本文選題：氧化脫汞　切入點(diǎn)：等離子體　出處：《華北電力大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：汞由于其劇毒、高揮發(fā)性以及在生物鏈中能夠富集等特性,危害人類的身體健康。燃煤電廠作為最大的人為汞排放源,如何安全、高效、經(jīng)濟(jì)的控制燃煤汞排放成為目前研究的熱點(diǎn)。低溫等離子體氧化脫汞技術(shù)以其適應(yīng)性強(qiáng),能夠多種污染物聯(lián)合控制的特點(diǎn)引起了廣泛關(guān)注。本文利用等離子體結(jié)合濕法過程氧化煙氣中的單質(zhì)汞。采用介質(zhì)阻擋放電(DBD)作為產(chǎn)生等離子體的方法,配比含汞的模擬煙氣依次連續(xù)通入DBD反應(yīng)器和濕法鼓泡反應(yīng)器內(nèi)反應(yīng),考察了含氧量、電壓、溫度、濕法過程、停留時(shí)間以及煙氣成分變化等因素對氧化脫汞的影響。主要內(nèi)容如下:在等離子體氧化單質(zhì)汞過程中O原子和O3起主導(dǎo)作用,提高O2體積分?jǐn)?shù)能夠增加O原子和O3的含量,促進(jìn)Hg0的氧化。實(shí)驗(yàn)中當(dāng)氧含量為30%時(shí),最高能達(dá)到97%的汞氧化效率。在放電電壓小于10k V時(shí)升高電壓能夠增加單質(zhì)汞的氧化效率,但電壓過高時(shí)汞氧化效率反而會(huì)下降。系統(tǒng)中產(chǎn)生的活性氧化物質(zhì)對于只有ppb濃度的汞而言是遠(yuǎn)遠(yuǎn)過量的,增加單質(zhì)汞濃度,會(huì)增大汞原子與活性自由基間的碰撞幾率,所以單質(zhì)汞氧化效率會(huì)升高。模擬煙氣溫度升高能夠使折合場強(qiáng)增大和化學(xué)反應(yīng)速率增加,會(huì)促進(jìn)單質(zhì)汞氧化,在放電電壓為6k V,氧含量為10%的條件下,溫度從室溫升高到403K時(shí),單質(zhì)汞氧化效率從61%增大到92%。在DBD反應(yīng)器后添加濕法過程能夠明顯促進(jìn)汞的氧化。在8kV放電條件下,添加濕法過程后Hg0的氧化效率從42.64%增加到81.48%,提高了近一倍。由于活性物質(zhì)相對于單質(zhì)汞是過量的,通過增加停留時(shí)間,也能夠提高汞氧化效率。煙氣成分對DBD結(jié)合濕法過程氧化脫汞有影響,NO會(huì)競爭消耗臭氧,對單質(zhì)汞的氧化有明顯的抑制作用,當(dāng)加入750ppm的NO,有無濕法過程均只有12%的Hg0被氧化。而SO2在系統(tǒng)內(nèi)會(huì)被氧化成SO3能夠促進(jìn)汞的氧化。CO2會(huì)輕微抑制等離子體對單質(zhì)汞的氧化過程,但是CO2能夠穩(wěn)定放電,可以削弱高壓放電時(shí)的負(fù)面效果。
[Abstract]:Mercury is harmful to human health because of its high toxicity, high volatility and ability to enrich in biological chain. As the largest anthropogenic mercury emission source, coal-fired power plants are safe and efficient. Economic control of mercury emissions from coal combustion has become a hot research topic. Low temperature plasma oxidation decarbonization technology has strong adaptability. In this paper, plasma combined with wet process is used to oxidize elemental mercury in flue gas. Dielectric barrier discharge (DBD) is used as the method to produce plasma. The simulated flue gas containing mercury was successively passed into the DBD reactor and the wet bubbling reactor. The oxygen content, voltage, temperature and wet process were investigated. The main contents are as follows: O atom and O 3 play a leading role in the process of plasma oxidation of elemental mercury, increasing the volume fraction of O 2 can increase the content of O atom and O 3. In the experiment, the maximum oxidation efficiency of mercury is 97% when the oxygen content is 30. When the discharge voltage is less than 10 kV, increasing the voltage can increase the oxidation efficiency of elemental mercury. However, when the voltage is too high, the efficiency of mercury oxidation will decrease. The active oxidized substance produced in the system is far excess for mercury with only ppb concentration, and increasing the concentration of elemental mercury increases the probability of collision between mercury atoms and active free radicals. So the oxidation efficiency of elemental mercury will increase, and the simulated flue gas temperature will increase the field strength and chemical reaction rate, which will promote the oxidation of mercury, at the discharge voltage of 6kV and the oxygen content of 10%. When the temperature increases from room temperature to 403K, the oxidation efficiency of elemental mercury increases from 61% to 9220.The wet process of adding mercury after DBD reactor can obviously promote the oxidation of mercury. After adding wet process, the oxidation efficiency of Hg0 increased from 42.64% to 81.48, which is nearly doubled. Because the active substance is excessive relative to elemental mercury, by increasing the residence time, The effect of flue gas composition on oxidative decarbonization of DBD combined with wet process will result in no competition for ozone depletion and obvious inhibition on the oxidation of elemental mercury. When 750ppm of no was added, only 12% of the Hg0 was oxidized in the wet process, while SO2 was oxidized to SO3 in the system, which could promote the oxidation of mercury. CO2 could slightly inhibit the oxidation of mercury by plasma, but CO2 could discharge steadily. It can weaken the negative effect of high voltage discharge.
【學(xué)位授予單位】：華北電力大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X773;O53

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 易秋;薛志鋼;宋凱;馬京華;杜謹(jǐn)宏;劉妍;;燃煤電廠煙氣重金屬排放與控制研究[J];環(huán)境與可持續(xù)發(fā)展;2015年05期

2 惠，

本文編號(hào)：1610924