SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "LAR1:cth ;pers:(Lyngfelt Anders 1955);conttype:(scientificother);lar1:(cth)"

Sökning: LAR1:cth > Lyngfelt Anders 1955 > Övrigt vetenskapligt/konstnärligt > Chalmers tekniska högskola

  • Resultat 11-20 av 69
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
11.
  •  
12.
  •  
13.
  • 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/konstnärligt)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.IntroductionChemical-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.
  •  
14.
  • 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/konstnärligt)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.
  •  
15.
  • Leion, Henrik, 1976, et al. (författare)
  • Coupled CLC and CLOU behaviour for Solid Fuels Conversion
  • 2011
  • Ingår i: Proceedings of the 36th International Technical Conference on Clean Coal and Fuel Systems.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • There are two main strategies for using solid fuels in chemical-looping. The first is conventional Chemical-Looping Combustion (CLC) where the fuel is directly introduced to the fuel reactor with the gasification of the solid fuel and subsequent reactions with the oxygen carrier occurring simultaneously. The second is referred to as Chemical-Looping with Oxygen Uncoupling (CLOU) and requires an oxygen carrier which releases gas-phase O2 in the fuel reactor. The solid fuel is in this case oxidized through normal combustion which is a considerably faster reaction path than in conventional CLC. CLOU also makes it easier to obtain full conversion of the fuel since the oxidation of intermediates can occur in the gas-phase above the bed of oxygen carrier. The difference between CLOU and conventional CLC is determined by the oxygen carrier. If the carrier releases gas-phase O2 it is CLOU, if not it is CLC. But the situation can occur when the rate of O2 release from a CLOU oxygen carrier is comparably slow, and consequently the major reaction mechanism may be CLC. Nevertheless, the oxygen released could be very helpful in improving gas conversion as well as char conversion. This paper presents experimental results and discussed the benefits with this kind of coupled CLC and CLOU behaviour. Experiments were performed in a batch fluidized bed reactor with wood char and petroleum coke used as fuel. The primary oxygen carriers used were manganese-based with different additives such as Fe or Ca. These experiments were compared to both conventional CLC experiments with the iron-titanium mineral ilmenite as oxygen carrier, and to pure CLOU experiments where CuO on Zr2O was used as oxygen carrier. The results indicate that it is possible to utilize a combination of CLOU and conventional CLC. The rate of conversion of char for the combined system is lower as compared to pure CLOU but high compared to conventional CLC. The system also had more or less full char and gas conversion similar to the CLOU case.
  •  
16.
  • Leion, Henrik, 1976, et al. (författare)
  • Investigation on ceria- and doped ceria-supported oxygen carriers for CLC applications
  • 2011
  • Ingår i: Technical Workshop at the 3rd Meeting of the IEA-GHG Network on High Temperature Solids Looping Cycles.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In the area of chemical-looping combustion as a pathway to CO2 sequestration and subsequent storage, major efforts have concentrated on investigating various oxygen carriers supported on inert materials. So, it would be innovative to utilize supports that are participating in the combustion process and thus can act as a minor but additional oxygen carrier or as a facilitating oxidizing catalyst during CLC operation. One of these materials is cerium dioxide (ceria, CeO2), which is used extensively as an integral component of 3-way catalyst in automobiles. In order to exploit the synergy of a composite made up of the active carrier and the participating support, formulations consisting of two-phase mixtures of copper oxide, iron oxide and manganese oxide with pure or doped ceria were fabricated and evaluated for their reactivity in methane and syngas fuel streams. Relevant parameter of significance to CLC process, such as fuel conversion, oxygen release measurement, fluidization properties and, temperature variations during fuel and oxidation cycles, were examined.All the samples showed very good fluidization properties during tests without any agglomeration. Copper oxide-based oxygen carriers showed nearly full conversion of methane with high oxygen release and no sign of defluidization, while iron-based systems exhibited unusually high conversion of methane together with favourable reactivity during oxidation periods after the fuel cycles. The superiority of the GDC-supported materials over those supported on ceria could be interrelated to the better oxygen transport capability of the GDC support due to the oxygen ion vacancies in it by virtue of doping.
  •  
17.
  • Leion, Henrik, 1976, et al. (författare)
  • Using chemical-looping with oxygen uncoupling (CLOU) for combustion six different of solid fuels
  • 2008
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 1:1, s. 447-453
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)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. This paper presents batch laboratory fluidized bed CLOU tests where six different solid fuels are used with a Cu-based oxygen carrier. The results show that CLOU results in a factor 3 to 15 faster fuel conversions than conversional chemical-looping combustion.
  •  
18.
  • Linderholm, Carl Johan, 1976, et al. (författare)
  • Chemical-Looping Coal Combustion – Results from the ACCLAIM project
  • 2014
  • Ingår i: 3rd International Conference on Chemical Looping.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This work concerns the first 22 months of the 30-month ACCLAIM project. The project has involved both experimental activities in CLC pilots of 1.5 kW, 10 kW and 100 kW, as well as laboratory investigations and studies in a cold-flow model. Furthermore, investigations have been made using modelling with different approaches and with different aims.The main result of the pilot operation is that several low-cost materials should be able to improve gas conversion significantly as compared to previously tested ilmenite. Promising low cost materials include iron and manganese ores. Two manganese ores were evaluated by operation in a 10 kW CLC reactor system. These materials are called Sinfin, and Mangagran. Both materials performed well with respect to gas conversion, and oxygen demand was clearly lower as compared to ilmenite. The production rate of fines suggested an expected lifetime of around 300 h for one of the manganese materials, Sinfin, which is a distinct improvement as compared to the Buriturama ore previously tested in the 10 kW unit.Further, the fate of fuel contaminants like sulphur and nitrogen has been investigated. Models to describe fluidization and to predict conversion have been developed and are validated against operational data. Mathematical modelling and cold-flow modelling show possible ways of increasing process performance by modification of process or reactor design.A 100 kW CLC unit was operated with a mixture of ilmenite and a Brazilian manganese ore called Buritirama, which had been tested in a previous project and had been found to be much more reactive than ilmenite, although concerns had been raised regarding the attrition resistance. The mixture of ilmenite and Buritirama gave significant improvements in gas conversion in comparison to ilmenite.
