Failure Analysis Case Study on Condenser Vessels of Gas Removal System in Wayang Windu Geothermal Power Plant Unit 2

Abstract

Gas exhauster or gas removal system is typical facility for non-condensable gases (NCG) removal from turbine condenser in a single flash geothermal conversion system. Wayang Windu Geothermal Power Plant Unit 2 in West Java, Indonesia, which is also operated by single flash system, applies a hybrid type Gas Removal System (GRS) consisting of three exhauster series. The second-stage, direct-contact condenser vessels of those three series experienced cracks and leaks alternately after three years of operation. Material testing and examination including metallography, hardness test, and SEM-EDS analysis have been conducted to deliver failure analysis of the condenser failures. It was concluded that the cracks were caused by hydrogen cracking due to combination of corrosive environment in the vessel and high residual stress thanks to its manufacturing process. Based on this study, several improvement on material specifications and maintenance activities of surface facility equipments were proposed in order to afford more reliable geothermal power plant.