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  • 251.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Korttidslagring av värme: mätning och utvärdering av ett el-baserat ackumulatorsystem1988Rapport (Annet vitenskapelig)
  • 252.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Phenomena that effect the thermal stratification in water heat storage's1991Inngår i: IEA-Workshop on Thermal Energy Storage and Low Energy Buildings: Tutzing, Germany 18 - 19 June 1991, München: Universität München , 1991Konferansepaper (Fagfellevurdert)
  • 253.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Temperatures and velocities in a thermally stratified water heat storage1988Inngår i: Proceedings, 4th International Conference on Energy Storage for Building Heating and Cooling: JIGASTOCK 88 / [ed] J. Despois, French Agency for Energy Control, AFME , 1988, Vol. 1, s. 161-166Konferansepaper (Fagfellevurdert)
  • 254.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    The establishing of a gradient zone and its effect on the velocity field in a water heat storage1989Inngår i: Proceedings / North Sun '88 - Solar Energy at High Latitudes / [ed] Lars Broman; Mats Rönnelid, Stockholm: Statens råd för byggnadsforskning , 1989Konferansepaper (Fagfellevurdert)
  • 255.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Värmeleveranserna till Piteås fjärrvärmenät: resultat av mätningar som genomförts vid Backens hetvattencentral och Assi Kraftliner under 19901992Rapport (Annet vitenskapelig)
  • 256.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Gren, Per
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Benckert, Lars
    Temperatures and velocities near the gradient zone in a short term water heat storage1991Inngår i: Proceedings: Thermastock '91, International Conference on Thermal Energy Storage, Scheveningen, 13 - 16 May 1991, Utrecht: Novem , 1991Konferansepaper (Fagfellevurdert)
  • 257.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Tiberg, Sven-Erik
    Veber, Pascal
    Luleå tekniska universitet.
    Use of video-based Particle Image Velocimetry technique for studies of velocity fields in a water heat storage vessel1995Inngår i: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 18, nr 5, s. 383-388Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A video-based Particle Image Velocimetry technique has been developed. The technique is particularly suitable for measurement of small velocities, below 3 cm/s. It has proved to be useful for the documentation of non-stationary velocity fields in a scaled-down model of a water heat storage vessel. An ordinary video camera is used to record the in-plane movements of particles in a light sheet in seeded water. The hardware used, the experimental method and the accuracy of the method are discussed. The use of two commercially available software packages (NIH-Image and IGOR) for the analyses is described. Examples of velocity fields are presented, showing that the measuring technique can be used for studies of mixing near the inlet of the storage vessel and exchange of water between the boundary layer and the core.

  • 258.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Veber, Pascal
    Luleå tekniska universitet.
    Studies of velocity fields in a water heat storage with a video based particle image velocimetry technique1995Inngår i: Energy technologies for a sustainable future: : proceedings of the 30th Intersociety Energy Conversion Engineering Conference, IECEC, July 30 - August 4, 1995, Orlando, Florida / [ed] D. Yogi Goswami, New York: American Society of Mechanical Engineers , 1995Konferansepaper (Fagfellevurdert)
  • 259.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Westerlund, Lars
    Egenskaper hos gaser, vätskor och fasta ämnen2001Inngår i: VVS 2000 Tabeller och diagram, Stockholm: Förlags AB VVS , 2001Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 260.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hermansson, Roger
    Westerlund, Lars
    Abel, Enno
    Värmeströmning2008Inngår i: VVS 2000 Tabeller och diagram, Stockholm: Förlags AB VVS , 2008Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 261.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Karlsson, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    A new form of education: mechanics at the University of Lulea1978Inngår i: European Journal of Engineering Education, ISSN 0304-3797, E-ISSN 1469-5898, Vol. 3, nr 3/4, s. 277-283Artikkel i tidsskrift (Fagfellevurdert)
  • 262.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Keikkala, Gudrun
    Kask, Andrey
    Malyshev, Vladimir
    Murmansk State University.
    Minimizing greenhouse gas emissions by integration of a mineral processing and a district heating system for an adjacent town in North East Russia2006Konferansepaper (Annet vitenskapelig)
  • 263.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Mikael
    Grip, Carl-Erik
    Process integration in the steel industry2004Inngår i: Proceedings: 2nd International Conference on New Developments in Metallurgical Process Technology, Milano: Associazione Italiana di Metallurgia , 2004Konferansepaper (Fagfellevurdert)
  • 264.
    Dahl, Jan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Strid, Martin
    Mushi, Isaac
    Environmental education at Moshi national vocational training centre: feasibility and importance of fourteen schemes a preliminary study1992Rapport (Annet vitenskapelig)
  • 265.
    de Jong, Sierk
    et al.
    Copernicus Institute of Sustainable Development, Utrecht University.
    Hoefnagels, Ric
    Copernicus Institute of Sustainable Development, Utrecht University.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Pettersson, Karin
    RISE Research Institutes of Sweden.
    Faaij, André
    Energy Academy Europe, University of Groningen.
    Junginger, Martin
    Copernicus Institute of Sustainable Development, Utrecht University.
    Cost optimization of biofuel production: The impact of scale, integration, transport and supply chain configurations2017Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 195, s. 1055-1070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study uses a geographically-explicit cost optimization model to analyze the impact of and interrelation between four cost reduction strategies for biofuel production: economies of scale, intermodal transport, integration with existing industries, and distributed supply chain configurations (i.e. supply chains with an intermediate pre-treatment step to reduce biomass transport cost). The model assessed biofuel production levels ranging from 1 to 150 PJ a−1 in the context of the existing Swedish forest industry. Biofuel was produced from forestry biomass using hydrothermal liquefaction and hydroprocessing. Simultaneous implementation of all cost reduction strategies yielded minimum biofuel production costs of 18.1–18.2 € GJ−1 at biofuel production levels between 10 and 75 PJ a−1. Limiting the economies of scale was shown to cause the largest cost increase (+0–12%, increasing with biofuel production level), followed by disabling integration benefits (+1–10%, decreasing with biofuel production level) and allowing unimodal truck transport only (+0–6%, increasing with biofuel production level). Distributed supply chain configurations were introduced once biomass supply became increasingly dispersed, but did not provide a significant cost benefit (<1%). Disabling the benefits of integration favors large-scale centralized production, while intermodal transport networks positively affect the benefits of economies of scale. As biofuel production costs still exceeds the price of fossil transport fuels in Sweden after implementation of all cost reduction strategies, policy support and stimulation of further technological learning remains essential to achieve cost parity with fossil fuels for this feedstock/technology combination in this spatiotemporal context.

