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Title:
APPARATUS, SYSTEMS AND METHODS FOR THIN FILM MASS TRANSFER OF NITROGEN AND OTHER GASES INTO BEER AND OTHER LIQUIDS
Document Type and Number:
WIPO Patent Application WO/2012/100333
Kind Code:
A1
Abstract:
A method for effecting mass transfer of nitrogen gas into beer, including providing a chamber having nitrogen gas therein, providing at least one surface within the chamber, providing beer on each surface, and providing a relative velocity between the beer and the at least one surface. The relative velocity is selected such that the beer forms a thin film on the at least one surface to facilitate thin film gasification of the nitrogen in the beer.

Inventors:
REED DAVID (CA)
RODRIGUEZ JESSICA (CA)
KOSLOW EVAN (CA)
BECKETT RICHARD (CA)
FERNANDES PATRICK (CA)
MITCHELL ANDREW (CA)
Application Number:
PCT/CA2012/000071
Publication Date:
August 02, 2012
Filing Date:
January 27, 2012
Export Citation:
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Assignee:
EVANTAGE TECHNOLOGIES LLC (US)
REED DAVID (CA)
RODRIGUEZ JESSICA (CA)
KOSLOW EVAN (CA)
BECKETT RICHARD (CA)
FERNANDES PATRICK (CA)
MITCHELL ANDREW (CA)
International Classes:
B01F1/00; B01F3/04; C12C11/11
Domestic Patent References:
WO2010105351A12010-09-23
WO2005039731A22005-05-06
Foreign References:
EP0947463A11999-10-06
US20050053532A12005-03-10
US20070200262A12007-08-30
Attorney, Agent or Firm:
BERESKIN & PARR LLP/SENCRL, SRL (40th FloorToronto, Ontario M5H 3Y2, CA)
Download PDF:
Claims:
Claims

1. A method for effecting mass transfer of nitrogen gas into beer, comprising: providing a chamber having nitrogen gas therein;

providing at least one surface within the chamber;

providing beer on each surface; and

rotating each surface at an angular velocity selected such that the beer forms a thin film on the surface to facilitate thin film gasification of the nitrogen in the beer.

2. The method of claim 1 , wherein the angular velocity is selected to inhibit separation of the beer from each surface as liquid particles to inhibit foaming of the beer.

3. The method of claim 1 , wherein the angular velocity is between about 300 and 400 revolutions per minute.

4. The method of claim 1 , wherein the angular velocity is selected so that the concentration of nitrogen in the beer is between about 15 and 90 parts per million.

5. The method of claim 1 , wherein the at least one surface includes a surface on a disc.

6. The method of claim 5, wherein the angular velocity is selected so that the beer separates from the edge of the disc as a cascade with substantially laminar flow.

7. The method of claim 5, wherein the angular velocity is selected such that the thin film gasification substantially occurs before the beer separates from an edge of the disc.

8. The method of claim 1 , wherein the temperature in the chamber is between about 30 degrees Fahrenheit and 80 degrees Fahrenheit during thin film gasification.

9. The method of claim 1 , wherein the temperature in the chamber is between 36 degrees Fahrenheit and 42 degrees Fahrenheit during thin film gasification.

10. The method of claim 1 , wherein the pressure in the chamber is greater than atmospheric pressure.

1 1. The method of claim 1 , wherein the at least one surface includes a flat upper surface.

12. The method of claim 1 , wherein the at least one surface includes a convex surface.

13. The method of claim 1 , wherein the at least one surface includes a concave surface.

14. A method for effecting mass transfer of gas into a liquid, comprising:

providing a chamber having the gas therein;

providing at least one surface within the chamber; providing a liquid on each surface; and

rotating each surface at an angular velocity selected such that the liquid forms a thin film on the surface to facilitate thin film gasification of the liquid.

15. The method of claim 14, wherein the angular velocity is selected to inhibit separation of the beer from each surface as liquid particles.

16. The method of claim 14, wherein the angular velocity is between about 50 and 1500 revolutions per minute.

17. The method of claim 14, wherein the angular velocity is selected so that the concentration of gas in the liquid is between about 15 and 90 parts per million.

18. The method of claim 4, wherein the at least one surface includes a surface on a disc.

19. The method of claim 18, wherein the angular velocity is selected so that the liquid separates from the edge of the disc as a cascade with substantially laminar flow.

20. The method of claim 18, wherein the angular velocity is selected such that the thin film gasification substantially occurs before the liquid separates from an edge of the disc.

21. The method of claim 15, wherein the temperature in the chamber is between about 30 degrees Fahrenheit and 80 degrees Fahrenheit during thin film gasification.

22. The method of claim 15, wherein the temperature in the chamber is between about 36 degrees Fahrenheit and 42 degrees Fahrenheit during thin film gasification.

23. The method of claim 15, wherein the gas includes nitrogen.

24. The method of claim 5, wherein the gas includes carbon dioxide

25. The method of claim 5, wherein the liquid is a beer.

26. The method of claim 15, wherein the pressure in the chamber is greater than atmospheric pressure.

27. The method of claim 15, wherein the at least one surface includes a flat upper surface.

28. The method of claim 15, wherein the at least one surface includes a convex surface.

29. The method of claim 15, wherein the at least one surface includes a concave surface.

30. An apparatus for mass transfer of a gas into a liquid, comprising: a tank that defines a chamber for receiving the gas; and

at least one surface provided within the chamber;

wherein each surface is configured to receive the liquid and rotate at an angular velocity selected such that the liquid forms a thin film on the surface to facilitate thin film gasification of the liquid.

31. The apparatus of claim 30, wherein the angular velocity is selected to inhibit separation of the beer from each surface as liquid particles.

32. The apparatus of claim 30, wherein the angular velocity is between about 50 and 1500 revolutions per minute.

33. The apparatus of claim 30, wherein the angular velocity is selected so that the concentration of gas in the liquid is between about 15 and 90 parts per million.

34. The apparatus of claim 30, wherein the at least one surface includes a surface on a disc.

35. The apparatus of claim 34, wherein the angular velocity is selected so that the liquid separates from the edge of the disc as a cascade with substantially laminar flow.

36. The apparatus of claim 34, wherein the angular velocity is selected such that the thin film gasification substantially occurs before the liquid separates from an edge of the disc.

37. The apparatus of claim 30, wherein the temperature in the chamber is between about 30 degrees Fahrenheit and 80 degrees Fahrenheit during thin film gasification.

38. The apparatus of claim 30, wherein the temperature in the chamber is between about 36 degrees Fahrenheit and 42 degrees Fahrenheit during thin film gasification.

39. The apparatus of claim 30 wherein the gas includes nitrogen.

40. The apparatus of claim 30, wherein the gas includes carbon dioxide

41. The apparatus of claim 30, wherein the liquid is a beer.

42. The apparatus of claim 30, wherein the pressure in the chamber is greater than atmospheric pressure.

43. The apparatus of claim 30, further comprising a capacitive element coupled to the chamber and adapted to absorb excess gases as the pressure in the chamber increase.

44. The apparatus of claim 43, wherein the capacitive element is a flexible bladder.

45. The method of claim 1 , wherein the at least one surface includes a flat upper surface.

46. The method of claim 1 , wherein the at least one surface includes a convex surface.

47. The method of claim 1 , wherein the at least one surface includes a concave surface.

48. A method for effecting mass transfer of nitrogen gas into beer, comprising: providing a chamber having nitrogen gas therein;

providing at least one fixed surface within the chamber;

providing beer on each surface; and

providing a relative velocity between the beer and the at least one surface, the relative velocity selected such that the beer forms a thin film on the at least one surface to facilitate thin film gasification of the nitrogen in the beer.

49. The method of claim 48, wherein the at least one surface is an inverted conical surface and the beer is provided with an input velocity selected so that the beer adopts a swirling motion on the conical surface.

