Externally-attached eight-sound-channel ultrasonic gas flow measuring device and measuring method

Abstract

The invention relates to the technical field of gas flow measurement, and discloses an externally-attached eight-channel ultrasonic gas flow measurement device and method, and the device comprises a computer, a speed measurement circuit board, a thickness measurement circuit board, a speed measurement probe, a thickness measurement probe, a speed measurement power board, a thickness measurement power board, a serial port line, a data acquisition card and a data acquisition card power supply; a plurality of data acquisition cards and a plurality of data acquisition card power supplies are arranged, and each data acquisition card power supply is connected with one data acquisition card; the speed measuring circuit board is connected with the speed measuring probe, the thickness measuring circuit board is connected with the speed measuring probe, a signal output end of the computer is connected with a signal input end of the speed measuring circuit board through a serial port line, the speed measuring circuit board is connected with the speed measuring power board, and a signal output end of the speed measuring circuit board is connected with a signal input end of the computer through the data acquisition card. And the speed measuring probe and the thickness measuring probe are attached in the measuring pipeline. According to the invention, the design requirements of synchronous and multi-probe gas flow measurement can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of gas flow measurement, and particularly relates to an externally attached eight-channel ultrasonic gas flow measurement device and a measurement method. Background Art

[0002] At present, the methods for ultrasonic measurement include the propagation velocity difference method, the Doppler method, the correlation method, the beam offset method, the noise method, etc.

[0003] The propagation velocity difference method realizes flow measurement based on the velocity difference generated when ultrasonic waves propagate in the upstream and downstream directions. The propagation velocity difference method includes the time difference method, the frequency difference method, and the phase difference method, which respectively realize flow measurement based on the time difference, frequency difference, and phase difference of ultrasonic waves in the upstream and downstream directions. The frequency difference method has unstable circuit performance, the phase difference method is easily affected by temperature, and the time difference method has high accuracy and is widely used.

[0004] The Doppler method realizes flow velocity measurement based on the Doppler effect of acoustics. When ultrasonic waves encounter impurities or bubbles in the fluid, a Doppler frequency shift will be generated, and the magnitude of the frequency shift is related to the flow velocity of the fluid.

[0005] The correlation method is based on the correlation theory of the digital characteristics of a random process, and uses the correlation processing technology of mathematical analysis to perform a cross-correlation operation on the acoustic wave signals modulated by the fluid in the pipeline to be measured, and then the fluid flow velocity can be calculated. Two pairs of ultrasonic transducers with exactly the same performance are arranged at a certain distance on the pipeline. When the fluid flows, the two ultrasonic transmitting transducers simultaneously transmit the same ultrasonic wave signal, and the ultrasonic wave signal is received by the two receiving transducers after flowing through the fluid. The different the flow velocity is, the different the correlation degree of the two signals is. According to the correlation of the signals, the flow velocity can be analyzed.

[0006] The beam offset method realizes flow velocity measurement by using the ultrasonic offset angle. The ultrasonic transducer is divided into two types: a transmitting transducer and a receiving transducer. When the fluid is in a static state, the signal intensities received by the two ultrasonic transducers are the same; when the fluid flows, the propagation direction of the ultrasonic wave changes with the flow velocity, and the offset angle of the ultrasonic wave is obtained from the signal intensity difference between the two transducers.

[0007] The noise method realizes flow velocity measurement by using the magnitude of the noise generated during the fluid flow process. Ultrasonic waves are a kind of mechanical waves. When ultrasonic waves propagate in the fluid, they carry the noise generated by the fluid flow. By detecting the received signal and determining the magnitude of the noise it carries, the flow velocity can be determined.

[0008] Currently, Hironari Obayashi proposed a method to enable multi-dimensional linear flow field velocity vector measurement. The system realizes the measurement by using multiple transducers to obtain the velocity profile; in the research of B. Watson, the continuous demand for a large number of actuators smaller than 1 cubic meter has led researchers to design a large number of micron-level products, and proposed that we should create a new classification system for piezoelectric ultrasonic sensors so that we can better understand the core characteristics of each sensor, which sensor is most suitable for various applications, and the in-depth potential of the sensor in future research; Li-Hong Juang studied the use of a three-dimensional mechanical element with an externally applied electronic degree of freedom to realize the simulation of linear piezoelectric dynamic vibration modes, piezoelectric mechanics, and the mechanical behavior of embedding a metal disc structure in a piezoelectric actuator; M. Garcia-Rodriguez studied the low-cost matching network of high-impedance ultrasonic transducers. The key to matching the impedance of the output actuator to a high-impedance transducer is to maximize the energy of the transducer and improve the transmission efficiency of the transducer, and obtain a better signal-to-noise ratio. Although the ultrasonic flowmeters in our country cannot reach the international advanced level at present, researchers and technicians are constantly developing new methods and technologies to enable domestic products to continuously expand the market. Sun Jian proposed a new type of ultrasonic flowmeter applied in oil wells. The measurement of this flowmeter relies on the propagation time of ultrasonic pulses in the downstream and upstream directions. The ultrasonic transmission channel is used to prevent the disadvantage of high viscosity of oil. Two time-delay estimation methods are experimentally studied and realized: the threshold method and the cross-correlation method. In 2011, Zheng Dandan studied and improved the measurement performance of the dry calibration of ultrasonic flowmeters, analyzed the influence of computational fluid dynamics modeling methods on the external clamping and internal embedding of transducers and the accuracy of ultrasonic flowmeters. The final measurement results show that the external clamping installation method can measure smaller measurement errors and is a better installation method for ultrasonic flowmeter transducers.

