CN112539805A - Ultrasonic liquid level measurement system and method for sound velocity compensation by using DTS (delay tolerant system) - Google Patents
Ultrasonic liquid level measurement system and method for sound velocity compensation by using DTS (delay tolerant system) Download PDFInfo
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- 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
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Abstract
The invention discloses an ultrasonic liquid level measuring system and method for sound velocity compensation by DTS, the system mainly comprises: the device comprises an ultrasonic probe, a waveguide tube, a transmitting circuit, a receiving circuit, a controller, a DTS optical fiber temperature sensing module and a display module; when the ultrasonic probe works, the ultrasonic probe transmits ultrasonic waves to the liquid level to be detected, the ultrasonic waves are reflected by the liquid level and then received by the probe, and the propagation time of ultrasonic signals is calculated; and continuously measuring the temperatures at different heights in the closed container by using the DTS temperature sensing module, further calculating a sound velocity curve, calculating the liquid level height in the container by using the propagation time and the sound velocity curve, and displaying and storing the liquid level height. The ultrasonic liquid level measurement method adopting the DTS to perform sound velocity compensation can compensate the influence of temperature on the measurement precision of the ultrasonic liquid level meter, realize high-precision liquid level measurement, and meanwhile, the system can be used for liquid level measurement of corrosive liquid, so that the application occasions are wider.
Description
Technical Field
The invention belongs to the technical field of liquid level detection, and particularly relates to an ultrasonic liquid level measurement system and method for sound velocity compensation by DTS distributed optical fiber temperature measurement.
Background
The liquid level measurement is widely applied to industries such as petroleum, chemical engineering and the like, and is the most common measurement parameter in industrial production. The liquid level measuring method can be divided into a contact type and a non-contact type according to whether the liquid level measuring device is in contact with the measured medium or not. The sensing part of the contact type liquid level meter is contacted with the measured liquid, is not suitable for liquid level measurement under the strong acid and strong alkali corrosion radiation condition, and mainly comprises a manual scale detection method liquid level meter, a floater liquid level meter, a capacitance type liquid level meter, a magnetostriction liquid level meter and the like; the non-contact liquid level measurement generally utilizes time difference to measure liquid level, and a sensing part is not contacted with the measured liquid, so that the non-contact liquid level measurement can be used for liquid level measurement in special occasions, and mainly comprises an ultrasonic liquid level meter, a radar liquid level meter, a laser liquid level meter and the like.
Compared with other types of liquid level meters, the ultrasonic liquid level meter has the advantages of non-contact measurement, strong adaptability, strong universality, no abrasion, long service life and the like, can work in severe environment, and is suitable for liquid level measurement in a closed container. However, the ultrasonic sound velocity is greatly influenced by the environment, the sound velocity is influenced by the change of the temperature, the humidity, the pressure or the composition of a transmission medium, wherein the influence of the temperature is the largest, and the sound velocity needs to be corrected by a temperature compensation method so as to improve the measurement accuracy of the ultrasonic liquid level meter. At present, the sound velocity compensation in the ultrasonic liquid level meter mostly adopts a single-point temperature measurement method to measure the temperature of the environment where the instrument is located, the method is suitable for the occasions with stable and uniform environment temperature, the temperature of liquid in a closed container in a special environment can be higher or lower than the environment temperature, the temperature of air in the container is layered, the sound velocity change in the whole space range can not be accurately compensated obviously only by measuring the temperature of a single point, and the high-precision liquid level measurement can not be realized.
Therefore, how to provide an ultrasonic liquid level meter capable of performing sound velocity compensation in a full space range is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to overcome the defects and provide an ultrasonic liquid level measurement system and method with DTS sound velocity compensation.
