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  • 51.
    Sanches Pereira, Alessandro
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. University of São Paulo, Brazil .
    Lönnqvist, Tomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Gómez, Maria F.
    Universidad de La Sabana.
    Teixeira Coelho, Suani
    USP University of São Paulo.
    Tudeschini, Luís G.
    USP University of São Paulo.
    Is natural gas a backup fuel against shortages of biogas or a threat to the Swedish vision of pursuing a vehicle fleet independent of fossil fuels?2015In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 83, p. 1187-1199Article in journal (Refereed)
    Abstract [en]

    The objective of this study is to verify whether natural gas is only a backup fuel against shortages of upgraded biogas or a threat to the Swedish vision of pursuing a vehicle fleet independent of fossil fuels. The paper uses Stockholm County as a case study to guide our analysis. The region not only concentrates the largest number of inhabitants in Sweden but also holds alone around 35% of the Swedish fleet of passenger cars using gas as fuel. The region's potential vehicle gas demands are 460 GWh by 2020 and 1202 GWh by 2030. The methodological approach relies on Network Theory to guide the numerical analysis of the vehicle gas supply chain in the region. Our results show that natural gas will keep on being an important resource and playing a vital role within the local vehicle gas supply chain but no longer as a backup fuel against upgraded biogas shortages. In fact, natural gas has become a price regulator responsible for vehicle gas attractiveness, especially for passenger cars in the region. As a result, phasing out natural gas could hamper future developments of biogas supply chain in the country, hindering the achievement of a green fleet.

  • 52.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Bioenergy – realizing the potential2005Book (Other academic)
  • 53.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Ska jag tanka etanol?2011Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Ska konsumenter som vill agera miljövänligt köra fordon somdrivs på etanol? Sänks verkligen utsläppen när folk tankar E85 istället för bensin? Och riskerar en ökad etanolproduktion att ta mark ianspråk som istället kunde användas till att odla livsmedel?

    Denna studie vill nyansera debatten och slå hål på några av myterna kring användandet av etanol. Här ges exempel på samhällets vinster av en ökad produktion och användning av etanol inomtransportsektorn, såväl för miljön som för ekonomin. Likaså visarden på de positiva effekter etanolen har i de utvecklingsländer därfrämst sockergrödor odlas, särskilt vad avser en modernisering avjordbruks- och industrisektorerna. I ett särskilt avsnitt diskuterasockså industriländernas generella behov av en högre tillgång till alternativa drivmedel.

    Studien ser positivt på en utbyggd produktion av etanol somdrivmedel, men betonar tydligt att det inte får vara den enda vägenframåt. Behövliga satsningar inom etanolindustrin ska inte utesluta eller ske på bekostnad av utvecklingen av andra förnybarabränslen.

  • 54.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    The role of energy policies and markets in promoting sustainable development2010Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    This paper discusses the use of energy provision as a strategy for promoting sustainabledevelopment. We briefly discuss the role that bioenergy can play in addressing environmentand development issues through the promotion of efficient renewable alternatives fortransport and electrification in developing countries. We argue that accumulated experiencesprovide guidance to how energy policies and programs can contribute to overall developmentgoals in developing countries. The topic is of high relevance for multilateral organizationssuch as UNCTAD, the World Bank, development assistance agencies, and nationalgovernments in developing countries.

  • 55. Sinkala, T.
    et al.
    Johnson, Francis X.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Biofuels for Poverty Reduction and Environmental Restoration: the Case of Jatropha in Zambia2009In: Climate challenge-the safety’s off / [ed] B. Johansson, Stockholm: FORMAS , 2009Chapter in book (Refereed)
  • 56. Smail, R. E.
    et al.
    Horsley, R.
    Nakamura, Y.
    Perlt, H.
    Pleiter, Dirk
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for High Performance Computing, PDC.
    Rakow, P. E. L.
    Schierholz, G.
    Stüben, H.
    Young, R. D.
    Zanotti, J. M.
    Tensor Charges and their Impact on Physics Beyond the Standard Model2022In: Proceedings of Science, Sissa Medialab Srl , 2022Conference paper (Refereed)
    Abstract [en]

    The nucleon tensor charge, gT, is an important quantity in the search for beyond the Standard Model tensor interactions in neutron and nuclear β-decays as well as the contribution of the quark electric dipole moment (EDM) to the neutron EDM. We present results from the QCDSF/UKQCD/CSSM collaboration for the tensor charge, gT, using lattice QCD methods and the Feynman-Hellmann theorem. We use a flavour symmetry breaking method to systematically approach the physical quark mass using ensembles that span three lattice spacings. 

