KR102718998B1 - Method for calibration of wet type multipath ultrasonic flowmeter - Google Patents

Abstract

The present invention relates to a calibration method for a wet multi-circuit ultrasonic flow meter.
The present invention is for field verification of a wet multi-circuit ultrasonic flow meter, and comprises the steps of: attaching a pair of dry ultrasonic sensors, which mutually receive and transmit ultrasonic waves, to the outer wall of the measuring tube so as to be spaced apart from each other along the direction of flow of the fluid; measuring a dry measurement velocity of a fluid flowing inside the measuring tube using the dry ultrasonic sensors; measuring partial velocities from each of a plurality of velocity measurement lines of the wet multi-circuit ultrasonic flow meter, and identifying a central partial velocity measured from a central measurement line in which an ultrasonic transmission path passes through the center of the measuring tube among the plurality of velocity measurement lines; calculating a converted partial velocity by converting the partial velocities into a ratio to the central partial velocity, obtaining an average value of the plurality of converted partial velocities, and setting it as a conversion correction factor; and calculating a dry average velocity by multiplying the dry measurement velocity by the conversion correction factor, and verifying the performance of the wet multi-circuit flow meter by comparing the dry average velocity with an average velocity measured by the wet multi-circuit flow meter using the dry average velocity. It has a characteristic.

Description

Method for calibration of wet type multipath ultrasonic flowmeter

The present invention relates to a technology for an ultrasonic flow meter that measures the flow rate and volume of a fluid using ultrasonic waves, and more particularly, to a method and device for directly verifying the performance of an ultrasonic flow meter in the field.

Ultrasonic flow meters are used to measure flow velocity and flow rate by transmitting and receiving ultrasonic waves to moving fluids. When ultrasonic waves are transmitted in the forward direction of the fluid, the transmission time is shorter when they are transmitted in the reverse direction. The velocity and flow rate are measured by using the difference in transmission time in the forward and reverse directions.

Ultrasonic flow meters are installed in pipelines in various industrial sites, including water pipes, and their operating status and performance must be periodically inspected to verify their accuracy and performance.

In order to verify an ultrasonic flowmeter, the flowmeter is sometimes separated from the pipeline and verified at a calibration facility, but this has the problem that the pipeline where the flowmeter is installed must be closed. In addition, even if it is perfectly calibrated at an external calibration facility, it is not sufficient because the performance and function may be affected when reinstalled in the pipeline.

To verify the performance of the ultrasonic flow meter without closing the pipeline, an external wall-mounted flow meter (or dry flow meter) is used. That is, a wall-mounted flow meter is installed separately from the ultrasonic flow meter to be verified in the pipeline and the flow rate is measured to verify the performance of the existing ultrasonic flow meter.

However, when verifying the performance of an existing flow meter using a dry flow meter, there are restrictions on the location where the dry flow meter can be installed. For example, if there are disturbance factors such as bends, expansion pipes, reduction pipes, and valves that can affect the flow of fluid, the location where the dry flow meter can be installed is restricted. For example, if a measurement tolerance of ±2% for disturbance is required, if there is a 90-degree bend in the pipe as a disturbance factor, the dry flow meter must be installed and measured at a point that is at least 30 times the pipe diameter after the end of the bend (Sanderson & Yeung, 2002, UK). In addition, if there is an expansion pipe within 8° as a disturbance factor, the dry flow meter must be installed at a point that is 18 times the diameter after the end of the expansion pipe. In addition, there are restrictions on the location where the dry flow meter can be installed for various disturbance factors. Therefore, there are many difficulties in performing field verification of an existing flow meter using a dry flow meter.

Meanwhile, even when installing a dry ultrasonic flow meter in an existing pipeline to measure flow, there are factors that reduce measurement accuracy. That is, the transmission path or signal intensity of ultrasonic waves are affected by various factors such as the thickness of the pipeline, material, degree of scale attachment, distortion of the pipeline, and the distance between ultrasonic sensors. These physical/mechanical factors may cause problems in the accuracy of velocity/flow measurement using a dry ultrasonic flow meter.