In order to achieve the above purpose, the invention provides the following technical scheme:
an ultrasonic liquid level measurement system using DTS for sound velocity compensation, comprising: the device comprises an ultrasonic probe, a waveguide tube, a transmitting circuit, a receiving circuit, a controller, a DTS optical fiber temperature sensing module and a display module; wherein:
an ultrasonic probe: receiving a pulse signal input by a transmitting circuit, generating an ultrasonic signal under the action of the pulse signal and transmitting the ultrasonic signal to the liquid level through a waveguide tube; receiving the liquid level reflection ultrasonic wave returned by the waveguide tube, realizing the mutual conversion of the liquid level reflection ultrasonic wave and a voltage signal, and outputting the voltage signal to a receiving circuit;
wave guide tube: transmitting an ultrasonic signal generated by the ultrasonic probe to the liquid level, and transmitting ultrasonic waves reflected by the liquid level to the ultrasonic probe; a transmitting circuit: the pulse signal input by the controller is amplified and then output to the ultrasonic probe;
a receiving circuit: amplifying, filtering, detecting and shaping the voltage signal input by the ultrasonic probe, generating an interrupt signal and outputting the interrupt signal to the controller;
a controller: outputting the pulse signal to a transmitting circuit and starting timing; receiving an interrupt signal input by a receiving circuit, stopping timing, recording the time from starting timing to stopping timing as a time signal of ultrasonic wave propagation, and outputting the time signal to a DTS optical fiber temperature sensing module;
DTS optical fiber temperature sensing module: receiving an ultrasonic wave propagation time signal input by a controller, measuring temperatures at different heights in the closed container, calculating a sound velocity according to the measured temperatures, calculating a liquid level value by combining the ultrasonic wave propagation time signal and the sound velocity, and outputting the liquid level value to a display module;
a display module: and receiving and displaying the liquid level value input by the DTS temperature sensing module.
Further, the transmitting circuit is an amplitude amplifying circuit.
Further, the ultrasonic probe is a piezoelectric ultrasonic transducer.
Furthermore, the waveguide tube is a hollow rigid cylinder, is sleeved at the lower end of the ultrasonic probe, and has a length less than or equal to the height in the container;
further, the receiving circuit comprises an amplifying circuit, a filtering circuit, an envelope detection circuit and a shaping circuit, wherein the output end of the ultrasonic probe is connected with the input end of the amplifying circuit, the output end of the amplifying circuit is connected with the input end of the filtering circuit, the output end of the filtering circuit is connected with the input end of the envelope detection circuit, the output end of the envelope detection circuit is connected with the input end of the shaping circuit, and the output end of the shaping circuit is connected with the input end of the controller.
Furthermore, the DTS optical fiber temperature sensing module comprises a laser, a wavelength division multiplexer, a first photoelectric conversion circuit, a second photoelectric conversion circuit, an A/D acquisition module, an upper computer, a data storage module and a sensing optical fiber;
the output end of the laser is connected with the input end of a wavelength division multiplexer, the wavelength division multiplexer is connected with the sensing optical fiber through a bidirectional port, the first output end and the second output end of the wavelength division multiplexer are respectively connected with the input ends of a first photoelectric conversion circuit and a second photoelectric conversion circuit, the output ends of the first photoelectric conversion circuit and the second photoelectric conversion circuit are both connected with the input end of the A/D acquisition module, the output end of the A/D acquisition module is connected with the input end of the upper computer, the output end of the upper computer is connected with the input end of the data storage module, and the output end of the upper computer is connected with the display module;
the sensing optical fibers are arranged on the outer surface of the waveguide tube from bottom to top along the axis in parallel, and signals are transmitted by the sensing optical fibers and then return to the wavelength division multiplexer again.
An ultrasonic liquid level measurement method for sound velocity compensation by adopting DTS comprises the following steps:
s1, the controller generates a pulse signal and starts timing, the pulse signal is input to the transmitting circuit, and the transmitting circuit drives the ultrasonic probe to transmit an ultrasonic signal to the liquid surface to be measured through the waveguide tube;
s2, the echo signal reflected by the measured liquid surface is received by the ultrasonic probe through the waveguide tube, an interrupt signal is generated after the echo signal enters the receiving circuit, and the controller stops timing;
s3, the controller calculates the propagation time of the ultrasonic signal and transmits the propagation time to the DTS optical fiber temperature sensing module;
s4, the DTS optical fiber temperature sensing module acquires the temperature value in the closed container in real time, the sound velocity can be calculated according to the temperature value, the liquid level height in the container can be obtained by combining the propagation time information obtained in the step S3, and the liquid level height is displayed in real time through the display module.
