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  • 1.
    Baratieri, Marco
    et al.
    Faculty of Science and Technology Free Universty of Bozen, Bozen, Italy.
    Pieratti, Elisa
    Dept.of Civil and Environment Engineering, University of Trento, Trento, Italy.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Grigiante, Maurizio
    Dept.of Civil and Environment Engineering, University of Trento, Trento, Italy.
    Biomass Gasification with Dolomite as Catalyst in a Small Fluidized Bed Experimental and Modelling Analysis2010In: Waste and Biomass Valorization, ISSN 1877-2641, Vol. 1, no 3, p. 283-291Article in journal (Refereed)
    Abstract [en]

    Purpose Actually, one of the main challenges to be achieved in biomass gasification is the minimization of tar concentration in combination with optimization of the gas composition. An extensive examination has been performed in order to expose the effect of several Chinese dolomites as a catalyst for tar cracking and gas composition enhancement. In this paper, the experimental data collected are presented. Methods Thebiomass gasification tests have been performed in a laboratory small-scale atmosphericfluidized bed gasifier that uses nitrogen as a fluidizing media and pure oxygen as gasifying agent. The system is equipped with a ceramic filter and a catalytic bed. Different types of dolomites have been used as catalyst. Results The main results are that thedolomite reduces the tar concentration and at the same time increases the permanent gas yield. A gasification equilibrium model, written in Matlab environment, has been developed to predict the synthesis gas composition. Main conclusions Several biomassgasification tests have been performed to assess the dolomite effect on the syngas and tar composition. The results have been used to tune an equilibrium model up. The model has been modified with some experimental data and it seems to predict with good accuracy the syngas composition.

  • 2.
    Nemanova, Vera
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Brundu, M.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Biomass gasification in an atmospheric fluidised bed: Probability to employ metallic iron as a tar reduction catalyst.2009In: 17th European Biomass Conference, 2009Conference paper (Refereed)
  • 3.
    Nemanova, Vera
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Engvall, Klas
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Biomass gasification in an atmospheric fluidised bed: Tar reduction with experimental iron-based granules from Höganäs AB, Sweden2011In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 176, no 1, p. 253-257Article in journal (Refereed)
    Abstract [en]

    The present study investigates the effect of several experimental iron-based granules on biomass tar decomposition. The iron-based materials were provided by Höganäs AB and were all in their metallic state when they were applied in a secondary catalytic reactor. Bark-free birch was employed as fuel in an atmospheric fluidised bed reactor, and the tar concentration and gas composition in the producer gas were measured before and after the catalytic bed. The results demonstrate a clear tar reduction capacity for all the tested iron-based materials.

  • 4.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Iron-based materials as tar cracking catalyst in waste gasification2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The treatment of municipal solid waste (MSW) in Sweden has changed during the past decades due to national legislation and European Union directives. The former landfills have more or less been abandoned in favour of material recycling and waste incineration. On a yearly basis approximately 2.2 million tonnes waste are incinerated in Sweden with heat recovery and to some extent also with electricity generation, though at a low efficiency. It is desirable to alter this utilisation and instead employ MSW as fuel in a fluid bed gasification process. Then electrical energy may be produced at a much higher efficiency. However, MSW contain about 1 % chlorine in the form of ordinary table salt (NaCl) from food scraps. This implies that the tar cracking catalyst, dolomite, which is normally employed in gasification, will suffer from poisoning if applied under such conditions. Then the tar cracking capacity will be reduced or vanish completely with time. Consequently, an alternative catalyst, more resistant to chlorine, is needed.

    Preliminary research at KTH has indicated that iron in its metallic state may possess tar cracking ability. With this information at hand and participating in the project “Energy from Waste” an experimental campaign was launched. Numerous experiments were conducted using iron as tar cracking catalyst. First iron sinter pellets from LKAB were employed. They were reduced in situ with a stream of hydrogen before they were applied. Later iron-based granules from Höganäs AB were tested. These materials were delivered in the metallic state. In all tests the KTH atmospheric fluidised bed gasifier with a secondary catalytic reactor housing the catalytic material was deployed. Mostly, the applied fuel was birch. The results show that metallic iron possesses an intrinsic ability, almost in the range of dolomite, to crack tars. Calculations indicate that iron may be more resistant to chlorine than dolomite. The exploration of metallic iron’s excellent tar cracking capacity led to the innovative manufacture of an iron catalytic tar cracking filter as well as a general knowledge of its tar cracking capacity. This filter with dual functionality would be a general improvement of the gasification process since it among other things would make the process denser.

  • 5.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Metallic iron: potential to function as tar breakdown catalyst in waste gasification2005Licentiate thesis, comprehensive summary (Other scientific)
  • 6.
    Nordgreen, Thomas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Elemental iron as a tar breakdown catalyst in conjunction with atmospheric fluidized bed gasification of biomass: A thermodynamic study2006In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 20, no 3, p. 890-895Article in journal (Refereed)
    Abstract [en]

    Metallic iron as a catalyst for tar cracking in biomass gasification has been investigated. Based on previous studies showing that iron must be in its elemental form to catalyze the tar breakdown reactions, thermodynamic calculations suggest the existence of an operating window where iron is neither oxidized nor contaminated by carbon deposits. A straightforward biomass gasification model has been derived and used in conjunction with thermodynamics for making plots that illustrate the mentioned operating window, which is achievable under real conditions. Experiments made under these specific calculated conditions confirm that elemental iron effectively acts as a tar breakdown catalyst, resulting in an improved gas yield and a decrease in tar concentration. The desired operating window is governed mainly by adjusting the oxygen input (i.e., the equivalence ratio) and the temperature.

