Computational gas-solids flows and reacting systems : theory, methods and practice

499 Pages·2011·34.786 MB·English

by  Sreekanth Pannala, Madhava Syamlal, Thomas J O'Brien

Computational Gas-Solids
Flows and Reacting
Systems:
Theory, Methods and Practice
Sreekanth Pannala
Oak Ridge National Laboratory, USA
Madhava Syamlal
National Energy Technology Laboratory, USA
Thomas J. O'Brien
National Energy Technology Laboratory, USA

EnginEEring sciEncE rEfErEncE
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Library of Congress Cataloging-in-Publication Data
Computational gas-solids flows and reacting systems : theory, methods and
practice / Sreekanth Pannala, Madhava Syamlal and Thomas J. O'Brien, editors.
p. cm.
Summary: "This book provides various approaches to computational gas-solids
flow and will aid the researchers, graduate students and practicing engineers
in this rapidly expanding area"--Provided by publisher.
Includes bibliographical references and index.
ISBN 978-1-61520-651-3 (hardcover) -- ISBN 978-1-61520-652-0 (ebook) 1.
Two-phase flow. 2. Gas-solid interfaces. 3. Computational fluid dynamics.
I. Pannala, Sreekanth, 1971- II. Syamlal, Madhava. III. O'Brien, Thomas J.
(Thomas Joseph), 1941-
TA357.5.M84C646 2010
620.1'064--dc22
2009053472
British Cataloguing in Publication Data
A Cataloguing in Publication record for this book is available from the British Library.
All work contributed to this book is new, previously-unpublished material. The views expressed in this book are those of the
authors, but not necessarily of the publisher.
List of Reviewers
Aibing Yu, UNSW, Australia
Aparna Baskaran, Syracuse, New York, USA
Badri Velamur Asokan, ORNL, USA
Berend van Wachem, Imperial College, UK
Christine Hrenya, Boulder, Colorado, USA
Dale Snider, CPFD, USA
Dimitri Gidaspow, IIT, USA
George Bergantz, Seattle, Washington, USA
Janine Galvin, NETL, USA
Jeff Dietiker, NETL, USA
Jennifer Sinclair, Florida, USA
Jim Dufty, Florida, USA
Judith Hill, ORNL, USA
Juray De Wilde, UCL, Belgium
Kate Evans, ORNL, USA
Lothar Reh, ETH, Switzerland
Peter Witt, CSIRO, Australia
Ray Cocco, PSRI, USA
Richard Mills, ORNL, USA
Rodney Fox, Iowa State, USA
Ron Breault, NETL, USA
Shankar Subramaniam, Iowa State, USA
Sofiane Benyahia, NETL, USA
Sourabh Apte, Oregon State, USA
Sreekanth Pannala, ORNL, USA
Stuart Daw, ORNL, USA
Todd Pugsley, University of Saskatchewan, Canada
Wei Ge, CAS, China
Table of Contents
Foreword ............................................................................................................................................xiv
Preface ................................................................................................................................................xvi
Section 1
Theory
Chapter 1
Multiphase Continuum Formulation for Gas-Solids Reacting Flows .....................................................1
Madhava Syamlal, National Energy Technology Laboratory, USA
Sreekanth Pannala, Oak Ridge National Laboratory, USA
Chapter 2
Hydrodynamic Equations from Kinetic Theory: Fundamental Considerations....................................66
James W. Dufty, University of Florida, USA
Aparna Baskaran, Syracuse University, USA
Chapter 3
Kinetic Theory for Granular Materials: Polydispersity ......................................................................102
Christine M. Hrenya, University of Colorado, USA
Chapter 4
Interfacial Interactions: Drag ..............................................................................................................128
Wei Ge, Chinese Academy of Sciences, China
Ning Yang, Chinese Academy of Sciences, China
Wei Wang, Chinese Academy of Sciences, China
Jinghai Li, Chinese Academy of Sciences, China
Chapter 5
Mass and Heat Transfer Modeling ......................................................................................................178
Ronald W. Breault, National Energy Technology Laboratory, USA
Section 2
Numerical Methods
Chapter 6
Coupled Solvers for Gas-Solids Flows ...............................................................................................204
Berend van Wachem, Imperial College, UK
Chapter 7
Quadrature-Based Moment Methods for Polydisperse Gas-Solids Flows .........................................221
Alberto Passalacqua, Iowa State University, USA
Prakash Vedula, University of Oklahoma, USA
Rodney O. Fox, Iowa State University, USA
Chapter 8
Direct Numerical Simulation of Gas-Solids Flow Based on the Immersed Boundary Method .........245
Rahul Garg, Iowa State University, USA
Sudheer Tenneti, Iowa State University, USA
Jamaludin Mohd. Yusof, Los Alamos National Laboratory, USA
Shankar Subramaniam, Iowa State University, USA
Chapter 9
The Multiphase Particle-in-Cell (MP-PIC) Method for Dense Particle Flow ....................................277
Dale M. Snider, CPFD, USA
Peter J. O’Rourke, CPFD, USA
Section 3
Practice

