Patent Publication Number: US-2006000518-A1

Title: Apparatus for inerting the headspace of a container

Description:
FIELD OF THE INVENTION  
      This invention relates to a method and apparatus for producing an inert atmosphere above a product stored in a container. The invention is particularly applicable in the food industry where contact with atmospheric oxygen may cause deterioration of a food product. However, the invention is not limited to this particular field of use.  
     BACKGROUND OF THE INVENTION  
      Many liquid products and particularly beverages are susceptible to damage or deterioration when mixed with or exposed to gaseous oxygen (usually oxygen present in air) for a period of time. Some O 2  may dissolve in the liquid and react with one or more of the chemical constituents causing undesirable changes such as flavour deterioration, aroma deterioration, colour change, formation of undesirable colour, hazing, browning and so on.  
      These changes are of particular concern to the beverage industries producing beer, wines, soft drinks, fruit juices, etc. The quantity of dissolved O 2  required to produce a slight but noticeable flavour deterioration in certain types of beer, wines and soft drinks can be extremely small, of the order of 1 ppm or less.  
      It is therefore of great importance to exclude or keep to an absolute minimum the presence of O 2  (air) in the system during the manufacture, storage, pumping, bottling or canning of many types of these beverages.  
      This is generally achieved by the use of a relatively inert and inexpensive gas such as nitrogen (N 2 ) or carbon dioxide (CO 2 ) or even Argon (Ar) to purge items of equipment, storage tanks, pipelines, canning and bottling lines free of air and to then blanket the liquid product to exclude contact with air during manufacture, storage and packaging.  
      The choice of whether to use N 2  or CO 2  or a mixture of these two gases can depend on various factors including the compatibility of the gas with the product, solubility, effect on flavour, taste, aroma or bouquet, storage life, etc. For example, N 2  may be the gas preferred for inerting types of wine, whilst CO 2  is usually preferred to inerting the gas space in vessels for carbonated beverages such as beer, soft drinks and various types of wine.  
      With respect to the use of CO 2  in the wine industry for purging equipment including storage tanks and for blanketing the wine during its manufacture, storage and bottling or canning, one practice is to use the CO 2  in gaseous form at around room temperature and at or above atmospheric pressure. The CO 2  gas may be obtained from transportable high pressure liquid CO 2  containers or by vapourising liquid CO 2  stored in on-site storage vessels operating at pressures ranging from about 650 kPa to about 2100 kPa.  
      Because the density of gaseous CO 2  at room temperature and at atmospheric pressure is about 50% greater than that of air under the same conditions, it has proved to be very suitable for displacing air from empty wine storage tanks prior to filling and for eliminating or greatly minimising the ingress of air during static storage and during the emptying of these tanks. Also, it is being used on a large scale to displace the air from empty wine bottles and cans prior to filling.  
      Australian patent 580732 describes methods and apparatus for producing an inert atmosphere above a stored product in a storage vessel. More particularly, Australian patent 580732 describes an apparatus and method for delivering a mixture of CO 2  snow and gaseous CO 2  into the head space of a recently filled bottle. The gaseous CO 2  which is heavier than the air in the head space displaces the air from the bottle. Additionally, the CO 2  gas resulting from the sublimation of the CO 2  snow in the relatively warm bottle displaces any remaining air and then flows gently out of the neck of the bottle, thus preventing air from re-entering the bottle. In this manner the air/oxygen content of the head space at the capping or corking station is significantly reduced when compared to bottles capped following the introduction of only gaseous CO 2  into the head space of the bottle.  
      Although the method and apparatus disclosed in Australian patent 580732 offers some advantage over prior art arrangements, the present invention seeks to further improve thereon.  
      The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of any of the claims.  
     SUMMARY OF THE INVENTION  
      According to a first aspect of the present invention there is provided a device for use with an apparatus for supplying an inert compound into the head space of a container, the device including a delivery path having an inlet for receiving a mixture of gaseous and solid phase inert compound, an outlet and a tortuous section located between said inlet and said outlet, said tortuous section being arranged to reduce the velocity of said solid phase inert compound as it flows there through.  
      Preferably, a vent means is formed in the tortuous section so that gaseous phase inert compound can vent from the tortuous section.  
