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- Evangelopoulos, Panagiotis, et al.
(författare)
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Performance analysis and fate of bromine in a single screw reactor for pyrolysis of waste electrical and electronic equipment (WEEE)
- 2020
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Ingår i: Process Safety and Environmental Protection. - : Institution of Chemical Engineers. - 0957-5820 .- 1744-3598. ; 143, s. 313-321
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on chemical recycling of plastics from waste electrical and electronic equipment (WEEE), which constitutes a problematic waste fraction due to the presence of brominated flame retardants. An auger reactor has been designed and used for this study. Real WEEE material provided by Stena Technoworld has been pyrolyzed under different temperature conditions. The performance of the reactor as well as other important parameters such as the fate of the bromine have been investigated and evaluated. The main outcome of this investigation is to simulate a continuous process, which can be useful for designing a full-scale industrial process. The mass balance results after performing thermal treatment at 400, 500, and 600 °C, showed a high gas yield (44 %wt) at the temperature of 600 °C, which energy content is enough to self-sustain the auger reactor. At the low temperature of 400 °C the oil production reaches its maximum yield as well as maximum concentration of bromine, corresponding to 0.5 wt% in the oil. Several valuable organic compounds have been detected in the oil composition, which can be used as precursors for feedstock recycling producing new plastics. © 2020 The Authors
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| 2. |
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| 3. |
- Ding, Saiman, et al.
(författare)
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Effects of Porous Structure Development and Ash on the Steam Gasification Reactivity of Biochar Residues from a Commercial Gasifier at Different Temperatures
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:18
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims at investigating the effects of porous structure development and ash content on the observed reactivity during steam gasification of biochar residues from a commercial gasifier. The experiments were conducted at a temperature range of 700 to 800 °C using biochar, derived from entrained flow gasification of biomass, under isothermal conditions using a thermogravimetric analyzer. The pore size distribution, surface area and morphology of char samples were determined by N2 physiosorption and scanning electron microscopy (SEM). The results showed that the gasification temperature does not affect the porous structure development considerably. The total surface area of char exhibits a threefold increase, while the total pore volume increase ranges between 2.0 and 5.3 times, at all temperatures. Both properties are directly proportional to the observed reactivity, especially at conversions up to 70%. Catalytic effects of the mineral matter of the char (mainly potassium) become predominant at the later stages of conversion (conversion greater than 70%).
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| 4. |
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| 5. |
- Ding, Saiman, et al.
(författare)
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Potassium-Induced Phenomena and Their Effects on the Intrinsic Reactivity of Biomass-Derived Char during Steam Gasification
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:32, s. 29131-29142
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Tidskriftsartikel (refereegranskat)abstract
- The mineral content of biomass plays an important role in the gasification rate of biomass-derived char. The understanding and quantification of mineral-related phenomena are thus of importance when considering gasification reactor design. In the present work, the potassium-induced catalytic phenomena during gasification of biomass-derived char have been studied. Char samples with similar structure and different intrinsic potassium content were gasified in a steam atmosphere at a temperature range of 700-800 °C. It was found that for all the samples, irrespective of the temperature and the initial potassium content, there is a critical K/C ratio (5 × 10-3), whereafter the catalytic phenomena prevail. The instantaneous conversion rate of the char is positively correlated with the potassium content and the progressively increasing conversion. The application of the modified random pore model was able to capture the later stages of conversion by the introduction of two additional parameters (c and p). It was found that these constants are not just fitting parameters but that there is an underlying physical significance with c being directly related to the intrinsic potassium content while being temperature independent and with p being temperature dependent.
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| 6. |
- Ding, Saiman, et al.
