Numerical Optimization And Experimental Study On Flow Field Of SCR Denitrification Tank

Coal-fired power generation is in an absolute dominant position in our country.The energy structure of "rich coal,oil shortage and less gas" determines that the leading position of coal-fired power generation will not change for a long time.Although coal-fired power generation is the "cleanest" way of coal utilization,a large number of pollutants still exist because of the huge base.Relevant data indicate that 67% of nitrogen oxides in China's atmosphere come from coal combustion.As a large coal fired power plant,with the increase of installed capacity in recent years,the amount of nitrogen oxide emissions is increasing every year,and it has a trend to speed up.So that the amount of NOx emissions in China has been the second largest country in the world.It is urgent to take relevant measures to control the emission of NOx.Therefore,in order to achieve sustainable development,China has formulated more stringent environmental protection standards.In the denitration process of thermal power plants,SCR has become the most widely used flue gas denitration technology because of its early start,relatively mature technology and high denitration efficiency.Selective catalytic reduction and denitrification technology can react with NOx by injecting ammonia,liquid ammonia,urea and other reductants to produce nitrogen and water products.However,as the catalyst causes self inactivation due to wear and clogging in a long period of operation,it is necessary to optimize the flow field in the SCR denitrification tower to improve the life of the catalyst.This thesis used Flunet software,based on the SCR denitrification tower of a power plant in Shandong,this paper simulated the influence of the velocity distribution on the section velocity distribution above the first layer of the catalyst layer and the entry angle of the flue gas.The results show that the spacing of the grid is equal to 100 mm and the height is equal to 300 mm,the first layer is accelerated.The relative standard deviation value of the cross-sectional velocity above the chemical agent is less than 14.25%,and the proportion of the gas deflection angle within 10 degrees is 95.38%.After the rectification grid is optimized,the result accords with the standard,but there is still a low speed zone on the right side of the denitrification tower after the optimization of the grid.It is found that the right low speed area of the tower is eliminated when the baffle is arranged at the height of the 1/3 level at the inlet of the 1/3 level.The relative standard deviation of the cross section above the first layer of the catalyst drops to 7.24%.On the basis of the simulation,the cold experiment is used to verify the simulation results.It is found that the rectifying grid can effectively eliminate the low-speed eddy current zone in the middle and middle parts of the tower,and the top diversion baffle can improve the low speed zone in the right side,and the experimental results are in agreement with the simulation.