      The tortuous section may adopt many different forms. However, in one preferred form, the tortuous section includes a curved section, for example a loop, through which the inert compound flows. The loop is preferably substantially circular in shape. In such an embodiment, the venting means may include a vent or slot formed in an inner side thereof.  
      The tortuous section is preferably shaped so that the gaseous phase inert compound is separated from the solid phase inert compound as it travels there through so that the gaseous phase inert compound can be more readily vented through the venting means.  
      Preferably, the inert compound delivered from said outlet is of a substantially solid phase.  
      According to a second aspect of the present invention there is provided an apparatus for supplying an inert compound into an head space of a container, said apparatus including a pathway having an inlet arranged to be connected to a supply of an inert compound in a liquid phase, means for converting said inert compound from a liquid phase to a mixture of solid and gaseous phase inert compound and an outlet arranged to supply inert compound to the head space of the container and wherein a device is provided substantially adjacent the outlet, said device including a delivery path having an inlet for receiving the mixture of solid and gaseous phase inert compound, an outlet and a tortuous section located between said inlet and said outlet, said tortuous section being arranged to reduce the velocity of said solid phase inert compound as it flows there through.  
      According to a third aspect of the present invention there is provided a method of storing a liquid in a container, said method including the steps of: 
          (i) partially filling a container with a liquid so that a head space filled with air is formed in an upper part of the container;     (ii) passing an amount of an inert compound through a converting means to convert the inert compound to a mixture of a solid and a gaseous state;     (iii) passing the mixture through a device including a delivery path having an inlet for receiving a mixture of gaseous and solid phase inert compound, an outlet and a tortuous section located between said inlet and said outlet, said tortuous section being arranged to reduce the velocity of said solid phase inert compound as it flows there through; and     (iv) delivering inert compound into the head space of the container.        

      Preferably, a closure is applied to the container after air and in particular after oxygen has been displaced from the head space. The air and/or oxygen is preferably displaced from the head space as a result of sublimation of the inert compound. Accordingly, the inert compound is denser than air and/or oxygen when the solid phase inert compound has returned to the gaseous phase after sublimation and is at a lower temperature than the ambient air.  
      The invention further includes a bottling line incorporating an apparatus according to the second aspect of the present invention.  
      As used throughout this specification, the phrase “inert compound” is used to define any substance that is in gaseous form at atmospheric pressure and at a temperature above 0° C. and which does not react to an unacceptable degree with the other components in the container.  
      The inert compound delivered is preferably denser than air, at least when the inert compound has returned to the gaseous phase after sublimation. The greater density of the inert compound may be an intrinsic property of the gas (i.e. at atmospheric pressure and temperature the deposited gas has a greater density than air). Alternatively, or in addition, the greater density of the inert compound may be a result of the low temperature thereof after sublimation (i.e. the gas has a greater density then air at the temperature at which it sublimes). The use of an inert compound denser than air enables the method and apparatus of the present invention to be used to create a layer of inert gas above the surface of the liquid in the container, said layer of gas serving to displace any air/oxygen from the head space of the container. This layer is preferably relatively stable and arranged to remain as an effective inerting atmosphere at the liquid surface for a considerable period of time.  
      The preferred inert compound for many possible applications of the invention is carbon dioxide (CO 2 ). Carbon dioxide is denser than air when it is in the gaseous phase at standard temperature and pressure. Thus, it will create a layer of an inert gas at the liquid surface due to the density difference. The carbon dioxide is preferably deposited in the head space of the container as solid phase carbon dioxide (CO 2  snow) at about −78.5°. However, it will be appreciated by those skilled in the art that at least a small amount of gaseous carbon dioxide will also be delivered into the head space of the container. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
       FIG. 1  is a schematic side view of an apparatus according to an embodiment of the invention; and  
       FIG. 2  is a schematic front view of a venting apparatus according to an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  shows a bottling line  10  for filling bottles  12  with a product such as wine. As shown in this Figure, each bottle  12  passes under a filling station  14  whereat the bottle  12  is charged with a liquid such as wine. Each filled bottle  12  then passes under an outlet nozzle  16  of an inerting apparatus  18 . The inerting apparatus  18  delivers an amount or charge of inerting compound into the head space of the filled bottle  12 . In this embodiment, the inerting apparatus  18  delivers an amount of solid phase CO 2  (hereinafter referred to as CO 2  snow) into the head space of the bottle  12 . A small amount of gaseous CO 2  may also be delivered into the head space of the bottle  12 . As the CO 2  snow settles and/or comes into contact with the wine in the bottle  12 , sublimation takes place causing displacement from the head space of the bottle  12  of air/oxygen. The resulting cold dense CO 2  gas then acts to prevent any substantial reintroduction of air/oxygen into the headspace of the bottle  12  prior to capping at a capping station (not shown). Preferably, sublimation of the CO 2  snow is almost completed by the time the cap/closure is applied to the bottle  12 .  
