Gas Turbine Combustor Stepped Recess Flame Stability
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Solution Overview
Problem
Existing combustors using fuels with low reactivity, such as mixtures of hydrogen and natural gas, face challenges in maintaining a stable flame, leading to difficulties in achieving low-NOx combustion and preventing backfire.
Innovation Solution
A gas turbine combustor design featuring a fuel injection device with a stepped recess in the fuel injection portion, where the fuel injection opening is located at the bottom wall surface of the recess, ensuring stable flame maintenance by directing fuel flow and promoting air-fuel mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If small diameter fuel injection holes are used for multipoint dispersed injection, then low-NOx combustion is achieved, but flame stability deteriorates when using fuel with low reactivity
Solution Approach 1:
The fuel injection system is divided into multiple annular members with multiple fuel injection holes, creating numerous dispersed injection points. This segmentation allows for distributed fuel injection throughout the combustion chamber, reducing local high-temperature zones that generate NOx while maintaining overall combustion stability through the collective effect of multiple injection points.
Solution Approach 2:
Multiple annular members are arranged concentrically within each other, with fuel injection holes positioned at different radial distances from the combustion chamber center. This nested configuration enables staged fuel injection where inner and outer annular members can inject fuel at different rates and timing, improving flame stability for low-reactivity fuels while maintaining the dispersed injection pattern needed for low-NOx combustion.
2Object-generated harmful factors
If fuel is injected in a dispersed manner from multiple holes, then low-NOx combustion is achieved, but difficulty in maintaining stable flame increases
Solution Approach 1:
Different annular members and fuel injection holes are configured with varying hole diameters, injection angles, and positions tailored to local combustion requirements. This allows optimization of fuel-air mixing at each injection point while maintaining the overall dispersed injection pattern, ensuring stable flame propagation across the entire combustion chamber even when using low-reactivity fuels.
Solution Approach 2:
Fuel is pre-mixed with air in the annular passages before injection into the combustion chamber. This preliminary mixing action ensures that fuel and air are properly combined prior to injection, creating stable fuel-air mixtures that ignite reliably and maintain stable combustion, particularly important for low-reactivity fuels that require adequate mixing time.
3Object-generated harmful factors
If multipoint dispersed fuel injection is used, then low-NOx combustion is achieved, but complexity of fuel injection device increases
Solution Approach 1:
The annular members serve multiple functions: they structure the fuel injection pattern, provide passages for air-fuel mixing, position multiple injection holes in precise configurations, and enable staged injection control. This multi-functionality reduces the need for separate components for each function, simplifying the overall device structure while achieving complex injection patterns required for low-NOx combustion.
Solution Approach 2:
Multiple functional elements are merged into the annular member structure: fuel injection holes, air mixing passages, and structural support are integrated into a single annular component. This merging reduces the total number of separate parts, simplifies assembly, and maintains the dispersed injection pattern needed for low-NOx combustion without excessive device 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 stabilizes the flame for fuels with low reactivity, enhancing low-NOx combustion and preventing backfire, as confirmed by CFD combustion analysis, ensuring stable operation across various load conditions.
Implementation Method 1
a plurality of fuel injection holes each configured to inject the fuel in a direction containing a component perpendicular to an axial direction of the combustion chamber
Implementation Method 2
an air guide portion having an air guide groove configured to guide air for combustion to the fuel injected from each fuel injection hole
Implementation Method 3
The fuel injection portion has an air guide surface configured to guide the air for combustion and located frontward in the axial direction of the combustion chamber relative to the fuel injection hole
Implementation Method 4
a combustion tube forming a combustion chamber on an inner side
Data Source
AI summary
A gas turbine combustor includes a fuel injection device provided to a combustion tube forming a combustion chamber on an inner side, and including: a fuel injection portion having a plurality of fuel injection holes which inject fuel in directions containing components perpendicular to an axial direction and a common fuel supply chamber which supplies fuel into the plurality of fuel injection holes; and an air guide portion which guides air to fuel injected from each fuel injection hole. The fuel injection portion has an air guide surface which guides air for combustion and is located frontward in the axial direction of the combustion chamber relative to the fuel injection hole. A fuel injection opening of the fuel injection hole is provided at a bottom wall surface of a stepped recess recessed in a step shape from the air guide surface.