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• 1. In any Hydrotreater unit, it is observed from our Material Balance sheets, that H2 dissolution is more in Hot HP Separator liquid than in Cold HP Separator liquid, even though the temperature is high in HHPS with marginal high pressure on the vessel compared to CHPS? Why is it so?

  2. It is observed that Diesel Hydrotreater HHPS H2 dissolution is found to be on higher side compared to VGO Hydrotreater HHPS H2 dissolution, even though both pressure and temperature at HHPS of Diesel hydrotreater is less than VGO hydrotreater? Why is it so?

  Jan-2023

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Answers

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• Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

  The hydrogen solubility is a key parameter in hydroprocessing processes and the facts pointed in the questions are related to the solubility behavior of hydrogen. The hydrogen solubility in hydrocarbons is increased by pressure and temperature, this explain the phenomenon described in the first question.

  In the second question, it's expected that the hydrogen solubility is higher in lighter hydrocarbons like diesel than VGO (Vacuum Gas Oil) once the hydrogen solubility is reduced in the presence of heavy aromatics and heteroatoms, which is characteristic of VGO.

   

  Jan-2023