Design Improvements of Power Conversion System of Gas Turbine High Temperature Reactor (GTHTR300)

The power conversion system for GTHTR300 with a power output 274 MWe was designed to operate on regenerative closed-cycle with the turbine inlet helium gas temperature 850 °C and pressure 7.0 MPa. Horizontal single-shaft, axial-flow turbo-compressor and directly coupled electric generator by diaphragm-coupling are suspended by magnetic bearings. The study aimed to reduce the total mass of the plant by selecting non-inter-cooled-cycle and improving the performance of the main system components. Three-dimensional aerodynamic design of the turbo-compressor predicted high polytropic efficiencies of 93% and 90% respectively, while keeping high surge margin of 30% for compressor, which resulted in net generation efficiency of 45.6%. The turbo-machine rotor, which passed over critical speeds of the bending mode, fulfilled the standard limit of vibration amplitude of 75 μm at the rated rotational speed by optimising stiffness of the magnetic bearings. Plate-fin type recuperator with off-set fin arrangement minimized size and mass with square cross section of 1.2 mm × 1.2 mm, while fulfilling the target temperature effectiveness of 95%.