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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721802395 Category : Languages : en Pages : 28
Book Description
Packed bed reactors are well known for their vast and diverse applications in the chemical industry; from gas absorption, to stripping, to catalytic conversion. Use of this type of reactor in terrestrial applications has been rather extensive because of its simplicity and relative ease of operation. Developing similar reactors for use in microgravity is critical to many space-based advanced life support systems. However, the hydrodynamics of two-phase flow packed bed reactors in this new environment and the effects of one physiochemical process on another has not been adequately assessed. Surface tension or capillary forces play a much greater role which results in a shifting in flow regime transitions and pressure drop. Results from low gravity experiments related to flow regimes and two-phase pressure drop models are presented in this paper along with a description of plans for a flight experiment on the International Space Station (ISS). Understanding the packed bed hydrodynamics and its effects on mass transfer processes in microgravity is crucial for the design of packed bed chemical or biological reactors to be used for water reclamation and other life support processes involving water purification. Motil, Brian J. and Nahra, Henry K. and Balakotaiah, Vemuri Glenn Research Center NASA/TM-2005-213806, E-15145, Rept-2005-01-3035
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721802395 Category : Languages : en Pages : 28
Book Description
Packed bed reactors are well known for their vast and diverse applications in the chemical industry; from gas absorption, to stripping, to catalytic conversion. Use of this type of reactor in terrestrial applications has been rather extensive because of its simplicity and relative ease of operation. Developing similar reactors for use in microgravity is critical to many space-based advanced life support systems. However, the hydrodynamics of two-phase flow packed bed reactors in this new environment and the effects of one physiochemical process on another has not been adequately assessed. Surface tension or capillary forces play a much greater role which results in a shifting in flow regime transitions and pressure drop. Results from low gravity experiments related to flow regimes and two-phase pressure drop models are presented in this paper along with a description of plans for a flight experiment on the International Space Station (ISS). Understanding the packed bed hydrodynamics and its effects on mass transfer processes in microgravity is crucial for the design of packed bed chemical or biological reactors to be used for water reclamation and other life support processes involving water purification. Motil, Brian J. and Nahra, Henry K. and Balakotaiah, Vemuri Glenn Research Center NASA/TM-2005-213806, E-15145, Rept-2005-01-3035
Author: Ali Jabbar Toukan Publisher: ISBN: Category : Fixed bed reactors Languages : en Pages : 103
Book Description
"In this study, the hydrodynamic, i.e. flow regime identification, line average liquid holdup, and the internal liquid holdup of a co-current moving packed bed reactor were studied. For the sake of hydrodynamics study, moving bed reactor is investigated as two-phase upflow packed bed reactor. Scaled down configuration was used to simulate of the moving bed reactors utilized in the industrial process. First, line average liquid holdup is measured with different geometrical configurations covering empty, dry, wet, and packed column under flowrates operation conditions. A new methodology has been developed to determine the line average liquid holdup for a porous catalyst. Second, flow regime is identified by variation of superficial gas velocity at constant liquid superficial velocity. The experiments were carried out in an 11 - inch inner diameter Plexiglas column using the air-water system, at superficial gas velocities in the range of 0.6 to 7.7 cm/s and at a constant liquid superficial velocity of 0.017 cm/s. Gamma ray densitometry (GRD) technique was used to obtain the line average liquid holdup and to identify the flow regime at different axial and radial positions along the column. The obtained results showed that the flow regimes are bubble flow and pulse flow regimes with a transition flow in-between under the operation conditions used. The result showed that the liquid holdup decreased as the superficial gas velocity increased. It was also found that the liquid holdup radial distribution was not uniform. These kinds of information are essential to improve the performance of the reactor"--Abstract, page iv.
