Proposal of Chemical Gas Turbine and Characteristics of Pressurized Low-NOx Chemical Combustion

A new concept of highly efficient gas turbine/steam turbine combined cyc le system with Chemical Gas Turbine was proposed in order to break through the turbine inlet temperature and the thermal efficiency in the present state. The chemical gas turbine consists of a combustor operated under fuel-rich and high pressure and C/C composite material adopted as turbine blade. The thermal efficiency of the combined system was estimated. From the calculation under the condition of the temperature at 1500°C, it is clear that the gas turbine efficiency is 44% and the thermal efficiency of the combined cycle system could be 66%. The efficiency of the system is much higher than that of conventional one. As one of the most crucial technologies for the development of this proposed chemical gas turbine, a lab-scale combustor in which fuel-rich combustion can be realized under pressurized condition, was designed and the combustion characteristics were examined theoretically and experimentally. It was found that the flammability limit extended with increasing the equivalence ratio in fuel-rich side while it was constant in fuel-lean side, and that the emissions of NOx decreased drastically with increasing the equivalence ratio in fuel-rich side. and with increase of the operating pressure as well. These encourage us to advance the research and development of the proposed gas turbine system.