Extrusion International 6-2025

59 Extrusion International 6/2025 use pleated lter cartridges in two lter inserts so that COBRA can produce non-stop. Switching between the two lter inserts is automated, as is inline intermediate cleaning. While one lter insert is in production, the other insert is cleaned. The whole system is closed and runs without manual intervention or cleaning chemi- cals. Our ‘White Filter Cleaning’ technology works ex- clusively with superheated steam and restores the lter cartridges to an operational condition. This extends the service life of the lter many times over and protects the materials. In summary, our COBRA lter achieves signif - icant ef ciency gains through integrated intermediate cleaning, requires only minimal operating effort thanks to automation, and is very safe in terms of both process stability and handling. There are many exciting aspects to this. Let’s rst return to the topic of ltration itself. COBRA is a large- area ne lter with cartridges. Why do you use this particular method and how effective is the ltration? Schmitz: Large-area ltration has the stigma of high costs, high maintenance and time-consuming conver- sion and cleaning work. This is why many producers shy away from large-area lters. However, they offer the best ltration performance, which is essential, especially with increasing rPET pro- portions. That is why we have created a large-area l - ter that precisely overcomes these known weaknesses. With its pleated lter cartridges, COBRA offers a lter area of up to 24 mÇ with a neness of up to 20 μm. COBRA therefore lters more nely than screen changers or laser lters and can absorb a larger amount of contamination. This makes it perfect for recycling ap- plications or other demanding ltrations tasks, such as synthetic bre spinning and lm production. In a lter test with rPET, the COBRA lter with 20 μm showed a l - ter pressure value of 1,5 bar/kg/cm2, which corresponds to the quality of virgin material. Your approach to the high operating costs associated with changeover and cleaning is the intermediate inline cleaning. How exactly does it work? Schmitz: We have been offering our White Filter Cleaning (WFC) lter cleaning system as a standalone solution for several years now. This intermediate clean- ing of lter inserts does not require any chemicals and uses only superheated steam. This protects the compo- nents, is more cost-effective and also signi cantly safer for operators and, of course, for the environment. The WFC system is now fully integrated into the COBRA and can therefore be used as a closed system with ltration to its full advantage. The lter control system signals when intermediate cleaning is required, switches pro- duction to the second lter insert and initiates cleaning. The lter insert remains in the lter and is automatically drained and then repeatedly exposed to superheated water vapour in several hundred cycles until it is ready for operation again. The cleaning process takes only 10 hours, whereas pyrolysis and chemical cleaning re- quire several days. What advantages does this offer producers? Schmitz: 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 consum- ables 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. Ul- timately, COBRA’s automation and intermediate clean- ing lead to noticeable OPEX savings in terms of person- nel, energy, materials, and parts. However, in our view, the biggest advantage is the signi cantly longer service life of the lter. Thanks to the intermediate cleaning cy - cles, the lter can remain in use approx. 3 to 5 times lon - ger before it needs to be cleaned and inspected again. This means a signi cant increase in ef ciency, especially in recycling, where service lives tend to be shorter rather than longer. This also applies to downstream processes. To the downstream processes – in what respect? Schmitz: The high ltration performance of the CO - BRA lter makes the melt so clean that downstream cleaning steps are signi cantly reduced or even elimi - nated. This saves time, material, and energy. In addi- tion, there are fewer interruptions in the production chain due to residual particles in the melt. This is a de- cisive advantage, especially in demanding applications such as the packaging or textile industry. Are there any applications beyond PET recycling? Schmitz: De nitely. Although the COBRA lter was developed with a focus on PET recycling, its modular de- sign means it can also be used in other areas – such as plastic spinning or the processing of technical plastics. Wherever high-purity melt is required, and contami- nation is to be expected, COBRA can demonstrate ist strengths, even as a retro t solution in existing plants. Rendering of the new COBRA lter from BB Engineering