CN115900896A - Parameter calibration and verification test method for time difference method ultrasonic flowmeter - Google Patents

Abstract

The invention provides a parameter calibration and verification test method of an ultrasonic flowmeter by a time difference method, which relates to the technical field of nuclear power instruments, and is used for measuring a sound channel of the ultrasonic flowmeter to obtain the length of the sound channel; measuring the zero flow time difference offset of each sound channel in a non-flowing static water state; calculating the non-fluid delay time of each sound channel according to the propagation time of the sound wave which is sent once and received twice; developing a calibration test and determining the meter coefficient of the ultrasonic flowmeter to complete parameter calibration of the ultrasonic flowmeter; the method completes accurate and efficient parameter setting of the ultrasonic flowmeter through a measurement test of the sound channel length, zero flow time difference offset, non-fluid delay time and a calibration test of the instrument coefficient, obtains the percentage reading deviation through a probe replacement test and a turbulence test, and is used for supporting the uncertainty analysis of the instrument coefficient; necessary test data are provided for parameter configuration and meter coefficient uncertainty calculation of the high-precision time difference method ultrasonic flowmeter.

Description

Parameter calibration and verification test method of a time-difference method ultrasonic flowmeter

technical field

The invention belongs to the technical field of nuclear power instruments, and in particular relates to a parameter calibration and verification test method of a time-difference method ultrasonic flowmeter.

Background technique

The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

The use of ultrasonic flowmeters in nuclear power plants/nuclear power plants can obtain flow measurement results with higher accuracy than traditional flow measurement methods such as orifice plates/venturis, and has broad applications in the measurement of main feedwater flow and primary circuit coolant flow. application prospects.

At the same time, the calculation formula of the transit-time ultrasonic flowmeter is more complex than the traditional measurement method: parameter configuration values such as instrument coefficient, sound channel length, and zero offset need to be determined through various tests.

The operating temperature of the ultrasonic flowmeter may be high, and it is also faced with the replacement of the probe during the service life. It is impossible to directly determine or prove the measurement of the ultrasonic flowmeter only based on the bench calibration test at room temperature (there is no general extrapolation algorithm). Accuracy also needs to be supported by multiple experiments to estimate the uncertainty of measurement of the meter coefficient.

Therefore, how to accurately and efficiently calibrate the parameters of transit-time ultrasonic flowmeters used in nuclear power plants/nuclear power plants; how to plan tests to support the analysis of instrument coefficient uncertainty has become an urgent problem to be solved.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a parameter calibration and verification test method of the time difference method ultrasonic flowmeter, through the measurement test of the sound channel length, the zero flow time difference offset, the non-fluid delay time and the instrument The calibration test of the coefficient completes the accurate and efficient parameter setting of the ultrasonic flowmeter. Through the probe replacement test and the disturbance test, the percentage reading deviation is obtained, which is used to support the uncertainty analysis of the instrument coefficient; through six tests, it is a high-precision time difference method The parameter configuration and meter coefficient uncertainty calculation of the ultrasonic flowmeter provide the necessary test data.

In order to achieve the above purpose, one or more embodiments of the present invention provide the following technical solutions:

The first aspect of the present invention provides a method for calibrating parameters of a transit-time ultrasonic flowmeter;

A method for calibrating the parameters of ultrasonic flowmeters by transit time difference method, which is used for calibrating the parameters of each ultrasonic flowmeter before leaving the factory, including:

Measure the sound channel of the ultrasonic flowmeter to obtain the sound channel length of the ultrasonic flowmeter;

In the state of still water with no flow, measure the zero-flow time difference offset of each channel;

Calculate the non-fluid delay time of each channel according to the propagation time of the sound wave once sent twice;

Carry out the calibration test and determine the instrument coefficient of the ultrasonic flowmeter, and complete the parameter calibration of the ultrasonic flowmeter.

Further, the specific way to obtain the channel length is:

Keep the pipe section of the ultrasonic flowmeter filled with water, determine the transmission speed C of the sound wave in water according to the temperature T and pressure P during the test, and determine the transmission speed C of the sound wave in the water according to the flight time tw of the sound wave measured by each pair of probes, determine each sound channel The length of L=C*tw.

Further, the specific way of obtaining the length of the vocal tract also includes: using a micrometer or a laser rangefinder to directly measure.

