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Juan Adánez - One of the best experts on this subject based on the ideXlab platform.
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chemical looping combustion of gaseous and solid fuels with manganese iron mixed oxide as Oxygen Carrier
Energy Conversion and Management, 2018Co-Authors: Raul Perezvega, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Synthetic manganese-iron mixed oxides are considered promising materials to be used as Oxygen Carriers for Chemical Looping Combustion of coal with carbon dioxide capture at low cost. The aim of this work was to evaluate a manganese-iron mixed oxide material with a manganese to iron molar ratio of 0.77:0.23 as Oxygen Carrier for coal combustion by means of chemical looping processes, including both ex-situ and in-situ gasification of coal. The preparation method -spray drying followed by calcination- was optimized in order to produce particles with high reactivity and mechanical strength. The material was studied in two continuously operated facilities designed to burn either gaseous or solid fuels. While full combustion was achieved burning syngas, showing the feasibility of the use of this material considering the ex-situ gasification process. Coal combustion efficiency by in-situ gasification process was improved in comparison with other previously tested low-cost materials such as ilmenite and iron ore. Moreover, the Oxygen Carrier particles showed an interesting magnetic behavior that was able to facilitate Oxygen Carrier recovery from the purge ash stream. In view of these results, the manganese-iron mixed oxide as Oxygen Carrier is proposed as a promising candidate for use coal combustion by the chemical looping process.
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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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biomass combustion in a clc system using an iron ore as an Oxygen Carrier
International Journal of Greenhouse Gas Control, 2013Co-Authors: T Mendiara, Alberto Abad, F Garcialabiano, P Gayan, L F De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a promising CO2 capture technology with a very low energy penalty and cost. Several previous studies have demonstrated the feasibility of this technology using both gaseous and solid fuels. The combustion of biomass using CLC would make the concept of negative-CO2 emission possible. This paper presents a study of biomass combustion in a continuous CLC unit using pine wood as fuel and iron ore as an Oxygen Carrier and analyses several parameters influencing the CLC process. High carbon captures (>95%) were achieved in the interval 880–915 °C using both steam and CO2 as gasifying agents. Tar compounds were detected at the fuel reactor outlet. After 78 h of continuous operation, no changes were detected in the physical and chemical properties of the Oxygen Carrier particles.
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identification of operational regions in the chemical looping with Oxygen uncoupling clou process with a cu based Oxygen Carrier
Fuel, 2012Co-Authors: Inaki Adanezrubio, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, Juan AdánezAbstract:Abstract Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative chemical-looping process for the combustion of solid fuels with inherent CO 2 capture. The CLOU process demands a material as Oxygen Carrier with the ability to decompose with O 2 release at suitable temperatures for solid fuel combustion, e.g. copper oxide. This article presents an experimental method to determine the maximum Oxygen generation rate of an Oxygen Carrier as well as to determine the minimum solid inventory that must be used in the fuel reactor. The method here proposed can be used as basis for comparison of the use of different Oxygen Carriers or type of coals. In this work, the combustion of coal by using a promising Cu-based Oxygen Carrier prepared by the spray drying method was tested. The Oxygen Carrier (Cu60MgAl) was composed of 60 wt.% CuO and MgAl 2 O 4 was used as supporting material. Experiments were carried out in a batch fluidized-bed reactor at temperatures ranging from 900 to 980 °C. Three different regions were identified depending on the Oxygen Carrier to coal mass ratio. For Oxygen Carrier to coal ratios higher than 50 (Region I), coal was fully converted to CO 2 and H 2 O. In addition, an excess of Oxygen was present in the flue gases, which was close to the equilibrium concentration. When this ratio was in the range 50–25 (Region II), the concentration of Oxygen was decreasing whereas some CO was observed as the only unconverted gas. Further decrease in the Oxygen Carrier to coal ratio below 25 (Region III) caused the depletion of Oxygen in the exhaust gases but CO remained as the only unconverted gas. CH 4 or H 2 were never detected at the reactor outlet in any case and agglomeration problems were never observed. These regions were related to the solids inventory in the fuel reactor by the rate of Oxygen generation calculated in every case. A maximum rate of Oxygen generation for the Oxygen Carrier was determined as kg O 2 /s per kg of Oxygen Carrier, which increased with the temperature from 2.1 × 10 −3 at 930 °C to 2.8 × 10 −3 at 980 °C. From these values, the estimated solids inventory in the fuel reactor was changed from 39 at 930 °C to 29 kg/MW th at 980 °C. The results obtained in this work showed that in the CLOU process it is possible to reach full conversion of the solid fuel with very low solids inventory and avoiding the Oxygen polishing step.