50. The method of claim 49, wherein the beer is provided with an input velocity having a horizontal component.

51. The method of claim 49, wherein the beer is provided with an input velocity having a vertical component.

52. A method for effecting mass transfer of gas into a liquid, comprising:

providing a chamber having the gas therein; providing at least one fixed surface within the chamber;

providing a liquid on each surface; and

providing a relative velocity between the liquid and the at least one surface, the relative velocity selected such that the liquid forms a thin film on the at least one surface to facilitate thin film gasification of the liquid.

53. The method of claim 52, wherein the at least one surface is an inverted frustoconical surface and the liquid is provided with an input velocity selected so that the liquid adopts a swirling motion on the conical surface.

54. The method of claim 53, wherein the liquid is provided with an input velocity having a horizontal component.

55. The method of claim 43, wherein the liquid is provided with an input velocity having a vertical component.

56. An apparatus for mass transfer of a gas into a liquid, comprising:

a tank that defines a chamber for receiving the gas; and

at least one fixed surface provided within the chamber;

wherein the at least one surface is configured to receive the liquid thereon and provide a relative velocity between the liquid and the at least one surface, the relative velocity selected such that the liquid forms a thin film on the at least one surface to facilitate thin film gasification of the liquid.

57. The apparatus of claim 56, further comprising an inlet spout for supplying the liquid with an input velocity relative to the at least one surface so as to provide the relative velocity between the liquid and the at least one surface.

58. The apparatus of claim 57, wherein the at least one surface is an inverted conical surface.

59. The apparatus of claim 58, wherein the liquid is provided with an input velocity having a horizontal component.

60. The apparatus of claim 58, wherein the liquid is provided with an input velocity having a vertical component.

61. The apparatus of claim 58 wherein conical surface has slope angle Θ generally with respect to a horizontal plane.

62. The apparatus of claim 61 , wherein the slope angle Θ is between 5 degrees and 85 degrees.

63. The apparatus of claim 61 , wherein the slope angle Θ is between 30 degrees and 60 degrees.

Description:
Title: Apparatus, Systems and Methods for Thin Film Mass Transfer Of Nitrogen and Other Gases Into Beer and Other Liquids

Related Applications

This application is related to PCT/CA2009/00323 entitled APPARATUS, SYSTEMS AND METHODS FOR MASS TRANSFER OF GASES INTO LIQUIDS filed on March 16, 2009, the entire contents of which are hereby incorporated by reference herein for all purposes; and this application is also related to PCT/CA2010/000390, entitled APPARATUS, SYSTEMS AND METHODS FOR MASS TRANSFER OF GASES INTO LIQUIDS filed on March 16, 2010, the entire contents of which also are hereby incorporated by reference herein for all purposes; and this application also claims the benefit of U.S. Provisional Patent Applications Serial Nos. 61/437,166 and 61/467,314 both entitled APPARATUS, SYSTEMS AND METHODS FOR THIN FILM MASS TRANSFER OF NITROGEN AND OTHER GASES INTO BEER AND OTHER LIQUIDS filed on January 28, 2011 and March 24, 2011 , respectively, the entire contents of both of which are also hereby incorporated by reference herein for all purposes.

Technical Field

[0001] The embodiments disclosed herein relate to mass transfer, and in particular to apparatus, systems and methods for effecting thin film mass transfer of nitrogen and other gases into beer and other liquids, such as beverages.

Introduction

[0002] There are numerous industrial processes and types of equipment used to promote the mass transfer of gases into liquids. In many cases, the mass transfer of a gas into a liquid is limited by the mass-transfer resistance at the gas-liquid interface and the diffusion of the gas away from this interface. For example, the binary diffusion coefficient of carbon dioxide in air is 0.139 sq. cm/sec, while the binary diffusion coefficient for carbon dioxide in water is 0.00002 sq. cm/sec. [0003] Since the diffusivity of a gas within a gas is typically around 1 ,000-10,000 times greater than the diffusivity of a gas into a liquid, dispersion of the liquid is important for effecting mass transfer of a gas into a liquid. For example, if a liquid can be dispersed as droplets having a characteristic droplet length roughly equal to the square root of the binary diffusion coefficient (e.g. for carbon dioxide into water, νΌ.00002 = 0.0044 cm, or 44 micrometers), then the diffusion will tend to be extraordinarily rapid.

[0004] Generally, in such embodiments, to provide for optimum mass transfer rates, all of the liquid particles should be provided with a similar droplet size having the characteristic diffusion length. Any quantity of liquid particles that has a larger droplet size will not provide for rapid diffusion, and will not reach equilibrium in the surrounding gas environment within a brief period of time (as is the case with the smaller liquid droplets).

[0005] In many prior art systems, the mass-transfer resistance may be partially overcome by increasing the gas-liquid surface (e.g. by performing mechanical work on the liquid). For example, some systems use powerful mechanical mixers to agitate a liquid. Other systems create small bubbles of gas by pressing a gas through small orifices, and then the bubbles are allowed to rise through a liquid column. However, neither of these approaches is particularly good at overcoming the mass-transfer resistance.

[0006] One technique that would be beneficial is to cause the liquid to be dispersed into the gas, rather than the gas into the liquid. In practice, however, this is very difficult to achieve. Some prior art systems attempt this using high-pressure nozzles to disperse a liquid as fine droplets. Other systems use a two-phase flow of gas and liquid through a nozzle at lower pressure. However, these types of systems are generally undesirable, as they may require high-pressure, pressure-boosting pumps to be used, or make an undesirable use of gas to disperse the liquid (e.g. using two-phase nozzles). In particular, when attempting a precision transfer of gas into liquid, two-phase nozzles are often unacceptable as the amount of gas required to accomplish the required breakup of the liquid is normally not the quantity of gas that is desired to be dispersed into the liquid.

[0007] Accordingly, such systems are not appropriate for many applications, especially where precise control of the ratio of gas to liquid is desired, such as in beverage carbonation (e.g. for soda pop and similar beverages) or when dispersing nitrogen into beer.

Summary

[0008] In some embodiments described herein, a fine dispersion of liquid is generated using a spinning disc apparatus to generate small liquid particles. The small liquid particles are then dispersed into gas to carry out the mass transfer of the gas into the liquid droplets. The liquid particles may then coalesce with the chamber and/or against the walls of the chamber, and be subsequently collected for extraction.

[0009] Some embodiments as described herein provide an apparatus that tends to produce a uniform and precise dispersion of a liquid into a mist or spray having a specific droplet size and with minimal potential for any significant volume of the liquid being dispersed as over-sized droplets (e.g. droplets that are larger than desired). In some examples, this dispersion may be carried out within a space or chamber that operates at elevated pressure so as to cause a gas to rapidly dissolve into the liquid droplets and approach equilibrium saturation during the flight time of the droplets (e.g. between when they are thrown or disengage from the spinning disc and before contacting the walls of the chamber). To accomplish the required mass transfer within the brief flight time of the droplets, the droplets generally should be extremely small. Furthermore, the distance between the edge of the spinning disc and the walls of the chamber should be sufficient to allow the droplets to closely approach saturation with the surrounding gas prior to being arrested against the walls. If the droplets are sufficiently small, they will slow and even come to rest before engaging the chamber walls and thus their contact time with the gas can be extended. [0010] Other embodiments as described herein are directed to methods and apparatus for providing for the mass transfer of gas into liquid via thin film gasification and generally without dispersing liquid particles. For example, according to one aspect there is provided a method for effecting mass transfer of gas into a liquid that includes providing a chamber having the gas therein, providing at least one surface within the chamber, providing a liquid on each surface, and rotating each surface at an angular velocity selected such that the liquid forms a thin film on the surface to facilitate thin film gasification of the liquid. The angular velocity may be selected to inhibit the separation of the liquid from each surface as liquid particles.

