Ultrasonic gas metering module and double-sonic path distance and sound channel switching self-adaption method

Abstract

The invention relates to an ultrasonic gas metering module and a double-sonic path distance and sound track switching self-adaption method. Two pairs of ultrasonic transducer groups with different working frequencies are arranged in a flow channel of a metering module, two transducers of each pair of ultrasonic transducer groups are mutually transmitted and received to form a sound channel, and the two pairs of ultrasonic transducer groups work independently to form double sound channels of the module; wherein the working sound channels of one pair of ultrasonic transducers with relatively high working frequencies are configured to be conventional sound path distance sound channels, and the working sound channels of the other pair of ultrasonic transducers with relatively low working frequencies are configured to be lengthened sound path distance sound channels. According to the metering module, a transducer with higher frequency is installed in a conventional sound path distance channel, by means of the propagation characteristic of the transducer, the reaction speed is increased, accurate positioning is achieved, and meanwhile the product cost is reduced; a low-frequency transducer is arranged in the lengthened sound path distance sound channel, so that stable metering under high sound velocity is ensured; the corresponding method for switching the sound channels according to the flight time and the sound path distance facilitates selection and judgment of the working sound channels in different sound path distance states.

Description

Technical Field

[0001] The present invention relates to the field of gas metering using ultrasound, and in particular to an ultrasonic gas metering module and a dual-path sound channel switching adaptive method. Background Art

[0002] In the past two years, ultrasonic gas meters based on the time difference method have been increasingly used in the urban gas metering market. At the same time, with the implementation of my country's "dual carbon" plan, hydrogen-blended natural gas is also developing continuously. The first hydrogen-blended high-pressure gas transmission pipeline of Western Natural Gas Company has also started construction, with a total length of 258km and a maximum annual gas transmission of 1.2 billion m3 / h; and the gate station demonstration project of Zhejiang Energy Pinghu Natural Gas Company has a designed hydrogen blending ratio of 30%. The propagation speed of sound waves in pure hydrogen is as high as 1300m / s, which is much higher than 340m / s in air and 430m / s in CH4. The metering accuracy of hydrogen-blended natural gas will be affected by whether the acquisition capacity and method are upgraded after the sound wave speed changes. The increase in gas sound speed will shorten the forward and reverse time difference of sound waves in the transmission of hydrogen-blended natural gas, resulting in an increase in the calculation deviation of gas flow rate, making it difficult for the metering accuracy to meet the standard requirements. Summary of the invention

[0003] In view of the problems existing in the prior art, the object of the present invention is to provide a technical solution of an ultrasonic gas metering module and a dual-path channel switching adaptive method.

[0004] The ultrasonic gas metering module is characterized in that two pairs of ultrasonic transducer groups with different working frequencies are arranged on the flow channel of the metering module, and the two pairs of ultrasonic transducer groups with different working frequencies are arranged in the flow path through which the fluid is to pass. The two ultrasonic transducers of each pair of ultrasonic transducer groups transmit and receive to each other to form a sound channel, and the two pairs of ultrasonic transducer groups work independently to form a dual channel of the module; the working sound channel of one pair of ultrasonic transducers with relatively high working frequencies is configured as a conventional sound path channel, and the working sound channel of the other pair of ultrasonic transducers with relatively low working frequencies is configured as an extended sound path channel.

[0005] The ultrasonic gas metering module is characterized in that the metering module also includes a timing unit, a storage unit, an ultrasonic excitation module, a signal acquisition unit and a micro control unit.

[0006] Timing unit: used to trigger and manage timing tasks; measures the propagation time of ultrasonic signals between a pair of transducers;

[0007] Storage unit: used to store the average value of ultrasonic upstream and downstream flight time measured once according to laboratory experience, the average value of upstream and downstream flight time of the dual-channel ultrasonic transducer measured once calculated by the microcontroller after being collected by the timing unit; store the flow velocity and flow rate data calculated by the microcontroller;

[0008] Ultrasonic excitation module: gives driving voltage to the ultrasonic transducer according to the instruction of the microcontroller unit, so that the ultrasonic transducer is forced to vibrate;

[0009] Signal acquisition unit: open two channels to monitor the voltage output of the ultrasonic transducer of the conventional sound path channel and the extended sound path channel respectively, convert the voltage signal output by the ultrasonic transducer into a digital signal, and transmit it to the micro control unit;

[0010] Microcontrol unit: compares the voltage data or time data obtained by the signal acquisition unit and the timing unit with the threshold value set by the storage unit, determines whether the working condition of a certain channel has changed, selects the working channel that is most suitable for flow measurement under the current working condition, sends the channel excitation instruction to the ultrasonic excitation module and starts timing, so as to realize the switching of the working channel; when the measurement work is carried out after the channel switching is completed, the flow velocity and flow rate are calculated based on the data obtained by the signal acquisition unit and the timing unit, and stored in the storage unit.

