JP4914971B2 - How to sterilize containers - Google Patents

Description

  The present invention relates to a method for sterilizing a group of containers in a sterilized chamber capable of being decompressed.

  A method of this kind, but including a number of steps that differ from that of the series, is known, for example, from US Pat. This known method is carried out in a sterilization chamber which is a component of a so-called linear filling machine in which the container to be filled moves linearly in the machine equipment. In so doing, a group of, for example, six containers are simultaneously in one sterilization chamber during sterilization. That is, all containers in the group are always at the same position in the process cycle. Mechanical equipment operates discontinuously. Sterilization itself is performed by a low-temperature plasma generated in the sterilization chamber.

  Such plasma sterilization is fundamental but requires a relatively high cycle time, and it has been found that there are several areas of insufficient sterilization both in the container and in the walls of the sterilization chamber itself.

Therefore, the efficiency of the known method is not satisfactory.
German Patent Application Publication No. 4408301

  The object of the present invention is to improve the periodic filling device in this way during sterilization in a method of sterilizing a group of containers in a sterilization chamber that can be decompressed, but without the low-temperature plasma used for sterilization. It is to provide a way to work with efficiency.

  This problem is solved by sequentially executing the steps recited in claim 1.

BEST MODE FOR CARRYING OUT THE INVENTION

  When sterilizing using hydrogen peroxide that is always present in an aqueous solution, the original sterilization is performed purely by the action of “activated” hydrogen peroxide. The term “activation” as used in this context is undefined per se, but a suitable heat supply causes a chemical and / or physical change with hydrogen peroxide, which ultimately leads to sterilization. It was found.

  In the process according to the invention, the “activation” of hydrogen peroxide takes place exactly when it is used for sterilization, ie during condensation. Subsequent removal of residual hydrogen peroxide is done simply by reducing the pressure to a point where the condensate components evaporate, which is possible very quickly and ensures that all hydrogen peroxide residues are removed.

  A vapor mixture of water vapor and hydrogen peroxide vapor necessary for sterilization is produced in the evaporator. As long as the evaporator can produce a sufficiently large amount of vapor with a sufficiently high concentration of hydrogen peroxide vapor in the vapor mixture within a sufficiently short time, the configuration of the evaporator is itself arbitrary for the present invention. The natural “activation” of hydrogen peroxide contained in the vapor mixture occurs in this case when it condenses on the surface to be sterilized. As a result, the vapor mixture wets the surface with a thin and uniform liquid film as much as possible.

Because of the slight layer thickness, no freezing phenomenon occurs during subsequent vacuum drying.

  Applicants speculate that the "activation" of hydrogen peroxide is caused by the evaporation enthalpy liberated upon condensation. The evaporation enthalpy liberated upon condensation provides the energy necessary to make the hydrogen peroxide molecules dissociable so that oxygen atoms are liberated. This chemically reactive atomic oxygen is probably responsible for bactericidal action.

  The temperature of the steam mixture, the pressure of the steam mixture before entering the sterilization chamber, and the sterilization chamber pressure at which condensation occurs can be used to influence the sterilization effect. In any case, the condensation pressure should be 500 mb or less, mainly in the range of 250-150 mb. The pressure required when removing the condensate should suitably be slightly below 4 mb.

  Since the preliminary vacuum for carrying the vapor mixture and the subsequent vacuum for removing the condensate are performed in the same sterilization chamber at different times, an intake / exhaust unit consisting of a vane pump and a subsequent roots pump is used to decompress the sterilization chamber. Can be used for both operating steps. However, the Roots pump is suitably bypassed during the preliminary decompression. This prevents the Roots pump from being exposed to an excessively high pressure differential.

  In other configurations of the invention, particularly when the sterilization chamber exceeds a certain volume, the vapor mixture to be supplied to the sterilization chamber and / or the sterile gas required to be injected into the sterilization chamber is upstream of the sterilization chamber. Each storage container provided in the storage container is refilled during an operation step in which the storage container is not required. As a result, it is achieved that the required vapor mixture and the sterilized gas required in the subsequent operation steps are prepared in a sufficient amount in a very short time.