  • 57.
    Solis, Jerry Luis
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Davila, R.
    Sandoval, C.
    Guzmán, D.
    Guzmán, H.
    Alejo, L.
    Kiros, Yohannes
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Ethanol Production from Schinus molle Essential Oil Extraction Residues2020In: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, Vol. 11, no 8, p. 4053-4065Article in journal (Refereed)
    Abstract [en]

    Abstract: The present study determines the best conditions for the fermentation of Schinus molle drupes by the combination of different types of hydrolysis with the search for an adequate yeast strain. Schinus molle seed residues from an essential oil extraction plant (EOEP) have a high potential for ethanol production. Native yeast strains were isolated from the residues and were used to ferment the lignocellulosic residues, along with baker’s yeast (Saccharomyces cerevisiae) at 30 °C and pH 5.5 for comparison. Morphological and biochemical characterizations were carried out on the isolated yeast strains. Thermogravimetric and high-performance liquid chromatography analyses were done on the S. molle seeds (fresh and residue) to determine the ethanol production potential. The followed methodology included increasing the sugar content by hydrolysis with chemical (sulphuric acid, acetic acid, and sodium hydroxide), physical (thermal, vacuum, and ultrasound), and enzymatic treatments (amyloglucosidase and α-amylase). Once the optimum combination of yeast-hydrolysis was determined, a comparison of the greenhouse gas emissions between the original and proposed processes was done. The fermentation of the residues might replace methane from uncontrolled decomposition and reduce the solid residues in 50%/day, hence the EOEP global warming potential is reduced by 47%. The yearly income was estimated to increase by USD 2592.50 from 6302.6 L of ethanol produced from the residues.

  • 58.
    Steinhagen, Sophie
    et al.
    Univ Gothenburg, Dept Marine Sci, Strömstad, Sweden..
    Enge, Swantje
    Univ Gothenburg, Dept Marine Sci, Strömstad, Sweden..
    Cervin, Gunnar
    Univ Gothenburg, Dept Marine Sci, Strömstad, Sweden..
    Larsson, Karin
    Chalmers Univ Technol, Div Food & Nutr Sci, Dept Biol & Biol Engn, Gothenburg, Sweden..
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Schmidt, Alina E. M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wahlström, Niklas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kollander, Barbro
    Swedish Food Agcy, Uppsala, Sweden..
    Pavia, Henrik
    Univ Gothenburg, Dept Marine Sci, Strömstad, Sweden..
    Undeland, Ingrid
    Chalmers Univ Technol, Div Food & Nutr Sci, Dept Biol & Biol Engn, Gothenburg, Sweden..
    Toth, Gunilla B.
    Univ Gothenburg, Dept Marine Sci, Strömstad, Sweden..
    Harvest Time Can Affect the Optimal Yield and Quality of Sea Lettuce (Ulva fenestrata) in a Sustainable Sea-Based Cultivation2022In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 9, article id 816890Article in journal (Refereed)
    Abstract [en]

    Seaweed biomass is a renewable resource with multiple applications. Sea-based cultivation of seaweeds can provide high biomass yields, low construction, operation, and maintenance costs and could offer an environmentally and economically sustainable alternative to land-based cultivations. The biochemical profile of sea-grown biomass depends on seasonal variation in environmental factors, and the optimization of harvest time is important for the quality of the produced biomass. To identify optimal harvest times of Swedish sea-based cultivated sea lettuce (Ulva fenestrata), this study monitored biomass yield, morphology, chemical composition, fertility, and biofouling at five different harvesting times in April - June 2020. The highest biomass yields (approximately 1.2 kg fw [m rope](-1)) were observed in late spring (May). The number and size of holes in the thalli and the amount of fertile and fouled tissue increased with prolonged growth season, which together led to a significant decline in both biomass yield and quality during summer (June). Early spring (April) conditions were optimal for obtaining high fatty acid, protein, biochar, phenolic, and pigment contents in the biomass, whereas carbohydrate and ash content, as well as essential and non-essential elements, increased later in the growth season. Our study results show that the optimal harvest time of sea-based cultivated U. fenestrata depends on the downstream application of the biomass and must be carefully selected to balance yield, quality, and desired biochemical contents to maximize the output of future sea-based algal cultivations in the European Northern Hemisphere.

