Innovative KHS ultraclean concept with mini hygiene housing proves convincing

Ludwig Clüsserath*

Within the bottling industry ultraclean filling is still often performed in a glass hygiene housing that is open to the floor. In setups where the filler/capper system is not monoblocked with a blow molder, a rinsing system is installed upstream of the filler to disinfect the bottles. In order that ultraclean filling is even more sustainable KHS has developed a filling system with a mini hygiene housing into which the filler/capper system is integrated and monoblocked with the stretch blow molder. The entire transfer area for open bottles is tightly enclosed and permanently filled with sterile air. This means that the filling area is completely sealed and thus protected from any outside influences. Where this new InnoPET BloFill ultraclean system is utilized, the freshly blown plastic bottles don't have to be rinsed which reduces investment and operating costs. The mini hygiene housing – as its name suggests – is also much smaller than the classic ultraclean isolator, taking up 40% less space in the bottling shop. It also saves around 20% in detergents and sterile air. The consistent implementation of hygienic design in the new mini hygiene housing's machine area allows bottlers to always produce their beverages under the required hygienic conditions.  The plastic bottles in the monoblocked InnoPET Blomax Series IV stretch blow molder are also manufactured under extremely hygienic conditions. Here, KHS preform sterilization has been integrated into the heater area, and sterile air is blown into the preform and bottle transfer area in the stretch blow molder.  During transfer from the stretch blow molder to the filling system the insides of the containers are excellently protected against recontamination. Another special feature is that the bottle bases are cooled during transfer and the bottle exteriors disinfected thanks to the addition of chlorine dioxide. All told, the new InnoPET BloFill ultraclean concept gives the beverage industry nothing but benefits, and is absolutely ideal for both the pressurized filling of microbiologically sensitive beverages and pressureless filling.

Conventional low-germ filling

Beverages are normally divided into different levels of sensitivity which the filling process has to be able to account for. Beverages with a high carbon dioxide content are usually well protected against the growth of microorganisms. These include highly 

* Head of Filling and Processing Technology Development, KHS GmbH, Bad Kreuznach, Germany. 

    Phone: +49 671 852 2501

carbonated mineral water, soda pop, and cola beverages. For these types of drink conventional low-germ filling is totally adequate. However, products such as beer or mixed beer beverages, which are not heated in a tunnel pasteurizer, or milk and juice, which only have a shelf life of a few days in the cold chain, carry a much greater hygienic risk. Extra hygienic measures have to be implemented here in comparison to the classic low-germ filling process, the possibilities being an even more consistent hygienic design, the incorporation of automatic sanitizing systems, the installation of the machines in a very clean environment, and specific microbiological testing of machines and the filled product at defined intervals. 

Ultraclean filling 

Low-alcohol or non-alcoholic beverages with a limited CO2 content of between four and seven grams per liter are even more sensitive. Certain still beverages, which contain preservatives or Velcorin (Velcorin is a registered trademark of Lanxess Deutschland GmbH), can also be filled without pressure on the ultraclean system. These include fruit spritzers, slightly sparkling health and sports drinks, fruit juices and fruit juice beverages containing preservatives or Velcorin, and alcohol-free beer, alcohol-free wine, non-alcoholic sparkling wine, and mixed wine beverages. All of the above can be bottled using the ultraclean filling process. This procedure can also be used to fill still water.

Aseptic cold filling

Should beverages have absolutely no intrinsic protection against the growth of microorganisms (due to their CO2 or alcohol content, for instance) and if they also contain nutrients, aseptic filling is the filling process of choice – provided no preservatives are added to these beverages. This applies to still, flavored water, still health drinks, fruit juice, fruit juice beverages, and milk beverages, for example. Compared to classic hot filling, which would also be suitable for the aforementioned products, aseptic cold filling allows natural tastes and flavors to be retained in the beverage – as does ultraclean filling.  Added to this are various cost advantages which among other things stem from the ability to use lightweight, less expensive PET bottles. Equally important is that preservatives can be dispensed with – completely in the case of aseptic cold filling. With ultraclean filling this depends on the product scheduled for bottling. 

Holistic approach to aseptic cold filling and ultraclean filling

Like aseptic cold filling the ultraclean filling of beverages must always be seen from all sides. The steps involved in the manufacture of plastic bottles prior to filling must meet the high hygienic demands made of them by an ultraclean process, as must the product processing stages upstream of the filling process. Activities such as filtration and pasteurization ensure that product is supplied in a beverage-sterile state. On request KHS can provide customers with an all-inclusive, trouble-free package which includes not only the newly devised InnoPET BloFill ultraclean monoblock but also up-to-the-minute process technology from KHS. 

