Combination of extractive distillation and liquid extraction process for separation of a hydrocarbon feed mixture

Claim 2

A PROCESS FOR THE RECOVERY OF TWO AROMATIC FRACTIONS AND NON-AROMATICS FROM A HYDROCARBON FEED MIXTURE CONTAINING AROMATIC AND NON-AROMATIC HYDROCARBONS, WHICH PROCESS COMPRISES: A. PASSING SAID FEED INTO AN EXTRACTIVE DISTILLATION ZONE MAINTAINED UNDER EXTRACTIVE DISTILLATION CONDITIONS INCLUDING THE PRESENCE OF LIQUID SOLVENT CAPABLE OF SELECTIVELY DISSOLVING A FIRST AROMATIC FRACTION OF SAID TWO FRACTIONS TO PROVIDE A FIRST RICH SOLVENT STREAM CONTAINING SAID FIRST PRISING NON-AROMATIC AND SECOND AROMATIC FRACTION MATERRIAL; B. RECOVERING SAID FIRST AROMATIC FRACTION SAID FIRST RICH SOLVENT AND PASSING SOLVENT REMAINING AFTER SAID RECOVERY BACK TO SAID EXTRACTIVE DISTILLATION ZONE OF STEP (A); C. CONDENSING AT LEAST A PORTION OF SAID FIRST OVERHEAD VAPOR STREAM TO FORM A CONDENSED FEED, D. PASSING CONDENSED FEED INTO A LIQUID PHASE EXTRACTION ZONE MAINTAINED AT EXTRACTION CONDITIONS INCLUDING THE PRESENCE OF A LIQUID SOLVENT CAPABLE OF SELECTIVELY DISSOLVING THE SECOND AROMATIC FRACTION MATERIAL IN SAID CONDENSED FEED AND A HEREINAFTER DEFINED REFLUX TO PROVIDE A SECOND RICH SOLVENT STREAM CONTAINING THE SECOND AROMATIC FRACTION AND NON-AROMATIC HYDROCARBONS; PHASE COMPRISING NON-AROMATIC HYDROCARBONS; E. PASSING SAID SECOND RICH SOLVENT STREAM INTO A STRIPPING ZONE MAINTAINED UNDER STRIPPING CONDITIONS TO REMOVE NONE-AROMATICS FROM SAID SECOND RICH SOLVENT TO PROVIDE A SECOND OVERHEAD STREAM COMPRISING SAID SECOND AROMATIC THIRD RICH SOLVENT STREAM COMPRISING SAID SECOND AROMATIC FRACTION AND SOLVENT; F. CONDENSING SECOND OVERHEAD VAPOR AND RETURNING AT LEAST A PORTION THEREOF TO SAID LIQUID-LIQUID EXTRACTION ZONE OF STEP (D) AS THE ABOVE MENTIONED REFLUX; G. RECOERING SAID SECOND AROMATIC FRACTION FROM SAID THIRD RICH SOLVENT AND PASSING SOLVENT REMAINING AFTER SAID RECOVERY BACK TO SAID LIQUID PAHSE EXTRACTION ZONE.

Claim 3

Claim 1 in that said hydrocarbon feed contAins aromatics selected from the group consisting of benzene, toluene, xylenes and C9 aromatics and non-aromatics selected from the group consisting of paraffins and cyclo-paraffins having from about five to about nine carbon atoms per molecule.

Claim 4

Claim 2 in that said second aromatic fraction comprises benzene and toluene.

Claim 5

Claim 1 in that said hydrocarbon feed contains aromatics selected from the group consisting of benzene, toluene and xylenes and non-aromatics selected from the group consisting of paraffins and cyclo-paraffins having from about five to about nine carbon atoms per molecule.

Claim 6

Claim 4 in that said first aromatic fraction comprises toluene and xylene.

Claim 7

Claim 4 in that said second aromatic fraction comprises benzene and toluene.

Claim 8

Claim 4 in that said raffinate stream comprises paraffins and cyclo-paraffins having from about five to about nine carbon atoms per molecule.

Claim 9

Claim 4 in that said reflux comprises paraffins and cyclo-paraffins having an average boiling point which is lower than the average boiling point of the raffinate stream.

