Vacuum separation of mixtures with similar boiling points

• US 4,056,444 A
• Filed: 04/02/1975
• Issued: 11/01/1977
• Est. Priority Date: 04/24/1974
• Status: Expired due to Term

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Weicht, Bodo, Kleinhenz, Karl
• Primary Examiner(s): Yudkoff, Norman
• Application Number:
  US05/564,395
• Time in Patent Office: 944 Days
• Field of Search: 203/91-94, 203/26, 203/24, 159/17 P, 159/17 VS
• US Class Current: 203/26
• CPC Class Codes: B01D 1/2856 The compressed vapour is used for heating a reboiler or a heat exchanger outside an evaporator
• CPC Class Codes: B01D 3/10 Vacuum distillation B01D3/12 takes precedence
• CPC Class Codes: B01D 3/322 Reboiler specifications

Abstract

This invention relates to the use of a heat pump in combination with a column having a low pressure loss for separating mixtures with similar boiling points in a vacuum of 10 Torr up to normal pressure. By using this arrangement,it is possible to separate isomers in particular, saving heat in relation to normal distillation.

Claims

1. A process for separating mixtures of components which differ in boiling points by up to about 10°

C, comprising distilling the mixture in a distillation column at a reduced pressure of above 10 Torr, supplying heat to the column in an amount of 5-15% of the heat required for heating the column by indirect heat exchange in a first reboiler, collecting the vapors at the top of the column, compressing said vapors and supplying the balance of the heat required for the distillation by indirect heat exchange by condensing the compressed vapors in a second reboiler evaporator.

2. Process of claim 1, wherein in the first evaporator and the second reboiler the indirect heat exchange is with the bottoms product of the distillation.

3. Process of claim 2, wherein the components differ in boiling by up to about 5°

C, and the pressure loss per theoretical plate is less than 1.5 Torr.

4. Process of claim 3, wherein said vapors collected and compressed are all of the vapors from the top of the column.

5. Process of claim 2, wherein the pressure loss per theoretical plate is less than 1.5 Torr.

6. Process of claim 1, wherein the components differ in boiling by up to about 5°

C.

7. Process of claim 6, wherein the pressure loss per theoretical plate is less than 1.5 Torr.

8. Process of claim 1, wherein the pressure loss per theoretical plate is less than 1.5 Torr.

9. A process as claimed in claim 1, when used for separating mixtures of isomers.