Marine engineering vol 3 part 18

Section 2 of this work deals with activating systems in a "cold" ship, and there are some inescapable parallels between auxiliaries for diesel plant and those for steam turbine plant as

MARINE ENGINEERING PRACTICE

Volume 2

Part 18

OPERATION OF MACHINERY IN MOTORSHIPS:

MAIN DIESELS, BOILERS AND AUXILIARY PLANT

by

A NORRIS, C.Eng., F.LMar.E.

THE INSTITUTE OF MARINE ENGINEERS

Published by THE INSTITUTE OF MARINE ENGINEERS

The Memorial Building,

76 Mark Lane,

London,

EC3R 7JN

Copyright © 1981THE INSTITUTE OF MARINE ENGINEERS

A charity registered in England and Wales

re-Enquiries should be addressed to:

THE INSTITUTE OF MARINE ENGINEERS

ISBN: 0900976 14 2

Printed in the UKbyArrowhead Books Ltd, Reading, RG30 1LZ

2.1.6 Air Conditioning Plant 42.1.7 Refrigerating Machinery 42.2 POWER PLANT SUPPORT SYSTEMS 42.2.1 Air Compressor Systems 62.2.2 Fuel Systems-High Viscosity Fuel Oil 72.2.2.1 Fuel Treatment 72.2.3 Lubricating Oil Systems 72.2.3.1 Purification, Lubricating Oil 72.2.4 Oil Transfer Pumps 72.2.5 Centrifugal Pumps 102.2.6 Sea Water Distillers 10

2.3.1 Boiler Management 122.3.2 Boiler Preparation 142.3.3 Burner Commissioning 142.3.3.1 Fuel Burning Precautions 162.3.4 Boiler Start-up 192.3.5 Boiler Shut-down and Securing 192.3.6 Steam and Exhaust Systems 19

iii

iv CONTENTS

2.3.7 Condensate Systems 212.3.8 Steam-using Plant 222.3.8.1 Turbo-generators 222.3.8.2 Cargo/Ballast Pumps 222.3.9 Composite Boilers 222.3.10 Waste Heat Recovery (W.H.R.) Systems 252.3.10.1 W.H.R Circuits 272.3.10.2 Commissioning W.H.R Systems 272.3.10.3 Normal Service Operation 272.3.10.4 Control of Output 292.3.10.5 Emergency Operation 302.3.10.6 Fire in W.H.R Units 312.3.11 Inert Gas Systems 34

4.1 5.1 6.14.1.1

4.1.2 6.1.14.1.3

4.1.44.2 K-GF 5.276J 6.2 RND4.2.1 5.2.1 6.2.14.2.1 5.2.1.1 6.2.1.14.2.1 6.2.1.24.2.1 5.2.1.2 6.2.1.5

Burmeister Doxford Sulzer

& WainSection 4 Section 5 Section 6

Piston Cooling 6.2.1.3Fuel Oil 4.2.1 5.2.1.3 6.2.1.4

MANOEUVRING AND

SECURING PLANT 4.3 5.3 6.3Bridge Control (U.M.S.)

6.3.1Starting Main Engine 5.3.1 6.3.2Quay or Basin Trial 4.3.1

Manoeuvring 4.3.2 5.3.2

Running -in Period 4.3.3

6.3.3Arrival in Port 4.3.4 5.3.3 6.3.4Port Inspections and Routines 4.3.5 6.3.5Crankcase Examination 4.3.6

Cylinders, Pistons and Rings 4.3.7

Maintenance Schedule 6.3.6

OPERA TION AT SEA 4.4 5.4 6.4Pressure and

Temperature Levels 4.4.1 5.4.1 6.4.1Normal Engine Operation 5.4.2 6.4.2Permissible Pressure and

Temperature Deviations 4.4.2

Watchkeeping Routine 5.4.2.1

Low Power Operations 5.4.2.2 6.4.5Running on Overload 6.4.3Running at Minimum Speed 6.4.4

Engirle Performance Trends 4.4.3

TROUBLE-SHOOTING 4.5 5.5

6.5Slow-down and Shut-down 4.5.1

Limits

Starting Failures 4.5.2 5.5.1 6.5.1Running Defects 4.5.3 5.5.2 6.5.2Cooling Oil Failure 4.5.4

Lubricating Oil Failure 4.5.5

Cooling Water Failure 4.5.6

Piston Ring Leakage 4.5.7

Scavenge Fires 4.5.8

6.5.3Crankcase Explosions 4.5.9

vi CONTENTS

Burmeister Doxford Sulzer

& WainSection 4 Section 5 Section 6

Isolating Cylinders 4.5.10 5.5.3 6.5.4Turbo-chargers 4.5.11 5.5.4 6.5.5LUBRICANTS AND

7.2.2 Constant Pressure Turbo-charging 1517.2.3 Running with Cylinders or Turbo-chargers Isolated 1547.2.4 Pressure and Temperature Levels 155

Those marked with an asterisk * are in the form of a check list whichindicates the correct order in which the various operations should be carriedout:

*FIG 2.1.6 Air conditioning plant

5

*FIG 2.1 7 Main refrigeration plant (direct expansion)

6TABLE2.2.3.1 Purifier trouble tracing 8TABLE2.2.5 Centrifugal pump defects IIFIG 2.2.6a) Single effect submerged tube hot water distiller 12

*FIG 2.2.6b) Starting distiller plant (with pumped brine discharge

and vacuum pump) 13

*FIG 2.2.6c) Stopping distiller plant 13

*FIG 2.3.2 Boiler preparation 15

*FIG 2.3.3 Burner commissioning 16

*FIG 2.3.3a) Commissioning fuel burning system 17TABLE2.3.3.1 Fuel-burning faults

