Abstract:
A method and an installation for the sterile filling of containers with a product, wherein the method includes, after the container has been filled with the product and before it is sealed, introducing liquid nitrogen is introduced into the container. The container is then sealed. The installation of the dosing system for the liquid nitrogen is sterilized at least once with hydrogen peroxide. The containers are conveyed along at least one linear conveyance path from a filling station to the area of the dosing system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method for the sterile filling of containers with a product. The method includes after filling the container with the product and before sealing it, introducing liquid nitrogen into the container, and then sealing the container. 
         [0003]    The present invention also relates to an installation for the sterile filling of containers with a product, wherein the installation has at least one conveyance system for the containers, at least one filling station, at least one dosing system for liquid nitrogen, and at least one sealing station for sealing the containers. 
         [0004]    2. Description of the Related Art 
         [0005]    Previously known installations of this type have a rotating filling wheel that feeds the containers to be filled to the individual processing stations. Liquid nitrogen introduced onto the product filling vaporizes, and the vaporized nitrogen displaces air and/or oxygen possibly present above the filled product. 
         [0006]    Sterile filling of the container with the product requires not only that the product itself and the container to be filled are sufficiently sterile, but also that the liquid nitrogen and the conveying lines and switching elements for the liquid nitrogen are sufficiently sterile. In prior-art systems, it is possible, for example, to sterilize the entire filling plant with superheated steam before a production run. The superheated steam is carried through all of the connecting lines that are used. 
         [0007]    The previously known methods and installations are still unable to meet all of the requirements with respect to a high degree of sterility and at the same time simple operation of the filling plant. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, the object of the invention is to improve a method of the aforementioned type in such a way that improved conditions of sterility are realized. 
         [0009]    In accordance with the invention, this objective is achieved in such a way that a dosing system for the liquid nitrogen is sterilized at least once with hydrogen peroxide and that the containers are conveyed along at least one linear conveyance path from a filling station to the area of the dosing system. 
         [0010]    A further object of the present invention is to provide an installation of the aforementioned type in a way that is conducive to achieving a high degree of sterility. 
         [0011]    In accordance with the invention, this object is achieved in that the dosing system is coupled with a sterilization unit, which is connected with a supply system for supplying hydrogen peroxide, and that the conveyance system is a linear conveyor for at least part of its length. 
         [0012]    The sterilization of the liquid nitrogen dosing system with hydrogen peroxide makes it possible to carry out a dry sterilization and thus to avoid the formation of condensate. In particular, the use of hydrogen peroxide as a sterilizing agent makes it possible to dispense with a sealing element in the area of the filling head. Where the design of the installation is concerned, compared to sterilization with superheated steam, devices for removing condensate and steam are eliminated. 
         [0013]    A preferred use is in cold aseptic filling. Designing the conveyance line as a linear conveyance path along at least part of its length allows a sufficiently long period of time for the vaporization of the liquid nitrogen to occur. In rotary systems, the period of time from the dosing of the liquid nitrogen to pressure-tight sealing of the container is usually well below 0.5 seconds. The use of a linear conveyance line allows corresponding vaporization times on the order of 12 seconds and is thus conducive to almost complete displacement of foreign gases from the headspace of the container above the product filling by the nitrogen. 
         [0014]    A typical degree of sterility with respect to spore-forming microorganisms is log  5  and preferably log  6 . With respect to Clostridium botulinum, a sterility of log  12  is preferably achieved. 
         [0015]    In a typical embodiment, the linear conveyance path is placed in the vicinity of a linear filler. 
         [0016]    To assist in the flushing of the headspace of the container, it has been found advantageous to carry out a pressure-tight sealing of the container at no less than five seconds after the dosing of the liquid nitrogen. 
         [0017]    The proportion of nitrogen in the headspace can be still further increased by carrying out a pressure-tight sealing of the container at no less than ten seconds after the liquid nitrogen has been dosed. 
         [0018]    It is conducive to a high degree of stability of the filled container if the container is sealed pressure-tight after a predetermined liquid nitrogen vaporization time has elapsed. 
         [0019]    In accordance with a variant of the operation of the filling machine, it is provided that the sterilization with hydrogen peroxide is carried out as part of a maintenance program. 
         [0020]    Moreover, it is contemplated that the sterilization with hydrogen peroxide be carried out at predetermined intervals of time. 
         [0021]    It is conducive to a high degree of sterility during product filling if the sterilization with hydrogen peroxide is carried out before a production run. 
         [0022]    In a preferred variant of the method, the liquid nitrogen flushes the headspace of the filled container during its vaporization. 
         [0023]    It is conducive to well-defined flow out of the headspace of the container into the surrounding area if a closure is first placed loosely on the container after the liquid nitrogen has been dosed and is not joined pressure-tight with the container until after a predetermined vaporization time has elapsed. 