  •  
19.
  • Linderholm, Carl Johan, 1976, et al. (författare)
  • Chemical-looping combustion of solid fuels
  • 2015
  • Ingår i: Calcium and Chemical Looping Technology for Power Generation and Carbon Dioxide (CO2) Capture. - 9780857092434 ; , s. 299-326
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Chemical-looping combustion (CLC) of solid fuels is a novel combustion technology with the potential to drastically reduce the costs associated with CO2 capture. In this chapter, the costs and energy penalty of CO2 capture using CLC with solid fuel are compared with corresponding costs using other capture technologies. Furthermore, the operational experience in continuous units reported in the literature is explored: principal layout of reactor systems, fuels and oxygen carriers used in these systems, time of operation, and fuel-reactor temperature. The chapter also looks at the CLC process from a fuel perspective-how does the choice of fuel affect the process?
  •  
20.
  • Linderholm, Carl Johan, 1976, et al. (författare)
  • Chemical-looping combustion of solid fuels in a 10 kWth pilot – Batch tests with five fuels
  • 2011
  • Ingår i: Energy Procedia. 10th International Conference on Greenhouse Gas Control Technologies; Amsterdam; 19-23 September 2010. - : Elsevier BV. - 1876-6102. ; 4, s. 385-392
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Chemical-looping combustion (CLC) is a combustion concept with inherent separation of CO2. The process uses a solidoxygen carrier, which consists of metal oxide, to transfer the oxygen from air to fuel. This paper presents findings from batch tests performed in a 10 kWth CLC pilot for solid fuels. The pilot, which is the world’s first chemical-looping combustor for solid fuels, is based on interconnected fluidized-bed technology and features a fuel reactor (FR) and an air reactor (AR) as the principalreaction chambers. In the FR, fuel is gasified with steam whereupon gasification products react with the oxygen carrier to form, ideally, CO2, H2O and SO2. Oxygen-carrier particles exit the FR through a weir and are led to the AR, where they are regenerated to their oxidized state. The pilot has been operated using a natural iron-titanium ore called ilmenite as oxygen carrier. Previous continuous tests have demonstrated a need for batch tests in order to obtain complementary information on system performance.In this study, five fuels were fed to the fuel reactor in batches of 20-25 g at four temperatures; 940°C, 970°C, 1000°C and 1030°C. By using devolatilized fuel, it was possible to determine (a) oxygen demand associated with syngas from char gasification as well as (b) kinetics of char conversion to gas. Rates of char conversion were found to be temperature dependent, as expected, whereas no temperature dependence was found for the oxygen demand. Activation energies for conversion of char to gas were calculated using Arrhenius plots. The minimum oxygen demand for char was found to be around 5%.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 11-20 av 69
Typ av publikation
konferensbidrag (40)
bokkapitel (14)
tidskriftsartikel (11)
rapport (3)
patent (1)
Typ av innehåll
Författare/redaktör
Mattisson, Tobias, 1 ... (41)
Rydén, Magnus, 1975 (16)
Leion, Henrik, 1976 (9)
Leckner, Bo G, 1936 (9)
Linderholm, Carl Joh ... (7)
visa fler...
Adánez, Juan (6)
Johansson, Marcus, 1 ... (5)
Åmand, Lars-Erik, 19 ... (5)
Beal, Corinne (5)
Epple, Bernd (3)
Johnsson, Filip, 196 ... (2)
Azimi, Golnar, 1985 (2)
Snijkers, Frans (2)
Jerndal, Erik, 1980 (2)
Mei, Daofeng, 1986 (2)
Karlsson, Maria, 198 ... (2)
Abad, Alberto, 1972 (1)
Williams, Gareth (1)
Ciais, Philippe (1)
Jacobs, Marijke (1)
Franck, Per-Åke, 195 ... (1)
Berntsson, Thore, 19 ... (1)
Canadell, Josep G. (1)
Jackson, Robert B. (1)
Algehed, Jessica, 19 ... (1)
Åsblad, Anders, 1956 (1)
Peters, Glen P. (1)
Hildor, Fredrik, 199 ... (1)
Wolf, Jens (1)
Hedayati, Ali, 1984 (1)
Azad, Abdul-Majeed, ... (1)
Richards, Tobias, 19 ... (1)
Jing, Dazheng, 1986 (1)
Larring, Yngve (1)
Joumani, Y (1)
Bergqvist, Klas (1)
Persson Elmeroth, Le ... (1)
Hektor, Erik, 1978 (1)
Gevert, Börje Sten, ... (1)
Biermann, Max, 1989 (1)
Denafas, Gintaras (1)
Fuss, Sabine (1)
Iqbal, A (1)
Cho, P. (1)
Cuadrat, Ana, 1982 (1)
Jones, Chris D. (1)
van Vuuren, Detlef P ... (1)
Gogolev, Ivan, 1984 (1)
MAYER, K (1)
visa färre...
Lärosäte
Språk
Engelska (67)
Svenska (2)
Forskningsämne (UKÄ/SCB)
Teknik (67)
Naturvetenskap (10)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy