Mon, 25 July, 2022
TWI principal project leader, Briony Holmes is set to present findings from the collaborative GeoSmart project at EUROCORR 2022, in Berlin.
The event takes place from 28 August to 1 September, with Briony presenting on ‘Materials Compatibility Study for Geothermal Plant’ during the ‘Corrosion in Green and Low Carbon Energy Technologies’ session at 9:50am on Tuesday 30 August.
The presentation is based on work undertaken on the GeoSmart project by Briony alongside fellow TWI employees Alexandre Sabard, Chi Lee and Shiladitya Paul.
The presentation will deliver details of the testing of a series of materials that are likely to be used in geothermal assets.
Geothermal fluids are an established means of producing energy, with plant efficiencies based on the fluid temperature as well as the reinjection temperature. If heat could be extracted from the geothermal fluids down to lower reinjection temperatures, it would be possible to improve plant efficiency. However, these lower temperatures could also lead to more scaling in components.
In order to gain these improved efficiencies, modifications to a high enthalpy power plant, with the inclusion of an additional heat exchanger and a retention tank that would allow for the removal of silica from the fluid before reinjection were envisaged.
A selection of commercially-available alloys that could be used in the construction of a modified plant were assessed in a simulated geothermal brine in order to assess the corrosive impact of the geothermal fluids upon them. The materials tested included parent materials, welded materials and coated materials based on SA516 Grade 60 carbon steel, 304L (UNS S30403), 254SMO (UNS S31254), and 316L (UNS S31603) austenitic stainless steels, UNS S32760 duplex stainless steel and Ti Grade 1 and 2 (UNS R50250 and R50400). Some two-part epoxy coatings were also tested, after being selected for their hydrophobicity or ‘anti-scaling’ properties.
Laboratory–based crevice corrosion, pitting corrosion and stress-corrosion cracking tests were performed in static fluid and long-term immersion testing was also performed to simulate the likely failure modes and evaluate scaling. Short-term static electrochemical testing was also performed.
The test temperatures aligned with the intended minimum and maximum operating and design temperatures of the components.
Finally, post-test evaluation of the materials was undertaken, including visual observations, light and scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, metallographic sectioning, dye penetrant inspection (DPI) and optical profilometry tests.
You can find out more about TWI’s work as part of the GeoSmart project consortium on the dedicated GeoSmart project website, here.
The GeoSmart project has received funding from the European Union's Horizon 2020 research and innovation programme grant agreement 818576