  • 266.
    de Jong, Sierk
    et al.
    Utrecht University and SkyNRG.
    Wetterlund, Elisabeth
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hoefnagels, Ric
    Utrecht University.
    Tzanetis, Kostis
    Utrecht University.
    Pettersson, Karin
    Chalmers University ofTechnology.
    Junginger, Martin
    Utrecht University.
    Optimizing biofuel supply chains based on liquefaction technologies: evaluating the hub-and-spoke model2016Inngår i: Meeting Sweden's current and future energy challenges, Luleå: Luleå tekniska universitet, 2016, Luleå: Luleå tekniska universitet, 2016Konferansepaper (Annet vitenskapelig)
  • 267.
    de Oliveira, Tiago Elias Castelo
    et al.
    Electrical Energy Systems, Technological University of Eindhoven, Eindhoven, The Netherlands.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Ribeiro, Paulo Fernando
    Advanced Power Technologies and Innovations in Systems and Smart Grids Group, Federal University of Itajuba, Itajuba, Brazil.
    de Carvalho, Pedro M. S.
    Energy Scientific Area, Instituto Superior Tecnico, Lisbon, Portugal.
    Zambroni, Antônio C.
    Advanced Power Technologies and Innovations in Systems and Smart Grids Group, Federal University of Itajuba, Itajuba, Brazil.
    Bonatto, Benedito D.
    Advanced Power Technologies and Innovations in Systems and Smart Grids Group, Federal University of Itajuba, Itajuba, Brazil.
    The Concept of Dynamic Hosting Capacity for Distributed Energy Resources: Analytics and Practical Considerations2019Inngår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 13, artikkel-id 2576Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hosting capacity approach is presented as a planning, improving, and communication tool for electrical distribution systems operating under specific uncertainties, such as power quality issues, power stabilities, and reliability, among others. In other words, it is an important technique, when renewable sources are present, to answer the amount of power that is possible to supply to the system without trespassing power performance limits. However, the power flow in a distribution system, for instance, can change throughout time due to the penetration of distributed generation, as well as load consumption. Based on the dynamic nature existing in distribution grids nowadays, it is important to highlight that the hosting capacity should not be calculated in a specifically chosen time only, but must be analyzed throughout a period of time. Thus, this paper introduces an extended concept of hosting capacity in relation to an integrated impact of harmonic voltage distortion and voltage rise as a function of time for daily, weekly, monthly, or even yearly periods. This extended concept is named as Dynamic Hosting Capacity (DHC(t)). General aspects of DHC(t) are demonstrated via measured data on a photovoltaic system (PV) connected at a low-voltage (LV) side of a university building.

  • 268.
    Degerman, Bengt
    et al.
    Luleå tekniska universitet.
    Hedin, Johan
    Luleå tekniska universitet.
    Fredriksson, Christian
    Luleå tekniska universitet.
    Kjellström, Björn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Salman, Hassan
    Luleå tekniska universitet.
    Studies of two stage gas turbine combustor for biomass powder: Part 1 : atmospheric cyclone gasification experiments with wood powder1998Rapport (Annet vitenskapelig)
    Abstract [en]

    This report summarises the research and development work regarding development of a two stage gas turbine combustor for wood powder carried out at the Luleå University of Technology from July 1993 to December 1996. The process being studied is based on cyclone gasification of the wood powder and combustion of the product gas in a suitably adapted gas turbine combustion chamber, without other gas cleaning than that obtained by the cyclone. A critical issue to be studied in the project is if the burned gases from such a cyclone gasifier lead to acceptably low deposition rates for K- and Na-compounds in a gas turbine with 850°C inlet temperature. The project strategy has been to study wood powder feeding and cyclone gasification first at atmospheric pressure, then run separate pressurised cyclone gasification tests for studies of the possibilities to achieve stable operation when the air flow is supplied by a separate compressor and finally to run integrated gasifier/gas turbine tests for studies of the deposition problem in practical operation.

  • 269. Deuse, J.
    et al.
    Grenard, S.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    EU-DEEP integrated proect: technical implications of the "hosting-capacity" of the sytem for DER2008Inngår i: International Journal of Distributed Energy Resources, ISSN 1614-7138, Vol. 4, nr 1, s. 17-34Artikkel i tidsskrift (Fagfellevurdert)
  • 270. Deuse, J
    et al.
    Grenard, S
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Chuvychin, V
    Integration of DER & RES in power system and distribution network design2008Inngår i: CIGRE Sessions: CD ROM 2008 Session Papers, 2008Konferansepaper (Fagfellevurdert)
  • 271. Deuse, J
    et al.
    Grenard, S
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Häger, M
    Sollerkvist, F
    Effective impact of DER on distribution system protection2007Inngår i: Conference proceedings: 19th International Conference and Exhibition on Electricity Distribution : Vienna, 21 - 24 May 2007, Liege: AIM , 2007Konferansepaper (Fagfellevurdert)
  • 272. Deuse, J
    et al.
    Karoui, K
    Crisciu, H
    Gertmar, L
    Samuelsson, O
    Karlsson, P
    Chuvychin, V
    Ribickis, L
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Interactions of dispersed energy resources with power system in normal and emergency conditions2006Inngår i: Compte rendu de la session, CIGRE session 41 : 27 août > 1er septembre 2006 = Session proceedings, CIGRE session 41, Conseil International des Grands Réseaux Electriques , 2006Konferansepaper (Fagfellevurdert)
  • 273.
    Djokic, S
    et al.
    University of Edinburgh.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reusel, K Van
    Katholieke Universiteit Leuven.
    Neumann, R
    Qualitrol.
    Stockman, K
    Howest.
    Gordon, J
    Endesa, Sevilla.
    Ethier, G
    Hydro-Québec Research’s Institute.
    Zavoda, F
    Hydro-Québec Research’s Institute.
    Cundeva, S
    Ss. Cyril and Methodius University.
    Stephens, M
    EPRI.
    UIE WG 2 power quality: recommendations to the stakeholderson voltage dip immunity of equipment and installations (after the CIGRE/CIRED/UIE joint WG C4.110)2012Konferansepaper (Fagfellevurdert)
  • 274.
    Djokic, S
    et al.
    University of Edinburgh.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reusel, K Van
    Katholieke Universiteit Leuven.
    Neumann, R
    Qualitrol.
    Stockman, K
    Howest.
    Milanovic, J
    University of Manchester.
    UIE WG 2 power quality: further work and research on voltage dip immunity of equipment and installations (after the CIGRE/CIRED/UIE joint WG C4.110)2012Konferansepaper (Fagfellevurdert)
  • 275. Djokic, S
    et al.
    Stockman, K
    Howest.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reusel, K Van
    Neumann, R
    Qualitrol.
    Marteyn, P
    Dow.
    UIE WG 2 power quality: the concept of process immunity time for the assessment of dip immunity of industrial processes (after the CIGRE/CIRED/UIE joint WG C4.110)2012Konferansepaper (Fagfellevurdert)
  • 276.
    Djokic, Sasa
    et al.
    School of Engineering and Electronics, University of Edinburgh.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dip segmentation method2008Inngår i: 2008 13th International Conference on Harmonics and Quality of Power: [ICHQP 2008] ; Wollongong, Australia, 28 September - 1 October 2008, Piscataway, NJ: IEEE Communications Society, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An alternative approach for the analysis of various types of dip events, termed Dip Segmentation Method, is presented in this paper. The description of a voltage dip in the proposed method includes both pre-dip and postdip parts/segments of a dip-related event, while the during-dip part is divided into a number of "during-event segments" and "transition segments". In that way, the proposed method allows for an improved assessment of standard and commonly used dip characteristics, incorporating, at the same time, several usually neglected characteristics, aspects and features of dip events into the analysis. After identifying the corresponding dip segments, direct correlation between the individual segments and particular effects on equipment operation could be established, allowing a more detailed description of the dip events and more accurate assessment of their influence on equipment performance.

