Thermochemical recycling of complex polymers: General decomposition pathways for pyrolysis of end-of-life-tires
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Sustainable energy systems (MPSES), MSc
Publicerad
2024
Författare
Sköld, Adam
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
With an increasing population of the world, our reliance on tires in transportation and
production of goods is following suit. As tires are relying on fossil fuels to produce both
synthetic rubbers and the filler carbon black, recycling the material in end-of-life tires (ELTs)
and closing the carbon loop is of great importance for continuing the production of tires in a
sustainable fashion. Thermochemical conversion using pyrolysis is a viable option and has
been proven to be commercially viable as the company Scandinavian Enviro System has shown
by using the recovered carbon black in new tires, and the oils as feedstock to the petrochemical
industry. To be able to predict the results from pyrolysis of ELTs, understanding the process is
a must. In this work, the behaviour of the solid and volatile products was investigated using
prior experiments, literature review and followed by modelling, done using both an empirical
model as well as a simplified reactor model (SRM) using kinetics based radical reactions. The
empirical model investigated the feasibility of using key species, i.e. species providing
significant information about the process to be used in an implicit fashion to decrease the
complexity of both models and analysis in experiments. The solid behaviour indicates the
significance of how the particle is heated, as this dictates how if the particle is swelling or
shattering as the volatile compounds are leaving the material. The interaction between the solid
and volatile vapours leaving the sample was investigate further in a literature review, where
the influence of heating rate was shown to affect the amount of carbonisation in the solid yield,
where lower heating rates favoured carbonisation. The heating rate was also shown to influence
the secondary reactions as yields of aromatic content increase with heating rate at the expense
of aliphatic content, along with slightly higher gas production. The empirical model took
heating rate into account when predicting the carbon conversion to species in both the oil and
gas using a key specie. The models showed the promise of utilizing key species, while the
species chosen, ethylene and styrene, should be investigated further in future research. By
increasing the complexity in the simplified reactor model, additional insight regarding radical
rearrangement could be gleaned, however, significant focus should be put on the kinetic
parameters of the different reactions to create a more holistic decomposition model.
Beskrivning
Ämne/nyckelord
Tire pyrolysis , ELTs , Carbon black , Pyrolysis , Aromatic hydrocarbons , Empirical modelling