This document discusses various types of compressors used in industrial processes. It describes centrifugal compressors, which are commonly used for medium to large gas flows at low to medium pressures. Typical components of a centrifugal compressor include impellers, casings, rotors, and bearings. The document also discusses factors that affect compressor performance such as inlet pressure, temperature, and molecular weight of the gas. Methods of capacity control and anti-surge control are outlined.

1. 04/02/200404/02/2004 HEMANTHEMANT 11
CENTRIFUGAL COMPRESSORSCENTRIFUGAL COMPRESSORS
N.B.HEMANT HUMARN.B.HEMANT HUMAR

2. 04/02/2004 HEMANT 2
CLASSIFICATION OF COMPRESSORSCLASSIFICATION OF COMPRESSORS
A x ia lly S p lit
R a d ia lly S p lit
I n t e g r a lly G e a r e d
C e n t r ifu g a l
( u p t o 1 5 0 0 0 0 m 3 / h r )
A x ia l
( flo w > 1 0 0 , 0 0 0 m 3 / h r )
M e d iu m t o la r g e flo w s
L o w t o m e d iu m p r e s s u r e
D y n a m ic
P is t o n
L a b y r in t h
D ia p h r a g m
R e c ip r o c a t in g
< 2 0 0 0 m 3 / h r
S c r e w
L o b e
R o t a r y
L o w t o m e d iu m flo w s
P r e s s u r e n o lim it a t io n
P o s it iv e D is p la c e m e n t
C o m p r e s s o r s

3. 04/02/2004 HEMANT 3
VARIOUS TYPES OF COMPRESSORS:VARIOUS TYPES OF COMPRESSORS:
 STRAIGHT THROUGHSTRAIGHT THROUGH
 STRAIGHT THROUGH – BACK TO BACKSTRAIGHT THROUGH – BACK TO BACK
 SIDE STREAM ( EXTRACTION / INJECTION )SIDE STREAM ( EXTRACTION / INJECTION )
 BARREL TYPEBARREL TYPE
 SINGLE STAGE COMPRESSORSSINGLE STAGE COMPRESSORS
 HIGH SPEED INTEGRALLY GEARED COMPRESORSHIGH SPEED INTEGRALLY GEARED COMPRESORS

4. 04/02/2004 HEMANT 4
Typical Construction
Centrifugal Compressor (Radial Split)
A- Casing
B-Diaphragm
Bundle
C-Rotor
D-Impellers
E-Balance Drum
I-Thrust Bearing
H-Journal Bearing
F-Thrust Collar
L-Labyrinth
M-Seals

5. 04/02/2004 HEMANT 5
TYPICAL CENTRIFUGAL COMPRESSORTYPICAL CENTRIFUGAL COMPRESSOR

6. 04/02/2004 HEMANT 6

7. 04/02/2004 HEMANT 7
GENERAL INFORMATION / CONSIDERATIONSGENERAL INFORMATION / CONSIDERATIONS
 CAPACITY RANGE FOR CENTRIFUGAL COMPRESSORS -CAPACITY RANGE FOR CENTRIFUGAL COMPRESSORS -
1,700 TO 170,000 m1,700 TO 170,000 m33
/hr/hr
 HORIZONTALLY SPLIT COMPRESSORS:HORIZONTALLY SPLIT COMPRESSORS:
 WITH NOZZLES ON THE BOTTOM HALF , MAINTENANCEWITH NOZZLES ON THE BOTTOM HALF , MAINTENANCE
WITHOUT DISTRIBING THE PROCESS PIPING.WITHOUT DISTRIBING THE PROCESS PIPING.
 WITH PRESSURES ABOVE 500 psig THESE COMPRESSORWITH PRESSURES ABOVE 500 psig THESE COMPRESSOR
CASINGS LOOSE THEIR SEALING CAPABILITYCASINGS LOOSE THEIR SEALING CAPABILITY
 VERTICALLY SPLI COMPRESSORS:VERTICALLY SPLI COMPRESSORS:
 MAINTENANCE WITHOUT DISTRUBING THE PROCESSMAINTENANCE WITHOUT DISTRUBING THE PROCESS
PIPINGPIPING
 FOR PRESSURES ABOVE 500 PSIG THIS TYPE OFFOR PRESSURES ABOVE 500 PSIG THIS TYPE OF
CASINGS SHALL BE USED.CASINGS SHALL BE USED.