  • 277.
    Dong, Yihui
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. State Key Laboratory of Materials-Oriented and Chemical Engineering and Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, China.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Laaksonen, Aatto
    State Key Laboratory of Materials-Oriented and Chemical Engineering and Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, China. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden. Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden. Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, Iasi, Romania.
    Cao, Wei
    State Key Laboratory of Tribology, Tsinghua University, Beijing, China.
    An, Rong
    Herbert Gleiter Institute of Nanoscience, Nanjing University of Science & Technology, Nanjing, China.
    Lu, Linghong
    State Key Laboratory of Materials-Oriented and Chemical Engineering and Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, China.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented and Chemical Engineering and Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, China.
    Determination of the small amount of proteins interacting with TiO2 nanotubes by AFM-measurement2019Inngår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 192, s. 368-376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Detecting the small amounts of proteins interacting effectively with the solid film electrodes surface still remains a challenge. To address this, in this work, a new approach was proposed by the combination of the adhesion forces and the molecular interaction measured with AFM. Cytochrome c (Cyt C) interacting effectively with TiO2 nanotube arrays (TNAs) was chosen as a probe. The amounts of Cyt C molecules interacting effectively on TNAs surface (CTNA) range from 5.5×10-12 to 7.0×10-12 mol/cm2 (68.2-86.8 ng/cm2) and they are comparable with the values obtained by the electrochemistry method in the literature, in evidence of the accuracy of this AFM-based approach. The reliability of the proposed approach was further verified by conducting Surface Enhanced Raman Scattering (SERS) measurements and estimating the enhancement factor (EF). This interaction-based AFM approach can be used to accurately obtain the small amounts of adsorbed substances on the solid film electrodes surface in the applications such as biosensors, biocatalysis, and drug delivery, etc.

  • 278.
    Dong, Yihui
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap. State Key Laboratory of Materials-Oriented and Chemical Engineering Nanjing Tech University.
    Laaksonen, Aatto
    Department of Materials and Environmental Chemistry Arrhenius Laboratory Stockholm University. Centre of Advanced Research in Bionanoconjugates and Biopolymers Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, Iasi, Romania. State Key Laboratory of Materials-Oriented and Chemical Engineering Nanjing Tech University, China.
    Cao, Wei
    State Key Laboratory of Tribology Tsinghua University, Beijing, China.
    Ji, Xiaoyan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lu, Xiaohua
    State Key Laboratory of Materials-Oriented and Chemical Engineering Nanjing Tech University Nanjing, China.
    AFM Study of pH-Dependent Adhesion of Single Protein to TiO2 Surface2019Inngår i: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, nr 14, artikkel-id 1900411Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of pH-induced electrostatic conditions on the molecular interaction force of a single lysozyme molecule with TiO2 is investigated using atomic force microscopy (AFM). The force between the charged or neutral lysozyme molecule and the TiO2 surface is measured at different pH from 3.6 to 10.8. It is found to be directly proportional to the contact area, given by an effective diameter of the lysozyme molecule, and is further qualitatively verified by the AFM-measured friction coefficients. The results of the Derjaguin–Landau–Verwey–Overbeek theory show that the pH can change the surface charge densities of both lysozyme and TiO2, but the molecular interaction force at different pH is only dependent on the pH-induced effective diameter of lysozyme. The molecular interaction forces, quantified at the nanoscale, can be directly used to design high-performance liquid chromatography measurements at macroscale by tuning the retention time of a protein under varied pH conditions. They can also be applied to develop a model for predicting and controlling the chromatographic separations of proteins.

