Thu, 07 November, 2024
Findings from a study into scaling and the performance of materials in simulated geothermal brine have been published in the Journal of Materials.
The paper, ‘Investigation of Scaling and Materials’ Performance in Simulated Geothermal Brine,’ was co-written by David Martelo, Briony Holmes, Namrata Kale and Shiladitya Paul of TWI Ltd alongside Samuel Warren Scott from the University of Iceland’s Institute of Earth Sciences.
The findings presented in the paper forms part of the GeoSmart project’s work to test solutions to improve the flexibility and efficiency of geothermal heat and power systems. The published research paper comes from a larger GeoSmart study to develop a scaling retention system in the Kizildere 2 geothermal power plant in Turkey.
Corrosion and Scaling Challenges
Although geothermal energy offers a sustainable and eco-friendly form of power generation, the efficiency and lifespan of geothermal power plants are often compromised by corrosion and scaling. Corrosion can occur as a result of selecting the wrong materials or from inadvertent changes in the chemistry of the geothermal brine. Scaling, meanwhile, occurs when dissolved minerals precipitate from the geothermal fluid and are deposited on the surfaces of pipes and equipment, causing blockages and increasing maintenance costs. Both corrosion and scaling can lead to significant operational challenges, so strategies to prevent these are critical to improved geothermal operations.
Mitigation Techniques
There are a number of methods currently in use to mitigate against scaling in geothermal systems, including controlling fluid temperatures and the use of chemical treatments to inhibit the rate of scale deposition. In addition, the development of coatings to help materials resist scaling more effectively has shown promise. However, these techniques present some drawbacks. For example, scaling inhibitors can generate other issues such as corrosion or stress corrosion cracking.
The Study
This study explores the behaviour of materials in a simulated geothermal brine using flow conditions that approximated the predicted flow conditions within the geothermal brine. Both scale-promoting and scale-preventing materials were studied, including carbon steel, austenitic stainless steel, duplex stainless steel, two proprietary two-part epoxy coatings, and thermally sprayed aluminium (TSA).
A laboratory vessel designed to replicate the wall shear stress conditions in a scaling reactor was used for the tests, which revealed varying scaling tendencies among the materials as well as minimal corrosion. Coupons of the materials that were tested have now been introduced into a retention tank installed in Kizildere 2, with the assessment of these due be performed using the same methodologies as the laboratory tests so the results can be compared.
Find Out More
You can find out more about the materials and the testing conditions as well as the findings of this work by reading the full paper, here: https://doi.org/10.3390/ma17215250
The GeoSmart project has received funding from the European Union's Horizon 2020 research and innovation programme. Grant agreement 818576