Liquefaction of Natural Gas – How can fundamental R&D help the

Gas Technology Center NTNU-SINTEF

Liquefaction of Natural Gas – How can fundamental R&D help the industry?

Case studies from GTS

Geir Skaugen SINTEF Energy Research,

Trondheim, Norway

6th Annual LNG TECH Global Summit 2011 De Doelen, Rotterdam 3rd-5th October


Content of the presentation

The Gas Technology Centre at NTNU - SINTEF - What is GTS - Research areas and capabilities

Case Studies: - LNG Heat Exchanger Studies

• Multilevel experiments and modelling - Small scale LNG systems

• From laboratory experiments to installation onboard a gas carrier - LNG and Low temperature Energy chain - Future research tasks within LNG at GTS

http://www.ntnu.no/gass/


Gas Technology Centre NTNU - SINTEF Researchers NTNU • 75 professors • 135 Ph.D. researchers • 30 post.doc. researchers SINTEF • 200 research scientists

Students • Award 75% of all M.Sc. in

Norway’s gas-related industry

Cooperation • Virtual organisation • Tight links to industry • International network

Strategic partners • Statoil

Mission: • To act as a common

interface in gas technology R&D between NTNU- SINTEF and the marked:

Presenter

Presentation Notes

Sorry about this researcher-like slide, but a Center is much like a jigsaw puzzle where every part is important to draw a complete picture Virtual organisation means that all groups are located physically within their local departments Let us have a tour of some of the laboratories.


The Norwegian University of Science & Technology (NTNU) - and The SINTEF Group

Number of employees (2010):

NTNU 4.700 (Scientific 60%)

SINTEF 2.145 (Scientific 73%)

Students: 18.500 10.000 in Engineering & Science

A technological cluster with education, basic & applied research, innovations and business developments

- of large importance for Norway


SINTEF Building and Infrastructure SINTEF ICT

SINTEF Materials and Chemistry

SINTEF Technology and Society

SINTEF Energy Research SINTEF Fisheries and Aquaculture SINTEF Petroleum Research MARINTEK

SINTEF is a multidisciplinary research organisation with international top level expertise in specific fields

Presenter

Presentation Notes

SINTEF’s eight research institutes. The four in the left-hand column are in the SINTEF Foundation, others are research companies. All are part of the SINTEF group


Disciplines around Gas Technology Centre


R&D along the Natural Gas value chain

Reservoir technology (including CO2-injection) Gas transport (multiphase pipelines, LNG, LPG,

energy markets) Chemical conversion Gas processing Gas transport infrastructure and techno-economic

optimisation Fossil fuel hydrogen production, storage and

usage

Presenter

Presentation Notes

OK


Laboratory facilities

Refrigeration and Combustion Technology LAB - Multiphase flow of oil and gas - Heat transfer and pressure drop for gas mixtures in compact

geometries - Small scale laboratory prototype for liquefaction of Natural

gas - Oxy-fuel Combustion for Gas Turbines

Absorption LAB - Absorption of CO2, H2S and NOx

- Catalysts and absorbents

Membrane technology LAB - Membranes for hydrogen and CO2 separation

Hydrogen production, liquefaction and storage Fuel cell technology

Presenter

Presentation Notes

Internal coordination: Gass og samfunn; SFP-søknad (teknologi og økonomi; modellering og beslutninger under usikkerhet); integrerte energi og økonomi-analyser; internal funds 5MNOK/yr; NFR: ”Prosess”; CO2 + posisjonerling ift. Innovasjonsselskapet i Grenland; integrert system analyse; SFP-søknad Strategisk partner: extenal funding


1. Common strategies 2. Industrial relevance and involvement 3. Basic scientific methodology

NTNU & SINTEF A Strategic Model of Cooperation:

NTNU-personnel participates in SINTEF-projects

SINTEF-personnel participates in teaching at NTNU

Joint use of laboratories and equipment

Core Areas: - Education - Basic Research Core Area:

