WO2013013395A1 - Dispositif et procédé de mesure du niveau d'un liquide - Google Patents

Dispositif et procédé de mesure du niveau d'un liquide Download PDF

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Publication number
WO2013013395A1
WO2013013395A1 PCT/CN2011/077677 CN2011077677W WO2013013395A1 WO 2013013395 A1 WO2013013395 A1 WO 2013013395A1 CN 2011077677 W CN2011077677 W CN 2011077677W WO 2013013395 A1 WO2013013395 A1 WO 2013013395A1
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WO
WIPO (PCT)
Prior art keywords
ultrasonic waves
container
transducer
reflection means
distributor
Prior art date
Application number
PCT/CN2011/077677
Other languages
English (en)
Inventor
Min Guo
Herbert Schorb
Shunjie Fan
Qinggang Wang
Bing Kong
Yue Zhuo
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to PCT/CN2011/077677 priority Critical patent/WO2013013395A1/fr
Publication of WO2013013395A1 publication Critical patent/WO2013013395A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves
    • G01F23/2962—Measuring transit time of reflected waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G01S15/10—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G01S15/102—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves using transmission of pulses having some particular characteristics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/521—Constructional features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/523—Details of pulse systems
    • G01S7/524—Transmitters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/523—Details of pulse systems
    • G01S7/526—Receivers
    • G01S7/527—Extracting wanted echo signals

Definitions

  • the present invention relates to the filed of liquid level measurement, and particularly to a device and method for measuring liquid level.
  • Liquid level, especially continuous liquid level, in a container is a very important parameter in various industrial and commercial areas.
  • Continuous liquid level refers to the level of liquid which continuously changes.
  • Ultrasonic wave is a kind of acoustic wave which can propagate through a solid wall, and may often be used to measure liquid level inside a container.
  • U.S. Patent No. : US 6412344 Bl presents an ultrasonic liquid level sensor which can be mounted on the bottom of a container to measure liquid level inside the container. This sensor measures the liquid level by measuring the time period during which an ultrasonic wave pulse propagates through the liquid and echoes back. Because ultrasonic wave speed is different in different liquids, the calibration for this sensor is difficult and thus it is difficult to widely use this sensor.
  • U.S. Patent Application No. : US 4901245 A presents a similar ultrasonic liquid level sensor located on the bottom of a container, and an additional sensor mounted on the side wall of the container for determining ultrasonic wave speed in the liquid in the container.
  • This patent application partially solves the problem caused by different ultrasonic wave speeds in different liquids. However, if the liquid is non-uniform in different temperatures or at different densities, then measuring with the two liquid level sensors may still have the problem.
  • U.S. Patent No. : US 6925870 B2 presents a liquid level sensor which can be mounted on the side wall of a container. By measuring the reflection of ultrasonic wave from the intersection of the liquid and the inside lateral wall, the liquid level can be calculated by Pythagorean Theorem. However, this liquid level sensor can not measure non-uniform liquid either. Furthermore, the fluctuation of the liquid surface may affect the reflection of the ultrasonic wave, which may lead to an inaccurate result.
  • ultrasonic wave based liquid level sensors are based on sound speed inside a container, and the ultrasonic wave should propagate through the entire liquid. Therefore, the bubbles, stirrer inside the container, or non-uniformity of the liquid may bring problems to these sensors.
  • U.S. Patent No. : US 6631639 Bl presents a liquid level sensor which adopts two transducers to measure the phase delay of an ultrasonic wave propagating along the side wall of a container.
  • the phase delay relates to liquid level inside the container.
  • the drawback of this solution lies in that a thin layer of liquid residue on the inside wall may lead to an inaccurate measurement result.
  • U.S. Patent Application No. : US 5195058 A presents a liquid level sensor which determines liquid level merely by ultrasonic absorption at the interface between the inside lateral wall and inner contents. The determination method relies on neither the sound speed nor the time period. However, this liquid level sensor can only be used as a point level indicator or switch, and can not be used for general continuous liquid level measurement.
  • liquid level sensors e.g. radar and ultrasonic based liquid level sensors
  • radar and ultrasonic based liquid level sensors are well known to be easily affected by the foams of the liquid.
  • the prior art liquid level measurement method based on ultrasonic wave is easily affected by bubbles, foams, turbulence, density, and sound speed of liquid inside a container.
  • the present invention provides a device and method for measuring liquid level, which can measure continuous liquid level in a container without the affect of bubbles, foams, turbulence, density, and sound speed of liquid inside the container.