  • 279. Du, C
    et al.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Power-frequency control for VSC-HVDC during island operation2006Inngår i: The 8th IEE International Conference on AC and DC Power Transmission : ACDC 2006 : 28 - 31 March 2006, [London], London: Institution of Engineering and Technology, 2006Konferansepaper (Fagfellevurdert)
  • 280.
    Du, C
    et al.
    ABB AB, HVDC System, Ludvika.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Agneholm, E
    Sannino, A
    ABB AB, Corporate research.
    A new control strategy of a VSC-HVDC System for high-quality supply of industrial plants2007Inngår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 22, nr 4, s. 2386-2394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a control strategy for a VSC-HVDC for improving the quality of power supply to industrial plants. The new idea of this control strategy is to give high priority to keep up the ac voltage and slightly decrease the frequency during disturbances. The motivation for choosing this strategy is that the sensitive processing industries are much more sensitive to voltage drops as compared with frequency deviations. In order to test this control strategy, the dynamic performance of a VSC-HVDC supplied industrial plant is investigated during sudden load disturbances, balanced and unbalanced faults from the grid. Simulation results obtained using PSCAD/EMTDC show that with the use of the proposed control strategy, the system can ride through disturbances such as motor starting and faults by slightly decreasing the frequency. The current limit of the VSC-HVDC converters has a significant influence on the dynamics of the system. An increase of the current limit significantly improves the power quality of the system. The comparison of the behavior between a pure ac supplied industrial plant and a VSC-HVDC supplied industrial plant clearly shows the capability of the VSC-HVDC to mitigate voltage dips during faults.

  • 281.
    Du, c.
    et al.
    Division of Electric Power Engineering, Department of Energy and Environment, Chalmers University of Technology.
    Sannino, A.
    ABB Corporate Research.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Analysis of response of VSC-based HVDC to unbalanced faults with different control systems2005Inngår i: Security and sustainable development under deregulation: 2005 IEEE/PES Transmission and Distribution Conference & Exhibition: Asia and Pacific : [August 14 - 18, 2005, Dalian, China] ; paper abstracts, Piscataway, NJ: IEEE Communications Society, 2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper investigates the dynamic performance of a VSC-HVDC system under unbalanced faults in ac systems. Three different control systems are presented and analyzed for the most common unbalanced fault, i.e. single-line-to-ground fault (SLGF) in PSCAD/EMTDC. Simulation results show that the system resumes normal operation after fault clearing using all three control systems, among which the third control system produces the best transient performance

  • 282. Dumortier, L.
    et al.
    Dahl, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Benckert, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Kjellström, Björn
    Evaluation of particle tracking velocimetry for studies of the flow in a boiler furnace1999Inngår i: Applied Modelling and Simulation, International conference, 1999Konferansepaper (Fagfellevurdert)
  • 283.
    Edo, Mar
    et al.
    Department of Chemistry, Umeå University.
    Skoglund, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gao, Qiuju
    Department of Chemistry, Umeå University.
    Persson, Per-Erik
    VafabMiljö Kommunalförbund, SE-721 87 Västerås.
    Jansson, Stina
    Department of Chemistry, Umeå University.
    Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF2017Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 68, s. 646-652Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220 °C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.

  • 284.
    Ehnberg, S.G. Jimmy
    et al.
    Chalmers University of Technology.
    Bollen, Math
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Reliability of a small power system using solar power and hydro2005Inngår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 74, nr 1, s. 119-127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper studies the availability of the electricity supply when the sources consist of a combination of solar energy and a small hydro installation. Instead of flow-of-river, a small reservoir is used. By not using the hydro energy during sunny periods, the natural flow-of-river fills up the reservoir for later use. A model for global solar radiation is proposed with an astronomical part (deterministic) and a meteorological part (stochastic). The meteorological part is based on a Markov model of the cloud coverage. The solar model does not require solar radiation measurements, just cloud observations. A case study has been performed for Timbuktu (16.75°N, 0.07°W) in which generation availability is simulated for four different cases: solar power only; solar power with storage; solar and hydro power and solar and hydro power with storage. To be able to use exclusively renewable energy sources, a combination of sources is needed to secure the reliability of the supply. Using solar cells in combination with a small reservoir is favorable. Even with a weak flow the affect of the flow on the day time reliability is minor, but great benefits can be found for reliability during low load hours (night time).

  • 285.
    Ekbom, Tomas
    et al.
    Grontmij AB, Energy and Power, Stockholm.
    Hulteberg, Christian
    Nordlight AB.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Larsson, Mikael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Lundgren, Joakim
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Nilsson, Leif
    SSAB EMEA, Luleå.
    Tunå, Per
    Lund University.
    Methanol production from steel-work off-gases and biomass based synthesis gas2012Inngår i: International Conference on Applied Energy, ICAE 2012: Jul 5-8, 2012, Suzhou, China, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main objective has been to describe different cases of the methanol production from steel-work off gases (Coke oven gas and Basic oxygen furnace gas) and biomass based synthesis gas. The SSAB steel mill in the town of Luleå, Sweden has been used as a basis to analyze four different methanol production cases.The studied biomass gasification technology is based on a fluidized bed gasifier unit, where the production capacity is determined from case to case coupled to the heat production required to satisfy the local district heating demand. Critical factors are the integration of the gases with availability to the synthesis unit, to balance the steam system of the biorefinery and to meet the district heat demand of Luleå.For each case, the annual production potential of methanol, the overall production efficiencies and the effects on the total steel plant have been estimated.

  • 286.
    Elfgren, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Cosmic dust and heavy neutrinos2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This Doctoral thesis treats two subjects. The first subject is the impact of early dust on the cosmic microwave background (CMB). The dust that is studied comes from the first generation of stars, which were hot and short-lived, ending their lives as giant supernovae. In the supernova explosions, heavy elements, produced through the fusion in the stars, were ejected into the interstellar medium. These heavy elements condensed to form dust, which can absorb and thus perturb the CMB radiation. The dust contribution to this radiation is calculated and found negligible. However, since the dust is produced within structures (like galaxy clusters), it will have a spatial correlation that could be used to detect it. This correlation is calculated with relevant assumptions. The planned Planck satellite could eventually detect and thus confirm this correlation. The second subject is heavy neutrinos and their impact on the diffuse gamma ray background. Neutrinos heavier than M_Z /2 ~ 45 GeV are not excluded by particle physics data. Stable neutrinos heavier than this might contribute to the cosmic gamma ray background through annihilation in distant galaxies as well as to the dark matter content of the universe. The evolution of the heavy neutrino density in the universe is calculated as a function of its mass, M_N, and then the subsequent gamma ray spectrum from annihilation of distant N-Nbar (from 0 < z < 5). The evolution of the heavy neutrino density in the universe is calculated numerically. In order to obtain the enhancement due to structure formation in the universe, the distribution of N is approximated to be proportional to that of dark matter in the GalICS model. The calculated gamma ray spectrum is compared to the measured EGRET data. A conservative exclusion region for the heavy neutrino mass is 100 to 200 GeV, both from EGRET data and our re-evalutation of the Kamiokande data. The heavy neutrino contribution to dark matter is found to be at most 15%. Finally, heavy neutrinos are considered within the context of a preon model for composite leptons and quarks, where such particles are natural. The consequences of these are discussed, with emphasis on existing data from the particle accelerator LEP at CERN. A numerical method for optimizing variable cuts in particle physics is also included in the thesis.

