A reflective flat flow channel with trap structure and flow meter system

Abstract

The application discloses a reflective flat flow channel with trap structure and a flow meter system. The cross section of the flat flow channel is rectangular, and the length of the cross section is greater than the height. Two ultrasonic sensors are arranged at the central position of the upper and lower direction of one side wall of the flat flow channel. The extension lines of the axes of the two sensors intersect on the other side wall, and the plane determined by the axes of the two sensors is perpendicular to the side wall. The upper and lower inner walls of the flat flow channel are each provided with a plurality of trap structures with openings facing the inside of the flow channel. The bottom wall of the trap structure is parallel to the upper and lower walls of the flat flow channel. The top surfaces of two adjacent trap structures are on the same plane, and the plane is the plane where the upper and lower boundaries of the effective flow channel are located. The side walls of the two adjacent trap structures are parallel and adjacent, and the thickness of the trap wall surface formed by the side walls is less than the wavelength of the ultrasonic wave. The plane where the side wall of the trap structure is located is not perpendicular to the axes of the two sensors. The application is helpful for the flow meter system to realize accurate measurement of the gas flow.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metering instruments, in particular to a reflective flat flow channel with a trap structure and a flow meter system. BACKGROUND

[0002] As people pay more and more attention to the environment, natural gas as a clean and environmentally friendly green energy has received more and more attention and application, and the natural gas industry will continue to develop rapidly in the future. In order to meet the development needs of the natural gas industry, especially the development needs of gas companies for natural gas metering and pipeline distribution management, under the background of the development of information technology, ultrasonic gas flow meters have gradually played a greater role in natural gas metering and pipeline distribution management.

[0003] At present, the flow meters mainly used in natural gas metering and pipeline distribution management in China are Roots meters and turbine meters. Both of these two types of metering instruments belong to mechanical metering instruments, and it is difficult to overcome the inherent weaknesses of mechanical metering instruments, such as high requirements for the quality of natural gas, easy to jam, frequent maintenance and high maintenance cost. At the same time, with the increase of the diameter of the natural gas conveying pipeline, the volume, weight and price of the two types of mechanical metering instruments will increase substantially, which seriously restricts the development of natural gas metering and pipeline distribution management in the direction of "accuracy, stability, intelligence and efficiency".

[0004] In order to overcome the shortcomings of mechanical metering instruments, ultrasonic flow meters have appeared in the prior art. In the current ultrasonic flow meter, the flow channel design is mainly based on a circular cross-section flow channel, and there are also designs of rectangular flat flow channels. Compared with circular flow channels, flat flow channels have smaller fixed dimensions and can limit the size of large eddies under the condition of a certain flow area. At the same time, under the condition of a certain flow, the Reynolds coefficient of the fluid in the flat flow channel is higher, and it is easier to enter the turbulent flow region. Therefore, the flat flow channel is beneficial to the stability of the flow state, and then beneficial to the accurate measurement of the flow.

[0005] However, due to the signal reflection and superposition of ultrasonic signals in the flat flow channel, there are problems such as signal weakening and distortion in the actual application of the flat flow channel, which limits its application range.

[0006] In this regard, the Chinese patent document with publication number CN115200657A discloses a flat flow channel structure with a strip-shaped grid, and the Chinese patent document with publication number CN115200658A discloses a flat flow channel structure with an ultrasonic trap structure, which is used to solve the problems of signal reflection and superposition in the reflective flat flow channel. However, when the above method is applied to the reflective flat flow channel, there is still a problem of mutual interference caused by ultrasonic signal reflection and superposition.

[0007] To this end, the Chinese patent document with publication number CN115265684A discloses a reflective flat flow channel structure with a gradually changing strip-shaped grid, and proposes a method for solving the problems of signal reflection and superposition in the reflective flat flow channel using a gradually changing strip-shaped grid. However, this design method is related to the beam shape of the probe, and in actual application, it needs to be designed in conjunction with the ultrasonic sensor, which has the problem of limited applicability of the ultrasonic sensor. SUMMARY

[0008] The present application provides a reflective flat flow channel with a trap structure and a flow meter system, which can effectively solve the problem of insufficient adaptability of the reflective flat flow channel with a gradually changing strip-shaped grid to the ultrasonic sensor, expand the application of the flat flow channel in the design of the reflective acoustic channel, suppress the influence of stray signals in the reflective flat flow channel on the target signal, and help the flow meter system using the flat flow channel to achieve accurate measurement of gas flow.

