Reflection type flat flow channel with trap structure and flow meter system

Abstract

The invention discloses a reflective flat flow channel with a trap structure and a flowmeter system. The cross section of the flat flow channel is rectangular, and the length of the cross section is larger than the height of the cross section; two ultrasonic sensors are arranged in the middle of one side wall of the flat flow channel in the vertical direction; the axis extension lines 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. A plurality of trap structures with openings facing the interior of the flow channel are arranged on the upper and lower inner wall surfaces of the flat flow channel; the bottom walls of the trap structures are parallel to the upper and lower wall surfaces of the flat flow channel; the top faces of every two adjacent trap structures are located on the same plane, and the planes are the planes where the upper boundary and the lower boundary of the effective flow channel are located. The side walls of two adjacent trap structures are parallel and adjacent to each other, and the wall surface thickness of the formed trap wall is smaller than the ultrasonic wavelength; the plane where the side wall of the trap structure is located is not perpendicular to the axes of the two sensors. According to the invention, the flow meter system is helpful to realize accurate measurement of the gas flow.

Description

Technical Field

[0001] The invention relates to the technical field of measuring instruments, and in particular to a reflective flat flow channel with a trap structure and a flow meter system. Background Art

[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 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 an increasingly important role in natural gas metering and distribution management.

[0003] At present, the flow meters used in natural gas metering and distribution management in China are mainly Roots meters and turbine meters. Both of these metering instruments are mechanical metering instruments and are difficult to get rid of the inherent weaknesses of mechanical meters. For example, they have high requirements on the quality of natural gas, are prone to getting stuck, require frequent maintenance and have high maintenance costs. At the same time, as the diameter of the natural gas transmission pipeline increases, the size, weight and price of the two mechanical metering instruments will increase significantly. These weaknesses have seriously restricted the development of natural gas metering and pipeline distribution management towards the direction of "precision, 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 meters, the flow channel design is mainly based on a circular cross-section flow channel, and there are also designs of flat flow channels with rectangular cross-sections. When the flow area is constant, compared with the circular flow channel, the flat flow channel has a smaller fixed size, which can limit the size of large eddies; at the same time, when the flow rate is constant, the Reynolds coefficient of the flattened flow channel fluid is higher and it is easier to enter the turbulent area. Therefore, the flat flow channel is conducive to the stability of the flow state, which in turn is conducive to the accurate measurement of the flow rate.

[0005] However, due to the reflection and superposition of ultrasonic signals in flat flow channels, flat flow channels suffer from problems such as signal attenuation and distortion in actual applications, which limits their scope of application.

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

[0007] In this regard, the Chinese patent document with publication number CN115265684A discloses a reflective flat flow channel structure with a gradient strip grid, and proposes a method of using a gradient strip grid to solve the signal reflection and superposition problems in the reflective flat flow channel. However, this design method is related to the beam shape of the probe, and in practical applications, it needs to be designed in conjunction with an ultrasonic sensor, which has the problem of limited applicability of ultrasonic sensors. Summary of the invention

[0008] The present invention provides a reflective flat flow channel and a flow meter system with a trap structure, which can effectively solve the problem of insufficient adaptability of the reflective flat flow channel with a gradient strip grid to ultrasonic sensors, expand the application of the flat flow channel in the design of reflective sound channels, and suppress the influence of stray signals in the reflective flat flow channel on the target signal, which is helpful for 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, wherein the cross section of the flat flow channel is rectangular, and the length L of the cross section is greater than the height H; two ultrasonic sensors are arranged at the center of one side wall in the vertical direction of the flat flow channel; the axes of the two ultrasonic sensors form an angle of Φ with the flow direction of the flat flow channel, the extended 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 both provided with a plurality of trap structures with openings facing the inside of the flow channel, and the bottom walls of the trap structures are 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;

[0011] The side walls of two adjacent trap structures are parallel and close to each other, and the thickness d of the formed trap wall is less than the ultrasonic wavelength λ; the plane where the side wall of the trap structure is located is not perpendicular to the axes of the two ultrasonic sensors, and the preferred angle range is 30° to 60°.

[0012] In the present invention, the trap structure is a groove structure whose size parameters are not less than the ultrasonic wavelength λ. Preferably, the trap structure is a polygonal groove structure, whose size parameters are not less than the ultrasonic wavelength λ.

