Serious Corrosion Reason for Air Pre-heater in a Power Plant

To identify the cause of the serious corrosion of air pre-heater in a power plant and put forward effective solution, a primary analysis of the air pre-heater was carried out by adopting on-site inspection and pipe macroscopic observation. On the basis of the primary analysis, in-depth analysis on the dust and corrosion products of the air pre-heater′s pipe wall was conducted, with the help of microscopic analysis detection methods, including scanning electron microscopy (SEM) and energy dispersion spectrum (EDS). Results indicated that the serious corrosion occurring in the air pre-heater initiated from the outside wall of the pipes. After the corrosion, the sulfur content of the pipe wall was relatively high while little nitrogen was found, so it could be determined that the serious corrosion was low-temperature acid dew point corrosion rather than ammonium hydrogen sulfate corrosion caused by ammonia escape, and effective solutions, such as optimizing the steam air heater and utilizing new corrosion-resistant materials, were put forward accordingly.