The Main Challenges in Operation and Maintenance of Geothermal Power Plant

Abstract

The operation of geothermal power plants has many challenges in terms of maintenance. These challenges can in some cases be specific to geothermal power plants. The specific problems faced by operators of geothermal power plants can be divided into few main categories but in general the main causes are: a) scaling b) corrosion c) erosion In terms of the power plants operated by ON Power, problems associated with scaling are most frequently observed in moving parts. These are mechanical parts extending from control valves at production wellheads, stuck gland steam seals and valves throughout the re-injection system to name a few. Heat exchangers in contact with the geothermal brines are prone to scaling if mitigation actions are not in place. A heavy emphasis is placed on the maintenance of turbine parts and in particular on diaphragms and rotors. There, erosion can be elevated in the case of insufficient removal of condensed droplets from the steam collection system and the condensation of steam while travelling through the turbine towards the condenser. Corrosion is mainly observed when temperatures are below 100°C and moisture within insulations is not evaporated rapidly. There, corrosion of pipes is observed where moisture penetrates the claddings protecting insulation materials. Corrosion is also observed in the gas collection system and over the recent years, ON Power has been involved in research on specialized coatings and studying steel alternatives to 316L.