Fri, 22 March, 2019
Geothermal power plants operate at high temperature and pressure conditions, and geothermal sources, being aggressive natural environments, pose severe challenges to the structural integrity of various components such as well casings, well heads, turbines, pumps, valves, heat exchangers etc.
Materials used in these applications are subjected to several degradation mechanisms such as corrosion, erosion-corrosion due to dissolved CO2, H2S, NH3 gases and sulphate & chloride ions in the geothermal fluid that is circulated at high flow rates. Therefore, novel materials with enhanced resistance to harsh geothermal environment that can be manufactured at relatively low or acceptable costs, are desirable.
TWI, in collaboration with other project partners, is part of a European-funded H2020 project titled Geo-Coat 'Development of novel and cost effective corrosion resistant coatings for high temperature’.
The project includes the development of corrosion and erosion resistant coatings and metal matrix composite (MMC) materials for geothermal applications. Within the Thermal Processing Technologies (TPT) section, we are developing nickel and titanium based MMCs with ceramic reinforcements using powder metallurgy (PM) based processes such as uniaxial hot pressing (UHP) and hot isostatic pressing (HIPing) consolidation processes. The initial trials to produce MMCs have been completed both using UHP and HIPing consolidation techniques with microstructural characterisation, corrosion, corrosion-erosion, mechanical and tribological testing currently in progress.
In addition, we are also developing corrosion and wear resistant electroless nickel based coatings for low alloy steels. The initial coating development trials have been completed, including the inclusion of a functional top layer through the incorporation of Polytetrafluoroethylene (PTFE). Coating characterisation and testing work is in progress. The MMCs and PTFE based electroless nickel coatings will be tested under simulated geothermal environments by other partner organisations to check their suitability for geothermal applications.
The Geo-Coat project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 764086.
Discover more about how TWI is involved in projects to help exploit and progress the use of geothermal energy by industry.