Method and means for capture and long-term sequestration of carbon dioxide

• US 20090081096A1
• Filed: 11/24/2008
• Published: 03/26/2009
• Est. Priority Date: 03/28/2007
• Status: Abandoned Application

• Current Assignee: Westec Environmental Solutions, LLC
• Original Assignee: Westec Environmental Solutions, LLC
• Inventors: Pellegrin, Roy J.
• Application Number:
  US12/313,702
• Publication Number:
  US 20090081096A1
• Time in Patent Office: Days
• US Class Current: 423/232
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 47/04 by passing the gas or air or vapour through foam
• CPC Class Codes: B01D 50/40 Combinations of devices covered by groups B01D45/00 and B01D47/00
• CPC Class Codes: B01D 50/60 Combinations of devices covered by groups B01D46/00 and B01D47/00
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/185 Liquid distributors
• CPC Class Codes: B01D 53/62 Carbon oxides
• 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
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

The invention teaches a practical method of recovering CO₂ from a mixture of gases, and sequestering the captured CO₂ from the atmosphere for geologic time as calcium carbonate and provides a CO₂ scrubber for carbon capture and sequestration. CO₂ from the production of calcium oxide is geologically sequestered. A calcium hydroxide solution is produced from the environmentally responsibly-produced calcium oxide. The CO₂ scrubber incorporates an aqueous froth to maximize liquid-to-gas surface area and time-of-contact between gaseous CO₂ and the calcium hydroxide solution. The CO₂ scrubber decreases the temperature of the liquid and the mixed gases, increases ambient pressure on the bubbles and vapor pressure inside the bubbles, diffuses the gas through intercellular walls from relative smaller bubbles with relative high vapor pressure into relative larger bubbles with relative low vapor pressure, and decreases the mean-free-paths of the CO₂ molecules inside the bubbles, in order to increase solubility of CO₂ and the rate of dissolution of gaseous CO₂ from a mixture of gases into the calcium hydroxide solution.

The CO₂ scrubber recovers gaseous CO₂ directly from the atmosphere, from post-combustion flue gas, or from industrial processes that release CO₂ as a result of process. CO₂ reacts with calcium ions and hydroxide ions in solution forming insoluble calcium carbonate precipitates. The calcium carbonate precipitates are separated from solution, and sold to recover at least a portion of the cost of CCS.

Claims

1. A method of capturing and sequestering gaseous carbon dioxide (CO₂) from a mixed gas stream, wherein a reaction chamber is utilized and a mesh panel assembly in said reaction chamber has a plurality of mesh openings, comprising the steps:

continuously saturating said mesh assembly, having a plurality of mesh panels, with a solution containing calcium ions (Ca++) and hydroxide ions (OH−

),

passing said gas stream, having gaseous CO₂, through said saturated mesh assembly to form an aqueous froth wherein the bubbles of said froth have their interior volumes filled with said mixed gases

causing at least some of said bubbles to burst and reform, said bursting bubbles forming numerous micro-droplets having various radii, wherein each reforming bubble encapsulates a discrete volume of said gas stream, a discrete number of said solution micro-droplets, and a discrete volume of solution vapor,

limiting the size of said bubbles formed in said aqueous froth by limiting the size of the openings in said mesh panels, and thereby forming a myriad of uniformly small bubbles, thereby maximizing the contact between said CO₂ molecules, said micro-droplets, and the inner and outer surfaces of said myriad of small bubbles,

cooling said solution before it flows through said saturated mesh panels and cooling said gas inside said bubbles as the bubbles moves downwardly through said reaction chamber,

causing said aqueous froth and said gas stream to move together downwardly through said reaction chamber to increase the reaction time between said gas stream and said myriad of bubbles, and to increase the pressure of said aqueous froth, thereby decreasing the size of said bubbles and increasing solubility of CO₂ molecules into said solution,

minimizing the mean free path of CO₂ molecules inside said bubbles by decreasing the volume of said bubbles to reduce the distance between said inner surfaces of each bubble and said micro-droplets inside each bubble, thereby maximizing contact between said CO₂ molecules and said solution used to form said bubbles and said micro-droplets,

capturing CO₂ molecules carried in said solution by the reaction of said CO₂ molecules with said calcium ions (Ca++) and hydroxide ions (OH−

) in said solution to form calcium carbonate (CaCO₃) molecules, and

precipitating said calcium carbonate out of said solution.

2. The method of claim 1 comprising the further step:

cooling said solution before it flows through said saturated mesh panels.

3. The method of claim 1 wherein said reaction chamber is an elongated, vertically oriented chamber having a bottom portion in fluid communication with a horizontal dewatering chamber, and wherein an adjustable outlet panel changes the size of the opening between the reaction and dewatering chambers, comprising the further step:

adjustably changing the size of the opening between the lower portion of said reaction chamber and said dewatering chamber.

4. The method of claim 3 comprising the further steps:

dewatering said aqueous froth in said dewatering chamber, and

discharging said dewatered gas stream into the atmosphere.

5. The method of claim 1 wherein a settling tank is positioned below said reaction chamber, comprising the further step:

causing said precipitated calcium carbonate to settle downwardly by gravity into said settling tank.

6. The method of claim 5 comprising the further step of continuously removing said precipitated calcium carbonate from said settling tank.

