Numerical Simulation And Optimization Of SCR Denitrification System In Supercritical Boiler

Nitrogen oxides?NO_x?in coal-fired power plants are the key pollutants controlled by national energy conservation and emission reduction.Selective catalytic reduction?SCR?denitrification is one of the most effective NO_x control technologies,guaranteeing SCR to run efficiently and under all conditions,so as to control NO_x emissions and reduce environmental pollution.Taking SCR denitrification system of power plant supercritical boiler as the research object,using ANSYS-Fluent software,under the condition of maximum evaporation rate?BMCR?,the velocity and pressure distribution of empty tower SCR system were simulated firstly,and the relative standard deviation coefficient C_v was used to quantitatively evaluate the uniformity of system velocity.According to the simulation results,the relative standard deviation C_v1 of upstream velocity of ammonia-spraying grille?AIG?is 20.05%,and the relative standard deviation C_v2 of inlet velocity of the first layer catalyst is 9.74%.Among them,C_v1 does not meet the design requirements of less than 15.00%.Eighteen groups of calculation conditions were designed by orthogonal test method.The effects of diversion plate,porous plate and rectifying grid with different structural parameters on the velocity uniformity of upstream and first layer catalyst inlet of AIG were analyzed.The simulation results show that the perforation ratio of porous plate has the greatest impact on C_v1 value,and the rectifier grid spacing has the greatest impact on C_v2 value;under the optimized scheme,the C_v1 value is 3.94%,and the C_v2 value is 4.33%.The flue gas bypass is installed before the entrance of SCR reactor to increase the flue gas temperature of boiler under medium and low load conditions and ensure the full operation of SCR denitrification system.Under 30%MCR condition,the intermittent insertion type of flue gas bypass was determined by optimization.After optimization,the temperature distribution,velocity distribution and pressure loss of flue gas under 50%MCR and BMCR conditions all meet the operation requirements.Figure 44;Table 9;Reference 60.