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Air or Compressors
Lecture # 23-24
Mujahid Mehdi Abro IndusUniversity
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Air or Gas compressors
Compressor is a machineused to compressed air orgas to a fnal pressureexceeding 24!2" $a
%a%e.
&'
Compressor is used toincrease the pressure o air
rom low pressure to highpressure by using someexternal energy.
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U()( &* C&M$')(()+AI'
Operation o small engines
Pneumatic tools
Industrial cleaning by air blast
Tire ination Paint Spraying
anuacture o plastics and otherindustrial products
Textile Industry
!ot o use in wea"ing machine
Compressors are used in wet#processingdepartment
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Main Components in
Compressed Air Systems
Intake air filters
Inter-stage coolers
Air dryers
Moisture drain traps
Receivers
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Compressed air systems consist o ollowingma$or components%
Inta,e Air *iters that pre"ent dust romentering a compressor. &ust causes stic'ing"al"es( scoured cylinders( excessi"e wear
etc.
Inter-sta%e Cooers that reduce thetemperature o the air beore it enters the
next stage to reduce the wor' ocompression and increase e)ciency. Theyare normally water#cooled.
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Air-dryers that remo"e the remainingtraces o moisture ater ater#cooler ase*uipment has to be relati"ely ree o anymoisture.
Moisture drain traps that are used orremo"al o moisture in the compressed air.
These traps resemble steam traps. +arious
types o traps used are manual drain coc's(timer based , automatic drain "al"es etc.
'eceivers that are pro"ided as storage
and smoothening pulsating air output #
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-ey%#.'/ /on 0eturn +al"e 1 a one way "al"e(/ Saety "al"e. The fnal saety "al"e is usually set 234 abo"ethe cylinder maximum wor'ing pressure$M/ Pressure maintaining "al"e 1 5 crucial part o the fltrationsystem usually set to release pressure between 263#273 bars.
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Types of Compressors
Type of
compressor
Positive
displacement
ReciprocatingRotary
Dynamic
Centrifugal Axial
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01$)( &* C&M$')((&'(I0 ')($)C0 0& U(AG)
Centrifugal Compressors %
8or low pressure and high capacity application
Rotary Compressors %
8or medium pressure and low capacityapplication
Reciprocating Compressors %
8or high pressure and low capacity application
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Reciprocating Compressor
In a reciprocatingcompressor, a volume of air
is drawn into a cylinder, it is
trapped, and compressed by
piston and then dischargedinto the discharge line. The
cylinder valves control the
flow of air through the
cylinder; these valves act as
check valves.
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There are two types o reciprocatingcompressor
Single 1 5cting compressor
It is a compressor that has one discharge perre"olution o cran'shat.
&ouble 1 5cting Compressor
It is a compressor that completes two
discharge stro'es per re"olutions o cran'shat.ost hea" #dut com ressors are double
Types of Reciprocating
Compressors
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Parts of Reciprocating Compressor
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orking of Reciprocating Compressor
!Disc"arge#
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orking of Reciprocating Compressor
!Disc"arge#
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orking of Dou$le Acting Reciprocating
Compressor
(ta%e
(ta%e3
(ta%e2
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Advantage of Dou$le Acting
Compressor
0eduction in power re*uired to dri"e thecompressor.
9etter mechanical balance o the whole unit
and uniorm tor*ue. Increase in "olumetric e)ciency.
0educed lea'age loss.
!ess di)culty in lubrication due to low wor'ingtemperature.
!ighter cylinders can be used.
Cheaper materials can be used or
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Rotors instead of pistons% continuousdisc"arge
&enefits% lo' cost( compact( lo' 'eig"t(
easy to maintain
Types
)o$e compressor
Scre' compressor
Rotary vane * Slide vane
Rotary Compressor
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Centrifugal Compressor
Centrifugal compressorsaccelerates the velocity of the
gases (increases kinetic energy)
which is then converted into
pressure as the air flow leavesthe volute and enters the
discharge pipe.
sually operate at speeds !
",### rpm.
$eliver much higher flow rates
than positive displacement
compressors
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Impellers( +anes( +olutes(Suction :yes( &ischargelines( &i;user Plates(
Seals( Shat( Casing
Suction +ane Tips Parto the impeller "ane that
comes into contact withair frst.
&ischarge +ane Tips
Part o the impeller "ane
asic Components