The present invention is intended to solve the above-mentioned problems, and the purpose of the present invention is to provide a calibration method that has high accuracy and reliability and is not limited to the installation location when verifying on-site a pre-installed wet multi-circuit ultrasonic flow meter using an external wall-mounted dry flow meter.

Meanwhile, other unspecified purposes of the present invention will be additionally considered within a range that can be easily inferred from the following detailed description and its effects.

In order to achieve the above object, the present invention provides a wet multi-line ultrasonic flow meter calibration method, which comprises a measuring tube inserted into a pipe with a fluid flowing inside, a pair of wet ultrasonic sensors each of which is disposed facing each other on the upstream and downstream sides in the direction of fluid flow and penetrates the measuring tube to transmit and receive ultrasonic waves from each other, and a plurality of ultrasonic velocity measurement lines disposed spaced apart from each other along the radial direction of the measuring tube, for verifying the performance of the wet multi-line ultrasonic flow meter, comprising the steps of: (a) attaching a pair of dry ultrasonic sensors, which transmit and receive ultrasonic waves from each other, to the outer wall of the measuring tube so as to be spaced apart from each other along the direction of fluid flow; (b) measuring a dry velocity of a fluid flowing inside the measuring tube using the dry ultrasonic sensors; (c) a step of measuring partial velocities from each of the plurality of velocity measurement lines of the wet multi-circuit ultrasonic flowmeter, and identifying a central partial velocity measured from a central measurement line among the plurality of velocity measurement lines in which an ultrasonic transmission path passes through the center of the measurement pipe; (d) a step of calculating a converted partial velocity by converting the partial velocities into a ratio to the central partial velocity, and obtaining an average value of the plurality of converted partial velocities and setting the converted partial velocity as a conversion correction coefficient; and (e) a step of calculating a dry average velocity by multiplying the dry measured velocity by the conversion correction coefficient, and verifying the performance of the wet multi-circuit flowmeter by comparing the dry average velocity with the average velocity measured by the wet multi-circuit flowmeter.

According to the present invention, ultrasonic waves transmitted from the pair of dry ultrasonic sensors are transmitted on a central plane including the center line of the measuring tube.

In one example of the present invention, the pair of dry ultrasonic sensors are mounted on a jig provided in the ultrasonic flow meter, the jig being formed long along the longitudinal direction of the measuring tube and having a pair of guard frames attached to the outer wall of the measuring tube so as to be spaced apart from each other along the radial direction of the measuring tube, and a fixing unit for fixing the position of the dry ultrasonic sensor mounted between the guard frames.

In particular, the above-mentioned fixed unit is installed so as to be positionally movable on the above-mentioned pair of guard frames and has a cover part that surrounds the above-mentioned dry ultrasonic sensor, and a pressurizing rod that is screw-connected to the cover part and pressurizes the above-mentioned dry ultrasonic sensor toward the above-mentioned measuring tube when rotated in the direction of screw fastening.

In one example of the present invention, the pair of dry ultrasonic sensors are mounted between a pair of guard frames of the jig, so that ultrasonic waves emitted from one ultrasonic sensor are reflected from a measuring tube to form a 'V' or 'W' shaped path, and then are received by the other ultrasonic sensor.

In one example of the present invention, a function for the converted partial velocity according to the radial distance of the measuring tube is set using the plurality of converted partial velocity and the spline interpolation method, and the function is integrated with respect to the radial distance of the measuring tube, and then the integrated value is divided by the diameter of the measuring tube to calculate the average value of the converted partial velocity.

The present invention provides a method for performing field verification of a wet multi-circuit ultrasonic flow meter at the same location using a dry ultrasonic sensor. This method is made possible by improvements in the mechanical configuration and the flow rate calculation program.

In the present invention, a dry ultrasonic sensor is used to measure flow in a wet ultrasonic flow meter rather than a pipe, and in particular, a jig is installed in advance to improve the installation accuracy and measurement accuracy of the dry ultrasonic sensor.

In addition, by reflecting the partial flow rate of the fluid area obtained from the wet multi-circuit ultrasonic flowmeter to the flow rate value measured from the dry ultrasonic sensor, the limitation of the dry sensor that measures only with a single circuit can be overcome, thereby improving the measurement accuracy.

