Gas Turbine Combustor Annular Fuel Injector for NOx Reduction
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Solution Overview
Problem
Gas turbine engines face challenges in reducing nitrogen oxide (NOx) emissions and preventing backfiring due to local high-temperature combustion, especially when using highly-reactive fuels like hydrogen.
Innovation Solution
A combustor design featuring a fuel injector with annular portions and an air guide member that deflects fuel jets, promoting uniform mixing and stabilizing the flame, combined with an air-flow rectifying mechanism and a rectifying protrusion member for enhanced combustion stability and NOx reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a premix combustion system is adopted to reduce NOx emissions, then NOx generation is suppressed, but flame stability deteriorates and backfiring occurs
Solution Approach 1:
The fuel injection system is divided into multiple annular portions with numerous small fuel injection holes distributed across the annular surfaces. This segmentation creates multiple small flame sources throughout the combustion chamber, preventing localized high-temperature zones that cause backfiring while maintaining overall flame stability through distributed combustion points
Solution Approach 2:
The air guide member provides localized air supply to each fuel injection hole through corresponding air guide grooves. This creates locally optimized air-fuel mixing zones that ensure stable combustion at each injection point while maintaining a uniform overall mixture, preventing both backfiring and excessive NOx generation
2Productivity
If fuel is injected radially to promote mixing, then combustion efficiency improves, but local high-temperature zones form causing NOx generation
Solution Approach 1:
The fuel injection holes are arranged radially on annular surfaces, and air guide grooves supply air in the axial direction. This creates three-dimensional fuel-air mixing patterns that distribute combustion throughout the annular volume, maintaining high combustion efficiency while eliminating concentrated high-temperature zones through spatial distribution of combustion points
3Power
If highly-reactive hydrogen fuel is used to improve combustion efficiency, then energy output increases, but flame instability and backfiring increase
Solution Approach 1:
Hydrogen fuel is distributed to multiple annular injection portions with numerous small holes, creating multiple small flame sources. This segmentation prevents the concentrated high reactivity of hydrogen from causing localized explosions or backfiring, while the cumulative effect of multiple stable flame points maintains high overall energy output
Solution Approach 2:
Air is supplied through air guide grooves positioned upstream relative to fuel injection holes, creating pre-mixed zones before combustion. This preliminary mixing ensures that highly-reactive hydrogen burns steadily and controllably, preventing flame instability and backfiring while maximizing energy release
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 NOx generation and prevents backfiring, ensuring stable combustion even with hydrogen fuels by maintaining minute flames at multiple points and uniform air flow, while the annular fuel flow passage and impingement cooling enhance temperature management.
Implementation Method 1
each of the combustion air annular portions includes a plurality of air guide grooves that are open in an axial direction and are configured to guide the air axially to the fuel jetted from the fuel injection holes, each of the air guide grooves being disposed at circumferential positions corresponding to respective fuel injection holes so that the fuel jetted from the fuel injection holes is deflected by the axially flowing air
Implementation Method 2
each of the fuel injection annular portions is formed as a hollow portion, and a hollow space in the fuel injection annular portion forms an annular fuel flow passage that allows the fuel to flow in a circumferential direction
Implementation Method 3
an injection nozzle configured to jet the fuel in the second fuel flow passage to a wall surface of the first fuel flow passage on the combustion chamber side
Implementation Method 4
When the premix combustion system is adopted, air and fuel are premixed and combusted as a lean air-fuel mixture whose fuel concentration is uniformized. Therefore, a combustion region where the flame temperature is locally high does not exist. In addition, the flame temperature can be lowered across the whole region by dilution of the fuel
Data Source
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AI summary
A combustor including a combustion liner (13) having a combustion chamber (11) formed therein; and a fuel injector (15) mounted to a top portion of the combustion liner, and including a fuel injection member (34) having a plurality of fuel injection annular portions (33) and an air guide member (36) including a plurality of combustion air annular portions (35) that guide air for combustion. The fuel injection annular portions and the combustion air annular portions are arranged concentrically and alternately. The fuel injector injects fuel (F) and air (A) into the combustion chamber. Each of the fuel injection annular portions includes a plurality of fuel injection holes (39) that are open in a radial direction thereof, and each of the combustion air annular portions includes a plurality of air guide grooves (41) that are open in an axial direction thereof, and guide the air to the fuel jetted from the fuel injection holes.