Study On Optimization Of Multi-Stage Removal Of Pollutants From Flue Gas Of Municipal Solid Waste Incineration

The flue gas of municipal solid waste incineration contains a variety of harmful pollutants,so measures need to be taken to control the emission.At present,the national emission standards are still implemented in China as a whole,but with the increasingly stringent environmental protection requirements,some areas have put forward stricter local standards,requiring waste incineration power plants to achieve ultra-low emissions.Considering that the limits stipulated in different local standards are different,this paper collates the relevant standard limits at home and abroad,and puts forward a unified recommended limit for ultra-low emission,combined with the mainstream flue gas purification process of domestic municipal solid waste incineration power plants.The feasible ultra-low emission transformation measures are further studied,and the ultra-low emission technical route of municipal solid waste incineration is further obtained.According to the research content of the recommended limit and technical route of ultra-low emission,this paper carries out the research on the selection of ultra-low emission process and operating condition optimization of a municipal solid waste incineration power plant in Guangdong.Specifically,for nitrogen oxides,SNCR+SCR multi-stage denitrification process is selected;for acid gas,a combined multi-stage deacidification process is selected among spray semi-dry deacidification,pipeline jet dry deacidification and NaOH wet deacidification;for flue gas pollutants such as dust,dioxins,heavy metals and their compounds,the existing process is selected to optimize the existing process.After determining the ultra-low emission process plan,based on the design parameters and actual operation data of the power plant,the pollutant removal costs under different operating conditions are calculated by establishing a mathematical model.This paper focuses on the impact of different technological operating conditions on the economic cost in the process of multi-stage removal.The main conclusions are as follows:(1)In the process of SNCR+SCR multistage denitrification,with the increase of SNCR denitrification share,SCR denitrification share decreases,and the total denitrification cost decreases at first and then increases.There is a minimum total cost.The denitrification of SNCR and SCR in the corresponding range is 3:7 respectively.The total denitrification efficiency of SCR and SCR is about 23%and 71%respectively.(2)For the semi-dry+dry multi-stage deacidizing process,the calcium-acid molar ratio of the semi-dry deacidizing process is 2.2 and that of the dry deacidizing process is 2.0,which can meet the ultra-low emission target and the lowest cost,but only in the case of the power plant.(3)Considering that the total deacidizing efficiency of semi-dry+dry multi-stage deacidizing process is low,it is suggested that semi-dry+ wet multi-stage deacidizing process should be selected under the condition of abundant building area and capital,which can regulate and control the deacidizing process more easily and has wider applicability.The mathematical model of municipal solid waste incineration power plant established in this paper can be used as a technical means to carry out economic research,and provides a reference for the selection of ultra-low emission process and the determination of multi-stage removal process operation parameters.