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  • 101.
    Carvalho, Lara
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Furusjö, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ma, Chunyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning: Part 2: Techno-economic analysis2018Inngår i: Energy Journal, ISSN 0195-6574, E-ISSN 1944-9089Artikkel i tidsskrift (Fagfellevurdert)
  • 102.
    Cazot, Mathilde
    KTH, Skolan för kemivetenskap (CHE).
    Empirical Modeling of a full-iron redox flow battery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The need for energy storage is growing to reduce the carbon footprint of electricity

    production. Among the conceivable storage solutions, the redox flow battery (RFB) is

    one of the most promising. The best-researched type is the vanadium flow battery, but

    extensive research is underway to develop a cheaper and more compact system. The full-

    iron redox flow battery is an attractive alternative. A testing module has been developed,

    in order to study the influence of different operating parameters on the system output.

    The experiments highlight that the electrode compression, the stacking of single cells and

    the charge and discharge rates are design key factors and need a precise optimization. A

    35% electrode compression is a good trade-off between pump power losses and low contact

    resistances inside the cell. Single cells undergo a higher self-discharge when they are piled

    up; it is the direct effect of a power leakage called shunt current. The stack design must

    be thought with caution to lessen this power loss. The cycling profile also influence the

    battery performance. The findings confirm that optimizing the charge and discharge rates

    can prolong the system lifespan.

  • 103.
    Chavez Varela, Camila
    KTH, Skolan för kemivetenskap (CHE).
    Elektrokemisk sensor för styrning av bränslecell2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Telecommunication stations for surveillance, wireless communication nodes, and other applications require a main energy source, energy storage unit and a back-up energy system. In the last years, fuel cells have become a good replacement for diesel generators in remote and off-grid applications. Fuel cells provide several advantages like high energy efficiency, no moving parts, silent, scaling is a function of their surface area instead of volume, and reliability. Among the disadvantages there are equipment cost, and difficulties in hydrogen storage. Simplifying the control system of the hydrogen feed control will lower the equipment costs and allow the use of this technology for remote applications where the system is mainly fed by renewable sources, like solar panels, and constant maintenance represents an issue.

    For this purpose the present work investigates the use of a single air-breathing micro fuel cell, used as a sensor cell that can serve to control a fuel cell energy backup system. First the sensor cell was tested under different conditions of temperature, hydrogen humidity, flooding, and hydrogen inlet flow in order to determine optimum operation conditions. Then the sensor cell was connected to the hydrogen outlet of a single cell or stack, receiving the remaining hydrogen that was not consumed by the stack. Further tests were performed by modifying the hydrogen flow, resistance value, and stack current output. During the experiments the sensor cell voltage was monitored. The results show that the micro fuel cell delivers a cell voltage signal sensible to the hydrogen inlet flow, which means it can be used to control the operation of a fuel cell stack. The sensibility of the voltage signal can be modified by means of the resistance connected to its circuit. The stability in time of the voltage signal was achieved by setting the sensor cell to 45 °C or higher.

  • 104. Codan, Lorenzo
    et al.
    Bäbler, Matthäus
    Institute of Process Engineering, ETH Zurich.
    Mazzotti, Marco
    Phase Diagram of a Chiral Substance Exhibiting Oiling Out in Cyclohexane2010Inngår i: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, nr 9, s. 4005-4013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work investigates the ternary phase diagram of the enantiomers of ethyl-2-ethoxy-3-(4-hydroxyphenyl)propanoate (EEHP) in cyclohexane. The enantiomers of EEHP form aconglomerate, and both the pure enantiomer and the racemic mixture exhibit stable oilingout in cyclohexane. Our analysis shows that the ternary phase diagram of such a system assumes a unique structural evolution around the onset temperature of oiling out; that is, we found that the onset of oiling out strictly occurs through the emergence of a second liquid phase of racemic composition. Furthermore, we found that the further evolution of the ternary phase diagram, i.e., above the onset temperature of oiling out, is dictated by the properties of the phase diagrams pure enantiomer/solvent and racemic mixture/solvent. Our theoretical considerations are in excellent agreement with experimental measurements of EEHP in cyclohexane. 

  • 105.
    Cornell, Ann
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Chlorate cathodes and electrode design2014Inngår i: Encyclopedia of applied electrochemistry / [ed] R.F. Savinell,K. Ota,G. Kreysa, Springer, 2014, s. 175-181Kapittel i bok, del av antologi (Fagfellevurdert)
  • 106.
    Cornell, Ann
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Chlorate synthesis cells and technology2014Inngår i: Encyclopedia of applied electrochemistry / [ed] R.F. Savinell, K. Ota, G. Kreysa, Springer, 2014, s. 181-187Kapittel i bok, del av antologi (Fagfellevurdert)
  • 107.
    Cornell, Ann
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Simonsson, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ruthenium Dioxide as Cathode Material for Hydrogen Evolution in Hydroxide and Chlorate Solutions1993Inngår i: Chlor-Alkali and Chlorate Production/New Mathematical and Computational Methods in Electrochemical Engineering / [ed] T. Jeffrey, K. Ota, J. Fenton och H. Kawamoto, Pennington, New Jersey, USA: The Electrochemical Society , 1993, s. 191-Kapittel i bok, del av antologi (Fagfellevurdert)
  • 108.
    Creaser, D.
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology.
    Hudgins, R.R.
    University of Waterloo.
    Silveston, P.L.
    University of Waterloo.
    Oxygen partial pressure effects on the oxidative dehydrogenation of propane1999Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 54, nr 20, s. 4365-4370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of the gas-phase oxygen partial pressure for the oxidative dehydrogenation of propane over a V-Mg-O catalyst was investigated to explore reasons for improved propene yields when dehydrogenation was carried out under periodic operation. Steady-state experiments were performed in which the oxygen partial pressure was varied over a large range at constant propane partial pressures. In addition, the catalyst mass was varied to control the propane conversion so that selectivity and yield could be compared at a constant propane conversion. At the same propane conversion, propene selectivity increased as the partial pressure of oxygen decreased. Thus, propene yields can be improved at steady state by employing low oxygen partial pressures. It is likely that this is the reason for the higher propene yields observed under unsteady-state or periodic operation. It appears that the reaction mechanism must consist of more than one pathway for production of carbon oxides

  • 109.
    Creaser, Derek
    Luleå tekniska universitet.
    Crystal population balance model for nucleation and growth of colloidal TPA-silicalite-11999Inngår i: Porous materials in environmentally friendly processes: Proceedings of the 1st International FEZA Conference, Eger, Hungary, 1-4 September, 1999, Amsterdam: Elsevier, 1999, s. 117-124Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A model describing the crystallization of colloidal TPA-silicalite-1 is developed and tested. The nucleation rate is approximated from experimental data. Crystal growth is surface-reaction limited and the Gibbs-Thomson effect suppresses growth of small crystals, resulting in an induction period. Slow crystal growth during the nucleation period results in the narrow crystal size distribution typically observed for colloidal TPA-silicalite-1 syntheses.

