PROCESSING | MELT FILTRATION
Right: Nordson installed
candle filters to upgrade a BKG POLY melt filter for PET at Köksan in Turkey
screenchanger, which comprised eight flat screens supported by a breaker plate. The optimised retrofit replaced these with a new design carrying multiple filter candles, increasing the filtration area by a factor or more than 10. According to the company, the
upgraded screenchanger extends filter life by between four to eight times while reducing the number of black specks and gels and lowering shear stress. The latter benefit also extends melt pump life. “Lower delta pressure across the filter, achieved with Nordson’s POLY candle filter design even at 120 % capacity production, results in long life for the polymer pumps and its mechani- cal seals,” according to Peter Thomas, General Manager for PET Resin at Köksan. The ability to operate the unit with flat screens during start-up and shutdown is also said to be a benefit.
D S O N
Below: 3D model of a screen fitted above the support plate for CFD calculation at Coperion
Taking on change Parkinson Technologies has been offering the KCH continuous belt screen changer in its Key Filters range for several years. “The KCH set itself apart in the marketplace with its innovative hydraulic puller action allowing it to react rapidly to disruptions caused by varying contaminant levels,” says Marketing Manager Brian Lundgren. Since the 2012 launch of the original KCH,
Lundgren says Parkinson Technologies has been making refinements as well releasing new options – such as its “spent screen shear” and ScreenLync technology – focused on increasing reliability and efficiency. “Parkinson saw a growing need in the compounding market for a way to decrease downtime when making a material, grade, or colour change,” he says. In such applications, Lundgren says there is a need to limit cross contamination, which in many cases requires replacement of the breaker plate and/or filtration screen. The result is what he says is an innovative
quick-change breaker plate, the
KCH-SB. This has been engineered to drastically reduce the amount of time it takes to replace a breaker plate and introduce a fresh clean screen into the process. “The breaker plate’s
48 COMPOUNDING WORLD | July 2018
unique design allows rapid change out of the breaker plate in under five minutes, which normally could take up to four hours in downtime,” Lundgren says. Without the use of tools, the clean breaker plate is actuated into position while pushing the contaminated
breaker plate out of the melt stream. A hydraulic
puller (featured on all KCH models) then
allows the operator to pull fresh clean screen into the melt stream in a matter of minutes.
Simulation solutions At Coperion, R&D Head Markus Schmudde says the company is concentrating on improving its simulation models for material flow. “The pressure drop in the discharge equipment can be critical to the whole extrusion process,” he says. “Melt filters are still a bit tricky to simulate, due to multiple flow channels within the screen changer and the mesh itself. Especially in the screen area, elongational flow has to be considered. Simulating that elonga- tional flow is challenging, and good material data is needed to set up the right simulation model.” Coperion uses CFD methods to investigate the smallest details of its SWZ screen pack changer – in- cluding the screen layers. The company says that modelling and calculating the individual screen layers enables targeted optimisation of the compo- nents. It compiles a pressure loss evaluation for every single screen layer by simulating the actual screen geometries. “This enables Coperion to precisely calculate changes to the pressure loss caused by changing the mesh width or wire diameter,” says Schmudde. “Considering main flows and cross flows when designing the screen changer enables Coperion to achieve minimum pressure loss.”
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.fimic.it �
www.cofit.com �
www.bdplast.com �
www.ettlinger.com �
www.psi-polymersystems.com �
www.adgs.net (ADG Solutions) �
www.erema.com �
www.gneuss.com �
www.nordsonpolymerprocessing.com �
www.parkinsontechnologies.com �
www.coperion.com
www.compoundingworld.com
PHOTO: COPERION
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