Pumping machinery theory and practice

PUMPING

MACHINERY THEORY

AND PRACTICE

PUMPING

MACHINERY THEORY

AND PRACTICE

Hassan M. Badr

Wael H. Ahmed

King Fahd University of Petroleum and Minerals

Saudi Arabia

This edition first published 2015

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Library of Congress Cataloging-in-Publication Data

Badr, Hassan M.

Pumping machinery theory and practice / Hassan M. Badr, Wael H. Ahmed.

pages cm

Includes bibliographical references and index.

ISBN 978-1-118-93208-7 (hardback)

1. Pumping machinery. I. Ahmed, Wael H. II. Title.

TJ900.B193 2015

621.6–dc23

2014031896

A catalogue record for this book is available from the British Library.

Set in 10/12pt Times by SPi Publisher Services, Pondicherry, India

1 2015

To my parents, my dear wife and my children

Contents

Preface xi

Nomenclature xiii

1 Essentials of Fluid Mechanics 1

1.1 Kinematics of Fluid Flow 1

1.2 Conservation Principles 4

1.3 Some Important Applications 8

1.4 Dimensionless Numbers 12

1.5 Laminar and Turbulent Flows 12

1.6 Flow Separation 13

1.7 Cavitation 13

1.8 Friction Losses in Pipes and Pipe Fittings 14

References 21

2 Introduction and Basic Considerations 29

2.1 Introduction 29

2.2 Basic Definitions and Terminology 37

2.3 Determination of Flow Rate in a Pumping System 45

2.4 Operation of Pumps in Parallel and in Series 51

2.5 Similitude Applied to Centrifugal and Axial Flow Pumps 55

2.6 Flow Rate Control in Dynamic Pump Systems 62

2.7 Pump Specific Speed 65

References 72

3 Fundamentals of Energy Transfer in Centrifugal Pumps 81

3.1 Main Components of the Centrifugal Pump 81

3.2 Energy Transfer from the Pump Rotor to the Fluid 88

3.3 Theoretical Characteristic Curves 93

3.4 Deviation from Theoretical Characteristics 99

3.5 Leakage Losses 105

3.6 Mechanical Losses 106

3.7 Relationship between the Overall Efficiency and Other Efficiencies 111

3.8 Flow Rate Control in Pumping Systems 118

References 126

4 Axial and Radial Thrusts in Centrifugal Pumps 133

4.1 Introduction 133

4.2 Axial Thrust 133

4.3 Methods of Balancing the Axial Thrust 135

4.4 Radial Thrust 144

References 153

5 Common Problems in Centrifugal Pumps 159

5.1 Introduction 159

5.2 Cavitation 160

5.3 Mechanism of Cavitation Erosion 179

5.4 Solid Particle Erosion 180

5.5 Pump Surge 180

5.6 Operation at Other Than the Normal Capacity 183

5.7 Temperature Rise of Pumped Fluid 186

5.8 Change of Pump Performance with Fluid Viscosity 189

5.9 Rotating Stall in Centrifugal Pumps 190

5.10 Pump Vibration 191

5.11 Vibration Measurements 193

5.12 Vibration Signal Analysis 194

References 198

6 Axial Flow Pumps 205

6.1 Introduction 205

6.2 Definitions and General Considerations 205

6.3 Pump Theoretical Head and the Mean Effective Radius 210

6.4 Performance Characteristics of Axial-Flow Pumps 212

6.5 Axial Thrust in Axial Flow Pumps 213

6.6 Flow Rate Control in Axial Flow Pumps 214

References 218

7 Displacement Pumps 221

7.1 Introduction 221

7.2 Reciprocating Pumps 222

7.3 Pressure Variation during Suction and Delivery Strokes 225

7.4 Use of Air Vessels in Reciprocating Pump Systems 230

7.5 Performance Characteristics of Reciprocating Pumps 232

7.6 Flow Rate Control 234

7.7 Rotary Pumps 242

References 251

viii Contents

8 Introduction to Fans and Compressors 255

8.1 Introduction 255

8.2 Centrifugal Fans 256

8.3 Some Basic Concepts of High Speed Flow 262

8.4 Introduction to Centrifugal Compressors and Basic Considerations 272

8.5 Some Inlet Design Considerations 274

8.6 One-Dimensional Flow Analysis 276

8.7 Effect of Circulatory Flow (Slip) 279

8.8 Pressure Rise and Efficiencies 284

8.9 Sources of Losses in Centrifugal Compressors 286

8.10 Compressor Performance Characteristics 287

8.11 Compressor Surge 288

8.12 Choking in Centrifugal Compressors 291