[0009] However, due to the fact that during the gas flow detection process, ultrasonic flowmeters at home and abroad cannot measure the flow velocity of the flowing fluid at the same time point, there is a problem of large errors in existing ultrasonic flowmeters. Summary of the Invention

[0010] The object of the present invention is to provide an externally attached eight-channel ultrasonic gas flow measurement device and a measurement method to achieve the design requirements of synchronous and multi-probe gas flow measurement. There is no need to drill holes or disassemble the pipeline, and the flow velocity of the gas in the pipe can be measured with high precision, and the gas flowmeter that is not suitable for disassembly can be calibrated.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] In a first aspect, the present invention provides an externally attached eight-channel ultrasonic gas flow measurement device, which includes a computer, a velocity measurement circuit board, a thickness measurement circuit board, a velocity measurement probe, a thickness measurement probe, a velocity measurement power supply board, a thickness measurement power supply board, a serial cable, a data acquisition card, and a data acquisition card power supply;

[0013] The data acquisition card and the data acquisition card power supply are provided in multiple numbers, and each data acquisition card power supply is connected to one data acquisition card;

[0014] The velocity measurement circuit board is connected to the velocity measurement probe, and the thickness measurement circuit board is connected to the velocity measurement probe;

[0015] The signal output end of the computer is connected to the signal input end of the velocity measurement circuit board through one serial cable, the velocity measurement circuit board is connected to the velocity measurement power supply board, the signal output end of the velocity measurement circuit board is connected to the signal input end of one data acquisition card, and the signal output end of the data acquisition card is connected to the signal input end of the computer;

[0016] The signal output end of the computer is connected to the signal input end of the thickness measurement circuit board through one serial cable, the thickness measurement circuit board is connected to the thickness measurement power supply board, the signal output end of the thickness measurement circuit board is connected to the signal input end of one data acquisition card, and the signal output end of the data acquisition card is connected to the signal input end of the computer;

[0017] Both the velocity measurement probe and the thickness measurement probe are adhesively arranged inside the measurement pipeline.

[0018] Furthermore, multiple velocity measurement probes are provided, and the multiple velocity measurement probes are symmetrically arranged on both sides of the inner wall of the measurement pipeline.

[0019] Furthermore, the computer is configured to:

[0020] Obtain the downstream propagation time and upstream propagation time of ultrasonic waves;

[0021] Determine the time difference between downstream and upstream propagation based on the downstream propagation time and upstream propagation time of the ultrasonic waves;

[0022] Determine a flow velocity calculation formula according to the time difference between downstream and upstream propagation;

[0023] Determine the flow velocity signals corresponding to each velocity measurement probe according to the flow velocity calculation formula, and calculate the average velocity based on the flow velocity signals;

[0024] Calculate the pipeline thickness according to the propagation time of the ultrasonic waves emitted by the thickness measurement probe in the measurement pipeline;

[0025] Calculate the flow rate based on the flow velocity of the fluid and the pipeline thickness.

[0026] Further, the computer is further configured to;

[0027] Determine the relationships between the downstream propagation time and the upstream propagation time of the ultrasonic wave and the flow velocity, as shown in the following formulas (1) and (2) respectively:

[0028]

[0029] In the formula, T 1 is the downstream propagation time of the ultrasonic wave, L is the distance between the two transducers of the velocity measurement probe, c is the ultrasonic velocity, v is the flow velocity of the fluid, θ is the angle between the upper side wall of the measurement pipe and the velocity measurement probe, and T 2 is the upstream propagation time of the ultrasonic wave.

