Thu, 07 May, 2020
Geo-Coat is currently developing novel high performance, specialised corrosion- and erosion-resistant coatings for exceptionally harsh geothermal environments. Launched in February 2018, the project now enters its third successful year when samples have travelled across continents for testing in ‘real’ geothermal conditions.
We are currently very busy performing exposure tests in both simulated conditions and field tests for the coatings and Metal Matrix Composites (MMC) down-selected from lab-based tests. These include a HVOF-sprayed cermet and two laser cladded High Entropy Alloys (HEA) for pipelines, valves, casing and turbine components, two electroless plated Ni-P-PTFE coatings for heat exchangers and Ni- and Ti-based MMCs for pump impellers.
Tests in simulated geothermal conditions are being performed, in parallel, at the University of Iceland (flow-through corrosion), TWI Ltd (static and SCC corrosion) and The Weir Group (erosion-corrosion). Tests are performed at temperatures between 130 and 200°C in a simulated geothermal fluid containing H2S and CO2 at pH=4. The specimens so exposed are then analysed for their microstructure (defects, permeation) and tribological/mechanical properties (e.g. 3 Point Bending Test, Scratch Test, etc.). Results from coated specimens are compared to uncoated bulk specimens made of standard alloys used in the geothermal industry (e.g. P265GH, Inconel Alloy 625, 254 SMO, etc.). In parallel, the same materials are being tested with real geothermal fluid within the Hellisheidi power plant (Reykjavik, Iceland) in a collaborative effort between the Innovation Centre Iceland and ON Power. The testing equipment, manufactured specifically for the Geo-Coat project, are placed at several locations within the power plant, including within one of the wellheads itself.
The results from all these analyses are being gathered and compared with each other. Thanks to these results, a final down-selection of one coating per application will be performed within the next 1-2 months. In the final stage of the project, the down-selected coatings will be applied to real components, such as a pipeline and steam turbine rotor component. These will be tested within the real power plant operational cycle in order to fully validate the Geo-Coat technology.