Mass flowmeter

Abstract

A mass flowmeter, comprising: at least one flow tube, wherein any flow tube is axisymmetric about an imaginary symmetry axis; an excitation unit (13), wherein the excitation unit (13) is arranged in an intermediate tube section (11) and is used for driving the flow tube to vibrate; and a vibration sensing unit (14), comprising pick-up sensors (141, 142) which are symmetrically arranged on two sides of the excitation unit (13), wherein the pick-up sensors (141, 142) are used for acquiring a vibration signal of the flow tube. The flow tube comprises the intermediate tube section (11) passing through the imaginary symmetry axis and inner bent tube sections (12) located at two ends of the intermediate tube section (11); the intermediate tube section (11) is smoothly connected to the inner bent tube sections (12); the intermediate tube section (11) of the flow tube is a straight tube; the inner bent tube sections (12) of the flow tube are bent tubes; and the ratio of the length of the intermediate tube section (11) to the outer tube diameter of the intermediate tube section (11) is greater than 0 and less than or equal to 3. The vibration frequency of the mass flowmeter is less sensitive to pressure, so that the measurement is more accurate.

Description

Mass flow meter

[0001] The present application claims priority to the Chinese patent application No. 202410691872.0, filed on May 30, 2024, and entitled "Mass flow meter", the content of which is incorporated herein by reference in its entirety.

[0002] The present application claims priority to the Chinese patent application No. 202422952282.7, filed on November 29, 2024, and entitled "Mass flow meter", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of flow metering, in particular to a mass flow meter. BACKGROUND

[0004] In industrial measurement technology, in order to determine a characteristic measurement variable of a flowing medium, such as a liquid and / or a gas, in a process line, such as a pipe, a measurement system is often used, which, by means of a vibrating measurement transducer and a connected measurement device electronics with a driver and evaluation circuit, induces counter forces, such as Coriolis forces, in the flowing medium and generates measurement signals which correspondingly represent at least one measurement variable, such as a mass flow rate, a density, a viscosity or other process parameters, derived from these forces.

[0005] Such measurement systems, often formed by means of an online measurement device with a compact design with an integrated measurement transducer, such as a Coriolis mass flow meter, have been known for a long time and are proven in industrial applications. However, Coriolis mass flow meters have requirements for the pipe design, which, especially in compact Coriolis mass flow meters, can affect the pressure sensitivity of the Coriolis mass flow meter and affect the detection accuracy of the mass flow meter. SUMMARY

[0006] The purpose of the present application is to provide a technical solution to solve the problem of pressure sensitivity of the mass flow meter in the related art, which easily affects the detection accuracy.

[0007] In order to achieve the above purpose, the present application provides a mass flow meter, comprising:

[0008] At least one flow tube, any flow tube is axisymmetric about an imaginary symmetry axis, the flow tube comprises a middle tube section passing through the imaginary symmetry axis and inner elbow tube sections located at both ends of the middle tube section, the middle tube section and the inner elbow tube section are smoothly connected;

[0009] An excitation unit, the excitation unit is arranged on the middle tube section and is used to drive the flow tube to vibrate;

[0010] The vibration sensing unit comprises pick-up sensors symmetrically arranged on both sides of the vibration exciting unit, and the pick-up sensors are used to acquire the vibration of the flow tube.

[0011] The intermediate pipe section of the flow tube is a straight pipe, and the inner elbow pipe section of the flow tube is a bend pipe, and the ratio of the length of the intermediate pipe section to the outer pipe diameter of the intermediate pipe section is greater than 0 and less than or equal to 3.

[0012] Further, the ratio of the length of the intermediate pipe section to the outer pipe diameter of the intermediate pipe section is greater than or equal to 1.5.

[0013] Further, the flow tube further comprises a transition straight pipe section and a transition bend pipe section, one end of the transition straight pipe section is smoothly connected with the inner elbow pipe section, the other end of the transition straight pipe section is smoothly connected with one end of the transition bend pipe section, and the other end of the transition bend pipe section is used as an outlet end or an inlet end of the flow tube.

[0014] The ratio of the curvature radius of the inner elbow pipe section to the curvature radius of the transition bend pipe section is greater than or equal to 1.25.

