Tandem - filtration ensures quality of PET film |
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Kreyenborg convinces Asian producer of food grade packaging with the technically challenging solution of a tandem-filtration. In films for food grade packaging bad spots or other impurities have to be excluded.
For that purpose a fine filtration is required, which has been recently delivered by Kreyenborg GmbH, Münster as a tandem configuration for the PET flat film line of a Southeast Asian producer of food grade packaging. In this configuration both twin screw extruders, which are used in the coextrusion line, are equipped with two screen changers which are installed in tandem. In this tandem arrangement the first filter with a filter fineness of 200 ?m provides for the removal of coarse impurities, whilst the second filter with a filter fineness of 40 ?m undertakes the fine filtration. The intermediate Kreyenborg melt pump provides for a constant volume flow and the pressure build-up for the fine filtration. The diverter valves directly downstream the extruders come into operation during the start-up of the line as well as in case of failures. The requirements concerning the process and the quality of the end product call for a large filtration area and high process constancy. Hence the Kreyenborg piston screen changer K-SWE-4K-75 has been applied. This type of filter with four screen cavities and an active filtration area of 75% during screen change has also established in the field of Polymer production, compounding and recycling. It convinces by its patented technology and a very favourable price-performance ratio. In the delivered line the main extruder for the midlayer (performance 3.200 kg/h of virgin material, production waste, recycling material) is equipped with two K-SWE-4K-75, the co-extruder for the outer layers (performance 600 kg/h of virgin material) with two K-SWE, in each case as tandem design with Kreyenborg melt pump. |
