Analysis Of Sncr Reaction Mechanism Using Urea As The Reducing Agent And Numerical Simulation Of Denitration Pilot Test

SNCR technology is a low-cost flue gas denitration technology.The reducing agent of SNCR is usually ammonia,ammonia water or urea,etc.Urea is safe,easy to transport and store,but the denitrification process of SNCR using urea as a reducing agent is relatively complex.It is of great significance for engineering application and optimization to study the influence of urea decomposition on the denitrification process of SNCR and its reaction mechanism,and to establish a numerical simulation method of SCNR for the engineering application and operation optimization of urea method SNCR.Chemkin software platform was used to study SNCR denitrification reaction mechanism of different reductants at different temperatures by Urea2000 mechanism,and the influence of urea decomposition on SNCR denitration was analyzed to obtain the main reaction path of UREA SCNR.GAMBIT software was used to model and grid the SCNR pilot plant.Numerical simulation of the combustion process on the one-dimensional pilot plant was completed on the FLUENT platform of CFD software,and the temperature distribution and NO concentration distribution in the furnace were obtained.On this basis,numerical simulation of SNCR denitration process was carried out.This article compared the three methods of "two-step decomposition model of urea","decomposition of urea to ammonia" and "decomposition of urea to ammonia and isocyanic acid" to describe the chemical reaction process of SNCR denitration using urea as reducing agent,and calculated the ammonia nitrogen ratio(NSR)and the influence of reaction temperature on the denitration process,at the same time,compared the denitration efficiency of urea and ammonia as reductant.The following conclusions are drawn through simulation calculation: the simulation results of "urea decomposition into ammonia and isocyanic acid" are close to the experimental values.With the increase of NSR,the denitration efficiency of SNCR increased.The simulation results of "urea decomposition into ammonia and isocyanic acid" showed that when NSR increased from 1.0 to 2.5,the denitration efficiency increased from 64.5% to 89.2%.The denitrification efficiency can reach 70%?80% when the reducing agent is sprayed at 900?,while the denitrification efficiency is only 40%?50% when the reducing agent is sprayed at 1000?.The denitrification efficiency of urea was slightly higher than that of ammonia.