[0011] According to one particular aspect, there may be provided a method for effecting mass transfer of nitrogen gas into beer, comprising providing a chamber having nitrogen gas therein, providing at least one surface within the chamber, providing beer on each surface, and rotating each surface at an angular velocity selected such that the beer forms a thin film on the surface to facilitate thin film gasification of the nitrogen in the beer. The angular velocity may be selected to inhibit separation of the beer from each surface as liquid particles to inhibit foaming.

[0012] According to another particular aspect, there may be provided a method for effecting mass transfer of gas into a liquid, comprising providing a chamber having the gas therein, providing at least one fixed surface within the chamber, providing a liquid on each surface, and providing a relative velocity between the liquid and the at least one surface. The relative velocity may be selected such that the liquid forms a thin film on the at least one surface to facilitate thin film gasification of the liquid.

[0013] According to another particular aspect, there may be provided a method for effecting mass transfer of nitrogen gas into beer, comprising providing a chamber having nitrogen gas therein, providing at least one fixed surface within the chamber, providing beer on each surface, and providing a relative velocity between the beer and the at least one surface. The relative velocity may be selected such that the beer forms a thin film on the at least one surface to facilitate thin film gasification of the nitrogen in the beer.

[0014] According to another particular aspect, there may be provided an apparatus for mass transfer of a gas into a liquid comprising a tank that defines a chamber for receiving the gas, and at least one fixed surface provided within the chamber. The at least one surface is configured to receive the liquid thereon and provide a relative velocity between the liquid and the at least one surface. The relative velocity may be selected such that the liquid forms a thin film on the at least one surface to facilitate thin film gasification of the liquid.

Brief Description of the Drawings

[0015] The drawings included herewith are for illustrating various examples of apparatus, systems and methods of the present specification and are not intended to limit the scope of what is taught in any way. In the drawings:

[0016] Figure 1 is a cross-sectional perspective view of an apparatus for mass transfer of a gas into a liquid according to one embodiment;

[0017] Figure 2 is a cross-sectional elevation view of the apparatus of Figure 1 ;

[0018] Figure 3 is an overhead schematic view of the spinning disc and chamber of the apparatus of Figure 1 ;

[0019] Figure 4 is a schematic side view of an apparatus for effecting mass transfer of gases into liquids according to another embodiment;

[0020] Figure 5 is a schematic side view of the apparatus of Figure 4 with a convex disc;

[0021] Figure 6 is a schematic side view of the apparatus of Figure 4 with a concave disc;

[0022] Figure 7 is a schematic side view of the apparatus of Figure 4 with a rotating sphere; [0023] Figure 8 is a schematic side view of the apparatus of Figure 4 with a rotating spherical object having a flanged bottom;

[0024] Figure 9 is a schematic side view of the apparatus of Figure 4 with a rotating egg-shaped object;

[0025] Figure 10 is a schematic side view of the apparatus of Figure 4 with a rotating torpedo-shaped object;

[0026] Figure 1 1 is a schematic side view of the apparatus of Figure 4 with a rotating cone;

[0027] Figure 12 is a schematic side view of the apparatus of Figure 4 with a rotating umbrella-shaped object;

[0028] Figure 13 is a schematic side view of the apparatus of Figure 4 with a rotating funnel;

[0029] Figure 14 is a cross-sectional perspective view of a stationary apparatus for mass transfer of a gas into a liquid according to another embodiment;

[0030] Figure 15 is a schematic side view of the apparatus of Figure 14 showing secondary walls; and

[0031] Figure 16 is a schematic side view of another apparatus for effecting the mass transfer of a gas into a liquid.

Detailed Description

[0032] Illustrated in Figures 1 to 3 is an apparatus 10 for mass transfer of a gas into a liquid according to one embodiment. The apparatus 10 generally includes a tank 12 that defines a chamber 14 into which the gas and liquid may be generally received for effecting the mass transfer.

[0033] The apparatus 10 also generally includes a disc 20 that is provided within the chamber 14. The disc 20 has a surface configured to receive a liquid thereon and can rotate so as to cause mass transfer of a gas into a liquid. [0034] As will be discussed below, in some embodiments, the disc 20 may be rotated at speeds selected to form a fine dispersion of liquid particles to be ejected from the edges thereof (e.g. atomization of the liquid particles, also referred to generally as a "liquid particle" mode).

[0035] In other embodiments, the disc 20 may be rotated at speeds selected to form a thin film of liquid on the disc 20 (also referred to as a "thin film" mode), providing for thin film gasification of the liquid without substantially ejecting liquid particles from the edge of the disc 20. Such thin film modes may be useful for certain combinations of liquids and gases, such as beer and nitrogen.

[0036] As shown, the tank 12 may be a pressure vessel or any other suitable vessel. In some embodiments, the tank 12 and may be capable of operating at elevated pressures according to the desired operating conditions of the apparatus 10. For instance, in some examples, the tank 12 may be configured to operate up to pressures of 3 atmospheres or greater.

[0037] As shown, the tank 12 may include a separate top tank head 16 and bottom tank head 18, each having upper and lower mounting flanges 22, 24 extending outwardly from the perimeter thereof. The mounting flanges 22, 24 may be coupled together using one or more fasteners (e.g. bolts 28, washers 30 and nuts 32) so as to secure the upper tank head 16 and lower tank head 18 together to define the chamber 14 therebetween.

[0038] In some examples, a flange gasket 26 may be provided between the flanges 22, 24 so as to help seal the tank heads 16, 18 together and to inhibit leaks.

[0039] As shown, each of the upper and lower tank heads 16, 18 have outer walls generally located around the perimeter of the chamber 14. For example, the upper tank head 16 has a peripheral upper chamber wall 34, and the lower tank head 18 has a peripheral lower chamber wall 36.

[0040] The upper tank head 16 may have a bulkhead fitting 38 (or liquid inlet fitting) that is adapted to be coupled to a liquid supply (e.g. using a hose, not shown) so that liquid may be pumped into the chamber 14 during use of the apparatus 10.

[0041] The upper tank head 16 may include an upper puck 40 for securing the bulkhead fitting 38 to the tank head 16. The upper puck 40 may help to stabilize the upper tank head 16 so as to provide for a more secure coupling of the bulkhead fitting 38. In some examples, the bulkhead fitting 38 and upper puck 40 may be welded to the upper tank head 16.

[0042] The bulkhead fitting 38 is coupled to an inlet spout 42 that extends generally downwardly into the chamber 14. The inlet spout 42 is configured to provide liquid (usually to an inner region 20a) of the spinning disc 20 during use of the apparatus 10, as will be described in greater detail below.

[0043] The upper tank head 16 in this embodiment also generally includes a gas inlet 44 (shown in Figure 1 ). The gas inlet 44 is adapted to be coupled to a gas supply using a coupling member (e.g. a hose, not shown) for providing gas to the chamber 14 during use of the apparatus 10.

[0044] The lower tank head 18 also generally includes an outlet fitting 46. The outlet fitting 46 is configured to allow extraction of the gas and liquid mixture (e.g. using a hose, not shown) that is generated by the apparatus 10 and which tends to collect in the lower tank head 18 during use.

[0045] The apparatus 10 may also include a pH sensor 48, which may be coupled to the lower tank head 18 using a sensor fitting 50. The pH sensor 48 has a sensor tip 52 that extends into the chamber 14 and may be configured to measure the pH levels of the gas-liquid mixture that collects in the lower tank head 18.

[0046] Based on the pH levels observed by the pH sensor 48, the properties of the gas-liquid mixture can be monitored and decisions may be made about the operation of the apparatus 10, such as whether additional quantities of liquid or gas (or both) should be added to the apparatus 10, and/or whether the gas-liquid mixture is ready for extraction via the outlet fitting 46.

[0047] In some examples, the tank 12 also includes a float switch 54 mounted to the lower tank head 18 via a switch fitting 56. The float switch 54 may be configured to monitor the level of the gas-liquid mixture within the lower tank head 18. Based on the height of the mixture, the float switch 54 may be used to trigger extraction 46 of the mixture, control the rate of liquid flowing in through the inlet spout 42, and/or take other actions. In particular, the float switch 54 can ensure that the level of mixed liquid in the chamber 14 remains below the surface of the disc 20.

