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Juan Adánez - One of the best experts on this subject based on the ideXlab platform.
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evaluation of different strategies to improve the efficiency of coal conversion in a 50 kwth chemical looping combustion unit
Fuel, 2020Co-Authors: A Abad, F Garcialabiano, P Gayan, L F De Diego, R Perezvega, T Mendiara, M Izquierdo, Juan AdánezAbstract:Abstract Minerals or industrial waste Materials are considered promising Oxygen Carriers for coal combustion through in-situ Gasification Chemical Looping Combustion (iG-CLC) process in order to maintain CO2 capture at low cost. Nevertheless, complete coal combustion to CO2 and H2O is usually not achieved and different solutions have been outlined to improve it. The aim of this work is to analyze the potential of two of these strategies: (1) using a more reactive Oxygen Carrier; and (2) to have two fuel reactors by feeding the coal into the carbon stripper. Coal combustion in a 50 kWth CLC unit was carried out using two Oxygen Carrier Materials, namely Norwegian ilmenite and Tierga iron-ore. Also, an additional test was carried out feeding the coal directly into the carbon stripper of the CLC unit, in contrast with the conventional coal feeding to the fuel reactor. CO2 capture efficiency was barely affected by the type of Oxygen Carrier Material, but slightly lower values were obtained when coal was fed to the carbon stripper. In contrast, coal combustion efficiency was enhanced by using the iron-ore Material, with a potential decrease of the total Oxygen demand of 40%, achieving a minimum value of total Oxygen demand of 4.1%. Also, the total Oxygen demand was decreased by 24% when coal was fed to the carbon stripper due to the improvement in the combustion of the volatiles in the fuel reactor. The combination of both strategies has high potential to maximize the coal combustion via iG-CLC process.
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fe2o3 al2o3 Oxygen Carrier Materials for chemical looping combustion a redox thermodynamic and thermogravimetric evaluation in the presence of h2s
Journal of Thermal Analysis and Calorimetry, 2018Co-Authors: Mehdi Pishahang, Juan Adánez, P Gayan, Yngve Larring, Martin F SundingAbstract:Alumina-supported Fe2O3 Oxygen Carrier Material (OCM) system is among the most promising OCM systems for solid and gaseous fuel CLC. This work utilizes a comprehensive thermogravimetric and thermodynamic equilibrium approach to redox and CLOU performance, Oxygen transfer capacity, reduction rate and sulfur tolerance of the Fe2O3 impregnated on Al2O3 OCM. Thermodynamic evaluations reveal that the beneficial composition range lies in a wide range of 7.5–34% molar Fe2O3 ratios. This is the range at which aluminum-rich corundum phase, i.e., (Al, Fe)2O3, remains stable throughout the oxidizing to very reducing Oxygen partial pressures in fuel reactor. The experimental system in this study contains 20 mass% Fe2O3, i.e., XFe = 13.8% molar which lies well within this interval. Deep redox cycle experiments confirm the thermodynamic modeling and during the long residence time of this experiment, the sample is almost fully reduced and exhibits its thermodynamic redox Oxygen capacity of close to 1.5 mass%. Extension of the deep redox cycles to 15 cycles induces no performance deterioration in terms of capacity, rate of reduction or morphological failure. The redox experiment under sour reducing gas indicates no H2S poisoning for the 20 mass% Fe2O3 supported on Al2O3 OCM. The findings that this system is not affected with the H2S content of the gas, and the prediction of the SO2 release from the fuel reactor is in good agreement with our recent reactor testing findings available in the literature.