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effect of h2s on the behaviour of an impregnated nio based Oxygen Carrier for chemical looping combustion clc
Applied Catalysis B-environmental, 2012Co-Authors: Cristina Dueso, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Gaseous fuels for chemical-looping combustion (CLC) process may contain sulphur-compounds which could affect the Oxygen-Carrier behaviour, especially if NiO is used as active phase. In this work, several samples of a NiO-based Oxygen-Carrier prepared by impregnation (18 wt.%) on α-Al 2 O 3 , so-called NiO18-αAl, were extracted from a CLC unit after continuous operation with CH 4 containing 500 vppm of H 2 S and characterized subsequently. Part of the sulphur fed to the system was release as SO 2 in the air-reactor during the CLC experiments while the rest remained in the solid particles. Ni 3 S 2 was found in the Oxygen-Carrier extracted from the fuel-reactor, although small amounts of NiSO 4 were also detected. On the contrary, NiSO 4 was the main sulphur compound in the Oxygen-Carrier from the air-reactor while a low concentration of Ni 3 S 2 was present. Despite the accumulated sulphur and the Oxygen transport capacity loss during the operation, the Oxygen-Carrier was capable of recovering the initial reactivity for the CH 4 combustion after some time without H 2 S feeding to the CLC system. In addition, a study about the possible regeneration of the Oxygen-Carrier in the air-reactor working at different temperatures and Oxygen concentrations was performed. Independently of the operating conditions, part of the sulphur remained in the solid and total regeneration was not possible. The analysis of the NiO18-αAl Oxygen-Carrier after the CLC operation using TPR and XPS techniques revealed that sulphur reacted preferably with free NiO instead of NiAl 2 O 4 . Although Ni 3 S 2 was the majority sulphide in the fuel-reactor, minor amounts of other sulphides such as NiS were detected. Sulphur was preferably concentrated in the outer surface of the particles. Taking into account all these results, a previous desulphuration process of the fuel would be necessary when NiO-based Oxygen-Carriers are used in a CLC system.
Alberto Abad - One of the best experts on this subject based on the ideXlab platform.
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chemical looping combustion of gaseous and solid fuels with manganese iron mixed oxide as Oxygen Carrier
Energy Conversion and Management, 2018Co-Authors: Raul Perezvega, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Synthetic manganese-iron mixed oxides are considered promising materials to be used as Oxygen Carriers for Chemical Looping Combustion of coal with carbon dioxide capture at low cost. The aim of this work was to evaluate a manganese-iron mixed oxide material with a manganese to iron molar ratio of 0.77:0.23 as Oxygen Carrier for coal combustion by means of chemical looping processes, including both ex-situ and in-situ gasification of coal. The preparation method -spray drying followed by calcination- was optimized in order to produce particles with high reactivity and mechanical strength. The material was studied in two continuously operated facilities designed to burn either gaseous or solid fuels. While full combustion was achieved burning syngas, showing the feasibility of the use of this material considering the ex-situ gasification process. Coal combustion efficiency by in-situ gasification process was improved in comparison with other previously tested low-cost materials such as ilmenite and iron ore. Moreover, the Oxygen Carrier particles showed an interesting magnetic behavior that was able to facilitate Oxygen Carrier recovery from the purge ash stream. In view of these results, the manganese-iron mixed oxide as Oxygen Carrier is proposed as a promising candidate for use coal combustion by the chemical looping process.
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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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biomass combustion in a clc system using an iron ore as an Oxygen Carrier
International Journal of Greenhouse Gas Control, 2013Co-Authors: T Mendiara, Alberto Abad, F Garcialabiano, P Gayan, L F De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a promising CO2 capture technology with a very low energy penalty and cost. Several previous studies have demonstrated the feasibility of this technology using both gaseous and solid fuels. The combustion of biomass using CLC would make the concept of negative-CO2 emission possible. This paper presents a study of biomass combustion in a continuous CLC unit using pine wood as fuel and iron ore as an Oxygen Carrier and analyses several parameters influencing the CLC process. High carbon captures (>95%) were achieved in the interval 880–915 °C using both steam and CO2 as gasifying agents. Tar compounds were detected at the fuel reactor outlet. After 78 h of continuous operation, no changes were detected in the physical and chemical properties of the Oxygen Carrier particles.