      The inerting apparatus  18  includes a fluid pathway  20  having an inlet  22  arranged to be connected to a supply of liquid CO 2  (not shown). The supply of liquid CO 2  may be contained in either a portable or static bulk vessel with an operating pressure typically of 1500 kPa. Fluid flows from the inlet  22  to a gas eliminator  24  which vents to atmosphere. The gas eliminator  24  feeds almost pure liquid CO 2  to a solenoid valve  26  and expansion orifice  28 . The CO 2  snow and gas exiting from the expansion orifice  28  then pass through a device  30 , hereafter referred to as a venting apparatus  30 . In the venting apparatus  30  as much of the CO 2  gas as possible is vented from the pathway  20  so that the inert compound delivered through the outlet nozzle  16  to the head space of the bottle  12  is mostly of a solid phase (i.e. CO 2  snow).  
      The proportion of CO 2  snow produced depends on the initial temperature of the liquid CO 2  entering the solenoid valve  26  and expansion orifice  28 . The colder the liquid CO 2 , the greater the proportion of CO 2  snow produced. For example, liquid CO 2  at a temperature of −16.8° C. produces about 46% of its weight as snow, whilst liquid CO 2  at a temperature of −46.3° C. produces about 56% of its weight as snow.  
      A heater  29 , for example a band heater, is provided on or adjacent to the solenoid valve  26  so as to enable control of the temperature of the valve  26 .  
      The heater  29  enables control of the temperature of the liquid CO 2  and thus, as mentioned above, the proportion of CO 2  snow produced.  
      The operation of the solenoid valve  26 , which determines the timing and quantity of the CO 2  snow delivered to the expansion orifice  28  and thus the bottle  12 , is controlled by a sensor  32  and a control system  33 . The control system  33  may include a PLC.  
      In the illustrated embodiment, the sensor  32  is located adjacent the inerting apparatus  18  and is in the form of an optical sensor. The sensor  32  activates the control system  33  allowing CO 2  snow to be delivered to the head space of the bottle  12 . In a preferred embodiment of the invention, the control system  33  enables four individual injection times and consequently four different CO 2  snow quantities. The preferred injection times are 0.04 seconds delivering 0.38 grams of snow, 0.06 seconds delivering 0.57 grams of snow, 0.08 delivering 0.76 grams of snow and 0.10 seconds delivering 0.95 grams of snow to the head space of the bottle  12 . The control system  33  can also be set for continuous operation. The control system  33  also controls the temperature of the heater  29 .  
      The venting apparatus  30  includes a stainless steel enclosure  34  that is vented to allow for the dispersion of gaseous CO 2 . Housed within the enclosure  34  is a portion of the pathway  20  that has a tortuous section  20   a . As best shown in  FIG. 2 , the tortuous section  20   a  takes the form of a circular shaped loop. In accordance with one preferred embodiment of the invention, the pathway  20  is made from stainless steel tube having a 10 mm inner diameter and the circular shaped loop has a diameter of 150 mm. Although the diameter of the loop of this embodiment is 150 mm, it is envisaged that a diameter of between 100 and 250 mm could be effective. The diameter of the loop is constrained by size limitations of the inerting apparatus  18  and also by the desired ratio of CO 2  snow/CO 2  gas at the outlet nozzle  16 . It is normally preferable to have the highest level of CO 2  snow possible, but it is recognised that a small quantity of CO 2  gas will normally be present at the outlet nozzle  16 .  
      As best depicted in  FIG. 2 , the curved section or loop  20   a  of the pathway  20  includes a venting means  20   b . The venting means  20   b  includes as a slot  20   b  cut or formed in an inner wall portion of the loop  20   a . The slot  20   b  is positioned and sized so that CO 2  gas can pass from the loop  20   a  through the vent  20   b  and then out to atmosphere. In accordance with one preferred embodiment of the invention wherein the loop has a diameter of 100 mm, the slot which forms the vent  20   b  extends over an arc of approximately 65°. The slot has a width of approximately 5.5 mm.  