18

*FIG 2.3.4 Raising steam in double pressure type boiler 20

*FIG 2.3.8.2 Steam turbine driven cargo/ballast pump 23FIG 2.3.9 Spanner boiler combustion system

24FIG 2.3.10.1 Waste heat recovery circuit 26

*FIG 2.3.10.2 Commissioning waste heat recovery systems

28

*FIG 2.3.11 Operating inert gas system 33TABLE3.3.1 Leading particulars of SD 14 class of ship 37FIG 3.3.2 Plan at floor plates ofSD 14 plant 38FIG 3.3.2a) Heat flow diagram for Sulzer type 5RND68 engine 39FIG 3.3.2b) Environmental protection plant 40TABLE3.5 Watchkeeping inspections in motorships 42

*FIG 3.7a) Emergency full astern (manual control)

50

*FIG 3.7b) Extinguishing scavenge fire 51

*FIG 3.7c) Loss of electrical power (black-out) 52TABLE4.1 B & W diesel engine data, type K -GF

53FIG 4.2 Cross-section of B & W K90GF engine 55FIG 4.2a) Shop test data for B & W 6K90GF engine 56TABLE4.2 B & W 7K90GF engine heat balance 57FIG 4.2b) Load diagram for B & W K90GF engine 58FIG 4.2.1a) B & W main cooling & lubrication systems 59FIG 4.2.1b) B & W fuel oil system 60

*FIG 4.3 Starting B & W main engine on diesel fuel 62TABLE4.4.1 Guidance alarm limits and measuring values for

B & W K-GF engines 67TABLE4.4.3 Interpretation of indicator card readings 70FIG 4.4.3 B & W engine performance trends 71TABLE4.5.1 Emergency slow-down li!ld shut-down limits 72TABLE4.5.2 Starting failures 73

vii

viii LIST OF ILLUSTRATIONS AND TABLES

TABLE 4.5.3 Running defects 75TABLE 4.5.10 Putting cylinders out of operation 81FIG 4.6.2a) b) B & W cylinder lubricants 85TABLE 5.1 Particulars of Doxford J series engines 88FIG 5.2 Doxford 76J engine 89TABLE 5.2 Power rating and balance of Doxford 76J4 engine 87FIG 5.2.1.1 Doxford 76J4 cooling water system 90

*FIG 5.3.1 Starting Doxford engine on diesel fuel 93TABLE 5.4.1 Doxford 76J4 operating and alarm pressures and

temperatures (full load conditions) 95TABLES 5.5.1.1 to 5.5.1.4 Starting failures 98-103TABLES 5.5.2.1 to 5.5.2.12 Running defects 104-114TABLE 5.5.3 Isolating cylinders 115FIG 6.1.1 Sulzer load diagram 117FIG 6.L1a) Sulzer power diagram 118TABLE 6.2 Sulzer power range, RND engines (1978) 116FIG 6.2 Cross section of Sulzer RND engine 119FIG 6.2.1.1 Sulzer jacket water cooling 121FIG 6.2.1.3 Sulzer piston cooling water system 122FIG 6.2.1.4 Sulzer fuel oil systems 123FIG 6.2.1.5 RND (M) lubricating oil systems 125FIG 6.3.1 Sulzer type SBC7 bridge control panel 127FIG 6.3.1a) Engine room control console 128FIG 6.3.2 Control system for Sulzer RND engine 129FIG 6.3.2a) Starting Sulzer engine after overhaul or long stoppage 130TABLE 6.4.1 Sulzer measuring values 133FIG 6.4.6 Evaluation of indicator diagrams 137TABLE 6.5.1 Starting failures 138TABLE 6.5.2 Running defects 142FIG 7.1 Fuel separation comparatives 147FIG 7.1a) Fuel injection viscosity/temperature curves 148TABLE 7.2.1 B & W type K/L-GFCA engine data (June 1980) 153FIG 7.2.1 B & W L90GFCA engine cross section 149FIG 7.2.1a) Performance curves for B & W L90GFC engine 151FIG 7.2.1b) Latest B & W fuel system [see also Fig 4.2.1b)] 152TABLE 7.2.2 Emergency running ofB & W 7L67GFC engine

on six cylinders 153TABLE 7.2.4 B & W types L-GFCA and K-GFCA engine

guidance alarm limits and service values withengine running steady 156TABLE 7.2.4a) B & W types L-GFCA and K-GFCA engine

guidance limits for emergency actions 157TABLE 7.4 Marine 2-stroke Sulzer engines 1980 160FIG 7.4.1 Cross-section of Sulzer type RLA90 engine 158FIG 7.4.1a) Performance curves of 6RLB90 Sulzer engine 159FIG 7.4.1b) Scavenge air flows in Sulzer RLA engines 160

This Part of Marine Engineering Practice Volume 2 deals with the operation of typical auxiliary plant and main engines in motor ships, and also with three specific main engines which are currently (1980) still in production Each type has been well proven at sea in many ships over a period of several years A separate section has been included for each engine since the operational procedures recommended by the designers are not identical It is important that these differences should be recognized and each engine should be operated strictly in accordance with the manufacturer's recommendations, rather than

by generalized methods, which may be suggested by precedent or by archaic practices which, however sound initially, may have accumulated in-built but unrecognized procedural flaws To widen further the range covered, some details are included of the machinery of one of the popular SD 14 ships (Shelter Deck 14000 d.w.t.) It is hoped that this wide cover will provide a ready source

of reference for operating the varied range of installations which will be encountered at sea for more than the next decade.