Meanwhile, it is added that even if an effect is not explicitly mentioned herein, the effect and its provisional effect described in the following specification expected by the technical features of the present invention are treated as described in the specification of the present invention.

Figure 1 is a drawing for explaining a wet multi-circuit ultrasonic flow meter.
Figure 2 shows the flow rate distribution of the fluid measured by the ultrasonic flow meter illustrated in Figure 1.
Figures 3 and 4 illustrate irregular velocity distribution patterns.
Figure 5 is a schematic flow diagram of a wet multi-circuit ultrasonic flow meter calibration method according to an example of the present invention.
Figure 6 is a schematic perspective view of a jig used in one example of the present invention.
Figure 7 is an exploded perspective view showing the installation of a dry ultrasonic sensor with the jig installed in a wet multi-circuit ultrasonic flow meter.
Figure 8 is a projection view from the front of the pipe so that a virtual plane through which multiple velocity measurement lines pass in Figure 7 is expressed.
Figure 9 is a schematic cross-sectional view of the KK line of Figure 8.
※ It is stated that the attached drawings are provided as references to help understand the technical concept of the present invention, and the scope of the rights of the present invention is not limited thereby.

In describing the present invention, if it is judged that the detailed description of related known functions that are obvious to those skilled in the art and may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Hereinafter, a wet multi-circuit ultrasonic flow meter calibration method (hereinafter referred to as “flow meter calibration method”) according to an example of the present invention will be described in more detail with reference to the attached drawings.

First, the configuration of the wet multi-circuit ultrasonic flow meter that is the subject of verification in the present invention is described.

Figure 1 is a schematic diagram illustrating a wet multi-circuit ultrasonic flow meter.

Referring to the drawing, the wet multi-circuit ultrasonic flow meter (100) has a measuring tube (10) and multiple flow rate measuring lines.

The measuring tube (10) is installed by being inserted in the middle of a pipe (p) through which the fluid flows. The measuring tube (10) is formed in a hollow shape, and a pipe (t) through which the fluid flows is formed inside it. In this embodiment, the measuring tube (10) is formed in a cylindrical shape with an inner diameter of R.

A plurality of velocity measurement lines are provided in the measuring tube (10), and in this example, five velocity measurement lines are provided in particular. Each velocity measurement line is composed of a pair of ultrasonic sensors (21A, 22A, 23A, 24A, 25A) arranged on the upstream side in the flow direction (a) of the fluid and an ultrasonic sensor (21B, 22B, 23B, 24B, 25B) arranged on the downstream side. A pair of ultrasonic sensors is arranged to face each other, and an imaginary straight line connecting a pair of ultrasonic sensors, i.e., a line through which ultrasonic waves are transmitted, is inclined at a certain angle with respect to the flow direction of the fluid.

As shown in the drawing, among the five ultrasonic velocity measurement lines, the remaining four velocity measurement lines are arranged symmetrically at a certain distance along the radial direction of the pipe (t) based on the velocity measurement lines (23A, 23B) arranged at the center of the pipe (t). Each ultrasonic sensor is installed by penetrating the measuring pipe (10) so that the transmitting and receiving surfaces of the ultrasonic sensors are in communication with the pipe. Since they come into direct contact with the fluid flowing in the pipe, they are called wet sensors. In addition, all ultrasonic sensors are electrically connected to a controller (not shown), transmit ultrasonic waves under the control of the controller, and transmit ultrasonic waves to the controller when they are received.

The controller measures the ultrasonic transmission time from the time of transmission to the time of reception of the ultrasonic wave, and calculates the flow velocity of the fluid by using the difference between the transmission time of the ultrasonic wave transmitted from the upstream side and received from the downstream side and the transmission time of the ultrasonic wave transmitted in the reverse direction. Since this is a well-known configuration, a detailed description will be omitted.

