Device and Method for Sterilization During the Filling of Preferably Liquid Foodstuffs into Packaging Containers

Abstract

Shown and described are a method and a device for sterilisation during the filling of foodstuffs into packaging containers with a preheating zone, a sterilisation zone, a drying zone, a filling zone and a sealing zone, which form a sterile space and are arranged immediately adjacent to one another and are sealed at the top by a cover which accommodates the necessary supply elements and supply lines. In order to reliably prevent the penetration of microbes into the packaging units, open at the top, passing through the treatment zones, and into the sterile space formed by the treatment zones, essentially horizontal air guide elements having a plurality of openings are provided in the sterile space underneath the cover and that these are supplied with sterile air from above through the cover, so that underneath the air guide elements a laminar flow directed evenly downwards is formed.

Description

The invention relates to a device and a method for sterilisation during the filling of preferably liquid foodstuffs into packaging containers with a preheating zone, a sterilisation zone, a drying zone, a filling zone and a sealing zone, which form a sterile space and are arranged immediately adjacent to one another and are sealed at the top by a cover which accommodates the necessary supply elements and supply lines.

When filling in particular, liquid foodstuffs into packaging containers, one must—for reasons relating to hygiene and shelf life—always pay particular attention to sterilisation. The actual sterilisation here takes place using known methods in which the surfaces to be sterilised of the—still open—packaging, preferably composite cardboard/plastic packaging, must come into contact for a predetermined time period with a sterilising agent, which subsequently, i.e. prior to the actual filling process, must be removed again from the surface of the packaging (DE 30 36 972 C2).

In order to make this sterilisation process as cost-effective as possible, there has been a shift to using H₂O₂, i.e. hydrogen peroxide, as a sterilising agent. An optimum effect is then achieved when the packaging units to be filled are heated in a first zone (preheating zone) in order to be able to carry out the sterilisation as quickly and efficiently as possible. The packaging units which are continuously moved along are transported from the preheating zone into the downstream sterilisation zone, where they are wetted with the sterilising agent, preferably H₂O₂. For this purpose, the liquid H₂O₂ is atomised using hot compressed air or superheated steam into an H₂O₂ aerosol, so that no larger, heavier droplets can condense on the packaging surface which could no longer simply be removed during the subsequent rinsing process.

It has been shown that the brief wetting with the H₂O₂ aerosol in a hot atmosphere is sufficient for any microbes present to be reliably killed off. By preheating the open packaging units, condensation of aerosol droplets is reliably prevented. In order, now, to remove the H₂O₂ aerosol from the packaging units once again, the packaging units pass through a further zone, that which is known as the drying zone. In this zone, the packaging units are flushed with hot sterile air at atmospheric pressure. Subsequently, in a filling zone, the actual filling of the packaging units takes place using means that are likewise known. Finally, the filled packaging units are sealed directly after the filling process in a sealing zone.

Since sterile conditions must be present in all the aforementioned five zones, the individual zones are to a large extent sealed off from the outside in order to be able to transport the packaging units inside a germicidal atmosphere. Although the use of H₂O₂ has proved itself for sterilisation, with the filling machines used it must be ensured, firstly for economic reasons and secondly for health reasons (hydrogen peroxide is a strong oxidising agent), that none of the H₂O₂ atmosphere reaches the room in which the filling machine is located.

Since the individual zones can always be only inadequately sealed off at the bottom and in particular in the direction of transportation of the packaging units because the packaging units—open at the top—are moved continuously through the device by means of cell chains that receive these units, a closing of inflow and outflow in the manner of an (air)lock is not possible. In the generic device for sterilisation (EP 0 726 203 B1) it has therefore already been proposed that all five zones named be amalgamated into a single sterile space and this be sealed using a collective removable lid, which has a cavity in which the distribution and supply elements are housed. However, this known device, too, is subject to the problems of the packaging units to be filled always being continuously transported.

The object of the invention is therefore to design and further develop the device, named at the beginning and described in more detail above, in such a way that penetration of microbes into the open packaging units passing through the treatment zones and into the sterile space formed by the treatment zones is reliably prevented. Over and above this, a simple construction of the device is desired in order, also, to minimise the cleaning and maintenance work (and costs) that is always necessary.

