Industry News - Bottling Beer in PET

No compromises

The expected consumer trend towards the consumption of beer in plastic bottles is one side of the coin. The other side of the coin relates to the optimized bottling of beer in plastic bottles. The brewing industry, which has long been predominantly fixed on the bottling of beer in glass bottles, must now turn its attention to the best possible way of bottling beer in plastic bottles, in order to be able to play a major qualitative role in the global scenario in the future.

The KHS Innofill DRS-ZMS/S provides the world's best combination of oxygen and CO2 levels in computer-controlled, short-tube filler systems.

Here, the important thing is to avoid compromise solutions. Particularly due to the gas permeability of plastic bottles, the objective when bottling beer in plastic bottles must be to achieve an oxygen content in the product, which is at least as low as when bottling beer in glass bottles. With the Innofill DRS-ZMS/S filling system, KHS provides a solution, which not only ensures the lowest oxygen absorption levels between 0.02 and 0.03 mg/l, but that also works with an extremely low CO2 consumption, which varies between 400 g/hl and 800 g/hl depending on the size of plastic bottle used. The Innofill DRS-ZMS/S is therefore the first computer-controlled pneumatic short-tube pressure filling system in the world to achieve such an outstanding combination of oxygen and CO2 levels.

The Innofill DRS-ZMS/S is a KHS innovation, which has been developed on the basis of extensive experience. The development of the new filling system was preceded by an exact analysis of the suitability of existing systems for bottling beer in plastic bottles.

A beer filling system comparison: Mechanical short-tube filling system...

First, let us consider mechanical short-tube filling systems. In this case, when beer is bottled in glass bottles, the oxygen absorbed into the product is an outstanding 0.02 to 0.03 mg/l. The CO2 consumption is 280 g/hl of beer. This is mainly achieved by the double pre-evacuation process. In this process, after the bottle, which is pressed against the filling valve, has been pre-evacuated, it is purged with CO2 followed by final evacuation. The product flows into a virtually pure CO2 atmosphere.

Although the double pre-evacuation process works outstandingly well when bottling beer in glass bottles, it cannot be used for plastic bottles. The sometimes extremely thin-walled plastic bottles cannot withstand any sort of vacuum, and deformation and damage would be the result of evacuation.

The alternative to double pre-evacuation when bottling beer in plastic bottles using mechanical short-tube filling systems is to purge the bottle with CO2 gas from the ring bowl. However, in this case, it is only possible to purge using the high filling pressure present in the ring bowl. CO2 can only be introduced into the bottle by using a large amount of energy. However, high purging pressures give rise to a backup pressure inside the plastic bottle.

In a closed purging process, in which the bottle mouth is pressed against the filling element during purging, up to 2500 g CO2/hl are required in order to achieve the necessary CO2 atmosphere for low-oxygen filling when there is no possibility of evacuation. In this case, the larger the bottle, the higher the CO2 consumption.

The CO2 consumption can be reduced by more than 50 percent if the bottle is not pressed against the filling valve during purging and the purged gas mixture is able to flow freely into the atmosphere via the open bottle mouth. Nevertheless, this type of open purging has serious disadvantages.

The gas passages in the filling valve must be dry before initiating the purging process. A "wet" purging process would lead to a difficult to control liberation of gas during the subsequent filling process and thus increased foaming. Dry gas passages are achieved by briefly blowing out the return gas passage in the loss angle between the infeed and discharge starwheel.

When the filling valves are blown out, beer residues remaining in the filling valve are sprayed outwards at high pressure. This leads to a noticeable wetting of the filler components with beer aerosols. The nutrient distribution in the critical hygienic area of the open bottles considerably increases the risk of contamination with microorganisms that can harm the beverage. A similar effect also occurs immediately on purging the open bottle. The purging gas escaping from the bottle collides with the filling valves and here too leads to a dispersal of beer residues. A further disadvantage of open purging relates to the increased level of CO2 in the vicinity of the machine operator. The CO2 purged out of the open bottle flows away over the machine.

When considered overall, the mechanical short-tube filling system is only suitable to a limited extent for bottling beer in plastic bottles, particularly because of the hygienic risks and on account of the extremely high CO2 consumption. This is due to the necessity to dispense with pre-evacuation and the use of a short filling tube, which simultaneously undertakes the functions of purging, pressurizing, return gas control and the determination of the filling level.

