Method and instrument for measuring flow of fluid in pipeline

Abstract

The invention relates to the field of flow measurement of fluid in a pipeline, in particular to a method and instrument for measuring the flow of the fluid in the pipeline, and the method comprises the following steps: measuring liquid level data of the fluid in the pipeline based on a liquid level sensor; measuring flow velocity data of fluid in the pipeline based on the transducer; obtaining cross-sectional area data of the fluid in the pipeline based on the liquid level data of the fluid; and obtaining instantaneous flow data of the fluid based on the cross-sectional area data and the flow velocity data of the fluid. According to the invention, the cross-sectional area data of the fluid is calculated based on the actual liquid level data of the fluid measured by the liquid level sensor, and the flow of the fluid in the pipeline is calculated based on the cross-sectional area data and the flow velocity data measured by the transducer; compared with the traditional fluid flow calculated by directly defaulting that the fluid in the pipeline is in a full pipe state, the accuracy of the measured fluid flow is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of flow measurement of fluid in a pipeline, and in particular to a method and an instrument for measuring the flow of fluid in a pipeline. Background Art

[0002] At present, conventional velocity flow meters or heat meters on the market all belong to full-pipe measurement, that is, when calculating the flow rate of the fluid in the pipeline, they usually do not judge whether the fluid in the pipeline is in a full-pipe state, and assume that the fluid in the pipeline is in a full-pipe state. After measuring the flow rate of the fluid in the pipeline, the flow rate of the fluid in the pipeline is calculated according to the state of the fluid in the full pipe. Because the pipeline is generally more complex in actual application and the installation conditions are changeable, and the pipeline in the system is sometimes in an intermittent operation state or there is gas in the pipeline, this will cause the fluid in the pipeline to be in a state of not being full during the flow process. The traditional method of calculating the flow rate of the fluid by full pipe will cause the calculated fluid flow to have a large measurement error.

[0003] In order to solve the problem of the pipeline being not full, the conventional treatment method is to install an exhaust valve on the pipeline and exhaust the gas from the pipeline regularly or at a constant pressure. In fact, whether it is regular exhaust or constant pressure exhaust, a certain amount of gas will accumulate in the pipeline before it is discharged. It does not trigger the exhaust of gas in real time. Therefore, the above method can only alleviate the problem of large measurement errors temporarily, and it cannot completely solve the problem of the fluid in the pipeline being not full. Based on this, the inventor has developed a method and instrument that can more accurately measure the flow rate of fluid in a pipeline. Summary of the invention

[0004] In order to improve the accuracy of measuring the flow rate of a fluid in a pipeline, the present invention provides a method and an instrument for measuring the flow rate of a fluid in a pipeline, which calculates the cross-sectional area data of the fluid based on the actual fluid level data measured by a liquid level sensor, and calculates the flow rate of the fluid in the pipeline based on the cross-sectional area data and the flow velocity data measured by a transducer. Compared with the traditional method of directly calculating the fluid flow rate by assuming that the fluid in the pipeline is in a full pipe state, the accuracy of the measured fluid flow rate is greatly improved.

[0005] In a first aspect, the present invention provides a method for measuring the flow rate of a fluid in a pipeline, which adopts the following technical solution:

[0006] A method for measuring the flow rate of a fluid in a pipeline comprises the following steps:

[0007] Measuring the liquid level data of the fluid in the pipeline based on the liquid level sensor;

[0008] Measuring the flow velocity data of the fluid in the pipeline based on the transducer;

[0009] Obtaining cross-sectional area data of the fluid in the pipeline based on the liquid level data of the fluid;

[0010] The instantaneous flow data of the fluid is obtained based on the cross-sectional area data and flow velocity data of the fluid.

[0011] Preferably, the total volume flow data of the fluid is obtained based on the instantaneous flow data of the fluid.

[0012] Preferably, the flow velocity data of the fluid in the pipeline is measured by an ultrasonic time difference method or a Karman vortex street principle to measure the average flow velocity of the fluid in the pipeline.

[0013] Preferably, obtaining cross-sectional area data of the fluid in the pipeline based on the liquid level data of the fluid includes:

[0014] The installation inclination angle of the liquid level sensor during installation is obtained, and the cross-sectional area data of the fluid is obtained based on the installation inclination angle and the liquid level data measured by the liquid level sensor.