[0009] A reflective flat flow channel with a trap structure, the cross section of the flat flow channel is rectangular, the length L of the cross section is greater than the height H; two ultrasonic sensors are arranged in the upper and lower central positions of one of the side walls of the flat flow channel; the angle between the axis of the two ultrasonic sensors and the flow direction of the flat flow channel is Φ, the extension lines of the axes of the two ultrasonic sensors intersect on the other side wall, and the plane determined by the axes of the two ultrasonic sensors is perpendicular to the side wall;

[0010] The upper and lower inner walls of the flat flow channel are each provided with a plurality of trap structures with openings facing the inside of the flow channel, the bottom wall of the trap structure is parallel to the upper and lower walls of the flat flow channel; the top surfaces of two adjacent trap structures are on the same plane, and the plane is the plane in which the upper and lower boundaries of the effective flow channel lie;

[0011] The side walls of two adjacent trap structures are parallel and adjacent, forming a trap wall with a wall thickness d less than the ultrasonic wave length λ; the plane in which the side walls of the trap structure lie is not perpendicular to the axes of the two ultrasonic sensors, and the preferred angle range is 30°-60°.

[0012] In the present application, the trap structure is a groove structure with all size parameters not less than the ultrasonic wave length λ. Preferably, the trap structure is a polygonal groove structure, and all size parameters of the polygonal groove are not less than the ultrasonic wave length λ.

[0013] When the trap structure adopts a rectangular groove structure, the size parameters (including length l, width w and height h) of the rectangular groove are all not less than the ultrasonic wave length λ.

[0014] The effective flow channel is a channel for the medium to flow along the longitudinal axis of the flat flow channel between the upper and lower trap structures after the trap structure is provided on the upper and lower walls of the flat flow channel.

[0015] The wall thickness d of the trap structure is smaller than the ultrasonic wave wavelength λ, and is small enough to meet the requirement of preventing the ultrasonic wave signal from being effectively reflected at the top of the wall to reach the receiving end ultrasonic wave sensor. Alternatively, the top of the trap wall is designed in other shapes to prevent the ultrasonic wave signal from being reflected to reach the receiving end sensor.

[0016] Preferably, the trap structure is arranged on the upper and lower inner walls of the entire flat flow channel, or is arranged only on the upper and lower inner wall regions of the flat flow channel near the effective path of ultrasonic wave signal propagation, so as to eliminate the ultrasonic wave signal reflected by the upper and lower walls of the flat flow channel to reach the receiving end sensor.

[0017] Alternatively, all trap structures in the flat flow channel use the same structure, the same size, different structures, or different sizes.

[0018] Preferably, the ratio of the length L to the height H of the cross section is not less than 3, and Φ is 30°-60°.

[0019] A flow meter system includes a measuring flow channel composed of a reflective flat flow channel with a trap structure; wherein the measuring flow channel is composed of one flat flow channel, or is composed of multiple flat flow channels stacked together.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The present application uses a carefully designed trap structure to solve the problem of non-target signals reaching the receiving sensor through paths other than the intended path in the reflective flat flow channel, and eliminates the problem that the flow channel must be designed in association with the ultrasonic wave probe as described in the Chinese patent document CN115265684A, thereby effectively improving the quality of ultrasonic wave signals in the reflective flat flow channel, and enabling the ultrasonic wave flow meter using the flat flow channel to achieve higher metering performance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A reflective flat flow channel with a trap structure and its parameter diagram.

[0023] Figure 2 A rectangular prism-shaped trap structure and its parameter diagram in an embodiment of the present application.

[0024] Figure 3 A diagram of two reflective flat flow channels with trap structures stacked together in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in conjunction with the drawings and embodiments, it should be noted that the following embodiments are intended to facilitate the understanding of the present application, and do not limit the present application in any way.

[0026] As a theoretical basis, the principle of using ultrasonic waves to measure gas flow is briefly described as follows: the principle of using ultrasonic waves to measure gas flow is the time difference method of ultrasonic waves, that is, using the acceleration of fluid (downstream) and deceleration of fluid (upstream) on ultrasonic wave signals, measuring the time of ultrasonic wave propagation in downstream and upstream directions respectively, and then calculating the medium flow rate by using the difference between the two, and finally obtaining the medium flow rate. That is, how to accurately identify the ultrasonic wave signal and accurately calculate the ultrasonic wave signal propagation time is the key to accurate measurement; therefore, all factors affecting the stable propagation of ultrasonic wave signals will adversely affect accurate measurement.