[0011] The ultrasonic gas metering module is characterized in that a plurality of parallel diverter plates are installed in the flow channel of the metering module, the diverter plates are perpendicular to the flow channel plane where the ultrasonic transducer is installed, and the diverter plates divide the interior of the flow channel into a plurality of parallel and independent cavities, and any two cavities are selected as measurement flow channels corresponding to two pairs of ultrasonic transducer groups.

[0012] The ultrasonic gas metering module is characterized in that transducer mounting holes are respectively arranged at the corresponding cavity positions upstream and downstream of the flow channel of the metering module, and by controlling the inclination angle of the transducer mounting holes, the sound channel of one pair of ultrasonic transducer groups becomes a conventional sound path channel with a single reflection, and the sound channel of the other pair of ultrasonic transducer groups becomes an extended sound path channel in which the signal is reflected multiple times in the flow channel.

[0013] The ultrasonic gas metering module is characterized in that the conventional sound path sound channel is a V-shaped single reflection sound channel, and the extended sound path sound channel is an N-shaped or W-shaped reflection sound channel.

[0014] The dual-path channel switching adaptive method of the ultrasonic gas metering module is characterized by comprising the following steps:

[0015] S101 Set the preset flight time average T of the two laboratory experiences thresL 、T thresHStored in the storage unit, that is, when the standard gas component gas passes through the conventional sound path channel, the average flight time of a pair of ultrasonic transducers in the conventional sound path channel to complete one measurement is recorded as T thresL When the standard gas component passes through the extended sound path channel, the average flight time of a pair of ultrasonic transducers in the extended sound path channel to complete one measurement is recorded as T thresH ;

[0016] S102 The microcontroller sends a command to the ultrasonic excitation module to start periodic sampling for the two groups of ultrasonic transducers corresponding to the conventional sound path channel and the extended sound path channel at the same time. When the signal acquisition unit collects a signal in any channel, the analog signal output by the ultrasonic transducer is converted into a digital signal and sent to the microcontroller. The microcontroller instructs the timing unit to calibrate the flight time of one measurement and feed it back to the microcontroller. S103 is calculated by the formula Calculate the average flight time of the ultrasonic transducer in the conventional sound path after one measurement By formula Calculate the average flight time of the ultrasonic transducer in the extended sound path after one measurement S104 microcontroller unit will and The flight time average value T set in the storage unit thresL 、T thresH For comparison:

[0017] S104.1 When the working channel is a normal path channel, if This indicates that the speed of the ultrasonic wave passing through the gas medium increases, so the working sound channel is changed to a sound channel with a longer sound path. After one measurement period is completed, step S102 is executed.

[0018] S104.2 If the current working channel is an extended path channel, if This means that the speed of the ultrasonic wave passing through the gas medium decreases, and the working sound channel is changed into a conventional sound path sound channel;

[0019] After the channel selection in S105, the flow channel metering work is carried out, and after the end of one measurement period, the step S102 is executed. The dual-path channel switching adaptive method of the ultrasonic gas metering module is characterized in that the laboratory empirical flight time average value pre-stored in the storage unit or the signal acquisition unit is extracted from the laboratory's hundreds of thousands of metering instrument test data, including but not limited to temperature, pressure, transducer acquisition voltage, noise amplitude, flight time, and gas sound speed. After that, the optimal threshold value under a certain simulated standard working condition is obtained by using the minimum mean square error as the optimal criterion through the Wiener filter, and a matrix table of multiple working conditions is formed and stored in the micro control unit; when the micro control unit receives the working condition data measured by various sensors of the instrument, the optimal threshold value is selected by looking up the table for later comparison and judgment.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) The metering module of the present invention installs a higher-frequency transducer in the conventional sound path channel, and utilizes its propagation characteristics to improve the reaction speed and precise positioning, while reducing the product cost; a low-frequency transducer is installed in the extended sound path channel to ensure stable measurement under high sound speed; the corresponding method of switching channels according to flight time and sound path is conducive to selection and judgment when the working channel is in different sound path states.