Chapter 10
Circulating Fluidized Beds .................................................................................................................316
Ray Cocco, PSRI, USA
S.B. Reddy Karri, PSRI, USA
Ted Knowlton, PSRI, USA
Chapter 11
CFD Modeling of Bubbling Fluidized Beds of Geldart A Powders ...................................................357
T. Pugsley, The University of Saskatchewan, Canada
S. Karimipour, The University of Saskatchewan, Canada
Z. Wang, The University of Saskatchewan, Canada
Chapter 12
Computational Modeling of Gas-Solids Fluidized-Bed Polymerization Reactors .............................373
Ram G. Rokkam, Iowa State University, USA
Rodney O. Fox, Iowa State University, USA
Michael E. Muhle, Univation Technologies, USA
Chapter 13
Validation Approaches to Volcanic Explosive Phenomenology .........................................................398
Sébastien Dartevelle, Los Alamos National Laboratory, USA
Compilation of References ..............................................................................................................430
About the Contributors ...................................................................................................................467
Index ...................................................................................................................................................471
Detailed Table of Contents
Foreword ............................................................................................................................................xiv
Preface ................................................................................................................................................xvi
Section 1
Theory
Chapter 1
Multiphase Continuum Formulation for Gas-Solids Reacting Flows .....................................................1
Madhava Syamlal, National Energy Technology Laboratory, USA
Sreekanth Pannala, Oak Ridge National Laboratory, USA
This chapter describes the formulation of multiphase continuum models for gas-solids flows with
chemical reactions. A typical formulation of the equations is presented here, following the equations in
the open-source software MFIX (http://mfix.netl.doe.gov) so that interested users may look up details
of the numerical implementation, study the solutions, or experiment with the numerical implementation
of alternative formulations. We will first provide a brief overview of the significance of gas-solids react-
ing flows and the challenges in m odeling these systems along with various efforts undertaken by differ-
ent groups over the last 2–3 decades. We will then summarize the methods used to derive multiphase
continuum models and to formulate constitutive equations. We will later provide information on the
formulation for mass, momentum, granular energy, energy, and species balance equations for gas and
multiple solids phases. We will discuss the constitutive equations required in each of the balance equa-
tions; a detailed discussion of certain constitutive equations, such as the gas-solids drag and granular
stresses (derived from kinetic theory), will be presented by other authors in later chapters. We will point
out the differences between different approaches and direct the reader to references that discuss those
approaches in detail. We will end the chapter with the example problem of the simulation of a bubbling
fluidized bed to illustrate some of the modeling options — physical models, numerical discretization
schemes, and grid resolution – that need to be considered to accurately simulate gas-solids systems.
Chapter 2
Hydrodynamic Equations from Kinetic Theory: Fundamental Considerations....................................66
James W. Dufty, University of Florida, USA
Aparna Baskaran, Syracuse University, USA
In this chapter, a theoretical description is provided for the solid (granular) phase of the gas-solids
flows that are the focus of this book. Emphasis is placed on the fundamental concepts involved in de-
riving a macroscopic hydrodynamic description for the granular material in terms of the hydrodynamic
fields (species densities, flow velocity, and the granular temperature) from a prescribed “microscopic”
interaction among the grains. To this end, the role of the interstitial gas phase, body forces such as
gravity, and other coupling to the environment are suppressed and retained only via a possible non-
conservative external force and implicit boundary conditions. The general notion of a kinetic equation
is introduced to obtain macroscopic balance equations for the fields. Constitutive equations for the
fluxes in these balance equations are obtained from special “normal” solutions to the kinetic equation,
resulting in a closed set of hydrodynamic equations. This general constructive procedure is illustrated
for the Boltzmann-Enskog kinetic equation describing a system of smooth, inelastic hard spheres. For
weakly inhomogeneous fluid states the granular Navier-Stokes hydrodynamic equations are obtained,
including exact integral equations for the transport coefficients. A method to obtain practical solutions
to these integral equations is described. Finally, a brief discussion is given for hydrodynamics beyond
the Navier-Stokes limitations.
Chapter 3
Kinetic Theory for Granular Materials: Polydispersity ......................................................................102
Christine M. Hrenya, University of Colorado, USA
Kinetic-theory-based models of rapid, polydisperse, solids flows are essential for the prediction of
a wide range of practical flows found in both nature and industry. In this work, existing models for
granular flows are critically compared by considering the techniques used for their derivation and the
expected implications of those techniques. The driving forces for species segregation, as predicted by