  • 110.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    University of Waterloo.
    Hudgins, R.R.
    Chalmers University of Technology.
    Silveston, P.L.
    Chalmers University of Technology.
    Cyclic operation of the oxidative dehydrogenation of propane1999Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 54, nr 20, s. 4437-4448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cyclic operation of the oxidative dehydrogenation of propane over a V-Mg-O catalyst by the alternate feeding of propane and oxygen gas mixtures was investigated. Generally, the response of the reaction products following a step-change in composition determined the cyclic conditions that resulted in an improved yield of propene. By alternating propane and oxygen with a 1 : 1 cycle split, time-average propene yields higher than steady state could be obtained. The optimal cycle period was about 60 s. This same period provided high propane conversion, as well as high propene selectivity. The cycle split could be varied by shortening the oxygen-feed half of the cycle with little effect on the time-average results. The oxygen half-cycle needed only to be long enough to reoxidize the catalyst. The propane feed scheme was varied by feeding increasing amounts of propane in the oxygen half-cycle. The change in feed scheme caused an increase in the time-average propane conversion that resulted in some further improvement in the propene yield despite some loss in propene selectivity.

  • 111.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, R.R.
    Department of Chemical Engineering, University of Waterloo.
    Silveston, P.L.
    Department of Chemical Engineering, University of Waterloo.
    Transient kinetic analysis of the oxidative dehydrogenation of propane1999Inngår i: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 182, nr 1, s. 264-269Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxidative dehydrogenation of propane was studied using various transient techniques. Results support a redox mechanism in which propane reduces the catalyst, which is reoxidized by gas-phase oxygen. Only lattice oxygen participates in propene formation. Desorbable oxygen is a major source of poor selectivity, although lattice oxygen also causes total oxidation. Consequently, propene selectivity in the absence of gas-phase O2is superior to co-feed, steady-state selectivity at the same propane conversion. Propene selectivity is further improved by increasing the degree of catalyst reduction.

  • 112.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, B.
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, R.R.
    Department of Chemical Engineering, University of Waterloo.
    Silveston, P.L.
    Department of Chemical Engineering, University of Waterloo.
    Transient study of oxidative dehydrogenation of propane1999Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 187, nr 1, s. 147-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kinetics and the mechanism of the oxidative dehydrogenation of propane were investigated using various transient techniques. Results support a redox reaction mechanism in which propane and intermediate products react with lattice oxygen, reducing the catalyst surface, which is reoxidized by gas-phase O2. Partial reduction of the catalyst occurs during the start-up to a steady state. Successive pulsing with C3H8 reduced V5+ in the magnesium ortho-vanadate phase to V2+. Carbon-containing species were observed upon interruption of the reaction, although only minute amounts were formed. Cycling increases the amount of the carbon deposited, but this carbon is reactive and most of it is oxidized in the succeeding O2 pulse. Temperature-programmed oxidation (TPO) experiments on the catalyst used in steady-state operation revealed mainly strongly bound carbonaceous matter on the catalyst, but this carbon deposition did not affect catalyst activity. Thus, adsorbed oxygen is an important source of total combustion. Our experiments show, however, that lattice oxygen also produces total oxidation. Propene selectivity of the reaction in the absence of gas-phase O2 was superior to steady-state selectivity, at the same propane conversion. Propene selectivity could be further improved by increasing the degree of reduction of the catalyst

  • 113.
    Creaser, Derek
    et al.
    Luleå tekniska universitet.
    Andersson, Bengt
    Chalmers University of Technology, Department of Chemical Reaction Engineering.
    Hudgins, Robert
    Department of Chemical Engineering, University of Waterloo.
    Silveston, Peter
    Department of Chemical Engineering, University of Waterloo.
    Kinetic modelling of oxygen dependence in oxidative dehydrogenation of propane2000Inngår i: Canadian Journal of Chemical Engineering, ISSN 0008-4034, E-ISSN 1939-019X, Vol. 78, nr 1, s. 182-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several Mars-Van Krevelen-type redox kinetic models were developed for the catalytic oxidative dehydrogenation of propane and examined for their ability to predict high propene yields at low oxygen/propane feed ratios. The intent in this study was to use modelling as a means of extracting further mechanistic insight from experimental data rather than to identify the best model. Thus, a conventional redox model with a consecutive reaction mechanism and a single pathway for the production of carbon oxides predicts higher propene selectivity but only at the expense of low propane conversion. Experimental data indicated, however, that even at the same propane conversion, propene selectivity increased as the oxygen partial pressure was lowered. Models that successfully describe the data had an additional carbon oxide production path involving the reaction of propane with deeply oxidizing surface oxygen species. Kinetic models and experimental data examined do not fully resolve how these deeply oxidizing surface oxygen species are formed. However, they do reflect the accepted view that lattice oxygen selectively produces propene whereas more weakly bound surface adsorbed oxygen reacts to completely oxidize propane.

  • 114.
    Cuvilas, Carlos Alberto
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal.

    In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours.

  • 115.
    Dahlin, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Na/S balances at Skoghall mill 2015: Balances after reconstruction of the fiber line2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The scope of this master thesis was to investigate how a reconstruction at Skoghall Mill had changed the Na/S balance as well as evaluating how a new chemical plant manufacturing the mill’s chlorine dioxide would affect the balance. This was done by analyzing ingoing and outgoing process streams at the mill for sodium and sulfur and using obtained flow data for the period after the reconstruction. A balance was made to simulate how the system behaved at the time as well as balances simulating different shares of bleached pulp being manufactured. Balances with three possible types of chemical plants were also made, as well as calculations of the operating cost for each type of plant. From the balances and the operating costs it was concluded that the HPA process was the most beneficial for the Na/S balance as well as having the lowest operating cost.

