Modelling the chemical recycling of plastic waste via pyrolysis and analysing integration with existing refinery infrastructure
(2023) KETM05 20231Chemical Engineering (M.Sc.Eng.)
- Abstract
- Current plastic management is unsustainable as large amounts of plastic end up landfilled or in the ocean, necessitating an expansion of waste management infrastructure. Pyrolysis is a viable chemical recycling option, and in this report a pyrolysis model is constructed in Aspen Plus. The model is a stoichiometric pre-sorted polyethylene feed and is based on experimental pyrolysis results. Products from the model include 19.6% production of LPG gas and 28% of fuels such as gasoline, kerosene and diesel. Char production was estimated to 9.5% and dechlorination achieved sufficient results with the addition of calcium oxide to the pyrolysis. Energy demands were estimated to be 1.77 GJ/hour for hot utility and 0.556 GJ/ hour for cold utility.... (More)
- Current plastic management is unsustainable as large amounts of plastic end up landfilled or in the ocean, necessitating an expansion of waste management infrastructure. Pyrolysis is a viable chemical recycling option, and in this report a pyrolysis model is constructed in Aspen Plus. The model is a stoichiometric pre-sorted polyethylene feed and is based on experimental pyrolysis results. Products from the model include 19.6% production of LPG gas and 28% of fuels such as gasoline, kerosene and diesel. Char production was estimated to 9.5% and dechlorination achieved sufficient results with the addition of calcium oxide to the pyrolysis. Energy demands were estimated to be 1.77 GJ/hour for hot utility and 0.556 GJ/ hour for cold utility. A techno-economic analysis approximated capital costs to $13.5 million and annual net profits of $3.8 million annually, resulting in a payback time of 3.6 years. Finally integration opportunities with existing refinery infrastructure were investigated, showing that integration is feasible. (Less)
- Popular Abstract
- After modelling chemical waste recycling, results showed that large amounts of fuel were among the products. Because of this, pyrolysis is viable as a method of chemical recycling and can be used as an alternative to help reduce the amount of plastic polluting the environment. Fuels produced from recycling plastic can be sold to make the recycling profitable, and in roughly 3,5 years the initial investments will have been repaid. Furthermore, chemical waste recycling is more versatile than current mechanical recycling methods and can process waste that is contaminated.
Current handling of plastics demands an expansion of waste management infrastructure to reach sustainable usage of plastics. Annually, 8 million tonnes of plastics... (More) - After modelling chemical waste recycling, results showed that large amounts of fuel were among the products. Because of this, pyrolysis is viable as a method of chemical recycling and can be used as an alternative to help reduce the amount of plastic polluting the environment. Fuels produced from recycling plastic can be sold to make the recycling profitable, and in roughly 3,5 years the initial investments will have been repaid. Furthermore, chemical waste recycling is more versatile than current mechanical recycling methods and can process waste that is contaminated.
Current handling of plastics demands an expansion of waste management infrastructure to reach sustainable usage of plastics. Annually, 8 million tonnes of plastics enters the ocean, further increasing the environmental pollution. This is equal to dumping a garbage truck full of plastic into the ocean every minute and if the trend continues, there will be more plastic than fish in the ocean by 2050. Clearly we need to increase plastic recycling to avoid reaching this point. A large issue with current recycling infrastructure is that it requires plastic to be sorted before being recycled. Chemical recycling has the advantage of being able to process mixed plastics. The reason for this is because instead of melting the plastic and turning it into a new product, chemical methods break down the plastic into fuels and valuable chemicals. Pyrolysis does this by heating the plastic without oxygen, causing the plastic to break down into chemical components that can be turned into fuels. Essentially, the whole process can therefore be seen as a massive oven that turns plastic into something useful. The process is profitable, and investment costs can be reduced further by using equipment from the oil refinery industry. This essentially works because in both cases fuels are produced and the chemicals from the chemical recycling are similar to ones used in oil refineries.
Limitations to the process do exist practically. High amounts of PVC plastic will be harmful to the process due to toxic chlorine gas being released when the plastic is heated. Another plastic that will hurt the recycling process is PET plastic due to the plastic clogging equipment. Therefore, these plastics should not be present in large quantities. Various toxic chemicals are also produced during the pyrolysis process. Most are fine to include in fuels as they later are burned in engines and form carbon dioxide and water, however care should be taken to make sure toxic pollutants are not leaking out of the process as gases. In the thesis work, computer simulations were made on a pyrolysis process and results showed the quantity of fuel production, energy demands, and potential profits, all of which can be useful as estimations for any global actors looking to build a pyrolysis plant. In a broader sense, the work contributes to improving recycling and creating a more sustainable future. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9136606
- author
- Dahl, Simon LU
- supervisor
- organization
- course
- KETM05 20231
- year
- 2023
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Pyrolysis, Recycling, Integration, Modelling, Simulation, Techno-economic, Plastic, Chemical engineering
- language
- English
- id
- 9136606
- date added to LUP
- 2023-09-26 09:56:57
- date last changed
- 2023-09-26 09:56:57
@misc{9136606,
abstract = {{Current plastic management is unsustainable as large amounts of plastic end up landfilled or in the ocean, necessitating an expansion of waste management infrastructure. Pyrolysis is a viable chemical recycling option, and in this report a pyrolysis model is constructed in Aspen Plus. The model is a stoichiometric pre-sorted polyethylene feed and is based on experimental pyrolysis results. Products from the model include 19.6% production of LPG gas and 28% of fuels such as gasoline, kerosene and diesel. Char production was estimated to 9.5% and dechlorination achieved sufficient results with the addition of calcium oxide to the pyrolysis. Energy demands were estimated to be 1.77 GJ/hour for hot utility and 0.556 GJ/ hour for cold utility. A techno-economic analysis approximated capital costs to $13.5 million and annual net profits of $3.8 million annually, resulting in a payback time of 3.6 years. Finally integration opportunities with existing refinery infrastructure were investigated, showing that integration is feasible.}},
author = {{Dahl, Simon}},
language = {{eng}},
note = {{Student Paper}},
title = {{Modelling the chemical recycling of plastic waste via pyrolysis and analysing integration with existing refinery infrastructure}},
year = {{2023}},
}