WO1998014774A1 - Procede pour determiner un decalage - Google Patents

Procede pour determiner un decalage Download PDF

Info

Publication number
WO1998014774A1
WO1998014774A1 PCT/US1997/017842 US9717842W WO9814774A1 WO 1998014774 A1 WO1998014774 A1 WO 1998014774A1 US 9717842 W US9717842 W US 9717842W WO 9814774 A1 WO9814774 A1 WO 9814774A1
Authority
WO
WIPO (PCT)
Prior art keywords
transit time
fluid
sound
determining
speed
Prior art date
Application number
PCT/US1997/017842
Other languages
English (en)
Other versions
WO1998014774A9 (fr
Inventor
Alvin E. Brown
Original Assignee
Dietrich Technology Holding Corp.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dietrich Technology Holding Corp. filed Critical Dietrich Technology Holding Corp.
Priority to AU47439/97A priority Critical patent/AU4743997A/en
Publication of WO1998014774A1 publication Critical patent/WO1998014774A1/fr
Publication of WO1998014774A9 publication Critical patent/WO1998014774A9/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • G01F1/668—Compensating or correcting for variations in velocity of sound
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/024—Analysing fluids by measuring propagation velocity or propagation time of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2487—Directing probes, e.g. angle probes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02836—Flow rate, liquid level
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/048—Transmission, i.e. analysed material between transmitter and receiver
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/056—Angular incidence, angular propagation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/10—Number of transducers
    • G01N2291/102—Number of transducers one emitter, one receiver