[0015] In a second aspect, the present invention provides an instrument for measuring the flow rate of a fluid in a pipeline, which adopts the following technical solution:

[0016] A meter for measuring the flow rate of a fluid in a pipeline, comprising:

[0017] The instrument body is installed coaxially with the pipeline, and the inner diameter of the instrument body is equal to the inner diameter of the pipeline;

[0018] The liquid level sensor is arranged on the instrument body and is used to measure the liquid level data of the fluid in the instrument body;

[0019] The transducer is arranged on the instrument body and is used to measure the flow velocity data of the fluid in the instrument body;

[0020] A cross-sectional area calculation module, used for calculating cross-sectional area data of the fluid based on the liquid level data of the fluid;

[0021] The instantaneous flow calculation module is used to calculate the instantaneous flow data based on the cross-sectional area data and flow velocity data of the fluid.

[0022] Preferably, the instrument further comprises:

[0023] The total volume flow calculation module is used to calculate the total volume flow data of the fluid based on the instantaneous flow data of the fluid.

[0024] In summary, the present invention includes the following beneficial technical effects:

[0025] 1. The present invention calculates the cross-sectional area data of the fluid based on the actual fluid level data measured by the liquid level sensor, and calculates the flow rate of the fluid in the pipeline based on the cross-sectional area data and the flow velocity data measured by the transducer. Compared with the traditional method of directly calculating the fluid flow rate by assuming that the fluid in the pipeline is in a full pipe state, the accuracy of the measured fluid flow rate is greatly improved.

[0026] 2. The present invention obtains the installation inclination angle of the pipeline and the liquid level sensor when the pipeline is installed, and calculates the real cross-sectional area data of the fluid in the pipeline based on the installation inclination angle, and then calculates the instantaneous flow data of the fluid in the pipeline based on the real cross-sectional area data and the flow velocity data of the fluid. The installation inclination angle of the liquid level sensor is taken into account when calculating the cross-sectional area data, thereby further improving the accuracy of the calculated instantaneous flow data of the fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of a method in an embodiment of the present invention.

[0028] Figure 2 It is a schematic diagram of Example 1 in the method in an embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of Example 2 in the method in an embodiment of the present invention.

[0030] Figure 4 It is a schematic diagram for calculating the cross-sectional area data of the fluid liquid level height of Example 2 in the method in an embodiment of the present invention that is higher than (including a solution where the liquid level height is the same as the axis) the pipeline axis and a schematic diagram for calculating the cross-sectional area data of the fluid liquid level height that is lower than (including a solution where the liquid level height is the same as the axis) the pipeline axis (wherein the installation inclination angle of the liquid level sensor is 0).

[0031] Figure 5 It is a schematic diagram for calculating the cross-sectional area data of the fluid liquid level height of Example 2 in the method in an embodiment of the present invention when it is higher than (including a solution where the liquid level height is the same as the axis) the pipeline axis and a schematic diagram for calculating the cross-sectional area data of the fluid liquid level height when it is lower than (including a solution where the liquid level height is the same as the axis) the pipeline axis (wherein the installation inclination angle of the liquid level sensor is X).

[0032] Figure 6 It is a schematic diagram of the principle of a method for calculating the total volume flow rate of a fluid in an embodiment of the present invention.

[0033] Figure 7 It is the instrument in Example 1 in the embodiment of the present invention.

[0034] Figure 8 It is the instrument in Example 2 of the embodiment of the present invention.

[0035] Explanation of the accompanying reference numerals: 1. Instrument body; 2. Liquid level sensor; 3. Transducer; 4. Vortex sound generator. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0037] An embodiment of the invention discloses a method for measuring the flow rate of a fluid in a pipeline.

[0038] Specifically, refer to Figure 1 , the method comprises the following steps:

[0039] S1. Measuring the liquid level data of the fluid in the pipeline based on the liquid level sensor.

[0040] Specifically, a liquid level sensor disposed on the meter body is used to measure the liquid level of the fluid in the pipeline and record it as liquid level data, wherein the meter body and the pipeline are installed coaxially, and the coaxiality error between the meter body and the pipeline after installation is negligible, specifically, both ends of the meter body are installed on the pipeline through flanges, and the inner diameter of the meter body is the same as the inner diameter of the pipeline.

