本文選題：燃煤 + 脫汞　； 參考：《華北電力大學》2015年碩士論文

【摘要】：燃煤汞污染是繼粉塵、NO_x和SO_2后又一備受關(guān)注的大氣污染物。目前并沒有一種應用成熟的燃煤煙氣脫汞技術(shù),在各種燃煤煙氣汞污染控制技術(shù)中,利用現(xiàn)有空氣污染物控制裝置實現(xiàn)汞的聯(lián)合脫除是一種經(jīng)濟有效的方法。汞在煙氣有3種不同形態(tài)(Hg~0、Hg~(2+)、Hg~P),現(xiàn)有空氣污染物控制裝置脫汞效率受煙氣中汞的形態(tài)影響很大。大多數(shù)的Hg~P能隨著飛灰被電除塵器(ESP)和布袋除塵器捕獲;二價汞離子具有較好的水溶性,能夠被濕法脫硫裝置捕集;Hg~0由于其在低溫下的弱氧化活性以及在高溫下較高的熱力學穩(wěn)定性,Hg~0很難被現(xiàn)有的空氣污染控制裝置去除。因此降低其單質(zhì)汞的比例,使煙氣中的單質(zhì)汞盡可能的氧化成易溶于水的二價汞離子,是利用現(xiàn)有污染物控制裝置脫汞技術(shù)的關(guān)鍵所在。SCR催化劑具有將單質(zhì)汞氧化成二價汞離子的能力,但受煙氣成分等因素的影響,傳統(tǒng)SCR催化劑氧化單質(zhì)汞的效率不高。研究SCR催化劑對單質(zhì)汞的催化氧化特性,強化其對單質(zhì)汞的催化氧化效率,將很好的解決燃煤電廠汞污染控制問題。本文首先在自建的SCR催化劑催化氧化單質(zhì)汞實驗臺上,對傳統(tǒng)SCR催化劑催化氧化單質(zhì)汞的特性進行了實驗研究,研究了反應溫度、氨氮比和SO_2含量等因素對傳統(tǒng)SCR催化劑對單質(zhì)汞催化氧化的影響。實驗結(jié)果表明,在一定程度上升高溫度能夠促進單質(zhì)汞的氧化,但是溫度過高會降低單質(zhì)汞的轉(zhuǎn)化率;噴氨量的增加會明顯抑制單質(zhì)汞的氧化,在氨氮比為1.5時,反應裝置出口Hg~(2+）濃度幾乎為零;較高濃度的SO_2條件下,單質(zhì)汞的氧化效率略有提高,但是效果并不明顯。在上述實驗的基礎上,本文采用浸漬法對傳統(tǒng)SCR催化劑進行改性,并對改性SCR催化劑對單質(zhì)汞的催化氧化效果進行了實驗研究,研究了改性SCR催化劑在不同溫度,不同SO_2、NH_3等氣體含量的條件下對單質(zhì)汞的催化氧化規(guī)律,并與傳統(tǒng)SCR催化劑進行了對比。實驗結(jié)果表明,在不同溫度條件下兩種改性SCR催化劑比傳統(tǒng)SCR催化劑對單質(zhì)汞的氧化效率均有明顯的提升,氧化效率均在90%以上,溫度窗口較寬;改性SCR催化劑對單質(zhì)汞的氧化效率受噴氨量的影響不大,較傳統(tǒng)SCR催化劑有明顯的提升,氧化效率均在90%以上;在不同濃度的SO_2條件下,改性SCR催化劑氧化單質(zhì)汞的效率均能保持在90%左右,研究結(jié)果為燃煤電廠利用現(xiàn)有空氣污染控制裝置同時脫汞提供了理論基礎。
[Abstract]:Mercury pollution from coal combustion is one of the most concerned air pollutants after dust nox and SO_2. At present, there is no mature technology for mercury removal from coal-fired flue gas. Among all kinds of mercury pollution control technologies in coal-fired flue gas, it is an economical and effective method to realize mercury removal by using existing air pollutant control devices. There are three different forms of mercury in the flue gas. The mercury removal efficiency of the existing air pollutant control devices is greatly affected by the mercury species in the flue gas. Most of the Hg~P can be captured with the fly ash by the ESP) and the bag dust collector, and the divalent mercury ions have good water solubility. Because of its weak oxidation activity at low temperature and high thermodynamic stability at high temperature, it is difficult to remove HgC0 from the existing air pollution control devices. Thus reducing the proportion of its elemental mercury, so that the elemental mercury in the flue gas is oxidized as much as possible into water-soluble divalent mercury ions, SCR catalyst has the ability to oxidize elemental mercury to divalent mercury ion, but the traditional SCR catalyst is not efficient in the oxidation of elemental mercury due to the influence of flue gas composition and other factors. The study on the catalytic oxidation characteristics of SCR catalyst for elemental mercury and the enhancement of its catalytic oxidation efficiency will solve the problem of mercury pollution control in coal-fired power plants. In this paper, the catalytic oxidation of elemental mercury with SCR catalyst was studied on a self-built experimental bench, and the reaction temperature was studied. Effects of NH _ 3-N ratio and SO_2 content on the Catalytic Oxidation of Mercury over conventional SCR Catalysts. The experimental results show that increasing temperature can promote the oxidation of elemental mercury to some extent, but too high temperature will reduce the conversion rate of elemental mercury, and the increase of ammonia injection will obviously inhibit the oxidation of elemental mercury, when the ratio of ammonia to nitrogen is 1.5, The concentration of Hg~(2 at the outlet of the reactor was almost zero, and the oxidation efficiency of elemental mercury was slightly improved under the condition of higher SO_2 concentration, but the effect was not obvious. On the basis of the above experiments, the traditional SCR catalyst was modified by impregnation method, and the catalytic oxidation effect of modified SCR catalyst on elemental mercury was studied experimentally, and the modified SCR catalyst at different temperatures was studied. The catalytic oxidation of mercury was studied under the conditions of different contents of so _ 2H _ 3 and NH _ 3, and the results were compared with those of traditional SCR catalysts. The experimental results show that the oxidation efficiency of the two modified SCR catalysts is obviously higher than that of the traditional SCR catalyst at different temperature, the oxidation efficiency is above 90%, and the temperature window is wide. The modified SCR catalyst has little effect on the oxidation efficiency of elemental mercury by ammonia injection, and the oxidation efficiency of the modified SCR catalyst is above 90% compared with that of the traditional SCR catalyst, and the oxidation efficiency of the modified SCR catalyst is above 90% under the conditions of different concentration of SO_2. The efficiency of oxidation of elemental mercury by modified SCR catalyst is about 90%. The results provide a theoretical basis for simultaneous mercury removal by using existing air pollution control devices in coal-fired power plants.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X701;X773

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