Solar-assisted sorption-enhanced gasification of polyethylene terephthalate (PET) plastic waste - Experimentation and process modelling
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Journal Title
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School of Engineering |
Doctoral thesis (article-based)
| Defence date: 2024-08-23
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Author
Date
2024
Major/Subject
Mcode
Degree programme
Language
en
Pages
80 + app. 72
Series
Aalto University publication series DOCTORAL THESES, 165/2024
Abstract
Polyethylene terephthalate (PET) is a common plastic that has been widely used in packaging and textiles. In European Union countries, only 10% of PET plastic was recycled in a closed loop, and the remained was discarded in nature. Therefore, we proposed the solar-assisted sorptionenhanced gasification (SEG) to produce H2 and other materials from PET waste. This research aims to study the solar-assisted SEG of PET waste by experiments to obtain the optimized operating conditions, and then use them in Aspen Plus modelling to investigate the techno-economic performance of the system. This research was divided into four tasks: three experiments of PET steam gasification, PET steam gasification with CaO, and solar-assisted Ca looping process in bubbling fluidized beds, and the Aspen Plus modelling of SEG of PET integrated with a steam power plant and a LiBr-H2O absorption chiller to recover the excess heat in the process. Four journal papers were published accordingly to research tasks. Publication 1 revealed that gas yields increased significantly with the increasing temperatures, and the total tar yields dropped. The effect of temperature on gas products was more remarkable than steam-to-PET ratio and residence time. Carbon balance analysis showed that half of the carbon in PET was converted into tars, and CO2 was the dominant gas product. Publication 2 reported that adding CaO promoted H2 and CO2 yields and reduced tars, meaning that CaO mainly acted as a catalyst at the examined conditions at examined temperatures. Correlations between gas products and three operating parameters: temperature, CaO-to-PET ratio, and steam-to-PET ratio were fitted with the help of response surface methodology, and the gas yields were predicted well. Publication 3 studied the solarassisted Ca looping process and obtained the optimized combined temperatures of carbonation 650 °C and calcination 850 °C to minimize CaO deactivation and maximize the energy-carrying capacity, considering a reasonable mass flow rate between the solar calciner and the gasifier. Publication 4 discovered that the energy and exergy efficiencies of the integrated system were 60%–70% for both day and night modes. The annual production of H2 and benzene were 684 t and 6286 t, respectively, with an annual 19 kt of PET feedstock and capturing 21 kt of CO2. The project is feasible when the benzene price is greater than 1092 €/t and the CO2 prices are higher than 80 - 120 €/t. The results show that there is a potential to implement solar-assisted SEG of PET plastic waste to produce H2 and other valuable chemicals. This research provides a novel method for PET plastic waste upcycling sustainably with zero CO2 emission and a renewable heat source without burning additional fuels to achieve the zero plastic waste goal in the future.Description
Supervising professor
Järvinen, Mika, Prof., Aalto University, Department of Mechanical Engineering, FinlandThesis advisor
Vuorinen, Ville, Prof., Aalto University, Department of Mechanical Engineering, FinlandKeywords
PET, sorption-enhanced gasification, CO2 capture, hydrogen, solar heat, experiments, process simulation
Other note
Parts
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[Publication 1]: Li, Shouzhuang; Vela, Isabel Cañete; Järvinen, Mika; Seemann, Martin. 2021. Polyethylene terephthalate (PET) recycling via steam gasification–The effect of operating conditions on gas and tar composition. Elsevier. Waste Management, 130, 117-126. ISSN: 0956-053X.
DOI: 10.1016/j.wasman.2021.05.023 View at publisher
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[Publication 2]: Li, Shouzhuang; Inayat, Muddasser; Järvinen, Mika. 2023. Steam gasification of polyethylene terephthalate (PET) with CaO in a bubbling fluidized bed gasifier for enriching H2 in syngas with Response Surface Methodology (RSM). Elsevier. Applied Energy, 348, 121536. ISSN: 0306-2619.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202308114681DOI: 10.1016/j.apenergy.2023.121536 View at publisher
- [Publication 3]: Li, Shouzhuang; Tregambi, Claudio; Di Lauro, Francesca; Montagnaro, Fabio; Salatino, Piero; Järvinen, Mika; Solimene, Roberto. Tailoring solar-assisted calcium looping for polyethylene terephthalate (PET) steam gasification: combined effect of carbonation and calcination temperatures on process performance. Revised version submitted to the journal Applied Energy in the year 2024.
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[Publication 4]: Li, Shouzhuang; Laukkanen, Timo; Jiang, Dingyi; Vuorinen, Ville; Järvinen, Mika. 2024. AspenPlus-based techno-economic analysis of solar- assisted sorption-enhanced gasification for hydrogen and chemicals recovery from polyethylene terephthalate waste. Elsevier. Energy Conversion and Management, 306, 118318. ISSN: 0196-8904.
Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202403272933DOI: 10.1016/j.enconman. 2024.118318 View at publisher