... and traditional computer-controlled short-tube probe filling system

Another option is the Innofill DRS-ZMS computer-controlled short-tube probe filling system. When bottling beer in glass bottles, this filling system works with triple pre-evacuation and double CO2 purging before the pressurization and filling processes. In this case, an oxygen pickup of 0.02 to 0.03 mg/l is achieved with a CO2 consumption of 230 g/hl of beer. Compared with mechanically controlled short-tube filling systems, this means a further reduction in CO2 consumption when bottling beer in glass bottles, which again cannot be maintained when bottling beer in plastic bottles. An identical "backup pressure effect", as already described when using mechanical short-tube filling systems, occurs when CO2 is introduced into the plastic bottle. Here too, the CO2 consumption is high in order to obtain the required concentration of CO2 in the bottle before the start of the filling process and to achieve low-oxygen pickup filling at levels between 0.02 and 0.03 mg/l O2 absorption. The microbiological and hygienic disadvantages are otherwise the same as those of the mechanical short-tube filling system.

The most interesting alternative up to now - the long-tube filling system

Instead of the mechanical short-tube filling system or the computer-controlled short-tube probe filling system, the computer-controlled long-tube filling system is a further conceivable possibility for bottling beer in plastic bottles. Long-tube filling systems are generally a means of implementing the bottom-up filling process without previous evacuation stages. The technological values are equally good for filling beer in both glass as well as PET bottles. In this case, the bottle materials are not important. The oxygen pickup lies between 0.02 and 0.03 mg/l and the CO2 consumption is approximately 600 g/hl. At first glance, therefore, a suitable system for bottling beer in plastic bottles. At second glance, however, some drawbacks come to light even with this system. It is always necessary to change filling tubes for different bottle sizes or different filling levels. As well as the time required for conversion work of this kind, the investment in different filling tubes is also a disadvantage. Added to this is the increased complexity of the system.

The optimum solution is based on a closed purging process under atmospheric pressure ("drinking straw effect")

The objective behind the development of the new filling system for the optimum bottling of beer in PET and plastic bottles was now to adapt the best performance offered by the short-tube probe filling system for bottling beer in glass bottles in such a way as to meet the requirements of plastic bottles. The newly developed Innofill DRS-ZMS/S filling system (the German abbreviations stand for pressure - computer-controlled - probe; double volume purging/purging tube) is based on the proven Innofill DRS-ZMS computer-controlled short-tube probe filling system. The special feature of the Innofill DRS-ZMS/S is that, with this system, the filling valve is designed so that the purging process steps are completely separate from the filling process steps. Along with optimum purging, optimum filling is therefore also guaranteed.

Plastic bottles like PET or others are purged with CO2 by means of a newly developed hollow tube probe, which is comprised of an outer tube, inner tube, and an insulated segment. The stream of gas can be individually controlled according to the shape and size of the bottle, and the height of the purging probe can be adjusted at the push of a button. With the help of the purging probe, a so-called "drinking straw effect" is achieved, which means that only that amount of gas enters the bottle, which is required to maintain atmospheric pressure during the purging with CO2. In this way, a high CO2 concentration level is achieved in the plastic bottle within a very short time coupled with a minimized consumption of CO2

As well as injecting the purging gas into the center of the bottle, the hollow probe also takes on the function of level measurement. While the first probe signal indicates the changeover from the fast filling phase to the slow filling phase, the second probe signal indicates the end of the filling process.

The switching points for the level measurement that are integrated into the hollow probe are independent of the length of the purging tube extended into the bottle mouth Compared with conventional short-tube filling systems, the end of the purging tube extends significantly further into the bottle resulting in a more efficient purging process.

The process of bottling beer in plastic bottles using the new Innofill DRS-ZMS/S filling system in brief: During the purging process with CO2, a path is established by means of a cylinder from the gas space in the ring bowl to the hollow probe. CO2 passes via the annular gap to the vacuum channel. An approximately 60-percent vacuum is always maintained within the vacuum channel. The feed quantity of CO2 is adjusted in proportion to the amount expelled, so that approximately atmospheric pressure prevails in the bottle during the purging process. The purging process is followed by the classic pressurization process. In doing so, the plastic bottle is not pressurized via the flow-restricted passage of the hollow probe, as this would lengthen the pressurization time. Pressurization now takes place directly from the ring bowl with the help of a second gas cylinder via an annular gap, which bypasses the hollow probe. As with other probe filling systems, pressurization is followed by the fast filling phase in the cylindrical area of the bottle over a swirler that conducts the product to the wall of the bottle. During this fast filling phase, return gas escapes into the ring bowl without restriction. As the neck of the bottle becomes narrower, the slow filling phase is initiated by means of a first probe signal. The connection to the ring bowl closes and a second cylinder now makes a connection via a nozzle into the pressure-free return gas channel. The filling speed is controlled by means of the quantity of gas discharging at the nozzle. When the preset filling level is reached, an appropriate signal is registered electronically at the second switching point of the hollow probe. On this signal, the filling valve closes and the filled product is calmed for a specified period. At the end of the process, the neck of the bottle is depressurized to atmospheric pressure.

