clamp-on meter – how do they work? · 2017-03-31 · zero stability •real zero stability due to...

Clamp-on meter –how do they work?

Eike Schwede – Insatech Process Days 2017

Ultrasonic Clamp-on Flow Meter

Clamp On UltrasonicFlowmeter:•Transmitter•Transducers•Mounting Fixture•Pipe


Ultrasonic Clamp-on Flow Meter

Transmitter

Junction Box

Mounting Fixture

Transducers

PipeEike Schwede – Insatech Process Days 2017

What is Sound

Sound• Vibrations that travel through the air or another medium in form of a wave

Speed of Sound (c)• Velocity of a sound wave propagating through an elastic medium• Depends of density and medium temperature• Does not depend of sound frequency• Example: SS=6500 m/s, H2O=1500 m/s, Air=330 m/s

C

Density

H2O

74

C

Temperature, °C

Gas

Liquid


What is Sound

Atte

nuat

ion

Distance

m (material)

MoreAttenuation

LessAttenuation

MOLECULAR LEVEL

Attenuation• Reduction of the sound wave amplitude

Causes• Dissipation• Reflection• Absorption• Attenuation=1/Gain

M: Linear Attenuation Coefficient


Sound Frequency

Subsonic: 0 to 20Hz

Audio: 20 Hz to 20 kHz

Ultrasonic: >20 kHz


How we Generate Sound

TRANSDUCERS

The piezoelectric effect transforms:• Electrical Energy into Mechanical Energy• Mechanical Energy into Electrical Energy• Is both Transmitter and Receptor

TRANSMITTER: RECEPTOR:


Time difference principle

Signals are send in and against the flowdirection

Signal with the flow are faster than signalsagainst the flow

Transit time difference Δt is proportional tothe flow velocity of the fluid

Volume flow = flow velocity multiplied bycross section of the inner pipe

V=k*ΔTQ=A*V


Name Author

Open Question?


Considerations

The pipe must be fully packed for liquidapplications

Gas bubbles and solid depositions affectsthe signal

Space availability for transducers


Considerations

Wall Thickness is important Pipe Conditions must be consideredfor attenuation

Proper coupling between transducer and pipe must be done, and a clean surfaceis important

Re 2 fl

tQ K A K

t

Meter formula

What contributes to the Uncertainty of measurement ?

Fluidmechanic

transduceracoustic

pipe crosssectional area

time measurementwith transmitterelectronics

Operational formula

Concept of Calibration

Re 2 fl

tQ K A K

t

Independent sources of Uncertainty => separate calibration

Fluidmechanic

transduceracoustic

pipecrosssectionalarea

timemeasurement

with transmitterelectonics

The flow profile and the pipe (offinal use on site) : factory

calibration not possible, butoptional field calibration

Transducercalibration

Transmittercalibration


Calibration Certificates

Transducer calibration Transmitter calibration

2 2t AU U U

Total: 1.2% +/- 1 cm/sEike Schwede – Insatech Process Days 2017


Independent Calibration

15

All transducers and transmittersare calibrated independently= any combination calibrationcertificates are valid forperformance

Transducer calibration datastored in SENSPROM:automatically read whenconnecting the transmitter

FLEXIM Unique Noise Suppression

• Benefit: robust measurement even underdifficult conditions

Signal Processing

1060 1080 1100 1120 1140 11601.

0.75

0.5

0.25

0.

0.25

0.5

0.75

1.

1060 1080 1100 1120 1140 11601.

0.75

0.5

0.25

0.

0.25

0.5

0.75

1.

• Digital signal processing of full signalenables highly efficient random noisesuppression

;2l a

f

tv K

t

Mean velocity on sound path :

Transit time differencet lv

Transit time in the fluidft Acoustical calibrationfactor

aK

Meter Formula

sin

cK

sin sin sin

c cc

Snell‘s Law:

Acoustical calibration factor:


Zero Stability

Temperature compensated transducers – required to zero-out temperature offsets Clamp-On flowmeters should have integrated RTD’s

for compensation of changing transducertemperatures and must be able to meet the ASMEMFC-5M-2001Standard

long-term drift free measurement

18

c

c

c Fluiddi

w

Zero Stability

•real zero stability due to matching of transducers in production and temperaturecompensation•long-term drift free measurement•meets ANSI/ASME MFC-5M-1985 standard

12" Pipe Flexim Versus Competitor Zero Test

-2

0

2

4

6

8

10

1 67 133 199 265 331 397 463 529 595 661 727 793 859 925 991 1057 1123 1189 1255 1321 1387 1453

GPM

66.1

66.15

66.2

66.25

66.3

66.35

66.4

66.45Flexim

Other UFM

Temp


Re > 3000 >> K=0,91 ….. 0,97

Turbulent Flow

Reynolds number

Re < 1000 >> K=0,75

Laminar Flow

Critical is the range between

Re 1000 and 3000!

