WO1996011073A1

WO1996011073A1 - Process and device for cleaning and sterilising objects

Info

Publication number: WO1996011073A1
Application number: PCT/DE1995/001367
Authority: WO
Inventors: Sönke EWERS; Thomas Schulz
Original assignee: E & S Automation Gmbh
Priority date: 1994-10-10
Filing date: 1995-10-05
Publication date: 1996-04-18
Also published as: AU3649695A; DE19581129D2; DE4436141A1

Abstract

In the cleaning process the objects are first taken into a cleaning bath subjected to ultra-sound containing a biologically degradable cleaning agent and then into a rinsing bath in which they are ultrasonically sterilised. An indicator is added to the rinsing bath in order to indicate a change in the redox potential and thus helps to detect impurities in the rinsing bath and log them using a recorder. The process is particularly suitable for cleaning and removing germs from plastic bottles.

Description

Method and device for cleaning and sterilizing objects

The invention relates to a method and a device for cleaning and sterilizing objects, in particular empty bottles of the beverage industry.

The automatic cleaning of vessels usually takes place in that the vessels are passed through different baths by means of a conveyor. The baths contain either lye or acid, which act as cleaning media. In addition, mechanical parameters such as spraying out or treating the vessels with brushes can increase the cleaning effect. Nozzles are used in particular for cleaning bottles. The inner and outer surfaces of the bottle are sprayed off with a high pressure jet. The cleaning effect can be increased by moving the nozzles or spraying at intervals.

In general, it can be stated that three parameters are responsible for the cleaning effect. These are the temperature of the cleaning bath, the chemical composition of the cleaning agent and the mechanical treatment of the vessels to be cleaned.

As is known, an increased temperature increases the cleaning effect, but has the disadvantage that the vessels to be cleaned have to be heated to the high temperature and cooled again. This requires a large amount of energy, which causes considerable costs. In addition, the vessels to be cleaned can be damaged by the temperature changes. this applies

especially for plastic vessels and especially for the frequently used PTFE bottles, which deform at temperatures that are too high (from 57 ° C).

The chemical composition of the cleaning agent allows a good cleaning effect to be achieved even at lower temperatures. However, it is problematic that the chemicals introduced into the cleaning baths are very wastewater-polluting and thus cause high wastewater costs.

The mechanical treatment of the vessels used to bring the main cleaning effect, but became less and less important as the cleaning machines became more and more automated. This is because, for example, the brushing of bottles can only be achieved by means of complex mechanics and the brushes used wear out easily.

Since the beverage industry, in particular, places high demands on the sterility of the vessels, the vessels must be sterilized after cleaning. Sterilization is usually carried out at high temperatures. However, this is very cost-intensive and especially not possible with plastic bottles, since the bottles would be destroyed. It is known to sterilize plastic bottles using sulfur dioxide or ozone. For this purpose, the bottles to be sterilized are immersed in an immersion bath enriched with sulphurous acid or ozone and emptied upside down after the required sterilization time has elapsed, sprayed with fresh water and, after a sufficiently long dripping time, set up again and fed to the filling device. The

However, using sulfur dioxide or ozone for sterilization has significant disadvantages. On the one hand, it is no longer possible to supply the used sulfur or ozone baths to conventional wastewater treatment plants, and on the other hand, the resulting exhaust gases have to be treated with a considerable amount of technical effort in order to avoid the entry of sulfur gases or ozone into the atmosphere, or extremely little to keep.

The known cleaning and sterilizing devices are therefore particularly unsuitable for cleaning PTFE bottles. Since plastic bottles do not have the surface flatness of glass bottles and can only be treated at significantly lower temperatures, a sterilized sterilization using the known methods is particularly difficult to achieve.

On the basis of the known prior art and the problems associated therewith, the object of the invention is to propose a method and a device for cleaning and sterilizing objects, in particular empty bottles of the beverage industry, with which it is possible to safely treat the objects to be treated, inexpensive and environmentally friendly to clean and sterilize.

The object is achieved according to the invention in that the objects first pass through a cleaning bath which is sonicated with ultrasound and contains a cleaning agent, and then through a rinsing bath in which the objects are sterilized with ultrasound and which is an indicator means

contains that, when it is broken down, changes the redox potential in the rinsing bath and thus measurably indicates contamination in the rinsing bath.