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identification of operational regions in the chemical looping with Oxygen uncoupling clou process with a cu based Oxygen Carrier
Fuel, 2012Co-Authors: Inaki Adanezrubio, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, Juan AdánezAbstract:Abstract Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative chemical-looping process for the combustion of solid fuels with inherent CO 2 capture. The CLOU process demands a material as Oxygen Carrier with the ability to decompose with O 2 release at suitable temperatures for solid fuel combustion, e.g. copper oxide. This article presents an experimental method to determine the maximum Oxygen generation rate of an Oxygen Carrier as well as to determine the minimum solid inventory that must be used in the fuel reactor. The method here proposed can be used as basis for comparison of the use of different Oxygen Carriers or type of coals. In this work, the combustion of coal by using a promising Cu-based Oxygen Carrier prepared by the spray drying method was tested. The Oxygen Carrier (Cu60MgAl) was composed of 60 wt.% CuO and MgAl 2 O 4 was used as supporting material. Experiments were carried out in a batch fluidized-bed reactor at temperatures ranging from 900 to 980 °C. Three different regions were identified depending on the Oxygen Carrier to coal mass ratio. For Oxygen Carrier to coal ratios higher than 50 (Region I), coal was fully converted to CO 2 and H 2 O. In addition, an excess of Oxygen was present in the flue gases, which was close to the equilibrium concentration. When this ratio was in the range 50–25 (Region II), the concentration of Oxygen was decreasing whereas some CO was observed as the only unconverted gas. Further decrease in the Oxygen Carrier to coal ratio below 25 (Region III) caused the depletion of Oxygen in the exhaust gases but CO remained as the only unconverted gas. CH 4 or H 2 were never detected at the reactor outlet in any case and agglomeration problems were never observed. These regions were related to the solids inventory in the fuel reactor by the rate of Oxygen generation calculated in every case. A maximum rate of Oxygen generation for the Oxygen Carrier was determined as kg O 2 /s per kg of Oxygen Carrier, which increased with the temperature from 2.1 × 10 −3 at 930 °C to 2.8 × 10 −3 at 980 °C. From these values, the estimated solids inventory in the fuel reactor was changed from 39 at 930 °C to 29 kg/MW th at 980 °C. The results obtained in this work showed that in the CLOU process it is possible to reach full conversion of the solid fuel with very low solids inventory and avoiding the Oxygen polishing step.
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effect of h2s on the behaviour of an impregnated nio based Oxygen Carrier for chemical looping combustion clc
Applied Catalysis B-environmental, 2012Co-Authors: Cristina Dueso, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Gaseous fuels for chemical-looping combustion (CLC) process may contain sulphur-compounds which could affect the Oxygen-Carrier behaviour, especially if NiO is used as active phase. In this work, several samples of a NiO-based Oxygen-Carrier prepared by impregnation (18 wt.%) on α-Al 2 O 3 , so-called NiO18-αAl, were extracted from a CLC unit after continuous operation with CH 4 containing 500 vppm of H 2 S and characterized subsequently. Part of the sulphur fed to the system was release as SO 2 in the air-reactor during the CLC experiments while the rest remained in the solid particles. Ni 3 S 2 was found in the Oxygen-Carrier extracted from the fuel-reactor, although small amounts of NiSO 4 were also detected. On the contrary, NiSO 4 was the main sulphur compound in the Oxygen-Carrier from the air-reactor while a low concentration of Ni 3 S 2 was present. Despite the accumulated sulphur and the Oxygen transport capacity loss during the operation, the Oxygen-Carrier was capable of recovering the initial reactivity for the CH 4 combustion after some time without H 2 S feeding to the CLC system. In addition, a study about the possible regeneration of the Oxygen-Carrier in the air-reactor working at different temperatures and Oxygen concentrations was performed. Independently of the operating conditions, part of the sulphur remained in the solid and total regeneration was not possible. The analysis of the NiO18-αAl Oxygen-Carrier after the CLC operation using TPR and XPS techniques revealed that sulphur reacted preferably with free NiO instead of NiAl 2 O 4 . Although Ni 3 S 2 was the majority sulphide in the fuel-reactor, minor amounts of other sulphides such as NiS were detected. Sulphur was preferably concentrated in the outer surface of the particles. Taking into account all these results, a previous desulphuration process of the fuel would be necessary when NiO-based Oxygen-Carriers are used in a CLC system.
