Technology for a better society 1

Øivind Wilhelmsen1, Michael Drescher1, Armin Hafner1, Gelein de Koeijer2

and Jan H. Borch2

a) SINTEF Energy Researchb) Statoil ASA, Research and Development

Presentation for TCCS-6, Trondheim, June 2011

Heat Transfer Characteristics of a Pipeline for CO2 transport

Technology for a better society

• Motivation• Description of the test facility• Example on results from the experimental investigations• Heat transfer characteristics of a CO2 pipeline surrounded by water• Future experiments• Conclusion and summary

2

Contents

Aim of the work: Improve the knowledge about the heat-transfer to pipelines for CO2 transport with fresh-water as the surrounding substance.

Technology for a better society 3

Motivation The Snøhvit-pipeline is 150 km, surrounded by different media such as sea-water, gravel, rock, with different heat transfer characteristics. The heat transfer will have large effect on the behavior of the pipeline in steady-state operations and potential accidents (such as blow-outs).

153 km, 8 inch300 m

2500 m

300 bar

Ca 150 bar, 5oC

2000 ton/day CO2

Ca 150 bar, 25oC

Orifice atsafe location

DHSV

153 km, 8 inch300 m

2500 m

300 bar

Ca 150 bar, 5oC

2000 ton/day CO2

Ca 150 bar, 25oC

Orifice atsafe location

DHSV

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Process flow diagram of the test facility

Tank

VesselSight glass

Cooling

Heating

Heating

Bypass for direct CO2

vapour return

Pipeline

Surrounding substance

13°

25 Wheater

T

P

P

F

T T

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Heat transfer test chamber

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Positions of temperature elements

Cross-section view

as seen from pipeline inlet

Thermoelement on steel pipeline

Thermoelement on insulation

Thermoelement inside water

CO2 Water

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Example on results from the exp. investigations

-10

-8

-6

-4

-2

0

2

4

6

8

1100 1110 1120 1130 1140 1150 1160Time unit [minute]

Tem

pera

ture

[°C

]

Temperature Pipeline out Temperature Pipeline inAverage water temperature Average temperature on outer insulationAverage temperature on outer steel

Boiling CO2 Steel

Insulation

Water

Temperature

Technology for a better society

• (1) Inner heat transfer coefficient: Free convection/boiling • (2) Thermal conductivity of the steel: Conduction through the pipewall• (3) Thermal conductivity of the insulation: Conduction through the insulation• (4) Outer heat transfer coefficient: Free convection

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Overall heat transfer coefficient through the tube, htot

outisosintot hkrrr

krrr

rhr

h1)/ln()/ln(1 323312

1

3 +++=

(1) (2) (3) (4)

r1

r2 r3

Insulation

Steel

Tout

Tin

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Inner heat transfer coefficient, hin

• Inner heat transfer coefficient varied between 140-180 W/m2K, which corresponds to a free convection regime (left).

B C D

Ts-Tsat

log(hin)

FRE

E C

ON

VE

CTIO

N

NU

CLE

ATE B

OILIN

G

TRA

NS

ITION

BO

LILING

FILM B

OILIN

G

A

Technology for a better society 10

Outer heat transfer coefficient, hout

0

50

100

150

200

250

0 1 2 3 4 5 6

h out

[W/m

2 K]

Experiment No.

Model

Exp

• Outer heat transfer coefficient varied between 170-220 W/m2K.

• Governing regime in the experimental facility is free convection.

• Heat transfer coefficient may be described by the empirical relation developed by Churchill and Chu [1] to within 10% accuracy.

[1] S.W. Churchill and H.H.S. Chu, Int. J. Heat and Mass Transfer, 18, 1049, 1975

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Future experiments

• Experimental investigation and modelling of: • Heat transfer with ice formation around the pipeline• Different surrounding substances such as:

• Salt-water• Gravel• Sand• Etc.

0

10

20

30

40

50

60

0

0,2

0,4

0,6

0,8

1

1,2

0 100 200 300

U [W

/m2K

]

Ice

Thic

knes

s [c

m]

Time [min]

Ice

U

Technology for a better society

• A test facility was built at Statoil’s research centre at Rotvoll in cooperation with SINTEF Energy Research using an actual piece of the Snøhvit-pipeline submerged in a container.

• Initial experiments with tap-water show that the test facility successfully can be used to measure the heat transfer characteristics of the pipeline.

• Outer heat transfer coefficient varied between 170-220 W/m2K and could be described with 10% accuracy by the empirical correlation for free convection by Churchill and Chu [1].

• Inner heat transfer coefficient varied between 140-180 W/m2K and the boiling regime inside the pipeline was governed by free convection.

• Future experiments will investigate the heat transfer characteristics of a pipeline for CO2-transport with ice formation, sea-water, gravel and other surrounding substances.

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Conclusion and summary