Pump

PUMP

TM - FTTM

Pump (pendahuluan)

• Pumps have a prime of uses in the oilfield.

• Large pumps provide the pressure driving force needed to move oil through piping from point to point during its gathering, processing, and pipeline transport.

Pump

• Crude oil is stabilized by stage separation to or near atmospheric pressure for transportation and storage, before pumping.

• Main-line oil (MLO) pumps are required for pipeline transport or transfer pumps for delivery into other carrier or storage.

Background

• Large pumps are also needed for injection water and produced brine transport and disposal.

Background

• In the life of the field. Produced water must also be transported in the production facilities and possibly re-injected.

• Basically, Pumps convert the rotary motion of a prime mover into the linear motion of the liquid in the piping.

• As a secondary function, pumps occasionally serve to mix fluids.

Background• There are two basic classes of pumps: positive

displacement and centrifugal.

• Positive displacement pumps trap a portion of the liquid in a fixed volume and deliver it mechanically to a higher

pressure. The entrapment may be done by a reciprocatingpiston or plunger in a cylinder, or by a rotating slidingvane, or gear, or screw.

Head

o Significance of using Head instead of

Pressure

o Pressure to Head Conversion formula

o Static Suction Head, hS

o Static Discharge Head, hd

o Friction Head, hf

Double – Action Stroke in a Duplex Pump

SuctionSuction

DischargeDischarge

LIQUIDLIQUID

Single-action Stroke in a Triplex Pump

Suction

Discharge

Liquid

LS

Background

• Centrifugal pumps propel liquid in a smooth, uninterrupted stream.

• Centrifugal pumps accelerate the liquid by impellers and convert the induced kinetic energy of the liquid into pressure energy by an increase in cross-section.

Liquid flow path inside a centrifugal pump

Units

• In English engineering units, th. capacity of a pump is expressed in gpm (U. S. gallons per minute) at flow conditions. Work per unit mass is expressed in ft-lbf/lbm or ft or 'head‘.

• In SI unit, flows are expressed in cubic meters per second (m3/s), work per unit mass in kJ/kg, and work per unit time in W.

Centrifugal Pumps• The most common type of pump used in field handling of

crude oil.

• Centrifugal pumps operate reliably, require low maintenance, and are well-suited for automatic control.

• They produce smooth output flow and operate safely against partially closed control Valves safely against a closed valve for short time periods.

• Centrifugal pumps operate flexibly over a wide range of flow rates (from a few gpm to 100,000 bpd) at heads ranging from a few psi to 3,000 psi.

Sectional View of a Centrifugal Pump (Jackson, 1973)

General Components of Centrifugal Pump

Cut-away of a Pump Showing Volute Casing

Solid Casing

Suction and Discharge Nozzle Location

Horizontal Centrifugal Pump Cross Section

Typical Centrifugal-Pump Curves

Centrifugal Pump Performance Curve

Typical performance curve for centrifugal pumps

Characteristic Curves for 11½ in Impeller

Operating Point for Centrifugal Pump in a Piping System

Horizontal Multistage Centrifugal Pump, GPSA 1987

Parallel Pumps

Centrifugal pumps may be operated in parallel at the same head to provide greater capacity than a single pump.

Parallel flows are additive at the same head. Extreme care must be exercised that parallel pumps have identical, or nearly identical, performance curves.

Pumps connected in parallel / in series

Parallel Operation Matched Centrifugal Pumps

Parallel Operation mismatched Centrifugal Pumps

No Diameter Change Only

Speed Change Only Diameter & Speed Change

1

2

3

1

212 D

D Q Q

1

212 N

N Q Q

1

2

1

212 N

N x DD Q Q

2

1

212 D

D H H

2

1

212 N

N H H

2

1

2

1

212 N

N x DD H H

3

1

212 D

D bhp bhp

3

1

212 N

N bhp bhp

3

1

2

1

212 N

N x DD bhp bhp

IInitial Capacity, Head, break horse power, Diameter, Speed

New Capacity, Head, break horse power, Diameter, Speed

11111 N, D , bhp , H , Q

22222 N , D , bhp , H , Q

Series / parallel Combinations – Centrifugal Pumps

2 Pumps in Series

One Pump

2 Pumps in Parallel

Hea

d - F

eet

Series and parallel operation of Centrifugal Pumps

Sys. Friction

Net Positive Suction Head Required(NPSHR)

An important consideration in pump selection is

the so called net positive suction head required

(NPSHR), which is the head that must be supplied

at the pump inlet in order to avoid or minimize

cavitation.

