watch out for the iceberg! - vsl · watch out for the iceberg! remco van den berg vsl – ceesi 2nd...

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Watch out for the Iceberg! Remco van den Berg

VSL – CEESI 2nd EFMWS 25 – 27 March 2014 / Lisbon, Portugal

Content

-! Requirements of flow metering -! Mathematics in uncertainty calculation -! Real life applications -! Meet up to the requirements

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General requirements of metering and goals to achieve

-! Conformity -! To written standards, legal regulations,

-! Traceability -! To (inter-)national measurement standards and

references -! Accuracy

-! Reduce systematic measurement error

-! Precision -! Achieve lowest possible

uncertainty Beyond all doubt

Conformity

-! Select the applicable standards

-! Agree on the standards with your supplier or customer

-! Get to know the applicable standards

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Traceability

Proof it: Build the pyramid:

Accuracy and Precision!

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0,05 % %

0,10 % - 0,15 %

0,15 % - 0,3 %

0,3 % - 0,5 %

0,5 % - 5 % Metrological pyramid

Primary Measurement standard (VSL)

Secondary measurement standard (VSL)

Operating measurement standards accredited laboratories (ISO/IEC 17025)

Measuring departments industry Measuring & operating processes industrial production

Traceability Pyramid for flow

Less M

easu

rem

ent u

ncer

tain

ty

More Less

Costs of O

wnership

More

Maximum Profit

!"#$

!%&$

!%#$

!&$

#$

&$

%#$

%&$

#$ #'&$ %$ %'&$ "$ "'&$ ($

!"#$%&'()*&+,-&

.#/$0123#1%&'4-&

)*+,-.,/0*1$0*$2,,.-3-.,,4$ 50*-.$ 647,.$)*+,-.4,*.$0*$-3-.,4$ 8/9:.$ ;<=,-$

Profit = f(Uncertainty)

Optimum

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-! Requirements of flow metering -! Mathematics in uncertainty calculation -! Real life applications -! Meet up to the requirements

Uncertainty: The recipe

1.! Describe the measurement set-up 2.! Determine the mathematical model

give the relation between all input quantities and the measurement results (output quantity)

3.! Determine for each input quantity: a.! The value and its uncertainty b.! The distribution function and the standard uncertainty c.! How sensitive is the measurement result for a variation

in this input quantity d.! The uncertainty contribution in the measurement result

Fill in the uncertainty table 4.! Determine and present the result

Example U = I x R

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Uncertainty Table

Total Uncertainty: U = k ! u (y )

End Result: Y = (y ±± U) [unit]

Quantity Xi

Estimate xi Uncertainty Probability

distribution and k-factor

Standard deviation

u(xi)

Sensitivity coefficient

ci

Uncertainty contribution

ui(y)

X1

x1

U1 Distrib1

k1 u(x1)

c1

u1(y)

X2

x2

U2 Distrib2

k2 u(x2)

c2

u2(y)

Y y Standard

uncertainty: u (y) = !!(u1

2 +u22

)

MODEL: Y = f (X1, X2)

Simple Mathematical Model

>?$ @*,/13$

Energy (MJ) = Quantity (m3) x Quality (MJ/m3)

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Adding uncertainties

.#/$0123#1%&

5%61$7&8"#9:;02<"#&

A94B9*,*.$C$ A94B9*,*.$D$ E.9.<<=$

Contribution of uncertainty sources

With: Uflow = 0.3% rel.

UH = 0.5% rel. } Uenergy = 0.58% rel.





To reduce Uflow from 0.3% to 0.2% can be big investment

To reduce UH from 0.5% to 0.2% can be smaller investment

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Uncertainty Table: Example 1

Quantity Xi

Estimate xi Uncertainty Probability

distribution and k-factor

Standard deviation

u(xi)

Sensitivity coeffiicent

ci

[E/xi]

Uncertainty contribution

ui(!E ) [E]

Uncertainty contribution ui(!E/!E)

[%]

