Download or read book Hydrodynamics of Bubble Column Reactors in Floating Conditions written by Nasim Heydari and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas-liquid as well as gas-liquid-solid bubble column reactors are extensively used in oil refineries and gas treatment plants. They are used especially in chemical processes involving reactions. In recent years, offshore oil and gas industry has been increasingly interested in extending application of reactors for floating platforms such as floating production storage and offloading (FPSO) units. However, the challenges of marine currents and waves influence performance of reactors installed onboard marine units. To maintain the capacity and product specifications in such reactors, prediction of their performance deviations with respect to the static ones is essential. Particularly, investigation on single bubble flow behavior in a moving column will provide a basis to understand the more complex behavior in multi-bubble flow in a bubble column reactor operating in floating conditions. To provide more detailed understanding into the effects of marine swells on the performance of bubble column reactors, this research aims at studying the hydrodynamics of single bubble rising in an inclined column. As the bubble-wall interaction has a major impact on the hydrodynamics of bubble column reactor under floating conditions, the modifications in bubble trajectory, velocity, and aspect ratio imposed by the bubble-wall interactions are studied. This master thesis consists of two chapters. The first chapter contains a general introduction on the challenges brought by the need to extend the application of hydrocarbon treating facilities onboard marine units. Important information about hydrodynamics of bubble column reactors and single bubble rising in liquid are provided. Additionally, the most important issues in selection of the solver and the simulation methods are discussed. In the second chapter, the dynamics of a single ellipsoidal air bubble rising in an inclined cylindrical vessel is experimentally investigated. At the end, a general conclusion on the work performed and recommendations for future works is presented.

Download or read book Experimental Characterization of Slurry Bubble column Reactor Hydrodynamics written by and published by . This book was released on 1997 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandia's program to develop, implement, and apply diagnostics for hydrodynamic characterization of slurry bubble column reactors (SBCRs) at industrially relevant conditions is discussed. Gas liquid flow experiments are performed on an industrial scale. Gamma densitometry tomography (GDT) is applied to measure radial variations in gas holdup at one axial location. Differential pressure (DP) measurements are used to calculate volume averaged gas holdups along the axis of the vessel. The holdups obtained from DP show negligible axial variation for water but significant variations for oil, suggesting that the air water flow is fully developed (minimal flow variations in the axial direction) but that the air oil flow is still developing at the GDT measurement location. The GDT and DP gas holdup results are in good agreement for the air water flow but not for the air oil flow. Strong flow variations in the axial direction may be impacting the accuracy of one or both of these techniques. DP measurements are also acquired at high sampling frequencies (250 Hz) and are interpreted using statistical analyses to determine the physical mechanism producing each frequency component in the flow. This approach did not yield the information needed to determine the flow regime in these experiments. As a first step toward three phase material distribution measurements, electrical impedance tomography (EIT) and GDT are applied to a liquid solid flow to measure solids holdup. Good agreement is observed between both techniques and known values.

Download or read book Hydrodynamics of Gas Liquid Reactors written by Barry Azzopardi and published by John Wiley & Sons. This book was released on 2011-05-12 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of chemical reactors and their safety are as critical to the success of a chemical process as the actual chemistry taking place within the reactor. This book provides a comprehensive overview of the practical aspects of multiphase reactor design and operation with an emphasis on safety and clean technology. It considers not only standard operation conditions, but also the problems of runaway reaction conditions and protection against ensuing over-pressure. Hydrodynamics of Multiphase Reactors addresses both practical and theoretical aspects of this topic. Initial chapters discuss various different types of gas/liquid reactors from a practical viewpoint, and later chapters focus on the modelling of multiphase systems and computational methods for reactor design and problem solving. The material is written by experts in their specific fields and will include chapters on the following topics: Multiphase flow, Bubble columns, Sparged stirred vessels, Macroscale modelling, Microscale modelling, Runaway conditions, Behaviour of vessel contents, Choked flow, Measurement techniques.