[0048] In other embodiments, various other sensors may be provided for measuring the operating conditions within the tank 12.

[0049] The apparatus also generally includes a drive mechanism 60 adapted for rotating or spinning the disc 20 about an axis of rotation A. The drive mechanism 60 may generally be any suitable drive (e.g. a magnetic drive) and may include an inner rotor 62 configured to rotate and an outer rotor 64 that is mechanically coupled to an electric motor or other suitable source of powered rotation. For instance, in this example, the inner and outer rotors 62, 64 are magnetically coupled so that the inner rotor 62 rotates when the outer rotor 64 is caused to rotate.

[0050] The inner rotor 62 is generally coupled to a shaft 66 that extends upwardly into the chamber 14. The shaft 66 has an upper portion 66a that is coupled to the disc 20 so that as the inner rotor 62 rotates, the shaft 66 and disc 20 also rotate.

[0051] The shaft 66 may be received within a shaft housing 68 configured to support and stabilize the shaft 66 and disc 20 during rotation. One or more journal bearings 70 may be provided between the shaft 66 and housing 68 so as to inhibit wear during rotation. In some examples, the journal bearings 70 may be plastic, or any other suitable material. [0052] In some examples, a cap 72 may extend downwardly from the bottom of the lower tank head 18. The cap 72 may house elements of the drive mechanism 60 (e.g. the inner rotor 62 and a lower portion of 66b of the shaft 66) generally below the tank 12, which may facilitate the operation of the drive mechanism 60 (e.g. the magnetic coupling between the inner and outer rotors 62, 64).

[0053] As shown, the cap 72 may be coupled to a lower puck 78 provided in the lower tank head 18 using one or more fasteners 74, and may have a gasket 76 provided between the lower puck 78 and the barrier 72 to assist with inhibiting leaks.

[0054] In some examples, the inner rotor 62 may be coupled to a thrust bearing 80 (which may be plastic or any other suitable material).

[0055] The drive mechanism 60 may be used to rotate the disc 20 at elevated speeds selected according to the desired operating conditions of the apparatus 10. For example, the disc 20 may be rotated at speeds up to and including 3600 RPM. Alternatively, the disc 20 may be rotated at speeds of greater than 3600 RPM, for example up to 5000 RPM or more. Generally such higher speeds may be associated with liquid particle modes of operation.

[0056] In some embodiments, the disc 20 may be rotated a lower speeds, such as 1500 RPM or less, or more particularly, 1000 RPM or less, or between 200 and 500 RPM, and so on. Generally lower speeds may be associated with thin film mode of operation.

[0057] In some examples, the tank 12 may also include a safety release valve (not shown) so as to inhibit an overpressure situation from forming within the chamber 14, and which could otherwise damage the components therein and/or cause the tank 12 to crack or burst.

[0058] As shown, in this embodiment the disc 20 generally has a flat upper surface (as shown in Figure 1 ) and has a circular shape, with a disc diameter D (as shown in Figure 3). However, in other examples, the disc 20 may have other shapes (e.g. the surface of the disc 20 may be convex or concave, the disc 20 may not be circular, etc.).

[0059] In some examples, the disc 20 may be made of a metal (e.g. steel, aluminum, etc.). In other examples, this disc 20 may be made of another material that is suitable for rotation at elevated speeds, such as high- strength plastics or ceramics. In some embodiments, the disc 20 may have specific textures, coatings, or other features designed to assist with the formation of a thin film thereon.

[0060] During use of the apparatus 10, liquid (e.g. water, beer, other beverages, etc.) may be fed onto the disc 20 (normally to the inner region 20a but in other embodiments at other locations) using the inlet spout 42, and the drive mechanism 60 may be used to rotate the disc 20 about the axis of rotation A.

[0061] As shown, a lower end portion 42a of the inlet spout 42 may be positioned adjacent or directly above the upper surface of the disc 20. Accordingly, in some embodiments the liquid can be directed onto the disc 20 in a generally smooth manner (e.g. without violent impaction that could cause poly-disperse sizes of droplets to be formed).

[0062] The rotation of the disc 20 generally causes the liquid to move from the inner region 20a outwardly towards an outer region 20b of the disc 20. As the liquid moves outwardly, it tends to spread upon the surface of the disc 20, generally forming a thin film.

[0063] Operation of the apparatus 10 will now be described with reference to a liquid particle mode, wherein the angular velocity of the disc 20 and other operating parameters are selected so as to cause a fine dispersion of liquid particles to be ejected from the edges of the disc 20.

[0064] In some such embodiments once the liquid reaches the outer edge 21 of the disc 20, it may collect at the edge, and then eventually separate from the edge 21 as liquid particles or liquid droplets. Once separated, the liquid particles of liquid will fly outwardly through the surrounding atmosphere in the chamber 14 towards the chamber walls 34, 36. During this flight, the liquid particles will interact with gas fed into the chamber 14 using the gas inlet 44 (e.g. carbon dioxide). In some examples, the gas may be continuously fed into the chamber 14. In other examples, the gas may be intermittently fed into the chamber 4.

[0065] Generally, the liquid particles are sufficiently small that the gas will rapidly dissolve into them and approach equilibrium saturation during the flight time of the particles (e.g. between disengaging from the spinning disc 20 and contacting the walls 34, 36 of the chamber 14). In some examples, the flight time is less than 100 milliseconds. In yet other examples, the flight time is less than 50 milliseconds. To accomplish the required mass transfer within the brief flight times of the droplets, the droplets should be extremely small and be of exact or very similar droplet sizes, or at least be almost entirely and reliably below a critical droplet size, so as to closely approach equilibrium with the surrounding gas. For example, in some examples, the droplets should be less than 100 microns in diameter. In other examples, the droplets should be less than 60 microns in diameter.

[0066] Furthermore, the distance between the edge 21 of the spinning disc 20 and the walls 34, 26 of the chamber 14 should be selected to allow the droplets to closely approach saturation with the surrounding gas prior to being arrested against the walls 34, 36. Accordingly, the chamber 14 should have a chamber diameter C sufficiently larger than disc diameter D such that the droplets have an extended life within the atmosphere prior to their coalescence into larger droplets or against a surface of the chamber walls 34, 36.

[0067] Generally, the chamber diameter C will be selected such that the droplets will tend to come to rest within the atmosphere before contacting the chamber walls 34, 36. Thus, the particles will have an extended life within the gas prior to coalescence so as to obtain a desired equilibrium level. However, in some cases, the chamber diameter C may be sufficiently small so that the droplets tend to reach the walls 34, 36 before being arrested by the atmosphere in the chamber 14, thus coalescing on the walls 34, 36.

[0068] Once arrested within the atmosphere (or on the walls 34, 36), the gas-liquid droplets will tend to collect and/or grow and will eventually fall into the lower tank head 18, where they can be subsequently extracted via the outlet fitting 63. In this manner, the apparatus 10 can be used to provide for mass transfer of gases into liquids.

[0069] Generally, during liquid particle mode the following equation can be used to estimate the diameter of water droplets produced by the spinning disc 20:

d = 4/[Q(Dp/o) 1 2 ] (1 )

[0070] where d is the droplet diameter in centimeters, Ω is the rate of rotation of the disc 20 in revolutions per minute (RPM), D is the disc diameter in centimeters, p is the density of the liquid medium being dispersed as droplets, and σ is the surface tension of the liquid medium.

[0071] In some cases, where the liquid does not perfectly wet the spinning disc 20, this equation should be corrected by dividing the answer by cos(<t>), where Φ is the wetting contact angle. For example, water often does not have a wetting reaction with metal surfaces (e.g. a metal spinning disc 20). Accordingly, in some examples such surfaces may be chemically or physically modified (e.g. using a coating) to provide hydrophilic surfaces, where cos(O) is roughly equal to unity.