Definitions

  • the present invention relates generally to the field of ultrasonic flow meters and more particularly to a method of determining a transducer setback in an ultrasonic flow meter.
  • Ultrasonic flow meters have many advantages over other methods of determining flow rates. Ultrasonic flow meters can continuously measure the flow rate, while other methods generally measure average flow rates. In addition, ultrasonic flow meters are obstructionless and work with non- conductive fluids.
  • Ultrasonic flow meters have a pair of transducers that are placed on either side of the flow path of a fluid flowing through a pipe.
  • the transducers are pointed at each other and placed on either side of the flow path of a fluid flowing through a pipe.
  • the transducers are pointed at each other and the line between them has a component in the direction of the fluid flow.
  • the principle used to detect flow rates is that the transit time of an ultrasonic packet will increase in the upstream and decrease in the downstream path. The amount by which the transit time changes is directly proportional to the flow rate. The measured transit time however includes a number of errors.
  • the front window of a transducer provides a delay. Immersed transducers (fixed transducers see FIG. 1) have a stagnant volume between the transducer face and the flowing medium.
  • a method of determining a transducer setback in an ultrasonic flow meter that overcomes these and other problems determines an actual path length of a flow portion of a fluid in a conduit. Next the speed of sound in the fluid is determined. The flowing path transit time is calculated using the speed of sound in the fluid. A total path transit time is measured and the flowing path transit time is subtracted from it to find the setback.
  • FIG. 1 is a block diagram of an ultrasonic flow meter
  • FIG. 2 is a cross section of a pair of clamp-on transducers attached to a conduit
  • FIG. 3 is a flow chart of a process for determining a setback
  • FIG. 4 is a flow chart of the process of determining an actual path length in a clamp-on transducer.
  • the invention determines a setback by measuring a total transit time and subtracting a calculated flowing path transit time.
  • the total transit time is measured by adding an upstream transit time and a downstream transit time and then dividing by two. In this way the effects of the flowing fluid are eliminated in determining the total transit time.
  • the calculated flowing path transit time is determined by using trigonometry to calculate a flowing path length.
  • the flowing path length is divided by a speed of sound in the fluid to determine the flowing path transit time.
  • the speed of sound in the fluid is a function of the temperature of the fluid. By measuring the temperature of the fluid, the speed of sound in the fluid can be found in a look up table.
  • FIG. 1 is a block diagram of an ultrasonic flow meter 10 attached to a conduit 12.
  • a pair of transducers 14, 16 are immersed in the fluid and placed at angle to an inside diameter 18 of the conduit 12.
  • the actual path length (flowing path length) 20 of a flowing portion of the fluid can be found knowing the diameter 18 and the angle of transmission ( ).
  • the transducers (pair of immersed transducers) 14, 16 are coupled to a decoding electronics 22.
  • the decoding electronics 22 are used to determine the transit times.
  • a microprocessor 24 is coupled to the decoding electronics 22.
  • the microprocessor 24 controls the decoding electronics 22 and performs a number of calculations necessary to determine the setback.
  • the microprocessor (computer) 24 is coupled to a memory (computer readable device) 26 that stores the instructions executed by the microprocessor 24 to determine the setback.
  • the memory stores look up tables (table plurality of fluid tables) on a variety of mediums (type of fluid).
  • the look up tables relate the temperature of the medium to the speed of sound in the medium.
  • a display 28 and an input device 30 are also connected to the microprocessor 24.
  • the input device 30 can be used to input information such as the temperature of the medium, the diameter of the conduit and other information.
  • the decoding electronics can include a temperature measurement device, such as a thermocouple.
  • the setback is calculated at the factory and entered as a fixed offset in the equations used by the ultrasonic flow meter to calculate flow rates.
  • FIG. 2 is a cross section of a pair of clamp-on transducers 40, 42 attached to a conduit 44. Determining the actual path length 46 is more complicated in the case of clamp-on transducers than immersed transducers.
  • the diameter 48 of the conduit 44 is known, but the angle ⁇ varies with the temperature of the fluid. This is because the speed of sound in the fluid is different from the speed of sound in the transducer 40, 42 and different from the speed of sound in a wall 50 of the conduit.
  • the sound waves propagate through these various mediums according to Snells Law. It can be shown that the wall has no effect on the angle ⁇ (angle of transmission), since the sound passes through the wall. Similarly the angle at which the sound is propagating in the receive transducer 40 is equal to an initial angle of transmission a.
  • the angle ⁇ can be found using the equation below:
  • SSt - is the Speed of Sound in the transducer
  • SSf - is the Speed of Sound in the fluid
  • the speed of sound in the fluid and in the transducer is a function of temperature.
  • the angle ⁇ is a function of the temperatures of the mediums and varies with these temperatures.
  • the clamp-on transducers 40, 42 are filled with an index matching (i.e., same sound speed) material 52, 54 that makes contact with the pipe wall 50.
  • placement of the transducers 40, 42 is considered critical and specially designed guides are used to hold the transducers 40, 42 in place. These specially designed guides allow the setback to be determined based on the geometry and ignoring that the temperature affects the setback. Using this invention it is no longer necessary to use the specially designed guides.
  • FIG. 3 is a flow chart of the process used to calculate the setback.
  • This process can be implemented by a computer (microprocessor) executing a set of instructions.
  • the set of instructions can be stored on any computer- readable storage medium (e.g., diskette, CD-ROM, ROM, RAM).
  • the process starts, step 100, by determining the actual path length of the flowing portion of the fluid at step 102.
  • the calculation of the actual path length depends on whether the transducers are immersed or are clamp-on transducers.
  • a computer program may include a meter indicator variable that indicates whether the transducers are clamp-on or immersed.
  • the speed of sound in the fluid is determined at step 104.
  • the speed of sound in the fluid is found by measuring the temperature and using a look up table for the fluid to determine the speed of sound.
  • the flowing path transit time is determined at step 106.
  • the flowing path transit time is calculated by dividing the actual path length by the speed of sound in the fluid.
  • the total path transit time is measured at step 108. This measurement is done by launching an ultrasonic pulse and measuring the time from launch until detection at the receive transducer. Generally both the upstream and the downstream transit time are measured and added together to find a round trip time. By dividing the round trip time by two the total transit time is found.
  • the increase in the upstream transit time over a no-flow situation is equal to the decrease in the downstream transit time.
  • the setback is found by subtracting the calculated flowing path transit time from the total transit time at step 110, which ends the process at step 112. In the preferred embodiment half the setback time is attributed to each transducer and the setback is converted to an effective distance.
  • FIG. 4 is a flow chart of a process for determining the actual path length in the case of a clamp-on transducer.
  • the actual path length in the clamp-on case will vary with temperature.
  • the actual path length does not vary and the setback can be calculated once at the factory.
  • the setback is then a fixed correction factor.
  • the process starts, step 150, by inputting the inside diameter of the conduit and the initial angle of transmission (a.) at step 152.
  • the fluid temperature is measured at step 154.
  • the temperature of the transducer is assumed to be equal to the temperature of the fluid.
  • the speed of sound in the transducer is found in a look-up table at step 156. Similarly the speed of sound in the fluid is found in a look-up table at step 158.
  • the angle of transmission ( ⁇ ) is calculated at step 160.
  • the calculated actual path length is determined at step 162, which ends the process at step 164.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • General Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Acoustics & Sound (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Measuring Volume Flow (AREA)

Abstract

L'invention concerne un procédé pour déterminer un décalage de transducteur dans un débitmètre (10) ultrasonore, en déterminant une longueur (20) de parcours réelle d'une partie d'écoulement d'un liquide dans un conduit (12). Puis la vitesse du son dans le liquide est déterminée (104). Le temps de transit dans la voie d'écoulement est calculée en utilisant la vitesse du son dans le liquide (106). Un temps total de transit dans la voie est mesuré (108) puis soustrait au temps de transit dans la voie d'écoulement pour obtenir ledit décalage (110).
PCT/US1997/017842 1996-10-04 1997-10-01 Procede pour determiner un decalage WO1998014774A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU47439/97A AU4743997A (en) 1996-10-04 1997-10-01 Method of determining a setback

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US72079296A 1996-10-04 1996-10-04
US08/720,792 1996-10-04

Publications (2)

