| 1. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Feedstock recycling of cable plastic residue via steam cracking on an industrial-scale fluidized bed
- 2024
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Ingår i: Fuel. - 0016-2361. ; 355
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Tidskriftsartikel (refereegranskat)abstract
- The use of plastic materials in a circular way requires a technology that can treat any plastic waste and produce the same quality of product as the original. Cable plastic residue from metal recycling of electric wires is composed of cross-linked polyethene (XLPE) and PVC, which is a mixture that cannot be mechanically recycled today. Through thermochemical processes, polymer chains are broken into syngas and monomers, which can be further used in the chemical industry. However, feedstock recycling of such a mixture (XLPE, PVC) has been scarcely studied on an industrial scale. Here, the steam cracking of cable plastic was studied in an industrial fluidised bed, aiming to convert cable plastics into valuable products. Two process temperatures were tested: 730 °C and 800 °C. The results show that the products consist of 27–31 wt% ethylene and propylene, 5–16% wt.% other linear hydrocarbons, and more than 10 wt% benzene. Therefore, 40%–60% of the products are high-value chemicals that could be recovered via steam cracking of cable plastic.
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| 2. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Thermochemical recycling of tall oil pitch in a dual fluidized bed
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 340
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Tidskriftsartikel (refereegranskat)abstract
- Crude tall oil is a by-product obtained from the manufacture of chemical wood pulp. The residue obtained after the distillation of this product is known as tall oil pitch (TOP). This complex fraction is a highly viscous liquid that consists mainly of free fatty acids, fatty acids derivatives, rosin acids and additives. Given its complex composition, it is commonly used as fuel for heat production. In this work, steam cracking is proposed as an alternative treatment for this residue. Steam cracking can convert TOP into a valuable product gas that can be used in different applications including the production of green chemicals, moving towards a carbon circular economy. The experimental tests were performed in the Chalmers pilot scale Dual Fluidized Bed, consisting of a steam cracker and a combustor. For these experiments, the thermochemical decomposition of 150–175 kg/h TOP was performed at the steam cracker at two different temperatures (775 and 825 °C) to evaluate the influence of this parameter on the obtained products. Wood pellets were also tested as reference material for the highest temperature. The distribution of the obtained products was analysed. Results show that TOP can be regarded as a by-product instead of a residue and used as feedstock for the recovery of chemical building blocks and syngas via thermochemical recycling. Between 40 and 50 % of the carbon present in the fuel is kept in the permanent gases, while about 20 % is in aromatic hydrocarbons. Compared to biomass, the aromatics yield obtained for TOP is much higher (190 g/kg for TOP and 13 g/kg for biomass). Among the species found, benzene, toluene and xylene, represent between 62 and 72 % of the total measured aromatics. Regarding the gas fraction, the production of valuable light hydrocarbons (such as ethylene and propylene) is more pronounced in the TOP residue than in the biomass. In addition, an energy balance over the system was estimated and showed that TOP thermochemical recycling can be self-sustained in a Dual Fluidized Bed if the non-valuable products are combusted. The results obtained in this work indicate that this TOP could be an appealing option to consider as a source of biorefinery revenue leading to the circular use of waste.
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| 3. |
- Forero Franco, Renesteban, 1987, et al.
(författare)
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Correlations between product distribution and feedstock composition in thermal cracking processes for mixed plastic waste
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 341
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Tidskriftsartikel (refereegranskat)abstract
- Thermal conversion can transform the carbon-based waste into valuable chemicals to be further used in the petrochemical industry for a polymeric carbon circular economy. This work's aim was to identify chemical correlations between the thermal-cracking products and the feedstock polymer composition when using highly blended waste streams. The challenges addressed were to: (i) access a pool of experimental data on the monomer recovery potential of real-life, highly blended waste streams; (ii) estimate the polymer constituents of the mixed waste streams; and (iii) formulate a generic and systematic method to identify correlations between feedstock constituents and cracking products. Different post-consumer waste streams were investigated, including cardboard, automotive shredder residues, cable stripping waste, and textile waste. The cracking experiments were performed in a 2–4MWth industrial-scale Dual Fluidized Bed system at 800 °C using steam as fluidization agent. The polymeric constituents of the feedstocks were estimated using a numerical convex optimization method. To identify correlations between the feedstocks and products, a carbon bond-based classification was introduced. The experimental monomer yield ranged from 0.08 kg/kgf to 0.3 kg/kgf (f = feedstock) for the evaluated materials, corresponding to a carbon feedstock conversion rate between 14 % and 44 %. High yields of valuable monomers were obtained for the materials with the highest polyolefin content. The olefin monomer production correlated positively to the amount of aliphatic carbon in the original material and negatively to the carbon contents of the aromatic rings. From the trends observed, it was concluded that a framework based on carbon bond types is a promising approach to identify such correlations, which could serve as predictive tools for monomer recovery based on material's composition and overall process conditions.
