Energy, exergy and economic (3E) analysis of integrated solar direct steam generation combined cycle power plant

In this paper, energy, exergy and economic (3E) analyses have been performed on a conceptual power plant cycle formed by integrating solar energy in steam cycle of a natural gas fired combined cycle power plant (CCPP). Solar integration has been done at medium temperature level using direct steam generation (DSG) technique with parabolic trough collectors. A portion of the feed water leaving the high pressure economiser-1, goes to the solar field for preheating and evaporation. As the feed water passes through the absorber tubes of the solar field, part of it is evaporated into steam. The water-steam mixture leaves the solar field and enters a separator placed at the end of the solar collector field. The separator separates the steam from the water-steam mixture. The water is sent back to the solar field using a recirculation pump whereas the separated dry steam leaving the separator is allowed to mix with the dry saturated steam leaving the high-pressure drum. Superheating of steam takes place in the heat recovery steam generator (HRSG). The results have shown that the energy and exergy efficiencies of solar field are 53.79% and 27.39% respectively. The results have shown that plant output has increased by 7.84% with solar field operating at design point for a 50 MWth nominal solar field capacity. The levelised cost of electricity generation has been observed to be lowered from 7.4 to 6.7 cents/kW h.