Installation Effects on Ultrasonic Flow Meters for Liquids. Jan Drenthen - Krohne

Transcription

1 Installation Effects on Ultrasonic Flow Meters for Liquids Jan Drenthen - Krohne

2 Jan G. Drenthen & Pico Brand ALTOSONIC 5 Installation effects on ultrasonic flow meters for liquids

3 1. Introduction 2. Meter design 3. Test results Installation effects Meter proving 4. Conclusions Jan G. Drenthen & Pico Brand

4 ALTOSONIC V First Ultrasonic liquid flow meter for custody transfer on the market In operation since 1997 In operation since

5 ALTOSONIC V Even in harsh environments Offshore Ambient -55 C 4

6 ALTOSONIC V and in tough applications High viscosities Cryogenic 5

7 1. Introduction 2. Development of the ALTOSONIC 5 3. Test results Installation effects Meter proving 4. Conclusions Pico Brand

8 Multi-path Flow Meter Configuration Accuracy depends on: Acoustic path configuration The number of paths The calculation schedule of individual paths Major issues are: Erratic flow profile changes in the Transition region Profile distortions Temperature stability Most manufacturers only state the accuracy for Reynolds >

9 What /who is Reynolds ( )? Osborne Reynolds dye experiment. 8

10 9

11 What is Reynolds? Doing his experiments, Reynolds found that there is a similarity in the flow pattern if it is characterized by a certain dimensionless number; which he called the Reynolds number. Re.D. V - density V - mean velocity D - internal pipe diameter µ - the dynamic viscosity For identical Reynolds numbers, the profiles are the same. 10

12 Calibrating at different viscosities than used in situ. As Reynolds found, for identical Reynolds numbers, the profiles are the same. Therefore during calibration at a different viscosity, not the velocity range, but the Reynolds range is of importance! Essential is to match the Reynolds number as they are encountered in situ. Example for a 12 meter Reynold s No. Water 1 cst HC 5 cst HC 10 cst m/s 0.5 m/s 1.0 m/s m/s 1.0 m/s 2.0 m/s m/s 5.0 m/s 10.0 m/s m/s 11

13 Low viscosity versus high viscosity Low viscosity Bitumen High viscosity The University of Queensland pitch drop experiment. Picture taken in 1990, two years after the seventh drop and 10 years before the eighth drop of bitumen fell. 12

14 Temperature dependence of crudes Within 20 degrees F (10 C), the viscosity changes a factor ALTOSONIC for liquids

15 Impact of temperature Especially highly viscous crude oils are transferred at high temperatures; therefore temperature fluctuations are commonplace. As a direct consequence of these temperature variations, large variations in viscosity occur and as a result of that the flow velocity profile will change constantly. So at high viscosities, temperature stability is essential to get an accurate measurement result. At low viscosities, there is more turbulent mixing and temperatures play a smaller role; but than installation effects are more apparent. 14

16 Designer s toolbox: the reducer The reasons for using a reducer are: the improvement of the velocity profile in the transition range. reduction of the impact of the turbulence. Straight bore Reducer (β ratio ) 15

17 Meter design In selecting the acoustic path configuration there are 2 possibilities: 1. Using mathematics dating from the 1830 s (such as used in the Westinghouse patent from 1968 and still applied in many parallel paths meters). And / or.. Gauss Jacobi Legendre Chebyshev 2. by applying flow research and using physical models such as CFD. Only then the technology can progress. 16

18 Hydrodynamic models / CFD Computational Fluid Dynamics (CFD) Turbulence models (e.g. k-ε model, k-ω model) DN25 Double out of plane bend Re=3250 5,897,875 elements CPU time 15 hours (1 Core) 17

19 Flow profile distortions Reducer tests at the University of Erlangen 18

20 Laboratory tests Reducer tests at the University of Erlangen 19

21 v/v gem [-] Laser Doppler and CFD calculation 1.5 Position x: 0R Disturbed profile 5.5 D after a single 45 bending measured in a 135 plane Measured LDA Theory (30% and 0.6R) r/r [-] 20

22 v/v gem [-] Analytical model Theoretical models: - Undisturbed fully developed pipe flow theory - Mathematical hydrodynamic disturbance functions - Wall roughness theory - Cavity correction theory - Flow integration scheme Input: - Experimental LDA/PIV Data - Geometrical parameters - Hydrodynamic parameters (e.g. Reynolds number) 1.5 Position x: 0R Computation: Path position optimization 1 Disturbed profile 5.5 D after a single 45 bending measured in a 135 plane 0.5 Measured LDA Theory (30% and 0.6R) Final design r/r [-] 21

23 Acoustic path configuration Improving upon linearity and installation effects starts with the optimization of the sensor tube concept To determine the best path position, thousands of different path positions have been simulated and tested. Conclusion: Measuring closer to the pipe wall improves the measurement. 22

24 Linearity Improving ultrasonic performance by designing smaller transducers enabling measuring closer to the wall Number of paths Current design Linearity over 1e2<Re<1e8 p-p [%] 23