Claim 10

Claim 1 in that at least one of said solvents comprises a sulfolane type chemical of the general formula:

Claim 11

Claim 9 in that at least one of said solvents comprises sulfolane.

Claim 12

Claim 9 in that at least one of said solvents comprises a sulfolane selected from the group consisting of 2-sulfolene and 3-sulfolene.

Claim 13

A process for the recovery of a heavy aromatic extract comprising toluene and xylene, a light aromatic extract comprising benzene and toluene and a non-aromatic raffinate comprising paraffins and cyclo-paraffins having from about five to about nine carbon atoms per molecule from a hydrocarbon feed stock, which process comprises: a. passing said feed into an extractive distillation zone maintained under extractive distillation conditions including the presence of a sulfolane solvent to provide a first rich solvent substantially free of non-aromatics and containing toluene and xylene and a first overhead vapor stream comprising benzene, toluene and raffinate components; b. recovering toluene and xylene from said first rich solvent as said heavy extract and passing solvent remaining after said recovery back to said extractive distillation zone of step (a); c. cooling said first overhead vapor stream to form a condensed feed; d. passing condensed feed into a liquid phase extraction zone maintained at extraction conditions including the presence of a sulfolane solvent and a hereinbelow defined reflux stream to provide a second rich solvent stream containing benzene and toluene and non-aromatics, and a raffinate phase substantially free of aromatics; e. passing said second rich solvent stream into a stripping zone maintained under stripping conditions to remove non-aromatics from said second rich solvent as a second overhead vapor stream containing said non-aromatics from said second rich solvent and from a third rich solvent substantially free of non-aromatics containing benzene and toluene; f. cooling second overhead vapor and returning at least a portion thereof to said liquid phase extraction zone of step (d) as said reflux stream; g. recovering benzene and toluene from said third rich solvent as said light extract and passing solvent remaining after said recovery back to said liquid-phase extraction zone of step (d).

Claim 14

A process for the recovery of a heavy aromatic extract comprising toluene and xylene, a light aromatic extract comprising benzene and toluene and a non-aromatic raffinate comprising paraffins and cyclo-paraffins having from about five to about nine carbon atoms per molecule from a hydrocarbon feed stock, which process comprises: a. passing said feed into an extractive distillation zone maintained under extractive distillation conditions including the presence of a sulfolane solvent to provide a first rich solvent substantially free of non-aromatics and containing toluene and xylene and a first overhead vapor stream comprising benzene, toluene and raffinate components; b. recovering toluene and xylene from said first rich solvent as said heavy extract and passing solvent remaining after said recovery back to said extractive distillation zone of step (a); c. cooling said first overhead vapor stream to form a condensed feed; d. passing condensed feed into a liquid phase extraction zone maintained at extraction conditions including the presence of a sulfolane solvent and a hereinbelow defined reflux stream to provide a second rich solvent stream containing benzene and toluene and non-aromatics, and a raffinate phase substantially free of aromatics; e. passing said second rich solvent stream into a stripping zone maintained under stripping conditions to remove non-aromatics from said second rich solvent as a second overhead vapor stream containing said non-aromatics from said second rich solvent and from a third rich solvent substantially free of non-aromatics containing benzene and toluene; f. cooling second overhead vapor and returning at least a portion thereof to said liquid phase extraction zone of step (d) as said reflux stream; g. recovering benzene and toluene from said third rich solvent as said light extract and passing solvent remaining after said recovery back to said liquid-phase extraction zone of step (d).

Claim 15

Claim 12 in that said solvent utilized in said extractive distillation and liquid-phase extraction zone is the same.

Claim 16

Claim 13 in that said solvent comprises tetrahydrothiophene-1,1-dioxide.

Claim 17

Claim 12 in that the average boiling point of said reflux is lower than the average boiling point of said raffinate.

Claim 18

Claim 12 iN that said first overhead vapor stream from the extractive distillation zone and said second overhead vapor stream from said stripping zone are cooled and collected in a common overhead system and said reflux of step (f) is thereby commingled with the feed to the liquid-phase extraction zone.