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Träfflista för sökning "LAR1:cth ;pers:(Lyngfelt Anders 1955);conttype:(scientificother);srt2:(2005-2009)"

Sökning: LAR1:cth > Lyngfelt Anders 1955 > Övrigt vetenskapligt > (2005-2009)

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1.
  • Berntsson, Thore, 1947-, et al. (författare)
  • Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
  • 2008
  • Rapport (övrigt vetenskapligt)abstract
    • In this report, the Chalmers EnergiCentrum (CEC) presents the results of a pre-study commissioned by Preem relating to the effective production of future vehicle fuels. This pre-study was made up of three studies focusing on energy streamlining, the utilisation of waste heat and carbon-dioxide separation and biorefinement relating to the gasification and hydration of vegetable oils. One of the common starting points for these studies was the current situation at the Preem refineries in Göteborg and Lysekil from where the measurement data were obtained and analysed. The report summarises the knowledge situation based on current research in the individual technical fields. The results present some interesting future opportunities for developing the sustainable production of future vehicle fuels. The sections vary, as the areas that have been examined differ and the sections have been written by different people. The reports ends with some joint conclusions and a number of questions which could be included and answered in a more extensive future main study, as part of a developed research partnership between Preem and the Chalmers University of Technology. The preliminary results of this work were analysed with the client at workshops on 1 October and 29 November 2007. The report is written in English combined with an extensive summary in Swedish including a proposal on a future main study. The study was conducted by the Chalmers EnergiCentrum (CEC), in collaboration with a number of researchers in the CEC’s network. They included Thore Berntsson, Jessica Algehed, Erik Hektor and Lennart Persson Elmeroth, all from Heat and Power Technology, Börje Gevert, Chemical and Biological Engineering, Tobias Richards, Forest Products and Chemical Engineering, Filip Johnsson and Anders Lyngfelt, Energy Technology, and Per-Åke Franck and Anders Åsblad, CIT Industriell Energianalys AB. The client, Preem, was represented by Bengt Ahlén, Sören Eriksson, Johan Jervehed, Bertil Karlsson, Gunnar Olsson, Ulf Kuylenstierna, Stefan Nyström, Martin Sjöberg and Thomas Ögren. Tobias Richards was responsible for compiling the report and Bertil Pettersson was the project manager.
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  • Leion, Henrik, 1976-, et al. (författare)
  • CO2 capture from direct combustion of solid fuels with Chemical-Looping Combustion
  • 2008
  • Ingår i: The proceedings of the 33rd International Technical Conference on Coal Utilization & Fuel Systems.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • Chemical-looping combustion (CLC) is a combustion technology where an oxygen carrier is used to transfer oxygen from the combustion air to the fuel, thus avoiding direct contact between air and fuel. Thus, the CO2 is inherently separated from the flue gases with a considerable lower energy penalty and cost compared to other techniques for CO2 separation. The oxygen carrier is circulated between two reactors, a fuel and an air reactor, where the flue gas from the air reactor contains only N2 and some unreacted O2 and the flue gas from the fuel reactor contains only CO2 and H2O. The water can easily be condensed and the remaining CO2 can be transported for underground storage. Most of the prior work with CLC has focused on using natural gas and syngas as fuel. However, recent work on adapting the CLC process for solid fuels shows promising results. Two main strategies for achieving this are: 1) using syngas from coal gasification in the fuel reactor and 2) introduction of the coal directly to the fuel reactor where the gasification of the coal and subsequent reactions with the metal oxide particles will occur simultaneously. This paper will focus on this second route, and present results from reactivity investigations in a laboratory fluidized-bed reactor system of a number of different solid fuels, including three types of bituminous coal, petroleum coke, lignite and char from bio fuel. As oxygen carrier the previously investigated natural mineral ilmenite is used. The experiments were conducted at 970°C with 92% steam in the fluidizing gas. The reaction rates were considerably higher compared to investigations using lower steam fractions. The fraction of volatiles in the fuel was found to be important for the conversion rate of the fuel. Furthermore, the presence of an oxygen-carrier was shown to enhance the conversion rate of the intermediate gasification reaction compared with normal gasification performed without the presence of an oxygen carrier. Introduction Chemical-looping combustion (CLC) has been introduced as a technique where the greenhouse gas CO2 is inherently separated during combustion. The CLC-process is composed of two fluidized bed reactors, an air and a fuel reactor. The fuel is introduced to the fuel reactor where it reacts with an oxygen carrier to CO2 and H2O, reaction (1). The reduced oxygen carrier is transported to the air reactor where it is oxidized back to its original state by air, reaction (2). In this paper, when oxidation and reduction is mentioned, it refers to oxidation and reduction of the oxygen carrier.
