Compressor Flow Control for Gas Turbine Combustor
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Solution Overview
Problem
In gas turbines, the compressed working fluid flowing through late lean fuel injectors during non-base load operations causes air dilution of combustion gases, leading to undesirable emissions and high temperatures in hot gas path components, necessitating a system to control the air flow rate effectively.
Innovation Solution
A system comprising an outer casing with an extraction port and an inlet port, a baffle for flow separation, and a flow modulation valve in an external fluid circuit to control the air flow rate of the compressed working fluid to the fuel injectors, allowing for precise modulation of the air flow between a high pressure plenum and an injection air plenum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the compressed working fluid is routed through the late lean fuel injectors during non-base load operations, then the injectors can be used for base load operation, but air dilution of combustion gases occurs causing undesirable emissions and high temperatures
Solution Approach 1:
The harmful compressed working fluid flow is extracted from the combustor system by routing it through a separate external fluid circuit that bypasses the fuel injectors during non-base load operations, eliminating air dilution and harmful emissions while preserving the capability to use injectors during base load operation
Solution Approach 2:
The fluid circuit is segmented into separate paths: an internal circuit through the fuel injectors for base load operation and an external circuit for non-base load operations, allowing independent control of each path to avoid harmful interactions
2Reliability
If compressed working fluid flows through the fuel injectors and mixes with combustion gases, then the injectors remain passive during non-base load operation, but this causes air dilution requiring over-firing of fuel nozzles which increases component temperatures
Solution Approach 1:
The compressed working fluid flow is extracted from the combustor system by routing it through an external fluid circuit that bypasses the fuel injectors during non-base load operations, eliminating air dilution and the need for over-firing, thereby preventing excessive temperatures in combustion liner and transition duct components
Solution Approach 2:
An external fluid circuit acts as an intermediary path for the compressed working fluid, providing an alternative route that prevents direct flow through the fuel injectors and subsequent mixing with combustion gases, thereby eliminating the temperature problem
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
This system effectively reduces air dilution and emission levels, prevents overheating of hot gas path components, and enhances the thermodynamic efficiency of the combustor by allowing for controlled air flow during various operation modes.
Implementation Method 1
A baffle extends radially between the outer air shield and the outer casing. The baffle provides flow separation between the inlet passage to the injection air plenum and the high pressure plenum.
Implementation Method 2
A flow modulation valve in an external fluid circuit to control the air flow rate of the compressed working fluid to the fuel injectors
Implementation Method 3
A portion of the compressed working fluid exiting the compressor is routed through the fuel injectors to mix with fuel to produce a lean fuel-air mixture.
Implementation Method 4
The compressed working fluid mixes with fuel in the one or more fuel nozzles and/or within the combustion chamber and ignites to generate combustion gases having a high temperature and pressure.
Data Source
AI summary
A system for controlling air flow rate of a compressed working fluid to a fuel injector of a combustor includes an outer casing that defines a high pressure plenum around a portion of the combustor, an extraction port in fluid communication with the high pressure plenum and an inlet port. The combustor includes a plurality of fuel injectors arranged around a combustion liner, an inner flow sleeve, an outer air shield that surrounds the plurality of fuel injectors and the inner flow sleeve. The outer air shield defines an injection an air plenum between the outer air shield and the inner flow sleeve and an inlet to the injection air plenum. An external fluid circuit provides fluid communication between the extraction port and the inlet port. A baffle extends between the outer casing and the outer air shield to provide flow separation between the inlet and the high pressure plenum.