[0072] It has been found that the roughly monodisperse droplets produced by the spinning disc 20 travel a given fixed distance in the surrounding gaseous medium (based on the operating conditions of the apparatus 10) before their velocity declines to essentially the ambient drag velocity within the gas. The result is a cloud of droplets accumulating in a dense and stationary ring at a generally fixed distance from the spinning disc 20. This fixed distance generally follows the form:

X/d = P (2) [0073] where X is the distance the primary droplet travels from the spinning disc in centimeters before the droplet loses their kinetic energy and come roughly to rest, and P is a constant that may be determined by observation. For example, for water droplets released into air at ambient pressure, P is equal to 2540.

[0074] Substituting equation (1 ) into (2), and adding a term to account for the viscosity of a surrounding atmosphere in the chamber 14 (e.g. carbon dioxide) under pressure as compared with ambient air, the following equation may be obtained to solve for the distance X:

X = 10, 100 /[Ω(Ορ/σ) 1/2 ] * (n air / η 2 ) (3)

[0075] The ratio of viscosities for air (171 micro Poise) and carbon dioxide (139 micro Poise) is approximately 1.23, and this is roughly independent of the surrounding gas pressure. The surface tension of water is approximately 72 dynes/cm, and the density of water is 1.00 grams/cm 3 , all at a temperature of approximately 4°C.

[0076] In some embodiments, the maximum flow rate, Q max of liquid that can be fed onto the spinning disc 20 is limited by the volume that would "flood" the surface and inhibit the formation of small droplets. This maximum flow rate is roughly equal to:

Q max = jt 2 D 2 Qd = ( 4π 2 D 2 ) / (Dp/o) 1 2 (4)

[0077] EXAMPLE 1 : Calculated Droplet Size and Distance of

Droplet Projected From An Apparatus Operating as a Carbonator.

[0078] According to one example, the apparatus 10 was configured with the spinning disc 20 having a disc diameter D of 10 cm, and using an AC synchronous motor to drive the drive mechanism 60.

[0079] When operating such an apparatus 10 with the disc 20 rotating at 3600 RPM, a carbon dioxide atmosphere with an absolute pressure of 45 psi (roughly 3 atmospheres) within the chamber 14, and water as the liquid, droplets of 0.00298 cm (roughly 30 micron) can be produced. Under these conditions, droplets of this size tend to be thrown a distance of approximately 9.2 cm from the edge 21 of the disc 20 prior to being arrested by their friction within the surrounding gas.

[0080] Accordingly, for this example embodiment the chamber diameter C should be made larger than 28.4 cm to enhance the contact time between droplets or particles and the surrounding atmosphere in the chamber 14 and provide for improved dispersion of the carbon dioxide into the water. After coalescing, the gas-liquid mixture can be collected in the bottom tank head 18, and subsequently extracted.

[0081] Alternatively, the chamber diameter C may be selected to be less than 28.4 cm if it is desired that the liquid droplets impact the walls 34, 36 of the chamber 14 rather than become entrained within the surrounding atmosphere.

[0082] The roughly 30 micron droplets produced by the spinning disc 20 in this example will tend to achieve approximately 97% equilibrium with the surrounding carbon dioxide atmosphere in approximately 0.05 seconds after leaving the edge 21 of the disc 20. However, because of time spent by the liquid spreading upon the surface of the disc 20 (prior to separation from the edge 21 ), the actual equilibrium results are generally better than is predicted by the diffusion into droplets alone.

[0083] If the walls 34, 36 of the chamber 14 in this example are selected to be larger than the specified 28.4 cm, then the droplets produced by the spinning disc 20 will tend to accumulate within a dense cloud at this distance, and will have much greater residence time within the gas atmosphere of the chamber 14 prior to coalescing into larger droplets.

[0084] The maximum recommended flow rate (Q max , calculated using equation (4) above) for this particular example is approximately ten liters of liquid per minute. It can be seen by inspection of equation (4) that the maximum flow rate of the apparatus 10 can be improved by increasing the size of the disc 20, and not through an increase in the speed of rotation of the disc 20. The system can be operated above the Q max value, but generally only in cases where mass transfer is favored, such as in carbonation.

[0085] Operation of an apparatus will now be described with reference to a thin film mode, wherein the angular velocity of the disc and other operating parameters are selected so as to form a thin film of liquid on the disc and allow for thin film gasification of the liquid generally without substantially forming liquid particles that are ejected from the edge of the disc.

[0086] For example, illustrated in Figure 4 is another apparatus 310 for providing for the mass transfer of one or more gases into one or more liquids via thin film gasification. The apparatus 310 may be similar to apparatus 10 as described above, and where appropriate like elements have been given similar reference numerals incremented by 300.

[0087] For example, the apparatus 310 generally includes a tank 312 that defines a chamber 314 into which the gas is received. In some embodiments, the tank 312 may be a pressure vessel adapted to operate at elevated pressures (e.g. greater than atmospheric pressure, at 3 atmospheres or more, and so on).

[0088] The apparatus 310 also generally includes a disc 320 provided within the chamber 314. The disc 320 has at least one surface configured to receive the liquid thereon. Furthermore, the disc 320 is also adapted to be rotated at angular velocities selected to provide for mass transfer of the gas into the liquid via thin film gasification.

[0089] As shown, the apparatus 310 also includes an inlet spout 342 that extends generally downwardly into the chamber 314. The inlet spout 42 is adapted to provide liquid (normally to an inner region) of the disc 320 during use of the apparatus 310. The apparatus 310 may also include a gas inlet 344 for supplying gas to the chamber 314.

[0090] In some embodiments, the apparatus 310 may optionally include a capacitive element 315 (e.g. a flexible bladder) coupled to the chamber 314. The capacitive element 315 is adapted to help absorb excess gases during use. This may be helpful with certain gases (e.g. nitrogen) that may not compress as much as other gases (e.g. carbon dioxide) to avoid the formation of excess pressures within the chamber 314. In particular, as pressures within the chamber 314 increase during use of the apparatus 310, the capacitive element 315 may receive excess gas from the chamber 314 and serve to relieve some of the pressure in the chamber 314. In some embodiments, the capacitive element 315 may be coupled to the chamber 314 via a valve.

[0091] In other embodiments, the apparatus 310 may not include a capacitive element 315.

[0092] In some embodiments, the gas could include nitrogen. In some embodiments, the liquid could be beer or other beverages.

[0093] In some particular embodiments, the apparatus 310 may be used for effecting the mass transfer of nitrogen gas into beer. In particular, entraining nitrogen gas in beer may be desirable for certain beers since it tends to provide beer with a "creamy" taste. However, beer is normally resistant to absorbing nitrogen gas.

[0094] Investigations were first made to determine whether nitrogen could be entrained in beer by operating an apparatus (e.g. apparatus 10) in liquid particle mode, causing liquid particles of beer to separate from the edge of a disc at high angular speeds (e.g. around 5000 RPM) in an atmosphere of nitrogen gas. It was observed that this approach tended to produce some undesirable effects. In particular, liquid particle mode techniques tended to result in "foaming" of the beer, which is generally undesirable and which may inhibit the mass transfer of nitrogen into the beer. This foaming is believed to be due to the presence of carbon dioxide in the beer; as the beer was ejected as liquid particles, the carbon dioxide therein caused foaming.

[0095] Accordingly, further investigations were made with the apparatus 310 operating in a thin film mode. In particular, the disc 320 was rotated at lower speeds (e.g. less than 1500 RPM, or in some embodiments, less than 1000 RPM) and it was discovered that mass transfer of nitrogen into the beer could be effected via thin film mass transfer at certain lower speeds substantially without foaming. In particular, in some embodiments the apparatus 310 may be operated with the disc 320 at an angular velocity selected so as to form a thin film or "sheet" of beer on the disc 320 (indicated generally as TFL in Figure 4) and inhibit the beer from separates from the edge of the disc 320 as liquid particles.