  • a device for measuring liquid level includes a transducer, a distributor, and an analyzer; and wherein,
  • the transducer is configured to emit ultrasonic waves to the distributor and to receive echoed ultrasonic waves returned back from the distributor;
  • the distributor is configured to distribute the ultrasonic waves emitted from the transducer in an entire height range of a container, so that the distributed ultrasonic waves in the entire height range of the container propagate towards liquid or gas in the container and are reflected to form the echoed ultrasonic waves upon reaching the liquid or gas in the container, and to return the echoed ultrasonic waves back to the transducer;
  • the analyzer is configured to determine the liquid level based on a shift of amplitudes of the echoed ultrasonic waves returned back to the transducer.
  • the device for measuring liquid level in the embodiment can determine the liquid level based on a shift of amplitudes of echoed ultrasonic waves, because ultrasonic waves distributed in an entire height range of a container can propagate towards liquid or gas in the container and can be reflected to form the echoed ultrasonic waves upon reaching the liquid or gas, and the amplitudes of the echoed ultrasonic waves reflected by the liquid are different from that of the echoed ultrasonic waves reflected by the gas. Therefore, continuous liquid level in a container can be measured by the device without the affect of bubbles, foams, turbulence, density, and sound speed of liquid inside the container.
  • the transducer is mounted on an end of the distributor and is configured to receive the echoed ultrasonic waves reflected back from reflection means of the distributor;
  • the distributor includes at least three reflection means spaced along an emitting direction of the ultrasonic waves, wherein at least one reflection means is disposed lower than a possible lowest liquid level in the container, at least one reflection means is disposed higher than a possible highest liquid level in the container, at least one reflection means is disposed within a shift range of the liquid level, and each reflection means is able to partly reflect and partly transmit the ultrasonic waves, and wherein part of the ultrasonic waves transmitted by one reflection means continue to propagate in the distributor along the emitting direction of the ultrasonic waves to a next reflection means, part of the ultrasonic waves reflected by respective reflection means are reflected back to form the echoed ultrasonic waves upon reaching the liquid or gas in the container, and the echoed ultrasonic waves propagate back to the transducer along a direction right opposite to a propagation direction of the ultrasonic waves from the trans
  • the analyzer is configured to determine the liquid level based on an instant on which an echoed ultrasonic wave reflected back from a reflection means closest to the transducer is received, an instant on which an echoed ultrasonic wave reflected back from a reflection means farthest from the transducer is received, an instant on which amplitudes of received echoed ultrasonic waves are shifted and a distance between the reflection means closest to the transducer and the reflection means farthest from the transducer.
  • ultrasonic waves can be distributed in an entire height range of a container with merely one transducer and multiple reflection means, because the reflection means are disposed in the distributor, the ultrasonic waves can be propagated and reflected in the distributor, the reflected ultrasonic waves can be reflected back upon reaching the liquid or the gas in the container to form the echoed ultrasonic waves, and the echoed ultrasonic waves can then propagate back to the transducer via the reflection means.
  • the distributor is mounted on an outside lateral wall of the container, and part of the ultrasonic waves reflected by the respective reflection means propagate along a direction perpendicular to the outside lateral wall of the container through the outside lateral wall of the container to an interface between the liquid and an inside lateral wall of the container or an interface between the gas and the inside lateral wall of the container, and then are reflected back to form the echoed ultrasonic waves.
  • the distributor is mounted on an outside lateral wall of the container, thus enabling non-invasive installation, reducing the complexity of mounting, repair, and replacement of the distributor, and avoiding contamination to the liquids in the container.
  • the emitting direction of the ultrasonic waves is parallel with the outside lateral wall of the container.
  • the ultrasonic waves can be emitted along the outside lateral wall of the container and thus simplifying the structure of the device.
  • the distributor is invasively mounted in the container, and part of the ultrasonic waves reflected by the respective reflection means propagate in the distributor along a direction perpendicular to a side wall of the distributor in contact with the liquid or the gas, until reaching an interface between the liquid and the side wall or an interface between the gas and the side wall, and then are reflected back to form the echoed ultrasonic waves.
  • the ultrasonic waves do not pass the lateral wall of the container after reflected, and thus the affect of the level of contact between the distributor and the container is avoided so that the measurement result is made accurate.
  • the emitting direction of the ultrasonic waves is parallel with the side wall of the distributor in contact with the liquid or the gas.
  • the ultrasonic waves can be emitted directly along the side wall of the distributor, and thus the structure of the device is made simple and is easy to be achieved.
  • a reflection surface of the reflection means is a plane surface or a parabolic surface.
  • ultrasonic waves can be reflected by the reflection means with a plane surface or a parabolic surface.
  • a reflection surface of the reflection means is a plane surface and is at an angle of 45 degree or 135 degree with the emitting direction of the ultrasonic waves when the emitting direction of the ultrasonic waves is parallel with the outside lateral wall of the container or the side wall of the distributor.