[0030] Further, the computer is further configured to:

[0031] Transform formula (1) to get:

[0032]

[0033] Transform formula (3) to get:

[0034]

[0035] Subtract formula (2) from formula (4) to get:

[0036]

[0037] The calculation formula for the time difference ΔT of the upstream and downstream propagation is:

[0038] ΔT = T 2 -T 1 (6)

[0039] According to formula (5) and formula (6), determine the flow velocity calculation formula, expressed as:

[0040] .

[0042] Further, the computer is further configured to:

[0043] Determine the flow velocity signals corresponding to each velocity measurement probe through the following formulas (8) to (11):

[0044]

[0045] In the formula, v 1 , v 2 , v 3 and v 4respectively represent the first flow velocity signal, the second flow velocity signal, the third flow velocity signal, and the fourth flow velocity signal, ΔT 1 , ΔT 2 , ΔT 3 and ΔT 4 respectively represent the time difference of the first forward and reverse propagation, the time difference of the second forward and reverse propagation, the time difference of the third forward and reverse propagation, and the time difference of the fourth forward and reverse propagation;

[0046] Based on formulas (8) to (11), the average velocity is obtained through the following formula (12):

[0047]

[0048] In the formula, represents the average velocity.

[0049] Furthermore, the computer is further configured to:

[0050] According to the propagation time of the ultrasonic wave emitted by the thickness measurement probe in the measurement pipeline, calculate the pipeline thickness through the following formula (13):

[0051]

[0052] In the formula, δ represents the pipeline thickness; t represents the time required for the ultrasonic wave to travel back and forth once in the measurement pipeline; c is the ultrasonic wave velocity.

[0053] In a second aspect, the present invention provides a measurement method for an externally attached eight-channel ultrasonic gas flow measurement device as described above, and the measurement method includes:

[0054] Obtain the forward propagation time and reverse propagation time of the ultrasonic wave;

[0055] Based on the forward propagation time and reverse propagation time of the ultrasonic wave, determine the time difference of the forward and reverse propagation;

[0056] According to the time difference of the forward and reverse propagation, determine the flow velocity calculation formula;

[0057] According to the flow velocity calculation formula, determine the flow velocity signals corresponding to each velocity measurement probe, and calculate the average velocity based on the flow velocity signals;

[0058] Calculate the pipeline thickness according to the propagation time of the ultrasonic wave emitted by the thickness measurement probe in the measurement pipeline.

[0059] Furthermore, the flow velocity calculation formula is determined through the following method:

[0060] Determine the relationships between the forward propagation time and reverse propagation time of the ultrasonic wave and the flow velocity, as shown in the following formulas (1) and (2) respectively:

[0061]

[0062] Wherein, T 1 is the downstream propagation time of the ultrasonic wave, L is the distance between the two transducers of the velocity measurement probe, c is the ultrasonic sound velocity, v is the flow velocity of the fluid, θ is the angle between the upper side wall of the measurement pipeline and the velocity measurement probe, and T 2 is the upstream propagation time of the ultrasonic wave;

[0063] By transforming formula (1), we get:

[0064]

[0065] By transforming formula (3), we get:

[0066]

[0067] Subtracting formula (2) from formula (4), we get:

[0068]

[0069] The calculation formula for the time difference ΔT of upstream and downstream propagation is:

[0070] ΔT = T 2 - T 1 (6)

[0071] According to formula (5) and formula (6), the calculation formula for the flow velocity is determined and expressed as:

[0072]

[0073] Furthermore, the measurement method further includes calculating the flow rate Q based on the flow velocity of the fluid through the following formula (14):

[0074] Q = Av (14)

[0075] Wherein, A is the cross-sectional area of the measurement pipeline.

[0076] The beneficial effects of the present invention are:

[0077] The present invention solves the technical problems that most flow meters on the current market need to perform operations such as disassembling or punching holes in the gas transportation pipeline. By using an externally attached ultrasonic probe, it makes the measurement of gas flow velocity more convenient, reduces the measurement cost, and improves the measurement efficiency. The invention can be used to measure various gases and has a wide range of applications. Description of the Drawings

[0078] Figure 1 Shows the structural layout diagram of an externally attached eight-channel ultrasonic gas flow measurement device according to an embodiment of the present invention;

[0079] Figure 2 Shows an example layout diagram of a speed measurement probe and a thickness measurement probe according to an embodiment of the present invention; among them, (a) is an overall layout example; (b) is a side thickness probe layout example;

[0080] Figure 3 Shows the schematic diagram of the reflection thickness measurement principle for pipeline thickness measurement according to an embodiment of the present invention;

[0081] Figure 4 Shows the schematic diagram of the flow velocity measurement principle according to an embodiment of the present invention;

