| 1. |
- Berntsson, Thore, 1947, et al.
(författare)
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Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)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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| 2. |
- Lyngfelt, Anders, 1955, et al.
(författare)
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11,000 h of chemical-looping combustion operation—Where are we and where do we want to go?
- 2019
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 88, s. 38-56
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Forskningsöversikt (refereegranskat)abstract
- A key for chemical-looping combustion (CLC) is the oxygen carrier. The ultimate test is obviously the actual operation, which reveals if it turns to dust, agglomerates or loses its reactivity or oxygen carrier capacity. The CLC process has been operated in 46 smaller chemical-looping combustors, for a total of more than 11,000 h. The operation involves both manufactured oxygen carriers, with 70% of the total time of operation, and less costly materials, i.e. natural ores or waste materials. Among manufactured materials, the most popular materials are based on NiO with 29% of the operational time, Fe2O3 with 16% and CuO with 13%. Among the monometallic oxides there are also Mn3O4 with 1%, and CoO with 2%. The manufactured materials also include a number of combined oxides with 11% of operation, mostly calcium manganites and other combined manganese oxides. Finally, the natural ores and waste materials include ilmenite, FeTiO3 with 13%, iron ore/waste with 9% and manganese ore with 6%. In the last years a shift towards more focus on CuO, combined oxides and natural ores has been seen. The operational experience shows a large variation in performance depending on pilot design, operational conditions, solids inventory, oxygen carrier and fuel. However, there is at present no experience of the process at commercial or semi-commercial scale, although oxygen-carrier materials have been successfully used in commercial fluidized-bed boilers for Oxygen-Carrier Aided Combustion (OCAC) during more than 12,000 h of operation. The paper discusses strategies for upscaling as well as the use of biomass for negative emissions. A key question is how scaling-up will affect the performance, which again will determine the costs for purification of CO2 through e.g. oxy-polishing. Unfortunately, the conditions in the small-scale pilots do not allow for any safe conclusions with respect to performance in full scale. Nevertheless, the experiences from pilot operation shows that the process works and can be expected to work in the large scale and gives important information, for instance on the usefulness of various oxygen-carriers. Because further research is not likely to improve our understanding of the performance that can be achieved in full scale, there is little sense in waiting with the scale-up. A major difficulty with the scaling-up of a novel process is in the risk. First-of-its-kind large-scale projects include risks of technical mistakes and unforeseen obstacles, leading to added costs or, in the worst case, failure. One way of addressing these risks is to focus on the heart of the process and build it with maximum flexibility for future use. A concept for maximum flexibility is the Multipurpose Dual Fluidized Bed (MDFB). Another is to find a suitable existing plant, e.g. a dual fluidized-bed thermal gasifier. With present emissions the global CO2 budget associated with a maximum temperature of 2 °C may be spent in around 20–25 years, whereas the CO2 budget for 1.5 °C is may be exhausted in 10 years. Thus, the need for both CO2 neutral fuels and negative emissions will become increasingly urgent as we are nearing or transgressing the maximum amount of CO2 that can be emitted without compromising the global climate agreement in Paris saying we must keep “well below” 2 °C and aim for a maximum of 1.5 °C. Thus, biomass may turn out to be a key fuel for Carbon Capture and Storage (CCS), because CO2-free power does not necessarily need CCS, but negative emissions will definitely need Bio-CCS.
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| 3. |
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| 4. |
- Rydén, Magnus, 1975, et al.