  • the ultrasonic waves can be reflected to be perpendicular to the outside lateral wall of the container or the side wall of the distributor by the reflection surface at an angle of 45 degree or 135 degree with the emitting direction of the ultrasonic waves.
  • the distributor is a slim pole
  • the reflection means is a groove filled with a selected material, wherein the selected material is able to partly reflect and partly transmit the ultrasonic waves.
  • the ultrasonic waves can be partly reflected and partly transmitted when propagating to the groove filled with the selected material.
  • the distributor is a housing filled with a proper medium for propagation of the ultrasonic waves
  • the reflection means is a thin film immersed in the medium, wherein, the thin film is able to partly reflect and partly transmit the ultrasonic waves. In this way, the ultrasonic waves can be partly reflected and partly transmitted when propagating to the thin film.
  • reflection means closer to the transducer are disposed with larger space, and reflection means farther from the transducer are disposed with smaller space. In this way, the performance of the measurement is further optimized.
  • the analyzer is further configured to provide energy to the transducer for generating the ultrasonic waves.
  • the transducer may be powered by the analyzer.
  • a method for measuring liquid level is further provided in an embodiment, the method includes:
  • a second operation distributing by the distributor the ultrasonic waves in an entire height range of a container, wherein the distributed ultrasonic waves in the entire height range of the container propagate towards liquid or gas in the container and are reflected to form echoed ultrasonic waves upon reaching the liquid or the gas in the container;
  • a fourth operation determining by an analyzer the liquid level based on a shift of amplitudes of the echoed ultrasonic waves returned back to the transducer.
  • each reflection means in the distributor partly reflects and partly transmits the ultrasonic waves, wherein part of the ultrasonic waves transmitted by one reflection means continue to propagate in the distributor along an emitting direction of the ultrasonic waves to a next reflection means; and part of the ultrasonic waves reflected by the respective reflection means are reflected back to form the echoed ultrasonic waves upon reaching the liquid or the gas in the container; and
  • the analyzer determines the liquid level based on an instant on which an echoed ultrasonic wave reflected back from a reflection means closest to the transducer is received, an instant on which an echoed ultrasonic wave reflected back from a reflection means farthest from the transducer is received, an instant on which amplitudes of received echoed ultrasonic waves are shifted and a distance between the reflection means closest to the transducer and the reflection means farthest from the transducer.
  • part propagation and part reflection of ultrasonic waves may be achieved with reflection means in the distributor, and the liquid level may be determined based on the shift of amplitudes of echoed ultrasonic waves.
  • Fig. la is a schematic diagram of a container mounted with two transducers
  • Fig. lb corresponding to Fig. la is a schematic diagram of echoed ultrasonic waves reflected respectively from gas and liquid;
  • Fig. 2 is a schematic diagram of the device for measuring liquid level according to an embodiment of the invention.
  • Fig. 3a illustrates a process of ultrasonic waves being emitted from a transducer and propagating to reach liquid and gas in a container
  • Fig. 3b is corresponding to Fig. 3a and illustrates a process of echoed ultrasonic waves returned back from the liquid and gas in the container to the transducer;
  • Fig. 4 illustrates a process of ultrasonic waves being emitted at an angle with an outside lateral wall of a container
  • Fig. 5 illustrates a corresponding relationship between instants on which echoed ultrasonic waves are received by a transducer and amplitudes of the echoed ultrasonic waves
  • Fig. 6a is a schematic diagram of the structure of a distributor
  • Fig. 6b is a schematic diagram of the structure of another distributor
  • Fig. 7 is a schematic diagram of the structure of the device for measuring liquid level according to another embodiment of the invention.
  • Fig. 8 is a flow chart illustrating the method for measuring liquid level according to an embodiment of the invention.
  • liquid inside a container at a point can be detected externally by echoed waves of pulse stimulated ultrasonic waves. Because the acoustic impedance of liquid is always as 1000 times high as that of gas, the amplitudes of echoed ultrasonic waves reflected from gas/solid interface and liquid/solid interface are different. As shown in Fig.
  • transducers 1 and 2 are mounted on an outside lateral wall of a container 14, particularly, the transducer 1 is mounted higher than the liquid level in the container in height, and the transducer 2 is mounted lower than the liquid level in the container in height; stimulated ultrasonic waves emitted from the transducer 1 pass through the lateral wall of the container and are reflected by gas in the container to form echoed ultrasonic waves; and stimulated ultrasonic waves emitted from the transducer 2 pass through the lateral wall of the container, and most parts are absorbed by liquid in the container and small parts are reflected to form echoed ultrasonic waves.
  • Fig. lb corresponding to Fig.
  • la is a schematic diagram of the echoed ultrasonic waves reflected respectively from the gas and the liquid.