Section 2 of this work deals with activating systems in a "cold" ship, and there are some inescapable parallels between auxiliaries for diesel plant and those for steam turbine plant as described in Reference Ie) Repetition of comment in the Section has been avoided as much as possible in order that this Part is kept as self-contained as considered essential The operation of waste heat recovery plant has been treated in some detail as procedures are not covered in the prior literature generally available.

Wherever possible, information has been concentrated into "ladder" diagrams, in the form of a check list indicating a preferred order in which the various operations should be carried out These may be easily amended to suit particular installations or precise operating instructions.

The procedures, comments and recommendations are intended for general guidance only and are offered without prejudice: it is essential that for each particular plant any specific company instructions or manufacturer's requirements prevail over the methods here discussed.

C.S.R continuous service rating (see Clauses 4.1.2 and 6.1.1) Assigned

power, usually not more than 90% M.C.R., at which an engine can be operated continuously under normal sea conditions C.W cooling or circulating water.

cfm cubic feet per minute.

D/G diesel generator.

~p differential pressure.

F.D fan forced draught fan.

F.W.E finished with engines.

H.V.F high viscosity fuel.

I& 0 inlet and outlet.

J.C.W jacket cooling water.

Lube lubricating.

L.O lubricating oil.

M.C.R maximum continuous rating (see Clauses 4.1.2 and 6.1.1).

M.C.R = 100% rated power at 100% rated rev/min., i.e power which can be developed with engine ·and ship "as new" only in good weather.

M.E.P mean effective pressure is used mainly by engine manufacturers'

as, without an accurate torque meter, it cannot be calculated accurately on board ship M.E.P is worked out from the brake horsepower developed at the main engine coupling and for practical purposes may be considered as equal to the M.I.P x a coefficient based on the mechanical efficiency of the engine M.I.P mean indicated pressure is obtained from analysing indicator

diagrams and gives the average pressure applied to the piston during one stroke The M.I.P is then used to calculate the indicated horsepower being developed by the engine.

To obtain brake or shaft horsepower the indicated power is multiplied by an engine constant which varies with power and allows for the frictional losses in the engine.

N.P.S.H net positive suction head is the critical factor in pump system

design and is the pressure head available after deducting the pressure losses due to moving and accelerating the fluid into the pump cavity An adequate N.P.S.H is essential for all types of pump.

P.C piston cooling.

P.C.W piston cooling water.

x

S.A starting air.

S.B stuffing box.

S&D suction and discharge.

T.C turbo-charger.

V.M.S. unattended machinery space.

W.H.R waste heat recovery.

W.P working pressure.

ACKNOWLEDGEMENTS

The Author expresses his gratitude to Austin & Pickersgill, Ltd., (British Shipbuilders) for information provided on their SD 14 Class Ships, also to Burmeister& Wain Engineering Ltd., Doxford Engines Ltd., and Sulzer Bros.

(VK) Ltd., for making freely available their excellent Instruction Books and for their individual approval of the text relating to the specific engines discussed in Sections 4, 5 and 6.

Thanks are also due to Senior Econornisers Ltd., M&W Grazebrook Ltd., (for Spanner Boilers), and Alfa-Laval Co Ltd., for access to information required for the preparation of separate clauses of this work Individual thanks are also due to Mr J W Thomas, C.Eng, M.I.Mar.E., of the BP Tanker Company Limited who has kindly read the text and acted as Referee for content approval.

l GENERAL CONSIDERATIONS

1.1 GENERAL

Diesel engine ancillary systems-fuel, lubrication, coolants-are not as complex nor are their circuits so interdependent as for steam power plant Otherwise, the general comments made in Clause 1.1 of Reference Ie) on detailed information, corrective action in emergency, and starting up plant from the cold condition are applicable for diesel plant Also, the clauses in the same reference on "Standard Procedures" (1.2) and "Guidance Figures and Diagrams" (1.4) are relevant for diesel power plant, but are not reproduced in this text.

The Parts of "Marine Engineering Practice" listed as direct references in the Bibliography provide additional information to supplement that given in outline here In particular, Part 12 includes procedures for commissioning of auxiliaries, controls and instrumentation; Part 15 adds details on systems, boiler plant and emergencies which are also applicable for many motor ships; and Part 17 covers the essentials of typical main engines, their components, and principal supporting systems Where the subject or relationship is obvious from the context it is to be understood that, apart from the more essential points, cross references to these other Parts are omitted from this work to avoid possible tedious repetition.

1.2 PLANT DISCUSSED

All major designs of slow speed diesels cannot be covered in a work of this restricted length The makes of main engines discussed have thus been restricted to three, including the two at the top of the horsepower league table and the one British design now extant Since the operational procedures recommended by designers are not identical, a separate section has been included for each make; repetition has been avoided and comments made in one section will supplement those made in the others In deciding on the specific engine types to be discussed in some detail it was considered desirable not to select the very latest designs of the engines, but to cover well-proven and popular types still currently on order, in service in many ships now at sea, and likely to give many more years of service: the Burmeister & Wain K-GF, the Doxford 76J and the Sulzer RND engines satisfy these criteria Similar considerations also led to the inclusion in Section 3 of some details of auxiliary machinery in a typical ship of the successful SD 14 Class: main engine

1

operation in this typical ship is covered by Section 6, which is applicable to thewide power range of the Sulzer RND engine.

