| 1. |
- Wang, Shule, 1994-, et al.
(författare)
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Novel carbon-negative methane production via integrating anaerobic digestion and pyrolysis of organic fraction of municipal solid waste
- 2021
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The use of bioenergy with carbon capture and storage (BECCS) is vital to reaching the desired climate goals. This study proposed a novel process combining anaerobic digestion, pyrolysis, catalytic reforming and methanation (APRM) to produce biomethane and to capture carbon emission from the organic fraction of municipal solid waste (OFMSW). The evaluation of the process was conducted by using modelling software and techno-economic analysis. The process modelling and evaluation result showed that 151.4 kg CH4 and 355.64 kg stored carbon emission can be produced from 1 ton dry matter of OFMSW with an energy efficiency of 0.40. 6.74 MJ electricity was required to capture 1 kg of CO2 via the proposed process. The energy balance of the pyrolysis reaction was investigated. The sensitivities of the pyrolysis temperatures, dewatering technologies and conversion of catalytic reforming on the process performance were analyzed. The result also indicated a positive net profit when using the APRM process to treat the OFMSW based on the calculation of operating expenses and revenue, when the CO2 negativity can be sold as commodity.
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| 2. |
- Wang, Shule, 1994-, et al.
(författare)
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Pyrolysis behaviour, kinetics and thermodynamic data of hydrothermal carbonization-Treated pulp and paper mill sludge
- 2021
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Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 177, s. 1282-1292
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Tidskriftsartikel (refereegranskat)abstract
- Organic-rich pulp and paper mill sludge (PPMS) has the potential to become a renewable carbon source for producing alternatives to fossil-based product. In this work, PPMS treated by hydrothermal carbonization (HTC) was investigated based on its pyrolysis properties. The pyrolytic mechanism, kinetics data and product of the sample were studied using TG as well as pyrolysis tests in Py-GC/MS and a bench-scale reactor at 450, 550, and 650 degrees C. The results show that the thermal decomposition of feedstock is a two-stage reaction. The mean activation energy of the pyrolysis of HTC treated PPMS was estimated as 233.08 kl/mol, which is higher than that of the pyrolysis of paper sludge reported before. The changes in enthalpies, entropies and Gibbs free energies from the reactants to the activated complex were estimated. The concentration of monocyclic aromatic hydrocarbons in the derived organic liquid fraction shows a positive correlation with the pyrolysis temperature. At 550 degrees C, the organic liquid fraction reached its highest yield at 13.7% with an oxygen level of 10.7 wt% and a higher heating value of 35.9 MJ/ kg. The pyrolytic chars show that a molar ratio of O:C is less than 0.2, which shows potential for use as a carbon sink.
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| 3. |
- Wang, Shule, 1994-
(författare)
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Pyrolysis of Biodegradable Waste for Negative Carbon Emissions
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bioenergy with Carbon Capture and Storage represents a crucial technology that enables an energy production with negative carbon emissions, which is needed to achieve global climate goals. Appropriated management of biodegradable waste, including biodegradable lignocellulosic waste, sewage sludge, organic fraction of municipal solid waste, can make this contribution. The implementation of pyrolysis process is able to produce biochar, liquid and gas product from biodegradable waste. Based on the pyrolysis technology, a sustainable management of biodegradable waste for negative carbon emission is proposed in this work. The proposed novel process combines an anaerobic digestion, pyrolysis of the digestate following by catalytic reforming the pyrolytic vapor, then methanation of the reforming gas, separating the stream of CH4 and CO2. The storage of separated CO2 streams and biochar can be considered as negative emissions. Furthermore, the pyrolysis behaviors of the solid residue, which was produced from hydrothermal carbonization pretreatment of biodegradable wastes, are investigated. The pyrolytic liquid was further upgraded to a higher quality product with a less oxygen content, a higher calorific value by using ex-situ and in-situ hydrogen donors. Carbon stability of the pyrolytic biochar, which is one of key parameters to assess the biochar as carbon sink, was evaluated by using the accelerated oxidation method. Finally, energy and mass balance on the proposed process was obtained. The pyrolysis behavior of hydrothermal carbonization-treated sewage sludge digestate, and paper sludges were investigated. Thermogravimetric analysis, Py- Gas chromatography–Mass spectrometry and bench-scale experiments were employed to fulfil this objective. The thermal degradation behavior of these two feedstocks was investigated. Initially, the compounds in the pyrolytic vapor were identified. Thereafter, the pyrolytic product from the bench-scale experiment was characterized. It was found that the pyrolysis reaction of both feedstocks was a two-stage reaction. The organic fraction with a