  • the amplitude of the stimulated ultrasonic wave 3 is large and that of the echoed ultrasonic wave 4 is small. Because the acoustic impedance of liquid is much larger than that of gas, the amplitude of the echoed ultrasonic wave reflected from the liquid is smaller than that of the echoed ultrasonic wave reflected from the gas.
  • liquid level may possible be determined based on a shift of amplitudes of echoed ultrasonic waves.
  • Fig. 2 schematically illustrates a device for measuring liquid level according to an embodiment.
  • the device includes a transducer 11, a distributor 12 and an analyzer 13.
  • the transducer 11 is configured to emit ultrasonic waves to the distributor 12 and to receive echoed ultrasonic waves returned back from the distributor 12;
  • the transducer 11 is mounted on the distributor 12;
  • the distributor 12 is configured to distribute the ultrasonic waves emitted from the transducer 11 in an entire height range of a container 14, so that the distributed ultrasonic waves in the entire height range of the container 14 propagate towards liquid or gas in the container 14 and are reflected to form the echoed ultrasonic waves upon reaching the liquid or the gas in the container 14, and to return the echoed ultrasonic waves back to the transducer 11 ;
  • the analyzer 13 is connected to the transducer 11 and is configured to determine the liquid level based on a shift of amplitudes of the echoed ultrasonic waves returned back to the transducer 11.
  • the analyzer 13 may provide energy to the transducer 11 for generating the ultrasonic waves, for example, a pulse may be provided to stimulate the transducer 11 to emit the ultrasonic waves, or power may be provided to the transducer 11.
  • the analyzer 13 may further perform a serious of processes such as amplification, demodulation, A/D conversion on received echoed ultrasonic waves, and determine the liquid level based on amplitudes of processed echoed ultrasonic waves.
  • any configuration of the distributor 12 is available as long as the ultrasonic waves emitted from the transducer 11 can be distributed in an entire height range of the container 14, can propagate to reach liquid or gas in the container 14, and can be reflected to form echoed ultrasonic waves, and the echoed ultrasonic waves can be returned to the transducer 11. Since amplitudes of echoed ultrasonic waves reflected back from the liquid and gas are different, the liquid level can be determined based on a shift of amplitudes of the echoed ultrasonic waves.
  • the distributor 12 may be mounted on a lateral wall of the container 14, and multiple transducers may be mounted in the entire height range of the container 14 and all emit ultrasonic waves towards the liquid or the gas in the container 14, in this way, the liquid level can be determined based on the sift of the amplitudes of the echoed ultrasonic waves.
  • ultrasonic waves emitted from a transducer 11 can be distributed in an entire height range of the container 14 by configuring multiple reflection means 15 in the distributor 12 according to an embodiment. In this situation, only one transducer is used, thus saving the resources.
  • Fig. 3a illustrates a process of ultrasonic waves being emitted from a transducer and propagating to reach liquid and gas in a container.
  • Fig. 3b is corresponding to Fig. 3a and illustrates a process of echoed ultrasonic waves returned back from the liquid and the gas in the container to the transducer.
  • the transducer 11 is mounted on the bottom of the distributor 12 and configured to emit stimulated ultrasonic waves (always a few cycles of pulse in a very short period of time) to the distributor 12 and to receive echoed ultrasonic waves reflected back from reflection means 15 in the distributor 12.
  • the transducer 11 may be mounted on the top of the distributor 12.
  • the distributor 12 includes at least three reflection means 15 spaced along an emitting direction of the ultrasonic waves, wherein at least one reflection means 15 is disposed lower than a possible lowest liquid level, at least one reflection means 15 is disposed higher than a possible highest liquid level, at least one reflection means 15 is disposed within a shift range of the liquid level, and each reflection means 15 is able to partly reflect and partly transmit the ultrasonic waves.
  • the ultrasonic waves emitted by the transducer 11 are partly reflected and partly transmitted by respective reflection means 15 in turn while propagating in the distributor 12. Part of the ultrasonic waves transmitted by one reflection means 15 continue to propagate in the distributor 12 along the emitting direction of the ultrasonic waves to a next reflection means 15.
  • the path of the ultrasonic waves from the transducer 11 to the liquid and the gas in the container 14 is the same as the path of the echoed ultrasonic waves reflected back from the liquid and the gas in the container 14 to the transducer 11, but with right opposite directions.
  • An analyzer 13 is connected to the transducer 11 and configured to determine the liquid level based on an instant tl on which an echoed ultrasonic wave reflected back from a reflection means 15 closest to the transducer 11 is received, an instant t3 on which an echoed ultrasonic wave reflected back from a reflection means 15 farthest from the transducer 11 is received, an instant t2 on which amplitudes of the received echoed ultrasonic waves are shifted and a distance between the reflection means 15 closest to the transducer 11 and the reflection means 15 farthest from the transducer 11.