Preform sterilization in the heater area

The new InnoPET BloFill ultraclean monoblock concept contains a KHS InnoPET Blomax Series IV stretch blow molder whose heater is equipped with a sterile chamber module for the sterilization of preforms. A sterile air airlock reliably separates the sterile chamber at the preform infeed and discharge from the remaining heater area. Each preform is conveyed through the entire heater area by an active mandrel with side openings. Through these a mixture of hot air and hydrogen peroxide (H2O2) is pumped straight into the preform body at a temperature of approximately 120°C in the sterile chamber module, meaning that the preform is permanently covered in the gas mixture. This ensures that all inside surfaces of the preform plus the preform mouth are reliably sterilized. At the end of the process in the sterile chamber sterile air is fed in, enveloping the entire preform body. New sterile air is constantly introduced and any air contaminated with H2O2 permanently extracted. Any residue H2O2 still on the exterior of the preform is also reliably removed from the process in this way.

Once sterilization has finished the preform is given its exact heating profile in a separate heating chamber in the heater. The system works on near infrared radiation, which is shortwave radiation where the penetration of the preform wall is extremely intense. This is reinforced by the preform being conveyed through an enclosed heating chamber with all-round reflection. Compared to classic infrared radiation preform heating time is practically halved. 

Once the preform has passed through the heater area, the active mandrel hands it over to a gripper system. To prevent the preform from being recontaminated the gripper system segment to the blow molding station is enclosed. This enclosure is permanently filled with a downward flow of sterile air. The same principle is applied when the freshly blow molded PET bottles are discharged from the stretch blow molder. 

Servo-motor-controlled stretching process

A servo-motor-controlled stretching process built into the blow stations operates with the utmost precision. It ensures an optimum distribution of material during the manufacture of the PET bottles, thus specifically saving on materials and enabling very light PET bottles to be produced. It also gives operators high process stability, reducing the scrap rate. Equally, it permits the blow molder to perfectly adjust to the conditions of the filling system at all times. If the filler should be running slower, for instance, the stretching motion can still be carried out at the same rate and with the same precision as at the high machine speed despite the slower rotation speed of the stretch blow molder. 

Packing and filling areas consistently separated

When the bottles are removed from the blow station and passed on to the filler the distance between the freshly blow molded PET bottles adapts to suit that of the filling system. On their way to the filling system the PET bottles first pass through a sterile airlock which ensures that the dry area of the blow molder is kept quite separate from the wet area of the filler. This airlock is a composite part of the mini hygiene housing. A HEPA or high-efficiency particulate air filter system next to the airlock fills the adjacent transfer area with sterile air. This transfer segment includes integrated bottle base cooling and external bottle disinfection. The sterile air flows in the direction of the bottle guide and is specifically discharged before the bottles are passed onto the filler.

Bottle base cooling and sterilization all in one 

As a rule, slightly sparkling beverages are filled on an ultraclean system, although these are often combined with the bottling of still products. For this reason the transfer segment has a cooling module where the bases of the PET bottles, which reach temperatures of about 75°C in the blow molder, are cooled down to approximately 55°C. This procedure is essential if carbonated beverages are to be filled safely, the reason being that if pressure is applied to these hot PET bottles, bottle bases could bulge or in an extreme case even burst during filling. What's special here is that not just water is used to cool the bottle bases but water enriched with chlorine dioxide, the concentration of chlorine dioxide being between 0.5 and 1.5 ppm. This is because preform sterilization concentrates on the inside of the bottle, on the mouth, and on the sides. The effect of sterilization on the base is weaker, however. This gap in the system is now successfully closed by the bottle base being sprayed with a film of chlorine dioxide and water, enabling chlorine dioxide in the above concentration and at room temperature to achieve extremely high kill rates for all beverage contaminants relevant to ultraclean filling. Even if the base doesn't require cooling prior to filling still beverages into PET bottles, the spraying process is still applied for the purpose of sterilization.  

The cooling and sterilization process consumes the minimum amount of water and disinfectant, making it especially sustainable and cost effective. A system of nozzles constantly sprays a mixture of water and disinfectant onto the bottle bases, covering them with fine drops of mist. 