  • 287.
    Elfgren, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Dust in the early universe2005Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This Licentiate thesis treats the impact of early dust on the Cosmic Microwave Background (CMB). The dust that is studied comes from the first generation of stars, which were hot and short-lived, ending their lives as giant supernovæ. In the supernova explosions, heavy elements, produced through the fusion in the stars, were ejected into the interstellar medium. These heavy elements condensed to form dust, which can absorb and thus perturb the Cosmic Microwave Background radiation. The dust contribution to this radiation is calculated and found negligible. However, as the dust will be produced within structures (like galaxy clusters), it will have a spatial correlation that could be used to detect it. This correlation is calculated using relevant assumptions. The planned Planck satellite is likely to be able to measure and thus confirm this correlation.

  • 288.
    Elfgren, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Désert, Francois-Xavier
    Laboratoire d’Astrophysique, Observatoire de Grenoble.
    Dust from reionization2004Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 425, s. 9-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility that population III stars have reionized the Universe at redshifts greater than 6 has recently gained momentum with WMAP polarization results. Here we analyse the role of early dust produced by these stars and ejected into the intergalactic medium. We show that this dust, heated by the radiation from the same population III stars, produces a submillimetre excess. The electromagnetic spectrum of this excess could account for a significant fraction of the FIRAS (Far Infrared Absolute Spectrophotometer) cosmic far infrared background above 700 micron. This spectrum, a primary anisotropy (Delta T) spectrum times the nu2 dust emissivity law, peaking in the submillimetre domain around 750 micron, is generic and does not depend on other detailed dust properties. Arcminute-scale anisotropies, coming from inhomogeneities in this early dust, could be detected by future submillimetre experiments such as Planck HFI.

  • 289.
    Elfgren, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Désert, François-Xavier
    Laboratoire d’Astrophysique, Observatoire de Grenoble.
    Guiderdoni, Bruno
    Université Lyon 1, Centre de Recherche Astrophysique de Lyon, Observatoire de Lyon.
    Dust distribution during reionization2007Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 476, s. 1145-1150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. The dust produced by the first generation of stars will be a foreground to cosmic microwave background.Aims. In order to evaluate the effect of this early dust, we calculate the power spectrum of the dust emission anisotropies and compare it with the sensitivity limit of the Planck satellite.Methods. The spatial distribution of the dust is estimated through the distribution of dark matter.Results. At small angular scales l ≥ 1000 the dust signal is found to be noticeable with the Planck detector for certain values of dust lifetime and production rates. The dust signal is also compared to sensitivities of other instruments. The early dust emission anisotropies are finally compared to those of local dustand they are found to be similar in magnitude at mm wavelengths.

  • 290.
    Elfgren, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wang, Chuan
    Swerea MEFOS AB.
    Karlsson, Jonny
    SSAB EMEA, Luleå.
    Exergy as a means for process integration in an integrated steel plant2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Luleå energy system consists of SSAB (an integrated steel plant) – LuleKraft (the heat and power plant) – Luleå Energi (the district heating network). The exergy flows in the whole system have been studied and some possibilities on how to reduce the exergy losses are discussed. The exergy thermal efficiency of SSAB, LuleKraft and Luleå Energi are 70 %, 40 % and 30 % respectively. The relatively low exergy thermal efficiencies is a natural consequence of converting high-value chemical energy into heating water. In the integrated steel plant, the exergy losses are caused by the cooling of the steel prior to transport. In the heat and power plant, exergy is destroyed mainly in the furnace. In the district heating, exergy is destroyed mainly by the customer. A preliminary conclusion is that a lot of exergy is destroyed and lost in order to produce hot water, which doesn’t really need so much exergy. By lowering the water temperature of the district heating, a larger portion of the exergy can be converted to high-value electricity. Mapping by combined Exergy/energy analysis is important to find ways to improve energy efficiency. It can also be important to initiate regional energy collaboration.

  • 291.
    Elfgren, Erik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Grip, Carl-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Wang, Chuan
    Swerea MEFOS AB.
    Karlsson, Jonny
    SSAB.
    Possibility to combine exergy with other process integration methods for a steelmaking case2010Inngår i: PRES 2010, 13th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction / [ed] Jirí J. Klemeš; Hon Loong Lam; Petar S. Varbanov, AIDIC Servizi S.r.l. , 2010, s. 1375-1380Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The energy system of Luleå consists of the steel plant, a local CHP using process gases from the plant and the district heating system. Process integration work to improve the efficiency of the system is presently carried out by mathematical programming using a MILP tool (reMIND). Further improvements would need an improved possibility of the tool to consider the thermodynamic quality of the energy flows. This project aims to include exergy parameters in the node equations and object functions. This has been carried out for a test case, including a part of the system. Programming principles and some results are described.

  • 292.
    Engström, T. Fredrik
    et al.
    Luleå tekniska universitet.
    Gebart, Rikard
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Gyroscopic design of swirling flow diffusers1999Inngår i: Proceedings of ASME/JSME FEDSM'99: ASME/JSME Fluids Engineering Division Summer Meeting, American Society of Mechanical Engineers , 1999Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The flow in the draft tube of a hydro power plant is often swirling when the turbine is operating outside its best efficiency point. The swirl gives rise to gyroscopic effects when the flow is forced through the bend in the draft tube. The resulting complex flow field causes losses.The idea in this paper is to investigate the possibility of using a simple model to calculate a new geometry of the draft tube that avoids distortion of the vortex core. Simulations are carried out using the CFD code CFX. A Reynolds stress model, with wall functions, is used to model turbulence.A loss factor is calculated and it was found that the new design draft tube shows approximately the same loss as a non-modified draft tube. The explanation to the somewhat surprising result is that the flow through and after the bend is dominated by the centrifugal effects from streamline curvature. It is therefore concluded that the most important loss mechanism appears to be triggered by streamline curvature.

