Process for the mechanical cleaning of reusable drinks containers

In the case of a process for the mechanical cleaning of reusable drinks containers made of glass or plastic, the process comprising one or more washing cycles or zones and rinsing cycles or zones in a cleaning installation, the reusable drinks containers undergo pretreatment before being supplied to the actual cleaning installation. The reusable drinks containers are sprayed with an aqueous cleaning formulation by means of one or more nozzles which produce a spray yet which is directed into the interior of the reusable containers and, in the interior of the reusable containers, is transformed into a spray mist, with the result that the cleaning formulation is distributed uniformly. The pretreatment ensures that even stubborn dirt or microorganisms such as mold or yeasts is/are removed effectively in the cleaning installation.

FIELD OF THE INVENTION 
The invention relates to a process for the mechanical cleaning of reusable 
drinks containers made of glass or plastic, in particular bottles made of 
PET, PEN or PC. 
BACKGROUND OF THE INVENTION 
DE 3 707 366 A1 discloses a process which is intended for the continuous 
mechanical cleaning of everyday crockery and in the case of which the 
crockery which is contaminated with bits of food is doused with water in a 
prewashing cycle or a prewashing zone. Following the prewashing zone or 
the prewashing cycle, the crockery passes into a washing zone or a washing 
cycle, where it is sprayed with a metered washing liquor, which comprises 
preheated water to which a detergent has been added. Consequently, in 
particular dried-on or baked-on bits of food are swollen and detached. 
In a clear-washing zone, which follows the washing zone or the washing 
cycle, and in a rinsing zone, the detached bits of food are then removed 
together with the washing liquor. 
In order to reduce the resulting waste-water contamination and to achieve 
better cleaning of the crockery, a highly concentrated detergent solution 
is sprayed onto the crockery in finely distributed form in the washing 
zone and, after a certain contact time, is washed off in the clear-washing 
and rinsing zone together with the detached bits of food. 
In addition to the processes for cleaning everyday crockery, processes for 
cleaning reusable drinks containers are also known. The known reusable 
drinks containers, in particular glass and plastic bottles, undergo 
intensive cleaning before being refilled. And this cleaning operation has 
to satisfy the stringent requirements as laid down by food regulations. In 
the case of automatic filling installations, cleaning and filling of the 
drinks containers generally takes place in a self-contained installation. 
The known installations generally comprise a transporting device for the 
crates which contain the bottles, a device for unpacking the bottles and 
unscrewing the closure elements, a device for tracing, in the bottles, 
residues of substances which are a health hazard, this device also being 
known as a sniffer, a machine for cleaning the bottles, a filling device, 
a device for screwing on the closure caps, and a device for packing the 
bottles into the crates and for transporting the bottle crates. 
In the case of the known standard cleaning processes, cleaning of the 
reusable drinks containers takes place exclusively in the cleaning 
machine, which usually contains up to three lye baths. The concentration 
of NaOH therein is between 1.0 and 3.0% by weight, between 0.05 and 1.0% 
by weight of additives being metered into the lyes in order to stabilize 
hardness and to assist cleaning. Although such standard cleaning processes 
have proven successful in practice, there is a risk, in particular in the 
case of cleaning reusable plastic bottles made of PET, PEN and PC, that 
dirt which cannot readily be dissolved or else microorganisms such as 
mould and yeast is/are only partially removed in a cleaning machine, if at 
all. 
DEFINITION OF THE INVENTION 
The object of the invention is to specify a process which ensures complete 
removal of firmly adhering dirt and microorganisms such as mould and 
yeasts. 
The present invention describes a process for mechanically cleaning 
reusable drink containers made out of glass or plastic. The process has 
one or more washing cycles or zones and rinsing cycles or zones. In a 
pretreatment installation, an aqueous cleaning formation is sprayed onto 
the soiled containers by one or more spray nozzles which produce a spray 
jet which is directed through the opening into the interior of the 
containers. Once inside the drink containers, the formation is changed 
into a spray mist so that the cleaning formulation is uniformly 
distributed in the interior of the containers. 
DETAILED DESCRIPTION OF THE INVENTION 
In order to achieve uniform distribution of the cleaning formation in the 
interior of the reusable drinks containers, it is critical that, once it 
has entered into the container, the spray jet is transformed into a spray 
mist. In the case of the known reusable drinks bottles, uniform 
distribution of the cleaning formulation, in particular in the critical 
regions of the bottle neck, is advantageously achieved by a spray mist in 
the form of a hollow cone. 
The bottles are pretreated preferably during transportation to the cleaning 
installation. In the case of the filling lines known in the drinks 
industry, the cleaning formulation is sprayed downstream of the unscrewing 
device and, if present, downstream of the sniffer, as seem in the 
conveying direction. 
The contact time of the cleaning formulation is preferably between 0.5 and 
30 minutes. The reusable drinks containers are deliberately not sprayed 
during the contact time. In the case of particularly firmly adhering dirt, 
the empties may also be stored intermediately before they enter into the 
cleaning installation and may undergo pretreatment there in order to 
achieve contact times of up to a number of weeks. It was preferred, 
however, to incorporate the pretreatment in the known filling lines, it 
being possible for a sufficient contact time to be ensured generally 
without a reduction in the transporting speed. 
A preferred embodiment provides that, during the pretreatment, a conveying 
device conveys the reusable containers in a number of rows and a 
multiplicity of nozzles spray the reusable containers with the cleaning 
formulation, in which case, depending on the strength and nature of the 
dirt, the volume of liquid discharged from each nozzle is between 1 and 20 
l/h. 
The aqueous cleaning formulation preferably contains at least 0.5% by 
weight of one or more active detergents. The cleaning formulation is 
highly concentrated and is preferably mixed, directly before discharge, 
with lyes, acids or stabilizer solutions for the detergents via a metering 
system with water, the concentration of the cleaning formulation in the 
application solution being between 0.1 and 100% by weight, preferably 
between 0.5 and 3% by weight. 
A product which is suitable for removing the adhering dirt may be 
formulated from the following: 
______________________________________ 
Inorganic acid(s) 30 to 50% 
Wetting agent(s) 18 to 28% 
Dispersing polymer(s) 
2 to 7% 
Threshold agent 2 to 7% 
Chelating agent(s) 5 to 10% 
Water to make up the remainder. 
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An installation which is designed as a belt-type transporting machine and 
belongs to a filling line which is typical in the drinks industry, in the 
case of which the reusable drinks containers are pretreated by the process 
according to the invention, is explained in more detail hereinbelow with 
reference to the drawings:

