Efficient COBRA filter revolutionises PET recycling

Rapidly rising recycling rates, fluctuating input qualities and high demands on product purity pose major challenges for recyclers—especially in filtration. BB Engineering GmbH is responding to this with an innovative filter system: the COBRA filter. This combines large-area fine filtration with inline cleaning and promises not only increased efficiency and low operating costs, but also noticeable cost reductions.

Speaking about the main motivation behind the development of the COBRA filter, Matthias Schmitz, head of engineering recycling technology at BB Engineering, said, “The filtration requirements in PET recycling are high. The input material is often heavily contaminated, but at the same time the quality of the end product must be right. Conventional filter systems quickly reach their limits – either they cannot achieve the necessary filtration fineness, or they are extremely maintenance intensive and complicated to handle. And yet filtration plays a key role in recycling. Our motivation was to develop a system that could overcome these challenges – efficiently, automatically and with as little waste of resources as possible.”

The system features dual filter inserts enabling continuous operation, with automatic switching and intermediate cleaning via BB Engineering’s ‘White Filter Cleaning’ (WFC) technology. Using only superheated steam, WFC avoids chemicals, prolongs filter life 3–5 times, and reduces operating costs. Cleaning is completed in 10 hours versus several days for pyrolysis or chemical cleaning.

COBRA ensures safer handling, minimal downtime, and reduced consumables, leading to major OPEX savings in personnel, energy, and materials. Its filtration quality improves downstream processes by reducing melt impurities, lowering energy use, and minimising production interruptions.

“Large-area filtration has the stigma of high costs, high maintenance and time-consuming conversion and cleaning work. This is why many producers shy away from large-area filters. However, they offer the best filtration performance, which is essential, especially with increasing rPET proportions. That is why we have created a large-area filter that precisely overcomes these known weaknesses. With its pleated filter cartridges, COBRA offers a filter area of up to 24 m² with a fineness of up to 20 μm. COBRA therefore filters more finely than screen changers or laser filters and can absorb a larger amount of contamination. This makes it perfect for recycling applications or other demanding filtrations tasks, such as synthetic fibre spinning and film production. In a filter test with rPET, the COBRA filter with 20 μm showed a filter pressure value of 1,5 bar/kg/cm², which corresponds to the quality of virgin material,” added Schmitz.

Talking about its advantages, Schmitz further said, “COBRA offers advantages in many respects. Operators do not have to handle molten liquids or hot components, and there is no need to spend time on changeovers and cleaning. Furthermore, the consumables and materials have a longer service life because they are cleaned gently, without aggressive chemicals or the extremely high temperatures of pyrolysis. The costs for chemicals and their disposal are eliminated. Ultimately, COBRA’s automation and intermediate cleaning lead to noticeable OPEX savings in terms of personnel, energy, materials, and parts. However, in our view, the biggest advantage is the significantly longer service life of the filter. Thanks to the intermediate cleaning cycles, the filter can remain in use approx. 3-5 times longer before it needs to be cleaned and inspected again. This means a significant increase in efficiency, especially in recycling, where service lives tend to be shorter rather than longer. This also applies to downstream processes.”

Though developed for PET recycling, COBRA is suitable for plastic spinning, technical plastics processing, and can be retrofitted into existing plants. Schmitz sees advanced filtration as critical for achieving high recycled content targets within a circular economy framework.

“Filtration already plays a key role in recycling and will become even more critical if we want to achieve really high recycled content in high quality products. To do this, filters have to perform well under high levels of contamination while remaining efficient. What’s more, sustainability doesn’t just start with the product, but with the process design. I believe that solutions such as COBRA help to ensure that recycling remains economical, becomes more efficient and becomes even more widespread in industrial applications,” Schmitz said.

BB Engineering will showcase COBRA at the K Show in Dusseldorf this October and at ITMA Asia in Singapore.

ALCHEMPro News Desk (KD)