WO1988004143A1

WO1988004143A1 - Continuous sterilizer and also carrier from the said sterilizer

Info

Publication number: WO1988004143A1
Application number: PCT/US1987/003198
Authority: WO
Inventors: Johannes Hoppe; Daniel Lambertus Moellenkamp
Original assignee: Baxter Travenol Laboratories, Inc.
Priority date: 1986-12-11
Filing date: 1987-12-02
Publication date: 1988-06-16
Also published as: NL8603157A

Abstract

An apparatus for the thermal treatment of liquids packed in plastic bags includes a treatment chamber having an endless conveyor. The apparatus further includes through-shaped carriers (14), attachable to the endless conveyor, for receiving, transporting and discharging the plastic bags. Each carrier is constructed from three separate parts: two bases (15) each with a W-shaped cross section and a sidewall (16) with a U-shaped cross section. During operation of the apparatus, an opening (17) of the carrier (14) is parallel to the plane of the endless conveyor.

Description

Continuous sterilizer and also carrier from the said sterilizer

The invention relates to a device for the thermal treatment of liquids packed in plastic bags, comprising a treatment chamber and an endless conveyor with carriers for receiving, transporting and discharging the bags again and each carrier is formed as a trough-shaped container with an essentially C-shaped cross section, the opening of which is situated parallel to the plane of the conveyor and can be closed by a rotatable visor , which conveyor traverses a loop-shaped path inside the chamber and, outside thereof a cooling section, an unloading and loading station and a heating section, the two said sections each adjoining one side of the treatment chamber and each being provided with means for bringing about a pressure-controlling liquid seal (hydrostatic limb), while the treatment chamber possesses a controllable inlet for a pressurized gas and, in addition, liquid spraying elements are present at the top of the treatment chamber and of the cooling section.

A device of this type, but for application to pharmaceutical liquids in bottles, was described in the journal PHARHA-INTERNATIONAL, No. 1, 1968 by Ing. K. RUIG. A good four years later the same author described further additional details for the application to the sterilization of infusion liquids in plastic bags in the same journal PHARMA-INTERNATIONAL NO. 5, 1972.

It is stated that the nature of the heat treatment to which the plastic bags are subjected has not only already been described in two issues of the abovementioned journal PHARMA-INTERNATIONAL, but that a continuous sterilizer employing an atmosphere and an increased over pressure as a result of applying a gas supply is already known from the British patent 974,659. In this case, spraying elements are also used, only in the cooling section it is true, for increasing the caloric heat exchange. Another example of a heat treatment using steam with the application of an over pressure by supplying additional gas is the US Patent 1,584,397. Finally, reference is additionally made to the US Patent 3,619,126, from which a continuous sterilizer is known which has a treatment chamber inside which an over pressure is maintained by supplying additional gas while, in addition, spraying elements are present for increasing the heat transfer.

A problem which arises in this connection is the imprint of the contact surface of the inside of the carrier which often remains behind on the outside of a bag of this type, especially if these are formed with some perforations and/or sharp edges. The production of an imprint of this type is, inter alia, the consequence of the increased temperature in the treatment chamber and the weak or soft condition of the plastic which occurs as a result.

The object of the invention is to form the carriers from the device specified above in a manner such that while traversing the treatment chamber, the bags do not come into contact with sharp edges of the carrier. This object is achieved according to the invention in that eachtrough-shaped carrier is constructed from three separate parts:

- two carrier bases which have a rounded W-shape in cross section

- a side wall which is U-shape in cross section, which parts are held together by at least two end walls, the vϊsor also having a U-shaped cross section, and in that the rounded edges of the two carrier bases form a slit-shaped free passage with both the side wall and the visor .

As a result of this construction a hexagonal carrier is obtained which has two si it-shaped passages both at the top and bottom in any position while traversing the loop-shaped path. In this way, the liquid originating from the spraying elements can expediently enter the interior of each carrier and rinse the plastic bags, while these are, as it were, lying via a thin layer of liquid on the carrier base. While traversing the treatment chamber, the intrinsic weight of each bag rests essentially on a smooth plate and not on a sharp limiting edge. The two passage slits now present make a continuous and constantly self-renewing supply of liquid possible inside each carrier. The upward pressure, small, it is true, exerted on the bags as a result is able to provide an adequate guarantee that the smooth outside of the bags is retained in order in this way to prevent the fixing of any impression of the inside of the carrier occurring on the outside of the plastic bag.

