long term stability of coriolis flowmeters in cryogenic fluids...•energy density is 2.4 time...

10/15/2018

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Long Term Stability of Coriolis Flowmeters in Cryogenic Fluids

LNG Workshop 2018

Iryna Marfenko – Product Manager Metrology

Endress + Hauser Flowtec AG

Slide 1 Product Management Metrology

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LNG Workshop 2018

Agenda

• Benefits of Coriolis meters in cryogenic fluids

• Temperature compensation

• Transferability of water-based calibration factors to cryogenics

• Example: Road tanker filling at Linde Gas

• Measurement analysis on long term stability

• New Coriolis technology for cryogenic fluids

• Conclusions


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LNG Workshop 2018

Cryogenic Liquids

• Generally referenced as a gas that can be liquefied below -

150°C at atmospheric pressure

Cryogen Temperature

Methane -162° C

Oxygen -183° C

Nitrogen -196° C

Hydrogen -253° C

Helium -269° C

Argon -186° C


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LNG Workshop 2018

Cryogenic Uses

• Cryogenics such as liquid Nitrogen are

used for extreme cooling in:

• Manufacturing Industry

• Medical & Pharmaceutical Industry

• Food & Beverage Industry

• LNG is liquefied at extreme low temps:

• Takes up 1/600th the volume of natural gas

• Energy density is 2.4 time higher than CNG

• Easy and economical way to transport natural

gas where no pipelines exist

Both fluids are monetarily

traded, hence the need to

measure loading and unloading

with a high degree of accuracy.


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LNG Workshop 2018

Measuring Cryogenics with Coriolis

Coriolis technology presents many advantages for measuring cryogenics:

• Measure mass flow directly – avoids volume to mass conversions

• Compact design – short installation lengths; no straight runs required

• No moving parts or seals – low OPEX* and high repeatability

• High degree of accuracy – approved for custody transfer


*OPEX: operating expenses

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LNG Workshop 2018

Temperature compensation

• Deflection of the measuring tubes is a direct function of

stiffness of the tubes


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LNG Workshop 2018




• Tube stiffness is directly related to the mass flow

calibration factor


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LNG Workshop 2018





calibration factor

• Stiffness has a temperature dependency


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calibration factor

• Stiffness has a temperature dependency

• Additional challenges for Cryogenic applications:

• Stainless steel tubes exhibit a nonlinear relationship between temperature

and tube stiffness at low temperatures

• Accuracy of published data for tube properties that allow for extrapolation

to lower temperatures


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LNG Workshop 2018

Example: Thermal Expansion-Contraction/Change of geometry/Change of I

• Source: Johnson, Wesley (NASA Glenn Research

Center, Cleveland, OH United States); 25th Thermal

and Fluids Analysis Workshop (TFAWS); 4-8 Aug.

2014; Cleveland, OH; United States


10/15/2018

• Stiffness of the tube is characterized by the spring constant (k)

� = � �, � � = � � Area moment of Inertia of tube (linear)

� = �(�) Young's Modulus (non linear below about -50°C)

• Therefore, for thermal compensation of the mass flow, I(T) and E(T) are considered.

• The non linear range below -50°C is accurately characterized at two points:

• -196°C (validated via NIST type tests)

• 20°C (meter calibration) with a non-linear interpolation in between.

LNG Workshop 2018


� = � �, �� = � �


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LNG Workshop 2018

Coriolis Meters Calibrated in Water

Calibration

rig

Testing

equipment

National

standard

Global

reference

±0.000001% ±0.0001% ±0.0016% ±0.015%

• All meters calibrated with water

on ISO 17025 accredited and

traceable calibration rigs

• Establishes calibration factor for

meter at about 20°C in water


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LNG Workshop 2018

Flow Calibration Results at NIST – Liquid N2

Uncertainty of NIST Test Rig

Re

lati

ve e

rro

r [%

]


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LNG Workshop 2018

Today yes… But what about tomorrow?

