Process for a dual extract flush

Patent metadata

Field	Value
Publication number	US-11027221-B2
Application number	US-201916515195-A
Country	US
Kind code	B2
Filing date	Jul 18, 2019
Priority date	Oct 19, 2018
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

The present invention relates to dual extract flush for feeds for xylene extraction processes. More specifically, the present invention relates to dual extract flush for feeds for simulated moving bed extraction processes. It decouples line flush in and line flush out, providing a means for optimizing each flush independently. This scheme will allow for minimizing each bedline and flushing each according to its own bedline volume, which will minimize any additional non-ideal compositions added to the chambers or downstream fractionation.

First claim

What is claimed is:

1. A process for a dual extract flush, comprising:
passing a feed and desorbent into a unit wherein the unit comprises a desorption zone, a purification zone, and an adsorption zone wherein the desorption zone is located between a desorbent inlet at the top of the desorption zone and an extract outlet at the top of the purification zone, the purification zone is located between the extract outlet and a feed inlet at the top of the adsorption zone, and the adsorption zone is located between the feed inlet and a raffinate outlet at the bottom of the adsorption zone, wherein the feed is introduced through the feed inlet and the desorbent is introduced through the desorbent inlet;
removing an extract stream from the unit through the extract outlet and splitting a portion of the extract stream into a first flush and a second flush; and
passing the first flush and the second flush back to the unit in the purification zone through a first flush inlet and a second flush inlet.

2. The process of claim 1 , wherein the unit is a para-xylene extraction unit.

3. The process of claim 1 , wherein the unit is a meta-xylene extraction unit.

4. The process of claim 1 , wherein the feed enters the unit at a meeting point of the purification zone and the adsorption zone.

5. The process of claim 1 , wherein the extract is removed from the unit at a meeting point of the desorption zone and the purification zone.

6. The process of claim 1 , wherein the first flush enters the unit below the second flush.

7. The process of claim 1 , wherein the first flush and the second flush enter the unit above the feed but below the extract.

8. The process of claim 1 , wherein the first flush comprises 70% of the flush and the second flush comprises 30% of the flush.

9. The process of claim 1 , wherein the first flush about 60% to about 80% of the flush and the second flush comprises about 40% to about 20% of the flush.

10. The process of claim 1 , wherein the first flush comprises 80% of the flush and the second flush comprises 20% of the flush.

11. The process of claim 1 , wherein the first flush and the second flush are controlled by a control system.

12. The process of claim 1 , wherein the first flush and the second flush may be controlled independently.

13. The process of claim 1 , further comprising combining the extract product stream from the unit, with a line flush out and sending this combined stream to an extract column.

14. The process of claim 1 , wherein the unit comprises a plurality of beds, and the second flush enters the unit two to four beds above the feed.

15. The process of claim 1 , wherein the unit comprises a plurality of beds, and the first flush enters the unit two beds above the feed.

16. The process of claim 11 , further comprising a third flush that may be split from the extract product stream from the unit and sent back to the unit in the purification zone.

17. The process of claim 16 , wherein the third flush may enter the unit in between the second flush and the extract.

18. A process for a dual extract flush, comprising:
passing a feed and a desorbent to a unit comprising a plurality of beds wherein the unit comprises a desorption zone, a purification zone, and an adsorption zone wherein the desorption zone is located between a desorbent inlet at the top of the desorption zone and an extract outlet, the purification zone is located between the extract outlet and a feed inlet, and the adsorption zone is located between the feed inlet and a raffinate outlet at the bottom of the adsorption zone, wherein the feed is introduced through the feed inlet and the desorbent is introduced through the desorbent inlet;
removing an extract stream from the unit through the extract outlet;
splitting the extract stream into a first flush and a second flush; and
passing the first flush and the second flush back to the unit in the purification zone through a first flush inlet and a second flush inlet, wherein the first flush comprises about 60% to about 80% of the flush and the second flush comprises about 40% to about 20% of the flush.

19. The process of claim 18 , wherein the unit comprises a plurality of beds, and the second flush enters the unit below the extract and two to four beds above the feed.

20. The process of claim 18 , wherein the unit comprises a plurality of beds, and the first flush enters the unit below the extract two beds above the feed.

Assignees

• Uop Llc

Inventors

• Mlinar Anton N
• Ernst Gregory A
• Noe R Jason L

Classifications

• C07C7/12 Primary

  by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers · CPC title

• B01D15/185

  characterised by the components to be separated · CPC title

• B01D15/1835 Primary

  Flushing · CPC title

• C07C15/08

  Xylenes · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title