This object is achieved by there being provided, underneath the cover, essentially horizontal air guide elements having a plurality of openings and by these having sterile air supplied to them from above through the cover, so that underneath the air guide elements a laminar flow in an even downward direction is formed. By this means it is ensured that dust or microbes which could reach the interior of the device via the transport chains have no possibility at this point of rising against the laminar flow. Hence they remain in the lower section of the device and/or are transported from there further down and out of the device.

According to a preferred teaching of the invention, the air guide elements are arranged at least in the area of the drying zone, filling zone and sealing zone. The air guide elements may have different designs depending on the zone. On the one hand there may be an adaptation to the already pre-determined size of the respective zone but on the other, a specific orientation of the laminar flow can also take place depending on the zone and the (pipe)lines located therein.

According to a further embodiment of the invention, separating walls extending vertically from the cover in a downward direction as far as the respective air guide element are provided at the zone boundaries; these seal the zones off from one another in the upper section of the sterile space and thereby prevent a horizontal exchange of air, as a result of which the formation of a laminar flow in an even downward direction is further improved. By this means, a sterile air chamber can be formed for each individual zone.

Tests have shown that it is particularly suitable if, according to a further teaching of the invention, at least one pre-distributor element spanning the entire width of the device, to which sterile air is supplied via the supply pipe running vertically through the cover, is arranged in each sterile air chamber. Each pre-distributor element can have a plurality of openings at least on its horizontal base in order to let through the supplied air in a downward direction into the respective sterile air chamber. The pre-distributor element may for example consist of a U-shaped metal sheet.

According to a further preferred embodiment of the invention it is provided that a structure acting as an impact zone and not equipped with openings, such as for example an impact plate, is provided in each pre-distributor element, below the supply pipes. Such an impact plate ensures that the sterile air supplied to the pre-distributor chamber at a slight overpressure initially spreads horizontally within the pre-distributor and then is released evenly across the entire width of the device to the sterile air chamber.

Another embodiment of the invention provides that the openings in the air guide elements and/or the pre-distributor elements are chamfered on the inlet and/or outlet sides in order to minimise or if possible completely avoid turbulence in the sterile air upon passage through these openings.

According to a further teaching of the invention, all the openings in the air guide elements and/or pre-distributor elements are arranged so as to be evenly distributed. This allows particularly simple manufacture of these elements. However, it is also possible for the openings to be designed smaller or larger in particular sections, or to be arranged concentrated to a larger or smaller extent so as to take into account the prevailing geometry in the individual zones (through components etc.).

A further preferred embodiment of the invention provides that the air guide elements and/or pre-distributor elements are designed as perforated metal sheets. It is also possible, however, to use honeycomb sheets or similar. Preferably, the air guide elements or pre-distributor elements consist of stainless steel.

Alternatively, it is also conceivable for the air guide elements and/or pre-distributor elements to be designed as grid structures or the like.

Another teaching of the invention provides that the air guide elements and/or pre-distributor elements are attached to the cover so as to be detachable using retaining brackets or clasps. To this end, the air guide elements and/or pre-distributor elements can be equipped with lugs or hooks which correspond to the retaining brackets or clasps. By arranging the retaining elements on the air guide elements or pre-distributor elements appropriately, it can be ensured that these can only be attached in the device in the correct orientation.

According to a further preferred teaching of the invention, it is provided that the walls of the device running parallel to the direction of transport of the packaging units are designed as transparent panes and that in each pane and/or on the housing of the device a groove, running all the way round, is present which is connected to at least one of the pre-distributor elements. By this means, the pre-distributor chamber produced between the cover and the pre-distributor element, which is open on both faces, can perform the additional role of supplying the annular groove, running all the way around, with sterile air at slight overpressure. In this way, a barrier results which effectively prevents the penetration of microbe-containing air into the interior of the device.

The invention also relates to a method for sterilisation during the filling of preferably liquid foodstuffs into packaging containers, comprising the following steps:

a) Provision of a device for sterilisation during the filling of preferably liquid foodstuffs into packaging containers with a preheating zone, a sterilisation zone, a drying zone, a filling zone and a sealing zone, which form a sterile space and are arranged immediately adjacent to one another and are sealed at the top by a cover which accommodates the necessary supply elements and supply lines;

b) Provision of at least one cut section or packaging sleeve that can be moulded into a packaging unit.

For this method, the object of the invention is achieved by the packaging unit, of which there is at least one, moulded from a mouldable cut section or packaging sleeve and open at the top, being transported discontinuously or continuously through the preheating zone, the sterilisation zone, the drying zone, the filling zone and the sealing zone and in the process having applied to it, continuously, a laminar flow of sterile air that is directed evenly downwards.

