Method for calibrating a multi-channel ultrasonic flow meter after replacement of a transducer

Abstract

The application discloses a kind of multi-channel ultrasonic flowmeter after replacing transducer correction method, comprising: step S1, the ultrasonic wave downstream and upstream propagation time of each sound channel is measured;Step S2, the flow rate of each sound channel, sound channel coefficient and the average flow rate of flowmeter are obtained;Step S3, whether sound channel is normal work is judged;If all sound channels are normal, execute S4, if there is not normal work sound channel, execute S5;Step S4, the flow rate of each sound channel, each sound channel coefficient and the average flow rate of flowmeter are recorded to sound channel coefficient record table;Step S5, whether new transducer has been replaced is judged, the average flow rate of remaining sound channel is obtained;Step S6, the flow rate of sound channel that has replaced new transducer is obtained by reverse calculation;Step S7, the delay time of sound channel that has replaced new transducer is obtained.The application can be reliably calibrated to new ultrasonic transducer after replacing new ultrasonic transducer of multi-channel ultrasonic flowmeter.

Description

Technical Field

[0001] This invention relates to the field of flow measurement technology, and in particular to a calibration method for a multi-channel ultrasonic flow meter after transducer replacement. Background Technology

[0002] Currently, time-of-flight (TOF) measurement is commonly used for measuring the velocity of media using ultrasound. TOF offers the highest measurement resolution and is the most widely applied method. Its principle involves two ultrasonic transducers transmitting and receiving ultrasonic signals, measuring the flight time of the ultrasonic waves during the forward and reverse strokes, and then calculating the time difference to determine the flow velocity. The commonly used formula is: ; In the formula: It is the time for the ultrasonic wave to travel downstream in the fluid, that is, the time required for transducer A to emit ultrasonic waves and for transducer B to receive ultrasonic waves. D is the time it takes for the ultrasonic wave to travel against the current in the fluid, i.e., the time required for transducer B to emit the ultrasonic wave and for transducer A to receive it; D is the pipe diameter of the ultrasonic flow meter. The angle between the ultrasonic transducer channel and the central axis of the flow meter.

[0003] The formula for calculating the flow velocity in each channel of a multi-channel ultrasonic flow meter is as follows: ; The average flow velocity of the n-channel ultrasonic flow meter is: ; K k This is the flow rate weighting coefficient for each channel.

[0004] However, in practical use, only the time (i.e., duration) between the moment when the CPU in one ultrasonic transducer generates the ultrasonic excitation signal and the moment when another ultrasonic transducer receives the processed ultrasonic reception signal can be measured. This time includes: transducer switching time, ultrasonic flight time, and ultrasonic reception signal processing delay. ; Where: t1 is the time difference (i.e., duration) between the measured ultrasonic signal transmission time and the reception time, t z t is the transducer switching time. f For ultrasonic time of flight, t d Delay for receiving and processing signals.

[0005] This can be simply expressed as: ; Where: t D The signal measurement delay is equal to the transducer switching time t.z With the received signal processing delay t d The sum of these delays is determined by the inherent characteristics of the ultrasonic transducer; different ultrasonic transducers have different delay times.

[0006] From the above formula, it can be seen that when one of the transducers in a multi-channel ultrasonic flow meter fails and is replaced with a new ultrasonic transducer, the transducer switching time t will be reduced. z Ultrasonic signal receiving and processing delay t d Because different transducers can cause variations, flow velocity measurement errors can occur, leading to flow meter inaccuracies exceeding tolerance.

[0007] Therefore, there is an urgent need to develop a technology that can promptly and reliably calibrate the new ultrasonic transducer after replacing it in a multi-channel ultrasonic flow meter, thereby ensuring the accuracy of the flow meter. Summary of the Invention

[0008] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a calibration method for multi-channel ultrasonic flow meters after transducer replacement.