Further, in step S4, the DTS optical fiber temperature sensing module includes a laser, a wavelength division multiplexer, a first photoelectric conversion circuit, a second photoelectric conversion circuit, an a/D acquisition module, an upper computer, a data storage module, and a sensing optical fiber;
the specific steps of the DTS optical fiber temperature sensing module for acquiring the temperature value are as follows:
the method comprises the following steps that S41 a laser emits pulse laser signals, and simultaneously provides trigger signals for an A/D acquisition module, and the A/D acquisition module starts to acquire;
s42 pulse laser signal enters the sensing optical fiber after passing through the wavelength division multiplexer;
backward scattered light generated by the propagation of the S43 pulse laser signal in the sensing optical fiber is divided into anti-Stokes light and Stokes light through the wavelength division multiplexer, and the anti-Stokes light and the Stokes light respectively enter the first photoelectric receiving conversion circuit and the second photoelectric receiving conversion circuit to complete photoelectric conversion and signal amplification processing to obtain voltage signals V1 and V2;
s44 voltage signals V1 and V2 enter an A/D acquisition module, and the A/D acquisition module finishes accumulation and average processing on the acquired signals to obtain acquired signals Vd1 and Vd 2;
and S45Vd1 and Vd2 enter the upper computer, demodulate temperature information in the container and transmit the temperature information to the data storage module for storage.
Further, in the above step S4, the formula for calculating the sound velocity from the temperature is that v is 331.45+0.607T, where v is the ultrasonic sound velocity and T is the ambient temperature.
Further, the information on the liquid level height in step S4 is obtained by the formula H-L-v · t/2, where v denotes the ultrasonic sound velocity, t denotes the propagation time of the ultrasonic wave, H denotes the liquid level height, and L denotes the total height in the container.
Compared with the prior art, the invention has the following beneficial effects:
(1) the ultrasonic liquid level sensing system adopts the DTS to perform sound velocity compensation, combines the distributed optical fiber temperature sensing system with the ultrasonic liquid level meter, realizes continuous measurement of the temperature of a gas transmission medium part in the closed container, greatly reduces the influence of the temperature on the measurement precision of the ultrasonic liquid level meter, and can more accurately compensate the ultrasonic sound velocity and realize high-precision liquid level measurement compared with the sound velocity compensation of single-point temperature measurement;
(2) the distributed optical fiber temperature sensing technology adopted by the invention takes the optical fiber as a sensing element, has strong anti-electromagnetic interference capability, long transmission distance, strong corrosion resistance and good durability, can be used for liquid level measurement of corrosive liquid, and has wider application occasions;
(3) the invention adopts the wave guide pipe structure, so that the ultrasonic waves can only be transmitted and emitted in the pipe, the interference of stray reflection waves can be reduced, meanwhile, the influence of steam in the container on the ultrasonic liquid level measurement can be inhibited to a certain extent, and the liquid level measurement precision is improved.
Drawings
FIG. 1 is a schematic view of an ultrasonic level gauge according to the present invention.
Fig. 2 is a schematic structural diagram of an ultrasonic liquid level sensing system using DTS for sound velocity compensation according to the present invention.
Fig. 3 is a schematic diagram of a receiving circuit structure provided by the present invention.
Fig. 4 is a schematic structural diagram of a DTS optical fiber temperature sensing system provided by the present invention.
FIG. 5 is a flow chart of the operation of the ultrasonic liquid level sensing system using DTS for sound velocity compensation according to the present invention.
Fig. 6 is a flow chart of the DTS fiber temperature sensing operation provided by the present invention.
The ultrasonic probe comprises an ultrasonic probe 1, a waveguide 2, a transmitting circuit 3, a receiving circuit 4, an amplifying circuit 401, a filtering circuit 402, an envelope detection circuit 403, a shaping circuit 404, a controller 5, a 6DTS optical fiber temperature sensing module 601, a laser 602, a wavelength division multiplexer 603, a photoelectric receiving and converting circuit I, a photoelectric receiving and converting circuit II 604, an A/D acquisition module 605, an upper computer 606, a data storage module 607, a display module 7 and a sensing optical fiber 8.
