Measurements in the trade of LNGImproving measurement methods & standards 

Oswin Kerkhof, VSLokerkhof@vsl.nl

Botlek studiegroep, 7 april 2011

OutlineOutline

LNG custody transfer measurement

LNG quantity measurement – static versus dynamic

LNG quality measurement – sampling versus spectroscopy

R d i t t i ti h i t t?Reducing measurement uncertainties - why important?

Reducing measurement uncertainties – how to?

Metrology for LNG project

LNG Test & Technology Center (LNG TTC)LNG Test & Technology Center (LNG TTC)

LNG custody transferLNG custody transfer

LNG transport and custody transferLNG transport and custody transfer

Ocean tankertanker

Receiving Small production sites

Pipeline

terminal

Small Road

(incl. LBG)

gas

Fuel stations Local

ship tanker

(ship and road transport)

regasification point

Ships Trucks Buses

LNG custody transfer measurement processy p

Source: GIIGNL Custody transfer handbook, 3rd edition

What is the accuracy?What is the accuracy?

Measurement uncertainty total energy LNG

• Between 0.9% (GIIGNL) and 1% or more

Comparison with the case of oil or gas:

• Crude oil custody transfer 0.2 - 0.4% (mass)

• High pressure natural gas 0.6 - 0.7% (on energy)

LNG quantity – static vs dynamicLNG quantity – static vs dynamic

Static

• Ship tank level gauging

• Examples: Radar capacitive float laser

State-of-the-art technology

• Examples: Radar, capacitive, float, laser

Dynamic

• Flow meteringChallenging

• Flow metering

• Examples: ultrasonic, coriolistechnology

LNG quantity – static measurements

Tank based measurement : state‐of‐the‐art in LNG custody transfer

LNG quantity – static measurements

• Expanded uncertainty (k=2) 0.42%  (GIIGNL custody transfer handbook 3rd edition)• Ship based measurements• Tank strapping => tank deformation => errors in tank tables• Tank strapping => tank deformation => errors in tank tables• Tank level gauging: Floating, microwave radar, electrical capacitance, laser

Uncertainty sources consideredUncertainty sources considered

1. Gauge table2. Correction tables for list and trim3 Oth l ti ( i d h i d ift)3. Other volume corrections (e.g. sagging and hogging, drift)4. Volumetric temperature expansion coefficient of the tank and reference

temperature of the tank5. Expansion coefficient of the level gauge6 G t t di t ib ti ( l d d t f l l6. Gauge temperature distribution (relevance depends on type of level

gauge)7. Mean temperature of the dimensional structure of the tank8. Intrinsic uncertainty level gauge9 D ift i l l9. Drift in level gauge10. Procedure to measure trim and list (location, stability, traceability)

Uncertainty budget: volume unloadedvolume unloaded

See next slide

Examples from aExamples from a study by DNV (Det Norske Veritas)

Ambient/seawater temperature within ± 20 °C f f± 20 °C of reference temperature of gauge table (20 °C)

Uncertainty calculation shows the importance of correcting for ambient/seawater temperature for a Membrane tank

Uncertainty budget: level gaugelevel gauge

HorizontalHorizontal displacement of level gauge:Trim: d = 2 mList: d =1 mList: d 1 m

According to a study bystudy by Metropartner

Uncertainty calculation shows the importance of correcting for calibration and location-effect on trim and list

LNG quantity – dynamic measurements

Flow metering: state‐of‐the‐art in other hydrocarbon custody transfer

LNG quantity – dynamic measurements

• LNG flowmeters available and used in special projects, proces monitoring and custody transfer (unofficial) verification at LNG terminals

• Potential calibration uncertainty (k=2) with real LNG reference system ~0 2%Potential calibration uncertainty (k 2) with real LNG reference system  0,2%• Flowmeters as alternative for or verification of off‐shore tank measurements• For off shore LNG applications (FPSO – Floating Production Storage Offloading)• For small and mid‐scale LNG applications

Gas metering station in Jordania LNG allocation metering skid in Qatar LNG Floating Production Storage Offloading

LNG quality measurementsLNG quality measurements

Sampling

• Liquid line samplingE i ti

State-of-the-art technology• Evaporization

• Gas chromatography analysistechnology

Non-sampling

• Liquid line Raman spectrometryChallenging

• Liquid line Raman spectrometry• In-line measurement technology

LNG quality measurementsLNG quality measurements

Sampling systems

Raman spectroscopyRaman spectroscopy system

Reducing measurement uncertaintiesReducing measurement uncertaintiesHow important is that?

• 1% uncertainty on total value of global trade of LNG (200 mtpa in 2010)

= 440 M€/year (2010) 900 M€/year (2015)

• Mass balance considerations

Reducing measurement uncertaintiesReducing measurement uncertaintiesHow to do it?

• Volume - flow metering – potential for roughly factor two

D it i i f d t t ti l f hl f t t• Density - improving reference data – potential for roughly factor two

• Mass – flow metering – potential for roughly more than factor two

• Gross calorific value - improved samping techniques or Raman spectroscopy – improvement factor ???

Metrology for LNG project

• Developing traceability for LNG

Metrology for LNG project

Volumep g y

flow meters (WP1)• Testing and evaluating LNG

quantity metering systems (WP2)

WP5

Measurement GuidelinesMass

Density• Improving LNG composition

measurement systems (WP3)• Reducing uncertainties in LNG

density calculations (WP4)

WrittenStandards

Mass

density calculations (WP4)

• Improving LNG composition measurement systems (WP3)

Gross Calorific

Legal Metrology

y ( )• Reducing uncertainties in calorific

value calculations (WP4)Calorific

Value

Overall objectiveReduction of the measurement uncertainty by a factor twoEnergy

Metrology for LNG

W W W. L N G M E T R O L O G Y. I N F O

• Detailed project information• Objectives tasks activities• Objectives, tasks, activities• Progress reports, project results

• Project news• Photo gallery• Discussion forum• Publications and articles

• Project presentations and articles• Other LNG measurement articles• Other LNG measurement articles• Relevant standards and guidelines

Metrology for LNG projectMetrology for LNG project

WP1 Developing traceability for LNGDeveloping traceability for LNG

flowmeters

Traceability for LNG FlowmetersTraceability for LNG Flowmeters

A three step approach:

1. Primary standard2 S t f t di th f2. System for extending the range of

flowrates3 Full scale facilities3. Full scale facilities

1st step: Primary LNG mass flow standard1 step: Primary LNG mass flow standard

2nd step:2 step: 1st stage upscaling standard

RM RM

2nd stage information

RM

RM

RM

RM

RM

RM RM

RM

1st stage information

RM= Reference Meter

3rd step: Full scale facilities

Base of Design: LNG Test & Technology Center (LNG TTC)

3rd step: Full scale facilities

Ultrasonic master meters

Primary mass flow

TNO testing area

LNG Piston prover

Primary mass flowstandard (EMRP WP1)

1st stage upscalingstandard (EMRP WP1)

LNG compositiontesting area

standard (EMRP WP1)

Installation areaflowmeters under test

2nd and 3rd stage upscaling

Conclusies

Di LNG t d t f t l i b hikbDiverse LNG custody transfer systeem oplossingen beschikbaar maar …Veel ruimte voor verbetering

Nieuwe en verbeterde meetsystemen en methodenyVerbeterde metrologische infrastructuur

Nederland heeft grote ambities om LNG distributieland te wordenInvesteren in kennis op gebied van LNGInvesteren in kennis op gebied van LNGOntwikkelen van excellente kennis op gebied van LNG metingenBetrouwbaar meten staat aan de basis van handelsverkeer