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20050681 Bulk Solids Handling

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P1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32Bulk Solids HandlingiBulk Solids Handling: Equipment Selection and Operation Edited by Don McGlinchey 2008 Blackwell Publishing Ltd. ISBN: 978-1-405-15825-1P1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32Bulk Solids HandlingEquipment Selection and OperationEdited byDon McGlincheyReaderCentre for Industrial Bulk Solids HandlingGlasgow Caledonian UniversityUKiiiP1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32c 2008 by Blackwell Publishing LtdBlackwell Publishing editorial ofces:Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UKTel: +44 (0)1865 776868Blackwell Publishing Professional, 2121 State Avenue, Ames, Iowa 50014-8300, USATel: +1 515 292 0140Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, AustraliaTel: +61 (0)3 8359 1011The right of the Author to be identied as the Author of this Work has been asserted in accordance with theCopyright, Designs and Patents Act 1988.All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, inany form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted bythe UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.Designations used by companies to distinguish their products are often claimed as trademarks. All brand namesand product names used in this book are trade names, service marks, trademarks or registered trademarks of theirrespective owners. The publisher is not associated with any product or vendor mentioned in this book.This publication is designed to provide accurate and authoritative information in regard to the subject mattercovered. It is sold on the understanding that the publisher is not engaged in rendering professional services. Ifprofessional advice or other expert assistance is required, the services of a competent professional should besought.First published 2008 by Blackwell Publishing LtdISBN: 978-1-4051-5825-1Library of Congress Cataloging-in-Publication DataBulk solids handling : equipment selection and operation / edited by Don McGlinchey. 1st ed.p. cm.Includes bibliographical references and index.ISBN-13: 978-1-4051-5825-1 (hardback : alk. paper)ISBN-10: 1-4051-5825-5 (hardback : alk. paper) 1. Bulk solids handlingEquipment and supplies.I. McGlinchey, Don.TS180.8.B8B853 2008621.8