The velocity distribution measured in each velocity measurement line is illustrated in Fig. 2. In Fig. 2, X represents the radial distance of the measuring pipe. The velocity measurement lines (21A, 21B and 25A, 25B) arranged at both ends are indicated at _X1 and _X5 , the point arranged in the center is indicated at _X3 , and the remaining two lines are arranged at _X2 and _X4 . They are arranged at equal intervals. Looking at the velocity distribution measured in each velocity measurement line, the velocity is the largest in the center of the pipe and becomes slower as it goes to both sides. This is due to friction with the inner wall of the measuring pipe as it goes toward the edge. In general, the velocity distribution shows a similar shape as illustrated in Fig. 2, but as illustrated in Figs. 3 and 4, it may show an atypical shape in which the velocity is not the largest in the center of the pipe depending on the pipe or flow conditions.

Multi-circuit ultrasonic flowmeters can separately measure the flow rate of a fluid passing through a specific (divided) area along the radial direction of a pipeline, that is, the partial flow rate. Therefore, they have the advantage of being able to accurately measure the flow rate not only when a typical flow rate pattern is shown, but also when an atypical pattern is shown.

As described in the prior art, it is necessary to verify the performance of a wet multi-circuit ultrasonic flow meter on a regular or irregular basis, and the present invention provides a verification method using a dry ultrasonic flow meter, i.e., a flow meter attached to the outer wall of a measuring pipe.

In the case of using a conventional dry flow meter, it is mainly installed and used in a pipe, but in some cases, basic information on the thickness and material of the pipe is not provided, and due to long-term use, scale is attached to the pipe, causing a deformation in the actual pipe thickness, so the measurement accuracy is bound to deteriorate when a dry flow meter is used. As shown in Fig. 9, in a dry flow meter, ultrasonic waves are first refracted in the pipe after being emitted from the sensor, then refracted again when they are incident on the fluid, and after being reflected from the inner wall of the pipe, they undergo two more refractions before being incident on the ultrasonic sensor. It is necessary to know the material and thickness of the pipe, the thickness of the scale, etc., but it is not easy to obtain such information in conventional pipes. In addition, since a dry flow meter receives a reflected wave as shown in Fig. 9, the distance and installation direction between a pair of ultrasonic sensors are very important, but it was difficult to install it precisely in conventional pipes.

In the present invention, a jig capable of mounting a dry flow meter on a wet multi-circuit ultrasonic flow meter is installed in advance. The dry ultrasonic flow meter can be precisely installed using the jig. In addition, unlike a simple pipe, the wet multi-circuit ultrasonic flow meter can accurately determine information about the thickness and material of the measuring pipe, and the inner surface of the pipe is treated with an anti-rust treatment or a liner is attached to minimize the attachment of scale. Therefore, factors related to the refraction and reflection of ultrasonic waves emitted from the dry flow meter can be accurately determined. In addition, the distance between a pair of ultrasonic sensors can be accurately set using the jig, and the installation direction can be accurately aligned with each other.

The configuration of the jig is explained with reference to Figs. 6 and 7.

FIG. 6 is a schematic perspective view of a jig used in one example of the present invention, and FIG. 7 is an exploded perspective view showing a dry ultrasonic sensor being installed while the jig is installed in a wet multi-circuit ultrasonic flow meter.

Referring to the drawing, the jig (50) is provided with a pair of guard frames (51, 52) formed long along the longitudinal direction of the measuring tube (10). The guard frames (51, 52) are spaced apart from each other along the radial direction of the measuring tube (10) and are fixed to the outer wall of the measuring tube (10). A receiving portion (63) in which a dry ultrasonic sensor (61, 62) is seated is formed between the guard frames (51, 52). The distance between the guard frames (51, 52) is formed to be almost the same as the width of the dry ultrasonic sensors (61, 62), so that the alignment direction of the dry ultrasonic sensors is not distorted. The correct alignment direction means that the dry ultrasonic sensors (61, 62) are arranged so that ultrasonic waves are irradiated onto the central plane including the center line (C) of the measuring tube (10), as shown in FIG. 8. A scale (s) is marked on the upper surface of the guard frames (51, 52), so that a pair of dry ultrasonic sensors can be installed on the site without separate equipment. The distance between ultrasonic sensors (61, 62) can be accurately set. A support part (54, 55) is formed at the bottom of a pair of guard frames.

