Rotary Filtration Systems for Large Scale Applications

A process-constant Filtration System type RSFgenius 330 will replace a duplex candle filter in a line for the production of PVC film (interlayer for laminated glass). The operation of the RSFgenius 330 will ensure that the process disturbances, which had hitherto been a problem when switching from one candle filter to the other prior to filter changes are completely avoided, in addition to the costs for dismantling, handling and cleaning the candle filter elements. An additional important advantage in the processing of this high viscosity material is the absolute pressure stability ensured by the Rotary Filtration System which guarantees a constant film thickness. The RSFgenius, with its Rotary Filtration System in this case is characterised by a filtration area of 1,900cm2 and operates with a filtration fineness of 56μm. The throughput rate is 2,800kg/h. When increasing the number of recycling lines from 3 to 4, a major French manufacture of recycled PET bottle grade chip/pellets from post consumer PET bottles once more selected the Rotary Filtration System. The RSFgenius Filtration Systems already in operation at this customer have a filtration area of 590cm2 and operate with a throughput rate of 1,500kg/h and a filtration fineness of 56 microns. The trademark characteristic of the Rotary Filtration Systems is the disc, which rotates between the inlet and outlet blocks and which is equipped with a set of filter elements, located in a ring pattern around the disc. The polymer melt flows across the filter surface, leaving the contamination on the filter elements. As a result, the pressure differential increases slightly and the control system reacts immediately, rotating the disc by approximately 1° angle at a time. In this way, contaminated filter area is indexed out of the melt channel and clean area is introduced at the same time. Additionally, the RSFgenius is equipped with an integrated high pressure sequential self cleaning system which ensures complete cleaning of the filter elements. Depending on the filtration fineness, the filter elements can be used as many as 400 times, which in this case results in an interval between filter element changes (which can be carried out without disturbing the process) of approximately 2 months. All the Gneuss Melt Filtration Systems operate “gneussconstant” – in other words, they operate fully automatically and ensure pressure and process constant production at all times. They are available in a range of different model sizes with filtration areas from 25cm2 up to 17,400cm2 for throughput rates from 190 to 32,000 kg/h. A manufacturer of cable compounds for high Voltage cables (> 2,500kV) from LDPE and which are cross linked in a second processing step needed a flow optimised melt channel design and extremely fine filtration (20μm). The manufacturer selected the KSF Melt Filtration System, designed so that the screws of the twin screw extruder reached to within 10mm of the filter elements. In this way, the high viscosity material is agitated through the inlet block, the residence time spectrum is kept narrow, the polymer flow is fast and streamlined.