GEG is a supplier of flash-condensing type and modular geothermal wellhead power plants, delivered on a turnkey basis. Here below we provide an overview on the functionality of a flash steam plant and connected condenser.
Flash steam geothermal power plants
The U.S. Department of Energy’s Geothermal Technologies Office, describes three main geothermal power plant technologies, that can convert hydrothermal fluids to electricity.
The technologies are dry steam, flash steam and binary-cycle power plants. “The type of conversion used depends on the state of the fluid (wheather steam or water) and its temperature.”
Flash steam plants, as provided by GEG, are the most common type of geothermal power generation plants in operation today. At the end of 2014, the majority of all geothermal power plants, around 63% or 7,800 MW are classified as flash steam plants. (Bertani, R., Geothermal Power Generation in the World 2010-2014, WGC2015)
“Hydrothermal fluids from geothermal wells that have a temperature of more than 182°C (360°F) can be used in flash plants.” GEG normally requires a temperature of 200°C and more downhole for its solution.
“Fluid is sprayed into a tank held at a much lower pressure than the fluid, causing some of the fluid to rapidly vaporize, or “flash” (please refer to picture 2.8). The vapour then drives a turbine, which drives a generator. If any liquid remains in the tank, it can be flashed again in a second tank to extract even more energy.
Flash power plants exist in single and multiple flash variations. In a single flash plant the liquid dominated brine steam mixture will be flashed in a separator before the dried steam will be fed to the condensing steam turbine.”
- U.S. DOE, Geothermal Technologies Office, Hydrothermal Power Systems
“The main purpose of the condenser is to maximize turbine efficiency by maintaining a proper vacuum by condensing steam, removing dissolved non condensable gases from the condensate and conserving the condensate for re-injection or as feed water for the cooling tower. As the operating pressure of the condenser is lowered (vacuum is increased), the enthalpy drop of the expanding steam in the turbine will also increase. This will increase the amount of available work from the turbine (and thus electrical output).”
- Najafabadi, A., “Geothermal Power Plant Condensers in the World”, Proceedings WGC2015