乙醇胺(MEA)法燃煤电厂CO2捕集系统尾气二次污染分析

摘要

在某燃煤电厂用乙醇胺(MEA)作吸收剂进行了 CO2燃烧后捕集中试,并对系统的排放物进行了分析.吸收塔尾气和再生气用GASMET烟气监测系统进行在线监测,可得到二者组分及含量.结合电厂烟气、连续监测系统(CEMS)数据及实验室溶液分析,根据烟气数据对MEA的挥发及降解情况作了研究,比较了系统前后烟气组分的变化,讨论其尾气对环境是否造成二次污染.试验结果表明:MEA在吸收塔中主要发生氧化降解,在再生塔中主要发生热降解,且溶剂损耗主要来自氧化降解和挥发;降解的主要产物为 NH3和乙醛,二者在气体中含量变化情况与溶液中MEA浓度变化基本一致;预洗塔能除去原烟气中部分酸性气体.故CO2捕集系统可以进一步减少电厂净烟气中的原有污染物,但也会产生新的污染组分.新生成的污染物含量很少,符合国家标准,不会造成二次污染.%A pilot scale post-combustion CO2 capture test using mono ethanol amine(MEA)was conducted in a coal-fired power plant,and the exhaust gas was analyzed using GASMET analyzer. This research investigated MEA volatilization and degradation using GASMET data,CEMS (continuous emission monitoring system) data and laboratory analysis,compared the components of the flue gas before and after system,and discussed the effects of secondary pollution on environment. The results indicated that degradation of MEA mainly occurred in absorber and thermal degradation occurred in stripper,solvent loss was mainly caused by oxidative degradation and volatilization. The main degradation products were ammonia and acetaldehyde,the concentrations of which changed in accordance with MEA consumption rate in solution. And the pre-wash column could decrease acid gases. Therefore,the CO2 capture system could effectively reduce the original pollution from flue gas, even though new pollutions could be generated,considering the small amount (mush less than national standards),this system would not cause secondary pollution.