What is the typical hydrogen-to-oil ratio for gasoline and diesel hydroprocessing, as well as for diesel hydroprocessing? What is an appropriate level for hydrogen sulfide in the recycled hydrogen during operation?
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What is the typical hydrogen-to-oil ratio for gasoline and diesel hydroprocessing, as well as for diesel hydroprocessing? What is an appropriate level for hydrogen sulfide in the recycled hydrogen during operation?
This is a very professional question! Based on my experience, the hydrogen-to-oil ratio in diesel and gasoline hydrogenation is generally between 300–800 Nm³/m³, depending on the plant design and the properties of the feedstock. It is advisable to keep the hydrogen sulfide concentration in the recycled hydrogen below 100–200 ppm; higher levels can affect catalyst activity. However, in practice, it is still necessary to follow the specifications outlined in the process package for your equipment; it is advisable to check the design documents or consult a process engineer for greater certainty~
Based on practical experience, the hydrogen-to-oil ratio indeed needs to be adjusted flexibly according to the type of installation. When processing straight-run diesel, our unit maintains a hydrogen-to-oil ratio of around 500; for the oils that undergo secondary processing, this ratio is increased to 600–700. Controlling the H2S concentration in the recycle hydrogen is crucial. Generally, we keep it below 150 ppm by water washing; excessively high levels can lead to an increase in the pressure drop across the catalyst bed. It is recommended that the poster make dynamic adjustments based on the sulfur content of the raw materials and the service life of the catalyst, and it is best to conduct regular sampling and analysis of the catalyst.
In the operation of hydrogenation units in refineries, the hydrogen-to-oil ratio indeed needs to be adjusted flexibly according to the properties of the feedstock. When processing straight-run diesel, we keep the value at 400–500 Nm³/m³ in our unit; it is more appropriate to raise the value for reprocessed diesel to 600–700. It is recommended to control the H₂S concentration in the recycle hydrogen within the range of 100–200 ppm by water injection. In our actual operations, we’ve found that when this concentration exceeds 250 ppm, the catalyst activity decreases significantly. Additionally, please note that different catalyst suppliers may have varying tolerances to H₂S; it is best to adjust the parameters based on the catalyst manual for your facility.