Efficiency improvement of gas turbine cogeneration systems

Abstract

Original scientific paper In this study eight methods are evaluated for a gas turbine cogeneration cycle to improve the efficiency. These methods are increasing gas turbine inlet air temperature, cooling the inlet air of the compressor, air preheating, fuel preheating, increasing compressor inlet air pressure, increasing air excess rates, steam injection, and humidification of the inlet air of the compressor. These methods are studied in order to compare their effects on the performance of the systems. The effects of these methods on the exergetic efficiency depend on the kind of the cogeneration cycle. By combining recuperation, preheating fuel and steam injection methods high efficiency can be achieved. The combined methods give the best results under variable heat demands of the market. An appropriate combination of the efficiency improvement methods may increase the exergetic efficiency about 20 %. The results show that efficiency improvement methods must be applied together whenever it is possible. Keywords: cogeneration; efficiency; improvements Poboljšanje učinkovitosti kogeneracijskih sustava plinske turbineIzvorni znanstveni članak U radu se procjenjuje osam metoda za poboljšanje učinkovitosti kogeneracijskog ciklusa plinske turbine. Tim se metodama povećava temperatura ulaznog zraka plinske turbine, rashlađuje ulazni zrak kompresora, predgrijava zrak, predgrijava gorivo, povećava tlak ulaznog zraka kompresora, povećava brzina viška zraka, ubrizgava para i vlaži ulazni zrak kompresora. Te se metode istražuju kako bi se usporedilo njihovo djelovanje na performanse sustava. Učinci tih metoda na egzergetsku učinkovitost ovise o vrsti kogeneracijskog ciklusa. Kombiniranjem metoda rekuperacije, predgrijavanja goriva i ubrizgavanja pare može se postići visoka učinkovitost. Kombinirane metode daju najbolje rezultate kod različitih potreba tržišta za toplinom. Odgovarajućom kombinacijom metoda za poboljšanje učinkovitosti može se povećati egzergetska učinkovitost za oko 20 %. Rezultati pokazuju da se metode za poboljšanje učinkovitosti moraju primijeniti zajedno kada je god to moguće.

Thermodynamic Analysis of Effects of the Inlet Air Cooling on Cycle Performance in Combined Brayton-Diesel Cycle

“…Different methods to improve efficiency gas turbine cogeneration cycle are studied by [20]. In these methods, they investigated the increase in gas turbine inlet air temperature, cooling the compressor inlet air, air preheating, fuel preheating, increasing the compressor inlet air pressure, increasing the excess air rate, steam injection, and humidification of the compressor inlet air.…”

Performance Optimization of Combined Gas and Steam Power Plant using Matrix Laboratory (MATLAB)

“…Cogeneration systems can work with high capacity and high efficiency nearly all year. Cogeneration systems save 30 % more energy than conventional energy systems [1]. Thermodynamically, when two thermal cycles are combined in a single power plant the efficiency that can be achieved is higher than that of one cycle alone and energy is conserved [2].…”