[0022] 2) The product can be installed once to meet different working conditions, especially the measurement after gas quality change or temperature change. In gas media with different sound speeds or under different temperature environments, a large time difference can still be obtained, thereby ensuring stable and reliable measurement accuracy. It is applicable to but not limited to the measurement of natural gas and hydrogen-blended natural gas. The running instrument will not have to be replaced due to large changes in the gas composition, reducing enterprise investment and waste of social resources.

[0023] 3) By using the separator to expand the number of cavity layers in the flow channel, the module can be applied to a larger flow range while ensuring the metering accuracy, thereby expanding the product series specifications. For example, the G4 gas meter in this example can be expanded to G6, G10, G16 and other gas meters.

[0024] 4) Selecting two of the cavities as the measurement channels corresponding to the two pairs of transducer channels has the following advantages compared to placing the two pairs of transducer channels in the same cavity for measurement:

[0025] A. When two groups of ultrasonic transducers are placed in two different cavities for operation, the sound channel reflection point of one group of ultrasonic transducers and the mounting hole of the other group of ultrasonic transducers are not in the same cavity, and no additional staggered position design is required, thus saving space in the direction of flow channel extension, which facilitates the compact design of the internal cavity of the ultrasonic gas meter;

[0026] B. The flow channel adaptation method of the present method requires that the ultrasonic transducers corresponding to the conventional sound path channel and the extended sound path channel be simultaneously excited and periodically sampled, so as to obtain the average value of the flight time after one measurement of each, and therefore depends on the accurate measurement of the flight time. In order to facilitate the staggering of the reflection point and the transducer opening, the single-cavity dual-channel solution generally considers increasing the height of the cavity to facilitate the formation of a height difference in the transducer group. However, increasing the width of the cavity will make the flow field of the cavity complex, and the downstream and upstream time acquisition of the transducer is closely related to the flow field. In this way, it is difficult to ensure the accurate measurement of the flight time. The dual-cavity dual-channel solution can make the height of the dual cavities approximate, and at the same time, the transmitting and receiving center positions of the transducers are placed at the center position of the height of each cavity, so that the flow field environment of the two cavities can be similar, which is convenient for the accurate measurement of the flight time, and thus it is convenient to judge the switching of the channels according to the method of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a logic block diagram of the module structure of the ultrasonic gas metering module of the present invention;

[0028] Figure 2 It is a schematic diagram of the assembly of the WV type double-chamber metering module of the present invention (assembly of the air outlet duct);

[0029] Figure 3 This is a working principle diagram of cavity A of the WV type double cavity metering module of the present invention;

[0030] Figure 4 This is a working principle diagram of the B cavity of the WV type double cavity metering module of the present invention;

[0031] Figure 5 This is a front view of the WV type double-cavity metering module of the present invention (with a transfer tube);

[0032] Figure 6 This is a structural diagram of the air inlet direction of the WV type multi-cavity metering module of the present invention;

[0033] Figure 7 It is a schematic diagram of the dual-cavity assembly of the NV type dual-cavity metering module of the present invention (assembly of the air outlet duct);

[0034] Figure 8 This is a working principle diagram of the C cavity of the NV type double cavity metering module of the present invention;

[0035] Fig. 9 This is a working principle diagram of the D cavity of the NV type double cavity metering module of the present invention;

[0036] Fig.10 This is a front view of the NV type double-cavity metering module of the present invention (with a transfer tube);

[0037] Fig.11It is a flow chart of a dual-path channel switching adaptive method of an ultrasonic gas metering module of the present invention;

[0038] In the figure, 1-A1 transducer, 2-WV type sound path flow channel, 3-B1 transducer, 4-A2 transducer, 5-B2 transducer group, 6-air outlet duct, 7-B cavity, 8-diverter, 9-A cavity, 10-NV type sound path flow channel, 11-C cavity, 12-D cavity, 13-air inlet, 14-large diameter flow channel, 15-multi-layer diverter, 16-connecting flange. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings:

[0040] Aiming at the problem that the current ultrasonic gas meter cannot adapt to the signal acquisition and accurate measurement caused by the change of sound velocity under complex working conditions, the present invention proposes an ultrasonic gas metering module and a dual-path sound channel switching adaptive method.