[0041] When the liquid level sensor measures that the liquid level in the instrument body is low, the liquid level sensor issues an alarm; specifically, when the liquid level sensor detects that the liquid level in the instrument body is lower than the radius of the pipeline when the fluid is full, that is, when the liquid level in the instrument body is lower than half of the inner diameter of the pipeline, the liquid level sensor issues an alarm.

[0042] In order to better demonstrate how the liquid level sensor measures the liquid level of the fluid in the instrument body, this embodiment provides two measurement methods, namely Example 1 and Example 2.

[0043] Example 1: Take the water immersion sensor as an example;

[0044] like Figure 2 As shown, multiple water immersion sensors are installed on the instrument body; when the liquid level of the fluid in the instrument body is lower than the detection position of the lowest water immersion sensor, the water immersion sensor detects no data on the liquid level of the fluid, and the transducer at this time issues a fault alarm to remind the staff that the liquid level of the fluid in the instrument body is low.

[0045] When the liquid level of the fluid in the meter body at least submerges the water immersion sensor at the lowest position, the water immersion sensor measures the liquid level of the fluid in the meter body.

[0046] by Figure 2For example, assuming that 5 water immersion sensors are installed on the instrument body, when the fluid in the instrument body submerges the water immersion sensor at a but does not submerge the water immersion sensor at b, the 5 water immersion sensors use the liquid level of the fluid at a as the measured fluid level data; if it submerges b but does not submerge c, the liquid level height at b is used as the measured fluid level data; the above is only an example.

[0047] In actual use, the liquid level of the water immersion sensor at the highest point that the fluid can submerge is used as the liquid level data;

[0048] Example 2, refer to Figure 3 As shown, it is assumed that the liquid level sensor is arranged in the instrument body along the vertical direction, and the liquid level sensor can measure the liquid level height of the fluid in the instrument body in real time and record it as liquid level data.

[0049] When the liquid level of the fluid in the meter body is lower than the position of the transducer, the transducer at this time issues a fault alarm to remind the staff that the liquid level of the fluid in the meter body is low.

[0050] S2, measuring the flow velocity data of the fluid in the pipeline based on the transducer;

[0051] Specifically, the flow velocity of the fluid in the meter body is measured by using a transducer disposed on the meter body, and recorded as flow velocity data;

[0052] The transducer can measure the average flow velocity of the fluid in the instrument body by ultrasonic time difference method or Karman vortex street principle, and record the average flow velocity as the flow velocity data v of the fluid;

[0053] When the liquid level of the fluid in the instrument body is lower than the installation position of the transducer, the transducer will issue a fault alarm, where the transducer is installed on both sides of the middle position of the instrument body;

[0054] S3, obtaining cross-sectional area data of the fluid in the pipeline based on the liquid level data of the fluid;

[0055] For Example 1, refer to Figure 2 , the calculation method of its cross-sectional area data is:

[0056] S31. When the meter body is installed, the meter body is likely to have a certain tilt angle, or the five water immersion sensors are installed at a certain tilt angle, where the fluid submerges the liquid level sensor at a but does not submerge the liquid level sensor at b as an example;

[0057] The installation inclination angle of the liquid level sensor at c, which is the highest among the five, is β, that is, the installation inclination angle of the instrument body is β, that is, the angle between the liquid level sensor at c and the vertical plane is recorded as β, the angle between the water immersion sensor at a and the transducer is α, and the angle between the liquid level sensor at a and the horizontal plane is γ.

[0058] When the installation inclination angle of the five liquid level sensors is 0, β is 0.

[0059] Based on the above measured β, α and γ, it can be concluded that the angle γ = α-β;

[0060] The angle α can be preset when the instrument body is installed, and it is a preset value, while β is the actual tilt angle when the instrument body is installed, which can also be easily measured. When installing the instrument body and the pipeline, it is usually necessary to align the flange on the instrument body and the flange on the pipeline, which enables the installer to know the actual tilt angle β after the instrument body is installed. Therefore, the actual tilt angle β can also be preset after the installation is completed. Therefore, the angle γ can be easily calculated;

[0061] When calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangle area S2, that is, the calculation formula for the cross-sectional area data is:

[0062] S=S1+S2=πR2×(π+2γ)÷(2π)+R2×sinγ×cosγ=πR2×(π

[0063] +2(α-β))÷(2π)+R2×sin(α-β)×cos(α-β).

