Modified Exhaust-Heated Gas Turbine Cycle With Increased Thermal Efficiency and its Prospect for Industrial Application

Abstract

A kind of developed exhaust-heated cycle arrangement comprising two or three reheaters and three intercoolers as well as an extra primary air blower (atmospheric combustion) is proposed. As far as classical exhaust-heated cycle is concerned, its thermal efficiency is quite low (15–20%) and therefore, a conception of a developed system provided with additional heat exchangers and combustion chambers has been worked out. The proposed installation operates on natural gas, which is becoming more and more popular now. A numerical example of calculation of a plant of 5250 kW effective power is presented. The “free-shaft” principle has been adopted. All the compressors are driven by a set of two turbines and the other two turbines are used for driving the electric generator. (Extra power that could be obtained from natural gas expander was not taken into account). In general it may be stated that the modified exhaust-heated cycle arrangement may compete with closed cycle turbine arrangements (e.g. Escher Wyss type). Moreover it may — to some extent — be superior to semi-closed cycle arrangements, since in the system proposed all the turbines are driven by compressed air whereas in the semi-closed cycle two turbines are driven by combustion gases.