Study On Transformation Of Low Nitrogen Burner Of 320MW Subcritical Coal-Fired Boiler

NO_x is one of the main pollutants in the atmosphere,which is the main cause of photochemical pollution and acid rain.As coal will produce a large amount of NO_x during combustion,coal-fired boilers become the main source of NO_x emissions.According to the ultra clean emission target of coal-fired power plants recently implemented by the state,power generation enterprises are required to control the emission concentration of NO_x within50mg/Nm~3.Therefore,coal-fired power plants need to be transformed to use low nitrogen combustion technology to reduce NO_x emissions.In order to reduce the NO_x concentration at the boiler outlet,reduce the cost of SCR denitration,and ensure that the hourly average NO_x emission of the unit meets the requirements of the national ultra-low emission standard,a thermal power plant in South China has upgraded its#3 boiler’s low nitrogen combustion system.This paper carries out a comprehensive research and analysis of the Company’s#3 boiler burner transformation,and describes various influencing factors to be considered in the upgrading and transformation scheme for the selection of low nitrogen combustion technology transformation scheme of large power plant boilers,including the overall evaluation of the unit before transformation,the selection of burner type,the setting of secondary air,the design of primary and secondary air nozzles,etc.After investigation and comparison,it was finally decided to adopt the transformation scheme of air staged combustion and low nitrogen burner.In order to investigate the operation state of the new low nitrogen combustion system after transformation and find the best way to operate,various tests were carried out according to the relevant national and industrial standards,and the main parameter changes before and after transformation were compared and analyzed to find the better operation condition of the boiler and optimize the combustion condition.The NO_x content of flue gas at the inlet of denitration reactor shall reach the emission requirement of about 250mg/Nm~3,and the service life of SCR catalyst shall be extended to reduce the operation cost of denitration device.Finally,after careful study and analysis,the optimization scheme and suggestions for solving the new problems after transformation are proposed to improve the safety and economy of the unit.In addition,by comparing the performance before and after the transformation,technical reference and transformation experience are provided for the same type of units.