The issue of the hydrogen air-fuel ratio
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Recently, I came across a case involving the combustion of pure hydrogen, and I would like to ask those knowledgeable online users about the air-fuel ratio for hydrogen combustion. From the chemical equation 2H2 + O2 = 2H2O, it is clear that the ratio of oxygen to hydrogen is 1:2, which results in the most complete combustion; in other words, the air-to-hydrogen ratio is 5:2. Under these conditions, the volume concentration of hydrogen would be around 28%. This concentration falls within the explosion range of 4.0% to 74.2% (with hydrogen’s volume accounting for the total volume of the mixture), so wouldn’t an explosion occur? . . Some people say that hydrogen burns quietly only outside its explosive range, for example at concentrations lower than 4% or higher than 75%. Could anyone help me figure out what’s really going on? Thank you!
If there is no combustion and only mixing occurs, it’s a baozha* device; if ignited directly, it may explode. The two gases enter the combustion chamber in proportion; since the hydrogen in the burner has already been burned, its concentration is naturally zero.
Burning in an open space will not cause an explosion. Explosions generally occur in confined spaces. Quartz utensil processing is done using hydrogen fire
Thank you, now I understand. Is this air-fuel ratio correct?
Thank you. I have another question: since you use hydrogen for combustion, I’d like to ask about nitrogen purging. Is it necessary to purge the pipelines inside the burner valve assembly, which are approximately 2 meters long? (The valve assembly contains solenoid valves that cannot be opened before the burner is ignited; nitrogen can only be introduced between the end of the valve assembly and the burner.)