kinetic theory models, are then reviewed. Although the rigor associated with the development of such
models has improved considerably in the recent past, a systematic assessment of model validity and
computational efficiency is still needed. Finally, a rigorous extension of such models to gas-solids flows
is discussed.
Chapter 4
Interfacial Interactions: Drag ..............................................................................................................128
Wei Ge, Chinese Academy of Sciences, China
Ning Yang, Chinese Academy of Sciences, China
Wei Wang, Chinese Academy of Sciences, China
Jinghai Li, Chinese Academy of Sciences, China
The drag interaction between gas and solids not only acts as a driving force for solids in gas-solids
flows but also plays as a major role in the dissipation of the energy due to drag losses. This leads to
enormous complexities as these drag terms are highly non-linear and multiscale in nature because of the
variations in solids spatio-temporal distribution. This chapter provides an overview of this important
aspect of the hydrodynamic interactions between the gas and solids and the role of spatio-temporal het-
erogeneities on the quantification of this drag force. In particular, a model is presented which introduces
a mesoscale description into two-fluid models for gas-solids flows. This description is formulated in
terms of the stability of gas-solids suspension. The stability condition is, in turn, posed as a minimiza-
tion problem where the competing factors are the energy consumption required to suspend and trans-
port the solids and their gravitational potential energy. However, the lack of scale-separation leads to
many uncertainties in quantifying mesoscale structures. The authors have incorporated this model into
computational fluid dynamics (CFD) simulations which have shown improvements over traditional
drag models. Fully resolved simulations, such as those mentioned in this chapter and the subject of a
later chapter on Immersed Boundary Methods, can be used to obtain additional information about these
mesoscale structures. This can be used to formulate better constitutive equations for continuum models.
Chapter 5
Mass and Heat Transfer Modeling ......................................................................................................178
Ronald W. Breault, National Energy Technology Laboratory, USA
This chapter focuses on the important topic of mass and heat transfer models and closures for con-
tinuum gas-solids reacting flows. The previous three chapters have primarily focused on the hydrody-
namics of gas-solids flows, However, in addition, accurate models for heat and mass transfer must be
constructed to allow predictive simulations of reacting gas-solids flows. As mentioned before, the goal
of an ideal reactor is to establish the best temperature, reactant species distribution and residence time
conditions for reactions. This, obviously, requires an accurate understanding the heat and mass transfer
within the gas and also across the gas-solids interface. This chapter provides an overview of this topic
for dilute and dense gas-solids systems. Specifically, it covers diffusional mass transfer, turbulent dis-
persion, and convective heat transfer between the different phases and, also, at the boundaries. Again in
this case, there is a lack of scale-separation. Thus, there are large uncertainties in the models available
in the literature. Fully resolved simulations can lead to a reduction of this uncertainty.