The invention relates in particular to a device in which the conveyor consists of two chains situated parallel to each other at some distance and in which each carrier has on the two end walls an outwardly projecting pivot pin which is joined at its free end to a mounting plate which engages in two adjacent carrier pins of the transport chain, the visor being movably mounted on the two pivot pins between a loadedand a freely movable, i.e. rotatable, position as described, for example, in the US Patent 3,814,234. According to this invention said device is distinguished by the fact that the visor of each carrier is provided on both sides with t-wo projections which are disposed diametrically with respect to the pivot pin and which can each interact in the freely movable position of the visor during operation with a bumper element for rotating the visor through a quarter turn between a closed and an opened position and vice versa. In this way each carrier can be opened immediately before reaching the unloading station in order for it to be possible to unload the bags thereafter and in order to remain open until the loading station is passed (see related patent application No. (file 855,125)). The invention is also embodied in the carrier from the device described above, which carrier is distinguished in that the V-shaped centre of the W-shaped carrier base has an inwardly divergent form with ah angular position such that the bases (via the slit-shaped free passage) merge smoothly into the inwardly divergent sides of the U- shaped side wall.

The invention will now be explained in more detail on the basis of the drawing which shows a single embodi- ment of the device and of the carrier used therein.

Figure. 1 gives a very diagrammatic overall view of the device in a vertical section.

F i g u r e s 2A , B a n d C s h ow t h r e e p a r ts o f t h e c a r r i e r f r o m t he device according to Figure 1 in longitudinal section along the line II-II in Figures 3A and 3B.

Figures 3A and B are a longitudinal section perpendicular to the plane of Figures 2A-C.

Figure. 4 is a cross section of the carrier along the line IV-IV in Figures 2A-C. Figure. 5 shows a part of the conveyor in side view with two carriers received therein.

Figure. 6 shows a complete carrier on a reduced scale.

The construction of the continuous sterilizer according to the invention is described to an considerable extent in the journal PHARMA-INTERNATIONAL No. 1, 1968 mentioned above and consists of four vertical towers A-0 which are each subdivided into a number of columns. The columns 1 and 2 form the first tower A, the tower 8 con- sists of the columns 3 and 4 while the towers C and 0 are constructed from the columns 5 and 6, and 7 and 8, respectively. The tower A forms the heating section, the tower B the treatment chamber, the tower C is a transition zone and the tower D forms the cooling section. In addition, the device is provided with an endless conveyor 9 formed as a double chain which traverses a loop-shaped path within the heating set ion A, the treatment chamber B, the transition chamber C and the cooling section D. In addition, the conveyor 9 passes a loading station 10 and an unloading station 11. The conveyor 9, which is guided along a large number of wheels 12 is closed at the bottom of the device by means of the inactive linking part 13 of the path. During operation a pressure-controlling liquid seal or hydrostatic limb is produced in the usual manner in columns 2 and 7. The conveyor 9 is provided over its entire length with trough-shaped carriers 14 for the treatment of plastic bags.

As is best seen in Fig. 4, each carrier 14 is constructed of three separate parts, viz. two carrier bases 15 which are W-shaped in cross section and a side wall 16 which is U-shaped in cross section. The trough- shaped carrier 14 thus has an opening 17 through which the plastic bags can be introduced and removed again. To define the concept it may be stated that each carrier 14 has an elongated form and may, for example, have a length of almost two metres. The bases 15 and the side wall 16 are held together by two end walls 18, as well as by a number of dividing walls 19 (see the centre part of Figure 2). During operation, the opening 17 of the trough-shaped carrier 14 is parallel to the plane of the conveyor 9. Said opening 17 can be closed by a rotatable visor 20 which. like the side wall 16, has a U-shaped cross section. The parts 15 and 16 of the carrier 14 are not in contact with each other and the edges 21 of the two bases 15 form a slit-shaped clear passage 22 with both the side wall 16 and the visor 20. The V-shaped centre of the W- shaped carrier bases 15 has an inwardly divergent formwith an angular position such that each base (via the slit- shaped clear passage 22) merges smoothly into the inwardly divergent sides of the U-shaped side wall 16.

The conveyor 9 consists of two chains 23 which are disposed parallel to each other at some distance and which therefore have a mutual spacing in the given embodiment of approximately 2 metres. Each carrier 14 has an outwardly projecting pivot pin 24 on both end walls 18. At its free end, said pin is joined to a mounting plate 25 which engages in two adjacent carrier pins 26 of the respective conveyor chain 23. The visor 20 is movably mounted on the two pivot pins 24 between a locking position and a freely movable, i.e. rotatable, position.

