05-Sundyne Presentation Fs Npsh
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Transcript of 05-Sundyne Presentation Fs Npsh
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NPSH
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NPSH
NET
POSITIVE
SUCTION
HEAD
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DEFINITIONS
NPSH A AVAILABLE (System)
NPSH R REQUIRED (Pump)
IF NPSHA < NPSHR,CAVITATION OCCURS
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ON SITE CASE
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ON SITE CASE
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NPSHR?
NPSHA? P VAP
P LIQUID
HEAD
DISTANCE A B C D E
A : PUMP SUCTIONB : INDUCER INLETC : IMPELLER INLETD : DIFFUSER THROAT INLETE : PUMP DISCHARGE
NPSHA
B
C D E
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HEAD
DISTANCE A C
F
G
F = NPSHAG = NPSHR
P VAP
GAS BUBBLES APPEAR & ... IMPLODE
NPSHA < NPSHR
P LIQUID
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HEAD
DISTANCE A B C D E
INDUCER EFFECT A : PUMP SUCTION
B : INDUCER INLETC : IMPELLER INLETD : DIFFUSER THROAT INLETE : PUMP DISCHARGE
INDUCER EFFECT
P LIQUID
P VAP
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HEAD
DISTANCE A C
GF
F = NPSHAG = NPSHR
B
NPSHA > NPSHR
P LIQUID
P VAP
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NPSHA CALCULATION
STATICHEAD
SURFACEPRESSURE
HEADFRICTIONLOSSES VAPORPRESSURENPSHA = + - -
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NPSHA OPEN TANK
STATICHEAD
SURFACEPRESSURE
HEADFRICTION
LOSSES VAPOR
PRESSURENPSHA = + - -
0 BARGOPEN TANK
WATER
Line losses:
0,8 m
TEMPERATURE = 80 C PRESSURE AT TOP = 0 barg or 1 Bara VAPOR PRESSURE AT 80
C = 0,47 Bara SPECIFIC GRAVITY = 0.97 @ 80
CH = 2,5m
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NPSHA OPEN TANK
STATICHEAD
SURFACEPRESSURE
HEADFRICTION
LOSSES VAPOR
PRESSURENPSHA = + - -
2,50 m
TEMPERATURE = 80
C PRESSURE AT TOP = 0 barg or 1 Bara VAPOR PRESSURE AT 80
C = 0,47 Bara SPECIFIC GRAVITY = 0.97 @ 80
C
0 BARGOPEN TANK
WATER
Line losses:
0,8 m
H = 2,5m
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NPSHA OPEN TANK
SURFACEPRESSURE
HEADFRICTIONLOSSES VAPORPRESSURENPSHA = + - -
1Bara x 10.20.97
2,5m
TEMPERATURE = 80
C PRESSURE AT TOP = 0 barg or 1 Bara VAPOR PRESSURE AT 80
C = 0,47 Bara MASS DENSITY = 970 kg/m 3 @ 80
C
0 BARGOPEN TANK
WATER
Line losses:
0,8 m
H = 2,5m
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NPSHA OPEN TANK
FRICTIONLOSSES VAPORPRESSURENPSHA = + - -
0,8m
10,5m
TEMPERATURE = 80
C PRESSURE AT TOP = 0 barg or 1 Bara VAPOR PRESSURE AT 80
C = 0,47 Bara SPECIFIC GRAVITY = 0.97 @ 80
C
0 BARGOPEN TANK
WATER
Line losses:
0,8 m
2,5m
H = 2,5m
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NPSHA OPEN TANK
VAPORPRESSURENPSHA = + - -
0.47Bara x 10.2
0.97
0,8m
TEMPERATURE = 80
C PRESSURE AT TOP = 0 barg or 1 Bara VAPOR PRESSURE AT 80
C = 0,47 Bara SPECIFIC GRAVITY = 0.97 @ 80
C
0 BARGOPEN TANK
WATER
Line losses:
0,8 m
10,5m2,5m
H = 2,5m
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STATICHEAD
SURFACEPRESSURE
HEADFRICTIONLOSSES VAPORPRESSURE
NPSHA CLOSED TANK
NPSHA = + - -
TEMPERATURE = 38 C PRESSURE AT TOP = 2,5 barg or 3,5 bara VAPOR PRESSURE AT 38
C = 3,6 bara SPECIFIC GRAVITY = 0.56 @ 38
C
N-Butane
Gas 2,5 barg
Line losses:0,8m
2,5m
H = 2,5m
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SURFACEPRESSURE