Strategic Research

Core Areas: - Contract Research - Applied Research


Strategic Research - Competence Building Projects for the Industry Some key characteristics: Long term projects 3-5 years Cooperation with leading international research partners and includes PhD

education Results are to be published in open scientific journals Minimum industry funding of 20% of total budget The industry is represented in the steering committee of the project "Enabling Low Emission LNG-systems" Project figures:

Duration 2009-2014 Total budget: 44 million NOK (With 61% from the research council)

2 industry partners and support from the Gas Technology Centre Educate 3 PhD candidates and 1 postdoc candidates within the field


Enabling low-emission LNG systems Fundamentals for multilevel modelling Focus towards fundamental phenomena occurring in

LNG equipment - Experimentally - By modeling

Unit design/operation in perspective of: - Fundamental phenomena - Robust modeling approach - Integration with the process

Process design and system analysis including: - LNG process optimizing taking into account detailed unit models - LNG process dynamics - Process evaluation methodology

LNG fundamental phenomena

LNG systems

LNG heat exchangers


Droplet and film phenomena (PhD and PostDoc)

To be able to model and predict heat exchanger shell-side flow, droplet and bubble and film interaction needs to be better understood, hence both experiments and numerical analysis is required.

instabilities and heat transfer for two-phase flow in confined geometries representing heat exchanger tube side phenomena.

Fundamental knowledge can be applied to build more accurate engineering models.


Droplet and film phenomena – experimental setup

Experiments conducted with water and with n-Pentane on a horizontal or a tilted flowing film


General and modular heat exchanger modeling framework

14

Generic tool with building blocks of: • fluid nodes • heat nodes • surfaces • thermal resistors

• splitters • mixers • flash units • flow restrictions

Surfaces: • geometry models • heat transfer/pressure drop models

Fluid nodes: • thermodynamic model • numerical and physical flow model

Example: Counter-flow HX with wall heat conduction


Use of detailed heat exchanger simulation models in an engineering flow-sheeting environment for static instability analysis


Process optimisation

Heat exchanger representation in process simulation and optimisation are most often:

- Black or grey boxes that provide the process input/output states - Some degree of ”zone-analysis” in a simplified manner - Using lump, composite warm and cold streams

Using a detailed heat exchanger model, a chosen design can be

validated and the process operability can be investigated in a more complete way

The focus of this presentation is to investigate heat exchanger design in terms of steady state instability, also referred to in literature as: Ledinegg type instability.

16


Industrial relevance Increased focus on compact and

energy efficient solutions

Compact, optimized LNG processes using are proposed and presented in literature are often based on using brazed aluminum heat exchangers (BAHX) only

A recent example: - The ExxonMobile EMR process.

- About 30 parallel cores (Denton 2010)

The issues of potential instability need to be addressed Presented at: 89th Annual GPA Convention,

21-24 March 2010, Austin , TX (Denton et.al)


Flow rate

Pre

ssur

e dr

op

All liquid

All v

apou

r

Two-phase

N-shape for upward boiling in a heat exchanger

Ledinegg instability in boiling services

An N-shape may occur in boiling services if an increase in flow rate results in a decrease in pressure- drop

Counteracting effects: - Increase in flow -> higher

pressure drop - Decrease in average void

fraction -> lower pressure drop

Combination: increased flow -> decrease in average void fraction may give an N-shape

18


Case: Optimised SMR process for liquefaction of natural gas

Cooling and liquefaction of 1 kmole/s NG from 25 to -155 °C

Optimisation of flow-rate, composition, and pressure levels to obtain minimum energy consumption with restrictions:

- 10 K superheat - 1.2 K minimum temperature approach (MITA)

