16. Hydrotreating

Question 1

■ Objective and description of Alkylation process?
■ The process?
■ Main Units?

Answer 1

■
▪ Hydrotreating does an effective job of removing many of the contaminants from many of the streams. Hydrogen is the operative input to the hydrotreating process.
▪ Any refinery streams that have C6 and heavier hydrocarbons in them are likely to have some sulfur hidden in the mixture

■
▪ Hydrogen combines with S form H2S
▪ Nitrogen compounds convert to Ammonia NH4
▪ Metals entrained in the oil react with the chlorine to form chlorides
▪ Olefins and aromatics get saturated with hydrogen
▪ As the contaminants crack away from the hydrocarbon, some methane (CH4), Ethane (C2H6), Propane (C3H8) and Butanes (C4H10) form.

■
▪ Heater
▪ Reactor
▪ H Separator

Question 2

■ Jet fuel hydrotreating
■ Distillates hydrotreating
■ Gasoline hydrotreating

■ Pyrolysis gas hydrotreating
■ Cat feed and reformer feed hydrotreating
■ Residual hydrotreating

Answer 2

■ Jet fuel hydrotreating:
Improving burning charactheristics of distillates especially jet fuel.
▪ Kerosene containt large % of aromatics.
▪ Deficiency of H can cause smoke (Smoke Point low is bad)
▪ During the process aromatic rings get saturated with H, converting aromatics to naphtenes with higher H to C ratios that burn cleaner.

■ Distillates hydrotreating:
▪ Reduce S contents of Diesel
▪ Reduce the amounts of aromatics and raises cetane numbers

■ Gasoline hydrotreating:
▪ Reduces olefins and aromatics content by saturating the double bonds with H.
▪ Also reduces octane number as the aromatics get saturated to naphtenes.