  • 293.
    Eriksson, Daniel
    et al.
    Swedish University of Agricultural Sciences, Vindeln Experimental Forest, Svartberget Research Station.
    Weiland, Fredrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Stenberg, Martin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Öhrman, Olov
    Lestander, Torbjörn A.
    Swedish University of Agricultural Sciences, Unit of Biomass Technology and Chemistry, Umeå.
    Bergsten, Urban
    Swedish University of Agricultural Sciences, Vindeln Experimental Forest, Svartberget Research Station.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Characterization of Scots pine stump-root biomass as feed-stock for gasification2012Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 104, s. 729-736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈ 19%) compared to the other fuels (2 – 8%) and thereby ≈ 16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it.

  • 294.
    Eriksson, Gunnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Combustion of solid waste from wood-based ethanol production2005Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The solid residue from wood-based ethanol production has a low ash content and high heating value, making it interesting for combustion applications, e.g. small-scale appliances and gas turbines. Combustion and gasification properties have been studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Char combustion rate data obtained could be used in combustion simulations. TGA and DTA data are useful for comparison with other fuels where data are available for similar heating rates. One possible use is direct-firing of gas turbines for Combined Heat and Power (CHP) at the site of the ethanol plant. Another possible use of the material is for the production of fuel pellets. A combustion test with a 150 kW powder burner has been done. Fuel feeding and combustion were stable. The average concentration of CO in the stack gas was 8 mg/MJ, the averag concentration of NOx was 59 mg/MJ and the average total hydrocarbon concentration was below 1 ppm, at an average O2 concentration of 4.6 per cent. Process parameters, investments, costs and revenues for these two production options have been estimated. The conclusion is that CHP is the most profitable use, although the uncertainties in estimated costs are considerable. Reductions of greenhouse gas emissions are decidedly larger for the CHP option. It has been concluded that CHP production is an option worth pursuing further. The technical feasibility of using the material for direct-firing of a gas turbine remains to be established however.

  • 295.
    Eriksson, Gunnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Klarar Luleå miljömålen?: utsläpp av svaveldioxid, kväveoxider och kolväten inom Luleå kommun1993Rapport (Annet vitenskapelig)
  • 296.
    Eriksson, Gunnar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Residues from biochemical production of transport biofuels in Northern Europe: combustion properties and applications2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Residues from biochemical production of liquid transport biofuels will probably become available for energy use if more gasoline and diesel is substituted. For processes used in northern Europe they amount to 35-65 % of the feedstock energy and despite interest from energy companies, their fuel properties are largely unknown. Combustion-relevant material properties have been characterized and fuel-specific combustion properties determined for powder-, grate- and fluidized bed combustion. Suitable combustion applications have been identified. A techno-economic evaluation of utilization of a selected residue for supplying process heat and electricity to the transport biofuel production, combined with sale of surplus energy has been done. Residues studied are rape-seed meal (RM) from biodiesel production, wheat distillers dried grain with solubles (wheat DDGS) from grain-based ethanol production and hydrolysis residue (HR) from wood-based ethanol production. For RM and wheat DDGS, mixtures with typical forest- and agricultural fuels were also studied. Combustion experiments were performed in a fluidized (quartz) bed (5 kW), an under-fed pellet burner (12 kW), and in a powder burner (150 kW).The calorific value for HR was higher than for wood, for RM and wheat DDGS it was similar to wood. More char was produced from HR, otherwise TGA results showed that thermal kinetics was similar to wood for all fuels. All pulverized residues had better feeding properties than wood powder. While RM and wheat DDGS ash contents were higher than for most common forest and also for some agricultural fuels, HR mostly had very low contents of ash, alkali, Cl, S and N. RM and DDGS had high concentrations of S, N, K and P compared to most other biomass fuels. RM had higher Ca and Mg concentrations than DDGS. The Cl content of wheat DDGS was similar to wheat straw, while RM had a lower Cl content, similar to wood. Combustion of all pulverized residues was stable with CO emissions not higher than for wood powder. While the bed agglomeration tendency of RM was low and comparable to many forest fuels the wheat DDGS bed agglomeration tendency was high and comparable to wheat straw. The K, P and Si contents of wheat DDGS formed layers of K-phosphates/silicates on the quartz grain particles, with low melting temperatures and therefore sticky, resulting in bed agglomeration. For RM, this effect was mitigated by the considerable Ca and Mg concentrations, making the layers formed less sticky, despite the high K and P concentrations. For basically the same reason, the slag formation tendency of RM was moderate and comparable to many forest fuels while wheat DDGS had a slag formation tendency which was even higher than for typical wheat straw. HR had very low bed agglomeration and slagging tendencies.For RM and wheat DDGS, emissions of NO and SO2 were generally high, for HR considerably lower. While HCl emissions for RM were low, they were relatively high for fluidized bed combustion of wheat DDGS. Particle emissions from RM and wheat DDGS were generally high. For powder combustion of RM and wheat DDGS, particle emissions were 15-20 times higher than for wood. The particle emissions from combustion of HR were generally low. For fluidized bed- and grate combustion of RM the finer particles (< 1 μm) contained mainly alkali sulfates. RM addition to bark tended to lower the particle Cl concentrations, potentially lowering the risk of high-temperature corrosion. For fluidized bed combustion of wheat DDGS and wheat DDGS-mixtures the finer particles contained mainly K and S. The Cl concentrations of the fine particles in fluidized bed combustion were reduced when wheat DDGS where added to logging residues and wheat straw in fluidized bed combustion. In grate combustion the Cl- and P-concentrations in the finer particles during combustion of the wheat DDGS-mixtures were considerable higher than during fluidized bed combustion. The fine particles from powder combustion of RM mainly contained P and K, while they mainly contained K, P, Cl, Na and S from wheat DDGS (apart from C and O).A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K in large-scale fluidized-bed and grate combustors for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases. Due to its high slagging and bed agglomeration tendencies, the best use of wheat DDGS may be to mix it with other fuels, preferably with high Ca and Mg contents (e.g. woody biomass fuels), so that only a minor fraction of the total ash-forming elements is contributed by the wheat DDGS. Because of their high N- and S contents, RM and wheat DDGS require applications with flue-gas cleaning, economically viable at large-scale. Powder combustion of RM and wheat DDGS should be used with caution, as potassium phosphate particles have low melting temperatures and could therefore increase the risk of deposit formation. Use of HR in small-scale pellet appliances is an interesting option due to low emissions, low ash content and low slagging tendency. While most large-scale combustion uses of HR would be feasible, the low ash and alkali contents and stable powder combustion of HR may be better exploited in a combined-cycle process, as the alkali content can be kept sufficiently low for use in robustgas turbines, simplifying the gas cleaning.In the techno-economic assessment, residue (HR) was assumed to be combusted on site, to supply process steam and electricity to the liquid biofuel production (wood-based ethanol) with surplus residue either sold as solid fuel or used for additional heat and power generation. With a combined cycle to increase electricity production, a location with a large district heating base load is not needed. As electricity replaced is largely generated with fossil fuels, a combined cycle is significantly more effective as a climate mitigation measure than a steam-cycle only, with about 25 percent greater reduction in CO2 emissions per litre of ethanol produced. While it is generally accepted that energy use of the residue is important to the process economy and environmental benefits of ligno-cellulosic ethanol production, it can be concluded from this study that the choice of integrated process design has a significant impact on CO2 emissions.

