Device and a method for maintaining a gas flow barrier between two interconnected volumes

Abstract

A method and a device for maintaining, in a filling machine, a gas flow barrier between two volumes of a channel, wherein the channel is used for transportation of packages in a length direction thereof, and the volumes comprise a first volume having a first degree of sterilization and a second volume having a second degree of sterilization, and wherein the first volume comprises a gas injection mechanism, the second volume comprises a gas evacuation mechanism, and the first and the second volume meet in an interface area extending in a length direction of the channel. The method comprises arranging, divergent jets flowing from the gas injection mechanism such that the divergent jets of gas cooperate in the interface region for the generation of a unidirectional flow in the direction from the first volume towards the second volume in the interface area, and thus forming a gas flow barrier.

Claims

1. A device for maintenance of a gas flow barrier between two volumes of a channel in a filling machine, the channel being configured for transportation of packages in a length direction of the channel, the device comprising: a first volume with a first degree of sterilization; a second volume with a second degree of sterilization that is lower than the first degree of sterilization; nozzles in an upper portion of the first volume; a gas evacuation opening in the second volume; the first volume and the second volume meeting in an interface area extending in a length direction of the channel; the channel including first and second side walls on opposite sides of the channel in a width direction of the channel, the width direction being orthogonal to the length direction of the channel; the nozzles configured to inject turbulent, divergent, jets of gas directed toward the interface area, such that the divergent jets of gas meet in the interface area to generate a unidirectional flow in a first direction from the first volume toward the second volume in the interface area, the unidirectional flow forming the gas flow barrier preventing a flow in a second direction from the second volume toward the first volume; and the nozzles including first and second nozzles spaced apart from one another in the width direction of the channel, the first nozzle being closer to the first side wall than the second nozzle, and the second nozzle being closer to the second side wall than the first nozzle, the first and second nozzles being arranged and configured such that the divergent jet injected from the first nozzle intersects the first side wall, and the divergent jet injected from the second nozzle intersects the second side wall.

2. The device of claim 1, wherein the first and second volumes meet in a portion of the channel having a reduced cross section in a direction perpendicular to the length direction of the channel.

3. The device of claim 1, wherein the second volume comprises carriers for conveying the packages by their closed end.

4. The device of claim 1, wherein the nozzles are located in an uppermost portion of the first volume, spaced from the interface area.

5. The device of claim 4, wherein the nozzles comprise circular openings in the uppermost portion of the first volume.

6. The device of claim 4, wherein the nozzles are arranged at a fixed relationship along two lines extending symmetrically along a central axis of the length direction of the channel.

7. A device for maintenance of a gas flow barrier between two volumes of a channel in a filling machine, the channel being configured for transportation of packages in a length direction of the channel, the device comprising: a first volume with a first degree of sterilization; a second volume with a second degree of sterilization that is lower than the first degree of sterilization; nozzles in an upper portion of the first volume; a gas evacuation opening in the second volume; the first volume and the second volume meeting in an interface area extending in a length direction of the channel; the channel including first and second side walls on opposite sides of the channel in a width direction of the channel, the width direction being orthogonal to the length direction of the channel; the nozzles being configured to inject turbulent, divergent, jets of gas directed toward the interface area, such that the divergent jets of gas meet in the interface area to generate a unidirectional flow in a first direction from the first volume toward the second volume in the interface area, the unidirectional flow forming the gas flow barrier preventing a flow in a second direction from the second volume toward the first volume; a first flow restrictor positioned on the first side wall at the interface area; a second flow restrictor positioned on the second side wall at the interface area; and the nozzles including first and second nozzles spaced apart from one another in the width direction of the channel, the first nozzle being closer to the first side wall than the second nozzle, and the second nozzle being closer to the second side wall than the first nozzle, the first and second nozzles being arranged and configured such that the divergent jet injected from the first nozzle intersects the first flow restrictor, and the divergent jet injected from the second nozzle intersects the second flow restrictor.

8. The device of claim 7, wherein the first and second volumes meet in a portion of the channel having a reduced cross section in a direction perpendicular to the package transportation direction.