Auxiliary installations fall roughly into two categories, one with minimal or

no steam boiler plant, as in 2.1 and 2.2, with the other simple steam plant with

or without a turbo-generator taking steam from waste heat recovery plant atsea, as in 2.3.1 through to 2.3.11, covering the additional plant that may beencountered in large tankers and OHO ships In conjunction with Reference Id)all the machinery fitted in modern direct-drive motorships is now covered inoutline from the building through commissioning and sea trials to theoperational phase, except for maintenance procedures which have had to beexcluded for space considerations

Medium speed engines are also excluded since they are already well covered

by Volume 1 Part 3 of this series "Marine Medium Speed Diesel Engines"

It is hoped that this treatment will give a wide spread of cover suitable forgeneral guidance in operating many types of machinery installations

2 ACTIVATING SYSTEMS, COLD SHIP

2.1 COLD SHIP STARTING

The cold ship condition postulated is that where a ship is about to be prepared for leaving drydock and the shore facilities then supplied have to be replaced from ship's sources Some required procedures are similar for both steamships and motorships and many of those carried out for new ships are also relevant.

In all cases the starting procedures must be co-ordinated by the Chief Engineer Officer or a nominated deputy Desirably, check-off lists should be used to identify the actions required when starting the plant systems and components.

2 1.1 Starting Conditions

After a prolonged shut-down of plant, or when work has been carried out by repairers, an extensive check needs to be made on all systems for cleanliness and valve settings All machinery units which have been opened up must be thoroughly examined before closure Rotating machines should be barred round and electric motors megger-tested before starting Standard safety precautions must be observed at all times It is to be understood throughout that alarms and safety devices should be proven as each unit and system is commissioned, as discussed in Reference Id), Section 6.

2.1.2 Diesel Generator Systems

The emergency diesel generator should be tested, stopped and left in an immediate stand-by condition, and the 24 V battery supply system for alarms and emergency lighting must be available As soon as a cooling water source is available, one of the diesel generators should be started After a main set has been put on load the feeder breakers to auxiliary motors should be seen to be closed and a check made that auxiliary machinery, previously supplied from shore power, has restarted Thereafter, the principal ship and hotel services may be activated, e.g sea water and sanitary, fire and washdeck, potable water, and control air supply (where fitted).

2.1.3 Sea Water Services Systems

Sanitary system and refrigerator circulation supply should be transferred to

3

ship sources without delay Commissioning instructions for small pumps aregenerally:

• Open sea suction valves on sea chests and pumps' suction valves

• Vent selected suction strainer and casings of pumps for each service

• Start selected pump, either from local starter or from control console

• Open discharge valve of selected pumps to system

• Open overboard discharge and supply valves to heat exchangers, etc

• Ensure that heat exchangers are fully vented

• Open discharge valves on stand-by pumps and check auto-starter

2.1.4 Fire and Washdeck Systems

A fire and washdeck pump should be started as soon as power is available andnormally be kept running at all times to give an immediate hose supply inemergency The pump discharge valve should be gradually opened as thepressure builds up, and hydrants at the most remote and highest points of thesystem should be opened for sufficient time to expel all air The emergency firepump, installed outside the machinery spaces, should be proven as being ingood order In cold climates, precautions may have to be taken against frostdamage to the deck fire main

2.1.5 Bilge Systems

Two self-priming pumps must be available for connection to bilge pumpinglines and one large pump in the engine room, e.g a ballast pump, arranged totake a direct bilge suction in emergency Under all normal conditions bilges arepumped to the bilge water separator from whence the water effluent is led eitheroverboard at sea, or in port to a storage tank for later discharge more than 25miles from the coastline Oil is led to a waste oil tank Lloyd's Rules and adiagram of a typical arrangement are discussed in the March 1979 issue of

Marine Engineers Review.

2.1.6 Air Conditioning Plant

Figure 2.1.6 shows starting and stopping procedures for a typical plant

2.1.7 Refrigerating Machinery

Figure 2.1.7 shows compressor starting procedures Stopping is generally asgiven on Fig 2.1.6

2.2 POWER PLANT SUPPORT SYSTEMS

The essential work to commission the machinery installation must be related tothe complexity of the particular plant and the amount of disturbance to whichsystems or equipment have been exposed since they were last operating Atworst, the detailed procedures for individual units as set out in Section 6 ofReference Id) may have to be implemented to ensure plant reliability when theship goes to sea Since systems and components in individual ships, or classes

The compressors are generally arranged for automatic operation with onemachine running continually when manoeuvring, automatically loading andunloading on demand, but with automatic stopping and starting at sea Whenfirst starting, air and oil filters must be clean, pressure gauge valves crackedopen and, if pumping up an empty air receiver, the delivery valve should bethrottled until about 20 per cent of normal pressure is built up in the receiver.With manually controlled machines the drains must be opened beforestarting, coolers periodically drained during running periods, and drainsopened for two to three minutes before the machine is stopped to purgemoisture thoroughly from the unit before idle periods Air reservoirs should beregularly drained of moisture.