higher heating value around 28.47 to 38.46 MJ/kg was produced from the pyrolysis of hydrothermal carbonization-treated biodegradable waste. More organic fraction can be produced from the pyrolysis of the paper sludge than that from sewage sludge digestate. It was also found that the fixed carbon content in raw materials is difficult to be determined by using the standard method due to the ash oxidation behavior in such materials. Therefore, a method to determine the sample's fixed carbon content without affected by the ash oxidation behavior was developed. Introducing hydrogen donors to upgrade the pyrolytic liquid products for a higher quality product with a lower oxygen content and a higher calorific value is investigated. The H2 was used as an ex-situ hydrogen donor in the lignocellulosic waste pyrolysis in both non-catalytic and catalytic cases. The catalyst used in this study was a commercial HZSM-5, catalyst with a strong selectivity of aromatics. The hydrogen consumption during pyrolysis in the H2 atmosphere was indicated by experiments. The gas and liquid production were promoted while the biochar yield was suppressed in the presence of the H2 atmosphere. However, the presence of an H2 atmosphere was found to increase the acidity of the HZSM-5 and enhance the production of polyaromatics during the pyrolysis process. Further, the study using the sewage sludge digestate as an in-situ hydrogen donor to pyrolysis of lignocellulosic biomass obtained from the salix family was investigated. The sewage sludge digestate was premixed with salix in five blended ratios and pyrolyzed in a bench-scale reactor. The composite of 75% sludge digestate and 25% salix presented the highest mass and energy yields of the organic fraction in the liquid product. The yield of biochar was suppressed in this copyrolysis. The synergistic effect between the sludge digestate and salix was studied with respect to reaction mechanisms, carbon number distribution of the compounds in organic fraction, and biochar stability. The competition reaction between the short-chain carboxylic acid from salix pyrolysis and a long-chain carboxylic acid from digestate pyrolysis was one of the main reasons for the synergistic reaction regarding the composition of the organic fraction. This competition reaction results in a higher amount of long-chain carboxylic acid esters and N-heterocyclic compounds, a lower amount of the long-chain nitriles in the organic fraction produced from copyrolysis compared to it from individual pyrolysis. The stabilities of the biochar products from the copyrolysis of sewage sludge digestate and salix, were determined by using the accelerated oxidation method. It was found that the biochar stabilities are promoted by this copyrolysis. The nitrogen yield in the biochar product was also enhanced by the copyrolysis process. The proposed CO2 negative process was modelled using the process simulation software, and the modelling results were validated by using an experimental data. The pyrolysis temperature and dewatering technology were used for sensitivity analysis. In this process, methane was chosen as the final product. Pyrolytic biochar and compressed CO2 was captured and stored as the negative carbon emission. It was found that for 1000 kg of dry matter digestate, one can obtain 151.4 kg CH4 in a purity of 96 vol%, 304.5kg compressed CO2, and 80.8 kg biochar. The latter two are equal to 355.64 kg negative CO2 emission.
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| 4. |
- Wang, Shule, 1994-, et al.
(författare)
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Synergistic effects in the copyrolysis of municipal sewage sludge digestate and salix : Reaction mechanism, product characterization and char stability
- 2021
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 289
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion is a practical process for recovering energy and materials from sewage sludge. However, land disposal of the derived digestate results in environmental problems, such as eutrophication and salinization. Copyrolysis of sewage sludge digestate and lignocellulosic biomass produces a high-quality oil, a diluted hazardous component of biochar. This study investigates the copyrolysis behavior of lignocellulosic biomass and sludge digestate with different blending ratios using bench-scale experiments. Compared to individual feedstock pyrolysis, copyrolysis shows a higher energy distribution in the liquid product and a lower energy distribution in the char and gas product. The highest energy yield with respect to the organic fraction of liquid product is observed in the copyrolysis case, corresponding to 36.4% of the total energy in the feedstock. The interaction between the sludge digestate and lignocellulosic biomass is studied through product characterizations, mechanistic investigations and char stability assessments. The liquid products in the copyrolysis cases show a relatively high abundance of esters, aliphatic hydrocarbons, pyridines and pyrroles. The reaction pathways of proteins, lipids and carbohydrates are investigated. Two synergistic reaction pathways are proposed. The char stability and nitrogen distribution are investigated. According to the results, the synergistic interaction between feedstocks enhances the quality and energy yield of the liquid biofuel. The char product from copyrolysis has higher potential for use as a carbon sink and fertilizer.
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| 5. |
- Wen, Yuming, et al.
