Fast-Pyrolysis Process Recovers Valuable Materials from Tires – Pyrolysis Process Recovers Tires - Arhive
Fast-Pyrolysis Process Recovers Valuable Materials from Tires Pyrolysis Process Recovers Tires
By Gerald Ondrey
Each year, more than 1 billion automobile tires are replaced worldwide. Together, the used tires contain 4.4 million metric tons of valuable products, such as carbon black, metals, fuels and chemicals.Pyrolysis Process Recovers Tires
In an effort to recover these materials, the University of Twente (Enschede, the Netherlands; www.utwente.nl) and Continental Reifen Deutschland GmbH (Hannover, Germany; www.continental-reiden.de) are developing a new fast pyrolysis process that decomposes used tires at high temperatures in a matter of seconds.
In the process (diagram), tires are first pretreated to remove metal, fibers and textiles, and the rubber is milled to centimeter-sized granules. A screw feeder continuously feeds rubber granulate to a flash-liquification reactor, operating at a temperature of around 500°C. With residence times of a few seconds, the rubber is converted into pyrolysis gas and solids, explains project leader Gerrit Brem, professor of Thermal Engineering at Twente. The solids are recovered by a cyclone and the gas is condensed into fuel oil and non-condensable fuel gas.
Although the product yield depends on the operating conditions, Brem estimates that a given feed yields about 35 wt.% carbon black, 20 wt.% gas and 45 wt.% condensable oil.
“Unique is our fast heat transfer, resulting in a fast process of seconds, while conventional pyrolysis needs hours to complete the process,” says Brem. “Because of the fast process, we expect — and have seen — a superior carbon black quality,” he says.
The project, partially funded by the Materials Innovations Institute (M2i), aims for a design for a pilot plant and an optimum window for the process conditions. The plan is to scale up the process to demonstration scale in a follow-up project, says Brem.
The fast pyrolysis process is also capable of converting other waste streams into valuable materials. Examples are the recovery of fuels and minerals from paper sludge, carbon fibers from waste composites, or glass fibers from dismantled boats or wind turbines.
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