Function of diesel engine.docx

7/25/2019 Function of diesel engine.docx

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Function of diesel engine - Preparations for standby,starting,reversing and running at full speed

Marine diesel engine operation

The diesel engine is a type of internal combustion engine which ignites the fuel by injectingit into hot, high-pressure air in a combustion chamber. In common with all internal

combustion engines the diesel engine operates with a fixed sequence of events, which maybe achieved either in four strokes or two, a stroke being the travel of the piston between its

extreme points. ach stroke is accomplished in half a revolution of the crankshaft.

Main Engine Power and VibrationThe normal service power of the !ain ngine must be maintained as instructed in the

vessel"s commissioning letter unless otherwise directed by the #ompany, except under

emergency conditions involving safety of life or safety of the ship.

$hould the vessel"s normal service power require to be altered the fact, together with thereason for the alteration, is to be reported to the #ompany and noted in the ngine %og

&ook. The #hief ngineer is to take instructions from the !aster for the specific voyagerequirements, always keeping within safe operating parameters.

'ibration can cause severe damage to machinery, bearings, pipes, fittings, instrumentationand structure. To minimise this damage the main machinery must be regulated at all times

to avoid speeds at which excessive vibration may be experienced. &esides the barred-speedranges prescribed by the engine designers, operation at certain speeds where the

combination of draught, trim and weather leads to severe vibration, is also to be avoided.


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(ig) !*+ & %/!# engine

0articular attention must be paid to the balancing of cylinder loads in 1iesel engines and tothe tightness of holding down bolts on all reciprocating machinery. (ull use must be made of

all condition monitoring equipment supplied to detect and measure vibration, and anysignificant increase in vibration levels that cannot be accounted for must be reported to the

management ashore.


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Warming Through

!ain engines are to be warmed through gradually following a stay in port or other occasionwhen they have been shut down. The jacket water circulation temperature is to be raised

over a period of time to as near to the operating temperature as possible. The period oftime is dependent on the jacket water temperature prior to the commencement ofcirculation, the heating medium and si2e of main engine etc. *s a general rule circulation

should commence not less than 34 hours before the estimated time of departure. 5ther

circulating systems are to be put on line during this period i.e.

%ubricating oil systems.

(uel circulating systems.

$team tracing systems as is appropriate to the type of engine.

Precautions Prior to tandby !eparture

*ll circulating systems are to be as near as is possible normal operating parametersaccording to the manufacturer6s instructions for the engine type. 5n vessels where the

engine or engines are directly coupled to the propeller or propellers, the 1eck 5fficer of thewatch or 1uty 1eck 5fficer is to be contacted and permission to turn the engine requested.

5nce the 1eck 5fficer has confirmed that this can safely be carried out, then and only then

can the engine be turned.

*ll the indicator cocks are to be opened. The engine is then to be turned a minimum of onerevolution with the turning gear during which time the indicator cocks are to be sighted for

any evidence of oil or water discharge. If this test is satisfactory, then the indicator cocksare to be shut and the turning gear disengaged. It is of the utmost importance that the

disengagement of the turning gear is physically checked. +o reliance is to be placed on theindicator light in the control room, interlocks etc. It is the #hief ngineer6s responsibility to

ensure that this physical check is carried out.

5n vessels where the engine or engines are directly coupled to the propeller or propellers,the 1eck 5fficer of the watch or 1uty 1eck 5fficer is to be contacted and permission to turn

the engine on air requested. 5nce the 1eck 5fficer has confirmed that this can safely bedone, then and only then can the engine be turned on air. *ll indicator cocks are to be

opened. In conjunction with the &ridge and as applicable, the engine is to be 7kicked7 aheadand astern on starting air. The indicator cocks are then to be closed.

(ollowing the satisfactory turning of the engine on air, the 1eck 5fficer of the watch is to becontacted and permission to turn the engine on fuel requested. 5nce the 1eck 5fficer hasconfirmed that this can safely be done then, and only then, can the engine be turned on

fuel. In conjunction with the &ridge the engine is to be turned dead slow ahead and asternon fuel.

