Air Wizard Plus recycling system

THE Air Wizard Plus recycling system from Krones prepares the final blow-moulding air inside the machine, with the aid of the additional process stages of pre-blow-moulding, intermediate blow-moulding and stretching. This reduces the consumption of highly compressed air and energy costs as well.

Usually, PET containers are produced in the Contiform using a blowing pressure of 30 to 35 bar. Previously, compressed air remaining in the bottle had been pressure-relieved into a 10-bar compressed-air network. However, this caused losing the pressure differential between 10 and 35 bar.

Now the Air Wizard Plus prevents this from occurring. Krones installs a multi-stage snifting valve at each of the 20 blow-moulding stations of the Contiform S, and creates two additional compressed-air circuits:

- The high-pressure air from the containers is now pressure-relieved into an intermediate blow-moulding stage.

- New bottles are pre-blow-moulded using fresh low-pressure air at 6 to 10 bar.

- This is followed by intermediate blow-moulding using the recycled high-pressure air obtained beforehand from the final blow-moulding stage.

- Only for final blow-moulding at 30 to 35 bar does the Contiform now still need new high-pressure air at 35 bar. This change-over perceptibly eases the workload of the high-pressure compressor.

Air Wizard Plus recycling system verifiably reduces the consumption of highly compressed air – and thus the energy costs as well, says Krones

Small modification – huge impact

The system for intermediate blow-moulding is integrated into the software and visualisation function of the Contiform S, and displayed on the touch-screen. In order to evidence the system’s efficacy, it is advisable to measure the air consumption for all formats, both before and after installation of the upgrade. This and an optimisation of the blow-moulding process achieves energy savings of more 40%, depending on the preform’s material and weight, and on the volume, design, and specification of the container concerned. This also cuts the line’s operating costs, and downsizes the output of the high-pressure compressors by some 30%.

The internal high-pressure recycling system Air Wizard Plus can be retrofitted to almost all machines in the Contiform S series. However, the upgrade is not feasible in the case of machines that are using the NitroHotfill or Hotfill process, and the Contipure preform sterilisation system for reasons of process engineering.

Case study: PepsiCo Tafalla

PepsiCo’s facility at Tafalla, Spain was one of the first to install the Air Wizard Plus. Tafalla had already retrofitted the Air Wizard 2 in the Contiform S and therefore downsized the energy costs involved: Now part of the blowing air is used during the pressure-relief phase for pre-blow-moulding and stretching and an external supply of air is now no longer required for this purpose.

Together with the integrated compressed-air recovery from the stretching cylinders, the Tafalla plant’s total compressed-air savings can now reach 44%. The new high-pressure recycling system Air Wizard Plus has not only met PepsiCo’s stipulations regarding return on investment when it comes to capital expenditure involving sustainability, it has even outperformed them.

“PepsiCo is extending its environmental stewardship efforts to more members of its supply chain where it works while continuing to improve the efficiency of manufacturing operations, including energy efficiency use, water positive impact, among others. This improvement in our facility is one of those good examples,” emphasises Thomas Sauerwald, who is responsible for engineering at six PepsiCo facilities in Western Europe.

Smaller compressor now possible

Mr Sauerwald further explains: “Our PET-Asept D system has been up and running for about nine years now. And the high-pressure compressor is the same age. But since we now need substantially less compressed air, we can also replace this by a smaller model, such as one with a rating of meanwhile 1,200 instead of the previous 2,000 cubic metres per hour and 400 kilowatts power consumption. After all, technical advances have not made an exception of compressors: newer compressors are inherently more energy-economical than their older counterparts. For example, there are now frequency-controlled models with a direct drive instead of a belt drive system. Anyone can work out the resultant savings for himself.”

Besides all these energy-saving options, he singles out some further important points:

• The container quality remains equally good.
• The level of the final blow-moulding pressure is determinant.
• The internal high-pressure recycling system can be switched off at any time, and the Contiform will nonetheless continue to produce containers.

It took only a weekend to install the Air Wizard Plus. By Monday, the production line was up and running again.