(författare)
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Negative CO2 Emissions with Chemical-Looping Combustion of Biomass - A Nordic Energy Research Flagship Project
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 114, s. 6074-6082
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Konferensbidrag (refereegranskat)abstract
- The Nordic countries constitute a natural location for the development and deployment of Bio-Energy with Carbon Capture and Storage (BECCS). Finland, Sweden and Denmark are world-leading with respect to heat and power generation from sustainable biomass. Norway is world-leading with respect to Carbon Capture and Storage (CCS). The Nordic countries also have ambitious targets for reductions of their CO2 emissions, host leading technology providers, and have large biomass potential per capita. System studies suggest that bioenergy could be the single largest energy carrier in the Nordic countries by 2050. Negative CO2 Emissions with Chemical Looping Combustion of Biomass is a multi-partner project with the goal to develop new technology that: i) enables CO2 capture and negative CO2 emissions at the lowest possible cost, ii) is able to produce power and steam for industrial and other applications, iii) utilizes Nordic expertise in fluidized bed technology and iv) has potential to achieve improved fuel utilization. The technology capable of achieving these goals is Chemical-Looping Combustion of biomass (Bio-CLC). The article presents the project and features some early results from its implementation.
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| 5. |
- Rydén, Magnus, 1975, et al.
(författare)
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Novel oxygen-carrier materials for chemical-looping combustion and chemical-looping reforming; LaxSr1─xFeyCo1─yO3─δ perovskites and mixed-metal oxides of NiO, Fe2O3 and Mn3O4
- 2008
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Ingår i: International Journal of Greenhouse Gas Control. - 1750-5836. ; 2:1, s. 21-36
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxygen-carrier materials for chemical-looping applications have been examined by reduction with CH4 and oxidation with air in a fixed-bed quartz reactor at 900ºC. Four perovskite materials, three metal-oxide materials and four metal-oxide mixtures have been studied. It was found that LaxSr1─xFeO3─δ perovskites provided very high selectivity towards CO/H2 and should be well suited for chemical-looping reforming. Substituting La for Sr was found to increase the oxygen capacity of these materials, but reduced the selectivity towards CO/H2 and the reactivity with CH4. La0.5Sr0.5Fe0.5Co0.5O3─δ was found to be feasible for chemical-looping combustion applications. NiO/MgAl2O4 propagated formation of solid carbon, likely due to the catalytic properties of metallic Ni. Fe2O3/MgAl2O4 had properties that made it interesting both for chemical-looping combustion and chemical-looping reforming. Adding 1% NiO particles to a bed of Fe2O3-particles increased both reactivity with CH4 and selectivity towards CO/H2 for reforming applications. Mn3O4/MgZrO2 was found to be suitable for chemical-looping combustion applications, but it could not be verified that adding NiO produced any positive effects.
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| 6. |
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| 7. |
- Abad, Alberto, 1972, et al.
(författare)
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Fuel reactor model validation: Assessment of the key parameters affecting the chemical-looping combustion of coal
- 2013
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 19, s. 541-551
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Tidskriftsartikel (refereegranskat)abstract
- The success of a Chemical Looping Combustion (CLC) system for coal combustion is greatly affected by the performance of the fuel reactor. When coal is gasified in situ in the fuel reactor, several parameters affect the coal conversion, and hence the capture and combustion efficiencies. In this paper, a mathematical model for the fuel reactor is validated against experimental results obtained in a 100 kW(th) CLC unit when reactor temperature, solids circulation flow rate or solids inventory are varied. This is the first time that a mathematical model for Chemical Looping Combustion of coal with in situ gasification (iG-CLC) has been validated against experimental results obtained in a continuously operated unit. The validated model can be used to evaluate the relevance of operating conditions on process efficiency. Model simulations showed that the reactor temperature, the solids circulation flow rate and the solids inventory were the most relevant operating conditions affecting the oxygen demand. However, high values of the solids circulation flow rate must be prevented because they cause a decrease in the CO2 capture. The high values of CO2 capture efficiency obtained were due to the highly efficient carbon stripper. The validated model is a helpful tool in designing the fuel reactor to optimize the CLC process. A CO2 capture efficiency of eta(CC) = 98.5% and a total oxygen demand of Omega(T) = 9.6% is predicted, operating at 1000 C and 1500 kg/MWth in the fuel reactor.
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| 8. |
- Abad, Alberto, 1972, et al.
