The Icing on the Ice Cream

The makers of Magnum ice cream wanted to maintain their high-volume production levels, but at the same time reduce their compressed air consumption. However, part of the problem was not knowing just what that consumption was.

Until Festo were involved, Unilever had never known how much compressed air any one of their Magnum production lines consumed. However, with each of the five lines at the Heppenheim, Germany plant extruding one Magnum core per second, and over 20,000 of the ice creams on a stick being produced every hour, the guess was that consumption would be high.

Electricity and compressed air play an important role in the Magnum production process, for everything from mixing and extruding the ingredients (milk, chocolate, sugar and vanilla beans), to deep-freezing to -25°C, dipping in chocolate, and final packaging. But without knowing how much compressed air was being used, it was difficult to know where and how to make savings.

So Unilever and Festo began working together to produce a prototype energy-efficiency compressed air module that could not only measure but also help reduce consumption.

Invisible consumption

Highly aware of the need to cut their energy use, Unilever have a Sustainable Living plan in place which – since 2008 – has saved more than 150 million euros in energy costs across the global business, through efficiency improvements in the production process.

Initiatives at the Heppenheim plant have included replacing energy-intensive geared motors with more efficient models (reducing energy use by 60%), and installing frequency converters with variable torque loads for the 18kW ventilators in the cooling tunnels – eliminating continuous operation and cutting energy consumption by around 40%.

However the difference between these areas and compressed air, is that: “Air is not visible, so it is not immediately obvious if consumption is too high”, as Alexander Hemmerich – Automation Engineer at Heppenheim – pointed out.

So an essential part of the specification for any Festo solution was to make information on compressed air usage fully visible.

Coldly calculated

Festo and Unilever collaborated closely on developing the first prototype of the Festo MSE 6-E2M energy efficiency module.

Unilever’s requirements were for a device which can be incorporated into new systems and retrofitted into existing systems, not only to automatically regulate the compressed air supply but also to measure leaks and provide a continuous stream of process-relevant data.

The first version of the module, field-tested at Heppenheim, proved highly effective, but the final production model has been improved to incorporate a Profibus interface for reporting, a pressure and flow sensor, shut-off valve and fieldbus node – and all in the smallest possible footprint (around half the size of the prototype).

Energy freeze

With the help of the MSE 6-E2M energy-efficiency module, Unilever have achieved significant compressed air and energy use reductions.

The module incorporates on-board intelligence – similar to the start-stop system in a car – which, when it detects a standby mode in the equipment it’s supplying, automatically shuts off the compressed air supply. This has the additional benefit of making it possible to see how quickly the system empties when individual consumers are switched off, making it easier to locate leaks.

The MSE 6-E2M reports immediately to the system controller if there is an unusually fast drop in pressure. It also reports continually on flow, pressure and consumption – in effect making compressed air visible.

Although the module offers full automation, Unilever opted to operate the MSE 6-E2M via the system controller, to enable all information to be merged centrally.

Alexander Hemmerich describes the results: “We’ve been able to reduce compressed air consumption on the Magnum production system step by step, with the energy efficiency module from Festo. And the Profibus connection has the advantage that we didn’t have to add any more cables when converting our existing systems”.

Converted into cold, hard cash, the Festo MSE 6-E2M energy-efficiency module saved Unilever more than 500€ per annum on one production line alone. Which for the makers of Magnum ice creams, is energy efficiency that can’t be licked.