[0009] Therefore, the present invention provides a calibration method for a multi-channel ultrasonic flow meter after transducer replacement, which includes the following steps: Step S1: For a multi-channel ultrasonic flow meter, measure the downstream and upstream propagation times of the ultrasonic waves in each channel in real time. Step S2: Calculate the flow rate of each channel, the coefficient of each channel, and the average flow rate of the flow meter by running calculation formulas (1), (3), and (2); Step S3: Determine whether each channel is working properly through a preset judgment operation; If all channels are working properly, proceed to step S4; if there is a malfunctioning channel in the flow meter, proceed to step S5. Step S4: Record the flow velocity of each channel, the coefficient of each channel, and the average flow velocity of the flow meter obtained in step S2 into a channel coefficient record table, and simultaneously enter the corresponding timestamp of the data. The channel coefficient recording table records the recording timestamp of the average flow rate of each flow meter and the correspondence between the average flow rate and the channel coefficient of each channel at the recording time. Step S5: Continue to determine whether a new transducer has been replaced; If a certain channel has been replaced with a new transducer, the average flow rate of the current flow meter is obtained by running formula (2), and the record timestamp corresponding to the average flow rate of the current flow meter is obtained from the channel coefficient record table in step S4. Then, it is checked whether the record timestamp corresponding to the average flow rate of the current flow meter is after the application time in this field. If the timestamp of the average flow rate record of the current flow meter is after the on-site application time, the average flow rate of the flow meter is calculated according to formula (2) by all the remaining channels of the multi-channel ultrasonic flow meter after removing the replaced channels, and the calculation result is defined as the average flow rate of the remaining channels. Then, step S6 is executed. Step S6: Based on the average flow rate of the remaining channels, obtain the channel coefficient corresponding to the channel with the new transducer from the channel coefficient record table. Then, based on the channel coefficient corresponding to the channel with the new transducer, the average flow rate of the remaining channels, and formula (4), calculate the flow rate of the channel with the new transducer in reverse. Then continue to execute step S7. Step S7: Calculate the delay time of the channel with the new transducer by running the calculation formula (5).

[0010] As can be seen from the technical solution provided by the present invention above, compared with the prior art, the present invention provides a calibration method for a multi-channel ultrasonic flow meter after the transducer is replaced. Its design is scientific and can calibrate the new ultrasonic transducer in a timely and reliable manner after the multi-channel ultrasonic flow meter is replaced with a new ultrasonic transducer, thereby ensuring the accuracy of the flow meter and having significant practical significance.

[0011] The application of this invention solves the problem of excessive accuracy in multi-channel ultrasonic flow meters after replacing the ultrasonic transducer. The multi-channel ultrasonic flow meter replacement and calibration method provided by this invention uses the original other channel transducers to calibrate the newly replaced ultrasonic transducer, which can automatically calibrate the ultrasonic flow meter without returning it to the factory for re-verification, thus ensuring the accuracy of the flow meter. Attached Figure Description

[0012] Figure 1 The overall flowchart of a calibration method for a multi-channel ultrasonic flow meter after transducer replacement provided by the present invention; Figure 2 Here is a flowchart of the transducer replacement operation based on the present invention: Figure 3 This is a schematic diagram of a four-channel ultrasonic flow meter. Detailed Implementation

[0013] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] See Figure 1 This invention provides a calibration method for a multi-channel ultrasonic flow meter after transducer replacement, comprising the following steps: Step S1: For a multi-channel ultrasonic flow meter, measure the downstream and upstream propagation times of the ultrasonic waves in each channel in real time. Step S2: Calculate the flow rate of each channel, the coefficient of each channel, and the average flow rate of the flow meter by running calculation formulas (1), (3), and (2); Step S3: Determine whether each channel is working properly through a preset judgment operation; If all channels are working properly, proceed to step S4; if any channel is not working properly, proceed to step S5. In step S3, the preset judgment operation specifically includes the following steps: Step S31: For each channel in the flow meter, collect the real-time signal strength and real-time signal-to-noise ratio of each channel in real time; Step S32: Compare the real-time signal strength and real-time signal-to-noise ratio of each channel with the normal signal strength amplitude and preset normal signal-to-noise ratio of that channel, respectively. When the real-time signal strength of a certain channel is less than the normal signal strength amplitude of the channel, and / or when the real-time signal-to-noise ratio of a certain channel is lower than the preset normal signal-to-noise ratio of the channel, it is determined that the channel is malfunctioning (i.e. abnormal), and thus it is determined that there is an abnormal channel in the flow meter. When the real-time signal strength of all channels is greater than or equal to the normal signal strength amplitude of the channels, and the real-time signal-to-noise ratio of all channels is greater than or equal to the preset normal signal-to-noise ratio of the channels, all channels are considered to be working normally.