  • 297.
    Eriksson, Gunnar
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Grimm, Alejandro
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Skoglund, Nils
    Umeå universitet.
    Boström, Dan
    Umeå universitet.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Combustion and fuel characterisation of wheat distillers dried grain with solubles (DDGS) and possible combustion applications2012Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 102, s. 208-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present transition to a sustainable global energy system requires that biomass is increasingly combusted for heat and power production. Agricultural fuels considered include alkali-rich fuels with high phosphorus content. One such fuel is wheat distiller’s dried grain with solubles (wheat DDGS) from wheat-based ethanol production. Further increases in ethanol production may saturate the current market for wheat DDGS as livestock feed, and fuel uses are therefore considered. Fuel properties of wheat DDGS have been determined. The ash content (5.4. ± 1.6 %wt d.s.) is similar to many agricultural fuels. In comparison to most other biomass fuels the sulphur content is high (0.538 ± 0.232 %wt d.s.), and so are the contents of nitrogen (5.1 ± 0.6 %wt d.s.), phosphorus (0.960. ± 0.073 %wt d.s.) and potassium (1.30 ± 0.35 %wt d.s.). To determine fuel-specific combustion properties, wheat DDGS and mixes between wheat DDGS and logging residues (LR 60 %wt d.s. and DDGS 40 %wt d.s.), and wheat straw (wheat straw 50 %wt d.s., DDGS 50 %wt d.s.) were pelletized and combusted in a bubbling fluidised bed combustor (5 kW) and in a pellets burner combustor (20 kW). Pure wheat DDGS powder was also combusted in a powder burner (150 kW). Wheat DDGS had a high bed agglomeration and slagging tendency compared to other biomass fuels, although these tendencies were significantly lower for the mixture with the Ca-rich LR, probably reflecting the higher first (solid) melting temperatures of K–Ca–Mg-phosphates compared to K-phosphates. Combustion and co-combustion of wheat DDGS resulted in relatively large emissions of fine particles (<1 μm) for all combustion appliances. For powder combustion PMtot was sixteen times higher than from softwood stem wood. While the Cl concentrations of the fine particles from the LR–wheat DDGS-mixture in fluidised bed combustion were lower than from combustion of pure LR, the Cl- and P-concentrations were considerably higher from the wheat DDGS mixtures combusted in the other appliances at higher fuel particle temperature. The particles from powder combustion of wheat DDGS contained mainly K, P, Cl, Na and S, and as KPO3 (i.e. the main phase identified with XRD) is known to have a low melting temperature, this suggests that powder combustion of wheat DDGS should be used with caution. The high slagging and bed agglomeration tendency of wheat DDGS, and the high emissions of fine particles rich in K, P and Cl from combustion at high temperature, mean that it is best used mixed with other fuels, preferably with high Ca and Mg contents, and in equipment where fuel particle temperatures during combustion are moderate, i.e. fluidised beds and possibly grate combustors rather than powder combustors.

  • 298. Eriksson, Gunnar
    et al.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Backman, Rainer
    Energy Technology and Thermal Process Chemistry, Department of Applied Physics and Electronics, Umea University.
    Pettersson, Esbjörn
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Combustion characterization of rapeseed meal and possible combustion applications2009Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 23, nr 8, s. 3930-3939Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A future shortage of biomass fuel can be foreseen. The production of rapeseed oil for a number of purposes is increasing, among others, for biodiesel production. A byproduct from the oil extraction process is rapeseed meal (RM), presently used as animal feed. Further increases in supply will make fuel use an option. Several energy companies have shown interest but have been cautious because of the scarcity of data on fuel properties, which led to the present study. Combustion-relevant properties of RM from several producers have been determined. The volatile fraction (74 ± 0.06%wtds) is comparable to wood; the moisture content (6.2−11.8%wt) is low; and the ash content (7.41 ± 0.286%wtds) is high compared to most other biomass fuels. The lower heating value is 18.2 ± 0.3 MJ/kg (dry basis). In comparison to other biomass fuels, the chlorine content is low (0.02−0.05%wtds) and the sulfur content is high (0.67−0.74%wtds). RM has high contents of nitrogen (5.0−6.4%wtds), phosphorus (1.12−1.23%wtds), and potassium (1.2−1.4%wtds). Fuel-specific combustion properties of typical RM were determined through combustion tests, with an emphasis on gas emissions, ash formation, and potential ash-related operational problems. Softwood bark was chosen as a suitable and representative co-combustion (woody) fuel. RM was added to the bark at two levels: 10 and 30%wtds. These mixtures were pelletized, and so was RM without bark (for durability mixed with cutter shavings, contributing 1%wt of the ash). Each of these fuels was combusted in a 5 kW fluidized bed and an underfed pellet burner (to simulate grate combustion). Pure RM was combusted in a powder burner. Emissions of NO and SO2 were high for all combustion tests, requiring applications with flue gas cleaning, economically viable only at large scale. Emissions of HCl were relatively low. Temperatures for initial bed agglomeration in the fluidized-bed tests were high for RM compared to many other agricultural fuels, thereby indicating that RM could be an attractive fuel from a bed agglomeration point of view. The results of grate combustion suggest that slagging is not likely to be severe for RM, pure or mixed with other fuels. Fine-mode particles from fluidized-bed combustion and grate combustion mainly contained sulfates of potassium, suggesting that the risk of problems caused by deposit formation should be moderate. The chlorine concentration of the particles was reduced when RM was added to bark, potentially lowering the risk of high-temperature corrosion. Particle emissions from powder combustion of RM were 17 times higher than for wood powder, and the fine-mode fraction contained mainly K-phosphates known to cause deposits, suggesting that powder combustion of RM should be used with caution. A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases.

