Efficient Power Generation From Large 750°C Heat Sources: Application to Coal-Fired and Nuclear Power Stations

Considering the concern about a more efficient, rational use of heat sources, and a greater location flexibility of power plants owing to cooling capability, closed gas cycles can offer new solutions for fossil or nuclear energy. An efficient heat conversion into power is obtained by the combination of a main non-intercooled helium cycle with a flexible, superheated, low-pressure bottoming steam cycle. Emphasis is placed on the matching of the two cycles and, for that, a recuperator bypass arrangement is used. The operation of the main gas turbocompressor does not depend upon the operation of the small steam cycle. Results are presented for a conservative turbine inlet temperature of 750 C. Applications are made for a coal-fired power plant and for a nuclear GT-HTGR. Overall net plant efficiencies of 39 and 46 percent, respectively, are projected.