Numerical Study And Performance Monitoring Of Coal-fired Flue Gas SCR De-NO_x System

As for coal-fired power plant,selective catalytic reduction(SCR)technology for flue gas denitrification is still the mainstream technology in the present and future.This paper takes a 660MW coal-fired thermal power SCR denitrification catalyst as the research object,The following work is carried out:SCR powder catalyst test?SCR pilot test?kinetic study on the selective catalytic reduction(SCR)of NO?performance analysis of SCR denitrification and so on.The main research contents of this paper are as follows:(1)The SCR denitration experimentThe experiment of SCR powder catalyst is divided into four parts.The first three parts are as follows:experiment of different catalyst particle mesh?experiments with different mass flow rates?fixed bed experiment with different catalyst loading.Through the experiment,the reaction conditions of the catalyst samples without internal and external diffusion are obtained:the catalyst particle mesh within 60?80?flue gas flow rate is 3.5L/min?Catalyst loading is 1mL.The last part of the experiment is to change the ammonia nitrogen molar ratio and temperature under the above conditions,the experimental results lay the foundation for the subsequent dynamic parameter mining.SCR pilot scale experiment was conducted to study the effects of different operating conditions on the catalyst,and as a basis for validation of dynamic model,capture of deterioration rule,the experiment results show that:with the increase of operation time,catalyst activity decreased,the optimal temperature window becomes narrow,when the temperature is lower than 290 ? and higher than the temperature of 330 ?,the performance of denitrification changes greatly,otherwise,it doesn't chage much.(2)Dynamic parameter mining and 3D porous catalyst modelFirstly,on the basis of E-R reaction kinetics,considering the side effects of NH3,the genetic algorithm was used to optimize the intrinsic kinetic parameters of SCR denitrification.The research shows when using 300 species,the parameters of the 200 generation for 27 operating conditions,the NO conversion error between calculated value and powder catalyst test were 5.88×10-2,this kinetic parameters are taken as the final result.On the basis of these,further coupled SCR intrinsic reaction model and SCR reactor macroscopic flow model,the multiphase reaction model of three-dimensional multi channel catalyst was established.The model is in agreement with the experimental results,the NO conversion rate of the model was slightly higher than that of the experimental results.(3)Performance analysis of SCR denitrificationThe distribution of NO in the flue gas and catalyst wall is obtained by simulation.Besides,the relationship between the characteristics of SCR macro denitrification and chemical reaction and diffusion was obtained.The influence of operating conditions on denitrification efficiency was studied during the follow-up study,the results show that when the space velocity is kept at 3600 h-1 and the temperature is between 280??350?,the denitrification efficiency is about 80%?90%,good denitrification performance was obtained at this time.There is an optimal performance interval in SCR,the results show that the denitrification performance reached a good level when the temperature is about 313.8?,space velocity is kept at3600 h-1 and the ammonia nitrogen molar ratio is 1.03,In addition,the development and application of performance monitoring platform for denitration system in coal fired power plant will benefit power plant operators,it can save a lot of time for managers,help them to learn from each other and improve the overall operation level.