(Photo credit: Gneuss Kunststofftechnik)

Melt Filtration Technology

Gneuss Kunststofftechnik: Efficiency increase in PET-recycling by retrofitting existing melt filter

| Recycling technology | Gneuss Kunststofftechnik | Bad Oeynhausen | Germany

Spanish PET bottle-to-bottle recycler sees major efficiency improvements by replacing melt filter - against a background of government rules prescribing the proportion of recycled polymer, the plastics strategy of the EU and the commitment of many market leaders to responsible use of polymers, the conversion or modification of extrusion lines represents an important trend. The German manufacturer of Filtration Systems, Gneuss, has seen a surge of interest among customers looking to retrofit their extrusion lines, despite the Covid-19 Crisis.

The expectations that Nosoplas placed on the retrofit with a Gneuss Rotary Filter have been completely fulfilled. Immediately after commissioning the units, a drastic reduction in in material loss due to back flushing was observed and, at the same time, the quality of the rPET granulate produced was noticeably improved.

RSFgenius back flushing filters as optimum retrofit solution for PET bottle flake recycling

The processing of PET Bottle Flakes presents particular challenges for Melt Filtration Systems. On the one hand, the post-consumer material source typically has a relatively high contamination level, on the other hand, the quality requirements (fine filtration) are very high – especially when the material is to be put back into transparent bottles for beverages.

In order that the filter elements do not need to be constantly changed by hand, the ideal Melt Filtration System should be self-cleaning. Typically, the principle of back flushing is used. A proportion of the melt flow is diverted so that it flows in the reverse direction across filter elements which are not in use in order to wash the contamination out. The cleaning efficiency of the back-flushing and the quantity of material needed for back flushing vary greatly between the different systems available on the market.

With the Gneuss RSFgenius Melt Filtration System, the high pressure sequential cleaning system ensures that the filter elements are completely cleaned with the absolute minimum of polymer.

Nosoplas in Spain decided in favour of the RSFgenius Rotary Filtration System due to the high efficiency and the fast return on investment which it offers. Nosoplas manufactures bottle grade pellets (chip) from PET bottle flake. The pellets (chip) are supplied to other companies, where they are injection moulded to pre-forms which are later blown into high quality bottles for beverages.

Nosoplas decided to replace their existing, conventional filtration system due to problems with back flushing and high polymer losses. They replaced this conventional system with a Gneuss RSFgenius 175 for a throughput of 1.500 kg/h and a filtration fineness of 56 µm. In fact, the customer is even able to operate with 30 µm for special products. And this all with a constant, steady melt pressure, minimal losses due to back flushing and without any production variations, even during replacement of the filter elements.