  • 299. Eriksson, Gunnar
    et al.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Öhman, Marcus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Boström, Dan
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Pettersson, Esbjörn
    Pommer, Linda
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Lindström, Erica
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Backman, Rainer
    Energy Technology and Thermal Process Chemistry, Umeå University.
    Öhman, Rikard
    Energy Technology Centre, Piteå.
    Förbränningskarakterisering av rapsmjöl och förslag till optimalt nyttjande i olika förbränningsanläggningar2007Rapport (Annet vitenskapelig)
    Abstract [en]

    When rape oil is chemically extracted, rape seed meal, a solid residue remains. Currently, it is used as animal feed. Several plants for the production of rape methyl ester (RME, biodiesel) are in operation or under construction. Combustion properties have been studied for rape seed meal produced as a by product to rape-methyl esther (RME, biodiesel). Composition of the material has been measured, using proximate and ultimate analysis. The lower heating value was 18.2 ± 0,3 MJ/kg d.w. and the ash content was 7-8 percent d.w. The material is rich in nitrogen and sulphur. Concentrations of K, P, Ca and Mg are high in the fuel. Rape seed meal was mixed with bark and pelletised. Bark pellets were also used as a reference fuel. Pellets with 10 and 30 percent rape seed meal were produced. Material with 80 percent rape seed meal and 20 percent planer shavings was also pelletised. Wood had to be added to provide enough friction in the pelletising process, with adapted equipment rape seed meal could probably be easily pelletised). The material was studied using Thermo-Gravimetric Analysis (TGA), and compared with data from tests with wood powder. The pyrolysis of the rape seed meal has a characteristic temperature of 320oC. Devolatilisation starts at 150 oC (at a lower temperature than for wood powder), and proceeds within a rather wide temperature range. The probable cause is the difference in organic content, in particular protein content. The result does not suggest that the material will be difficult to ignite. Experiments in a bench-scale fluidised bed (5 kW) showed that pellets containing only bark, and the mixture rape seed meal/wood had a bed agglomeration temperature well over the normal operational bed temperature. For the fuel mixtures rape seed meal and bark, the agglomeration temperature was slightly over the operational temperature. Particle emissions from fluidised bed combustion and grate combustion were, the latter simulated using a commercial pellet burner, were roughly doubled with fuels containing rape seed meal compared to bark. In the powder burner tests, particle emissions increased with a factor 17 with rape seed meal compared to wood powder. The emitted particles were mainly found in the fine (< 1 µm) mode during grate and powder combustion. During fluidized bed combustion the total particulate matter consisted both of a coarse (>1 µm) and a fine mode fraction. The particles from grate combustion of bark contain mostly K, S, Na and Cl apart from oxygen and carbon. When rape seed meal is present, Cl and Na concentrations decrease considerably and the main contents of the particles are K and S (and O and C). The results from the X-ray Diffraction Spectroscopy (XRD) analyses showed the presence of crystalline K2SO4 och KCl. The fine particles (<1 µm) from powder combustion contain mainly K, P and S. The only identified crystalline phase was K2SO4, suggesting that most phosphorus was in the amorphous phase, i.d. most probably molten. The deposit formation on a cooled probe was studied during the fluidized bed and powder combustion experiments. The fine particles deposited during fluidised bed combustion contained K, Cl and S. When bark was combusted in the fluidised bed, the coarse fraction contained Ca and Si, when rape seed meal in different mixes was combusted this changed to P, K, Ca and Mg. The deposits formed during combustion of rape seed meal in the powder burner were mainly made up of phosphates (Ca-, Mg/K-, Ca/Mg-phosphates) and MgO. Sintered material (slag) from grate combustion of bark contained mainly Si, Ca, K and Al, probably as silicates. Adding rape seed meal tended to increase P, Ca and Mg while Si and Ca content tended to decrease. Through XRD a number o crystalline phases in the sintered material and the rest of the bottom ashes could be identified. NO emissions from the combustions tests increased two to four times with rape seed meal compared to typical wood fuels. For the fluidised bed test, SO2 concentrations were rather high for the rape seed meal pellets (with 20 percent wood), still only about 20 percent of the sulphur in the fuel formed SO2. For the grate combustion and powder burner combustion, 60 percent and 70 percent of the sulphur respectively formed SO2. HCl emissions were low for all tests. The rather high emissions of NOx and SOx mean that the material should be used in large-scale facilities with external SOx and NOx cleaning. In smaller facilities, the material may be used in small amounts mixed with other fuels. The risk of slagging is not very high, and should not rule out grate combustion of pellets with rape seed meal mixed with other fuels. The risk of corrosion of superheater surfaces during combustion is probably low since the smaller-size particles formed at fluidised bed combustion and grate combustion contain K2SO4. However, a large fraction of the particles formed in powder burner combustion probably contains low temperature melting K2PO4, making the risk for deposit formation significant. Rape seed meal for powder burner applications should be used with care. The content of phosphorus in the material may be an advantage when mixes of rape seed meal and other fuels are considered. The high affinity between potassium and phosphorus means that more sulphur in the fuel will be available for sulphatising of any KC. (formed from combustion of many forest and agricultural fuels). Use of rape seed meal as a sulphur containing additive could thus be an option. For grate combustion and fluidised bed combustion, addition of rape seed meal may reduce the risk of slagging and bed agglomeration, respectively. Full scale tests in fluidised beds or grate combustors with problematic biofuels (containing Cl and K) would be useful to test whether ash-reduced operational problems could be reduced through the addition of rape seed meal.

  • 300.
    Eriksson, Gunnar
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Jacobsson, Jan-Erik
    Mekanismer för spontan spridning av lönsam energieffektiv teknik1998Rapport (Annet vitenskapelig)
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