  • 59.
    Steinhagen, Sophie
    et al.
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    Enge, Swantje
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    Wahlström, Niklas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Olsson, Joakim
    Chalmers Univ Technol, Dept Biol & Biol Engn Ind Biotechnol, Gothenburg, Sweden..
    Nylund, Goran
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    Cervin, Gunnar
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    Albers, Eva
    Chalmers Univ Technol, Dept Biol & Biol Engn Ind Biotechnol, Gothenburg, Sweden..
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Undeland, Ingrid
    Chalmers Univ Technol, Dept Biol & Biol Engn & Nutr Sci, Gothenburg, Sweden..
    Pavia, Henrik
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    Toth, Gunilla
    Univ Gothenburg, Tjarno Marine Lab, Lab Vagen 10, Marine Sci, Stromstad, Sweden..
    The large-scale cultivation potential of ulva fenestrata: A case study from a scandinavian off-shore seafarm2021In: Phycologia, ISSN 0031-8884, E-ISSN 2330-2968, Vol. 60, p. 17-17Article in journal (Other academic)
  • 60.
    Taibi, Emanuele
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    A system dynamics energy model for a sustainable transportation system2010In: Proceedings of the 28th International Conference of the System Dynamics Society: July 25 – 29, 2010. Seoul, Korea, Boston, USA, 2010Conference paper (Refereed)
    Abstract [en]

    The transportation sector is one of the most resilient to the shift away from oil. Policies have been put in place in different regions to introduce alternative fuels and reduce the road transportation heavy dependency on oil products and the related environmental impacts; results, however, are in most cases disappointing. The system is resilient and goes back to the historical dichotomy gasoline-diesel. If from a policy maker perspective, a system dynamics model of the automotive sector can lead to the development of effective policies to achieve sustainable mobility, from an energy company perspective, such a model could be used to analyze possible threats and design optimal adaptation strategies for a highly volatile and market that is always on the edge of starting a new major transition. The model here presented can serve both purposes, and the results obtained show how a similar instrument can really make the difference in highly dynamic sectors with ongoing major transitions.

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  • 61. Toth, Gunilla B.
    et al.
    Harrysson, Hanna
    Wahlström, Niklas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Olsson, Joakim
    Oerbekke, Annelous
    Steinhagen, Sopie
    Kinnby, Alexandra
    White, Joel
    Albers, Eva
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Undeland, Ingrid
    Pavia, Henrik
    Effects of irradiance, temperature, nutrients, and pCO2 on the growth and biochemical composition of cultivated Ulva fenestrata2020In: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176, Vol. 32, no 5, p. 3243-3254Article in journal (Refereed)
    Abstract [en]

    Ulva fenestrata is an economically and ecologically important green algal species with a large potential in seaweed aquaculture due to its high productivity, wide environmental tolerance, as well as interesting functional and nutritional properties. Here, we performed a series of manipulative cultivation experiments in order to investigate the effects of irradiance (50, 100, and 160 μmol photons m−2 s−1), temperature (13 and 18 °C), nitrate (< 5, 150, and 500 μM), phosphate (< 1 and 50 μM), and pCO2 (200, 400, and 2500 ppm) on the relative growth rate and biochemical composition (fatty acid, protein, phenolic, ash, and biochar content) in indoor tank cultivation of Swedish U. fenestrata. High irradiance and low temperature were optimal for the growth of this northern hemisphere U. fenestrata strain, but addition of nutrients or changes in pCO2 levels were not necessary to increase growth. Low irradiance resulted in the highest fatty acid, protein, and phenolic content, while low temperature had a negative effect on the fatty acid content but a positive effect on the protein content. Addition of nutrients (especially nitrate) increased the fatty acid, protein, and phenolic content. High nitrate levels decreased the total ash content of the seaweeds. The char content of the seaweeds did not change in response to any of the manipulated factors, and the only significant effect of changes in pCO2 was a negative relationship with phenolic content. We conclude that the optimal cultivation conditions for Swedish U. fenestrata are dependent on the desired biomass traits (biomass yield or biochemical composition).

  • 62.
    Trossbach, Martin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Björk, Sara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Jönsson, Håkan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    High-throughput fluorescence area sorting of droplet microfluidic S. cerevisiae microcoloniesManuscript (preprint) (Other academic)
    Abstract [en]

    Cellular heterogeneity in isogenic cell populations is a major obstacle for single-cell screening campaigns, as the phenotype of individual cells might differ drastically from the mean, leading to large overlaps between productivity assessments of populations. At the other end of the spectrum, isogenic bulk assays provide a more accurate picture of a strain’s capacity at production scale, but suffers from low throughput and high reagent consumption.

    Here, we present a screening format for cell factory variant libraries, aiming at combining the advantages of single-cell screening and bulk assay formats. Using microfluidic droplets, we compartmentalize yeast cell producer candidates, culture them to form isogenic microcolonies and sort colonies at higher throughput than bulk experiments to assess the genetic potential more accurately than in a single-cell screening format. To this end, we developed a fluorescence area-based sorting method that integrates the fluorescence signal from the entire fluorescence profile of a droplet and bases the sorting decision on that integrated fluorescence area. We validate the concept by sorting droplet microcolonies of fluorescent protein expressing Escherichia coli. Finally, we successfully sorted encapsulated iso-genic microcolonies of a low-producing and a high-producing strain of Saccharomyces cerevisiae by Triacylglycerol (TAG) production at 220 Hz, enriching the high-producing strain 4.45-fold.