And it has a fixing unit for fixing the position of the dry ultrasonic sensor (61, 62) installed between the guard frames (51, 52). In this example, the fixing unit has a cross section that is approximately 'ㄷ' shaped and has a cover part (56) that is installed so as to be positionally movable on a pair of guard frames (51, 52), and has a pressurizing rod (57) that is screw-fastened to the center of the cover part (56). When the pressurizing rod (57) is rotated in one direction, the pressurizing rod presses the ultrasonic sensor (61, 62) downward so that the ultrasonic sensor (61, 62) is in close contact with the measuring tube (10).

As described above, in the present invention, by installing a jig (50) in advance on the measuring tube (10) of the wet multi-circuit ultrasonic flow meter, the dry ultrasonic sensors (61, 62) can be installed without being twisted in the alignment direction during field verification. In addition, the ultrasonic sensors (61, 62) can be attached to the outer wall of the measuring tube (10) using a fixing unit, so that ultrasonic waves can be transmitted into the fluid without loss. In addition, information on the material, thickness, etc. of the measuring tube (10) is accurately identified, and since there is no scale attached to the inner wall, the refraction and reflection paths of the dry ultrasonic sensor can be accurately predicted according to conditions such as temperature and viscosity of a specific fluid. By accurately identifying the refraction and reflection paths, the optimal separation distance between a pair of ultrasonic sensors (61, 62) can be calculated. In addition, by using the scale (s) indicated on the jig (50), the sensors can be installed accurately according to the calculated separation distance.

On the other hand, the reason why the field verification using the existing dry ultrasonic sensor is difficult is due to the limitation of the installation location. Since the dry ultrasonic sensor is composed of only one line, it is not possible to obtain the partial flow rate for each area by dividing the pipe like a multi-line flow meter. In other words, the measurement precision is lowered compared to a multi-line flow meter. For this reason, when there is a disturbance element in the pipe, the flow rate is measured after the fluid flow is stabilized again at a point sufficiently far away from the point where the disturbance element is present. The present invention is characterized in that it utilizes the flow rate distribution pattern of an existing wet multi-line flow meter to calculate the flow rate by a dry ultrasonic sensor in order to overcome this limitation of the installation location. In the case of a wet multi-line ultrasonic flow meter, the partial flow rate for each area can be calculated independently, so the criteria for the installation location are much more relaxed than for a dry ultrasonic sensor even when there is a disturbance element in the pipe.

A method of utilizing the measured values of a dry ultrasonic sensor and the flow velocity distribution in a pipe identified by a wet multi-circuit ultrasonic flow meter is explained with reference to Fig. 5.

First, the optimal separation distance of the dry ultrasonic sensor is calculated by considering factors such as the thickness of the measuring tube, material, type of fluid, temperature, viscosity, and air volume in the wet multi-circuit flow meter (100) installed in the pipe. Then, a pair of dry ultrasonic sensors (61, 62) are mounted on the jig (50) according to the calculated separation distance. The dry ultrasonic sensors (61, 62) are attached to the outer wall of the measuring tube (10) of the wet multi-circuit flow meter.

After the installation is complete, the flow rate (dry measurement flow rate) of the fluid flowing through the inner pipe of the measuring tube (10) is measured using a dry ultrasonic sensor. As illustrated in FIG. 9, ultrasonic waves emitted from an ultrasonic sensor (61) on one side are transmitted to the fluid, reflected by the inner wall of the measuring tube, and then incident on the ultrasonic sensor (62) on the other side again. Ultrasonic waves are also transmitted and received in the opposite direction. The flow rate of the fluid is measured using the difference in the transmission time of ultrasonic waves emitted in opposite directions. The transmission path (w) of ultrasonic waves emitted from the dry ultrasonic sensor is on the center line (or center plane, C) including the center point of the measuring tube (10), as illustrated in FIGS. 8 and 9. In addition, ultrasonic waves form a path in the letter 'V' or 'W'.

In addition to dry ultrasonic sensors, wet multi-line ultrasonic flow meters measure partial velocities in each area within a pipe using multiple velocity measurement lines. Then, among the partial velocities, the velocity measured by the velocity measurement line located in the center of the pipe, i.e., the central partial velocities, is identified. In general, the central partial velocities are the largest values among the partial velocities. In addition, among the multiple partial velocities, the central partial velocities are the velocities in the area corresponding to the ultrasonic transmission path of the dry ultrasonic sensor.