         [0024]    It is conducive to high production rates if the conveyance system has at least two conveyance paths that are parallel to each other. 
         [0025]    Sterilizability of the filling machine is assisted if the dosing system comprises at least one dosing valve operated with compressed gas. 
         [0026]    Performance of the sterilizing operations in a way that is well defined with respect to time is assisted if the sterilization unit has a sterilization valve for the controlled dosing of hydrogen peroxide. 
         [0027]    To make it possible to sterilize the dosing valve, it is proposed that the dosing valve be connected with the hydrogen peroxide supply via a connecting line and a shutoff valve. 
         [0028]    Systematic flow of the hydrogen peroxide towards the dosing valve is achieved by providing a supply line for the hydrogen peroxide downstream of the shutoff valve in the direction of flow of the nitrogen. 
         [0029]    Additional valves make it possible to realize systematic sterilization of all nitrogen-carrying pipelines and the dosing valve in the direction of flow of the nitrogen. 
         [0030]    Another sterilization possibility consists in providing a supply line for hydrogen peroxide in the direction of flow of the nitrogen in an initial section of a distributor line. 
         [0031]    A simple design is realized if a nitrogen nozzle connected to the dosing valve is designed open in the area of its expansion facing away from the dosing valve. 
         [0032]    High sterilization rates are achieved if a sterilization system for the nitrogen is located in the vicinity of the filling system. 
         [0033]    To produce sterile liquid nitrogen, it has been found to be advantageous to use a heat exchanger to liquefy the sterile nitrogen. 
         [0034]    In an advantageous arrangement of the nitrogen supply system, the dosing system is positioned downstream of the filling station and upstream of the sealing station with respect to the direction of conveyance of the containers. 
         [0035]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0036]    In the drawing: 
           [0037]      FIG. 1  is a schematic side view of a filling machine; 
           [0038]      FIG. 2  is a greatly simplified diagram that illustrates the filling of the containers and the dosing of the liquid nitrogen; and 
           [0039]      FIG. 3  is a schematic drawing of the components used for supplying the liquid nitrogen; 
           [0040]      FIG. 4  is an enlarged cross-sectional view of a nitrogen nozzle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]      FIG. 1  is a side view of a typical construction of a filling machine in the form of a linear filler. The filling machine has a bottle feed system  4  and a bottle sterilization unit  5 . A filling station  6  is installed downstream of the bottle sterilization unit  5  in the direction of conveyance of the bottles to be filled, and a sealing station  7  is installed downstream of the filling station  6  in the direction of conveyance of the bottles. The filled and sealed bottles are removed from the area of the filling machine by a bottle extraction system  8 . 
         [0042]    Furthermore, the filling machine is equipped with an exhaust system  1 , a valve manifold  2  and an operating unit  3 . The operating unit  3  can comprise a touchscreen and additional operating elements. 
         [0043]      FIG. 2  shows schematically how a filling operation is carried out with a direction of conveyance  10  of the bottles  9  from right to left. A first filling module  11  and a second filling module  12  of the filling station  6  are arranged in succession in the direction of bottle conveyance  10 . The bottles  9  are filled to the extent of about one third to two thirds in the first filling module  11 , and the filling of the bottles is completed in the second filling module  12 . A liquid nitrogen dosing system  13  is positioned downstream of the filling station  6 . The dosing system  13  is connected with a nitrogen supply system  14 . In the embodiment illustrated here, the sealing station  7  consists of a first sealing module  15  and a second sealing module  16 . In the first sealing module  15 , caps (not shown) are first placed loosely on the bottle  9 , and a pressure-tight seal is then produced in the second sealing module  16 . 
         [0044]    A conveyance system  17  for the bottles  9  is a linear conveyor. The conveyance system  17  can be, for example, a chain conveyor that is guided over guide wheels  18 ,  19 . 
         [0045]    In a preferred embodiment of the invention, a plurality of conveyance systems  17  run next to one another. This allows parallel arrangement of a plurality of handling elements in the area of the individual stations, so that the machine capacity can be multiplied according to the number of parallel conveyance lines. 
         [0046]    In the bottle sterilization unit  5 , sterilization is carried out with the use of hydrogen peroxide. The hydrogen peroxide is preferably mixed with hot air. The sterilization can be carried out in several successive sterilization units. After they have been sterilized and before they are filled, the bottles  9  are typically dried. This can be done with hot air. Here again, several drying units are typically arranged in succession in the direction of conveyance  10 . The hot air in each drying unit has a temperature of at least 100° C., so that sterility is guaranteed. 
         [0047]    In accordance with a customary process sequence, conveyance of the bottles  9  through the filling machine is timed. With each timed stroke, the bottles  9  are carried the same distance farther along the line. When two sterilization modules are used, the sterilization is thus carried out over the length of two timed strokes, and when four drying modules are used, the drying is carried out over the length of four timed strokes. Each bottle  9  is assigned to the first filling module  11  for one timed stroke and to the second filling module  12  for another timed stroke. 
