Marine Engineering Series Marine Auxiliary Machinery — 6th edition David W. Smith, CEng, MIMarE Pounder's Marine Diesel Engines — 6th edition C. T. Wilbur, CEng, MIMarE and D. A. Wight, BSc, CEng, MIMechE, FIMarE Marine Electrical Practice — 5th edition G. O. Watson, FIEE, FAIEE, FIMarE Marine and Offshore Corrosion K. A. Chandler, BSc, CEng, FIM, ARSM, FICorrT Marine and Offshore Pumping and Piping Systems J. Crawford, CEng, FIMarE Marine Steam Boilers — 4th edition J. H. Milton, CEng, FIMarE and Roy M. Leach, CEng, MIMechE, FIMarE Marine Steam Engines and Turbines — 4th edition S. C. McBirnie, CEng, FIMechE Merchant Ship Stability Alan Lester, Extra Master, BA(Hons), MRINA, MNI Marine Control Practice D.A. Taylor MSc, BSc, CEng, MIMarE, MRINA Senior Lecturer in Marine Technology, Hong Kong Polytechnic BUTTERWORTHS London—Boston—Durban—Singapore—Sydney—Toronto—Wellington All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the written permission of the copyright holder, application for which should be addressed to the Publishers. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. This book is sold subject to the Standard Conditions of Sale of Net Books and may not be re-sold in the UK below the net price given by the Publishers in their current price list. First published 1987 ©Butterworth & Co (Publishers) Ltd, 1987 British Library Cataloguing in Publication Data Taylor, D.A. Marine control practice.—(Marine engineering series) 1. Marine engineering I. Title II. Series 623.8'5 VM605 ISBN 0-408-01313-3 Library of Congress Cataloging-in-Publication Data Taylor, D. Α., M.Sc. Marine control practice. (Marine engineering series) Includes index. 1. Marine engines—Automatic control. I. Title. II. Series VM731.T36 1987 623.85 86-31737 ISBN O-408-01313-3 Phototypeset by Scribe Design, Gillingham, Kent Printed in England by Anchor-Brendon Ltd, Tiptree, Essex Preface Any engineer who has ever glanced at a thermometer or a pressure gauge knows the value of instrumentation and ultimately the control of the parameters that influence machinery operation. This book progressively deals with instrumentation, control theory, control equipment and the control systems to be found on board ship. The final chapter examines microprocessors and computer control applications. The text aims to cover the requirements for all the Certificates of Competency for Marine Engineers, including Extra First Class. Additional material and a deeper theoretical study is provided in areas where this is required for Higher Technical Certificates and Diplomas and Degree course syllabuses. The approach used is largely practical, dealing with actual equipment, its operation and mainte- nance. Where inevitably a mathematical approach is required this is combined with illustrations and examples to assist in understanding. Some advice on the use of this text for various courses is given at the end of Chapter 1. While primarily aimed at the marine engineer it is hoped this book will also be of use to those involved in offshore engineering and any mechanical engineering field where the operating environment is severe. Instrumentation and its associated control systems are increasing in use and application. The techniques used and the application of computerization are advancing the subject almost daily. The structured use of this text should enable the would-be, and the practising, marine engineer to understand what currently exists, and be prepared for what is to come. D.A. Taylor Acknowledgements I would like to thank the many firms, organizations and individuals who have provided me with assistance and material during the writing of this book; in particular, my colleague Mr Tony Naylor, whose expert comments on the electronics material in Chapter 4 were most helpful. To my many other colleagues and friends who have answered numerous queries and added their wealth of experience, I am most grateful. The following firms have provided information on their products for which I thank them: Advies-en Verkoopbureau voor Hamworthy Engineering Ltd, Drijfwerkonderdelen bv Combustion Division Alan Cobham Engineering Ltd Hamworthy Engineering Ltd, Pumps and APV Hall International Ltd Compressors Division ASEA Industries Ltd Haven Automation Ltd Autronica A.S. Haven Automation (H.K.) Ltd Babcock-Bristol Ltd Honeywell Controls Systems Ltd Bailey and Mackey Ltd Horiba Instruments Ltd Bell and Howell IMI Norgren Enots Ltd Benmar Η & Ρ Ltd ITT Conoflow VAF Bestobell Mobrey Kent Industrial Measurements Ltd Blakell (T.LG.D.) Ltd Kent Meters Ltd Blohm and Voss AG H. Maihak AG Bowden Controls Martonair Overseas Ltd Brown Brothers and Co. Ltd Moore