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 The Impact of Heat Exchanging Internals on Hydrodynamics of Bubble Column Reactor written by Ahmed Jasim and published by . This book was released on 2016 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this study, the impact of configuration and size of vertical heat exchanging internals in bubble columns on gas holdup, specific gas-liquid interfacial area, bubble chord length, and bubble rise velocity were investigated. Three different configurations of internals, each covering 25% of the column's cross-sectional area, were used to simulate the heat exchanging tubes utilized in the F-T process. The First configuration is a circular-like arrangement of 0.5 inch diameter vertical rods, whereas the second is a hexagonal-like arrangement of 0.5 inch diameter vertical rods. The third configuration is also a circular arrangement but of 1 inch diameter vertical rods used to examine the effect heat exchanging tubes diameter on the hydrodynamics. The experiments were carried out in a 14 cm inner diameter Plexiglas bubble column using air-water system, at superficial gas velocities in the range of 0.02 to 0.45 m/s, measured based on free cross-sectional area of the column available for fluid flow. 4-point optical fiber probe technique was used to collect the diameter profiles of the hydrodynamic parameters. In comparison to bubble column without internals, the obtained result showed that the configuration of the internals significantly affect the hydrodynamics and also the flow resistance inside the column. Steeper gas holdup and specific interfacial area profiles observed when the 0.5 inch circular arrangement internals is used. A distinct asymmetrical radial profiles of gas holdup and specific interfacial area were obtained when the hexagonal arrangement is used. The 1 inch internals enhanced the gas holdup and specific interfacial area near to the wall regions. In the churn turbulent regime, Bubbles chord length and bubbles rise velocity were found to be larger with the presence of internals when compared to bubble column without internals"--Abstract, page iv.

Download or read book Hydrodynamics of Bubble Column Reactors Operating with Non Newtonian Liquids written by Amin Esmaeili Khalil Saraei and published by . This book was released on 2015 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics Mass Transfer and Chemical Reactions in Bubble Column Reactors Using Euler Lagrange Approach written by Manuel Alejandro Taborda Ceballos and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Dense Heat Exchanging Internals on the Hydrodynamics of Bubble Column Reactors Using Non invasive Measurement Techniques written by Mohammed Khloofh Al Mesfer and published by . This book was released on 2013 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Given their efficiency and capital cost reduction, bubble/slurry bubble column reactors are the reactors of choice for Fischer-Tropsch (FT) synthesis, offering clean alternative fuels and chemicals. FT synthesis is an exothermic process that requires many heat exchanging tubes in order to remove heat efficiently and maintain the desired temperature and isothermal operating condition. The impact of the heat exchanging tubes (internals) on the hydrodynamics is not fully understood. Reliably designing and scaling up bubble column reactors requires proper understanding of hydrodynamics, as well as heat and mass transfer parameters. The main objective of this work is to advance the understanding of the effect of internals (25% covered cross-sectional area to meet FT needs) on hydrodynamics (gas holdup distribution, 3D liquid velocity, Reynolds stresses, turbulent kinetic energy, eddy diffusivity, etc.) in bubble columns. Single-source y-ray Computed Tomography (CT) and Radioactive Particle Tracking (RPT) were used for the first time to study the effect of dense internals and gas velocity on the phase holdup distribution and radial profiles, liquid velocity field and turbulent parameter profiles. The main findings obtained for the first time in this study can be summarized as follows: [I] The presence of internals at a given superficial gas velocity causes: [a] An increase in gas holdup and the axial centerline liquid velocity [b] A sharp decrease in turbulence parmeters [II] The increase in superficial gas velocity in the presence of internals causes: [a] An increase in gas holdup, axial centerline liquid velocity and turbulent parameters"--Abstract, leaf iii.