(författare)
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The use of iron oxide as oxygen carrier in a chemical-looping reactor
- 2007
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 86:7-8, s. 1021-1035
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-looping combustion (CLC) is a method for the combustion of fuel gas with inherent separation of carbon dioxide. This technique involves the use of two interconnected reactors, an air reactor and a fuel reactor. The oxygen demanded in the fuel combustion is supplied by a solid oxygen carrier, which circulates between both reactors. Fuel gas and air are never mixed and pure CO2 can be obtained from the flue gas exit. This paper presents the results from the use of an iron-based oxygen-carrier in a continuously operating laboratory CLC unit, consisting of two interconnected fluidized beds. Natural gas or syngas was used as fuel, and the thermal power was between 100 and 300 W. Tests were performed at four temperatures: 1073, 1123, 1173 and 1223 K. The prototype was successfully operated for all tests and stable conditions were maintained during the combustion. The same particles were used during 60 h of hot fluidization conditions, whereof 40 h with combustion. The combustion efficiency of syngas was high, about 99% for all experimental conditions. However, in the combustion tests with natural gas, there was unconverted methane in the exit flue gases. Higher temperature and lower fuel flows increase the combustion efficiency, which ranged between 70% and 94% at 1123 K. No signs of agglomeration or mass loss were detected, and the crushing strength of the oxygen carrier particles did not change significantly. Complementary experiments in a batch fluidized bed were made to compare the reactivity of the oxygen carrier particles before and after the 40 h of operation, but the reactivity of the particles was not affected significantly.
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| 9. |
- Abanades, J. C., et al.
(författare)
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Emerging CO2 capture systems
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 40, s. 126-166
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Tidskriftsartikel (refereegranskat)abstract
- In 2005, the IPCC SRCCS recognized the large potential for developing and scaling up a wide range of emerging CO2 capture technologies that promised to deliver lower energy penalties and cost. These included new energy conversion technologies such as chemical looping and novel capture systems based on the use of solid sorbents or membrane-based separation systems. In the last 10 years, a substantial body of scientific and technical literature on these topics has been produced from a large number of R&D projects worldwide, trying to demonstrate these concepts at increasing pilot scales, test and model the performance of key components at bench scale, investigate and develop improved functional materials, optimize the full process schemes with a view to a wide range of industrial applications, and to carry out more rigorous cost studies etc. This paper presents a general and critical review of the state of the art of these emerging CO2 capture technologies paying special attention to specific process routes that have undergone a substantial increase in technical readiness level toward the large scales required by any CO2 capture system.
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| 10. |
- Adanez-Rubio, Inaki, et al.
(författare)
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Investigation of Combined Supports for Cu-based Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU)
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:7, s. 3918-3927
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Tidskriftsartikel (refereegranskat)abstract
- The chemical-looping with oxygen uncoupling (CLOU) process is a novel solution for efficient combustion with inherent separation of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor. In the fuel reactor, the metal oxide releases gas phase oxygen which oxidizes the fuel through normal combustion. In this study, Cu-based oxygen carrier materials that combine different supports of MgAl2O4, TiO2 and SiO2 are prepared and characterized with the objective of obtaining highly reactive and attrition resistant particles. The oxygen carrier particles were produced by spray-drying and were calcined at different temperatures ranging from 950 to 1030oC for 4 h. The chemical-looping performance of the oxygen carriers was examined in a batch fluidized-bed reactor in the temperature range of 900-950oC under alternating reducing and oxidizing conditions. The mechanical stability of the oxygen carriers was tested in a jet-cup attrition rig. All of the oxygen carriers showed oxygen uncoupling behaviour with oxygen concentrations close to equilibrium. During reactivity tests with methane, oxygen carriers with lower mechanical stability showed higher reactivity, yielding almost complete fuel conversion. Oxygen carrier materials based on support mixtures of MgAl2O4/TiO2, MgAl2O4/SiO2 and TiO2/SiO2 showed a combination of high mechanical stability, low attrition rates, good reactivity with methane and oxygen uncoupling behaviour.
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