Thimble Assemblies for Cross-Flow Combustion
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Solution Overview
Problem
Existing gas turbine combustors with axial fuel staging systems face challenges in assembly and leak detection due to complex fuel line configurations, which restrict the use of highly reactive fuels due to the risk of combustion within the high-pressure, high-temperature environment.
Innovation Solution
The introduction of a thimble assembly and injector unit configuration where the fuel injection assemblies have a main fuel inlet external to the forward casing, reducing the risk of leaks and allowing for the use of highly reactive fuels by thermally isolating the fuel supply lines and eliminating the need for fuel seals within the combustor enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fuel lines are attached to the combustor liner within the combustor casing, then fuel can be delivered to AFS injectors, but assembly becomes challenging and leak detection becomes difficult
Solution Approach 1:
The fuel delivery system is extracted from the combustor casing interior and relocated to the exterior. The fuel manifold and lines are now positioned outside the combustor casing, eliminating the complexity of internal fuel line routing and assembly within the high-temperature combustion environment.
2Reliability
If fuel lines are located within the combustor casing, then fuel delivery is achieved, but the risk of fuel leaks and combustion increases
Solution Approach 1:
The fuel lines are extracted from the high-temperature combustor casing environment and relocated to the exterior where they operate in a cooler, safer environment, reducing the risk of fuel leaks causing combustion within the casing.
Solution Approach 2:
A fuel manifold serves as an intermediary component that receives fuel from external lines and distributes it to the AFS injectors through a controlled interface, isolating the fuel delivery system from the combustor casing and reducing leak risks.
3Power
If highly reactive fuels are used in existing combustors with AFS injectors, then energy output increases, but the risk of combustion from leaked fuel within the high-pressure, high-temperature environment increases
Solution Approach 1:
The fuel delivery infrastructure is extracted from the high-pressure, high-temperature combustor environment and positioned externally, creating a safer operational environment for highly reactive fuels while maintaining their energy benefits.
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 configuration enhances reliability, facilitates inspection and maintenance, and allows for the use of a wide range of fuels, including highly reactive ones, by reducing the risk of ignition and coking, while improving the mixing efficiency of fuel and air in the secondary combustion zone.
Implementation Method 1
a flow path from an inlet opening to an outlet opening
Implementation Method 2
introduces a flow of fuel into a flow of air flowing through the thimble, such that fuel and air are injected into the secondary combustion zone
Data Source
AI summary
A thimble assembly, which directs fluid flow through a combustor liner, includes a thimble boss and a thimble. The thimble boss is mounted an outer surface of the liner and surrounds a liner opening, thus defining a thimble boss passage. The thimble is disposed through the passage and the liner opening. The thimble wall extends from an inlet portion to an outlet of the thimble. The inlet portion has a greater diameter than the outlet and defines an inlet plane and a parallel intermediate plane. A terminal plane, parallel to the intermediate plane, includes an array of points most distant from a corresponding array of points defining the intermediate plane. The thimble wall has a non-uniform length, such that the outlet of the thimble is oriented at an oblique angle relative to the terminal plane. The thimble wall may have an arcuate shape defined as one-fourth of an ellipse.