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Polyester recycling line for post-consumer and post-production waste
Matthias Schmitz M.Sc.
Product Manager Recycling Systems
BB Engineering GmbH, Remscheid/Germany
Polyester and its applications are omnipresent in our everyday lives. Whether as beverage bottles, film packaging, high-tech sports shirts or safety belts, polyester impresses with its excellent mechanical properties and efficient production. BB Engineering (BBE), joint venture of the Oerlikon Barmag and Brückner Group, has launched an interesting product on the market with VacuFil, which is intended to provide a solution for an almost waste-free polyester spinning process.
Demand for polyester rises constantly
However, the constantly rising demand for polyester and its various applications require responsible handling of global resources. All textile producers are under pressure to find sustainable solutions for the future. For this reason, it is not only ‘virgin polyester’ generated from crude oil that is exclusively the raw material for manufacturing, so too is polyester recycled from post-consumer and post-production waste. Processing production waste also helps cutting raw material, disposal and transport costs, hence increasing efficiency. As a side effect, CO2 emissions decrease significantly.
Additionally, to the already existing rPET spinning line VarioFil R+, which processes post-consumer bottle flakes into fibers, BB Engineering and Oerlikon Barmag introduced an innovative solution for the recycling of post-productionpolyester fiber waste, called VacuFil, at last year’s ITMA Barcelona.
Decades of experience
Decades of experience in the areas of extrusion, filtration and spinning systems have been bundled into a new, innovative core component – the vacuum filter Visco+. It unites gentle large-scale filtration and a swift intrinsic-viscosity build-up for consistently outstanding melt quality. The attached vacuum, which is regulated automatically from 1-30 mbar, removes volatile contamination, ensures a controlled IV-increase and furthermore achieves an ideal melt homogeneity, which is vital for the downstream spinning performance. Comprising an inline viscosity-measuring unit connected with the vacuum system, the IV can be adjusted continuously and reliably. Hence, producers are able to generate that specific kind of recycled polyester they need for their application. The excellent degasification performance additionally relieves energy-intensive pre-drying.
Modular structure opens numerous possibilities
The modular structure of the VacuFil range opens up numerous possibilities to process waste content. Bottle-flakes, agglomerated fiber-waste or a mixture of both can be used to produce first-class PET-granules or to feed downstream direct spinning positions as inline variant.
Expertise in screw design offers a gentle melt treatment
Figure 1 shows the typical VacuFil Visco+ process to upcycle production waste and feed it back into the PET main melt stream, coming from the continuous polycondensation. The PET waste is plasticized by a robust single screw degassing extruder (1), which is the first step among many for a gentle melt treatment, thanks to the expertise in screw design of more than 17.000 BBE extruders in operation.
The upcycling is done by multiple degassing and filtration steps, cleverly combined in and around the vacuum filter (5). Besides commonly used screen changers (3) for rough particles, state-of-the-art large area candle type filters (6) for fine filtration come into action, which are BBE’s core competence for decades now and will really make a difference for the customer’s spinning performance – bobbin for bobbin for bobbin.
Requested throughput ranges should be catered thanks to various system configurations
With the 3DD-mixer (7), a market-proven mixing technology by BB Engineering, producers can not only add sophisticated additives to the melt, but also change rPET-ratios from 5 to 50 % easily in the main melt stream in order to match legal standards. Customer requirements can be optimally catered for with various system configurations and hourly throughput ranging between 300 and 3000 kg.
The whole process is controlled and monitored by Oerlikon Barmag’s GUIDE system to guarantee the accustomed reliability.
VacuFil conquer the market worldwide thanks to reliable results derived from numerous customer trials
Since ITMA Barcelona, VacuFil has awakened huge interest in manufacturers of manmade fibers worldwide. Since then, numerous customers’ trials have been carried out in Remscheid on the fully developed pilot plant, with the effect that reliable results are now available which should allow the company to conquer the market. Customers have challenged the VacuFil technology with their own, authentic waste material. POY and FDY yarn has been spun successfully from 100% rPET-pellets. In times of the Corona Pandemic, BB Engineering offers digital video conferencing to continue providing access to this technology to a worldwide customer base.