6dc22A catalogue record for this title is available from the British LibrarySet in 10/12 pt Times by Aptara Inc., New Delhi, IndiaPrinted and bound in Singapore by C.O.S. Printers Pte LtdThe publishers policy is to use permanent paper from mills that operate a sustainable forestry policy, and whichhas been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore,the publisher ensures that the text paper and cover board used have met acceptable environmental accreditationstandards.For further information on Blackwell Publishing, visit our website:www.blackwellpublishing.comivP1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32ContentsContributors xiAims and Scope xiiAcknowledgements xiii1 Bulk powder properties: instrumentation and techniques 1NAYLAND STANLEY-WOOD1.1 Introduction 11.1.1 Density 31.1.2 Particleparticle bonding 31.1.3 Particle packing 31.1.4 Flowability 31.1.5 Variables contributing to bulk powder properties 31.2 Particle and powder densities 51.3 Determination and protocol for bulk density 81.3.1 Aerated bulk density 81.3.2 Poured bulk density 101.3.3 Tap density 101.3.4 Fluidised bulk density 111.3.5 Compressed and compact bulk density 111.4 Flow properties from powder bulk densities 111.4.1 Hausner ratio 111.4.2 Carrs percentage compressibility frombulk densities 131.4.3 Compacted bulk density 151.4.4 Ergun particle density 161.4.5 Application of the Hausner ratio to uidisedpowder systems 201.4.6 Floodability 201.4.7 Flowability 221.4.8 Dispersibility or dustiness 231.4.9 Permeability 241.4.10 Wall friction tester 251.5 Powder angles 271.5.1 Poured and drained angles 271.5.2 Static angle of repose of a heap 271.5.3 Angle of fall 291.5.4 Angle of difference 291.5.5 Dynamic angle of repose 29vP1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32vi CONTENTS1.6 Bulk powder ow properties from internal anglesand shear 301.6.1 Failure properties 301.6.2 Flowability and failure 311.6.3 Failure function from shear tests 341.6.4 Jenike effective angle of internal friction 361.7 Instrumentation for the measurement of tensile strengthand cohesion 371.7.1 Cohesiveness and tensile strength 371.7.2 Split cell and lifting lid (vertical shear) instrumentsfor tensile strength and cohesiveness 381.7.3 Direct measurement of cohesion 411.7.4 Uniaxial compression 441.8 Bulk power correlations 531.8.1 Relationships between cohesion and tensilestrength 541.8.2 The inuence of particle characteristics on bulkpowder properties 571.8.3 Overview of the instrumentation and techniquesavailable for the determination of bulkpowder properties 59References 622 Hopper/bin design 68JOHN W. CARSON2.1 Fundamentals 682.2 Flow patterns 692.3 Arching 742.4 Ratholing 762.5 Flow rate 762.6 Segregation 782.6.1 Sifting 782.6.2 Dusting (particle entrainment) 792.6.3 Fluidisation (air entrainment) 792.7 Importance of outlet and outlet region 792.8 Aerated versus non-aerated 822.9 Selection criteria 822.9.1 How to set bin size 822.9.2 Flow pattern selection 852.9.3 Inlets and outlets 852.9.4 Inserts 892.9.5 Cylinder geometry 912.9.6 Materials of construction 922.9.7 Type of feeder and valve 932.9.8 Safety and environmental considerations 93P1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32CONTENTS vii2.10 Operational aspects 932.10.1 No ow or erratic ow 942.10.2 Flow rate problems 942.10.3 Particle segregation 942.10.4 Excess stagnant material 952.10.5 Structural concerns 952.10.6 Process problems 972.10.7 Abrasive wear and attrition 972.10.8 Feeder problems 98References 983 Silo and hopper design for strength 99J. MICHAEL ROTTER3.1 Introduction 993.2 Why pressures in silos matter 993.2.1 General 993.2.2 Classications of silos 1013.2.3 Metal and concrete silos 1023.3 Pressures in silos: basic theory 1033.3.1 Early studies 1033.3.2 Janssen silo pressure theory for vertical walls 1033.3.3 The lateral pressure ratio K 1063.3.4 Pressures in hoppers 1073.3.5 Simple structural concepts for cylinders 1103.3.6 Variability of the properties of stored solids 1133.4 Pressure changes during discharge of solids (emptying) 1143.4.1 First discoveries and explanations 1143.4.2 A better understanding 1163.4.3 Pressure observations during emptying 1173.4.4 The importance of ow patterns duringdischarge 1223.4.5 Eccentric discharge and its consequences 1243.5 Structural damage and its causes 1253.5.1 Introduction 1253.5.2 Steel and aluminium silos 1253.5.3 Concrete silos 1293.6 Design situations 1313.7 Concluding remarks 132Acknowledgements 132References 1324 Pneumatic conveying 135DAVID MILLS AND MARK JONES4.1 Introduction 1354.1.1 System exibility 135P1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32viii CONTENTS4.1.2 Industries and materials 1364.1.3 Modes of conveying 1364.2 Conveying system types 1374.2.1 Open systems 1384.2.2 Positive pressure systems 1384.2.3 Negative pressure (vacuum) systems 1384.2.4 Staged systems 1404.2.5 Shared negative and positive pressure systems 1404.2.6 Dual vacuum and positive pressure systems 1414.2.7 Batch conveying systems 1414.2.8 Mobile systems 1444.2.9 Closed systems 1454.2.10 Innovatory systems 1464.3 System components 1484.3.1 Pipeline feeding devices 1494.3.2 Gassolid separation 1574.3.3 Air supply 1594.3.4 Air compression effects 1624.3.5 Power requirements 1634.3.6 Pipelines and valves 1644.4 Conveying capability 1704.4.1 Pipeline bore 1714.4.2 Conveying distance 1714.4.3 Pressure 1714.4.4 Conveying air velocity 1714.4.5 Particle velocity 1724.4.6 Material properties 1724.4.7 Dense phase conveying 1724.4.8 Sliding bed ow 1734.4.9 Plug ow 1754.4.10 Dilute phase conveying 1764.5 Conveying system design 1784.5.1 Conveying air velocity 1794.5.2 Compressor specication 1804.5.3 Solids loading ratio 1804.5.4 The air only datum 1814.5.5 Acceleration pressure drop 1824.5.6 Scaling parameters 1824.5.7 Scaling model 1834.5.8 Scaling procedure 1864.6 Troubleshooting 1874.6.1 Material ow rate problems 1874.6.2 Pipeline blockage 1874.6.3 Conveying limits 1884.6.4 Air leakage 190P1: SFK/RPW P2: SFK/RPW QC: SFK/RPW T1: SFKBLUK141-McGlinchey.cls December 21, 2007 21:32CONTENTS ix4.6.5 Performance monitoring 1914.6.6 System optimising 1924.6.7 Erosive wear 1934.6.8 Particle degradation 195References 196Nomenclature 1965 Screw conveyors 197LYN BATES5.1 Introduction 1975.2 Classes of screw equipment 1995.3 Standard screw conveyor features 2015.4 The many operating benets of screw conveyors 2035.5 General limitations of screw conveyors 2045.6 Screw conveyor capacity 2055.6.1 The effect of machine inclination 206

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