Products Co. (U.K.) Ltd Capper Neill Controls Ltd MSW Control Instruments Ltd CGEE Alsthom Murray (Scientific Instruments) Ltd Commercial Hydraulics Ltd National Semiconductor Corporation Commercial Shearing Inc. Negretti and Zambra Ltd Danfoss Norcontrol Detector Electronics (U.K.) Ltd Normond Instruments Ltd Diamond Power Speciality Ltd Perolin Marine Draeger Manufacturing Régulateurs Europa Ltd Eagle Process Controls Ltd Reutlinger EIL Analytical Instruments G.L. Rexroth Ltd Fiber-optic AG Riley Corporation Foster Wheeler Power Products Ltd Rotork Controls Ltd Foxboro Far East Pte. Ltd Saab-Scania Graviner Ltd Salen and Wincander (H.K.) Ltd Saunders Valve Co. Ltd Telektron Ltd Seetru Ltd Vibro-meter S.A. Siemens Ltd Walton Engineering Co. Ltd Stal Refrigeration AB Westinghouse Brake and Signal Co. Ltd Stal Laval Turbin AB Westinghouse Electric Corporation, SMM Engineering Ltd Combustion Control Division Taylor Instruments Ltd Whessoe Systems and Controls Ltd George Taylor (Brass Founders) Ltd Young and Cunningham Ltd Telegan Ltd A special thank you goes to my wife, Jill, for her efforts on the word processor, which produced a readable manuscript from my untidy scribble. Introduction Marine engineers have always exercised control over the many items of machinery and equipment on board ship. Initially the controlling actions took place close to the equipment and were manual. Gradually, the use of remote operating devices led to controls being grouped at some convenient location. Automatic remote control ultimately followed with the location of equipment and the engineer in a machinery control room. The engineer's role then became more supervisory in nature, in that he monitored all the information provided and was often able to bring about corrective action without leaving the machinery control room. This monitoring role can now be undertaken by a computer-controlled system which will inform the engineer of any fault and detail the location. It therefore remains for the engineer to be available to remedy faults when they are brought to his notice by the monitoring system. Condition monitoring systems are now available that can give considerable warning of impending problems or the need for maintenance. This, nevertheless, still means that the engineer must undertake the repairs and maintenance, although he is now usually able to plan and coordinate his activities to gain the maximum benefits from his skills. There is also the fact that automatic control systems, no matter what the degree of sophistication, do occasionally break down. Manual operation by a skilled engineer is the ultimate fail-safe. It is interesting to note that some of the latest microp- rocessor-based equipment is now able to monitor itself during operation and also transfer to a spare circuit incorporated within the unit should a failure occur. The modern marine engineer, therefore, must first be fully trained and conversant with all the machinery he is required to'öperate. Secondly, he must be aware of the instrumenta- tion, control equipment and control systems used in conjunction with that machinery. It is to this second requirement that this book will address itself. A ship is designed to be an efficient, economic, cargo carrier which travels the oceans of the world. Its cargo may be determined by the ι 2 INTRODUCTION vessel design, its trade routes may be similarly restricted, but it must operate in an environment that is perhaps the most severe for any transport vehicle. Its operators must live on board for many weeks or months at a time with its equipment functioning all this time. Control systems have been developed to enable unattended operation of much of the machinery and equipment to ease the burden of the ship's staff and also reduce their numbers. Such methods of operation are, of course, carefully regulated by various authorities to ensure safe operation of the vessel. Each of these particular aspects will now be considered in further detail before examining the actual techniques employed in measurement, signal transmission and control. SHIPS The modern ship is a large complex vehicle which must be self-sustaining for long periods with a high degree of reliability. The marine engineer is responsible for the various systems which propel and operate the ship. To be precise, this means the machinery required for propulsion, steering, anchoring and ship securing, cargo handling, air conditioning, power generation and its distribution. All this equipment is, to varying degrees, automatically controlled. The particular type of vessel, e.g. oil tanker or refrigerated cargo vessel, may result in different