SCR脱硝副产物硫酸氢铵特性研究:现状及发展

燃煤电厂加装以NH3和尿素为还原剂的脱硝装置后,还原剂NH3与烟气中的硫氧化物和水蒸气反应生成硫酸氢铵(ABS),ABS沉积会造成选择性催化还原法(SCR)脱硝效率降低、下游热力设备,如空气预热器(APH)和静电除尘器(ESP)堵塞等问题。ABS的生成和沉积与运行环境有关,但业内对ABS特性存在很多模糊认识。从ABS问题的出现入手,指出火电厂宽负荷脱硝情景下ABS影响加重的原因,对ABS在SCR反应器和空预器内生成、迁移和沉积的行为进行综述,总结了ABS的重要特性,如生成方式、生成温度、露点温度、挥发和沉积特性、分解特性等;并对ABS生成-迁移-挥发-分解-沉积的特性研究提出建议,指出了研究ABS迁移挥发特性对SCR和空预器整体影响的方向和发展趋势。

Status and development for characteristic of ammonium bisulfate as a by-product of SCR denitrification

After the denitrification device using NH 3 and urea as reducing agents is installed in a coal-fired power plant,ammonium bisulfate(ABS)is formed by the reaction of reducing agent NH 3 with sulfur oxides and water vapor in the flue gas.ABS deposition will lead to the reduction of selective catalytic reduction(SCR)and the blockage of downstream thermal equipment,such as air preheater(APH)and electrostatic precipitator(ESP).The formation and deposition of ABS are related to the operating environment,but there are some unclear understandings about the characteristics of ABS in the industry.Therefore,starting from the emergence of the ABS problem,and then the reason why the wide-load denitrification of thermal power plants causes the aggravation of the ABS influence was pointed out,and the behavior of ABS formation,migration and deposition in the SCR reactor and air preheater was reviewed subsequently.The significant characteristics of ABS,such as formation method,formation temperature,dew point temperature,volatilization and deposition characteristics and decomposition characteristics were summarized.Based on the above summary,suggestions for the study of the characteristics of ABS formation-migration-volatility-decomposition-deposition were put forward,and the direction and development trend of studying the overall influence of ABS migration and volatilization characteristics on SCR and air preheaterwas pointed out.