[0041] like Figure 1 As shown, an ultrasonic gas metering module is provided with two pairs of ultrasonic transducer groups with different working frequencies on the flow path of the metering module, the two pairs of ultrasonic transducer groups with different working frequencies are arranged in the flow path through which the fluid is to pass, the two ultrasonic transducers of each pair of ultrasonic transducer groups transmit and receive to each other to form a sound channel, and the two pairs of ultrasonic transducer groups work independently to form a dual sound channel of the module; the working sound channel of one pair of ultrasonic transducers with relatively high working frequency is configured as a conventional sound path sound channel, and the working sound channel of the other pair of ultrasonic transducers with relatively low working frequency is configured as an extended sound path sound channel.

[0042] The metering module also includes a timing unit, a storage unit, an ultrasonic excitation module, a signal acquisition unit and a micro control unit.

[0043] Timing unit: used for triggering and managing timing tasks; measuring the propagation time of ultrasonic signals between a pair of transducers.

[0044] Storage unit: used to store the average value of ultrasonic upstream and downstream flight time measured once according to laboratory experience, the average value of the upstream and downstream flight time of the dual-channel ultrasonic transducer measured once calculated by the microcontroller after being collected by the timing unit. Store the flow rate and flow data calculated by the microcontroller.

[0045] Ultrasonic excitation module: According to the instructions of the microcontroller unit, the driving voltage is given to the two sets of ultrasonic transducers in the working channel to force the ultrasonic transducers to vibrate.

[0046] Signal acquisition unit: open two channels to monitor the voltage output of the ultrasonic transducer of the conventional sound path channel and the extended sound path channel respectively, convert the voltage signal output by the ultrasonic transducer into a digital signal, and transmit it to the micro control unit.

[0047] Microcontrol unit: compares the voltage data or time data obtained by the signal acquisition unit and the timing unit with the threshold value set by the storage unit, determines whether a certain channel has noise or working condition changes, selects the working channel that is most suitable for flow measurement under the current working condition according to the method described in the present invention, sends a channel excitation instruction to the ultrasonic excitation module and performs timing, thereby realizing the switching of the working channel. When the measurement work is performed after the channel switching is completed, the flow velocity and flow rate are calculated based on the data obtained by the signal acquisition unit and the timing unit, and stored in the storage unit.

[0048] Specifically, several parallel diverter plates are installed in the flow channel of the metering module. The diverter plates are perpendicular to the flow channel plane where the ultrasonic transducers are installed. The diverter plates divide the interior of the flow channel into several parallel and independent cavities. Any two cavities are selected as measurement flow channels corresponding to two pairs of ultrasonic transducer groups.

[0049] Transducer mounting holes are respectively set at the corresponding cavity positions upstream and downstream of the flow channel of the metering module. By controlling the inclination angle of the transducer mounting holes, the sound channel of one pair of ultrasonic transducer groups becomes a conventional sound path channel with a single reflection, and the signal of the other pair of ultrasonic transducer groups is reflected multiple times in the flow channel to form its sound channel into an extended sound path channel. It should be noted that the reflection point position of each ultrasonic sound channel is staggered from the transducer mounting hole to avoid failure of collection after reflection and inability to measure. The conventional sound path channel is a V-type single reflection channel, and the extended sound path channel is an N-type or W-type reflection channel.

[0050] When two groups of ultrasonic transducers are placed in two different cavities for operation, the sound channel reflection point of one group of ultrasonic transducers and the mounting hole of the other group of ultrasonic transducers are not in the same cavity. It is not necessary to stagger the reflection point of the sound channel of each pair of ultrasonic transducers with the transducer mounting hole as in a single cavity flow channel. Therefore, space in the extension direction of the flow channel can be saved, which is convenient for the compact design of the internal cavity of the ultrasonic gas meter. Figure 2 As shown, a WV-type dual-channel ultrasonic metering module is divided into two independent spaces, A cavity 9 and B cavity 7, by a diverter plate 8. The tail of the WV-type sound path flow channel 2 is connected to the air outlet duct 6. Figure 3 As shown, an A1 transducer 1 and an A2 transducer 4 are installed in the A cavity 9, and the signal propagation channel of the pair of transducers is a W-shaped extended sound path channel; the ultrasonic wave emitted by the A1 transducer 1 in the A cavity 9 is received by the A2 transducer 4 after three reflections, and then the A2 transducer 4 emits and is received by the A1 transducer 1 after three reflections, and the transmission time difference Δt is obtained through the downstream and upstream transmission.A , calculate the gas velocity V in the flow channel A After multiple reflections, the flight time of the ultrasonic wave is prolonged, Δt A Compared with the conventional sound path, the flight time is correspondingly increased, thereby improving the measurement accuracy.

