Researchers at the Korea Institute of Industrial Technology (KITECH) have developed a continuous pyrolysis system capable of processing one ton of waste plastic per day.
KITECH announced on the 5th that a research team led by Principal Researcher Shin Myung-chul of the Low Carbon Emission Control Research Division successfully implemented a process that continuously feeds waste plastic and recovers products without interruption.
Test results showed the pyrolysis oil produced meets quality standards for use as a raw material in industrial gear lubricants, demonstrating commercial viability.
Pyrolysis is a technology that decomposes carbon-containing organic materials at high temperatures in an oxygen-free environment to produce useful raw materials.
When waste plastic undergoes pyrolysis, vapor is generated and converted into pyrolysis oil, wax, and non-condensable gases through cooling and condensation processes.
The resulting pyrolysis oil can be converted into raw materials for various petrochemical products including plastics, drawing attention as a technology for recycling waste plastic resources.
However, pyrolysis oil produced by conventional systems has inconsistent quality.
Conventional pyrolysis facilities must halt operations to remove solid residue (pyrolysis char) that accumulates inside after processing raw materials, requiring reheating before the next cycle.
During the reheating process, sticky wax components (high-boiling-point oil) increase and can adhere to or clog equipment interiors.
Furthermore, the varying amounts of wax mixing with the oil cause fluctuations in viscosity and quality of the pyrolysis oil.
The research team solved these problems by building a continuous pyrolysis system that operates without stopping from raw material input through reaction to product recovery and refinement.
First, they developed a continuous discharge system combining a screw-type conveyor with special isolation valves at the bottom of the facility, enabling automatic discharge of pyrolysis char while preventing external air infiltration.
They also prevented wax adhesion by utilizing non-condensable gases generated during the process as a heat source to maintain consistent internal temperatures.
Additionally, the team applied staged cooling of vapors generated during pyrolysis to first separate and recover sticky wax components, then selectively collect high-purity pyrolysis oil.
The system was specifically designed to recycle byproducts generated during the pyrolysis process.
Pyrolysis char, previously disposed of in landfills, can now be continuously recovered and further processed into activated carbon or conductive carbon materials.
Non-condensable gases are reinjected as an energy source, achieving an energy-efficient process.
To explore high-value lubricant applications, the research team created a blended oil mixing pyrolysis oil and synthetic oil (poly-alpha-olefin) at a 50:50 ratio, then tested it against the KS M 2127 standard for commercial gear oil base oil specifications.
The results showed a viscosity index of 132, pour point of -16°C, and flash point of 204°C, meeting the physical property standards required for gear oil base oil.
"We confirmed that pyrolysis oil produced through continuous processing of waste plastic without interruption can be applied as base oil for gear oil," said Principal Researcher Shin Myung-chul of KITECH. "We plan to commercialize this through demonstration and follow-up research."
