Axial Fuel Staging Injection Assembly External Routing
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Solution Overview
Problem
Existing gas turbine combustors with axial fuel staging systems face challenges in assembly and leak detection, particularly when using highly reactive fuels, due to the complexity of fuel supply lines within the combustor casing, which can lead to ignition risks and limited fuel options.
Innovation Solution
The axial fuel staging system incorporates a thimble assembly and injector unit design 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 fuel supply lines outside the combustor casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fuel supply lines are located within the combustor casing, then assembly is simplified, but leak detection becomes difficult and ignition risk increases
Solution Approach 1:
The fuel supply lines are extracted from the combustor casing interior and repositioned to run externally along the outer surface of the casing. This allows fuel lines to be easily accessible for assembly while enabling straightforward leak detection through visual inspection of the external routing path.
2Ease of manufacture
If fuel supply lines are located within the combustor casing, then assembly is simplified, but ignition risk increases due to leaked fuel in high-temperature environment
Solution Approach 1:
The fuel supply lines are extracted from the high-temperature combustor casing interior and repositioned externally. This physical separation removes leaked fuel from the high-temperature environment that could cause ignition, while maintaining assembly simplicity through external accessibility.
Solution Approach 2:
A cooling air flow path is introduced as an intermediary barrier between the fuel supply lines and the hot combustion zone. Cooling air is directed along the external fuel line routing to create a thermal buffer, further reducing ignition risk while allowing external fuel line placement.
3Adaptability or versatility
If fuel supply lines are thermally isolated outside the combustor casing, then use of highly reactive fuels becomes possible, but system complexity increases
Solution Approach 1:
The fuel supply lines are extracted from the hot combustor environment and routed externally with thermal isolation. This enables the use of highly reactive fuels by preventing premature ignition, while the complexity is managed through the straightforward external routing approach that leverages the existing combustor outer surface for line placement.
Data Source
AI summary
An injection assembly for a gas turbine combustor having a liner defining a combustion zone and a secondary combustion zone and a forward casing circumferentially surrounding at least a portion of the liner is provided. The injection assembly includes a thimble assembly and an injector unit. The thimble assembly, which is mounted to the liner, includes a thimble that extends through a thimble aperture in the liner. The injector unit, which is mounted to and extends through the forward casing, includes an injector blade that extends into the thimble. The injection assembly 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 in a direction transverse to a flow of combustion products from the primary combustion zone.