Further, the measurement method of the zero flow time difference offset is:

For each channel, the time-of-flight difference in the fluid within a certain period of time is recorded at intervals, which is used as a set value for calculating the zero-flow time difference offset of the channel.

Further, the static water state without flow is a state in which the ultrasonic flowmeter is placed statically or installed on a calibration bench (the bench test valve is closed), and the pipeline of the ultrasonic flowmeter is filled with water and the flow rate is zero.

Further, the calculation method of the non-fluid delay time is:

Carry out experiments in still water, use probe A to send sound wave 1 to probe B, and measure the total time on side B. When the sound wave is received for the first time, its propagation time is:

t1=L/c+τ

This time, the sound wave energy will be reflected at the interface between the B side transducer and the fluid, and the reflected sound wave 2 will return to the A side transducer for reflection again, and the reflected sound wave 3 will finally reach the B transducer and be absorbed by the B transducer. It is captured that the sound wave propagation time at this time is:

t3=3L/c+τ

Then the non-fluid delay time τ=(3t1-t3)/2 can be obtained by combining the above two formulas.

The second aspect of the present invention provides a verification test method for the transit-time ultrasonic flowmeter.

A verification test method for transit-time ultrasonic flowmeters,

The ultrasonic flowmeters in the research and development stage are verified on the calibration bench in turn, and the percentage reading deviation is obtained, which is used to support the post-analysis of the uncertainty of the meter coefficient. The specific steps include:

(1) Carry out the probe replacement test of the ultrasonic flowmeter, and calculate the percentage reading deviation after the probe is replaced;

(2) Use the parameter calibration method of a time difference method ultrasonic flowmeter provided in the first aspect to perform parameter calibration on the ultrasonic flowmeter;

(3) Carry out the turbulence test, and record the percentage reading deviation in the turbulence test.

Further, the formula of the percentage reading deviation is:

Percent reading deviation = 100% × (flow reading of the flow meter - flow reading of the calibration bench) / flow reading of the flow meter.

Further, the probe replacement test, the specific steps are:

Keep the position of the ultrasonic flowmeter on the calibration bench unchanged, and replace all probes;

Carry out zero-flow time difference offset, non-fluid delay time measurement test and instrument coefficient calibration test for the ultrasonic flowmeter with replaced probe;

Using the calibration bench, calculate the percent reading deviation after probe replacement.

Further, the turbulence test is based on the calibration test, adding a turbulence element upstream of the ultrasonic flowmeter, and trying different installation angles of the turbulence element for the non-centrosymmetric turbulence element; on the basis of the straight pipe arrangement, Add elbow spoiler upstream of meter.

The above one or more technical solutions have the following beneficial effects:

The parameter calibration method of the transit-time ultrasonic flowmeter of the present invention realizes the accurate and accurate calibration of the transit-time ultrasonic flowmeter through the measurement and research of the sound channel length, the zero-flow time-difference offset and the non-fluid delay time and the calibration test of the instrument coefficient. Efficient parameter calibration; through the probe replacement test and the turbulence test, the percentage reading deviation is obtained to support the uncertainty analysis of the instrument coefficient; through the six tests of the present invention, the transit time ultrasonic flowmeter that needs test data support can be determined Configure the parameters, collect various test inputs required for the calculation of the uncertainty of the instrument coefficient of the ultrasonic flowmeter, and provide the necessary test data for the parameter configuration of the high-precision time-of-flight ultrasonic flowmeter and the calculation of the uncertainty of the instrument coefficient.

Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Fig. 1 is a flow chart of the parameter calibration method of the first embodiment.

Fig. 2 is the basic principle diagram of the time-of-flight method ultrasonic flow.

Figure 3 is a flowchart of probe replacement.

Fig. 4 is a schematic diagram of non-fluid delay time solution.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment one

This embodiment discloses a method for calibrating parameters of a transit-time ultrasonic flowmeter;

As shown in Figure 1, a parameter calibration method for a transit-time ultrasonic flowmeter includes:

Step S101: measure the sound channel of the ultrasonic flowmeter to obtain the sound channel length of the ultrasonic flowmeter;

The definition of the length of the sound channel can refer to L in Figure 2 (the basic principle diagram of the time-difference method of ultrasonic flow); due to the existence of processing errors, the actual processing position of a pair of ultrasonic probes A and B on one sound channel may deviate from the design value , which in turn leads to a deviation between the length L of the sound channel and the design value; therefore, after the measurement pipe section (as shown in Figure 2 as a whole is the measurement pipe section) is processed, the measurement sound channel needs to be measured first.

