A STUDY OF THERMODYNAMIC CYCLE AND SYSTEM CONFIGURATIONS OF HYDROGEN COMBUSTION TURBINES

A hydrogen combustion turbine is powered by steam generated from the i nternal combustion of hydrogen as a Fuel mixed with stoichiometric oxy gen. As it is possible to use a closed cycle system, benefits in cycle efficiency and a reduction of environmental pollution effects. Three different closed hydrogen combustion turbine cycles are evaluated. The se are the Bottoming reheat cycle (A), the Topping extraction cycle (B ) designed by Jericha and Ratzesberger, and the Rankine cycle (C). Cal culations have been carried out to investigate the best cycle. This in vestigation consists of the comparison of thermodynamic efficiency, fi rst stage turbine vane height of the high temperature, high pressure t urbine, and maximum operating temperature of the heat exchangers. In t hese investigations, the component efficiencies are assumed to be the values which are expected to be achieved in the near future. As a resu lt, the thermal efficiency of cycles (A) and (B) is the same value of 61.5%. That of cycle (C), which has the feed water heating with optimi zed pressure ratio of the intermediate turbine, is 58.8%. Cycle (B) ha s the largest first stage turbine vane height of the high temperature/ high pressure turbine. The larger vane height has an advantage from th e point of view of both the manufacturing of the complex cooling passa ge inside the vane and the turbine aerodynamic efficiency. The maximum operating temperature of the heat exchanger of cycles (A) and (B) is 870 degrees C, while that of cycle (C) is more than 1000 degrees C whe re some problems are anticipated in the feasibility of this heat excha nger. This investigation shows that the Topping extraction cycle (B) i s considered to be the best cycle from the point of view of both the t hermal efficiency and the feasibility of manufacturing. (C) 1998 Inter national Association for Hydrogen Energy.