Energy costs pure squeezed
January 1st 2008

PET bottling production at Tropicana's purpose-built facility in Zeebrugge, Belgium is making significant energy savings following the installation of one of the first new generation of ZD compressor and booster combinations – a concept that provides a 40bar, oilfree air facility for Europe's drink and beverage sector

Tropicana, a division of Pepsico International, has taken delivery of one of the first of Atlas Copco's new generation combined ZD 1400 VSD oilfree compressor and a 40 bar booster in Europe for PET bottling production in the drink and beverage industry.

For the first time, the Atlas Copco ZD combination features a Z rotary screw, oil-free air compressor that delivers quality dry air at 10.5bar and a D booster, raising the oil-free air pressure to 40bar for the PET blow moulding machines. The ZD combination has been developed as a complete integrated package and the installation incorporates Atlas Copco's Variable Speed Drive (VSD) technology, Electronikon and AirOptimizer control system, designed for multicompressor installations to provide significant regulated energy savings.

Quayside operation The Tropicana facility was opened in 2002 with production of blown PET bottles and carton filling with fresh chilled juice commencing the following year. Its quayside location in the Port of Zeebrugge, Belgium was purpose-selected to eliminate large movements of bulk tankers on the busy highways. Fresh juice is unloaded directly from the ships into the plant's tank farm, under aseptic conditions. This tank farm is kept refrigerated just above freezing point in order to retain maximum freshness in the juice before being passed through to the blending and filling area, and finally to the packaging and automatic palleting process.

The filling area today features four carton lines and a PET bottle blowing line. The carton area is maintained as an ultra clean production facility while the PET facility is maintained under aseptic conditions. The facility also features a high speed Procomac PET line producing a range of bottles from 250ml up to 1.5 litre capacity.

PET air power Initially two Atlas Copco ZT 110 rotary screw, oil-free compressors were installed in the utility plant room to meet basic loads for carton filling. As production output increased, and with the introduction of PET bottles blown on-site, a ZT 160 VSD FF was installed to meet increased loads for oil-free air. Although the Z compressor and D booster have been designed to stand alongside each other as a combined installation, Tropicana engineers recognised that the initial phase of the operation only required the ZT 160 VSD compressor to operate until the PET moulding machine was delivered and commissioned.

Once the blow moulding plant had been installed, the D booster was subsequently sited in a separate plant room some 60m from the Z compressor but just 20m from the moulding room; thereby eliminating possible losses of air pressure in the airnet.

Energy savings Recognising that energy consumption is an increasingly major factor in a compressor's life cycle, Atlas Copco has designed the VSD option to maximise energy savings.

In a typical blowing operation, the moulding machine forms the production centrepiece, but it is surrounded by equally important peripheral equipment such as cappers, labelers and instrumentation – all requiring a reliable oil-free air supply. The VSD continually adjusts the speed of the motor load to match load requirements in the PET bottling plant. If the air demand drops, the motor slows and in doing so, uses less electrical energy. With VSD technology, energy consumption is reduced by up to 35% compared to a load/no load operation.

The Tropicana installation also features Atlas Copco's AIROptimizer package that regulates the three compressors.

Operational data measurements at Tropicana showed that without the regulating package, the specific energy requirement was 663J/l and an energy consumption of 24,371kW/h over one week. With the AIROptimizer, the specific energy requirement decreased to 603J/l and energy consumed fell to 22,165kW/h.

ZD installation benefits Commenting on the choice of an Atlas Copco's compressor system, Tropicana's maintenance manager, Mr StijnVan Paemelen said: "An important factor in opting for the ZD combination was the ease of installation. It is equipment that requires no special foundations or fixing systems; installation was just a simple 'plug in and play' operation and relocation in the future is also very simple". Adding, "Availability of service and support from Atlas Copco were also other key considerations in choosing the ZD option".

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