25 Linearity Improving ultrasonic performance by designing smaller transducers enabling measuring closer to the wall Number of paths Current design New design Linearity over 1e2<Re<1e8 p-p [%] 24

26 Design process 7 path meter Finding the optimum position 7 beam configuration; search area per beam 4 Fixed Flow computation Profiles Worst case filter Red dashed lines indicates the search boundaries solutions 25 25

27 Results base lines 7 BEAM (TRAPIL RAW DATA, 20D no FC) 26

28 OIML & API requirements. Next to the requirements for the accuracy, both the OIML and the API also state requirements for the repeatability of the measurement. OIML requirements: Maximum permissible error: 0.2% Maximum repeatability: 0.12% This also impacts the path position the selection of the flow conditioner the sampling frequency the minimum proving volume when a small volume prover is used

29 Meter design considerations accuracy repeatability Full bore L L Reducer J J Paths located close to the wall J L Plate flow straightener J L Tube bundle L J 28 28

30 Meter design conclusions: The bore reduction has a dominant effect on the meter performance. The best design, accuracy wise, is a meter with: A reduced bore Acoustic paths close to the wall A plate flow conditioner Therefore that design is used for the full range Altosonic

31 ALTOSONIC 5 Path configuration 30 7 direct measuring paths in a criss-cross configuration and one vertical diagnostic path

32 Artist impression of the new meter

33 1. Introduction 2. Development of the ALTOSONIC 5 3. Test results Installation effects 4. Conclusions Jan G. Drenthen & Pico Brand

34 Installation tests The goal for these tests was to quantify the impact of the installation effects that occur in measuring low viscosity fluids ~ 1cSt. At much higher viscosities these effects disappear. The results shown are therefore only valid for low viscosities. 33

35 TEST SETUP 8 meterrun 11 beam Ultrasonic meter was used as a reference, positioned in the undisturbed section. Test facility is Hycal, 1 cst (test liquid is water ºC) Test rates : 60, 110, 200, 375, 675, 1130 m3/h ( m/s) 5 repeats per rate, 1 repeat is 100 seconds

36 Tested Flow conditioners Flow conditioners used in the tests: None 2D slide in ISO tube bundle Spearman plate (similar to the CPA plate). 35

37 Reynolds independence Meter response at various viscosities (0, cst) 36

38 Uncorrected base lines: 0 D, plate FC 0 D Tube FC Tube FC 3, 5 & 10 D, plate FC. 3, 5 & 10 D

39 Perturbation tests: Single Bend in plane, horizontal and vertical 10D..0D Double out of plane bend, horizontal and vertical 10D..0D Concentric reducer

40 Results Single bend in plane (setup) Horizontal setup (3D inlet example) Vertical setup 90º turn of meter (10D inlet example)

41 Dev% Results Single bend in plane at 0D, 3D, 5D &10D no FC. Err% cSt~inplaneH10D~(simu:1.03cSt) SINGLE BEND HORIZONTAL, NO FLOW CONDITIONING Err% cSt~inplaneH5D~(simu:1.08cSt) Err% cSt~inplaneH3D~(simu:0.98cSt) Err% cSt~inplaneH0D~(simu:1.04cSt) Re

42 Dev% Results Single bend in plane at 3D, 5D & 10 D no FC. Err% cSt~inplaneH10D~(simu:1.03cSt) SINGLE BEND HORIZONTAL, NO FLOW CONDITIONING Err% cSt~inplaneH5D~(simu:1.08cSt) Err% cSt~inplaneH3D~(simu:0.98cSt) Err% cSt~inplaneH0D~(simu:1.04cSt) Re

43 Dev% Results Single bend in plane at 3D, 5D & 10 D; 2D ISO Tube bundle Err% cSt~inplaneH10DTB~(simu:1.02cSt) SINGLE BEND, 2D ISO TUBE BUNDLE Err% cSt~inplaneH5D+5DTB2~(simu:1.08cSt) Err% cSt~inplaneH5DTB2~(simu:1.09cSt) Re

44 Dev% Results Single bend in plane at 0D, 3D, 5D & 10 D; plate FC Err% cSt~inplaneH10DHP~(simu:1.02cSt) SINGLE BEND, SPEARMAN PLATE Err% cSt~inplaneH5DHP~(simu:1.12cSt) Err% cSt~inplaneH3DHP~(simu:1.03cSt) Err% cSt~InplaneH3D+0DHP~(simu:1.15cSt) 0.50 Err% cSt~inplaneH0DHP~(simu:1.02cSt) Re

45 Double out-of-plane test results. Double out-of-plane bends create swirl Swirl has a major impact on the flow measurement The decay of swirl depends on both the viscosity and time

46 Err% Results double out-of-plane bend at 0D, 3D, 5D & 10 D; no FC. DOUBLE BEND OUT OF PLANE, NO FLOW CONDITIONING Err% cSt~D-outplaneH10D~(simu:1.17cSt) Err% cSt~D-outplaneH5D~(simu:1.12cSt) Err% cSt~D-outplaneH3D~(simu:0.98cSt) Err% cSt~D-outplaneH0D~(simu:1.03cSt) Re SIMU rev5b (mode VISCO) Dev.Inp: 0.00[%]

