Method for separating materials by means of an extractive distillation process

Patent metadata

Field	Value
Publication number	US-10793494-B2
Application number	US-201716072695-A
Country	US
Kind code	B2
Filing date	Feb 2, 2017
Priority date	Feb 5, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A method for separating a mixture of materials A and B by extractive distillation, using an extraction medium having a higher affinity to B than to A, collecting a liquid fraction on a collecting tray and heated and partially evaporated in a first indirect heat exchanger, collecting the resultant vapor is released into the column and a non-evaporated proportion of the liquid fraction in the sump of the column, and a series of heating, separation and cooling where partially cooled extraction medium fraction is used as heating medium for a heat exchanger.

First claim

The invention claimed is:

1. A method for separating a mixture of a material A and a material B by extractive distillation, using an extraction medium having a higher affinity to B than to A, wherein the method comprises:
a) conducting a feed stream comprising A and B towards the extraction medium in a column, wherein an overhead fraction comprising A, and also a liquid fraction comprising B and extraction medium, are obtained,
b) collecting the liquid fraction on a collecting tray and heating and partially evaporating the liquid fraction in a first indirect heat exchanger, where a first resultant vapor is released into the column and a non-evaporated proportion of the liquid fraction is collected as a sump fraction in a sump of the column,
c) successively heating the sump fraction in a second indirect heat exchanger and a third indirect heat exchanger and in part evaporating the sump fraction, wherein a second resultant vapor is at least in part released into the column,
d) separating the sump fraction in a stripper, into: i) a fraction comprising B and ii) an extraction medium fraction,
e) using the extraction medium fraction as a heating medium for the second indirect heat exchanger, wherein a partially cooled extraction medium fraction is obtained, and an external heating medium is used for the third indirect heat exchanger, and
f) using the partially cooled extraction medium fraction as a heating medium for the first indirect heat exchanger.

2. The method according to claim 1 , wherein the sump fraction is successively conducted through the second indirect heat exchanger and the third indirect heat exchanger.

3. The method according to claim 2 , wherein, downstream of the third heat exchanger, a circulated sump fraction is conducted through a cell, communicating a vapor side with the column, where in the cell a resultant vapor is separated off from the sump fraction, and a vapor is separated from the the sump fraction.

4. The method according to claim 3 , wherein the cell is integrated into the sump of the column, or is a phase separator arranged outside the column.

5. The method according to claim 1 , wherein the sump fraction is conducted through three cells, each communicating with a vapor side with the column, by collecting the sump fraction in a first cell integrated into the sump of the column, taking off the sump fraction from the first cell and conducting it through the second indirect heat exchanger into a second cell, taking off the sump fraction from the second cell and conducting it through the third indirect heat exchanger into a third cell and taking off from the third cell the sump fraction that is to be fed to the stripper.

6. The method according to claim 5 , wherein the three cells are integrated into the sump of the column.

7. The method according to claim 5 , wherein the third cell is a phase separator arranged outside the column.

8. The method according to claim 5 , wherein the second cell is a phase separator arranged outside the column.

9. The method according to claim 1 , wherein the first indirect heat exchanger is a natural-circulation evaporator.

10. The method according to an claim 1 , wherein
i. A is butane and B is butene, butadiene or a mixture thereof, or
ii. A is pentane and B is pentene, isoprene or a mixture thereof, or
iii. A is hexane and B is benzene, or
iv. A is 2-propanol and B is water, or
v. A is hydrogen chloride and B is water, or
vi. A is acetonitrile and B is water, or
vii. A is 2-butyl acetate and B is 2-butanol, or
viii. A is tetrahydrofuran and B is methanol, or
ix. A is acetone and B is chloroform, or
x. A is ethanol and B is water, or
xi. A is acetone and B is methanol, or
xii. A is a mixture of ethanol and water and B is ethyl acetate.

11. The method according to claim 10 , wherein the extraction medium comprises, in the case of
i. dimethylformamide, N-methylpyrrolidone, acetonitrile, furfural, or dimethyl sulfoxide,
ii. dimethylformamide or N-methylpyrrolidone,
iii. phenol, N-methylpyrrolidone, or N-formylmorpholine,
iv. a solution of calcium chloride in water, dimethyl sulfoxide, or ethylene glycol,
v. sulfuric acid,
vi. ethylene glycol,
vii. N,N-dimethylacetamide,
viii. water,
ix. dimethyl sulfoxide,
x. ethylene glycol, glycerol, or dimethyl sulfoxide,
xi. water,
xii. dimethyl sulfoxide, glycerol, diethylene glycol, 1-naphthol, hydroquinone, or dimethylformamide.

12. The method according to claim 1 , wherein A is butane and B is butene, butadiene or mixtures thereof, and the extraction medium comprises N-methylpyrrolidone.

Assignees

• Basf Se

Inventors

• Asprion Norbert

Classifications

• C07C7/08 Primary

  by extractive distillation · CPC title

• B01D3/322

  Reboiler specifications · CPC title

• B01D3/143

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

• C07C253/34

  Separation; Purification · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title