Study On The Optimization Scheme Of Ultra Low Emission From SCR Flue Gas Denitrification System Of 300MW Coal-fired Boiler

Selective catalytic reduction denitrification?SCR?technology is widely used in electric power production and industrial enterprises because of its high efficiency,high reliability,simple equipment and easy maintenance.In recent years,the original SCR denitration system of a power plant has not been able to meet the increasing ultra-low emission requirements,which seriously affects the normal operation of the unit.IIn view of the problem of large ammonia consumption and blockage of air preheater in the operation of SCR in a power plant,the flow field and concentration field distribution of denitrification reactor and inlet and outlet flue were calculated by using CFD numerical simulation method.The flow field of denitrification system,the structure of ammonia injection grille and the optimization scheme of adjusting the valve of ammonia injection grille are given.According to the optimization scheme,the ammonia consumption of the system is obviously reduced when the unit load is approximately the same as that of the unit.The specific research work is as follows:1.The production mechanism the principle of SCR flue gas denitrification and process,the formation mechanism and hazard control of ammonium hydrogen sulfate are analyzed.2.The existing problems of SCR denitrification system in a power plant are analyzed.The equal proportion model of denitrification system is built by GAMBIT,and the numerical calculation of flow field is carried out by FLUENT.It is found that the flow field is unevenly distributed in the flue and reactor at the entrance of SCR.Furthermore,the flow field optimization scheme for reasonable layout of diversion plate in denitrification system is put forward.3.On the basis of flow field optimization of denitrification system,the concentration field of SCR denitrification system was calculated considering denitrification chemical reaction,the distribution of NOx?NH₃ and ammonia nitrogen mole ratio in reactor was obtained,and the problem of uneven distribution of concentration field and ammonia nitrogen mole ratio was found.The optimization scheme of ammonia injection grille structure,concentration field optimization,replacement of ammonia injection valve and AIG ammonia valve adjustment is put forward.4.According to the optimization scheme,the denitrification system was reformed and adjusted.Compared with the operation of the denitrification system before and after the revamping,the denitrification efficiency of the denitrification system was stable at more than 90%,the ammonia consumption was reduced by about 10 kg/h,and the optimized revamping target was achieved.