  • 116. Dahlquist, Erik
    et al.
    Mirmoshtaghi, Guilnaz
    Larsson, Eva K.
    Thorin, Eva
    Yan, Jinyue
    Engvall, Klas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Liliedahl, Truls
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Dong, C.
    Hu, X.
    Lu, Q.
    Modelling and simulation of biomass conversion processes2015Inngår i: 2013 8TH EUROSIM CONGRESS ON MODELLING AND SIMULATION (EUROSIM), 2015, s. 506-512Konferansepaper (Fagfellevurdert)
    Abstract [en]

    By utilizing biomass gasification, the energy content of the biomass can be utilized to produce gas to be used for cogeneration of heat and power as well as other energy carriers such as fuels for vehicles. The concept is suitable for application to existing CHP plants as well as for utilizing spent liqour in small scale pulp and paper mills. The introduction would enable flexible energy utilization, use of problematic fuels as well as protects the environment by e.g. avoiding the release of toxic substances. In this paper, the possibilities to develop this concept is discussed. In this paper we compare different gasification processes with respect to what gas quality we get, and how the gasification can be modelled using different modelling approaches, and how these can be combined. Results from simulations are compared to experimental results from pilot plant operations in different scales and with different processes like CFB and BFB Technologies, athmospheric and pressurized, and using steam, air and oxygen as oxidizing media.

  • 117.
    Das, Supriyo K.
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Roychoudhury, Alakendra N.
    Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa.
    Klump, J. Val
    Department of Biological Sciences and Department of Geosciences, Great Lakes WATER Institute, University of Wisconsin-Milwaukee, Milwaukee, USA.
    Elemental (C, N, H and P) and stable isotope (del15 N and del13C) signatures in sediments from Zeekoevlei, South Africa: a record of human intervention in the lake2007Inngår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 39, nr 3, s. 349-360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We used elemental carbon, nitrogen, phosphorus and hydrogen ratios (C/N, N/P and H/C) with total organic carbon (TOC) and total phosphorus (TP) as well as stable carbon and nitrogen isotopes (δ13C and δ15N) to investigate the source and depositional conditions of organic matter in sediments from Zeekoevlei, the largest freshwater lake in South Africa. Typical C/N (10–12), H/C ratios (≥1.7) and δ13Corganic values (−22 to −19‰) together with the increase in TOC concentration indicate elevated primary productivity in lower middle (18–22 cm) and top (0–8 cm) sections of the sediment cores. Seepage of nutrients from a nearby waste water treatment plant, rapid urbanization and heavily fertilized farming in the catchments are responsible for the increased productivity. Consistent with this, measured δ15Norganic values (∼11‰) indicate increased raw sewage input towards the top-section of the core. Although cyanobacterial blooms are evident from the low δ15N values (∼3‰) in mid-section of the core, they did not outnumber the phytoplankton population. Low N/P ratio (∼0) and high TP (100–2,200 mg l−1) support cyanobacterial growth under N limited condition, and insignificant input of macrophytes towards the organic matter pool. Dredging in 1983, caused sub-aerial exposure of the suspended and surface sediments, and affected organic matter preservation in the upper mid-section (12–14 cm) of the core.

  • 118. Dau, H.
    et al.
    Fujita, E.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Artificial Photosynthesis: Beyond Mimicking Nature2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 22, s. 4228-4235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this Editorial, Guest Editors Holger Dau, Etsuko Fujita, and Licheng Sun introduce the Special Issue of ChemSusChem on “Artificial Photosynthesis for Sustainable Fuels”. They discuss the need for non-fossil based fuels, introduce both biological and artificial photosynthesis, and outline various important concepts in artificial photosynthesis, including molecular and solid-state catalysts for water oxidation and hydrogen evolution, catalytic CO2 reduction, and photoelectrochemical systems.

  • 119.
    Dedic, D.
    et al.
    RISE, Innventia.
    Sandberg, T.
    Iversen, T.
    RISE, Innventia.
    Larsson, T.
    RISE, Innventia.
    Ek, M.
    Analysis of lignin and extractives in the oak wood of the 17th century warship Vasa2014Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, nr 4, s. 419-425Artikkel i tidsskrift (Fagfellevurdert)
  • 120.
    Deng, Tengfei
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    Du, Sichen
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    Study of Lime Dissolution Under Forced Convection2012Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 43, nr 3, s. 578-586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dissolution of different CaO cubes under force convection in liquid CaO-"FeO"-SiO2 slag was studied at 1873 K (1600 A degrees C). A linear relationship between normalized lengths and time was obtained after the experiment. It was evidently observed that the removal of the interface layer(s) including 2CaO center dot SiO2 by shear stress was the main mechanism for the dissolution. A stirring rate of approximately 100 rpm was found to be efficient to remove the interface layer(s). The limes with different structures had different dissolution rates.

  • 121.
    Deshpande, Raghu
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    The initial phase of the sodium bisulfite pulping of softwood dissolving pulp2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way.

    Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate.

  • 122.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Potapova, Elisaveta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Weber, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Application of AFM to probe micro- and nano-sized magnetite particle interaction in Ca2+ solution2014Inngår i: Proceedings of the International Summer School on Application of Scanning Probe Microscopy in Life Sciences, Soft Matter and Nanofabrication", Aalborg: River Publishers, 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Natural magnetite is used for producing iron ore pellets, one of the raw materials in steel production. The quality of produced pellets depends on many factors, including the properties of the magnetite concentrate fed to pelletization. To be able to minimize the effect of the variations in feed properties on pellets quality, investigation of magnetite particle interaction with a focus on the surface properties is required. Atomic force microscopy (AFM), using the colloidal probe technique, is a suitable tool for measuring such particle-particle interaction in-situ. Natural particles are usually of micro-sizes (m-s) and have different sizes and shapes, which complicates an accurate investigation of particle interaction with AFM. To overcome such difficulties, synthetic nanoparticles are used instead. Process water chemistry is one of the factors affecting magnetite surface properties. Partial dissolution of calcite and apatite minerals, present in iron ore, results in high Ca2+ concentrations in the process water, which has been shown to have a major effect on the charge of the magnetite particles [1, 2]. The aim of this study was therefore to investigate forces and aggregation between magnetite particles, of micro- and nano-size (n-s), in Ca2+ solutions at various pH values. The spherical monodispersed magnetite nano-sized particles, with a diameter of approx. 10 nm, were synthesized by the precipitation technique [3]. Measurements were performed for m-s probe/m-s layer and m-s probe/n-s layer systems. Natural magnetite particles of 10-30 µm size were glued to NP-S cantilevers (Digital Instruments/Bruker, Santa Barbara, CA) with a measured spring constant of 0.12 N/m. Nano-sized particles were deposited on the glass slides by dip-coating. Roughness (Ra) of the n-s layers was measured with AFM and was about 10 nm for areas 1×1µm2, a representative high-resolution image is shown in Figure 1. Particle interaction was similar for m-s and n-s magnetite particles at pH 4 and 6. At pH 10, the interaction behavior was different due to probable surface modification of natural magnetite particles by ions from process water. The adhesion force for both interacting systems was measured, see ref. [4] for a detailed description of the results. To verify that ϛ-potential measurements could be used to predict the interaction between charged particles (in this case silica and magnetite) in solutions containing inorganic ions, force measurements between n-s magnetite layer and a SiO2 spherical probe (3.5 µm in diameter) were performed and correlated with the ϛ-potential results for these particles in the same solutions. Also, a DLVO simulation was performed to theoretically confirm the experimental interaction based on surface charge trends. An example of the simulated force curves is shown in Figure 2. The interaction between the probe and the magnetite surface was attractive at pH 4 and 6 but became repulsive at pH 8 and 10, which is in agreement with what could be expected from the ϛ-potential results for these particles.