[0027] For the problem of signal reflection and superposition in the reflection type flat flow channel, Chinese patent documents with publication numbers CN115200657A and CN115200658A disclose a specific flow channel design method. For the problem of signal reflection and superposition in the reflection type flat flow channel, Chinese patent document with publication number CN115265684A describes the problem in detail and discloses a reflection type flat flow channel structure with a gradually changing strip-shaped grid, and proposes a method for solving the problem of signal reflection and superposition in the reflection type flat flow channel using the gradually changing strip-shaped grid. However, this design method is related to the beam shape of the probe, and in actual application, it needs to be designed in association with the ultrasonic sensor, and there is a problem of limited applicability of the ultrasonic sensor.

[0028] In theory, for a specific ultrasonic sensor, as long as the gradually changing strip-shaped grid is carefully designed under certain beam conditions so that the gradually changing strip-shaped grid can effectively "wrap" the ultrasonic beam, it can achieve the shielding of stray signals other than effective ultrasonic signals, so that the stray signals cannot reach the receiving sensor and then adversely affect the reception of effective signals.

[0029] However, in actual application, with the changes of medium temperature, medium pressure, medium composition, and other factors, and the influence of fluid disturbance and probe aging, the beam shape of the ultrasonic sensor will change to a certain extent. When this change exceeds a certain range, the shielding effect of the strip-shaped gradually changing grid on stray signals will be weakened or even invalid. When this weakening reaches a certain degree, it will have a non-negligible impact on the quality of effective signals, thereby affecting the measurement results.

[0030] To this end, the present application proposes a reflection type flat flow channel with a trap structure to solve the above-mentioned problems faced by the gradually changing strip-shaped grid design applied to the reflection type sound channel.

[0031] As Figure 1As shown in the figure, a reflective flat flow channel with a trap structure has an effective flow channel with a rectangular cross-section, a length of L and a height of H. Two ultrasonic sensors are arranged in the center of one side wall in the vertical direction, and the extended axes of the two sensors SA and SB intersect on the other side wall, and the plane where the axes of the two sensors are located is perpendicular to the side wall. The angles between the axes of the two sensors and the longitudinal axis of the flow channel (gas flow direction) are both Φ. Theoretically, Φ≠90° is sufficient. In practical applications, the range of 30° to 60° is generally preferred.

[0032] Each flow channel may be provided with multiple pairs of ultrasonic sensors on the two flow channel side walls in the above manner, and the angle Φ of each pair may be the same or different.

[0033] At the same time, trap structures are placed on the upper and lower walls of the flow channel according to the following optimization principles:

[0034] a. The bottom wall of the trap structure is parallel to the upper and lower walls of the flow channel, and the opening faces the interior of the flow channel;

[0035] b. The top surfaces of adjacent trap structures are on the same plane, and this plane is the plane where the upper and lower walls of the effective flow channel are located;

[0036] c. The side walls of adjacent trap structures are parallel and closely adjacent, and the thickness d of the formed wall is less than the ultrasonic wavelength λ;

[0037] d. The plane of the side wall of the trap structure is not perpendicular to the straight line of the sensor axis.

[0038] like Figure 2 Figure 2 shows a schematic diagram of a preferred rectangular trap structure and its dimensional parameters. The rectangular trap structure is a rectangular groove with four side walls and a bottom wall, an opening at the top, and perpendicular walls. When deployed, the opening faces the interior of the flow channel. The structural dimensions must be such that the length l, width w, and height h must not be less than the ultrasonic wavelength λ.

[0039] Following the above principles, multiple rectangular trap structures are closely arranged, with their openings facing the interior of the flow channel and flush with the surfaces where they are located. They are also placed on the upper and lower walls of the flow channel. The portion of the flow channel between the opposing trap structures, which allows fluid to pass through, is called the effective flow channel, and the corresponding cross-section is called the effective cross-section.

[0040] At the same time, two points need to be noted: 1. There is a trap wall between adjacent trap structures, and the width d (i.e. the thickness of the trap wall) at the top of the trap wall should be less than the wavelength λ of the ultrasonic wave used in the application, and the smaller the better, to prevent the formation of an effective ultrasonic reflection surface, so that the ultrasonic signal is effectively reflected at the top of the trap wall, causing the stray ultrasonic signal to be received by the receiving sensor and affecting the quality of the effective signal; 2. The trap structure is preferably distributed on the entire upper and lower wall surfaces of the flow channel, or can be distributed only in the upper and lower wall regions of the flow channel near the effective path of the ultrasonic signal, as long as it can effectively eliminate the stray ultrasonic signal that reaches the receiving sensor after being reflected by the upper and lower wall surfaces of the flow channel.

