If the sulfur content in the raw material is low, what are the criteria for the hydrogen sulfide concentration in the recycled hydrogen, and what actions should be taken if this concentration falls below the specified levels?
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What are the criteria for the hydrogen sulfide concentration in the recycled hydrogen when the sulfur content of the raw material is low, and what actions should be taken if this concentration falls below the specified levels?
What kind of hydrogenation is it? Generally, the sulfur content in circulating hydrogen is not controlled when it is low; if it is high, it can be replaced
It’s only for the reformation unit. The hydrogen sulfide content in the circulating hydrogen must be kept under control! If it is too high, it might be due to catalyst sulfur poisoning or an excessive sulfur content in the refined oil used in the pretreatment process!
This post was last edited by leisure929 on 2011-9-22 at 14:43. We have encountered this problem in our hydrocracking units: after the hydrogen sulfide content in the recycle hydrogen remained below 0.1% for an extended period, the catalyst activity **decreased**, and its activity was restored by adding DMDS
The hydrogen sulfide content in the circulating hydrogen of hydrocracking units should not be less than 300 ppm; otherwise, the catalysts will be reduced. This applies roughly to diesel, residue, and most gasoline hydroprocessing units
A low sulfur content can easily lead to catalyst reduction; the sulfur content in the feedstock used for our hydrogenation process is very low, which is why the desulfurization of recycled hydrogen has been eliminated. Waste hydrogen is discharged only when the purity of the recycled hydrogen is low.
The last edit to this post was made by jbcyf on 2011-10-2 at 15:11. Reply to 1# dugutianzuo: The hydrogen sulfide concentration in the system needs to be strictly controlled. Generally, when the concentration drops to 200–300 ppm, the catalyst is reduced to elemental metal by hydrogen, resulting in its complete deactivation; this reaction is irreversible, meaning that the catalyst is no longer usable. A gentleman upstairs said that adding a vulcanizing agent is the right approach, but it’s not economical from a financial perspective. Our usual practice is to use high-sulfur oil in combination with other materials, and the results are excellent; high-sulfur oil is relatively cheap, while vulcanizing agents are expensive, so the math adds up well!