All of the process technology
For the process-engineering part of the project, Krones supplied the product UHT, designed as a VarioAsept J with shell-and-tube heat exchanger and including the ancillary equipment like the homogeniser and deaerator. In addition, Krones was also responsible for modifying and expanding the existing concentrate store and the syrup kitchen, for installing a new liquid-sugar store, for expanding the existing water treatment unit and the boiler house, for integrating a new cooling system and a new high-pressure and low-pressure system, and also for the entire electrical-engineering and piping installation. An LDS line documentation system for production data acquisition was an indispensable part of the whole, of course, given the line’s sheer complexity. And last but not least, Krones also handled the approval procedure for the entire line with the Spanish authorities. What was more, the entire modification and factory-expansion work had to be carried out while the existing two hotfill glass lines continued in operation, a very important aspect for the client and something that was achieved by providing the appropriate project management capabilities in conjunction with the associated technical layout and planning jobs in close liaison with the customer. The financial advantages of this approach for Pepsi-Cola Tafalla were manifest.
Sterilisation without any H2O2 condensation
The design-enhanced PET-Asept D process was virgin territory for everyone involved. In contrast to other hydrogen-peroxide methods, sterilisation is here performed without any H2O2 condensation. Rather, the bottle is preheated, and gaseous H2O2 is applied to the warm container surfaces, which after a brief sterilisation period is removed again by hot sterile air, down to a minimum residual concentration of less than 0.5 parts per million (ppm). Cold sterile air is used for subsequent cooling.
The impressive number of nine different container sizes and shapes is one of the line’s idiosyncrasies, as are its high output of 36,000 containers an hour and its BLOC configuration comprising blow-moulder and PET-Asept steriliser/filler. Thanks to this layout variant, the entire bottling operation has a very small footprint and can manage without any air conveyors whatsoever. The Contiform S20 blow-moulder produces the containers, using the relax concept with neck cooling. For prewarming the bottles, the process utilises the residual heat from the blow-moulding operation. Yet another advantage: the blow-moulding and sterilisation processes have been directly harmonised for optimum interaction.
Only H2O2 and nothing else – both inside and out
Container sterilisation itself is a continuous process, during which the same gas (H2O2) is used both inside and out. Interior sterilisation is carried out using nozzles, each with a spreader, which are inserted inside the containers. They make sure the sterilisation medium and the blow-out air are evenly distributed inside the container while also assuring efficient temperature and media distribution. An H2O2 atmosphere is created for sterilising the bottles’ exterior surfaces; for this purpose, a centralised ventilation system with a sterilisable HEPA filter generates an overpressure in the isolator, by controlled distribution for the flows of both gaseous H2O2 and sterile air from top to bottom. By utilising gaseous H2O2 as the only sterilising agent, the sterilisation process can be monitored from a central location, which in turn means fewer pressure transmitters, no switching valves, simplified instrumentation and control, and of course a reduced outlay for care and maintenance – so overall it’s a simple process not easily unsettled.
For further enhancement of microbiological safety, the filler is sealed off during production and surface disinfection by two water seals. This functions by guiding the rotating interior filler carousel with T-shaped ends engaging at the top and bottom in a U-shaped ring channel filled with disinfectant. This dependably separates the interior from the filler’s surroundings, while at the same time reducing the volume of air required for recirculation to maintain the overpressure in the interior.
Huge time gains for the cleaning routines
Interior and exterior cleaning routines have also been significantly enhanced, something which is also and especially reflected in huge time gains. Instead of alkaline foam and acidic foam, the only media used are hot caustic at approx. 70 degrees and acid at about 60 degrees Celsius. Firstly, this means that the number of media needed has been reduced by two, that they are batch-type media, which can be recirculated, and do not have to be thrown away as was previously the case with the foam. This, of course, cuts the costs for the cleaning agents involved. But secondly, and most importantly, interior and exterior cleaning routines can be performed simultaneously. This would not work with foam, because foam would dry immediately on the still-hot surfaces. This method of running both routines in parallel produces time savings of about 30 minutes for interior and exterior cleaning. What’s more, the verifiable cleaning result is also much better.
So the interval for main cleaning and disinfection of the last bottle from the previous filling run to the first bottle of the next filling run is reduced to a period of less than four hours. The line’s continuous running time at Pepsi-Cola Tafalla is 72 hours. And overall, sterilisation performance, too, is very high, with the log rate for the container being log six for the interior, and log four for the exterior and the isolator.
“Considering we’re handling nine different bottle formats, the line is unbelievably flexible”, says Javier Espronceda. “Usually, though, we have to bottle all the products once within a period of two weeks. What’s more, the flavours of the beverages concerned sometimes exhibit very short lifecycles, of just a few months. This isn’t good for performance, of course. The aim now is to reduce this high level of product diversity and the multiplicity of relatively small filling batches. We have a Ferrari, but we sometimes have to use it just to drive round the corner. The market first has to catch up when it comes to some products.” After all, every change-over costs time and money. Every flavour change takes about three-quarters of an hour, every container change needs three or four hours, with simultaneous exterior sterilisation of the filler room. The line can then be run for 72 hours continuously, after which a major cleaning and disinfection process has to be performed, which takes about 4 hours. “In summer, sometimes we run a particular size for three days at a time, while in winter we average one change-over a day”, explains Ignacio Peman.
During the planning work Pepsi Cola Tafalla had specified a series of parameters, like the desired reduction in micro-organisms, the quality of the chemicals, the type of filling valve. The rest was the responsibility of Krones’ development experts. To quote Javier Espronceda: “In the commissioning phase, of course, we had sunny days and rainy ones. But in view of the fact that the whole thing was a pilot project, we’re very satisfied. Both mechanically and qualitatively, the line is running very nicely, our people are really happy with it.