Study On The Mechanism Of Waste Heat Recovery Of Coke Oven Flue Gas Coupled SNCR/SCR Process

Under the current serious atmospheric environmental problems such as chemical smog,haze and greenhouse effect,the nitrogen oxide(NOx)emission concentration of coke oven flue gas is as high as 200?1800mg/m3,and many coking enterprises choose high-efficiency medium temperature(573?673K)selective catalytic reduction(SCR)process to remove NOx.However,the SCR denitrification system of coke oven flue gas has reduced the economic benefits of the coking plant due to the high cost,huge equipment,and additional fuel consumption.Especially in the context of energy saving,emission reduction and"dual carbon" goals,coking companies urgently need to explore new processes with low cost and low energy consumption to control flue gas NOx emissions.Therefore,in this paper,combining the thermal performance characteristics of the coke oven regenerator,a new-type of flue gas waste heat recovery coupled with selective noncatalytic reduction(SNCR)or selective catalytic reduction(SCR)is developed to achieve the dual goals of heat storage and low-cost,low-energy denitration.Taking JNK43-98D traditional regenerator as the research object,this paper discusses the heat transfer law with reversing time in the process of flue gas flowsolid heat storage,emphasizes that temperature movement and interval proportion are the key factor to limit the coupled SNCR/SCR process,and defines the importance of heat storage materials on the outlet temperature and heat storage capacity of regenerator;The ammonia injection space structure for reductant injection is designed,and the mathematical model of coupling fluid-solid heat storage and SCNR/SCR reaction is established.The validity of the reaction kinetic model is verified,and an evaluation method of flue gas heat storage based on the principle of energy conservation is proposed,and the effect of various heat storage materials on the heat storage capacity of the new-type regenerator is measured and optimized.For the coupled single SNCR process,the spatial location of ammonia injection on the flow,heat transfer and NO/NH3 spatial concentration distribution characteristics of the new regenerator are analyzed.It is found that the reaction ambient temperature is very important for the competitive process of reduction reaction NH3+NO?N2 and oxidation reaction NH3+O2?NO,outlet NO concentration and NH3 escape,the in-depth discussion on improving the relevant process operating parameters of reductant injection can effectively enhance the SNCR process and achieve the maximum NO reduction efficiency of 80%.Further research has obtained the optimization strategy of NO emission reaching the standard and NH3 escape of 13.4mg/m3;For the coupled single SCR process,the influence mechanism of NH3 concentration uniformity distribution and diffusion rate on SCR catalytic reduction is revealed,the enhancement effect of mixed process parameters on SCR reaction efficiency is analyzed,and the NO reduction efficiency is increased from 36%to 70%by increasing the catalytic area;For the coupled SNCR+SCR process,the spatial upstream and downstream sequential undertaking relationship between SNCR and SCR section on NO reduction and NH3 consumption reduction is clarified.By analyzing the process operation parameters,it is clear that SNCR undertakes the contribution of NO reduction and SCR to further reduce NH3 escape,and further uses the orthogonal design method,the low-cost optimization scheme of the coupling process meeting the dual low emission requirements of NO and NH3 is determined.