  • 123.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Potapova, Elisaveta
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Weber, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Force interactions between magnetite, silica, and bentonite studied with atomic force microscopy2015Inngår i: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 42, nr 4, s. 319-326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron ore pellets consist of variety of mineral particles and are an important refined product used in steel manufacturing. Production of high-quality pellets requires good understanding of interactions between different constituents, such as magnetite, gangue residues, bentonite, and additives. Much research has been reported on magnetite, silica, and bentonite surface properties and their effect on pellet strength but more scant with a focus on a fundamental particle–particle interaction. To probe such particle interaction, atomic force microscopy (AFM) using colloidal probe technique has proven to be a suitable tool. In this work, the measurements were performed between magnetite–magnetite, bentonite–magnetite, silica–bentonite, and silica–magnetite particles in 1 mM CaCl2 solution at various pH values. The interaction character, i.e., repulsion or attraction, was determined by measuring and analyzing AFM force curves. The observed quantitative changes in interaction forces were in good agreement with the measured zeta-potentials for the particles at the same experimental conditions. Particle aggregation was studied by measuring the adhesion force. Absolute values of adhesion forces for different systems could not be compared due to the difference in particle size and contact geometry. Therefore, the relative change of adhesion force between pH 6 and 10 was used for comparison. The adhesion force decreased for the magnetite–magnetite and bentonite–silica systems and slightly increased for the magnetite–bentonite system at pH 10 as compared to pH 6, whereas a pronounced decrease in adhesion force was observed in the magnetite–silica system. Thus, the presence of silica particles on the magnetite surface could have a negative impact on the interaction between magnetite and bentonite in balling due to the reduction of the adhesion force.

  • 124.
    Dobryden, Illia
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Yang, Xiaofang
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Weber, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Interaction forces between surface modified magnetite particles in aqueous solution2011Konferansepaper (Annet vitenskapelig)
  • 125.
    Duan, Ran
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Acid-Catalyzed Synthesis of Foamed Materials from Renewable Sources2014Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, nr 45, s. 17597-17603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, lightweight biobased foamed materials were successfully synthesized by the modification of renewable polysaccharides, such as starch and microcrystalline cellulose. Low-cost and nontoxic organic acids were utilized as catalysts in the first-step esterification reaction of the synthesis. The effects of different reaction conditions on the water absorbency and weight loss of freeze-casted polysaccharide–citrate–chitosan foams are discussed. Physical properties, such as pore-size distributions and compressive stress–strain curves, of the foams were determined. The characterization results show that the amide bonds formed between the carboxylic acid groups of polysaccharide–citrate and the amino groups of chitosan are crucial to the foamed material’s performance.

  • 126.
    Duman, Isa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Coke characterization on HZSM-5, Fe/ZSM-5, Ni/ZSM-5, and Fe-Ni/ZSM-5 from Catalytic Fast Pyrolysis of Biomass2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The combustion of fossil fuels has for a long time been a problem from an environmental and sustainability point of view, especially when it comes to the emissions of atmospheric carbon dioxide. The environmental concern has for instance shifted the attention towards finding new sustainable alternatives for producing chemicals and fuels, as a substitute to today’s dependence on fossil based crude oil. Catalytic Fast Pyrolysis of biomass is an excellent way to produce valuable chemicals and fuels using renewable resources. However, the process has some drawbacks, for example rapid deactivation of catalysts due to coke formation. Little is known about the characteristics of the formation of catalytic coke from pyrolysis processes, which should be a vital concern in future industrial processes. This thesis is dedicated to investigate the chemical coke characteristics found on zeolitic catalysts. Four zeolites of the type ZSM-5 were chosen for this thesis to deduce any chemical differences in the coke: HZSM-5, Fe/ZSM-5, Ni/ZSM-5, and Fe-Ni/ZSM-5. The coke were characterized by TGA, GC/MS, and FTIR.

    The results show that Fe/ZSM-5 produced the highest amount of coke compared to the other zeolites, where HZSM-5 had the lowest amount of coke formation. The coke consisted mainly of aromatic and cyclic hydrocarbons, dominated by polycyclic aromatic hydrocarbons. The content of ketones and alcohols in the coke found on HZSM-5 was higher compared to the metal-doped zeolites, while the formation of naphthalenes was lower. The FTIR results also show that coke was mainly comprised of aromatic hydrocarbons. However, traces of alkanes and alkenes reveal that the coke may have a greater variety than the GC/MS analysis suggests.

    The results show interesting features when metals are introduced to the zeolitic structure, at least when it comes to coke formation. The metal-doping of zeolites certainly seems to alter the chemistry of the catalytic reactions, compared to the parent zeolite. The differences in the chemical characteristics found in the coke are certainly interesting, and it could mean that the chemistry of the bio-oil also varies depending on the metals chosen for the ZSM-5. The new properties that metals introduce to the parent catalyst may open up new possibilities in industrial catalytic processes, and allow industries to take more advantage of the great benefits that biomass has to offer.

  • 127.
    Dyhr, Kurt
    Luleå tekniska universitet.
    Zeolites in pulp bleaching1998Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 128.
    Dyhr, Kurt
    et al.
    Luleå tekniska universitet.
    Sterte, Johan
    Effects of zeolite addition on the manganese catalyzed decomposition of hydrogen peroxide1999Inngår i: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 6, nr 4, s. 275-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Manganese catalyzed decomposition of hydrogen peroxide in the presence of various zeolites was investigated at different pH values, Mn concentrations and zeolite: Mn ratios. Depending upon the level of these parameters the zeolites studied displayed both catalytic and inhibitive effects on the rate of decomposition. At a high pH (10.8) Mordenite 10A in a twofold excess on an ion-exchange capacity basis acted as an inhibitor whereas the other zeolites had little or no effect on the reaction rate. At a lower pH (9.0) zeolite A when added in large excess resulted in a remarkable inhibitive effect whereas the same zeolite resulted in a promotion of the catalytic action of manganese at an intermediate pH (9.9). The complex catalytic nature of zeolite-peroxide-Mn systems is discussed.