Constant supply of sterile air in the mini hygiene housing

As in the transfer segment there is a permanent supply of sterile air in the mini hygiene housing, this also ensured by the HEPA filter units. In the filler and capper area the flow of sterile air, which is kept at a slight overpressure, is conducted parallel to the bottle flow up to the point where the bottles leave the system. The air then escapes into the production shop, or is discharged from the shop through an extraction unit. Extraction is particularly recommended when water containing ozone is to be filled. Within the system the air is also forced out through small grooves in the upper and lower areas of the devices, these grooves created by the overlap of the rotating machine carousel and the static components. 

The filler area in the mini hygiene housing itself only contains the bottles, bottle grippers, and filling spouts, with the filling valves, product bowl, electronics, and control unit outside the sanitary zone. In the hygienic version of the capper the servo drives for the capping elements are also outside the hygiene area. In the mini hygiene housing up to 60,000 plastic bottles per hour holding between 0.1 and 3 liters can be processed.

Approx. 40% in space and around 20% in detergent saved

Compared to the classic ultraclean isolator the mini hygiene housing has fewer surfaces to be kept clean, meaning that the consumption of detergent is reduced by over 20%. Cleaning nozzles integrated into the system make sure that all areas included in the cleaning process, such as the surfaces of the stars and housing, the capper elements, and the filling spouts, are reliably accessed. The cleaning nozzles are fed by a newly developed KHS hygiene center with integrated chlorine dioxide preparation unit, among other features. The hygiene center doses the detergent and pumps this into the relevant circuits. Besides water three different cleaning media can be supplied to the hygiene center which, like the valve manifold, is right next to the filling system. The advantage here compared to previous setups is that there is less piping and the system is directly integrated into the machine control and operator monitor. 

Innofill DRV offers full range of advantages

Specially designed to satisfy the demands of ultraclean filling, the Innofill DRV-UCF filling system perfectly integrated into the mini hygiene housing is suitable for the bottling of a wide range of carbonated beverages and can be switched over to pressureless filling for still beverages at the mere press of a button. One of its special features is the twin control of certain functions in the filling valves, which eliminates a considerable number of gas valves, complete with their pneumatic and electrical controls, which in turn reduces servicing and maintenance costs. Despite these savings in components the full quality of the filling results is retained and each separate filling valve can still be individually switched. For instance, a filler with 140 filling stations now only has 280 gas control valves instead of 420.

When filling in an inert gas atmosphere (e.g. using CO2) the proportion of inert gas in the pressurized bottle can be freely selected depending on the beverage's sensitivity to oxygen. This cuts CO2 consumption costs by adapting the filling atmosphere to the specific requirements of the beverage.  The Innofill DRV is the only filling system not to have separately controlled lifting elements that press the bottle mouths to the filling valves. The bottle mouths are sealed against the filling valves by the internal bottle pressure being transfered to the neck ring holder via an aseptically designed expansion joint located inside the filling valve.  On our above filler example with 140 filling stations a further 140 pneumatic cylinders with their pneumatic and electric control elements therefore also become redundant. At the same time the pressing force couldn't be more exact. If, for instance, the filling pressure is high, the bottle is pressed against the filling valve with the required greater amount of force; if the filling pressure is low, a correspondingly lower pressing force is brought to bear. This ensures that the plastic bottles are handled extremely gently. Applying this procedure also reduces the number of wear parts, which means that maintenance intervals can be lengthened and the filling system runs with even greater efficiency.  

The Innofill DRV-UCF operates according to the principle of volumetric filling using electromagnetic induction flowmetering. The product to be filled is guided down the bottle walls as a film by a swirler. The advantage here is that there are no spreader elements protruding into the bottle, giving operators top hygienic conditions and high filling flexibility. Another plus is that the swirler also makes it possible to fill beverages with fiber lengths of up to 10 mm. The filling system is suitable for standard 28-mm or larger bottle mouths; as an option bottles with two different size mouths can also be processed, for which purpose the valve outlet and neck ring holder must be changed during conversion.

If only still water is to be bottled under ultraclean conditions in the mini hygiene housing, the Innofill NV-UCF filler can be utilized. This filling system operates on the same principle of volumetric filling where free-flow filling valves are used for non-contact filling of the PET bottles. 

Maximum hygienic safety a given

On both the Innofill DRV-UCF and the Innofill NV-UCF aseptic membranes and seals are used in all beverage and process gas passages. The rotary leadthrough for the transfer of beverages and all process media to the rotating filler carousel has sealing systems that do not need grease lubrication; special constructive measures also mean that no bearing lubrication grease can be transfered to the product and process gas areas. Here, too, full consideration has been given to the aspect of maximum hygienic product protection.

