Application of ultrasonic flowmeters in LNG

D. Laan

KROHNE customer

presentation D. Laan, KROHNE

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

3

Introduction KROHNE, history and experience

Experience with ultrasonic flowmeters since early 1980’s

Experience with measuring LNG using Ultrasonic Flowmeters since early

1990’s

Using acoustic wave guides for high and Low temperature sensor design

Osaka Gas – Japan 1990’s

4

Introduction KROHNE, experience

Over 15 years of Experience with Ultrasonic Flowmeters with Fiscal Accuracy

Proven technology in the field

In operation since 1997!

Introduction

Requirements for LNG flow measurement

Good long term repeatability

No pressure loss

Maintenance free

Verifiable

| YYYY-MM-DD 5 | Presentationtitel

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction,

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

7

Transducer design

2 possible methods: Wave guide and direct method

Wave guide:

The piëzo kristal is mounted away from the cold or hot medium.

The acoustic signal is guided into the liquid using a wave guide

Direct method:

The piëzo kristal is mounted directly at the liquid behind a 3 mm steel

acoustic window

Piëzo kristal

Direct method Wave guide method

8

Transducer design

Advantage of wave guide method

Electric connection and acoustic coupling in a less extreme environment

Disadvantages of wave guide method

Temperature gradient in wave guide provides unknown transient time of acoustic

signal in wave guide

Difficult to insulate

Heat leakage at transducer area which may provide gas bubbles near the transducer

Ice forming

9

Transducer design

Advantage of direct method

Acoustic signal goes direct into the liquid, only the transient time in liquid is measured

Compact construction

Flowmeter can be completely insulated, no heat leakage, no ice forming

Consequence:

Replacement of transducers is not possible

10

Transducer Design

Water @ 20 degC Liquefied Nitrogen @ -196 degC

Piezo material selection for application at -200 ºC

Investigation focused on:

Electric properties

Acoustic properties

Mechanic properties

Result: Very good performance of Piezo Crystal

12

Transducer Tests

Liquefied Nitrogen @ -196 degC

Transducer submerged in Liquefied N2

Signal is monitored

Temperature shock tests

Durability tests

Result: Stable behaviour and a good

performance

13

Flowmeter tests:

Static Tests with complete Flowmeter

Filled with LN2 (-196 ºC)

Very good and stable performance

Design meets all requirements like:

Strong acoustic signal

Large acoustic bandwidth

Good SNR (> 50 dB)

Stable performance during cooling down

No effect of thermal cycles

Flowmeter Tests

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction,

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

15

Calibration Concept

No LNG calibration facility available (yet), with good reference

Calibration procedure has been developed

Transfer calibration at ambient conditions to application at cryogenic condition

The following items have been into account:

Uncertainty calibration rig

Thermal expansion

Linearity → Reynolds calibration

16

Calibration Concept - calibration facilities

Calibration rig: tower is 45 meters high

Max. flow rate: 30.000 m3/hr (almost ½ million liters of water within 1 minute)

Flow meter sizes up to 3200 mm can be calibrated

CMC: 0.03%

17

Calibration Concept – Thermal Expansion

Illustration using ALTOSONIC III

Liquid: Water

Tests at 20ºC, 50ºC and 80ºC

Uncorrected Flow at 20, 50 and 80 degC

-0,5

-0,4

-0,3

-0,2

-0,1

0

0,1

0,2

0,3

0,4

0,5

0 50 100 150 200

Volume flow [m3/h]

Devia

tio

n [

%]

20 degC 50 degC 80 degC

18

Calibration Concept – Reynolds calibration

Corrected for Thermal expansion

Plotted as function of Reynolds number (taking into account changing viscosity)

Flow corrected for thermal expansion and plotted as

function of Reynolds number

-0,5

-0,4

-0,3

-0,2

-0,1

0

0,1

0,2

0,3

0,4

0,5

0,0E+00 5,0E+05 1,0E+06 1,5E+06 2,0E+06

Reynolds number [-]

dev

iati

on

[%

]

20 degC 50 degC 80 degC

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction,

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

20

Test on Liquefied Nitrogen at NIST

Test rig in USA

NIST, Boulder, USA

Cryogenic Test rig on liquefied Nitrogen

Temperature: -193 [ºC] to -183[ºC]

Pressure range: 4 to 7.6 [bar]

Flow range: 4.5 to 45 [m3/h]

Reference: Weighing Tank

Overall uncertainty on totalized mass flow: 0.17%

(k=2) (in range 4.5 to 45 m3/h)

ALTOSONIC V 10 D

DN50 (2”) DN100 (4”)