[0051] like Figure 4 As shown, B1 transducer 3 and B2 transducer 5 are installed in B cavity 7, and the signal propagation channel of the pair of transducers is a V-shaped conventional sound path channel. The ultrasonic wave emitted by B1 transducer 3 in B cavity 7 is received by B2 transducer 5 after one reflection, and then B2 transducer 5 emits ultrasonic wave, which is received by B1 transducer 3, and the transmission time difference Δt is calculated through the downstream and upstream transmission. B , calculate the gas velocity V in the flow channel B The acoustic path in cavity B is shorter, which is more conducive to low power consumption and refined measurement.

[0052] like Figure 5 As shown, preferably, the cross-sectional areas of cavity A 9 and cavity B 7 of the WV-type dual-channel ultrasonic metering module are set to be equal, and the flow field environments formed therein are similar, so that when the two pairs of transducers need to switch the working channels due to changes in working conditions, the metering results are consistent.

[0053] like Figure 6 As shown, a multi-layer flow divider 15 is arranged in the flow channel to divide the interior of the WV-type large-diameter flow channel 14 into N parallel independent cavities (6 cavities are shown in the figure), and one or two cavities are selected as the measurement channel area, and then connected to the corresponding outlet pipeline through the connecting flange 16. This scheme is convenient for the module to reduce pressure loss when working in the industrial and commercial gas metering device. At the same time, the airflow is initially rectified by the flow divider when entering the air inlet 13, which is convenient for the stability of the flow field and ensures the stability and reliability of the metering. This design is also applicable to the NV-type large-diameter flow channel.

[0054] like Figure 7 As shown, an NV type dual-channel ultrasonic metering module is divided into two independent spaces C cavity 11 and D cavity 12 by a diverter plate 8, and the tail of the NV type sound path flow channel 10 is connected to the outlet duct 6. Figure 8 As shown, an A1 transducer 1 and an A2 transducer 4 are installed in the C cavity 11, and the signal propagation channel of the pair of transducers is an N-type extended sound path channel; the ultrasonic wave emitted by the A1 transducer 1 in the A cavity 9 is received by the A2 transducer 4 after two reflections, and then the A2 transducer 4 emits and is received by the A1 transducer 1 after two reflections, and the transmission time difference Δt is obtained through the downstream and upstream transmission. A , calculate the gas velocity V in the flow channel A After multiple reflections, the flight time of the ultrasonic wave is prolonged, Δt ACompared with the conventional sound path, the flight time is correspondingly increased, thereby improving the measurement accuracy.

[0055] like Fig. 9 As shown, a B1 transducer 3 and a B2 transducer 5 are installed in the D cavity 12, and the signal propagation channel of the pair of transducers is a V-shaped conventional sound path channel; the ultrasonic wave emitted by the B1 transducer 3 in the B cavity 7 is received by the B2 transducer 5 after one reflection, and then the B2 transducer 5 emits the ultrasonic wave, which is received by the B1 transducer 3, and the transmission time difference Δt is calculated by the downstream and upstream transmission. B , calculate the gas velocity V in the flow channel B The acoustic path in cavity B is shorter, which is more conducive to low power consumption and refined measurement.

[0056] like Fig.10 As shown, as a preference, the cross-sectional areas of the C cavity 11 and the D cavity 12 of the NV-type dual-channel ultrasonic metering module are set to be equal, and the flow field environments formed therein are similar, so that when the two pairs of transducers need to switch the working channels due to changes in working conditions, the metering results are consistent.

[0057] Here’s how it works:

[0058] When the working environment (hereinafter referred to as working conditions) in the flow channel of the metering module changes, the gas sound velocity will change. Since the flow channel length remains unchanged and the sound path is fixed, the single transmission and reception measurement time of the ultrasonic transducer group changes. At this time, a flow channel that is easy to ensure the accuracy of signal acquisition should be selected to collect the forward and reverse flow time of the ultrasonic wave through the medium during the transmission and reception cycle to improve the measurement accuracy.