[0064] Among them, R is the radius of the fluid in the instrument body, which is 1 / 2 of the inner diameter D of the instrument body. If the inner diameter D of the instrument body is used for calculation, the calculation formula for the cross-sectional area data is:

[0065] S=S1+S2=π(D / 2)2×(π+2γ)÷(2π)+(D / 2)2×sinγ×cos

[0066] γ=π(D / 2)2×(π+2(α-β))÷(2π)+(D / 2)2×sin(α-β)×cos(α-β).

[0067] For example 2;

[0068] S32. Assume that the liquid level sensor is installed in the instrument body along the vertical direction;

[0069] S321, reference Figure 4, when the fluid level is higher than the transducer; where, assuming that the fluid level data is h, the radius of the fluid in the instrument body is r, that is, the fluid radius r is 1 / 2 of the inner diameter d of the instrument body;

[0070] Similarly, when calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangular area S2, such as Figure 4 As shown, assuming that the angle between the line connecting the edge of the water surface of the fluid and the axis of the instrument body and the vertical direction is A, then cosA = (hr) / r;

[0071] If the calculation is based on the fluid radius r, the calculation formula for the cross-sectional area data is:

[0072]

[0073] If the inner diameter d of the instrument body is used for calculation, the calculation formula for the cross-sectional area data is:

[0074]

[0075] S322, reference Figure 4 , when the liquid level of the fluid is lower than the transducer, the transducer will issue a fault alarm;

[0076] And assume that the fluid level data is H, and the radius of the fluid in the instrument body is R, that is, the fluid radius R is 1 / 2 of the inner diameter D of the instrument body;

[0077] When calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangular area S2, such as Figure 4 As shown, it is assumed that the angle between the line connecting the edge of the fluid surface and the axis of the instrument body and the vertical direction is B, cosB = (RH) / R;

[0078] If the calculation is based on the fluid radius R, the calculation formula for the cross-sectional area data is:

[0079]

[0080] If the inner diameter D of the instrument body is used for calculation, the calculation formula for the cross-sectional area data is:

[0081]

[0082] S33. When the instrument body is installed, it is very likely that the instrument body has a certain tilt angle. Therefore, the fluid cross-sectional area data when the instrument body is installed at a tilt angle is calculated; because when the instrument body and the pipeline are installed, it is usually necessary to align the flange on the instrument body and the flange on the pipeline, which makes the installation of the instrument body have a certain tilt angle, and thus the liquid level sensor on the instrument body will also have a certain tilt angle. After the installation of the instrument body and the pipeline is completed, the installer can preset the tilt angle, and the installer can also measure the tilt angle.

[0083] Reference Figure 5 Since the meter body is installed at an angle, the liquid level sensor is also installed at an angle inside the meter body. The measured liquid level of the fluid is not the real fluid level. Therefore, the liquid level of the fluid in the meter body needs to be corrected. Assuming that the inclination angle of the meter body is X,

[0084] S331, when the liquid level of the fluid is higher than the transducer;

[0085] Assume that the fluid level measured by the level sensor is h, calculate the actual fluid level h at this time z ;

[0086] h z =(hr)cosX+r=(hd / 2)cosX+d / 2;

[0087] like Figure 5 As shown in the figure, assuming that the angle between the line connecting the water surface and its center point and the vertical direction is A, then cosA = (h z -r) / r;

[0088] When calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangle area S2;

[0089] If the calculation is based on the fluid radius r, the calculation formula for the cross-sectional area data is:

[0090]

[0091] If the inner diameter d of the instrument body is used for calculation, the calculation formula for the cross-sectional area data is:

[0092]

[0093] S332, when the liquid level of the fluid is lower than the transducer;

[0094] Reference Figure 5 , assuming that the fluid level measured by the level sensor is H, calculate the actual fluid level H at this timez , the fluid radius is R, and the inner diameter of the instrument body is D;

[0095] H z =R-(RH)cosX=D / 2-(D / 2-H)cosX;