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

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

[0015] The wall thickness d of the trap structure is less than the ultrasonic wavelength λ, and is small enough to prevent the ultrasonic signal from being effectively reflected at the top of the wall and reaching the receiving end ultrasonic sensor. Alternatively, the top of the trap wall is designed to be other shapes that can prevent the ultrasonic signal from reaching the receiving end sensor after being reflected therefrom.

[0016] Preferably, 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 areas of the flat flow channel near the effective path of ultrasonic signal propagation, so as to eliminate the ultrasonic signal from reaching the receiving end sensor after being reflected by the upper and lower walls of the flat flow channel.

[0017] Optionally, all the trap structures in the flat channel have the same structure and the same size, the same structure but different sizes, or different structures but 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° to 60°.

[0019] A flow meter system comprises a measuring flow channel, wherein the measuring flow channel is 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 formed by superimposing a plurality of flat flow channels.

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

[0021] The present invention utilizes a carefully designed trap structure to solve the problem that non-target signals reaching the receiving sensor through paths other than the ideal path cannot be effectively eliminated in the reflective flat flow channel, and at the same time eliminates the problem that the flow channel must be designed in association with the ultrasonic probe as described in the Chinese patent document with publication number CN115265684A. The quality of the ultrasonic signal in the reflective flat flow channel can be effectively improved, so that the ultrasonic flow meter using the flat flow channel can achieve higher metering performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A reflective flat flow channel with a trap structure and a schematic diagram of its parameters according to the present invention.

[0023] Figure 2 Schematic diagram of the rectangular trap structure and parameters in an embodiment of the present invention.

[0024] Figure 3 It is a schematic diagram of the superposition of two reflective flat flow channels with trap structures in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0026] As a theoretical basis, the principle of using ultrasound to measure gas flow is briefly described as follows: The principle of using ultrasound to measure gas flow is the ultrasonic time difference method, that is, using the (downstream) acceleration and (upstream) deceleration of the ultrasonic signal by the fluid, by measuring the propagation time of the ultrasonic wave in the downstream and upstream directions respectively, and then using the difference between the two to calculate the medium flow rate, and finally obtain the medium flow rate. In other words, how to accurately identify the ultrasonic signal and accurately calculate the ultrasonic signal propagation time is the key to whether it can be accurately measured; therefore, all factors that affect the stable propagation of the ultrasonic signal will have an adverse effect on accurate measurement.

[0027] For the signal reflection and superposition problems in the opposite-type flat flow channel, the Chinese patent documents with publication numbers CN115200657A and CN115200658A disclose targeted flow channel design methods. For the signal reflection and superposition problems in the reflective flat flow channel, the Chinese patent document with publication number CN115265684A explains the problems in detail and discloses a reflective flat flow channel structure with a gradient strip grid, and proposes a method of using a gradient strip grid to solve the signal reflection and superposition problems in the reflective flat flow channel. However, this design method is related to the beam shape of the probe, and in practical applications, it needs to be designed in conjunction with an ultrasonic sensor, which has the problem of limited applicability of ultrasonic sensors.

[0028] Theoretically, for a specific ultrasonic sensor, as long as the gradient strip grid is carefully designed under certain beam conditions so that the gradient strip grid can effectively "wrap" the ultrasonic beam, it can block stray signals other than the effective ultrasonic signal, making it impossible for the stray signal to reach the receiving sensor and adversely affect the reception of the effective signal.

[0029] However, in actual applications, with the changes in medium temperature, medium pressure, medium composition, fluid disturbance, probe aging and other factors, 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 gradient grid on stray signals will be weakened or even fail. When this weakening reaches a certain level, it will have a non-negligible impact on the quality of the effective signal, thus affecting the measurement results.

[0030] In this regard, the present invention proposes a reflective flat flow channel with a trap structure, which specifically solves the above-mentioned problems faced when the gradient strip grille design is applied to the reflective sound channel.

[0031] like Figure 1As shown, a reflective flat flow channel with a trap structure, the cross-section of the effective flow channel is a rectangle, the length of the rectangle is L, and the height is H; two ultrasonic sensors are arranged in the middle position in the up and down direction of one of the side walls, the extended lines of the 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°, in practical applications, the range of 30° to 60° is generally preferred.

