Gas Turbine Combustor Flame Stabilization
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Solution Overview
Problem
Gas turbine combustors face challenges in reducing NOx emissions while preventing flashback and combustion oscillation, particularly due to flame surface variations.
Innovation Solution
The design incorporates a fuel nozzle configuration with a projection at the leading end and an orifice that causes a pressure drop, along with an air hole plate arrangement that promotes swirl flow and radial mixing of fuel and air, reducing NOx generation and stabilizing the flame to suppress combustion oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a premixed combustor is used to reduce NOx emissions, then NOx emissions are reduced, but flash-back phenomenon occurs
Solution Approach 1:
A pilot burner is introduced as an intermediary device to stabilize the flame before the main fuel injection. The pilot burner creates a controlled flame front that prevents uncontrolled flash-back into the premixed combustion zone, while still maintaining the low-NOx premixed combustion characteristics of the main combustor.
Solution Approach 2:
Different regions of the combustor are given different functional characteristics: the pilot burner zone provides flame stabilization and prevents flash-back, while the main combustor zone maintains premixed combustion for low NOx emissions. This local differentiation resolves the contradiction between preventing flash-back and maintaining low NOx emissions.
2Object-generated harmful factors
If fuel and air are mixed over a longer distance to reduce NOx, then NOx emissions are reduced, but combustion oscillation occurs due to flame surface variation
Solution Approach 1:
The pilot burner acts as a feedback mechanism that continuously monitors and stabilizes the flame position. When flame surface variations occur during the extended mixing process, the pilot burner provides a stabilizing influence that suppresses combustion oscillations, allowing the system to maintain both long mixing distance and combustion stability.
Solution Approach 2:
The pilot burner performs preliminary flame stabilization before the main fuel-air mixture is fully mixed and burned. This preliminary action prevents flame surface variations from developing into combustion oscillations during the extended mixing process, allowing NOx reduction through longer mixing distance without sacrificing combustion stability.
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
This configuration effectively reduces NOx emissions and stabilizes the flame, suppressing combustion oscillation by ensuring uniform fuel-air mixing and controlling pressure variations, thereby enhancing the operational stability of the gas turbine combustor.
Implementation Method 1
an orifice that causes a pressure drop in the gaseous fuel
Implementation Method 2
an air hole plate arrangement that promotes swirl flow and radial mixing of fuel and air
Implementation Method 3
an air hole plate arrangement that promotes swirl flow and radial mixing of fuel and air
Implementation Method 4
a fuel nozzle configuration with a projection at the leading end
Data Source
Figure 1~2
Figure 3
Figure 4A~6
AI summary
A combustor according to the present invention includes a combustion chamber (5) to which fuel and air are supplied; air holes (32) adapted to supply air to the combustion chamber (5); fuel nozzles (25) adapted to supply gaseous fuel to the air holes (32); and orifices (24) adapted to allow the gaseous fuel supplied to the air holes (32) to cause a pressure drop.