[0041] The preferred structure of the trap structure is a rectangular groove structure, but it is not limited to this structure, and can also be a polygonal groove structure, an inner fold line groove structure, etc., as long as it can effectively eliminate / weaken the ultrasonic signal reflected by the upper and lower wall surfaces of the flow channel to avoid its reaching the receiving sensor.

[0042] The same type of trap structure with uniform size is usually used in a reflective flat flow channel with trap structure, but trap structures of the same type with different sizes or even different types can also be used at the same time.

[0043] The reflective flat flow channel with trap structure described above is applied to a flowmeter system, and the number of flow channels can be one or multiple to achieve the flow measurement of the working condition of the gas medium. Figure 3 The figure shown is a superimposed schematic diagram of two reflective flat flow channels with trap structure. When the flow channels are superimposed, a non-streamline cross-section will be formed due to the thickness of the trap structure, and in actual application, streamline processing can be performed to reduce its influence on the flow state of the fluid entering the measurement flow channel.

[0044] Note that, Figure 3 The sensors in the two flow channels are arranged on the same side of the flow channel, but in actual application, this is not limited, and the angle between the sensor axis and the longitudinal axis of the flow channel in different flow channels is not necessarily consistent. Further, the width and height of different flow channels do not necessarily have to be consistent.

[0045] The above-described embodiments have described the technical solutions and beneficial effects of the present application in detail, and it should be understood that the above-described embodiments are only specific embodiments of the present application and are not intended to limit the present application. Any modification, supplement and equivalent replacement made within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A reflective flat flow channel with trap structure, characterized by, The cross section of the flat flow channel is rectangular, the length L of the cross section is greater than the height H; two ultrasonic sensors are arranged in the middle of the upper and lower direction of one of the side walls of the flat flow channel; the angle between the axis of the two ultrasonic sensors and the flow direction of the flat flow channel is Φ, the extension line of the axis of the two ultrasonic sensors intersects on the other side wall, and the plane determined by the axis of the two ultrasonic sensors is perpendicular to the side wall; The upper and lower inner walls of the flat flow channel are each provided with a plurality of trap structures with openings facing the inside of the flow channel, the bottom wall of the trap structure is parallel to the upper and lower walls of the flat flow channel; the top surfaces of adjacent two trap structures are on the same plane, and the plane is the plane on which the upper and lower boundaries of the effective flow channel are located; The trap structure is a groove structure with all size parameters not less than the wavelength λ of the ultrasonic wave; The side walls of adjacent two trap structures are parallel and adjacent, forming a trap wall with a wall thickness d less than the wavelength λ of the ultrasonic wave; the plane on which the side walls of the trap structure are located is not perpendicular to the axis of the two ultrasonic sensors, and the included angle ranges from 30° to 60°.

2. The trap-structured reflective flat flow channel according to claim 1, wherein The trap structure is a polygonal groove structure, and the size parameters of the polygonal groove are all not less than the wavelength λ of the ultrasonic wave.

3. The trap-structured reflective flat flow channel according to claim 1, wherein The effective flow channel is a channel between the upper and lower trap structures of the flat flow channel for the medium to flow along the longitudinal axis direction of the flat flow channel after the trap structure is arranged on the upper and lower walls of the flat flow channel.

4. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: The wall thickness d of the trap structure needs to meet the requirement of preventing the effective reflection of the ultrasonic signal at the top end of the wall to reach the receiving end ultrasonic sensor.

5. The trap-structured reflective flat flow channel according to claim 1, wherein The trap structure is arranged on the upper and lower inner walls of the entire flat flow channel, or only on the upper and lower inner wall regions of the flat flow channel near the effective path of the ultrasonic signal propagation, so as to eliminate the reflection of the ultrasonic signal on the upper and lower walls of the flat flow channel and reach the receiving end sensor.

6. The trap-structured reflective flat flow channel according to claim 1, wherein All trap structures in the flat flow channel use the same structure, the same size, different structures or different sizes.

7. The trap-structured reflective flat flow channel according to claim 1, wherein The ratio of the length L to the height H of the cross section is not less than 3, and Φ is 30° to 60°.

8. A flow meter system comprising a measurement flow passage, characterized by, The measuring flow channel is composed of the trap-structured reflective flat flow channel according to any one of claims 1 to 7; wherein the measuring flow channel is composed of one flat flow channel, or is composed of a plurality of flat flow channels stacked together. The measuring flow channel is composed of the trap-structured reflective flat flow channel according to any one of claims 1 to 7; wherein the measuring flow channel is composed of one flat flow channel, or is composed of a plurality of flat flow channels stacked together.

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