The document discusses different types of compressors used to compress gases. It describes positive displacement compressors like reciprocating, screw, and rotary vane compressors which work by reducing the gas volume. Dynamic compressors like centrifugal compressors are also discussed which increase gas pressure using an impeller. Key components, working principles, advantages and disadvantages of reciprocating, screw, rotary vane and centrifugal compressors are summarized. Selection factors for compressors like required pressure, flow rates, piston speed and system layout are also highlighted.

1. COMPRESSORS
PRESENTED BY
M.SRINIVASARAO
7893168462
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2. Detailed Study of various
Components:
Compres
sors
Conden
sers
Evapora
tors
Expansion
Devices
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3.  Compressors are mechanical devices that
compresses gases. It is widely used in industries and
has various applications
 The machine which takes in air or any other gas at
low pressure and compresses it to high pressure are
called compressors.
 A compressor is used for increasing the pressure of
air is called Air compressor.
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5. Air compressors are classified according to method of
energy transfer and pressure generation i.e. positive
displacement and dynamic compressors
Positive displacement compressors work on the principle of
increasing the pressure of air by reducing the volume of air
in an enclosed chamber
Dynamic compressors works on the principle of imparting
the energy by rotating vanes of impeller on air flowing
through casing that increases pressure in air
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6. Reciprocating Air compressors
 Reciprocatingaircompressorsarepositivedisplacement
typeofaircompressors.
 Thesearepiston&diaphragmtype,vanetype,geartype,
screwtypecompressors
 Theprincipleofoperationissamebutaccordingtostages
thedeliverypressureisdifferentineachcompressor.
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7.  Areciprocatingaircompressorconsistofapistonwhichis
enclosedwithinacylinderandequippedwithsuctionand
dischargevalve
 ThepistonreceivespowerfromelectricmotororICengine.
 Thecompressionofairisdonebyfirstdrawingavolumeof
airintothecylinderthroughsuctionvalveduringsuction
strokeofpistonandthencompressedanddischarged
throughdeliveryvalveduringdeliverystroke
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8. SinglestageReciprocatingAircompressors
 Inthistypetheentirecompressioniscarriedoutinasingle
cylinder
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9.  Whenpistonstartsmovingdownwards,thepressureinside
thecylinderfallsbelowatmosphericpressurethatopens
suctionvalve.
 Thepressureoftheairinthecylinderrisesduring
compressionandattheendofcompression,deliveryvalve
opensanddischargesthecompressedairintothereceiver
tank.
 Singlestageaircompressordeveloppressureupto7bar.
 Forhigherpressuresmultistagecompressorsaresuitable
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10. Double stage Reciprocating Air compressors
 Itconsistoftwocylinders–lowpressurecylinderandhigh
pressurecylinder
 Piston,crankcase,pistonrod,crank,crankshaft, oil,finsetc.
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12.  ThefreshairisdrawninsidetheL.P.cylinderthroughinlet
suctionfilter.
 Thisairiscompressedbypiston
 Asthepistonmovestowardstheendofcylinder,theair
compressiontookplace.
 ThefreshairisdrawninsidetheL.P.cylinderthroughinlet
suctionfilter.
 Thisairiscompressedbypiston
 Asthepistonmovestowardstheendofcylinder,theair
compressiontookplace.
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13.  ThehighpressureairfromH.P.cylinderisthendeliveredto
receiverthroughdischargevalves.
 Inthiscompressor,apressureofairdeliveredisupto13bar.
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14. Advantages
 Simple in design
 Lower initial cost
 Easy to install
 Higher effeiciency
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15. Disadvantages
 Number of moving parts are more
 Higher maintenance cost
 Heavy foundation is required as it has vibration
problem
 Cannot run at full capacity
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16. Rotary vane compressor
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17. Rotary vane compressor
 Itispositivedisplacementtypecompressor.
 Itprovideshigherefficiencyandflowratesoverawide
rangeofpressure
 Rotaryvanecompressorconsistofrotorwithanumber
ofvanesinsertedintheradialslotscutinrotor.
