【摘要】：氮氧化物(NO_x)是大氣主要污染源之一,我國(guó)水泥行業(yè)NO_x排放量較大。選擇性非催化還原(SNCR)是一種廣泛應(yīng)用的脫硝技術(shù),在電站鍋爐上已運(yùn)用成熟,然而在水泥分解爐運(yùn)用效果沒(méi)有有效發(fā)揮,造成脫硝率低,氨水大量消耗,表明運(yùn)用于水泥分解爐SNCR煙氣脫硝過(guò)程比電站鍋爐更加復(fù)雜。水泥分解爐中存在高濃度水泥生料,包含活性較高的各種氧化物,可能對(duì)SNCR脫硝反應(yīng)過(guò)程造成影響。因此研究水泥生料對(duì)SNCR脫硝過(guò)程的影響對(duì)于研究提高水泥分解爐脫硝效率具有重要意義。通過(guò)脫硝率測(cè)試方法、原位漫反射紅外光譜(DRIFTS)、多項(xiàng)催化反應(yīng)動(dòng)力學(xué)對(duì)不同條件下水泥生料及其氧化物對(duì)SNCR脫硝過(guò)程的影響進(jìn)行研究,并通過(guò)脫硝率測(cè)試方法和XRD分析方法分析不同條件下煙氣組分對(duì)SNCR脫硝過(guò)程的影響。結(jié)果表明水泥生料吸附NH_3促使NH_3發(fā)生氧化反應(yīng)生成NO,抑制脫硝反應(yīng)。通過(guò)原位漫反射紅外光譜分析表明水泥生料表面主要發(fā)生NH_3被O_2氧化生成NO和H_2O的反應(yīng)。在不同氨氮比和溫度條件下CaO、Al_2O_3、Fe_2O_3與水泥生料作用相同也抑制脫硝反應(yīng),而SiO_2在NSR為1時(shí),會(huì)促進(jìn)脫硝反應(yīng),在NSR為1.5時(shí)抑制脫硝反應(yīng)。探討在O_2、CO_2、SO_2煙氣組分下水泥生料對(duì)SNCR脫硝過(guò)程的影響。結(jié)果表明有水泥生料時(shí),無(wú)O_2時(shí),水泥生料促進(jìn)NH_3和NO發(fā)生還原反應(yīng),脫硝率可達(dá)80%以上,O_2體積濃度的升高會(huì)促進(jìn)在水泥生料表面的NH_3脫氫,脫氫后NH_3會(huì)和O_2反應(yīng)生成NO,從而抑制脫硝反應(yīng),因此O_2越少越好。CO_2會(huì)抑制O_2在水泥生料表面的作用,從而抑制NO的生成,水泥分解爐內(nèi)CO_2體積濃度在20%-30%之間,20%的CO_2脫硝率較高。SO_2也會(huì)抑制水泥生料對(duì)脫硝反應(yīng)的影響,這是由于SO_2會(huì)和水泥生料中的CaO生成CaSO4。但SO_2還會(huì)和NH_3反應(yīng)生成(NH4)2SO3·H_2O和(NH4)2SO4,造成結(jié)皮堵塞,因此SO_2越少越好。通過(guò)對(duì)水泥生料及CaO、SiO_2、Al_2O_3、Fe_2O_3進(jìn)行多項(xiàng)催化反應(yīng)動(dòng)力學(xué)計(jì)算,擬合得到的脫硝反應(yīng)NO的出口濃度,且擬合相關(guān)度較好。分析動(dòng)力學(xué)參數(shù),表明在工業(yè)應(yīng)用中減小水泥顆粒比表面積和表觀密度或增大平均粒徑會(huì)使得SNCR脫硝反應(yīng)過(guò)程中生成的NO減少,提高脫硝率。對(duì)比擬合的水泥生料及CaO、SiO_2、Al_2O_3、Fe_2O_3表面NO的反應(yīng)速率,可以看出在750℃-970℃提高鋁率,在970℃-1100℃提高石灰飽和系數(shù),都可以減少NO的生成,提高脫硝效率。
[Abstract]:Nitrogen oxide (NO_x) is one of the main air pollution sources, and the NO_x emission of cement industry in China is large. Selective non-catalytic reduction of (SNCR) is a widely used denitrification technology, which has been used in power plant boilers. However, the application effect in cement calciner has not been effectively brought into play, resulting in low denitrification rate and large consumption of ammonia water. It shows that the process of flue gas denitrification in cement calciner SNCR is more complicated than that in power plant boiler. The existence of high concentration raw cement in cement calciner, including various oxides with high activity, may affect the denitrification process of SNCR. Therefore, it is of great significance to study the effect of cement raw material on the denitrification process of SNCR in order to improve the denitrification efficiency of cement calciner. The effect of in situ diffuse reflectance infrared spectroscopy (DRIFTS),) reaction kinetics on the denitrification of cement raw materials and their oxides on the denitrification process of SNCR was studied by the method of denitrification rate measurement and in situ diffuse reflectance infrared spectroscopy (DRIFTS),). The effects of flue gas components on the denitrification process of SNCR were analyzed by means of denitrification rate test method and XRD analysis method. The results showed that the adsorption of NH_3 from raw cement resulted in the oxidation of NH_3 and the formation of NO, to inhibit denitrification. In situ diffuse reflectance infrared spectroscopy analysis showed that NH_3 was oxidized by O _ 2 to NO and H _ 2O on the surface of raw cement. The denitrification reaction was also inhibited by CaO,Al_2O_3,Fe_2O_3 at different ammonia / nitrogen ratio and temperature, while the denitrification reaction was promoted by SiO_2 when NSR was 1, and the denitrification reaction was inhibited when NSR was 1.5. The effect of cement raw material on the denitrification process of SNCR was discussed in this paper. The results show that when there is no O _ 2, cement raw material can promote the reduction of NH_3 and NO, and the denitrification rate can reach more than 80%. The increase of O _ 2 volume concentration will promote the dehydrogenation of NH_3 on the surface of cement raw meal. After dehydrogenation, NH_3 reacts with O _ 2 to produce NO, to inhibit denitrification, so the less O _ 2 the better. CO_2 will inhibit the effect of O _ (2) on the surface of cement raw meal, thereby inhibiting the formation of NO. In cement calciner, the volume concentration of CO_2 is between 20% and 30%, and the denitrification rate of 20% CO_2 is higher. SO_2 can also inhibit the effect of cement raw material on denitrification, which is because SO_2 and CaO in raw cement produce CaSO4.. However, SO_2 also reacts with NH_3 to produce (NH4) 2SO3 H2O and (NH4) 2SO _ 4, resulting in blockage of crusts, so the less SO_2 the better. Through the kinetic calculation of several catalytic reactions of cement raw meal and CaO,SiO_2,Al_2O_3,Fe_2O_3, the outlet concentration of denitrification reaction NO was obtained by fitting, and the correlation degree was good. The kinetic parameters show that decreasing the specific surface area and apparent density of cement particles or increasing the average particle size in industrial application will reduce the NO generated in the process of SNCR denitrification and increase the denitrification rate. By comparing the reaction rate of NO on cement raw meal and CaO,SiO_2,Al_2O_3,Fe_2O_3 surface, it can be seen that increasing Al content at 750 鈩，

本文編號(hào)：2300875