Preferably, for the method in step a), a device according to one of claims 1 to 18 is provided.

According to a further teaching of the invention, the laminar sterile air flow has, at least in sections, an overpressure of 0.12 bar to 0.55 bar, preferably of 0.18 bar to 0.32 bar. The aforementioned overpressure is measured within the sterile chamber for example with the aid of a Prandtl tube.

Finally, it is provided according to a further development of the invention that the packaging unit, of which there is at least one, is transported at a transport speed of 0.8 m/s to 3.0 m/s, preferably at 1.2 m/s to 1.8 m/s through the zones.

The invention is explained in more detail below using a drawing depicting only one embodiment. In the drawings:

FIG. 1 shows a cover of a device according to the invention in side view,

FIG. 2 shows the cover from FIG. 1, open at the top, in perspective view,

FIG. 3 shows the preheating zone of the device, in vertical cross section, along the line III-III in FIG. 1,

FIG. 4A shows the drying zone of the device, in vertical cross section, along the line IV-IV in FIG. 1,

FIG. 4B shows the subject matter of FIG. 4A in perspective view,

FIG. 5 shows the filling zone of the device in vertical cross section along the line V-V in FIG. 1,

FIG. 6 shows the sealing zone of the device in vertical cross section along the line VI-VI in FIG. 1 and

FIG. 7 shows, in schematic representation, a cover disc placed on the side of the device.

FIG. 1 shows a cover 1 of the device according to the invention for sterilisation during the filling of preferably liquid foodstuffs into packaging containers in side view. There are displayed, consecutively from left to right, the individual zones passed through by packaging units P to be filled, namely preheating zone A, sterilisation zone B, drying zone C, filling zone D and sealing zone E.

The sterile space formed by individual zones A, B, C, D, E is bounded by a housing (not shown) that goes all the way round. At the top, the sterile space is, according to the invention, bounded by the cover 1, of which only a frame 2, going all the way round, and a cover panel 3 are discernible. As already known from the generic prior art, all the supply elements are contained within the cover 1. At the bottom, the ‘sterile space’ is not constructively bounded; its lower extension must however reach to below the packaging units P, that are open at the top, and is indicated in FIG. 1 with the dot-dashed line SH.

According to the invention, sterile air is now fed to the sterile space underneath the cover 1 through sterile air tubes which extend through the cover 1 and of which only sterile air nozzles 4 that protrude at the top are discernible. The sterile air nozzles 4 are supplied with sterile air via hoses (not shown). The supply elements comprise—in FIG. 1 from left to right—a distributor 5 for hot sterile air, an H2O₂ distributor 6, a sterile air distributor 7, two filling connections 8 with filling nozzles 9 arranged underneath them and a superheated steam distributor 10.

The aforementioned supply elements are significantly easier to see in the perspective view in FIG. 2 in which the cover 1 is shown open at the top. Here it is also possible to see supply lines (not described in any more detail). The device according to the invention serves the purpose of sterilising packaging units P that are open at the top, which are fed to the device along six parallel lines L1 to L6 through an outer wall 11 with, in the embodiment, six recesses 12.

Preheating connections 13 are connected to corresponding preheating nozzles 14, through which the packaging units P open at the top are flushed out with hot air or superheated steam in order to heat them, so that condensation of sterilising liquid in the interior of the packaging unit P is reliably prevented.

From FIG. 2 it can also be learned that underneath each of the three H₂O₂ distributors 6 each intended for two lines L1, L2; L3, L4 and L5, L6, H₂O₂ aerosol distributors 15 are arranged, of which H₂O₂ aerosol nozzles 16 lead through the cover 1 into the interior of the sterile space, as shown in FIG. 1. The H₂O₂ aerosol nozzles 16 reach down to just above the packaging units P. The H₂O₂ aerosol nozzles 16 end in a tunnel sheet 17 in order to minimise the unnecessary spread of hydrogen peroxide in the sterile space.

According to the invention, there are now several air guide elements arranged underneath cover 1 for the generation of a laminar sterile air flow directed downwards. In the drying zone C, in FIG. 1, a first air guide element 18 can be seen which has an L-shaped cross section and, together with the underside of the cover 1, forms a sterile chamber 19. In the interior of the sterile chamber 19, in the top left, a pre-distributor element 20 can be seen whose function is described in more detail further down. On the right, the sterile chamber 19 is separated by a separating wall 21 from the subsequent filling zone D. Filling zone D is also equipped with an air guide element 22 which, together with the separating wall 21 and the underside of the cover 1, forms a sterile chamber 23. In this, at the top right, a pre-distributor element 24 in cross section can be seen; this is also described in more detail further down. To the right the sterile chamber 23 is bounded by the separating wall 25.