  • 129.
    Dyhr, Kurt
    et al.
    Luleå tekniska universitet.
    Sterte, Johan
    Use of zeolites in hydrogen peroxide bleaching of pulp1998Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 13, nr 4, s. 257-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of zeolites for inhibition of transition metal catalyzed decomposition of hydrogen peroxide was evaluated. A number of zeolite types (A, P, Y, and mordenite 10A), with different crystal structures and ion-exchange characteristics, were tested as additives in bleaching experiments using a mechanical (TMP) pulp and a chemical (kraft) pulp. For the mechanical pulp, addition of zeolites A and P at a moderate alkali charge resulted in a significant improvement of the bleaching performance as signified by an increase in both brightness and residual peroxide content of the bleaching liquor. The other zeolite types studied did not give any positive effects at the bleaching conditions used. For the chemical pulp, no significant improvements were obtained at any alkali charge using zeolite A as an additive. At high alkali charges, addition of zeolite A resulted in a substantially lower brightness than that reached in a zeolite free reference experiment. The effects of zeolite addition upon the bleaching of pulp are complex and dependent upon a number of factors. Parameters of great importance are the bleaching pH, consistency and the zeolite type and charge

  • 130.
    Edin, M.
    et al.
    Luleå tekniska universitet.
    Ödberg, Lars
    Luleå tekniska universitet.
    Sterte, Johan
    Adhesion of hot melt adhesives to linerboard2002Inngår i: Proceedings: 2002 Progress in Paper Physics Seminar, September 8 - 13, 2002, Wm. Noah Allyn International Center for Training and Development, Skaneateles Falls, New York, [Syracuse, New York], U.S.A / [ed] D. Steven Keller, Syracuse, NY: SUNY-ESF , 2002, s. 27-Konferansepaper (Annet vitenskapelig)
  • 131.
    Edin, M.
    et al.
    Luleå tekniska universitet.
    Ödberg, Lars
    Luleå tekniska universitet.
    Sterte, Johan
    Hot melt adhesion of liner sized with alkylketene dimer2002Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, nr 4, s. 395-400Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of the sizing agent alkylketene dimer (AKD) on hot melt adhesive joint strength was studied. By varying the amount of AKD added, and varying the degrees of beating and calendering, sheets with different surface energies, surface structures, and strength properties, were obtained. The sheets were adhesively bonded using a commercial packaging machine, and the adhesive joints were tested in T-peel and creep tests. Contact angles, water absorptivity, delamination strength, density, and surface roughness were measured to study the way in which the addition of AKD, beating, and calendering influence these paper properties. The results indicate that neither sizing with AKD nor calendering or beating have any pronounced effect on the adhesive joint strength, at least not under the conditions used. Most of the differences observed are within the limits of the experimental error. The greatest influence on the joint strength was observed when samples had been stored at low temperature.

  • 132.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lågdimensionella material för generering av solbränsle2017Konferansepaper (Annet vitenskapelig)
  • 133. Ehrl, Lyonel
    et al.
    Soos, Miroslav
    Morbidelli, Massimo
    Bäbler, Matthäus
    Institute of Process Engineering, Dept. of Mechanical and Process Engineering, ETH Zurich.
    Dependence of Initial Cluster Aggregation Kinetics on Shear Rate for Particles of Different Sizes Under Turbulence2009Inngår i: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 55, nr 12, s. 3076-3087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Initial aggregation kinetics for three particle sizes and broad range of Péclet numbers were investigated under turbulent conditions in stirred tank. This allowed us to observe the transition from diffusion-controlled to purely shear-induced aggregation. The evolution of the root-mean-square radius of gyration, zero-angle intensity of scattered light, and obscuration was obtained by small-angle static light scattering. For a given particle sizethe measured evolution of all integral quantities obtained for various volume averageshear rates (G), scales with a dimensionless time, τexp = αexp × (G) × φ × t. The experimentally obtained aggregation efficiency αexp, follows the power law αexp = Pe-n, where Pe is the primary particle Péclet number. With increasing particle size a decrease in n is observed in accordance with theory and literature data. As previously predicted by population balance equation simulations three aggregationregimes were observed experimentally.

  • 134.
    Einvall, Jessica
    et al.
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Sanati, Mehri
    Växjö universitet, Fakulteten för matematik/naturvetenskap/teknik, Institutionen för teknik och design. Bioenergiteknik.
    Impact of fly ash from biomass gasification on deactivation of reforming catalyst2006Inngår i: 12th Nordic Symposium in Catalysis-May 28-30-Trondheim-Norway, 2006, s. 132-133Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 135.
    Ek, Mattias
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    Shu, Q. F.
    van Boggelen, J.
    Sichen, Du
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Mikro-modellering.
    A new approach towards dynamic modelling of dephosphorisation in converter process2012Inngår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 39, s. 77-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new approach was made to model the dephosphorisation process in a 300 tons basic oxygen furnace converter with three argon gas inlets. The main feature of the new approach was to utilise the velocity vectors obtained by computational fluid dynamics (CFD) simulation in a standalone model. The CFD simulation was carried out using commercial software COMSOL Multiphysics. In the standalone model, the steel melt domain was sliced into 1000 cells. The calculated velocity vector in each cell was assumed constant. Based on the imported velocity vectors from the CFD calculation, the mass transfer of carbon and phosphorus was calculated by taking into account the slag-metal reactions. The mass exchange between slag and metal was considered to be dominated by the metal droplet formation due to the oxygen jet. The convergence of the model calculation and the promising comparison between the model prediction and the industrial data strongly suggested that the proposed approach would be a powerful tool in dynamic process control. As a preliminary step, the model only simulated the process after the formation of slag-metal-gas emulsion. Note that the present work is intended to establish a structure of the model. More precise descriptions of other process aspects need to be included before the model can be practically employed in a dynamic controlling system.

  • 136.
    Ekbåge, Daniel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Process modelling based on data from an evaporation and a CTMP process: Analysis of energy efficiency and process variability2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The manufacture of pulp and paper is an energy intensive process configured of several unit processes that shape a network of flows of wood chips, chemical pulp, mechanical pulp, paperboard, steam and other important components. Improved energy efficiency supports sustainability of the process and the products. With the purpose of monitoring and controlling, information from multiple process and quality variables is continuously collected in the process data system. This data may be of time-varying nature and the variability might potentially span from seasonal to time-wise shorter variations and there are in some cases a need for predicting certain properties.

    By applying models based on process data there is a potential to increase the knowledge of the process characteristics, investigate the applicability of predictive models and identify optimization opportunities. Based on data from an evaporation and a CTMP plant, process models have been developed with the aim of improving the energy efficiency and studying process variability.  

