US 11,697,631 B2Granted

Process and facility for recovering methoxypropanols from an aqueous stream

AssigneesEvonik Operations GmbH, Thyssenkrupp Industrial Solutions AG

InventorsMichael Kleiber, Willi Hofen

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Abstract

A process can be used for recovering 1-methoxy-2-propanol and 2-methoxy-1-propanol from an aqueous effluent stream by liquid-liquid-extraction, followed by extractive distillation, distillation of methoxypropanols from the extraction solvent, and distillative separation of the methoxypropanol isomers. Recovered extraction solvent is recycled to the extraction and extractive distillation. Heat transfer from recovered extraction solvent to the extract fed to the extractive distillation reduces energy demand of the process. A facility for this process contains a countercurrent extraction column, an extractive distillation column, a solvent recovery distillation column, an isomer separation distillation column, and a heat exchanger for transferring heat from recovered extraction solvent to the extract fed to the extractive distillation.

Claims14

Dependent claims

A process for recovering l-methoxy-2-propanol and 2-methoxy-1-propanol from an aqueous effluent stream, the process comprising:

a) extracting said aqueous effluent stream with an extraction solvent stream in a countercurrent extraction column at a temperature of from 20 to 60° C., to provide a raffinate stream and an extract stream,
b) heating said extract stream by passing it through a heat exchanger on a heat uptake side of the heat exchanger, to provide a heated extract stream,
c) subjecting the heated extract stream to an extractive distillation in an extractive distillation column having an inlet for extraction solvent above an inlet for said heated extract stream, to provide a first overhead stream enriched in water and a first bottoms stream depleted in water relative to said heated extract stream,
d) distilling said first bottoms stream in a solvent recovery distillation column, to provide a second overhead stream comprising 1-methoxy-2-propanol and 2 methoxy-1-propanol and a second bottoms stream comprising recovered extraction solvent,
e) distilling said second overhead stream in an isomer separation distillation column, to provide a third overhead stream comprising 1-methoxy-2-propanol and a third bottoms stream comprising 2-methoxy-1-propanol,
f) cooling said second bottoms stream by passing it through said heat exchanger on a heat delivery side of the heat exchanger, to provide a recovered extraction solvent stream, and
g) passing a part of said recovered extraction solvent stream as the extraction solvent stream to a) and a part of said recovered extraction solvent stream as extraction solvent to the inlet for extraction solvent in c).

4 more elements

A facility for recovering 1-methoxy-2-propanol and 2-methoxy-1-propanol from an aqueous effluent stream, comprising:

a countercurrent extraction column having a feed inlet, an extraction solvent inlet, a raffinate outlet, and an extract outlet;
an extractive distillation column having a feed inlet, an extraction solvent inlet above the feed inlet, an overhead product outlet, and a bottoms product outlet;
a solvent recovery distillation column having a feed inlet, an overhead product outlet, and a bottoms product outlet;
an isomer separation distillation column having a feed inlet, an overhead product outlet, and a bottoms product outlet;
a heat exchanger having a heat supply side and a heat uptake side, each having an inlet and an outlet;
a conduit connecting the extract outlet of the countercurrent extraction column with the inlet of the heat uptake side of the heat exchanger;
a conduit connecting the outlet of the heat uptake side of the heat exchanger with the feed inlet of the extractive distillation column;
a conduit connecting the bottoms product outlet of the extractive distillation column with the feed inlet of the solvent recovery distillation column;
a conduit connecting the overhead product outlet of the solvent recovery distillation column with the feed inlet of the isomer separation distillation column;
a conduit connecting the bottoms product outlet of the solvent recovery distillation column with the inlet of the heat supply side of the heat exchanger;
and
a conduit connecting the outlet of the heat supply side of the heat exchanger with each of the extraction solvent inlet of the countercurrent extraction column and the extraction solvent inlet of the extractive distillation column.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/995,468Filed 23 Mar 2021
Priority: EP 201681266 Apr 2020
Published: US 2023/0122837 A120 Apr 2023
Granted: 11 Jul 2023
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

B01D 3/40
With one or more auxiliary substances: extractive distillation
C07C 41/42
By change of physical state, e.g. by crystallisation: by distillation
B01D 3/007
Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping: energy recuperation; Heat pumps
B01D 3/143
Fractional distillation or use of a fractionation or rectification column: by two or more of a fractionation, separation or rectification step