Energy conservation in heavy-hydrocarbon distillation
First Claim
Patent Images
1. A process for producing para-xylene from feed streams containing C8 aromatics and C9-and-heavier aromatics, comprising:
- (a) a distillation process comprising two xylene columns separating C8 aromatics from C9-and-heavier aromatics contained in at least one lower-boiling and at least one higher-boiling feed stream, wherein the at least one higher-boiling feed stream has a higher content of C9-and heavier aromatics than the at least one lower-boiling feed stream, comprising distilling the at least one higher-boiling feed stream in a first xylene column having a reboiler at a low pressure to separate a first C8-aromatics stream from a first C9-and-heavier aromatics stream, distilling the at least one lower-boiling feed stream in a second xylene column at an elevated pressure above the low pressure to separate a second C8-aromatics stream from a second C9-and-heavier aromatics stream, wherein an overhead stream from the second column exchanges heat with the reboiler of the first column;
(b) a para-xylene separation process to recover para-xylene from one or both of the first and second C8-aromatics streams by injecting the one or both C8-aromatics streams and a desorbent stream into a moving-bed adsorption process to obtain a first mixture of para-xylene and desorbent and a second mixture of a raffinate and desorbent; and
,(c) a desorbent-recovery process to separate the second mixture of step (b) by distillation in a prefractionator followed by a pressurized raffinate column into the raffinate and a desorbent stream returned to the separation process, wherein the overhead stream of the second xylene column of step (a) further provides heat to a reboiler of the raffinate column.
2 Assignments
0 Petitions
Accused Products
Abstract
An aromatics complex producing one or more xylene isomers offers a large number of opportunities to conserve energy by heat exchange within the complex. One previously unrecognized opportunity is through providing two parallel distillation columns operating at different pressures to separate C8 aromatics from C9+ aromatics. The parallel columns offer additional opportunities to conserve energy within the complex through heat exchange in associated xylene recovery facilities.
-
Citations
10 Claims
-
1. A process for producing para-xylene from feed streams containing C8 aromatics and C9-and-heavier aromatics, comprising:
-
(a) a distillation process comprising two xylene columns separating C8 aromatics from C9-and-heavier aromatics contained in at least one lower-boiling and at least one higher-boiling feed stream, wherein the at least one higher-boiling feed stream has a higher content of C9-and heavier aromatics than the at least one lower-boiling feed stream, comprising distilling the at least one higher-boiling feed stream in a first xylene column having a reboiler at a low pressure to separate a first C8-aromatics stream from a first C9-and-heavier aromatics stream, distilling the at least one lower-boiling feed stream in a second xylene column at an elevated pressure above the low pressure to separate a second C8-aromatics stream from a second C9-and-heavier aromatics stream, wherein an overhead stream from the second column exchanges heat with the reboiler of the first column; (b) a para-xylene separation process to recover para-xylene from one or both of the first and second C8-aromatics streams by injecting the one or both C8-aromatics streams and a desorbent stream into a moving-bed adsorption process to obtain a first mixture of para-xylene and desorbent and a second mixture of a raffinate and desorbent; and
,(c) a desorbent-recovery process to separate the second mixture of step (b) by distillation in a prefractionator followed by a pressurized raffinate column into the raffinate and a desorbent stream returned to the separation process, wherein the overhead stream of the second xylene column of step (a) further provides heat to a reboiler of the raffinate column. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A process for producing para-xylene from feed streams containing C8 aromatics and C9-and-heavier aromatics, comprising:
-
(a) a distillation process comprising two xylene columns separating C8 aromatics from C9-and-heavier aromatics contained in at least one lower-boiling and at least one higher-boiling feed stream, wherein the at least one higher-boiling feed stream has a higher content of C9-and heavier aromatics than the at least one lower-boiling feed stream, comprising distilling the at least one higher-boiling feed stream in a first xylene column having a reboiler at a low pressure to separate a first C8-aromatics stream from a first C9-and-heavier aromatics stream, distilling the at least one lower-boiling feed stream in a second xylene column having a reboiler at an elevated pressure above the low pressure to separate a second C8-aromatics stream from a second C9-and heavier aromatics stream, wherein an overhead stream from the second column exchanges heat with the reboiler of the first column; (b) a para-xylene separation process to recover para-xylene from one or both of the first and second C8-aromatics streams by injecting the one or both C8-aromatics streams and a desorbent stream into a moving-bed adsorption process to obtain a first mixture of para-xylene and desorbent and a second mixture of a raffinate and desorbent; and
,(c) a desorbent-recovery process which separates the second mixture of step (b) by distillation in a pressurized raffinate column into the raffinate and a desorbent stream returned to the separation process, wherein a reboiler effluent of the second xylene column is separated into a vapor and a liquid stream and the vapor stream provides heat to a reboiler of the raffinate column. - View Dependent Claims (7, 8)
-
-
9. A process for producing para-xylene from feed streams containing C8 aromatics and C9-and-heavier aromatics, comprising:
-
(a) a distillation process comprising two xylene columns separating C8 aromatics from C9-and-heavier aromatics contained in at least one lower-boiling and at least one higher-boiling feed stream, wherein the at least one higher-boiling feed stream has a higher content of C9-and heavier aromatics than the at least one lower-boiling feed stream, comprising distilling the at least one higher-boiling feed stream in a first xylene column having a reboiler at a low pressure to separate a first C8-aromatics stream from a first C9-and-heavier aromatics stream, distilling the at least one lower-boiling feed stream in a second xylene column having a reboiler at an elevated pressure above the low pressure to separate a second C8-aromatics stream from a second C9-and heavier aromatics stream, wherein an overhead stream from the second column exchanges heat with the reboiler of the first column; (b) a para-xylene separation process to recover para-xylene from one or both of the first and second C8-aromatics streams by injecting the one or both C8-aromatics streams and a desorbent stream into a moving-bed adsorption process to obtain a first mixture of para-xylene and desorbent and a second mixture of a raffinate and desorbent; and
,(c) a desorbent-recovery process which separates the second mixture of step (b) by distillation in a prefractionator followed by a pressurized raffinate column into the raffinate and a desorbent stream returned to the separation process, wherein an overhead stream from the raffinate column provides heat to a reboiler of the prefractionator. - View Dependent Claims (10)
-
Specification