Forsthoffer's Rotating Equipment Handbooks, Vol. 1: Fundamentals of Rotating Equipment (World Pumps) PDF
Preview Forsthoffer's Rotating Equipment Handbooks, Vol. 1: Fundamentals of Rotating Equipment (World Pumps)
Forsthoffer's Rotating Equipment Handbooks This page intentionally left blank Forsthoffer's Rotating Equipment Handbooks Volume 1: Principles of Rotating Equipment W E (Bill) Forsthoffer President, Forsthoffer Associates Washington Crossing, PA, USA ELSEVIER UK Elsevier Ltd, The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK USA Elsevier Inc, 360 Park Avenue South, New York, NY 10010-1710, USA JAPAN Elsevier Japan, Tsunashima Building Annex, 3-20-12 Yushima, Bunkyo-ku, Tokyo 113, Japan Copyright © 2005 W E Forsthoffer. Published by Elsevier Ltd. All rights reserved. ISBN 1-85617-467-0 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without permission in writing from the publishers. British Library Cataloguing in Publication Data A CIP Catalogue record for this book is available from the British Library No responsibility is assumed by the Author or Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Published by Elsevier Advanced Technology, The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK Tel: +44(0) 1865 843000 Fax: +44(0) 1865 843971 Typeset by Land & Unwin Ltd., Northamptonshire Printed and bound in Great Britain by MPG Books Ltd, Bodmin, Cornwall Contents Preface Acknowledgements About the author xni XV xvii 1 Rotating equipment overview Introduction Definition of rotating equipment Classifications of rotating equipment Site equipment examples Performance and mechanical design similarities The equipment 'train' or 'unit' Important fijndamentals I 2 3 4 6 8 9 2 Compressor characteristics Introduction Positive displacement compressors Actual volume, standard volume and mass flow Dynamic compressors 13 13 15 17 20 3 Operation of a compressor in a system Introduction The definition of a process system System resistance curves The operating point 27 27 29 30 33 Contents A positive displacement compressor in the process system A dynamic compressor in the process system 4 Pump types and applications Definition of pump types Positive displacement pumps Dynamic pumps When to use positive displacement or centrifugal pumps 5 Pump performance data The pump curve The limits of the centrifugal pump curve Increasing head produced by a centrifugal pump 6 Centrifugal pump hydraulic disturbances Introduction Maintaining a liquid inside a pump Causes of damage Preventing hydraulic disturbances The project design phase Field operation 7 Pump mechanical design Introduction Basic elements of centrihgal pumps Volutes Wear rings Impellers Bearings Anti-friction bearings Hydrodynamic bearings Balancing devices Shaft and key stress 34 34 37 37 40 45 52 55 55 60 63 65 65 66 73 75 75 83 89 89 89 90 93 93 96 99 102 104 106 vi Contents 8 Mechanical seals Introduction Function of mechanical seals The seal system Controlling flush flow to the seal Examining some causes of seal failures Seal configurations Flush system types Auxiliary stuffing box and flush plans 9 Compressor types and applications Introduction Positive displacement compressors Dynamic compressors 10 The concept of fluid head Introduction Definition Paths of compression The different types of gas head Dynamic compressor curves format 11 Performance relationships Introduction Satisfjring the objective Gas characteristics Compression head Impeller types and specific speed Efficiency Horsepower The Fan Laws 12 Surge (stall) and stonewall Introduction Surge facts The limits of the curve 109 109 110 112 113 114 115 118 124 127 127 129 135 143 143 144 149 149 152 153 153 154 155 157 157 160 161 162 163 163 165 167 Contents What causes surge What causes stonewall (choke) 13 The effect of a gas density change Introduction The factors involved The effect on turbo-compressor pressure ratio The effect on the compressor head The effect on system resistance The effect on turbo-compressor flow rate The effect on power 14 Turbo-compressor mechanical design overview Introduction The casing The inlet guide vanes The rotor Diaphragms Inter-stage seals Shaft end seals Journal bearings Thrust bearings 15 Radial bearing design Introduction Anti-friction bearings Hydrodynamic bearings Hydrodynamic bearing types Condition monitoring Vibration instabilities 16 Rotor axial (thrust) forces Introduction The hydrodynamic thrust bearing Impeller thrust forces Rotor thrust balance Thrust condition monitoring 168 171 175 175 177 178 178 181 181 182 185 185 187 188 189 190 191 192 195 196 201 201 202 2 04 206 2 09 21 1 217 217 218 222 223 225 ... . 