Study On Operation Adjustment Of SCR Denitration System For 660MW Coal-Fired Units

Selective catalytic reduction(SCR)flue gas denitrification technology is widely used in flue gas denitrification project of thermal power plant,which has the advantages of high denitration efficiency and stable and reliable system operation,and can better meet the demand for efficiency under unit load change.Denitrification efficiency and ammonia gas escape rate are important factors to evaluate whether the SCR denitrification system is running well.The uniformity of NO_x concentration and the homogeneity of the flue gas flow field are the decisive factors of these two important indexes.In this article,studied on the SCR denitration system equipped with a 660 MW ultra-supercritical coal-fired unit,and the relative deviation of NO_x emission from SCR flue gas denitrification system is 36.98% and 65.92% respectively,which do not satisfy the export relative deviation less than 20 % Of the requirements,the downstream air preheater equipment there are different degrees of pressure drop and a slight blockage phenomenon.According to the non-uniform distribution of NOX concentration at the exit of the denitrification system,the distribution of NO x and O2 in the outlet of the reactor was measured by grid method,and the distribution of NO_x and O2 was measured.After the NO_x denitrification system is fully sprayed,the flue gas flow rate,NO_x concentration and ammonia concentration are measured at the exit of the SCR denitrification system inlet and the SCR denitrification system,and the NO_x concentration at the outlet of the SCR denitrification system is measured.The distribution of the situation to conduct detailed measurement,calculation and analysis,in the NO_x concentration of export reactor control relative deviation of 20% or less,Under the condition of the same load and ammonia escape rate,the denitrification efficiency of the SCR denitrification system was observed and the uniformity of NO_x concentration distribution at the outlet of the SCR denitrification system was investigated to the important effect of SCR denitrification system operation.Through the comprehensive comparison and analysis of the data before and after the operation of the SCR denitrification system,the 660 MW ultra-supercritical coal-fired units have been fully optimized to make the maximum deviation,standard deviation and relative deviation of NO_x concentration in the SCR denitrification system export The NO_x concentration in the outlet of the SCR denitrification system is reduced and the uniformity of NO_x concentration in the outlet of the SCR denitrification system is improved.At the same time,the problem of the high escape rate of the ammonia in the local area of the SCR denitrification system is solved,,The ammonia escape rate is reduced,and the service life of the catalyst is improved.The results of this study can meet the actual operating results of the research object,and reach the corresponding national standard.At the same time,the research method and research results can provide references for the safe operation and efficient regulation of the SCR denitrification system of the same type unit in China.