Process and installation for the fractionation of air into specific gases

• US 20060213224A1
• Filed: 02/07/2006
• Published: 09/28/2006
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: CO2 Solutions Inc.
• Original Assignee: CO2 Solutions Inc.
• Inventors: Fradette, Sylvie, Paelinck, Philippe
• Granted Patent: US 7,514,056 B2
• Time in Patent Office: Days
• US Class Current: 62/643
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01D 53/84 Biological processes
• CPC Class Codes: F25J 2205/32 as direct contact cooling tower to produce a cooled gas stream, e.g. direct contact after cooler [DCAC]
• CPC Class Codes: F25J 2205/34 as evaporative cooling tower to produce chilled water, e.g. evaporative water chiller [EWC]
• 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 2205/82 using a reactor with combustion or catalytic reaction
• CPC Class Codes: F25J 2210/04 Mixing or blending of fluids with the feed stream
• CPC Class Codes: F25J 2210/42 Nitrogen
• CPC Class Codes: F25J 2210/50 Oxygen
• CPC Class Codes: F25J 2220/40 Separating high boiling, i.e. less volatile components from air, e.g. CO2, hydrocarbons
• CPC Class Codes: F25J 3/04157 Afterstage cooling and so-called "pre-cooling" of the feed air upstream the air purification unit and main heat exchange line F25J3/04618 takes precedence
• CPC Class Codes: F25J 3/04163 Hot end purification of the feed air arrangements of cold regenerators F25J5/00
• CPC Class Codes: F25J 3/04169 by adsorption of the impurities adsorption in general B01D53/02
• CPC Class Codes: F25J 3/04969 Retrofitting or revamping of an existing air fractionation unit
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

In order to reduce incoming atmospheric carbon dioxide levels in compressed air prior to cryogenic distillation, a water spray cooling tower equipped with biocatalytic packing, or fed with absorptive reagents, is used to convert gaseous carbon dioxide into bicarbonate ions which dissolve in the cooling water. The hydration reaction and refrigeration occur synergistically. The bicarbonate ions are subsequently removed from the solution using the heat from the compressed air in a regenerator re-boiler unit, and then fed to a percolation cooling tower for releasing CO₂ and cooling.

Claims

1. A process for fractioning air, comprising the steps of:

a) providing compressed air;

b) simultaneously cooling the compressed air and reducing CO₂ contained therein, by

providing a spray tower;

providing the spray tower with catalyzing means for promoting the hydration reaction of dissolved CO₂ into at least bicarbonate ions and hydrogen ions, thereby producing treated air with a reduced amount of CO₂ and an ion rich solution containing at least bicarbonate ions and hydrogen ions; and

feeding the compressed air into the spray tower while spraying a cooling solvent therein;

c) feeding the treated air to a cold distillation apparatus for fractioning the treated air into at least one gas selected from the group consisting of nitrogen and oxygen.

2. The process of claim 1, further comprising, after step b) and before step c), the step of:

feeding the treated air into at least one adsorption chamber for dehydrating and/or further removing CO₂ from said treated air.

3. The process of claim 1, further comprising, after step b), the step of:

regenerating the ion rich solution by the sub-steps of;

(i) heating the solution to promote conversion of the ions back into at least CO₂ and water, to produce a weak ion solution, and

(ii) cooling the weak ion solution, thereby producing a regenerated cooling solvent.

4. The process of claim 3, wherein step (i) is performed in a regenerator, wherein the CO2 released from the ion rich solution is purged from the regenerator.

5. The process of claim 4, wherein the regenerator is heated with the hot compressed air containing CO₂, thereby heating the ion rich solution and pre-cooling the hot compressed air before the latter is fed into the spray tower.

6. The process of claim 3, wherein step (ii) is performed in a percolation cooling tower, wherein cooling air is fed therein, to produce a regenerated cooling solvent.

7. The process of claim 6, wherein the regenerated cooling solvent is recycled back to the spray tower to be sprayed therein.

8. The process of claim 6, wherein the at least one of the regenerator and the percolation cooling tower is provided with at least one of an enzymatic packing and a biocatalytic packing to promote conversion of the ions back into CO₂ and water.

