Centrifugal Compressor course helps beginners to understand basic knowledge about how to operate and maintain the compressor.

Centrifugal Compressor course helps beginners to understand basic knowledge about how to operate and maintain the compressor. Also it gives detailed information about the machine components.

1. CENTRIFUGALCOMPRESSORS

2. Tableofcontents
•IntroductiontoCentrifugalcompressors
–PotentialandKineticenergy
–Dynamiccompressors
–Operatingcharacteristics
•CompressorsConstruction
–
–
–
–
CasingDesigns
Compressorsparts
Typeofseals
Compressorssystems
•Coolingsystem
•Lubricationsystem
•SafetyDevices
•OperatingCompressors
–Compressorsconfiguration
–Performancefeatures

3. IntroductiontoCentrifugalcompressors
PotentialandKineticEnergy
Whengas
iscompressed
intoa
smallervolume,
thepressureof
thegas
increases
Pressure Newton’sFirstLawofmotion

4. IntroductiontoCentrifugalcompressors
Dynamiccompressors
Centrifugalcompressor
Bladesforceairinthe
impellertomove.The
impelleradds both
velocityandpressureto
air.
Gaspassesfromthediffuser
intothevolute.Theconversion
fromvelocitytopressure
continues.

5. IntroductiontoCentrifugalcompressors
ExampleofCentrifugalcompressors

6. IntroductiontoCentrifugalcompressors
Dynamiccompressors
Axialcompressor
•Thestatorbladesareattachedtothe
casing.
•Therotorbladesforcethegasto
move,impartpressureandvelocity
•Asthegasflowsthroughanaxial
compressoritoccupieslessvolume
increasingitspressure.
•Therotorbladesincreasevelocityand
statorbladesconvertittopressure

7. IntroductiontoCentrifugalcompressors
ExampleofAxialcompressors

8. IntroductiontoCentrifugalcompressors
ExampleofAxialcompressors

9. IntroductiontoCentrifugalcompressors
Surging
ItoccurswhenSurgingoccurswhengasrapidlyflowsbackandforththroughthecompressor.
thecompressorisoperatedbelowminimumcapacity

10. IntroductiontoCentrifugalcompressors
Operatingcharacteristics
CompressorRatio:Relationshipbetweendischargepressureandsuctionpressure
CompressorCapacity:Volumeofgasthatthecompressormovesinagivenperiodoftime(CFM)
Workofcompression:Theworkofcompressioncanbethoughtofasstraightliftingofagivenweightofgas(foot-pound)
•ThefastertheRPMofthe
impeller,themoreworkis
doneonthegas.
Pressureinthehead

11. •ConstantWeightflow:Someprocessesrequireaconstantweightflowofgasorairduringagiventimeperiod.
UseFlowElement→Dischargeendofthecompressor
•VariableFlowEqualtoMake:Thisobjectiveismetinrelationtoasetpressurepointthatwilloptimizethe
process.
UsePressureElement→Suctionendofthecompressor
•VariableFlowEqualtoDemand:Someprocessesrequirethatavariableamountofgasbemovedasfastas
itisneededbyothercomponentsinthesystem
UsePressureElement→Dischargeendofthecompressor
IntroductiontoCentrifugalcompressors
ControlObjectives

12. Compressorconstruction
CasingDesign
12
•VerticallyCasingrequiresless
sealing
•Horizontallycasinghaseasier
access

13. 13
Openimpeller Semi-enclosed
impeller
Enclosedimpeller
CompressorConstruction
ImpellersandDiaphragms
Typesofimpellers
Diaphragms
•Anopenimpellerisusedforhighheadsandsmall-to-large-flow.
•Asemi-enclosedimpellerisusedforlargeflow.
•Inanenclosedimpeller,thegasisdrawnintotheeyeandflows
outtheedgeorrim.
•Thediaphragmsareusuallymadeof
castironorotherhardmetal,like
steel,anddonotrotatewiththeshaft.
•Adjacentwallsofthediaphragmsform
apassagecalledthediffuser.After
thegastravelsthroughthediffuser,it
entersthereturnpassagewhich
guidesitintothenextimpeller

