Patent Publication Number: US-6712342-B2

Title: Hollow fiber carbonation

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates generally to beverage dispensing, and in particular to methods and apparatus for carbonating beverages. 
     BACKGROUND OF THE INVENTION 
     In “post-mix” beverage dispensing, beverage syrups are mixed with plain or carbonated water to form finished beverages. Carbonation has proved to be one of the more difficult areas in post-mix dispensing. For example, carbonation systems are relatively expensive and can present significant maintenance and reliability issues. 
     Therefore, a need has arisen for a less expensive, high quality, and more reliable carbonation system. 
     SUMMARY OF THE INVENTION 
     In accordance with the teachings of the present invention, methods and apparatus for carbonating beverages are provided which substantially eliminate or reduce problems associated with prior art systems. 
     In a particular embodiment, a beverage dispenser is provided that includes a water supply (that may or may not comprise treated water), a CO 2  source, and a carbonator coupled to the water supply and the CO 2  source. The carbonator includes at least one hydrophobic hollow fiber proximate to which water is carbonated. Also included is a beverage syrup source, such that beverage syrup and carbonated water are dispensed to form finished drinks. In one particular embodiment, the hydrophobic hollow fiber comprises polypropylene. 
     In particular embodiments, CO 2  is supplied through one or more hollow fibers, and water flows across the outside of one or more of the hollow fibers. In an alternative embodiment, water is supplied through one or more of the hollow fibers. 
     It is advantageous to include a water treatment system, such that the water supply comprises treated water. It is particularly advantageous for the water treatment system to comprise a reverse osmosis water treatment system. In another embodiment, a reservoir is coupled to a reverse osmosis water treatment system and the carbonator. Plain water circuits may also be included with the various embodiments, such that both carbonated and non-carbonated beverages may be produced. 
     In one embodiment, a pre-carbonator is coupled to the carbonator to pre-carbonate water before further carbonation in the carbonator. The pre-carbonator may comprise a plurality of hollow fibers. 
     In particular embodiments, a reservoir may be coupled to the pre-carbonator, or to the carbonator (whether or not a pre-carbonator is used), to hold carbonated water. 
     Methods of dispensing beverages are provided that comprise supplying water, supplying CO 2 , carbonating the water with the CO 2  proximate to a plurality of hydrophobic hollow fibers, and dispensing carbonated water and beverage syrup to form finished drinks. The methods may also include treating the water, for example through reverse osmosis. Also, the methods may include pre-carbonating the water before carbonating it. 
     In particular methods, the treated water is stored before carbonating. Also, non-carbonated water may be dispensed, such that both carbonated and non-carbonated beverages may be produced. 
     Important technical advantages of the present invention include, among other advantages, reducing the cost of dispensers; increasing the efficiency and reliability of carbonation; and increasing beverage quality due to the use of treated water and better carbonation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made in the description to the following briefly described drawings, wherein like reference numerals refer to corresponding elements: 
     FIG. 1 illustrates an embodiment of a carbonation system with water treatment according to the teachings of the present invention; 
     FIG. 2 illustrates an embodiment of a pre-carbonation and finishing carbonation combination according to the teachings of the present invention; 
     FIG. 3 illustrates an embodiment of a hollow fiber carbonator according to the teachings of the present invention; 
     FIG. 4 illustrates another embodiment of a hollow fiber carbonator according to the teachings of the present invention; 
     FIG. 5 illustrates one embodiment of a pre-carbonation system according to the teachings of the present invention; 
     FIG. 6 illustrates one embodiment of a treated water source according to the teachings of the present invention; 
     FIG. 7 illustrates a particular embodiment of an integrated source of plain treated water for use with beverage dispensing; and 
     FIG. 8 illustrates another embodiment according to the teachings of the present invention in which a pre-carbonation circuit forms a reservoir for supply of treated water. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a dispensing system  10  that includes a hollow fiber carbonator  12  according to the teachings of the present invention. Hollow fiber carbonator  12 , which will be discussed in detail in connection with FIGS. 3 and 4, comprises one or more (preferably a bundle of) hollow fibers made of a hydrophobic material, such as polypropylene. Carbonation occurs by molecular gas transfer of CO 2  into the water. 
     Preferably, water is first treated in treatment system  14 . However, water may be taken directly from a water supply without treating it in a treatment system. Treatment system  14  can be any water treatment system, but preferably is a reverse osmosis (“R/O”) system. Thin film composite membranes (“TFC”) or thin film membranes (“TFM”) such as those made by the Dow Chemical Company under the trademark Filmtec, may be used as the R/O membrane. However, this is illustrative only, and any R/O device may be used. 