[0059] The specific flow rate calculation method for the conventional working channel and auxiliary channel is as follows:

[0060] According to the propagation characteristics of ultrasonic waves in the flow channel, the propagation time under forward and reverse flow is expressed as follows (refer to patent CN106461437B extended range ADC flowmeter):

[0061] Among them, t up is the downstream flight time of the transducer group (e.g. ultrasonic transducer A transmits, ultrasonic transducer B receives), t down is the countercurrent flight time (e.g. ultrasonic transducer B transmits and ultrasonic transducer A receives), L is the distance between the ultrasonic transducer groups, C is the speed of sound, v is the fluid velocity, is the installation angle of the transducer; the propagation time difference Δt is obtained from the downstream and upstream time, as follows:

[0062]

[0063] The angle and distance L are known, and the goal is to measure the fluid velocity v; the sound velocity C of the ultrasonic signal of the known fluid medium composition is a known constant, then only the propagation time t is required up and propagation time t down The difference between the two; however, the sound speed C of ultrasound passing through a fixed medium will change with temperature and is a function of temperature. At the same time, the sound speed C of ultrasound passing through media with different components will also change, so the sound speed C is variable; usually ultrasonic measurement requires measuring the flight time t of a group of ultrasonic transducers sending and receiving signals up and t down , to eliminate the variability of C; the flow rate calculation formula is as follows:

[0064]

[0065] It can be seen that the accuracy of flight time measurement is crucial to the measurement accuracy of flow velocity. When the sound velocity C of the ultrasonic wave changes when passing through the medium, if the sound path L remains unchanged, the larger the sound velocity C, the smaller the t up and t down The smaller the value, the more difficult it is to determine the accuracy of the signal acquisition unit and the timing unit. Therefore, we will consider lengthening the sound path to facilitate accurate acquisition of the flight time in order to obtain an accurate time difference Δt. When the speed of sound C decreases, t up and t down The value of becomes larger. Considering that the ultrasonic signal in the flow channel medium will decay over time, it is necessary to reduce the sound path or change the extended sound path to a normal sound path to facilitate accurate acquisition of the flight time to obtain an accurate time difference Δt. In order to facilitate the judgment of the appropriate sound path for the current working condition, t up and t down The smaller the value of is, the smaller the average value of the sum of the two is. Conversely, t up and t down The larger the value of is, the larger the average value of the sum of the two is. Therefore, consider the measurement flight time t of the transducer group. up and t down The average value of the sum is used for laboratory experience testing to obtain a suitable threshold value, and then the acquisition results of the signal acquisition unit and the timing unit are comprehensively calculated (such as formula 3) and compared with the threshold value to quickly select the appropriate channel.

[0066]

[0067] Among them, t up is the downstream flight time, t down is the countercurrent flight time; the flight time of the two channels is expressed as formula (4) and formula (5):

[0068]

[0069] in, is the average time of the normal sound path channel, t 1up is the downstream propagation time of the conventional sound path, t 1down is the upstream propagation time of the conventional sound path; is the average time of lengthening the sound path, t 2up To lengthen the downstream propagation time of the sound path, t 2down To lengthen the countercurrent propagation time of the sound path.

[0070] Figure 2-Figure 10 The embodiment described above is a case where the flow channel is divided into two or more cavities by a flow divider, and each pair of transducers is installed in one of the cavities. Its working principle is: during operation, the transmission time difference Δt generated by a pair of transducers in the forward and reverse flow is independently measured to calculate the gas flow rate, and then the real-time flow rate Q is obtained through the cross-sectional area ratio of the two cavity sections; for example, if the flow rate obtained in cavity A is V A , the cross-sectional area of ​​cavity A is S A , the cross-sectional area of ​​cavity B is S B , the total flow rate of the device can be obtained as Q = V A *S A / (S A +S B ), similarly, the total flow Q of the device can be calculated through the B cavity, or two Q values ​​can be calculated through the A and B cavity parameters respectively for weighted average, or the real-time flow can be calculated by calibrating the correlation coefficient according to laboratory experience values ​​to reduce the measurement error.