"peration on #eavy Fuel "il


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!ain engines designed to manoeuvre on heavy fuel oil are to be operated according to themanufacturer6s instructions. In the event of problems during manoeuvring on engines using

heavy oil there must be no hesitation in changing over to diesel oil irrespective of whetherthe engines are being operated using bridge control, or using engine room control.

It is the #hief ngineer"s responsibility to inform the !aster of the particular engine type6s

maximum period that it can safely remain in the stopped position. 8e is also to inform the!aster of the procedures which will have to be carried out if the particular engine type6smaximum period at standstill during manoeuvring is exceeded.

Preparations for standby

3. &efore a large diesel is started it must be warmed through by circulating hot water

through the jackets, etc. This will enable the various engine parts to expand in relation toone another.

4. The various supply tanks, filters, valves and drains are all to be checked.

9. The lubricating oil pumps and circulating water pumps are started and all the visiblereturns should be observed.

:. *ll control equipment and alarms should be examined for correct operation.

;. The indicator cocks are opened, the turning gear engaged and the engine turned throughseveral complete revolutions. In this way any water which may have collected in the

cylinders will be forced out.

. The engine is now available for standby.

The length of time involved in these preparations will depend upon the si2e of the engine.

Engine starting

3. The direction handle is positioned ahead or astern. This handle may be built into thetelegraph reply lever. The camshaft is thus positioned relative to the crankshaft to operate

the various cams for fuel injection, valve operation, etc.

4. The manoeuvring handle is moved to "start". This will admit compressed air into thecylinders in the correct sequence to turn the engine in the desired direction.* separate air

start button may be used.

9. hen the engine reaches its firing speed the manoeuvring handle is moved to therunning position. (uel is admitted and the combustion process will accelerate the engine and

starting air admission will cease.


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Engine reversing

hen running at manoeuvring speeds)

3. here manually operated auxiliary blowers are (itted they should be started.

4. The fuel supply is shut off and the engine will quickly slow down,

9. The direction handle is positioned astern.

:. #ompressed air is admitted to the engine to turn it in the astern direction.

;. hen turning astern under the action of compressed air, fuel will be admitted. Thecombustion process will take over and air admission cease.

When running at full speed$

3. The auxiliary blowers, where manually operated, should be started.

4. (uel is shut off from the engine.

9. &lasts of compressed air may be used to slow the engine down.

:. hen the engine is stopped the direction handle is positioned astern.

;. #ompressed air is admitted to turn the engine astern and fuel is admitted to acceleratethe engine. The compressed air supply will then cease.

Starting of generator engine

Starting of an engine from "stop" state is something which needs to be done with care, especially if the

interval of starting is suciently long. The following is a checklist of all the checks which ideally need

to be carried out before starting the generator. In actual practice sometimes the engineers might take

some of these for granted and skip, but it is advisable not to indulge in such a practice. Infact these

checks are generic for any four stroke engine starting process

1. heck the turbochargersump oil level, governor, alternator, forward and aft lube oil

levels, and diesel oil level in service tank

!. pen the indicator cock

#. $rime the lube oil to all parts by hand pump or by motor driven priming pump

%. &nsure that all 'acket cooler valves, lube oil cooler valves, air cooler valves should be in

open position

(. )ith use of the Turning bar turn the *y wheel and check for any resistance on the

bottom end bearing and check any water + fuel coming out through indicator cocks
http://www.brighthubengineering.com/marine-engines-machinery/41368-components-of-a-turbocharger/http://www.brighthubengineering.com/marine-engines-machinery/41368-components-of-a-turbocharger/


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. )hile turning engine, check all visible lube oil points are lubricated

-. emove the turning bar from *y wheel and put in the place

/. 0rain the auiliary air bottle

2. 3low through engine 4ie5 by turning engine with air6. In order to ensure that no water is

inside combustion chamber if it is present it may cause water hammering

17. lose the indicator cocksand pull lever from stop to start

11. )hen the needle in $8 indicator de*ects to some value of 479!( rpm6 put the lever in

run condition

1!. The engine will run on fuel oil once the generator picks up the rated speed

1#. $ut generator on load by closing air circuit breaker

1%. :or checking the alternator fore and aft bearing lube oil level by opening oil plug in the

alternator and the ring bearing while rotating splash lube oil from the sump can be seen

