Decentralised pneumatic valves save money and boost quality

GB Glace, part of the Unilever Group, has 300 employees at its site in Flen, Sweden. This is just one of its 10 European ice cream production sites and here it produces approximately 45million litres of ice cream each year. Production is subject to strict hygiene regulations, and cost reductions are an important factor. With the conversion to Bosch Rexroth CL03 Clean Line series pneumatic valves with integrated Profibus communications, GB Glace has achieved significant savings in materials, energy, installation and labour costs, as well as improving its process reliability.

Small technical details are important in ice cream production, as GB Glace's secrets involve quantities, ingredients and mixture ratios. One example of a small but important technical detail is the conversion from traditional pneumatics to modern valve technology with fieldbus communications. Karleric Idegren, a process project engineer at GB Glace in Flen, comments: "Since its installation in 1989, our previous technology served us very well. However, we were forced to realise that maintenance-related spare parts were no longer available on the market. Our initial idea was to search for adequate replacements for the components. This ultimately gave rise to a new pneumatic actuation concept. Rexroth presented a design and that is what we are now using with great success."

Rexroth CL03 series valve terminals are at the heart of the new system. The valves feature a consistent hygiene concept that is certified by the European Hygienic Engineering and Design Group, protected to IP69K and has a bus connection that is directly integrated in the valve terminal system. Idegren adds: "If we had merely replaced the components in the existing system, the investment for their installation alone would have cost five times more than our current, more modern and technologically advanced solution."

Valve features

CL03 valves are easy to clean and maintain. Individual base plates with internal wiring can be populated with up to 16 valves. The individual valves, in turn, can be set for two different pressures, so actuators can be operated so as to deliver the requisite force.

GB Glace replaced the previously installed pilot valves with new 2x3/2-way solenoid valves that now provide more functions to actuate the 51 process valves on the mixing tanks. GB Glace's overall system uses approximately 400 valve functions. With a total of 38 functions, two ramps actuate the valves at the cream tanks.

Due to the decentralised configuration of the pneumatic system (all valves are close to the actuators) there is no need for traditional cabinets for valves and Profibus connections.

Idegren states: "We have now also started the conversion of the pneumatic system on the mix storage tanks, where approximately 330 functions will be available for process valves on completion. In this area of the system alone, the new solution with integrated Profibus eliminates 14 control cabinets, including their wiring. This facilitates our work enormously.

"We have now eliminated 400m of air hoses and three ramps, so that 25 per cent of cost reductions can be attributed to components that are no longer necessary, including their installation."

Process efficiencies

These figures provide impressive evidence as to the savings potential of an intelligent solution. Idegren adds: "And this does not even factor in the process improvements we have achieved," referring to the further advantage of greater system efficiency. Fewer cables mean less dead volume and pressure loss - and, therefore, lower air consumption and less expenditure in relation to the prevention of potential infiltration of bacteria.

Idegren says: "The new system demonstrates a clear functional improvement; it is simpler and more economical. The mixing tank system now operates more efficiently and reliably than it did before. In addition, the lower investment also shortens the amortisation period."

These advantages are based on a series of detailed equipment improvements, including inductive sensors to monitor the status of the control valves; whereas the older pilot valves needed ten seconds from end stop to end stop, today's solenoid valves accomplish this in just three seconds. The sensors verify whether the valves have closed in the allotted time and a notification alerts employees if that window is exceeded. Idegren says of the new features: "It increases safety, reliability and profitability, since a defective component in the final manufacturing phase, for example, can spoil up to 5000 litres of finished ice cream."

All of these facts demonstrate the savings in effort and money that users can achieve by selecting a high-intelligence concept. And this is without taking into account the improvements that GB Glace has been able to make to the process itself. Idegren is also pleased with the increased efficiency that has been attained through less pneumatic piping, less dead space, lower pressure losses and reduced air consumption: "The new system achieves functional improvements and is simpler in its design. The system works more efficiently and reliably than ever before. What is more, reduced installation work - and especially the lower investment costs - shorten the amortisation period."

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