[0082] Figure 5 Shows the schematic diagram of the AC-DC power supply design according to an embodiment of the present invention;

[0083] Figure 6 Shows the schematic diagram of the high-voltage power supply design according to an embodiment of the present invention;

[0084] Figure 7 Shows the schematic diagram of the control unit design according to an embodiment of the present invention; among them, (a) is the schematic diagram of the control unit design for the flow velocity measurement circuit board, and (b) is the schematic diagram of the control unit design for the pipe wall thickness measurement circuit board;

[0085] Figure 8 Shows the schematic diagram of the communication unit design according to an embodiment of the present invention, where (a) is the schematic diagram of the communication unit design for the flow velocity measurement circuit board, and (b) is the schematic diagram of the communication unit design for the pipe wall thickness measurement circuit board;

[0086] Figure 9 Shows the schematic diagram of the relay drive unit design according to an embodiment of the present invention, where (a) is the schematic diagram of the relay drive unit design for the flow velocity measurement circuit board, and (b) is the schematic diagram of the unit design for the pipe wall thickness measurement circuit board;

[0087] Figure 10 Shows the schematic diagram of the ultrasonic emission unit design according to an embodiment of the present invention, (a) is the schematic diagram of the ultrasonic emission unit design for the flow velocity measurement circuit board, and (b) is the schematic diagram of the ultrasonic emission unit design for the pipe wall thickness measurement circuit board;

[0088] Figure 11 Schematic diagram of the ultrasonic receiving unit design according to an embodiment of the present invention, where (a) is the schematic diagram of the ultrasonic receiving unit design for the flow velocity measurement circuit board, and (b) is the schematic diagram of the ultrasonic receiving unit design for the pipe wall thickness measurement circuit board;

[0089] Figure 12 Flow chart of a measurement method of an external-mounted eight-channel ultrasonic gas flow measurement device according to an embodiment of the present invention.

[0090] Description of reference numerals:

[0091] 1. Computer; 2. Velocity measurement circuit board; 3. Thickness measurement circuit board; 4. Velocity measurement probe; 41. Ultrasonic signal transmitting probe; 42. Ultrasonic signal receiving probe; 5. Thickness measurement probe; 6. Velocity measurement power supply board; 7. Thickness measurement power supply board; 8. Serial port cable; 9. Data acquisition card; 10. Data acquisition card power supply; 11. Measurement pipeline. Specific implementation manners

[0092] The following uses specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0093] The following further describes in detail the specific implementation manners of the present invention in conjunction with the drawings and embodiments.

[0094] Embodiment 1:

[0095] The embodiment of the present invention provides an externally attached eight-channel ultrasonic gas flow measurement device, which combines the ultrasonic echo resonance main frequency method. It is a device with convenient installation and strong stability, suitable for measuring the gas flow velocity in a stainless steel pipe by ultrasonic measurement. This device can use an externally attached ultrasonic probe to measure the gas flow velocity in a stainless steel pipe. As Figure 1 shown, it is the structural layout diagram of the externally attached eight-channel ultrasonic gas flow measurement device. The externally attached eight-channel ultrasonic gas flow measurement device includes a computer 1, a velocity measurement circuit board 2, a thickness measurement circuit board 3, a velocity measurement probe 4, a thickness measurement probe 5, a velocity measurement power supply board 6, a thickness measurement power supply board 7, a serial port cable 8, a data acquisition card 9, and a data acquisition card power supply 10; the data acquisition card 9 and the data acquisition card power supply 10 are provided in multiple numbers, and each data acquisition card power supply 10 is connected to a data acquisition card 9; the velocity measurement circuit board 2 is connected to the velocity measurement probe 4, the thickness measurement circuit board 3 is connected to the velocity measurement probe 4, the signal output end of the computer 1 is connected to the signal input end of the velocity measurement circuit board 2 through a serial port cable 8, the velocity measurement circuit board 2 is connected to the velocity measurement power supply board 6, the signal output end of the velocity measurement circuit board 2 is connected to the signal input end of a data acquisition card 9, and the signal output end of the data acquisition card 9 is connected to the signal input end of the computer 1; the signal output end of the computer 1 is connected to the signal input end of the thickness measurement circuit board 3 through a serial port cable 8, the thickness measurement circuit board 3 is connected to the thickness measurement power supply board 7, the signal output end of the thickness measurement circuit board 3 is connected to the signal input end of a data acquisition card 9, and the signal output end of the data acquisition card 9 is connected to the signal input end of the computer 1; both the velocity measurement probe 4 and the thickness measurement probe 5 are attached to the inside of the measurement pipeline 11.

