Liquid Ultrasonic Flow Meters

Transcription

1 Liquid Ultrasonic Flow Meters Acadiana Flow Measurement School Lafayette, LA April 17-18, 2007

2 Liquid Ultrasonic Meter with Integral Transmitter

3 Trans-Alaska Pipeline First Multi-path Ultrasonic Flow Meters for Liquid Petroleum Measurement Application: Line Balance Pipeline Length: ~ 800 miles Number of Meters: 23 Size: 48 inch Rate: ~ 100,000 BPH Date Installed: 1976

4 Creating Ultrasonic Sound Piezoelectric Phenomenon 1 Voltage E E E E E E E E E-05 Crystal Rings to Produce Ultrasound 0.5 to 2 MHz

5 Sensing Ultrasonic Sound Sensing Ultrasonic Sound Piezoelectric Phenomenon Sound Voltage E E E E E E E E E-05 Sound Wave Converted to Voltage

6 Transit Time Flowmeters T up = L/(C-V cosθ) T down = L/(C+V cosθ) Tup Where: L = Path Length Tdown C = Speed of Sound in the fluid θ = Angle of sound path to the pipe axis V = Average velocity along the pipe axis V = (T u L Τ T d) 2cos θ The solution for fluid velocity is independent of the speed of sound (C)

7 Differential Transit Time Signal Processing unit Spool P 1 P 2 P 3 P 4

8 Wetted Transducers No Refraction Caldon LEFM 240C

9 Accoustic Transducer Housings and RTD Caldon LEFM 240C Transducer Housings RTD Temperature Probe

10 Accoustic Transducer Assembly Compression Nut Transducer Transducer Housing Weld Spacer Spring

11 V Chordal Acoustic Paths and Flow Profile ( Pn ) Velocity of Each Path PathLength T = 2 up down ( T T ) Cos φ Integration into a Flow Measurement times per second Q 4 = i = 1 k bi V i A P 1 P 2 P 3 P 4

12 Pulse Formation Q 4 = i = 1 k bi V i A Frequency Generator Continuous Pulse Output 1/60 Sec 1/60 Sec 1/60 Sec 1/60 Sec 1/60 Sec 1/60 Sec 1/60 Sec 1/60 Sec

13 Transmitter (Signal Processing Unit) Inputs and Output Power: 24 Vdc, 120 Vac, 240 Vac Up to 3 Analogs In: Temperature Pressure Density Interconnect Cables Transmitter (Signal Processing Unit) 3 Pulse Channels: 0 5 V Serial: ModBus RTU Up to 4 Analogs Out: Flow Rate Density Temperature Viscosity Flow

14 Meter Prices Cost of metering system Expense ($) Financial exposure Increasing uncertainty

15 Meter Measurement Uncertainty Application Typical Uncertainty Line Balance or Check Metering +/- 0.3 to 0.5% Custody Transfer +/ to 0.25% Master Meter +/- 0.1 to 0.12%

16 Two-Path Meter Line Balance and Check Metering Major Characteristics Stability Reproducibility Reliability Bidirectional Flow Economy

17 Four-Path Meter Custody Transfer Measurement MEASUREMENT SYSTEMS Major Characteristics Precision Accuracy Linearity Stability Bidirectional Flow Provability

18 Eight-Path Meter MEASUREMENT SYSTEMS Premium Custody Transfer and Master Meter Measurement Major Characteristics Premium Accuracy Immune to Installation Effects Total Redundancy Bidirectional Flow Master Meter

19 Meter Installation and Flow Conditioning

20 Horizontal Meter Orientation Avoids: Gas Interference at the Top of the Pipe Particles/Water at the bottom of the Pipe Horizontal Acoustic Paths Gas Chordal Paths Water/particles

