Regarding the control of the water-to-hydrogen ratio at the start of hydrogen production?
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When hydrogen production starts, the reduction conditions for the conversion catalyst require a value between 3 and 7. Could someone please explain what the consequences are if this value is too low or too high?
Too low a level will result in incomplete conversion, leaving behind large amounts of methane, causing carbon buildup, and may also lead to overheating and damage of the furnace tubes. Excess levels can cause the active centers of the catalyst to be gradually lost, resulting in a loss of its activity; moreover, a large amount of steam is also wasteful.
The water-hydrogen ratio should be less than 7.5. The operation is carried out in a reducing atmosphere; the lower the water-to-hydrogen ratio, the more favorable it is for reduction. When the water-to-hydrogen ratio is greater than 7.5, the reaction proceeds in the oxidative direction.
If it’s too high, it will cause oxidation; it won’t have a reducing effect, right?
During the reduction process, hydrogen and nitrogen are used; the probability of carbon deposition due to methane decomposition is very low, right? Is it the concern that the reduction may not be thorough enough? The air flow isn’t distributed evenly throughout each furnace tube!
If it is too high, it mainly affects conversion; above a ratio of 7.5 to 1, the internal medium becomes oxidizing, and without reducing properties, reduction cannot occur. If it is too low, it mainly affects the medium-temperature conversion process. The main component of medium-temperature conversion catalysts is iron oxide, which is quite sensitive; a value below 3 may lead to excessive reduction, causing the catalyst to lose its activity.