!Vn [m3] 6876 20.6 Normal K=2

10.3 3.835E+07 7.91E+07 0.30

Hs [J.m-3] 3.835E+07 76700 Normal K=2 38350

6.876E+03

5.27E+08 0.20

!E [J] 2.637E+11

Expanded Uncertainty

(k=2): 1.55E+09 0.36

MODEL: Energy (J) = Quantity (m3) x Quality (J/m3)

-! Requirements of flow metering -! Mathematics in uncertainty calculation -! Real life application -! Meet up to the requirements

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Real Life Application

USM

PT

TT

GC

Desired uncertainty = 0.5 %

Real Life App: Mathematical Model

-! Real Gas

-! Determination of measured Volume

-! Determination of measured Energy

KZV

TP

i

i

i

i =!

mm

m

n

m

n

n

m

eV

TT

ZZ

PP

+!"!!!="11Vn

sm

mm

n

m

n

n

m He

VTT

ZZ

PP

!+

"!!!="11E

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Real Life App: Uncertainty Budget

quantity estimate source of estimate uncertainty sensitivity uncertainty uncertaintycoefficient contribution contribution

X i x i U(x i) c i U i( V) U i( V/ V)[V/x i] [V] [%]

P m [bar] 31 uncertainty calibration 0.0485 6.384E+03 309.70 0.16

P n [bar] 1.01325 standard pressure 0 -1.953E+05 0.00 0.00

T n [K] 288.15 standard temperature 0 6.869E+02 0.00

T m [K] 292.15 uncertainty calibration 0.20 -6.774E+02 134.72 0.07

e m [-] 0.0000 total uncertainty calibration 0.20% -1.979E+05 395.83 0.20

!! V s [MMSCFT] 1.979E-01 expanded uncertainty (k=2) on volume measurement 5.20E+02 0.26


X i x i U(x i) c i U i( E) U i( E/ E)[E/x i] [E] [%]

H s [MMBTU/SCFT] 1.0372E-03 uncertainty in calorif ic value 1.556E-06 1.979E+05 3.079E-01 0.15

!!E [MMBTU] 2.05282E+02 expanded uncertainty (k=2) on energy measurement 6.21E-01 0.30

Watch out for the iceberg!

The visible:

Calibration uncertainties

The invisible:

?

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AGA8

Accuracy of Equation Of State (EOS)

-! The mathematical model:

sm

mm

n

m

n

n

m He

VTT

ZZ

PP

!+

"!!!="11E

Add the Accuracy of EOS



P m [bar] 31 uncertainty calibration 0.0485 1.808E+02 8.77 0.16


Z n [-] 0.997839 uncertainty of AGA8 algorithm 0.000998 5.617E+03 5.60 0.10Z m [-] 0.937705 uncertainty of AGA8 algorithm 0.000938 -5.977E+03 5.60 0.10


T m [K] 292.15 uncertainty calibration 0.20 -1.918E+01 3.81 0.07

e m [-] 0.0000 total uncertainty calibration 0.20% -5.604E+03 11.21 0.20

!! V n [m 3] 5604 expanded uncertainty (k=2) on volume measurement 1.67E+01 0.30



H s [J.m-3] 3.8645E+07 uncertainty in calorif ic value 5.797E+04 5.604E+03 3.249E+08 0.15

!!E [J] 2.16584E+11 expanded uncertainty (k=2) on energy measurement 7.24E+08 0.33

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Installation Effects

Pressure

Piping (flow profile)

Temperature

Etc!!.

Vibrations

EMC

Fluid properties

Installation Effects



P m [bar] 31 uncertainty calibration 0.0485 1.808E+02 9.49 0.17installation effects 0.020




T m [K] 292.15 uncertainty calibration 0.20 -1.918E+01 4.27 0.08installation effects 0.10

e m [-] 0.0000 total uncertainty calibration 0.20% -5.604E+03 13.73 0.24pipe configuration 0.10%

diff. Calibr. Vs operational conditions 0.10%

!! V n [m 3] 5604 expanded uncertainty (k=2) on volume 1.90E+01 0.34quantity estimate source of estimate uncertainty sensitivity uncertainty uncertainty

coefficient contribution contributionX i x i U(x i) c i U i( E) U i( E/ E)

[E/x i] [E] [%]H s [J.m-3] 3.8645E+07 uncertainty in calorif ic value 5.797E+04 5.604E+03 3.249E+08 0.15


