Download or read book CFD Investigation of Gas solid Flow Dynamics in Monolithic Micro circulating Fluidized Bed Reactors written by Yining Wang and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: La biomasse est une des sources importantes d'énergie primaire et renouvelable. Le développement d'un procédé basé sur la conversion de celle-ci en énergie tout en demeurant respectueux de l'environnement, fait l'objet de recherches intenses aussi bien dans les mondes académique qu'industriel. La gazéification pour produire un gaz de biosynthèse est considérée comme une des options les plus prometteuses via la valorisation des sources de résidus de biomasse. La thermodynamique et la cinétique intrinsèque imposent que les réactions de gazéification de la biomasse doivent être effectuées à des températures élevées, exigeant la fourniture et la récupération de chaleur de manière efficace. Le concept de gazéification allotherme (par opposition à son pendant autotherme) offre une solution attrayante pour la mise en oeuvre à haute température du couplage de réactions fortement endothermique avec des réactions exothermiques. Toutefois, la mise en oeuvre pratique du concept sous haute température n'est pas aisée. Dans ce travail, un nouveau concept pour la gazéification de résidus de la biomasse est proposé impliquant l'hybridation de réactions à hautes températures de la gazéification et de la combustion dans un réacteur monolithique structuré. Clairement, le design et l'optimisation de ce nouveau procédé hybride requiert la compréhension précise, non seulement des phénomènes physico-chimiques de la conversion thermochimique de la biomasse, mais aussi du comportement hydrodynamique, complexe, des deux phases mises en oeuvre dans un microréacteur monolithique à lit fluidisé. À cet égard, la caractéristique hydrodynamique de la distribution des écoulements des phases gaz-solide au sein du réacteur revêt une importance cruciale pour la prédiction du comportement des processus de gazéification/combustion et pour l'examen de stratégies d'opération du procédé. En particulier, en raison de la nature complexe de l'interaction entre le gaz et les particules solides ainsi que la phase stationnaire représentée par le microréacteur monolithique, un des défis dans le design et l'opération de ces réacteurs est la prévention de la maldistribution des phases. Dans ce travail, la mécanique des fluides numériques (MFN) est mise à profit comme outil de simulation permettant d'explorer les distributions des écoulements gaz-solide dans un réacteur monolithique. L'ensemble des sections structurée 111 (le monolithe) et les parties terminales non-structurées (lits fixes aléatoires permettant l'alimentation et l'évacuation de la suspension gaz-solide) est globalement considéré dans la simulation afin de capturer les tendances lourdes des mécanismes contribuant à la dynamique gaz-solide. Les résultats des simulations ont démontré la capacité de la MFN à capturer la caractéristique de non-uniformité de l'écoulement dans ce type de géométrie.

Download or read book CFD Investigation of Gas solid Flow Dynamics in Monolithic Micro circulating Fluidized Bed Reactors written by Yining Wang and published by . This book was released on 2008 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Fluid Dynamics CFD Simulation of a Gas Solid Fluidized Bed Residence Time Validation Study written by Baru Debtera and published by GRIN Verlag. This book was released on 2021-11-29 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Academic Paper from the year 2021 in the subject Physics - Mechanics, , language: English, abstract: In this study, numerical simulations of a gas-solid fluidized bed reactor involving a two-fluid Eulerian multiphase model and incorporating the Kinetic Theory of Granular Flow (KTGF) for the solids phase have been performed using a commercial Computational Fluid Dynamics (CFD) software. The fluidized bed setup consists of 1,5 m height and 0,2 m diameter in which a series of experiments were performed using Helium tracer to determine the Residence Time Distribution (RTD) at various normalized velocities i.e., with different degrees of gas-solids mixing. Both 2D and 3D simulations of the fluidized bed reactor are performed. The main purpose of this study is to understand the hydrodynamic behavior of a gas-solid fluidized bed reactor through a framework of Eulerian multiphase model and to analyze hydrodynamic behavior of the gas-solids mixing.

