Coaxial Combustor Nozzle Assembly for Gas Turbine
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Solution Overview
Problem
Current gas turbine combustors face challenges in achieving uniform fuel-air mixing and stable combustion, leading to increased nitrogen oxide emissions and combustion instability due to non-premixed fuel injection and inadequate mixing characteristics in existing burner designs.
Innovation Solution
A combustor nozzle assembly with a coaxial two-stage stratified combustion system, featuring a central and outer nozzle tube with pilot and main fuel injectors, and a main swirler, which allows for adjustable fuel-air concentrations in separate flow paths to enhance mixing and stability, minimizing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel and air are premixed into a lean mixture in the nozzle before combustion, then nitrogen oxide emissions are reduced, but flame stability deteriorates and combustion rate becomes unstable
Solution Approach 1:
The combustor is divided into multiple zones with different fuel-air mixing characteristics: a central premixed combustion zone for low NOx emission and an outer non-premixed combustion zone for stable flame anchoring. This segmentation allows each zone to fulfill its specific function independently, resolving the contradiction between emission reduction and flame stability.
Solution Approach 2:
Different regions of the combustor are designed with different fuel injection and mixing characteristics. The central region uses lean premixed combustion with controlled equivalence ratio for emission control, while the outer region maintains richer non-premixed combustion for flame stability. This local differentiation allows simultaneous achievement of low emissions and stable combustion.
2Reliability
If a Swozzle-type burner with cylindrical central body is used to form recirculation area, then flame stability is improved, but fuel-air mixing uniformity deteriorates
Solution Approach 1:
The burner is segmented into a central swirler for generating recirculation flow and flame stabilization, and an outer annular region for fuel-air mixing. The central body is optimized specifically for flow control rather than mixing, while the outer region handles the mixing function, thereby resolving the conflict between flame stability and mixing uniformity.
Solution Approach 2:
The design transitions from a single-dimensional mixing approach to a multi-dimensional structure with central and outer flow paths. By utilizing the radial dimension to create concentric flow zones, the system achieves both recirculation for stability and distributed mixing for uniformity simultaneously.
3Manufacturing precision
If dual annular counter rotating swirler is used for air-fuel mixing, then fuel-air mixing characteristics are improved, but flame stability deteriorates due to lack of strong recirculation flow
Solution Approach 1:
The swirler system is segmented into central and outer annular swirlers that operate in different flow regimes. The central swirler generates strong recirculation for flame stability, while the outer annular swirler provides enhanced mixing. This segmentation allows each component to optimize for its primary function without compromising the other.
Solution Approach 2:
The design merges the recirculation function (traditionally provided by a single swirler) with the mixing function (provided by multiple swirlers) into a unified dual-swirler system. The central and outer swirlers work together, with the central unit ensuring flame stability through recirculation and the outer unit enhancing mixing through counter-rotation, achieving both objectives simultaneously.
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 improves fuel-air mixing and flame stability, reducing NOx emissions and combustion fluctuations, resulting in a more efficient and environmentally friendly combustion process.
Implementation Method 1
a main swirler, which allows for adjustable fuel-air concentrations in separate flow paths to enhance mixing and stability
Implementation Method 2
coaxial two-stage stratified combustion system
Implementation Method 3
combust the mixture to generate high-temperature and high-pressure combustion gas
Data Source
AI summary
A combustor nozzle assembly and a gas turbine combustor including the same are provided. The combustor nozzle assembly includes a central nozzle tube, an inner nozzle tube surrounding the central nozzle tube in a spaced-apart state, an outer nozzle tube surrounding the inner nozzle tube in a spaced-apart state, a pilot fuel injector provided between the central nozzle tube and the inner nozzle tube, and a main fuel injector provided between the inner nozzle tube and the outer nozzle tube.