[0096] When calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangular area S2, such as Figure 5 As shown, assuming that the angle between the line connecting the water surface and its center point and the vertical direction is B, cosB = (RH z ) / R;

[0097] When calculating the cross-sectional area data of the fluid, the cross-sectional area data is divided into a sector area S1 and a triangle area S2;

[0098] If the calculation is based on the fluid radius R, the calculation formula for the cross-sectional area data is:

[0099]

[0100]

[0101] If the inner diameter D of the instrument body is used for calculation, the calculation formula for the cross-sectional area data is:

[0102]

[0103] To sum up, it can be seen that the formula for calculating the cross-sectional area data of the fluid in step S32 is a special case of the formula for calculating the cross-sectional area data of the fluid in step S33, that is, when the installation inclination angle of the instrument body is 0, the calculation formula for the cross-sectional area data of the fluid in the instrument body, at this time cosA or cosB are both cosA=cosB=cos0=1.

[0104] S4. Obtain instantaneous flow data of the fluid based on the cross-sectional area data and flow velocity data of the fluid.

[0105] The instantaneous flow rate of the fluid is calculated as:

[0106] q = Sv;

[0107] Wherein, S is the cross-sectional area data of the fluid measured in step S3, and v is the flow velocity data of the fluid measured in step S2;

[0108] Then, the instantaneous flow data q of the fluid is calculated based on the instantaneous flow calculation formula of the fluid.

[0109] When the fluid level in step S322 and step S332 is lower than the installation position of the transducer, the transducer will issue a fault alarm, and the transducer is not in contact with the fluid at this time, so the flow velocity data of the fluid cannot be measured. Therefore, the instantaneous flow data of the fluid cannot be obtained. However, when the fluid level is lower than the installation position of the transducer, the method can still provide the fluid level data and cross-sectional area data of the fluid in the pipeline.

[0110] Therefore, this step is only for calculating the instantaneous flow rate of the fluid when the liquid level of the fluid in step S321 and step S331 is higher than the installation position of the transducer, and obtaining the instantaneous flow rate data of the fluid.

[0111] S5. Calculating the total volume flow data of the fluid based on the instantaneous flow data of the fluid;

[0112] When measuring the flow rate and level data of the fluid in the instrument body, the flow rate and level of the fluid are usually measured several times within 1S, such as 10 times, 20 times, 30 times, etc. This requires the calculation of the total volume flow of the fluid within 1S, that is, the calculation formula for the total volume flow of the fluid is:

[0113]

[0114] Specifically, two calculation methods are given below:

[0115] Wherein, q is the instantaneous flow data, v is the measured instantaneous flow velocity of the fluid, S is the instantaneous cross-sectional area data calculated based on the measured instantaneous liquid level data, τ0 is 0S, and τ1 is 1S.

[0116] The above formula is the integration of multiple instantaneous flow data calculated within a unit time, and assumes that the flow velocity of the fluid changes linearly during each measurement, and the total volume flow data of the fluid within a unit time is obtained, such as Figure 6 shown.

[0117] Based on the method for measuring the flow rate of a fluid in a pipeline disclosed in the above embodiment, an instrument for measuring the flow rate of a fluid in a pipeline matching the method for measuring the flow rate of a fluid in a pipeline is also disclosed.

[0118] The instrument comprises an instrument body, a liquid level sensor, a transducer, a cross-sectional area calculation module, an instantaneous flow calculation module and a total volume flow calculation module.

[0119] The instrument body is installed coaxially with the pipeline, and the coaxiality error between the instrument body and the pipeline after installation is negligible. Specifically, both ends of the instrument body are connected to the pipeline through flange connections, and the inner diameter of the instrument body is the same as the inner diameter of the pipeline;

[0120] The liquid level sensor is installed and fixed on the instrument body, and the liquid level sensor is used to measure the liquid level data of the fluid flowing through the instrument body;

[0121] The transducer is also mounted and fixed on the meter body, and the transducer is mounted and fixed on the side wall in the middle of the meter body. The transducer is used to measure the flow velocity data of the fluid flowing through the meter body;

[0122] The cross-sectional area calculation module is used to calculate the cross-sectional area data of the fluid based on the liquid level data of the fluid;

[0123] The instantaneous flow calculation module is used to calculate the instantaneous flow data based on the cross-sectional area data and flow velocity data of the fluid.

