Prediction Of NO_x Production And Emission And Source Control Methods Of MSW Incineration Plant

In recent years,with the rapid growth of the scale of waste incineration,the emission limit of incineration flue gas pollutants has been further tightened.As the main pollutant of photochemical smog and greenhouse effect,NO_x has attracted more attention.Many domestic cities have issued more stringent local standards than the national standard to limit NO_x emissions.The most common way to further reduce NO_x emissions is to increase the dosage of SNCR denitration agent,but it will also increase the risk of ammonia escape.In this context,it is of great significance to explore a NO_x source prevention and control method.Through the investigation of NO_x emission characteristics in waste incineration plants,this paper found that in addition to denitrification devices and related management need to be further optimized,there is a greater space for optimization of NO_x generation from a micro perspective to reduce NO_x emissions.The effects of furnace temperature,excess air coefficient,moisture content of flue gas,the contents of H/N,O/N and N elements,as well as the contents of fixed carbon and volatile components on NO_x production were analyzed under the conditions of small test.Data related to the above working conditions,waste material data and NO_x generation data when SNCR is shut down are collected from 8 actual incineration plants.Using Pearson correlation analysis and stepwise linear regression analysis to verify the fuel-N conversion rate and the correlation between various influencing factors.The results show that in industrial production,there is no significant relationship between fuel N conversion rate and furnace temperature and waste water content.The fuel N conversion rate decreases with the increase of N element content and fixed carbon content,but increases with the increase of excess air coefficient,H/N,O/N element ratio.Two independent variables H/N and fixed carbon content were selected as independent variables,and a prediction model was established with fuel N conversion rate as dependent variable.According to the fuel N conversion path diagram under industrial production conditions,fuel N conversion was divided into three parts: fuel N pyrolysis,oxidation and NO reduction.The accuracy of the model was verified by two methods,namely the functional expression method with the average relative error of 28.8%,and interval prediction method with the prediction accuracy of 75%,where H/N and fixed carbon content were divided into 3and 4 intervals respectively,making a total of 12 intervals.According to the prediction model,two methods are proposed to improve the combustion quality of waste materials to reduce NO_x production,namely,separating kitchen waste and adding coal.The separation of kitchen waste can mainly reduce the fuel N content and fuel N conversion rate at the same time.Four typical waste groups from the first and second-tier cities were divided into examples.The results show that fuel N conversion may increase at first and then decrease with the separation of kitchen waste.The addition of coal is mainly to enhance the reduction of NO_x by increasing the fixed content of fuel.Generally,lignite,bituminous coal and anthracite are optional.The reduction effect of NO_x achieved by adding different kinds of coal is similar,which mainly depends on the price of fuel.