1 - Pipeline Hydraulics-Basics

7/25/2019 1 - Pipeline Hydraulics-Basics

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Marine Pipelines - Hydraulics - 1

Pipeline Hydraulics - Basics

Gert van Spronsen - Pipelines

Shell Global Solutions International (SGSI) - Rijswijk

Email : [email protected] : +31 70 447 3427

2009 Shell Global Solutions International B.V. All rights reserved. Do not distribute without consent of copyright owner

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Pipeline Hydraulics - (single phase)

Session Objectives:

Review basics of pipeline hydraulics

Be able to perform single phase flow hydraulicscalculations

Liquid & Gas

Awareness of special subject - Heat transfer

3


Pipeline Hydraulics - Topics

Types of fluids and their properties

Density, viscosity

Liquid flow Darcy equation, Reynolds number, Friction factor

Gas flowAGA equation, Compressibility

Special subjects Heat Transfer

Shell - E&P Pipeline systems


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5


Key Parameters for Pipeline Hydraulics- Sizing a Pipeline

Flow - How much & what to transport Fluid quantity (flow rates) Fluid properties (composition or bulk properties)

Distance - How far & what are the conditions Distance & elevation Pipeline conditions (wall roughness, coatings, etc) Environmental conditions

Pressure - What is the available Pressure drop Available pressure vs. pump/compression power Pipeline Inlet/Outlet pressures

Flow

Distance

Pressure

6


Type of Fluids

Liquids Crude oil (waxy, heavy)

Condensate

Water

Gases Natural gas (lean, rich)

Two-phase Gas & Liquid

Natural gas & condensate

Crude & associated gas

7


Liquid Flow

Density

Viscosity

Vapour presure

Water content

Nasties CO2, H2S

8


Fluid Density (Definitions)

Density: [ kg/m3]

Specific Gravity (s.g.)or relative density rel

s = standard condition(15 C, 1.01325 bar)

Liquid API gravity : 5.1315.141

APIrel

=

s,air

s,gas

air

gas

relor

M

M

=

s,water

s,liquid

rel=


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9


Crude Oil Properties

Crude Country Density Viscosity (15 C) (40 C)kg/m3 cSt

Ekofisk Norway 804 2Arabian light Saudi Arabia 859 6Kuwait Kuwait 870 10Bintulu Sarawak 886 6

Schoonebeek Netherlands 904 200Langunillas Venezuela 967 800Boscan Venezuela 1,005 20,000

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Viscosity Variation with Temperature

Ekofisk (14) visc @40 C = 2 cSt

visc @10 C = 4 cSt

Bintulu (8) visc @40 C = 6 cSt visc @10 C = 15 cSt

Gamba (16) visc @40 C = 45 cSt visc @10 C = 100 cSt

Langunillas(22)

visc @40 C = 800 cSt visc @10 C = 10,000 cSt

11


Basic Flow Equations

L

Pi

Po

h

( )

...

22

.

.

2

.

5.0

5.0

accelevfrictotal

ioacc

elev

fric

PPPP

vvP

hgP

fd

LvP

++=

=

=

=

Friction

Elevation

Acceleration(=0 if d=constant)

Total

12


Elevation Pressure Loss

P = Elevation pressure loss Pa

= Liquid density kg/m3

g = Gravity constant m/s2

h = Pipeline elevation m

hgPelevation =


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13


Frictional Pressure Loss - Liquid Flow

fdLvP 22

1 =

Darcys equation

P = Frictional pressure loss Pa


v = Velocity m/s

Q = Volume flow m3/s

L = Pipeline length m

d = Pipe internal diameter m

f = Friction factor (Moody) (Fanning ff = 4x Moody ff)14


Frictional Pressure Loss - Liquid Flow

P = Frictional pressure loss Pa


v = Velocity m/s

Q = Volume flow m3/s

L = Pipeline length m

d = Pipe internal diameter m

f = Friction factor (Moody) (Fanning ff = 4x Moody ff)

fdLQf

dLvP

5

2

2

22

1 8

==

Darcys equation

15


Pipeline design basic rules:

