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FLUIDIZATION, SOLIDS HANDLING, AND PROCESSING

Industrial Applications

Edited by

Wen-Ching Yang

Siemens Westinghouse Power Corporation

Pittsburgh, Pennsylvania

np NOYES PUBLICATIONS

Westwood, New Jersey, U.S.A.

98-18924 CIP

Copyright © 1998 by Noyes Publications

No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without permission in writing from the Publisher.

Library of Congress Catalog Card Number: 98-18924 ISBN: 0-8155-1427-1

Printed in the United States

Published in the United States of America by Noyes Publications

369 Fairview Avenue, Westwood, New Jersey 07675 10 9 8 7 6 5 4 3 2 1

Library of Congress Cataloging-in-Publication Data

Fluidization, solids handling, and processing : industrial applications / edited by Wen-Ching Yang.

p .

cm .

 

Includes bibliographical references and index.

ISBN 0

-8155

-1427-1

1. Fluidization. 2. Bulk solids flow. I. Yang, Wen-ching, 1939-

TP156.F65F5828

1998

660 ' .284292

--dc21

PARTICLE TECHNOLOGY SERIES

Series Editor: Liang-Shih Fan, Ohio State University

FLUIDIZATION, SOLIDS HANDLING, AND PROCESSING: Edited by Wen-Ching Yang

INSTRUMENTATION FOR FLUID-PARTICLE FLOWS: by S. L. Soo

v

Contributors

John C. Chen

Thomas B. Jones

Department of Chemical

Department of Electrical

Engineering

Engineering

Lehigh University

University of Rochester

Bethlehem, PA

Rochester, NY

Bryan J. Ennis

S.B. Reddy Karri

E&G Associates

Particulate Solid Research, Inc.

Nashville, TN

Chicago, IL

Liang-Shih Fan

George E. Klinzing

Department of Chemical

Department of Chemical and

Engineering

Petroleum Engineering

Ohio State University

University of Pittsburgh

Columbus, OH

Pittsburgh, PA

Leon R. Glicksman

Ted M. Knowlton

Department of Architecture,

Particulate Solid Research, Inc.

Building Technology Program

Chicago, IL

Massachusetts Institute of

 

Technology

Mooson Kwauk

Cambridge, MA

Institute of Chemical Metallurgy

 

Adacemia Sinica

 

Beijing, People’s Republic of

 

China

ix

x

Contributors

 

JackReese

Joachim Werther

Department of Chemical

Technical University Hamburg-

 

Engineering

Harburg

Ohio State University

Hamburg, Germany

Columbus, OH

Peter Wypych

 

 

Jens Reppenhagen

Department of Mechanical

Technical University Hamburg-

Engineering

 

Harburg

University of Wollongong

Hamburg, Germany

Wollongong, NSW, Australia

Ellen M. Silva

Shang-Tian Yang

Department of Chemical

Department of Chemical

 

Engineering

Engineering

Ohio State University

Ohio State University

Columbus, OH

Columbus, OH

Gabriel I. Tardos

Wen-Ching Yang

Department of Chemical

Science and Technology Center

 

Engineering

Siemens Westinghouse Power

City College of City University of

Corporation

 

New York

Pittsburgh, PA

New York, NY

Frederick A. Zenz

 

 

Richard Turton

Process Equipment Modeling &

Department of Chemical

Mfg. Co., Inc.

 

Engineering

Cold Spring, NY

West Virginia University

 

Morgantown, WV

 

Preface

This volume, Fluidization, Solids Handling, and Processing, is the first of a series of volumes on “Particle Technology” to be published by Noyes Publications with L. S. Fan of Ohio State University as the consulting editor. Particles are important products of chemical process industries spanning the basic and specialty chemicals, agricultural products, pharmaceuticals, paints, dyestuffs and pigments, cement, ceramics, and electronic materials. Solids handling and processing technologies are thus essential to the operation and competitiveness of these industries. Fluidization technologyis employed not only in chemical production, it also is applied in coal gasification and combustion for power generation, mineral processing, food processing, soil washing and other related waste treatment, environmental remediation, and resource recovery processes. The FCC (Fluid Catalytic Cracking) technology commonly employed in the modern petroleum refineries is also based on the fluidization principles.

There are already many books published on the subjects of fluidization, solids handling, and processing. On first thought, I was skeptical about the wisdom and necessity of one more book on these subjects. On closer examination, however, I found that some industrially important subjects were either not covered in those books or were skimpily rendered. It would be a good service to the profession and the engineering community to assemble all these topics in one volume. In this book, I have invited recognized experts in their respective areas to provide a detailed treatment

vi

Preface vii

of those industrially important subjects. The subject areas covered in this book were selected based on two criteria: (i) the subjects are of industrial importance, and (ii) the subjects have not been covered extensively in books published to date.

The chapter on fluidized bed scaleup provides a stimulating approach to scale up fluidized beds. Although the scaleup issues are by no means resolved, the discussion improves the understanding of the issues and provides reassessments of current approaches. The pressure and temperature effects and heat transfer in fluidized beds are covered in separate chapters. They provide important information to quantify the effects of pressure and temperature. The gas distributor and plenum design, critical and always neglected in other books, are discussed in detail. For some applications, the conventional fluidized beds are not necessarily the best. Special design features can usually achieve the objective cheaper and be more forgiving. Two of the non-conventional fluidized beds,recirculating fluidized beds with a draft tube and jetting fluidized beds, are introduced and their design approaches discussed. Fluidized bed coating and granulation, applied primarily in the pharmaceutical industry, is treated from the fluidization and chemical engineering point of view. Attrition, which is critical in design and operation of fluidized beds and pneumatic transport lines, is discussed in detail in a separate chapter. Fluidization with no bubbles to minimize bypassing, bubbleless fluidization, points to potential areas of application of this technology. The industrial applications of the ever-increasingly important three-phase fluidization systems are included as well. The developments in dense phase conveying and in long distance pneumatic transport with pipe branching are treated separately in two chapters. The cyclone, the most common component employed in plants handling solids and often misunderstood, is elucidated by an experienced practitioner in the industry. The book is concluded with a discussion on electrostatics and dust explosion by an electrical engineer.

