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1To Be a Leader in Maritime Education and Training
Learning Objective: Understand the air compressor and reservoirs
types, construction and operation on board.
Specific Learning Objectives: Explain the uses of compressed air
onboard. State the compressor types that may be found
onboard. Explain the operation of single and multi-stage air
compressor Sketch and describe the inter and after cooling.
Describe the air compressor components assembly
and materials. With the aid of diagram, explain the air
reservoir
construction. Describe the safety features an air compressor.
Describe the design features of air reservoir. Describe the safety
features of air reservoir.
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Dynamic Air Compressor
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Dynamic Air Compressor
Increasing the pressure of gases by imparting to it the kinetic
energy, which is converted into pressure energy into a diffuser.
Means that air is forced into space and energy is added to it by
increasing the velocity. Velocity will decrease by volute casing or
diffuser. Thus loss of velocity will cause the pressure to
increaseat the discharge side of the compressor.
This type of compressor is considered under continuous mode in
which the gas moved into the compressor is moved through the
compressor and discharged without interruption of the flow at any
point in the process
These are multi-blade compressors and are further subdivided
into:
Centrifugal compressor
Jet compressor
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Centrifugal Air Compressor
A high peripheral velocity is imparted to the gases being
compressed by the blades of the impeller which rotates at a speed
of 3000 to 27000 rpm to produce high-pressure discharge or by
converting angular momentum imparted by the rotatingimpeller
(dynamic displacement)
The centrifugal force developed in this way partially compresses
the gases. Further compression occurs in diffuser (reduced velocity
which is depending upon the direction of gases flow) at outlet from
impeller. Compressor can be radial or axial.
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Centrifugal compressors are now most frequently used for medium
volume and medium pressure air delivery. One advantage of a
centrifugal compressor is the smooth discharge of the compressed
air.
Simplified centrifugal
compressor
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The centrifugal force utilized by the centrifugal compressor is
the same force utilized by the centrifugal pump. The air particles
enter the eye of the impeller then is thrown against the casing
The air becomes compressed as more and more air is thrown out to
the casing by the impeller blades
The air is pushed along the volute casing cause pressure of the
air is increased that
The impeller blades curve forward, which is opposite to the
backward curve used in typical centrifugal liquid pumps or
considered can use a variety of blade orientation including both
forward and backward curves.
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There may be several stages to a centrifugal air compressor, as
in the centrifugal pump, and the result would be the same; a higher
pressure would be produced.
The air compressor is used to create compressed or high pressure
air for a variety of uses. Some of its uses are pneumatic control
devices, pneumatic sensors, pneumatic valve operators, pneumatic
motors, and starting air for diesel engines.
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Internal view of a multistage
centrifugal compressor
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Jet Compressor
In jet compressor the driving vapour attains a high supersonic
velocity in a Laval nozzle and then mixed with the gases to be
compressed in a mixing chamber and leading it at high velocity to
the diffuser where kinetic energy is converted into pressure
energy
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GAS-JET COMPRESSOR
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Summary
Uses of Compressed Air onboard.
Compressor Types
Operation of Single and Multi-stage Air Compressor
Components of Air Compressor
Safety features an Air Compressor and Air Reservoir.
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Thank You
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