Problem solving

Quality and hygiene in food processing

At "Dr. Oetker" in Bielefeld

Central extraction plant for a clean work place

A centralized extraction plant is often a much more effective investment than a series of standard industrial vacuums. A good example of this is the new extraction plant just installed in the Oerlinghausen production facility of food processor August Oetker Nahrungsmittel KG.

Here, the company packs baking powder, cake mixes and other powdery products in large quantities. The formation of potentially explosive powder mixes is inevitable feature of the production process. At Dr. Oetker some cleaning is done with vacuum equipment and in some cases with compressed air. Large machine surfaces, for example, are simply blown off with compressed air. Unfortunately this method does not completely remove all the powder dusts. A feasibility study showed that the use of vacuum extraction plant throughout the production facility would be the best possible solution to the company's cleaning needs. At the same time, a staggered cleaning schedule was recommended in order to keep extractor performance and running costs to within limits. Company management had its reservations about these limitations. Line employees take the cleanness of their machines very seriously and this is an attitude which the company wants to encourage rather limit with time constraints .

Together with Ruwac Industrie-Sauger GmbH, Dr. Oetker developed a cleaning system design which was cost-effective without placing any time constraints on when and where machine operators could do their cleaning. The central part of the system is a fixed extraction unit. There are forty cleaning points on packing line machines. Each of these has a connection for an suction hose. When the machine operator connects the 5 metre long hose to the connector, the extraction unit switches on automatically and cleaning can proceed immediately. In comparison with conventional industrial vacuums, this system has the advantage that it saves space at each workstation. No space is taken up at the workstations for the filtration and disposal equipment which is installed elsewhere at a central location.

Energy-saving features include the drive layout and design. Six identical vacuums, with individual power ratings of 7.5 kW, switch on and off as required depending on how many cleaning stations are currently active. The vacuum units are connected to a central filter housing which contains two bag filters; each bag filter has a surface filtering area of 11 m². The dust trapped by the filters is collected and disposed of in big-bags. Broken or unbaked product is rapidly removed at the outfeed by two switchable vibrators.

The entire extraction plant is controlled by a PLC. The PLC triggers automatic filter dedusting. When the differential pressure inside the bag filter reaches a programmed value, the filter is dedusted by a counter-current of compressed air blowing from the clean gas side. Any dust held in the filter is thus dislodged and drops down into the collection bin. Dedusting can take place on-line, i.e. while the line is operating.

Together with the central extraction unit, Ruwac also delivered a mobile extraction unit. This is used to remove surplus product from product magazines when the product type is changed over on mixing and filling machines. The vacuum can be flanged straight onto the magazine outfeed. A high-pressure fan driven by a 5.3 kW motor creates the necessary suction power of 2,000 m³/h (max.) and a vacuum of 10.050 Pa. This system ensures that no powder gets into the surrounding area when the magazines are being cleaned at product changeover. Dr. Oetker is fully satisfied with the performance of both these units. Dr. Oetker production sites elsewhere also make wide use of fixed and mobile vacuums and extractors from Ruwac.