發(fā)布時(shí)間：2019-03-23 18:03

【摘要】：燃煤產(chǎn)生的煙氣汞具有很強(qiáng)的毒性,對(duì)人類的生存環(huán)境和身體健康造成了極大的危害,在全球范圍內(nèi)引起了廣泛的關(guān)注。改進(jìn)現(xiàn)有的濕法煙氣脫硫裝置(Wet Flue Gas Desulfurization,WFGD)脫汞和活性炭噴射(Activated carbon injection,ACI)脫汞是目前極具發(fā)展前景的燃煤煙氣汞控制技術(shù)。本文篩選了三種綠色環(huán)保氧化劑(類芬頓試劑過硫酸銨和高鐵酸鉀),并且在噴淋塔和固定床兩種常見反應(yīng)器上分別研究了三種氧化劑氧化脫除燃煤煙氣單質(zhì)汞的基礎(chǔ)理論問題。主要的研究內(nèi)容和研究成果可分為如下三個(gè)部分:在噴淋塔反應(yīng)器中,研究了溶液pH、反應(yīng)溫度、液-氣比、H_2O_2濃度、Fe~(3+)濃度、Cu~(2+)濃度、初始汞濃度、NO濃度和SO_2濃度等工藝參數(shù)對(duì)類芬頓試劑脫汞性能的影響,并通過離子色譜、液相熒光光譜儀和電子自旋共振波譜儀測(cè)定了溶液中的液相反應(yīng)產(chǎn)物和自由基,推測(cè)出煙氣汞脫除的最終產(chǎn)物以及脫除路徑。研究結(jié)果表明:(1)隨著H_2O_2濃度、Fe~(3+)濃度、Cu~(2+)濃度和液-氣比的增加,脫汞效率有了顯著提升。然而,隨著溶液pH、NO濃度和SO_2濃度的增加,脫汞效率大幅度下降。初始汞濃度和反應(yīng)溫度的變化對(duì)脫汞效率的影響很小。(2)羥基自由基氧化是汞脫除的主要路徑,過氧化氫氧化是汞脫除的次要路徑。在噴淋塔反應(yīng)器中,研究了反應(yīng)溫度、(NH_4)_2S_2O_8濃度、液-氣比、汞濃度、溶液pH、urea濃度和SO_2濃度等工藝參數(shù)對(duì)高溫活化過硫酸銨氧化脫除單質(zhì)汞的影響,并通過離子色譜、紫外分光光度法、液相熒光光譜儀和液質(zhì)聯(lián)用儀測(cè)定了溶液中的液相反應(yīng)產(chǎn)物和自由基,推測(cè)出煙氣汞脫除的最終產(chǎn)物以及脫除路徑。研究結(jié)果表明:(1)隨著反應(yīng)溫度、(NH_4)_2S_2O_8濃度和液-氣比的增加,脫汞效率有了顯著提升。然而,隨著溶液pH和urea濃度的增加,脫汞效率反而大幅度降低。初始汞濃度和SO_2濃度的改變對(duì)脫汞效率的影響很小。(2)煙氣中的單質(zhì)汞主要是被溶液中的S_2O_8~(2-)、·OH和SO_4~-氧化成二價(jià)汞的方式脫除,且二價(jià)汞是最終產(chǎn)物。利用高溫?zé)峤夂突瘜W(xué)改性的方法制備了麥稈焦吸附劑,并在固定床反應(yīng)器中,研究了K_2FeO_4濃度、初始汞濃度、O_2濃度、NO濃度、SO_2濃度以及反應(yīng)溫度等工藝參數(shù)對(duì)該吸附劑脫汞性能的影響,研究結(jié)果表明:(1)改性后的麥稈焦的比表面積和孔隙結(jié)構(gòu)均有了明顯的改善。改性焦的表面成功負(fù)載了新的活性劑組分Fe_2O_3和K_2FeO_4。(2)隨著O_2濃度的增加,脫汞效率得到提升。然而,隨著初始汞濃度增加,脫汞效率反而下降。當(dāng)煙氣中加入NO時(shí),脫汞效率上升。然而,當(dāng)繼續(xù)向煙氣中加入SO_2時(shí),脫汞效率反而下降。隨著反應(yīng)溫度的增加,脫汞效率先提高后降低。
[Abstract]:The smoke mercury produced by coal combustion has strong toxicity, which has caused great harm to the living environment and health of human beings, and has attracted wide attention all over the world. The improvement of the existing wet flue gas desulfurization unit (Wet Flue Gas Desulfurization,WFGD) and activated carbon injection (Activated carbon injection,ACI) for mercury removal are promising technologies for mercury control in coal-fired flue gas. In this paper, three kinds of environmental protection oxidants (Fenton-like reagent) were selected. Ammonium persulfate and potassium ferrate), and the basic theory of removing mercury from coal-fired flue gas by oxidation of three oxidants were studied in two common reactors: spray column and fixed bed reactor. The main research contents and achievements can be divided into three parts as follows: in the spray column reactor, the solution pH, reaction temperature, liquid-gas ratio, H_2O_2 concentration, Fe~ (3) concentration, Cu~ (2) concentration and initial mercury concentration were studied. The effects of technological parameters such as NO concentration and SO_2 concentration on the performance of Fenton-like reagent for mercury removal were studied. The reaction products and free radicals in the solution were determined by ion chromatography, liquid phase fluorescence spectrometer and electron spin resonance spectroscopy. The final products of mercury removal from flue gas and the removal path were deduced. The