[0015] It should be noted that in this invention, for flow meters, the indicators for diagnosing whether a channel is working properly include two parameters: channel signal strength and signal-to-noise ratio (SNR). Generally, if the channel signal strength is less than 1 / 2 of the normal signal amplitude (this value is common; the judgment standard varies among flow meter manufacturers and is determined by the manufacturer), the signal strength is abnormal. Generally, if the SNR is below 14dB (which is the preset normal SNR; this value is common; the judgment standard varies among flow meter manufacturers and is determined by the manufacturer), the SNR is abnormal.

[0016] In addition, it should be noted that existing multi-channel flow meters of various models have their own fault self-diagnosis function; if the self-diagnosis alarm channel of the flow meter is not working properly, it means that the flow meter is not working properly, and there is a malfunctioning channel; otherwise, all channels are working properly.

[0017] Step S4: The flow velocity of each channel, the coefficient of each channel, and the average flow velocity of the flow meter calculated in step S2 are recorded in a channel coefficient record table, and the recording timestamp (i.e., recording time) of these data are entered at the same time. The channel coefficient recording table records the recording timestamp (i.e., recording time) of the average flow rate of each flow meter and the correspondence between the average flow rate and the channel coefficient of each channel (e.g., the first to fourth channels) at the recording time. Step S5: Continue to determine whether a new transducer has been replaced; If a certain channel has been replaced with a new transducer, the average flow rate of the current flow meter is obtained by running formula (2), and the record timestamp corresponding to the average flow rate of the current flow meter is obtained from the channel coefficient record table in step S4. Then, it is checked whether the record timestamp corresponding to the average flow rate of the current flow meter is after the application time in this field. If the timestamp of the average flow rate record of the current flow meter is after the on-site application time, the average flow rate of the flow meter is calculated according to formula (2) by all the remaining channels of the multi-channel ultrasonic flow meter after removing the replaced channels, and the calculation result is defined as the average flow rate of the remaining channels. Then, step S6 is executed. It should be noted that for a flow meter, if a new transducer is replaced on-site, a replacement indicator will be set. During measurement, staff will manually check if the flow meter has a replacement indicator. If it does, it means the new transducer has been replaced; otherwise, it has not been replaced. Step S6: Based on the average flow rate of the remaining channels, obtain the channel coefficient corresponding to the channel with the new transducer from the channel coefficient record table. Then, based on the channel coefficient corresponding to the channel with the new transducer, the average flow rate of the remaining channels, and formula (4), calculate the flow rate of the channel with the new transducer in reverse. Then continue to execute step S7. Step S7: By running the calculation formula (5), the delay time of the channel with the new transducer has been calculated (i.e., the delay time of this channel compared with the old transducer before replacement). Therefore, the maintenance work after the transducer replacement is completed.

[0018] It should be noted that the field application time refers to the time it takes for the flow meter to be installed in the field pipeline and put into formal operation, which is provided by the user.

[0019] The coefficients of each channel can only be recorded under the on-site flow field conditions after the flow meter is applied in the field. If the timestamp is before the on-site application, it means that the timestamp recorded by the flow meter is not the channel coefficient under the on-site flow field conditions (i.e., not after it is installed in the on-site pipeline). This is not very meaningful on-site. In this case, it can only be returned to the factory for repair. The channel coefficients recorded on-site cannot be used to calibrate the replaced ultrasonic transducer.