  • 137.
    Ekman, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Martin-Torres, Javier
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Emami, Reza
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Törlind, Peter
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Innovation och Design.
    Kuhn, Thomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Nilsson, Hans
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Minami, Ichiro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Öhrwall Rönnbäck, Anna
    Gustafsson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Zorzano Mier, Maria-Paz
    Milz, Mathias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Parida, Vinit
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Innovation och Design.
    Behar, Etienne
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Wolf, Veronika
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Dordlofva, Christo
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Innovation och Design.
    Mendaza de Cal, Maria Teresa
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Jamali, Maryam
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Roos, Tobias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Ottemark, Rikard
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Nieto, Chris
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Soria Salinas, Álvaro Tomás
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Vázquez Martín, Sandra
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Nyberg, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Neikter, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Lindwall, Angelica
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Innovation och Design.
    Fakhardji, Wissam
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Projekt: Rymdforskarskolan2015Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The Graduate School of Space Technology

  • 138.
    El Azab, Ahmad
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Modeling of Biofuel Combustion2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fortum Scandinavia’s future challenge is to develop the district heating system to be able to meet costumers and societies demand for affordable and sustainable heating. One way to reach those goals is to use biofuels in the coal-fired power and heating plant KVV6 at Värtaverket in Stockholm. Different types of biofuels could be used but it is important to understand their combustion processes and the chemical characteristics of the biofuels. During this project olive stone cross, palm shell kernel (PKS), lignin and the liquid biofuel crude glycerol where tested in a lab-scale combustor fitted with a quartz cylinder. The combustion process was filmed and the results showed that palm shell kernel is a very promising fuel to be used instead of coal, with glycerol used as a substituted for water to make paste, which is needed to be able to pump the fuel in to the PFBC at KVV6. The biofuels where also tested for alkali where the results showed that PKS have very low amounts of alkali while the glycerol have very high amounts which would be unfavorable in the PFBC at KVV6. Olive stone cross and lignin are also good substitutes for coal but they do have higher amounts of alkali compared to PKS.

  • 139.
    Elm Svensson, Erik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Nanomaterials for high-temperature catalytic combustion2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Katalytisk förbränning är en lovande teknik för användning vid kraftgenerering, särskilt för gasturbiner. Genom att använda katalytisk förbränning kan man nå mycket låga emissioner av kväveoxider (NOX), kolmonoxid (CO) och oförbrända kolväten (UHC) samtidigt, vilket är svårt vid konventionell förbränning. Förutom att man erhåller låga emissioner, kan katalytisk förbränning stabilisera förbränningen och kan därmed användas för att uppnå stabil förbränning för gaser med låga värmevärden.

    Denna avhandling behandlar huvudsakligen högtemperaturdelen av den katalytiska förbränningskammaren. Kraven på denna del har visat sig svåra att nå. För att den katalytiska förbränningskammaren ska kunna göras till ett alternativ till den konventionella, måste katalysatorer med bättre stabilitet och aktivitet utvecklas.

    Målet med denna avhandling har varit att utveckla katalysatorer med högre aktivitet och stabilitet, lämpliga för högtemperaturdelen av en katalytisk förbränningskammare för förbränning av naturgas.

    En mikroemulsionsbaserad framställningsmetod utvecklades för att undersöka om den kunde ge katalysatorer med bättre stabilitet och aktivitet. Bärarmaterial som är kända för sin stabilitet, magnesia och hexaaluminat, framställdes med den nya metoden. Mikroemulsionsmetoden användes också för att impregnera de framställda materialen med de mer aktiva materialen perovskit (LaMnO3) och ceriumdioxid (CeO2). Det visade sig att mikroemulsionsmetoden kan användas för att framställa katalysatorer med bättre aktivitet jämfört med de konventionella framställningsmetoderna. Genom att använda mikroemulsionen för att lägga på aktiva material på bäraren erhölls också en högre aktivitet jämfört med konventionella beläggningsstekniker.

    Eftersom katalysatorerna ska användas under lång tid i förbräningskammaren utfördes också en åldringsstudie. Som jämförelse användes en av de mest stabila materialen som rapporterats i litteraturen: LMHA (mangan-substituerad lantan-hexaaluminat). Resultaten visade att LMHA deaktiverade mycket mer jämfört med flera av katalysatorerna innehållande ceriumdioxid på hexaaluminat som framställts med den utvecklade mikroemulsionstekniken.

  • 140.
    El-Seedi, Hesham R.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi. Uppsala University, Sweden.
    Azeem, Muhammad
    KTH, Skolan för kemivetenskap (CHE), Kemi. COMSATS Institute of Information Technology, Pakistan.
    Khalil, Nasr S.
    KTH, Skolan för kemivetenskap (CHE), Kemi. Agricultural Research Centre, Egypt.
    Sakr, Hanem H.
    Khalifa, Shaden A. M.
    Awang, Khalijah
    Saeed, Aamer
    Farag, Mohamed A.
    AlAjmi, Mohamed F.
    Pålsson, Katinka
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Essential oils of aromatic Egyptian plants repel nymphs of the tick Ixodes ricinus (Acari: Ixodidae)2017Inngår i: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 73, nr 1, s. 139-157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to the role of Ixodes ricinus (L.) (Acari: Ixodidae) in the transmission of many serious pathogens, personal protection against bites of this tick is essential. In the present study the essential oils from 11 aromatic Egyptian plants were isolated and their repellent activity against I. ricinus nymphs was evaluated Three oils (i.e. Conyza dioscoridis L., Artemisia herba-alba Asso and Calendula officinalis L.) elicited high repellent activity in vitro of 94, 84.2 and 82%, respectively. The most active essential oil (C. dioscoridis) was applied in the field at a concentration of 6.5 A mu g/cm(2) and elicited a significant repellent activity against I. ricinus nymphs by 61.1%. The most repellent plants C. dioscoridis, C. officinalis and A. herba-alba yielded essential oils by 0.17, 0.11 and 0.14%, respectively. These oils were further investigated using gas chromatography-mass spectrometry analysis. alpha-Cadinol (10.7%) and hexadecanoic acid (10.5%) were the major components of C. dioscoridis whereas in C. officinalis, alpha-cadinol (21.2%) and carvone (18.2%) were major components. Artemisia herba-alba contained piperitone (26.5%), ethyl cinnamate (9.5%), camphor (7.7%) and hexadecanoic acid (6.9%). Essential oils of these three plants have a potential to be used for personal protection against tick bites.