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titanium substituted manganese ferrite as an Oxygen Carrier with permanent magnetic properties for chemical looping combustion of solid fuels
Fuel, 2017Co-Authors: Maria Abian, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Luis F De Diego, Juan AdánezAbstract:Abstract Mixed oxides of Mn-Fe have been identified as suitable Materials for Chemical Looping Combustion (CLC) with solid fuels both via in-situ Gasification Chemical Looping Combustion ( i G-CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) processes. These Materials show the property of react with gaseous fuels as well as release Oxygen under given conditions, while cheap metals are used. In addition, these Materials can show magnetic properties that can be used for an easy separation from ash in CLC with solid fuels. Thus, losses of Oxygen Carrier Material in the ash drain stream would be reduced. Different cations have been proposed for improving the magnetic properties of manganese ferrites, including Ti 4+ . In this context, the present work accomplishes a screening of (Mn x Fe 1−x ) 2 O 3 doped with 7 wt.% TiO 2 , with x ranging from 0 to 1. The influence of Mn:Fe ratio on their physical and chemical properties was evaluated. In general, particles with high crushing strength values (>4 N) were obtained, and magnetic characteristics were highlighted when x ⩽ 0.66. The Oxygen uncoupling capability depended on the Mn:Fe ratio and the oxidation conditions, i.e. temperature and Oxygen partial pressure. Broader oxidation conditions to take advantage of the Oxygen uncoupling capability were found for Materials with low Mn content. On contrary, the reactivity with fuel gases (CH 4 , H 2 and CO) increased with the Mn content. Thus, Oxygen Carriers with Mn/(Mn + Fe) molar ratio in the 0.5–0.9 interval showed interesting properties at suitable temperatures for the i G-CLC and CLOU processes (i.e. 850–980 °C). The Material with Mn/(Mn + Fe) = 0.55 was preferred considering a trade-off between reactivity and magnetic properties.
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long lasting cu based Oxygen Carrier Material for industrial scale in chemical looping combustion
International Journal of Greenhouse Gas Control, 2016Co-Authors: Arturo Cabello, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, L F De Diego, Andrew Scullard, Gareth Williams, Juan AdánezAbstract:Abstract One of the most important current objectives of the Chemical Looping Combustion (CLC) technology for gaseous fuels lies in scaling-up the aforementioned technology in the short term from 100 kW th to 10 MW th scale. In order to meet this challenge, the commercial availability of suitable multi ton-scale Oxygen Carrier Materials at competitive price is needed. In this work, a Cu-based Oxygen Carrier prepared by the impregnation method using a commercial alumina as support, referred as Cu14γAl_Commercial, has been developed and evaluated in a 500 W th CLC pilot plant during the combustion of CH 4 at two different temperatures, i.e., 800 °C and 900 °C. The outstanding results obtained in terms of both combustion efficiency and mechanical stability have shown that the Cu14γAl_Commercial impregnated Oxygen Carrier can be selected to upscale CLC technology for gaseous fuels.
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redox kinetics of camg0 1ti0 125mn0 775o2 9 δ for chemical looping combustion clc and chemical looping with Oxygen uncoupling clou
Chemical Engineering Journal, 2015Co-Authors: A Abad, P Gayan, F Garcialabiano, L F De Diego, Juan AdánezAbstract:Abstract The objective of this study was to establish the kinetic of reactions involved in redox cycles of an Oxygen Carrier Material based on a perovskite type structure with the formula CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ . The Oxygen transport capacity and reactivity of this Material during reduction with gaseous fuels (CH 4 , H 2 and CO) and the subsequent oxidation with Oxygen are studied in a TGA apparatus. Besides, the Oxygen uncoupling properties of this Material are analysed. Thus, kinetics for relevant reactions involved in Chemical Looping Combustion (CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) were determined. CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ reactivity increased with the number of redox cycles, whereas the total Oxygen transport capacity decreased from 8.5 to 8.0 wt.%. Particles that reached the maximum reactivity were denoted as “activated” Material. Kinetics for both fresh and “activated” particles was determined. Conversion vs. time curves at different temperatures (973–1273 K), and reacting gas concentration (5–60 vol.% for CH 4 , H 2 or CO; 5–21 vol.% for O 2 ) were obtained for both fresh and “activated” Material. For kinetics determination, the shrinking core model with control by chemical reaction and diffusion through the product layer was used to obtain the kinetic parameters.
Henrik Leion - One of the best experts on this subject based on the ideXlab platform.
