Fuel Staging Valve Recirculation for Gas Turbine
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Solution Overview
Problem
The existing fuel systems for gas turbine engines face issues with fuel stagnation in lines and manifolds, leading to thermal degradation and lacquering, which negatively impact system operation due to high temperature zones that fuel passes through.
Innovation Solution
A fuel staging system with a staging valve that divides the fuel supply between pilot and mains delivery lines, and a recirculation valve to maintain fuel circulation when no fuel is delivered to the mains line, preventing stagnation and degradation by allowing fuel to recirculate back to a low-pressure zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the staging valve delivers no fuel to the mains delivery line, then fuel consumption is reduced, but fuel stagnation and thermal degradation occur in the mains delivery line
Solution Approach 1:
The recirculation valve maintains continuous fuel circulation through the mains delivery line even when the staging valve closes off fuel delivery to the mains burners. This continuous flow prevents fuel stagnation and thermal degradation, ensuring the fuel system remains reliable and ready for immediate operation when fuel delivery is resumed.
Solution Approach 2:
The recirculation valve acts as an intermediary mechanism that creates a separate circulation path for fuel. When the staging valve closes the main fuel delivery path, the recirculation valve opens an alternative path allowing fuel to circulate through the mains delivery line and return to the low-pressure zone, preventing stagnation without requiring main fuel delivery.
2Reliability
If fuel circulates continuously through the mains delivery line, then fuel degradation is prevented, but fuel consumption increases
Solution Approach 1:
The recirculation valve provides partial fuel circulation rather than full delivery to the mains burners. This partial action is sufficient to prevent fuel stagnation and thermal degradation in the mains delivery line, while consuming significantly less fuel than would be required for complete fuel delivery to the burners.
3Reliability
If the recirculation valve is opened, then fuel stagnation is prevented, but system complexity increases
Solution Approach 1:
The recirculation valve is integrated with the staging valve assembly, combining two valve functions into a single structural unit. This merging reduces overall system complexity compared to having completely separate valve assemblies, while still providing the necessary recirculation capability to prevent fuel stagnation.
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 solution effectively reduces thermal degradation and lacquering, ensuring efficient fuel management and maintaining system performance by preventing fuel stagnation and maintaining a uniform pressure drop across the staging valve.
Implementation Method 1
a recirculation valve connected to the mains delivery line and operable to permit a recirculation fuel flow to be supplied to the mains delivery line
Implementation Method 2
a staging valve operable to divide a metered fuel supply between a pilot delivery line and a mains delivery line
Implementation Method 3
the fuel lines carrying this fuel to the combustion chamber of the engine pass through a bypass duct and around the engine core, both of which are high temperature zones, and as a result significant heat transfer to the fuel can occur
Data Source
AI summary
A fuel staging system is described which comprises a staging valve 28 operable to divide a metered fuel supply between a pilot delivery line 18 and a mains delivery line 16, and a recirculation valve 54 connected to the mains delivery line 16 and operable to permit a recirculation fuel flow to be supplied to the mains delivery line 16 when the staging valve 28 occupies a position in which substantially no fuel is delivered to the mains delivery line 16 through the staging valve 28.