Detailed Description
The features and advantages of the present invention will become more apparent and appreciated from the following detailed description of the invention.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
As shown in fig. 2, an ultrasonic liquid level sensing system using DTS for sound velocity compensation includes: the device comprises an ultrasonic probe 1, a waveguide tube 2, a transmitting circuit 3, a receiving circuit 4, a controller 5, a DTS optical fiber temperature sensing module 6 and a display module 7;
the controller 5 and the transmitting circuit 3 are sequentially connected with the ultrasonic probe 1, the waveguide tube 2 is arranged below the ultrasonic probe, the ultrasonic probe 1 generates an ultrasonic pulse signal, the ultrasonic pulse signal is transmitted in the waveguide tube 2 and is emitted to the liquid level to be detected, meanwhile, the ultrasonic probe 1 detects the reflected ultrasonic signal, and after mutual conversion of the ultrasonic signal and a voltage signal is realized, the voltage signal is transmitted to the receiving circuit 4; the waveguide tube 2 is used for reducing the influence of stray reflected waves on ultrasonic detection and reducing the influence of steam in the container on liquid level measurement; because the ultrasonic probe can generate ultrasonic waves only by high-voltage pulse excitation, the transmitting circuit 3 is used for amplifying pulse signals output by the controller so as to enable the ultrasonic probes to emit ultrasonic waves with certain energy and capable of transmitting for a long distance; the receiving circuit 4 amplifies, filters, detects and shapes the voltage signal output by the ultrasonic probe, generates an interrupt signal and inputs the interrupt signal into the controller; the output end of the receiving circuit 4 is connected with the input end of the controller 5; the controller 5 is used for generating a square wave signal with fixed frequency, receiving an interrupt signal, namely a stop timing signal, and calculating the propagation time of the ultrasonic wave; the output end of the controller 5 is connected with the input end of the DTS optical fiber temperature sensing module 6, the output end of the DTS optical fiber temperature sensing module 6 is connected with the input end of the display module 7, the DTS optical fiber temperature sensing module 6 is used for continuously measuring the temperatures at different heights in the closed container, calculating the sound velocity according to the measured temperatures, compensating the influence of the temperatures on the sound velocity, calculating the liquid level value by combining the ultrasonic propagation time calculated by the controller, and improving the measurement precision of the liquid level meter; and the display module 7 is used for displaying the liquid level measurement result calculated and processed by the DTS temperature sensing module.
As shown in fig. 1, the distance measurement principle of the ultrasonic level meter is that, during operation, an ultrasonic probe emits pulse ultrasonic waves to a liquid surface, the ultrasonic waves are emitted at an interface between gas and liquid, reflected echo signals are returned and received by the ultrasonic probe, the ultrasonic level meter calculates a time difference t according to recorded pulse emission time and echo reception time, calculates a distance value between the liquid surface and the top end of a closed container according to a formula H-v.t/2, and then calculates a liquid level value in the container according to a formula H-v.t/2, wherein H is the distance between the top end of the closed container and the liquid surface, H is the liquid level height, and L is the total height in the container.
Further, the transmission circuit 3 is an amplitude amplification circuit.
Further, the ultrasonic probe is a piezoelectric type ultrasonic transducer.
Further, the waveguide tube 2 is a hollow rigid cylinder which can be sleeved at the lower end of the ultrasonic probe, and the length of the waveguide tube is less than or equal to the height in the container;
further, as shown in fig. 3, the receiving circuit 4 includes an amplifying circuit 401, a filtering circuit 402, an envelope detecting circuit 403, and a shaping circuit 404, wherein an output terminal of the ultrasonic probe 1 is connected to an input terminal of the amplifying circuit 401, an output terminal of the amplifying circuit 401 is connected to an input terminal of the filtering circuit 402, an output terminal of the filtering circuit 402 is connected to an input terminal of the envelope detecting circuit 403, an output terminal of the envelope detecting circuit 403 is connected to an input terminal of the shaping circuit 404, and an output terminal of the shaping circuit 404 is connected to an input terminal of the controller 5.