      The loop  20   a  causes the CO 2  snow to follow the outer side of the loop radius, whilst the gas follows the inner side of the loop radius. Thus, the gaseous CO 2  is separated from the CO 2  snow and can more efficiently vent through the slot  20   b.    
      Most of the gaseous CO 2  flows out of the slot  20   b  as the CO 2  snow is pushed through the pathway  20  to the outlet nozzle  16 . The gaseous CO 2  flows out of the venting apparatus  30  via a vent  35 . The flow of CO 2  snow meanwhile continues around the loop  20   a  and arrives at the outlet nozzle  16  at a greatly reduced velocity. The velocity of the CO 2  snow is reduced because of the pressure drop at the slot  20   b  and also because of the diameter and shape of the loop  20   a  (i.e. the inclusion of the tortuous section  20   a ). Accordingly, the CO 2  snow can be delivered to the head space of the bottle  12  at a lower velocity. This is advantageous because it increases the efficiency of the CO 2  snow in displacing the air out of the head space of the bottle  12 .  
      The CO 2  snow is also delivered in a more “compact” form and thus the dosage to the head space of the bottle  12  can be more accurately controlled. The “compact” form of the CO 2  snow is important so as to prevent the snow injection angle into the bottle  12  from being too large. If the snow injection angle is too large, snow will be spilled over both sides of the neck of the bottle  12 . This is wasteful and more importantly prevents accurate dosing of the head space of the bottle  12 . Precise control of the amount of CO 2  snow delivered to the head space of the bottle  12  is desirable as it enables the amount of air/oxygen left in the head space after capping to be controlled. Thus, the level of gaseous or dissolved oxygen in the product in the bottle  12  can be maintained at a predetermined level.  
      It will be appreciated that the venting means  20   b  may not remove all of the gaseous CO 2  and that accordingly some gas will be flow out of the outlet  16 . However, the amount of gas will be greatly reduced as compared to the amount of gas in the mixture entering the venting apparatus  30 . Thus, the inclusion of the vent  20   b  increases the efficiency and accuracy of the CO 2  snow delivery to the head space of the bottle  12 .  
      The atmosphere within the enclosure  34  is heated by an air heater  36  that is controlled by the control system  33 . The enclosure atmosphere is heated to prevent blockages in the section of the pathway  20  within the enclosure  34  and to also prevent blockage of the vent  20   b.    
      Although not illustrated in the Figures, a reducing union may be located between the inlet  22  and the gas eliminator  24 . A relief valve may also be provided to relieve excess pressure within the pathway  20 .  
      The components of the inerting apparatus  18  are contained within an enclosure which is preferably made of stainless steel. The enclosure may be free standing or suitable for mounting on a wall surface, floor or stand.  
      The described embodiment of the invention is advantageous over prior art arrangements because it delivers the CO 2  snow to the outlet nozzle  16  at a reduced velocity. Additionally, because of the inclusion of the vent  20   b , a higher proportion of CO 2  snow is delivered to the outlet nozzle  16 , thereby making dosing of the head space of the bottle  12  more accurate. The inerting apparatus  18  is also suitable for use on high speed bottling lines.  
      Although the embodiment of the invention has been described in relation to filled containers, such as wine bottles, it will be appreciated that the invention is not restricted to such applications. The invention may be used in conjunction with storage vessels, cans, cartons etc for many different liquids. The invention may also be used in connection with empty containers, such as empty bottles or cans (i.e. can be used pre fill or post fill).  
      The described embodiment includes a tortuous section  20   a  which takes the form of a circular loop  20   a . However, it is recognised that the tortuous section  20   a  may adopt different forms. For example, it is envisaged that other shaped paths may result in a decrease in the velocity of the solid phase inert compound passing there through. It is also envisaged that a path with barriers or protrusions extending from the inner walls of the path may also serve to decrease the velocity of the solid phase inert compound.  
      In the present embodiment the vent  20   b  is described as a slot. However, it will be appreciated by those skilled in the art that the vent may adopt other forms. For example, the vent may take the form of a scoop (i.e. an angled and curved protuberance extending inside of the loop).  
      The embodiments have been described by way of example only and modifications within the spirit and scope of the invention are envisaged.