Thursday, 22 April
Official Opening of the Geothermal Plant on the OIT Campus
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Oregon Institute of Technology’s Klamath Falls campus reports on the official opening of its geothermal electric power plant generation demonstration plant. I remember a presentation by Toni Boyd (the Assistant Director for OIT's Geo-Heat Centre, which is responsible for this project) on planning for this in last year's Stanford Geothermal Workshop. |
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The brine is produced using line-shaft pumps with variable-frequency drives placed at about 170-m depth. Prior to the the construction of the power plant, the geothermal fluid was being used for heating. The fluid out of the well was first piped into a central heat exchanger building where its particulate matter (mostly sand) is removed in a settling tank. From there the water is gravity fed into the various buildings on campus.
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Toni Boyd with the new OIT Demo Plant. The new power plant is based on a UTC Pure Cycle unit. The plant is fed by geothermal fluid that boils the cycle fluid (a refrigerant) at 91 oC.
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Initially the geothermal water was used directly in the heating systems, but due to ammonia and 2 ppm (2 mg/L) of hydrogensulfide which attacked the copper and solder in the radiators, this introduced maintenance problems. There was a range of failures including failure of the 50/50 tin/lead solder connections; rapid failure of the 1% silver solder; wall thinning and perforation of copper tubing; control valve failure where brass plugs were crimped on stainless steel stems (threaded vaves experienced no problem); and control valve problems associated with packing leakage. To address these issues, isolation plate heat exchangers had to be installed in each building. These used 316 stainless steel plates with Buna-N gaskets and a picture was included in Toni Boyd's paper and I copy below.
The 316 stainless steel was not suitable for the heat exchanger that was used for swimming pool heating due to the chlorine in the pool water and titanium plates had to be used there.
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