  • 63.
    Wahlund, Bertil
    et al.
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Yan, Jinyue
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Westermark, Mats
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Increasing biomass utilisation in energy systems: A comparative study of CO2 reduction and cost for different bioenergy processing options2004In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 26, no 6, p. 531-544Article in journal (Refereed)
    Abstract [en]

    Emissions of greenhouse gases, such as CO2, need to be greatly reduced to avoid the risk of a harmful climate change. One powerful way to mitigate emissions is to switch fuels from fossil fuels to renewable energy, such as biomass. In this paper, we systematically investigate several bioenergy processing options, quantify the reduction rate and calculate the specific cost of reduction. This paper addresses the issue of which option Sweden should concentrate on to achieve the largest CO2 reduction at the lowest cost. The results show that the largest and most long-term sustainable CO2 reduction would be achieved by refining the woody biomass to fuel pellets for coal substitution, which have been done in Sweden. Refining to motor fuels, such as methanol, DME and ethanol, gives only half of the reduction and furthermore at a higher specific cost. Biomass refining into pellets enables transportation over long distances and seasonal storage, which is crucial for further utilisation of the woody biomass potential.

  • 64. Wang, C.
    et al.
    Mellin, Pelle
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Nilsson, L.
    Lövgren, J.
    Wikström, J.-O.
    Larsson, M.
    Injecting different types of biomass products to the blast furnace and their impacts on the CO2 emission reduction2015In: AISTech - Iron and Steel Technology Conference Proceedings, 2015, Vol. 1, p. 1525-1535Conference paper (Refereed)
    Abstract [en]

    Recent years more research has been focusing on utilizing biomass in the blast furnaces (BFs). One driving force is linked to the climate change mitigation, i.e. to reduce CO<inf>2</inf> emission from fossil reducing agents or fuels, by using biomass. The amounts of biomass that could be utilized in BF is limited by different parameters, such as metallurgical properties of reducing agents, fuel properties such as volatile content, fixed carbon and oxygen content, ash chemistry (S, Na<inf>2</inf>O, K<inf>2</inf>O, etc.). In this paper, different types of biomass products in the form of solid, liquid and gas are investigated as injectants to the blast furnace. The modelling work has been done for a BF from a Nordic country. The possible amounts of injected biomass products are presented. With the replacement ratios of pulverized coal (PC), the potential CO<inf>2</inf>emission reduction when injecting different biomass products is quantified. In addition, the strategy of using biomass at the studied iron-making plant is discussed. AISTech 2015 Proceedings

  • 65.
    Wang, Damao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Li, Jing
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience.
    Wong, Ann Chi Yan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Affinity Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Aachmann, Finn L.
    Hsieh, Yves S. Y.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    A colorimetric assay to rapidly determine the activities of lytic polysaccharide monooxygenases2018In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 11, no 215Article in journal (Refereed)
    Abstract [en]

    Lytic polysaccharide monooxygenase (LPMOs) are enzymes that catalyze the breakdown of polysaccharides in biomass and have excellent potential for biorefinery applications. However, their activities are relatively low, and methods to measure these activities are costly, tedious or often reflect only an apparent activity to the polysaccharide substrates. Here, we describe a new method we have developed that is simple to use to determine the activities of type-1 (C1-oxidizing) LPMOs. The method is based on quantifying the ionic binding of cations to carboxyl groups formed by the action of type-1 LPMOs on polysaccharides. It allows comparisons to be made of activities under different conditions.

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  • 66.
    Wang, Guangwei
    et al.
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Li, Desheng
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Yuan, Xiang
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Li, Renguo
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Dan, Jiayun
    Hunan Valin Xiangtan Iron and Steel Co, Ltd., Xiangtan 411101, China.
    Wu, Junyi
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Liu, Jiawen
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Ning, Xiaojun
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China.
    Wang, Chuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Swerim AB, SE-971 25, Luleå, Sweden.
    Co-hydrothermal carbonization of polyvinyl chloride and pyrolysis carbon black for the preparation of clean solid fuels2024In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 361, article id 130550Article in journal (Refereed)
    Abstract [en]

    Large quantities of polyvinyl chloride (PVC) and waste tires generated daily have the disadvantage of high content of harmful elements. They cannot be directly applied to blast furnace ironmaking. In this study, Cl in PVC and Zn in pyrolysis products of waste tires (pyrolysis carbon black, CB) were effectively removed by co-hydrothermal carbonization (co-HTC). The results indicated the dechlorination and dezincification efficiencies of co-HTC were improved by 2.78 % and 64.69 %, respectively, compared to HTC. Compositional analysis shows that the ash content of co-HTC is reduced by at least 7.67 % compared to conventional HTC. The hydrochar produced by co-HTC has an higher heating value (HHV) ranging from 30.67 to 34.13 MJ/kg. Results of physical and chemical characteristics analysis showed increasing the proportion of CB can reduce the C–H and -CHCl- functional groups and improve the carbon orderliness of the hydrochar. Combustion characteristics and kinetic analyses show that the combustibility of hydrochar increases with an increase in the proportion of PVC added to the co-HTC. The thermal stability and activation energy of the hydrochar increase with the addition of CB. Overall, this study has removed major harmful elements from PVC and CB through co-HTC, converting both into high-quality solid fuels that can be utilised in blast furnace ironmaking.

