Mon, 02 September, 2024
Findings from the Horizon 2020-funded GeoSmart project are due to be presented at The European Corrosion Congress (EUROCORR) 2024.
A paper, ‘Materials and Scaling Study for Geothermal Plant,’ which was co-written by Briony Holmes, David Martelo, Chi Lee, and Shiladitya Paul from TWI Ltd, will be presented by David Martelo on Tuesday, 3 September, 2024.
The presentation will detail investigations into the scaling tendency of geothermal fluids on materials likely to be used in the construction of a scaling reactor and retention tank, which would permit the removal of silica from geothermal fluids before reinjection in a high enthalpy power plant.
Geothermal plant efficiency depends upon the temperature of geothermal fluids along with their reinjection temperature. Efficiency gains would be possible if heat was extracted from the geothermal fluids down to lower reinjection temperatures. However, these lower temperatures could lead to more scaling.
To solve this, modifications to a high enthalpy power plant were envisaged, including a scaling reactor and retention tank to permit the removal of silica from the fluid before reinjection.
To assess the scaling tendency of the geothermal fluids on the likely materials of construction, the performance of a selection of commercially available alloys was evaluated in a simulated geothermal brine.
In addition, some 2-part epoxy coatings and thermally-sprayed aluminium were also tested, having been selected either for their hydrophobicity (i.e. ‘anti-scaling’ properties) or their scale-promoting properties.
Tests were performed in flowing fluid in the laboratory under conditions calculated to simulate the likely fluid flow conditions in the scaling reactor in the field, and testing was performed to evaluate scaling. Short-term electrochemical testing was also performed.
The materials tested included bare and coated materials based on SA516 Grade 60 carbon steel, 304L austenitic stainless steel, lean duplex stainless steel, three types of proprietary 2-part epoxy coatings and thermally-sprayed aluminium. Test temperatures were up to 50°C, keeping them relevant to the scaling reactor’s intended operating and design temperatures. The simulated geothermal brine was adjusted to test at different pH and detailed post-test evaluation was conducted by visual observation, light and scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, metallographic sectioning, and optical profilometry. Comparative samples have now been placed in an operational geothermal plant to demonstrate and assess their scaling and corrosion performance.
David’s presentation will offer details of this important testing for geothermal operations.
About EUROCORR
The European Corrosion Congress (EUROCORR) is the European Federation of Corrosion’s (EFC) annual conference, which combines a high technical standard with a popular social programme. The flagship event of the international corrosion calendar, EUROCORR attracts upwards of a thousand delegates and is held every September in a different European country. This year’s EUROCORR is taking place 1 - 5 September 2024 in Paris, France.
You can find out more and register, here.
This project has received funding from the European Union's Horizon 2020 research and innovation programme. Geosmart, Grant agreement 818576.