Modulating Burner Air-Gas Ratio Control for Hydrogen Flashback
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Solution Overview
Problem
Surface stabilized fully premixed gas burners using hydrogen or high hydrogen content fuels are prone to flame flashback at low burner loads due to high burning velocity, which affects combustion efficiency and safety.
Innovation Solution
The method involves adjusting the air to combustible gas ratio, increasing it by at least 20% at minimum load compared to full load, to enhance the exit speed of premix gas and reduce flame speed, thereby preventing flashback while maintaining high efficiency at higher load levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air to combustible gas ratio is kept constant for complete combustion, then combustion efficiency is improved, but flame flashback occurs at low burner loads due to high burning velocity of hydrogen
Solution Approach 1:
The patent applies dynamics by making the air to combustible gas ratio variable rather than constant. The control mechanism adjusts the ratio dynamically based on burner load, using higher ratios at low loads to prevent flashback and lower ratios at high loads to maintain efficiency, thus resolving the contradiction between reliability and harmful factors
Solution Approach 2:
The patent changes the parameter of air to combustible gas ratio from a fixed value to a variable value that depends on burner load. By implementing different ratio ranges for different load conditions (higher ratios at low loads, lower ratios at high loads), the system prevents flame flashback while maintaining combustion efficiency across the entire operating range
2Object-affected harmful factors
If the air to combustible gas ratio is increased to prevent flame flashback at low load, then safety is improved, but heat exchanger efficiency decreases due to excess air
Solution Approach 1:
The system dynamically adjusts the air to combustible gas ratio based on burner load conditions. At low loads, a higher ratio prevents flashback, while at high loads, a lower ratio maintains efficiency. This dynamic adaptation ensures that the harmful effect of excess air is minimized while still preventing flashback when needed
Solution Approach 2:
The patent implements parameter changes by varying the air to combustible gas ratio across different operating conditions. The control mechanism selects appropriate ratio values from predefined ranges based on burner load, optimizing the balance between safety (flashback prevention) and energy efficiency (heat exchanger performance)
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 approach effectively reduces the probability of flame flashback and maintains high heat exchanger efficiency by optimizing the air to gas ratio, ensuring stable operation across varying load conditions.
Implementation Method 1
supplying a premix of combustible gas and air to the burner at an air to combustible gas ratio
Implementation Method 2
The use of gas burners using 100% hydrogen or mixtures of natural gas with hydrogen seems an interesting solution to reduce carbon dioxide emissions
Data Source
AI summary
The invention pertains to a method for operating a surface stabilized fully premixed gas premix burner. The burner is adapted to modulate between a minimum load and a full load, the ratio of the full load over the minimum load being at least 4. The method comprises the step of supplying a premix of combustible gas and air to the burner at an air to combustible gas ratio, the combustible gas supplied to the burner comprises at least 20% by volume of hydrogen, In the method, the air to combustible gas ratio of the premix which is supplied to the burner when the burner is operated at minimum load is set by a mechanism to be in relative terms at least 20% higher than the air to combustible gas ratio of the premix which is supplied to the burner when the burner is operated at full load.