8. 04/02/2004 HEMANT 8
GENERAL INFORMATION / CONSIDERATIONS (Contd.)GENERAL INFORMATION / CONSIDERATIONS (Contd.)
 NUMBER OF CASINGS FOR COMPRESSORS IS GENERALLYNUMBER OF CASINGS FOR COMPRESSORS IS GENERALLY
LIMITED TO 3LIMITED TO 3
 SINGLE STAGE COMPRESSORS:SINGLE STAGE COMPRESSORS:
 SIMILAR TO SINGLE STAGE, OVERHUNG C.F. PUMPS.SIMILAR TO SINGLE STAGE, OVERHUNG C.F. PUMPS.
 PRESSURE RATIO ~ 1.6PRESSURE RATIO ~ 1.6

9. 04/02/2004 HEMANT 9
SPECIFYING FLOW TO A COMPRESSOR MANF.SPECIFYING FLOW TO A COMPRESSOR MANF.
 MASS FLOWMASS FLOW
 IT IS DIFFICULT TO APPRECIATE SIZE OF COMPRESORIT IS DIFFICULT TO APPRECIATE SIZE OF COMPRESOR
 CONFUSION ON ACCOUNT OF WATER VAPORCONFUSION ON ACCOUNT OF WATER VAPOR
 ACTUAL FLOWACTUAL FLOW
 DISADVANTAGEOUS IN CASE OF SIDE LOAD COMPR.SDISADVANTAGEOUS IN CASE OF SIDE LOAD COMPR.S
 STANDARD FLOW / NORMAL FLOWSTANDARD FLOW / NORMAL FLOW

10. 04/02/2004 HEMANT 10
COMPRESSOR PERFORMANCE CALCULAIONCOMPRESSOR PERFORMANCE CALCULAION
WHY COMPRESSIBILITY FACTORWHY COMPRESSIBILITY FACTOR ::
 IDEAL GAS EQUATION : PV = RTIDEAL GAS EQUATION : PV = RT
 NO GAS CONFIRMS TO IDEAL GAS BEHAVIOUR.NO GAS CONFIRMS TO IDEAL GAS BEHAVIOUR.
 INTRODUCTION OF DEVIANCE PARAMETER TO APPLY THEINTRODUCTION OF DEVIANCE PARAMETER TO APPLY THE
IDEAL GAS EQUATION TO REAL GAS EQUATIONIDEAL GAS EQUATION TO REAL GAS EQUATION
 HENCE: PV = ZRTHENCE: PV = ZRT

11. 04/02/2004 HEMANT 11
CALCULATION OF COMPRESSIMILITY FACTORCALCULATION OF COMPRESSIMILITY FACTOR
 ASSUMPTION - LAW OF CORRESPONDING STATESASSUMPTION - LAW OF CORRESPONDING STATES
 CALCULATE REDUCTION PRESSURE FOR EACH COMPONENTCALCULATE REDUCTION PRESSURE FOR EACH COMPONENT
OF THE GAS COMPOSITION MULTYPLIED BY THE MOLEOF THE GAS COMPOSITION MULTYPLIED BY THE MOLE
FRACTIONFRACTION
 AND ADD ALL REDUCED PRESSURES TO FIND REDUCEDAND ADD ALL REDUCED PRESSURES TO FIND REDUCED
PRESSURE OF THE GAS MIXTUREPRESSURE OF THE GAS MIXTURE
Pr = P / Pc
Pc = Critical pressure
P = Pressure of the gas

12. 04/02/2004 HEMANT 12
 SIMILARLY CALCULATE REDUCED PRESSURE FOR EACHSIMILARLY CALCULATE REDUCED PRESSURE FOR EACH
COMPONENT OF THE GAS COMPOSITION MULTYPLIED BYCOMPONENT OF THE GAS COMPOSITION MULTYPLIED BY
THE MOLE FRACTIONTHE MOLE FRACTION
 AND ADD ALL REDUCED TEMPERATURES TO FIND REDUCEDAND ADD ALL REDUCED TEMPERATURES TO FIND REDUCED
TEMPERATURE OF THE GAS MIXTURETEMPERATURE OF THE GAS MIXTURE
 OBTAIN THE COMPRESSIBILITY FACTOR FROM THEOBTAIN THE COMPRESSIBILITY FACTOR FROM THE
COMPRESSIBILITY FACTOR CHARTCOMPRESSIBILITY FACTOR CHART
Tr = T / Tc
Tc = Critical Temperature
T = Temperature of the gas