HEADFRICTIONLOSSES VAPORPRESSURE
NPSHA CLOSED TANK
NPSHA = + - -2,5m
3.7 Bara x 10.2
0.56 TEMPERATURE = 38 C PRESSURE AT TOP = 2,7 barg or 3,7 bara VAPOR PRESSURE AT 38
C = 3,6 bara SPECIFIC GRAVITY = 0.56 @ 38
C
N-Butane
Gas 2,7 barg
Line losses:0,8m
H = 2,5m
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FRICTIONLOSSES
VAPORPRESSURE
NPSHA CLOSED TANK
NPSHA = + - -67,4m
0,8m
TEMPERATURE = 38 C PRESSURE AT TOP = 2,5 barg or 3,5 bara VAPOR PRESSURE AT 38
C = 3,6 bara SPECIFIC GRAVITY = 0.56 @ 38
C
N-Butane
Gas 2,5 barg
H = 2,5m
Line losses:0,8m
2,5m
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VAPORPRESSURE
NPSHA CLOSED TANK
NPSHA = + - -0,8m
3.6 Bara x 10.2
0.56
67,4m2,5m
TEMPERATURE = 38 C PRESSURE AT TOP = 2,5 barg or 3,5 bara VAPOR PRESSURE AT 38
C = 3,6 bara SPECIFIC GRAVITY = 0.56 @ 38
C
N-Butane
Gas 2,5 barg
H = 2,5m
Line losses:0,8m
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65,5m
NPSHA CLOSED TANK
NPSHA = + - -
NPSHA = 3,6m
0,8m67,4m2,5m
TEMPERATURE = 38 C PRESSURE AT TOP = 2,5 barg or 3,5 bara VAPOR PRESSURE AT 38
C = 3,6 bara SPECIFIC GRAVITY = 0.56 @ 38
C
N-Butane
Gas 2,5 barg
H = 2,5m
Line losses:0,8m
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HOW TO INCREASE NPSHA
INCREASE SUCTION VESSEL PRESSURE
DECREASE VAPOR PRESSURE
( DECREASE SUCTION TEMPERATURE)
DECREASE LINE LOSSES
INCREASE STATIC HEAD
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NPSH TESTING
SET FLOW RATE, DETERMINE DIFFERENTIAL PRESSURE
REDUCE SUCTION PRESSURE (APPLY VACUUM)
WHEN DIFFERENTIAL PRESSURE DROPS BY 3% UNIT ISCAVITATING
NPSHA FOR THIS OPERATING CONDITION IS EQUAL TONPSHR
NPSHA = NPSHR
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INDUCER PERFORMANCE
"GENTLE" BREAKDOWN
3% PUMP SUPPRESSION 1% SUPPRESSION
"SHARP" BREAKDOWN
100%
97%
ADEQUATE NPSH
A P U M P O
R I N D U C E R
H E A D R I S E
NPSH
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THE INDUCER FAMILY
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THE INDUCER FAMILY
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WHAT DOES THIS HAVE TO DO WITH PUMPMAINTENANCE?
INDUCER OR IMPELLER CAN FAIL MECHANICALLY
RESULTING HSSA UNBALANCE CAN LEAD TO BEARING FAILURE
IDENTIFICATION OF CAUSE REDUCES MAINTENANCE
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CAVITATION EFFECT ON AN IMPELLER INCASE OF INSUFFICIENT NPSH MARGIN
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CAVITATION EFFECT ON INDUCER
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FLUID TEMPERATURE RISE
TEMPERATURE RISE FROM SUCTION TO DISCHARGE - RESULTOF INEFFICIENCY
TYPICALLY OF LITTLE OR NO CONCERN
OF CONCERN IN CLOSED LOOP SYSTEM WITHOUT COOLING
OR WHEN NPSH IS MARGINAL
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HEAD
DISTANCE A B C D E
A : PUMP SUCTIONB : INDUCER INLET
C : IMPELLER INLETD : DIFFUSER THROAT INLETE : PUMP DISCHARGE
INDUCER EFFECT
TEMPERATURE RISE INFLUENCE
P LIQUID
P VAP
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FLUID TEMPERATURE RISE RESOLUTION
INCREASE BYPASS TO SUCTION VESSEL
VENT PORT #6 TO SUCTION VESSEL
INCREASED EFFICIENCY LEADS TO DECREASED INTERNAL
RECIRCULATION (OPERATE NEAR BEP)
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TO REMEMBER
What is NPSH?
How to calculate it?
What is the effect of an inducer?
What is cavitation?