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  • Leion, Henrik, 1976-, et al. (författare)
  • Combustion of a German lignite using chemical-looping with oxygen uncoupling (CLOU)
  • 2008
  • Ingår i: The Proceedings of 33rd International Technical Conference on Coal Utilization & Fuel Systems.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • Chemical-looping with oxygen uncoupling (CLOU) is a novel method to burn solid fuels in gas-phase oxygen without the need for an energy intensive air separation unit. The carbon dioxide from the combustion is inherently obtained separated from the rest of the flue gases. The technique is based on chemical-looping combustion but involves a completely different reaction mechanism for the fuel oxidation. The process uses three steps in two reactors, one air reactor where a metal oxide captures oxygen from the combustion air (step 1), and a fuel reactor where the metal oxide releases oxygen (step 2) and where this oxygen reacts with a fuel (step 3). This means that the char reacts directly with gaseous O2, which is a very fast reaction. In other proposed schemes for using chemical-looping combustion of solid fuels there is a need for an intermediate gasification step of the char with steam or carbon dioxide to form reactive gaseous compounds which then react with the oxygen carrier particles. The gasification reactions are inherently slow, resulting in slow overall rates of reaction. This is solved in the proposed process, since there is no intermediate gasification step needed and the char reacts directly with gas-phase oxygen. Of course this demands another type of oxygen carrier than those normally used in chemical-looping combustion, and a thermal analysis has identified CuO/Cu2O, Mn2O3/Mn3O4 and Co3O4/CoO as potential systems. Thermodynamic calculations indicate that metal sulphates should not be formed in the fuel reactor during normal operation, although they could be formed locally for Co and Mn-based oxygen carriers at lower temperatures. This work presents results from an investigation of the reaction between a Cu-based oxygen carrier with a German lignite in a batch fluidized bed reactor. A ratio of oxygen carriers to fuel of 6 kg/MJ was employed during the combustion and between 30-45 seconds was needed for 95% conversion of the coal in the temperature interval 850-985C. The oxidation was possible at all temperatures, and a substantial part of the oxidation occurred near the equilibrium O2 concentration. No signs of agglomerations of the oxygen carrier particles were found.
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  • Linderholm, Carl, 1976-, et al. (författare)
  • Chemical-looping combustion with natural gas using spray-dried NiO-based oxygen carriers
  • 2009
  • Ingår i: Advances in CO2 Capture and Storage Technology (2004-2009). - 9781872691497 ; 3, s. 67-74
  • Bokkapitel (övrigt vetenskapligt)abstract
    • The work presented in this chapter demonstrates the economical feasibility of making a good oxygen carrier from commercial raw materials using a commercial production method, i.e. spray-drying. A batch fluidized-bed reactor was used for an extensive screening of many NiO-based oxygen carriers. This screening process led to the production of two major particle batches, which were used in continuous chemical-looping experiments. High-temperature experiments in a batch-fluidized bed verified the thermal durability of the particles. The most important result presented here concerns long-term operation (> 1000 h) of a 10-kWth chemical-looping combustor using spray-dried NiO-based oxygen carriers. Conversion of the fuel was good, and increased with (a) decreased circulation, and (b) increased fuel-reactor temperature. Combustion efficiency close to 99% was accomplished using these spray-dried particles. At the end of the test series, the continuous loss of fine material was 0.003%/h, which corresponds to a particle life time of 33000 h. No decrease in reactivity was seen during these long-term tests. The fuel used in the experiments was natural gas and methane.
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