Combined cycle power unit with a binary system based on waste geothermal brine at Mutnovsk geothermal power plant

Abstract

The Russian geothermal power systems developed in the last few decades outperform their counterparts around the world in many respects. However, all Russian geothermal power stations employ steam as the geothermal fluid and discard the accompanying geothermal brine. In reality, the power of the existing Russian geothermal power stations may be increased without drilling more wells, if the waste brine is employed in combined cycle systems with steam and binary turbine units. For the example of the 50 MW Mutnovsk geothermal power plant, the optimal combined cycle power unit based on the waste geothermal brine is considered. It is of great interest to determine how the thermodynamic parameters of the secondary steam in the expansion unit and the pressure in the condenser affect the performance of the equipment in the combined cycle power unit at Mutnovsk geothermal power plant. For the utilization of the waste geothermal brine at Mutnovsk geothermal power plant, the optimal air temperature in the condensers of the combined cycle power unit is +5°C. The use of secondary steam obtained by flashing of the geothermal brine at Mutnovsk geothermal power plant 1 at a pressure of 0.2 MPa permits the generation of up to 8 MW of electric power in steam turbines and additional power of 5 MW in the turbines of the binary cycle.