Author: Mohammed Jaber Al-Ani Publisher: ISBN: Category : Languages : en Pages : 197
Book Description
"The impacts of the packing characteristics on the hydrodynamics od a trickle bed reactor (TBR) have been investigated using advanced measurements techniques of Gamma-ray densitometry (GRD) and Optical fiber probe and conventional measurement techniques of high-frequency differential pressure transducer and load cell. Two different reactor sizes of bench and pilot plant scale were used. Bench-scale TBR carried out the experiments to assess phase distribution and catalyst utilization with 1.18 cm inside diameter and 72 cm length at ambient pressure and temperature. The mixture of catalyst and fine particles displayed considerable improvements in the phase distribution, liquid holdup profile, and catalyst utilization efficiency. In the pilot plant scale reactor, the catalyst shape showed a significant impact on the hydrodynamics, pressure drop, local gas and liquid velocities, and flow regime transition. The currently used trilobe and quadrilobe in hydrotreating processes showed lower pressure drop, increased liquid holdup, enhanced local gas and liquid saturation and velocities, and lower flow regime transition compared with spherical and cylindrical shapes of catalysts. Meanwhile, mechanistic model named slit model predicted the pressure drop and liquid holdup better than selected correlations where equivalent diameter is used and the bed characteristic is quantitated properly by measured Ergun constants"--Abstract, page iv.
Author: Volker Hessel Publisher: John Wiley & Sons ISBN: 3527606270 Category : Science Languages : en Pages : 681
Book Description
Micro process engineering is approaching both academia and industry. With the provision of micro devices, systems and whole plants by commercial suppliers, one main barrier for using these units has been eliminated. This book focuses on processes and their plants rather than on devices: what is 'before', 'behind' and 'around' micro device fabrication - and gives a comprehensive and detailed overview on the micro-reactor plants and three topic-class applications which are mixing, fuel processing, and catalyst screening. Thus, the book reflects the current level of development from 'micro-reactor design' to 'micro-reactor process design'.
Author: Nikolai Kolev Publisher: Elsevier ISBN: 0080463924 Category : Technology & Engineering Languages : en Pages : 709
Book Description
Packed bed columns are largely employed for absorption, desorption, rectification and direct heat transfer processes in chemical and food industry, environmental protection and also processes in thermal power stations like water purification, flue gas heat utilization and SO2 removal. These Separation processes, are estimated to account for 40%-70% of capital and operating costs in process industry. Packed bed columns are widely employed in this area. Their usage also for direct heat transfer between gas and liquid, enlarge their importance. They are the best apparatuses, from thermodynamical point of view, for mass and heat transfer processes between gas and liquid phase. Their wide spreading is due to low capital investments and operating costs. Since 1995 there has not been published a specialised book in this area, and this is a period of quick development of packed columns. Packed Bed Columns reflects the state of this field including the author's experience on creating and investigating of new packings, column internals and industrial columns. - Considers the theories of mass transfer processes and shows how they help the construction of highly effective packings - Complete information about the performance characteristics of different modern types of highly effective packings - Considers the models for calculation and areas of their application
Author: S. Whitaker Publisher: Springer Science & Business Media ISBN: 9401733899 Category : Science Languages : en Pages : 236
Book Description
Multiphase systems dominate nearly every area of science and technology, and the method of volume averaging provides a rigorous foundation for the analysis of these systems. The development is based on classical continuum physics, and it provides both the spatially smoothed equations and a method of predicting the effective transport coefficients that appear in those equations. The text is based on a ten-week graduate course that has been taught for more than 20 years at the University of California at Davis and at other universities around the world. Problems dealing with both the theoretical foundations and the applications are included with each chapter, and detailed solutions for all problems are available from the author. The course has attracted participants from chemical engineering, mechanical engineering, civil engineering, hydrologic science, mathematics, chemistry and physics.
Author: National Aeronautics and Space Administration (NASA)
Author: National Aeronautics and Space Administration (NASA)
Author: Brian J. Motil
Author: Ali Jabbar Toukan
Author: Mohammed Jaber Al-Ani
Author: Volker Hessel
Author: Bora Aydin
Author: Adeline Rachelle Klotz
Author: Michael John Bly
Author: Nikolai Kolev
Author: S. Whitaker