Furthermore, since a relatively long time is available to inject into the storage container, the required throughput of the evaporator or bacteria filter is relatively small.

  Of particular importance for storage containers containing sterile gas is that a predeterminable pressure is generated therein, which determines the expected final pressure in the sterilization chamber. Although the pressure generated in the sterilization chamber cannot be controlled sufficiently during the injection due to the rapid injection, the final pressure in the sterilization chamber can thus be determined very accurately. At the moment of opening the sterilization chamber, there is a slight gauge pressure of about 0.2-0.8 mb in the sterilization chamber so that, for example, non-sterile ambient air does not reach the sterilized container at this dangerous stage. Would have to.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  Schematized FIG. 1 shows a part of the mechanical equipment in the region of the sterilization chamber 1. This mechanical facility is a mechanical complex that moves periodically and linearly. The sterilization chamber 1, the filling device, and the closing device are integrated in a single frame, and for example, about 12000 small containers per hour.・ Conceived for medium performance.

  According to FIG. 1, the transport belt 2 carries a group of containers 3 to the side of the sterilization chamber 1 in the supply direction A in the first cycle. In this case the group contains a total of 10 containers 3. In the next cycle, the container 3 in the standby position on the transport belt 2 next to the sterilization chamber 1 is simultaneously pushed into a holder (not shown) such as a lowered loading floor (not shown), and then the loading floor is sterilized upward. It can move into the chamber 1. After completion of the sterilization process, the loading floor is lowered again. In the next cycle, the sterilized containers 4 are now withdrawn from the sterilization chamber 1 as a group and delivered to the transport belt 5. The transport belt feeds the sterilized containers 4 in the transport direction B into the filling device, which has as many filling stations as there are container locations of the sterilization chamber 1. In other cycles, the sterilized container 4 can then be filled again by simultaneously moving under the filling valve by translation. Finally, in another cycle, the filled containers are removed from the filling device and moved again onto the opposite transport belt, which then transports the containers to the closure station.

  However, what is a problem in the present invention is the operation steps that take place exclusively in the region of the sterilization chamber 1.

  The time course of the sterilization process in the sterilization chamber 1 is shown as a diagram in FIG. 2, the abscissa is the time t in seconds [s], and the ordinate is the millibar [mb] units present in the sterilization chamber 1. The pressure P is shown.

Accordingly, curve 6 of the diagram shown in FIG. 2 shows the pressure transition over time.

  In the first operation step (a), the containers 3 prepared as a group are carried into the sterilization chamber 1 and this is performed at atmospheric pressure (1000 mb). In the next operating step (b), the sterilization chamber 1 is then hermetically closed. The closure time requires about 0.7 seconds.

  During the other operation step (c), the sterilization chamber 1 is at a pressure of 400 mb or less, mainly about 150 mb, i.e. the vapor mixture of the next incoming steam and hydrogen peroxide vapor can condense on the surface of the container 3. The pressure is reduced to a pressure that enables The preliminary decompression requires about 0.8 seconds.

  According to operation step (d), about 0.6 seconds is scheduled for putting the steam mixture into the pre-depressurized sterilization chamber 1. Condensation by the subsequent operating step (e) lasts about 0.8 seconds, depending on the boundary conditions selected. Within this time, the “activation” of hydrogen peroxide already described takes place, which leads to a very rapid and radical sterilization. The pressure in the sterilization chamber rises slightly again during the introduction of the steam mixture, as is evident from FIG.

  Now in another operating step (f), the condensate must be removed from the sterilized container 4 by depressurizing the sterilization chamber 1 to a pressure below the actual boiling point of water and hydrogen peroxide. It has been found that the final pressure in the operating step (f) must be slightly below 4 mb. This is the most time-consuming step in the sterilization process and lasts about 3.4 seconds.

  After the condensate is discharged, the sterilization chamber 1 is rapidly injected with aseptic gas, for example, aseptic air or aseptic nitrogen within 0.5 seconds. This takes place during the operating step (g), after which a pressure of about 0.3 mb above the atmospheric pressure present outside the mechanical installation is achieved. Finally, in the other operation steps (h) and (i), the sterilization chamber 1 can be opened, the sterilized container 4 can be opened, and the sterilization chamber 1 can be handed over to the transport belt 5.