1(. In order to synchroni;e the incoming generatorwith running generator syncroscope

method+dark lamp method is used

Starting of generator

Checks to be made while running

nce the generator has actually started to run, there are several checks which must be performed

before it is left on its own to continue running. These checks pertain to verifying various parameters

related to lube oil levels, temperatures and so forth. ir cooler 4inlet 9outlet6 temperature
http://www.brighthubengineering.com/marine-engines-machinery/10205-what-is-an-indicator-diagram-in-context-of-marine-diesel-engines/http://www.brighthubengineering.com/marine-engines-machinery/31782-how-are-generators-synchronized-on-a-ship/http://www.brighthubengineering.com/marine-engines-machinery/10205-what-is-an-indicator-diagram-in-context-of-marine-diesel-engines/http://www.brighthubengineering.com/marine-engines-machinery/31782-how-are-generators-synchronized-on-a-ship/


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Safety devices

nce the above mentioned parameters have been checked and found within normal range, it is safe to

continue running the generator. Aet a fault can develop even at a later stage, so for this very purpose

various trips and alarms are situated on the generators. >n alarm gives the signal of an impeding

danger and reBuires Buick action while a trip actually trips the generator immediately because of the

nature of the fault.

The various trips and alarms are mentioned as follows

1. >lternator bearing low oil level alarm ? trip

!. >lternator bearing high temperature lube oil alarm ?trip

#. =ow sump oil level alarm and trip

%. =ube low oil pressure alarm and trip

(. everse current trip

. ver speed trip

-. ver load trip

/. Cigh and low freBuency trip

2. @acket cooling water low pressure alarm

A generator on a ship is known as the heart of the ship. It is that life-line which supports each

and every function of the ship. Generator of the ship requires special care, attention, and

maintenance for its effective and economic running. Moreover, when it comes to operating a

generator on a ship, its a totally different ball game.

Unlike the conventional generators that we use on land, a ships generator requires a specialprocedure for starting and stopping it. Though not a very complex one, the process demands a

step-by-step system to be followed. Missing even a single step might lead to failure in starting or

stopping the generator and can even lead to black-out, a situation which everyone on ship tries

their best to stay away from. In this article, we bring to you an accurate, step by step procedure

for starting and stopping a generator on a ship.

Generator starting procedure

Automatic Start

1.This method is only possible if sufficient amount of starting air is available. The

air valves and interlocks are operated like in the turning gear operation.


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2.In this method the operator has nothing to do, for the generator starts itself

depending on the load requirement.

3.However during the Maneuvering process and in restricted areas, the operator

has to start by going into the computer based Power Management System (pms).

Once inside the system, the operator needs to go to the generator page and click

start.

4.In PMS system, the automation follows sequence of starting, matching voltage

and frequency of the incoming generator and the generator comes on load

automatically.

5.In case of a blackout condition or a dead ship condition, the operator mighthave to start the generator manually.

Manual start

The manual process is totally different from the automatic start system. The following

steps need to be followed:

1.Check that all the necessary valves and lines are open and no interlock is

active on the generator before operating.

2.Generally before starting the generator the indicator cocks are opened and

small air kick is given with the help of the starting lever. After this, the lever is

brought back to the zero position, which ensures there is no water leakage in the

generator. The leakage can be from cylinder head, liner or from the

turbocharger .

3.The step is performed by putting the control to local position and then thegenerator is started locally.

4.In case any water leakage is found, it is to be reported to a senior officer or

chief engineer and further actions are to be taken.


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5.It is to note that this manual starting procedure is not followed generally on Ums

ships, but it is a common procedure on manned engine room.

6.In engine rooms, which have water mist fire fighting system installed, this

procedure is not followed because when the engine is given a manual kick with

open indicator cocks, small amount of smoke comes out of the heads which can

lead to false fire alarm, resulting in release of water mist in the specified area.

7.After checking the leakage, in case of any, the indicator cocks are closed and

generator is started again from the local panel.

8.The generator is then allowed to run on zero or no load condition for some time

for about 5 minutes.

9.After this the generator control is put to the remote mode.

10.If the automation of the ship is in working after putting in remote mode

thegenerator will come on loadautomatically after checking voltage and

frequency parameters.

11.If this doesnt happen automatically, then one has to go to the generator panel

in Engine control room and check the parameters.

12.The parameters checked are voltage and the frequency of the incoming

generator.

13.The frequency can be increased or decreased by the frequency controller or

governor control on the panel.

14.The incoming generator is checked in synchroscope to see if its running fast or

slow, which means if frequency is high or low.

15.In synchroscope, it is checked that the needle moves in clockwise and

anticlockwise direction.
http://marineinsight.com/more/featured/how-to-synchronize-generators-on-a-ship/http://marineinsight.com/more/featured/how-to-synchronize-generators-on-a-ship/


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16.Clockwise direction means it is running fast and anti-clockwise means it is

running slow.

17.Generally the breaker is pressed when the needle moves in clockwise direction

very slowly and when it comes in 11o clock position.

18.This process is to be done in supervision of experienced officer if someone is

doing for the first time, for if this is done incorrectly the blackout can happen

which can lead to accidents, if the ship is operating in restricted areas.

19.Once this is done, the generator load will be shared almost equally by the

number of generators running.

20.After this the parameters of the generator are checked for any abnormalities.

Stopping procedure

Automatic Procedure

In this procedure the generator is stopped by going into the PMS system in the

computer and pressing the stop button to bring stop the generator.

1.This is to be followed only when two or more generators are running.

2.Even if you trying to stop the only running generator it will not stop due to inbuilt

safety. The safety system thus prevents a blackout.

3.When the stop button is pressed the load is gradually reduced by the PMS and

after following the procedure the generator is stopped.

Manual Procedure

1.In this procedure the generator to be stopped, is put off load from the generator

panel in the Engine control room.

2.The load is reduced slowly by the governor control on the panel.


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3.The load is reduced until the load comes on the panel below 100 kw.

4.When the load is below 100kw the breaker is pressed and the generator is

taken off-load.

5.The generator is allowed to run for 5 minutes in idle condition and the stop

button is pressed on the panel.

6.The generator is then stopped .

Large Marine Diesel Engines are started using high pressure compressed air. The airis admitted into the cylinder when the piston is just past TDC and continued until

just before the exhaust valve opens. There is always more than one air start valve

open ! a situation "nown as overlap. This ensures that the engine will start in any

position. The opening of the main air start valves is controlled by a set of pilot

valves located in the air start distributor# which in turn are timed to operate by a

drive lin"ed to the main camshaft. $n the example shown# a small camshaft is used

to control the opening and closing of the air start pilot valves.


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The drawing shows the principle of operation of an air start system. Large air

receivers are used to store the compressed air. The diagram shows the isolating

valve open so air is being allowed as far as the automatic valve and the air start

control valve.

%hen the engine is re&uired to start# a low pressure air signal is sent to the air start

control valve 'which can also be hand operated in an emergency(. The air pushes a

piston down which opens the valve and allows high pressure air to flow to the pilot

valve and the automatic valve operating pistons. The pilot valve is forced down

onto the cam profile and the automatic valve opens and high pressure air is led to

the main air start valves and the pilot valve. %hen the pilot valve cam follower is on

the lowest point on the cam# air flows to the operating piston of the main air start

valve for that particular cylinder# opening the valve and allowing high pressure air

to flow into the cylinder.

%hen the pilot valve is lifted by the cam# the pilot valve vents and the main air start

valve closes. %hen the start air signal is ta"en off the air start control valve# the

system vents and the automatic valve shuts.

The animation below shows the se&uence of operations.


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)n interloc" bloc"ing valve will operate# for instance if the turning gear is left in#

and this will stop high pressure air from reaching the air start control valve and thus

either the automatic valve or the pilot valve.

