Abstract: SCR flue gas denitration technology has been widely used in China’s thermal power plants because of its maturity and reliability. SCR devices have strict requirements for inlet flue gas temperature. The decrease of boiler feed water temperature will directly lead to the decrease of flue gas temperature. How to ensure the normal operation of the SCR device after the high pressure heater out of service has become an urgent issue for the majority of thermal power plants. This paper makes a large amount of data statistics and analysis for the operation of the 320 MW unit in a plant,and summarizes the operation measures of high pressure heater out of service or put into service that can ensure the safe operation of the SCR device. It is of guiding and reference significance to ensure the safe operation of denitration system in thermal power plant.

Key words: influencing factors, denitration device, impact of high pressure heater out of service, reasons and countermeasures, optimization measures