In the method according to the invention, the effect of the ultrasound sonication is used on the one hand to mechanically produce a cleaning effect on the objects by blasting away dirt particles from the surface of the objects by cavitation action, and on the other hand the ultrasound sonication is used to produce a sterilizing effect on the surface of the objects , in which the special physical process of cavitation is used to destroy microorganisms and spores on the surface of the object and in the bath. The elicitation of a cleaning effect by means of ultrasound is intensified in the present method through the use of preferably biodegradable cleaning agents, so that the surface of the objects can be cleaned down to the pores at a temperature of only about 30 ° C. In doing so, incrustations, remaining fillings in vessels and other dirt are removed both inside and outside of the objects. The use of a biodegradable cleaner, which will be 96% degraded after approx. 12 to 15 days, makes it possible to comply with all safety waste water regulations relating to environmental protection.

The rinsing bath following the cleaning bath serves to sterilize the objects, in particular vessels, by sonicating the cleaned vessels again with ultrasound. According to the invention, the ultrasonic energy is used to sterilize the bath including all immersed objects. Therefore, so much energy is transferred into the rinsing bath using ultrasound

introduced that the liquid tears apart at instability during the pull phase of the cavitation. This creates tiny void bubbles that contain a gas with a very strong negative pressure inside. In the following pressure phase, the bubbles collapse at high speed, whereby energy in the vicinity of these very small bubbles is released as a vacuum of the order of magnitude up to 1000 bar. Particularly at the interfaces between liquids and solids, instability points are preferably formed. Therefore, the cavitation in the present case arises primarily at the places where microorganisms of all kinds, such as bacteria, yeasts and other spores, adhere to the container wall. These micro-organisms are destroyed by the formation of the cavitation bubble on their surface by the high released energy and thus killed. A good germicidal effect is achieved by ultrasound in the range of 20-40 kHz. Local heat development also occurs during the implosion. These local heating points have temperatures of up to 5000 K with a lifespan of just a few microseconds and destroy the organisms through the action of heat.

It is also particularly advantageous that the cavitation phenomena preferably also take place in the innermost, finest cracks, pores, capillaries or the like and that, in contrast to other methods, particularly intensive disinfection takes place in these areas.

To check the sterilization effect, an indicator agent is added to the rinsing bath. This indicator is chosen so that by its Degradation the redox potential in the rinsing bath changes. By measuring the redox potential, a possible germ load in the rinsing bath can be determined immediately and can be indicated to the operating personnel by suitable devices, such as buzzer or flashing lights.

Hydrogen peroxide or ozone is particularly suitable as an indicator. Both agents react with existing germs and thereby reduce the redox potential in the rinsing bath. While ozone has the disadvantage that excess ozone is contained as a toxic component in the exhaust air, the addition of hydrogen peroxide as an indicator means also allows measurement of the redox potential. However, hydrogen peroxide has the advantage that when it is broken down into water, only oxygen is produced which can be released into the environment without any problems.

It is also advantageous if the flow of the vessels is stopped when the concentration of the indicator agent in the rinsing bath is below a certain limit and the vessels are sonicated while the indicator agent is being fed in until the limit value is no longer undershot. Such a safety device can be fully automated by means of a simple control and has the advantage that it is always ensured that only completely sterilized vessels leave the rinsing bath.

If the released contaminants are sucked off against the direction of movement of the vessels in the immersion bath, it is ensured that a flow arises in the rinsing bath which is less contaminated with impurities in the area of the cleaned vessels than in the area of the vessels still to be cleaned. In addition, the invention is based on the object of proposing a device for carrying out the method described, with which the proposed method can be carried out in a simple manner.

This object is achieved in that a cleaning bath and a rinsing bath are connected to a loading and unloading device arranged outside the baths.

Such a device differs from the known devices for cleaning vessels in that the vessels are not, as has been customary up to now, drawn in succession through the individual baths in a container carrier by means of chain conveyors, but are removed from the container carriers belonging to the cleaning bath after they have passed through the cleaning bath are led to the rinsing bath and are inserted there into the container supports belonging to the rinsing bath. While the conventional chain systems have carried both heat energy and cleaning agents from one bathroom to the next bathroom, the loading and unloading device located outside the bathrooms is suitable for transporting the vessels from one bathroom to the other without coming into contact with the bathrooms themselves take the next bath.

