Combined Cycle Exhaust Gas Recirculation Intercooling for Turbine Cooling

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Solution Overview

Problem

Gas turbine components are strained by high temperature flows, reducing their service life and efficiency, and existing cooling methods using compressor bleed air decrease overall system efficiency.

Innovation Solution

Implementing exhaust gas recirculation with intercooling by compressing and cooling a portion of the exhaust gas stream for recirculation to the gas turbine engine, and modulating its flow and temperature using a controller to maintain optimal operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If compressor bleed air is used for cooling components, then component cooling is achieved, but overall system efficiency decreases

Engineering Contradiction:

Improvecomponent temperatureVSAvoidsystem efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The invention converts the harmful hot exhaust gas that would otherwise be wasted into a beneficial cooling resource. By recirculating exhaust gas through the compressor interstage, the system uses this thermal energy to cool compressed air, reducing the need for compressor bleed air and improving overall system efficiency while still achieving component cooling objectives

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system changes the temperature parameter of the compressed air by introducing cooler recirculated exhaust gas into the compressor interstage. This parameter change allows the compressed air to be cooled without extracting bleed air from the compressor, thereby maintaining system efficiency while achieving the required cooling effect for component protection

Inventive Principle:

Principle #35Parameter changes

2Power

If gas turbine operates at higher temperature, then power output and efficiency increase, but component service life decreases

Engineering Contradiction:

Improvepower outputVSAvoidcomponent service life

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The system performs preliminary cooling of the compressed air before it enters the combustor by introducing recirculated exhaust gas into the compressor interstage. This preliminary action reduces the temperature of the air entering the combustion zone, which indirectly protects downstream components from excessive thermal strain while allowing the turbine to operate at higher temperatures for increased power output

Inventive Principle:

Principle #10Preliminary action

3Temperature

If exhaust gas is recirculated through compression and cooling, then compressor exit temperature is reduced, but system complexity increases

Engineering Contradiction:

Improvecompressor exit temperatureVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The recirculated exhaust gas serves multiple functions simultaneously: it acts as a cooling medium for the compressor interstage, serves as a diluent to reduce combustion temperatures, and functions as a source of thermal energy that would otherwise be wasted. This multi-functionality reduces the need for separate cooling systems and auxiliary components, thereby limiting the increase in system complexity while achieving effective temperature reduction

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances gas turbine performance by reducing compressor exit temperature, extending component life, and increasing power output while minimizing system complexity and cost.

Implementation Method 1

extracting heat from the first exhaust gas stream via a heat recovery steam generator

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

cooling the pressurized stream to discharge a cooled stream using a first cooler

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentUS12385437B2Combined cycle power plants with exhaust gas recirculation intercooling

Publication Date: 2025.08.12 GENERAL ELECTRIC CO

AI summary

A method of operating a combined cycle power plant to facilitate increasing an output of the power plant. The method includes discharging a first exhaust gas stream from a gas turbine engine and extracting heat from the first exhaust gas stream via a heat recovery steam generator. The method also includes discharging a second exhaust gas stream from the heat recovery steam generator, pressurizing a first portion of the second exhaust gas stream using a recirculation compressor, and cooling the first portion of the second exhaust gas stream using a first cooler. The method further includes discharging a cooled exhaust gas stream from the first cooler to the gas turbine engine and modulating, via a controller, a flow and a temperature of the first portion of the second exhaust gas stream recirculated towards the gas turbine engine.