The Experts below are selected from a list of 615 Experts worldwide ranked by ideXlab platform
Yu Jhih Syu - One of the best experts on this subject based on the ideXlab platform.
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hydrogen production from water gas shift reaction in a High gravity higee environment using a rotating packed bed
International Journal of Hydrogen Energy, 2010Co-Authors: Wei Hsi Che, Yu Jhih SyuAbstract:Abstract Hydrogen production via the water gas shift reaction (WGSR) was investigated in a High gravity environment. A rotating packed bed (RPB) reactor containing a Cu–Zn catalyst and spinning in the range of 0–1800 rpm was used to create High Centrifugal Force. The reaction temperature and the steam/CO ratio ranged from 250 to 350 °C and 2 to 8, respectively. A dimensionless parameter, the G number , was derived to account for the effect of Centrifugal Force on the enhancement of the WGSR. With the rotor speed of 1800 rpm, the induced Centrifugal Force acting on the reactants was as High as 234 g on average in the RPB. As a result, the CO conversion from the WGSR was increased up to 70% compared to that without rotation. This clearly revealed that the Centrifugal Force was conducive to hydrogen production, resulting from intensifying mass transfer and elongating the path of the reactants in the catalyst bed. From Le Chatelier’s principle, a Higher reaction temperature or a lower steam/CO ratio disfavors CO conversion; however, under such a situation the enhancement of the Centrifugal Force on hydrogen production from the WGSR tended to become more significant. Accordingly, a correlation between the enhancement of CO conversion and the G number was established. As a whole, the Higher the reaction temperature and the lower the steam/CO ratio, the Higher the exponent of the G number function and the better the Centrifugal Force on the WGSR.
Wei Hsi Che - One of the best experts on this subject based on the ideXlab platform.
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hydrogen production from water gas shift reaction in a High gravity higee environment using a rotating packed bed
International Journal of Hydrogen Energy, 2010Co-Authors: Wei Hsi Che, Yu Jhih SyuAbstract:Abstract Hydrogen production via the water gas shift reaction (WGSR) was investigated in a High gravity environment. A rotating packed bed (RPB) reactor containing a Cu–Zn catalyst and spinning in the range of 0–1800 rpm was used to create High Centrifugal Force. The reaction temperature and the steam/CO ratio ranged from 250 to 350 °C and 2 to 8, respectively. A dimensionless parameter, the G number , was derived to account for the effect of Centrifugal Force on the enhancement of the WGSR. With the rotor speed of 1800 rpm, the induced Centrifugal Force acting on the reactants was as High as 234 g on average in the RPB. As a result, the CO conversion from the WGSR was increased up to 70% compared to that without rotation. This clearly revealed that the Centrifugal Force was conducive to hydrogen production, resulting from intensifying mass transfer and elongating the path of the reactants in the catalyst bed. From Le Chatelier’s principle, a Higher reaction temperature or a lower steam/CO ratio disfavors CO conversion; however, under such a situation the enhancement of the Centrifugal Force on hydrogen production from the WGSR tended to become more significant. Accordingly, a correlation between the enhancement of CO conversion and the G number was established. As a whole, the Higher the reaction temperature and the lower the steam/CO ratio, the Higher the exponent of the G number function and the better the Centrifugal Force on the WGSR.
Hidenori Kuroki - One of the best experts on this subject based on the ideXlab platform.
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Effect of Sintering Atmosphere and HIP Treatment on Translucency and Mechanical Properties of Alumina Made by High-Speed Centrifugal Compaction Process
Journal of the Japan Society of Powder and Powder Metallurgy, 2000Co-Authors: Hiroyuki Y. Suzuki, Shunzo Tashima, Kenji Shinozaki, Hidenori KurokiAbstract:Complete pore elimination from alumina compacts is attempted under various sintering conditions. An alumina powder of purity of 99.99 % and grain size of 0.2 μm is used as a raw material, and it is mixed with ion-exchanged water of 25 mass%, dispersing agent of 0.6 mass% and binder of 0.1 mass% to prepare slip. Compacting process is executed under High Centrifugal Force of 10, 000-20, 000g. Dense and homogeneous green compacts are obtained and they are subsequently sintered in dry hydrogen, vacuum or HIPed.Although vacuum sintering allows the specimen attains slight Higher density than air-sintered specimen, some pores remain in the structure and the specimen doesn't show translucency. HIP treatment of air-sintered specimen, on the other hand, realizes almost pore free microstructure and the specimen shows translucency. HIPed specimen shows Higher strength(four-point bending strength of 750 MPa)in comparison with commercial translucent alumina, but no remarkable improvement of strength is marked in comparison with air sintered alumina. HIPed specimen loses translucency after annealing in air because of the restore of transgranular pores. In-line transmittance of the HIPed specimen decreases as the wave length decreases.