The direct measurement method can be selected for the vocal tract length measurement test. This method requires the necessary operating space, and will use a micrometer or a laser rangefinder to measure distances. However, it is difficult to ensure sufficient operating space in the actual environment, so this embodiment chooses to pass Indirect way to determine the length of the sound channel: keep the pipe section filled with water, determine the transmission speed C of the sound wave in water according to the temperature T and pressure P during the test, and determine the sound wave transmission speed C in water according to the flight time tw of the sound wave measured by each pair of probes. The length of a channel L=C*tw; the measurement of flight time can be carried out on the calibration bench.

Step S102: Measure the zero-flow time difference offset of each sound channel in the state of still water without flow;

For the time-difference ultrasonic flowmeter, the key input when calculating the acoustic channel flow velocity is the flight time difference Δt between the "downstream" and "countercurrent" sound waves in the fluid; when the fluid in the pipeline is still (the flow rate is 0), the theoretical value of the time difference is 0. For the deviation of the actual value relative to the theoretical value, it can be corrected by configuring the zero flow time difference offset t0 coefficient for each channel; during the working process of the instrument, the flight time difference in the fluid used in the flow calculation formula is the measured value of Δt Subtract t0.

For zero-flow time-difference measurement, the state of "still water" without flow should be selected; for each sound channel, the time-of-flight in the fluid within a certain period of time is recorded at intervals, as the input for calculating the instrument parameter t0 of the "zero-flow time difference" of the sound channel ; Usually, the flowmeter pipe section can be placed statically or installed on the test bench (the bench test valve is closed), and the ultrasonic flowmeter pipe is filled with water and the flow rate is zero.

Step S103: Calculate the non-fluid delay time of each channel according to the propagation time of the sound wave once sent and received twice;

The purpose of the ultrasonic probe is to measure the flight time difference Δt between the "downstream" and "countercurrent" sound waves in the fluid; but the sound wave is transmitted from the probe A to the probe B in Figure 2, there is inevitably a non-fluid delay time τ, each sound channel The non-fluid delay time of the time τ can be determined by the method shown in Figure 4.

In this embodiment, experiments are carried out in still water. Probe A is used to send sound wave 1 to probe B, and side B measures the total time. When the sound wave is received for the first time, its propagation time is:

t ₁ =L/c+τ

The acoustic wave energy will be reflected at the interface between the B-side transducer and the fluid, and the reflected sound wave energy 2 will return to the A-side transducer for reflection again, and the reflected energy 3 will eventually reach the B-side transducer and be absorbed by the B-side transducer. Captured by the side transducer, the sound wave propagation time at this time is:

t ₃ =3L/c+τ

Then, by combining the above two formulas, τ=(3t1-t3)/2 can be obtained.

Step S104: Carry out a calibration test and determine the instrument coefficient of the ultrasonic flowmeter, and complete the parameter calibration of the ultrasonic flowmeter.

After completing the parameter configuration of ultrasonic flowmeter sound channel length L, zero flow time difference offset t0 and non-fluid delay time τ, carry out calibration test to determine the instrument coefficient IF, the flowmeter coefficient is the actual flow verification of the flowmeter, and The coefficient for correcting the indication value of the flowmeter according to the result, and its value is the ratio of the indication value of the standard device to the indication value of the flowmeter.

The instrument factor IF is a parameter point, or a parameter broken line that changes with the flow rate or Reynolds number; according to the definition, the calculation formula of IF under a certain working condition is:

Meter factor IF = calibration bench (standard device) flow reading / flow meter flow reading

In order to reduce the influence of the fluid working conditions on the uncertainty of the instrument coefficient, the pipeline layout of the calibration bench should simulate the actual working conditions of the ultrasonic flowmeter as much as possible, and configure the upstream straight pipe section length, elbow and other disturbances that are as consistent as possible with the flowmeter application conditions. The test flow point and the number of tests for each flow point can be determined by referring to the requirements of relevant testing standards and following the specific flowmeter technical requirements.