  • the distributor 12 is mounted on an outside lateral wall of the container 14 along the height direction of the container.
  • the ultrasonic waves reflected by the reflection means 15 propagate along a direction perpendicular to the outside lateral wall of the container and pass through the outside lateral wall of the container to reach an interface between the liquid and an inside lateral wall 20 of the container or an interface between the gas and the inside lateral wall 20 of the container, and then are reflected back to form the echoed ultrasonic waves.
  • the distributor 12 is connected to the outside lateral wall of the container 14 by glue or strips, the contacting surface between the outside lateral wall and the distributor 12 should be well sealed by glue or ultrasonic couplant, so that no ultrasonic wave will be reflected at a point between the distributor 12 and the outside lateral wall.
  • a reflection surface of the reflection means may be a plane surface or a parabolic surface, or any other kind of surface that can better bundle the ultrasonic waves, as long as the ultrasonic waves reflected by the reflection surface can propagate to reach the interface of the inner lateral wall 20 of the container and the liquid or the interface between the inner lateral wall 20 of the container and the gas and can be further reflected to form the echoed ultrasonic waves, and the echoed ultrasonic waves can be reflected back via the reflection means 15 to the transducer 11 along a direction right opposite to a propagation direction of the ultrasonic waves from the transducer 11 to the liquid or the gas in the container 14.
  • the emitting direction of the ultrasonic waves emitted by the transducer 11 may be parallel with the outside lateral wall of the container 14.
  • the reflection means 15 may be a plane surface and disposed at angle of 45 degree or 135 degree with the emitting direction of the ultrasonic waves, and thus the emitted ultrasonic waves can be reflected to be perpendicular to the outside lateral wall of the container 14.
  • a reflection means 15 made of a plurality of reflective surfaces may also be used as long as the reflective surfaces are arranged with reasonable angles, and with this kind of reflection means, the ultrasonic waves with an emitting direction parallel with the outside lateral wall of the container 14 can be reflected to be perpendicular to the outside lateral wall of the container 14, and the echoed ultrasonic waves can propagate back to the transducer 11 along a direction right opposite to a propagation direction of the ultrasonic waves from the transducer 11 to the liquid and the gas in the container 14, via the reflection means 15.
  • Fig. 3b illustrates a process of echoed ultrasonic waves reflected back from the liquid and gas in the container to the transducer.
  • the emitting direction of the ultrasonic waves may be at an angle to the outside lateral wall of the container.
  • the angle of the reflection means 15 should be disposed as desired to ensure that the emitted ultrasonic waves can be reflected to be perpendicular to the outside lateral wall of the container and to ensure that at least a part of the ultrasonic waves emitted at an angle to the outside lateral wall of the container can propagate to reach the reflection means 15 farthest from the transducer.
  • Fig. 4 illustrates a process of ultrasonic waves being emitted at an angle with an outside lateral wall of a container. If the emitted ultrasonic waves are at an angle (i.e., angle B in Fig.
  • the reflection surface of the reflection means 15 should be arranged to be at an angle (i.e., angle A in Fig. 4) of 60 degree with the outside lateral wall of the container to ensure that the emitted ultrasonic waves can be reflected to be perpendicular to the outside lateral wall of the container. Further, since the ultrasonic waves reflected by the reflection means 15 are perpendicular to the outside lateral wall of the container, the ultrasonic waves can be reflected to form the echoed ultrasonic waves when passing through the outside lateral wall of the container and contacting liquid or gas, and the echoed ultrasonic waves can be returned back along an original path.
  • reflection means 15 made up of two or more reflective surfaces can be used.
  • the ultrasonic waves emitted at an angle with the outside lateral wall of the container can be reflected to be perpendicular to the outside lateral wall of the container, and the echoed ultrasonic waves can propagate back to the transducer 11 along a direction right opposite to a propagation direction of the ultrasonic waves from the transducer 11 to the liquid and the gas in the container 14, via the reflection means 15.
  • the analyzer 13 performs a serious of processes such as amplification, demodulation, and A/D conversion on a serious of echoed ultrasonic waves received by the transducer 11, determines the instances on which the respective echoed ultrasonic waves are received based on the processed echoed ultrasonic waves, and determines the liquid level based on the relationship between the instances and the amplitudes of the received echoed ultrasonic waves. Specifically, since energy will loss during a propagation process and the amplitude of an echoed ultrasonic wave reflected by the liquid is small, the echoed ultrasonic waves should be amplified and the interferences in the received echoed ultrasonic waves should be removed.
