HIGHLY SUPERCHARGED GAS TURBINE AND POWER GENERATING SYSTEM

摘要

A highly supercharged gas-turbine generation system include a gas turbine power plant that is supercharged to a high inlet pressure, preferably over about 1.15 pressure ratio and preferably includes a transmission system with refrigerated transformers for increased output. The gas turbine power plant includes a precompressor (24) that supercharges to a design pressure ratio of about 1.20 to 10, with a preferred pressure ratio of about 2. For high supercharging pressures, a pressure-reducer (456) is located downstream of the gas turbine (20) to maintain turbine outlet pressure that is close to the inlet pressure. The pressure-reducer is preferably an expander (26), but can alternatively be an orifice (450). A torque-limiting coupling (56) on the shaft between the gas turbine (20) and the generator (52) prevents transient overload of the shaft. Capacity of the gas turbine plant is preferably controlled by varying supercharging pressure. The expander preferably has variable-pitch blades (34) to allow sufficient variation of turbine outlet pressure. For combined-cycle embodiments, a heat-recovery steam generator (HRSG) (60) may be placed between the gas turbine (20) and a downstream expander. For highest combined cycle output, a single-pressure steam system with high inlet temperature to the HRSG is preferred. The high temperature is preferably provided by supplemental firing between the gas turbine and the HRSG. An expander may be inserted between the supplemental firing and the HRSG to further improve cycle efficiency and to reduce pressure in the HRSG. For retrofit applications with limited supercharging, a refrigeration system for generator cooling may be added to increase generator output to match that available from the supercharged gas turbine.