[0071] The present invention also discloses an ultrasonic gas metering module dual-path channel switching adaptive method, the working steps are as follows:

[0072] S101 Set the preset flight time average T of the two laboratory experiences thresL 、T thresH Stored in the storage unit, that is, when the standard gas component gas passes through the conventional sound path channel, the average flight time of a pair of ultrasonic transducers in the conventional sound path channel to complete one measurement is recorded as T thresL When the standard gas component passes through the extended sound path channel, the average flight time of a pair of ultrasonic transducers in the extended sound path channel to complete one measurement is recorded as T thresH ;

[0073] S102 The microcontroller unit sends a command to the ultrasonic excitation module to start periodic sampling for the two groups of ultrasonic transducers corresponding to the conventional sound path channel and the extended sound path channel at the same time. When the signal acquisition unit collects a signal in any channel, it converts the analog signal output by the ultrasonic transducer into a digital signal and sends it to the microcontroller unit. The microcontroller unit instructs the timing unit to calibrate the flight time of one measurement and feeds back to the microcontroller unit. S103 According to formula (4): Calculate the average flight time of the ultrasonic transducer in the conventional sound path after one measurement According to formula (5) Calculate the average flight time of the ultrasonic transducer in the extended sound path after one measurement

[0074] S104 microcontroller unit will and The flight time average value T set in the storage unit thresL 、T thresH Make comparisons;

[0075] S104.1 When the working channel is a normal path channel, if This indicates that the speed of the ultrasonic wave passing through the gas medium increases, so the working sound channel is changed to a sound channel with a longer sound path. After one measurement period is completed, step S102 is executed.

[0076] S104.2 If the current working channel is an extended path channel, if This means that the speed of the ultrasonic wave passing through the gas medium decreases, and the working sound channel is changed into a conventional sound path sound channel;

[0077] After the channel selection in S105, the flow channel metering work is carried out, and after the end of one measurement period, the step S102 is executed. The laboratory empirical flight time average value pre-stored in the storage unit or the signal acquisition unit of the present invention is extracted from the laboratory's hundreds of thousands of metering instrument test data, including but not limited to temperature, pressure, transducer acquisition voltage, noise amplitude, flight time, gas sound speed, etc., and filtered with a Wiener filter, with the minimum mean square error as the optimal criterion, to obtain the optimal threshold under a certain simulated standard working condition, and form a matrix table of multiple working conditions and store it in the micro control unit; when the micro control unit receives the working condition data measured by various sensors of the instrument, it looks up the table to select the optimal threshold for later comparison and judgment.

[0078] The specific examples described in this article are merely illustrative of the spirit of the present invention. A person skilled in the art of the present invention may make various modifications or additions to the specific examples described, or replace them in a similar manner, but this will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims. Although this article uses more terms such as hydrogen-blended natural gas, ultrasonic waves, transducers, and time difference of upstream and downstream transmission, it does not exclude the possibility of using other terms. These terms are used only to more conveniently describe and explain the essence of the present invention. It is contrary to the spirit of the present invention to interpret them as any additional restrictions.

Claims

1. An ultrasonic gas metering module, Features: Two pairs of ultrasonic transducer groups with different working frequencies are arranged on the flow channel of the metering module. The two pairs of ultrasonic transducer groups with different working frequencies are arranged in the flow path through which the fluid is to pass. The two ultrasonic transducers of each pair of ultrasonic transducer groups transmit and receive to each other to form a sound channel. The two pairs of ultrasonic transducer groups work independently to form a dual sound channel of the module; the working sound channel of one pair of ultrasonic transducers with relatively high working frequencies is configured as a conventional sound path channel, and the working sound channel of the other pair of ultrasonic transducers with relatively low working frequencies is configured as an extended sound path channel.

2. An ultrasonic gas metering module according to claim 1, Features The metering module also includes a timing unit, a storage unit, an ultrasonic excitation module, a signal acquisition unit and a micro control unit. Timing unit: used to trigger and manage timing tasks; measures the propagation time of ultrasonic signals between a pair of transducers; Storage unit: used to store the average value of ultrasonic upstream and downstream flight time measured once according to laboratory experience, the average value of upstream and downstream flight time of the dual-channel ultrasonic transducer measured once calculated by the microcontroller after being collected by the timing unit; store the flow velocity and flow rate data calculated by the microcontroller; Ultrasonic excitation module: gives driving voltage to the ultrasonic transducer according to the instruction of the microcontroller unit, so that the ultrasonic transducer is forced to vibrate; Signal acquisition unit: open two channels to monitor the voltage output of the ultrasonic transducer of the conventional sound path channel and the extended sound path channel respectively, convert the voltage signal output by the ultrasonic transducer into a digital signal, and transmit it to the micro control unit; Microcontrol unit: compares the voltage data or time data obtained by the signal acquisition unit and the timing unit with the threshold value set by the storage unit, determines whether the working condition of a certain channel has changed, selects the working channel that is most suitable for flow measurement under the current working condition, sends the channel excitation instruction to the ultrasonic excitation module and starts timing, so as to realize the switching of the working channel; when the measurement work is carried out after the channel switching is completed, the flow velocity and flow rate are calculated based on the data obtained by the signal acquisition unit and the timing unit, and stored in the storage unit.