13. 04/02/2004 HEMANT 13
CALCULATION OF MOL. WEIGHT, Cp AND KCALCULATION OF MOL. WEIGHT, Cp AND K
 MOL. WEIGHT CONTRIBUTION OF EACH COMPONENT = MOL.MOL. WEIGHT CONTRIBUTION OF EACH COMPONENT = MOL.
WEIGHT OF THE COMPONENT X MOLE FRACTIONWEIGHT OF THE COMPONENT X MOLE FRACTION
 ADD MOL. WT. CONTRIBUTION FOR ALL COMPONENTS TOADD MOL. WT. CONTRIBUTION FOR ALL COMPONENTS TO
OBTAIN THE MOL.WT. OF THE GAS MIXTUREOBTAIN THE MOL.WT. OF THE GAS MIXTURE
 Cp CONTRIBUTION OF EACH COMPONENT = Cp OF THECp CONTRIBUTION OF EACH COMPONENT = Cp OF THE
COMPONENT X MOLE FRACTIONCOMPONENT X MOLE FRACTION
 ADD Cp CONTRIBUTION OF ALL COMPONENTS TO OBTAINADD Cp CONTRIBUTION OF ALL COMPONENTS TO OBTAIN
THE Cp OF THE GAS MIXTURETHE Cp OF THE GAS MIXTURE
 K = Cp / ( Cp – 8.314 )K = Cp / ( Cp – 8.314 )

14. 04/02/2004 HEMANT 14
TYPICAL PERFORMANCE
CURVE
OF
CENTRIFUGAL
COMPRESSOR

15. 04/02/2004 HEMANT 15
SYSTEM RESISTANCE AND PERFORMANCESYSTEM RESISTANCE AND PERFORMANCE
N1
N2
N3
N4
CAPACITY
ΔPRESSURE

16. 04/02/2004 HEMANT 16
PERFORMANCE VARIATIONS:PERFORMANCE VARIATIONS:
 CHANGE IN INLET PRESSURECHANGE IN INLET PRESSURE
 POWER REQUIREMENT DIRECT PROPORTONALLY CHANGEPOWER REQUIREMENT DIRECT PROPORTONALLY CHANGE
 INLET FLOW ILL ALSO CHAGE IN THE SAME WAYINLET FLOW ILL ALSO CHAGE IN THE SAME WAY
 THE PEFORMANCE CURVE FALLS LOWER TO RATEDTHE PEFORMANCE CURVE FALLS LOWER TO RATED
 VARIATION IN INLET TEMPERATUREVARIATION IN INLET TEMPERATURE

PR. RATIOPR. RATIO INVERSELY PROPORTIONAL TO INLET TEMP.INVERSELY PROPORTIONAL TO INLET TEMP.
HENCE FOR LOWER TEMP. THE DISCH. TEMP. INCREASESHENCE FOR LOWER TEMP. THE DISCH. TEMP. INCREASES
 MASS FLOW INCREASES AND SO AS THE POWERMASS FLOW INCREASES AND SO AS THE POWER
 THE PEFORMANCE CURVE RISES ABOVE ORIGINAL CURVETHE PEFORMANCE CURVE RISES ABOVE ORIGINAL CURVE

17. 04/02/2004 HEMANT 17
PERFORMANCE VARIATIONS (Contd..):PERFORMANCE VARIATIONS (Contd..):
 VARIATION IN MOLECULAR WEIGHTVARIATION IN MOLECULAR WEIGHT
 PRESSURE RATIO DIRECTLY PROPORTIONAL TO MWPRESSURE RATIO DIRECTLY PROPORTIONAL TO MW
 DISCHARGE PRESSURE INCREASESDISCHARGE PRESSURE INCREASES
 POWER REQUIREMENT INCREASESPOWER REQUIREMENT INCREASES
 VARIATION IN Z AND Cp/Cv VALUESVARIATION IN Z AND Cp/Cv VALUES
 FOR AIR APPLICATIONS THESE VARIATIONS ARE VERYFOR AIR APPLICATIONS THESE VARIATIONS ARE VERY
LESS. SO NEGLIGIBLELESS. SO NEGLIGIBLE
 FALL IN COMPRESSIBILITY RAISES THE PERF. CURVEFALL IN COMPRESSIBILITY RAISES THE PERF. CURVE
 FALL IN Cp/ Cv ALSO RAISES THE PERF. CURVEFALL IN Cp/ Cv ALSO RAISES THE PERF. CURVE
 VARIATION IN RPM ( Hp DIR. PROP. TO NVARIATION IN RPM ( Hp DIR. PROP. TO N22
))

18. 04/02/2004 HEMANT 18
SURGE AND STONE WALLSURGE AND STONE WALL
 SURGE IS THE MINIMUM STABLE FLOW POINTSURGE IS THE MINIMUM STABLE FLOW POINT
 STONE WALL IS THE MAXIMUM STABLE POINTSTONE WALL IS THE MAXIMUM STABLE POINT
 BEYOND THE SURGE AND STONE WALL POINTS THEBEYOND THE SURGE AND STONE WALL POINTS THE
COMPRESSOR’S OPERATION IS UNPREDICTABLE.COMPRESSOR’S OPERATION IS UNPREDICTABLE.
 COMPRESSOR SURGE IS DAMAGING TO THE COMPRESSOR.COMPRESSOR SURGE IS DAMAGING TO THE COMPRESSOR.

