METHOD AND APPARATUS FOR REMOVING ACID GASES FROM A NATURAL GAS STREAM

• US 20110110833A1
• Filed: 11/12/2009
• Published: 05/12/2011
• Est. Priority Date: 11/12/2009
• Status: Abandoned Application

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Huang, Stanley, Chan, Kaman I., Buckles, John J.
• Application Number:
  US12/617,579
• Publication Number:
  US 20110110833A1
• Time in Patent Office: Days
• US Class Current: 423/228
• CPC Class Codes: B01D 2259/4566 for use in transportation means
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1456 Removing acid components
• CPC Class Codes: C10L 3/103 Sulfur containing contaminants
• CPC Class Codes: C10L 3/104 Carbon dioxide

Abstract

A method and apparatus for separating acid gas from a natural gas stream suitable for use on an offshore facility located on a platform or floating vessel are disclosed. The method includes the steps of: contacting the natural gas stream with a semi-lean amine solution in a static mixer to produce a rich amine solution, separating a first portion of carbon dioxide from the rich amine solution to produce the semi-lean amine solution, and heating a portion of the semi-lean amine solution to separate a second portion of carbon dioxide and produce the lean amine solution. The rich amine solution and semi-lean amine solution can be heated using recovered waste heat.

Claims

1. A method for separating acid gas from a natural gas stream, comprising the steps of:

(a) contacting the natural gas stream with a semi-lean amine solution within a static mixer to produce a first rich amine solution;

(b) separating the first rich amine solution within a separator into a second rich amine solution stream and a semi-clean gas stream;

(c) contacting the semi-clean gas stream with a lean amine solution within an amine absorber;

(d) separating a first portion of acid gas from the second rich amine solution stream to produce the semi-lean amine solution by heating the second rich amine solution stream using recovered waste heat or by reducing the pressure on the second rich amine solution stream; and

(e) separating a second portion of acid gas from the semi-lean amine solution to produce the lean amine solution by heating the semi-lean amine solution using recovered waste heat.

2. The method of claim 1, wherein steps (a) through (e) are conducted on an offshore platform or floating vessel.

3. The method of claim 1, wherein the waste heat is recovered from one or more of a turbine, compressor, and compressor driver.

4. The method of claim 1, wherein the second rich amine solution stream is heated by providing heat to the second rich amine solution stream in a flash vessel from an overhead stream of a stripper column, the stripper column having a reboiler heated with the recovered waste heat.

5. The method of claim 1, wherein the semi-lean amine solution is heated in a stripper column.

6. The method of claim 4, wherein heat is provided to the stripper column through a reboiler heated with the recovered waste heat.

7. The method of claim 1, wherein the natural gas stream contains at least about 7 mol % carbon dioxide before contacting the semi-lean amine solution.

8. An apparatus for liquefying a natural gas stream, the apparatus comprising:

a liquefaction unit having a heat generating unit; and

an acid gas treating unit connected to the liquefaction unit having;

a static mixer for contacting a natural gas stream with a semi-lean amine solution to remove carbon dioxide from the natural gas stream and produce a first rich amine stream;

a separator for separating the first rich amine solution into a second rich amine solution stream and a semi-clean gas stream;

an amine absorber for contacting the semi-clean gas stream with a lean amine solution;

a first flash vessel connected to the amine absorber for separating a first portion of acid gas from the rich amine solution to produce the semi-lean amine solution; and

a stripper column connected to the flash vessel for separating a second portion of carbon dioxide from a portion of the semi-lean amine solution to produce the lean amine solution;

wherein the stripper column is connected to the heat generating unit for receiving heat therefrom.

9. The apparatus of claim 8, wherein one or more of the liquefaction unit and the acid gas treating unit is located off-shore on a platform or floating vessel.

10. The apparatus of claim 8, wherein the heat generating unit comprises one or more of turbine, compressor, and compressor driver.

11. The apparatus of claim 8, wherein the heat generating unit does not comprise a fired heater.