Pressure drop proportional to Length Pressure drop proportional to Flow Squared Pressure drop inverse proportional to Diameter to 5th power

Flow capacity proportional to Diameter to 2.5th power

5

2""d

LQConstP

A. One additional Pump station - capacity 40% up

B. 10% more flow - pressure drop 20% upC. Decrease from 12 to 10 inch - pressure drop up 2.4 times

16


Friction Factor - Liquid Pipelines

F (Re, e /d) via Moody diagram

Re = Reynolds number v = Velocity m/s d = Pipe internal diameter m v = Kinematic viscosity m2/s (106 cSt)


= Dynamic viscosity Pa.s (103 cP)

e = Wall roughness m e /d = Relative wall roughness

dvdv==Re d


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Pipeline Wall Roughness

Roughness is either absolute () or relative ( /d)

Roughness is not a physical measurement

Significant effected by corrosion, erosion or waxdeposits

Typical values: Standard carbon steel 0.03 mm Heavily corroded steel 1.0 mm Internally coated pipe 0.01 mm Flexible pipe with inner carcass 250/d mm

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0.1

Laminarzone

Smooth pipes

Criticalzone

Transitionzone

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.025

.05

.04

.03

.02

.015

.01

.008

.006

.004

.002

.001

.0008

.0006

.0004

.0002

.0001

.00005

.00001

0.02

0.015

0.01

0.009

0.008103 1042 3 4 5 6 8 1052 3 4 5 6 8 1062 3 4 5 6 8 1072 3 4 5 6 8 1082 3 4 5 6 8

Complete turbulence, rough pipes

Turbulent zone

_ = .000 001

d_ = .000 005

d

Frictionfactorf

d

Relativeroughness

_

vd

vd

Reynolds number = =

Friction Factor- Moody Diagram

f = 0.019

RE = 8. 10^4

Rel.R = 0.00005

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Pumping Power

Ppower = Power requirement kW

Q = Throughput m3/s

P = Differential pressure kPa (over the pump)

= Pump efficiency

PQPpower

=

20


Gas Flow

= Density kg/m3

P = Pressure Pa

M = Molecular Weight kg/kmole

z = Compressibility (correction) Factor

R = Gas Constant J/kmole.K = 8314

T = Temperature K

TRz

MP=

Compressibility - Gas Density - function ofPressure

Z - Compressibility (correction) Factor for Non-Ideal Gases


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Z - factor - Charts (1)

M = 16.04 kg/kmol M = 17.40 kg/kmol

Molar mass = 16.04 kg/kmolpc= 4640 kPa (abs)Tc= 191 K

Temp, C1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000

Compressibilityfactor,z

Pressure, kPa (abs)

-50C

-70C

-25C

-10C

0C

10C

25C

50C

75C

100C

200C300C

500C

150C125C

Temp, C


1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000


Pressure, kPa (abs)

300C

200C

150C

100C75C

50C

25C

10C

0C

-20C

250C

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Temp, C1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000


Pressure, kPa (abs)

0C

-10C

10C

25C

50C

75C

100C125C

150C

250C350C

200C

Temp, C


1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000


Pressure, kPa (abs)

50C

25C

10C

0C

-20

C

75C

100C

150C

200C

250C

350C300C


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Temp, C1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000

Compressibility

factor,z

Pressure, kPa (abs)

10C

0C

25C

-10

C

50C

75C

100C

500C

350C

250C

150C

175C

200C

125C


Temp, C1.10

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0 5000 10000 15000 20000 25000 30000 35000

Compressibility

factor,z

Pressure, kPa (abs)

0C10

C25

C

50C

100C

75C

175C

125C

150C

225C

400C450C

300C350C

200C

250C

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Gas Flow Pressure Loss - AGA Equation