P Gayan - One of the best experts on this subject based on the ideXlab platform.
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chemical looping combustion of gaseous and solid fuels with manganese iron mixed oxide as Oxygen Carrier
Energy Conversion and Management, 2018Co-Authors: Raul Perezvega, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Synthetic manganese-iron mixed oxides are considered promising materials to be used as Oxygen Carriers for Chemical Looping Combustion of coal with carbon dioxide capture at low cost. The aim of this work was to evaluate a manganese-iron mixed oxide material with a manganese to iron molar ratio of 0.77:0.23 as Oxygen Carrier for coal combustion by means of chemical looping processes, including both ex-situ and in-situ gasification of coal. The preparation method -spray drying followed by calcination- was optimized in order to produce particles with high reactivity and mechanical strength. The material was studied in two continuously operated facilities designed to burn either gaseous or solid fuels. While full combustion was achieved burning syngas, showing the feasibility of the use of this material considering the ex-situ gasification process. Coal combustion efficiency by in-situ gasification process was improved in comparison with other previously tested low-cost materials such as ilmenite and iron ore. Moreover, the Oxygen Carrier particles showed an interesting magnetic behavior that was able to facilitate Oxygen Carrier recovery from the purge ash stream. In view of these results, the manganese-iron mixed oxide as Oxygen Carrier is proposed as a promising candidate for use coal combustion by the chemical looping process.
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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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biomass combustion in a clc system using an iron ore as an Oxygen Carrier
International Journal of Greenhouse Gas Control, 2013Co-Authors: T Mendiara, Alberto Abad, F Garcialabiano, P Gayan, L F De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a promising CO2 capture technology with a very low energy penalty and cost. Several previous studies have demonstrated the feasibility of this technology using both gaseous and solid fuels. The combustion of biomass using CLC would make the concept of negative-CO2 emission possible. This paper presents a study of biomass combustion in a continuous CLC unit using pine wood as fuel and iron ore as an Oxygen Carrier and analyses several parameters influencing the CLC process. High carbon captures (>95%) were achieved in the interval 880–915 °C using both steam and CO2 as gasifying agents. Tar compounds were detected at the fuel reactor outlet. After 78 h of continuous operation, no changes were detected in the physical and chemical properties of the Oxygen Carrier particles.
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identification of operational regions in the chemical looping with Oxygen uncoupling clou process with a cu based Oxygen Carrier
Fuel, 2012Co-Authors: Inaki Adanezrubio, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, Juan AdánezAbstract:Abstract Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative chemical-looping process for the combustion of solid fuels with inherent CO 2 capture. The CLOU process demands a material as Oxygen Carrier with the ability to decompose with O 2 release at suitable temperatures for solid fuel combustion, e.g. copper oxide. This article presents an experimental method to determine the maximum Oxygen generation rate of an Oxygen Carrier as well as to determine the minimum solid inventory that must be used in the fuel reactor. The method here proposed can be used as basis for comparison of the use of different Oxygen Carriers or type of coals. In this work, the combustion of coal by using a promising Cu-based Oxygen Carrier prepared by the spray drying method was tested. The Oxygen Carrier (Cu60MgAl) was composed of 60 wt.% CuO and MgAl 2 O 4 was used as supporting material. Experiments were carried out in a batch fluidized-bed reactor at temperatures ranging from 900 to 980 °C. Three different regions were identified depending on the Oxygen Carrier to coal mass ratio. For Oxygen Carrier to coal ratios higher than 50 (Region I), coal was fully converted to CO 2 and H 2 O. In addition, an excess of Oxygen was present in the flue gases, which was close to the equilibrium concentration. When this ratio was in the range 50–25 (Region II), the concentration of Oxygen was decreasing whereas some CO was observed as the only unconverted gas. Further decrease in the Oxygen Carrier to coal ratio below 25 (Region III) caused the depletion of Oxygen in the exhaust gases but CO remained as the only unconverted gas. CH 4 or H 2 were never detected at the reactor outlet in any case and agglomeration problems were never observed. These regions were related to the solids inventory in the fuel reactor by the rate of Oxygen generation calculated in every case. A maximum rate of Oxygen generation for the Oxygen Carrier was determined as kg O 2 /s per kg of Oxygen Carrier, which increased with the temperature from 2.1 × 10 −3 at 930 °C to 2.8 × 10 −3 at 980 °C. From these values, the estimated solids inventory in the fuel reactor was changed from 39 at 930 °C to 29 kg/MW th at 980 °C. The results obtained in this work showed that in the CLOU process it is possible to reach full conversion of the solid fuel with very low solids inventory and avoiding the Oxygen polishing step.