Beer in plastic or glass bottles – Innofill DRS-ZMS/S is the right filling system every time

The newly developed KHS Innofill DRS-ZMS/S filling system is quite obviously the right system for bottling beer in plastic bottles. And it can do even more. Optionally, the filling system can also be used for bottling beer in glass bottles. A press of a button is all that is needed and the system changes over to the optimum process for bottling beer in glass bottles. For filling glass bottles, the Innofill DRS-ZMS/S then works with the process of triple pre-evacuation and double CO2 purging followed by the pressurization and filling process, which is extremely beneficial for filling glass, with a CO2 consumption of 230 g/hl and oxygen pickup levels between 0.02 and 0.03 mg/l.The motto: no-compromise quality for all filling tasks.

Oxygen in the headspace

The residual oxygen remaining in the headspace of the bottles after foaming depends on the type of cap and not on the bottle materials. The residual oxygen content in the headspace that can be achieved today with glass bottles in conjunction with crown cork and screw caps is also directly applicable to plastic bottles.

Minimum conversion times

In general, not only is the changeover from plastic to glass bottle filling extremely easy with the Innofill DRS-ZMS/S filling system, but also the changeover effort when filling different sized bottles is minimal. A push of a button is all that is needed to adjust the height of the hollow probe. No changeover work is required.

Not only the filling system of choice for bottling beer

Another highlight of the Innofill DRS-ZMS/S is that, as well as bottling beer in plastic and glass bottles, other carbonated beverages, such as soft drinks, can be bottled in plastic and glass bottles at any time.

High cost savings

However, a decisive highlight of the Innofill DRS-ZMS/S is, and will continue to be, that it is the first computer-controlled short-tube filler in the world to enable oxygen values between 0.02 and 0.03 mg/l with a low CO2 usage of 400 to 800 g/hl to be achieved when bottling beer in plastic bottles. For example, 500 g CO2/hl are used for the 0.5-liter longneck bottle, while 800 g CO2/hl relates to the 1.5-liter bottle.

Calculations clearly show that the low CO2 consumption is associated with a high saving in costs. An example of this is a cost comparison between filling the 0.5-liter longneck plastic bottle on a mechanically controlled short-tube filling system and on the Innofill DRS-ZMS/S filling system.

With an identical oxygen pickup in the product, the mechanically controlled short-tube filling system works with a closed purging process without the possibility of evacuation with approximately 2500 g CO2/hl, while the Innofill DRS-ZMS/S emerges with 500 g CO2/hl. Assuming two-shift operation and a system efficiency of 85 percent with 230 production days/year and costs of €0.12/kg of CO2, the annual saving comes to €187,680. The data are based on a machine output of 50,000 0.5-liter bottles per hour.

Closed purging process, no microbiological impact on the environment due to beer aerosols

A further advantage offered by the Innofill DRS-ZMS/S is that the purging of bottles with CO2 always takes place with the bottled mouth pressed against the filling valve. The process is thus a closed purging process. Excess CO2 therefore does not escape into the atmosphere, but is removed via closed channels. Above all, this is a major benefit to operating personnel. The closed purging process also has the advantage that no beer aerosols have a hygienic impact on the environment, which could result in microbiological contamination and risks to the product quality.

High standard of beverage hygiene

As a general principle, the limited number of moving parts within the Innofill DRS-ZMS/S guarantees that the system is easy to operate and to maintain. All of the seals and membranes that come in contact with the beverage and product-contacting gases are designed according to state-of-the-art standards of hygiene. Smooth-surfaced, easily accessible filling valves make effective cleaning and high hygienic standards possible.

Extensive practical trials exceed expectations

The superiority of the Innofill DRS-ZMS/S filling system for bottling beer in plastic bottles has been confirmed by extensive practical trials. In these trials, with outstanding oxygen pickup levels of 0.02 mg/l to 0.03 mg/l, in most cases the CO2 consumption actually fell short of the envisaged levels. Which again confirms that, with regard to CO2 consumption and oxygen pickup levels in the product when bottling beer in plastic bottles, the Innofill DRS-ZMS/S is the world's leading computer-controlled short-tube filling system. And all this at a cost of investment, which is definitely comparable to that of the computer-controlled short tube filling systems used to date.