Different Parts of a Marine Air Compressor
Used on a Ship
A marine air compressor
provides compressed air for various purposes on a ship. An air compressor is
one of the most important equipments on a ship which needs special care and
routine maintenance. In this article we will know the basics of the marine air
compressor by first getting familiarized with the different parts of the same.
The main
parts of the marine air compressor are:
1) Cylinder liner:
It is
made of graded cast iron and is accompanied with water jacket around it to
absorb heat produced during compression process. It is designed so as to give a
streamline passage to the pressurized air resulting in minimum pressure drop.
2) Piston:
For a
non-lubricating type compressor, light weight aluminum alloy piston are used
and for lubricating type graded, cast iron piston are used with piston rings
for sealing and scrapping off excess oil.
3) Piston Rod:
In high
capacity compressor which is normally big in size, piston is attached to piston
rod made up of alloy steel. They are fitted with anti friction packing ring to
avoid chances of compressed air leakage.
4) Connecting rod:
Connecting
rod plays its role to minimize thrust to the bearing surface. It is made up of
forged alloy steel.
5) Big end bearing and Main
bearing:
They are
constructed to give rigidity to the running rotational mechanism. They are made
up of copper lead alloy and have a long operational life if proper lube oil and
lubrication is provided.
6) Crank shaft:
It is a
one piece designed part, using counterweights for dynamic balancing during high
speed of rotation to avoid twisting due to torsion forces. Connecting rod big
end bearing and main bearing are connected to crank shaft at crank pin and
journal pin which are polished to ensure long working life of bearings.
7) Frame and crankcase:
Normally
they have rectangular shape and accommodate all the moving parts and that’s why
are made up of rigid cast iron. Main bearing housing is fitted on a bore in
crank case and is made with highest precision to avoid eccentricity or
misalignment.
8 ) Oil pump:
A
lubricating oil pump is fitted to supply lube oil to all the bearings, which
can be chain or gear driven, through crank shaft. Pressure of oil can be
regulated by means of regulating screw provided in the pump. A filter in the
inlet of the pump is also attached to supply clean and particle free oil to the
bearings.
9) Water pump:
Some
compressor may have attached water cooling pump driven by crankshaft through
chain or gear. Some system does not use attached pump as they use water supply
from main or auxiliary system for cooling.
10) Suction and Discharge
valve:
These are multi-plate valves made up of stainless steel and are
used to suck and to discharge air from one stage to another and to the air
bottle. Proper assembling of valves is very important for efficient operation
of the compressor.
11) Suction Filter:
It is a air filter made up of copper or soft steel with a paper
material to absorb oil and wire mesh to avoid any metal or dust particle to go
inside compression chamber.
12) Inter-coolers:
Inter-coolers
are normally fitted in between two stages to cool down the air temperature and
to increase the volumetric efficiency of compressor. Some compressor have
inbuilt attached copper tubes for cooling and some have outside assembly of
copper tube inter-coolers.
13) Driving Motor:
An
Electrical motor is attached to the compressor for making it operational and is
connected to the compressor through the flywheel.
There
are the main parts of a marine air compressor. The parts may vary according to
the requirement of the system or ship.
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