Failure Analysis and Remedial Solution Suggestion for Superheater Tubes of a Power Plant Boiler

Abstract

Superheater tubes are the most critical components of a power plant’s boiler. Due to operation in high-temperature and -pressure conditions, platen superheater (primary superheater) tubes in thermal power point boilers are exposed to breakdowns such as creep failure and overheating. Therefore, identifying the causes of these failures and its maintenance is very important. Platen superheater tubes have failed in several similar power plant units at the same specific area. This problem is analyzed by three methods to find out the reason. These methods are metallography, measuring oxide layer thickness and CFD. These methods prove that the temperature difference between tubes is the cause of failure at the critical area. Length difference between tubes is the reason of the temperature raising in this case. Then, three solution methods are presented, namely (1) changing tubes material, (2) balancing tubes length and redesigning the platen superheater and (3) replacing the failed tube with new one. For comparing the methods, balancing tube’s length and redesigning is selected. The selected solution introduces three proposed plans. These plans will be alternative for the failed platen superheater. A comparison made between three proposed design and platen superheater indicates that all of the three proposed designs are better in temperature side than the existing platen superheater. After that, the best design is chosen by the CFD results. The selected design here is the proposed plan 2 because it reduces the 25 K temperature difference of the platen superheater to 5 K and this will prevent this kind of failing.