  • processes such as amplification, demodulation, and A/D conversion on a serious of echoed ultrasonic waves received by the transducer 11
  • determines the instances on which the respective echoed ultrasonic waves are received based on the processed echoed ultrasonic waves determines the liquid level based on the relationship between the instances and
  • a part of the ultrasonic waves may pass through the liquid or the gas to reach another lateral wall of the container and then be reflected to form a part of the echoed ultrasonic waves which may constitute the interferences.
  • the interferences may be practically removed according to a transmission delay.
  • Fig. 5 illustrates a corresponding relationship between instants (T) on which echoed ultrasonic waves are received by a transducer and amplitudes (A) of the echoed ultrasonic waves.
  • the duration of the emitted ultrasonic waves is short, and the echoed ultrasonic waves are distributed within a relatively long time due to different transmission distances, wherein tl is the instant on which an echoed ultrasonic wave reflected back from a reflection means closest to the transducer is received, t3 is the instant on which an echoed ultrasonic wave reflected back from a reflection means farthest from the transducer is received, and t2 is the instant on which amplitudes of the received echoed ultrasonic waves are shifted.
  • the dotted line 'a' in Fig. 5 presents a corresponding relationship between instants and amplitudes of the echoed ultrasonic waves when no liquid is contained in the container
  • the dotted line 'b' in Fig. 5 presents a corresponding relationship between instants and amplitudes of the echoed ultrasonic waves when liquid is full filled in the container.
  • the time period during which the amplitudes of the received echoed ultrasonic waves are larger than a preset value may be measured for a container containing no liquid, and may be regarded as the time period tl— 13 during which echoed ultrasonic waves are received. If the amplitude of a received echoed ultrasonic wave is smaller than the preset value, then the echoed ultrasonic wave is ignored. That is to say, when the amplitude represented on the dotted line 'a' in Fig.
  • the preset value may be taken as 90% of the maximum amplitude.
  • the time period tl— 13 during which echoed ultrasonic waves are received may be predetermined according to transmission speed and transmission path of the ultrasonic waves.
  • the corresponding relationship between instances on which echoed ultrasonic waves are received and amplitudes is as illustrated by the solid line in Fig. 5. Since the amplitude of an echoed ultrasonic wave reflected back from liquid is significantly different from that of an echoed ultrasonic wave reflected back from gas, the amplitudes of actual received echoed ultrasonic waves presented by the solid line in Fig. 5 are shifted from the dotted line 'b' to the dotted line 'a' at a position near the liquid level. The instance on which the amplitude is shifted to the preset value may be taken as the instant t2 on which amplitudes of the received echoed ultrasonic waves are shifted. It can be seen from the above analysis that t2 is right the instance on which an echoed ultrasonic wave reflected back from a reflection means corresponding to the liquid level is received.
  • the liquid level can be determined by the analyzer 13 based on the instant tl, the instant t3, the instant t2, and the distance between the reflection means closest to the transducer and the reflection means farthest from the transducer.
  • a relative height of the liquid level may be calculated by the following formulation:
  • W is a vertical distance between the liquid level and the reflection means closest to the transducer, i.e. a relative height position of the liquid level; L is the distance between the reflection means closest to the transducer and the reflection means farthest from the transducer in a vertical direction.
  • W may be a distance between a reflection means corresponding to the liquid level and the reflection means closest to the transducer in a vertical direction.
  • the measurement of the liquid level is based on a shift of the amplitudes of the echoed ultrasonic waves and thus is not subject to the liquid density and the sound speed. It is possible to only use one transducer to measure continuous liquid level and is free from the foam and liquid type. Further, in the above embodiment, the distributor is mounted on the outside lateral wall of the container, and thus it is a non-invasive installation, and thus reducing the complexity of mounting, replacement and repair of the distributor and reducing the probability of contamination.
  • the transducer 11 may be one component working both for emitting and receiving stimulated ultrasonic waves, or may be two components with one working for emitting ultrasonic waves and the other working for receiving ultrasonic waves.
  • Fig. 6a is a schematic diagram of the structure of a distributor.
  • the distributor 12 may be a slim pole made of a material being able to transmit ultrasonic waves, and the reflection means 15 may be a groove 16 filled with a selected material, wherein, the selected material is able to partly reflect and partly transmit the ultrasonic waves.
  • the distributor 12 may be made of stainless steel and the selected material may be epoxy resin.
  • Fig. 6b is a schematic diagram of the structure of another distributor.
  • the distributor may be a housing 18 filled with a proper medium for propagation of ultrasonic waves, and the reflection means 15 may be a thin film 17 immersed in the medium, wherein the housing 18 may be made of plastic or metal, the medium may be liquid (e.g. oil) or solid, the thin film 17 may be made of plastic, glass, metal, etc.
  • the measurement may be optimized by configuring the spaced distance of the reflection means properly. For example, as shown in Fig. 6b, in the distributor, the reflection means closer to the transducer 11 are disposed with larger space, and the reflection means farther from the transducer 11 are disposed with smaller space.