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High Speed Centrifugal Compaction and Low Temperature Sintering of Submicron Alumina Powder
Journal of the Japan Society of Powder and Powder Metallurgy, 1994Co-Authors: Shunzo Tashima, Shigeaki Hashimoto, Hidenori KurokiAbstract:A slip has been prepared from an alumina powder with the average particle size of 0.22 μm and the purity of 99.99%. Compacts have been formed from the slip in the High speed Centrifugal compaction process by a 8-12kG Centrifugal Force, and sintered in air at 1200-1250°C for 2hr.The SEM observations on polished and thermally etched sections of the sintered compacts showed fine grain structures with no void. The sintering at 1220°C has given a 3-point bending strength of 1160MPa (Weibull modulus : 20.5), an average particle size of 0.64μm, a relative density of 99.3%, and a Vickers hardness of 2100.An alumina having High levels of the purity and same characteristics as Hipped materials was obtained in the Centrifugal process by only sintering a non-doped green compact in air. One of the reason for obtaining such an excellent property of sintered alumina may be due to complete removal of bubbles during compaction by the High Centrifugal Force.
Neng-chou Shang - One of the best experts on this subject based on the ideXlab platform.
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Biodiesel production in a rotating packed bed using K/γ-Al2O3 solid catalyst
Journal of the Taiwan Institute of Chemical Engineers, 2011Co-Authors: Yi-hung Chen, Neng-chou Shang, Yu Hang Huang, Rong Hsien Lin, Ching-yuan Chang, Chia-chi Chang, Pen-chi ChiangAbstract:Abstract The methanolysis of soybean oil with a K/γ-Al 2 O 3 catalyst using a rotating packed bed (RPB) for the production of fatty acid methyl esters (biodiesel) is presented. The RPB, which provides High Centrifugal Force and has an adjustable rotational speed, was employed as a novel heterogeneously catalyzed transesterification reactor. The methanol-to-oil molar ratio, the catalyst dosage, the rotational speed of the packed-bed rotator, and the reaction temperature were investigated for their effects on the yield of fatty acid methyl esters ( Y FAME ) in the RPB. Furthermore, the modified first-order reaction kinetics was employed to study the transesterification reaction rate of the K/γ-Al 2 O 3 catalyzed RPB system. In addition, the transesterification performance and durability of the K/γ-Al 2 O 3 catalyst with respect to Y FAME using the RPB system were evaluated, allowing for further comparison with other heterogeneously catalyzed transesterification reactors. Based on the results, the RPB system is considered as a practical, heterogeneously catalyzed transesterification reactor due to its excellent micromixing characteristics.
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Continuous-flow Esterification of Free Fatty Acids in a Rotating Packed Bed
Industrial & Engineering Chemistry Research, 2010Co-Authors: Yi-hung Chen, Liang-chi Wang, Cheng-hsien Tsai, Neng-chou ShangAbstract:The continuous-flow esterification of free fatty acids (FFAs) with methanol for the production of fatty acid methyl esters (FAMEs) using a rotating packed bed (RPB) is presented herein. The RPB, which provides a High Centrifugal Force and has an adjustable rotational speed, was employed as a novel esterification reactor. The following variables were investigated for their effects on the esterification efficiency: the methanol-FFA molar ratio, the estimated hydraulic retention time, the rotational speed of the packed bed, the reaction temperature, and the catalyst dosage. The conversion of the FFAs in the RPB system significantly depended on the experimental conditions, which influenced the residence time distribution, the esterification reaction rate, and the micromixing intensity. Due to its excellent micromixing characteristics, the RPB system exhibited good efficiency for the esterification reaction in continuous-flow operation. The RPB system achieved the conversion of the FFAs of 10.0−96.6% and the p...
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A continuous-flow biodiesel production process using a rotating packed bed.
