Meier, DB, Gunnlaugsson, E, Gunnarsson, I et al. (3 more authors) (2014) Microstructural and chemical variation in silica rich precipitates at the Hellisheidi geothermal power plant. Mineralogical Magazine, 78 (6). 1381 - 1389. ISSN 0026-461X
Abstract
Precipitation of amorphous silica (SiO2) in geothermal power plants, although a common factor limiting the efficiency of geothermal energy production, is poorly understood and no universally applicable mitigation strategy to prevent or reduce precipitation is available. This is primarily due to the lack of understanding of the precipitation mechanism of amorphous silica in geothermal systems. In the present study data are presented about microstructures and compositions of precipitates formed on scaling plates inserted at five different locations in the pipelines at the Hellisheiði power station (SW-Iceland). Precipitates on these plates formed over 6 to 8 weeks of immersion in hot (120 or 60ºC), fast-flowing and silica-supersaturated geothermal fluids (∼800 ppm of SiO2). Although the composition of the precipitates is fairly homogeneous, with silica being the dominant component and Fe sulfides as a less common phase, the microstructures of the precipitates are highly variable and dependent on the location within the geothermal pipelines. The silica precipitates have grown through aggregation and precipitation of silica particles that precipitated homogeneously in the geothermal fluid. Five main factors were identified that may control the precipitation of silica: (1) temperature, (2) fluid composition, (3) fluid-flow regime, (4) distance along the flow path, and (5) immersion time. On all scaling plates, a corrosion layer was found underlying the silica precipitates indicating that, once formed, the presence of a silica layer probably protects the steel pipe surface against further corrosion. Yet silica precipitates influence the flow of the geothermal fluids and therefore can limit the efficiency of geothermal power stations.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2014 The Mineralogical Society. This is an author produced version of a paper published in Mineralogical Magazine. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Geothermal power; Iceland; precipitates; scaling; silica |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Jul 2015 13:33 |
Last Modified: | 03 Nov 2015 19:05 |
Published Version: | http://dx.doi.org/10.1180/minmag.2014.078.6.04 |
Status: | Published |
Publisher: | The Mineralogical Society |
Identification Number: | 10.1180/minmag.2014.078.6.04 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:85779 |