  • reflection means Two kinds of reflection means as shown in Fig. 6a and Fig. 6b are provided above.
  • other reflection means are possible, as long as the material of the reflection means and the material of the distributor for ultrasonic wave propagation have different sound impedances so as to achieve part propagation and part reflection.
  • the emitted ultrasonic waves can be reflected to be perpendicular to the lateral wall of the container by properly setting the angle of the reflection means.
  • Fig. 7 is a schematic diagram of the structure of a device for measuring liquid level according to another embodiment of the invention.
  • This embodiment is different from the above embodiment merely in that the distributor 12 is invasively mounted.
  • the distributor 12 is extended to the liquid from the top of the container.
  • the transducer 11 is mounted on one end of the distributor and is exposed to the outside of the container.
  • the distributor 12 is fixed to the container with a flange 19.
  • the reflected ultrasonic waves propagate in the distributor 12 along a direction perpendicular to the side wall 21 of the distributor, to the interface between the liquid and the distributor 12 or between the gas and the distributor 12 and then is reflected to form the echoed ultrasonic waves.
  • the side wall 21 is a wall of the distributor 12 which is in contact with the liquid and the gas.
  • the emitting direction of the ultrasonic waves may be parallel with the side wall 21 of the distributor, and at this point the reflection surface of the reflection means may be a plane surface and at an angle of 45 degree or 135 degree with the side wall 21 of the distributor.
  • the emitting direction of the ultrasonic waves may be not parallel with the side wall 21 of the distributor, and at this point the angle of the reflection means should be set properly to enable the ultrasonic waves emitted at an angle to the side wall 21 of the distributor to be reflected to be perpendicular to the side wall 21 of the distributor.
  • the ultrasonic waves do not pass the lateral wall of the container after reflected, and thus avoiding the affect of the level of contact between the distributor and the container, and improving the accuracy of the measurement result.
  • a method for measuring liquid level using the above device is provided according an embodiment. As shown in Fig. 8, the method includes the following operations S801-S804.
  • a transducer emits stimulated ultrasonic waves to a distributor
  • the distributor distributes the ultrasonic waves in an entire height range of a container, wherein the distributed ultrasonic waves in the entire height range of the container propagate towards liquid or gas in the container and are reflected to form echoed ultrasonic waves upon reaching the liquid or the gas in the container;
  • an analyzer determines the liquid level based on a shift of amplitudes of the echoed ultrasonic waves returned back to the transducer.
  • each reflection means in the distributor partly reflects and partly transmits the ultrasonic waves, wherein part of the ultrasonic waves transmitted by one reflection means continue to propagate in the distributor along an emitting direction of the ultrasonic waves to a next reflection means; and part of the ultrasonic waves reflected by the respective reflection means are further reflected back to form the echoed ultrasonic waves upon reaching the liquid or the gas in a container.
  • the operation of S804 includes: the analyzer determines the liquid level based on an instant tl on which an echoed ultrasonic wave reflected back from a reflection means closest to the transducer is received, an instant t3 on which an echoed ultrasonic wave reflected back from a reflection means farthest from the transducer is received, an instant t2 on which amplitudes of the received echoed ultrasonic waves are shifted and a distance between the reflection means closest to the transducer and the reflection means farthest from the transducer.
  • continuous liquid levels can be measured without the affect of bubbles, foams, turbulence, density, and sound speed of liquid inside the container.
  • the present application may also be adopted to measure the height of an interface between two materials with different acoustic impedances, e.g., the height of a gas/solid or liquid/solid interface.
  • the present invention may also be adopted to measure simultaneously the heights of multiple interfaces, each of which is between two materials with different acoustic impedances, e.g., the heights of air/oil/water or air/water/mud interfaces.
  • a device for measuring liquid level includes: a transducer configured to emit ultrasonic waves to a distributor and to receive echoed waves returned back from the distributor; the distributor configured to distribute the ultrasonic waves emitted from the transducer in an entire height range of a container, so that the distributed ultrasonic waves in the entire height range of a container propagate towards liquid or gas in the container and are reflected to form the echoed waves upon reaching the liquid or gas in the container, and to return the echoed waves back to the transducer; and an analyzer configured to determine the liquid level based on a shift of amplitudes of the echoed waves returned back to the transducer.
