Download or read book Hydrodynamics and Mass Transfer in Bubble and Three phase Fluidized Columns with and Without Baffles written by Alain B. P. Catros and published by . This book was released on 1986 with total page 1110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics and Mass Transfer in Downflow Slurry Bubble Columns written by Subrata Kumar Majumder and published by CRC Press. This book was released on 2019-01-02 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Slurry bubble column reactors are intensively used as a multiphase reactor in the chemical, biochemical, and petrochemical industries for carrying out reactions and mass transfer operations in which a gas, made up of one or several reactive components, comes into contact or reacts with a liquid. This volume describes the hydrodynamics of three-phase gas-liquid-solid flow in a downflow slurry bubble column. The efficiency of the downflow gas interacting system is characterized by the self-entrainment of secondary gas. The book covers the gas entrainment phenomena, gas holdup characteristics, pressure drop, gasliquid mixing characteristics, bubble size distribution, interfacial phenomena, and the mass transfer phenomena in the downflow slurry system. This volume will be useful in chemical and biochemical industries and in industrial research and development sectors, as well as in advanced education courses in this area. The book will be helpful for further understanding the multiphase behavior in gas interacting multiphase systems for research and development. The hydrodynamic and mass transfer characteristics discussed will be useful in the design and installation of the modified slurry bubble column in industry for specific applications.

Download or read book Hydrodynamics and Mass Transfer in Bubble Columns written by Onkar N. Manjrekar and published by . This book was released on 2016 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bubble columns and slurry bubble columns are multiphase reactors used for a wide range of applications in the biochemical, chemical, petrochemical, and metallurgical industries. In spite of their widespread usage, the scale-up of bubble columns remains an ongoing challenge. Various scale-up approaches, based on concepts ranging from ideal mixing to complex 3-D multiphase CFD models, have been used for assessing the effect of column size and gas and liquid flow rates on column hydrodynamics and reactor performance. Among these approaches, phenomenological models based on either single-class or multi-class bubbles that were validated on cold flow systems have been successful in predicting the residence time distributions of gas and liquid in pilot-scale bubble columns (Chen et al., 2004) (Gupta, 2002). However, such models are not entirely predictive, since they are validated using columns having the same size as hot operating units. To provide better predictive capability, we need prior knowledge of local hold-up, transport coefficients, and bubble dynamics. This dissertation provides an improved understanding of the key design parameters (gas hold-up, volumetric mass transfer coefficients, gas-liquid interfacial area, and their spatial distribution) for predictive scale-up of bubble columns. In this work, a 4-point optical probe is used to estimate local gas hold-up and bubble dynamics (specific interfacial area, frequency, bubble velocity, and bubble chord-lengths) and their radial profiles in a cold-flow slurry bubble column and a bubble column photo-bioreactor. Along with local bubble dynamics, the effect of superficial gas velocity on volumetric mass transport coefficients in several sizes of bubble columns, with and without internals, and in slurry bubble columns and photo-bioreactors are studied. Key findings: In the bubbly flow regime, bubble dynamics in photo-bioreactors with suspended algae were dominated by the physicochemical properties of the liquid, as distinguished from the churn-turbulent flow regime in the slurry bubble columns, where bubble dynamics were mainly affected by turbulent intensities. In the bubbly-flow regime, volumetric mass transfer coefficients increased with an increase in superficial gas velocity. However, in the churn-turbulent flow regime, they approached a constant value with an increase in the superficial gas velocity. A new methodology was proposed to identify the flow regime from optical probe signals based on the support vector machine algorithm, which can uniquely classify flow regimes for various systems on a single flow regime map. A new model for the liquid phase mixing, that with a proper choice of the mass transfer coefficients enables a good match of the predicted and measured tracer response is described. This model provides a better prediction of volumetric mass transfer coefficients than the currently used well mixed model for the liquid phase (CSTR). The dissertation improves the fundamental understanding of the connection between bubble dynamics and mass transfer. Using the 4-point optical probe as a tool, it demonstrates a connection between bubble dynamics and volumetric mass transfer coefficients. Present work addresses the need of industries to have a method that can be used as an online process control tool to identify flow regime, this method has been tested at cold flow conditions and needs to be implemented at hot flow conditions. The parameters (radial distributions of gas hold-up, bubble velocities, and volumetric mass transfer coefficient) that are evaluated in the present work can be used to validate phenomenological models and CFD results at cold flow conditions, which can later be combined with process chemistry to accomplish scale-up (Chen et al., 2004). The open literature on multiphase reactors is mainly limited to cold flow condition, and techniques such as the optical probe need to be extended to hot flow conditions. The optical probe described here can withstand high temperature and pressure, but for hot flow conditions it requires a better binding agent to hold the probe tips together, one that will not dissolve in industrial solvents.

