Process steam at geothermal power plants contains high concentrations of non-condensable gases (NCG). This operations fact of life requires the use of efficient and reliable equipment to remove it from power turbine condensers to maintain lowest vacuum possible and optimize system performance. An innovative, collaborative effort by Barber-Nichols, Inc., Pacific Gas & Electric Co. (PG&E), Unocal Corp., and the U.S. Department of Energy has resulted in the development of a new turbocompressor that offers an efficient and reliable alternative for removing NCG from condensers at geothermal power plants. Most geothermal power plants currently utilize several stages of steam-jet ejectors, and occasionally a liquid-ring vacuum pump, as the final stage to remove NCG from condensers at a low vacuum pressure, with exhaust at ambient pressure. These systems perform the necessary work, but can require highly parasitic steam-flow rates in the case of ejectors, or high power requirements in the case of motor-driven liquid-ring vacuum pumps.
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