,對火電廠煙塵顆粒對汞的吸附與氧化機(jī)理,除塵器對煙氣中汞的脫除效果以及影響除塵器除汞的主要因素進(jìn)行了相關(guān)研究,為燃煤汞控制技術(shù)的進(jìn)一步發(fā)展打下基礎(chǔ)。 對15家燃煤電廠采集的煤、飛灰、爐渣及除塵器出口處煙氣中汞濃度進(jìn)行測試,并對電站各部分燃燒產(chǎn)物中汞分布情況及排放特性進(jìn)行分析,結(jié)果表明：測試電站的燃煤平均汞含量為0.171mg/kg,爐渣中平均汞量為0.0538mg/kg,飛灰中平均汞含量為0.223mg/kg。汞的質(zhì)量平衡在47.3%-106%之間,基本符合一般接受的70%-130%范圍。燃煤電廠汞的各排放環(huán)節(jié)中底渣中汞含量很低,基本可以忽略；飛灰中汞含量約占汞排放的13%；除塵器出口煙氣中HgP含量很低,可以忽略,除塵器出口煙氣中汞仍占很大比例。 基于固定床汞吸附機(jī)理實(shí)驗(yàn)系統(tǒng),研究了燃煤電廠飛灰與汞的相互作用機(jī)理,從吸附動(dòng)力學(xué)角度分析了汞在飛灰上的吸附過程,考察了煙氣中O2、HCl對飛灰氧化煙氣汞的影響,結(jié)果表明：1)飛灰吸附煙氣中Hg0在初始階段,呈現(xiàn)較快的吸附速率,該階段Hg0吸附速率與表面吸附有關(guān)；隨著吸附的進(jìn)行,表面活性位逐漸被占據(jù),Hg0需要擴(kuò)散到飛灰內(nèi)部孔隙中的活性位上發(fā)生吸附,吸附速率急劇下降,直至達(dá)到汞吸附平衡；2)吸附動(dòng)力學(xué)研究表明,準(zhǔn)二階吸附動(dòng)力學(xué)模型可以較好的預(yù)測Hg0在飛灰上的動(dòng)態(tài)吸附過程,說明化學(xué)吸附是Hg0在飛灰上吸附過程的速率控制步驟；3)在N2氣氛下,飛灰對汞有微弱的氧化作用,與飛灰表面存在大量氧化性官能團(tuán)有關(guān)。O2對飛灰氧化汞有微弱的促進(jìn)作用,HC1對飛灰氧化汞的促進(jìn)作用明顯。 基于燃煤電廠實(shí)測數(shù)據(jù)研究了燃煤電廠除塵器除汞效果,考察了燃燒方式(煤粉爐、循環(huán)流化床鍋爐)、除塵器的類型(靜電除塵器、布袋除塵器)、飛灰中的殘?zhí)�、選擇性催化還原(SCR)脫硝裝置對除塵器協(xié)同除汞效果的影響,結(jié)果表明：1)靜電除塵器除汞效率平均為37.4%,與煙氣中顆粒態(tài)汞含量關(guān)系明顯；CFB+ESP機(jī)組的協(xié)同脫汞效率高于PC+ESP機(jī)組的除汞效率；袋式除塵器的協(xié)同除汞效率平均為50%,優(yōu)于靜電除塵器的協(xié)同除汞效率；2)飛灰殘?zhí)苛繉︼w灰汞含量影響較為明顯,煤中氯含量和硫含量與除塵器的協(xié)同除汞效率關(guān)系不明顯；3)SCR反應(yīng)器后煙氣中飛灰汞含量有明顯提高,SCR通過氧化煙氣中Hg0為Hg2+,提高了飛灰對汞的吸附能力,提高了除塵器協(xié)同除汞的效果。
[Abstract]:Mercury pollution control is an urgent problem to be solved after coal-fired power plants control the emission of so _ 2 and no _ X. Based on the public welfare project of Ministry of Environmental Protection and the key scientific and technological projects of Guodian Group, the mechanism of adsorption and oxidation of mercury to dust particles in thermal power plants is discussed in this paper. The removal effect of mercury in flue gas and the main factors affecting the removal of mercury from flue gas were studied in order to lay a foundation for the further development of mercury control technology in coal combustion. The mercury concentration in the flue gas of coal, fly ash, slag and dust collector at the outlet of 15 coal-fired power plants was measured, and the distribution and emission characteristics of mercury in the combustion products of each part of the power plant were analyzed. The results show that the average mercury content in coal combustion is 0.171 mg / kg, the average mercury content in slag is 0.0538 mg / kg, and the average mercury content in fly ash is 0.223 mg / kg. The mass balance of mercury is between 47.3% and 106%, which basically conforms to the generally accepted range of 70%-130%. The mercury content in bottom slag of coal-fired power plant is very low, which can be neglected basically; the mercury content in fly ash accounts for about 13% of mercury emission; the HGP content in outlet flue gas of dust collector is very low, which can be ignored, and the mercury content in flue gas of dust collector outlet still accounts for a large proportion. Based on the experimental system of fixed-bed mercury adsorption mechanism, the interaction mechanism between fly ash and mercury in coal-fired power plants was studied. The adsorption process of mercury on fly ash was analyzed from the point of view of adsorption kinetics, and the effect of O _ 2H _ 2HCl in flue gas on the oxidation of mercury in fly ash was investigated. The results showed that the adsorption rate of Hg _ 0 in flue gas was faster at the initial stage, and the adsorption rate of Hg _ 0 was related to the surface adsorption. The surface active sites gradually occupied by Hg0 need to diffuse to the active sites in the pores of fly ash, and the adsorption rate decreases sharply until the mercury adsorption equilibrium is reached. The quasi-second-order adsorption kinetic model can predict the dynamic adsorption process of Hg _ 0 on fly ash, which indicates that chemical adsorption is the rate control step of Hg _ 0 adsorption on fly ash. (3) in N2 atmosphere, fly ash has weak oxidation of mercury. There are a lot of oxidizing functional groups on the surface of fly ash. O2 has a weak promoting effect on mercury oxide in fly ash. HC1 can promote mercury oxide in fly ash obviously. Based on the measured data of coal-fired power plant, the mercury removal effect of dust remover in coal-fired power plant was studied. The combustion mode (pulverized coal boiler, circulating fluidized bed boiler), the type of dust collector (electrostatic precipitator, bag dust collector), and the residual carbon in fly ash were investigated. The effect of selective catalytic reduction (SCR) denitrification device on the synergistic mercury removal efficiency of dust precipitator was investigated. The results showed that the average removal efficiency of mercury in electrostatic precipitator was 37.4, which was obviously related to the content of mercury particles in flue gas. The synergistic mercury removal efficiency of CFB ESP is higher than that of PC ESP, and the average efficiency of bag dust collector is 50, which is better than that of electrostatic precipitator. There is no obvious relationship between chlorine content and sulfur content in coal and synergistic mercury removal efficiency of precipitator. 3) Mercury content in fly ash in SCR reactor can obviously increase Hg content in flue gas by oxidation of Hg _ 0 to Hg _ 2, which improves the adsorption ability of fly ash to mercury. The synergistic mercury removal effect of dust collector is improved.
【學(xué)位授予單位】：南京師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：X773

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本文編號：2079907