(författare)
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Secondary tar cracking in fixed bed using char residues from the wood gasification
- 2019
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Konferensbidrag (refereegranskat)abstract
- Biomass gasification is a promising technology for production of synthesis gas, hydrogen (H2) and carbon monoxide (CO), which can be subsequently converted into valuable end products. However, high tar content in the product gas during gasification is one of the major problems, limiting the further usage of the producer gas. Tar decomposition using char from the pyrolysis of biomass becomes more popular. Alternatively, using char residues, derived from the gasification process itself, could also be a measure to further reducing the tar content. Char and char-supported catalysts have been studied for the decomposition of model tar compounds, such as toluene, benzene, naphthalene as well as phenol.Moreover, there is no information about interactions or synergistic effects between light and heavy tar model compounds in mixtures of toluene and naphthalene. In this study, the catalytic effect of char samples derived from entrained flow gasification and high pressure carbonization process, on the tar model compounds decomposition was investigated using a fixed-bed reactor. The effects of differently produced char on the tar cracking efficiency was evaluated at 800 °C and 900 °C at a weight hourly space velocity (WHSV) 0.2 h-1 and a tar concentration of 5 g/Nm3.The effect of differently produced char on the efficiency of tar cracking is also evaluated. Preliminary results show that naphthalene and toluene conversion is increased over the char from the entrained flow with increased temperature. It verifies the catalytic effect of char on tar removal. However, conversions decreased over time most likely due to a decrease in specific surface area from 42 to 1.5 m2/g during the test at 900 °C. Comparation of catalytic tar cracking properties between different chars will be provided later on.
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| 7. |
- Ding, Saiman, et al.
(författare)
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Time-resolved alkali release during steam gasification of char in a fixed bed reactor
- 2024
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 356, s. 129528-
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Tidskriftsartikel (refereegranskat)abstract
- In this study time-resolved char conversion and alkali release under steam gasification conditions were investigated using a fixed bed reactor. The behaviour of an industrial char and chars produced from straw and furniture waste was investigated. For woody chars, an increase in gasification reactivity is observed together with a notable alkali release as the gasification approaches completion (degree of conversion > 0.8). In contrast, straw char exhibited a decrease in conversion rate and alkali release throughout the gasification process, attributed to the formation of catalytically inactive potassium silicates inhibiting the catalytic role of alkali. Aerosol particles in the 0.01–22 µm size range are emitted during the char conversion. A fraction is formed by nucleation of alkali compounds and other condensable gases. A wide particle distribution that extends over the whole size range is also observed, and the particles are likely to consist of solid char fragments. The study concludes on the importance of alkali release, illustrating the difference in alkali release pattern for high and low ash char.
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| 8. |
- Eleftheriadis, Georgios K., et al.
(författare)
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Automated digital design for 3D-printed individualized therapies
- 2021
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 599
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Tidskriftsartikel (refereegranskat)abstract
- Customization of pharmaceutical products is a central requirement for personalized medicines. However, the existing processing and supply chain solutions do not support such manufacturing-on-demand approaches. In order to solve this challenge, three-dimensional (3D) printing has been applied for customization of not only the dose and release characteristics, but also appearance of the product (e.g., size and shape). A solution for customization can be realized via non-expert-guided processing of digital designs and drug dose. This study presents a proof-of-concept computational algorithm which calculates the optimal dimensions of grid-like orodispersible films (ODFs), considering the recommended dose. Further, the algorithm exports a digital design file which contains the required ODF configuration. Cannabidiol (CBD) was incorporated in the ODFs, considering the simple correspondence between the recommended dose and the patient's weight. The ODFs were 3D-printed and characterized for their physicochemical, mechanical, disintegration and drug release properties. The algorithm was evaluated for its accuracy on dose estimation, highlighting the reproducibility of individualized ODFs. The in vitro performance was principally affected by the thickness and volume of the grid-like structures. The concept provides an alternative approach that promotes automation in the manufacturing of personalized medications in distributed points of care, such as hospitals and local pharmacies.
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| 9. |
- Evangelopoulos, Panagiotis, 1988-, et al.