[0015] Further, the transition straight pipe section and the intermediate pipe section are coupled through the inner elbow pipe section, any transition straight pipe section has an imaginary axis, the imaginary axis of the transition straight pipe section has a direction vector pointing to the coupled inner elbow pipe section; the intermediate pipe section has an imaginary axis, the imaginary axis of the intermediate pipe section has a direction vector pointing to the coupled inner elbow pipe section; the included angle between the direction vector of the intermediate pipe section and the direction vector of the transition straight pipe section is defined as a first included angle, and the angle of the first included angle satisfies: the angle is greater than or equal to 90° and less than or equal to 105°.

[0016] Further, the angle of the first included angle is greater than or equal to 95°.

[0017] Further, the opening direction of the transition bend pipe section is parallel to the axial direction of the intermediate pipe section.

[0018] A first straight line is defined, the first straight line coincides with the axis of the intermediate pipe section, a second straight line is defined, the second straight line is parallel to the first straight line, and the second straight line passes through the center of the opening end of the transition bend pipe section.

[0019] The ratio of the distance between the first straight line and the second straight line to the outer pipe diameter of the flow tube is less than or equal to 12.

[0020] Further, the bending angle of the inner elbow pipe section is equal to the bending angle of the transition bend pipe section.

[0021] Further, the mass flow meter further comprises a processing module, the processing module is used to send an excitation signal to the vibration exciting unit to make the flow tube vibrate at a resonance frequency, and receive and process a vibration signal transmitted by the vibration sensing unit, the vibration signal is used to characterize the vibration of the flow tube.

[0022] The processing module generates at least a mass flow measurement value based on the vibration signals, the mass flow measurement value representing an instantaneous mass flow rate of the measured fluid flowing through the mass flow meter.

[0023] Further, the processing module generates a density measurement value based on the vibration signals, the density measurement value representing an instantaneous density of the measured fluid flowing through the mass flow meter.

[0024] Further, the mass flow meter comprises two or more flow tubes, inlet ends of all the flow tubes are configured to be connected with the inlet flow divider, outlet ends of all the flow tubes are configured to be connected with the outlet flow divider, the measured fluid flows into each flow tube equally through the inlet flow divider and flows out through the outlet flow divider, structures of all the flow tubes are substantially identical, and the flow tubes are formed by bending a metal round tube.

[0025] Further, the mass flow meter comprises two or more flow tubes, a first straight line is defined, the first straight line coincides with the axis of the intermediate tube segment;

[0026] The mass flow meter further comprises a coupling sheet, the two or more flow tubes are coupled through the coupling sheet, wherein the coupling sheet comprises a first coupling sheet, the first coupling sheet is fixedly connected with the transition straight tube segment, a first intersection point is defined, the first intersection point is an intersection point of an extension direction of the imaginary axis of the transition straight tube segment and an extension direction of the first coupling sheet, a distance from the first intersection point to the first straight line is defined as a first distance, a ratio of the first distance to an outer tube diameter of the intermediate tube segment is greater than or equal to 4 and less than or equal to 12.

[0027] Further, an included angle between the extension direction of the first coupling sheet and the imaginary symmetry axis of the flow tube is defined as a second included angle, the angle of the second included angle satisfies: the angle is greater than or equal to 75° and less than or equal to 85°.

[0028] Further, the mass flow meter further comprises a second coupling sheet, the second coupling sheet is fixedly connected with the transition elbow tube segment;

[0029] An included angle between the extension direction of the second coupling sheet and the imaginary symmetry axis of the flow tube is defined as a third included angle, the angle of the third included angle satisfies: the angle is greater than or equal to 25° and less than or equal to 35°.

[0030] According to the above description, the embodiments of the present application provide a mass flow meter, by designing the flow tube type of the mass flow meter, the sensitivity of the vibration frequency of the mass flow meter to pressure is reduced, and the detection is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings in which:

[0032] Fig. 1 is a schematic diagram of a mass flow meter according to an embodiment of the present application;

[0033] Fig. 2 is a schematic diagram of a U-shaped tube according to the related art;

[0034] Fig. 3 is a schematic diagram of a flow tube according to an embodiment of the present application;

[0035] Fig. 4 is a schematic diagram of the flow tube of Fig. 3 with a radius of curvature labeled;

[0036] Fig. 5 is a schematic diagram of the flow tube of Fig. 3 with a first included angle labeled;

[0037] Fig. 6 is a schematic diagram of a flag mount scenario according to an embodiment of the present application;

[0038] Fig. 7 is a schematic diagram of a height of a flow tube according to an embodiment of the present application;

[0039] Fig. 8 is a schematic diagram of a mass flow meter according to an embodiment of the present application;

[0040] Fig. 9 is a schematic diagram of a first coupling tab installation according to Fig. 8;

[0041] Fig. 10 is a schematic diagram of a second coupling tab installation according to Fig. 8.