results showed that: (1) with the increase of H_2O_2 concentration, Fe~ (3) concentration, Cu~ (2) concentration and liquid-gas ratio, the mercury removal efficiency increased significantly. However, with the increase of the concentration of pH,NO and SO_2, the efficiency of mercury removal decreased greatly. The change of initial mercury concentration and reaction temperature has little effect on the efficiency of mercury removal. (2) hydroxyl radical oxidation is the main pathway for mercury removal, and hydrogen peroxide oxidation is the secondary pathway for mercury removal. The reaction temperature, (NH_4) _ 2S_2O_8 concentration, liquid-gas ratio, mercury concentration and solution pH, were studied in a spray column reactor. The effects of technological parameters such as urea concentration and SO_2 concentration on the removal of mercury by activated ammonium persulfate oxidation at high temperature were studied by ion chromatography and ultraviolet spectrophotometry. Liquid phase reaction products and free radicals were determined by liquid phase fluorescence spectrometer and mass spectrometry. The final products and removal path of mercury removal from flue gas were deduced. The results showed that: (1) with the increase of reaction temperature, the concentration of (NH_4) _ 2S_2O_8 and the ratio of liquid to gas, the efficiency of mercury removal increased significantly. However, with the increase of the concentration of pH and urea, the efficiency of mercury removal decreased greatly. The change of initial mercury concentration and SO_2 concentration has little effect on the efficiency of mercury removal. (2) the primary mercury in flue gas is mainly removed by oxidation of Sz _ 2O _ 2O _ 8 ~ (2 -), OH) and SO_4~- into divalent mercury in the solution. And divalent mercury is the final product. The sorbents for wheat stalk coke were prepared by high temperature pyrolysis and chemical modification. The K_2FeO_4 concentration, initial mercury concentration, O ~ (2 +) concentration and NO concentration were studied in a fixed-bed reactor. The effects of SO_2 concentration and reaction temperature on the mercury removal performance of the adsorbent were studied. The results showed that: (1) the specific surface area and pore structure of the modified wheat stalk coke were obviously improved. The surface of the modified coke was successfully loaded with new active agent Fe_2O_3 and K _ 2O _ 2 FeO _ 4. (2) the efficiency of mercury removal was improved with the increase of O ~ (2 +) concentration. However, the efficiency of mercury removal decreases with the increase of initial mercury concentration. When NO was added to the flue gas, the mercury removal efficiency increased. However, when SO_ 2 was added to the flue gas, the mercury removal efficiency decreased instead. With the increase of reaction temperature, the mercury removal efficiency first increased and then decreased.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X701

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