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Flow Computer Selection








V m [m 3] 1.745E+02 totalisation of the f low computer 0 3.211E+01 0.00 0.00

e m [-] 0.0000 total uncertainty calibration 0.002000 -5.604E+03 13.74 0.25pipe configuration 0.001000

diff. Calibr. Vs operational conditions 0.001000interpolation meter curve 0.000100

C t [-] 1.0000 temperature correction factor 0.00033 5.604E+03 1.85 0.03C p [-] 1.0000 pressure correction factor 0.00027 5.604E+03 1.51 0.03






Flow Computer Configuration

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Ambient Conditions

Ambient Conditions quantity estimate source of estimate uncertainty sensitivity uncertainty uncertainty

coefficient contribution contributionX i x i U(x i) c i U i( V) U i( V/ V)

[V/x i] [V] [%]P m [bar] 31 uncertainty calibration 0.0485 1.808E+02 17.31 0.31

installation effects 0.020ambient temperature effect per 28 °C 0.080





ambient temperature effect per 28 °C 0.03










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Long term Stability

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"&)*+

,-

./"0*1$%2*3&'4(5(&)*6*#'5(4%'&(/"*7$%(/8*/9*:*)$'%*;&'<$"*9%/2*='&'*>?$$&@

Long term stability quantity estimate source of estimate uncertainty sensitivity uncertainty uncertainty



installation effects 0.020ambient temperature effect per 28 °C 0.080

stability for 24 months 0.069





ambient temperature effect per 28 °C 0.03stability for 24 months 0.05











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-! Requirements of flow metering -! Mathematics in uncertainty calculation -! Real life application -! Meet up to the requirements

Where to put your Effort (= " $)

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!,#$%&'(-+

.,#$/(0-+."#$/(

1+

2,#$3(-+

2"#$3(4+

56"#$")(-+

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9;#$/(#)+

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Focus on 1 Component: Pressure Transmitter

Pressure Transmitter Uncertainty before improvements




ambient temperature effect per 28 °C 0.080stability for 24 months 0.069




Temperature controlled cabinet 0.040stability for 12 months 0.034

Pressure Transmitter Uncertainty after improvements

Back on the safe side quantity estimate source of estimate uncertainty sensitivity uncertainty uncertainty



installation effects 0.020Temperature controlled cabinet 0.040






Temperature controlled cabinet 0.01stability for 12 months 0.03











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More Balanced Uncertainty

84$FG</H$"IJ$

8*$FG</H$#J$

K*$F!H$%"J$

K4$F!H$%%J$

?*$FLH$#J$

?4$FLH$MJ$

NO4$F4(H$#J$

,4$F!H$((J$

A.$F!H$PJ$

AB$F!H$$(J$

Other Sources of Uncertainty or Error (1)

Flow computer Configuration

-! Correct all input and output I/O’s that influence the outcome of the measurement

-! Enough correction points for the I/O’S -! Use the correct formula’s -! Base conditions throughout the software

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Other Sources of Uncertainty or Error (2)

Equipment

-! Suitable ranges; input and output -! Suitable measurement technique -! Right I/O connections User Errors -! During Maintenance -! During Replacement

-! Do not make assumptions!

From design to sustainable traceability

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The Paper Work

Why are we doing this

FYI

How to do it

What is required?

Guidelines Procedures Standards Policy, Mission!

To Conclude

-! Get to know the written standards -! Get to know your process -! Make the uncertainty budget -! Find the cheapest dominant uncertainty

source -! ALWAYS, IN EVERY STAGE, THINK OF

METROLOGY!!!

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VSL PO Box 654 2600 AR Delft The Netherlands T F E I Erik Smits E Remco van den Berg E

+31 15 269 15 00 +31 15 261 29 71 [email protected] www.vsl.nl [email protected] [email protected] $

VSL group: http://lnkd.in/Bif3Sy

VSL Fluid Flow Metrology group: http://lnkd.in/DF2zJx

Questions ?

watch out for the iceberg! - vsl · watch out for the iceberg! remco van den berg vsl – ceesi 2nd...

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