Capturing Carbon Dioxide From High Pressure Streams

• US 20120090464A1
• Filed: 10/12/2011
• Published: 04/19/2012
• Est. Priority Date: 10/12/2010
• Status: Abandoned Application

• Current Assignee: NiQuan Energy LLC
• Original Assignee: NiQuan Energy LLC
• Inventors: Allam, Rodney J.
• Application Number:
  US13/272,001
• Publication Number:
  US 20120090464A1
• Time in Patent Office: Days
• US Class Current: 95/42
• CPC Class Codes: B01D 19/0036 Flash degasification the other groups take precedence
• CPC Class Codes: B01D 2252/2021 Methanol
• CPC Class Codes: B01D 2252/2026 Polyethylene glycol, ethers or esters thereof, e.g. Selexol
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/4005 Nature of purge gas
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 53/002 by condensation
• CPC Class Codes: B01D 53/0462 Temperature swing adsorption
• CPC Class Codes: B01D 53/1431 Pretreatment by other processes
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/261 by adsorption
• CPC Class Codes: F25J 2205/40 using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• CPC Class Codes: F25J 2205/50 using absorption, i.e. with selective solvents or lean oil, heavier CnHm and including generally a regeneration step for the solvent or lean oil
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 3/0625 H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas production of carbon monoxide containing gas in general C01B32/40, C10J, C10K; production of hydrogen containing gas C01B3/00
• CPC Class Codes: F25J 3/0655 separation of hydrogen production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506
• CPC Class Codes: F25J 3/067 separation of carbon dioxide production of carbon dioxide in general C01B32/00
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

The process consists of a combination of a low temperature CO2 condensation separation step followed by either a physical or chemical solvent scrubbing process. The first step results in the partial pressure of CO2 in the gaseous steam being reduced to a value near the triple point pressure of CO2. Typically, the partial pressure of CO2 is reduced to the range 5.5 bar to 7.0 bar. The second stage process then removes the remaining CO2.

Claims

1. A method for removing CO₂ from a high-pressure feed stream for a chemical process, comprising:

cooling the high-pressure feed gas stream to a temperature at least proximate to a freezing temperature of the high-pressure feed stream;

separating, from the cooled high-pressure feed stream, a condensed liquid CO₂ stream that includes at least a portion of hydrocarbon components from the high-pressure feed stream to produce a depleted-CO₂ high-pressure stream; and

removing, the depeleted-CO₂ high-pressure stream, substantially all remaining CO₂ in the cooled gas stream using at least one of a physical solvent scrubbing, a chemical solvent scrubbing, an adsorption separation, or a membrane separation.

2. The method of claim 1, wherein the high-pressure feed stream has partial pressure of CO₂ of at least 8 bars.

3. The method of claim 1, further comprising transferring heat between the high-pressure feed stream and both condensed liquid CO₂ stream and the depleted-CO₂ high-pressure stream.

4. The method of claim 1, wherein the high-pressure feed stream includes a mixture of CO+H₂.

5. The method of claim 1, wherein the high-pressure feed stream is at least a portion of a gas stream from a Fischer-Tropsch hydrocarbon synthesis system.

6. The method of claim 1, wherein the depleted-CO₂ high-pressure stream includes a partial pressure of CO₂ in a range of about 5.5 to about 7 bars.

7. A system for removing CO₂ from a high-pressure feed stream for a chemical process, comprising:

a first stage unit configured to cool the high-pressure feed gas stream to a temperature at least proximate to a freezing temperature of the high-pressure feed stream and separate, from the cooled high-pressure feed stream, a condensed liquid CO₂ stream that includes at least a portion of hydrocarbon components from the high-pressure feed stream to produce a depleted-CO₂ high-pressure stream; and

a second stage unit configured to remove, the depeleted-CO₂ high-pressure stream, substantially all remaining CO₂ in the cooled gas stream using at least one of a physical solvent scrubbing, a chemical solvent scrubbing, an adsorption separation, or a membrane separation.

8. The system of claim 7, wherein the high-pressure feed stream has partial pressure of CO₂ of at least 8 bars.

9. The system of claim 7, further comprising a heat exchanger configured to transfer heat between the high-pressure feed stream and both condensed liquid CO₂ stream and the depleted-CO₂ high-pressure stream.

10. The system of claim 7, wherein the high-pressure feed stream includes a mixture of CO+H₂.

11. The system of claim 7, wherein the high-pressure feed stream is at least a portion of a gas stream from a Fischer-Tropsch hydrocarbon synthesis system.

12. The system of claim 7, wherein the depleted-CO₂ high-pressure stream includes a partial pressure of CO₂ in a range of about 5.5 to about 7 bars.