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effect of h2s on the behaviour of an impregnated nio based Oxygen Carrier for chemical looping combustion clc
Applied Catalysis B-environmental, 2012Co-Authors: Cristina Dueso, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Gaseous fuels for chemical-looping combustion (CLC) process may contain sulphur-compounds which could affect the Oxygen-Carrier behaviour, especially if NiO is used as active phase. In this work, several samples of a NiO-based Oxygen-Carrier prepared by impregnation (18 wt.%) on α-Al 2 O 3 , so-called NiO18-αAl, were extracted from a CLC unit after continuous operation with CH 4 containing 500 vppm of H 2 S and characterized subsequently. Part of the sulphur fed to the system was release as SO 2 in the air-reactor during the CLC experiments while the rest remained in the solid particles. Ni 3 S 2 was found in the Oxygen-Carrier extracted from the fuel-reactor, although small amounts of NiSO 4 were also detected. On the contrary, NiSO 4 was the main sulphur compound in the Oxygen-Carrier from the air-reactor while a low concentration of Ni 3 S 2 was present. Despite the accumulated sulphur and the Oxygen transport capacity loss during the operation, the Oxygen-Carrier was capable of recovering the initial reactivity for the CH 4 combustion after some time without H 2 S feeding to the CLC system. In addition, a study about the possible regeneration of the Oxygen-Carrier in the air-reactor working at different temperatures and Oxygen concentrations was performed. Independently of the operating conditions, part of the sulphur remained in the solid and total regeneration was not possible. The analysis of the NiO18-αAl Oxygen-Carrier after the CLC operation using TPR and XPS techniques revealed that sulphur reacted preferably with free NiO instead of NiAl 2 O 4 . Although Ni 3 S 2 was the majority sulphide in the fuel-reactor, minor amounts of other sulphides such as NiS were detected. Sulphur was preferably concentrated in the outer surface of the particles. Taking into account all these results, a previous desulphuration process of the fuel would be necessary when NiO-based Oxygen-Carriers are used in a CLC system.
Jun Xiao - One of the best experts on this subject based on the ideXlab platform.
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Performance of Hematite/Ca2Al2SiO7 Oxygen Carrier in Chemical Looping Combustion of Coal
Industrial & Engineering Chemistry Research, 2013Co-Authors: Tao Song, Laihong Shen, Siwen Zhang, Dingqian Chen, Jun XiaoAbstract:In this work, a novel Ca-enhanced hematite Oxygen Carrier was developed for chemical looping combustion of coal. Calcium aluminate cement was used to bind hematite particles to enhance its mechanic...
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Evaluation of hematite Oxygen Carrier in chemical-looping combustion of coal
Fuel, 2013Co-Authors: Tao Song, Laihong Shen, Shen Tianxu, Jun Xiao, Siwen ZhangAbstract:Abstract Chemical-looping combustion (CLC) using a ShenHua bituminous coal and an HuaiBei anthracite as fuel was investigated in 1 kW th interconnected fluidized beds under continuous operation. The evaluation of hematite Oxygen Carrier in coal CLC was performed. Meanwhile, the fate of fuel-N in the CLC process was investigated. According to a 20 h continuous operation with the natural hematite at a fuel reactor temperature of 970 °C, results showed that the CO 2 capture efficiency for ShenHua bituminous coal was 82%, whereas the one for HuaiBei anthracite was 65% due to a low gasification rate for the anthracite. With the fuel reactor temperature range of 880–970 °C, there were neither hydrocarbons heavier than CH 4 nor tars in the exit of the fuel reactor. For both of the two coals used, the CO 2 fraction in the flue carbonaceous gas of the fuel reactor reached 92% at a fuel reactor temperature of 970 °C, indicating a high reactivity of the hematite as an Oxygen Carrier. Under the continuous operation, the inert material of SiO 2 in the hematite was difficult to react with the active phases of Fe 2 O 3 or Fe 3 O 4 , resulting in the alleviated sintering degree of the Oxygen Carrier. The mass loss rate of the hematite was about 0.12 wt.%/h. There was no nitrogen oxides evolution in the exit gas of the fuel reactor with the fuel reactor temperature range of 880 °C–970 °C. N 2 was the sole product of the nitrogen transfer of fuel-N in the fuel reactor. A high fuel reactor temperature produced more fuel-N to N 2 . Along with residual char circulating to the air reactor, there was some nitrogen oxides formation in the air reactor. The NO concentration was mostly influenced by the amount of char coming into the air reactor, which was less at a high fuel reactor temperature. Enough residence time for the fuel in the fuel reactor should be ensured with respect to eliminate NO formation in the air reactor, and a carbon stripper is better to be employed and developed in the future design and operation of CLC plant.
