Highly Supercharged Gas Turbine Generating System

Abstract

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 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 is located downstream of the gas turbine to maintain turbine outlet pressure that is close to the inlet pressure. The pressure-reducer is preferably an expander, but can alternatively be an orifice. A torque-limiting coupling on the shaft between the gas turbine and the generator 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 to allow efficient variation of turbine outlet pressure. For combined-cycle embodiments, a heat-recovery steam generator (HRSG) may be placed between the gas turbine 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.

1 . In an E-, F-, G- or H-class gas turbine having a compressor, a combustor, an expander, and an output shaft connected between said compressor and expander, said turbine having a predefined maximum design operating torque at a predefined design pressure ratio, the improvement comprising:
 increasing the amount of power outputted by said gas turbine by:   adding a system for variably increasing mass flow through said turbine to increase operating pressure ratio above said design pressure ratio; and   strengthening said output shaft to handle an operating torque exceeding said maximum design operating torque.   
   
   
       2 . In an E-, F-, G- or H-class gas turbine as set forth in  claim 1 , the improvement further comprising:
 strengthening stator components in said compressor and expander to withstand increased forces associated with increased mass flow from said added system.   
   
   
       3 . In an E-, F-, G- or H-class gas turbine as set forth in  claim 1 , the improvement further comprising:
 strengthening a pressure enclosure of said combustor to withstand higher operating pressures associated with increased mass flow from said added system.   
   
   
       4 . In an E-, F-, G- or H-class gas turbine as set forth in  claim 1 , the improvement further comprising:
 adding a torque-limiting coupling between said output shaft and a load on said output shaft to prevent transient overloads associated with increased mass flow from said added system.