Performance assessment of hybrid solar energy and coal-fired power plant based on feed-water preheating

Hybridizing solar energy and coal-fired steam power plant is one of most attractive approaches of cost-efficient solar electricity in the present. By using the concentrated solar heat at around 300 °C to replace the bleed steam of the turbine for preheating feed-water of coal-fired steam cycle, higher solar-to-power efficiency is possibly achieved in that the conversion of solar to power can utilize higher-temperature steam cycle. In this paper, with the aid of exergy methodology, we derive expressions of the conversion of solar energy into power for such kind of solar hybrid plant, especially an explicit correlation is obtained for explaining solar-to-power efficiency. By using the derived expressions, we examine a typical hybrid solar system with 330 MW coal-fired power plant and evaluate thermal performance of solar-to-power. In addition, the influences of key operation parameters on the solar thermal performance are disclosed such as solar irradiation, incident angle and turbine load. The results obtained here would be expected to provide a possibility for designing and evaluating practical hybrid solar and coal-fired power plant.