Further, as shown in fig. 4, the DTS optical fiber temperature sensing module 6 includes a laser 601, a wavelength division multiplexer 602, a first photoelectric conversion circuit 603, a second photoelectric conversion circuit 604, an a/D acquisition module 605, an upper computer 606, a data storage module 607, and a sensing optical fiber 8;
the output end of the laser 601 is connected with the input end of a wavelength division multiplexer 602, the first output end and the second output end of the wavelength division multiplexer 602 are respectively connected with the input ends of a first photoelectric conversion circuit 603 and a second photoelectric conversion circuit 604, the output ends of the first photoelectric conversion circuit 603 and the second photoelectric conversion circuit 604 are both connected with the input end of an A/D acquisition module 605, the output end of the A/D acquisition module 605 is connected with the input end of the upper computer 606, the output end of the upper computer 606 is connected with the input end of the data storage module 607, and the output end of the upper computer 606 is connected with a display module 7;
the sensing optical fiber 8 is a sensing element of the DTS optical fiber temperature sensing module, and is used for sensing external temperature change and transmitting an optical signal modulated by temperature. Wavelength division multiplexer 602's two-way port is connected sensing optical fiber 8, and sensing optical fiber 8 is laid along the axis parallel from bottom to top 2 outer surfaces of guided wave tube, and wavelength division multiplexer 602 is returned again after the propagation of sensing optical fiber 8.
The invention relates to an ultrasonic liquid level measurement method for sound velocity compensation by adopting a DTS (dynamic time series simulator), which comprises the following steps of:
s1, the controller 5 generates a pulse signal and starts timing, the pulse signal is input to the transmitting circuit 3, and the ultrasonic probe is driven to transmit an ultrasonic signal to the liquid surface to be measured through the waveguide tube 2;
s2, the echo signal reflected by the liquid surface to be measured is received by the ultrasonic probe 1 through the waveguide 2, and an interrupt signal is generated after entering the receiving circuit 4, and the controller 5 stops timing;
s3, the controller 5 calculates the propagation time of the ultrasonic signal and transmits the propagation time to the DTS optical fiber temperature sensing module 6;
s4, the DTS optical fiber temperature sensing module 6 acquires a temperature value in the closed container in real time, the sound velocity can be calculated according to the temperature value, the liquid level height in the container can be acquired by combining the propagation time information acquired in the step S3, and the liquid level height is displayed in real time through the display module 7;
8. the ultrasonic liquid level measuring method using the DTS for sound speed compensation according to claim 7, wherein in step S4, the DTS optical fiber temperature sensing module 6 includes a laser 601, a wavelength division multiplexer 602, a first photoelectric conversion circuit 603, a second photoelectric conversion circuit 604, an a/D acquisition module 605, an upper computer 606, a data storage module 607 and a sensing optical fiber 8;
the specific steps of the DTS optical fiber temperature sensing module for acquiring the temperature value are as follows:
the S41 laser 601 emits pulse laser signals, and provides trigger signals for the A/D acquisition module 605 at the same time, and the A/D acquisition module 605 starts acquisition;
the S42 pulse laser signal enters the sensing optical fiber 8 after passing through the wavelength division multiplexer 602;
backward scattered light generated by the propagation of the S43 pulse laser signal in the sensing fiber 8 is divided into anti-stokes light (AS light) and stokes light (S light) by the wavelength division multiplexer 602, and enters the first photoelectric receiving conversion circuit 603 and the second photoelectric receiving conversion circuit 604 respectively to complete photoelectric conversion and signal amplification processing to obtain voltage signals V1 and V2; the backward scattering light is backward Raman scattering light, Raman scattering can occur when the optical pulse propagates in the optical fiber, the Raman scattering light returning along the optical fiber is called backward Raman scattering light, and the intensity of the backward Raman scattering light is related to the temperature of a scattering point;
s44 voltage signals V1 and V2 enter the A/D acquisition module 605, and the A/D acquisition module 605 finishes accumulation and average processing on the acquired signals to obtain acquired signals Vd1 and Vd 2;
and S45Vd1 and Vd2 enter the upper computer 606, demodulate temperature information in the container and transmit the temperature information to the data storage module 607 for storage.
Further, in step S4, the formula for calculating the sound speed from the temperature is that v is 331.45+0.607T, where v is the ultrasonic sound speed and T is the ambient temperature.
Further, the information on the liquid level height in step S4 is obtained by the formula H-L-v · t/2, where v denotes the ultrasonic sound velocity, t is the propagation time of the ultrasonic wave, H is the liquid level height, and L is the total height in the container.