It can also be seen in FIG. 1 that the sealing zone E also has an air guide element 26 and a pre-distributor element 27. The precise arrangement and function of the air guide elements 18, 22, 26 and pre-distributor elements 20, 24, 27 is described below using the additional figures.

In the perspective view in FIG. 2, the laminar sterile air flow that becomes established underneath the air guide elements 18, 22, 26 is indicated by means of arrows.

FIG. 3 initially shows a vertical cross section through the device according to the invention along the line III-III in the preheating zone A in the direction of transport of the packaging units P. Here it can first be seen that the cover according to the invention, of which only the outer frame 2 could be seen in FIGS. 1 and 2, is closed off at the bottom by a continuous metal sheet, which in the embodiment shown—and therefore in this respect the preferred embodiment—is formed as one piece with the frame 2. Resting on top of this a cover panel 3 can be seen which rises from outside towards the middle of the device. In front of the (not yet relevant in this zone) sterile air nozzles 4 one can see (in cut-away view) the already-mentioned sterile air distributor 5, from which a number of supply lines emanate, in order to conduct the hot sterile air to the consumers.

The cross section in FIG. 3 runs precisely through the two connections 13 provided on this side of the cover 1, from which (connections) the three preheating nozzles 14 lead up to directly above the packaging units P, open at the top, in order to heat these with superheated steam or with hot air. In FIG. 3, three tunnel sheets 17 can also be seen which run above the lines L4 to L6 shown in the area of the subsequent sterilisation zone D above the clear opening of the packaging units P, in order to minimise unnecessary spread of H₂O₂ in the interior of the sterile space. Finally, one can also see in FIG. 3 the wall, chamfered upwards in a vertical direction, of the air guide element 18, which constitutes the edge of the drying zone C.

FIG. 4A shows a vertical cross section through the drying zone C along the line IV-IV in FIG. 1. Here the two hot air distributors 7 can initially be seen, from which three hot air nozzles 7′ lead downwards up to above the mouth area of the open packaging units P. Here, the horizontal base of the air guide element 18 can be seen. This is equipped with a plurality of holes, which are not described in any more detail, and preferably designed as a perforated sheet which constitutes the lower boundary of the sterile chamber 19. In the upper section of sterile chamber 19, the pre-distributor element 20, which is designed as a U-shaped profiled metal sheet and is likewise equipped with a plurality of rows of holes, can be seen underneath the cover 1. In the latter, however, no holes are present directly underneath the sterile air nozzles 4, in order, as already described, to form impact zones (Prallzonen) PZ there. Finally, one can also see the separating wall 21 sealing off the sterile chamber 19 to the rear, which constitutes the boundary to the adjacent filling zone D. The arrangement of the aforementioned construction elements can be seen even more clearly in the perspective view according to FIG. 4B. This particularly applies to the air guide element 18 and the pre-distributor element 20.

FIG. 5 now shows a cross section along the line V-V in FIG. 1 in the area of the filling zone D. Here, the packaging units P are already filled. The sterile air fed from above via the sterile air nozzles 4 initially across the pre-distributor element 24 with corresponding impact zone PZ to the air guide element 22 fills the entire sterile chamber 23 and leads through the evenly perforated base of the air guide element 22 to a “sterile air curtain” formed thereunder which is intended to prevent microbes from below coming close to the openings of the packaging units P or components in the interior of the sterile space. In order also to, for the most part, seal off the filling zone D at the bottom, covering sheets 28 can be seen extending in the direction of transport of the packaging units P, which are attached with hooks 29 to the separating wall 25 that extends behind this in a vertical direction.

FIG. 6 shows a cutaway drawing along the line VI-VI in FIG. 1, i.e. in the area of the sealing zone E. In this area, too, sterile air nozzles 4 enable the supply of sterile air, initially into the pre-distributor element 27 and from there—evenly distributed across the entire width of the device—into the air guide element 26 arranged thereunder. Here, too, the air guide element 26 ensures that the hot sterile air is directed downwards and results in a laminar flow. The sealing equipment itself is not shown; but sealed packaging units P′ can already be seen here.