Embodiment two

This embodiment discloses a verification test method for a transit-time ultrasonic flowmeter;

A verification test method for time-of-flight ultrasonic flowmeters. The ultrasonic flowmeters in the research and development stage are sequentially carried out on the calibration bench to obtain the percentage reading deviation, which is used to support the post-analysis of the uncertainty of the instrument coefficient. The specific steps include: :

1. Carry out the probe replacement test of the ultrasonic flowmeter, and calculate the percentage reading deviation after the probe is replaced;

Probes A and B in Figure 2 are installed in the pipe section of the ultrasonic flowmeter. The probe itself does not bear the fluid pressure in the pipe, so the probe can be replaced online; the life of the flowmeter pipe section is long, while the life of the probe is relatively short. During the service life of the meter, it is necessary to quantitatively evaluate the impact of the probe replacement on the uncertainty of the meter coefficient.

The main flow of the probe replacement test in which all probes are replaced N times is shown in Figure 3:

Step (1) Execute the i-th reading deviation measurement: where 0<i<N+1, select one or more flow points on the calibration bench for calibration test, for the flow bench of standard container method or weighing method , perform more than or equal to 20 flow tests at each flow point; for the standard meter flow bench, the duration of the flow test can be extended as much as possible; compare the meter readings with the bench readings, and record the i-th percentage reading deviation;

Step (2) judge the size of i and N, if i is greater than or equal to N, then the probe replacement test ends; if i is less than N, then i=i+1, go to step (3);

Step (3) Execute the i-th probe replacement: keep the instrument pipe section at the same position on the bench, replace all probes, and ensure that the probes in all probe installation positions are different from the previous test; in order to obtain as many data samples as possible, test The number of prepared probes may be greater than the number of probes configured on the pipe section;

Step (4): After the probe is replaced, parameters such as time difference offset t0 and non-fluid delay time t will be affected. Therefore, for ultrasonic flowmeters that can provide parameter adjustment functions after leaving the factory and whose application conditions meet the test conditions, After completing the (3) step probe replacement operation, the method provided in Embodiment 1 can be used to carry out the measurement test of zero flow time difference offset and non-fluid delay time, and complete the parameter reset after the probe replacement test; go to step (1 ), to measure the reading deviation.

2. Using the parameter calibration method of the transit-time ultrasonic flowmeter provided in Embodiment 1 to calibrate the parameters of the ultrasonic flowmeter.

3. Carry out the disturbance test and record the percentage reading deviation in the disturbance test.

The rated operating temperature of ultrasonic flowmeters used in nuclear power plants/nuclear power plants may be relatively high. For example, the application of main water supply is generally above 200°C. Calculation method) to directly determine or prove the measurement accuracy of the ultrasonic flowmeter; the piping layout of the calibration test cannot be completely consistent with the piping layout of the field application; therefore, it is necessary to produce more types and more complex flow fields through the turbulence test , to support the estimation of measurement uncertainty.

The flow turbulence conditions include: on the basis of the calibration test, add a turbulence element (such as an eccentric orifice) upstream, and try different installation angles of the turbulence element for the non-centrosymmetric turbulence element; it can also be arranged in a straight pipe On the basis, add elbows and other spoilers upstream of the instrument.

In addition, a verification test is also required. The working conditions of the verification test are the same as the calibration conditions. Generally, flow points that are different from the calibration test are selected to verify the calibration effect.

For each verification test condition and disturbance test condition, the selection of the test flow point and the number of tests for each flow point can refer to the requirements of the relevant testing standards and be determined in accordance with the specific flowmeter technical requirements; each test needs to be determined according to the meter Readings and bench readings, record the percentage reading deviation of each test.