Section 2
Numerical Methods
Chapter 6
Coupled Solvers for Gas-Solids Flows ...............................................................................................204
Berend van Wachem, Imperial College, UK
In recent years, the application of coupled solver techniques to solve the Navier-Stokes equations has
become increasingly popular. The main reason for this, is the increased robustness originating from
the implicit and global treatment of the pressure-velocity coupling. The drawback of a coupled solver
are the increase in memory requirement and the increased complexity of implementation. However,
fully coupled methods are reported to have an overall favorable computational cost when a suitable
pre-conditioner and algorithm for solving the resulting set of linear equations are employed. In solving
multi-phase flow problems, the coupled solver approach is even more advantageous than in single-
phase, due to the presence of large source terms arising from the coupling of the phases. In this chapter,
various strategies for the fully coupled approach are discussed. These strategies include employing ar-
tificial compressibility, applying physically consistent cell face interpolation, and applying momentum
weighted cell face interpolation. The idea behind the strategies is outlined and their advantages and
disadvantages are discussed. The treatment of source terms and volume fraction in coupled methods is
also shown. Finally, a number of examples of implementations and calculations are presented.
Chapter 7
Quadrature-Based Moment Methods for Polydisperse Gas-Solids Flows .........................................221
Alberto Passalacqua, Iowa State University, USA
Prakash Vedula, University of Oklahoma, USA
Rodney O. Fox, Iowa State University, USA
Classical Euler-Euler two-fluid models based on the kinetic theory of granular flows assume the particle
phase to be dominated by collisions, even when the particle volume fraction is low and hence collisions
are negligible. This leads to erroneous predictions of the particle-phase flow patterns and to the inabil-
ity of such models to capture phenomena like particle trajectory crossing for finite Stokes numbers. To
correctly predict the behavior of dilute gas-particle flows a more fundamental approach based on solv-
ing the Boltzmann kinetic equation is necessary to treat non-zero Knudsen-number and finite Stokes-
number conditions. In this chapter an Eulerian quadrature-based moment method for the direct solution
of the Boltzmann equation is adopted to describe the particle phase, and it is fully coupled with an
Eulerian fluid solver to account for the two-way coupling between the phases. The solution algorithm
for the moment transport equations derived in the quadrature-based moment method and the coupling
procedure with a fluid solver are illustrated. The predictive capabilities of the method are shown con-
sidering a lid-driven cavity flow with particles at finite Stokes and Knudsen numbers, and comparing
the results with both Euler-Euler two-fluid model predictions and with Euler-Lagrange simulations.
Chapter 8

Direct Numerical Simulation of Gas-Solids Flow Based on the Immersed Boundary Method .........245
Rahul Garg, Iowa State University, USA
Sudheer Tenneti, Iowa State University, USA
Jamaludin Mohd. Yusof, Los Alamos National Laboratory, USA
Shankar Subramaniam, Iowa State University, USA
In this chapter, the Direct numerical simulation (DNS) of flow past particles is described. DNS is a
first-principles approach for modeling interphase momentum transfer in gas-solids flows that does not
require any further closure as the flow around the particles is fully resolved. In this chapter, immersed
boundary method (IBM) is described where the governing Navier-Stokes equations are modeled with
exact boundary conditions imposed at each particle surface using IBM and the resulting three dimen-
sional time-dependent velocity and pressure fields are solved. Since this model has complete descrip-
tion of the gas-solids hydrodynamic behavior, one could extract all the Eulerian and Lagrangian statis-
tics for validation and development of more accurate closures which could be used at coarse-grained
simulations described in other chapters.