     Treated water is cooled in the dispenser  10  via chiller unit  16 . Chiller unit  16  may be a cold plate, through with the water is circulated and cooled because of contact of the cold plate with ice. As another example, the chilling unit  16  may be an ice/water bath created by a mechanical refrigeration unit, such as a vapor compression system. However, it should be understood that any cooling system may be used for chilling unit  16 , including, for example by way of illustration only and not by way of limitation, a system based on Stirling cycle refrigeration. 
     Chilled water is pumped via pump  18  to the hollow fiber carbonator  12 . The CO 2  supplied to the carbonator  12  is provided by CO 2  source  20  which may comprise a tank of CO 2  gas. Carbonated water, also called “soda,” is transmitted from the hollow fiber carbonator  12  to dispensing valves  22 . Dispensing valves  22 , in response to requests for beverages, open to transmit soda to nozzles  24 , which facilitate mixing of the water with beverage syrups and/or beverage flavors to form finished drinks. Instead of valves  22 , metering pumps or other devices for dispensing may be used, without departing from the intended scope of the present invention. 
     As shown in FIG. 1, a plain water circuit  26  is also provided, in which plain water is transmitted to the valves  22  around the carbonator  12 . In this way, the dispensing unit  10  allows for the dispensing of both carbonated beverages (with soda created through the carbonator  12  and transmitted to the valves  22 ) and plain water beverages, such as teas or juices (with plain water transmitted to the valves  22  via plain water circuit  26 ). 
     With the present invention, significant advances result from the use of hydrophobic hollow fiber carbonator  12 . In particular, efficient carbonation occurs at either low pressures or high pressures, because of the use of the hydrophobic material in the hollow fibers of carbonator  12 . The ability to carbonate at low pressures can significantly reduce the costs of the dispenser  10 . Furthermore, the combination of the hollow fiber carbonator  12  and the water treatment unit  14  provides for extremely efficient carbonation. In particular, the use of R/O treatment creates water that is very efficiently carbonated with the hollow fiber carbonator  12 . 
     FIG. 2 illustrates another embodiment of the present invention in which a pre-carbonation circuit  28  is provided. Pre-carbonation circuit  28  provides a supply of soda at a carbonation level lower than that required for some or all of the carbonated beverages to be dispensed. For example, if the most highly carbonated beverage includes five volumes of carbonation, then pre-carbonation circuit  28  may provide, as an example, a carbonation level of 2.5 volumes. However, it should be understood that this is an example only, and any carbonation level may be provided by pre-carbonation circuit  28 . In the embodiment of FIG. 2, carbonator  12  acts as a finishing carbonation unit, further carbonating water from the pre-carbonation circuit  28 . 
     As is shown in FIG. 2, the plain water circuit  26  runs parallel to the pre-carbonation circuit  28 , to provide plain water to the valves  22  for plain water finished beverages. Also shown in FIG. 2 is a lower-carbonation level circuit  30  that runs parallel to carbonator  12 . The lower-carbonation level circuit  30  provides soda to the valves  22  at a lower carbonation level than that provided by carbonator  12 . Thus, with the system shown in FIG. 2, valves  22  can receive plain water, or soda carbonated at at least two different levels, as provided by circuit  30  or through carbonator  12 . 
     Moreover, different levels of carbonation can be provided by mixing varying amounts of plain water with varying amounts of the soda provided by circuit  30  or carbonator  12  (whether or nor a pre-carbonation circuit is used). As another alternative, the carbonation level from carbonator  12  may be varied by adjusting the carbonation pressure provided by carbonation supply  20 . For example, a variable regulator may be provided to adjust the pressure depending on carbonation required. 
     FIG. 3 illustrates a particular embodiment of carbonator  12 . As shown in FIG. 3, the carbonator  12  preferably includes a bundle of individual hollow fibers  32 . CO 2  is supplied to these hollow fibers and runs through the hollow core of the fibers  32 . Water is supplied between the individual fibers, and can be supplied at any angle to the bundle, including tangentially to the bundle or parallel to the bundle. Carbonation occurs by molecular gas transfer through the hydrophobic fibers. 
     FIG. 4 illustrates an alternative configuration of carbonator  12 , in which the water is supplied through the cores of the hollow fibers  32 , and CO 2  is supplied between the individual fibers of the bundle. Thus, in FIG. 4, water flows through the fibers, with CO 2  supplied outside of the fibers. Again, carbonation occurs through molecular gas transfer. 