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Experimental investigation of hematite Oxygen Carrier decorated with NiO for chemical looping combustion of coal
Journal of Fuel Chemistry and Technology, 2012Co-Authors: Dingqian Chen, Laihong Shen, Jun Xiao, Tao Song, Siwen ZhangAbstract:Abstract Experiments on chemical-looping combustion of coal were conducted in a 1 kW th interconnected fluidized-bed reactor using a natural hematite as an Oxygen Carrier and Shenhua bituminous coal and Huaibei anthracite as fuel. An evaluation of a hematite Oxygen Carrier decorated with NiO by mechanical mixing and impregnation methods was also performed. The results indicate that coal gasification rate is a time-limiting step that is employed in the chemical-looping combustion of coal, and the coal type has a great impact on the CO 2 capture efficiency. When the fuel reactor temperature is 970°C and using hematite as an Oxygen Carrier, the CO 2 capture efficiency for Shenhua bituminous coal is 81.7%, whereas the one for Huaibei anthracite is 65%. Hematite shows stable reactivity during a process of long-term operation, and it should be a good candidate as an Oxygen Carrier for the chemical-looping combustion of coal. It is an effective way of improving the reactivity of the hematite Oxygen Carrier as well as the CO 2 capture efficiency by mechanical mixing with the NiO/Al 2 O 3 Oxygen Carrier. Impregnating NiO on hematite exhibits a negative effect of the reaction performance between the product of coal gasification and the Oxygen Carrier due to the poor microstructure after calcination. Further investigations on the method and process of impregnation should be conducted.
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Sulfur behavior in chemical looping combustion with NiO/Al2O3 Oxygen Carrier
Combustion and Flame, 2010Co-Authors: Laihong Shen, Zhengping Gao, Jun XiaoAbstract:Abstract Chemical looping combustion (CLC) is a novel technology where CO2 is inherently separated during combustion. Due to the existence of sulfur contaminants in the fossil fuels, the gaseous products of sulfur species and the interaction of sulfur contaminants with Oxygen Carrier are a big concern in the CLC practice. The reactivity of NiO/Al2O3 Oxygen Carrier reduction with a gas mixture of CO/H2 and H2S is investigated by means of a thermogravimetric analyzer (TGA) and Fourier Transform Infrared spectrum analyzer in this study. An X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to evaluate the phase characterization of reacted Oxygen Carrier, and the formation mechanisms of the gaseous products of sulfur species are elucidated in the process of chemical looping combustion with a gaseous fuel containing hydrogen sulfide. The results show that the rate of NiO reduction with H2S is higher than the one with CO. There are only Ni and Ni3S2 phases of nickel species in the fully reduced Oxygen Carrier, and no evidence for the existence of NiS or NiS2. The formation of Ni3S2 is completely reversible during the process of Oxygen Carrier redox. A liquid phase sintering on the external surface of reduced Oxygen Carriers is mainly attributed to the production of the low melting of Ni3S2 in the nickel-based Oxygen Carrier reduction with a gaseous fuel containing H2S. Due to the sintering of metallic nickel grains on the external surface of the reduced Oxygen Carrier, further reaction of the Oxygen Carrier with H2S is constrained, and there is no increase of the sulfidation index of the reduced Oxygen Carrier with the cyclical reduction number. Also, a continuous operation with a syngas of carbon monoxide and hydrogen containing H2S is carried out in a 1 kWth CLC prototype based on the nickel-based Oxygen Carrier, and the effect of the fuel reactor temperature on the release of gaseous products of sulfur species is investigated.
