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Why is steam injected into the bottom of a crude oil distillation column?
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petroleum refining
Aerial view of an oil refinery near New Orleans.
In petroleum refining, steam is injected into the bottom of a crude oil distillation column primarily to reduce the partial pressure of the hydrocarbons. By lowering the partial pressure, the steam facilitates the vaporization of lighter components at lower temperatures, which assists in the separation process within the column.1
This injection occurs specifically in the lower section of the tower, where unvaporized oil flows downward over stripping trays. The steam helps strip any remaining light constituents from the liquid, ensuring more efficient separation before the residue is withdrawn from the base of the column.1