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apparent kinetics derived from fluidized bed experiments for norwegian ilmenite as Oxygen Carrier
Journal of environmental chemical engineering, 2014Co-Authors: Georg L Schwebel, Sebastian E Sundqvist, Wolfgang Krumm, Henrik LeionAbstract:Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the Oxygen Carrier Material will be lowered preferring low cost and environmental sound Materials. In this work apparent kinetics for the reduction of a natural rock ilmenite from Norway are derived from experimental data while utilizing CO, H2 and CH4 as fuel gases. CO, H2 and CH4 are the main combustible gases in solid fuel CLC. The experiments were carried out in a laboratory batch fluidized bed reactor. The reactor was heated to bed temperatures varying from 850 to 950 °C. Different fuel gas concentrations were achieved by diluting the fuel flow with nitrogen. For H2, pulsed reduction experiments have been accomplished to allow the calculation of conversion dependent rates. The experimental conversion rates were fitted to different model approaches in order to derive the apparent kinetic parameters. Thereby the Oxygen Carrier conversion was represented by the mass based conversion ω. The results are compared to published data. The reaction order with respect to the gas phase is close to the reported values. Only the reaction order obtained for CH 4 with the fitted power law deviated with about 40%, what could indicate a limitation of available surface for the heterogeneous decomposition of CH4. Although the overall agreement between fitted power laws and experimental data was appropriate, their extrapolation outside the experimental data range has to be done with care. © 2014 Elsevier Ltd.
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apparent kinetics derived from fluidized bed experiments for norwegian ilmenite as Oxygen Carrier
Journal of environmental chemical engineering, 2014Co-Authors: Georg L Schwebel, Sebastian E Sundqvist, Wolfgang Krumm, Henrik LeionAbstract:Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the Oxygen Carrier Material will be lowered preferring low cost and environmental sound Materials. In this work apparent kinetics for the reduction of a natural rock ilmenite from Norway are derived from experimental data while utilizing CO, H2 and CH4 as fuel gases. CO, H2 and CH4 are the main combustible gases in solid fuel CLC. The experiments were carried out in a laboratory batch fluidized bed reactor. The reactor was heated to bed temperatures varying from 850 to 950 °C. Different fuel gas concentrations were achieved by diluting the fuel flow with nitrogen. For H2, pulsed reduction experiments have been accomplished to allow the calculation of conversion dependent rates. The experimental conversion rates were fitted to different model approaches in order to derive the apparent kinetic parameters. Thereby the Oxygen Carrier conversion was represented by the mass based conversion ω. The results are compared to published data. The reaction order with respect to the gas phase is close to the reported values. Only the reaction order obtained for CH 4 with the fitted power law deviated with about 40%, what could indicate a limitation of available surface for the heterogeneous decomposition of CH4. Although the overall agreement between fitted power laws and experimental data was appropriate, their extrapolation outside the experimental data range has to be done with care. © 2014 Elsevier Ltd.
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cuo based Oxygen Carrier particles for chemical looping with Oxygen uncoupling experiments in batch reactor and in continuous operation
Industrial & Engineering Chemistry Research, 2014Co-Authors: Magnus Ryden, Henrik Leion, Anders Lyngfelt, Dazheng Jing, Malin Kallen, Tobias MattissonAbstract:Chemical-looping with Oxygen uncoupling (CLOU) is an innovative method to oxidize fuels with inherent CO2 sequestration, which utilizes a solid Oxygen-Carrier Material to provide O-2 for fuel combustion. In this study, a range of CuO-based Oxygen-Carrier particles have been manufactured and examined. Out of 24 samples prepared, 10 were examined in a batch fluidized-bed reactor, of which three were selected for further examination by continuous operation in a small circulating fluidized-bed reactor system. Composite particles consisting of CuO as active phase and support Material such as ZrO2, YSZ, CeO2, and MgAl2O4 were capable of providing full conversion of CH4 at 900 and 925 degrees C, and were also found to release gas phase O-2 into inert atmosphere when fluidized with N-2. Particles using semiactive support such as Fe2O3, Mn2O3, and Al2O3 formed combined spinel phases with CuO. Such Materials were still capable of releasing gas phase O-2 but at different concentrations as compared to particles with inert support. Materials with semiactive support had less good reactivity with CH4. No formation of unexpected phases could be detected by X-ray diffractometry, and all chemical reactions were completely reversible. The three Materials that were examined in continuous operation were readily capable of providing more or less full conversion of natural gas under the chosen conditions. However, they also suffered from quick attrition and turned into a flour-like substance after a few hours of continuous operation with fuel. Crushing strength analysis showed that particles used in continuous operation were physically much weaker than fresh. In total, 23 h of continuous operation with fuel addition was recorded.