ACTIVATING SYSTEMS, COLD SHIPS 7

In control air systems the filter and drier must be kept functioning, and thedrain valves fitted at the lowest points on air distribution lines regularlyoperated Air lines must be kept free of oil or grease internally to avoid anexplosion hazard Safety valves provided on lines must be kept in workingorder

2.2.2 Fuel Systems-High Viscosity Fuel Oil

If fuel in bunkers or settling tanks has to be used soon after the power plant isactivated, the tank contents should be preheated to >38°C, over a 12 to 36-hour period It may be necessary to use shore-supplied steam, until steam isavailable from ship's plant Systems for specific main engines are shown inlater sections of this text

2.2.2.1 Fuel Treatment

This is discussed in Reference If) and in Trans.I.Mar.E Vol 90, Series A, Part

2 Purifiers used are now usually of the self-cleaning type Homogenizers arefitted in some ships and may present fewer maintenance problems thanpurifiers However, where homogenization is used fine filtration of fuel supply

to the engine may also be included

2.2.3 Lubricating Oil Systems

It is essential that all components should be scrupulously clean before anengine, or an auxiliary, is put into service See Reference Id), Clause 6.4.6.34

If the ship has been in port for some time the main lubricating oil charge willhave been pumped into the renovating tank When heating steam is availablethe tank contents should be heated, water drained off, and the purifier broughtinto service The oil charge should be circulated from the tank, through thepurifier at a temperature of 700 to 80°C, and back to the tank until the oil isclean Thereafter the oil may be returned to the drain tank

2.2.3.1 Purification, Lubricating Oil

The lubricating oil purifier should desirably be kept in continuous operationwhen the ship is on sea passages and a water wash should be used, whenpermissible (See 4.6.1, 2, 3) In view of the importance of correct operation

of purification plant each maker supplies comprehensive Instruction Books foruse with their products, e.g Table 2.2.3.1 gives extracts from the excellent

"Trouble Tracing" section of the Alfa-Laval publication for their MAP X typemachines, installed in so many ships now at sea

2.2.4 Oil Transfer Pumps

Electric motor-driven positive displacement rotary pumps, e.g of IMO type,are self-priming and used for oil transfer, fuel supply to main engine, andlubricating oil circulation duties, etc Bypass valves are usually provided foradjustment of pressure and capacity, but both discharge and suction valves

should be opened before the pump is started After starting, if such pumps donot build up adequate discharge pressure it may be due to:

• oil viscosity in suction lines too high, due to inadequate heating;

• excessive air leaks in valve glands, pump glands, or relief valve casing;

• vapour lock in (fuel) oil pipes due to excess heating;

• required suction lift being higher than designed

2.2.5 Centrifugal Pumps

These are used for nearly all water pumping duties and, in many ships, formain engine lubrication service, since the centrifugal pump characteristic ofincreased output on reduced viscosity is appropriate to the duty For bilge andballast duties, priming equipment of either integral type or from a central unit isrequired; this is usually a simple water ring air pump arrangement Startingprocedures are generally as given in 2.1.3 Typical pumps and pipingarrangements are discussed in the March 1979 issue of Marine Engineers Review.

In some ships chlorination plant is installed to deter marine growths in seawater pipe lines, components and fittings (see Reference Ie) p 19) Whenoperating in shallow waters the high injection valves should be in use for pumpsuctions to reduce the induction of sand or grit-laden water which would causeerosion and wear on pump casing wear rings and seals After leaving port, allpumps that have been in use with possibly aggressive water should be flushedthrough with clean water as soon as possible If pump output has to bethrottled this should be done by adjusting the discharge valve The suctionvalve must not be used, as control by this means could lead to cavitationdamage in the pump and erratic throughput

Because of the simple construction operating faults are rare, but ifencountered may, depending on pump type, duty and make, be as shown inTable 2.2.5

2.2.6 Sea Water Distillers

Jacket water heated plant is usually fitted in motorships This type, amongothers, is discussed in Trans.I.Mar.E 1976, Vol 88 "Sea Water Distillers" by

A Gilchrist, from which Fig 2.2.6a) is taken Commissioning and shut-downprocedures for older type plant provided with separate vacuum pumps andbrine pumps are shown in Fig 2.2.6b) and c) In some cases arrangements aremade for low pressure steam preheating as an alternative to the jacket waterheat input to allow boiler make-up feed, but not potable water, to be distilled inport; when so used the steam supply should be adjusted to give about 65° to70°C condensate drain temperature from the preheater

2.3 STEAM PLANT

Steam boilers are the most sensitive and easily damaged power plantcomponents and must be treated with great care Start-up and operating

boiler, should be explicitly followed and must prevail over any of the general comments made in this Section.

Excluding the few ships where only electric and/or thermal fluid heating systems (See Trans.I.Mar.E Vol 90 Series A, Part 3/7) are employed, there are many different grades of boiler plant installed in motorships (see References 2 and 4) These range from single small "package" or composite boilers to large, water tube boiler plants installed in oil tankers and in some bulk carriers Many smaller oil tankers and other ship types have one or more boilers of the double pressure type These provide, from a fired closed circuit water tube boiler primary section, high pressure saturated steam which is led through a heating coil in a steam/steam generator section to lower pressure steam for supply to external circuits Such boilers require handling methods common to many other types and manually controlled procedures are discussed below It will be appreciated that, as automatic controls for specific plants vary so much, they cannot be discussed in detail, but they may intervene

to carry out or supervise some or all of the operations mentioned.

This operation is free from hazard, but feed water and boiler watertreatment must be maintained to prevent internal deterioration or scaleformation Water level controllers must be kept operable to protectexternal steam using plant from water "carry-over" danger.