The vessels preferably each pass through the cleaning and rinsing baths in a cell wheel. The cell wheels offer an easy way to lead the vessels through the bath and then let the vessels drip out in the upper area of the cell wheel, so that no cleaning agent is carried over from one bath to the next. In addition, nozzles for spraying out the vessels can easily be arranged in the upper region of the cellular wheel. In order to empty the containers before cleaning and after the sterilization of residues and to allow them to drip out completely, a further cell wheel is proposed before the cleaning bath and after the rinsing bath. This cellular wheel serves on the one hand to empty the containers and on the other hand it can be used as a turning device to transfer the containers from the vertical position to the horizontal position in which they are fed to the cleaning bath and after sterilization from the horizontal position again to a vertical position attributed in which they leave the device for performing the method.

The compact, modular structure of the system makes it possible to expand the system with additional cellular wheels and / or additional baths in order to adapt the system to special cleaning requirements.

In contrast to conventional cleaning systems, there is hardly any water loss in the device according to the invention. Only the evaporation and a small amount of water carried through the vessels require that fresh water is added at certain intervals.

An embodiment is shown in the drawings and will be described in more detail below.

Show it:

Figure 1 is a view of a bottle washer in the

Top view

Figure 2 shows a section through the invention

Bottle cleaning system in Figure 1 along the line II-II and

Figure 3 shows a section through the invention

Bottle cleaning system in Figure 1 along the line III-III.

The device 1 for cleaning and sterilizing bottles essentially consists of four drums 2, 3, 4, 5 arranged one behind the other, a loading and unloading device 6, a bottle feed device 7 and a bottle discharge device 8. The bottle feed device 7 is a chain conveyor which carries the bottles 9 lined up in a line to the first drum 2 promotes. Shortly before the drum 2, a spacer wheel 10 is provided, which ensures that the bottles 9 move into the drum 1 at a distance from one another. The drum 2 has a cellular wheel 11, which can hold ten bottles 9 one after the other and leads on a circular arc around the axis 12 of the drum 2. The bottle battery 13, which consists of the ten bottles 9, is turned over so that the bottles 9 are transferred over a horizontal position to a vertical position in which the mouths of the bottles point downwards, in order to then move back on the circular path to come to a horizontal position. When the bottle battery 13 has arrived in its horizontal position, the loading and unloading device 6 engages the bottle battery 13. The loading and unloading device 6 pushes a bottle battery 13 of ten bottles 9 out of the drum 2 and into the drum 3 in cycles.

The drum 3 has a further cellular wheel 14, in which the bottle battery 13 runs downward in the circumferential direction into a cleaning bath 17, with which the drum 3 is filled to approximately half its height. After passing through the cleaning bath 17 in the drum 3, the bottle battery 13 is turned upside down so that cleaning bath residues can run out, and further led to the loading and unloading device 6.

The loading and unloading device 6 first leads the bottle battery 13 into a space between the drums 3 and 4 and then further into the cell wheel 15 of the drum 4, which contains a rinsing bath. This rinsing bath passes through the bottle battery 13 just like the cleaning bath just before, after which it is then pushed further into the cell wheel 16 of the drum 5 with the loading and unloading device 6.

In the cell wheel 16 of the drum 5, the bottle battery 13 only runs through a quarter circle in order to be led out of the drum 5 by the bottle discharge device 8 at the bottom of the drum 5. The bottle discharge device 8, like the bottle feed device 7, is a chain conveyor, on which the bottles 9 are led away standing one behind the other. FIG. 2 shows in cross section the drum 3 with the cell wheel 14. The cell wheel 14 is filled in the circumferential direction with bottle batteries 13 lying close together, only a few of which are shown in FIG. 2 for explanation. Each bottle battery 13 reaches the cell wheel 14 via the loading and unloading device 6. Within the cell wheel 14, the bottle battery 13 is first guided into the cleaning bath 17, which contains a biodegradable cleaning agent. A plurality of ultrasonic vibrators 18 are arranged on the lower circumference of the drum 3 and transmit the ultrasonic vibrations into the cleaning bath 17 in order to support the cleaning action of the cleaning bath. A control device 19 provides the power supply for the ultrasonic vibrators 18. While the bottles 9 pass through the cleaning bath 17, the biodegradable cleaning agent in combination with the ultrasonic vibrations completely cleans the bottles. After exiting the cleaning bath 17, the bottles pass through a spraying device 20, which injects targeted fresh membrane-filtered water with added cleaning agent into the bottles 9 and onto the walls of the bottles 9.

The spray water from the spray device 20 comes from the cleaning bath 17 and is removed from the sides and below at points 21.1 and 21.2. It then flows through a pre-filter 22 and is conveyed by means of a circulation pump 23 into a working container 24, from which it is conveyed via a pressure pump 25 into a membrane module system 26. The membrane module system 26 consists of a circulation line 27 with a circulation pump 28, via which the cleaning agent is passed through a membrane module 29. The filtered cleaning agent then reaches the spraying device 20 via a line 30 Compressed air connection 31 enables the filter membrane to be flushed at intervals.