Bioresource Technology, 2010Co-Authors: Yi-hung Chen, Yu Hang Huang, Rong Hsien Lin, Neng-chou ShangAbstract:Abstract The continuous-flow transesterification of soybean oil with methanol using a rotating packed bed (RPB) for the production of fatty acid methyl esters (biodiesel) is presented herein. The RPB, which provides High Centrifugal Force and has an adjustable rotational speed, is employed as a novel transesterification reactor. In this study, biodiesel is synthesized via the methanolysis of soybean oil using potassium hydroxide as the catalyst. The following variables were investigated for their effects on transesterification efficiency: the methanol–oil molar ratio, the estimated hydraulic retention time, the rotational speed of the packed-bed rotator, the reaction temperature, and the catalyst dosage. The yield of the fatty acid methyl esters ( Y FAME ) in the RPB system depends significantly on the experimental conditions, which influence the residence time distribution, the transesterification reaction rate, and the micromixing intensity. Due to its excellent micromixing characteristics, the RPB system shows satisfactory transesterification efficiency. The values of Y FAME , productivity of FAMEs ( P FAME ), and P FAME per unit reactor volume ( P FAME / V R ) in the RPB are used to evaluate the performance for biodiesel production and allow for further comparison with other continuous transesterification reactors. Consequently, a RPB is considered a practical transesterification reactor with High transesterification efficiency.
Shunzo Tashima - One of the best experts on this subject based on the ideXlab platform.
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Effect of Sintering Atmosphere and HIP Treatment on Translucency and Mechanical Properties of Alumina Made by High-Speed Centrifugal Compaction Process
Journal of the Japan Society of Powder and Powder Metallurgy, 2000Co-Authors: Hiroyuki Y. Suzuki, Shunzo Tashima, Kenji Shinozaki, Hidenori KurokiAbstract:Complete pore elimination from alumina compacts is attempted under various sintering conditions. An alumina powder of purity of 99.99 % and grain size of 0.2 μm is used as a raw material, and it is mixed with ion-exchanged water of 25 mass%, dispersing agent of 0.6 mass% and binder of 0.1 mass% to prepare slip. Compacting process is executed under High Centrifugal Force of 10, 000-20, 000g. Dense and homogeneous green compacts are obtained and they are subsequently sintered in dry hydrogen, vacuum or HIPed.Although vacuum sintering allows the specimen attains slight Higher density than air-sintered specimen, some pores remain in the structure and the specimen doesn't show translucency. HIP treatment of air-sintered specimen, on the other hand, realizes almost pore free microstructure and the specimen shows translucency. HIPed specimen shows Higher strength(four-point bending strength of 750 MPa)in comparison with commercial translucent alumina, but no remarkable improvement of strength is marked in comparison with air sintered alumina. HIPed specimen loses translucency after annealing in air because of the restore of transgranular pores. In-line transmittance of the HIPed specimen decreases as the wave length decreases.
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Mechanical properties and microstructure of Centrifugally compacted alumina and hot-isostatically-pressed alumina
Materials Science and Engineering: A, 1996Co-Authors: Junichi Koike, Shunzo Tashima, S. Wakiya, Kouichi Maruyama, Hiroshi OikawaAbstract:High purity alumina powder was compacted under a High Centrifugal Force. Mechanical properties of the sintered body were studied by the three-point bending test at room temperature and by the compressive test at elevated temperatures. Comparison was made with hot-isostatically-pressed (HIP) alumina. The room-temperature flexural strength of the Centrifugally compacted (CC) alumina was found to be 1330 MPa compared with 585 MPa of the HIP alumina. The difference in the room-temperature strength was attributed to the presence of the amorphous phase along the grain boundaries of the HIP alumina caused by the segregation of carbon and sulfur during HIP. A large ductility was observed above 1473 K in the CC alumina and above 1573 K in the HIP alumina. High-temperature ductility was lost in the HIP alumina at 1773 K where the amorphous grain-boundary phase was considered to be melted.
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High Speed Centrifugal Compaction and Low Temperature Sintering of Submicron Alumina Powder
Journal of the Japan Society of Powder and Powder Metallurgy, 1994Co-Authors: Shunzo Tashima, Shigeaki Hashimoto, Hidenori KurokiAbstract:A slip has been prepared from an alumina powder with the average particle size of 0.22 μm and the purity of 99.99%. Compacts have been formed from the slip in the High speed Centrifugal compaction process by a 8-12kG Centrifugal Force, and sintered in air at 1200-1250°C for 2hr.The SEM observations on polished and thermally etched sections of the sintered compacts showed fine grain structures with no void. The sintering at 1220°C has given a 3-point bending strength of 1160MPa (Weibull modulus : 20.5), an average particle size of 0.64μm, a relative density of 99.3%, and a Vickers hardness of 2100.An alumina having High levels of the purity and same characteristics as Hipped materials was obtained in the Centrifugal process by only sintering a non-doped green compact in air. One of the reason for obtaining such an excellent property of sintered alumina may be due to complete removal of bubbles during compaction by the High Centrifugal Force.