Solar parallel feed water heating repowering of a steam power plant: A case study in Iran

Currently, the use of renewable energies is put on the agenda of most researchers in the field of energy. On the other hand, in many parts of the world, fossil fuel power plants continue to be the main source of electrical power. Increased efficiency of fossil fuel power plants and the use of solar energy lead to recommendation of merging solar farms with the cycle of these power plants. The statistics indicate that the output of fossil fuel power plants in Iran, which currently supply about 93.9% of electricity of the national network, is experiencing a negative growth. On the other hand, according to government plans, part of the generated electricity should be provided from renewable energy sources in the next few years. In this paper, the use of solar energy for integration with power-plant units of Isfahan is investigated. To do this, preheat project of the feed water is investigated on 7 separate scenarios. The results showed that replacing all high-pressure feed water preheaters with solar farm increases the net energy and exergy efficiencies of the power plant by 18.3% compared to the simple cycle which respectively reaches to 45% and 43.91%. Given the importance of reducing emissions of CO2 pollutants at power plants, reduction level of gas emissions, as well as some economic aspects of the integration of solar farm with the cycle of this power plant has also been evaluated.