After measuring the partial velocity, a graph is drawn in which the X-axis is set to the radial distance of the measuring tube and the Y-axis is set to the velocity, and the velocity for the sections between each partial velocity is estimated using an interpolation method (e.g., spline interpolation) to create a velocity distribution as shown in Figure 2. If the velocity distribution is created as a function of the radial distance, the partial velocity at each point in the radial direction is secured.

Thereafter, the converted partial velocities are calculated by converting the partial velocities into a ratio to the central partial velocities, and the average of multiple converted partial velocities is obtained and set as the conversion correction factor. The average can be obtained by dividing the value of the function for the converted partial velocities integrated with respect to the radial distance by the diameter (inner diameter) of the measuring pipe. In a general velocity distribution pattern, the central partial velocities are the largest, so the converted partial velocities are located in the range of 0 to 1, and the average value of the converted partial velocities is also located in the range of 0 to 1. The average value obtained in this way is called the 'conversion correction factor'. Here, the average value reflects all the partial velocities obtained from each velocity measurement line of the multi-circuit flowmeter, and is expressed as a relative value to the central partial velocities.

Therefore, if we multiply the dry measurement velocity measured by the dry ultrasonic sensor above by the conversion correction factor, we can calculate the average velocity of the fluid flowing in the measurement pipe. The dry measurement velocity is a value corresponding to the central part velocity in the wet flow meter, and the conversion correction factor is the average of the ratios to the central part velocity, so if we multiply the dry measurement velocity by the conversion correction factor, we can obtain the average velocity. Finally, we calculate the instantaneous flow rate by multiplying the cross-sectional area.

Compared to the fluid velocity obtained simply using a dry ultrasonic sensor, the velocity obtained using a conversion correction factor that reflects the partial velocity of the wet multi-circuit flow meter as above is more accurate.

By multiplying the measured flow rate using the dry ultrasonic sensor by the conversion correction factor to calculate the (dry) average flow rate, and then comparing it with the average flow rate calculated by the wet multi-circuit ultrasonic flow meter, the measurement accuracy of the wet multi-circuit flow meter can be verified.

Since the existing dry ultrasonic sensors cannot individually measure partial flow rates within a pipe, there is a limitation that measurements must be made after the fluid flow has stabilized into laminar flow, and thus there are limitations on the installation location of the dry ultrasonic sensor. However, in the present invention, the partial flow rates for each region within a pipe obtained from a wet multi-circuit ultrasonic flowmeter are reflected in obtaining the flow rate of the dry ultrasonic sensor, thereby improving the measurement accuracy of the dry ultrasonic sensor and overcoming limitations on the installation location.

As described above, the present invention provides a method for performing field verification of a wet multi-circuit ultrasonic flow meter using a dry ultrasonic sensor. This method is made possible by improvements in the mechanical configuration and the flow rate calculation program.

First, as a mechanical element, the dry ultrasonic sensor is installed in the measurement pipe of the wet multi-circuit ultrasonic flow meter, not in the pipe. In the case of the wet ultrasonic flow meter, the scale is not attached to the inner wall of the measurement pipe, and the material, specification, etc. of the measurement pipe are accurately identified. Compared to the case where the sensor is installed in a pipe with a lot of scale attached to the inner wall and even the information is unclear, if the dry ultrasonic sensor is installed in the measurement pipe of the wet multi-circuit ultrasonic flow meter, the transmission path of the ultrasonic wave emitted from the ultrasonic sensor can be calculated without error, and the optimal separation distance between the ultrasonic sensors can be calculated accordingly. In particular, by installing a jig in advance in the measurement pipe, it is possible to install a pair of dry ultrasonic sensors without twisting the alignment direction, and to accurately maintain the optimal separation distance between the sensors.

Second, the partial velocity of the fluid in the pipe measured by each velocity measuring circuit in the wet multi-circuit flow meter is reflected in the velocity value measured by the dry ultrasonic sensor. The dry ultrasonic sensor is composed of a single circuit, and the accuracy of the velocity measurement may decrease when an abnormal flow such as turbulence or eddy occurs. However, the present invention overcomes this limitation by reflecting the partial velocity of the wet multi-circuit flow meter.