  The total time of the sterilization process including loading and unloading of the sterilization chamber 1 is about 10.8 seconds.

  The cooperation of the functional elements attached to the sterilization chamber 1 is shown schematically in FIG. 3, and the container 3 is sterilized by these functional elements.

  Here, in mechanical equipment that operates periodically, the operation steps (c) and (f) occur with a time lag, and therefore the intake / exhaust unit 7 common to both operation steps can be used. The intake / exhaust unit 7 includes a vane pump 8 and a roots pump 9.

  Since very different pressure conditions exist between the operating steps (c) and (f), the gas flow of the operating step (c) can be passed by the bypass 11 by the bypass 11 via the controllable valve 10. The Roots pump 9 can be short-circuited in terms of pressure. Thereby, the preliminary decompression stage (c) is processed only by the vane pump 8.

  If a gas buffer 12 is additionally provided and can be opened via a controllable valve 13, the gas buffer can be injected at the beginning of step (c), thereby increasing the volume. Gas from the sterilization chamber 1 rapidly flows into the pre-depressurized volume and need not be transferred by the vane pump 8. In this case, the vane pump 8 can be designed to be small. The filled gas buffer 12 can then be depressurized again during the operation steps (a), (b), (g), (h), (i), i.e. when the pump output is not originally required. Like.

  The vapor mixture consisting of water vapor and hydrogen peroxide vapor required during the operation step (d) is produced by the evaporator 14 during the remaining stages and prepared in a storage vessel 15 heated to at least 100 °. Is done. The flow of the steam mixture into the sterilization chamber 1 is effected by opening the heated valves 16 for a short time. The number of valves 16 must provide a uniform flow of steam mixture into the sterilization chamber 1. Nozzles 17 are provided in the sterilization chamber 1 through which the vapor mixture flows into the sterilization chamber 1 to ensure a suitable spatial distribution of the inflow and a suitable inflow rate.

  The aqueous hydrogen peroxide solution is supplied to the evaporator 14 through the valve 18 in the direction of arrow C. If it is necessary, the valve 19 allows the evaporator 14 to be disconnected from the storage container 15. The other valve 20 enables the storage container 15 to be depressurized via the conduit 21. Therefore, air can be removed from the storage container 15 at the start of operation. Furthermore, if necessary, a periodic pressure drop can be performed in the storage container 15. This may be necessary if an excessively high residual pressure remains in the storage container 15 after the vapor mixture has entered the sterilization chamber 1.

  In the case of a relatively large facility, it may be meaningful to supply a plurality of evaporators 14 to the storage container 15. The storage container 15 has a temperature sensor 25 and a pressure sensor 26 for process control and normal function monitoring.

  It is monitored by the pressure sensor 22 that the condensate is removed without residue during the operating step (f). When the pressure limit is reduced to about 3.8 mb, the intake / exhaust valve 23 is closed, and the sterilized gas is injected into the sterilization chamber 1 through the injection valve 24 until the external pressure is reached. Only then can the sterilization chamber 1 be opened. A plurality of injection valves 24 are provided to evenly distribute the injection gas within the sterilization chamber 1 and prevent unfavorable flow conditions. There are also two intake / exhaust valves 23 for the same reason.

  During operation step (g), a gas volume of about 130 standard liters is required for injection within about 0.5 seconds. This number of standard liters corresponds to the volume of the sterilization chamber 1. Such a gas stream will be oversized and cannot be passed through a bacterial filter during injection.

For this reason, another storage container 27 is provided, which is aseptic via a bacterial filter 28 and a shut-off valve 29 with gespannt air or compressed nitrogen continuously during the remaining process steps. Filled with gas. For this reason, a suitable gas is supplied to the bacteria filter 28 via the valve 31 in the direction of arrow D.

  Due to the rapid injection, the pressure generated in the sterilization chamber 1 is virtually uncontrollable. However, if the volume ratio is known, as in this case, the pressure generated in the sterilization chamber 1 can be accurately determined by generating a very specific pressure in the storage container 27 before injection. it can.

