Flat Burner Flashback Prevention via Lean Mixture and Fuel-Only Port
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Solution Overview
Problem
The use of hydrogen-containing fuel in flat burners poses a challenge due to its high combustion speed, which can lead to flashback at the flame retention port, where gas ejection speed is relatively low.
Innovation Solution
A flat burner design where a lean fuel-air mixture is ejected from the main burner port and fuel-only gas is ejected from the flame retention port, creating a diffusion flame and positioning the combustion region away from the upper end to prevent temperature rise and flashback, with the flame retention port being lower than the main burner port to further separate the combustion zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen-containing fuel is used in the flat burner, then the combustion efficiency is improved, but the risk of flashback at the flame retention port increases due to high combustion speed
Solution Approach 1:
The invention applies different gas compositions to different ports: the main burner port receives a lean fuel-air mixture while the flame retention port receives fuel-only gas. This local differentiation allows the system to maintain high combustion efficiency in the main burner while preventing flashback in the flame retention port by creating a diffusion flame with lower combustion speed.
Solution Approach 2:
The invention changes the fuel-air ratio parameter differently for each port. The main burner operates with a lean mixture (low fuel concentration) for efficient combustion, while the flame retention port operates with fuel-only gas (zero air mixing at the port) to reduce combustion speed and prevent flashback. This parameter differentiation resolves the contradiction between efficiency and safety.
2Object-generated harmful factors
If a lean fuel-air mixture is used in the main burner port to reduce NOx generation, then the main flame temperature is lowered, but the combustion speed decreases
Solution Approach 1:
The invention combines two different combustion modes: premixed combustion in the main burner port for low NOx emission, and diffusion combustion in the flame retention port for high combustion speed. The diffusion flame from the fuel-only port provides a pilot flame that maintains overall combustion speed while the lean premixed flame in the main burner keeps NOx generation low.
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 design effectively prevents flashback by maintaining a stable combustion region between the pilot and main flames, ensuring optimal combustion speed and temperature, thus preventing flashbacks at the flame retention port.
Implementation Method 1
a lean fuel-air mixture which is leaner in fuel concentration than the theoretical fuel-air ratio is ejected from the main burner port. Then by lowering the main flame temperature to be generated by the combustion of the lean fuel-air mixture by the excess air that is included in the lean fuel-air mixture, the amount of generation of NOx is reduced.
Implementation Method 2
since the gas containing only the fuel is ejected from the flame retention port, the pilot flame to be formed on the flame retention port will become diffusion flame
Implementation Method 3
the region in question being the one in which a combustion reaction takes place of a mixture gas of theoretical fuel-air ratio that can attain the highest temperature and the highest combustion speed, and the region also being the one which is present between the pilot flame and the main flame that is formed by the combustion of the lean fuel-air mixture ejected from the main burner port, in which the mixture gas of theoretical fuel-air ratio is defined to be a mixture gas in which the ejected fuel from the flame retention port gets mixed with the excess air in the ejected lean fuel-air mixture from the main burner port
Data Source
AI summary
[Problems] A flat burner elongated in the longitudinal direction has, at an upper end thereof, a main burner port (63) and a flame retention port (64) positioned at least on laterally one side of the main burner port (63). The flat burner uses hydrogen-containing fuel as a fuel. Flash back is prevented at the flame retention port in which the gas ejection speed becomes relatively small.[Solving Means] A lean fuel-air mixture which is leaner in fuel concentration than a theoretical fuel-air ratio is ejected from the main burner port (63) and a gas containing only fuel is ejected from the flame retention port (64). In addition, the height, on the side of the main burner port (63), of the upper end of the flame retention port (64), is made lower than the height of the upper end of the main burner port (63).