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reactivity deterioration of nio al2o3 Oxygen Carrier for chemical looping combustion of coal in a 10 kwth reactor
Combustion and Flame, 2009Co-Authors: Laihong Shen, Jiahua Wu, Jun XiaoAbstract:Abstract A relatively long-term experiment for chemical looping combustion of coal with NiO/Al2O3 Oxygen Carrier was carried out in a 10 kWth continuous reactor of interconnected fluidized beds, and 100 h of operation was reached with the same batch of the Oxygen Carrier. The reactivity deterioration of the Oxygen Carriers was present during the experimental period. The reactivity deterioration of reacted Oxygen Carriers at different experimental stages was evaluated using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray fluorescence spectrometer. SEM analysis showed no significant change in the morphology of the nickel-based Oxygen Carrier at the fuel reactor temperature ⩽940 °C, but loss of surface area and porosity of reacted Oxygen Carriers was observed when the fuel reactor temperature exceeded 960 °C. The results show that the sintering effect have mainly contributed to the reactivity deterioration of reacted Oxygen Carriers in the CLC process for coal, while the effects of coal ash and sulfur can be ignored. The oxidization of reduced Oxygen Carrier with air was an intensive exothermic process, and the high temperature of Oxygen Carrier particles led to sintering on the surface of Oxygen Carrier particles in the air reactor. Attention must be paid to control the external circulation of Oxygen Carrier particles in the interconnected fluidized beds in order to efficiently transport heat from the air reactor to the fuel reactor, and reduce the temperature of Oxygen Carrier particles in the air reactor. Improvement of reactivity deterioration of reacted Oxygen Carriers was achieved by the supplement of steam into the fuel reactor. Nevertheless, NiO/Al2O3 is still one of the optimal Oxygen Carriers for chemical looping combustion of coal if the sintering of Oxygen Carrier is minimized at the suitable reactor temperature.
F Garcialabiano - One of the best experts on this subject based on the ideXlab platform.
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chemical looping combustion of gaseous and solid fuels with manganese iron mixed oxide as Oxygen Carrier
Energy Conversion and Management, 2018Co-Authors: Raul Perezvega, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Synthetic manganese-iron mixed oxides are considered promising materials to be used as Oxygen Carriers for Chemical Looping Combustion of coal with carbon dioxide capture at low cost. The aim of this work was to evaluate a manganese-iron mixed oxide material with a manganese to iron molar ratio of 0.77:0.23 as Oxygen Carrier for coal combustion by means of chemical looping processes, including both ex-situ and in-situ gasification of coal. The preparation method -spray drying followed by calcination- was optimized in order to produce particles with high reactivity and mechanical strength. The material was studied in two continuously operated facilities designed to burn either gaseous or solid fuels. While full combustion was achieved burning syngas, showing the feasibility of the use of this material considering the ex-situ gasification process. Coal combustion efficiency by in-situ gasification process was improved in comparison with other previously tested low-cost materials such as ilmenite and iron ore. Moreover, the Oxygen Carrier particles showed an interesting magnetic behavior that was able to facilitate Oxygen Carrier recovery from the purge ash stream. In view of these results, the manganese-iron mixed oxide as Oxygen Carrier is proposed as a promising candidate for use coal combustion by the chemical looping process.
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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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biomass combustion in a clc system using an iron ore as an Oxygen Carrier
International Journal of Greenhouse Gas Control, 2013Co-Authors: T Mendiara, Alberto Abad, F Garcialabiano, P Gayan, L F De Diego, Juan AdánezAbstract:Abstract Chemical looping combustion (CLC) is a promising CO2 capture technology with a very low energy penalty and cost. Several previous studies have demonstrated the feasibility of this technology using both gaseous and solid fuels. The combustion of biomass using CLC would make the concept of negative-CO2 emission possible. This paper presents a study of biomass combustion in a continuous CLC unit using pine wood as fuel and iron ore as an Oxygen Carrier and analyses several parameters influencing the CLC process. High carbon captures (>95%) were achieved in the interval 880–915 °C using both steam and CO2 as gasifying agents. Tar compounds were detected at the fuel reactor outlet. After 78 h of continuous operation, no changes were detected in the physical and chemical properties of the Oxygen Carrier particles.
