Sulzer will showcase its advanced devolatilisation (DEVO) technology for solvent-based recycling of plastic and selective polymer extraction at the K 2019 trade fair.
The system delivers high-quality materials of unprecedented purity, offering clear benefits when compared to conventional purification equipment. The technology also allows processing industries to identify recovery methods for waste that is currently not recyclable, supporting a circular economy for plastics.
Growing sustainability trends demand innovative plastic recycling solutions. Particularly promising methods include solvent-based recycling. Compared to chemical recycling, which converts plastic into monomers that are subsequently reacted together to produce new polymers, this new process has less stages, improving energy efficiency and material usage.
To successfully recycle end-of-life polymers using selective extraction, it is essential to remove solvents used during the extractive processes as well as any other impurity without degrading the end product. In this way, companies can deliver materials that have the same purity and quality as virgin plastics. These challenges have been a barrier to building a fully circular economy for plastic.
Sulzer Chemtech is offering its breakthrough DEVO technology to address these issues. The solution, initially created and commonly used for the purification of virgin plastic, enables recycling facilities to increase the quality of recycled polymers and the overall throughput, optimise their processes as well as develop innovative solvent-based polymer extraction routes and facilities.
Sulzer’s DEVO system consists of a static heat exchanging stage, followed by a vacuum flash devolatilisation chamber featuring Sulzer’s proprietary design. In this way, polymer solutions are heated and homogenised. Once in the devolatilisation vessel, the volatile chemicals are separated from the polymer melt, which is discharged from the bottom section of the chamber.
Sulzer’s engineers have designed each stage of this system to deliver optimal performance. Advanced mixers with heat exchanging capabilities, such as Sulzer’s SMR and SMXL products allow the polymer feed to increase its temperature in a rapid, homogeneous and highly controlled manner. As a result, it is possible to process thermally sensitive plastics without degrading them. Additionally, Sulzer’s static mixers allow companies to inject stripping agents, into the polymer feed, further contributing to the separation process.
Compared to extrusion-based solutions, which feature a number of moving parts, flash vessels are static pieces of equipment. Therefore, recycling facilities can benefit from low capital expenditure (CAPEX) and operating expenses (OPEX), as well as reduced maintenance activities associated with damages to and failure of moving components.
The process of heating and separating the polymer feed within Sulzer’s DEVO technology can be repeated, if necessary, to further reduce the volume of solvents and other volatile compounds in the polymeric product. At the end of a single- or multi-stage devolatilisation procedure, plastic recycling businesses can obtain polymers with residue contents below 50ppm.
To address specific applications and customer needs with a highly efficient solution, Sulzer conducts extensive simulations as well as laboratory and pilot field testing aimed at fine-tuning its devo technology for any intended application. These investigations have revealed innovative alternative solvent-based recycling processes, which might have been impractical with conventional heat exchangers and vacuum flash vessels. The result is that chemical processing industries have a new option to meet increasingly strict recycling rate targets.
Sulzer’s highly skilled engineers can also deliver complete process packages, which include solvent recovery units as well as mixers for plastic downstream activities. Once the units have been delivered, Sulzer offers commissioning support to help ensure a smooth installation and start-up of devo units. Therefore, businesses can benefit from a one-stop-shop for the development, manufacturing and installation of high-quality, tailor-made devolatilisation equipment.
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