• Market concern for continuous long

term exposure to extremely low

temperatures

• Particularly where temperatures are

continuously cycled such as in batch

loading of trucks


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LNG Workshop 2018

Cryogenic Filling Process @ Linde Gas

Fluid Temperature

Nitrogen -196° C

Oxygen -183° C

Argon -186° C

• More than 150 Promass F (3”) in use for many years

• Meters are factory calibrated with water at about 20°C

• Fluids are liquefied oxygen, nitrogen and argon

• Typical ≈ five 20 ton batches per day @ 40 tons/h flowrate

• Data of 14 meters recorded and analyzed over 4 years

• ≈ 75,000 batches


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LNG Workshop 2018

Cryogenic Filling Process @ Linde Gas - Overview

Event Condition Pump (P) Valve 1 (V1) Valve 2 (V2) Valve 3 (V3) Totalizer (m)

Start cooling Off Close Open Open Reset

Start filling � = �� On Open Close Open Start

Stop filling � = �� Off Close Close Close Stop

Filling stationWeighing scale Storage tank

��

��

��1

��

+

�3

�2�� = �� - �� ≈ 20 ton

�� ≈ 40 ton�� ≈ −150°&

� = ' � ()*+, ,+,


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LNG Workshop 2018

Zero Point Adjustment

• No zero point adjustments were made after installation of

meters at Linde Gas

• Cryogenic fluids often start to boil as soon as the meter is “shut-

in” to perform a zero point

• It has been demonstrated that zero point adjustments can be

performed in an empty pipe condition with excellent results

• Short duration zero point verification on cryogenic fluids can

also be executed


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LNG Workshop 2018


• On site factors that effect the comparison results of meter to weigh scale:

• Batch into “warm” meter → boiling during start phase

• Variable batch size → more or less overall uncertainty due to weigh scale resoluUon

• Downstream portion of piping remains filled but does not enter tanker

• Variability of station design


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LNG Workshop 2018


Resolution weighing scale 20 kg ≈ 0.1%∆� = �� − �� = − ' ∆� ()R

ela

tive

err

or

of

∆�[%

]


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LNG Workshop 2018

Data Format

• ∆� : Mean error of mass in [%] over the four year period

• .∆� : Standard deviation of mass in [%] over the four year period

• ∆�/0 : Drift of mass error per year in [%/a]


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LNG Workshop 2018


Ar O2 N2

Me

an

err

or

∆�[%

]


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LNG Workshop 2018


Ar O2 N2


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LNG Workshop 2018


Ar O2 N2

In operation 6

Months


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LNG Workshop 2018

New Coriolis technology for cryogenics

• Developed to address the need for accurate mass flow in liquids with entrained gas (i.e. boiling)

• Uses a secondary higher order resonance frequency to provide active compensation

Raw �1 und ρ1st mode

2nd mode

Corrected 21 and ρ

Active

Compensation!

Additional

information

Multi-frequency technology™


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LNG Workshop 2018

What about LNG?

-200 -150 -100 -50 0 50

Temperature °C

�=�(�,�)O2

N2 Ar

LNG

H2O

• Water-based calibration factors have been demonstrated to be valid for a wide range of fluid densities

• Interpolation methods for determining tube mechanical properties have also been demonstrated to be valid

Density (kg/m3)

ArO2H2OCH4 N2

999 1141 139480747050

LNG

Interpolation


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LNG Workshop 2018

Conclusions

Coriolis meters are suitable devices for mass flow measurement of cryogenic fluids

• Effects of temperature on mechanical properties of the meter tubes must be understood and adequately

compensated by the meter manufacturer

• The transferability of water-based calibration factors has been demonstrated to be valid for cryogenic

fluids, and specifically for custody transfer applications


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LNG Workshop 2018

Conclusions






Coriolis devices exhibit excellent long-term stability in cryogenic fluids

• No evidence of systematic drift in one direction due to extreme temperature and temperature cycling

• Low levels of drift exhibited are likely attributed to small zero point shifts


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LNG Workshop 2018

Conclusions






Coriolis devices exhibit excellent long-term stability in cryogenic fluids

• No evidence of systematic drift in one direction due to extreme temperature and temperature cycling

• Low levels of drift exhibited are likely attributed to small zero point shifts

New innovations such as Multi-Frequency Technology is available to further improve

Coriolis measurement results in cryogenic fluids


10/15/2018

Products Solutions Services

Thank-You! Questions?

• Special thanks to Linde Group

• Paul Ceglia, Alfred Rieder, Martin Anklin


long term stability of coriolis flowmeters in cryogenic fluids...•energy density is 2.4 time...

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