焦炉烟气脱硫脱硝工艺优化与设计

发布时间：2018-09-12 11:57

【摘要】：近年来,我国日趋严重的大气环境污染直接影响人们的健康和生活,因此,国家针对钢铁行业烟气中二氧化硫和氮氧化物的排放情况提出了明确标准。本文是在前人研究的基础上,通过分析国内典型的脱硫和脱硝工艺,综合马钢5号焦炉烟气的特点,提出4套脱硫脱硝工艺方案,经过工艺案例和实际案例分析对比,最终确定先SCR脱硝,再余热回收,最后湿法脱硫的工艺路线,通过物料守恒、热量守恒和设备选型论证,以及大型化工模拟软件Aspen Plus对该工艺中的主要参数进行模拟分析,探究了烟气流速、氨氮比对脱硝过程的影响和液气比、钙硫比对脱硫过程的影响,最后进行经济分析。模拟结果表明:(1)烟气流速为2~6m/s时,随着烟气流速的加快,NO的脱除率下降,但考虑到工艺实际运行效果,不采取最低流速,一般烟气流速在3.2~3.6m/s时,NO的脱除率可达到84.6%;(2)NH3/NO比值为1~1.5时,NO的脱除率随比值的增加而增加,当比值达到1.5时,NO的浓度几乎不变,为了防止过量的氨发生逃逸现象,一般取NH3/NO在1.05左右,此时,NO的脱除率可达到82.4%;(3)在脱硫工艺中,发现当液气比为0.8~2.2时,脱硫率随着溶液量的增加而增加,当液气比达到1.3时,脱硫率达到99.7%;(4)在脱硫工艺中,发现随着碳酸钙投加量的增加,脱硫率升高,钙硫比约为0.5时(此时每小时添加碳酸钙70kg),二氧化硫的流量由原来的1.37kmol/h变为0.023kmol/h,脱除率接近100%,上述二氧化硫完全溶于溶液,生成亚硫酸氢根离子和亚硫酸钙;而随着碳酸钙的增加,亚硫酸根离子与碳酸钙反应生成亚硫酸钙,导致亚硫酸根离子渐渐减少、亚硫酸钙渐渐增加。钙硫比为1时(此时每小时添加碳酸钙137kg),二水合亚硫酸钙的流量为1.33kmol/h,几乎所有的二氧化硫都转化为二水合亚硫酸钙,经氧化生成二水合硫酸钙。
[Abstract]:In recent years, the increasingly serious air pollution in China directly affects the health and life of people. Therefore, the state has put forward a clear standard for the emission of sulfur dioxide and nitrogen oxides in the flue gas of iron and steel industry. On the basis of previous studies, through analyzing the typical desulphurization and denitrification processes in China and synthesizing the characteristics of the flue gas of Masteel No.5 coke oven, four sets of desulphurization and denitrification technology schemes are put forward. The process route of first SCR denitrification, then waste heat recovery, and finally wet desulfurization was determined. The main parameters of the process were simulated and analyzed by means of material conservation, heat conservation and equipment selection demonstration, as well as large scale chemical simulation software Aspen Plus. The effects of flue gas flow rate, ammonia to nitrogen ratio on denitrification process, liquid-gas ratio and calcium to sulfur ratio on desulfurization process were investigated. Finally, economic analysis was carried out. The simulation results show that: (1) when the flue gas velocity is 2~6m/s, the removal rate of no decreases with the increase of flue gas velocity, but considering the actual operation effect of the process, the lowest flow rate is not adopted. The removal rate of no can reach 84.6 when the flow rate of flue gas is 3.2~3.6m/s. (2) when the ratio of NH3/NO is 1 ~ 1.5, the removal rate of no increases with the increase of ratio, and the concentration of no is almost unchanged when the ratio reaches 1.5. In order to prevent excessive ammonia from escaping, Generally, NH3/NO is about 1.05, and the removal rate of no can reach 82.4. (3) in the desulfurization process, it is found that when the ratio of liquid to gas is 0.8 ~ 2.2, the desulfurization rate increases with the increase of solution content, and when the ratio of liquid to gas reaches 1.3, the desulfurization rate reaches 99.7. (4) in the desulfurization process, It is found that with the increase of calcium carbonate dosage, the desulphurization rate increases. When the Ca / S ratio is about 0.5 (when calcium carbonate 70kg is added per hour), the flow rate of sulfur dioxide changes from the original 1.37kmol/h to 0.023 kmol / h, and the removal rate is close to 100. The above sulfur dioxide is completely dissolved in the solution. The formation of hydrogen sulfite ion and calcium sulfite, but with the increase of calcium carbonate, the reaction of sulfite ion with calcium carbonate to form calcium sulfite, which led to the decrease of sulfite ion and the increase of calcium sulfite. The ratio of calcium to sulfur is 1 (adding calcium carbonate 137kg per hour) and the flow rate of calcium sulfite dihydrate is 1.33 kmol / h. Almost all sulfur dioxide is converted into calcium sulfite dihydrate and oxidized to calcium sulfate dihydrate.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X784

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