9. The process of claim 6, wherein the regenerator and the percolation cooling tower operate at pressures lower than a pressure of the compressed air.

10. The process of claim 1, wherein the catalysing means for promoting the hydration reaction of dissolved CO₂ are chosen from a biocatalyst immobilized within the spray tower and absorptive chemical agents.

11. The process of claim 1, wherein the spray tower further comprises a bottom stage and a top stage, a first spray inlet and a second spray inlet for spraying the cooling solvent into the respective stages, the top stage being provided with the catalyzing means, step b) of the process comprising the sub-step of:

initially cooling the compressed air with the cooling solvent of the first spray inlet in the bottom stage, thereby producing a pre-treated air and a weak ion solution at a first liquid outlet, and

cooling the pre-treated air while removing CO₂ therefrom with the cooling solvent of the second spray inlet in the top stage, the catalyzing means promoting the hydration reaction of CO₂, thereby producing the treated air with a reduced amount of CO₂ and the ion rich solution at a second liquid outlet.

12. An installation for fractioning air, comprising:

a compressor for compressing the air to produce compressed air;

a spray tower for simultaneously cooling the compressed air and reducing CO₂ contained therein, the spray tower having an air inlet for receiving the compressed air, at least one liquid spray inlet for receiving and spraying a cooling solvent to contact and cool the compressed air;

the spray tower also comprising catalyzing means for promoting the hydration reaction of dissolved CO₂ into at least bicarbonate ions and hydrogen ions, thereby producing treated air having a reduced amount of CO2 at a gas outlet, and an ion rich solution at at least one liquid outlet;

a cold distillation apparatus for receiving the treated air, the cold distillation apparatus fractioning the treated air into at least one gas selected from the group consisting of nitrogen and oxygen.

13. The installation of claim 12, further comprising:

at least one adsorption chamber in fluid communication with the gas outlet of the spray tower, for receiving the treated air, the adsorption chamber dehydrating and/or further removing the CO₂ from the treated air.

14. The installation of claim 12, further comprising:

a heat exchanger for receiving and heating the ion rich solution exiting the spray towe, while receiving and pre-cooling the compressed air exiting the compressor.

15. The installation of claim 12, further comprising:

a percolation cooling tower for receiving and regenerating the ion rich solution, the percolation cooling tower having a gas outlet for purging the CO₂ released from the ion rich solution, an air inlet for receiving cooling air to cool the ion rich solution and a liquid outlet for removing the regenerated cooling solvent.

16. The installation of claim 15, further comprising:

a regenerator having a liquid inlet in fluid communication with the liquid outlet of the spray tower, the regenerator comprising a reboiler for heating the ion rich solution to promote the conversion of the ions into CO₂ and water, thereby producing a weak ion solution, a gas outlet for purging the CO₂ gas from the regenerator, and a liquid outlet for releasing the weak ion solution to be treated in the percolation cooling tower.

17. The installation of claim 16, wherein the at least one of the regenerator and the percolation cooling tower is provided with at least one of an enzymatic packing and a biocatalytic packing to promote conversion of the ions back into CO₂ and water.

18. The installation of claim 16, wherein the spray tower further comprises a bottom stage and a top stage, the bottom stage comprising:

a gas inlet for receiving the compressed air;

a first spray inlet for spraying the cooling solvent into the bottom stage to cool the compressed air and remove CO₂ therefrom, thereby producing a pre-treated air and a weak ion solution; and

a first liquid outlet for removing the weak ion solution; and

the top stage comprising;

a second spray inlet for spraying the cooling solvent into the top stage;

the catalyzing means for promoting the hydration reaction of dissolved CO₂ into at least bicarbonate ions and hydrogen ions, thereby producing the treated air and the ion rich solution; and

a second liquid outlet for removing the ion rich solution.

19. The installation of claim 18, wherein the first liquid outlet is in fluid communication with the percolation cooling tower for directly feeding the weak ion solution thereto, and the second liquid outlet is in fluid communication with the regenerator for feeding the ion rich solution thereto.

20. The installation of claim 12, wherein the catalyzing means for promoting the hydration reaction of dissolved CO₂ are chosen from a biocatalyst immobilized within the spray tower and absorptive chemical reagents.