7. The method of claim 1 comprising the further step of separating sulfur from said gas stream by reacting said sulfur with said calcium carbonate in suspension.

8. A method of capturing and sequestering gaseous carbon dioxide (CO₂) from a mixed gas stream, wherein a reaction chamber is utilized and a mesh panel assembly in said reaction chamber has a plurality of mesh openings, comprising the steps:

continuously saturating said mesh assembly, having a plurality of mesh panels, with a solution containing calcium ions (Ca++) and hydroxide ions (OH−

),

passing said gas stream, having gaseous CO₂, through said saturated mesh assembly to form an aqueous froth wherein the bubbles of said froth have their interior volumes filled with said mixed gases

causing at least some of said bubbles to burst and reform, said bursting bubbles forming numerous micro-droplets having various radii, wherein each reforming bubble encapsulates a discrete volume of said gas stream, a discrete number of said solution micro-droplets, and a discrete volume of solution vapor,

limiting the size of said bubbles formed in said aqueous froth by limiting the size of the openings in said mesh panels, and thereby forming a myriad of uniformly small bubbles, thereby maximizing the contact between said CO₂ molecules, said micro-droplets, and the inner and outer surfaces of said myriad of small bubbles,

causing said aqueous froth and said gas stream to move together downwardly through said reaction chamber to increase the reaction time between said gas stream and said myriad of bubbles, and to increase the pressure of said aqueous froth, thereby decreasing the size of said bubbles and increasing solubility of CO₂ molecules into said solution,

minimizing the mean free path of CO₂ molecules inside said bubbles by decreasing the volume of said bubbles to reduce the distance between said inner surfaces of each bubble and said micro-droplets inside each bubble, thereby maximizing contact between said CO₂ molecules and said solution used to form said bubbles and said micro-droplets,

capturing CO₂ molecules carried in said solution by the reaction of said CO₂ molecules with said calcium ions (Ca++) and hydroxide ions (OH−

) in said solution to form calcium carbonate (CaCO₃) molecules, and

precipitating said calcium carbonate out of said solution.

9. The method of claim 8 comprising the further step of cooling said myriad of bubbles as the bubbles move downwardly through said reaction chamber.

10. The method of claim 8 wherein said solution is cooled before it passes through said mesh panels.

11. The method of claim 8 wherein said solution includes calcium hydroxide and an alkali earth metal hydroxide.

12. A method of capturing and sequestering gaseous carbon dioxide (CO₂) from a mixed gas stream, wherein a reaction chamber is utilized and a mesh panel assembly in said reaction chamber has a plurality of mesh openings, comprising the steps:

continuously saturating said mesh assembly, having a plurality of mesh panels, with a sodium hydroxide solution,

passing said gas stream, having gaseous CO₂, through said saturated mesh assembly to form an aqueous froth wherein the bubbles of said froth have their interior volumes filled with said mixed gases

causing at least some of said bubbles to burst and reform, said bursting bubbles forming numerous micro-droplets having various radii, wherein each reforming bubble encapsulates a discrete volume of said gas stream, a discrete number of said solution micro-droplets, and a discrete volume of solution vapor,

limiting the size of said bubbles formed in said aqueous froth by limiting the size of the openings in said mesh panels, and thereby forming a myriad of uniformly small bubbles, thereby maximizing the contact between said CO₂ molecules, said micro-droplets, and the inner and outer surfaces of said myriad of small bubbles,

causing said aqueous froth and said gas stream to move together downwardly through said reaction chamber to increase the reaction time between said gas stream and said myriad of bubbles, and to increase the pressure of said aqueous froth, thereby decreasing the size of said bubbles and increasing solubility of CO₂ molecules into said solution,

minimizing the mean free path of CO₂ molecules inside said bubbles by decreasing the volume of said bubbles to reduce the distance between said inner surfaces of each bubble and said micro-droplets inside each bubble, thereby maximizing contact between said CO₂ molecules and said solution used to form said bubbles and said micro-droplets,

capturing CO₂ molecules carried in said solution by the reaction of said CO₂ molecules with said sodium hydroxide solution to form sodium bicarbonate molecules, and

precipitating said sodium bicarbonate out of said solution.

13. The method of claim 12 comprising the further step of cooling said myriad of bubbles as the bubbles move downwardly through said reaction chamber.

14. Apparatus for capturing and sequestering gaseous carbon dioxide CO₂ from a mixed gas stream, wherein calcium ions and hydroxide ions react with carbon dioxide to form calcium carbonate as a precipitate, comprising:

a vertically extending reaction chamber having upper and lower sections,

an array of mesh panels positioned at said upper section of said reaction chamber,

means for continuously saturating said mesh panels with a solution containing calcium or sodium ions and hydroxide ions,

forth generator means positioned above said array of mesh panels,

a duct carrying said mixed gas stream into said froth generator means,

whereby said froth generator means forms an aqueous froth having a myriad of small bubbles wherein the interior volumes of said bubbles are filled with gas from said mixed gas stream containing gaseous carbon dioxide,

means for cooling said aqueous froth,

means for pressurizing said aqueous froth to reduce the size of said myriad of bubbles as said froth moves to said lower section of said reaction chamber, and

settling tank means below said reaction chamber for collecting calcium carbonate or sodium bicarbonate precipitates.