Failure analysis of hearth tubes in the boiler of a thermoelectric power plant

Abstract

Steam electrical power stations that have operated its boiler for a period of time greater than 15 years, generally begin to experience several types of tube failures on furnaces, superheater coils and other boiler tube banks, which seriously affect its availability and reliability. This research has been developed to analyze the root cause of the different failures occurred in the boiler furnace of a power station of 132.5 MW installed capacity with only one turbo generator set, with more than 100 thousand accumulated operation hours. The specimens for analysis were obtained from failed tubes in different furnace sites and in different opportunities, and were sent to specialized laboratories for metallurgical analysis and/or internal deposits analysis to determine the primary causes of the failures. As a result, a correlation has been established between the failures morphology and the operative circumstances previous to its occurrence with its root cause type, as determined by experts, with the purpose of become a guide to personnel responsible for the maintenance of boilers in similar installations, to rapidly define the more probable failure cause, in case of occurrence of one of the analyzed failure types.