本文關(guān)鍵詞：濕法脫硫溶液及脫硫石膏中汞的穩(wěn)定性研究　出處：《華中科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 濕法脫硫溶液 脫硫石膏 汞 再釋放 穩(wěn)定

【摘要】：我國是世界上煤炭消費量最大的國家,燃煤所帶來的汞污染問題日益突出。燃煤電廠是最大人為汞排放源之一,加強燃煤電廠汞排放控制十分必要。目前我國燃煤電廠主要利用現(xiàn)有除塵設(shè)備對汞進(jìn)行聯(lián)合脫除。濕法脫硫系統(tǒng)作為燃煤電廠主要除塵設(shè)備之一,在脫除SO2的同時能有效去除煙氣中的Hg2+。然而被濕法脫硫系統(tǒng)吸收的汞并不穩(wěn)定,脫硫液中的汞可能存在二次釋放,而進(jìn)入脫硫石膏中的汞可能在石膏資源化利用過程中再次轉(zhuǎn)移到環(huán)境中。因此對濕法脫硫系統(tǒng)溶液及脫硫石膏中汞的穩(wěn)定進(jìn)行研究具有重要意義。由于還原性離子的存在,濕法脫硫溶液中的Hg2+會被還原成Hg0而釋放出來。相關(guān)研究發(fā)現(xiàn)向脫硫溶液中加入穩(wěn)定劑能夠有效將溶液中的Hg2+捕集沉淀下來,但是濕法脫硫系統(tǒng)相關(guān)運行參數(shù)對穩(wěn)定劑的穩(wěn)定效果的影響尚不明確。因此,本文通過實驗研究,考察了添加量,溫度,pH,Cl-對Na2S和DTCR-3兩種穩(wěn)定劑對模擬電廠濕法脫硫溶液中Hg2+穩(wěn)定效果的影響,發(fā)現(xiàn)兩種穩(wěn)定劑都能有效捕集溶液中的Hg2+,且最佳添加量都為2.0倍摩爾計量比,溫度和pH的升高會提高兩種穩(wěn)定劑對Hg2+捕集沉淀效果,但Cl-濃度的增加會抑制兩種穩(wěn)定劑對Hg2+的捕集沉淀。脫硫石膏是濕法脫硫系統(tǒng)的主要產(chǎn)物,其在加工利用過程中會經(jīng)過加熱工序,因此會導(dǎo)致石膏中的汞重新釋放出來。本文通過程序升溫?zé)峤鈱嶒瀸Z、XY、GD三個電廠脫硫石膏中汞的化物的熱分解特性進(jìn)行了研究,并初步判斷了脫硫石膏中汞的化合物形態(tài)。發(fā)現(xiàn)在加熱過程中脫硫石膏中汞的釋放區(qū)間主要在200℃~500℃,脫硫石膏中汞的化合物主要是HgS(紅)和HgS(黑),升溫速率的變化不會改變汞的釋放溫度區(qū)間及峰值溫度。升溫速率的降低及氧氣的存在會導(dǎo)致脫硫石膏在加熱過程中Hg0的釋放濃度降低。此外,存在于脫硫石膏中的有害元素會在雨水、地下水等浸潤作用下轉(zhuǎn)移到周圍環(huán)境中造成污染。本文使用水平振蕩法對三種電廠石膏進(jìn)行了毒性鑒別實驗和有害元素浸出特性實驗。實驗結(jié)果表明,三種電廠脫硫石膏中各有害元素的浸出濃度都遠(yuǎn)低于相關(guān)規(guī)定中的濃度限值。三種電廠脫硫石膏中各有害元素的浸出率在8h~16h時達(dá)到最大值。Pb、As、Cr、Se這四種元素的浸出率都隨液固比的增大而逐漸增大。而Hg的浸出率會隨液固比的增大而減小。對于Pb、As、Cr、Se這四種元素,主要以氧化物的形式存在于脫硫石膏中,主要在酸性條件下溶解,因此pH的升高都會明顯降低其浸出率。
[Abstract]:China has the largest coal consumption in the world, and the mercury pollution caused by coal burning is increasingly prominent, and coal-fired power plant is one of the largest anthropogenic mercury emission sources. It is necessary to strengthen mercury emission control in coal-fired power plants. At present, coal-fired power plants in China mainly use the existing dust removal equipment for combined removal of mercury. Wet desulfurization system as one of the main dust removal equipment in coal-fired power plants. The removal of SO2 can effectively remove Hg2 from flue gas. However, the mercury absorbed by wet desulfurization system is not stable, and there may be secondary release of mercury in desulfurization solution. Therefore, it is important to study the stability of mercury in wet desulfurization system and desulphurized gypsum. The existence of son. Hg2 in wet desulfurization solution will be reduced to Hg0 and released. It is found that adding stabilizer to desulfurization solution can effectively capture and precipitate Hg2 in the solution. However, the influence of the operation parameters of wet desulfurization system on the stabilization effect of stabilizer is not clear. Therefore, through the experimental study, the addition amount, temperature and pH value of the stabilizer are investigated. The effect of CL- on Na2S and DTCR-3 stabilizers on the stability of Hg2 in wet desulfurization solution of power plant is simulated. It is found that both stabilizers can effectively capture Hg2 in the solution. And the optimum addition amount is 2.0 times molar ratio, the increase of temperature and pH will improve the effect of two stabilizers on Hg2 precipitation. However, the increase of Cl-concentration will inhibit the precipitation of Hg2 by two stabilizers. Desulfurization gypsum is the main product of wet desulphurization system, and it will go through heating process in the process of utilization. In this paper, the pyrolysis characteristics of mercury compounds in gypsum desulfurization gypsum in three power plants are studied by programmed pyrolysis experiments. It is found that the release range of mercury in desulfurized gypsum is mainly at 200 鈩，

本文編號：1440075