Download or read book Hydrodynamics and Mass Transfer Studies in High Pressure Gas liquid and Gas liquid solid Fluidization written by Wai Man R. Lau and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Slurry bubble columns and gas-solid fluidized bed reactors are some of the most commonly used industrial processes. Considerable interests have been recognized in the field of physical, chemical, petrochemical, electrochemical, and biochemical operations (Fan, 1989). In these reactor systems, large axial dispersion of phases and high flow patterns can be achieved by the excellent macromixing characteristics. It also provides excellent heat and mass transfer without the aid of external mechanisms and relatively easy operation. Despite the advantages of operations, the transport behavior in these systems is very complex and a comprehensive knowledge of the hydrodynamics, heat and mass transfer and mixing are required for successful application of these systems. Some aspects of the fundamental characteristics of evaporative liquid jets in gas-liquid-solid flows are studied and some pertinent literature is reviewed. It is found that the injection of an evaporative liquid jet decreases the minimum fluidization velocity at a high pressure due to the additional gas flow generated from liquid evaporation. Fluidizing gas velocities have no significant effect on the jet penetration length in a dense phase fluidized bed while it reduces the radial dispersed distance of the evaporative liquid. The tomographic images of liquid nitrogen injection in a dense phase fluidized bed indicate a distribution of reduced bubble sizes compared to a dry bed. The hydrodynamics, gas-liquid mass transfer properties and liquid entrainment phenomena in a high pressure and high temperature bubble column is investigated. Effects of pressure on hydrodynamics and mass transfer properties are mainly through the change in gas and liquid physical properties, which in turn changes the bubble dynamics that govern the transport phenomena. Experimental results show that liquid velocities have a direct influence on kl while other factors have a dominant effect on the interfacial area over kl. Liquid entrainment in bubble columns is controlled by the droplet formation during bubble bursting at interface. Effect of pressure on liquid entrainment is to due to the higher drag force exerted on the liquid droplet with higher gas density and the formation of smaller droplet by the smaller bubbles at high pressure.

Download or read book Hydrodynamics and Mass Transfer Studies in Three Phase Fluidized Beds written by Vinodkumar R. Dhanuka and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Oxygen Mass Transfer in Bubble Columns and Three phase Fluidized Beds written by Manuel Alvarez-Cuenca and published by . This book was released on 1979 with total page 1194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1985 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics and Mass Transfer in Different Zones of a Three phase Fluidized Bed written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental and Computational Study of Hydrodynamics and Mass Transfer in Gas liquid Bubble Columns written by Houman Shirzadi and published by . This book was released on 2012 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enhancement of Gas liquid and Particle liquid Mass Transfer in Bubble Columns and Three phase Fluidized Beds written by Anand Prakash and published by . This book was released on 1991 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Improved Model for Describing Mass transfer in Bubble Columns and Three phase Fluidized Beds written by Abdulghanni H. Nhaesi and published by . This book was released on 1986 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics and Mass Transfer in Three phase Fluidized Beds with Highly Viscous Liquids written by Akash N. Patwari and published by . This book was released on 1983 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics and Mass Transfer in Bubble Columns at Elevated Pressures written by Hugo Martijn Letzel and published by . This book was released on 1998 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics Mixing and Mass Transfer in Bubble Columns with Internals written by Mohamed Hamed and published by . This book was released on 2012 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bubble columns and slurry bubble columns are considered reactors of choice for a wide range of applications in the chemical, biochemical, and petrochemical industries. Most of the chemical applications of bubble columns include exothermic processes and hence they require some means of heat removal to maintain a steady process. The most practical means for heat removal in these reactors is the utilization of vertical cooling internals since they provide high heat transfer area per reactor volume. However, the effects of these internals on the reactor performance are poorly understood in the open literature. This causes the design of the internals to be based on empirical rules not on the applications of fundamentals. The main objective of this study is to enhance the understanding of the effects of vertical cooling internals on the gas hydrodynamics, gas mixing, and mass transfer. In addition, this study attempts to develop and validate models that can simulate the radial gas velocity profile and axial gas mixing in the presence and absence of internals. Finally, this work aims to validate all the observed experimental results and models in larger columns with and without internals to have a better understanding of the scale-up effects in the presence of internals. This is accomplished by carrying out experiments in a lab-scale 8-inch bubble column and a pilot-scale 18-inch bubble column in the absence and presence of internals. The studied % occluded area by internals (~ 25%) is chosen to match the % occluded area used in the Fischer-Tropsch synthesis. The radial gas velocity profiles are measured using the 4-point optical probe and are used to validate the 1-D gas velocity model developed by Gupta (2002). Gar tracer techniques are used to study the effect of internals on the overall axial gas mixing and mass transfer. A 2-D model, that considers the radial variations of the gas velocity and gas holdup, is developed and used to analyze the tracer data allowing the estimation of the turbulent diffusivities of the gas phase. The 2-D model along with the axial dispersion coefficient model developed by Degaleesan and Dudukovic (1998) are used to determine the contribution of different mixing mechanisms to the overall axial gas mixing. The effect of internals and column diameter on the gas velocity profile, gas mixing, and mass transfer is assessed. The presence of internals causes: The effect of internals and column diameter on the gas velocity profile, gas mixing, and mass transfer is assessed. The presence of internals causes: An increase in the center-line gas velocity. A significant decrease in axial gas mixing. A decrease in the gas-liquid mass transfer coefficient. The increase in column diameter causes: Enhancement of the gas circulation. An increase in axial gas mixing. The model developed by Gupta (2002) to predict radial gas velocity profiles is validated at different operating conditions in the presence and absence of internals. A 2-D convection-diffusion model is developed and proven useful in interpreting gas tracer data and simulating the overall axial gas mixing in the presence and absence of internals.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1986 with total page 734 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Three phase Inverse Fluidized Bed written by Volen Rossenov Nikolov and published by . This book was released on 1998 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Surfactants on the Hydrodynamics of Bubble Columns and Three phase Fluidized Beds written by Puneet Dargar and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: