engine systems for marine engineering students

8/11/2019 Engine Systems for Marine Engineering Students

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ENGINE SYSTEMS


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OBJECTIVES

Explain in detail the flow of the following engine systems:

- fuel oil system

- lubricating oil system

- piston cooling system

- jacket cooling water system

- starting air system

Accurately identify the principal parts that make up each

system

Correctly state the function of each part


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Ancillary system

SECTION 1 OF CHAPTER 2


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ANCILLARY SYSTEM

With the exception of the smallest installations, no shipspropulsion engine can operate without supporting ancillary machinery

systems to provide basic functions such as cooling, lubrication, exhaust

arrangements, starting arrangements, fuel treatment and so on.


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Fuel Oil System



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FUEL OIL SYSTEM

Basically, fuel is something that is burned to power or heat.

There are two types of fuel aboard ships, the Heavy Fuel Oil

(commonly known as bunker) and Diesel Oil. The fuel oil system can

be divided into two parts:a. Fuel Oil Purification and Transfer

b. Fuel Oil Service

As the name implies, FO purification and transfer deals

mainly with a purification of the fuel oil. This part of the system

begins from the bunker manifold ends in the service tank. The FO

Service Tank and in the main and auxiliary engines. The fuel oil is

loaded to the storage tanks via the bunker manifold.


7/30SHIPS FUEL OIL SYSTEM


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SHIPS FUEL OIL SYSTEM


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Lubricating Oil System



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LUBRICATING OIL SYSTEM

The lubricating oil system can be divided into two parts. Each

part uses a different types of lubricating oil.

a. System Oil

b. Cylinder oil

The system oil circulates within the main lubricating oil system and

acts as both lubricant and coolant for the enginesmoving parts and

the stationary parts. The cylinder oil is used to lubricate the cylinder

liner. This system is not circulating type, rather, the cylinder oil is

consumed within the cylinder during combustion process

The oil serves two purposes:

a. Reduce friction

b. Cool the bearings


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SOURCES OF CONTAMINATION IN


a. Water

I. Bilges

II. Jacket Cooling Water

III. Seawater via leaking oil coolerIV. Leaks in L.O. Purifier

V. Condensation

b. Fuel Oil

c. Solid Impuritiesd. Bacterial Attack


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CLICK FOR LUBE-OIL SYSTEM
http://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppthttp://localhost/var/www/apps/conversion/tmp/scratch_7/13_BPLube_oil_sys.ppt


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Piston Cooling System



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PISTON COOLING SYSTEM

The piston is exposed to very high temperatures,therefore a suitable cooling system needed to reducethe thermal stress on the crown. Piston cooling systemsmay either freshwater or system oil as coolant,

depending on the engine design. Water cooled systemshave been proven reliable when running on heavy fuelsand the use of water cooling has resulted in practicallynegligible system oil consumption. However there isalso slight risk of water leaking into the crankcase,

therefore, contaminating the system oil. With oil cooling,oil is consumed usually as a result of thermal aging onhot piston walls. Oil leaks from oil cooled pistons mayalso occur.


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PISTON COOLING SYSTEM


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Jacket Cooling Water System



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JACKET COOLING WATER

SYSTEM

The main engine is cooled by freshwater

circulated in a closed system driven by electric

motor driven centrifugal pumps. A header tank or

expansion tank maintains a constant head on

cooling freshwater pumps, thereby, reducing

cavitations at elevated temperatures. It allows thevolume of water in the system to vary without the

need for dumping and acts as a reserve in the

event of leakage. An outlet line leads to the

suction side of cooling water pumps.


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JACKET COOLING WATER SYSTEM


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Starting Air System



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STARTING AIR SYSTEM

Main propulsion diesel engines use compressed

air as the medium for starting. Although the system isquite simple and requires only a few equipments it isgoverned by requirements to ensure the safety of theship especially when there is a need for frequentstopping and starting of the engine particularly duringmaneuvering.

The components of the air start system are takento include compressors and storage bottles in addition tothe air start arrangement. A minimum of two

compressors should be matched to the starting airrequirements of the engine. The compressor aftercoolers should be protected by bursting disc. All highpressure lines in the system is to be made solid drawnpipe.


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STARTING AIR SYSTEM


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AIR RECEIVERS

Receivers must be protected by means of arelief valve. If the relief valve can be isolated fromthe receiver, then, a fusible plug or plugs must befitted. These are usually fitted because in the event

of a fire near the bottle, they will fail and releasethe entire contents of the bottle rapidly. A reliefvalve, however will only release air down to itsclosing pressure and will still retain a high,

although reduced, air pressure. If the structure ofthe bottle becomes weakened by the heat, then itsability to withstand even the reduced pressure isweakened, and possible rupture could occur.


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SAFETY DEVICES

An automatic valve prevents connectionbetween the air receiver and air start manifold

unless actually in the process of starting. This

minimizes the risk of an explosion in the air

manifold which could propagate back to the airreceiver where a much more severe explosion is

possible. Safety devices are incorporated in the air

start manifold in order to dissipate the energy of an

explosion, thus, keeping is effects local.


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SAFETY DEVICES (FLAME ARRESTOR)

The flame trap is manufactured from

brass or aluminum alloy which both have a

high specific heat capacity. A number of holes

are bored through the thick circular form toallow the air to pass through. They are fitted in

the main air line immediately before the air

start valve to restrict the risk of a flame in thecylinder propagating back to the main air start

manifold, by dissipating the heat energy in the

flame.


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SAFETY DEVICES (FLAME ARRESTOR)

FLAME ARRESTOR MAN B&W L58/64 FLAME ARRESTOR SULZER RTA


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SAFETY DEVICE (BURSTING DISC)

The safety cap consists of a bursting diskenclosed by a perforated cylinder and aperforated cover in order to protect any

bystanders, in the event of a burst. The coveris fitted with a tell tale, which shows if thebursting disc has been damaged. If thebursting disc of the safety cap is damaged due

to excessive pressure in the starting air line,overhaul or replace the starting valve whichcaused the burst, and mount a new disk


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SAFETY DEVICE (BURSTING DISC)

BURSTING DISC MAN B&W MC


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SAFETY DEVICE (START AIR RELIEF VALVE)

START AIR RELIEF VALVE

The sketch shows a reliefvalve as fitted to the air startmanifold of Sulzer RTA 2 strokeengines. Its purpose is to relieveexcess pressure in the air startmanifold. It consists of a springloaded valve disk which locateson a mating seat which is boltedto the end of the air startmanifold. When the forceexerted on the disk due toexcessive pressure is greaterthan the spring force holding thevalve closed, the valve will open.


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STARTING AIR EXPLOSION

Unsatisfactory practiceswhich have led to explosions in the airstart system include:

Telltales/drainsat each end of thestarting air manifold found to have

been blanked off with screwedplugs.

Failure to drain starting airreceivers and starting air pipes atregular intervals or beforemaneuvering.

Failure to check for leaking air startvalves.

Failure to maintain starting airvalves and systems strictly inaccordance with manufacturersrecommended practices.

Failure to maintain fuel valves

correctly

engine systems for marine engineering students

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