Finally, it is apparent from FIG. 7 that the walls of the device running parallel to the direction of transport of the packaging units P, whose housing is displayed here schematically as only rectangle 30, are designed as—preferably transparent—panes 31 and that in each pane 31 and/or on the housing 30 of the device a groove 32 running all the way around is present which is connected to at least one pre-distributor element 20. By this means, it is reliably achieved that, due to the overpressure prevailing in the annular groove 32, no microbes can penetrate into any leaks between housing 30 and pane 31.

Claims

1. A device for sterilisation during the filling of foodstuffs into packaging containers, the device comprising: a preheating zone, a sterilisation zone, a drying zone, a filling zone and a sealing zone, which form a sterile space and are arranged immediately adjacent to one another and are sealed at the top by a cover which accommodates the supply elements and supply lines,

wherein in the sterile space underneath the cover essentially horizontal air guide elements having a plurality of openings are provided and wherein sterile air is supplied to the air guide elements from above through the cover, so that underneath the air guide elements a laminar flow in an even downward direction is formed.

2. The device according to claim 1, wherein the air guide elements are arranged at least in the area of the drying zone, filling zone and sealing zone.

3. The device according to claim 2, wherein the air guide elements are designed differently depending on the zone.

4. The device according to claim 2, wherein separating walls extending vertically from the cover in a downward direction are provided at zone boundaries.

5. The device according to claim 4, wherein a sterile chamber is formed for each zone.

6. The device according to claim 5, wherein at least one pre-distributor element spanning the whole width of the device, into which the sterile air is fed via supply pipes running vertically through the cover, is arranged in each sterile chamber.

7. The device according to claim 6, wherein each pre-distributor element has a plurality of openings at least on its horizontal base.

8. The device according to claim 7, wherein a structure acting as an impact zone and not equipped with openings is provided in each pre-distributor element, directly underneath the supply pipes.

9. The device according to claim 1, wherein the openings are chamfered on at least one of the inlet and outlet sides.

10. The device according to claim 7, wherein the openings are arranged so as to be evenly distributed.

11. The device according to claim 9, wherein the openings are designed smaller or larger in particular sections or arranged concentrated to a larger or smaller extent.

12. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are designed as perforated sheets.

13. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are designed as honeycomb sheets.

14. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are made of stainless steel.

15. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are designed as grid structures.

16. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are attached to the cover so as to be detachable by means of retaining brackets.

17. The device according to claim 1, wherein the air guide elements or the pre-distributor elements are attached to the cover so as to be detachable by means of clasps.

18. The device according to claim 6, wherein the walls of the device running parallel to the direction of transport of the packaging units are designed as panes and wherein each pane or the housing of the device comprises a groove, running all the way round, which is connected to at least one pre-distributor element.

19. A method for sterilisation during the filling of foodstuffs into packaging containers comprising:

a) providing a device for sterilisation during the filling of foodstuffs into packaging containers, the device comprising a preheating zone, a sterilisation zone, a drying zone, a filling zone and a sealing zone, which form a sterile space and are arranged immediately adjacent to one another and are sealed at the top by a cover which accommodates supply elements and supply lines;

b) providing at least one cut section or packaging sleeve that can be moulded into a packaging unit;

wherein the packaging unit of which there is at least one, moulded from a mouldable cut section or packaging sleeve and open at the top, is transported discontinuously or continuously through the preheating zone, the sterilisation zone, the drying zone, the filling zone and the sealing zone and in the process has applied to it, continuously, a laminar flow of sterile air that is directed evenly downwards.

20. (canceled)

21. The method according to claim 19, wherein the laminar flow has, at least in sections, an overpressure of 0.12 bar to 0.55 bar.

22. The method according to claim 19, wherein the packaging unit, of which there is at least one, is transported at a transport speed of 0.8 m/s to 3.0 m/s through the zones.

23. A method for sterilisation during the filling of foodstuffs into packaging containers comprising:

a) providing the device according to claim 1;

b) providing at least one cut section or packaging sleeve that can be moulded into a packaging unit;

wherein the packaging unit of which there is at least one, moulded from a mouldable cut section or packaging sleeve and open at the top, is transported discontinuously or continuously through the preheating zone, the sterilisation zone, the drying zone, the filling zone and the sealing zone and in the process has applied to it, continuously, a laminar flow of sterile air that is directed evenly downwards.