In the mini hygiene housing CIP sanitizing is always performed by automatically extending and retracting CIP plates. What's special about CIP sanitizing on the Innofill DRV filling system is that the same principle is used during the CIP process as with the bottle pressing during pressurized filling. The pressure of the rinsing media dictates the pressure with which the CIP plates seal the filling valves. The sealing procedure is thus highly efficient and geared entirely to the interior pressure in the simplest manner.

The tubular design of the ring bowl also meets the highest sanitizing specifications, its round form making it ideal for the CIP and SIP process. Compared to the rectangular product tank the tubular ring bowl also has the benefit of being much lighter, thus shortening heating and cooling times. Less energy is consumed and the lightweight construction of the filler turret also reduces the necessary drive forces.

Drop of liquid nitrogen for more bottle stability

Once still beverages have been filled it's possible to add a drop of liquid nitrogen to the bottle head space. This procedure is particularly recommended when filling still beverages into very light PET bottles. Doing so builds up the pressure, making the bottles more stable. Adding liquid nitrogen is also advantageous in that it helps to displace oxygen, in turn lengthening the shelf life of the bottled beverage.  

Innofill SV servo screw capper in use

Simple hygienic design, optimum accessibility for cleaning and disinfection, and consistent capping force for increased cap-opening convenience for consumers – these are the demands made on the optimum capper for ultraclean lines. The Innofill SV servo screw capper satisfies all of these requirements and is therefore perfect for ultraclean processes. It comes ready for operation in a monoblock with the filling system and arranged in the mini hygiene housing. All of the components in the hygiene chamber have an open design for effective sanitizing and disinfection and are easily accessed through the nozzles in the exterior sanitizing and disinfection system.  Another special feature is that each capping spindle, operating completely independently of the machine speed, is equipped with its own servo drive tailored to the particular style of cap. Changeovers are made at the push of a button, with the data for the various types of cap stored in the system. The capping station operates without any lubricants whatsoever and is thus extremely safe when it comes to hygiene. 

Cap sterilization options

Caps are placed in storage outside the mini hygiene housing. Wet process rinsing and UV sterilization can both be used to sterilize the caps. When the wet process is used, the caps are first rinsed with chlorine dioxide water and then with sterile water in an enclosed disinfection channel, the concentration of the chlorine dioxide being between 0.5 and 1.5 ppm. Sterile air is used to dry the caps before they enter the capping stations. The caps are conveyed through the disinfection channel solely by the drive energy generated by the spray media in an extremely simple yet effective process. During UV sterilization UV light ensures that microorganisms are killed within a very short time indeed. 

Correct ultraclean behavior training

As in classic ultraclean bottling, when using the new InnoPET BloFill ultraclean system with an integrated mini hygiene housing, complying with hygiene guidelines is extremely important. Following any intervention in the system an automatic, interim disinfection of all surfaces must always be carried out. KHS trains operating personnel on all relevant measures and the ultraclean behavior required. 

The validation process 

Successful validation provides proof that the ultraclean process has been optimized. In our example this procedure consists of a full microbiological check.  On ultraclean line equipment validation is successful when evidence is provided that the line is free of the contaminants specified for the respective beverage range. This means that during validation of an ultraclean setup the utmost care must be taken right down to the last detail. The first step is comprised of what are known as spray-shadow tests, followed by smear samples and air samples being taken. Each individual process function is systematically examined. Finally, a microbiological check of the filling results takes place.

Control through the multi-award-winning KHS operator panel

The new InnoPET BloFill ultraclean monoblock with its integrated mini hygiene housing is controlled by the multi-award-winning KHS HMI operator panel which combines excellent ergonomics and navigation, and has an extremely attractive design. The result is user-friendly machine operator prompting that employs buttons, colored graphics, easy-to-remember icons, and interactive handling instructions, all of which are self-explanatory. Operators also have access to varying degrees of viewing detail and different operating levels.

Full package of benefits

To sum up, KHS' new approach to ultraclean filling is marked by its many special features. These include, for example, the application of the preform sterilization process, PET bottle base cooling and simultaneous sterilization using water enriched with chlorine dioxide, filling PET bottles in the mini hygiene housing which not only saves on space but is also closed to the floor, and much lower media consumption thanks to the aforementioned reduction in space. Another aspect is the flexibility of the filling system which allows a wide range of beverages to be bottled. All told, the newly designed KHS ultraclean concept successfully combines increased sustainability with reduced costs while giving operators maximum microbiological safety.