  • 67.
    Wang, Guangwei
    et al.
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Li, Renguo
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Dan, Jiayun
    Hunan Valin Xiangtan Iron & Steel Co Ltd, Xiangtan 411101, Peoples R China..
    Yuan, Xiang
    Hunan Valin Xiangtan Iron & Steel Co Ltd, Xiangtan 411101, Peoples R China..
    Shao, Jiugang
    Res Inst Iron & Steel Jiangsu Shasteel, Zhangjiagang 215625, Peoples R China..
    Liu, Jiawen
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Xu, Kun
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Li, Tao
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Ning, Xiaojun
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China..
    Wang, Chuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Swerim AB, SE-97125 Luleå, Sweden..
    Preparation of Biomass Hydrochar and Application Analysis of Blast Furnace Injection2023In: Energies, E-ISSN 1996-1073, Vol. 16, no 3, article id 1216Article in journal (Refereed)
    Abstract [en]

    Hydrothermal carbonization (HTC) technology was used to carbonize and improve biomass raw material to obtain hydrochar. The effects of HTC temperature and holding time on the yield, composition, structure, combustion behavior, and safety of hydrochar were studied systematically. In addition, the results show that with the increase in HTC temperature and the prolongation of holding time, the yield of hydrochar gradually reduces, the fixed carbon content of hydrochar increases, the volatile content decreases, and a large number of ash and alkali metals enter the liquid phase and are removed. Further, the analysis of the combustion properties and the structure of hydrochar can be observed in that, as the HTC process promotes the occurrence of polymerization reactions, the specific surface area gradually reduces, the degree of carbon ordering increases, and the combustion curve moves toward the high-temperature zone and gradually approaches bituminous coal. Since biomass hydrochar has the characteristic of being carbon neutral, blast furnace injection hydrochar can reduce CO2 emissions, and every 1 kg/tHM of biomass hydrochar can reduce CO2 emissions by 1.95 kg/tHM.

  • 68.
    Wang, Shule
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Catalytic fast pyrolysis of softwood under N2 and H2 atmosphere2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bio-oil generated from biomass is becoming one of the most promising alternatives as potential energy sources to replace fossil fuels in the transportation sector. Fast pyrolysis of biomass is one of the most economically feasible ways to produce bio-oil according to recent research on thermochemical conversion of biomass. Upgrading of oils derived from to hydrocarbon fuels requires oxygen removal and molecular weight reduction.  Catalytic cracking and hydrotreating are two efficient processes to upgrade bio-oil. Hydrotreating requires that hydrogen is added in the process to increase the H/C ratio of the product. Normally, catalytic fast pyrolysis and hydrotreating are two separated processes.

    In order to increase the energy efficiency of the process, exploring the fast pyrolysis of biomass with in-situ catalyst under the hydrogen atmosphere, i.e. catalytic hydropyrolysis shall be very interesting, and this is the objective of this work.

    In this work, biomass pyrolysis experiments using softwood have been performed in hydrogen and nitrogen atmospheres with/without catalyst. It was found that in the case of the H2 atmosphere, a higher yield on oil phase and a reduced water production is found. More oxygen was removed as CO and CO2. The catalytic fast pyrolysis (CFP) under H2 atmosphere also produce relatively more PAH (polymer aromatic hydrocarbon) and less MAH (monomer aromatic hydrocarbon) than under N2 atmosphere.