     Examples of hollow fiber membranes suitable for use with the present invention are provided by Celgard Inc., under the trademark Liqui-Cel®. While a bundle of hollow fibers is preferred, the carbonator may be configured as one or more fibers. For example, but not by way of limitation, one fiber may be used that is wound or laid out back and forth, or in a mesh or net pattern, to create sufficient surface area for the desired level of carbonation. 
     FIG. 5 illustrates a particular embodiment of pre-carbonation circuit  28 . As shown in FIG. 5, pre-carbonation circuit  28  includes a pump  34 , a hollow fiber carbonator  36  coupled to a CO 2  source  20 , and a reservoir  38  coupled between the output of carbonator  36  and the input of pump  34 . The reservoir  38  is preferably a flexible laminate bag capable of retaining carbonation. A relief valve  40  may be coupled to reservoir  38  to relieve pressures. In operation, water from the chiller unit  16  is provided to the pre-carbonation circuit  28 . Pump  34  pumps the cold water through the carbonator  36 , which may be configured, for example, as shown in FIG. 3 or FIG.  4 . The carbonated water output from the carbonator  36  is stored in the reservoir  38 . The pre-carbonation circuit  38  creates a reservoir of pre-carbonated water for dispensing. This reservoir is important in connection with the use of R/O systems, as it allows storage of treated water during lower use periods, thus allowing for smaller R/O systems than would be required if treated R/O water were supplied on demand. 
     The pre-carbonation circuit  28  operates continuously until the reservoir  38  is full, at which time the pump  34  is shut off. In a particular example, a proximity switch  42  may be used to control the pump  34 . When the bag of reservoir  38  is full, it will physically contact the proximity switch, thus resulting in a signal that turns off the pump  34 . It should be understood that other sensors may be used to regulate the volume of the reservoir, including floats. Also, other reservoirs, such as permanent tanks, may be used. However, it is preferable to use a bag and an external switch or sensor to minimize contamination of the water. With the pre-carbonation circuit  28  shown in FIG. 5, a reservoir of carbonated water is provided, thus allowing for high volume dispensing with a low volume R/O unit. Therefore, costs are greatly reduced over alternative configurations. 
     The output of the carbonator  36  and the reservoir  38  may be sent to valves  22  or finishing carbonator  12 , or may be sent there through a cooling coil located in proximity to the chilling unit  16 , so as to chill the water from the reservoir  38  before dispensing. Check valves  35  and  39  may be provided to prevent backflow (backflow prevention may be included in other embodiments, as well, if desired). 
     FIG. 6 illustrates a particular embodiment of water treatment system  14 . As shown in FIG. 6, water treatment system  14  may include a water treatment unit  44 , such as an R/O unit as discussed above, and a reservoir  46 . The reservoir  46  is preferably a bag with a volume regulation sensor, such as that discussed above in connection with FIG.  5 . With the configuration shown in FIG. 6, a reservoir of plain water is provided for supply to the beverage dispenser  10 . In a preferred embodiment, the water treatment system  14  is built in as part of the dispensing unit  10 ; however, all or part of the water treatment system  14  may be separate from the dispenser  10 . By using reservoir  46 , a relatively small treatment unit, and in particular a small R/O unit, may be used, thus lowering the costs from those that would be expended if an R/O unit were configured to supply water on demand. Also, systems other than or in addition to an R/O unit may be used, including, without limitation, pre-filter carbon filter systems. 
     In particular embodiments, the water treatment system may comprise some or all of the elements and advantages of those disclosed in pending U.S. patent application Ser. No. 09/912,868 (filed Jul. 25, 2001), Ser. No. 09/773,381 (filed Jan. 31, 2001, now U.S. Pat. No. 6,423,212), and Ser. No. 09/775,116 (filed Feb. 1, 2001), entitled “Self Cleaning Pre-Filter System.” “Microbial Resistant Water Purification and Collection System,” and “Constant Pressure Filtered Water Delivery System,” respectively, all of which are commonly owned by the assignee or inventor of the present application, and which are herein expressly incorporated by reference, in their entirety. 
     The reservoir  46  may be regulated by a sensor that senses when the reservoir is full, to turn off the water treatment unit  44 . The preferred embodiment of reservoir  46  is a flexible plastic laminate bag, with an external sensor for regulating volume. The use of a flexible bag reduces contamination issues and provides other advantages, such as lower costs and easy cleaning, since the flexible bag can be replaced periodically, if necessary. U.S. Pat. Nos. 5,256,279 and 5,927,099, which are herein incorporated by reference in their entirety, disclose particular combinations of water treatment systems with flexible bags that may be used, among others, as particular embodiments of a water treatment system in the present invention. However, any reservoir, such as a permanent tank, and internal or external sensors, may also be used. 