>> transition area !


Re Compensation

Reynolds Number

KR

e


2;4A iQ v A A d

Pipe Cross Sectional Area


How to achieve best accuracy

Signal Processing High Noise suppression

DSP – Up to 1000 signals per second

SENS-Prom Fool-Proof transducer detection Ensures an unchangeable accuracy even by a

exchange of the electronic

Matched Transducers Enables primary the drift free measurement Eliminates zeroing Provides reliable measurement values even under

difficult conditions FLEXIM flow meters meet the ANSI/ASME MFC-5M-1985

standard Temperature Compensation

Calibration certificate Each transducer gets a calibration certificate The calibration is traceable to national standards


Media Data Base

Large internal data base for gases and pipe wall materials

Data contains: sound velocity, density, viscosity and

gas compressibility factor

Customized gases (e.g. natural gases) can be storeddepending on temperature and pressure


Sound Path & Transducer Distance

Sensorabstand

Direct or Diagonal Mode:number of sound path = odd (1 or 3),

>> the transducers are mounted on the opposite sides of the pipe

transducer distance


Sound Paths & Transducer Distance

3

a2

Sensorabstand

Reflection Mode:number of sound path = even (2 or 4)

>> the transducers are mounted on the same side of the pipe

with reflection mode the accuracy of flow measurement is a bit higher

measurement will be better, but the signal attenuation is increased

In case of a high signal attenuation by medium, pipe or coatings, direct mode, 1 sound path will be used!

transducer distance


Fluids – Liquids and Gases


Measurement of Liquids

Applications ranges:

Mixtures of different liquids

non-conductive liquids

Multiphase Liquids

High purity or dirty liquids

Particles in liquids

<10% (higher percentage possible)

Size and kind of particles matters

Gases in liquids

<10% (depending)

Size of bubbles matters

some big bubbles are easier than millions of smallerones!

Limit: FoamEike Schwede – Insatech Process Days 2017

Diameter Range Liquids

DN6 DN6500 ?Small tubes Penstocks


- 40°C 200°C

Standard / High Temperature Transducers

-160°C 0°C 400°C 600°C

Extended temperature range with WaveInjector

Temperature Range Liquids


Pipe Materials range


Measurement of Gases

Applications ranges:

under observing minimum pressure requirements:

steel pipes: 5 bar(A) depending on pipe material/sizeno limitations on plastic pipes!

• Mixtures of different gases

Particles in Gases

<10% (higher percentage possible)

Size and kind of particles matters

Liquids in Gases

Wet gas Gases with up to 10% liquid

(water, condensate) More than 10% is generally considered as

multiphase


Diameter Range Gases

DN16 DN1600Small pipes / tubes Supply lines


Temperature Range Gases

-40°C 130°C (170°C)

High temperature transducers extend the range to 200°C


Straight length requirements


Flow profile disturbance

Fully Developed Flow Profile:– It has an almost flat shape

Effects of the accesories on the profile:– Bends, valves, elbows, diffusers,reducers, pumps etc. change the profile of the flow.

Distance from the accesories:– Certain distances to such flow elementsare necessary for an undisturbed flow profile.