[0020] In this invention, specifically, the flow rate of each audio channel is calculated using the following formula:

[0021] Simplified to: , formula (1); In the formula above, Let be the flow rate of the k-th audio channel; k is a natural number greater than 1 and is a counting marker for the vocal tract; The downstream propagation time of the ultrasound measured in the k-channel; The backflow propagation time of ultrasound was measured for the k-channel. The measurement error included in the measured ultrasonic wave propagation time mainly includes the ultrasonic transducer conversion error time and the channel delay error time caused by the signal detection point. The error time is similar in the forward and reverse flow measurement processes, so this formula assumes that this time is the same in forward and reverse flow measurements. The k-channel flow rate measurement coefficient is determined during factory testing.

[0022] In this invention, specifically, the average flow velocity of the multi-channel ultrasonic flow meter is calculated based on the sound channels without transducer replacement. The calculation method is as follows: , formula (2); The average flow velocity of the ultrasonic flow meter. A natural number greater than 1, representing the counting markers for the vocal tracts; This represents the total number of audio channels; The k-channel weighting coefficient is determined during factory testing. The measured k-channel flow velocity.

[0023] In this invention, specifically, the channel coefficients of each channel are calculated using the following formula: , formula (3); The channel coefficients for the k-channel; ; Flow velocity measured for k-channel audio; The average flow rate of the flow meter.

[0024] In this invention, specifically, the reverse calculation of the vocal tract flow velocity is performed using the following formula: , formula (4); The channel velocity of the newly replaced k-channel (the k-channel is the channel of the newly replaced ultrasonic transducer) is to be calculated in reverse. The average flow velocity measured in real time by the flow meter; is the channel coefficient for the k-channel.

[0025] In this invention, specifically, for a channel whose transducer has been replaced, the reverse calculation of its channel delay is performed using the following formula: , formula (5); In formula (5), The chord length of the channel for which the new transducer has been installed; The chord length of any channel (e.g., channel l) that has not had its transducer replaced; The measured time for the downstream flow of any channel (e.g., channel l) without changing the transducer. The delay time for any channel whose transducer has not been replaced (e.g., channel 1); The flow rate of any channel (e.g., channel l) that has not had its transducer replaced.

[0026] This refers to the channel delay error time for the newly replaced k-channel. The actual downstream measurement time for the newly replaced k-channel audio; The newly replaced channel velocity of the k-channel is calculated in reverse. The angle between the sound channel and the central axis of the flow meter.

[0027] In this invention, specifically, Table 1 below is a schematic diagram of the format of the vocal tract coefficient recording table; Table 1 is a record table of channel coefficients. Each time the channel coefficients of each channel are recorded, the average flow rate and total range ratio of the flow meter are first determined to determine which level it belongs to. Then the average flow rate value, the timestamp at that moment (i.e., the recording timestamp) and the channel coefficients of each channel are recorded (obtained by formula (3)).

[0028] Table 1:

[0029] It should be noted that in this invention, the flow points in Table 1 are divided into 10 flow points according to the measurement range of the flow meter, from 10% to 100% of the range.

[0030] For flow meters, the channel coefficient may deviate significantly at different flow points due to different flow fields. By subdividing the entire flow range into 10 flow points, the accuracy of the channel coefficient at all flow points can be guaranteed, thereby ensuring the calibration accuracy of the newly replaced ultrasonic transducer.

[0031] Based on Table 1 above, when calculating the channel velocity in reverse, this invention uses the channel coefficient corresponding to the flow point where the measured ultrasonic flow meter velocity is located.

[0032] In this invention, for specific implementation, see [link to relevant documentation]. Figure 3 As shown, a multi-channel ultrasonic flow meter can be a four-channel ultrasonic flow meter. The flow meter includes four channels, each arranged in parallel, with each channel making a 45° angle with the axis (i.e., the central axis of the flow meter).