[0042] Reference signs: intermediate tube section 11, inner elbow tube section 12, excitation unit 13, vibration sensing unit 14, first pick-off sensor 141, second pick-off sensor 142, transition straight tube section 15, transition elbow tube section 16, first coupling tab 17, second coupling tab 18, imaginary axis of symmetry 101. DETAILED DESCRIPTION

[0043] The present application will be described in detail below with reference to specific embodiments shown in the drawings, but these embodiments do not limit the present application, and modifications of structure, method, or function made by those of ordinary skill in the art based on these embodiments are included in the scope of the present application.

[0044] The purpose of the present application is to provide a high-precision, compact mass flow meter that can adapt to fluid medium flow measurement requirements in a small space.

[0045] To achieve the above purpose, as shown in Fig. 1, the present application provides a mass flow meter, which includes at least one flow tube, an excitation unit 13, and a vibration sensing unit 14.

[0046] Wherein, for two or more flow tubes, the inlet ends of all the flow tubes are connected with the inlet flow divider, the outlet ends of the flow tubes are connected with the outlet flow divider, the flow tubes are used to transport flow medium, the flow medium is divided at the inlet flow divider and flows into two or more flow tubes equally, and is converged at the outlet flow divider. The structural type of all the flow tubes is basically consistent, and one of the flow tubes is taken as an example. The flow tube is axisymmetric about an imaginary symmetry axis. The flow tube comprises a middle tube segment 11 passing through the imaginary symmetry axis and inner elbow segments 12 located at both ends of the middle tube segment 11. The middle tube segment 11 is smoothly connected with the inner elbow segments 12. In order to facilitate the description, the flow tube is defined as comprising a first inner elbow segment and a second inner elbow segment in the embodiments of the present application. The first inner elbow segment is the inner elbow segment 12 close to the inlet end of the flow tube, and the second inner elbow segment is the inner elbow segment 12 close to the outlet end of the flow tube.

[0047] The exciting unit 13 is arranged in the middle tube segment 11 and is used to drive the flow tube to vibrate. Further, the exciting unit 13 is arranged close to the imaginary symmetry axis of the flow tube, and preferably, the exciting unit 13 is arranged in the middle of the middle tube segment 11. The imaginary symmetry axis of the flow tube passes through the exciting unit 13. In this way, it can be ensured that the flow tube vibrates uniformly.

[0048] The vibration sensing unit 14 comprises pickup sensors symmetrically arranged on both sides of the exciting unit 13. The pickup sensors are used to acquire the vibration condition of the flow tube.

[0049] Exemplarily, the vibration sensing unit 14 comprises a first pickup sensor 141 and a second pickup sensor 142. The first pickup sensor 141 is used to acquire the vibration condition of the flow tube close to the first inner elbow segment, and the second pickup sensor 142 is used to acquire the vibration condition of the flow tube close to the second inner elbow segment. The first pickup sensor 141 and the second pickup sensor 142 are axisymmetric about the imaginary symmetry axis of the flow tube.

[0050] It should be noted that when the flow tube vibrates, the voltage waveform generated by the first pickup sensor 141 and the second pickup sensor 142 is a sine waveform. The generated sine wave indicates the movement of one flow tube relative to another flow tube. In the case that there is no fluid medium flowing in the flow tube (i.e., no fluid passes through the flow tube), the sine waves measured by the two pickup sensors are in phase, which means that the two flow tubes move synchronously. When the fluid medium flows through the pipe, the flow tube will generate a Coriolis force, which will cause the two flow tubes to twist towards each other, thereby causing the sine waveforms measured by the two pickup sensors to relatively phase shift. By analyzing the waveforms measured by the pickup sensors, the flow rate, density, viscosity and other measurement variables of the fluid medium can be obtained. It is easy to understand that the fluid medium can be a liquid or a gas.

[0051] As an optional implementation, the mass flow meter provided in the embodiment of the present application has the following technical features: the intermediate pipe section 11 of the flow pipe is a straight pipe, the inner elbow pipe section 12 of the flow pipe is an elbow pipe, and the ratio of the length of the intermediate pipe section 11 to the outer pipe diameter of the intermediate pipe section 11 is greater than 0 and less than or equal to 3.