     

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  • 69.
    Wang, Shule
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pyrolysis of Biodegradable Waste for Negative Carbon Emissions2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    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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  • 70.
    Wang, Shule
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Persson, Henry
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Effect of H2 as Pyrolytic Agent on the Product Distribution during Catalytic Fast Pyrolysis of Biomass Using Zeolites2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 8, p. 8530-8536Article in journal (Refereed)
    Abstract [en]

    Bio-oil generated from catalytic fast pyrolysis or hydrotreating processes represents one of the most promising alternatives to liquid fossil fuels. The use of H2 as carrier gas in the pyrolysis of biomass requires further research to study the catalytic fast pyrolysis reactions in the case of using reactive atmosphere. In this work, pyrolysis experiments with lignocellulosic biomass have been performed in a fixed bed reactor in H2 and N2 atmospheres with/without HZSM-5 additions to investigate the influence of the pyrolytic agents during fast pyrolysis of biomass and upgrading of pyrolytic vapors over a zeolitic catalyst. It was found that in a H2 atmosphere, H2 was consumed in both noncatalytic and catalytic pyrolysis processes, respectively. Higher yields of nonaqueous liquids and permanent gases are obtained in a H2 atmosphere compared to a N2 atmosphere. A catalytic pyrolysis process using HZSM-5 in a H2 atmosphere increased the production of polymer aromatic hydrocarbons and suppressed the production of monomer aromatic hydrocarbons compared to similar tests performed in a N2 atmosphere. The results show an overall increased activity of HZSM-5 in the reactive H2 atmosphere compared to a N2 atmosphere.

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  • 71.
    Wang, Shule
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Persson, Henry
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Pyrolysis study of hydrothermal carbonization-treated digested sewage sludge using a Py-GC/MS and a bench-scale pyrolyzer2020In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Fuel, Vol. 262, p. 116335-Article in journal (Refereed)
    Abstract [en]

    The disposal of digested sewage sludge is becoming a global problem. Hydrothermal carbonization (HTC) combined with the pyrolysis of digested sewage sludge was investigated by using a new conversion route for the exploitation of sewage sludge in energy applications. The thermochemical properties of the material were investigated by using HTC pre-treatments, thermogravimetric analyses, pyrolysis tests in Py-GC/MS and a bench-scale fixed bed reactor at temperatures of 450, 550, and 650 °C. It was found that the thermal decomposition of the hydrothermally treated digested sewage sludge takes place in a two-stage reaction. After pyrolysis, the ash in the sample was oxidized in the O2 atmosphere at 900 °C. Therefore, a new characterization method for determination of the non-oxdized ash content and fixed carbon content was proposed. The result from Py-GC/MS shows that the abundance of aromatic hydrocarbons in pyrolytic vapors present a positive correlation with increased temperature. In the bench-scale experiments, the highest HHV of the organic fraction was obtained at 650 °C as 38.46 MJ/kg.

  • 72.
    Wang, Shule
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Wen, Yuming
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Shi, Ziyi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Niedzwiecki, Lukasz
    Wroclaw Univ Sci & Technol, Wybrzeze Stanislawa Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Baranowski, Marcin
    Wroclaw Univ Sci & Technol, Wybrzeze Stanislawa Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Czerep, Michal
    Wroclaw Univ Sci & Technol, Wybrzeze Stanislawa Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Mu, Wangzhong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kruczek, Halina Pawlak
    Wroclaw Univ Sci & Technol, Wybrzeze Stanislawa Wyspianskiego 27, PL-50370 Wroclaw, Poland..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Effect of hydrothermal carbonization pretreatment on the pyrolysis behavior of the digestate of agricultural waste: A view on kinetics and thermodynamics2022In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 431, p. 133881-, article id 133881Article in journal (Refereed)
    Abstract [en]

    Anaerobic digestion is the most promising disposal methods to treat organic waste. Also, a feasible management is necessary for the resulted digestate. Hydrothermal carbonization (HTC) combination with pyrolysis could be a proper solution to use for the treatment of digestate. In this study, the effect of an HTC on the pyrolysis of the digestate of agricultural waste (AWD) was investigated, focusing on the kinetic and thermodynamic aspects. Three model-free methods, including Friedman, KAS, and OFW methods, were used to evaluate the kinetic performance of the total and pseudo pyrolytic reactions of AWD and its hydrochar. Furthermore, kinetic predictions were made to provide more information for further studies. It was found that the HTC treatment decreased the activation energy ranges of the pyrolysis of AWD from 182.9-274.43 kJ/mol to 144.59-205.20 kJ/mol by using the Friedman method. For a more thorough understanding of the effect of HTC treatment on the pyrolysis of AWD, the pyrolysis reactions of AWD and its hydrochar were divided into two pseudoreactions using the Fraser-Suzuki deconvolution method. The mean activation energy of the deduced pseudo 2 pyrolytic reaction of hydrochar was 175.64 kJ/mol, which was 28.11 kJ/mol less than that of AWD. In addition, the Delta H(double dagger )values of the pseudo 2 reactions of AWD and its hydrochar were 197.97 and 169.68 kJ/mol, respectively. The results of kinetic isothermal predictions suggested that the peak temperature for the further research and application of the pyrolysis of AWD and its hydmchar should not be lower than 450 degrees C.