47 Err% Double out-of-plane bend at 5D & 10 D; no 2D ISO tube bundle DOUBLE BEND OUT OF PLANE 2D ISO TUBE BUNDLE Err% cSt~D-outplaneH10DTB2~(simu:1.13cSt) Err% cSt~D-outplaneH5DTB2~(simu:1.05cSt) Re

48 Err% Double out-of-plane bend at 0D, 3D, 5D & 10 D; plate FC Err% cSt~D-outplaneH10DHP~(simu:1.08cSt) DOUBLE BEND OUT OF PLANE SPEARMAN PLATE Err% cSt~D-outplaneH5DHP~(simu:0.97cSt) Err% cSt~D-outplaneH3DHP~(simu:1.03cSt) Err% cSt~D-outplaneH0DHP~(simu:1.03cSt) Re

49 1. Introduction 2. Development of the ALTOSONIC 5 3. Test results Installation effects Meter proving 4. Conclusions Jan G. Drenthen & Pico Brand

50 Proving according to API Ch 5.8 The API Ch 5.8 is based on turbine meters. Turbine meters average the flow over the length of the rotor blade section and are not capable to measure high frequency fluctuations. Ultrasonic meters detect all these natural occurring fluctuations in the flow. Hence the output of ultrasonic meters possess a much larger scatter than turbine meters. To reduce the scatter to the level of the turbine meter, the ultrasonic meter must average over a larger time/volume. Proving ultrasonic meters with a SVP is not easy! 49

51 In the API ch. 5.8, 3 methods are described to calibrate a flowmeter with a SVP: 1. Performing 5 proving runs of each 1 pass 2. Performing up to 20 proving runs of each 1 pass 3. Performing 5 to 20 proving runs of each a number of passes (as an example 3, 5 or 10) Runs Repeatability Band % (R) Uncert. % 3 0,02 0, ,03 0, ,05 0, ,06 0, ,08 0, ,09 0, ,10 0, ,12 0, ,13 0, ,14 0, ,22 0,027

52 Minimum proving volume The minimum proving volume is a function of: The meter size. The flow regime (laminar transition turbulent). The turbulence level. The number of acoustic paths. The sampling rate. In the design of the new Altosonic 5, both the number of paths as well as the sampling rate have been optimized for use with SVP. 51

53 Recommended minimum proving volume Required proving volume for an 0.027% uncertainty level A-V full bore Altosonic 5 *new* full bore B a r r a 80.0 l s 60.0 A-V reduced bore Altosonic 5 *new* reduced bore lower is better Inch

54 Small volume prover test at Hycal 53

55 Repeatability SUMMARY TEST RESULTS with a 60 litre base volume Repeatability versus calibration method inch ALTOSONIC V repeatability x 5 5 x 10 3 x API Avg. of 5 x 5 Avg. of 5 x 10 5 x 300 L 5 x 600 L 0.02 Avg. of 3 x 20 3 x 1200 L number of calibrations performed Passed with: 5 x 10 and 3 x 20 Recommended test volume per repeat: 500 liter 54

56 Repeatability SUMMARY TEST RESULTS with a 60 litre base volume Repeatability versus calibration method x 5 5 x 10 3 x 20 6 inch ALTOSONIC V repeatabilities x 5 5 x 300 L API 5 x 10 3 x 20 5 x 600 L 3 x 1200 L number of calibrations performed All tests failed! Too small test volume! Recommended test volume per repeat: 1900 liter 55

57 Recommendations on proving Number of proving passes per run: Using a 5 runs of a 10 passes average gave in most calibration the best results. Recommended proving volumes per run: Meter inch Altosonic 5 liter Altosonic V liter Prover base volume liter A duration of 1.5 seconds is sufficient to guarantee acceptable calibration results for 5 runs of 10 passes each. 56

58 1. Introduction 2. Development of the ALTOSONIC 5 3. Test results Installation effects Meter proving 4. Conclusions Jan G. Drenthen & Pico Brand

59 Conclusions Without proper flow conditioning, installation effects are apparent at low viscosities. In combination with a perforated plate flow conditioner, even for low viscosities, the design is robust and highly insensitive for installation conditions. Using 7 beams, the minimal straight inlet length can be reduced to 3D 5D. 0 D inlet runs are to be avoided in general, but can be used in certain applications when it is calibrated as a package including the upstream piping. Using Reynolds compensation, the meter has become independent of the liquid properties. With the new design, a compact prover can be used. 58

60 Gas and Liquid Metering Skid for CLOV deep water development project. FPSO, Angola Major Projects Reference Overview

61 The King is dead. 60

62 .. long live the new King 61

63 62 Any Questions?

64 In for a bite? 63

65 Jan G. Drenthen & Pico Brand Thank you for your attention!