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combined oxides as Oxygen Carrier Material for chemical looping with Oxygen uncoupling
Applied Energy, 2014Co-Authors: Magnus Ryden, Henrik LeionAbstract:Oxygen-Carrier Materials for chemical-looping with Oxygen uncoupling (CLOU) must be capable of taking up and releasing gas-phase O2 at conditions relevant for generation of heat and power. In principle, the capability of a certain Material to do so is determined by its thermodynamic properties. This paper provides an overview of the possibility to design feasible Oxygen Carrier Materials from combined oxides, i.e. oxides with crystal structures that include several different cations. Relevant literature is reviewed and the thermodynamic properties and key characteristics of a few selected combined oxide systems are calculated and compared to experimental data. The general challenges and opportunities of the combined oxide concept are discussed. The focus is on Materials with manganese as one of its components and the following families of compounds and solid solutions have been considered: (MnyFe1−y)Ox, (MnySi1−y)Ox, CaMnO3−δ, (NiyMn1−y)Ox, (MnyCu1−y)Ox and (MnyMg1−y)Ox. In addition to showing promise from a thermodynamic point of view, reactivity data from experimental investigations suggests that the rate of O2 release can be high for all systems. Thus these combined oxides could also be very suitable for practical application.
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camn0 875ti0 125o3 δ as Oxygen Carrier in chemical looping with Oxygen uncoupling clou solid fuel testing and sulphur interaction
Energy technology, 2013Co-Authors: Sebastian E Sundqvist, Henrik Leion, Anders Lyngfelt, Magnus Ryden, Tobias MattissonAbstract:Particles of the perovskite Material CaMn0.875Ti0.125O3-δ have been examined as Oxygen-Carrier Material for chemical-looping with Oxygen uncoupling (CLOU). The aim of the work has been to determine the effect of the fuel to bed mass ratio when oxidizing solid fuels, and to determine the influence of SO2 on the reactivity with fuel. Two solid fuels have been used, a Mexican petroleum coke and a Colombian coal. The Oxygen Carrier Material used in this study was CaMn0.875Ti0.125O3-δ and was developed and manufactured by the Norwegian research institute SINTEF. The experiments were conducted in a discontinuous quartz glass batch fluidized-bed reactor with an inner diameter of 10 mm. The particle bed rests on a porous plate and thermocouples 5 mm under and 10 above the plate was used for measuring the temperature. In the oxidation phase a flow of 1000 ml/min with 5% Oxygen in nitrogen was used. During the solid fuel experiments the bed was fluidized with 600 ml/min nitrogen while 0.1 g of solid fuel added to the reactor from the top. Two solid fuels were used; petroleum coke and Colombian coal. In the experiments with gaseous fuels the bed was fluidized with 900 ml/min consisting of 450 ml/min CH4 and 450ml/min with 0.25-0.5% SO2 in nitrogen. It was found that the Colombian coal was oxidized considerably faster than the petroleum coke, which is unexpected since it could be expected that the kinetics for O2 release from the Oxygen Carrier should determine conversion rate rather than the reactivity of the fuels. The overall rate of conversion increased for experiments with larger bed mass though, which was expected. SO2 seems to have had a negative effect on the reactivity of the Oxygen Carrier, likely because of formation of CaSO4.
P Gayan - One of the best experts on this subject based on the ideXlab platform.