Download or read book Computational Fluid Dynamics for Engineers written by Bengt Andersson and published by Cambridge University Press. This book was released on 2011-12-22 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics, CFD, has become an indispensable tool for many engineers. This book gives an introduction to CFD simulations of turbulence, mixing, reaction, combustion and multiphase flows. The emphasis on understanding the physics of these flows helps the engineer to select appropriate models to obtain reliable simulations. Besides presenting the equations involved, the basics and limitations of the models are explained and discussed. The book combined with tutorials, project and power-point lecture notes (all available for download) forms a complete course. The reader is given hands-on experience of drawing, meshing and simulation. The tutorials cover flow and reactions inside a porous catalyst, combustion in turbulent non-premixed flow, and multiphase simulation of evaporation spray respectively. The project deals with design of an industrial-scale selective catalytic reduction process and allows the reader to explore various design improvements and apply best practice guidelines in the CFD simulations.

Download or read book Computational Fluid Dynamics CFD of Chemical Processes written by Young-Il Lim and published by MDPI. This book was released on 2021-02-22 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Special Issue, one review paper highlights the necessity of multiscale CFD, coupling micro- and macro-scales, for exchanging information at the interface of the two scales. Four research papers investigate the hydrodynamics, heat transfer, and chemical reactions of various processes using Eulerian CFD modeling. CFD models are attractive for industrial applications. However, substantial efforts in physical modeling and numerical implementation are still required before their widespread implementation.

Download or read book Computational Fluid Dynamics written by Jiyuan Tu and published by Butterworth-Heinemann. This book was released on 2018-01-26 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics: A Practical Approach, Third Edition, is an introduction to CFD fundamentals and commercial CFD software to solve engineering problems. The book is designed for a wide variety of engineering students new to CFD, and for practicing engineers learning CFD for the first time. Combining an appropriate level of mathematical background, worked examples, computer screen shots, and step-by-step processes, this book walks the reader through modeling and computing, as well as interpreting CFD results. This new edition has been updated throughout, with new content and improved figures, examples and problems. - Includes a new chapter on practical guidelines for mesh generation - Provides full coverage of high-pressure fluid dynamics and the meshless approach to provide a broader overview of the application areas where CFD can be used - Includes online resources with a new bonus chapter featuring detailed case studies and the latest developments in CFD

Download or read book Kinetic Theory of Granular Flows and Multi scale CFD Modeling for Fluidized Beds written by Yujian Sun and published by . This book was released on 2016 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluidized beds are widely used in chemical industry for carrying out gas-solids reactions. Their advantages include superior heat transfer, low pressure drop compared to fixed beds, high throughput, and the ability to regenerate or reprocess the spent particles in a separate unit from the main reactor, when operated in a circulating fluidized bed mode. In spite of these desirable features, this type of gas-solids contactors also present challenges in understanding the detailed hydrodynamics, mixing and contacting pattern, as well as their effects on reactions. Design of commercial fluidized beds often requires scale-up from a smaller lab or pilot plant, but the behavior of the different scales must be linked by proper reactor models that take into account the possible changes in hydrodynamics and contacting patterns between the scales. This can be challenging because the prediction and extension of key parameters used in a model, such as axial dispersion number is usually not available, and phenomenological models for these parameters based on science are often missing. To meet these challenges, computational fluid dynamics, or CFD, can be utilized as a tool to extract the needed information by coarse-graining from the detailed hydrodynamics of the multiphase system, thus aiding in more rational design and scale-up of fluidized bed reactors. The CFD models in turn have their own parameters that need phenomenological models, which xii are easier to construct from fundamentals. Two types of simulation methods, i.e. Eulerian-Eulerian and Eulerian-Lagrangian, are investigated in this study. For the Eulerian method (also called two-fluid model, or TFM), in which the discrete solid particles are assumed as a continuous granular phase interpenetrated with the gas, the constitutive models for solids phase stress are needed. In this work, a new set of such models is developed from kinetic theory of granular flows with a new collision model. In this model, both the normal and tangential part of relative velocity between two colliding particles is damped due to inelastic collision, while the traditional model only takes into account the normal part. With this modification, the previously under-estimated dissipation rate of fluctuation energy is increased as expected. The models are implemented in OpenFOAM, an open-source CFD platform, to simulate a fluidized bed. The model improves the prediction of solids volume fraction without extra computational cost. In the Lagrangian or DEM (discrete element method) approach, the effort is motivated by Bhusarapus (2005) pioneering finding using CARPT (computer-aided radioactive particle tracking) that the traditional tracer method for measuring solids residence time distribution (RTD) cannot capture the actual residence time due to inability to distinguish the time that a particle temporarily spends out of the riser after first entry to or before last exit from the riser. By implementing the algorithm developed in this work to record separately the time that each particle actually spends in the riser, Lagrangian simulation is performed for a small circulating fluidized bed in OpenFOAM. The results clearly demonstrate the difference between RTD obtained from simulated traditional tracer method and that from the Lagrangian approach. Other information can be extracted as well such as the first passage time distribution, macromixing index, and interchange coefficient between a core region and an annular region, if using a core-annulus model. The potential capability of this CFD approach is boundless.