[0096] In a specific embodiment, the speed measurement probe 4 is an externally attached probe, and an ultrasonic probe with a frequency of 100 kHz can be selected. The externally attached thickness measurement probe 5 selects an ultrasonic probe with a frequency of 5 MHz. The measurement pipeline 11 is a pipeline made of stainless steel. The externally attached speed measurement probe 4 and the externally attached thickness measurement probe 5 are installed on the measurement pipeline 11 at equal angles circumferentially. The speed measurement circuit board 2 is connected to the externally attached speed measurement probe 4 and the data acquisition card 9. The data acquisition card 9 is connected to the speed measurement circuit board 2 and the computer 1. The thickness measurement circuit board 3 is connected to the externally attached thickness measurement probe 5 and the data acquisition card 9. The data acquisition card 9 is connected to the thickness measurement circuit board 3 and the computer 1. The computer 1 sends commands to the speed measurement circuit board 2 and the thickness measurement circuit board 3 through a serial cable 8 (such as an RS485 serial cable) to set the excitation voltage of the externally attached ultrasonic probe to excite the externally attached speed measurement probe 4 and the externally attached thickness measurement probe 5 to emit ultrasonic waves. The ultrasonic waves pass through the measurement pipeline 11, and the received probe receives the signal and transmits it to the data acquisition card 9. The data acquisition card transmits the signal to the computer 1 to display the ultrasonic signal to achieve the purpose of measuring the gas flow rate in the measurement pipe. The speed measurement power supply board 6 supplies power to the speed measurement circuit board 2, and the thickness measurement power supply board 7 supplies power to the thickness measurement circuit board 3. The data acquisition card power supply 10 supplies power to the data acquisition card 9. The time difference and wall thickness measured by each ultrasonic probe (including the speed measurement probe 4 and the thickness measurement probe 5) installed on the pipe wall, combined with relevant formulas, are the fluid flow rate. The specific relevant formulas will be introduced in detail later.

[0097] In some embodiments, such as Figure 2 shown, it is a layout example diagram of the speed measurement probe and the thickness measurement probe. As Figure 2 shown in (a) therein, the two side ultrasonic probes are the speed measurement probes 4 for flow rate measurement, and the middle one is the thickness measurement probe 5 for pipeline wall thickness measurement. The speed measurement probe 4 includes an ultrasonic signal transmitting probe 41 and an ultrasonic signal receiving probe 42. The left side probes are 4 ultrasonic signal transmitting probes 41, and the right side probes are installed according to the installation positions of the left side probes. After the thickness measurement probe 5 emits ultrasonic waves, it directly receives the echo signal generated by the same probe. As Figure 2 shown in (b) therein, the number of thickness measurement probes 5 is 8, which are evenly distributed on the pipe wall around the measured pipeline, and the same applies to the two side probes.

[0098] In some embodiments, Figure 3 is the schematic diagram of the reflection type thickness measurement for pipeline thickness measurement. The center frequency of the probe is 10 MHz, and each probe emits and receives by itself. The pipeline wall thickness is measured by measuring the time interval between emission and reception.

[0099] In some embodiments, Figure 4This is the schematic diagram of flow velocity measurement. In the figure, D is the inner diameter of the pipeline for the transmission medium; θ is the angle between the probe and the central axis of the pipeline; v is the flow velocity of the medium; c is the propagation speed of ultrasonic waves in the medium. The central frequency of the probe is 100 kHz, and the flow velocity is calculated by calculating the time difference of propagation in the upstream and downstream directions.

[0100] In some embodiments, as Figure 5 shown, it is the schematic diagram of the AC-DC power supply design. The power supply 10 of the data acquisition card can be selected as an AC-DC power supply, which converts alternating current (AC) into direct current (DC).

[0101] In some embodiments, as Figure 6 shown, it is the schematic diagram of the high-voltage power supply design. The speed measurement power supply board 6 and the thickness measurement power supply board 7 can be selected as high-voltage power supplies, which can convert low voltage into high voltage to drive the ultrasonic probe with a relatively high voltage.