• If a boiler is isolated from the steam-using system it must be kept either inclosed dry storage with a suitable internal desiccant, completely full oftreated water, or under a low steam pressure preferably maintained by asteam-heated (simmering) coil

• Regular testing of boiler protective devices must be implemented asdiscussed in Reference 2 and Clause 2.3.4 of Reference Ie)

• Frequent comparison of drum-mounted and remote-reading water levelindicators: discrepancies between these have contributed to failuresbecause of overheating through shortage of water when a boiler was beingoil-fired If in doubt as to the true boiler water level, i.e whether a waterlevel indicator sight-glass is completely full or empty, when a unit is beingoil-fired the fires should be immediately extinguished until the true level isresolved

• Procedures should be predetermined and followed in the event of shortage

of water, bulging or fracture of plates or furnace, or bursting of watertubes In general, fires should be immediately extinguished by remotetripping of fuel supply valves; forced draught air pressure maintained ifthere is any risk of escaping steam entering the boiler room; steampressure relieved if metallic fractures seem possible; and boiler water levelmaintained, where practicable, until the boiler begins to cool down

• Regular operation of soot blowers, if these are fitted, when the boiler is onoil-fired operation The steam supply line must be thoroughly warmed anddrained before the blowers are used, the air/fuel ratio increasedthroughout the action, and blowers greased after use

• Immediate investigation of any high salinity alarms in condensatesystems, and elimination of any salt water or oil contamination of boilerfeed water system

• Periodical inspection and cleaning of boilers

• Safety precautions taken before entering a boiler connected to anotherboiler under steam

• Applicable procedures as suggested below

2.3.2 Boiler Preparation

Figure 2.3.2 shows initial procedures which are applicable to most types ofmedium or low steam pressure boilers in motorships Where a boiler is of thesmall package type using a rotary cup fuel burner, the steps relating to forceddraught fans and atomizer are not applicable

2.3.3 Burner Commissioning

With many small package boilers the automatic control sequence usuallyensures that the boiler fire is initially ignited from a gas or diesel oil supply, and

changed over to the usual fuel source when ignition is completed With goodmanagement, to facilitate subsequent starting from cold, the fuel system oflargeboilers will have been flushed through with diesel oil when the boiler was onlight duty immediately prior to being secured When burning such diesel fuel it

is essential for safety that only the correct (small) burner tip should be used

correct operational procedures must be adhered to rigidly.

Figure 2.3.3 shows burner commissioning procedures and Fig 2.3.3a) shows the preparation for the change-over to heavy fuel burning.

2.3.3.1 Fuel Burning Precautions

Complete ignition of fuel in the furnace is essential The burner flame, the smoke indicator and the funnel should be frequently observed With satisfactory combustion, the flame should appear incandescent with an orange shade at the flame tip, and a faint brownish haze should show at the funnel Table 2.3.3.1 shows some fuel-burning faults which may be encountered It is

ACTIVATING SYSTEMS, COLD SHIPS 19important that no unburnt fuel should be sprayed into the furnace nor heavysmoke produced To minimize explosion risks, the air purging of the furnacemust always be thorough before lighting off a burner after an unfired period.Never attempt to relight a fire from hot furnace brickwork-the ignitor or atorch must be used.

2.3.4 Boiler Start-up

Figure 2.3.4 shows procedures applicable for a double pressure type boiler Forboilers of the direct-fired, smoke tube type the steps on the left hand side of thefigure are relevant With Scotch boilers, circulation should be commenced assoon as the boiler gets warm, using the hydrokineter or a circulating pump, andworking pressure should not be raised in less than 12 hours (preferably 24hours) to reduce expansion stresses (Reference 4) Time required for otherboiler types will vary with construction and water content, but it is alwaysdesirable to heat through evenly and if necessary blow down some of thecontents to sea to displace cold water from the lowest part of the boiler shell, tominimize temperature differentials and thermal stresses in the pressure parts.See Reference Ie) for procedures for large, water tube boilers and testing ofprotective devices, and Reference 2 for alarm, logic and control systemsrelevant to modern auxiliary boilers

2.3.5 Boiler Shut-down and Securing

Although out of sequence here, this operation may have to be done normally atthe end of a voyage or in emergency For normal shut-down the suitableprocedure is:

• Carry out soot blowing, if permissible

• Change combustion control from automatic to manual

• Change fuel supply to diesel oil; shut steam off fuel heaters and traceheating

• Close burner supply valves and main fuel shut off valve

• Purge boiler furnaces with air for three to five minutes; stop forceddraught fan

• Close steam stop valves on boiler when pressure is reduced

• Drain boiler when it has cooled down or fill with treated water (seeReference 2)

2.3.6 Steam and Exhaust Systems

As an alternative to the steps shown on Fig 2.3.4, steam systems may bewarmed through as steam is being raised on the boiler by:

• opening steam range drains to bilge and to steam traps;

• opening steam line valves to the required services;

• cracking open boiler stop valve when drum pressure is 2 bar;

• throttling steam line drains as range warms through;

• opening boiler stop valve full (less tturn) before auxiliaries are started;

• closing steam line direct drains and steam trap bypasses on trapped lineswhen lines are hot

ACTIVATING SYSTEMS, COLD SHIPS 21The boiler water level must be maintained throughout and steam not supplied

to any auxiliary unit until arrangements have been made to condense theexhaust steam, e.g by circulating the auxiliary condenser

2.3.6.1 Oily Drains

Heating drains from fuel tanks, drain tanks and oil heaters are led through aninspection/observation tank before the clean condensate is allowed to return tothe feed water drain tank and from thence to the boiler During operation thesight-glasses of the observation tank must be frequently checked for oilindication; to avoid hazarding the boiler, any oil found must be immediatelydrained ofT, the source traced and leakage stopped The condensate filter,whether in a hotwell or in the feed pump discharge line (see Reference 4) must

be kept clean and condensate salinity checked as being less than say 4 p.p.m

2.3.7 Condensate Systems

These vary with the extent of steam plant installed, but are much simpler thansystems necessary for steam turbine plant In a motorship with steam deckmachinery and/or steam turbine driven cargo oil or ballast pumps thecomponents may include:

