Yang Fluidization, Solids Handling, and Processing

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.

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.

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.

xiiContents

6.0FURTHER SIMPLIFICATIONS IN THE SCALING