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evaluation of different strategies to improve the efficiency of coal conversion in a 50 kwth chemical looping combustion unit
Fuel, 2020Co-Authors: A Abad, F Garcialabiano, P Gayan, L F De Diego, R Perezvega, T Mendiara, M Izquierdo, Juan AdánezAbstract:Abstract Minerals or industrial waste Materials are considered promising Oxygen Carriers for coal combustion through in-situ Gasification Chemical Looping Combustion (iG-CLC) process in order to maintain CO2 capture at low cost. Nevertheless, complete coal combustion to CO2 and H2O is usually not achieved and different solutions have been outlined to improve it. The aim of this work is to analyze the potential of two of these strategies: (1) using a more reactive Oxygen Carrier; and (2) to have two fuel reactors by feeding the coal into the carbon stripper. Coal combustion in a 50 kWth CLC unit was carried out using two Oxygen Carrier Materials, namely Norwegian ilmenite and Tierga iron-ore. Also, an additional test was carried out feeding the coal directly into the carbon stripper of the CLC unit, in contrast with the conventional coal feeding to the fuel reactor. CO2 capture efficiency was barely affected by the type of Oxygen Carrier Material, but slightly lower values were obtained when coal was fed to the carbon stripper. In contrast, coal combustion efficiency was enhanced by using the iron-ore Material, with a potential decrease of the total Oxygen demand of 40%, achieving a minimum value of total Oxygen demand of 4.1%. Also, the total Oxygen demand was decreased by 24% when coal was fed to the carbon stripper due to the improvement in the combustion of the volatiles in the fuel reactor. The combination of both strategies has high potential to maximize the coal combustion via iG-CLC process.
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fe2o3 al2o3 Oxygen Carrier Materials for chemical looping combustion a redox thermodynamic and thermogravimetric evaluation in the presence of h2s
Journal of Thermal Analysis and Calorimetry, 2018Co-Authors: Mehdi Pishahang, Juan Adánez, P Gayan, Yngve Larring, Martin F SundingAbstract:Alumina-supported Fe2O3 Oxygen Carrier Material (OCM) system is among the most promising OCM systems for solid and gaseous fuel CLC. This work utilizes a comprehensive thermogravimetric and thermodynamic equilibrium approach to redox and CLOU performance, Oxygen transfer capacity, reduction rate and sulfur tolerance of the Fe2O3 impregnated on Al2O3 OCM. Thermodynamic evaluations reveal that the beneficial composition range lies in a wide range of 7.5–34% molar Fe2O3 ratios. This is the range at which aluminum-rich corundum phase, i.e., (Al, Fe)2O3, remains stable throughout the oxidizing to very reducing Oxygen partial pressures in fuel reactor. The experimental system in this study contains 20 mass% Fe2O3, i.e., XFe = 13.8% molar which lies well within this interval. Deep redox cycle experiments confirm the thermodynamic modeling and during the long residence time of this experiment, the sample is almost fully reduced and exhibits its thermodynamic redox Oxygen capacity of close to 1.5 mass%. Extension of the deep redox cycles to 15 cycles induces no performance deterioration in terms of capacity, rate of reduction or morphological failure. The redox experiment under sour reducing gas indicates no H2S poisoning for the 20 mass% Fe2O3 supported on Al2O3 OCM. The findings that this system is not affected with the H2S content of the gas, and the prediction of the SO2 release from the fuel reactor is in good agreement with our recent reactor testing findings available in the literature.
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titanium substituted manganese ferrite as an Oxygen Carrier with permanent magnetic properties for chemical looping combustion of solid fuels
Fuel, 2017Co-Authors: Maria Abian, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Luis F De Diego, Juan AdánezAbstract:Abstract Mixed oxides of Mn-Fe have been identified as suitable Materials for Chemical Looping Combustion (CLC) with solid fuels both via in-situ Gasification Chemical Looping Combustion ( i G-CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) processes. These Materials show the property of react with gaseous fuels as well as release Oxygen under given conditions, while cheap metals are used. In addition, these Materials can show magnetic properties that can be used for an easy separation from ash in CLC with solid fuels. Thus, losses of Oxygen Carrier Material in the ash drain stream would be reduced. Different cations have been proposed for improving the magnetic properties of manganese ferrites, including Ti 4+ . In this context, the present work accomplishes a screening of (Mn x Fe 1−x ) 2 O 3 doped with 7 wt.% TiO 2 , with x ranging from 0 to 1. The influence of Mn:Fe ratio on their physical and chemical properties was evaluated. In general, particles with high crushing strength values (>4 N) were obtained, and magnetic characteristics were highlighted when x ⩽ 0.66. The Oxygen uncoupling capability depended on the Mn:Fe ratio and the oxidation conditions, i.e. temperature and Oxygen partial pressure. Broader oxidation conditions to take advantage of the Oxygen uncoupling capability were found for Materials with low Mn content. On contrary, the reactivity with fuel gases (CH 4 , H 2 and CO) increased with the Mn content. Thus, Oxygen Carriers with Mn/(Mn + Fe) molar ratio in the 0.5–0.9 interval showed interesting properties at suitable temperatures for the i G-CLC and CLOU processes (i.e. 850–980 °C). The Material with Mn/(Mn + Fe) = 0.55 was preferred considering a trade-off between reactivity and magnetic properties.
