2013lect4 Pumping System of Fluid
30
PUMPING SYSTEM
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Transcript of 2013lect4 Pumping System of Fluid
PUMPING SYSTEM
RELIEF VALVES
PUMPING SYSTEM
STATIC SUCTION HEAD/SUCTION LIFT
PUMPING SYTEM
PUMPING SYSTEM
PUMP ENERGY
PUMP ENERGY = FRICTION ENERGY + ELEVATION ENERGY
Terminology used in pumps
Suction head. Refers to the vertical distance from the surface of water (including drawdown, if any) to centreline of the pump impeller.Discharge head. Is the vertical distance from the centreline of the impeller to point of discharge.Total Dynamic Head (TDH). Is the sum of the suction head, discharge head, hydraulic head losses and the velocity head.Drawdown. Is the lowering of water surface below the static level during pumping.
Terminology used in pumps
Static level. Is the water level before pumping begins.Hydraulic loss. Is loss due to pipe wall friction, elbow design, joints, gate valves, sudden reduction or enlargement of pipe size. This is expressed in its equivalent height or head of water loss.Discharge or capacity. Refers to the rate of flow or the volume of water pumped per unit time such as gallons per minute; cubic feet per second; cubic meters per minute; liters per second; etc.Performance curves. Is the variation of head with capacity at a constant impeller speed. It also includes efficiency and brake horsepower curves.
SUCTION LIFT
Pompa
1
2
h
gF
gV
gPPzzh
)
2)( 2
21212
0V0F0PjikaMax
2
2
Untuk fluida airh max = 34 ft=10m
gP
h atmosfir
max
P1= atmosfir
mftft
inlbf. s lbm .ft .
ft/s. lbm/ft, lbf/in,
gP
air
1034144232232362
7142
2
223
2
SUCTION LIFT ?
Pump
23
1
mengisi pompa dengan fluida untuk keperluan start awal
STARTING CENTRIFUGAL
Kenapa mesti dilakukan ?
PUMP-PRIMING ?
PERHITUNGAN TEKANAN PADA SUCTION
Pump
23
1
Diameter impeler 10 inRpm 1800Pompa penuh berisi air
2222
23
23 22222
rpm D)r(VVPP
22
22
2
223
23 411442323600
180012
102
362inlbf
inft
ft.lbm,s.lbf
smin
minftlbm/ft ,PP
23
3
2223 05,0lbm/ft 3,62lbm/ft 075,04141
inlbf
inlbf
inlbfPP
air
udara
m03010144232232362
0502
2
223
2
,ft,ft
inlbf. s lbm .ft .
ft/s. lbm/ft, lbf/ft,
gP
air
Pompa berisi air
Pompa berisi udara
Suction Lift
Berapa P2 ?
P 3= atmosferik
22 41inlbfP
22 050inlbf,P
Net Positive Suction Head (NPSH)
VaporP Vaporsuctionavailable
PP NPSH
g g
suctionP
h
suction Vaporrequired
P -PNPSH =
g
In order for the fluid not to vaporize Psuction must higher then Pvapor
NPSH is an amount pressure over the vapor pressure .
NPSH Net Positif Suction Head
Pump
23
1
02
222
1212 1
F
gVV
zzg
PP
Fg
Vhg
Pg
P
2
2212
NPSHg
Pg
P v
2
Fg
Vhg
PNPSHg
Pv 2
221
Fg
Vhg
Pg
PNPSH suctionv
2
221
-h = z2-z1
diabaikan dan 2
Jika 2
21 Fg
Vg
Pg
P v
hNPSH
gPPNPSH v
2
Q ft3/s
Bernouli point 1 to 2
gPv
Net Positive Suction Head available, NPSHa
NPSHa is a function of system design It is the excess pressure of the liquid (in ft) over its vapor pressure as it arrives at the pump suction, to be sure that the pump selected does not cavitate. It is calculated based on system or process conditions.
Static suction head, vertical distance between the eye of impeller and suction liquid level
Pressure head or Barometric
pressure of suction vessel
Vapor pressure head Friction head, friction and
entrance pressure losses on suction side
Fg
Vhg
Pg
PNPSH suctionv
2
221
Usually neglected
NPSHr function of the pump
operation.
Atmospheric Pressure - Vapor Pressure + Liquid Height - Friction in the Suction Line
CALCULATING TOTAL DYNAMIC HEAD (TDH)
100 GPM of HCL at 150 F
100 GPM of HCL at 150 F
Flooded Suction Application
NPSHA = Atmospheric Pressure (-) Elevation Correction (-) Vapor Pressure (+) Suction Head
Atmospheric Pressure = 33.96 ft. Elevation Correction for 2000 ft. = 33.96 ft. (-) 31.58 ft. = 2.38 ft
Vapor Pressure of HCl at 150 F (Assume VP of HCl = VP of Water) = 8.56 ft.
NPSHA = 33.96 ft.(-) 2.38 ft. (-) 8.56 ft. (+) 8.7 ft. = 31.72 ft
Suction Head = 8.7 ft.