Example 1
With reference to fig. 5, the ultrasonic liquid level sensing system and method using DTS for sound velocity compensation includes the following steps:
the system of S1 is electrified, the ultrasonic probe 1 is T/R40-16 type, can exert the best performance only under the drive of voltage of 40kHz, the controller 5, namely the single chip microcomputer, sends out the square wave with frequency of 40kHz and starts timing, the said square wave enters the transmitting circuit 3, the transmitting circuit 3 carries on power and amplitude amplification to the square wave signal that the controller produces, stimulate the ultrasonic probe to transmit the ultrasonic signal;
s2 ultrasonic signals reflected by the liquid surface to be detected are converted into voltage signals V through the ultrasonic probe 1, the voltage signals V enter the receiving circuit 4, the voltage signals output by the ultrasonic probe 1 are weak, the amplifying circuit 401 amplifies the signals to obtain signals VA, the VA is processed through the filter circuit to remove low-frequency noise to obtain signals VF, the detection circuit 403 carries out envelope detection on the voltage signals VF, the obtained voltage signals VD enter the shaping circuit 404, the shaping circuit 404 is built through a comparator, the threshold voltage is set to be Vth, when the amplitude of the signals VD is larger than the threshold voltage Vth, the output end of the shaping circuit outputs high level, otherwise, low level is output, therefore, the analog voltage signals VD can be shaped into digital square wave signals VS, interrupt signals are provided for the controller 5, and the controller 5 stops timing;
the signal VS of S3 enters the controller 5 as an interrupt signal, the controller 5 stops timing, calculates the propagation time of the ultrasonic signal, and transmits the time calculated value to the upper computer 606 of the DTS optical fiber temperature sensing module 6 through the serial port;
s4, because the temperature at different heights in the container may have a temperature stratification phenomenon, the DTS optical fiber temperature sensing module 6 continuously measures the temperature values at different heights in the closed container through the optical fiber to obtain temperature curves at different heights in the container, because the temperature of the liquid to be measured and the temperature of the gas above have a temperature difference, the upper computer finds the point with a large slope change of the temperature curve through an algorithm to be used as a critical surface of the gas and the liquid, the temperature point above the interface is taken to calculate the sound velocity v which is 331.45+0.607T, wherein T represents the environment temperature, the sound velocity curve of the gas part is fitted, the time value measured by the controller 5 in the step S3 is used, the distance value between the liquid surface to be measured and the top end of the container is obtained by integrating the sound velocity curve by using a formula H which is v.t/2, the liquid level height is calculated by substituting into a formula H which is L-v.t, h is the distance between the liquid level to be measured and the top end in the container, H is the height of the liquid level to be measured, L is the total height in the container, v is the sound velocity of the ultrasonic wave, and t is the propagation time of the ultrasonic wave;
and S5, the upper computer 606 transmits the calculated liquid level value to the data storage module 607 for storage, and transmits the liquid level data to the display module 7 for display.
Referring to fig. 6, the temperature measuring step of the DTS fiber temperature sensing module is as follows:
after the S41 system is powered on, the laser 601 emits a pulse laser signal with the wavelength of 1550 nm;
an S42 pulse laser signal enters the sensing optical fiber 8 after passing through the wavelength division multiplexer 602, backward scattered light sensitive to temperature is generated in the process that the laser light propagates in the sensing optical fiber 8, the backward scattered light is divided into two paths after entering the wavelength division multiplexer 602, one path is anti-Stokes light (AS light) with the wavelength of 1450nm, and the other path is Stokes light (S light) with the wavelength of 1663 nm;
the S43 wavelength division multiplexer 602 outputs AS light to enter a first photoelectric receiving conversion circuit 603, the first photoelectric receiving conversion circuit converts an AS light signal into a voltage signal, and amplifies the voltage signal to meet the input requirement of an A/D acquisition module to obtain a voltage signal V1; the S light output by the wavelength division multiplexer 602 enters a second photoelectric receiving and converting circuit 604, the second photoelectric receiving and converting circuit converts the S light signal into a voltage signal, and amplifies the voltage signal to meet the input requirement of the a/D acquisition module 605, so as to obtain a voltage signal V2;
the S44 laser 601 provides synchronous trigger signal for the A/D acquisition module 605 when emitting pulse laser signal, and the A/D acquisition module 605 starts to acquire; the voltage signal V1 and the voltage signal V2 enter the a/D acquisition module 605 respectively, the a/D acquisition module 605 completes analog-to-digital conversion and signal acquisition of V1 and V2, and performs accumulation and average processing on the acquired digital signals to obtain digital signals Vd1 and Vd2 respectively;
the digital signals Vd1 and Vd2 output by the S45A/D acquisition module are transmitted to the upper computer 606, the upper computer 606 performs demodulation operation to obtain a temperature curve in the container, and the data are transmitted to the data storage module 607 to be stored.