[0096] This thin film or sheet tends to provide a large surface area of beer into which desired quantities nitrogen can be absorbed, at least partially overcoming the mass transfer resistance.

[0097] Furthermore, since the velocity of the disc 320 is selected so as to avoid the formation of liquid particles ejected from the edge thereof, this generally avoids or inhibits the foaming effects observed when rotating a disc with beer at higher velocities (e.g. in the liquid particle mode). Rather, during thin film operation of the apparatus 310, the beer (or other liquid) tends to fall off the edge of the disc 320 as a smooth "cascade" of liquid (indicated generally as CS), generally in a non-violent manner. In particular, the cascade CS of liquid may be of substantially laminar flow.

[0098] The benefits of operating an apparatus in a thin film mode as opposed to a liquid particle mode may depend on the particular characteristics of the liquid or gas (or both) being used. For instance, when using the apparatus 310 with carbon dioxide gas in the chamber 314, it may be possible to run the disc 320 at around 5000 RPM to provide for desired carbonation of certain liquids (e.g. water) via liquid particle separation from the edge of the disc 320.

[0099] However, when using nitrogen gas in the chamber 314 and beer as the liquid, rotating at such speeds tends to cause undesirable foaming of the beer. Accordingly, the disc 320 can be rotated at lower speeds (e.g. in a thin film mode) to avoid foaming of the beer while still providing for desired quantities of nitrogen mass transfer into the beer. [00100] For example, in some embodiments, nitrogen mass transfer into beer may be performed with the disc 320 rotating at angular velocities between about 300 and 400 RPM, or between 20 RPM and 1500 RPM. In other embodiments, higher or lower angular velocities may be appropriate depending on the operating characteristics of the apparatus 310 and other parameters, such as the liquid temperature, gas pressure, and so on.

[00101] It will be understood that the particular angular velocity selected for a particular disc may vary, and may depend on various characteristics such as the size of the disc. For example, in some embodiments a larger disc may be rotated at slower speeds (as compared to a smaller disc) while still providing for generally similar thin film formation, since the linear speeds of the liquid at the edge of the disc are a function of disc diameter as well as angular velocity.

[00102] In some embodiments, thin film gasification may be used to provide for nitrogen concentrations in beer (or other beverages) of between about 15 and 90 parts per million (ppm). In some particular embodiments, nitrogen concentrations in beer around 35 ppm may be desirable. Generally, increasing the nitrogen concentration tends to provide for a smoother texture for beer, and bolder beer may benefit from higher concentrations of nitrogen.

[00103] In some embodiments, after the thin film gasification of the nitrogen in the beer, some of the beer may still separate from the edge of the disc 320 to form liquid particles. In some such instances, this may allow for further absorption of nitrogen gas into the beer (but may cause some foaming which is generally undesirable).

[00104] In some embodiments, gases other than nitrogen may be dispersed within a liquid via thin film gasification.

[00105] Generally, the angular velocities of the disc 320 that are suitable for operating the apparatus 310 in a thin film mode may depend on various other parameters, such as the temperature of the liquid, the temperature of the gas, the pressure of the gas, and the properties of the disc 320 (e.g. the size and shape of the disc 320, the disc's 320 surface properties such as texture or coatings, and so on). In particular, selecting the angular velocity of the disc 320 may involve selecting a balance between running the disc 320 too quickly, which tends to cause foaming of the beer, and too slow, which may not provide for the desired concentrations of gas in the liquid.

[00106] For example, in some embodiments, the apparatus 310 may be operated at a temperature between about 30 degrees Fahrenheit and about 50 degrees Fahrenheit when gases are being dispersed into a liquid via thin film gasification. In particular embodiments, the apparatus 310 may be operated at a temperature of between 36 degrees Fahrenheit and 42 degrees Fahrenheit when dispersing nitrogen into beer.

[00107] In some embodiments, pressures within the chamber 314 may also vary depending on the characteristics of the liquid and gas, and the desired concentrations of gas in the liquid. For example, in some embodiments the pressure within the chamber 314 may be greater than atmospheric pressure when dispersing nitrogen into beer via thin film gasification. In some embodiments, the pressure in the chamber 314 may be greater than 3 atmospheres or more during thin film gasification.

[00108] In some embodiments, the apparatus 310 may be used to add nitrogen to beer downstream of where the beer is manufactured. For example, nitrogen could be added to beer at the point of sale (e.g. a restaurant or bar) using an apparatus 310 coupled to a beer supply. For example, a keg of beer may not include appropriate concentrations of nitrogen gas for providing a desired taste. However, the apparatus 310 may be used to provide the desired nitrogen concentrations, in some cases on demand (e.g. when the beer is being poured for a specific customer).

[00109] In some embodiments, the disc in the apparatus 310 may have other shapes.

[00110] For example, referring to Figure 5, in some embodiments the apparatus 310 may include a disc 322 having a convex upper surface, with the disc 322 curved downwardly from the inner region 322a towards the outer edge 322b. This shape may help the cascade CS of liquid maintain substantially laminar flow, as the edge 322b of the disc 322 may more closely align with the flow lines of the liquid as the liquid leaves the disc 322. In particular, this profile may help reduce foaming of beer as the beer leaves the edge of the disc 322.

[00111] In other embodiments, the disc may have a concave profile. For example, referring to Figure 6, the apparatus 310 may include a disc 324 having a concave upper surface, with the disc 324 curved upwardly from the inner region 324a towards an upwardly extending lip 324b.

[00112] The concave upper surface may help form a thinner film of liquid as the liquid moves from the inner region to the edge of the disc 324. For example, gravity may act against the centripetal forces acting on the liquid as the liquid travels outwardly towards and then up the side of the lip 324b, which may facilitate thinning the liquid at or at least near the top of the lip 324b.

[00113] In some embodiments, the concave disc 324 may be sized and shaped to help maintain laminar flow of the cascade CS as the liquid leaves the disc 324. For example, the lip 324b may include a flared portion 324c that extends outwardly from a top of the lip 324b. The flared portion 324c may help the cascade CS of liquid maintain substantially laminar flow. In particular, the flared portion 324c may extend at least partially downwards to more closely align with the flow lines of the liquid as the liquid leaves the disc 324.

[00114] Referring to Figure 7, in some embodiments the apparatus 310 may include a sphere 326 rotated about an axis of rotation A (and which might be closely aligned with a central axis of the sphere 326). The inlet spout 342 may provide liquid onto an upper portion 327a of the sphere 326 (e.g. at some point on the upper hemisphere), and the liquid may spread out into a thin film liquid TFL as it flows down the sides of the sphere 326.

[00115] One benefit of the sphere 326 is that it may provide a larger surface area for the liquid to spread out as compared to the discs 320, 322, and 324, and as such, the sphere 326 may tend to provide for increased mass transfer via thin film gasification.

[00116] As shown, the liquid generally separates from the sphere 326 at one or more separation points 326b and may form a cascade CS. In particular, the separation points 326b may be located on a lower portion 327b of the sphere 326 (e.g. the lower hemisphere). The location of the separation points 326b may vary during operation and may depend on a number of factors, such as surface tension between the liquid and the sphere 326, the speed of rotation of the sphere 326, and so on.

[00117] Referring to Figure 8, in some embodiments, the apparatus 310 may include a spherical object 328 which is similar to the sphere 326 but which has a flanged lower portion 329b that extends outward to a tapered edge 328b. The spherical object 328 may also have an inwardly extending curved region 328a between the upper and lower portions 329a and 329b.

[00118] Similar to the convex disc 322 of Figure 5, the shape of the flanged lower portion 328a may help the cascade CS of liquid maintain substantially laminar flow. For example, the shape of the flanged lower portion 329a may align with the flow lines of the liquid as the liquid leaves the spherical object 328. This might reduce foaming when the liquid is beer for example.