  • 141. Enestam, Sonja
    et al.
    Mäkelä, Kari
    Backman, Rainer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Hupa, Miko
    Occurrence of Zinc and Lead in Aerosols and Deposits in the Fluidized-Bed Combustion of Recovered Waste Wood. Part 2: Thermodynamic Considerations2011Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, nr 4, s. 1970-1977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, which is the second part in a series of two, multi-phase, multi-component equilibrium calculations were used to study the chemistry and deposition behavior of lead and zinc in the combustion of recovered waste wood (RWW). Particular attention was paid to the deposition behavior in different parts of the boiler under varying flue gas and material temperature conditions. In addition, the influence of fuel composition was considered by studying three different fuel compositions. The results from the calculations were compared to experimental results from two measurement campaigns, whose goal was to experimentally determine the distribution and speciation of zinc and lead compounds in aerosol particles and deposits in the fluidized-bed combustion of RWW. The results from the experimental work are presented in part 1 (10.1021/ef101478n) of this work.

  • 142.
    Engström, Andreas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Mouzon, Johanne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Córdoba, J.M.
    Instituto de Ciencia de Materiales de Sevilla, Código del Centro.
    Tegman, Ragnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Synthesis of a TiCN – SiC polyhedron and elongated crystals nanopowder at low nitrogen concentration2012Inngår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 81, s. 148-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    At room temperature diluted TiCl4 and CCl4 were reduced by sodium particles and mixed with a polycarbomethylsilane (PCS) solution to yield a precursor. It was dried and subsequently annealed at 1300 °C, 1400 °C and 1450 °C in a tube furnace using argon with 10 ppm N2. After the 1450 °C annealing a nanocrystalline powder of TiC0.5 N0.5–SiC polyhedron and elongated crystals was obtained. At the low nitrogen concentration during annealing a gradual nitration is proposed. It is promoted by carbon gaseous species, precursor oxidation, a sufficient temperature and a summarised nitrogen surplus compared to the titanium and carbon amount.

  • 143.
    Engström, V.
    et al.
    Luleå tekniska universitet.
    Mihailova, Boriana
    Bulgarian Academy of Sciences.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holmgren, Allan
    Sterte, Johan
    The effect of seed size on the growth of silicalite-1 films on gold surfaces2000Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 38, nr 1, s. 51-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silicalite-1 films grown on gold surfaces seeded with colloidal crystals with a size of 60, 165 and 320 nm were investigated by reflection–absorption infrared spectroscopy, scanning electron microscopy and X-ray diffraction in order to follow up the formation of nano-scale defects and to determine the optimal synthesis conditions for preparation of silicalite-1 films with a low concentration of defects. Using 60-nm-sized colloidal crystals, the seeding method was capable of producing silicalite-1 films with low concentrations of defects and with thicknesses ranging from 100 to 300 nm, which are predominantly oriented with the a-axis perpendicular to the surface. Hydrothermal treatment times of the 60-nm-seeded surfaces longer than 36 h as well as the seeding with 165 or 320 nm colloidal crystals substantially enhanced the formation of defects in the films.

  • 144.
    Engström, Vania
    Luleå tekniska universitet.
    A vibrational spectroscopy study of the growth of silicate-1 films on noble metal surfaces1999Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main objective of this thesis was to acquire a better understanding of the mechanisms involved in the preparation of Silicalite-1 films in general and on gold surfaces in particular. Molecular sieve films on gold surfaces were prepared using the seed film method. The deficiency of negative charge on a gold surface in aqueous solution was overcome by a coupling agent (gamma-mercaptopropyltrimethoxysilane or sodium hydrosulfide). The resulting negatively charged surface was modified by a cationic polymer, facilitating the adsorption of negatively charged colloidal silicalite-1 seed crystals. The seed crystals were grown into a continuous molecular sieve film during hydrothermal treatment in synthesis solution. Reflection absorption infrared spectroscopy was found to be an excellent method to gain insight about the structures formed after each step in this preparation procedure. The recorded vibrational spectra were compared with vibrational modes calculated from the dynamic matrix of the clusters concidered. These comparisons showed that the organic coupling agent was oriented with the methylene chain perpendicular to the gold surface, the cationic polymer introduces disorder in the silane layer, the silanol groups predominantly form 6-membered puckered Si-O rings upon condensation and that linear defects in the films are formed during the hydrothermal treatment. The effects of seed size and hydrothermal treatment time on the formation of linear defects were investigated.

  • 145.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Characterization of kiln feed limestone by dynamic heating rate thermogravimetry2016Inngår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 147, s. 31-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quicklime is a product rich in calcium oxide produced in industrial kilns. The process involves thermal decomposition of minerals with high content of calcium carbonate. The kiln feed properties vary with the geological formation from where the mineral is quarried or mined. Characterization of feed properties is necessary to achieve an optimized kiln production. In this work the decomposition of four different types of calcite ore was investigated by comparing conventional constant heating rate and dynamic heating rate thermogravimetric methods. The conclusion of this work is that the conventional method always "overshoots" the calcination temperature when continuously heating during calcination compared to the dynamic rate method that resembles the kiln by holding temperatures constant during the calcination event. This justifies the used of the dynamic rate method. By a correct experimental parameter setup the dynamic rate method can be adapted for individual kilns and feed fractions, giving new additional value to the kiln operator and increasing the high value use of limestone deposits. This new method to characterize calcination properties of kiln feed materials can be utilized in normal kiln operations and when developing new mixes of different quality limestone. The results show differences when comparing the methods and different materials even though CaCO3 is present only as calcite. In addition, the dynamic rate method is faster than the conventional method. Besides quicklime production the method can also be applied in other industries calcining limestone, such as cement clinker production.

  • 146.
    Eriksson, Matias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Sustainability measures in quicklime and cement clinker production2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis investigates sustainability measures for quicklime and cement clinker production. It is the aim of this thesis to contribute to the effort of creating a more sustainable modus of industrial production.

    The methods used comprises process simulations through multicomponent chemical equilibrium calculations, fuel characterization and raw materials characterization through dynamic rate thermogravimetry.

    The investigated measures relate to alternative fuels, co-combustion, oxygen enrichment, oxyfuel combustion, mineral carbonation and optimizing raw material mixes based on thermal decomposition characteristics.

    The predictive multicomponent chemical equilibrium simulation tool developed has been used to investigate new process designs and combustion concepts. The results show that fuel selection and oxygen enrichment influence energy efficiency, and that oxyfuel combustion and mineral carbonation could allow for considerable emission reductions at low energy penalty, as compared to conventional post-combustion carbon dioxide capture technologies. Dynamic rate thermogravimetry, applied to kiln feed limestone, allows for improved feed analysis with a deeper understanding of how mixing of different feed materials will affect the production processes. The predictive simulation tool has proven to be of practical value when planning and executing production and full scale campaigns, reducing costs related to trial and error.