Undeveloped Flow Profiles

Cross Flow

Swirl Flow


Other Profile effects

• Most flowmeters will be affected by the flow profile in a pipe

• Piping configuration, amount of straight run of pipe must be considered


Straight length requirements


Cross flow compensation:

Reflect mode or

Dual beam Direct mode

V

r

Flow vector

Unsymmetry offlow profile

Compensation of profiledistortions:

Dual beam reflect mode

Methods of compensation forflow profile deviations

Transducer Alignment


Examples of alignment

Dual Beam with 2 to 4 sound paths

• Two sets of transducers• Redundancy

• Reflecting sound paths compensate cross flow influence• Dual plane configuration averages disturbed flow profiles• Reflecting sound paths compensate cross flow influence

• Maximum flow velocity range• X-configuration compensates cross flow influence• Suitable for handling build up on the inner pipe wall or

attenuative gases/liquids• Suitable to cover wide sound velocity ranges


Effect of disturbances with multiple channels

90° Bend

90°-Krümmer, Messfehler über Störstellenabstand/Di, Installation bei 90°, 1-Kanal

-14.00%

-12.00%

-10.00%

-8.00%

-6.00%

-4.00%

-2.00%

0.00%

-200 -150 -100 -50 0 50 100 150 200

Installationswinkel

Mes

sfeh

ler[%

]

Pos/Di=5Pos/Di=10Pos/Di=15

90°-Krümmer, Messfehler über Installationswinkel, 2-Kanal, 90°

-14.00%

-12.00%

-10.00%

-8.00%

-6.00%

-4.00%

-2.00%

0.00%

-200 -150 -100 -50 0 50 100

Installationswinkel

Mes

sfeh

ler[%

]


90°-Krümmer, Messfehler über Installationswinkel, 4-Kanal 45°

-14.00%

-12.00%

-10.00%

-8.00%

-6.00%

-4.00%

-2.00%

0.00%

-200 -150 -100 -50 0 50 100

Installationswinkel

Mes

sfeh

ler[%

]


Research


Effect of CPA-50E Conditioner

• Flexim has a 6” PVC pipe used for trade shows andtraining exercises

• There is a fan on one end to create a flow condition• Flexim has a CPA-50E conditioner on the other end• The fan can be reversed – flow can go in either direction

Fan

CPA 50E


The fan will create a very severe swirl flowA 2 path (4 beam) meter shows the effect of the profile conditioningThe results show the CPA-50E has a dramatic effect on conditioning the flow

Green = Channel ABlue = Channel BRed = Average channel

Flow Direction Negative – not through Flow Direction Positive – through

Effect of CPA-50E Conditioner

Gases vs Liquids

What is similar?

Gases and Liquids are both fluids

Flow meter formulas for gases and liquids are the same (acoustics, fluid-mechanics)

What is different?

Density of gases is very lowSound attenuation of gases is highGases are compressibleOften high flow velocities and low sound speed

beam blowing


Sound Transmission - AcousticImpedance

Acoustic impedance ρ * c

ρ density c sound speed

Density increases with higher pressure acoustic impedance increases Low transmission into the gas because of relation of acoustic impedance:

This leads to: Wave reflection is very high on the inner pipe wall Little ultrasonic sound amount coupled into the gas

High pressure measurements are easier to measure Minimum of pressure depends on the gas and pipe material

pipewallpipewallgasgas cc


Acoustic impedance and pipe signal

Pipe signals

Acoustic impedance: az c density

sound speed

c

Transmission/Reflection Amplitudepipepipe

gasgas

R

T

c

c

A

A


ρ [kg/m3] c[m/s]

ρ * c Factorsteel pipe / medium

Steel (pipe) 7500 3200 24.000.000 -

Air (1 bar) 1,2 340 408 60.000

Air (30 bar) 36 350 12.600 ~ 2.000

Water 1000 1500 1.500.000 16

Sound transmission

ρ * c steel / ρ * c gas < < 12000


ρ [kg/m3] c[m/s]

ρ * c Factorsteel pipe / medium

Steel pipe 7500 3200 24.000.000 -

Air (1 bar) 1,2 340 408 ~ 60.000

Air (30 bar) 36 350 12.600 ~ 2.000

ρ [kg/m3] c[m/s]

ρ * c FactorPP pipe / medium

PE pipe 900 2.400 ~ 2.200.000

Air (1 bar) 1,2 340 408 ~ 5.400

Compare with a plastic pipe (PE):

Steel pipe:

Sound Transmission PE Pipe


Non-Intrusive Measurement of Ammonia Gas

Medium: Ammonia gasPipe: DN200Material: Carbon SteelTemperature: up to 100 °CPressure: up to 16 bar

The Task:Flow Measurement of warm Ammonia gas at compressor without affectingthe operation of the cooling facility.

Maintenance of the Δp-Impuls lines were linked to high efforts due totoxicologic nature of Ammonia.