Publication Number Publication Date
WO1998014774A1 true WO1998014774A1 (fr) 1998-04-09
WO1998014774A9 WO1998014774A9 (fr) 1998-07-30

Family

ID=24895302

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/017842 WO1998014774A1 (fr) 1996-10-04 1997-10-01 Procede pour determiner un decalage

Country Status (2)

Country Link
AU (1) AU4743997A (fr)
WO (1) WO1998014774A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6907361B2 (en) * 2003-03-06 2005-06-14 Khrone A.G. Ultrasonic flow-measuring method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4633719A (en) * 1985-03-27 1987-01-06 Badger Meter, Inc. Digital flow meter circuit and method for measuring flow
US4856321A (en) * 1983-07-29 1989-08-15 Panametrics, Inc. Apparatus and methods for measuring fluid flow parameters
US5117698A (en) * 1988-12-07 1992-06-02 Joseph Baumoel Pulse train detection in transit time flowmeter
US5531124A (en) * 1993-08-25 1996-07-02 Changmin Technology Co., Ltd. Ultrasonic flow measuring method and apparatus thereof
US5546813A (en) * 1992-10-06 1996-08-20 Caldon, Inc. Apparatus for determining fluid flow

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4856321A (en) * 1983-07-29 1989-08-15 Panametrics, Inc. Apparatus and methods for measuring fluid flow parameters
US4633719A (en) * 1985-03-27 1987-01-06 Badger Meter, Inc. Digital flow meter circuit and method for measuring flow
US5117698A (en) * 1988-12-07 1992-06-02 Joseph Baumoel Pulse train detection in transit time flowmeter
US5546813A (en) * 1992-10-06 1996-08-20 Caldon, Inc. Apparatus for determining fluid flow
US5531124A (en) * 1993-08-25 1996-07-02 Changmin Technology Co., Ltd. Ultrasonic flow measuring method and apparatus thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6907361B2 (en) * 2003-03-06 2005-06-14 Khrone A.G. Ultrasonic flow-measuring method

Also Published As

Publication number Publication date
AU4743997A (en) 1998-04-24

Similar Documents

Publication Publication Date Title
CA2702666C (fr) Procede et systeme pour detecter une accumulation de depot a l'interieur d'un debitmetre a ultrasons
US6907361B2 (en) Ultrasonic flow-measuring method
US5835884A (en) Method of determining a characteristic of a fluid
US4331025A (en) Methods of measuring fluid viscosity and flow rate
JP3216769B2 (ja) クランプオン型超音波流量計における温度圧力補償方法
Moore et al. Ultrasonic transit-time flowmeters modelled with theoretical velocity profiles: methodology
CN104136891B (zh) 利用经补偿的计算温度的超声流动计量
CA2619008C (fr) Procede de calcul du retard propre des transducteurs et de l'intervalle entre transducteurs dans les debitmetres ultrasoniques
US7096135B2 (en) Method and system for calculating the transit time of an ultrasonic pulse
US8229695B2 (en) Meter electronics and methods for geometric thermal compensation in a flow meter
CA2589198C (fr) Systeme et procede de correction d'etalonnage de profil pour debitmetres a ultrasons
EP0017475A1 (fr) Débitmètre acoustique comprenant une correction en fonction du nombre de Reynolds
WO1988008516A1 (fr) Debitmetre ultrasonore pour fluide
US4432243A (en) Flow calculator with velocity curve fitting circuit means
US6816808B2 (en) Peak switch detector for transit time ultrasonic meters
US11169016B2 (en) Standards traceable verification of a vibratory meter
US6837113B1 (en) Enhanced velocity estimation in ultrasonic flow meters
US5965800A (en) Method of calibrating an ultrasonic flow meter
WO1998014774A1 (fr) Procede pour determiner un decalage
WO1998014774A9 (fr) Procede pour determiner un decalage
JP3103264B2 (ja) 超音波流量計
JP2001249039A (ja) 超音波式ガス流速測定方法
US20210302213A1 (en) Determining a damping of a meter assembly
EP1642175B1 (fr) Detecteur de commutation de valeurs cretes pour compteurs ultrasonores de temps de parcours
JPH0791996A (ja) 超音波流量計

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH HU IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG UZ VN YU ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH KE LS MW SD SZ UG ZW AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN

CFP Corrected version of a pamphlet front page
CR1 Correction of entry in section i

Free format text: PAT. BUL. 14/98 UNDER (71) REPLACE THE EXISTING TEXT BY "DIETRICH TECHNOLOGY HOLDING CORP. (US/US);5601 NORTH 71ST STREET, P.O. BOX 9000, BOULDER, CO 80301 (US)."

COP Corrected version of pamphlet

Free format text: PAGES 1/4-4/4, DRAWINGS, REPLACED BY NEW PAGES 1/4-4/4; DUE TO LATE TRANSMITTAL BY THE RECEIVING OFFICE

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1998516890

Format of ref document f/p: F