Pin = Inlet pressure MPa Pout = Outlet pressure MPa L = Pipe length m C = Constant = 5.7 x 10-10 MPa/K

f = Friction factor (Moody) (Fanning ff = 4x Moody ff) z = Additional Gas compressibility factor Tabs = Temperature K

st = Gas density at standard conditions kg/ m3 Q = Flow at standard conditions m3/s d = Pipe internal diameter m

5

222

d

QTzfC

L

PPstabs

outin=


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Gas Flow Pressure Loss - AGA Equation

Pin = Inlet pressure MPa Pout = Outlet pressure MPa L = Pipe length m C = Constant = 5.7 x 10-10 MPa/K

f = Friction factor (Moody) (Fanning ff = 4x Moody ff) z = Additional Gas compressibility factor Tabs = Temperature K st = Gas density at standard conditions kg/ m3

Q = Flow at standard conditions m3/s d = Pipe internal diameter m

2

5

22

outstabsin Pd

Q

TzfCLP +

=

26


Friction Factor - Gas Pipelines

F (Re, e/d) via Moody diagram

vac = Average velocity (actual conditions) m/s d = Pipe internal diameter m ac = Gas density (actual conditions) kg/m3

M = Gas molecular weight kg/kmole P = Pressure Pa z = Additional Compressibility factor R = Gas constant (8314) J/kmole.K T = Temperature K

= Dynamic gas viscosity Pa.s

dvRe acac=TRzPM=

27


0.1

Laminarzone

Smooth pipes

Criticalzone

Transitionzone

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.025

.05

.04

.03

.02

.015

.01

.008

.006

.004

.002

.001

.0008

.0006

.0004

.0002

.0001

.00005

.00001

0.02

0.015

0.01

0.009

0.008103 1042 3 4 5 6 8 1052 3 4 5 6 8 1062 3 4 5 6 8 1072 3 4 5 6 8 1082 3 4 5 6 8

Complete turbulence, rough pipes

Turbulent zone

_ = .000 001

d_ = .000 005

d

Frictionfactorf

d

Relativeroughness

_

vd

vd

Reynolds number = =

Friction Factor- Moody Diagram

f = 0.011

RE = 8. 10^6

Rel.R = 0.00005

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Hydraulics General


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Fittings Resistance Coefficient - K

L = 50D

L= 20

D

L= 60

D

L = 26D

90oElbow

Tee Flow Through Tee Flow Through Branch

45oElbow

Fitting resistance:Equivalent length as a function

of pipe diameter and fitting type

Leq = K d

Valves: Gate valve, K = 10

Check valve, K = 50 - 150

Leq = 50 d Leq = 26 d

Leq

= 60 dLeq

= 20 d

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Liquid & Gas Flow Summary

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Characteristics of Liquid Flow

P = f ( , + Q,d,L ) = f ( temperature ) = f ( temperature )

Liquid can be considered incompressible

No change in density

No change in velocity

Linearpressure drop

Independentof pressure level

Pressure

Oil

Length

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Gas

Pressure

Length

Characteristics of Gas Flow

P = f ( , + Q,d,L ) = f ( pressure, temperature ) = f ( pressure, temperature )

Gas is compressible

Density changeswith pressure

Velocity changeswith density

Non-linearpressure drop

Pressure drop depends on pressure level


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Summary Single Phase Hydraulics

Pressure Drop calculation Darcys equation for liquid

AGA equation for gas

Pipe wall roughness Roughness / Smoothness significant for gas

Smoothness less significant for liquid

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Heat Transfer

35


Key Parameters for Pipeline Heat Transfer

Pipeline surrounding Pipeline coating(s), buried - y/n, water/air

Ambient temperature

Pipeline dimensions Diameter, Length

Flowing conditions Flowrate, Specific heat

Non-flowing conditions Heat capacity of pipeline fluid Heat capacity of pipe & coating materials

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Pipeline Heat Transfer Schematic

Pipeline cooling under flowing conditions Pipeline fluid looses heat to surrounding Function of: heat transfer, heatflow & pipe dimensions