The ultrasonic liquid level measurement system and the method adopting the DTS for sound velocity compensation provided by the invention reduce the problem that the ultrasonic liquid level measurement precision is greatly influenced by the environmental temperature, improve the system measurement precision, and are simultaneously suitable for liquid level measurement of corrosive liquid.
The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (10)
1. An ultrasonic liquid level measurement system using DTS for sound velocity compensation, comprising: the device comprises an ultrasonic probe (1), a waveguide tube (2), a transmitting circuit (3), a receiving circuit (4), a controller (5), a DTS optical fiber temperature sensing module (6) and a display module (7); wherein:
ultrasonic probe (1): receiving a pulse signal input by a transmitting circuit (3), generating an ultrasonic signal under the action of the pulse signal and transmitting the ultrasonic signal to the liquid level through a waveguide tube (2); receiving the liquid surface reflection ultrasonic wave returned by the waveguide tube (2), realizing the mutual conversion of the liquid surface reflection ultrasonic wave and a voltage signal, and outputting the voltage signal to a receiving circuit (4);
waveguide (2): transmitting an ultrasonic signal generated by the ultrasonic probe (1) to the liquid level, and transmitting the ultrasonic wave reflected by the liquid level to the ultrasonic probe (1);
transmitting circuit (3): the pulse signal input by the controller (5) is amplified and then output to the ultrasonic probe (1);
reception circuit (4): the voltage signal input by the ultrasonic probe (1) is amplified, filtered, detected and shaped, and an interrupt signal is generated and output to the controller (5);
controller (5): outputting the pulse signal to a transmitting circuit (3) and starting timing; receiving an interrupt signal input by a receiving circuit (4), stopping timing, recording the time between the start of timing and the stop of timing as a time signal of ultrasonic wave propagation, and outputting the time signal to a DTS optical fiber temperature sensing module (6);
DTS optical fiber temperature sensing module (6): receiving an ultrasonic wave propagation time signal input by the controller (5), measuring the temperatures at different heights in the closed container, calculating the sound velocity according to the measured temperatures, calculating the liquid level value by combining the ultrasonic wave propagation time signal and the sound velocity, and outputting the liquid level value to the display module (7);
display module (7): and receiving and displaying the liquid level value input by the DTS temperature sensing module (6).
2. An ultrasonic level measurement system with sound speed compensation using DTS according to claim 1, characterized in that the transmitting circuit (3) is an amplitude amplifying circuit.
3. An ultrasonic level measurement system with sound speed compensation using DTS according to claim 1, characterized in that the ultrasonic probe (1) is a piezoelectric type ultrasonic transducer.
4. An ultrasonic level measuring system with DTS for sound speed compensation according to claim 1, wherein the waveguide (2) is a hollow rigid cylinder, which is sleeved on the lower end of the ultrasonic probe (1) and has a length less than or equal to the height of the inside of the container.
5. An ultrasonic level measurement system using DTS for sound speed compensation according to claim 1, wherein the receiving circuit (4) comprises an amplifying circuit (401), a filtering circuit (402), an envelope detection circuit (403) and a shaping circuit (404), the output terminal of the ultrasonic probe (1) is connected to the input terminal of the amplifying circuit (401), the output terminal of the amplifying circuit (401) is connected to the input terminal of the filtering circuit (402), the output terminal of the filtering circuit (402) is connected to the input terminal of the envelope detection circuit (403), the output terminal of the envelope detection circuit (403) is connected to the input terminal of the shaping circuit (404), and the output terminal of the shaping circuit (404) is connected to the input terminal of the controller (5).