  • 7.
    Nordgreen, Thomas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Metallic iron as a tar breakdown catalyst related to atmospheric, fluidised bed gasification of biomass2006In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 85, no 06-maj, p. 689-694Article in journal (Refereed)
    Abstract [en]

    Tar formation is a major drawback when biomass is converted in a gasifier to obtain gas aimed for utilisation in power production plants or for production of chemicals. Catalytic cracking is an efficient method to diminish the tar content in the gas mixture. In this study, the capability of metallic iron and iron oxides to catalytically crack tars has been experimentally examined. To obtain metallic iron, small grains of hematite (Fe2O3) were placed in a secondary reactor downstream the gasifier and reduced in situ prior to catalytic operation. The fuel used in the atmospheric fluidised bed gasifier was Swedish birch with a moisture content of approximately 7 wt%. The influence of temperature in the range 700-900 degrees C and), values (i.e. equivalence ratio, ER) between 0 and 0.20 have been investigated. In essence, the results show that raising the temperature in the catalytic bed to approximately 900 degrees C yields almost 100% tar breakdown. Moreover, increasing the). value also improves the overall tar cracking activity. The iron oxides did not demonstrate any catalytic activity.

  • 8.
    Nordgreen, Thomas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Nemanova, Vera
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Iron-based materials as tar depletion catalysts in biomass gasification: Dependency on oxygen potential2012In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 95, no 1, p. 71-78Article in journal (Refereed)
    Abstract [en]

    A study has been performed using experimental iron based granules as a tar breakdown catalyst in a biomass gasification gas. Previous examinations established that metallic iron located in a separate catalytic bed reactor has a stronger influence on the tar content and composition in the product gas than their corresponding iron oxides. The results from the present study show that tar diminution in the product gas is dependent on temperature, catalyst material and oxygen potential. Typically, values of 50-75% tar reduction were achieved when varying the catalytic bed temperature between 750 and 850 degrees C. Also, the oxidation state of the catalyst material has an influence on the tar content and gas composition in the gas. When changing the gasification temperature from 800 degrees C to 850 degrees C the oxygen potential in the producer gas also changes, resulting in a transition from oxidative to reductive conditions in the gas. This implies that when the gasification temperature is 800 degrees C, the catalyst is transformed from its metallic state to the iron oxide, wustite. Consequently, the tar reduction capacity of the catalyst is reduced by approximately 20%. In view of the overall results it can be concluded that the catalysts in their metallic states in general exhibits a better tar cracking capacity than their corresponding oxides. The iron material used is sintered iron powders manufactured at Hoganas AB, Sweden. The iron materials were dispensed in the metallic state.

  • 9.
    Nordgreen, Thomas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Partial oxidation of methane in a biomass gasification gas2007In: Proceedings of the 15th EU BC&E - Berlin 2007, 2007Conference paper (Refereed)
  • 10.
    Valderrama, Cesar
    et al.
    Univ Politecn Cataluna, Dept Chem Engn, Barcelona Tech, Barcelona, Spain..
    Hagström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nordgreen, Thomas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Shared curriculum at KTH and UPC universities Blended learning experience at the MSc SELECT programme2018In: PROCEEDINGS OF 2018 IEEE GLOBAL ENGINEERING EDUCATION CONFERENCE (EDUCON) - EMERGING TRENDS AND CHALLENGES OF ENGINEERING EDUCATION, IEEE , 2018, p. 669-676Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to present the experience and lessons learned of experimental implementing of blended learning methodology in the Master programme "Environomical Pathways for Sustainable Energy Systems" (SELECT) at the Royal Institute of Technology' (KTH in Stockholm) and the Universitat Politecnica de Catalunya.BarcelonaTech (UPC in Barcelona), in common and remotely taught courses (shared curriculum) under a transnational framework. Shared curriculum has been designed and strongly connected to the intended learning outcomes (ILO's) of the programme. Blended learning was implemented to improve the efficiency of the learning process through updated technological means of instruction and to have the same curriculum with equally shared teaching load to ensure that students by the end of year I have the same competence and background. It can be noted that, at least from the perspective of academic performance, the implementation of blended learning in the shared SELECT curriculum does not have a significant impact, although local students show slightly higher grade point average (GPA). Finally and from our general experience with students, it is possible to identify the interaction of communication as one of the key challenges and factors in blended education.

  • 11.
    Yu, Q. Z.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Brage, Claes O.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Nordgreen, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Effects of Chinese dolomites on tar cracking in gasification of birch2009In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 88, no 10, p. 1922-1926Article in journal (Refereed)
    Abstract [en]

    To minimize tar in the producer gas from birch gasification at 700, 750 and 800 degrees C, four Chinese dolomites (Zhenjiang, Nanjing, Shanxi, Anhui) and a Swedish dolomite (Sala) used as reference were studied in a laboratory-scale atmospheric fluidized bed gasifier. The gasifier was equipped with a downstream fixed catalyst bed. The results imply that all dolomites but Anhui dolomite effectively decompose tar into gases. Anhui dolomite showed a low catalytic capacity to crack tar produced at 700 and 800 degrees C. The influence of various ratios of steam to biomass on tar content in the producer gas after passing over dolomite was studied. The tar cracking efficiency of the dolomites did not improve significantly with the ratio of steam to biomass in the region 0.11-0.52.

1 - 11 of 11
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