14. CompressorConstruction
GuideVanesandBearings
14
GuideVanes Bearings
Theimpellersandshaftmustbefreetorotate,buttheymustnotmove
anyotherway.Damageandleakagecanresultfromerraticmotionof
theimpellersorshaft
•Theguidevanesinmulti-stagecentrifugal
compressorsareplacedattheendofthereturn
passageofthediaphragm.
•Theangleofflowaffectsthecharacteristic
performancecurveoftheimpeller

15. CompressorConstruction
BalancingDrums
15
Thebalancingdrumisattachedtotheshaftatthedischargeendofthecompressor.Oneendofthedrumisventedtothe
suctionendofthecompressor.Thepressureontheventedendisthesameasthesuctionpressure.Thenon-ventedsideof
thedrumisexposedtothegasatdischargepressure

16. Typeofseals
LabyrinthSeals
16
Thelabyrinthsealisasetof
metalringsorteeththatencircle,
butdonotcontact,theshaft.
Whenusingalabyrinthsealwithdangerousgas,itmustbe
ported.Theportisplacedonthesealbetweenthe
processgasandtheatmosphere.

17. Typeofseals
Restrictiverings&mechanicalcontactSeals
17
•Theringsaremadeoutoflowfrictionmetaland
areheldinpositionaroundtheshaftbystationary
ringcups.
•Theringcupsdonotcontacttheshaft.Leakage
overtheringispreventedbytheverticalcontact
betweentheringandthecup
RestrictiveRings Mechanicalcontact
❖Contactsealsmustbelubricatedto:
•Reducefriction.
•Carryawayheat.
•Sealtheshaftagainstleakage

18. Typeofseals
LiquidFilmSeals
18
•Thepressureoftheoilmustbeslightlyhigher
thanthepressureofthegas
•Becausetheoilinthetankhasitsownhead,itwillhave
itsownpressurethatwillensureoilflowtothebearings

19. Compressorsystems
Oilcirculation&coolingsystem
19
•Iftheoilsystemfailstodeliveroilto
thebearings,severedamagefrom
heatandfrictionmayresult,and
thebearingsmayfail
•Thegasiscooledoutside
ofthecompressor.Once
thegasiscooled,itis
returnedtothecompressor.
Coolingsystems
•thegasiscooledafteritleaves
thecompressor.Thegas
flowsthroughtheaftercooler
andonintotheflowline.

20. Compressorsystems
Safetydevices
20
Vents&Bypasses
•Ifthecompressornears
surge, the vent
automaticallyopensto
increasetheflow.This
flowincreasewill
preventsurging.
•Thebypassmoves
thegasfromthe
dischargebacktothe
suctionareaofthe
compressor
Speeddevices
•Anoverspeedtripisalways
locatedintheturbineshaft
•Servo-motorisdesigned
sothatwhentheturbine
beginstoslowdown,the
throttleisopened.Ifthe
turbinebeginstospeed
up,thethrottleisclosed.

21. Operatingcompressors
Compressorsconfiguration
21
•Inaseriessetup,thedischargeofthefirst
compressorfeedsintothesuctionlineofthe
next.
•Thecompressedgasthatentersthesecond
compressorisatahigherpressurethanwhen
itenteredthefirstcompressor
•
•
Thegasflowisdividedsothatallthegasdoesnot
flowthroughbothcompressors
Parallelcompressorsdrawtotheirfullcapacityfrom
acommonsourceofgasincreasingoverallflow
SeriesOperations ParallelOperations

22. Operatingcompressors
PerformanceFeatures
PositiveDisplacement:Theprincipleofcompressioninthistypeofcompressorsisbydecreasingthevolume.For
gases,asvolumedecreases,pressureincreasesknownascompression.
DynamicCompressors:Inthesecompressors,thegasesarefirstacceleratedi.e.velocityisincreased,thenits
madetoflowthroughincreasingcrosssectionarea,wherekineticenergyisconvertedintopressureenergyi.e.
pressureisincreased.
•DynamiccompressorsLessmaintenance
•Dynamiccompressorslowerefficiency.
Rule of Thumb:Dynamiccompressiontechnologyisbestsuitedforbaseloadrequirements,while
positivedisplacementcompressionisbettersuitedtovariableload.Forlargerflowsandvariabledemand
applications,acombinationofbothtechnologiesoftenhelpstoreachtheoptimalusageofcompressedair
whilesimultaneouslyreducingenergyconsumption.

23. Thanksforcoming!
HectorNguemaOndo