[0102] In some embodiments, the overall structural principles of the speed measurement circuit board 2 and the thickness measurement circuit board 3 are similar. For example, both the speed measurement circuit board 2 and the thickness measurement circuit board 3 can include a control unit, a communication power supply, a relay drive unit, an ultrasonic emission unit, and an ultrasonic reception unit. As Figures 7 to 9 shown, Figure 7 it is the schematic diagram of the control unit design, Figure 7 in which (a) is the schematic diagram of the control unit design of the flow velocity measurement circuit board, Figure 7 and (b) is the schematic diagram of the control unit design of the pipe wall thickness measurement circuit board. Figure 8 It is the schematic diagram of the communication unit design, Figure 8 in which (a) is the schematic diagram of the communication unit design of the flow velocity measurement circuit board, Figure 8 and (b) is the schematic diagram of the communication unit design of the pipe wall thickness measurement circuit board. Figure 9 It is the schematic diagram of the relay drive unit design, Figure 9 in which (a) is the schematic diagram of the relay drive unit design of the flow velocity measurement circuit board, Figure 9 and (b) is the schematic diagram of the unit design of the pipe wall thickness measurement circuit board. Figure 10 It is the schematic diagram of the ultrasonic emission unit design, Figure 10 in which (a) is the schematic diagram of the ultrasonic emission unit design of the flow velocity measurement circuit board, Figure 10 and (b) is the schematic diagram of the ultrasonic emission unit design of the pipe wall thickness measurement circuit board. Figure 11 It is the schematic diagram of the ultrasonic reception unit design, Figure 11 in which (a) is the schematic diagram of the ultrasonic reception unit design of the flow velocity measurement circuit board, Figure 11 and (b) is the schematic diagram of the ultrasonic reception unit design of the pipe wall thickness measurement circuit board.

[0103] Embodiment 2:

[0104] An embodiment of the present invention provides a measurement method based on the externally attached eight-channel ultrasonic gas flow measurement device provided in Embodiment 1. For the specific structure and working principle of the externally attached eight-channel ultrasonic gas flow measurement device, please refer to Embodiment 1 described above, and will not be repeated here.

[0105] This measurement method can be configured in the computer 1 in the form of software and / or circuit modules and implemented by the computer 1. Specifically, as Figure 12 shown, it includes the following steps S10 to S60.

[0106] S10: Obtain the downstream propagation time and upstream propagation time of the ultrasonic wave;

[0107] S20: Determine the time difference between downstream and upstream propagation based on the downstream propagation time and upstream propagation time of the ultrasonic wave;

[0108] S30: Determine the flow velocity calculation formula according to the time difference between downstream and upstream propagation;

[0109] S40: Determine the flow velocity signals corresponding to each velocity measurement probe according to the flow velocity calculation formula, and calculate the average velocity based on the flow velocity signals;

[0110] S50: Calculate the pipe thickness according to the propagation time of the ultrasonic wave emitted by the thickness measurement probe in the measurement pipe;

[0111] S60: Calculate the flow rate based on the flow velocity of the fluid and the pipe thickness.

[0112] Among them, steps S10 to S40 are used to measure the flow velocity, step S50 is used to measure the pipe thickness, and step S60 is used to calculate the flow rate.

[0113] Specifically, the way to measure the flow velocity is to perform mathematical analysis by measuring the propagation time difference between the downstream and upstream propagation of ultrasonic signals in the gas to be measured, and calculate the gas flow rate to be measured. A transceiver-integrated ultrasonic transducer is installed at the upstream and downstream of the pipe section, and the two transducers are installed opposite to each other on both sides of the pipe section. The included angle θ between the axis of the pipe where the gas to be measured flows and the ultrasonic signal propagation path is determined by the flowmeter itself and is a fixed value (the ultrasonic propagation path between the opposite transducers is called a sound channel, and the propagation direction of the ultrasonic signal will be slightly affected by the flowing gas to be measured. In this article, it is considered that the ultrasonic signal propagates linearly along the sound channel). The upstream ultrasonic transducer emits an ultrasonic signal, and the downstream transducer receives this ultrasonic signal to measure the forward ultrasonic signal propagation time; similarly, transducer B emits an ultrasonic signal, and transducer A receives the signal to measure the reverse ultrasonic signal propagation time. The ultrasonic transit time is the downstream propagation time denoted as T 1 , and the upstream propagation time denoted as T 2 .

[0114] The flow model selection of the ultrasonic base meter pipeline includes a theoretical model with three parameters: two forward and reverse transit times and the time difference. As follows:

[0115] Flow model: The transit time and time difference model ignore the radial propagation time of ultrasonic waves. The forward flow propagation time of ultrasonic waves is T 1 :

[0116]

[0117] In the formula:

[0118] D——Pipe diameter, mm

[0119] L——Distance between transducer A and transducer B, mm

[0120] c——Ultrasonic sound velocity, m / s

[0121] v——Flow velocity of the fluid, m / s

[0122] θ——Angle between the upper side pipe wall and the probe A, D, set to 45°

[0123] Formula transformation:

[0124]

[0125] The reverse flow propagation time of ultrasonic waves is T 2 :

[0126]

[0127] Formula transformation:

[0128]

[0129] Subtracting formula (2) from formula (4) gives:

