EXERGETIC ANALYSIS OF A COGENERATION POWER PLANT

Abstract

Cogeneration power plants connected to industrial processes have a direct impact on the overall efficiency of the plant and therefore on the economic results. Any modification to the thermal outline of these plants must first include an exergetic analysis to compare the benefits it can bring the new proposal. This research is performed to a cogeneration plant in operation with an installed electrical capacity of 24 MW and process heat demand of 190 MW, it shows a study made from the Second Law of Thermodynamics. Exergetic evaluation of each component of the plant was applied and similarly modified cogeneration scheme was evaluated. The results illustrate that the exergy losses and irreversibilities are completely different from one subsystem to another. In general, the total exergy destruction represented 70,7% from the primary fuel exergy. Steam generator was the subsystem with the highest irreversibility of the plant with 54%. It was demonstrated that the increase of the steam parameters lead to reduce exergy destruction and exergy efficiency elevation. The suppression of the reduction system and the adding of an extraction-condensing steam turbine produce the same effect and contribute to drop off the electrical consumption from the grid.