The filling line has a device 1 for unpacking the bottles which are located 
in the crates. The bottles removed from the crates are transported, on a 
belt conveyor 2, into a device 3 for unscrewing the closure caps. Arranged 
downstream of the unscrewing device 3, as seen in the conveying direction, 
is a device 4 for tracing residues of substances which are a health 
hazard, e.g. petrol or the like, and this device has a suitable sensor. If 
the sensor in the device 4, which is also known as a sniffer, detects a 
corresponding substance, the bottle is directed away for final recovery 5. 
The bottles passing the sniffer 4 are conveyed to a cleaning installation 
6 of known construction by means of the belt conveyor 2, in which cleaning 
installation the bottles are cleaned in one or more washing cycles or 
zones and rinsing cycles or zones. The cleaning installation 6 comprises a 
bottle-supply means, two dipping lyes with spraying and draining zones 
located between them, a hot-water zone, a cold-water zone, a clean-water 
spray means and the bottle-discharging means. The pretreatment 
installation 7 for carrying out the process according to the invention is 
arranged between the sniffer 4 and the actual cleaning installation 6. 
FIG. 2 shows a preferred embodiment of the pretreatment installation 7. The 
installation comprises a number of spray nozzles 9, 10, 11 which are 
arranged in a row over the belt conveyor 2, directly above the bottle 
openings 9, a mixing device 12 and a container 13 which contains the 
cleaning formulation as well as a container 14 which contains lye, acid or 
the stabilizer solution are directed by means of diaphragm pumps 15, 16, 
via delivery lines 17, 18 in which metering valves 19, 20 are arranged, to 
a mixing point 21, a water line 22 which is connected at a water 
connection 22a also leading to this mixing point. Also arranged in the 
water line 22, for rinsing purposes, is a pipe discconnector 23 with an 
emptying tap 23a arranged upstream of its inlet and an emptying tap 23b 
arranged downstream of its inlet. The pipe disconnector 23 is followed by 
a pressure reducer 24, a solenoid valve 25 for automatically disconnecting 
the water supply, for example, when the belt conveyor 2 comes to a 
standstill, and a flow meter 26. The mixing point 21 is connected to the 
spray nozzles 9, 10, 11 via a branching delivery line 27, in which an air 
chamber 35 is arranged, needle valves 28, 29, 30 for setting the volume of 
liquid discharged from the nozzles in dependence on the strength or nature 
of the dirt being arranged in the individual line branches. In order to 
minimize atomization in the ambient air, the spray nozzles are 
encapsulated. 
FIG. 3 shows the spray pattern made by the spray nozzles 9, 10, 11 arranged 
above the bottle openings 8. The spray nozzles are designed such that they 
produce a spray jet in the form of a hollow cone. The rotationally 
symmetrical spray jet 31 essentially follows the contour of the bottle 
neck 32, which widens in the downward direction. Beneath the bottle neck 
32, the spray jet 31 is transformed into a fine spray mist which descends 
uniformly on to the cylindrical inner wall 343 of the bottles. The spray 
mist is illustrated by dashed lines, and provided with the reference 
numeral 33, in FIG. 3. While the bottles are moving on the belt conveyor 2 
in the direction of the cleaning installation 6, the cleaning formulation 
detaches the adhering dirt, which is then removed in the cleaning 
installation 6 together with the cleaning formulation.