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18. Rotary vane compressor
 Therotorismountedeccentricinacasing.
 Thevanesslidesradiallyinandoutoftherotor.
 Astherotorrotatesathigherspeed,centrifugalforce
throwsthevanesoutwardkeepingtheendofvanein
contactwiththestatorring.
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19. Rotary vane compressor
 Astherotorturns,compressionisachievedasthevolume
goesfromamaximumatintakeporttominimumatthe
exhaustport.
 Anoilisinjectedintotheairintakeandalongthestator
wallstocooltheairandlubricatebearingandvanesand
toprovideasealbetweenthevaneandstatorwallto
reduceinternalleakage.
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20. Advantages:
 Simpledesign
 Compactinsize
 Lightinweight
 Easytoinstall
 Lowcost
 Lowmaintenancecost
 Longerlife
 Fewmovingparts
 Lowrotationalspeed
 Expensivefoundationnotrequired
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21. Disadvantages:
 Lowerefficiency
 Difficultywithhigherpressureabove200psi
 Oilinjecteddesignshaveoilcarryover
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22. Centrifugal compressor
 Itisdynamiccompressor.
 Itconsistofarotatingimpellerwhichrotatesathigher
speed(upto60000rpm)
 Animpellerfittedinsidecasingforcetheairtotherim
ofimpeller,increasingvelocityofair.
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23. Centrifugal compressor
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24. Centrifugal Supercharger
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25. Centrifugal compressor
 Adiffuser(divergentshapeofcasing)sectionconvertsthe
velocityofair tocauseanincreaseinpressure.This
process is called dynamic compression.
 These compressors are used for continuous,
stationary services in industries like oil refineries,
chemical and petrochemical plants, natural gas
processing plants.
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26. Centrifugal compressor
 These are also used in IC engine superchargers and
turbochargers.
 In gas turbine plants
 It can provide extremely high output pressures
greater than 10000psi.
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27. Screw compressor
 It consist of two screws - one with convex and the
other with concave contour mostly called male and
female rotor respectively.
 These two screws gets rotating by means of gear
trips there by sucking the air through an inlet port
in chamber and then compressing the same
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28. Screw compressor
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29. Screw Compressor
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30. Screw compressor
 Thus compression begins and air is discharged at
the end of other side.
 There is no contact between male and female
rotors and casing. Hence no lubrication require but
oil may injected for the purpose of cooling.
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31. Details of Screw Compressor
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32. Twin lobe compressor
 It is used in applications where higher flow at
comparatively low pressure is required.
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33. Twin lobe compressor
 Here two lobes are placed in a casing
 The air is transferred from suction side to the
delivery side with continuous rotation of two lobes
 The lobes are precisely maintained and the casing
also maintained to close tolerances
 It has limited compression ratio @ 1.7
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34. Selection of compressors
 Pressure :
 The discharge pressure from the compressor
should be decided first considering the needs of the
cylinder, air motor & pressure drop in the circuit.
 Most of pneumatic systems and tools are designed
for pressure of 6 – 7 bar.
 A compressor used should meet the requirement.
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35. Selection of compressors
 Pressure :
 Pneumatic circuit requiring air at high pressure
can be supplied with air by a separate high
pressure compressor
 While any low pressure can be met by availing a
reducing valve.
 For huge air flow rates at pressures below 2 bar, a
turbo-blower or low pressure rotary compressor
may be used.
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36. Selection of compressors
 Flow rates or capacity:-
 Volume of air required per minute is also an
important factor for selection.
 The capacity should be adequate enough to supply
air to all devices operating simultaneously.
 In many plants where pneumatic tools are
operated intermittently, in such cases maximum
instantaneous demand of the compressed air has
to be find first.
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37. Selection of compressors
 Speed of piston:-
 The speed of piston inside the cylinder must also
be considered.
 For small capacity compressor, the piston speed
300 m/min, whereas for large capacity
compressor piston speed 250 m/min.
 The layout of pipe line, system requirement and
the distance of user machine from compressor
plant
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