[0124] The total volume flow calculation module is used to calculate the total volume flow data of the fluid based on the instantaneous flow data of the fluid.

[0125] For example 1 in the method:

[0126] Reference Figure 7 , there are multiple liquid level sensors 2 on the instrument body 1, the multiple liquid level sensors 2 are installed on the top tube wall of the instrument body 1, and the multiple liquid level sensors are evenly distributed along the circumferential direction of the instrument body 1, and the transducer 3 is installed at the middle position of the instrument body 1;

[0127] For example 2:

[0128] Reference Figure 8 The liquid level sensor 2 is installed in the middle of the instrument body 1 along the vertical direction, and in order to improve the stability of the liquid level sensor 2 in the instrument body 1 and reduce the impact force of the fluid on the liquid level sensor 2, a fixed column or a vortex generator 4 can be installed inside the instrument body 1, and the liquid level sensor 2 is installed and fixed on the fixed column or the vortex generator 4, so that the liquid level sensor 2 measures the liquid level of the fluid in the instrument body 1, and the transducer 3 is installed in the middle position of the instrument body 1.

[0129] In both Example 1 and Example 2, after the liquid level sensor 2 measures the liquid level data of the fluid, the liquid level data is uploaded to the cross-sectional area calculation module, and the cross-sectional area calculation module calculates the cross-sectional area data of the fluid based on the liquid level data of the fluid, and uploads the cross-sectional area data to the instantaneous flow calculation module of the fluid; however, in the case where the liquid level of the fluid in the pipeline is lower than the installation position of the transducer, the instrument can only provide the liquid level data and cross-sectional area data of the fluid in the pipeline;

[0130] After the transducer measures the flow velocity data of the fluid, the flow velocity data is uploaded to the instantaneous flow calculation module of the fluid. The instantaneous flow calculation module calculates the instantaneous flow data of the fluid based on the cross-sectional area data uploaded and the flow velocity data uploaded by the transducer, and uploads the instantaneous flow data to the total volume flow calculation module. The total volume flow calculation module calculates the total volume flow data of the fluid based on the instantaneous flow data measured multiple times per unit time.

[0131] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the flow rate of a fluid in a pipeline, characterized in that: The following steps are involved: Measuring the liquid level data of the fluid in the pipeline based on the liquid level sensor; Measuring the flow velocity data of the fluid in the pipeline based on the transducer; Obtaining cross-sectional area data of the fluid in the pipeline based on the liquid level data of the fluid; The instantaneous flow data of the fluid is obtained based on the cross-sectional area data and flow velocity data of the fluid.

2. A method for measuring fluid flow in a pipeline according to claim 1, characterized in that: The total volume flow data of the fluid is obtained based on the instantaneous flow data of the fluid.

3. A method for measuring fluid flow in a pipeline according to claim 1, characterized in that: The flow velocity data of the fluid in the pipeline is measured by the ultrasonic time difference method or the Karman vortex street principle, which is the average flow velocity of the fluid in the pipeline.

4. A method for measuring fluid flow in a pipeline according to claim 1, characterized in that: The cross-sectional area data of the fluid in the pipeline is obtained based on the fluid level data, including: The installation inclination angle of the liquid level sensor during installation is obtained, and the cross-sectional area data of the fluid is obtained based on the installation inclination angle and the liquid level data measured by the liquid level sensor.

5. An instrument for measuring the flow rate of a fluid in a pipeline, characterized in that: include: The instrument body is installed coaxially with the pipeline, and the inner diameter of the instrument body is equal to the inner diameter of the pipeline; The liquid level sensor is arranged on the instrument body and is used to measure the liquid level data of the fluid in the instrument body; The transducer is arranged on the instrument body and is used to measure the flow velocity data of the fluid in the instrument body; A cross-sectional area calculation module, used for calculating cross-sectional area data of the fluid based on the liquid level data of the fluid; The instantaneous flow calculation module is used to calculate the instantaneous flow data based on the cross-sectional area data and flow velocity data of the fluid.

6. The instrument for measuring the flow rate of fluid in a pipeline according to claim 5, characterized in that: The instrument also includes: The total volume flow calculation module is used to calculate the total volume flow data of the fluid based on the instantaneous flow data of the fluid.

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