Download or read book Hydrodynamics of a Bubble Column Loop Reactor written by Robert Gerardus Jacobus Maria Van der Lans and published by . This book was released on 1985 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics of a Bubble Column Loop Reactor written by Robert Gerardus Jacobus Maria Lans and published by . This book was released on 1985 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamic Studies in Two and Three phase Slurry Bubble Column Reactors written by James G. Daly and published by . This book was released on 1990 with total page 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 Study of Hydrodynamic and Mass Transfer Characteristics of Multiphase Bubble Column Reactor written by Sanjay Purushottam Godbole and published by . This book was released on 1983 with total page 534 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 Hydrodynamics of a bubble column loop reactor written by Robert G. van der Lans and published by . This book was released on 1985 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamics of Fischer Tropsch Synthesis in Slurry Bubble Column Reactors written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes studies on hydrodynamics of bubble columns for Fischer-Tropsch synthesis. These studies were carried out in columns of 0.051 m and 0.229 m in diameter and 3 m tall to determine effects of operating conditions (temperature and gas flow rate), distributor type (sintered metal plate and single and multi-hole perforated plates) and liquid media (paraffin and reactor waxes) on gas hold-up and bubble size distribution. In experiments with the Fischer-Tropsch (F-T) derived paraffin wax (FT-300) for temperatures between 230 and 280°C there is a range of gas velocities (transition region) where two values of gas hold-up (i.e., two flow regimes) are possible. Higher hold-ups were accompanied by the presence of foam (''foamy'' regime) whereas lower values were obtained in the absence of foam (''slug flow'' in the 0.051 m column, or ''churn-turbulent'' flow regime in the 0.229 m column). This type of behavior has been observed for the first time in a system with molten paraffin wax as the liquid medium. Several factors which have significant effect on foaming characteristics of this system were identified. Reactor waxes have much smaller tendency to foam and produce lower hold-ups due to the presence of larger bubbles. Finally, new correlations for prediction of the gas hold-up and the specific gas-liquid interfacial area were developed on the basis of results obtained in the present study. 49 refs., 99 figs., 19 tabs.

Download or read book Investigations in Hydrodynamics and Mixing Patterns in the Bubble Column Equipped with Internals written by Keller George and published by . This book was released on 2015 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bubble column reactors, with or without solid particles, have a number of applications in the chemical, petrochemical, biochemical and environmental industries. A number of these industrial applications require internals such as baffles, heat transfer surfaces and special distributors to meet demands. Proper selection and design of these internals can lead to the improved performance and efficiency of a bubble column reactor. Several experiments are carried out in a bubble column equipped with a concentric tube bundle (CT) and an internal combination consisting of a concentric tube bundle and concentric baffle (or static mixer) (CTB) respectively. Neutrally buoyant particles are used to determine the effect of the CT and CTB internals on the local flow structures in the equipped column respectively. More upward, near-linear particle movements are observed with the CTB internal over the CT internal. Several non-linear particle movements are also observed. Overall bulk liquid circulation flow patterns are proposed for the intermediate to high gas velocity range based on the observed local flow structures for both internals. Comparisons are made between the gas holdups obtained during internal equipment and that of a comparable hollow bubble column from the literature. Both internals increase the gas holdup of a hollow bubble column. However, the increases with the CT internal are higher by more than 25% of that obtained with the CTB internal on average. The effect of the internals on average bubble size is investigated for the small bubble class. Smaller average diameters are obtained when the CT internal is used. The interfacial area in the presence of the two internals is determined respectively. Higher interfacial areas are obtained with the CT internal. The average difference in interfacial area is 54.0 m2/m3. The effect of the internals on mixing time is determined through dye and aqueous salt tracer studies. In both instances, higher mixing times are obtained with the CTB internal. Liquid backmixing is quantified through the axial dispersion coefficients obtained from the salt tracer studies. The axial dispersion coefficients obtained with the CT internal are higher than that of the CTB internal by about 15% on average.