Download or read book Coupled CFD DEM Modeling written by Hamid Reza Norouzi and published by John Wiley & Sons. This book was released on 2016-09-14 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discusses the CFD-DEM method of modeling which combines both the Discrete Element Method and Computational Fluid Dynamics to simulate fluid-particle interactions. Deals with both theoretical and practical concepts of CFD-DEM, its numerical implementation accompanied by a hands-on numerical code in FORTRAN Gives examples of industrial applications

Download or read book Computational Fluid Dynamics Applied to Waste to Energy Processes written by Valter Silva and published by Butterworth-Heinemann. This book was released on 2020-06-16 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics Applied to Waste-to-Energy Processes: A Hands-On Approach provides the key knowledge needed to perform CFD simulations using powerful commercial software tools. The book focuses on fluid mechanics, heat transfer and chemical reactions. To do so, the fundamentals of CFD are presented, with the entire workflow broken into manageable pieces that detail geometry preparation, meshing, problem setting, model implementation and post-processing actions. Pathways for process optimization using CFD integrated with Design of Experiments are also explored. The book's combined approach of theory, application and hands-on practice allows engineering graduate students, advanced undergraduates and industry practitioners to develop their own simulations. - Provides the skills needed to perform real-life simulation calculations through a combination of mathematical background and real-world examples, including step-by-step tutorials - Presents worked examples in complex processes as combustion or gasification involving fluid dynamics, heat and mass transfer, and complex chemistry sets

Download or read book Engineering Applications of Computational Fluid Dynamics written by Ku Zilati Ku Shaari and published by Springer. This book was released on 2014-11-28 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the results of Computational Fluid Dynamics (CFD) analysis that can be used for conceptual studies of product design, detail product development, process troubleshooting. It demonstrates the benefit of CFD modeling as a cost saving, timely, safe and easy to scale-up methodology.

Download or read book CFD Modeling of Hydrodynamics of Fluidized Bed written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to simulate a gas-solid fluidized by applying CFD techniques in order to investigate hydrodynamics and heat transfer phenomena. Reactor model predictions will be compared with the corresponding experimental data reported in the literature to validate the model . To simulate a gas-solid fluidized bed we need to use the multiphase flow approach . First we have to write the equations for the different flow regimes and then different CFD techniques are applied for discretization of those equations. After that a code is written for calculating the values of volume fraction, velocity and temperature.