This book is not supposed to be all things to all engineers. The primary emphasis of the book is for industrial applications and the primary audience is expected to be the practitioners of the art of fluidization, solids handling, and processing. It will be particularly beneficial for engineers who operate or design plants where solids are handled, transported, and processed using fluidization technology. The book, however, can also be useful as a reference book for students, teachers, and managers who study particle technology, especially in the areas of application of fluidization technology and pneumatic transport.

viii Preface

I’d like to take this opportunity to thank Professor Fan who showed confidence in me to take up this task and was always supportive. I’d also like to thank the authors who contributed to this book despite their busy schedules. All of them are recognized and respected experts in the areas they wrote about. The most appreciation goes to my wife, Rae, who endured many missing weekends while I worked alone in the office.

Pittsburgh, Pennsylvania

Wen-Ching Yang

February, 1998

 

NOTICE

To the best of our knowledge the information in this publication is accurate; however the Publisher does not assume any responsibility or liability for the accuracy or completeness of, or consequences arising from, such information. This book is intended for informational purposes only. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the Publisher. Final determination of the suitability of any information or product for use contemplated by any user, and the manner of that use, is the sole responsibility of the user. We recommend that anyone intending to rely on any recommendation of materials or procedures mentioned in this publication should satisfy himself as to such suitability, and that he can meet all applicable safety and health standards.

Contents

1 Fluidized Bed Scale-up ..............................................................

1

Leon R. Glicksman

 

1.0

INTRODUCTION ....................................................................................

1

2.0

REACTOR MODELING: BED DIAMETER INFLUENCE ...............

4

3.0

INFLUENCE OF BED DIAMETER ON HYDRODYNAMICS .......

10

 

3.1

Bubbling Beds.................................................................................

10

 

3.2

Mixing ...................................................................................

20

 

3.3

Influence of Bed Diameter on Circulating Fluidized Beds ..........

22

 

3.4

Flow Transition ...............................................................................

25

4.0

EXPERIMENTAL MEANS TO ACCOUNT FOR SCALE-UP: USE

 

OF SCALE MODELS ...........................................................................

26

 

4.1

Development of Scaling Parameters .............................................

27

 

4.2

Governing Equations ......................................................................

29

 

4.3

Fluid-Solid Forces ..........................................................................

35

 

4.4

Spouting and Slugging Beds ..........................................................

38

5.0

SIMPLIFIED SCALING RELATIONSHIPS ......................................

39

 

5.1

Low Reynolds Number ..................................................................

39

 

5.2

High Reynolds Numbers ................................................................

41

 

5.3

Low Slip Velocity...........................................................................

42

 

5.4

General Case ...................................................................................

43

 

5.5

Range of Validity of Simplified Scaling .......................................

44

xi

xiiContents

6.0FURTHER SIMPLIFICATIONS IN THE SCALING

 

RELATIONSHIP ...................................................................................

51

 

6.1

Viscous Limit ..................................................................................

51

 

6.2

Other Derivations for Circulating Fluidized Beds ........................

54

 

6.3

Deterministic Chaos .......................................................................

55

7.0

DESIGN OF SCALE MODELS ...........................................................

56

 

7.1

Full Set of Scaling Relationships ...................................................

56

 

7.2

Design of Scale Models Using the Simplified Set

 

 

 

of Scaling Relationships .................................................................

61

8.0

EXPERIMENTAL VERIFICATION OF SCALING LAWS FOR

 

 

BUBBLING BEDS ................................................................................

65

 

8.1

Hydrodynamic Scaling of Bubbling Beds ....................................

65

 

8.2

Verification of Scaling Relationships for Bubbling

 

 

 

and Slugging Beds ..........................................................................

69

 

8.3

Verification of Scaling Laws for Spouting Beds ..........................

75

 

8.4

Verification of Scaling Relationships for Pressurized

 

 

 

Bubbling Beds .................................................................................

76

9.0

APPLICATIONS OF SCALING TO COMMERCIAL BUBBLING

 

FLUIDIZED BED UNITS .....................................................................

80

10.0

HYDRODYNAMIC SCALING OF CIRCULATING BEDS ............

91

11.0

CONCLUSIONS .................................................................................

100

ACKNOWLEDGMENTS ...........................................................................

102

NOTATIONS .................................................................................

103

REFERENCES .................................................................................

104

2 Pressure and Temperature Effects in

 

Fluid-Particle Systems ..........................................................

111

Ted M. Knowlton

 

1.0 INTRODUCTION ................................................................................

111

1.1

Minimum Fluidization Velocity ..................................................

113

1.2

Bed Voidage and Bed Expansion ................................................

120

1.3

Bubbles in Fluidized Beds ...........................................................

124

1.4

Bubble Size and Frequency .........................................................

125

1.5

Bed-to-Surface Heat Transfer Coefficient ..................................

129

1.6

Entrainment and Transport Disengaging Height ........................

131

1.7

Particle Attrition at Grids .............................................................

134

1.8

Particle Attrition in Cyclones .......................................................

136

1.9

Jet Penetration ...............................................................................

137

1.10

Regime Transitions .......................................................................

139

1.11

Cyclone Efficiency .......................................................................

146

NOTATIONS .................................................................................

147

REFERENCES .................................................................................

149

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