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long lasting cu based Oxygen Carrier Material for industrial scale in chemical looping combustion
International Journal of Greenhouse Gas Control, 2016Co-Authors: Arturo Cabello, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, L F De Diego, Andrew Scullard, Gareth Williams, Juan AdánezAbstract:Abstract One of the most important current objectives of the Chemical Looping Combustion (CLC) technology for gaseous fuels lies in scaling-up the aforementioned technology in the short term from 100 kW th to 10 MW th scale. In order to meet this challenge, the commercial availability of suitable multi ton-scale Oxygen Carrier Materials at competitive price is needed. In this work, a Cu-based Oxygen Carrier prepared by the impregnation method using a commercial alumina as support, referred as Cu14γAl_Commercial, has been developed and evaluated in a 500 W th CLC pilot plant during the combustion of CH 4 at two different temperatures, i.e., 800 °C and 900 °C. The outstanding results obtained in terms of both combustion efficiency and mechanical stability have shown that the Cu14γAl_Commercial impregnated Oxygen Carrier can be selected to upscale CLC technology for gaseous fuels.
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redox kinetics of camg0 1ti0 125mn0 775o2 9 δ for chemical looping combustion clc and chemical looping with Oxygen uncoupling clou
Chemical Engineering Journal, 2015Co-Authors: A Abad, P Gayan, F Garcialabiano, L F De Diego, Juan AdánezAbstract:Abstract The objective of this study was to establish the kinetic of reactions involved in redox cycles of an Oxygen Carrier Material based on a perovskite type structure with the formula CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ . The Oxygen transport capacity and reactivity of this Material during reduction with gaseous fuels (CH 4 , H 2 and CO) and the subsequent oxidation with Oxygen are studied in a TGA apparatus. Besides, the Oxygen uncoupling properties of this Material are analysed. Thus, kinetics for relevant reactions involved in Chemical Looping Combustion (CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) were determined. CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ reactivity increased with the number of redox cycles, whereas the total Oxygen transport capacity decreased from 8.5 to 8.0 wt.%. Particles that reached the maximum reactivity were denoted as “activated” Material. Kinetics for both fresh and “activated” particles was determined. Conversion vs. time curves at different temperatures (973–1273 K), and reacting gas concentration (5–60 vol.% for CH 4 , H 2 or CO; 5–21 vol.% for O 2 ) were obtained for both fresh and “activated” Material. For kinetics determination, the shrinking core model with control by chemical reaction and diffusion through the product layer was used to obtain the kinetic parameters.
Georg L Schwebel - One of the best experts on this subject based on the ideXlab platform.
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apparent kinetics derived from fluidized bed experiments for norwegian ilmenite as Oxygen Carrier
Journal of environmental chemical engineering, 2014Co-Authors: Georg L Schwebel, Sebastian E Sundqvist, Wolfgang Krumm, Henrik LeionAbstract:Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the Oxygen Carrier Material will be lowered preferring low cost and environmental sound Materials. In this work apparent kinetics for the reduction of a natural rock ilmenite from Norway are derived from experimental data while utilizing CO, H2 and CH4 as fuel gases. CO, H2 and CH4 are the main combustible gases in solid fuel CLC. The experiments were carried out in a laboratory batch fluidized bed reactor. The reactor was heated to bed temperatures varying from 850 to 950 °C. Different fuel gas concentrations were achieved by diluting the fuel flow with nitrogen. For H2, pulsed reduction experiments have been accomplished to allow the calculation of conversion dependent rates. The experimental conversion rates were fitted to different model approaches in order to derive the apparent kinetic parameters. Thereby the Oxygen Carrier conversion was represented by the mass based conversion ω. The results are compared to published data. The reaction order with respect to the gas phase is close to the reported values. Only the reaction order obtained for CH 4 with the fitted power law deviated with about 40%, what could indicate a limitation of available surface for the heterogeneous decomposition of CH4. Although the overall agreement between fitted power laws and experimental data was appropriate, their extrapolation outside the experimental data range has to be done with care. © 2014 Elsevier Ltd.