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identification of operational regions in the chemical looping with Oxygen uncoupling clou process with a cu based Oxygen Carrier
Fuel, 2012Co-Authors: Inaki Adanezrubio, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, Juan AdánezAbstract:Abstract Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative chemical-looping process for the combustion of solid fuels with inherent CO 2 capture. The CLOU process demands a material as Oxygen Carrier with the ability to decompose with O 2 release at suitable temperatures for solid fuel combustion, e.g. copper oxide. This article presents an experimental method to determine the maximum Oxygen generation rate of an Oxygen Carrier as well as to determine the minimum solid inventory that must be used in the fuel reactor. The method here proposed can be used as basis for comparison of the use of different Oxygen Carriers or type of coals. In this work, the combustion of coal by using a promising Cu-based Oxygen Carrier prepared by the spray drying method was tested. The Oxygen Carrier (Cu60MgAl) was composed of 60 wt.% CuO and MgAl 2 O 4 was used as supporting material. Experiments were carried out in a batch fluidized-bed reactor at temperatures ranging from 900 to 980 °C. Three different regions were identified depending on the Oxygen Carrier to coal mass ratio. For Oxygen Carrier to coal ratios higher than 50 (Region I), coal was fully converted to CO 2 and H 2 O. In addition, an excess of Oxygen was present in the flue gases, which was close to the equilibrium concentration. When this ratio was in the range 50–25 (Region II), the concentration of Oxygen was decreasing whereas some CO was observed as the only unconverted gas. Further decrease in the Oxygen Carrier to coal ratio below 25 (Region III) caused the depletion of Oxygen in the exhaust gases but CO remained as the only unconverted gas. CH 4 or H 2 were never detected at the reactor outlet in any case and agglomeration problems were never observed. These regions were related to the solids inventory in the fuel reactor by the rate of Oxygen generation calculated in every case. A maximum rate of Oxygen generation for the Oxygen Carrier was determined as kg O 2 /s per kg of Oxygen Carrier, which increased with the temperature from 2.1 × 10 −3 at 930 °C to 2.8 × 10 −3 at 980 °C. From these values, the estimated solids inventory in the fuel reactor was changed from 39 at 930 °C to 29 kg/MW th at 980 °C. The results obtained in this work showed that in the CLOU process it is possible to reach full conversion of the solid fuel with very low solids inventory and avoiding the Oxygen polishing step.
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effect of h2s on the behaviour of an impregnated nio based Oxygen Carrier for chemical looping combustion clc
Applied Catalysis B-environmental, 2012Co-Authors: Cristina Dueso, Luis F. De Diego, Alberto Abad, F Garcialabiano, P Gayan, M T Izquierdo, Juan AdánezAbstract:Abstract Gaseous fuels for chemical-looping combustion (CLC) process may contain sulphur-compounds which could affect the Oxygen-Carrier behaviour, especially if NiO is used as active phase. In this work, several samples of a NiO-based Oxygen-Carrier prepared by impregnation (18 wt.%) on α-Al 2 O 3 , so-called NiO18-αAl, were extracted from a CLC unit after continuous operation with CH 4 containing 500 vppm of H 2 S and characterized subsequently. Part of the sulphur fed to the system was release as SO 2 in the air-reactor during the CLC experiments while the rest remained in the solid particles. Ni 3 S 2 was found in the Oxygen-Carrier extracted from the fuel-reactor, although small amounts of NiSO 4 were also detected. On the contrary, NiSO 4 was the main sulphur compound in the Oxygen-Carrier from the air-reactor while a low concentration of Ni 3 S 2 was present. Despite the accumulated sulphur and the Oxygen transport capacity loss during the operation, the Oxygen-Carrier was capable of recovering the initial reactivity for the CH 4 combustion after some time without H 2 S feeding to the CLC system. In addition, a study about the possible regeneration of the Oxygen-Carrier in the air-reactor working at different temperatures and Oxygen concentrations was performed. Independently of the operating conditions, part of the sulphur remained in the solid and total regeneration was not possible. The analysis of the NiO18-αAl Oxygen-Carrier after the CLC operation using TPR and XPS techniques revealed that sulphur reacted preferably with free NiO instead of NiAl 2 O 4 . Although Ni 3 S 2 was the majority sulphide in the fuel-reactor, minor amounts of other sulphides such as NiS were detected. Sulphur was preferably concentrated in the outer surface of the particles. Taking into account all these results, a previous desulphuration process of the fuel would be necessary when NiO-based Oxygen-Carriers are used in a CLC system.
