络合吸收—生物还原两段式烟气脱硝系统的性能研究与参数优化
发布时间：2019-06-28 09:38
【摘要】：随着经济的发展和物质生活水平的不断提高,人民对环境质量的要求也越来越高。作为大气主要污染物之一的氮氧化物,会造成包括酸雨、雾霾、臭氧层破坏等在内的一系列环境问题,因此它的治理也日趋得到各级政府的高度重视,国家也为此出台了一系列政策法规来限制氮氧化物的排放。针对火电厂大气污染物的排放,要求新建锅炉(65t/h以上)的氮氧化物排放浓度不超过100mg/m3。针对工业锅炉烟气的排放,新建锅炉的氮氧化物排放限值提出了更高的要求,一般地区要求不高于300 mg/m3(特别地区要求不高于200 mg/m3)。因此,如何研究并开发具有脱销效率高,投资运行费用低的烟气脱硝技术一直是我国脱硝技术研发需要努力的方向。化学吸收-生物还原技术(CABR)是当前很有应用前景的生物脱硝技术。其原理是利用Fe(Ⅱ)EDTA吸收烟气中的NO,生成含氮络合物Fe(Ⅱ)EDTA-NO。生成Fe(Ⅱ)EDTA-NO需要通过脱氮菌将其还原为N2,并实现Fe(Ⅱ)EDTA的再生。由于烟气中一般含有一定量的氧气,部分Fe(Ⅱ)EDTA会被氧化为Fe(Ⅲ)EDTA,因此生物还原过程还包括铁还原菌将Fe(Ⅲ)EDTA还原为Fe(Ⅱ)EDTA。基于光照对铁还原过程的影响,本文开展了一部分光照对铁还原菌生物还原过程的影响研究,另外,为了让CABR技术能更好地运用于实际生产中,本文建立了一套新型的络合吸收-生物还原两段式脱硝系统,并对其挂膜时间和最大处理负荷与传统的一体式脱硝系统进行了对比研究。最后本文就如何从削减运行成本的角度来对两段式脱硝系统的运行参数优化进行了探讨。主要得到了以下一些结论:1.对比了光照培养与无光照培养下的Fe(Ⅲ)EDTA生物还原过程,无光照培养下的还原效率和还原速率更高。对造成两者生物还原效率的差异性的原因进行探究,发现EDTA降解不是导致光照条件下还原效率下降的主要原因。利用分子生物学技术对比研究了两者的微生物群落结构,高通量测序的结果显示,无光照和光照培养的菌群有了较大差异;无光照培养下,菌群中的优势菌种中包含三种具有铁还原能力的菌属Bacteroides,Klebsiella,Desulfovibrio,三者合计占全部菌群的47.09%。光照条件下,菌群中的优势菌种中只有一种具有铁还原能力的菌属Desulfitobacterium,占全部菌群的12.4%。2.采用混合菌对新的络合吸收-生物还原两段式脱硝系统进行挂膜,比传统的相继用铁还原菌和脱氮菌进行挂膜的时间更短。并且,新型的两段式脱硝体系抗氧气冲击能力已大大提升,且在同等烟气工况下处理负荷有较大提升。对高进气量下NO脱除效率不高的原因进行分析,确定主要原因是体系中的脱氮菌和铁还原菌的量不足。3.从削减运行成本的角度对新型的两段式脱硝系统的运行参数优化,确定葡萄糖采用连续补加方式优于间歇补加方式,可以有效提高NO脱除效率,降低体系运行成本;系统在初始Fe(Ⅲ)EDTA浓度高于4mM的情况下,出口NO的浓度可以维持在40ppm以下;降低初始Fe(Ⅲ)EDTA浓度可以减小Na2EDTA的损耗速率,从而降低为补充Na2EDTA损耗所需的运行成本。
[Abstract]:With the development of economy and the improvement of the level of material life, the people's demand for environmental quality is getting higher and higher. As one of the main pollutants in the atmosphere, the nitrogen oxide can cause a series of environmental problems, including acid rain, haze, ozone layer destruction, etc., and therefore, it has become more and more highly valued by the governments at all levels. The state has also introduced a series of policies and regulations to limit the discharge of nitrogen oxides. For the discharge of atmospheric pollutants in the thermal power plant, the nitrogen oxide emission concentration of the new boiler (above 65t/ h) is required to not exceed 100 mg/ m3. In the light of the emission of the flue gas of the industrial boiler, the nitrogen oxide emission limit of the new boiler is higher, and the requirements of the general area are not higher than 300 mg/ m3 (the requirements of the special area are not higher than 200 mg/ m3). Therefore, how to study and develop the flue gas denitration technology with the high efficiency of removing the pin and the low cost of the investment operation has been the direction of the research and development of the denitration technology in China. Chemical absorption-bioreduction technology (CABR) is a promising bio-denitrification technology. The principle of the invention is to utilize the Fe (II) EDTA to absorb the NO in the flue gas to generate the nitrogen-containing complex Fe (II) EDTA-NO. The generation of Fe (鈪，
本文编号：2507193
[Abstract]:With the development of economy and the improvement of the level of material life, the people's demand for environmental quality is getting higher and higher. As one of the main pollutants in the atmosphere, the nitrogen oxide can cause a series of environmental problems, including acid rain, haze, ozone layer destruction, etc., and therefore, it has become more and more highly valued by the governments at all levels. The state has also introduced a series of policies and regulations to limit the discharge of nitrogen oxides. For the discharge of atmospheric pollutants in the thermal power plant, the nitrogen oxide emission concentration of the new boiler (above 65t/ h) is required to not exceed 100 mg/ m3. In the light of the emission of the flue gas of the industrial boiler, the nitrogen oxide emission limit of the new boiler is higher, and the requirements of the general area are not higher than 300 mg/ m3 (the requirements of the special area are not higher than 200 mg/ m3). Therefore, how to study and develop the flue gas denitration technology with the high efficiency of removing the pin and the low cost of the investment operation has been the direction of the research and development of the denitration technology in China. Chemical absorption-bioreduction technology (CABR) is a promising bio-denitrification technology. The principle of the invention is to utilize the Fe (II) EDTA to absorb the NO in the flue gas to generate the nitrogen-containing complex Fe (II) EDTA-NO. The generation of Fe (鈪，
本文编号：2507193
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