34 fooD ProcESSInG
Decentralised method of opening
and closing of valves automatically
he cost-down pressures
Improved process valve inherent in all process
control techniques and
industries mean that plant
enhanced monitoring are
T
operators are consistently
vital to energy and waste
required to improve efficiency, at the
reduction in food and
beverage plants.
same time as ensuring repeatable product
quality. Moreover, these objectives have
to be achieved within the required
De meilleures techniques
environment of high hygiene standards,
de contrôle des vannes de where reliable assurance of clean and
procédé et une
cleanable pipework and equipment is
surveillance plus poussée
paramount.
sont cruciales pour
In pursuit of efficiency goals,
réduire la consommation
companies are prepared to invest
d’énergie et les déchets
dans les installations
heavily in new plant and equipment.
alimentaires et de
However, in many cases, real savings
boissons.
and improvements in efficiency can be
achieved relatively simply and at relatively
low cost by focussing on cutting energy
Verbesserte
usage, and by reducing product wastage.
Steuerungstechniken für
With valves, pumps and fans used
Prozessventile und
bessere Überwachung sind
widely in food and beverage production,
für die Senkung von
the possibilities for energy savings are
Energieverbrauch und die
considerable. Take compressed air, for
Abfallvermeidung in
example; its generation is equivalent
Lebensmittel- und to about 10 per cent of industry’s total
Getränkewerken
electricity usage, rising to 30 per cent
Fig. 1. Control heads integrate electrical and pneumatic
ausschlaggebend.
in some sectors. This highlights why
control components as well as position feedback units.
companies have compelling reasons to
pursue energy saving initiatives in this area. and closing of process valves automatically,
However, one area of pneumatic energy saving eliminating the need for the wasteful venting of
potential is still largely unexploited: improved control air normally associated with pneumatic
process valve control techniques. These can tubing between the process valve and its related
lead to reduced compressed air use through the control solenoid valve.
adoption of on-actuator or in-actuator pneumatic The control heads integrate electrical and
solenoid valves. pneumatic control components as well as position
At present, the majority of pneumatically feedback units and, optionally, an ATEX-approved
piloted valves on production and process lines version or field bus interfaces for AS-Interface
centralise pneumatic control around valve or DeviceNet. They are mounted directly above
islands in a control cabinet or enclosure. This the valve body, and, because there is little or no
arrangement means that the pipework carrying distance between the actuator and the valve that it
the pilot pressure to the actual valve from the is piloting, there is no air bleed: it is sealed. With
valve island can travel for many metres before it this system the pressure feed goes directly into
reaches the valve head. As a result, the venting the valve head and the control signal is supplied
cycle of the valve’s operation will exhaust either from a local closed loop control sensor or
proportionately more air than is necessary. switch; or from a PLC/machine controller via
The solution to this problem is from within a control bus – AS-Interface or DeviceNet – or
Burkert’s types 1066, 8631 and 8692 valve control multipole (parallel) directly into the valve.
heads ranges. Developed for use in the food, Similarly, adopting digital positioners
beverage and pharmaceutical industries, these with integral solenoid valve control heads for
units provide a decentralised method of opening regulating modulating process control valves will
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