Among them, the calculation formula of the percentage reading deviation after the test is:

Percentage reading deviation = 100% x (flow reading of the flowmeter - flow reading of the calibration bench) / flow reading of the flowmeter

Comprehensive calibration test, probe replacement test and turbulence test data can be used to quantitatively evaluate the influence of instrument coefficient uncertainty.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A parameter calibration method of a time-difference method ultrasonic flowmeter, is characterized in that, is used for the parameter calibration of each ultrasonic flowmeter before leaving the factory, comprises: Measure the sound channel of the ultrasonic flowmeter to obtain the sound channel length of the ultrasonic flowmeter; In the state of still water with no flow, measure the zero-flow time difference offset of each channel; Calculate the non-fluid delay time of each channel according to the propagation time of the sound wave once sent twice; Carry out the calibration test and determine the instrument coefficient of the ultrasonic flowmeter, and complete the parameter calibration of the ultrasonic flowmeter. 2. the parameter calibration method of a kind of time-difference method ultrasonic flowmeter as claimed in claim 1, is characterized in that, the concrete way that obtains described sound channel length is: Keep the pipe section of the ultrasonic flowmeter filled with water, determine the transmission speed C of the sound wave in water according to the temperature T and pressure P during the test, and determine the transmission speed C of the sound wave in the water according to the flight time tw of the sound wave measured by each pair of probes, determine each sound channel The length of L=C*tw. 3. The method for calibrating parameters of a time-of-flight ultrasonic flowmeter according to claim 1, wherein the specific method of obtaining the length of the sound channel further comprises: using a micrometer or a laser range finder to perform direct measurement. 4. the parameter calibration method of a kind of transit-time method ultrasonic flowmeter as claimed in claim 1, is characterized in that, the measuring method of described zero flow time-difference offset is: For each channel, the time-of-flight difference in the fluid within a certain period of time is recorded at intervals, which is used as a set value for calculating the zero-flow time difference offset of the channel. 5. The parameter calibration method of a time-difference method ultrasonic flowmeter as claimed in claim 1, characterized in that, the static water state without flow is that the ultrasonic flowmeter is statically placed or installed on a calibration stand and the stand test The valve is closed, the pipeline of the ultrasonic flowmeter is filled with water and the flow rate is zero. 6. the parameter calibration method of a kind of time-difference method ultrasonic flowmeter as claimed in claim 1, is characterized in that, the calculation mode of described non-fluid delay time is: Carry out experiments in still water, use probe A to send sound wave 1 to probe B, and measure the total time on side B. When the sound wave is received for the first time, its propagation time is: t1=L/c+τ This time, the sound wave energy will be reflected at the interface between the B side transducer and the fluid, and the reflected sound wave 2 will return to the A side transducer for reflection again, and the reflected sound wave 3 will finally reach the B transducer and be absorbed by the B transducer. It is captured that the sound wave propagation time at this time is: t3=3L/c+τ Then the non-fluid delay time τ=(3t1-t3)/2 can be obtained by combining the above two formulas. 7. A verification test method for a transit-time ultrasonic flowmeter, characterized in that, The ultrasonic flowmeters in the research and development stage are verified on the calibration bench in turn, and the percentage reading deviation is obtained, which is used to support the post-analysis of the uncertainty of the meter coefficient. The specific steps include: (1) Carry out the probe replacement test of the ultrasonic flowmeter, and calculate the percentage reading deviation after the probe is replaced; (2) use the parameter calibration method of a kind of transit-time method ultrasonic flowmeter as described in any one of claim 1-6 to carry out parameter calibration to ultrasonic flowmeter; (3) Carry out the turbulence test, and record the percentage reading deviation in the turbulence test. 8. the verification test method of a kind of time-difference method ultrasonic flowmeter as claimed in claim 7, is characterized in that, the formula of described percentage reading deviation is: Percent reading deviation = 100% × (flow reading of the flow meter - flow reading of the calibration bench) / flow reading of the flow meter. 9. the verification test method of a kind of time-difference method ultrasonic flowmeter as claimed in claim 7, is characterized in that, described probe replacement test, concrete steps are: Keep the position of the ultrasonic flowmeter on the calibration bench unchanged, and replace all probes; Carry out zero-flow time difference offset, non-fluid delay time measurement test and instrument coefficient calibration test for the ultrasonic flowmeter with replaced probe; Using the calibration bench, calculate the percent reading deviation after probe replacement. 10. The verification test method of a time-difference method ultrasonic flowmeter as claimed in claim 7, wherein the turbulence test is based on a calibration test, and a turbulence member is added upstream, for non-centrosymmetric Spoiler Try different spoiler installation angles; on the basis of straight pipe arrangement, add elbow spoiler upstream of the instrument.

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