[0052] For example, in the embodiment of the present application, the flow pipe is formed by bending a circular pipe, and the circular pipe can be made of metal or other materials. In the embodiment of the present application, the flow pipe retains an intermediate straight pipe section, and the circular pipe is bent at both ends of the intermediate pipe section 11 to form a first inner elbow pipe section and a second inner elbow pipe section. By retaining the intermediate straight pipe section, the inner elbow pipe section 12 can be processed in two parts, thereby reducing the stroke length of the single inner elbow pipe section 12, reducing the overall processing difficulty, ensuring the consistency of the sizes of the two inner elbow pipe sections 12, ensuring the symmetry of the flow pipe, and further ensuring the accuracy of the mass flow meter detection.

[0053] It should be noted that the purpose of the present application is to provide a high-precision and compact mass flow meter. It is easy to understand that when designing the pipe type of the flow pipe, the overall length of the flow pipe of the mass flow meter cannot be too long based on the design requirement of compactness.

[0054] In the embodiment of the present application, the ratio of the length of the intermediate pipe section 11 to the outer pipe diameter of the intermediate pipe section 11 satisfies the following condition: the ratio of the length of the intermediate pipe section 11 to the outer pipe diameter of the intermediate pipe section 11 is greater than 0 and less than or equal to 3.

[0055] The flow pipe designed in the embodiment of the present application has an intermediate straight pipe section, which can process the inner elbow pipe section 12 in two parts to reduce the processing difficulty and ensure the symmetry of the flow pipe. In addition, in the embodiment of the present application, the ratio of the length of the intermediate pipe section 11 to the outer pipe diameter of the intermediate pipe section 11 is less than or equal to 3. Through this design, sufficient design space can be reserved for the inner elbow pipe section 12, the curvature radius of the inner elbow pipe section 12 can be as large as possible under the premise of meeting the compactness requirement, which helps to reduce the turbulence intensity that may occur when the fluid flows through the flow pipe, thereby reducing the flow field noise and making the detection of the mass flow meter more accurate. In addition, the curvature radius of the inner elbow pipe section 12 can be as large as possible, which can avoid the deformation of the circular pipe into an oval shape during bending, thereby avoiding the increase in the pressure sensitivity of the inner elbow pipe section 12 due to the oval deformation and avoiding zero drift.

[0056] In order to further illustrate the mass flow meter provided in the embodiment of the present application, the present application also performs vibration stress analysis on the flow pipe with an intermediate straight pipe section provided in the embodiment of the present application, and compares the vibration stress analysis results of the U-shaped flow pipe without an intermediate straight pipe section in related designs. Specifically as follows:

[0057] As shown in FIG. 2, it shows a U-shaped flow pipe design schematic without an intermediate straight pipe section in the related art.

[0058] In the embodiments of the present application, a 32*1.5mm U-shaped tube is taken as the object of vibration stress analysis. The U-shaped flow tube is axisymmetric about an imaginary symmetry axis, and the U-shaped tube includes a central elbow portion (S1, S2) and straight tube portions located on both sides of the elbow portion. It is easy to understand that the central elbow portion (S1, S2) of the U-shaped flow tube is a sensitive part for density and flow measurement. The elbow portion of the U-shaped flow tube can be divided into two inner elbow segments with the imaginary symmetry axis of the U-shaped tube as the boundary. The present application performs vibration stress analysis on the U-shaped flow tube, and selects four measurement points in one of the inner elbow segments as shown in FIG. 2. Assuming that the vibration amplitude at the exciter is 100 microns, the amplitudes and stresses of the measurement points on the U-shaped flow tube are shown in Table 1.

[0059] Table 1

[0060] According to Table 1, there is the maximum amplitude and high level of stress near the excitation unit 13. According to the flow tube design provided in the embodiments of the present application, which retains the middle straight tube segment, the deformation of the flow tube into an oval shape near the excitation unit 13 due to the bending of the measurement tube can be avoided, and the increase in pressure sensitivity caused by irregular deformation of the flow tube due to ovality during the processing process can be avoided, and zero drift can be avoided.

[0061] As shown in FIG. 3, it shows a flow tube design schematic diagram provided in the embodiments of the present application which retains the middle straight tube segment. Based on the flow tube shown in FIG. 3, the embodiments of the present application perform vibration stress analysis, and use numerical simulation to calculate the pressure sensitivity, and obtain the sensitivity of the flowmeter vibration frequency affected by the pressure, as shown in Table 2.

