水泥生料对SNCR脱硝过程的影响研究
发布时间：2018-10-30 18:54
【摘要】：氮氧化物(NO_x)是大气主要污染源之一,我国水泥行业NO_x排放量较大。选择性非催化还原(SNCR)是一种广泛应用的脱硝技术,在电站锅炉上已运用成熟,然而在水泥分解炉运用效果没有有效发挥,造成脱硝率低,氨水大量消耗,表明运用于水泥分解炉SNCR烟气脱硝过程比电站锅炉更加复杂。水泥分解炉中存在高浓度水泥生料,包含活性较高的各种氧化物,可能对SNCR脱硝反应过程造成影响。因此研究水泥生料对SNCR脱硝过程的影响对于研究提高水泥分解炉脱硝效率具有重要意义。通过脱硝率测试方法、原位漫反射红外光谱(DRIFTS)、多项催化反应动力学对不同条件下水泥生料及其氧化物对SNCR脱硝过程的影响进行研究,并通过脱硝率测试方法和XRD分析方法分析不同条件下烟气组分对SNCR脱硝过程的影响。结果表明水泥生料吸附NH_3促使NH_3发生氧化反应生成NO,抑制脱硝反应。通过原位漫反射红外光谱分析表明水泥生料表面主要发生NH_3被O_2氧化生成NO和H_2O的反应。在不同氨氮比和温度条件下CaO、Al_2O_3、Fe_2O_3与水泥生料作用相同也抑制脱硝反应,而SiO_2在NSR为1时,会促进脱硝反应,在NSR为1.5时抑制脱硝反应。探讨在O_2、CO_2、SO_2烟气组分下水泥生料对SNCR脱硝过程的影响。结果表明有水泥生料时,无O_2时,水泥生料促进NH_3和NO发生还原反应,脱硝率可达80%以上,O_2体积浓度的升高会促进在水泥生料表面的NH_3脱氢,脱氢后NH_3会和O_2反应生成NO,从而抑制脱硝反应,因此O_2越少越好。CO_2会抑制O_2在水泥生料表面的作用,从而抑制NO的生成,水泥分解炉内CO_2体积浓度在20%-30%之间,20%的CO_2脱硝率较高。SO_2也会抑制水泥生料对脱硝反应的影响,这是由于SO_2会和水泥生料中的CaO生成CaSO4。但SO_2还会和NH_3反应生成(NH4)2SO3·H_2O和(NH4)2SO4,造成结皮堵塞,因此SO_2越少越好。通过对水泥生料及CaO、SiO_2、Al_2O_3、Fe_2O_3进行多项催化反应动力学计算,拟合得到的脱硝反应NO的出口浓度,且拟合相关度较好。分析动力学参数,表明在工业应用中减小水泥颗粒比表面积和表观密度或增大平均粒径会使得SNCR脱硝反应过程中生成的NO减少,提高脱硝率。对比拟合的水泥生料及CaO、SiO_2、Al_2O_3、Fe_2O_3表面NO的反应速率,可以看出在750℃-970℃提高铝率,在970℃-1100℃提高石灰饱和系数,都可以减少NO的生成,提高脱硝效率。
[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，
本文编号：2300875
[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，
本文编号：2300875
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