TANK

Atm

. Pre

ss Vapor Pressure

Tank Suction (Fill) Line

Liquid (Water)

Centrifugal Pump

Static Head

NPSH Required

NPSH Available

NPSH at Tank

Tank Farm Line Sizing

NPSH Available ≥ NPSH Required by the Pump

Net Positive Suction Head Required(NPSHR)

If the pressure in the eye of the impeller falls below the

vapor pressure of the fluid, some vaporization occurs. At a

subsequent point in the pump, the pressure rises and

these bubbles collapse, creating sound pressure waves

(cavitation) that erode the pump impeller. Mechanical

damage may also be possible.

Flow Rate

NPS

HR

Pa

PZ

Water Level

PUMP

Outlet

L

Typical PD pumping system

Diameter

Centrifugal Pump performance data for speed

TANK

Atm

. Pre

ss Vapor Pressure


Liquid (Water)

Centrifugal Pump

Static Head

NPSH Required

NPSH Available

NPSH at Tank


NPSH Available ≥ NPSH Required by the Pump

TANK

Atm

. Pre

ss Vapor Pressure


Liquid (Water)

Centrifugal Pump

Static Head

NPSH Required

NPSH Available

NPSH at Tank


s.g2.31 x P - (ft) Press Static

s.g2.31 x P -

s.g2.31 x P FRICVatm

NPSH

Available

Pump by the required NPSH

TANK

Atm

. Pre

ss Vapor Pressure


Liquid (Water)

Centrifugal Pump

Static Head

NPSH Required

NPSH Available

NPSH at Tank


Vapor Press NPSH Available Meningkat

Pipa semakin panjang NPSH Available Menurun

Viscosity Liquid NPSH Available Menurun

Static Head NPSH Available Meningkat

No of Pump Operating Flow Rate3 100 %

2 75 %

1 50 %

Flow Rate NPSH100 % 15 feet

75 % 20 feet

50 % 27 feet

Pump combination produce the following rates :

NPSH available :

TANK

0.5 PSIAWater at 80 F

NPSHAvailable

AbsolutePress,(ft)

Vapor Press. (ft)

Line Loss, (ft)

Difference in elevation, ft= _ _ ±

Line Loss = 3 ft

10 ft - 0

Atmosphere14.7 psia

NPSH CALCULATION FOR SUCTION LIFT

Gravity Specific2.31 x psia) Pressure, ( (Feet) Pressure

Feet 19.7 10 - 3 - 12 - 33.9

10 - 3 - 1.0(2.31) (0.5) -

1.0(2.31) (14.7)

NPSH Available

NPSH available must be greater than NPSH Required by the PUMP

GASPRESSURE

52.2 PSIAN-BUTHANE

AT 100OF

Gauge Reading, 37.5 psi

8 fe

et -

0

Line Loss = 2.5 Ft

NPSH CALCULATION FOR LIQUID AT BOILING POINT

Specific gravity of N-Butane at 100 F = 0.56

Absolute Pressure = Gauge Pressure + Atmosphere Pressure = Gauge Pressure + 14.7

NPSH = Absolute - Vapor - Line ± Difference inAvailable Press, Ft Press, ft Loss, ft Elevation, Ft.

Feet 5.5

8 - 2.5 - 215.3 - 215.3

8 2.5 - 0.56

(2.31) (52.2) - (0.56)

2.31 14.7) - (37.5

NPSHAvailable


AirPRESSURE

0.5 PSIAN-BUTHANE

AT 100OF

Gauge Reading, 10 psi

5 fe

et -

0

Line Loss = 45 Ft

NPSH CALCULATION FOR LIQUID AT BOILING POINT

Specific gravity of Water = 1.0

Absolute Pressure = Gauge Pressure + Atmosphere Pressure = Gauge Pressure + 14.7

NPSH = Absolute - Vapor - Line ± Difference inAvailable Press, Ft Press, ft Loss, ft Elevation, Ft.

