Mon, 02 September, 2024
TWI Project Leader, David Martelo is due to present findings from the Horizon 2020-funded GeoSmart project at The European Corrosion Congress (EUROCORR) 2024 on Tuesday, 3 September, 2024.
David will present a paper, ‘Materials and Scaling Study for Geothermal Plant,’ which he co-wrote with TWI colleagues, Briony Holmes, Chi Lee, and Shiladitya Paul.
The paper details an investigation into the scaling tendency of geothermal fluids on materials likely to be used in the creation of a scaling reactor and retention tank at a high enthalpy power plant, which would permit the removal of silica from geothermal fluids before reinjection.
The efficiency of a geothermal plant depends upon the temperature (and reinjection temperatures) of the geothermal fluids. Efficiency gains would be possible if heat was extracted from the geothermal fluids down to lower reinjection temperatures, but these lower temperatures can, in turn, 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.
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. The materials were selected either for their hydrophobicity (i.e. ‘anti-scaling’ properties) or their scale-promoting properties.
Laboratory tests were performed in flowing fluid under conditions calculated to simulate the likely fluid flow conditions in a scaling reactor in the field. Testing was performed to evaluate scaling alongside additional short-term electrochemical testing.
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 before 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 in the field.
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.