Heat exchanger design considerations for gas turbine HTGR power plant

For an integrated plant configuration, a nonintercooled cycle with a high degree of heat recuperation was selected on the basis of performance and economic optimization studies. A recuperator of high effectiveness was chosen because it significantly reduces the optimum pressure ratio (for maximum cycle efficiency), and thus reduces the number of compressor and turbine stages for the low molecular weight, high specific heat, helium working fluid. Heat rejection from the primary system is effected by a helium-to-water precooler, which cools the gas to a low level prior to compression. The high heat transfer rates in the recuperator and precooler, combined with the envelope restraints associated with heat exchanger integration in the prestressed concrete reactor vessel, require the use of more compact surface geometries than in contemporary power plant steam generators. Various aspects of surface geometry, flow configuration, mechanical design, fabrication, and integration of the heat exchangers are discussed for a plant in the 1100 MWe class.