[0130]

[0131] The time difference ΔT between forward and reverse flow propagation is:

[0132] ΔT = T 2 -T 1 (6)

[0133] The root flow velocity is:

[0134]

[0135] Similarly, the multi-channel flow velocity measurement can reach up to 8 speeds. 4 groups of velocity data are measured for DN150 and below, and 8 groups of velocity data are measured for DN150 and above

[0136] Here, take those below DN150 as an example

[0137] That is:

[0138]

[0139] In the formula, v 1 , v 2 , v 3 and v 4 respectively represent the first flow velocity signal, the second flow velocity signal, the third flow velocity signal and the fourth flow velocity signal, and ΔT 1 , ΔT 2 , ΔT 3 and ΔT 4 respectively represent the time difference of the first forward and reverse propagation, the time difference of the second forward and reverse propagation, the time difference of the third forward and reverse propagation and the time difference of the fourth forward and reverse propagation;

[0140] The average velocity is obtained as:

[0141]

[0142] In the formula, represents the average velocity.

[0143] The measurement of the pipe wall thickness is based on the reflection measurement principle, and the thickness measurement method is the pulse reflection ultrasonic thickness measurement method. This method has low requirements for the flatness of the surface of the test piece, can measure the thickness of rough surfaces, concave and convex surfaces, and materials with paint, and has strong adaptability. Therefore, it is widely used in the measurement of the pipe wall thickness of industrial pipelines. When the pulse signal emitted by the ultrasonic probe reaches the material interface through the test piece, the pulse signal is reflected and an echo is generated. The echo signal returns along the original path and is received by the probe. By measuring the propagation time of the ultrasonic wave in the test piece, the thickness δ of the test piece can be calculated. The calculation formula is as follows:

[0144]

[0145] In the formula:

[0146] c — The wave velocity in the test piece to be measured, m / s

[0147] t — The time required for the ultrasonic wave to travel back and forth in the test piece to be measured once.

[0148] The flow rate Q refers to the volume of fluid passing through the pipe cross-section per unit time, usually expressed in cubic meters per second (m 3 / s). The gas flow velocity measurement module measures the average value of the gas flow velocity in the pipe, and the pipe wall thickness measurement module measures the wall thickness of the pipe, calculates the cross-sectional area of the pipe, and the flow rate is equal to the cross-sectional area multiplied by the flow velocity. The calculation formula is as follows:

[0149] Q = Av (14)

[0150] In the formula:

[0151] A——the cross-sectional area of the pipeline to be measured.

[0152] v——the flow velocity of the gas in the pipeline.

[0153] In summary, the present invention solves the technical problems that most flow meters on the current market need to perform operations such as disassembling or punching the gas transportation pipeline. By using external ultrasonic probes, it makes the measurement of gas flow velocity more convenient, reduces the measurement cost, and improves the measurement efficiency. The invention can be used to measure a variety of gases and has a wide range of applications.

[0154] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those of ordinary skill in the relevant technical fields can also make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention shall be defined by the claims.

Claims

1. An external eight-channel ultrasonic gas flow measurement device, characterized in that: Including computer, speed measuring circuit board, thickness measuring circuit board, speed measuring probe, thickness measuring probe, speed measuring power board, thickness measuring power board, serial port line, data acquisition card and data acquisition card power supply; The data acquisition card and the data acquisition card power supply are provided in plurality, and each data acquisition card power supply is connected to one data acquisition card; The speed measuring circuit board is connected to the speed measuring probe, and the thickness measuring circuit board is connected to the speed measuring probe; The signal output end of the computer is connected to the signal input end of the speed measuring circuit board through one of the serial port lines, the speed measuring circuit board is connected to the speed measuring power board, the signal output end of the speed measuring circuit board is connected to the signal input end of one of the data acquisition cards, and the signal output end of the data acquisition card is connected to the signal input end of the computer; The signal output end of the computer is connected to the signal input end of the thickness measuring circuit board through one of the serial port lines, the thickness measuring circuit board is connected to the thickness measuring power board, the signal output end of the thickness measuring circuit board is connected to the signal input end of one of the data acquisition cards, and the signal output end of the data acquisition card is connected to the signal input end of the computer; The velocity measuring probe and the thickness measuring probe are both attached and arranged in the measuring pipe.

2. The external eight-channel ultrasonic gas flow measurement device according to claim 1, characterized in that: The velocity measuring probes are provided in plurality, and the plurality of velocity measuring probes are symmetrically arranged on both sides of the inner wall of the measuring pipe.