With specifications: - External cooling to 25°C

19

25°CSingle phase vap

-155°CSubcooled

single phase liq

N2,C1,C2,C3,iC4 and nC4 flowrates

P1

P2

External cooling to 25°C

10K superheat

MITA=1.2 K

1 kmol/s(≈ 64 t/h)


Optimised process design with a fully designed heat exchanger

20

T NG -155 T LP -157.1 P LP 5.34 P HP 25.88

N2 0.0929 C1 0.2913 C2 0.3887 nC4 0.2271 MREFR (kmol/s) 3.15 MNG 1


Check for operability - Pressure drop vs. flow rate for the evaporating stream

21

MR LP

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Relative flow rate MR LP(-)

Pres

sure

dro

p (b

ar)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

Out

let v

apou

r fra

ctio

n

Pressure drop (bar)Vapour fraction (kg/kg)

Assumption for this simulation: Constant warm stream flow rates


Consequences of Ledinegg instability

22

Equal cold stream pressure drop with flow-rate split 42/58 (+/- 8%)

Individual temperature profile

Temperature profiles

-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

0 0.2 0.4 0.6 0.8 1

Relative length

Tem

pera

ture

LP MR – Under refrigerated

LP MR – Over refrigerated


Remedies for avoiding Ledinegg instabilities

Move the operating point within the blue line.

Get rid of the N-shape - Modify HX design, - Reduce outlet resistance - Increase inlet resistance - Avoid cold end pinch - (Reduce the heat load)

23

Flow rate

Pre

ssur

e dr

op

All liquid

All v

apou

r

Two-phase

N-shape for upward boiling in a heat exchanger


Example on modified design

Reduced heat flux for cold channels – increased surface while maintaining - or reducing the pressure drop…

24

MR LP

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Relative flow rate MR LP(-)

Pres

sure

dro

p (b

ar)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

Out

let v

apou

r fra

ctio

n

Pressure drop (bar)Vapour fraction (kg/kg)

HX 1 HX 2Core volume (m3) 31.7 107.0Heat transfer surface (m2) 26502 70255Average heat flux (W/m2) 2911 1073Mass flux (kg/m2 s) 62.7 19.4Design pressure drop (bar) 0.82 0.17

N-shape Yes No


Summary – on heat exchanger / process analysis

In cryogenic processes using fluids with low density and low latent heat, instabilities are more likely to occur

The risk of ending up with a design operating point in an unstable region is high, if

- processes are optimised based on composite curves and minimum temperature differences,

- the pressure drop vs flowrate curve exhibits an N-shape

When equipment with a high degree of parallelism is used, this could have serious consequences in terms of thermal stress or inefficient operation

There are currently 3 PhD studies on the topic of instability in heat exchangers at NTNU.

25


Small Scale LNG production – The SINTEF Mini-LNG concept – from laboratory to

installation onboard a gas carrier

Contact person on Mini LNG: Petter Nekså

([email protected])

26

• The Mini-LNG technology • General characteristics

• Re-Liquefaction plant, application example • Full scale plant analysis


NG liquefaction plants, capacity range

27

Mini-LNG LNG production: 3.5 – 35 kT/year (10 – 100 T/day)

Peak shaving LNG production: 35 – 150 kT/year

Base-load LNG production: 1500 – 5000 kT/year Hammerfest/Snøhvit 4300 kT/year (12500T/day)


The cost challenge of small scale LNG


The energy efficiency challenge of small scale LNG

SINTEF

Production capacity

E n er

gy e

ffice

ncy

Mini LNG Peak shaving Baseload

Magnetic cycle

Production capacity

E n er

gy e

ffice

ncy

Mini LNG Peak shaving Baseload

Magnetic cycle

Mini LNG


The SINTEF mini-LNG concept - Liquefaction Unit

Using standard equipment for low investment cost and fast manufacture of the liquefaction unit

- Copper brazed plate heat exchangers, withstands rapid temperature changes

- Lubricant injected screw compressors - Proven robust oil/lubricant management

Construction in steel frames: - Lower manufacturing cost - Faster manufacture time - Modular movable plant elements