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apparent kinetics derived from fluidized bed experiments for norwegian ilmenite as Oxygen Carrier
Journal of environmental chemical engineering, 2014Co-Authors: Georg L Schwebel, Sebastian E Sundqvist, Wolfgang Krumm, Henrik LeionAbstract:Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the Oxygen Carrier Material will be lowered preferring low cost and environmental sound Materials. In this work apparent kinetics for the reduction of a natural rock ilmenite from Norway are derived from experimental data while utilizing CO, H2 and CH4 as fuel gases. CO, H2 and CH4 are the main combustible gases in solid fuel CLC. The experiments were carried out in a laboratory batch fluidized bed reactor. The reactor was heated to bed temperatures varying from 850 to 950 °C. Different fuel gas concentrations were achieved by diluting the fuel flow with nitrogen. For H2, pulsed reduction experiments have been accomplished to allow the calculation of conversion dependent rates. The experimental conversion rates were fitted to different model approaches in order to derive the apparent kinetic parameters. Thereby the Oxygen Carrier conversion was represented by the mass based conversion ω. The results are compared to published data. The reaction order with respect to the gas phase is close to the reported values. Only the reaction order obtained for CH 4 with the fitted power law deviated with about 40%, what could indicate a limitation of available surface for the heterogeneous decomposition of CH4. Although the overall agreement between fitted power laws and experimental data was appropriate, their extrapolation outside the experimental data range has to be done with care. © 2014 Elsevier Ltd.
F Garcialabiano - One of the best experts on this subject based on the ideXlab platform.
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evaluation of different strategies to improve the efficiency of coal conversion in a 50 kwth chemical looping combustion unit
Fuel, 2020Co-Authors: A Abad, F Garcialabiano, P Gayan, L F De Diego, R Perezvega, T Mendiara, M Izquierdo, Juan AdánezAbstract:Abstract Minerals or industrial waste Materials are considered promising Oxygen Carriers for coal combustion through in-situ Gasification Chemical Looping Combustion (iG-CLC) process in order to maintain CO2 capture at low cost. Nevertheless, complete coal combustion to CO2 and H2O is usually not achieved and different solutions have been outlined to improve it. The aim of this work is to analyze the potential of two of these strategies: (1) using a more reactive Oxygen Carrier; and (2) to have two fuel reactors by feeding the coal into the carbon stripper. Coal combustion in a 50 kWth CLC unit was carried out using two Oxygen Carrier Materials, namely Norwegian ilmenite and Tierga iron-ore. Also, an additional test was carried out feeding the coal directly into the carbon stripper of the CLC unit, in contrast with the conventional coal feeding to the fuel reactor. CO2 capture efficiency was barely affected by the type of Oxygen Carrier Material, but slightly lower values were obtained when coal was fed to the carbon stripper. In contrast, coal combustion efficiency was enhanced by using the iron-ore Material, with a potential decrease of the total Oxygen demand of 40%, achieving a minimum value of total Oxygen demand of 4.1%. Also, the total Oxygen demand was decreased by 24% when coal was fed to the carbon stripper due to the improvement in the combustion of the volatiles in the fuel reactor. The combination of both strategies has high potential to maximize the coal combustion via iG-CLC process.