3. The external eight-channel ultrasonic gas flow measurement device according to claim 1, characterized in that: The computer is configured to: Obtain the downstream propagation time and upstream propagation time of the ultrasonic wave; Determine the time difference between upstream and downstream propagation based on the downstream propagation time and upstream propagation time of the ultrasonic wave; Determine the flow velocity calculation formula according to the time difference of the forward and reverse flow propagation; Determine the flow velocity signal corresponding to each velocity measuring probe according to the flow velocity calculation formula, and calculate the average velocity based on the flow velocity signal; Calculating the pipe thickness according to the propagation time of the ultrasonic wave emitted by the thickness measuring probe in the measuring pipe; Calculates flow rate based on the fluid velocity and pipe thickness.

4. The external eight-channel ultrasonic gas flow measurement device according to claim 3, characterized in that: The computer is further configured to: The relationship between the downstream propagation time and the upstream propagation time of the ultrasonic wave and the flow velocity is determined as shown in the following formula (1) and formula (2) respectively: Where T1 is the downstream propagation time of the ultrasonic wave, L is the distance between the two transducers of the velocity measuring probe, c is the ultrasonic sound velocity, v is the flow velocity of the fluid, θ is the angle between the upper wall of the measuring pipe and the velocity measuring probe, and T2 is the upstream propagation time of the ultrasonic wave.

5. The external eight-channel ultrasonic gas flow measurement device according to claim 4, characterized in that: The computer is further configured to: Transforming formula (1) we get: Transforming formula (3) yields: Subtracting formula (2) from formula (4), we get: The calculation formula for the time difference ΔT of upstream and downstream propagation is: ΔT=T2-T1 (6) According to formula (5) and formula (6), the flow rate calculation formula is determined as follows: 。 6. The external eight-channel ultrasonic gas flow measurement device according to claim 5, characterized in that: The computer is further configured to: The flow velocity signal corresponding to each velocity measuring probe is determined by the following formulas (8) to (11): Wherein, v1, v2, v3 and v4 represent the first flow velocity signal, the second flow velocity signal, the third flow velocity signal and the fourth flow velocity signal respectively, ΔT1, ΔT2, ΔT3 and ΔT4 represent the time difference of the first upstream and downstream propagation, the second upstream and downstream propagation, the third upstream and downstream propagation and the fourth upstream and downstream propagation respectively; Based on formulas (8) to (11), the average speed is obtained by the following formula (12): In the formula, Indicates average speed.

7. The external eight-channel ultrasonic gas flow measurement device according to claim 3, characterized in that: The computer is further configured to: According to the propagation time of the ultrasonic wave emitted by the thickness measuring probe in the measuring pipe, the pipe thickness is calculated by the following formula (13): In the formula, δ represents the pipe thickness; t represents the time required for the ultrasonic wave to travel back and forth in the measuring pipe; and c is the ultrasonic wave speed.

8. A measurement method based on the external eight-channel ultrasonic gas flow measurement device according to any one of claims 1 to 4, characterized in that: The measuring method comprises: Obtain the downstream propagation time and upstream propagation time of the ultrasonic wave; Determine the time difference between upstream and downstream propagation based on the downstream propagation time and upstream propagation time of the ultrasonic wave; Determine the flow velocity calculation formula according to the time difference of the forward and reverse flow propagation; Determine the flow velocity signal corresponding to each velocity measuring probe according to the flow velocity calculation formula, and calculate the average velocity based on the flow velocity signal; Calculating the pipe thickness according to the propagation time of the ultrasonic wave emitted by the thickness measuring probe in the measuring pipe; Calculates flow rate based on the fluid velocity and pipe thickness.

9. The measuring method according to claim 8, characterized in that: The flow rate calculation formula is determined by the following method: The relationship between the downstream propagation time and the upstream propagation time of the ultrasonic wave and the flow velocity is determined as shown in the following formula (1) and formula (2) respectively: Where, T1 is the downstream propagation time of the ultrasonic wave, L is the distance between the two transducers of the velocity measuring probe, c is the ultrasonic sound velocity, v is the flow velocity of the fluid, θ is the angle between the upper wall of the measuring pipe and the velocity measuring probe, and T2 is the upstream propagation time of the ultrasonic wave; Transforming formula (1) we get: Transforming formula (3) yields: Subtracting formula (2) from formula (4), we get: The calculation formula for the time difference ΔT of upstream and downstream propagation is: ΔT=T2-T1 (6) According to formula (5) and formula (6), the flow rate calculation formula is determined as follows:

10. The measuring method according to claim 8, characterized in that: The measuring method further comprises calculating the flow rate Q based on the flow velocity of the fluid by the following formula (14): Q=Av (14) Where A is the cross-sectional area of ​​the measuring pipe.

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