Refrigeration cycle with mixed refrigerant (N2,C1,C2,C3,C4) for low energy demand

Adaptation of selected equipment, MR and operational conditions to given application and NG composition

30


From theory – laboratory - full scale

Theoretical - Process development and simplification - Analysis

Laboratory plant 1 tonnesLNG/d - Fully instrumented closed loop lab plant at SINTEF - Operation since 2003, 2000 h (500 continuous) - Lubricant tests, various operating conditions, rapid

start-up

Full scale test, 20 tonnesLNG/d - Design and construction - FAT test at SINTEF Tiller lab in Trondheim 2008 - Analysis of results - Installation onboard a gas carrier 2009

31

-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

0 10 20 30 40 50 60 70minutes

tem

per

atu

re 'C

0

5

10

15

20

25

30

35

40

45

50

flo

w k

g/h

temperatureflow

start

60

102

118

62

78120

2276

90

28

54

64

20

2624

46

52

58

74

114

116

117

104

86

40

100

77

1088

Simplified concept

HA-01

HA-07 HA-04

HA-02

LNG


-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

0 10 20 30 40 50 60 70minutes

tem

pera

ture

'C

0

5

10

15

20

25

30

35

40

45

50

flow

kg/

htemperatureflow

start

Mini-LNG liquefaction unit Rapid start and stop

Reading from laboratory plant 1 tonnes/d


Application example SINTEF Mini-LNG Reliquefaction of boil-off gas from a small IMS Multigas carrier using the Mini-LNG Techology

33

3D illustration of the tanker with the refrigeration system on the top deck

10.000 m3

Multigas



Plant design simulation results (mini-LNG) BOG NG with 89 mol% CH4, 11 mol% N2 (18 bara)

Boil-off gas liquefaction capacity 20 tonnes/d

LNG exit temperature (before throttling to tank) -155 oC

MR (at first vapour-liquid separator inlet) and NG pre-cooling temperature

-35 oC

Mixed refrigerant compressor pressure ratio 9.3 -

Mixed refrigerant compressor power consumption 395 kW

Estimated compressor isentropic efficiency 0.65 -

Mixed refrigerant actual suction volume 1520 m3/h

Specific suction volume 1.8 m3/kg LNG

Specific power consumption mini-LNG 0.47 kWh/kg LNG


Heat Exchanger HX 2, MR-HP/MR-LP, high temp Duty vs. Temperature

36

Heat Exchanger HA2 Zones Analysis

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

0 0,00005 0,0001 0,00015 0,0002 0,00025 0,0003 0,00035 0,0004Duty, x 10^6 kW

Tem

pera

ture

, C


Heat Exchanger HX 7, NG/MR-LP Duty vs. Temperature

37


Plant exergy loss analysis

38

HA221 %

HP MIXER0 %

HA434 %

HA727 %

FCV43 %

FCV52 %

LP MIXER7 %

FCV16 %

- Still considerable potential for reducing losses - Especially for compressor and heat exchangers - Dependent on component availability

Plant Coldbox


Full scale test results

Capacity difference relative to nominal (18.8 tonnes/d) 1) Corrected for leak in safety valve by-pass from high p to low p and

undersized stop valve in suction tube 2) Corrected to nominal precooling temperature (-35°C)

Some maldistribution in first secondary hx (HX 2) observed - Estimated influence on capacity 5 - 7 %

~ 14 %-points ~ 9 %-points

39

Parameter ………………………………………….. Unit .

Measured ….

Simulation …..

