Method for deacidifying a fluid stream and washing liquid used in such a method

• US 20060162559A1
• Filed: 03/04/2003
• Published: 07/27/2006
• Est. Priority Date: 03/12/2002
• Status: Active Grant

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Grossmann, Chirstoph, Asprion, Norbert
• Granted Patent: US 7,749,309 B2
• Time in Patent Office: Days
• US Class Current: 95/235
• CPC Class Codes: B01D 53/1456 Removing acid components
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents

Abstract

Disclosed is a method for deacidifying a fluid stream containing acidic gases as contaminants, according to which the fluid stream is brought into intimate contact with a washing liquid in at least one absorption step. Said washing liquid represents an aqueous solution containing a) tertiary aliphatic alkanolamines (alkanolamine A), at least 30 percent by weight of said tertiary aliphatic alkanolamines being 3-dimethylamino-1-propanol, and b) secondary aliphatic amines (activator B), at least 20 percent by weight of said secondary aliphatic amines being piperazin. The fluid stream which has been essentially purified of the acidic gases is then separated from the washing liquid that is loaded with acidic gases.

Claims

1. A process for deacidifying a fluid stream comprising an acid gas as an impurity, the process comprising

intimately contacting the fluid stream with a scrubbing liquid,

separating a fluid stream substantially free of the acid gas from a scrubbing liquid laden with acid gases,

wherein the scrubbing liquid is an aqueous solution comprising

a) tertiary aliphatic alkanolamines wherein at least 30% by weight of the tertiary aliphatic alkanolamines is 3-dimethylamino-1-propanol and

b) secondary aliphatic amines wherein at least 20% by weight of the secondary aliphatic amines is piperazine,

and said contacting is performed at a total pressure of 2 bar or higher.

2. A process as claimed in claim 1, wherein the concentration of the tertiary aliphatic alkanolamines, based on the scrubbing solution, is from 10 to 60% by weight.

3. A process as claimed in claim 1, wherein the concentration of the secondary aliphatic amines, based on the scrubbing solution, is from 0.1 to 50% by weight.

4. A process as claimed in claim 1, further comprising

regenerating the scrubbing liquid laden with acid gases to form a regenerated scrubbing liquid

and then recirculating the regenerated scrubbing liquid to said intimately contacting step.

5. A process as claimed in claim 4, wherein the said regenerating comprises single- or multistage expansion.

6. A process as claimed in claim 4, wherein said regenerating comprises stripping the scrubbing liquid laden with acid gases with an inert fluid.

7. A process as claimed in claim 1, wherein said contacting step is carried out in a plurality of sequential substeps, said substeps comprising contacting the acid-gas-containing fluid stream with a substream of the scrubbing liquid in each of the substeps.

8. A process as claimed in claim 7, wherein the scrubbing liquid substreams are produced after respective sequential substeps of the regeneration process of the scrubbing liquid, wherein the scrubbing liquid substreams have a decreasing loading of acid gases.