Hydrogen Burner Injection Staging to Prevent Flashback and NOx
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Solution Overview
Problem
Hydrogen combustion in gas turbines faces challenges such as flashback problems, high flame speeds, extensive flammability limits, increased noise pollution, and high NOx emissions, which existing burners and injection systems struggle to address effectively.
Innovation Solution
A premixed rich injection process for hydrogen-air combustion in gas turbines, involving a staged combustion method with a rich hydrogen-air mixture injected through an internal channel and lean air injection through an external annular channel, creating two flame fronts to stabilize combustion and reduce thermo-acoustic instabilities and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If hydrogen-air combustion is used, then carbon-based pollutant emissions are eliminated, but flame speed increases causing flashback problems
Solution Approach 1:
The combustion process is divided into two distinct stages: a first rich combustion zone where hydrogen burns with limited air supply, and a second lean combustion zone where remaining fuel burns with excess air. This segmentation controls flame speed by managing fuel-air ratio distribution, preventing flashback while maintaining low emissions
Solution Approach 2:
Different regions of the combustion chamber are assigned different air-fuel ratios: the first zone operates with a rich mixture (excess fuel) to control flame propagation speed, while the second zone operates with a lean mixture (excess air) to complete combustion. This local quality variation resolves the contradiction between flame speed control and emission reduction
2Speed
If rich combustion is used, then flame speed is controlled to prevent flashback, but combustion stability deteriorates
Solution Approach 1:
The combustion system is segmented into two functional zones: the first zone provides stable anchor points for the flame through rich combustion, while the second zone ensures complete combustion and stability through lean combustion. The interaction between these zones maintains overall combustion stability while controlling flame speed
Solution Approach 2:
The patent combines two combustion modes (rich and lean) into a unified staged combustion system. The rich combustion zone provides flame stability and anchors the flame, while the lean combustion zone ensures complete burnout. Together, they achieve both flame speed control and combustion stability
3Stability of the object's composition
If lean combustion is used, then combustion stability improves, but thermoacoustic instabilities increase
Solution Approach 1:
The combustion chamber is segmented such that the first zone operates with rich mixture to suppress thermoacoustic instabilities through inherent flame damping, while the second zone operates with lean mixture for stable complete combustion. This spatial segmentation decouples the stability function from the low-instability function
4Productivity
If high flame temperature is used, then combustion efficiency increases, but NOx emissions increase
Solution Approach 1:
The combustion process is segmented into two temperature zones: the first rich combustion zone operates at controlled temperatures that limit thermal NOx formation, while the second lean combustion zone operates at lower temperatures due to excess air cooling. This segmentation maintains combustion efficiency while suppressing NOx emissions through temperature control
Solution Approach 2:
The patent changes the air-fuel ratio parameter through staging: the first zone uses a rich mixture (fuel-excess) to control peak temperature and reduce NOx, while the second zone uses a lean mixture (air-excess) to ensure complete combustion. This parameter variation achieves both efficiency and emission reduction
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 process achieves stable combustion with reduced NOx emissions, lower flame temperatures, and minimized noise pollution, while preventing flashback and ensuring the integrity of the combustion chamber.
Implementation Method 1
a first combustion rich in dihydrogen (30) is obtained at the outlet of said internal channel (6)
Implementation Method 2
The air injected through the annular channel can be rotated by an annular screw so as to make the second flame front turbulent
Implementation Method 3
The mixture burned in the first flame front generates residual gases which are advantageously burned in the second flame front
Data Source
Figure 1
Figure 2~3
Figure 4(A)~5(C)
AI summary
The invention relates to an injection method for an injection device in a combustion chamber of an aircraft turbine engine, the injection device comprising an internal channel (6) surrounded by an external annular channel (8), the channels opening into the combustion chamber (4, 4') of the gas turbine, the method being characterised in that it comprises injecting a dihydrogen-air mixture (12a) with a hydrogen content greater than the stoichiometric amount into the internal channel (6) and injecting air into the external annular channel (8) so as to produce, at the outlet of the internal channel (6), a first flame front (30) resulting from rich combustion surrounded by a second flame front (31) resulting from lean combustion.