    The main conclusion of this work is that several measures are available to increase the sustainability of the industry.

  • 147.
    Escalera, Edwin
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Garcia, Gustavo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Terán, R
    Chemistry Department, San Simon University.
    Tegman, Ragnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Odén, Magnus
    The production of porous brick material from diatomaceous earth and Brazil nut shell ash2015Inngår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 98, s. 257-264Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Diatomaceous earth was mixed with Brazil nut shell ash (BNS ash) in different amounts between 0 and 30 wt% and sintered at temperatures between 750 and 950 °C. The BNS ash contains 33 wt% K2O and 11 wt% CaO mainly in carbonate form. The addition of BNS ash into the diatomaceous earth caused significant changes of the microstructure after sintering. The BNS ash addition produces lightweight porous bricks with acceptable strength at lower sintering temperature. The best combination of strength and porosity was achieved for a mixture of 10 wt% of BNS ash in the diatomaceous earth sintered at 850 °C. The achieved high porosity was 49%, density 1.06 g/cm3, thermal conductivity 0.20 W/(m K) and the compressive strength was 8.5 MPa.

  • 148.
    Fagerström, Jonathan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Fine particle emissions and slag formation in fixed-bed biomass combustion: aspects of fuel engineering2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    There is a consensus worldwide that the share of renewable energy sources should be increased to mitigate climate change. The strive to increase the renewable energy fraction can partly be met by an increased utilization of different biomass feedstocks. Many of the "new" feedstocks puts stress on certain challenges such as air pollution emissions and operation stability of the combustion process. The overall objective was to investigate, evaluate, and explain the effects of fuel design and combustion control - fuel engineering - as primary measures for control of slag formation, deposit formation, and fine particle emissions during biomass combustion in small and medium scale fixed-bed appliances. The work in this thesis can be outlined as having two main focus areas, one more applied regarding fuel engineering measures and one more fundamental regarding the time-resolved release of ash forming elements, with particular focus on potassium.

    The overall conclusion related to the abatement of particle emissions and slag formation, is that the release of fine particle and deposit forming matter can be controlled simultaneously as the slag formation during fixed-bed biomass combustion. The methodology is in this perspective denoted “fuel engineering” and is based on a combined approach including both fuel design and process control measures. The studies on time-resolved potassium release showed that a Macro-TG reactor with single pellet experiments was a valuable tool for studying ash transformation along the fuel conversion. The combination of dedicated release determinations based on accurate mass balance considerations and ICP analysis, with phase composition characterization by XRD, is important for the understanding of potassium release in general and time-resolved data in particular. For wood, the results presented in this work supports the potassium release mechanism from "char-K" but questions the previously suggested release mechanism from decomposition of K-carbonates. For straw, the present data support the idea that the major part of the potassium release is attributed to volatilization of KCl. To further explore the detailed mechanisms, the novel approach developed and applied in this work should be complemented with other experimental and analytical techniques.

    The research in this thesis has explored some of the challenges related to the combined phenomena of fuel conversion and ash transformation during thermochemical conversion of biomass, and has contributed with novel methods and approaches that have gained new knowledge to be used for the development of more effective bioenergy systems.

  • 149.
    Fagerström, Jonathan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Nyström, Robin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Broström, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Dan, Boström
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Boman, Christoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Fuel conversion of large samples in a thermogravimetric analyzer set-up: method description and applications2011Inngår i: 19th European Biomass Conference and Exhibition: From Research to Industry and Markets, 2011Konferansepaper (Fagfellevurdert)
  • 150.
    Faisal, Abrar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Recovery of biochemicals from ABE fermentation broths using MFI adsorbents: A comparison between traditional beads and a structured adsorbent2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Energy demands of the world are ever increasing in this industrial era. Over reliance on petroleum-based fuels has a negative impact on the environment. In addition, with depleting reservoirs of fossil fuels, the need for new, sustainable fuels and chemicals is more urgent than ever. One such chemical is 1-butanol (or simply butanol), which has great potential as a gasoline substitute because of its favorable fuel properties. Butanol can be produced from acetone, butanol and ethanol (ABE) fermentation using e.g. Clostridium acetobutylicum. However, the concentration of butanol in fermentation in the resulting broth is limited to ca. 20 g/L due to its toxicity for microorganisms. Butyric acid is a precursor to butanol, which is produced prior to butanol in ABE fermentation. Butyric acid is an important industrial chemical, which can be further derived into a number of commercial compounds e.g. acetate butyrate, butyl acetate and butanol. In this study, hydrophobic MFI zeolite was evaluated for the recovery of butanol and butyric acid from both model and real fermentation broths. Adsorption isotherms of the main components viz. butanol, butyric acid, acetone, ethanol and acetic acid were determined at room temperature. The experimentally determined isotherms were than fitted to the Langmuir adsorption model with good fit. Butyric acid and butanol showed high affinity for the hydrophobic MFI zeolite. The butanol saturation loading was determined to be 0.11 g-butanol/g-zeolite for both binary (water-butanol) and multicomponent (ABE) model solutions in concert to previous findings. However, adsorption of butyric acid was found to be strongly pH dependent, with high adsorption below and little adsorption above the pKa value of the acid. Thermal desorption experiments showed that adsorbed water and butanol starts to desorb at 100 °C and 118 °C respectively. The hydrophobic MFI zeolite was also evaluated for the recovery of bio-butanol from real fermentation broth produced by Clostridium acetobutylicum using xylose recovered from birch Kraft black liquor. The results showed that even in the presence of phenolic compounds, which may interfere with the adsorption of butanol, the zeolite was very selective towards the targeted molecules i.e. butyric acid and butanol. In addition, butyric acid adsorption could be suppressed by increasing the pH of the solution to facilitate better selectivity towards butanol. The selectivity of butanol over acetone and ethanol was found to be 25 and 250 respectively at pH 8 and room temperature for batch adsorption experiments. A structured adsorbent in the form of steel monolith coated with a silicalite-1 film was prepared. X-ray diffractometry and scanning electron microscopy was used to characterize the adsorbent. The performance of the structured adsorbent was evaluated by performing breakthrough experiments at room temperature using model ABE fermentation broths and the performance was compared with that of traditional adsorbents in the form of beads. The structured silicalite-1 adsorbent required less amount of solution to achieve saturation as compared to the commercial ZSM-5 beads. Desorption studies showed that a high quality butanol product with purity up to 97% for butanol-water system and 89% for the ABE system can be recovered with the structured silicalite-1 adsorbent. The commercial ZSM-5 beads also showed good selectivity but the concentration of butanol in the desorbed product was limited to 71% for the butanol-water system and 61% for ABE system, probably as a result of entrained liquid between the beads.

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