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Reciprocating
Compressor
Nazaruddin Sinaga
Efficiency and Energy Conservation LaboratoryDiponegoro University
RECIPROCATING COMPRESSORS
RECIPROCATING COMPRESSORS
CompressorsCompressors
HIGH LOWV. HIGH
NO NOYES
YESNO YES
LOW HIGH V. HIGH
YES NO NO
Pressure PPressure P
Flow Rate QFlow Rate Q
S .R .VS .R .V
EfficiencyEfficiency
Maint. costMaint. cost
PulsationPulsation
SurgingSurging
Reciprocating Centrifugal Axial
V. HIGH LOW LOW
LOW HIGH V. HIGH
Crosshead
Stuffing
Box
Packing
Discharge Valves
Suction Valves
PistonDistance Piece
Con-rodCrank
Piston Rod
Wiper
Rings
POWER END POWER END
GASEND
GASEND
FIXED CLEARANCE
VOLUME
VARIABLECLEARANCE
VOLUME
RECIPROCATING COMPRESSORS:FLOW RATE REGULATION
RECIPROCATING COMPRESSORS:FLOW RATE REGULATION
• VARIABLE CLEARANCE
• VARIABLE SPEED
• BYPASS
• SUCTION VALVE
UNLOADERS
CF CR
CF = C
CR = C
23
13
• VARIABLE CLEARANCE• VARIABLE CLEARANCE
C = Total Clearance Volume = CF + CR
Before operating Before operating
After operating After operating
CF CR
CF = C
CR = C
12
12
Point g suction valves open
C = Clearance volume
C
v
b
a
c
g
Pd
Ps c1M
EFFECT OF CLEARANCE VOLUME
EFFECT OF CLEARANCE VOLUMEAtAt
Point a suction valves closed
Point b discharge valves open
Point c discharge valves closed
Compression ratio
Pressure ratio )ABSOLUTE(P d
P s=
Volumetric efficiency =V a g
V cylinder a M
a g=
= V cylinder
V b M
C
vb a
c
g
Pd
Ps c1M
b
b M
a M =
C
v
Pd
Ps c1M
b
a
c
g
Volumetric efficiency =V a g
V cylinder a M
a g=
C
v
Pd
PsM
b
a
c
g
Volumetric efficiency =V a g
V cylinder a M
a g=
v
Pd
Ps M
C
g a
bc
Volumetric efficiency =V a g
V cylinder a M
a g=
If C Increased suction valves will open at ( g (
C
va
c
g
Pd
Ps
b
M
EV DECREASES
Q DECREASES
Volumetric efficiency =V a g
V cylinder a M
a g=
If C Decreased suction valves will open at ( d (
C
va
c bPd
Ps M g
EV INCREASES
Q INCREASES
Volumetric efficiency =V a g
V cylinder a M
a g=
•SUCTION VALVE
UNLOADERS
•SUCTION VALVE
UNLOADERS
STUFFING BOX
RIDER RINGSRIDER RINGS
PRESSURE RINGS
PRESSURE RINGS
WIPER RINGS
WIPER RINGS
T
R
TANGENTIAL RINGST
R RADIAL RINGS
RECIPROCATING COMPRESSORS
INTERMEDIATEPRESSURES
RECIPROCATING COMPRESSORS
INTERMEDIATEPRESSURES
Example 1
4 Stages Reciprocating Air comp has outlet pressure P4 = 80 barg
what are the intermediate pressures
P0
0 barg
1st
stage
P1
2nd stage
P2
3rd stage
P3 P4
80 barg
4th stage
P0
0 barg
P1 P2 P3 P4
80 barg
1st
stage2nd
stage3rd
stage
4th stage
R =P1
P0
P4
P3=
P3
P2=
P2
P1=
Assume
R is The equal Pressure Ratio between stages.
R = 4 P4
P0RT =
P4
P0BUT
RTR =
4
AND RT = P4
P0
R = RT4
Generally
R = RTN
P4 = R * P3 = 3 * 27 = 81 bara = 80 barg
P0
0 barg
P1 P2 P3 P4
80 barg
1st
stage2nd
stage3rd
stage
4th stage
RT = P4 / P0 = (80 +1) / (0 +1) = 81/ 1 = 81
N 4R = RT = 81 = 3
P1 = R * P0 = 3 * 1 = 3 bara = 2 barg
P2 = R * P1 = 3 * 3 = 9 bara = 8 barg
P3 = R * P2 = 3 * 9 = 27 bara = 26 barg
Example 2
3 Stages Reciprocating Gas compressor has Outlet pressure P3 = 127 barg Inlet pressure P0 = 1 barg
what are the intermediate pressures
P0
1 barg
1st
stage
P1
2nd stage
P2
3rd stage
P3
127 barg
P0
1 barg
1st
stage
P1
2nd stage
P2
3rd stage
P3
127 barg
Assume
P3
P2=P1
P2=R
P1
P0
=
RTP3
P0
=3
RP3
P0
=BUT
3R
P3
P0
=
R = RT3 3
R = RT
P3 = R * P2 = 4 * 32 = 128 bara = 127 bar g
3R = RT = 64 = 4
=)127+ 1(
)1+1(=
1282 = 64
P1 = R * P0 = 4 * 2 = 8 bara = 7 bar g
P2 = R * P1 = 4 * 8 = 32 bara = 31 bar g
P3
P0
3R=RT =
Example 2
3 Stages Gas compressor has Outlet pressure = 255 bar gInlet pressure = 3 bar g
What are the intermediate pressures
P0
3 barg
1st
stage
P1
2nd stage
P2
3rd stage
P3
255 barg
P0
3 barg
1st
stageP1
2nd stage
P2
3rd stage
P3
255 barg
P3 = R * P2 = 4 * 64 = 256 bara = 255 bar g
3R = RT = 64 = 4
=)255+ 1(
)3+1(=
2564 = 64
P1 = R * P0 = 4 * 4 = 16 bara = 15 bar g
P2 = R * P1 = 4 * 16 = 64 bara = 63 bar g
P3
P0
3R=RT =
REFERENCES
1. L. Nelik. Centrifugal and Rotary Pumps: Fundamentals with Applications,
CRC Press, Boca Raton, 1999.
2. Sulzer Pumps. Centrifugal Pump Handbook, 3rd edition, Sulzer Pumps
Ltd., Winterthur, Switzerland, Elsevier, 2010.
3. S. L. Dixon and C. A. Hall. Fluid Mechanics and Thermodynamics of
Turbomachinery, 6th Edition, Elsevier Inc., Amsterdam, 2010.
4. M. P. Singh and G. M. Lucas. Blade Design and Analysis for Steam
Turbines, McGraw-Hill Companies, Inc., 2011.
5. M. P. Boyce. Gas Turbine Engineering Handbook, 3rd edition, GPM,
Houston, Texas, 2005.
6. C. Soares. Microturbines: Applications for Distributed Energy Systems,
Elsevier, Amsterdam, 2007.
7. A. S. Leyzerovich. Wet-Steam Turbines for Nuclear Power Plants,
PennWell Corporation, Tulsa, Oklahoma, 2005.
8. S. Yedidiah. Centrifugal Pump User's Guidebook: Problems and Solutions,
Chapman & Hall, New York, 1996.
9. M. L. Adams Jr. Power Plant Centrifugal Pumps Problem Analysis and
Troubleshooting, CRC Press, Boca Raton, 2017.