LNG Primary Flow standards out of space dreaming?

Transcription

1 LNG Primary Flow standards out of space dreaming? Metrology for LNG conference, th October 2013, Delft, the Netherlands Mijndert van der Beek Gerard Blom Oswin Kerkhof Gertjan Kok Peter Lucas Maria Mirzaei Erik Smits

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3 Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibrations Future upscaling project Conclusions & questions

4 Motivation 2009 Typically (static) Level gauging + tank table (static) Uncertainty: ~ 0.5 % Alternative (dynamic) Mass- & Volume rate meters Uncertainty claim % (???) No direct traceable link to SI units yet Calibration facility required!

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6 Overview Goal and motivation of this project Description facility and working principles Measurement challenge: (unsteady) mechanical stresses Some results reproducibility scale Some conclusions & questions

7 Working principle Cooling down by depressurization Subcooling by pressurization Stabilizing mode Calibration mode Schematic overview flow lines

8 Primary LNG flow standard at Gasunie peakshaver, LNG and N2 tie-ins

9 Overview Goal and motivation of this project Description facility and working principles Measurement challenges Some results reproducibility scale Some conclusions & questions

10 Measurement challenges 1. Mass reading error due to unsteady parasitic forces 2. Too low mass reading due to vented gas 3. Trapped vapor bubbles with unsteady volume 4. Start-stop timing errors 5.

11 (1) parasitic forces Connection tank to fixed world via flex gas return line Connection tank to fixed world via flexfilling line

12 (1) Liquid filling line connection Collecting tank Scale Fluid line connection Looking from the collecting tank L-shaped filling tube with two flexible parts for maximal freedom

13 (1) Where do these forces come from? Flex connections: cause forces on balance resulting in a mass-error Forces depend on Load or filling level of tank Operating pressure Hysteresis

14 (1) Calibration of scale includes kg 50 kg disk shaped mass references for calibration Using a number of disks by lowering and hoisting

15 (1) Typical results, effect of flex hoses 15

16 Measurement challenges 1. Mass reading error due to unsteady parasitic forces 2. Too low mass reading due to vented gas 3. Trapped vapor bubbles with unsteady volume 4. Start-stop timing errors 5.

17 (2) Special designed gas meter Temperature sensor stem Supporting straightener Orifice throat Uncertainty gas mass ~2-4% Low and high p-points Radiation shield (duct) Impact on LNG totalized mass: 0.01~0.03% 17

18 Measurement challenges 1. Mass reading error due to unsteady parasitic forces 2. Too low mass reading due to vented gas 3. Trapped vapor bubbles with unsteady volume 4. Start-stop timing errors 5.

19 (4) Uncertainty due to timing % opening of the switching valve Start of the test 80 switch to balance 60 switch to tank , , , , , , , , , Timestamp [s] Valves are type equal percentage characteristic. Timing based upon 50% valve opening, uncertainty ~ 50ms Actual: 50 ms Target u=30 ms 19

20 Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibrations Future upscaling project Conclusions & questions

21 Results flow meter calibrations Goals: Determination of CMC of facility Comparison with other traceability source Find answer to the question: A LNG Program: Testing 4 x MFM,1 x USM, different manufacturers in period May-July 2013:

22 Results, data analyses Physical model of meter deviation: = ( ) 100% = Distribution ~99% ~1% < 0.1% < 0.03% Uncertainties ~ 0.07% ~0.02% < 0.05% < 0.01%

23 Result meter 1 Smallest uncertainty single point: 0.08% 2s avg: 0.05~0.1% depending on MuT Uncertainty avg point: 0.12~0.15%

24 Result meter 2 Metrology for LNG conference, th October 2013, Delft, the Netherlands 24

25 Result meter 3 Norwegian source of traceability Outlyers? Metrology for LNG conference, th October 2013, Delft, the Netherlands 25

26 Result meter 3 Metrology for LNG conference, th October 2013, Delft, the Netherlands 26

27 Result meter 4 Metrology for LNG conference, th October 2013, Delft, the Netherlands 27

28 Overview all calibrated MFM at LNG Deviation 3 out of 4 meters > 0.3% Metrology for LNG conference, th October 2013, Delft, the Netherlands 28

29 Conclusions First primary standard for flowing LNG is realized, Q m = kg/s. Uncertainty: CMC 0.12~0.15% (0.10% within reach) 3 LNG deviation curves: 0.1% ~ 0.5% These test results prove that meter accuracy claims better than 0.5% need to be underpinned by calibrations at LNG Now, how about large (MFM, USM) flow meters?...upscaling to larger facilities, the only way to find

30 Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibration Future upscaling project Conclusions & questions

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32 Some technical challenges Flow stability, pressure control Temperature stability and -determination! Subcooling proces, Boil-off gas handling Composition control & measurement Density measurement => volume flow rate conversion

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35 LNG Flow calibration standard a dream comes true! any questions/ remarks? Oswin Kerkhof Mijndert van der Beek Gerard Blom Gertjan Kok Peter Lucas Maria Mirzaei Erik Smits

36 Functional design specifications midscale Target CMC: <0.15% obo 0.1% due to prim stnd MuT sizes: mm) MuT types: CFM, USM, Turbine, DeltaP, Vortex Flow range: m 3 /hr (4 80 ton/hr) Flow stability: <2%, <0.2 Hz Pressure range: 1 10 Bar(g) Pressure stability: <0.2 bar/min Temperature range: -175 to -123 C Temperature stability: <0.2 C/min, <1 C/hr

37 Physical proces diagram Venting mode Start boiling Cool down by evaporation Heating up during operation mode System at atm pressure Pressurize mode 37