Acoustic flowmeter and method for non-invasively determining the flow of a medium in an electrically conducting object

Patent metadata

Field	Value
Publication number	US-9664543-B2
Application number	US-201314432932-A
Country	US
Kind code	B2
Filing date	Sep 27, 2013
Priority date	Oct 1, 2012
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

The invention relates to a method for determining the flow or the flow rate of a medium in an electrically conductive object, in particular a pipe ( 1 ) or a pipeline, through which a medium flows. At least one ultrasonic wave ( 16 ) is produced by means of a transmitting transducer ( 11 ) in the object and is injected into the medium as a longitudinal wave ( 8 ) on an inner side of the object, and an ultrasonic signal, coming at least partially from the longitudinal wave ( 8 ), is received by the receiving transducer ( 12 ), at a spatial distance from the injection point and is used to evaluate the flow or the flow rate. Said transmitting transducer ( 11 ) produces, preferably in the absence of an acoustic coupling with the surface of the object, a first variable magnetic field in an area close to the surface of the object, in particular metallic, and a first ultrasonic wave is produced in said area by means of the interaction of said variable magnetic field with a static or quasi-static magnetic field. Said transmitting transducer ( 11 ) also produces an additional variable magnetic field in the area of the object and an additional ultrasonic wave is produced in said area by means of the interaction of the variable magnetic field with a static or quasi-static magnetic field, said other ultrasonic wave is superimposed on the first ultrasonic wave such that an amplitude of a resulting wave in the direction of the receiving transducer ( 12 ) is increased and is reduced in the direction away from said receiving transducer ( 12 ). Preferably, the first and the second magnetic fields are produced by two high frequency bobbins ( 18, 19 ) of the transmitting transducer ( 11 ). The invention also relates to a device for carrying out said inventive method.

First claim

The invention claimed is:

1. A method for determining a flow or a volumetric flow rate of a medium in an electrically conducting object through which the medium flows, the method comprising:
generating at least one ultrasonic wave in the object using an excitation transducer, wherein the ultrasonic wave is coupled into the medium at a coupling site as a longitudinal wave at an inner side of the object, wherein generating the at least one ultrasonic wave comprises:
generating a first varying magnetic field using the excitation transducer in a region close to a surface of the object;
generating a first ultrasonic wave in the region close to the surface of the object by interacting the first varying magnetic field with a static or quasi-static magnetic field;
generating a second varying magnetic field using the excitation transducer in the region close to the surface of the object; and
generating a second ultrasonic wave in the region close to the surface of the object by interacting the second varying magnetic field with the static or quasi-static magnetic field;

receiving an ultrasonic signal, which emerges at least in part from the longitudinal wave, at a spatial distance from the coupling site by a receiving transducer for evaluating the flow or the volumetric flow rate; and
superposing the second ultrasonic wave on the first ultrasonic wave to create a resultant wave,
wherein an amplitude of the resultant wave is increased in the direction of the receiving transducer and reduced in the direction away from the receiving transducer, and
wherein the first and the second varying magnetic fields are generated by two high-frequency induction coils of the excitation transducer.

2. The method according to claim 1 , wherein the first and the second ultrasonic waves cancel each other out in the direction away from the receiving transducer.

3. The method according to claim 1 , wherein the second ultrasonic wave is generated in the object with a 90° phase shift and a λ/4 spatial shift in relation to the first ultrasonic wave, wherein λ corresponds to the wavelength of the generated ultrasonic wave in the object.

4. The method according to claim 1 , characterized in that wherein the varying magnetic fields are generated by one or more conductor paths of the high-frequency induction coils, wherein the one or more conductor paths extend over at least 90° along the circumference of the tubular object and at an angle to the longitudinal axis thereof.

5. The method according to claim 4 , wherein the first and second high-frequency induction coil are formed by two different conductor paths of the excitation transducer.

6. The method according to claim 1 , wherein the excitation transducer is configured for the generation of bulk waves.

7. The method according to claim 6 , wherein the bulk waves are shear bulk waves.

8. The method according to claim 1 , wherein the first or the second ultrasonic wave is generated by at least one high-frequency induction coil, the coil winding of which is multiplied in the center of the coil.