  • 73. Wang, X.
    et al.
    Nordlander, E.
    Thorin, E.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. School of Sustainable Development of Society and Technology, Mälardalen University, 72123 Västerås, Sweden.
    Microalgal biomethane production integrated with an existing biogas plant: A case study in Sweden2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, no SI, p. 478-484Article in journal (Refereed)
    Abstract [en]

    Microalgae are considered as potential sources for biodiesel production due to the higher growth rate than terrestrial plants. However, the large-scale application of algal biodiesel would be limited by the downstream cost of lipid extraction and the availability of water, CO2 and nutrients. A possible solution is to integrate algae cultivation with existing biogas plant, where algae can be cultivated using the discharges of CO2 and digestate as nutrient input, and then the attained biomass can be converted directly to biomethane by existing infrastructures. This integrated system is investigated and evaluated in this study. Algae are cultivated in a photobioreactor in a greenhouse, and two cultivation options (greenhouse with and without heating) are included. Life cycle assessment of the system was conducted, showing that algal biomethane production without greenhouse heating would have a net energy ratio of 1.54, which is slightly lower than that (1.78) of biomethane from ley crop. However, land requirement of the latter is approximately 68 times that of the former, because the area productivity of algae could reach at about 400t/ha (dry basis) in half a year, while the annual productivity of ley crop is only about 5.8t/ha. For the case of Växtkraft biogas plant in Västerås, Sweden, the integrated system has the potential to increase the annual biomethane output by 9.4%. This new process is very simple, which might have potential for scale-up and commercial application of algal bioenergy.

  • 74.
    Yang, Hanmin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Cui, Yuxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Han, Tong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Linda
    RISE Energy Technol Ctr AB, Box 726, SE-94128 Pitea, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    High-purity syngas production by cascaded catalytic reforming of biomass pyrolysis vapors2022In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 322, p. 119501-, article id 119501Article in journal (Refereed)
    Abstract [en]

    A novel pyrolysis followed by in-line cascaded catalytic reforming process without additional steam was developed to produce high-purity syngas from woody biomass. The key to the proposed process is the construction of a cascaded biochar + NiAl2O4 catalytic reforming process in which biochar acts as a pre-reforming catalyst, and NiAl2O4 acts as a primary reforming catalyst. The large oxygenates in the pyro-vapors are deeply cracked in the biochar layer due to the increased residence time in the hot-biochar bed. The remaining small molecules are then reformed with the autogenerated steam from pyrolysis catalyzed by the reduced Ni0 species in the NiAl2O4 catalyst (NiAlO). The results showed that the yield of syngas for the optimized process was 71.28 wt% (including 44.44 mg-H2/g-biomass and 536.48 mg-CO/g-biomass), and the CO2 yield of the process was only 3 kg-CO2/kg-hydrogen. High-purity syngas with 89.47 vol% of (H2 + CO) was obtained, and the gas energy conversion efficiency (GECE) of the process reached 75.65%. The study shows that in the cascaded catalytic reforming process, cracking of the large oxygenates and reforming of the small molecules are promoted sequentially in separated biochar + NiAlO catalyst layers, which maximizes the syngas production and improves the activity and stability of the Ni-based catalyst.

  • 75.
    Ye, Lian
    et al.
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Zhang, Jianliang
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Wang, Guangwei
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Wang, Chen
    Baosteel Res Ctr, 889 Fujin Rd, Shanghai 201900, Peoples R China..
    Mao, Xiaoming
    Baosteel Res Ctr, 889 Fujin Rd, Shanghai 201900, Peoples R China..
    Ning, Xiaojun
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Zhang, Nan
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Teng, Haipeng
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Li, Jinhua
    Univ Sci & Technol Beijing, State Key Lab Adv Met, Beijing 100083, Peoples R China.;Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Beijing 100083, Peoples R China..
    Wang, Chuan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Swerim AB, SE-97125 Luleå, Sweden..
    Feasibility analysis of plastic and biomass hydrochar for blast furnace injection2023In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 263, article id 125903Article in journal (Refereed)
    Abstract [en]

    Hydrothermal carbonization (HTC) technology upgrades combustible waste (CW) to high-quality fuel known as hydrochar. However, there is a research gap regarding the application limit of hydrochar instead of fossil fuels in blast furnaces. In this study, the physical, chemical, and metallurgical properties of hydrochar were thoroughly analyzed. The results showed that gross calorific value, grindability, ignition temperature, explosivity, combustion and gasification all improved by HTC process compared with the waste feedstocks. Moreover, the HTC process can effectively remove harmful elements (K, Na, Cl, and S) from feedstocks into liquid and gas phase without adding other reagents, reducing harmful effects in the blast furnace. Removal rates by HTC were >80% for alkali metals and >73.9% for Cl (reaching 98.18% for polyvinyl chloride hydrochar). The environmental benefit calculation shows that the CO2 emission reduction of replacing bituminous coal with 40% HTC-treated maize straw can reach 94.7 kg/tHM. The annual CO2 reduction can reach 1.7 x 107 kg and the annual coal reduction is 1.5 x 107 kg of a blast furnace. The results showed that hydrochar is a clean energy source compared with fossil fuel alternatives and meets the blast furnace injection requirements.