Simulation corrected 1)

(dp and leak)

Simulation corrected 2)

(precooling t)

Liquefaction capacity tonnes/d 14,4 14,4 17,1 18,8

LNG exit temperature before throttling to tank oC -154,1 -154,1 -155 -155

MR precooling temperature at vap-liq separtor oC -24,9 -24,9 -24,9 -35

NG precooling temperature oC -31,7 -31,7 -35 -35

Refrigerating capacity kW 70,7 84,3 93,2 Volume flow LP MR out of coldbox m3/h 1436 1512 1517

Results from full scale tests and simulation model verification Including simulation results for future plant operating conditions (corrects for off-design conditions at full scale tests)


Constraints and possible improvements

Some constraints today - NG pressure from BOG handling system 18 bar (balance BOG

compr./Mini-LNG) - Storage pressure in chain, carrier tanks can handle 5 bara - Design for high ambient temperatures - Sea water temperatures in north

of Europe relatively low - Availability of components

Efficiency improvements - Improved compressor efficiency - Reduced temperature differences in hx - Optimisation of MR composition

Plant operation without pre-cooling could be possible - Existing refrigeration system on-board is used for precooling today

40


Liquid Energy Chain Optimization

Contact person: Prof. Truls.Gundersen ([email protected])

Aspelund A. and Gundersen T. ”A Liquefied Energy Chain for Transport and Utilization of Natural Gas for Power Production with CO2 Capture and Storage − Part 1”, Journal of Applied Energy, vol. 86, pp. 781-792, 2009 .

Gas Technology Center NTNU-SINTEF T. Gundersen

LNG LNG LNG LIN CO2 CO2

A Liquefied Energy Chain (LEC)

Aspelund A. and Gundersen T. ”A Liquefied Energy Chain for Transport and Utilization of Natural Gas for Power Production with CO2 Capture and Storage − Part 1”, Journal of Applied Energy, vol. 86, pp. 781-792, 2009 .


A Liquefied Energy Chain (LEC)

Key Features of the “LEC” Concept ♦ Utilization of Stranded Natural Gas for Power Production ♦ High Exergy Efficiency of 46.4% (vs. 42.0% for traditional) ♦ Elegant and Cost Effective solution to the CCS Problem ♦ CO2 replaces Natural Gas injection for EOR ♦ Combined Energy Chain (LNG) and Transport Chain (CO2)


Simulation-Optimization of the entire LEC

LIN LCO2 LCO2

LNGLNG

The field site

process

Storage

The market site

process

NG LNG LNG NG

P1 F1

LCO2CO2 P2

P3LINN2

N2

Powerprocess

with CO2 capture Water

Electricity

LNG

CO2

The simple chainThe complete chain

Storage

LNG

LCO2

LIN

LCO2F2

LIN

K-100

P-102

V-101

T1

LIQ-EXP-101NG-1

NG-4

LIQ-EXP-102

NG-5

NG-6

NG-PURGE

P3

P-101

N2-2

N2-10

N2-11

N2-6

N2-3

EXP-101

EXP-102

P2F2

P-100

CO2-2

F1

K-101

CO2-3

N2-12

T2

T4P6

CO2-4

HX-101 HX-102

P1

P5

P4

NG-2

T3

N2-1

CO2-1

LNG

N2-5

N2-8

NG-3

N2-4

N2-7

N2-9

NG-1HX-102

P3 P-101

NG-3

P-102

HX-101

N2-8N2-9

EXP-101

NG-4

NG-5

NG @ 25

V-101 CO2-4K-107

CO2-5CO2-6K-108

CO2-7

F4

CO2-8

CO2-11

CO2-9

CO2-13

CO2-Recycle

4 stage compressionK101-K104

N2-1

VF1

V-102

P2

N2-12

T5

P1

EXP-102

N2-14

T6

N2-16

F2

F32 stage compression

K105-K106

CO2-1

F1

CO2-0

N2-0

LCO2

LIN

LNG

CO2-12

CO2-10

N2-10

N2-13

T7N2-15

NG-2

N2-11

Offshore Onshore


Optimizing the Liquefied Energy Chain First: Near-Optimal Design established by

♦ Domain Knowledge related to LNG ♦ Heuristic Design rules (new and old) ♦ Pinch Analysis (the Composite Curves) ♦ Exergy Analysis (calculating ηExergy) ♦ Rigorous Simulation by HYSYS (testing the Concept)

