Optimization Of Ammonia Injection In SCR Denitration System Of Coal-fired Power Plants

SCR denitration system is the main way of flue gas denitrification in power plant.After SCR denitration device is put into use,some problems of increasing pollution and affecting safe operation of boiler units have occurred.Unreasonable ammonia injection is the main reason for the problems.Optimization of ammonia injection is an important guarantee for efficient operation of the system.Ammonia injection optimization according to engineering characteristics is to reduce nitrogen oxidation of the system The main technical measures to reduce the total emission.According to the actual investigation and visit to the power plant,the problems of ammonia injection system and CEMS system are analyzed,the automatic input of ammonia injection and the working environment between plants are optimized,and the continuous optimization is analyzed and prospected from three aspects of SCR system cold state adjustment,hot state adjustment and ammonia injection control.It is found that the main problems of the power plant are:uneven distribution of ammonia injection in SCR denitrification system and inaccurate detection value of CEMS online continuous monitoring system.Adjust the ammonia concentration at the outlet of the boiler by manual adjustment until the ammonia concentration at the outlet of the unit is adjusted according to the ammonia concentration of the grid and the ammonia concentration at the outlet of the unit.Finally,the standard deviation of NOX concentration was reduced to less than 10,and the average ammonia escape concentration was lower than 2.3 mg·Nm^-3.After optimization,the performance evaluation of SCR device was carried out.The denitration efficiency of the device was higher than 90%,the inlet and outlet flue gas temperature was between200℃and 500℃,the system resistance was between 600 Pa and 1100 Pa,and the air preheater was in stable and smooth operation state,which verified the results of optimization and transformation.Through the optimization test,the stability of power plant units and the capacity of flue gas purification are improved.In order to improve the monitoring level of pollutant emission in power plant,and solve the existing equipment defects and potential safety hazards of CEMS online continuous monitoring system,online monitoring meter comparison and sampling system inspection were carried out.The positions of sampling probe and sampling point were changed scientifically,and the blocked components in the sampling system were screened out and cleaned and replaced.Through optimization,the monitoring value of the instrument can reflect the real-time emission of flue pollutants accurately.