9. The device of claim 7, wherein the second volume comprises carriers for conveying the packages by their closed end.

10. The device of claim 7, wherein the nozzles are located in an uppermost portion of the first volume, spaced from the interface area.

11. The device of claim 10, wherein the nozzles comprise circular openings in the uppermost portion of the first volume.

12. The device of claim 10, wherein the nozzles are arranged at a fixed relationship along two lines extending symmetrically along a central axis of the length direction of the channel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic perspective view, partly in cross section, of a prior art filling machine used for filling of Ready-to-Fill-packages.

(2) FIG. 2 is a schematic sectional view, orthogonal to a transportation direction, of a filling machine according to a first embodiment.

(3) FIG. 3 is a cross section similar to FIG. 2, of a filling machine according to a second embodiment of the present invention.

(4) FIG. 4 is a cross sectional side view of a filling machine operating in accordance with the inventive method.

(5) FIG. 5 is a flowchart showing the inventive method.

DETAILED DESCRIPTION

(6) FIG. 1 illustrates a prior art filling machine, as disclosed in the previously mentioned application WO2004/054883. The device 1 has a heating zone 2, a sterilization zone 3, and a venting zone 4 and connected thereto a filling zone 5. As may be seen in FIG. 1, the zones 2-5 are separated from each other by partitionings 6, 7 arranged between the zones. In each partitioning 6, 7 there is an opening 6a, 7a. Packages 8 are arranged in holders 9 on a conveyor belt 10 which passes through the zones 2-5. The packages 8 stand on their closed top end 11 with their open bottom end 12 directed upwards.

(7) In the heating zone 2 there is a nozzle arrangement (not shown) in a top portion thereof for introduction of hot, filtered air. In a bottom portion of the heating zone 2 there are outlets (not shown) for withdrawing the hot air.

(8) Similarly, there are nozzles (not shown) for introduction of gaseous hydrogen peroxide in a top portion of the sterilization zone 3. In a bottom portion of the sterilization zone there are outlets (not shown) for withdrawing hydrogen peroxide.

(9) The venting zone 4 also has nozzles (not shown) for introducing hot sterile air in a top portion. In a bottom portion of the venting zone 4 there are outlets (not shown) for withdrawing hot air.

(10) In a manner similar to the heating, sterilization and venting zones 2-4, the filling zone 5 has nozzles 26 for introducing sterile air in a top portion 27 of the filling zone.

(11) The filling machine also has a gas production unit for producing the gaseous hydrogen peroxide used for sterilization, as well as a catalyst unit for degrading hydrogen peroxide gas withdrawn from the sterilization zone.

(12) FIG. 2 illustrates a first embodiment of the invention, and represents a schematic cross section, orthogonal to the transportation direction of the packages, in the filling zone of the filling machine. The package 108 is carried by a carrier 114 attached to a transportation line 115. Two rows of gas injection means in the form of circular nozzles 116 are arranged in the top of the zone, and these inject sterile air downwards. The injected air from each nozzle 116 forms a diverging flow, as indicated by the dotted lines extending from the nozzle opening, on its way downwards. From a fluid mechanics standpoint the flow is turbulent, yet not highly turbulent, and it will not be described in detail here. In one practical example an exit velocity may be in the region of 10-20 m/s, e.g. 13 m/s, and the nozzle-hole diameter 4 mm, i.e. in the turbulent region or transitional region. The dash-dotted line indicates the approximate position of an interface area between the first volume, above the line, and the second volume, below the line. In the same examples the nozzles 116 are arranged in two rows, with about 20 mm center-to-center distance of adjacent nozzles 116. In the interface area, there will always be a unidirectional flow, efficiently forming a gas flow barrier preventing mass transport from the second volume (II) to the first (I). The aseptic or sterile first volume may thus remain aseptic or sterile, independently of the atmosphere in the second volume. The level of the interface area (in the up-down direction in FIG. 2) may vary depending on if a package 108 is present or not, as well as during transportation of the package 108, but it must be stressed that the flow in the interface area will remain continuous at all times, which results in that a fixed and reliable level may be established above which the sterile or aseptic conditions are maintained, in the atmosphere as well as on surfaces of the machine and the package. The nozzles 116 may be arranged in rows, generally in pairs of nozzles 116 so as to define a symmetric setup. In the drawings there is one set of nozzles for each package indexing position, yet in the present working apparatus the nozzles 116 are arranged with a smaller distance in between, such that more than one pair of nozzles 116, on an average, is arranged in each indexing position. Since the generated flow is of relatively high velocity it will not as easily affected by interfering flows as prior art techniques. E.g. when the inventive concept is used in the filling zone of a filling machine, the interfering flows generated by the flow of a product into the package 108 will not affect the continuity gas flow barrier in the interface region. Interfering flows from neighboring zones, such as from the venting zone, will not affect the maintenance of the gas flow barrier. Gas evacuation means 122 are arranged in the second volume for driven evacuation of the gas, and these may be used to balance the net flow in the filling machine.