21

Test on Liquefied Nitrogen at NIST

Flowmeter tested on sensitivity to:

Pressure

Temperature

Flow rate

Thermal cycling

Witnessed by NMi

First Ultrasonic meter that have been tested

and witnessed at this rig

Test on Liquefied Nitrogen at NIST

Linearity:

4” ALTOSONIC V calibrated on water @ 20 ºC

Tested on LN2 in same Reynolds number range

Linearity within ± 0.15%

Including a 2” to 4” expansion just in front of the

ALTOSONIC V

22

Linearity on LN2 based on water calibration

-1,75

-1,25

-0,75

-0,25

0,25

0,75

1,25

1,75

0 200000 400000 600000 800000 1000000

Reynolds number [-]

Dev

iati

on

[%

]

LN2 @ -196 degC

OIML R81

Normal range of operation (v>0.5 m/s)

23

Test on Liquefied Nitrogen at NIST

Results

Sensitivity to pressure and temperature:

No sensitivity to pressure and temperature has been observed (in the range of the rig)

No effect has been measured as a result of thermal cycles

Reproducible results after several thermal cycles

Linearity

Linearity is better than ± 0.15% based on water curve

Even for flow rates down to 1.5% of F.S.

Repeatability and Stability

A complete flow rate cycle is done between collecting each flow rate point

A repeatability of ± 0.07% has been obtained in the normal flow range

Even at 1.5% of F.S. a very good and stable performance is observed

Test on Liquefied Nitrogen at NIST

Results

Uncertainty analysis in cooperation with NMi

Uncertainty statement NMi

With these data the uncertainty is expected to be < 0.2%

24

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction,

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

Applications, LNG import terminal

Enagas, Spain

26

Applications, LNG import terminal

Polski LNG project

North-west of Poland

Contractor: Saipem, Italy

End user: Gaz system

UFM 3030 LT for LNG

OPTISONIC 7300 for methane gas

Operational per June 2014.

27

Applications, LNG import terminal

Polski LNG project

28

Applications, LNG export terminal

One 30” LNG flowmeter installed in Angola

Several underway in and around Australia

29

Applications, non LNG

Supply of liquid oxygen and nitrogen

Separation of air in to N2, O2, Ar etc.

Small diameters 2”- 6”.

Also used for CT

30

Application of ultrasonic flowmeters in LNG

Agenda

1. Introduction,

2. Transducer and flowmeter design and tests

3. Calibration Concept

4. Flow Tests on Liquefied Nitrogen at NIST

5. Applications

6. Flowmeter verification

32

Typical advantages

No moving parts, no wear, no

maintenance, no recalibration

Excellent long term repeatability

No obstructions in the pipe, no

pressure loss

Flowmeter verification

Ultrasonic flow meters

transducer A

transducer B

D

Flowmeter verification

Standard product for cryogenic applications

OPTISONIC 3400

Robust all welded stainless steel construction

DN25…DN3000 (1”…120”)

Liquid temperatures as low as minus 200°C (-328°F)

External sensor housing for easy insulation and avoidance of icing

IP68 (NEMA 6P) ingress protection in case of condensation

Hazardous area approvals: ATEX zone 1, IEC-Ex

Remote converter

Measurement accuracy

± 0,3% of m.v. ± 2 mm/s under ref. conditions

Bidirectional flow measurement at nearly zero flow:

0,3...20 m/s (1...66 ft/s)

For process temperature range of

–200...+250°C (-328...+482°F)

Inlet/outlet conditions: min. 5D/3D

For complete diameter range DN25....3000 (1...120

inch) always a 3-beam ultrasonic sensor

construction

Flowmeter verification

Standard product for cryogenic applications

TBA - TAB ~ vMedium

Flowmeter verification

Diagnostics NAMUR NE107 on all communication

protocols for status messages and error

handling

Status messages are grouped

Group, or priority can be changed by user or switched off

F Failure

S Out of specification

M Maintenance required

C Function check

Flowmeter verification

Diagnostics

F F Sensor – crossed cabling

C C Configuration – flow simulation,

VoS simulation

S S Proc: Empty pipe

S S Proc: Signal lost (per path)

S S Proc: Signal unreliable (per path),

flow profile

Flowmeter verification

Periodical verification

Periodical verification report

Comparison of initial parameters recorded at commissioning

with actual values

Conclusion

Requirements for LNG flow measurement

Good long term repeatability!

No pressure loss!

Maintenance free!

Verifiable!

REQUIREMENTS FULFILLED!

| YYYY-MM-DD 38 | Presentationtitel

Thank you for your attention!