• Auxiliary Condenser.Waterboxes must be vented and the unit circulatedbefore steam machinery is used After leaving port, where aggressivecirculating water may have been in the system, the unit must be flushedout with clean sea water before shutting down Where a low vacuum airejector (125 mmHg, say) is fitted to assist exhaust flow and line drainage,

it must be used on heavy load as it also evacuates air and non-condensablegases from the shell This both maintains heat exchange efficiency andimproves feed water quality by partial deaeration When remotely locatedsteam machinery is first started, condensate surges may occur from watertrapped in exhaust pipes At this time, and when first started, the salinityindicator should be observed in case sea water contamination hasoccurred

• Hotwell or Feed Filter Tank. This receives the condensate and oily drainsafter they have passed through the observation tank Filter elements,which may be coke or towelling, must be kept clean and any water levelcontroller kept in working order Condensate temperature in the tankshould be kept high by avoiding undercooling in the condenser, as thisboth reduces air entrainment and contributes to boiler fuel economy

• Boiler Feed Water Pumps. These are now usually of the motor driven,multi-stage centrifugal type When filling a boiler and until the system isfully pressurized, it may be necessary to throttle the pump discharge valve

to avoid electric motor overloading

• Boiler Feed Water Heater. The waterboxes must be vented when firststarting The shell steam space must be regularly vented when the heater

is working to release air and non-condensable gases which would impair

heat transfer if allowed to accumulate Where the heating steam is fromauxiliary engine exhausts, the back pressure in the exhaust steam rangesmust be kept at the design figure to maintain a high exit feed watertemperature from the heater This saves the fuel which would be neededfor heating low temperature feed water in the boiler, improves boilercirculation, and reduces temperature differential stresses on the boiler andfittings

• Feed Water Treatment.Both this and boiler water condition treatment arediscussed in Reference Ie) Proprietary brands of chemical compoundsare in general use and, in motorships, are introduced into the boiler feedwater system

2.3.8 Steam-using Plant

Some ship systems, briefly discussed in Section 7 of Reference Ie), which arealso found in many motorships are: deck machinery, tank cleaning heater;stripping pumps; slop tank/cargo tank heating and auxiliary turbines

2.3.8.1 Turbo-generators

Machines operated on steam supplied from waste heat recovery systems at sea,and from oil-fired boilers at other times, are fitted in many motorships Suchunits are discussed in Reference Ib)

2.3.8.2 Cargo/Ballast Pumps

Steam turbine driven cargo and/or ballast pumps of large capacities are fitted

in many oil tankers and OBO ships Starting and stopping procedures for atypical unit are shown on Fig 2.3.8.2 Details of some operational aspects andproblems are given in Trans.I.Mar.E Vol 90, Series A, Part 7 of 7, and in theMarch 1979 issue ofMarine Engineers Review.

2.3.9 Composite Boilers

The Spanner "Swirlyflo" Exhaust Gas/Oil-Fired Composite Boiler is widelyused and typical of boiler plant installed for the combined duty Exhaust gasesfrom the main engine and the products of combustion from direct oil-firing,pass through heat exchange areas isolated one from the other but contained in

a common boiler shell Where steam is required for a turbo-generator, asuperheater is fitted in the bottom gas box A water level controller is providedand the boiler is fitted with a low water cut-out switch/alarm to safeguardagainst dangerous low water conditions when oil firing, by shutting down theoil burner if the water level falls 75 mm below normal

A) Starting up the boiler

The makers recommend that with electrical supply switched on to the burnercontrols and the oil burner:

• Procedures 10, 13,9, 18, 14, 15, 16, as given on the left hand steps of Fig2.3.2 (relevant to larger boilers) be carried out

• The boiler be filled to normal level (tglass) when the feed control valvewill automatically close and the panel indicating light be extinguished

• The oil burner be lit and when water level nears the top of the gauge glass,due to expansion, the initial level should be restored by draining ofT waterthrough the scum valve

ACTIVATING SYSTEMS, COLD SHIPS 25

• The air cock should be closed when steam issues freely and the boiler pressure gauge reads 0.4 bar

• The steam stop valve be opened to supply services.

For initial starting the oil burner may be manually controlled, but is normally on automatic control as shown on Fig 2.3.9.

B) Operation

The pH value of the boiler feed water should be kept between 8 and 9 and the boiler density less than 300 p.p.m but, if water samples show a heavy concentration of suspended matter, short blow-downs of 20 seconds duration should be given until the sludge content is seen to be reduced The boiler should

be blown down when the oil burner is operating, the water level lowered and then restored to prove the functioning of the low water cut-out and the oil burner start-up equipment The boiler scum valve should also be operated at this time to keep the water level clear from floating scum.

Tubes in the exhaust gas section of the boiler should be brushed through at about six-monthly intervals, and those in the oil-burning section periodically examined and cleaned as necessary with a wire bristle brush With correct feed water treatment, blow-down procedures and sludge contents in water samples

at a stable level, it should not be necessary to wash out the water side of the boilermore than once every three or four months.

Fuel burner components and igniter electrodes should be cleaned weekly and the furnace examined to ensure that there are no excess carbon deposits The main engine may be kept in operation with the boiler dry and the gases passing through the exhaust gas section If this is to be done for a prolonged period it is advisable to allow a current of air to flow through the boiler by removing manhole, sighthole and mudhole covers If refilling a hot boiler the main engine speed should be reduced to SLOW for half an hour and the feed water supplied be as hot as possible; thereafter the main engine may be brought

up to power over a similar period.