[00119] Providing the tapered edge 328b might also reduce foaming of beer, fcr example, by providing a defined separation point or edge at which the liquid can separate from the spherical object 328 in a continuous or substantially continuous cascade CS of liquid. In contrast, the separation points 326b of the sphere 326 in Figure 7 are generally not defined and may in fact vary such that separation of the liquid from the sphere 326 is unstable. For instance, liquid on the sphere 326 may coalesce into liquid particles that drip from the sphere 326, or the liquid might adopt other flow characteristics that might increase the chance of foaming. [00120] Referring to Figure 9, in some embodiments, the apparatus 310 may include a rotating egg-shaped object 330.

[00121] The egg-shaped object 330 is like the spherical object 328 shown in Figure 8 but tends to be more elongated. The egg-shaped object 330 may also include a flanged lower portion 331 b that extends radially outward to a tapered edge 330b. The egg-shaped object 330 may also have an inwardly extending curved region 330a between the upper and lower portions 331a and 331 b of the egg-shaped object 330. In other embodiments, the flanged lower portion 331 b and the curved region 330a may be omitted.

[00 22] The apparatus 310 with the egg-shaped object 330 may function in a generally similar way as with the spherical object 328. One difference is that the curvature of the egg-shaped object 330 may be more gradual at some locations and more pronounced and other locations, which might facilitate the liquid in spreading out into a thin film on the surface of the egg-shaped object 3330, and might thereby further facilitate mass transfer via thin film gasification.

[00123] Referring to Figure 10, in some embodiments the apparatus 310 may include a rotating torpedo-shaped object 332. The torpedo-shaped object 332 is similar in many respects to the egg-shaped object 330 of Figure 9, but tends to be more vertically elongated. One further difference is that the torpedo-shaped object 332 has straight sides between the upper and lower portions 333a and 333b (as opposed to the inwardly extending curved region 330a of the egg-shaped object 330 for example).

[00 24] Referring to Figure 1 , in some embodiments the apparatus 310 may include a rotating cone 334. As shown in Figure 1 1 , the cone 334 may have a lower portion 335b that is located within the pool P of the gas-liquid mixture located at the bottom of the chamber 314. Providing the lower portion 335b within the pool P may facilitate the transition from the thin film liquid TFL on the surface of the cone 334 to the pool P and may help reduce foaming that might be associated with the formation of a liquid cascade. [00125] In other embodiments, the lower portion 335b may be above the pool P, particularly when the apparatus 310 is starting up for example.

[00126] Referring now to Figure 12, in some embodiments the apparatus 310 may include a rotating umbrella-shaped object 336. The umbrella-shaped object 336 might function in a similar manner as the torpedo-shaped object 332. One difference is that the umbrella-shaped object 336 might provide a wider surface area for the liquid to spread out on in comparison to the torpedo-shaped object 332 for example.

[00127] Referring now to Figure 13, in some embodiments the apparatus 310 may include a rotating funnel 338 or cone. In such embodiments, the inlet spout 342 might be located offset from the axis of rotation A (which may also correspond to the central axis of the funnel 338). Accordingly, the liquid may be added through the inlet spout 342 to an outer edge 338a of the funnel and then form a thin film as the liquid flows downward to one or more exit ports 338b.

[00128] One difference between the rotating funnel 338 and other embodiments described previously is that centrifugal forces tend to push the liquid against the surface of the funnel (opposed to pulling the liquid along the surfaces). This may help spread the liquid out into a thinner film, and may improve thin film gasification.

[00129] As shown, the funnel 338 has a slope angle φ as defined with respect to a horizontal plane. The slope angle φ may be selected so as to obtain a desired thickness of the thin film liquid TFL. For example, a smaller slope angle φ (e.g. providing a shallower funnel) may provide for a thicker liquid film as the liquid may tend to move more slowly along the inner surface of the funnel 338 towards the exit ports 338b. Alternatively, selecting a larger slope angle φ (e.g. providing a steeper funnel) may tend to provide for a thinner liquid film as the liquid moves more quickly along the surface of the funnel 338 towards the exit ports 338b. [00130] In some embodiments, as shown in Figure 13, more than a single funnel may be used. For example, in some embodiments one or more secondary funnels (e.g. funnels 338c and 338d) may be nested or otherwise positioned within the funnel 388. Liquid may also be provided onto the secondary funnels 338c, 338d so as to effect thin film gasification thereof.

[001311 In some embodiments, the secondary funnels 338c, 338d may be smaller than the funnel 338.

[00132] It will be appreciated that the various embodiments as generally described herein may have a surface with a lower portion located within the pool P which may help facilitate a smooth transition form the surface to the pool P.

[00133] In some embodiments, the chamber 314 may have various shapes and sizes, which may be selected to encourage thin film gasification depending on the specific shape of the rotating surface being used.

[00134] Turning now to Figure 14, illustrated therein is an apparatus 410 for mass transfer of a gas into a liquid according to yet another embodiment. In this embodiment, the apparatus 410 includes a tank 412 that defines a chamber 414 into which the gas and liquid may be received for effecting thin film gasification therebetween.

[00135] Generally, the apparatus 410 includes at least one surface S that is fixed within the chamber 414 (for example on a wall 421 of the tank 412). The surface S is adapted to receive liquid (e.g. beer) thereon and is generally sized and shaped so that the liquid will adopt a thin film thereon, thus effecting thin film mass transfer of the gas into the liquid.

[00136] In some embodiments, as shown in Figure 14, the surface S may be an inverted conical surface (e.g. a funnel shape), as defined by the interior wall 421 of the chamber 414 that tapers from the top to bottom of the chamber 414.

[00137] The liquid may be supplied onto the surface S at or near the top of the chamber 414 with a input velocity selected so that the liquid moves relative to the fixed surface S and forms a thin film liquid (TFL) thereon. In particular, as the liquid is provided onto the surface S, it will tend to swirl around the surface S and form a "vortex" as gravity pulls the liquid downwards towards a bottom portion 418 of the tank 412 (where the liquid may collect in a pool P).

[00138] As shown, the apparatus 410 also includes an inlet spout 442 for providing the liquid onto the surface S. As shown, the inlet spout 442 may be located on or generally adjacent the inverted conical surface S and supplies the liquid onto the surface S with at least a partially horizontal component so as to induce a swirling motion.

[00139] In some embodiments, the inlet spout 442 may also provide the liquid with a slight downward velocity, which may help further thin the liquid film as will be described below. In other embodiments, the liquid may be supplied along a substantially horizontal direction, or with an upward velocity component.

[00140] In some embodiments, a pump 443a may be used to supply the liquid to the inlet spout 442 from a tank or another storage container 443b via piping 443c or another fluid conduit.

[00141] The apparatus 410 may also include a gas inlet 444 for providing gas (e.g. nitrogen) to the chamber 414. As shown, the gas inlet 444 may be located on a top portion 416 of the tank 412 and may be adapted to be coupled to a gas supply.

[00142] The bottom portion 418 of the tank 412 may define a reservoir for collecting the pool P of gas and liquid mixture therein. For example, in some embodiments, the bottom portion 418 may have a spherical or "lobed" shape. The apparatus 410 may also include an outlet 446 for extracting the gas and liquid mixture that collects in the bottom portion 418 of the tank 414.

[00143] In some embodiments, the tank 412 may have a neck 419 between the bottom portion 418 and the inverted conical surface S. [001441 In some embodiments, the apparatus 410 may be configured so that the surface of the pool P of liquid tends to be located above the neck 419. This may help provide a smooth transition of liquid from the conical surface S to the pool P, which may reduce splashing or other effects that could increase the likelihood of foaming (e.g. where the liquid is beer).

[00145] In some embodiments, the thickness of the thin film liquid TFL may vary along the surface S. For example, as shown in Figure 14, in some embodiments the thin film liquid TFL may tend to be thinner at or near the top of the surface S and thicker at or near the bottom of the surface S.

[00146] Generally, the thickness of the thin film liquid TFL along the surface S may depend on a number of factors, such as the size and shape of the surface S, the input velocity of the liquid from the inlet spout 442, the surface tension between the liquid and the surface S (which may depend on the wetting properties of the surface S), and so on.