This pressure determines the expected final pressure in the storage container 27 after pressure balancing. For this reason, a pressure sensor 30 is provided that operates with very high precision.

  Before opening the sterilization chamber 1, the pressure in the sterilization chamber 1 must match the external pressure of the machine equipment very precisely, and harmful flow generated by the pressure difference reaches the inside of the sterilization chamber 1 from the outside. It must have a slight gauge pressure of about 0.3 mb. In any case, microbial air must be avoided from flowing into the machine equipment area from the machine hall.

  On the one hand, the volume of the sterile gas storage container 27 will have to be as small as possible to save space. On the other hand, however, the required pressure would simply have to be so high that the injection accuracy to the level of the external pressure is not compromised. A good compromise is 1.5-2.5 bar. At the same time, the volume of the storage container substantially corresponds to 1.5 to 2 times the volume of the sterilization chamber 1. In the case of the arrangement, deoiled dry compressed air simply taken from the conduit can be used for this purpose.

It is a top view of the system which supplies and discharges a sterilization chamber and a group of containers, respectively. It is a diagram explaining each operation step. It is a diagram explaining the functional elements required for the method according to the present invention.

Claims (7)

In a method for sterilizing a group of containers in a sterilized chamber capable of decompression,
(A) carrying a group of containers into an open sterilization chamber;
(B) closing the sterilization chamber;
(C) pre-depressurizing the sterilization chamber to a pressure of 500 mb or less;
(D) supplying a vapor mixture comprising water vapor and hydrogen peroxide vapor to the sterilization chamber;
(E) condensing the vapor mixture on the surface of the container simultaneously with sterilization;
(F) removing the produced condensate by depressurizing the sterilization chamber to a pressure at which both components of the condensate evaporate;
(G) injecting sterile gas into the sterilization chamber;
(H) opening the sterilization chamber;
(I) removing a group of containers from the sterilization chamber;
A method characterized in that said step (e) is performed within 0.8 seconds .   The method of claim 1, wherein the sterilization chamber is depressurized to a pressure of about 4 mb to remove condensate.   3. A method according to claim 1 or 2, characterized in that an intake / exhaust unit consisting of a vane pump and a roots pump is used to depressurize the sterilization chamber, and the roots pump is bypassed by bypass during pre-depressurization.   In the operation step where the vapor mixture to be supplied to the sterilization chamber and / or the sterilization gas necessary for injection into the sterilization chamber are respectively provided in a storage container provided upstream of the sterilization chamber, no storage container is required. 4. The method according to any one of claims 1 to 3, characterized in that the storage container is filled again in the meantime.   5. A method according to claim 4, characterized in that a predeterminable pressure is generated in a storage container containing sterile gas and this pressure determines the expected final pressure in the sterilization chamber.   6. The method according to claim 5, wherein a slight gauge pressure of about 0.2 to 0.8 mb is present in the sterilization chamber at the moment of opening the sterilization chamber. In a method for sterilizing a group of containers in a sterilized chamber capable of decompression,
(A) carrying a group of containers into an open sterilization chamber;
(B) closing the sterilization chamber;
(C) pre-depressurizing the sterilization chamber to a pressure of 500 mb or less;
(D) supplying a vapor mixture comprising water vapor and hydrogen peroxide vapor to the sterilization chamber;
(E) condensing the vapor mixture on the surface of the container simultaneously with sterilization;
(F) removing the produced condensate by depressurizing the sterilization chamber to a pressure at which both components of the condensate evaporate;
(G) injecting sterile gas into the sterilization chamber;
(H) opening the sterilization chamber;
(I) removing a group of containers from the sterilization chamber;
A plurality of nozzles (17) are provided side by side in the horizontally long sterilization chamber (1) , and these nozzles (17) pass through these nozzles (17) so as to ensure the spatial distribution of the inflow and the inflow speed. , allowed to flow simultaneously vapor mixture into the sterilization chamber (1) by opening the valve (16) provided in each of the case, that multiple group of containers (3) is in the sterilization chamber (1) in Feature method.

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