3. The ultrasonic gas metering module according to claim 1, Features A plurality of parallel shunt plates are installed in the flow channel of the metering module. The shunt plates are perpendicular to the flow channel plane where the ultrasonic transducer is installed. The shunt plates divide the inside of the flow channel into a plurality of parallel and independent cavities. Any two cavities are selected as measurement flow channels corresponding to two pairs of ultrasonic transducer groups.

4. An ultrasonic gas metering module according to claim 1 or 3, Features Transducer mounting holes are respectively arranged at the corresponding cavity positions upstream and downstream of the flow channel of the metering module. By controlling the inclination angle of the transducer mounting holes, the sound channel of one pair of ultrasonic transducer groups becomes a conventional sound path channel with a single reflection, and the sound channel of the other pair of ultrasonic transducer groups becomes an extended sound path channel in which the signal is reflected multiple times in the flow channel.

5. An ultrasonic gas metering module according to claim 1 or 3, Features The conventional sound path sound channel is a V-shaped single reflection sound channel, and the extended sound path sound channel is an N-shaped or W-shaped reflection sound channel.

6. A dual-path channel switching adaptive method for the ultrasonic gas metering module according to claim 1 or 3, Features The steps include: S101 Set the preset flight time average T of the two laboratory experiences thresL、 T thresH Stored in the storage unit, that is, when the standard gas component gas passes through the conventional sound path channel, the average flight time of a pair of ultrasonic transducers in the conventional sound path channel to complete one measurement is recorded as T thresL When the standard gas component passes through the extended sound path channel, the average flight time of a pair of ultrasonic transducers in the extended sound path channel to complete one measurement is recorded as T thresH ; S102 The microcontroller unit sends a command to the ultrasonic excitation module to start periodic sampling for the two groups of ultrasonic transducers corresponding to the conventional sound path channel and the extended sound path channel at the same time. When the signal acquisition unit acquires a signal in any channel, the analog signal output by the ultrasonic transducer is converted into a digital signal and sent to the microcontroller unit. The microcontroller unit instructs the timing unit to calibrate the flight time of one measurement and feeds back to the microcontroller unit. S103 is given by the formula Calculate the average flight time of the ultrasonic transducer in the conventional sound path after one measurement , according to the formula Calculate the average flight time of the ultrasonic transducer in the extended sound path after one measurement ; S104 microcontroller unit will and The flight time average value T set in the storage unit thresL , T thresH For comparison: S104.1 When the working channel is a normal path channel, if ≤ T thresL , indicating that the speed of the ultrasonic wave passing through the gas medium increases, and the working sound channel becomes a sound channel with a longer sound path; After one measurement period ends, execute step S102; S104.2 If the current working channel is an extended path channel, if ≥ T thresH , indicating that the speed of the ultrasonic wave passing through the gas medium becomes smaller, and the working sound channel is changed into a conventional sound path sound channel; After the channel is selected in step S105, the flow channel metering operation is performed. After one measurement period is completed, step S102 is executed.

7. A dual-path channel switching adaptive method for the ultrasonic gas metering module as claimed in claim 6, Features The laboratory empirical flight time average value pre-stored in the storage unit or the signal acquisition unit is obtained by extracting data including but not limited to temperature, pressure, transducer acquisition voltage, noise amplitude, flight time, and gas sound speed from the laboratory's hundreds of thousands of metering instrument test data, and then using a Wiener filter with the minimum mean square error as the optimal criterion to obtain the optimal threshold under a certain simulated standard working condition, forming a matrix table of multiple working conditions and storing it in the micro control unit; when the micro control unit receives the working condition data measured by various sensors of the instrument, it looks up the table and selects the optimal threshold for later comparison and judgment.

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