  • 76.
    Zhang, Qinglin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Dor, L.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Włodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    CFD modeling of municipal solid waste gasification in a fixed-bed plasma gasification melting reactor2011In: Air Waste Manage. Assoc. - Int. Conf. Therm. Treat. Technol. Hazard. Waste Combustors, 2011, p. 252-278Conference paper (Refereed)
    Abstract [en]

    A steady CFD model is developed to simulate the gasification of municipal solid waste (MSW) in a moving-bed Plasma Gasification Melting (PGM) reactor. In this model, the Eulerian-Eulerian multiphase model is conducted, and the solid phase is treated as a plastic fluid. The conservation equations of both gas and solid phases are solved respectively. The momentum conservation equations of the solid phase are simplified by disregarding the interphase forces between gas and solid. Both heterogeneous reactions and homogeneous reactions are defined in this model to express the detailed gasification chemistry inside the reactor. A two-step pyrolysis model was used in this work, and the pyrolysis mechanisms of cellulosic and plastic fractions are considered separately. The predicted results of a base case are compared with the measured data of the trial reactor. The temperature distribution inside the PGM reactor is introduced. Based on the variation of temperature, the whole reaction shaft was divided into five layers. The 2D effect of the reactor is also discussed. The influence of two dimensionless parameters: the equivalence ratio (ER) and dimensionless plasma energy ratio (DPER) are introduced and discussed. With the variation of ER, two typical temperature distributions can be found for PGM reactor. The turning point of these two distributions stands in the ER range 0.120-0.133. This turning point is the optimal operation condition of PGM air gasification. It is also found that when the energy request for gasification is satisfied, further increment of DPER value does not significantly influence the characters of PGM process.

  • 77.
    Zhang, Xiaolei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Micro-reaction Mechanism Study of the Biomass Thermal Conversion Process using Density Functional Theory2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biomass, or bio-energy, is one of the most important alternative energies because of environmental concerns and the future shortage of fossil fuels. Multi-scaled bioenergy studies have been performed in the division of Energy and Furnace Technology, which included studies of macroscopic systems such as systems and reactors, modeling of computational fluid dynamics (CFD), and atomic/molecular level studies. The present thesis focus on the atomic/molecular level that based on quantum chemistry methods.

    The microscopic structure study of biomass is the first and an important step for the investigation of the biomass thermal conversion mechanism. Cellulose, hemicellulose, and lignin are the three most important components for biomass. The atomic interactions among these three main components were studied, including the hydrogen bond linkages between cellulose and hemicellulose, and the covalent bond linkages between hemicellulose and lignin.

    The decomposition of biomass is complicated and includes cellulose decomposition, hemicellulose decomposition, and lignin decomposition. As the main component of biomass, the mechanism of cellulose pyrolysis mechanism was focused on in this thesis. The study of this mechanism included an investigation of the pathways from cellulose to levoglucosan then to lower-molecular-weight species. Three different pathways were studied for the formation of levoglucosan from cellulose, and three different pathways were studied for the levoglucosan decomposition. The thermal properties for every reactant, intermediate, and product were obtained. The kinetics parameters (rate constant, pre-exponential factor, and activation energy) for every elementary step and pathway were calculated. For the formation of levoglucosan, the levoglucosan chain-end mechanism is the favored pathway due to the lower energy barrier; for the subsequent levoglucosan decomposition process, dehydration is a preferred first step and C-C bond scission is the most difficult pathway due to the strength of the C-C bonds.

    The biomass gasification process includes pyrolysis, char gasification, and a gas-phase reaction; Char gasification is considered to be the rate-controlling step because of its slower reaction rate. Char steam gasification can be described as the adsorption of steam on the char surface to form a surface complex, which may transfer to another surface complex, which then desorbs to give the gaseous products (CO and H2) and the solid product of the remaining char. The influences of several radicals (O, H, and OH) and molecules (H2 and O2) on steam adsorption were investigated. It was concluded that the reactivity order for these particles adsorbed onto both zigzag and armchair surfaces is O > H2 > H > OH > O2. For water adsorbs on both zigzag and armchair carbon surfaces, O and OH radicals accelerate water adsorption, but H, O2, and H2 have no significant influence on water adsorption.

    It was also shown that quantum chemistry (also known as molecular modeling) can be used to investigate the reaction mechanism of a macroscopic system. Detailed atomic/molecular descriptions can provide further understanding of the reaction process and possible products.

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