Pipeline

FlowQ

Soil Ta

x

Heat loss

Inlet

T = To


10/12

37


Pipe Heat Transfer Coefficient

Bd

38


Overall Heat Transfer Coefficient

39


Soil Heat Transfer Coefficient

Di Do

BdKsoil

Bd

D5.0H

H

H11LnD5.0

KU

0

2

i

soilsoil

=

+=

Usoil = Soil heat transfer coeff icient J/m2.s.C Ksoil = Soil thermal conductivity J/m.s.C Bd = Burial Depth (centre pipe) m

D = Diameter m i = internal o = outside

Not to be used ifBd < Do

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Soil Conductivity - Effect of Moisture


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Pipeline Temperature Profile Calculationat flowing conditions

T* = Dimensionless temperature T = Temperature C

x - at distance - x m i - inlet a - ambient

Q = Flowrate m3/s = Fluid density kg/m3

Cp = Specific heat capacity* J/kg.C dr = Reference diameter m U = Overall heat transfer coeff. J/m2.s.C

* Correct for more layers

y

x

ai

ax* eTTTTT

==

Ud

CQy

r

p

=

Where :

y = Characteristic heat transfer lengthi.e. length over which temperature is reduced by 63 %

42


Pipeline Cooling at non-flowing conditions

T* = Dimensionless temperature T = Temperature C

t - at time - t s i - inlet a - ambient

Q = Flowrate m3/s = Fluid density kg/m3

Cp = Specific heat capacity* J/kg.C dr = Reference diameter m U = Overall heat transfer coeff. J/m2.s.C

* Correct for more layers

==

t

ai

at eTTTTT*

U

Cd pr41

=

Where :

= Characteristic time for heat lossi.e. time over which temperature is reduced by 63 %

43


Example Temperature profiles

Gas

- Joule Thomson effect

Oil pipeline

44


Example Pipeline Cover - Effect of Dumping


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Fluid Temperature & Pipeline Surrounding

Sand Dumping

Commenced

Sand Dumping

Completed

Projected

Increased

Total Cover7300 m

2050 m Cover

from Wellhead

Instrumentation

Malfunction

3600 m Cover

from Platform

750 m Cover

from Wellhead

Crude Arrival Temperature

at Platform Riser

Dumping Operations-Days

25

20

15

10

50 5 10 15 20 25

46


Typical Thermal Conductivity & OHTC (Overall Heat Transfer Coefficient)

Coating W/m,C

Carbon steel 43.0

Stainless steel 21.0

Bitumen 0.7 Coal tar enamel 0.7 Polyethylene 0.4 FBE 0.2 Polyurethane foam 0.2 Syntactic foam 0.03

Concrete 1.0 - 1.5 Sand - wet 0.8 - 2.4 Sand - dry 0.4 - 1.0 Clay 0.3 - 1.2

Pipe, Coating and burial OHTCW/m2,C

36, 3 concrete 16

36, 3 con, buried 2 24, 2 concrete 23 24, 2 concr, buried 2.5

16, FBE 160 16, FBE, Buried 3.5 16, Syntactic foam 5 16, Pipe in pipe 1

12, FBE 160 12, FBE, Buried 4 12, Syntactic foam 5 12, pipe in pipe 1

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Pipeline Hydraulics Exercise Oil Pipeline Sizing

Oil Production 150,000 bbl/day 16 pipeline from Platform to onshore tank farm

Is the pipeline large enough?

Water depth at platform 167 m, deck 20 above sea level Onshore tank farm on a 30 m hill, tank 15 high

Crude oil density 42 oAPI Crude viscosity 0.01 Pa.s Ambient temperature 5 oC Pipeline Internal diameter 395 mm Pipe wall roughness 0.03 mm Pipeline design pressure 149 bara

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sometimes used for convenience where reference is made to these companies in general, or where no useful purpose is served by identifying a particular company.

Documents

1 - Pipeline Hydraulics-Basics