Gas Turbine Combustor Trapped Vortex NOx Reduction
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Solution Overview
Problem
Gas turbine engines face challenges in achieving efficient combustion while minimizing NOx emissions, particularly when operating on different fuels, as existing methods often result in flashback, flameout, and high emissions due to combustion instability and inefficient fuel mixing.
Innovation Solution
A combustor assembly and method that utilizes a trapped vortex formed by ammonia injection in an annular cavity downstream of the reaction zone to convert NOx and N2O emissions into non-polluting products, combined with independent premixing of fuels to stabilize the flame and optimize combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If lean premixed combustion is used to reduce peak flame temperatures and limit thermal NOx formation, then NOx emissions are reduced, but combustion instability and Lean Blow Out occur
Solution Approach 1:
A trapped vortex is introduced as an intermediary mechanism in the combustion chamber. This vortex, formed by injected fluid, acts as a mediator that stabilizes the flame front and prevents Lean Blow Out while maintaining the low temperature conditions necessary for reduced thermal NOx formation. The vortex creates a recirculation zone that anchors the flame and ensures reliable combustion.
Solution Approach 2:
The invention changes the flow dynamics parameters within the combustion chamber by introducing a trapped vortex. This alters the velocity distribution, pressure fields, and flame propagation characteristics. By modifying these flow parameters, the system achieves stable combustion at lean mixtures without thermal NOx formation, resolving the contradiction between emission reduction and combustion stability.
2Reliability
If fuel is introduced in multiple fuel injection holes with differing staging to control flame and avoid LBO, then combustion stability is improved, but device complexity and control difficulty increase
Solution Approach 1:
The invention extracts the flame stabilization function from the complex multi-hole fuel injection system and relocates it to a trapped vortex mechanism. Instead of using multiple injection holes with different staging to control flame position and prevent LBO, the system uses a single vortex-generating injection point that creates a recirculation zone to anchor the flame. This simplifies the hardware while maintaining stability.
Solution Approach 2:
The trapped vortex system is self-regulating and does not require complex feedback control or intelligent fuel scheduling. The vortex naturally forms and maintains the flame front position through its recirculation flow, providing automatic flame stabilization without the need for sophisticated control algorithms or multiple staged injection systems.
3Productivity
If the combustor is designed for a specific fuel with optimal operation, then combustion efficiency is maximized, but adaptability to different fuels is reduced
Solution Approach 1:
The trapped vortex mechanism serves multiple functions: it stabilizes the flame front, prevents LBO, and maintains efficient combustion across different fuel types. By introducing this universal stabilization mechanism, the combustor can operate efficiently on various fuels (natural gas, diesel, syngas, landfill gas) without requiring fuel-specific design optimizations, thus achieving both high combustion efficiency and fuel adaptability.
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 solution effectively reduces NOx emissions by converting pollutants into water and nitrogen, while maintaining stable combustion and tolerance to load changes, enhancing the overall efficiency and environmental sustainability of gas turbine operations.
Implementation Method 1
The trapped vortex in the combustion chamber supplies NH2 radicals, resulting from the ammonia injected into the annular cavity, to the passing by emissions and converts the NOx and N2O to non-polluting products, mainly water and nitrogen.
Implementation Method 2
The combustor assembly is adapted to premix the first and the second fuels with a first and a second air flows to form a first and a second premixing stream lines, respectively, before the fuels enter the reaction zone
Implementation Method 3
at least a first fuel is combusted in a reaction zone of a combustion chamber of the combustor assembly
Data Source
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AI summary
A gas turbine combustor assembly with a trapped vortex feature A combustor assembly (100) of a gas turbine engine (10) having a trapped vortex feature to reduce emissions is presented. The trapped vortex is formed using ammonia injected into an annular cavity (60) located in a wall surrounding a combustion chamber (28) of the combustor assembly. The annular cavity (60), and therefore the trapped vortex, is positioned such that when the combustion occurs within the combustion chamber the position of the annular cavity, and therefore of the trapped vortex, is downstream of a flame front (9). The emissions resulting from combustion travel through the combustion chamber (28) and pass by the annular cavity (60) before exiting the combustion chamber. The trapped vortex in the combustion chamber supplies NH2radicals, resulting from the ammonia of the trapped vortex, to the passing by emissions and converts NOx and/or N20 in the emissions to non-polluting products, mainly water and nitrogen.