Download or read book CFD Modelling of the Gas solid Flow Dynamics and Thermal Conversion Processes in Fluidised Beds written by Lindsay-Marie Armstrong and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book CFD Modeling of Biomass Gasification Using a Circulating Fluidized Bed Reactor written by Hui Liu and published by . This book was released on 2014 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomass, as a renewable energy resource, can be utilized to generate chemicals, heat, and electricity. Compared with biomass combustion, biomass gasification is more eco-friendly because it generates less amount of green gas (CO2) and other polluting gases (NOx and SO2). This research is focused on biomass gasification using a circulating fluidized bed. In the gasifier, fully fluidized biomass particles react with water vapor and air to generate syngas (CO and H2). A comprehensive model, consisting of three modules, hydrodynamics, mass transfer and energy transfer modules, is built to simulate this process using ANSYS Fluent software and C programming language. In the hydrodynamics module, the k-epsilon turbulence equations are coupled with the fluctuating energy equation to simulate gas-particle interaction in the turbulent flows occurring in the riser. In the mass transfer and energy transfer modules, heat transfer and mass transfer in turbulent flows are simulated to solve for the profiles of temperature and species concentration in the gasifier. The impacts of thermal radiation, water gas shift reaction (WGS), equivalence ratio (ER), and char combustion product distribution coefficient are also investigated to gain deeper understanding of biomass gasification process.

Download or read book CFD Simulation of Hydrodynamics of Three Phase Fluidized Bed written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Such a device is of considerable industrial importance as evident from its wide application in chemical, refining, petrochemical, biochemical processing, pharmaceutical and food industries. Selection and design is one of the main parameter in the performance of three phase system. Success is dependent on the effective contact between the phases. Even though a large number of experimental studies have been done in different process parameters and physical properties, the complex hydrodynamics of three phase fluidized bed reactors are not well understood due to complicated phenomena such as particle- article, liquid- article and particle- ubble interactions. For this reason, computational fluid dynamics (CFD) has been promoted as a useful tool for understanding multiphase reactors for precise design and scale up. In the present work three different configuration of cylindrical column has been taken for studying co-current gas-liquid-solid fluidization with the help of commercial CFD codes as FLUENT. The main focus for analyzing the results is on the column with 1.88 m height and diameter of 0.1 m containing solid particles as glass beads of size 2.18 mm and 4.05 mm. In the present study of three phase fluidized simulation the hydrodynamic parameters investigated includes phase hold up, velocity profiles of all phases, bed expansion, bed voidage, static pressure drop, frictional pressure drop at wall, and energy flows. The operating variables varied includes liquid and air inlet velocity, initial solid static bed height and particle size. The dynamic characteristics obtained from CFD simulation have been validated with the experimental results and a good agreement has been observed. Eulerian-Eulerian granular multiphase flow approach is capable of predicting the overall performance of gas- iquid- olid fluidized bed. The expanded bed height is s.

Download or read book Process Intensification written by David Reay and published by Butterworth-Heinemann. This book was released on 2013-06-05 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: Process Intensification: Engineering for Efficiency, Sustainability and Flexibility is the first book to provide a practical working guide to understanding process intensification (PI) and developing successful PI solutions and applications in chemical process, civil, environmental, energy, pharmaceutical, biological, and biochemical systems. Process intensification is a chemical and process design approach that leads to substantially smaller, cleaner, safer, and more energy efficient process technology. It improves process flexibility, product quality, speed to market and inherent safety, with a reduced environmental footprint. This book represents a valuable resource for engineers working with leading-edge process technologies, and those involved research and development of chemical, process, environmental, pharmaceutical, and bioscience systems. - No other reference covers both the technology and application of PI, addressing fundamentals, industry applications, and including a development and implementation guide - Covers hot and high growth topics, including emission prevention, sustainable design, and pinch analysis - World-class authors: Colin Ramshaw pioneered PI at ICI and is widely credited as the father of the technology

Download or read book Novel Process Windows written by Volker Hessel and published by John Wiley & Sons. This book was released on 2015-03-23 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the concept of novel process windows, focusing on cost improvements, safety, energy and eco-efficiency throughout each step of the process. The first part presents the new reactor and process-related technologies, introducing the potential and benefit analysis. The core of the book details scenarios for unusual parameter sets and the new holistic and systemic approach to processing, while the final part analyses the implications for green and cost-efficient processing. With its practical approach, this is invaluable reading for those working in the pharmaceutical, fine chemicals, fuels and oils industries.

Download or read book Bubbly Flows written by Martin Sommerfeld and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.