[0032] In each flow channel, multiple pairs of ultrasonic sensors may be arranged on the two flow channel side walls in the above manner, and the Φ angles 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 inside 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 close to each other, and the thickness d of the formed wall is less than the ultrasonic wavelength λ;

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

[0038] like Figure 2 The figure shows a schematic diagram of a preferred rectangular trap structure and its size parameters. The rectangular trap structure is a rectangular groove structure with four side walls and a bottom wall, an opening at the top, and adjacent walls are perpendicular to each other. When deployed, the opening will face the inside of the flow channel. The structural size requirements are that the length l, width w and height h shall not be less than the wavelength λ of the ultrasonic wave.

[0039] According to the above principle, multiple rectangular trap structures are closely arranged, with the openings facing the inside of the flow channel, and the surfaces where the openings are located are flush, and are arranged on the upper and lower walls of the flow channel. At this time, the flow channel portion sandwiched between the opposite trap structures in the flow channel and available for 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 should be noted: 1. There are trap walls between adjacent trap structures. The width d of the top of the trap wall (i.e., the thickness of the trap wall) should be smaller 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 stray ultrasonic signals to be received by the receiving sensor and affecting the quality of the effective signal; 2. The trap structure can preferably be distributed over the entire upper and lower walls of the flow channel, or it can be distributed only in the upper and lower wall areas of the flow channel near the effective path of the ultrasonic signal, as long as it can effectively eliminate the stray ultrasonic signals that reach the receiving sensor after being reflected by the upper and lower walls 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. It can also be a polygonal groove structure, an inward-folded groove structure, or other shapes, as long as it can effectively block / weaken the ultrasonic signal that is reflected up and down through the flow channel to prevent it from reaching the receiving sensor.

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

[0043] The above-mentioned reflective flat flow channel with a trap structure is applied to a flow meter system, and the number of flow channels can be one or more, so as to realize the working flow measurement of the gas medium. Figure 3 The figure shows the schematic diagram of the superposition of two reflective flat channels with trap structures. When the channels are superimposed, a non-streamlined cross section will be formed due to the thickness of the trap structure. In practical applications, it can be streamlined to reduce its impact on the flow state of the fluid entering the measurement channel.

[0044] Notice, Figure 3 The sensors in the two flow channels are arranged on the same side of the flow channels, but the actual application is not limited to this, and the angles between the sensor axes and the longitudinal axes of the flow channels in different flow channels are not necessarily the same. Furthermore, the widths and heights of different flow channels are not necessarily the same.

[0045] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A reflective flat flow channel with a trap structure, characterized in that: The cross section of the flat flow channel is rectangular, and the length L of the cross section is greater than the height H. Two ultrasonic sensors are arranged at the center of one side wall of the flat flow channel in the vertical direction. The axes of the two ultrasonic sensors form an angle Φ with the flow direction of the flat flow channel. The extended 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. The upper and lower inner walls of the flat flow channel are both provided with a plurality of trap structures with openings facing the inside of the flow channel, and the bottom walls of the trap structures are 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 two adjacent trap structures are parallel and close to each other, and the thickness d of the formed trap wall is less than the ultrasonic wavelength λ; the plane where the side wall of the trap structure is located is not perpendicular to the axes of the two ultrasonic sensors, and the angle range is 30° to 60°.

2. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: The trap structure is a groove structure whose size parameters are not less than the ultrasonic wavelength λ.

3. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: The trap structure is a polygonal groove structure, and the size parameters of the polygonal groove are not less than the ultrasonic wavelength λ.

4. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: The effective flow channel is a channel for the medium to flow along the longitudinal axis direction of the flat flow channel between the upper and lower trap structures after trap structures are arranged on the upper and lower walls of the flat flow channel.

5. 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 ultrasonic signal from being effectively reflected at the top of the wall and reaching the ultrasonic sensor at the receiving end.

6. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: The trap structure is arranged on the upper and lower inner walls of the entire flat channel, or only on the upper and lower inner wall areas of the flat channel near the effective path of ultrasonic signal propagation, so as to eliminate the ultrasonic signal from reaching the receiving end sensor after being reflected by the upper and lower walls of the flat channel.

7. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: All the trap structures in the flat flow channel have the same structure and the same size, the same structure but different sizes, or different structures but different sizes.

8. The reflective flat flow channel with a trap structure according to claim 1, characterized in that: 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°.

9. A flow meter system, comprising a measuring flow channel, characterized in that: The measuring flow channel is composed of a reflective flat flow channel with a trap structure as described in any one of claims 1 to 8; wherein, the measuring flow channel is composed of one flat flow channel, or is composed of a plurality of flat flow channels superimposed on each other.

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