LNG Mass Flow Standard

Improving the “kilogram” for LNG

Dushyant Parkhi

Flow Engineer

VSL

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- Why do we need mass flow calibration standards

for LNG?

- What is the role of VSL in LNG

• Goal

• Road Map

- How will the goal be reached?

• LNG-Primary Scale Loop (PSL)

• LNG-Mid Scale Loop (MSL)

Outline

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Reliable measurements

Why calibration standards?

LNG Tank gauging system volume flow meter

Best Uncertainties

±0.5% Expected Uncertainties

~ 0.15%

mass flow meter

LNG Custody Transfer :

Trust in Trade

Legal

Requirements

Contractual

Requirements

Commodity Market

LNG as transport fuel

production, storage and

offloading (FPSO) vessels

Based on guidelines

: GIIGNL

used for allocation and control but not for

custody-transfer measurement.

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Role of VSL in LNG

SI

SI

National/

Primary

Standards

Secondary / Working

Standards

Instruments in the field

BIPM

VSL

Manufacturers

End users

Metrological traceability requires an established calibration hierarchy.

VSL and/or

calibration

laboratories

Calib

ratio

n h

iera

rchy

Fro

m s

mall to

hig

her u

ncerta

inty

calibration hierarchy

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Goal of VSL:

SI

SI

National/

Primary

Standards

Secondary / Working

Standards

Instruments in the field

Get measurement

uncertainty for the

LNG “kilogram”

below 0.1%

Realization of an gravimetric LNG mass flow standard and

calibration facility

Requirements:

Page

Small scale LNG -

LNG as transport

fuel

Primary mass flow standard Mid-scale mass flow standard

Mid-scale volume

flow standard

2014 2009 2015

LNG Composition

calibration systems

Primary Density

standard

Large scale LNG -

Production and

regasification plants

2018

Large scale

flow

standards

2013

LNG Composition

evaluation state-of-

the-art

Improved density correlations /

Improved Equations of State

Traceable LNG

custody transfer

measurements

Clear uncertainty

budgets

Uncertainty reduction

by factor two

Ship tank volume

measurements

uncertainty evaluation

TARGETS

TRIGGERS New LNG applications

with New Business

Models

Methane Number

harmonization / ISO

Road Map:

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Execution:

Three Step Approach

Primary flow Standard

Mid-scale flow standard

Full scale facilities

10 - 25 m3/hr 4 -12 ton/hr

5 – 200/400 m3/hr 2 – 100/200 ton/hr

200 - 4000 m3/hr 100– 2,000 ton/hr

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Step1: Primary Flow Standard

(PSL)

Calibration and Measurement Capability: Q ~ 10 - 25 m3/hr CMC ~ 0.15%

Supplying

tank

Weighing

tank MUT

Scale

Pump MUT

Page

Flow meter to be calibrated Reference for

calibrations

Weighing tank

Supplying tank

Pump

LNG-PSL Description

Fixed connection

causing non-

constant forces on

scale

Partly undefined

direction of flow

during switch over

Uncertainty in mass

collected between

MUT and

Reference

Uncertainty Sources

Description: Parts

Description: Process

Description: Sources of uncertainties

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Step1a: PSL-Improvement

Supplying

tank

Weighing

tank MUT

Scale

Pump MUT

• Reduce uncertainties in flow measurements (<1%) • Provide traceability to Mid Scale Loop (200 m3/h)

WP1 Characterization mechanical hysteresis and stiffness matrix

WP2-4 Parasitic Force Reduction System

1. Reduction tank movement

2. Parasitic force compensation

Reduction uncertainty related to non-constant & parasitic forces

1 flange 2 x,y,z motion stage 3 LNG tank 4 position

measurement 5 flexible piping 6 load cell 7 foundation

Example1 : Parasitic force reduction based on position measurement

Weighing tank

Flex loop

Reduction uncertainty related to non-constant & parasitic forces

Example 2: Parasitic force elimination

Retraction due to Force of decoupling smooth bending of swivel

Dry break coupling

WP1 Decoupling the pipe to eliminate the parasitic forces

WP2-4

Weighing tank Retraction system

WP5 Reducing timing

Reduction uncertainty related to switching and temperature reading

Run mode (= calibration)

Pre run mode to get stable flow

WP5 Reducing timing uncertainty

Improve temperature reading and reduce dead volume uncertainty

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Step-2 : Mid Scale Loop