8.13 Flow Rate Control in Centrifugal Compressors 293

References 299

9 Multiphase Flow Pumping 305

9.1 Introduction 305

9.2 Multiphase Flow through Centrifugal Pumps 333

9.3 Multiphase Pumping for the Oil and Gas Industry 340

9.4 Airlift Pump: an Example of Non-Conventional Pumping 345

References 353

10 Pump Selection Guidelines 357

10.1 Introduction 357

10.2 Bases of Pump Selection 358

10.3 Selection Based on Type of Pumped Fluid 358

10.4 Selection Based on Operating Condition 359

10.5 Selection Based on Reliability and Maintainability 361

10.6 Selection Based on Initial and Operating Cost 362

10.7 Other Factors Affecting Pump Selection 362

References 363

Index 365

Contents ix

Preface

Energy consumption in pumping systems accounts for approximately 20% of the world’s

electrical energy demand. Moreover, the operational cost of pumping machinery far outweighs

their capital cost. Accordingly, engineers strive for optimum equipment performance for

achieving economic operation. A thorough understanding of the components and principles

of operation of these machines will provide an opportunity to dramatically reduce energy, oper￾ational and maintenance costs. Reducing energy consumption will also complement the current

thrust towards protecting our environment.

This book is intended to be a basic reference on theoretical foundation and applications of

various types of pumping machinery. In view of the great importance of pumps and compres￾sors in almost every engineering system, this book presents the fundamental concepts under￾lying the flow processes taking place in these machines and the transformation of mechanical

energy into fluid power. Special emphasis is given to basic theoretical formulation and design

considerations of pumps and compressors in addition to improving problem-solving skills. This

is achieved through the presentation of solved examples of applied nature using analytical

means and/or basic engineering practices.

The book consists of ten chapters covering two main themes: the first smoothly introduces

the essential terminology, basic principles, design considerations, and operational-type pro￾blems in pumping machinery. This part is supported by a good number of worked examples

plus problems at the end of each chapter for the benefit of senior undergraduate students and

junior engineers. This is considered a key feature of this book because other books in this area

rarely provide enough worked problems and exercises. The second theme focuses on advanced

topic such as two-phase flow pumping systems targeting practicing field engineers and intro￾ductory research scientists.

The authors wish to acknowledge their students’ encouragement to write this book. The idea

was initiated by the first author after searching for a good textbook for an undergraduate course

in pumping machinery that he has been teaching for over 20 years. The absence of a suitable

textbook demanded the preparation of a set of course notes to help the students to a better

understanding of the subject. The support received from King Fahd University of Petroleum

& Minerals under Grant # IN111025 for the preparation of this textbook is greatly appreciated.

Nomenclature

A area

b vane width

BP brake power

C speed of sound

Cc contraction coefficient

CH head coefficient

CP power coefficient

CQ flow coefficient

D impeller diameter

f friction coefficient

g gravitational acceleration

h enthalpy

hss static suction head

hsd static delivery head

hs suction head

hd delivery head

H pump total head

H angular momentum

I rotational enthalpy

k specific heat ratio

K loss coefficient for pipe fittings

L length of connecting rod

m

mass flow rate

M Mach number

M moment

ns specific speed in SI

Ns specific speed in the American system

NPSH net positive suction head