The Solution:With G721 there is no need to open the lines – not during installation ormaintenance

Fully available facility No wear No Leckage risk No pressure drop

50

Non-Intrusive Measurement of Thermal Oil

Medium: Shell Thermia Oil Bpipes: DN250 and DN200, Carbon SteelTemperature: ~ 280 °CPressure: ~ 4 bar

Situation:Vortex meter with short maintenance interval

Reason:Thermal stress at start up and shut down

51

Non-intrusive Measurement of Hot Water

Medium: Hot WaterPipes: typical 1‘‘, 1½‘‘ and 2‘‘Material: Stainless Steel

Task:Measurement of the hot water flow to insurance and regulation of the process related heatingpower

52

Non-Intrusive Measurement of Methanol

Medium: Methanol, Methanol-Water-Dilution (variable concentration);Pipes: DN100 and DN400Material: SteelTemperature: ca. 70 °C to 100 °C

Task:Improved efficiency of the vaporisation unit with implementation of a flow measurement.

53

Concentration measurement of concentrated H2SO4

Medium: High concentrated Sulfuric Acid (Electronic Grade), Konz. ~ 96,5 M%Pipe: Glas, 33 mm Outer Diameter,Thickness: 4 mmTemperature: ~ 120 °C to ~ 180 °C

Task:Non intrusive measurement of the concentration to keep the purity Continuos quality control in real time Simultanous measurement of density, mass flow and concentration

54

Non-Intrusive Measurement of Molten Salt

Medium: Thermal oil and Molten SaltsPipe: 610 mm OD, 12,7 mm Thickness, Carbon steel, Temperature: 390 °C to 600 °C

Task:Extreme Temperatures and possible Deposits in the line are problemsInline meters can hardly overcome.Solution:With the patented high temperature WaveInjector the medium is measurement non-intrusive. Thanksto the thermal seperation of pipe and transducer the measurement works drift and maintenance free.

55

Temporary Flow Measurement of Liquids and Gases

Temporary Flow Measurement of Gases, Liquids andHeat flows in Chemical Clusters

Task: Check of permanent installed flow meters Short term replacement of defect meters

Application: Flow Measurement of Gases and Liquids Heat Flow of Liquids Leakage detection in pressurised systems

56

Flow and Energy Measurement in Site Supply

Pipes: DN50 to DN200Material: Carbon Steel, Stainless Steel, PlastikMedia: Potable Water, Ultrapure Water, Demin water, Cold – and Hot water

Task:Efficient operation of modern cogeneration plants requires multiple flow and energy meaurements– also the requirements of the ISO 50001 are to be taken into consideration

57

Oil & Gas – Upstream

Exploration und Production(off- & onshore)

Flow measurement of Oil-WaterEmulsions and also Wetgas

Gas Treatment(i.e. drying)

Natural Gas – Midstream

Underground gas storages Gas Transport Gas Distribution Liquified Natural Gas (LNG)

Flüssige Kohlenwasserstoffprodukte – Midstream

Transport, Verteilung und Lagerung vonRohöl und von raffinierten Produkten

Medienerkennung Leckagendetektion

Application: Oil & Gas – Upstream & Midstream

58

Petrochemical and Chemical Industry

All kind of anorganic and organicFluids (acids, caustics, toxic liquidsetc.)

Industrial gases, Fuel gas Cryogenic or Hot medias

Applications: Oil & Gas – Downstream & Chemical

Refinery

Atmospheric and VacuumDestillation – Feed and Buttom

Coker flow up to 450 °C FCC- and Hydrocracker-

Applications, i.e. Fuel Gas and Gas treatment

59

Application: Water – HVAC – Power Generation

Power Generation

Boiler Feed Water Water/Steam Interface Detection Flow Measurement of Gas and Oil

HVAC – Thermal Supply

Thermal measurement for Boiler, Heat Exchanger and Coolers – forresidential and commercial buildings as well as industrial

Consumption measurement in Compressed Air Networks Pump Audits

Water and Waste Water

Supply and Sewage pipes Flow measurement on buried pipe with IP68 transducer

(no manhole required!) Leak detection - Pipe integrety management

60

FLEXIM – DANKE SCHÖN!


clamp-on meter – how do they work? · 2017-03-31 · zero stability •real zero stability due to...

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