By using the present invention, a dry ultrasonic sensor can be installed directly at the location where a wet multi-circuit ultrasonic flow meter is installed, thereby enabling verification of the wet flow meter, thereby overcoming the problem of limitations on the installation location of the dry sensor. Overcoming limitations on the installation location ultimately means that the flow rate of a fluid in a pipeline can be accurately measured using a dry ultrasonic sensor, thereby improving the reliability of on-site verification.

The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention belongs.

100 ... Wet Multi-Circuit Ultrasonic Flow Meter
10 ... Measuring tube, 21A~25A, 21B~25B ... Velocity measuring line
50 ... Jig, 61,62 ... Ultrasonic sensor

Claims (6)

A method for verifying a wet multi-line ultrasonic flowmeter, comprising: a measuring tube inserted into a pipe through which a fluid flows; and a pair of wet ultrasonic sensors positioned facing each other on the upstream and downstream sides in the direction of the fluid flow and penetrating the measuring tube to transmit and receive ultrasonic waves; wherein a plurality of ultrasonic velocity measurement lines are arranged spaced apart from each other along the radial direction of the measuring tube.
(a) a step of attaching a pair of dry ultrasonic sensors, which receive and transmit ultrasonic waves from each other, to the outer wall of the measuring tube so as to be spaced apart from each other along the direction of fluid flow;
(b) a step of measuring the dry measurement flow rate of the fluid flowing inside the measuring tube using the dry ultrasonic sensor;
(c) a step of measuring partial flow rates from each of the plurality of flow rate measuring lines of the wet multi-circuit ultrasonic flow meter, and determining the central partial flow rate measured from a central measuring line among the plurality of flow rate measuring lines in which the transmission path of the ultrasonic waves passes through the center of the measuring tube;
(d) a step of calculating a converted partial velocity by converting the above partial velocities into a ratio to the above central partial velocity, and calculating an average value of the plurality of converted partial velocities and setting it as a conversion correction coefficient; and
(e) a step of calculating a dry average velocity by multiplying the dry measured velocity by a conversion correction factor, and comparing the dry average velocity with the average velocity measured by the wet multi-circuit flow meter to verify the performance of the wet multi-circuit flow meter;
A calibration method for a wet multi-line ultrasonic flow meter, characterized in that the ultrasonic waves transmitted from the above pair of dry ultrasonic sensors are transmitted on a center plane including the center line of the measuring tube. delete In the first paragraph,
The above pair of dry ultrasonic sensors are mounted on a jig provided in the ultrasonic flow meter,
The above jig,
A pair of guard frames formed lengthwise along the longitudinal direction of the measuring tube and attached to the outer wall of the measuring tube so as to be spaced apart from each other along the radial direction of the measuring tube;
A calibration method for a wet multi-circuit ultrasonic flow meter, characterized by having a fixing unit for fixing the position of the dry ultrasonic sensor mounted between the guard frames. In the third paragraph,
The above fixed unit is installed so as to be positionally movable on the above pair of guard frames and has a cover part that surrounds the dry ultrasonic sensor,
A calibration method for a wet multi-circuit ultrasonic flow meter, characterized by having a pressurizing rod that pressurizes the dry ultrasonic sensor toward the measuring tube when it is screw-connected to the cover part and rotates in the direction of screw fastening. In the third paragraph,
A calibration method for a wet multi-circuit ultrasonic flow meter, characterized in that the above pair of dry ultrasonic sensors are installed between a pair of guard frames of the jig, and ultrasonic waves emitted from one ultrasonic sensor are reflected in a measuring tube to form a 'V' or 'W' shaped path and then received by the other ultrasonic sensor. In the first paragraph,
Using the above-mentioned plurality of converted partial velocities and the spline interpolation method, a function for the converted partial velocities according to the radial distance of the measuring tube is set,
After integrating the above function with respect to the radial distance of the measuring tube,
A calibration method for a wet multi-circuit ultrasonic flow meter, characterized in that the average value of the converted partial velocity is calculated by dividing the integral value by the diameter of the measuring tube.

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