Heat pump fractionation process

• US 4,277,268 A
• Filed: 10/17/1979
• Issued: 07/07/1981
• Est. Priority Date: 10/17/1979
• Status: Expired due to Term

• Current Assignee: Conoco Incorporated (ConocoPhillips)
• Original Assignee: Conoco Incorporated (ConocoPhillips)
• Inventors: Spangler, Carl D. Jr.
• Primary Examiner(s): Sever, Frank
• Application Number:
  US06/085,825
• Time in Patent Office: 629 Days
• Field of Search: 203/24, 203/26, 203/78, 203/82, 203/85, 62/26, 62/30, 62/38, 62/39, 208/351, 208/355, 208/354, 208/358, 208/364
• US Class Current: 62/630
• 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 1/289 Compressor features (e.g. constructions, details, cooling, lubrication, driving systems)
• CPC Class Codes: B01D 3/146 Multiple effect distillation

Abstract

A process for fractionating two or more compounds in which the stripping section of the fractionator is maintained at a first pressure and the rectifying section of the fractionator is maintained at a higher pressure. Overhead vapors from the stripping section are compressed in a heat pump where the vapor temperature and pressure are raised, and the heated and compressed vapors are then fed to the bottom of the rectifying section. Overhead vapors from the rectifying section, at a higher temperature than the bottoms from the stripping section, are heat exchanged with stripping section bottoms to condense overhead vapors and to supply reboiling heat to the stripping section.

Claims

1. In a process for separating compounds by fractionation in a fractionator comprised of a stripping section below the feed point and a rectifying section above the feed point, the improvement wherein only a vapor stream from the stripping section at a first temperature and pressure is passed through a single heat pump compressor directly to the rectifying section whereby the vapor stream leaving the heat pump compressor is at a higher temperature and pressure and the rectifying section is maintained at a higher temperature and pressure than the stripping section and bottoms liquid from the stripping section and overhead vapor from the rectifying section are heat exchanged to provide reboiler heat to the stripping section and to condense vapor from the rectifying section.

2. A process for separating chemical compounds having different boiling points in a fractionating unit including a stripping section below the feed point and a rectifying section above the feed point which comprises the steps of:

(a) passing a feed stream comprising a first and a second chemical compound into the fractionating unit;

(b) maintaining the stripping section at a first temperature and pressure;

(c) withdrawing a vapor stream from the stripping section;

(d) compressing only said vapor stream to increase its temperature in a single heat pump compressor and pressure;

(e) passing the compressed stream directly to the rectifying section;

(f) maintaining the rectifying section at a higher pressure and temperature than the stripping section;

(g) withdrawing a product vapor stream rich in said second compound from the rectifying section;

(h) withdrawing a liquid stream rich in said first compound from the stripping section; and

(i) utilizing heat in said product vapor stream from the rectifying section to reboil the stripping section.

3. The process of claim 2 wherein the feedstream is predominantly comprised of propane and butane.

4. A process for separating chemical compounds having different boiling points in a fractionating unit including a stripping section below the feed point and a rectifying section above the feed point which comprises the steps of:

(a) passing a feed stream comprising a first and a second chemical compound into the fractionating unit;

(b) maintaining the stripping section at a first temperature and pressure;

(c) withdrawing an overhead vapor stream from the stripping section;

(d) compressing only said overhead vapor stream to increase its pressure and temperature in a single heat pump compressor;

(e) passing the compressed stream directly to the rectifying section;

(f) maintaining the rectifying section at a higher temperature and pressure than the stripping section;

(g) withdrawing a liquid stream from the bottom of the rectifying section and returning it to the stripping section;

(h) withdrawing an overhead vapor stream rich in said second compound from the rectifying section;

(i) withdrawing a liquid stream rich in said first compound from the bottom of the stripping section;

(j) passing a portion of the liquid stream from the bottom of the stripping section in heat exchange relationship with at least a portion of the overhead vapor stream from the rectifying section whereby the liquid is heated and at least part of the vapor is condensed;

(k) returning the heated liquid stream to the bottom of the stripping section to provide reboiler heat;

(l) recovering the remainder of the liquid stream from the bottom of the stripping section as product;

(m) returning a portion of the condensed vapor from step (j) to the top of the rectifying section as reflux; and

(n) recovering the remainder of the condensed vapor from step (j) as product.