2.3.10 Waste Heat Recovery Systems (W.H.R.)

Generation of electric power from a steam turbo-generator and the supply of saturated steam to heating services by exhaust gas heat recovery systems is effected in many ships The type of W.H.R unit mainly fitted nowadays for medium to large outputs is made up of horizontal extended surface steel tubes, force-circulated with water taken from an oil fired boiler and returned as water/vapour emulsion The boiler is fired whenever the demand for steam exceeds that available from exhaust gas heating Additional heat extraction from the exhaust gases can be effected by adding an economizer section to the unit in plants where the arrangement permits the supply of cooled circulating water or feed water at the economizer inlet Similar results, but with some disadvantages, can be obtained by producing low pressure steam from a separate heat exchange unit at the tail end of the gas stream.

ACTIVATING SYSTEMS, COLD SHIPS 27

2.3.10.1 W.H.R Circuits

Figure 2.3.10.1 shows a widely-used simple circuit developed by the authorand originally marketed by Senior Economisers Ltd Related designs to extracteven more heat from the exhaust gases had additional heat exchangersinterposed in the circulating water circuit to produce steam for heating services

at a lower pressure than the steam supplied to the turbo-generator

Other circuits have also been widely used, e.g admixture of boiler feed waterand circulating water at the economizer inlet; a feed heating only economizersection as arranged for steam-ships (but which introduces a danger of waterhammer in the elements when used in motorships); and a steam generatorsection only without an economizer in large powered ships where adequatesteam output could be obtained without W.H.R system complication

2.3.10.2 Commissioning W.H.R Systems

Figure 2.3.10.2 shows procedures which are suitable for systems similar tothose of Fig 2.3.10.1 if they have been drained or depressurized -

2.3.10.3 Normal Service Operation

Circulation of the W.H.R plant must be maintained at all times when the mainengine is on load Also it must be continued for at least two hours after theengine has been stopped to ensure that any combustible material from theexhaust gas which has deposited on the heating surfaces is thoroughly cooledbelow the ignition point Circulation should be stopped and the system securedonly if a long stay in port is expected, i.e when it is necessary to conserveboiler fuel When leaving an intermediate port, if the system has beendepressurized, circulation of the W.H.R unit should be commenced before themain engines are started, and any air liberated by the hot circulating waterreleased from the header air vents

When S00t blowers are fitted to the unit, the fires should be lit in the oil-firedboiler to maintain steam pressure, the steam lines drained and the soot blowersoperated once daily at sea: intervals between blowing may be extended whenobservation of the funnel shows that soot discharge is small A guide to theireffectiveness is given by a change in the funnel exhaust temperatureimmediately after soot blower operation

Water washing of the heating surface must also be carried out at intervals ofthree months, or such lesser intervals as may be decided upon from sighting ofthe surface during intermediate inspections Before water washing is started,the drain provided at the lowest point of the inlet trunk immediately below theW.H.R unit must be proved clear prior to and during the washing operation.Washing is most effective when a large volume of water at low pressure isused This should be applied from outside the casing and personnel must not

enter the unit casing or trunking until the operation is completed and the spacevented As the wash water entrains aggressive sulphurous compounds from thedirty surfaces, casing and supporting steelwork exposed to the water should be

ACTIVATING SYSTEMS, COLD SHIPS 29

screened if possible When the washing is completed these surfaces should preferably be dried and protective paint coatings repaired where necessary Where a superheater is fitted in the W.H.R system, the superheater should

be drained, warmed through and brought on line when no further manoeuvring

is likely, to prevent it being subjected to a sudden cooling blast from main engine starting air Under normal main engine power conditions at sea the W.H.R plant will produce steam up to the design amount and pressure without adjustment If steam off-take from the boiler is reduced, the steam system pressure should be allowed to rise, provided it does not approach the boiler safety valve setting The rise in pressure initiates a self-balancing action in the W.H.R unit and less heat is extracted from the exhaust gases The funnel (i.e the gas tail end) temperature will thus vary with the steam load, being optimum

at the design condition and increasing as steam demand falls.

Steam system pressure changes are slow and not reflected in steam power plant performance where line steam pressure is reduced across a throttle valve For example, when a turbo-generator is in use the nozzle box pressure depends

on the load and the superheated steam temperature is related to the main engineexhaust temperature, so being independent of the steam pressure.

If auxiliary steam is required at sea for soot blowing, deck machinery or cargo services, it will be necessary to fire the boiler with fuel oil to supplement the output of the W.H.R unit whilst the machinery is in operation.

The oil burners should be lit-off in good time and for maximum economy the boiler pressure should be regulated to maintain a normal funnel temperature afterthe waste heat unit.

2.3.10.4 Control of Output

At a constant main engine power level, W.H.R systems have a rising pressure characteristic on a falling steam demand which affords some control With the circuit shown on Fig 2.3.10.1 output can be reduced by bypassing the feed heater on either the feed water or circulating water sides, so increasing the temperature at the economizer inlet and reducing gas/water temperature differences in this heat exchanger section Other automatic and/or manual control arrangements that may be encountered are:

• Controlling flow through an exhaust gas bypass duct by means of dampers.

• By closing one or more of the isolating valves supplying circulating water

to separate sections of the steam generator, when sub-divided inlet headers are provided Valves must be fully open or fully shut and not left

in an intermediate position.

• By steam dumping to the turbo-generator condenser.

At main engine powers lower than normal, the steam output possible from the W.H.R system will be reduced The steam system pressure will be reduced under this condition or if steam off-take from the boiler exceeds normal If