Relating to ethylene oxide recovery

Patent metadata

Field	Value
Publication number	US-10035782-B2
Application number	US-201515515609-A
Country	US
Kind code	B2
Filing date	Sep 29, 2015
Priority date	Oct 1, 2014
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

A process for recovering an ethylene oxide (EO) enriched product stream from fat absorbent (FA) comprising water, EO, and acetaldehyde. The process comprises passing a feed of FA from a loopgas EO absorber to a multi-stage countercurrent distillation zone, the feed of FA having a concentration of EO in the range of from about 1 to about 15 wt % upon entering the distillation zone; and obtaining from the distillation zone an acetaldehyde enriched stream, a lean absorbent (LA) stream, a vapor stream enriched in light ends, a glycol enriched bottoms stream and an EO enriched product stream. Suitable apparatus is also disclosed.

First claim

That which is claimed is:

1. A process for recovering an ethylene oxide (EO) enriched product stream from fat absorbent (FA) comprising water, EO, and acetaldehyde, the process comprising:
passing a feed of FA from a loopgas EO absorber to a multi-stage countercurrent distillation zone, the feed of FA having a concentration of EO in the range of from 1 to 15 wt % upon entering the distillation zone; and
obtaining from the distillation zone an acetaldehyde enriched stream, a lean absorbent (LA) stream, a vapour stream enriched in light ends and an EO enriched product stream,
and wherein the FA comprises glycols and the process comprises obtaining from the distillation zone a glycol enriched bottoms stream.

2. The process of claim 1 comprising stripping light ends from the EO enriched product stream to provide a purified EO product stream.

3. The process of claim 1 , wherein the feed of FA entering the distillation zone comprises in the range of from 1.5 to 10 wt % EO, preferably in the range of from 2 to 8 wt % EO.

4. The process of claim 1 , comprising heat-exchanging the LA stream with the FA feed passed to the distillation zone, and recycling at least part of the LA stream to the loopgas EO absorber.

5. The process of claim 1 , comprising passing the acetaldehyde enriched stream to a concentrator to obtain a concentrated acetaldehyde bleed and one or more other streams recycled to the distillation zone.

6. The process of claim 1 , wherein the EO enriched product stream is obtained from the distillation zone as a side-stream or as an overhead stream.

7. The process of claim 1 , comprising stripping light ends from the EO enriched product stream by countercurrent contact between the EO enriched product stream and a gas.

8. Apparatus for recovering an EO enriched product stream from fat absorbent (FA) comprising water, acetaldehyde, glycols, and ethylene oxide (EO) in a concentration in the range of from 1 to 15 wt %, the apparatus comprising a multi-stage countercurrent distillation column comprising: a FA inlet, an aldehyde outlet for an acetaldehyde enriched stream, a lean absorbent (LA) outlet for a LA stream, and an EO outlet for an EO enriched product stream,
wherein the multi-stage countercurrent distillation column comprises:
a FA inlet,
a glycol bottoms outlet,
a LA side draw constituting the LA outlet,
an acetaldehyde side draw constituting the acetaldehyde outlet, and
the EO outlet,

and wherein the distillation column comprises a base fractionation region of at least five, theoretical vapour-liquid contacting stages below the FA inlet and, in ascending order above the FA inlet, the following further fractionation regions:
a first fractionation region of at least fifteen, theoretical vapour-liquid contacting stages, the acetaldehyde outlet being arranged to withdraw from the column at least a portion of the downflow from the first fractionation region; and
a second fractionation region of at least one, theoretical vapour-liquid contacting stages, the EO outlet being arranged to withdraw from the column at least a portion of the downflow from the second fractionation region.

9. The apparatus of claim 8 , wherein the EO outlet is a side-draw or an overhead outlet.

10. The apparatus of claim 8 further comprising a loopgas EO absorber and a conduit for transporting FA from the loopgas EO absorber to the distillation column, the conduit comprising one or more heat exchangers in fluid communication with the LA outlet to effect heat exchange between FA flowing to the inlet of the distillation column and LA flowing from the LA outlet.

11. The apparatus of claim 8 comprising a concentrator in fluid communication with the acetaldehyde outlet, the concentrator being arranged to concentrate acetaldehyde enriched stream exiting the distillation column via the acetaldehyde outlet into a more concentrated acetaldehyde bleed having a higher concentration of acetaldehyde, and to feed a return stream comprising EO to the distillation column.

12. The apparatus of claim 8 defining a light ends stripping zone arranged to strip light ends from EO enriched product stream exiting the distillation zone via the EO outlet.

13. The apparatus of claim 8 wherein the distillation column as well as the concentrator and/or the light ends stripping zone are integrated into a single column shell.

Assignees

• Shell Int Research
• Shell Oil Co

Inventors

• Olthof Timothe Johannes

Classifications

• C07D301/32 Primary

  Separation; Purification · CPC title

• B01D3/143

  by two or more of a fractionation, separation or rectification step · CPC title

• C07D303/04

  containing only hydrogen and carbon atoms in addition to the ring oxygen atoms · CPC title

• B01D3/009 Primary

  in combination with chemical reactions · CPC title

• Y02P20/10

  Process efficiency · CPC title