) slow turning valve is fitted. This will open instead of the main automatic valve if

the engine has been stopped for more than *+ minutes during manoeuvering. $t will

only supply enough air to turn the engine over very slowly, This is a precaution in

case a cylinder has had oil or water lea" into it which would cause damage to the

engine when starting. $f the engine completes a full revolution on the slow turn#

then the main automatic valve opens and the engine will start. 'note The operating

system for the slow turning has been omitted for simplicity(.

$nternational )ssociation of Classification -ociety rules state

In order to protect starting air mains against eplosion arising from

improper functioning of starting valves, the following devices must

be Dtted5

i. >n isolation non9return valve or eBuivalent at the starting air

supply connection to each engine.


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ii. > bursting disc or *ame arrester in way of the starting valve of

each cylinder for direct reversing engineshaving a main

starting manifold. OR

ii. >t the supply inlet to the starting air manifold for non-reversing engines

0evices under 4ii6 above may be omitted for engines having a bore

not eceeding !#7 mm.

The system may also be provided with a relief valve.

Before Starting:

CHECK THE LEVEL OF THE FUEL OIL SERV. TANK AND

DIESEL OIL SERV. Tk.

SWITCH ON ALL THE COOLING WATER AND

LUBRICATING OIL P/Ps.

OBTAIN PROPELLER CLEARANCE FROM THE BRIDGEAND ENGAGE THE TURNING GEAR AND TURN THEENGINE BY MEANS OF TURNING GEAR WITH INDICATORCOCKS OPEN TO ASCERTAIN THAT NOTHINGOBSTRUCTS THE MOVEMENT OF THE RUNNING GEAR,

AT THE SAME TIME OPERATE THE HAND CRANKS OFTHE CYL. LUBRICATORS FOR ABOUT 20-2 TURNS SO

AS TO ENSURE SATISFACTORY LUBRICATION OF THECYLINDERS FROM THE VERY BEGINNING. IT MUST BENOTED THAT THA HAND CRANKS CAN BE OPERATEDWITHOUT APPLYING ANY ABNORMAL FORCE.

CHECK THE PRESSURE IN THE STARTING AIR

RECEIVER AND DRAIN THE AIR RECEIVER OF WATER.


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DISENGAGE THE TURNING GEAR AND SECURE.

STARTING THE MAIN ENGINE

I. CHECK WHETHER THE STARTING AIR IS ON THE MAINENGINE AND WHETHER THE TURNING GEAR ISDISENGAGED AND SECURED. THE AUTOMATIC

STARTING AIR STOP V/V MUST BE ON AUTOMATICPOSITION AND HAND SWITCH FOR THE AU!. BLOWERMUST BE ON MANUAL POSITION. THE FUEL LEVER OFTHE EMERGENCY MANEUVERING STAND IN POSITION "REMOTE CONTROL# AND SPEED SETTING LEVER ONTHE CONTROL DESK IS TO BE AT A POSITIONSUFFICIENT FOR STARTING THE ENGINE$A%%&'(. ).*.

II. MOVE THE TELEGRAPH LEVER TO THE POSITION AS

RE+UESTED BY THE BRIDGE.

III. PUSH THE STARTING BUTTON AND HOLD IN THISPOSITION UNTIL THE ENGINE FIRES CORRECTLY, THENRELEASE THE SAME THUS ALLOWING THE STARTINGSYSTEM TO DRAIN ITSELF.

IV. THE ENGINE IS NOW RUNNING ON FUEL. ADUST THEORDERED MANEUVERING SPEED BY SETTING THESPEED SETTING LEVER.

V. AS SOON AS THE ENGINE IS TURNING OVERCORRECTLY, CHECK THE PRESSURE GAUGES AND

ADUST THE PRESSURES TO THE PROPER VALUES,


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CHECK TURBOCHARGER AND THEIR CORRECT SPEEDBY OBSERVING THE TACHOMETERS.

VI. OBSERVE THE TEMPERATURES.

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Function of diesel engine.docx

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