CALCULATING NPSHA
CALCULATING TOTAL DYNAMIC HEAD (TDH)100 GPM of HCL at 150 F
Total Dynamic Head (TDH) = Elevation(ft) + Friction(ft)
Total Dynamic Head = TDH - TSH= 132.4' - 8.7' = 123.7'
Suction Static Head-------------------------- 10'
Friction Suction SideTotal Length of 3" Pipe----------------------17'
(1) 90 deg 3" Elbow = 7.7' of Pipe---------7.7'
(CHART)
(1) 3" Gate Valve = 1.6' of Pipe------------1.6'
(CHART)
Total Equivalent Length of 3"Pipe-------26.3'
Friction = 4.96 x 26.3 / 100--------------- 1.3'
(CHART)
Total Suction Head = 10’ - 1.30’= 8.7'
Discharge Static Head---------------------------60'
Friction Discharge SideTotal Length of 2" Pipe------------------------172'
(2) 45 deg 2" Elbow = 4.8'(2x2.4) of Pipe ---4.8'
(2) 90 deg 2" Elbow = 10.4(2x5.2)of Pipe---10.4'
(1) 2" Gate Valve = 1.1' of Pipe---------------1.1'
(1) 2" Check Valve = 14' of Pipe---------------14'
Total Equivalent Length of 2" Pipe ----------202.3'
Friction = 35.8 x 202.3/100-----------------72.4'
Total Discharge Head = 60’ + 72.4’ =132.4'
Find the Total Dynamic Head (TDH)
TDH = Total Discharge Head - Total Suction Lift
Fitting LossesEquivalent Length of Pipe in Feet
Pipe Diameter
GateValves Plug Globe Angle Check Foot
1.5" 0.9 - 45 23 11 392" 1.10 6.0 58 29 14 47
3" 1.6 8.0 86 43 20 644" 2.1 17 113 57 26 716" 3.2 65 170 85 39 77Pipe Diameter
Elbows Tube Turn
Tee Enlrg Contr
45 90 45 90 Strt Side 1:2 3:4 2:1 4:3
1.5" 1.9 4.1 1.4 2.3 2.7 8.1 2.6 1.0 1.5 1.02" 2.4 5.2 1.9 3.0 3.5 10.4 3.2 1.2 1.8 1.2
3" 3.6 7.7 2.9 4.5 5.2 15.5 4.7 1.7 2.8 1.7
4" 4.7 10.2 3.8 6.0 6.8 20.3 6.2 2.3 3.6 2.3
6" 7.1 15.3 5.8 9.0 10.2 31 9.5 3.4 5.6 3.4
Friction Drop ChartFriction Loss of Water in Feet per 100 Feet of Pipe
U.S. GPM
1"Pipe 2"Pipe 3"Pipe 4"Pipe 5"Pipe 6"Pipe
Vel Loss Vel Loss Vel Loss Vel Loss Vel Loss Vel Loss
10 3.72 11.7 1.02 0.50 0.45 0.07 - - - - - -
20 7.44 42.0 2.04 1.82 0.91 0.25 0.51 0.06 - - - -
30 11.15 89.0 3.06 3.84 1.36 0.54 0.77 0.13 0.49 0.04 - -
40 14.88 152 4.08 6.60 1.82 0.91 1.02 0.22 0.65 0.08 - -
50 - - 5.11 9.90 2.27 1.36 1.28 0.34 0.82 0.11 0.57 0.04
60 - - 6.13 13.9 2.72 1.92 1.53 0.47 0.98 0.16 0.68 0.06
70 - - 7.15 18.4 3.18 2.57 1.79 0.63 1.14 0.21 0.79 0.08
80 - - 8.17 23.7 3.65 3.28 2.04 0.81 1.31 0.27 0.91 0.11
90 - - 9.19 29.4 4.09 4.06 2.30 1.00 1.47 0.34 1.02 0.14
100 - - 10.2 35.8 4.54 4.96 2.55 1.22 1.63 0.41 1.13 0.17
110 - - 11.3 42.9 5.00 6.00 2.81 1.46 1.79 0.49 1.25 0.21
120 - - 12.3 50.0 5.45 7.00 3.06 1.72 1.96 0.58 1.36 0.24
130 - - 13.3 58.0 5.91 8.10 3.31 1.97 2.12 0.67 1.47 0.27
140 - - 14.3 67.0 6.35 9.20 3.57 2.28 2.29 0.76 1.59 0.32
150 - - 15.3 76.0 6.82 10.5 3.82 2.62 2.45 0.88 1.70 0.36
Suction Lift Application
SYSTEM CURVE OF PUMPING SYSTEM
•It represents the relationship between flow and hydraulic losses in a system in a graphic form.
•Since friction losses vary as a square of the flow rate, the system curve is parabolic in shape.
•Hydraulic losses in piping systems are composed of pipe friction losses, valves, elbows and other fittings, entrance and exit losses, and losses from changes in pipe size by enlargement or reduction in diameter.
System Curve
Select pump size that can work with the system requirement
SYSTEM CURVE
Pumps in series double the head at the same flow condition point. One pump discharge is piped into the suction of the second pump producing twice the
head capability of each pump separately. The second pump however must be capable of operating at the higher suction pressure which is produced
by pump number one.This mode of operation is a very cost effective way of overcoming high discharge heads when the
flow requirement remains the same
SERIES PUMPING
PARALLEL PUMPING
TDH FLOW
90' 0 GPM
87.5' 50 GPM
85' 100 GPM
80' 160 GPM
OPERATING POINT (A)
70' 300 GPM
TDH FLOW
90' 360 GPM
87.5' 410 GPM
85' 460 GPM
80' 470 GPM
OPERATING POINT (B)
87.5' 410 GPM
TDH FLOW
90' 360 GPM
87.5' 460 GPM
85' 560 GPM
80' 580 GPM
OPERATING POINT (C)
87.5' 460 GPM
3" & 4" pump4" pump3" pump
TDH FLOW
130' 100 GPM
120' 190 GPM
110' 280 GPM
100 360 GPM
OPERATING POINT (A)
85' 470 GPM
TDH FLOW
130' 200 GPM
120' 380 GPM
110' 560 GPM
100 720 GPM
OPERATING POINT (B)
105' 660 GPM
Parallel Pumping Identical Pumps