The vfsor 20 of each carrier 14 is provided on both sides with two projections 27 and 28 disposed diametrically with respect to the pivot pin 24. In the freely movable position of the visor 20 and during operation each of said projections can interact with a bumper element (a roller) 29 and 30 respectively to rotate the visor through a quarter turn between a closed position (as shown in Figure 4 and at the top of Figure 5) and an opened position (shown at the bottom in Figure 5) and vice versa. The locked position of the visor 20 is shown in

Figure 3. For this purpose a locking pin 31 is mounted on the right-hand mounting plate 25, while a locking pin 32 is likewise mounted in the left-hand end wall 18 of the carrier 14. The visor 2.0 is formed with two end plates 33 which are each provided with two holes 34 which are disposed at 90° to each other and into which the locking pins 31 and 32 respectively fit. The visor 20 (seen in Figure 3) is pressed to the right by means of a conical compression spring 35, under which circumstances the pins 31 and 32 engage with one of the two holes 34. This is the so-called locked position which can come into being with a closed visor (top of Figure 5) and an opened visor (bottom half of Figure 5). To unlock the visor 20, a pushing element (not shown in more detail) is present along the path of the conveyor 9 for moving the visor along the pivot pin 24 against the pressure of the spring 35. At that instant one of the rollers 29 or 30 may come into contact with the projection 27 or 28 to rotate the visor 2.0 through a quarter turn, as a result of which said visor is opened or closed respectively.

Each carrier 14 is divided by means of a few partition walls 19 into a number of compartments in which the plastic bags to be treated may be placed. At the ends, each compartment is provided with a few perforations 36 (see Figures 2 and 4). In the loop-shaped path of the conveyor the carriers are in a position as shown in Figures 4 and 5. In the treatment chamber 3, 4, i.e. in the tower B, the spraying liquid used can easily flow into each carrier 14 as a result of the presence of the passages 22 which are always at the top of each carrier. Said liquid can also flow in via the perforations 36 and flow away again at the bottom while continuously washing the plastic bags present inside the carrier. In addition to the intensification of the heat transfer obtained as a result of this, a certain suspended condition of the plastic bags is also obtained as a result of the upward pressure of the liquid. All this works together to prevent the fault, which still sometimes occurs, of an imprint of the interior of the carriers present on the outside of the plastic bags.

Claims

C L A I M S 1. Device for the thermal treatment of liquids packed in plastic bags, comprising a treatment chamber and an endless conveyor with carriers for receiving, transporting and discharging the bags again, and each carrier is formed as a trough-shaped container with an essentially C-shaped cross section, the opening of which is situated parallel to the plane of the conveyor and can be closed by a rotatable visor, which conveyor traverses a loop-shaped path inside said chamber and outside thereof a cooling section, an unloading and a loading station and an heating section, the two said sections each adjoining one side of the treatment chamber and each being provided with means for bringing about a pressure-controlling liquid seal (hydrostatic limb), while the treatment chamber possesses a controllable inlet for a pressurized gas and, in addition. liquid spraying elements are present at the top of the treatment chamber and of the cooling section, characterized-in that each trough-shaped carrier (14) is constructed from three separate parts: - two carrier bases (15) which have a rounded W- shape in cross section and - a side wall (16) which is U-shaped in cross section which parts are held together by at least two end walls (18), that the vfsor (20) also has a U-shaped cross- section and that rounded edges (21) of the two carrier bases form a slit-shaped free passage (22) with both the side wall and the visor.

2. Device according to Claim 1, the conveyor consist- ing of two chains situated parallel to each other at some distance and each carrier having on the two end walls an outwardly projecting pivot pin which is joined at its free end to a mounting plate which engages in two adjacent carrier pins of the conveyor chain, the visor being mounted movably on the two pivot pins between a locked and freely movable, i.e. rotatable, position, characterized in that the visor (20) of each carrier (14) is provided on both sides with two projections (27,28), which are disposed diametrically with respect to the pivot pin (24) and which can each interact in the freely movable position of the visor during operation with a bumper element (29 and 30 respectively) for rotating the visor through a quarter turn between a closed and an opened position and vice versa.

3. Carrier from the device according to Claim 1 or 2, characterized in that the V-shaped centre of the W-shaped carrier bases (15) have an inwardly divergent form with an angular position such that the bases (via the slit- shaped free passage (22)) merge smoothly into the inwardly divergent sides of the U-shaped side wall (16).