(författare)
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Magnetic bio-activated carbons production using different process parameters for phosphorus removal from artificially prepared phosphorus-rich and domestic wastewater
- 2021
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 271
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Tidskriftsartikel (refereegranskat)abstract
- A series of magnetic bio-activated carbon (MBAC) has been produced from lignin and ferrous salts following to the process including impregnation, carbonization, and steam activation. The influence of the impregnation methods and the steam flow rate on the quality and the maximum phosphorus adsorption capacity of the produced MBACs has been investigated. The phosphorus adsorption performance in real domestic wastewater of the MBAC with the highest maximum phosphorus adsorption capacity has been investigated. The results show that all of the produced MBACs have a relatively rich porous structure, and all surface iron species exist as magnetite (Fe3O4). Compared with the MBACs that are produced via the dry impregnation method using a lower steam flow rate, the MBACs that are produced via the wet impregnation method using a higher steam flow rate are believed to have a higher iron content and better iron species dispersion. The highest maximum phosphorus adsorption capacity of all the produced MBACs is estimated to be as high as 69.80 mg-P/g according to the best-fitting Langmuir model. The MBAC that shows the highest maximum phosphorus adsorption capacity could also remove 84.65% and 96.97% of the total phosphorus from the filtered raw domestic wastewater (FRDW) and treated domestic wastewater (TDW), respectively, which indicates a good potential for using MBACs for domestic wastewater treatment.
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| 6. |
- Wen, Yuming, et al.
(författare)
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Pyrolysis of raw and anaerobically digested organic fractions of municipal solid waste : Kinetics, thermodynamics, and product characterization
- 2021
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 415
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Tidskriftsartikel (refereegranskat)abstract
- Treating the solid residue after anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is currently a challenge. Here, pyrolysis is a promising way of recovering energy and materials from these solid residues. Thus, the objective of this study was to investigate the pyrolysis performance of these solid residues. The effect of AD on the pyrolysis of OFMSW was also studied. Thermogravimetry (TG), differential thermal analysis (DTA), and bench-scale pyrolysis experiments were performed by using OFMSW and anaembically digested OFMSW. Mathematical deconvolution analysis (MDA), model-free methods, and model-based methods were applied to study the kinetics. Thereafter, thermodynamic parameters were estimated based on the deduced kinetic results. The char, liquid, and permanent gas products from bench-scale experiments were characterized. The pyrolysis results show that the activation energies of the pseudoreactions of OFMSW are higher than those of the corresponding pseudoreactions of digestate. Moreover, the entropy reduction for digestate is larger than that for OFMSW. The characterization results of the products from the bench-scale experiments show that the interactions among feedstock components (lipids, lignocellulose, and proteins) during pyrolysis are enhanced by the application of AD. However, the pyrolysis yields of both heavy organics and gas are inhibited by the application of AD, while the char yield shows the opposite trend.
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| 7. |
- Wen, Yuming, et al.
(författare)
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Synergistic effect of the co-pyrolysis of cardboard and polyethylene : A kinetic and thermodynamic study
- 2021
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 229
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis of municipal solid waste (MSW) represents one of the most promising solutions to recycle materials and recover energy. Two of the main components of MSW are waste cardboard and plastic. In this study, the pyrolysis of cardboard and polyethylene (PE) and the co-pyrolysis of their mixtures were conducted to investigate the synergistic effect by using thermogravimetric analysis. The whole reaction process was divided into four pseudoreactions, namely, hemicellulose, lignin, cellulose, and PE, by using the Frazer-Suzuki deconvolution method. It was found that the co-pyrolysis of cardboard and PE could promote the decomposition degrees of cardboard from 70.28% to 75.31%, when the PE fraction increased from 0 to 75%. However, the presence of cardboard can hinder the heat adsorption of PE, which shifts the peak of the PE reaction to a higher temperature. This results in higher E-a and Delta H double dagger values for PE pyrolysis with an increasing fraction of cardboard. On the other hand, the E-a and Delta H double dagger values of cellulose pyrolysis have their lowest values when the mixing rate is around 50%. This research deepens the understanding of the synergistic effect of co-pyrolysis of cardboard and PE, which supports the potential application of pyrolysis of MSW.
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| 8. |
- Yin, Jun, et al.
(författare)
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Experimental and Numerical Study of the Gas Entrainment During the Initial Mold Filling in an Uphill Teeming Ingot Casting Process
- 2021
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The gas entrainment can influence surface disturbances during the filling in the uphill ingot teeming process. Surface disturbances can result in mold flux entrapments, leading to the generation of non-metallic inclusions which are detrimental to the final steel quality. A three-dimension simulation was conducted to study the gas entrainment during the filling process. Furthermore, a water model experiment was also carried out to validate the results from the numerical simulations. The results showed a good agreement between the numerical and physical models. Moreover, the formation of a big bubble can be observed at the bend between the trumpet and the horizontal runner, and between the horizontal runner and the vertical runner. The sizes of the big bubble fluctuate during the teeming process. The current study gives a specific overview of the gas entrainment phenomenon during the initial filling of the uphill teeming process.
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