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| 4. |
- González Arias, Judith, 1994, et al.
(författare)
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Effect of biomass ash on preventing aromatization of olefinic cracking products in dual fluidized bed systems
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 338
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effect of ash activated olivine on olefinic products cracking and aromatization was assessed. The experiments were carried out in the Chalmers 2–4 MWth dual fluidized bed gasifier, where the feedstock was cracked using steam as fluidization agent, at a reaction temperature of ca. 780–790 °C. Three activation states of the olivine, representing three consecutive days of the campaign, were evaluated. The changes of the permanent gas composition along with the reduction in aromatic species with the time of exposure to biomass ash demonstrate a clear effect of the ash activated olivine on the conversion of olefinic cracking products. The ash activation of the olivine clearly promoted the reactions involving steam. As a consequence, higher yields of permanent gases, mainly H2, CO and CO2, were produced at expenses of the yields of the total aromatic compounds and C4 hydrocarbons and larger. It is concluded that the biomass ash activated olivine promotes the steam reforming path of the C4 and larger hydrocarbon fragments, while avoiding the alternative aromatization route. The results presented here provide useful insights on the opportunities and limitations of ash activated materials in DFB systems when steam cracking linear hydrocarbon feedstocks, e.g., polyolefin-based materials.
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| 5. |
- González Arias, Judith, 1994, et al.
(författare)
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Steam gasification as a viable solution for converting single-use medical items into chemical building blocks with high yields for the plastic industry
- 2024
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Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 201
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the challenge of recycling single-use medical items due to their non-recyclable nature and associated environmental concerns. To align with the circular economy principles, we propose thermochemical recycling, specifically steam gasification, for carbon atoms recovery. Face masks, plastic syringes, non-woven gowns, and nitrile gloves were tested at different temperatures (700 °C, 750 °C, and 800 °C) in a lab-scale reactor. A significant portion of the carbon in the feedstock could be effectively recovered as valuable chemical building blocks (i.e., olefins, ethane, and BTXS species), enabling their direct application in the chemical industry and reducing reliance on fossil resources. At 700 °C, carbon recovery percentages were approximately 79 % for face masks, 82 % for plastic syringes, 38 % for nitrile gloves, and 76 % for non-woven gowns. Higher temperatures led to reduced recovery due to secondary cracking reactions. Overall, this study highlights the circularity potential of single-use medical waste contributing to sustainable waste management in healthcare.
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| 6. |
- Kiminaitė, Ieva, et al.
(författare)
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Syngas Production from Protective Face Masks through Pyrolysis/Steam Gasification
- 2023
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Ingår i: Energies. - 1996-1073 .- 1996-1073. ; 16:14
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has caused a heavy expansion of plastic pollution due to the extensive use of personal protective equipment (PPE) worldwide. To avoid problems related to the entrance of these wastes into the environment, proper management of the disposal is required. Here, the steam gasification/pyrolysis technique offers a reliable solution for the utilization of such wastes via chemical recycling into value-added products. The aim was to estimate the effect of thermo-chemical conversion temperature and steam-to-carbon ratio on the distribution of gaseous products obtained during non-catalytic steam gasification of 3-ply face masks and KN95 respirators in a fluidized bed reactor. Experimental results have revealed that the process temperature has a major influence on the composition of gases evolved. The production of syngas was significantly induced by temperature elevation from 700 °C to 800 °C. The highest molar concentration of H2 gases synthesized from both types of face masks was estimated at 800 °C with the steam-to-carbon ratio varying from 0 to 2. A similar trend of production was also determined for CO gases. Therefore, investigated thermochemical conversion process is a feasible route for the conversion of used face masks to valuable a product such as syngas.
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| 7. |
- Mandviwala, Chahat, 1995, et al.