(författare)
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Experimental investigation of low temperature pyrolysis of printed circuit boards (PCBs) and printed circuit board components (PCB sockets)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Printed circuit boards (PCBs) are the heart of all electronics due to their compact size and the broad spectrum of applications but very challenging when their life ends. Recycling of these components is problematic since they consist of different metallic parts packed on plastic compressed cover. The present study focuses on low temperature pyrolysis of PCBs since this process can separate the organic fraction from the inorganics. The latter, enables further separation and purification of the metals which are not oxidized during mild treatment. The low Br content of the resultant char after treatment at 320 oC for 30 min indicates that it could be used as solid fuel if efficient separation from the inorganic part would be performed. Moreover, the liquids obtained by this process can be used for feedstock recycling since the results indicates that toxic bromine containing on the organic compounds has been decreased both by increasing the residence time of pyrolysis process or by increasing the temperature conditions.
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| 10. |
- Evangelopoulos, Panagiotis, 1988-
(författare)
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Pyrolysis and Detoxification of Waste Electrical and Electronic Equipment (WEEE) for Feedstock Recycling
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The trends in waste electrical and electronic equipment (WEEE) generation shows that their volume constantly increases, while the current waste management technologies have proven to be insufficient in order to meet the strict criteria and the new legislations of the European Union. Pyrolysis and thermal treatment in general could be a valuable solution for closing the loop of materials and could contribute to the energy demands of modern society.Pyrolysis as a process and combination of other pre-treatment techniques was investigated with a focus on energy production, metal separation and feedstock recycling. In this work, several fractions of real WEEE have been tested based on the process requirements and the focus of each individual study.Firstly, the investigation was focused on the primary products of the process, revealing most of the environmental pollutants as well as the valuable monomers that can enhance feedstock recycling. A correlation of the process’ final temperature with the evolution of the major products was performed. Moreover, a conceptual reaction mechanism of Bisphenol A decomposition was suggested based on the process products.Then, a reduction of the bromine content of the initial WEEE fraction was achieved by solvent extraction pre-treatment. Isopropanol and toluene were tested as solvents capable of removing one of the main flame retardants at WEEE fractions, Tetrabromobisphenol A. The results indicate that the reduction of bromine was successfully performed even at ~37%. This result was further confirmed by the reduction or total removal of brominated species in the pyrolysis products. The toluene seems to be a valuable option for the pre-treatment, since it can be provided by the pyrolysis process itself, making the entire treatment more sustainable and in accordance with the concept of circular economy.Density separators used in the sorting of WEEE materials usually produced high moisture content fractions. As soon as those fractions follow thermal treatment, the moisture will eventually become steam, which influences the process. Therefore, WEEE materials were pyrolysed in nitrogen and steam atmospheres and their decomposition was evaluated. Steam had a negative impact on the products, since several high molecular weight products were detected, revealing that steam limits secondary cracking reactions. Additionally, the results show that the presence of steam complicates the separation of oils and favours the migration of antimony to the gas phase. Therefore, a drying step before using pyrolysis for this fraction is necessary.Low temperature pyrolysis was also investigated for making the WEEE more fragile to enhance metal separation from the carbonised solid residue while the fate of bromine was also monitored. The results indicate that the separation is possible at low temperatures for minimising the energy consumption of the process but it should be at least 40 ° higher than the onset temperature of the selected material. The separation was also evaluated with fractionation of the solid residue, revealing that the produced bromine-free solid carbonised material can be further utilised for energy production.Finally, the entire process was tested in a continuous screw reactor for overall process evaluation. The results indicate that the liquid products of pyrolysis can be used for feedstock recycling, producing necessary organic compounds that can be used for manufacturing new plastics or can be used as liquid fuel. The brominated compounds tend to migrate to the gas phase, as the temperature of the process increases, making the recycling of metals from the solid residue easier. The process in general can be self-sustained since the energy needed for the system to heat up can be covered from its gas production.
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