         [0048]    The bottles  9  are preferably sealed with the use of caps that have an internal thread that engages an external thread on the mouth of the bottle  9 . The second sealing module  16  thus carries out a rotation of the cap relative to the bottle  9 . 
         [0049]      FIG. 3  shows a typical design of a nitrogen supply system  14 . An internal chamber  20  of a heat exchanger  21  is filled with liquid nitrogen, which is received from a nitrogen supply line  22 . After it leaves the heat exchanger  21 , it is fed to a surrounding environment, in which vaporization causes the nitrogen to cool. 
         [0050]    Inside the heat exchanger  21 , a line  24  is installed, through which sterile nitrogen is carried. This gaseous nitrogen is fed to the heat exchanger  21  and is subsequently removed from it in liquid form. The sterile gaseous nitrogen is thus liquefied by heat transfer as it passes through the line  24 . It is then fed to a distributor line  25 . A plurality of dosing valves  26  is connected to the distributor line  25  according to the number of parallel conveyance paths. These dosing valves  26  together form the dosing system  13 . The dosing valves  26  are preferably controlled by compressed gas and have a compressed gas connection  27  for this purpose. 
         [0051]    A sterilization valve, which is integrated in the nitrogen supply system upstream of the heat exchanger  21 , and various other valves make it possible for hydrogen peroxide to be systematically admitted into all of the pipelines that carry nitrogen and into the dosing valve. The hydrogen peroxide then flows through the nitrogen nozzles  31  and other components into the sterile zone of the machine and is exhausted. 
         [0052]      FIG. 4  shows an enlarged cross-sectional view of the nitrogen nozzle  31 , which extends through a wall  32  of the filling station  6 . Only a cover sleeve  33  that partly encloses the nitrogen nozzle  31  is located in the sterile zone  34 . All other components of the nitrogen supply system  14  are located outside the sterile zone  34 . 
         [0053]    The nitrogen nozzle  31  is preferably mounted only with a nut or a cover sleeve  33  and without the use of an adapter. 
         [0054]    The installation of the invention can be used, for example, for the filling of noncarbonated products. In addition to the displacement of oxygen in the headspace, the internal pressure produced by the nitrogen stabilizes the container. 
         [0055]    The nitrogen nozzle  31  is formed as an extension of a nozzle carrier  35 . The nozzle carrier  35  can be positioned with the use of an outer flange  36  in the vicinity of a connection  37 , which extends out from the wall  32  in the direction that faces away from the sterile zone  34 . This makes it possible in a simple way for the nozzle carrier  35  with the nitrogen nozzle  31  to be placed on the connection  37 , which is supported by the wall  32 . The nozzle carrier  35  is located outside of the sterile zone  34 . 
         [0056]    Most of the nozzle carrier  35  is located outside the sterile zone  34 , and only the nitrogen nozzle  31  itself extends within the cover sleeve  33  into the sterile zone  34 . In the area of its end that extends into the sterile zone  34 , the nozzle carrier  35  has an external thread  38 , onto which the cover sleeve  33  is screwed with an internal thread  39 . The threads ( 38 ,  39 ) are preferably as fine-pitch threads. The cover sleeve  33  can be sealed relative to the wall  32  by an O-ring  40 , which is pressed against the wall  32  by the cover sleeve  33 . The threads  38 ,  39  can be sealed relative to the sterile zone  34  with the use of an O-ring  41 , which is fixed between the nozzle carrier  35  and the cover sleeve  33 . 
         [0057]    An optimum sealing effect can be achieved if the threads  38 ,  39  extend over only a portion of the cover sleeve  33 , starting from the wall  32 . In this regard, the O-ring  41  is positioned near the ends of the threads  38 ,  39  facing away from the wall  32 . Possible critical surfaces or thread surfaces facing towards the aseptic zone are reliably prevented in this way. 
         [0058]    The screwing of the cover sleeve  33  onto the nozzle carrier  35  and the arrangement of the O-ring  40  between the cover sleeve  33  and the wall  32  result in the nitrogen unit being clamped relative to the wall  32 , and the resulting joints are flexible due to the elastic properties of the O-ring  40 . This clamping joint makes it possible to avoid temperature-induced stresses between the aseptic housing and the nitrogen unit. Even in the event of temperature-induced material expansions or contractions, fissures that could open into the sterile zone  34  are avoided. In particular, this assists with the arrangement of a plurality of nitrogen nozzles  31  alongside one another, which are assigned to transport paths that are parallel to one another. 
         [0059]    The joining technique explained above is also conducive to automatic foam cleaning with the use of a foam cleaning agent. The foam cleaning is typically carried out before the disinfection with the use of hydrogen peroxide.