LNG Primary Flow standards out of space dreaming? Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands Mijndert van der Beek Gerard Blom Oswin Kerkhof Gertjan Kok Peter Lucas Maria Mirzaei Erik Smits
Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibrations Future upscaling project Conclusions & questions
Motivation 2009 Typically (static) Level gauging + tank table (static) Uncertainty: ~ 0.5 % Alternative (dynamic) Mass- & Volume rate meters Uncertainty claim 0.2 0.3 % (???) No direct traceable link to SI units yet Calibration facility required!
Overview Goal and motivation of this project Description facility and working principles Measurement challenge: (unsteady) mechanical stresses Some results reproducibility scale Some conclusions & questions
Working principle Cooling down by depressurization Subcooling by pressurization Stabilizing mode Calibration mode Schematic overview flow lines
Primary LNG flow standard at Gasunie peakshaver, LNG and N2 tie-ins
Overview Goal and motivation of this project Description facility and working principles Measurement challenges Some results reproducibility scale Some conclusions & questions
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.
(1) parasitic forces Connection tank to fixed world via flex gas return line Connection tank to fixed world via flexfilling line
(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
(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
(1) Calibration of scale includes 50-300 kg 50 kg disk shaped mass references for calibration Using a number of disks by lowering and hoisting
(1) Typical results, effect of flex hoses 15
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.
(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
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.
(4) Uncertainty due to timing % opening of the switching valve 120 100 Start of the test 80 switch to balance 60 switch to tank 40 20 0 1,433.05 1,433.10 1,433.15 1,433.20 1,433.25 1,433.30 1,433.35 1,433.40 1,433.45-20 Timestamp [s] Valves are type equal percentage characteristic. Timing based upon 50% valve opening, uncertainty ~ 50ms Actual: 50 ms Target u=30 ms 19
Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibrations Future upscaling project Conclusions & questions
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:
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%
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%
Result meter 2 Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands 24
Result meter 3 Norwegian source of traceability Outlyers? Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands 25
Result meter 3 Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands 26
Result meter 4 Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands 27
Overview all calibrated MFM at LNG Deviation 3 out of 4 meters > 0.3% Metrology for LNG conference, 17-18 th October 2013, Delft, the Netherlands 28
Conclusions First primary standard for flowing LNG is realized, Q m = 0.5-5 kg/s. Uncertainty: CMC 0.12~0.15% (0.10% within reach) 3 MFM @ 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
Overview Motivation and Goal of this project Description facility and working principles Measurement challenges Some results MFM calibration Future upscaling project Conclusions & questions
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
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
Functional design specifications midscale Target CMC: <0.15% obo 0.1% due to prim stnd MuT sizes: 1 200 mm) MuT types: CFM, USM, Turbine, DeltaP, Vortex Flow range: 10 200 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
Physical proces diagram Venting mode Start boiling Cool down by evaporation Heating up during operation mode System at atm pressure Pressurize mode 37