19. 04/02/2004 HEMANT 19
ANTI SURGE CONTROL:ANTI SURGE CONTROL:
 HARDWARE REQUIRED FOR ANTI SURGE CONTROL:HARDWARE REQUIRED FOR ANTI SURGE CONTROL:
 RECYCLE PIPING LOOPRECYCLE PIPING LOOP
 ANTI SURGE VALVE WITH NECESSARY VALVEANTI SURGE VALVE WITH NECESSARY VALVE
ACCESSORIESACCESSORIES
 INSTRUMENTATION FOR MEASURING THE FLOWINSTRUMENTATION FOR MEASURING THE FLOW
THROUGH THE COMPRESSORTHROUGH THE COMPRESSOR
 INSTRUMENTATION MEASURING INLET & OUTLETINSTRUMENTATION MEASURING INLET & OUTLET
PRESSURES & TEMPERATURESPRESSURES & TEMPERATURES

20. 04/02/2004 HEMANT 20
ANTI SURGE CONTROLANTI SURGE CONTROL

21. 04/02/2004 HEMANT 21
ANTI - SURGE CONTROL:ANTI - SURGE CONTROL:

22. 04/02/2004 HEMANT 22
METHOD OF CAPACITY CONTROLMETHOD OF CAPACITY CONTROL
 SUCTION / DISCHARGE THROTTLINGSUCTION / DISCHARGE THROTTLING
 BYPASSBYPASS
 IGVsIGVs
 SPEED VARIATIONSPEED VARIATION

23. 04/02/2004 HEMANT 23
CAPACITY CONTROL BY SPEED VARIATION
Hea
d
Flow
Speed

24. 04/02/2004 HEMANT 24
COMPRESSOR MONITORING AND SAFETY EQPT.COMPRESSOR MONITORING AND SAFETY EQPT.
 BEARING / TEMPERATURE MANITORBEARING / TEMPERATURE MANITOR
 MEASUREMENT OF VIBRATIONMEASUREMENT OF VIBRATION
 SHAFT POSITIONSHAFT POSITION

25. 04/02/2004 HEMANT 25
HIGH SPEED CENTRIFUGAL COMPRESSORS:HIGH SPEED CENTRIFUGAL COMPRESSORS:
 CAPACITIES FROM 10 ACFM TO 100000 ACFMCAPACITIES FROM 10 ACFM TO 100000 ACFM
 POWER RANGING FROM 15 HP – 2500 HP OR MOREPOWER RANGING FROM 15 HP – 2500 HP OR MORE
 SPEEDS UPTO 5800 RPM TO 50000 RPMSPEEDS UPTO 5800 RPM TO 50000 RPM
 DIAMETER OF THE IMPELLERS FROM 5” TO 36”DIAMETER OF THE IMPELLERS FROM 5” TO 36”
 USED FOR LOW CAPACITIES AND HIGH HEAD REQUIREMENTSUSED FOR LOW CAPACITIES AND HIGH HEAD REQUIREMENTS
 TO DECIDE APPLICEBILITY OF HIGH SPED COMPRESSORS – USETO DECIDE APPLICEBILITY OF HIGH SPED COMPRESSORS – USE
BALJE’S CHARTBALJE’S CHART
 FOR PRESSURE RATIO – 1.005 TO 3.5FOR PRESSURE RATIO – 1.005 TO 3.5
 TYPICAL APPLICATIONS:TYPICAL APPLICATIONS:
 MOLECULAR SEIVE ABSORPTION / REGENERATIONMOLECULAR SEIVE ABSORPTION / REGENERATION
 VAPOR RECOVERY / BOGVAPOR RECOVERY / BOG
 GAS RECYCLE SYSTEMSGAS RECYCLE SYSTEMS
 CHLORINE, NITROGEN ETC.CHLORINE, NITROGEN ETC.

26. 04/02/2004 HEMANT 26
AXIAL FLOW COMPRESSORS:AXIAL FLOW COMPRESSORS:
 INCREASING TENDENCY FOR USE OF AXIAL COMPRESSORSINCREASING TENDENCY FOR USE OF AXIAL COMPRESSORS
 HIGHER EFFICIENCIES COMPARED TO RADIL TYPEHIGHER EFFICIENCIES COMPARED TO RADIL TYPE
 APPLICATIONAPPLICATION
 REFINERIES – CATALYTIC CRACKINGREFINERIES – CATALYTIC CRACKING
 BUTADIENE -6000 TO 150000 ICFM @ 20 -30 PSIG AIRBUTADIENE -6000 TO 150000 ICFM @ 20 -30 PSIG AIR
 NITRIC ACID PLANTSNITRIC ACID PLANTS
 AIR SEPARATION PLANTSAIR SEPARATION PLANTS
 BLAST FURNACESBLAST FURNACES

27. 04/02/2004 HEMANT 27