21 Proving Ultrasonic Flow Meters

22 Flow Theory of Proving Known Volume MEASUREMENT SYSTEMS Meter Displacer Detectors Pipe/Displacer/Detectors Known volume (undisputed) 1 st Mile long prover in USA 1958 Modern provers Bidirectional Unidirectional Small Volume

23 Theory of Proving Comparison of the Meter s Registration and to a Known Volume (Standard) to Determine a Meter Factor Meter Factor = actual volume ( prover) indicated volume ( meter) The Comparison is Made Several Times and the Repeatability Measured The Conditions at the Time are Recorded The Process is Called Proving

24 Repeatability of Ultrasonic Flow Meters Vortices formed by viscous shear Against the pipe wall Standard Deviation of Transit Time Measurement Between 1% and 2%

25 Repeatability of Proving Runs Proving Runs API Chapter 4.8, Appendix A Repeatability Limit Meter Factor Uncertainty MEASUREMENT SYSTEMS /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10, /10,000

26 Prover Size and Proving Repeatability Prover Volume vs Meter Size 5 Runs 0.05% 8 Runs 0.09% 10 Runs 0.12% 15 Runs 0.17% Meter Size (in.) Prover Size (bbl)

27 Prover Size and Repeatability Small Volume Provers Proving Runs and Passes per Run 5 Runs, 1 Pass per Run 5 Runs, 5 Passes per Run 5 Runs, 10 Passes per Run 10 Runs, 1 Pass per Run 10 Runs, 5 Passes per Run 10 Runs, 10 Passes per Run

28 Small Volume Prover Proving Report 3 Passes per Run, 5 Runs Repeat within 0.05%

29 Manufactured Pulses Delay and Dampening PD DT DT DT RC Example: Error Flow Rate (%) RC ( PD + DT PT.5%( )/0.500 = 1.2% Error ) PT Time Erroneous Indication of Volume due to PD and DT Fundamental Pulse Delay or Sampling Period (PD) Dampening Filter Time Constant (DT) Proving Run Time (PT) Flow Rate Change (%) during the Prove Run (RC)

30 Meter Characterization Improves meter accuracy by compensating for non-linearity of raw Meter Factor for varying Reynolds Number (Re) R e = QD ν Meter is calibrated in a laboratory on liquids and flow rates that most closely match the application Re Because the meter directly measures the flow rate and viscosity, it knows the current Re and make the appropriate correction

31 OIML Specification R117 Linearity MEASUREMENT SYSTEMS

32 OIML Specification R117 Linearity MEASUREMENT SYSTEMS

33 API Chapter 5.8 Recommend Practices for the Custody Transfer Measurement of of Liquid Petroleum

34 Meter Calibration versus In-situ Proving API MPMS Chapter 5.8

35 White Rose FPSO Meters at SPSE, France MEASUREMENT SYSTEMS

36 Measurement System - Master Meter MEASUREMENT SYSTEMS Husky Oil Crude Oil Metering System - White Rose FPSO

37 International Organization for Legal Metrology OIML R 117 A Series of of Tests to to Insure Operation and Performance Suitable for for Custody Transfer Measurement

38 OIML Performance Specification R117 MEASUREMENT SYSTEMS Additional Requirements: Sealing and Password Protection Dry Heat Power Voltage Variations Short Time Power Reductions Electrostatic Bursts Electromagnetic Susceptibility Tampering

39 OIML R-117 R Certification Certification by a third Party (NMi) that the Meter Meets the Requirements LEFM 240C LEFM 220C

40 Advantages of Ultrasonic Flow Meters Simplicity of Measurement System Large Size Meters Smaller Systems Fewer Components Reduced Cost of Measurement & Ownership No Wearing Parts Low ΔP Less Proving Multi-property Measurement Density Viscosity Temperature VOS Diagnostics, etc.

41 In a Nutshell Value of Ultrasonic Meters Simplest Measurement Solution Lowest Cost CAPEX & OPEX Not Just a Flow Meter

42 Discussion, Questions & Answers