[0033] In practice, the ultrasonic flow meter tube body 1000 has four preset openings on each side; Four ultrasonic transducers 101 are sealed and installed in four pre-set openings on one side. Four ultrasonic receiving transducers 102 are sealed and installed in four pre-set openings on the other side. Four ultrasonic transmitting transducers 101 are symmetrically distributed with four ultrasonic receiving transducers 102. An ultrasonic transmitting transducer 101 is used to transmit ultrasonic signals to an ultrasonic receiving transducer 102. The ultrasonic receiving transducer 102 is used to receive the ultrasonic signal emitted by the ultrasonic transmitting transducer 101.

[0034] In the specific implementation of this invention, Figure 3 The procedure for replacing the transducer after a transducer malfunction is detected in the flow meter shown is as follows: Figure 2 As shown: After discovering a transducer malfunction, check the on-site timestamp to determine if the latest recorded time has been used in this field. If not, it must be returned to the factory for replacement. If it has been used, the transducer can be replaced on-site and then calibrated. After replacing the transducer, determine if the new transducer has been calibrated. If so, continue to use this transducer for measurements to determine if the measurements are normal. Compare the coefficient of the channel calculated at the latest measurement time with the coefficient in the record. If the error between the two coefficients is less than the instrument accuracy requirement, the repair is complete.

[0035] Based on the above technical solutions, the present invention provides a calibration method for a multi-channel ultrasonic flow meter after transducer replacement. During normal use, the coefficients of each channel are recorded in real time. When a transducer fails and is replaced, the timestamp of the updated coefficients of each channel is detected. The average flow velocity value calculated by other transducers is used to convert the channel flow velocity with the channel coefficient, and the channel flow velocity is used to correct the measurement delay time, thus realizing automatic calibration after on-site transducer replacement.

[0036] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for calibrating a multi-channel ultrasonic flow meter by replacing the transducer. By using transducers of different channels for mutual calibration, the ultrasonic flow meter can be automatically calibrated on-site under certain conditions without needing to be returned to the factory for recalibration. This ensures the accuracy of the flow meter, avoids the accuracy deviation problem caused by replacing the ultrasonic transducer on-site, and reduces the waste of returning the ultrasonic flow meter to the factory for recalibration.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A calibration method for a multi-channel ultrasonic flow meter after transducer replacement, characterized in that, Includes the following steps: Step S1: For a multi-channel ultrasonic flow meter, measure the downstream and upstream propagation times of the ultrasonic waves in each channel in real time. Step S2: Calculate the flow rate of each channel, the coefficient of each channel, and the average flow rate of the flow meter by running calculation formulas (1), (3), and (2); The formula for calculating the flow rate of each audio channel is as follows: , formula (1); In the formula above, Let be the flow rate of the k-th audio channel; k is a natural number greater than 1 and is a counting marker for the vocal tract; The downstream propagation time of the ultrasound measured in the k-channel; The backflow propagation time of ultrasound was measured for the k-channel. This refers to the measurement error included in the measured ultrasonic wave propagation time; The k-channel flow velocity measurement coefficient determined during factory testing; The average flow velocity of a multi-channel ultrasonic flow meter is calculated based on the number of channels without transducer replacement, as follows: Formula (2); The average flow velocity of the ultrasonic flow meter. A natural number greater than 1, representing the counting markers for the vocal tracts; This represents the total number of audio channels; The k-channel weighting coefficient is determined during factory testing. Let be the flow rate of the k-th audio channel; The formulas for calculating the channel coefficients of each channel are as follows: Formula (3); The channel coefficients for the k-channel; ； Let k be the flow rates of the audio channels; The average flow velocity of the flow meter; Step S3: Determine whether each channel is working properly through a preset judgment operation; If all channels are working properly, proceed to step S4; if there is a malfunctioning channel in the flow meter, proceed to step S5. Step S4: Record the flow velocity of each channel, the coefficient of each channel, and the average flow velocity of the flow meter obtained in step S2 into a channel coefficient record table, and simultaneously enter the corresponding timestamp of the data. The channel coefficient recording table records the recording timestamp of the average flow rate of each flow meter and the correspondence between the average flow rate and the channel coefficient of each channel at the recording time. Step S5: Continue to determine whether a new transducer has been replaced; If a certain channel has been replaced with a new transducer, the average flow rate of the current flow meter is obtained by running formula (2), and the record timestamp corresponding to the average flow rate of the current flow meter is obtained from the channel coefficient record table in step S4. Then, it is checked whether the record timestamp corresponding to the average flow rate of the current flow meter is after the application time in this field. If the timestamp of the average flow rate record of the current flow meter is after the on-site application time, the average flow rate of the flow meter is calculated according to formula (2) by all the remaining channels of the multi-channel ultrasonic flow meter after removing the replaced channels, and the calculation result is defined as the average flow rate of the remaining channels. Then, step S6 is executed. Step S6: Based on the average flow rate of the remaining channels, obtain the channel coefficient corresponding to the channel with the new transducer from the channel coefficient record table. Then, based on the channel coefficient corresponding to the channel with the new transducer, the average flow rate of the remaining channels, and formula (4), calculate the flow rate of the channel with the new transducer in reverse. Then continue to execute step S7. The formula for calculating the reverse flow velocity of the vocal tract is as follows: , formula (4); The channel velocity of the newly replaced k-channel, to be calculated in reverse; The average flow velocity measured in real time by the flow meter; The channel coefficients for the k-channel; Step S7: Calculate the delay time of the channel with the new transducer replaced by running the calculation formula (5); For a channel whose transducer has been replaced, the reverse calculation of its channel delay is performed using the following formula: , formula (5); In formula (5), The channel delay error time for the newly replaced k-channel; The chord length of the channel for which the new transducer has been installed; The chord length of any channel whose transducer has not been replaced; The measured time for the downstream current of any randomly selected channel without the transducer being replaced; The delay time for any channel whose transducer has not been replaced; The flow rate of any channel whose transducer has not been replaced; The actual downstream measurement time for the newly replaced k-channel audio; The newly replaced channel velocity of the k-channel is calculated in reverse. The angle between the sound channel and the central axis of the flow meter.