Feet 59.828

5 45 - 2.06 - 101.8875

5 45 - 0.56

(2.31) (0.5) - (0.56)

2.31 14.7) (10

NPSHAvailable


gg W-

ggF

g 2)V - (V ) Z- (Z )P - (P c

sc

21

22

1212

hpr + hst + hv + hf = hp

Pressure Head

Static Head

Velocity Head

Friction Head

Pump Head

gg W-

ggF

g 2)V - (V ) Z- (Z )P - (P c

sc

21

22

1212

hpr + hst + hv + hfric = hp

Pressure Head

Static Head

Velocity Head

Friction Head

Pump Head

Friction Loss : hfric

g 2V K

DL f

gg F h

2

i

cfric

f = Friction factor

L = Length of straight pipe

D = ID of pipe

∑ K = summation of resistance coefficients for all valve and fittings

V = velocity

gg W-

ggF

g 2)V - (V ) Z- (Z )P - (P c

sc

21

22

1212

hpr + hst + hv + hfric = hp

Pressure Head

Static Head

Velocity Head

Friction Head

Pump Head

c

2s

2d

fsfdsdf

12g 2

)V - (V )h (h )h - (h SG

2.31 x )P - (P H

H = Total Differential Head

E x 3960gravity specific x H x Q bhp

Q = Capacity, gpm

H = Total Head, ft

Bhp = break horse power

Where HL = head loss due to friction, ft L = length, ft

C = 140 for new steel pipe = 130 for new cast iron pipe = 100 for riveted pipe

d = pipe ID, in. gpm = liquid flow rate, gallons/minute

Q1 = liquid flow rate, bpd

85.187.4

85.11

L HCdLQ

Ldgpm

C

85.1

87.4

85.1

L100 0.00208 H

Hazen-Williams formula

P2 = 50 psig

P1 = 0 psigLiquid Level, Hs1

Liquid Level, Hs2

h = 35 ft

hd = 45 ft

hs = 10 ft

hs = - 10 ft

NPSHa = P1 + hs – hvp - hfs

H = (P2 – P1) x 2.31 / Sp.g + (hd- hs) + Hf + (Vd 2 – Vs 2) / 2gc

The tank is open to atmosphere, 0 psig = 34 ft water = P1, pumping water at 70F, hvp = 0.36 psi = 8 ft; from hs1 = ft.

NPSHa = 34 + 10 – 0.8 – 1 = 42.2 ft

Water

Water

Advantages of Centifugal Pump

• A centrifugal pump can be multistages• Discharge pressure may be increased by

increasing pump speed.• Increasing pump speed may increase

pump rate, if the pressure is held constant.• If the rate is held constant, a speed

increase will cause the pressure to increase.

Pump Application Sketch

E x 3960SG x H(ft) x Q(gpm) bhp


P2 = 50 psig


Liquid Level, Hs2

h = 35 ft

hd = 45 ft

hs = 10 ft

hs = - 10 ft


H = (P2 – P1) x 2.31 / Sp.g + (hd- hs) + Hf + (Vd 2 – Vs 2) / 2gc

The tank is open to atmosphere, 0 psig = 34 ft water = P1, pumping water at 70F, hvp = 0.36 psi = 8 ft; from hs1 = 10 ft, Hfs = 6 ft

NPSHa = 34 – 8 + 10 – 6 = 30 ft

Water

Water

P2 = 50 psig


Liquid Level, Hs2

h = 35 ft

hd = 45 ft

hs = 10 ft

hs = - 10 ft


H(ft) = (P2 – P1) x 2.31 / Sp.g + (hd- hs) + HF + (Vd 2 – Vs 2) / 2gc

Water

Water


85.187.4

85.11

F CdLQ H

Pump

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Transcript of Pump