Second: Mathematical Programming and a novel (and innovative) Superstructure

♦ Offshore and Onshore Processes Optimized separately Third: Stochastic Search with Rigorous Simulation

♦ Referred to as “Simulation−Optimization” ♦ Taboo Search (global) and Nelder Mead (local) ♦ HYSYS providing Objective Function Values ♦ Applied Simultaneously to the entire Chain


Progress of the Optimization

28

29

30

31

32

33

34

35

36

0 50 100 150 200 250 300 350 4000

1

Best known objective Current best Local search

Myklebust J., Aspelund A., Tomasgard, A., Nowak M. and Gundersen T., “An Optimization-Simulation Model of a Combined Liquefied Natural Gas and CO2 Value Chain”, INFORMS Annual Meeting, Seattle,

November 2007


Future research tasks – Rapid Phase Transition (RPT)

What is RPT? - can occur if liquid natural gas is spilled on / and mixed with water - a physical explosion where unstable, superheated liquid instantaneously

expands to vapour phase and creates overpressure and pressure waves

- explosion impact often converted to tons of TNT

Increased attention in recent safety studies - increased use and transport of LNG - well researched, but still difficult to predict - complex chain of various physical phenomena - challenging in terms of scale-up from laboratory tests


Physics of RPT – single component


Future research tasks – Rapid Phase Transfer (RPT)

Plan to start up new 3 mill EUR project in 2012 – awaiting governmental financial support – still open for industry participation

- Both experimental and modelling approach are planned

2 PhD from NTNU from the mid 90's - pool boiling of hydrocarbon on water surface - mixing of cryogenic jet in water - fragmentation - modelling - spreading

Now: Utilize advances in measurement and visualization techniques and advances in modelling experience on fast transients on pressure wave propagation

x


Thank you for your attention! Gas Technology Centre: www.ntnu.no/gass www.sintef.no


Some selected references Nekså, P., Brendeng, E., Drescher, M. and Norberg, B. (2010): Development and

analysis of a natural gas reliquefaction plant for small gas carriers, J. of Natural Gas Science and Engineering, ISSN1875-5100, Vol 2 (2-3), pp 143-149

Nekså P., Brendeng E., Norberg B., Brøndum P., Drescher M. (2008), Development of a small scale natural gas reliquefaction plant for gas tankers, Proc. of the 8th IIR Gustav Lorentzen Conference on Natural Working Fluids, Copenhagen, Sept 8-10, ISBN 9782913149632, ISSN 0151-1637

Brendeng E., Neeraas B.O. (2000), Method and device for small scale liquefaction of product gas, E.P. patent no. 1255955, priority date 2000-02-10

Zhao, H., A. Brunsvold, et al. (2011). "Investigation of droplets impinging on a deep pool: transition from coalescence to jetting." Experiments in Fluids 50(3): 621-635.

Zhao, H., A. Brunsvold, et al. (2010). "An experimental method for studying the discrete droplet impact phenomena in a flammable gas environment." Journal of Natural Gas Science and Engineering 2(5): 259-269.

G. Skaugen*, G.A. Gjøvåg, P. Nekså, P.E. Wahl, "Use of sophisticated heat exchanger simulation models for investigation of possible design and operational pitfalls in LNG processes", Journal of Natural Gas Science and Engineering 2(5) 235-243

Aspelund A. and Gundersen T. ”A Liquefied Energy Chain for Transport and Utilization of Natural Gas for Power Production with CO2 Capture and Storage − Part 1”, Journal of Applied Energy, vol. 86, pp. 781-792, 2009

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Documents

Liquefaction of Natural Gas – How can fundamental R&D help the