[00147] As shown in Figure 14, the conical surface S may be defined as having a radius R at the height of the inlet spout 442. The conical surface S may also be defined as having a slope angle Θ generally with respect to a horizontal plane. The radius R and the slope angle Θ may be selected (in combination with the input velocity of the liquid) to provide the thin film liquid TFL with a desired thickness profile as the liquid flows along the surface S from the inlet spout 442 to the bottom portion 418. For example, selecting a larger radius R may provide a greater surface area for the liquid to spread out onto and thus may tend to form a thinner film, while selecting a smaller radius R may tend to provide a thicker film.

[00148] On the other hand, selecting a smaller slope angle Θ (e.g. providing a shallower funnel) may provide for a thicker liquid film as the liquid may tend to move more slowly along the surface S towards the bottom portion 418. Alternatively, selecting a larger slope angle Θ (e.g. providing a steeper funnel) may tend to provide for a thinner liquid film. [00149] In some embodiments, the slope angle Θ may be between 5 degrees and 85 degrees. In some embodiments, the slope angle Θ may be between 15 degrees and 75 degrees. In other embodiments, the slope angle Θ may be between 30 degrees and 60 degrees. In some particular embodiments, the slope angle Θ may be about 45 degrees.

[00150] The configuration of the inlet spout 442 and the input velocity of the liquid may also affect the thickness of the thin film TFL. For example, providing a higher input velocity (e.g. by increasing the output pressure of the pump 443a) may generate more swirling of the liquid, which may tend to reduce the thickness of the liquid film TFL. Furthermore, configuring the inlet spout 442 to provide a downward velocity component might direct the liquid toward the bottom portion 418 of the chamber 414 more quickly, which may tend to reduce the thickness of the liquid film (although generally the input velocity should be selected to provide laminar flow of the liquid and avoid turbulent flow).

[00151] Reducing the surface tension between the liquid and the surface S might also help reduce the thickness of the thin film liquid TFL. Accordingly, in some embodiments, the surface S may be selected to reduce surface tension with the liquid (i.e. increase wetability), for example, by selecting a hydrophilic surface when the liquid is water-based (e.g. such as beer).

[00152] As shown in Figure 14, the position of the inlet spout 442 within the tank 412 may be selected to provide a height H between the neck 419 and the inlet spout 442. The height H may be selected so as to assist in providing the desired thickness of the thin film liquid TFL and to allow for sufficient time for the gas in the chamber 414 to diffuse into the thin film liquid TFL.

[00153] In some embodiments, the inlet spout 442 may have other locations within the chamber 414. For example, the inlet spout 442 may extend downward from a ceiling or top portion of the chamber 414. [00154] As shown in Figure 14, the surface S may be formed integrally as a portion of the interior sidewall of the tank 412. In other embodiments, the surface S may be provided on a separate component from the tank 412. For example, the surface S may be elevated above the sidewall of the tank 412.

[00155] Furthermore, while the surface S shown in Figure 14 has an inverted conical or funnel shape, the surface S may have other shapes. For example, in some embodiments the surface S may have a parabolic or curved shape. In some embodiments, the surface S may have one or more helical or spiral features, which may assist the liquid in adopting a desired swirling or vortex motion on the surface S.

[00156] The apparatus 410 may have some benefits in comparison to other apparatus that use rotating discs, such as the apparatus 10 and 310 as described above. For example, the apparatus 410 generally has no moving mechanical parts, which can reduce the overall complexity of the apparatus 410 and cost of operating the apparatus 410.

[00157] The use of the apparatus 410 may also reduce incidences of foaming when dispersing nitrogen (or other gases) in beer (or other liquids). More particularly, during use of the apparatus 410, the liquid may tend to remain attached to the inverted conical surface S as the liquid swirls downward toward the pool P generally without violently separating from the surface S. Since the liquid tends to remain attached to the surface S there might be fewer liquid particles formed, which might otherwise create foam. Furthermore, there might be less splashing, for example, as no cascade CS of liquid may form within the apparatus 410.

[00158] Turning now to Figure 15, in some embodiments more than one surface may be provided in the apparatus 410. For example, in some embodiments secondary walls 421a, 421 b may define other surfaces S2, S3 in addition to the first surface S defined by the wall 421 of the tank 412. These secondary surfaces S2, S3 may also receive fluid thereon (e.g. via inlet spouts 442a, 442b) so that the fluid can adopt a thin film and be gasified by the gas in the tank 412, [00159] Providing secondary surfaces S2, S3 may increase the output rate of the apparatus 410.

[00160] Turning now to Figure 16, illustrated therein is an apparatus 510 according to another embodiment for effecting the mass transfer of gas (e.g. nitrogen) into a liquid (e.g. beer). As shown, the apparatus 510 includes a tank 5 2 having a liquid inlet 514 at an upper end 512a of the tank 512, and a gas inlet 516 at a lower end 512b of the tank 512.

[00161] Provided within the tank 512 is a packing material 518. The packing material 518 may include random or pseudo-random arrangements of any material that will tend to cause an obstruction or otherwise slow the movement of the liquid to increase the chances for a thin film to occur within the tank 512. For example the packing material 518 may include loose packing materials, structured packing materials, metal or plastic rings (e.g. Paul rings), wired mesh, carbon or graphite Raschig rings, or other shapes or surfaces, etc.

[00162] The packing material 518 may be supported by a mechanical separator 520. The mechanical separator 520 is generally permeable such that gas and liquid can pass therethough but is operable to inhibit the packing material 518 from falling to the bottom of the tank 512.

[00163] During use, a liquid (e.g. beer) may be uniformly dispersed into the tank 512 using the liquid inlet 514 (e.g. in a generally uniform pattern, such as via spraying) while gas (e.g. nitrogen) may be added via the gas inlet 516. The gas will tend to flow upwards through the mechanical separator 520 while the liquid will tend to fall down from the liquid inlet 514. As such, the gas and liquid will tend to meet in the tank 512 and contact each other in the packing material 518.

[00164] Generally, the packing material 518 may provide a relatively large surface area for the liquid to be adsorbed upon and so that the gas can be entrained into the liquid. Furthermore, the packing material 518 may tend to slow the movement of the liquid so that it can be exposed to the gas for a W

- 31 - sufficient time to achieve the desired levels of gas entrainment via thin film gasification.

[00165] In some embodiments, gasified liquid can be removed from the tank 512 via an outlet 522, which might include a valve. In some embodiments, a float located in the gasified liquid may be used to control the operation of one or more valves in the outlet 522, the gas inlet 516 and the liquid inlet 514 to achieve desired operating parameters in the tank 512.

[00166] In view of the embodiments described above, it has been recognized that thin film gasification can be performed using an apparatus configured to generate a thin film in the presence of a gas. More particularly, a thin film can be generated using an apparatus comprising a chamber (e.g. the chamber 14, 314, or 414) having a gas therein, and a surface within the chamber (e.g. the upper surface of the rotating discs 20, 320, 322, or 324, or another surface such as the inverted conical surface of Figure 14). The surface is generally adapted to receive a liquid thereon and so that the liquid adopts a thin film profile.

[00167] In some embodiments, the thin film may be produced by rotating or otherwise moving the surface (e.g. by rotating the discs 20, 320, 322, or 324 so that the liquid moves over the disc with an outward radial velocity).

[00168] In other embodiments, the thin film may be produced by supplying the liquid with an initial velocity relative to a fixed or stationary surface so that there is a relative movement between the fixed surface and the liquid (e.g. by supplying liquid on inverted conical surface such that the liquid swirls around the surface). Generally, the relative velocity may be selected so that the liquid adopts a thin film condition on the surface.

[00169] While the above description provides examples of one or more methods and/or apparatuses, it will be appreciated that other methods and/or apparatuses may be within the scope of the present description as interpreted by one of skill in the art.