NEW APPROACH FOR INCREASING THE THERMAL EFFICIENCY OF STEAM POWER CYCLES.

The paper presents a modification of the super-critical steam power cycle that allows operation at pressures as high as 42 MPa with improved efficiency. The modification is confined to the high pressure end of the cycle and requires a limited extrapolation of present technology. The essence of the modification lies in augmenting the mass flow rate at the admission end of the turbine, thus allowing for efficient design of this part, while maintaining a manageable volume flow rate at the exhaust end. The added mass flow rate in the super-pressure turbine is extracted for high-temperature regenerative feedwater heating between feedwater pump and supercritical steam generator. This results in a higher average temperature of heat addition and, consequently, in a higher thermal efficiency. At an initial steam temperature of 540 C, the modified cycle is about 4 percent more efficient than the conventional one and produces about 8 percent more work without increasing the mass flow rate in the low pressure turbine.