Since cleaning agent is continuously removed from the drum 3 by moist bottles and evaporation, the lost cleaning agent must be fed to the cleaning bath in accordance with the water loss via a fresh water inflow 32 and a metering system 33.

At the upper end of the drum 3, a suction device 34 is provided, which sucks the steam generated in the cleaning bath and feeds it to a condenser 35. Dry air escapes via the condenser 35 and the condensate formed in the condenser is returned to the drum 3 via a line 36.

FIG. 3 shows the drum 4 with the rinsing bath 37, which is constructed essentially in the same way as the drum 3 with the cleaning bath 17. The bottles 9 coming from the drum 3 pass through the loading and unloading device 6 into the drum 4 immersed there in the rinsing bath 37 by means of the cell wheel 15, which is set into vibration with ultrasonic vibrators 38. The ultrasonic oscillators are connected to the control device 19 via a line 39. The rinsing bath 37 also has a spray device 40, a fresh water inflow 41 and a suction device 42.

The rinsing bath contains an indicator which is broken down if the bottles are not sufficiently sterilized. With this degradation, the redox potential in the rinsing bath changes, which is reflected in the redox measurement Dishwashing liquid can be easily identified. Suitable indicator agents are hydrogen peroxide (H ₂ 0 ₂ ), which is converted into water and oxygen in the case of impurities in the rinsing bath, or ozone, which decomposes to natural oxygen.

If ozone is used as an indicator, an ozone destroyer 43 must be provided after the suction device 42, since ozone should not be released into the atmosphere as a poison gas.

The ozone measurement is carried out in a water circuit 44 which leads from the lowest end of the drum 4 to the spray device 40. A filter 45, the redox measuring device 46, a circulation pump 47 and a reactor vessel 48 are provided in this circuit 44. The redox measuring device 46 reports the redox potential of a control device 49 which ensures that the rinsing liquid is re-sharpened depending on the redox potential. In addition, the control device 49 can stop the drive of the cellular wheel 15 if the redox potential falls below a lower limit value. Depending on the design of the control device 49, it can even be provided that the cellular wheel 15 moves backwards in order to rinse bottles 9, which have been treated with contaminated rinsing liquid, in the rinsing bath or to spray them out again.

The method according to the invention is suitable for the sterilization of any objects. For example, the sterilization of surgical instruments should also be mentioned. It is also suitable for liquids such as fruit juice or other substances such as jam or sewage sludge. The process can be used in one step as a pure sterilization process or in combination with any cleaning process. It is advantageous that the sterilization effect not only detects the objects in the liquid, but also the liquid itself.

Claims

claims

1. A method for cleaning and sterilizing objects (9), in particular emptied bottles of the beverage industry, in which the objects (9) first pass through a cleaning bath (17) which is sonicated with ultrasound and contains a cleaning agent, and then a rinsing bath (37). pass through, in which the objects (9) are ultrasonically sterilized and which contains an indicator agent which, when broken down, changes the redox potential in the rinsing bath (37) and thus measurably indicates contamination in the rinsing bath (37).

2. The method according to claim 1, characterized in that the indicator is hydrogen peroxide (H ₂ O ₂ ).

3. The method according to claim 1, characterized in that the indicator agent is ozone.

4. The method according to any one of the preceding claims, characterized in that when the concentration of the indicator agent in the rinsing bath (37) falls below a certain limit, the passage of the objects (9) is stopped and the objects (9) are sonicated while simultaneously adding new indicator means until the limit is no longer undershot.

5. The method according to any one of the preceding claims, characterized in that the contaminants released are sucked against the direction of movement of the objects (9).

6. Device for performing a method according to claims 1 to 4, with a cleaning bath (17) and a rinsing bath (37) which are connected to a loading and unloading system (6) arranged outside the baths.

7. The device according to claim 5, characterized in that the objects (9) in a cell wheel (14, 15) pass through the cleaning (17) and the rinsing bath (37).

8. Apparatus according to claim 5 or 6, characterized in that before the cleaning bath (17) and after the rinsing bath (37) a further cell wheel (11, 16) for turning the objects (9) is arranged vertically-horizontally or emptying .

9. The device according to claim 8, characterized in that the other cellular wheels (11,16) with the outside of the baths (17.37) arranged loading and unloading system (6) are connected.