Page 30 - Plastics News Issue December 2024

ENVIRONMENT NEWS
to expand the annual volume of plastic waste
processed via pyrolysis from 10,000 tons to
900,000 tons by 2030.
Currently, the kiln method is used in the Repub-
lic of Korea for the pyrolysis of waste plastics.
This process involves placing waste plastics
inside a cylindrical chamber, applying heat ex-
ternally, and condensing the resulting vapor to
produce pyrolysis oil. While the process design
is relatively simple, it faces scalability limitations,
as heat transfer from the exterior to the center
of the cylinder becomes increasingly difficult as
the size of the chamber increases.
The kiln method can process only up to 20 tons
of plastic per day, which falls far short of the
900,000 tons per year target set by the gov-
ernment for pyrolysis processing. Additionally,
the kiln method requires continuous external
heat supply and cannot operate continuously, as
the process must be paused to handle residual
waste before restarting. These limitations make
it inefficient for large-scale applications.
The research team developed a technology to
recycle waste plastics using a circulating fluid-
ized bed (CFB) process, overcoming the limita-
tions of conventional methods. The CFB process
is a technology in which heat carriers, such as
high-temperature sand, circulate to enable con-
tinuous heat transfer during reactions. For the
first time globally, the team successfully applied
the CFB process to the pyrolysis of waste plas-
tics, enabling both continuous operation and
scalability—key challenges of existing processes.
The core of the developed process lies in heat
circulation. In this system, catalyst particles heat- volumes of waste plastics while producing high-
ed in the combustion reactor are circulated to
the pyrolysis reactor, where they transfer heat
to facilitate the pyrolysis of waste plastics. After
transferring heat, the catalyst, now at a lower
30 PLASTICS NEWS
temperature, returns to the combustion reac-
tor along with the residual waste. The residual
waste is incinerated, generating heat to reheat
the catalyst. The reheated catalyst is then recir-
culated back to the pyrolysis reactor, maintain-
ing a continuous process of heat transfer and
pyrolysis.
By utilizing this process, a continuous opera-
tion is achievable as the cycle of raw material
input, heat supply, and residual waste treatment
is seamlessly maintained. Additionally, since the
catalyst moves freely within the reactor, heat
can be effectively transferred from the center to
the edges of the reactor, enabling scalability and
the development of larger systems.
The research team conducted pyrolysis experi-
ments on waste plastics using their process,
handling up to 100 kilograms per day. They con-
firmed that the process can pyrolyze not only
plastics but also solid recovered fuel (SRF) made
from household waste. When SRF was pro-
cessed, the yield was approximately 37%, which
is 1.2 times higher than conventional methods.
Additionally, the produced pyrolysis oil showed
a significant improvement in quality, with a 45%
content of light fractions, nearly doubling the
quality compared to existing processes.
Dr. Byungwook Hwang, the lead researcher,
stated, "The most significant achievement of
this study is the design and development of a
technology capable of continuously processing
waste, including plastic waste, through pyroly-
sis. This core pyrolysis technology is highly suit-
able for achieving Korea's waste plastic pyroly-
sis targets, as it enables the processing of large
quality pyrolysis oil."
Source: - Phys.org
December 2024