US 4,048,062 AGranted

Aromatic extraction with solvent recovery and regeneration

AssigneeUop LLC

InventorGeorge F. Asselin

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Abstract

A solvent extraction process for separating polar hydrocarbons from non-polar hydrocarbons. The solvent-rich extract phase is introduced into a stripping column, the bottoms from which, being a polar hydrocarbon-containing, solvent-rich stream, is introduced into an upper portion of a solvent recovery column. A first vaporous stripping medium is introduced into a lower portion of the solvent recovery column. A portion of the solvent-rich stream, virtually free from hydrocarbons, withdrawn as a bottoms product, is introduced into a solvent regeneration zone, the remainder being recycled to the extraction zone. A second vaporous stripping medium is introduced into the solvent regeneration zone, recovered with regenerated solvent and introduced into the solvent recovery column as at least a portion of the first vaporous stripping medium.

Claims10

Dependent claims

A method for recovering and regenerating a substantially hydrocarbon-free, polar hydrocarbon selective solvent from a mixture of an aqueous selective solvent with polar hydrocarbons and non-polar hydrocarbons, which method comprises the steps of:

a. introducing said mixture into a first fractionation column, removing a water-containing non-polar hydrocarbon-rich stream from an upper portion of said first column and removing a first solvent-rich, polar hydrocarbon-containing stream from a lower portion of said first column;
b. introducing at least a portion of said first solvent-rich, polar hydrocarbon-containing stream into a second fractionating column, removing a polar hydrocarbon-rich stream, substantially free from solvent and non-polar hydrocarbons, from an upper portion of said second column, and removing a second solvent-rich stream, substantially free from hydrocarbons, from a lower portion of said second column;
c. introducing a first vaporous stripping medium into said second fractionation column through a locus above that from which said second solvent-rich stream is removed;
d. separating water from said non-polar hydrocarbon-rich stream removed from the upper portion of said first column in step (a) and vaporizing the same to form steam;
e. introducing a portion of said second solvent-rich stream into the upper section of a solvent regenerating zone and introducing steam from step (d) as a second vaporous stripping medium into the lower section of said regenerating zone;
f. recovering a regenerated solvent stream containing substantially all of said second vaporous stripping medium;
and,
g. introducing said regenerated solvent stream, containing said second stripping medium, into said second fractionation column as at least a portion of said first vaporous stripping medium.

5 more elements

A process for the recovery of aromatic hydrocarbons from a mixture thereof with non-aromatic hydrocarbons which process comprises the steps of:

a. introducing said mixture into an extraction zone, and therein contacting said mixture with a solvent characteristically selective for absorbing aromatic hydrocarbons, at conditions selected to maintain said mixture and solvent in liquid phase;
b. removing a non-aromatic raffinate stream from said zone, through an upper locus thereof;
c. water washing said raffinate stream and then vaporizing the wash water to form steam;
d. removing an aromatic, solvent-rich extract stream from said zone, through a lower locus thereof, and introducing said extract stream into a stripper column;
e. removing a non-aromatic concentrate from said stripper column, through an upper locus thereof, and removing a first solvent-rich aromatic concentrate from said stripper column, through a lower locus thereof;
f. introducing said aromatic concentrate into a recovery column, through a first locus thereof, introducing a first vaporous stripping medium into a lower, second locus thereof, recovering a substantially solvent-free aromatic concentrate through an upper third locus thereof, removing a substantially hydrocarbon-free, second solvent-rich stream from a lower fourth locus thereof;
g. introducing a portion of said second solvent-rich stream into the upper section of a solvent regenerating zone and introducing at least a portion of said steam from step (c) as a second vaporous stripping medium into the lower portion of said regenerating zone;
h. recovering a regenerated solvent stream containing substantially all of said second vaporous stripping medium;
and
i. introducing said regenerated solvent stream, containing said second stripping medium, into said recovery column as at least a portion of said first stripping medium.

7 more elements

Dependencies are inferred from the claim text.