engine systems for marine engineering students
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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
SECTION 2 OF CHAPTER 2
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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.
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7/30SHIPS FUEL OIL SYSTEM
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SHIPS FUEL OIL SYSTEM
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Lubricating Oil System
SECTION 3 OF CHAPTER 2
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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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LUBRICATING OIL SYSTEM
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SOURCES OF CONTAMINATION IN
LUBRICATING OIL SYSTEM
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
SECTION 4 OF CHAPTER 5
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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
SECTION 5 OF CHAPTER 2
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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
SECTION 6 OF CHAPTER 2
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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
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