  • the continuous liquid level inside the container can be measured without the influence of bubbles, foams, turbulence, density, and sound speed of the liquid in the container.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Acoustics & Sound (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L'invention concerne un dispositif permettant de mesurer le niveau d'un liquide qui comprend un transducteur (11), un distributeur (12) et un analyseur (13); le transducteur (11) est destiné à émettre des ondes ultrasoniques vers le distributeur (12) et à recevoir l'écho des ondes ultrasoniques renvoyé par le distributeur (12); Ledit distributeur (12) est destiné à distribuer les ondes ultrasoniques émises par le transducteur (11) dans une plage entière de hauteur d'un récipient (14), ainsi, les ondes ultrasoniques distribuées dans la plage entière de hauteur du récipient (14) se propagent en direction du liquide ou du gaz dans le récipient (14) et se reflètent de manière à former l'écho des ondes ultrasoniques lorsqu'il atteint le liquide ou le gaz dans le récipient (14), et à le renvoyer vers le transducteur (11); et l'analyseur (13) est destiné à déterminer le niveau du liquide sur la base d'un déphasage des amplitudes de l'écho des ondes ultrasoniques renvoyé vers le transducteur (11). L'invention concerne un procédé de mesure du niveau du liquide. Grâce à la solution précitée, le niveau continu de liquide à l'intérieur du récipient peut être mesuré sans l'influence des bulles, des mousses, de la turbulence, de la densité et de la vitesse du son du liquide dans le récipient.
PCT/CN2011/077677 2011-07-27 2011-07-27 Dispositif et procédé de mesure du niveau d'un liquide WO2013013395A1 (fr)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106502196A (zh) * 2016-12-02 2017-03-15 高翔 电脱盐设备油水界面在线监测及控制方法和系统
CN110765686A (zh) * 2019-10-22 2020-02-07 中国人民解放军战略支援部队信息工程大学 利用有限波段海底地形进行船载声呐测深测线设计的方法
EP3479080B1 (fr) * 2016-07-01 2021-08-11 Serviglp, S.L. Surveillance d'un niveau de produit dans un contenant
CN113406196A (zh) * 2021-07-13 2021-09-17 广东飞达交通工程有限公司 一种超声波检测水成膜泡沫液箱的无线传输系统
WO2023197479A1 (fr) * 2022-04-14 2023-10-19 西安定华电子股份有限公司 Procédé et système de détermination, réflecteur, compteur de niveau de liquide de mesure externe de réservoir vertical et son procédé de montage
JP2023552238A (ja) * 2020-12-28 2023-12-14 西安定華電子株式有限会社 ステアリング反射面の決定方法及び外部測定液面計フォーカスステアリング

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CN1346049A (zh) * 2000-09-25 2002-04-24 海德罗索尼科国际有限公司 声波水位测量方法及其系统
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CN101097161A (zh) * 2006-06-30 2008-01-02 北京奥麦特科技有限公司 一种超声波测量液位的装置及方法
CN102052952A (zh) * 2010-11-18 2011-05-11 陕西科技大学 一种原油储罐油水界面测量装置及其测量方法

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US4901245A (en) * 1987-12-01 1990-02-13 Moore Technologies, Inc. Nonintrusive acoustic liquid level sensor
CN1304031A (zh) * 1999-10-20 2001-07-18 刘春生 传波杆接触式超声脉冲回波液位测量方法
CN1346049A (zh) * 2000-09-25 2002-04-24 海德罗索尼科国际有限公司 声波水位测量方法及其系统
US20050284217A1 (en) * 2003-10-02 2005-12-29 Denso Corporation Liquid level detecting apparatus
CN101097161A (zh) * 2006-06-30 2008-01-02 北京奥麦特科技有限公司 一种超声波测量液位的装置及方法
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3479080B1 (fr) * 2016-07-01 2021-08-11 Serviglp, S.L. Surveillance d'un niveau de produit dans un contenant
CN106502196A (zh) * 2016-12-02 2017-03-15 高翔 电脱盐设备油水界面在线监测及控制方法和系统
CN106502196B (zh) * 2016-12-02 2018-12-14 高翔 电脱盐设备油水界面在线监测及控制方法和系统
CN110765686A (zh) * 2019-10-22 2020-02-07 中国人民解放军战略支援部队信息工程大学 利用有限波段海底地形进行船载声呐测深测线设计的方法
JP2023552238A (ja) * 2020-12-28 2023-12-14 西安定華電子株式有限会社 ステアリング反射面の決定方法及び外部測定液面計フォーカスステアリング
JP7541195B2 (ja) 2020-12-28 2024-08-27 西安定華電子股▲フン▼有限公司 ステアリング反射面の決定方法及び外部測定液面計フォーカスステアリング
CN113406196A (zh) * 2021-07-13 2021-09-17 广东飞达交通工程有限公司 一种超声波检测水成膜泡沫液箱的无线传输系统
WO2023197479A1 (fr) * 2022-04-14 2023-10-19 西安定华电子股份有限公司 Procédé et système de détermination, réflecteur, compteur de niveau de liquide de mesure externe de réservoir vertical et son procédé de montage

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