(13) FIG. 3 illustrates a second embodiment. In this embodiment flow restrictors 118, 120 have been arranged in the channel. In this way the void volume around a package 108 is reduced. This makes it possible to use less diverging injections of air through the nozzles 116, and easier to obtain a gas barrier, when a package 108 is present, when no package 116 is present, as well as during transportation of packages 108. The divergence of the nozzles 116 may be varied by varying their geometry, in a known manner. The flow restrictors will generate stabilized recirculation zones on the outside of the rows of nozzles 108 (in relation to an imaginary centerline between the nozzles), which is indicated by the curved, dotted arrows.

(14) FIG. 4 is a schematic side view of a filling machine performing the inventive method. The arrow indicates the machine direction, in which the packages may be transported in an intermittent manner or in a continuous manner.

(15) To summarize, some advantages of the present invention include that it may be optimized regarding the space it requires in the machine, and may have a much less space consuming design as compared to existing systems. This, e.g., facilitates the design of filling system and external cleaning, which has been described earlier in the application. With remained functionality it may be designed to require minimum cleaning effort. It has been described how prior art methods require manual cleaning of perforated plates. With the inventive technique cleaning of the nozzles 116 may be readily performed by injecting cleaning fluid instead of air through the injection system. The function of the present invention may also be maintained without the build-up of an overpressure, and it requires a comparatively small mass flow of air. Despite this, it may be used in environments where strong interfering flows are present. Some direct advantages of the less complex design are: simplified assembly during production, reduced downtime during service, etc.

(16) In its most simplified design the nozzles 116 have a circular cross section, and are arranged as machined openings in the ceiling of the chamber. Openings with circular cross section are readily machined and they provide a symmetric flow pattern. The skilled person realizes, however, that the nozzles may have any suitable form without departing from the inventive concept as defined by the claims.

(17) The present invention may be applied in a filling or packaging machine, further details of which are described in a number of copending Swedish patent applications, filed by the same applicant on the same day as the present application, which hereby are incorporated by reference. To this end further details of:

(18) A nozzle that may be used when treating the interior of the packaging containers is disclosed in the application with the title A device and a method for gaseous-treatment of packages (SE-0900906-9).

(19) A method for obtaining an optimized concentration of sterilization agent in a sterilization zone is disclosed in the application with the title A device and a method for sterilizing packages (SE-0900907-7).

(20) A device and method for maintaining asepticity is also disclosed in A device and a method for maintaining a gas flow barrier between two volumes of a channel (SE-0900913-5).

(21) A system for ensuring that entrainment air is present for the jet flows of the filling zone and venting zone is disclosed in the application with the title A system for treating packaging containers (SE-0900912-7).

(22) A device for providing cleaned air, which may be used for the as a source of entrainment air to jets in the venting zone and filling zone and surplus air in the filling zone, is disclosed in the application with the title A device for cleaned air provision (SE-0900908-5).

(23) Some various aspect of the filling or packaging machine are disclosed in the applications titled Packaging machine and packaging method I (SE-0900909-3) and Packaging machine and packaging method II (SE-0900910-1), respectively. A system for supplying entrainment air to jet air flows in the machine are disclosed in the application with the title A system for treating packaging containers (SE-0900912-7), relevant parts of which, as mentioned, are hereby incorporated by reference.