6. The ultrasonic liquid level measurement system adopting the DTS for sound speed compensation is characterized in that the DTS optical fiber temperature sensing module (6) comprises a laser (601), a wavelength division multiplexer (602), a first photoelectric conversion circuit (603), a second photoelectric conversion circuit (604), an A/D acquisition module (605), an upper computer (606), a data storage module (607) and a sensing optical fiber (8);
the output end of the laser (601) is connected with the input end of a wavelength division multiplexer (602), the wavelength division multiplexer (602) is connected with the sensing optical fiber (8) through a bidirectional port, the first output end and the second output end of the wavelength division multiplexer (602) are respectively connected with the input ends of a first photoelectric conversion circuit (603) and a second photoelectric conversion circuit (604), the output ends of the first photoelectric conversion circuit (603) and the second photoelectric conversion circuit (604) are both connected with the input end of the A/D acquisition module (605), the output end of the A/D acquisition module (605) is connected with the input end of the upper computer (606), the output end of the upper computer (606) is connected with the input end of the data storage module (607), and the output end of the upper computer (606) is connected with the display module (7);
the sensing optical fiber (8) is arranged on the outer surface of the waveguide tube (2) from bottom to top along the axis in parallel, and the signal returns to the wavelength division multiplexer (602) again after being transmitted by the sensing optical fiber (8).
7. An ultrasonic liquid level measuring method using DTS for sound velocity compensation, which is performed using the ultrasonic liquid level measuring system using DTS for sound velocity compensation of any one of claims 1 to 6, comprising the steps of:
s1, the controller (5) generates a pulse signal and starts timing, the pulse signal is input into the transmitting circuit (3), and the transmitting circuit (3) drives the ultrasonic probe (1) to transmit an ultrasonic signal to the liquid surface to be measured through the waveguide tube (2);
s2 echo signals reflected by the measured liquid surface are received by the ultrasonic probe (1) through the waveguide tube (2), an interrupt signal is generated after the echo signals enter the receiving circuit (4), and the controller (5) stops timing;
s3, the controller (5) calculates the propagation time of the ultrasonic signal and transmits the propagation time to the DTS optical fiber temperature sensing module (6);
s4, the DTS optical fiber temperature sensing module (6) acquires the temperature value in the closed container in real time, the sound velocity can be calculated according to the temperature value, the liquid level height in the container can be acquired by combining the propagation time information acquired in the step S3, and the liquid level height is displayed in real time through the display module (7).
8. The ultrasonic liquid level measuring method using the DTS for sound speed compensation according to claim 7, wherein in the step S4, the DTS optical fiber temperature sensing module (6) comprises a laser (601), a wavelength division multiplexer (602), a first photoelectric conversion circuit (603), a second photoelectric conversion circuit (604), an A/D acquisition module (605), an upper computer (606), a data storage module (607) and a sensing optical fiber (8);
the specific steps of the DTS optical fiber temperature sensing module for acquiring the temperature value are as follows:
the method comprises the following steps that S41 a laser (601) emits a pulse laser signal, a trigger signal is provided for an A/D acquisition module (605) at the same time, and the A/D acquisition module (605) starts to acquire;
s42 pulse laser signals enter the sensing optical fiber (8) after passing through the wavelength division multiplexer (602);
backward scattered light generated by the propagation of the S43 pulse laser signal in the sensing optical fiber (8) is divided into anti-Stokes light and Stokes light by the wavelength division multiplexer (602), and the anti-Stokes light and the Stokes light respectively enter the first photoelectric receiving conversion circuit (603) and the second photoelectric receiving conversion circuit (604) to complete photoelectric conversion and signal amplification processing to obtain voltage signals V1 and V2;
s44 voltage signals V1 and V2 enter an A/D acquisition module (605), and the A/D acquisition module (605) finishes accumulation and average processing on the acquired signals to obtain acquired signals Vd1 and Vd 2;
and S45Vd1 and Vd2 enter the upper computer (606), demodulate temperature information in the container and transmit the temperature information to the data storage module (607) for storage.
9. The ultrasonic liquid level measuring method using DTS for sound speed compensation according to claim 7, wherein in step S4, the sound speed is calculated from the temperature according to the formula v being 331.45+0.607T, where v is the ultrasonic sound speed and T is the ambient temperature.
10. The ultrasonic liquid level measuring method using DTS for sound velocity compensation according to claim 7, wherein the information of the liquid level height in step S4 is obtained from the formula H-L-v-t/2, where v represents the ultrasonic sound velocity, t is the propagation time of the ultrasonic wave, H is the liquid level height, and L is the total height in the container.
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