systems. A marine engineer, however, is not confined to any one type of ship and must, therefore, be familiar with all kinds of systems on all types of ships. The principal division usually used by marine engineers relates to the type of propulsion of the vessel. The broad classes are steam, slow speed diesel and medium speed diesel. Associated with each of these propulsion units will be appropriate auxiliaries essential to the total plant. A steam turbine vessel will have high pressure, high temperature, water tube boilers, a condenser, the various pumps and other items in the closed feed system and various steam driven auxiliaries. Slow and medium speed diesels vary little beyond the main propulsion units. Diesel driven alternators and electrically operated auxiliaries are usual, together with exhaust gas driven boilers. Sufficient steam is often obtained to operate a turbo alternator when at sea. Three principal cargo carrying types of ship exist today, the general cargo vessel, the bulk carrier (liquid or solid) and the passenger vessel. The particular classification will bring with it appropriate systems for cargo handling and cargo conditioning. Cargo handling requirements would include pumping systems for bulk liquid carriers INTRODUCTION 3 or hatch operating and cargo lifting equipment for general cargo carriers. Cargo conditioning would relate to air conditioning and refrigeration systems for perishable cargoes and sometimes even heating systems. The passenger ship would have a requirement for reduced ship motions, using stabilizers for passenger comfort. Many ferries are fitted with controllable pitch propellers for improved manoeuvrability although the use of this device has occasionally been extended to almost all types of vessel. MANNING The numbers of personnel in the various departments of a ship have all been drastically reduced in recent years. One engineer is now considered capable of standing watch alone. He is considerably assisted by the increased amount of automatically controlled equipment and systems and the remote operating features provided. Much of his supervisory work can be accomplished within the machinery control room although occasional visual checks are to be recommended. It has not so far been considered necessary to carry instrument or electronic engineering specialists on board ships. The marine engineer has been expected to operate, maintain and repair his control equipment. This has led to simplified repair-by- replacement of modules in control units or systems owing to the high level of knowledge and skill that would be required for an actual component replacement or repair. Whatever maintenance method is adopted the need for adequate supplies of appropriate spares is evident. Specialized courses are now provided for marine engineers in order to update and further their knowledge of control systems and equipment. Marine Electronics Technicians courses are now provided by many marine colleges which will ultimately provide suitable personnel to maintain and service some of the specialized control equipment on board ship. It remains to be seen whether the marine engineer becomes more of a control equipment expert, at the expense of engineering knowledge, or whether a specialist control engineer is employed. ENVIRONMENT The marine environment and the ship's operating conditions present one of the most severe situations that any instrument or item of 4 INTRODUCTION Mist Rain Snow Hail I Solar ÷ / -w^v. í *,* - O -r a d i a t i on ^ ^ x » * * * · L/ Relative / N é1 humidity (%) 100 60120 „ c \VVVí ji+50 Wind ú \ë\\ Air l t ee mr a teu rc breeze —•storm } I \v\\ P ° ——^-^V ι / Vibration temperature^ wave speed up to 30 m/s/ /**^—' Forces due to 7Λ , Salinity of U-3° acceleration and 9A,e n£ he/L sea water 3 5% shock loads to 30-40° Figure 1.1 The marine environment equipment must accept (see Figure 1.1). Equipment that has been operating satisfactorily ashore may immediately fail when used on board ship. The rules of the various classification societies attempt to ensure that equipment is suitable for its purpose. The national authorities, e.g. Department of Transport, UK, or US Coastguard, USA, produce regulations which are mandatory for equipment fitted on their vessels or vessels entering their ports. Consideration will now be given to the various aspects of the environment and the motion of the vessel. Attitude and motion A ship is free to move with six degrees of freedom—three linear and three rotational, see Figure 1.2. The linear motions are known as surge, sway and heave. The rotational motions are roll, pitch and Figure 1.2 The six degrees of freedom