Exergy Analysis of Double Flash Geothermal Power Plant, SABALAN, IRAN

摘要

The Mt Sabalan geothermal field in NW of Iran is currently under development. A double flash cycle has been selected for power generation. The obtained results show that the maximum power output from the plant can be 54 MWe with pressures equal to 5.5, 0.9 and 0.1 bar for high and low pressure steps and condenser, respectively. Mathematical models for energy and exergy flows were developed and implemented in the Engineering Equation Solver (EES) software. A few assumptions and simplifications were made. The energy and exergy rates of the waste brine have been calculated as 18.7% and 15.8% of the total available energy and exergy rates, respectively. The separated brine can be used as a heat source for a district heating system or some other forms of direct use. Reinjection should also be taken into account. The parts of the system with largest exergy destruction are the condenser, the low-pressure turbine, the low pressure separator and the disposed waste brine. The overall exergy efficiency for the power plant is 45.2% and the overall energy efficiency is 9.4%. Exergy analysis was found helpful and important tool for analyzing the geothermal plant and should be considered at early stages of designs.