     FIG. 7 illustrates a more detailed example of a particular water supply system for beverage dispensing  10 . In the particular example of FIG. 7, the chilling unit is a vapor compression refrigeration unit that includes condenser  50  and evaporator  52 . A compressor  54  pumps refrigerant from the evaporator  52  to the condenser  50 . Water is provided to R/O system  56  from an external water supply, such as a municipal supply. In a particular embodiment, the inlet water is transmitted through a coil  58  located in close proximity to condenser  50 . This approach preheats the water to the R/O system  56 , improving the efficiency of the R/O unit, and also improving the efficiency of the refrigeration unit by assisting in condensation across condenser  50 . Similarly, the reject water from R/O unit  56  may be passed through coil  60  to assist in condensation across condenser  50 . However, it should be should be understood that these circuits  58  and  60  are exemplary only, and need not be included. While pre-heating the inlet water assists in R/O treatment efficiency, it then requires further cooling of the water by evaporator  52 . Thus, a balance should be made between the most efficient use of energy and water, depending on the demands of the application. In most cases, overall efficiency should be improved by using reject water from the R/O unit  56  to assist in condensation across condenser  50 . 
     Treated water from the R/O unit  56  is stored in reservoir  62 , which may be a reservoir such as that discussed above in connection with reservoir  46  of FIG. 6 (water may also flow back for back flushing of the unit  56 ). In a preferred embodiment, the reservoir  62  is located in proximity to evaporator  52 , to cool the water within the reservoir  62 . Water to be dispensed for carbonated or plain water drinks is drawn from the reservoir  62  through circuit  64  which is cooled by evaporator  52 . The system of FIG. 7 provides the advantages discussed above in connection with FIG. 6, in that a relatively small R/O unit may be used because of the storage reservoir  62 . Furthermore, by placing the reservoir  62  in close proximity to the evaporator  52 , relatively high quantities of cold water are available. 
     Although the refrigeration unit shown in FIG. 7 is a vapor compression system, a similar configuration can be used in connection with an ice-cooled cold plate. The evaporator  52  would represent a cold plate, and the reservoir  62  would be located in close proximity to the cold plate. With an ice-cooled cold plate, obviously the condenser and pump shown in FIG. 7 are not needed. 
     FIG. 8 illustrates another embodiment of the present invention in which a reservoir  70  is coupled to a carbonation circuit such as that shown in FIG.  5 . With the configuration of FIG. 8, the reservoir provides a source of soda. Reservoir  70  of FIG. 8 is located in close proximity to the evaporator  52 , and is coupled to a pump  72  and hollow fiber carbonator  74 , similar to the carbonation circuit discussed above in connection with FIG.  5 . 
     As shown in FIG. 8, plain treated water is sent through a cooling coil  76  in proximity to evaporator  52  (which may also represent a cold plate) and either bypasses or supplies the carbonation circuit. The bypass circuit leads to the valves for production of finished beverages. Also, the output of the reservoir  70  and carbonator  74  may be transmitted directly to the valves or to a finishing CO 2  carbonator, and may be sent there through a coiling cool that runs in proximity to evaporator  52  (or a cold plate). The volume of water in the reservoirs of both FIGS. 7 and 8 may by controlled, as discussed above, through use of an external proximity switch that shuts off flow to the reservoir when sufficiently full. Other control regimes may also be used. 
     Although not shown in the figures, an electronic control system is provided for controlling operation of the various embodiments discussed herein. The control system may include a microprocessor or microcontroller, and various input/output ports to effect the control. The control system interfaces with the sensors to control operation of the water treatment units, pumps, and any other electronically controlled elements (such as, without limitation, variable regulators). Furthermore, the control system interfaces with a customer interface for turning on valves to dispense the desired beverages, and for dispensing ice, if ice dispensing is included. 
     The particular descriptions provided are illustrative examples, and features and advantages of each example can be interchanged with, or added to the features and advantages in the other embodiments and examples herein. For example, the embodiments discussed in connection with pre-carbonation may be used alone without a need for a finishing carbonation stage—i.e., the pre-carbonator is the carbonator. 
     And, in general, although the present invention has been described in detail, it should be understood that various changes, alterations, substitutions, additions and modifications can be made without departing from the intended scope of the invention, as defined in the following claims.