9. The method according to claim 1 , wherein a signal of the excitation transducer is modulated by a window function.

10. The method according to claim 1 , wherein the excitation and receiving transducers are spaced so far apart that the ultrasonic signal in the receiving transducer emerges from several passages in the medium.

11. The method according to claim 1 , wherein a first pair of excitation and receiving transducers and a second pair of excitation and receiving transducers are arranged on the object and measurements are undertaken both in the direction of the flow and in the opposite direction, wherein the two pairs are arranged at a distance from one another on the object.

12. The method according to claim 1 , wherein the ultrasonic signal is picked up by two high-frequency induction coils of the receiving transducer, the reception signals of which are superposed for analysis purposes.

13. The method according to claim 1 , wherein the object is a tubular object.

14. The method according to claim 1 , wherein the object is a pipe or a pipeline.

15. The method according to claim 1 , wherein the first varying magnetic field is generated by forgoing an acoustic coupling with the surface of the object.

16. The method according to claim 1 , wherein the second varying magnetic field is generated by forgoing an acoustic coupling with the surface of the object.

17. The method according to claim 1 , wherein the excitation transducer is configured for the generation of guided waves.

18. The method according to claim 17 , wherein the guided waves are n-th order Lamb waves, where n is an integer and greater than or equal to 0.

19. The method according to claim 1 , wherein the longitudinal wave passes through the medium.

20. An acoustic flowmeter for non-invasively determining the flow or the volumetric flow rate of a medium in an electrically conducting object, through which the medium flows, comprising:
an excitation transducer for generating at least one ultrasonic wave in the object, wherein the ultrasonic wave is coupled into the medium as a longitudinal wave at an inner side of the object directed to the medium;
a receiving transducer to detect an ultrasonic signal in the object, wherein the ultrasonic signal emerges at least in part from the longitudinal wave,
wherein the excitation transducer comprises two high-frequency coils for generating two varying magnetic fields in a region close to the surface of the object,
wherein the high-frequency coils are arranged spatially offset from one another when observed transversely with respect to a longitudinal direction of the object and are able to generate two ultrasonic waves in the region close to the surface of the object by the interaction of the varying magnetic fields with a static or quasi-static magnetic field,
wherein the ultrasonic waves are superposed in the object in such that an amplitude of a resultant wave is increased in a direction of the receiving transducer and reduced in the direction away from the receiving transducer.

21. The acoustic flowmeter according to claim 20 , wherein, when observed transversely with respect to the longitudinal direction of the object, the receiving transducer comprises two high-frequency coils which are arranged spatially offset from one another.

22. The acoustic flowmeter according to claim 21 , wherein the excitation transducer or the receiving transducer comprises two conductor paths for forming two high-frequency coils, wherein the parts of the first conductor path, which are connected by deflections, in each case have a constant distance of λ/4 from neighboring part of the second conductor path, wherein λ/4 is the wavelength of the ultrasonic wave in the object.

23. The acoustic flowmeter according to claim 20 , wherein the parts of a conductor path have the same current direction have a spacing of λ, where λ is the wavelength of the ultrasonic wave induced in the object.

24. The acoustic flowmeter according to claim 20 , wherein the excitation transducer or the receiving transducer has a conductor path, which, when observed transversely with respect to the longitudinal direction of the object, has multiple windings in the center.

25. The acoustic flowmeter according to claim 20 , wherein the excitation transducer and receiving transducer are connected to one another by a same clock.

26. The

Assignees

• Rosen Swiss Ag

Inventors

• Twerdowski Evgeny
• Heinks Carsten

Classifications

• G01F1/662

  Constructional details · CPC title

• B06B1/04

  operating with electromagnetism (dynamo-electric motors with vibrating magnet, armature or coil system H02K33/00) · CPC title

• G01F1/667 Primary

  Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters · CPC title

• G01N2291/0426

  Bulk waves, e.g. quartz crystal microbalance, torsional waves · CPC title

• G01N2291/0427

  Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever · CPC title