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titanium substituted manganese ferrite as an Oxygen Carrier with permanent magnetic properties for chemical looping combustion of solid fuels
Fuel, 2017Co-Authors: Maria Abian, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Luis F De Diego, Juan AdánezAbstract:Abstract Mixed oxides of Mn-Fe have been identified as suitable Materials for Chemical Looping Combustion (CLC) with solid fuels both via in-situ Gasification Chemical Looping Combustion ( i G-CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) processes. These Materials show the property of react with gaseous fuels as well as release Oxygen under given conditions, while cheap metals are used. In addition, these Materials can show magnetic properties that can be used for an easy separation from ash in CLC with solid fuels. Thus, losses of Oxygen Carrier Material in the ash drain stream would be reduced. Different cations have been proposed for improving the magnetic properties of manganese ferrites, including Ti 4+ . In this context, the present work accomplishes a screening of (Mn x Fe 1−x ) 2 O 3 doped with 7 wt.% TiO 2 , with x ranging from 0 to 1. The influence of Mn:Fe ratio on their physical and chemical properties was evaluated. In general, particles with high crushing strength values (>4 N) were obtained, and magnetic characteristics were highlighted when x ⩽ 0.66. The Oxygen uncoupling capability depended on the Mn:Fe ratio and the oxidation conditions, i.e. temperature and Oxygen partial pressure. Broader oxidation conditions to take advantage of the Oxygen uncoupling capability were found for Materials with low Mn content. On contrary, the reactivity with fuel gases (CH 4 , H 2 and CO) increased with the Mn content. Thus, Oxygen Carriers with Mn/(Mn + Fe) molar ratio in the 0.5–0.9 interval showed interesting properties at suitable temperatures for the i G-CLC and CLOU processes (i.e. 850–980 °C). The Material with Mn/(Mn + Fe) = 0.55 was preferred considering a trade-off between reactivity and magnetic properties.
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long lasting cu based Oxygen Carrier Material for industrial scale in chemical looping combustion
International Journal of Greenhouse Gas Control, 2016Co-Authors: Arturo Cabello, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, L F De Diego, Andrew Scullard, Gareth Williams, Juan AdánezAbstract:Abstract One of the most important current objectives of the Chemical Looping Combustion (CLC) technology for gaseous fuels lies in scaling-up the aforementioned technology in the short term from 100 kW th to 10 MW th scale. In order to meet this challenge, the commercial availability of suitable multi ton-scale Oxygen Carrier Materials at competitive price is needed. In this work, a Cu-based Oxygen Carrier prepared by the impregnation method using a commercial alumina as support, referred as Cu14γAl_Commercial, has been developed and evaluated in a 500 W th CLC pilot plant during the combustion of CH 4 at two different temperatures, i.e., 800 °C and 900 °C. The outstanding results obtained in terms of both combustion efficiency and mechanical stability have shown that the Cu14γAl_Commercial impregnated Oxygen Carrier can be selected to upscale CLC technology for gaseous fuels.
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redox kinetics of camg0 1ti0 125mn0 775o2 9 δ for chemical looping combustion clc and chemical looping with Oxygen uncoupling clou
Chemical Engineering Journal, 2015Co-Authors: A Abad, P Gayan, F Garcialabiano, L F De Diego, Juan AdánezAbstract:Abstract The objective of this study was to establish the kinetic of reactions involved in redox cycles of an Oxygen Carrier Material based on a perovskite type structure with the formula CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ . The Oxygen transport capacity and reactivity of this Material during reduction with gaseous fuels (CH 4 , H 2 and CO) and the subsequent oxidation with Oxygen are studied in a TGA apparatus. Besides, the Oxygen uncoupling properties of this Material are analysed. Thus, kinetics for relevant reactions involved in Chemical Looping Combustion (CLC) and Chemical Looping with Oxygen Uncoupling (CLOU) were determined. CaMg 0.1 Ti 0.125 Mn 0.775 O 2.9− δ reactivity increased with the number of redox cycles, whereas the total Oxygen transport capacity decreased from 8.5 to 8.0 wt.%. Particles that reached the maximum reactivity were denoted as “activated” Material. Kinetics for both fresh and “activated” particles was determined. Conversion vs. time curves at different temperatures (973–1273 K), and reacting gas concentration (5–60 vol.% for CH 4 , H 2 or CO; 5–21 vol.% for O 2 ) were obtained for both fresh and “activated” Material. For kinetics determination, the shrinking core model with control by chemical reaction and diffusion through the product layer was used to obtain the kinetic parameters.