(författare)
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Comparing bed materials for fluidized bed steam cracking of high-density polyethylene: Olivine, bauxite, silica-sand, and feldspar
- 2023
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Ingår i: Journal of Analytical and Applied Pyrolysis. - 0165-2370. ; 173
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Tidskriftsartikel (refereegranskat)abstract
- Steam cracking in fluidized beds is an alternative method for producing valuable petrochemicals from plastic waste. Previous studies on the conversion of plastics in fluidized beds have revolved around non-catalytic cracking using silica sand as the bed material. On the other hand, studies on catalytic cracking have focused on the use of active materials such as olivine, bauxite, feldspar, and zeolites. The potential influence of the above-mentioned materials, in their natural or inactive state, on fluidized bed hydrocarbon cracking, is not well-documented in the literature. In this paper, steam cracking of polyethylene in a bubbling fluidized bed at 750 °C is investigated in the presence of four different natural ores: olivine, bauxite, silica sand, and feldspar. The paper compares the performance of the steam cracking process in terms of cracking severity, conversion, and product distribution among different hydrocarbon groups. The results show that there is only a marginal difference in cracking severity among the different bed materials, while the conversion remain relatively consistent, ranging from 93% to 95% (carbon.%). The yields of paraffins and carbon oxides are narrow, ranging from 15% to 16% and 3–4%, respectively, while the yields of light olefins and aromatics show a slightly wider range. The yield of olefins is in the range of 52–57%, and for aromatics, it ranges from 16% to 21%. The paper also discusses the potential impact of these bed materials on the cracking reactions, including their thermal and reactive interactions.
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| 8. |
- Mandviwala, Chahat, 1995, et al.
(författare)
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Fluidized bed steam cracking of rapeseed oil: exploring the direct production of the molecular building blocks for the plastics industry
- 2023
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 13, s. 14511-14522
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Tidskriftsartikel (refereegranskat)abstract
- Fossil-based production of plastics represents a serious sustainability challenge. The use of renewable and biogenic resources as feedstocks in the plastic industry is imminent. Thermochemical conversion enables the production of the molecular building blocks of plastic materials from widely available biogenic resources. Waste cooking oil (WCO) represents a significant fraction of these resources. This work provides insights into the thermochemical conversion of the fatty acids present in WCO, where rapeseed oil is used as the source of fatty acids. The experimental results reveal that fluidized bed steam cracking of rapeseed oil in the temperature range of 650-750 degrees C yields a product distribution rich in light olefins and mono aromatics. Up to 51% of light olefins, 15% of mono aromatics, and 13% of light paraffins were recovered through steam cracking. This means that up to 70% of the carbon in rapeseed oil was converted into molecular building blocks in a single step. The main conclusion from this study is that WCO and vegetable oils represent viable biogenic feedstocks for the direct production of the molecular building blocks, where the conversion is achieved through steam cracking in fluidized beds.
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| 9. |
- Mandviwala, Chahat, 1995, et al.
(författare)
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Method development and evaluation of product gas mixture from a semi-industrial scale fluidized bed steam cracker with GC-VUV
- 2024
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Ingår i: Fuel Processing Technology. - 0378-3820. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- Steam cracking in fluidized beds offers an alternative to conventional steam cracking for sustainable hydrocarbon production. This approach has gained interest, particularly in the context of recycling plastics to generate valuable hydrocarbons. Integrating this process into existing petrochemical clusters necessitates a thorough characterization of the products derived from this new feedstock. This work focuses on addressing the challenges associated with species quantification and characterization time for assessing the product mixture resulting from a steam cracking process. The experiments were conducted in a semi-industrial scale dual fluidized bed steam cracker, utilizing polyethylene as the feedstock. To sample species spanning from C1 to C18, cooling, scrubbing, and adsorption were introduced. These steps were integrated with GC-VUV (Gas Chromatography with Vacuum Ultraviolet Spectroscopy) and other widely recognized analytical methods to quantify the sampled species. The primary focus was on GC-VUV analysis as a suitable characterization method for identifying and quantifying C4 to C18 species, which can constitute up to 35% of the product mixture obtained from polyethylene steam cracking (750 °C to 850 °C). Quantifying C6 to C18 hydrocarbons becomes the time-critical step, with GC-VUV potentially achieving this in 1/6th of the analysis time and with relatively optimal quantification compared to the traditional characterization methods.
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| 10. |
- Mandviwala, Chahat, 1995, et al.
(författare)
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Unraveling the hydrocracking capabilities of fluidized bed systems operated with natural ores as bed materials
- 2022
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- Hydrocracking represents an alternative to the recycling of abundantly available plastic waste. Hydrocracking of polyethylene in a fluidized bed, at 750 °C and 1 atm, was investigated in this work. Water dissociation, through the steam-iron reaction, was used as the source of hydrogen. Bauxite and olivine, containing reduced iron, were used as the bed materials in the reactor to drive the water dissociation reaction. The hydrogen-to-carbon (H/C) ratios of the products were compared to assess the hydrocracking potential. It was discovered that conversion of polyethylene on the surface of reduced bauxite effectively increased the H/C ratios of the products, as compared to bauxite in its oxidized form. Reduced olivine was ineffective at increasing the H/C ratios of the products in the presence of water dissociation. It is concluded that hydrocracking through hydrogen donation by steam is feasible in fluidized beds, provided that the bed material has the ability to transfer the hydrogen atoms to the hydrocarbon species.
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