Cooled Flameholder Swirl Cup Combustor Design
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Solution Overview
Problem
Gas turbine combustors face challenges in achieving dry low emissions performance while maintaining combustion stability and durability, as operating lean to reduce nitrogen oxide emissions can lead to instability and overheating, and traditional designs compromise between fuel consumption, emissions, and structural integrity.
Innovation Solution
A combustor design featuring coaxial inner and outer swirl cups with a tubular centerbody and internal impingement ring for cooling the flameholder, which anchors the lean premixed flame and reduces instability by using bypass cooling air to impinge on the flameholder, enhancing stability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the combustor operates lean to reduce nitrogen oxide emissions, then emissions are reduced, but combustion stability is decreased
Solution Approach 1:
A flameholder is introduced as an intermediary component to anchor the lean premixed flame. The flameholder provides a stable reference point for the flame front, preventing combustion instability and acoustic pressures that would otherwise occur during lean operation. This mediator enables the combustor to maintain stable combustion at lean fuel-air ratios, thereby reducing nitrogen oxide emissions while preserving combustion stability.
Solution Approach 2:
The invention changes the operational parameters by anchoring the flame at a specific location using the flameholder, which allows the combustor to operate at leaner fuel-air ratios without sacrificing stability. This parameter change enables sustained lean combustion that reduces nitrogen oxide emissions while the flameholder ensures the combustion process remains stable through proper flame anchoring.
2Stability of the object's composition
If a flameholder is introduced to anchor the lean premixed combustion flame, then combustion stability is improved, but the flameholder overheats and durability is decreased
Solution Approach 1:
A cooling air passage is integrated into the flameholder structure, utilizing pneumatic flow of cooling air to remove heat from the flameholder. The cooling air flows through internal passages and exits via cooling holes on the flameholder surface, creating a protective cooling film that prevents overheating. This pneumatic cooling system enables the flameholder to maintain structural integrity and durability while continuously anchoring the combustion flame.
Solution Approach 2:
The cooling air undergoes phase-related thermal transformations as it passes through the flameholder - being heated by conduction from the hot flameholder surface and then discharged to cool subsequent portions of the flameholder. This thermal phase management through the cooling air flow prevents localized overheating and extends flameholder life while maintaining combustion stability.
3Duration of action of stationary object
If cooling air is provided through the centerbody to impinge on the flameholder, then flameholder durability is improved, but device complexity is increased
Solution Approach 1:
The cooling air passage is merged with the centerbody structure, integrating the cooling function into an existing structural component rather than adding a separate cooling system. The centerbody serves dual purposes: structural support and cooling air delivery. This merging reduces overall device complexity while still providing effective impingement cooling to the flameholder, extending its durability without proportionally increasing system complexity.
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
The design effectively suppresses combustor instability, increases combustion stability, and reduces undesirable emissions such as UHC, CO, and NOx, while maintaining high combustion efficiency and extending the life of the combustor components.
Implementation Method 1
An internal impingement ring is spaced forward from the flameholder in flow communication with the bypass inlet for receiving cooling air therefrom to impingement cool the flameholder
Data Source
AI summary
A combustor swirl cup includes coaxial inner and outer swirlers separated by a tubular centerbody. The centerbody includes a bypass inlet surrounding the inner swirler and diverges aft along a perforate inner nozzle to terminate at an annular flameholder. An impingement ring is spaced forward from the flameholder in flow communication with the bypass inlet for receiving cooling air therefrom to impingement cool the flameholder.