3 V l l l mmmmmmmmmammmmmmmmmmmmmK^^ Contents 17 Compressor seal system overview and types 229 Introduction 229 The supply system 233 The seal housing system 234 Seal supply systems 241 Seal supply system summary 248 Seal liquid leakage system 249 18 Reciprocating compressors major component functions 251 Introduction 251 Frame and running gear 252 Cylinder distance piece 254 Piston rod packing 255 Cylinder and liner 256 Reciprocating compressor cylinder valves 257 Piston assembly 259 Pulsation dampeners 261 Cylinder and packing lubricators 262 CooHng system 263 19 Flexible coupling design, installation and operation 265 Introduction 265 The coupling function 265 Types 266 The coupling system 274 Coupling installation and removal 277 Enclosed coupling guards 280 Field retrofits from lubricated to dry couplings 281 20 Steam turbine function and types 283 Introduction 283 Steam turbine types 287 Steam turbine applications 292 21 Steam turbine performance 295 Steam turbine performance characteristics 295 IX Contents Steam conditions 296 Theoretical steam rate 299 Actual steam rate 300 Turbine efficiency 300 Why steam turbines are not performance tested 301 Performance curves 303 22 Steam turbine mechanical design overview 307 Introduction 307 Steam turbine casings 308 Throttle valves 311 Nozzle ring 311 Rotor 313 Nozzle/diaphragm 320 Shaft end seals 320 Bearings 323 23 Steam turbine inlet steam regulation 325 Introduction 325 Requirements 326 Single valve design and admission path 327 Multi-valve design and admission path 329 24 Steam turbine control/protection systems 337 Introduction 337 Total train control and protection objectives 338 Control 340 Protection 349 25 Steam turbine operation 355 Introduction 355 Safety and reliability considerations 356 Pre start-up considerations 359 Steady state operation 365 Shutdown and post shutdown 368 Single stage turbine guidelines 370 wmaammmmmmmmmmm^ Contents 26 Gas turbine types and applications 379 Introduction 379 Comparison to a steam turbine 380 Comparison to an automotive engine 381 Building a gas turbine 382 History of gas turbine development 384 Gas turbine classifications 385 Classification by design type 385 The number of gas turbine shafiis 390 Gas turbine drive configurations 392 Gas turbine cycles 392 27 Gas turbine performance 395 Introduction 395 Gas turbine ISO conditions 398 Site rating correction factors 399 The effect of firing temperature on power and efficiency 406 28 Gas turbine mechanical design 407 Introduction 407 Major component assemblies 407 Air compressor section 409 Combuster design 414 Power turbine design 419 29 Gas turbine support systems 425 Introduction 425 Types of support systems by classification 428 Accessory gearbox 437 30 Gas turbine control and protection 439 Introduction - total train control and protection objectives 439 Start-up and shutdown sequencing 443 Gas turbine control 445 Protection systems 454 Contents 31 Lubrication system overview and types Introduction Types of lubrication systems Arrangement options 455 455 455 465 32 Monitoring reliability and component condition 469 Introduction The major machinery components Specific machinery components and system monitoring parameters and their limits The rotor Radial bearings Thrust bearings Seals Auxiliary systems Predictive maintenance (PDM) techniques Conversion to Metric System Index 469 476 478 478 478 480 481 481 482 485 497 XII Preface This series has evolved from my personal experience over the last 40 years with the design, selection, testing, start-up and condition monitoring of rotating equipment. Most of the concept figures were originally written on a blackboard or whiteboard during a training session and on a spare piece of paper or I beam during a start-up or a problem solving plant visit. My entire career has been devoted to this interesting and important field. Then and now more than ever, the cost of rotating equipment downtime can severely limit revenue and profits. A large process unit today can produce daily revenues in excess of 5 million US dollars. And yet, the operators, millwrights and engineers responsible for the safety and reliability of this equipment have not been afforded the opportunity to learn the design basis for this equipment in practical terms. I have also observed in the last ten years or so, that the number of experienced personnel in this field is diminishing rapidly. Therefore the series objective is to present, in User friendly (easy to access), practical terms (using familiar analogies), the key facts concerning rotating equipment design basis, operation, maintenance, installation and condition monitoring to enable the reader (engineer, operator and millwright) to: • Understand the effect of process & environmental changes on equipment operation, maintenance and reliability • Condition monitor equipment on a component basis to optimize up-time, mean time between failure (MTBF) and mean time to repair (MTTR) • Select, audit and test the equipment that will produce highest safety and reliability in the field for the lowest life cycle cost. The hope is that the knowledge contained in this series will enable plant operations, maintenance and engineering personnel to easily access the material that will allow them to present their recommendations to XIII Preface mmmmmmmmmmmmmm^^ management to solve existing costly problems and produce new projects of optimum reliability. This volume, Principles of Rotating Equipment, is an overview of the main types of rotating machinery in industry (pumps, compressors, turbines and auxiliary systems). Each equipment type is presented with a practical emphasis on the design basis for each major component and covers such aspects as performance parameters and field monitoring, system dynamics, surge control, vibration, bearing, seal, auxiliary system design and condition monitoring of all major components and systems. XIV
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