PERFORMANCE EVALUTION AND EXERGY ANALYSES OF AN INTEGRATED SOLAR COMBINED CYCLE POWER PLANT

Abstract

The present study is aimed to develop an integrated solar combined cycle power plant in which steam generator gets its energy by recovering the wasted heat of a gas turbine unit. The plant included also a concentrating collector field to heat the water coming from condenser replacing the regenerative process in Rankine cycle. In such a way, the extracted steam used for regenerative cycle can be used in other applications such as, heating process, desalination,…etc (Co-generation cycle). Producing saturated steam and superheating process are taken place in steam generator via recovering the wasted heat accompanying the exhaust gases of the gas turbine. An auxiliary heater is used at lower or less solar radiation times. A simulation mathematical model has been developed for each component of the plant and the components are matched together. This model is used to predict the temperatures, mass and heat transfer within the system under various operating and design conditions. The influence due to extracting a variable amount of steam for heating process is studied in the paper. The studied parameters included the contributions of the solar as well as the wasted energy with the products of the gas turbine. An exergy analyses for the main components of the plant are considered in the study. The final results showed that the solar energy can contribute by about 27 % from the total energy supplied to Rankine cycle whereas the energy recovery from the wasted energy of the gas turbine can contribute by about 64 %. The remaining part is covered by an auxiliary heater. The values of the efficiencies reached to about, 54 % for the solar collector, 46 % for the gas turbine, 43 % for the utilization factor of the steam turbine and 45 % for overall efficiency of the solar integrated combined cycle power plant. Also, the most exergy destruction in the plant occurred in the solar concentrator (about 33 % of the incident radiation), and the combustion chamber of the gas cycle (about 39 % of the input heat). Other components such as, compressor, gas turbine, steam turbine, and condenser, having an exergy destruction ranges from 1 % up to 5 % from the corresponding energy input to each component.