Turbine Steam Path, Volume IIIa Mechanical Design and Manufacture

385 Pages·2001·17.809 MB·English

by  William P. Sanders

TURBINE
STEAM PATH
MECHANICAL DESIGN AND
MANUFACTURE
Volume Ilia
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TURBINE
STEAM PATH
MECHANICAL DESIGN AND
MANUFACTURE
Volume Ilia
William R Sanders, R Eng.
PennWelr
Copyright © 2004 by PennWell Corporation
1421 S. Sheridan Road
P.O. Box 1260
Tulsa, OK 74101
Managing Editor: Kirk Bjornsgaard
Production Editor: Sue Rhodes Dodd
Cover and Book Design: Robin Remaley
Library of Congress Cataloging-in-Publication Data
Sanders, William P.
Turbine Steam Path Mechanical Design and Manufacture
Volume Ilia/William P. Sanders, P.E.
p. cm.
q.cm
Includes index
ISBN 1-59370-009-1
All rights reserved. No part of this book may be reproduced, stored in a
retrieval system, or transcribed in any form or by any means, electronic
or mechanical including photocopying or recording, without the prior
written permission of the publisher.
Printed in the United States of America
1 2 3 45 08 07 06 05 04
TABLE OF CONTENTS
Foreword x
Preface xi
Acknowledgments xvii
Author's Note xviii
1 The Basic Considerations of
Thermodynamic Design 1
Introduction 1
The Thermal Design Process 3
The process of defining the turbine itself 3
The basic heat balance 5
Other information from the heat balance 22
Section and Stage Energy 26
The Design Philosophy and Specification 28
Stage Selection 31
State-Line Efficiency 38
The Velocity (Vector) Diagrams 42
Two-dimensional considerations (pure impulse) 43
Two-dimensional considerations (with high reaction) 49
Example 1 (the pure impulse stage) 50
Example 2 (a 50% reaction stage) 52
Steam Path Sizing and Arrangement 58
V
Turbine Steam Path Mechanical Design and Manufacture—Volume Ilia
Radial Pressure Gradient 6S
Stage Construction Details 67
Feed Water Heating Trains <S9
Flow Splitting and Steam Extraction 77
Double-flow, high-pressure sections 79
an
Double-flow control stages in the high-pressure section
Extraction of partially expanded steam from
the high-pressure section 81
Extraction from high-pressure/reheat double-flow sections .. 82
Low-pressure extractions from multi-flow sections 88
Possible low-pressure extraction configurations 91
References 99
2 The Turbine Steam Path Mechanical
Design Process 101
Introduction 101
The Mechanical Design Process 102
Information required from the thermal design 104
Mechanical considerations 110
Section Arrangement 115
The Major Components of the Steam Path 118
The Casings 118
The Diaphragms and Stationary Blade Rows 120
Stationary vane design 1?1
The nozzle plate 1??
The Rotors 1??
Rotor configuration 1?3
Technical considerations affecting rotor configuration 1?f>
The Rotating Blades 177
Selection of root form 128
vi
Contents
131
The Stage Hardware
ns
The Sealing System
ns
Seal system design
The Development of New Turbine Products or Processes..136
Development because of innovation 137
Solving an operational problem 141
The Final Design 143
Stage mechanical analysis 144
Design review 146
Manufacturing specification 147
3 Turbine Steam Path Performance and the
Factors Affecting it 149
Introduction 149
Steam Path Performance 1S1
Steam Path Availability 154
The cost of an outage 158
Interval between inspections 161
State-Line Efficiency 163
Efficiency and the design process 169
Stage leakage losses (Ah!) 171
The effect of leakage steam on
state-line efficiency ...178
Stage moisture loss (Ahni) 181
Stage leaving loss (Ahv) 184
Basic stage (aerodynamic) efficiency (Aha) 19?
Stage Efficiency Considerations 193
Blade Profile Geometry Group One Losses 196
Basic profile loss (£bl) 196
VII
Turbine Steam Path Mechanical Design and Manufacture—Volume Ilia
Stage Reynolds Number (/r) 70S
Stage discharge Mach Number (%m, Axm) 717
Discharge trailing edge (tail)(^6, Ayb] ??1
Suction surface trailing edge curvature(4^c, dxs) 776
Incidence and the inlet nose (#/) 779
Tie or Lacing Wire Losses ?^
Stage Geometric Factors Group Two Losses 7^6
Disc friction (%w) 7S7
Row aspect ratio (/ar) 740
Wall end, flare, and stage transition losses 74^
Pressure balance holes 747
Negative root reaction 748
Analysis of the Magnitude of Losses 7 so
The Cost of Damage Mechanisms 7S6
Loss due to steam leakage (bypassing of blade elements) 760
Loss due to steam leakage at shaft-end glands 761
Loss due to surface deposits , 761
Determination of losses due to profile damage, 767
Losses due to discharge area deformation, 76^
Influence of State-Line Efficiency on Heat Rate 763
References 269
4 Performance Testing 771
Introduction 771
The Purpose of Performance Testing 272
Test Costs and Economics 777
Classes of Performance Test 779
A test requested by the manufacturer 780
VIM
Contents
Performance test conducted to a specific test code for
guarantee purposes 781
Performance test to code standards conducted by
the owner 787
A test not conducted to a specific code 781
Test Objectives and Requirements 784
The Enthalpy Drop Test (EOT) 286
Conducting an EDT 786
Using the results of EDTs 790
Other Test Codes 791
The Test Schedule and Advanced Planning 793
The test conference 79S
Test Cycle Isolation 300
Test Instrumentation and Calibration 303
Combined uncertainties 303
Measurement of flow quantities 304
Measurement of power output 311
The boiler feed pump power 31S
Measurement of thermal energy 316
Measurement of steam quality 319
Measurement of time 370
Measurement of unt speed 370
Simplified ASMEPTC-6 Test 371
References 323
Appendix 325
Contents of Volume Illb 37S
IX