Centralized Vacuum System Help Save Energy Costs

Vacuum is supplied by a pipework system with three vacuum circuits: rough vacuum, medium vacuum
and forming vacuum. Several vacuum pumps maintain a permanent rough vacuum of between 30 and
40 mbar in the vacuum reservoirs and pipework system. This vacuum is available directly at the
packaging point to evacuate the packaging to rough vacuum level. The medium vacuum circuit
is then activated.
 
The medium vacuum modules evacuate the packaging chamber and the packaging from rough vacuum
level to the final package pressure of less than 5 mbar. This two-stage evacuation has the advantage
of speed: the final pressure is achieved rapidly, allowing short cycle times. The two-stage process is
also the most energy-efficient way of achieving a vacuum of less than 5 mbar. Panda vacuum pumps
in a medium vacuum unit are used as vacuum boosters.
 
The forming vacuum circuit is used to form the plastic foil into trays. The vacuum level required is
between 100 and 200 mbar. A controller maintains the required vacuum level in all three vacuum
circuits, matching the demand created by the individual packaging lines. Vacuum pumps are switched
on or off as required, maintaining the desired pressure in the vacuum reservoirs.
 
The three packaging lines rarely require maximum pumping speed simultaneously, so in general only
some of the vacuum pumps are in operation. In the original decentralized vacuum system, both vacuum
pumps were started with the packaging machine and ran continuously at full speed. This maximum
output was dimensioned to meet the demand created by the shortest cycle time and largest packaging
volume of the machine.
 
The new centralized vacuum system has drastically reduced the running time of individual
vacuum pumps, which, in conjunction with the two-stage package evacuation, has resulted in significant
energy savings. The centralized vacuum system is located in an intermediate floor above the production
and packaging areas. The relocation of vacuum pumps installed directly to the packaging machines
prevents emitted heat from reaching the packaging machines and production area. In addition, no warm
air from vacuum pump exhausts is given off to air-conditioned rooms. This has reduced the cooling
required by the packaging machine tools, and air-conditioning costs are also lower.
 
As the centralized vacuum system is located externally, it is no longer necessary for service personnel to
enter the production area. Service technicians can carry out maintenance without interrupting
production, as the system has a reserve vacuum unit. Starting this reserve unit allows the first unit to be
disconnected from the network and maintenance tasks to be carried out. This has reduced expenditure,
as no production time is lost and maintenance is no longer required on weekends when costs are higher.