2. The calibration method for a multi-channel ultrasonic flow meter after transducer replacement as described in claim 1, characterized in that, In step S3, the preset judgment operation specifically includes the following steps: Step S31: For each channel in the flow meter, collect the real-time signal strength and real-time signal-to-noise ratio of each channel in real time; Step S32: Compare the real-time signal strength and real-time signal-to-noise ratio of each channel with the normal signal strength amplitude and preset normal signal-to-noise ratio of that channel, respectively. When the real-time signal strength of a certain channel is less than the normal signal strength amplitude of the channel, and / or when the real-time signal-to-noise ratio of a certain channel is lower than the preset normal signal-to-noise ratio of the channel, it is determined that the channel is malfunctioning, and thus it is determined that there is a malfunctioning channel in the flow meter. When the real-time signal strength of all channels is greater than or equal to the normal signal strength amplitude of the channels, and the real-time signal-to-noise ratio of all channels is greater than or equal to the preset normal signal-to-noise ratio of the channels, all channels are considered to be working normally.

3. The calibration method for a multi-channel ultrasonic flow meter after transducer replacement as described in claim 1 or 2, characterized in that, A multi-channel ultrasonic flow meter is a four-channel ultrasonic flow meter, which includes four channels. The channels are arranged in parallel, and the angle between each channel and the central axis of the flow meter is 45°.

4. The calibration method for a multi-channel ultrasonic flow meter after transducer replacement as described in claim 3, characterized in that, The ultrasonic flow meter tube body (1000) has four preset openings on each side; Four ultrasonic transducers (101) are sealed and installed in four pre-set openings on one side. Four ultrasonic receiving transducers (102) are sealed and installed in four pre-set openings on the other side. Four ultrasonic transmitting transducers (101) are symmetrically distributed with four ultrasonic receiving transducers (102). An ultrasonic transmitting transducer (101) is used to transmit ultrasonic signals to an ultrasonic receiving transducer (102). An ultrasonic receiving transducer (102) is used to receive ultrasonic signals emitted by an ultrasonic transmitting transducer (101).

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