[0062] Table 2

[0063] It should be noted that in the embodiments of the present application, the flow tube provided in the embodiments of the present application and the U-shaped flow tube for comparison have the same specification of the inner elbow segment 12 and maintain the same height and the overall length of the flowmeter, so as to exclude the interference of other factors. According to Table 2, it can be known that the flow tube design provided in the embodiments of the present application is obviously lower than the U-shaped tube design in the related art in terms of pressure sensitivity.

[0064] According to the above description, it can be known that the mass flowmeter using the flow tube design provided in the embodiments of the present application can effectively reduce the sensitivity of the vibration frequency of the mass flowmeter affected by the pressure, and avoid the occurrence of zero drift. In addition, since the density measurement of the mass flowmeter is an important process measurement parameter, and the density measurement is calculated based on the vibration frequency of the flowmeter, the flow tube design provided in the embodiments of the present application can reduce the sensitivity of the vibration frequency of the flowmeter affected by the pressure, and therefore has obvious advantages in the density measurement of the fluid.

[0065] Preferably, as an optional implementation manner, in the embodiment of the present application, the ratio of the length of the intermediate pipe section 11 to the outer diameter of the intermediate pipe section 11 satisfies the following condition: the ratio of the length of the intermediate pipe section 11 to the outer diameter of the intermediate pipe section 11 is greater than 1.5 and less than or equal to 3. Through this design, the intermediate pipe section 11 has sufficient length to facilitate clamping of the intermediate pipe section 11 during bending of the inner elbow pipe section 12, thereby reducing the processing difficulty of the flow pipe.

[0066] As an optional implementation manner, in the mass flow meter provided by the embodiment of the present application, the flow pipe further comprises a transition straight pipe section 15 and a transition elbow pipe section 16, one end of the transition straight pipe section 15 is smoothly connected with the inner elbow pipe section 12, the other end of the transition straight pipe section 15 is smoothly connected with one end of the transition elbow pipe section 16, and the other end of the transition elbow pipe section 16 is the outlet end or the inlet end of the flow pipe. The ratio of the curvature radius of the inner elbow pipe section 12 to the curvature radius of the transition elbow pipe section 16 is greater than or equal to 1.25.

[0067] Exemplarily, as shown in FIG. 4, the curvature radius R1 of the inner elbow pipe section 12 and the curvature radius R2 of the transition elbow pipe section 16 are shown. The ratio of the curvature radius R1 of the inner elbow pipe section 12 to the curvature radius R2 of the transition elbow pipe section 16 is greater than or equal to 1.25. Through this design, in the overall flow pipe, the curvature radius of the inner elbow pipe section 12 as the sensitive part of measurement is relatively large, and the curvature radius of the transition elbow pipe section 16 as the non-sensitive part is relatively small, thereby facilitating measurement under the premise that the overall size of the mass flow meter meets the compact design requirement.

[0068] In addition, in the embodiment of the present application, the ratio of the curvature radius of the inner elbow pipe section 12 to the curvature radius of the transition elbow pipe section is greater than or equal to 1.25. Under this design requirement, it can be ensured that the curvature radius of the inner elbow pipe section 12 as the sensitive part of measurement is as large as possible, thereby reducing the excessive turbulence intensity caused by the too small curvature radius of the inner elbow pipe section 12, or reducing the flow field noise in the turbulence state, so that the measurement result of the mass flow meter is more accurate. And it is easy to understand that ensuring the curvature radius of the inner elbow pipe section 12 to be large enough, the bending degree of the inner elbow pipe section 12 is small, thereby reducing the ovality of the inner elbow pipe section 12 after bending processing, reducing the pressure sensitivity of the flow pipe, and avoiding zero drift.

[0069] As an optional implementation manner, as shown in FIG. 5, in the embodiment of the present application, the transition straight pipe section and the intermediate pipe section are coupled through the inner elbow pipe section. Any transition straight pipe section has an imaginary axis, and the imaginary axis of the transition straight pipe section has a direction vector pointing to the coupled inner elbow pipe section. The intermediate pipe section has an imaginary axis, and the imaginary axis of the intermediate pipe section has a direction vector pointing to the coupled inner elbow pipe section. The included angle between the direction vector of the intermediate pipe section and the direction vector of the transition straight pipe section is defined as a first included angle, and the angle of the first included angle satisfies: the angle is greater than or equal to 90° and less than or equal to 105°.

[0070] As shown in FIG. 5, for the transition straight pipe section 15 close to the inlet end of the flow tube, the included angle between the direction vector of the intermediate pipe section and the direction vector of the transition straight pipe section is denoted as β. And for the transition straight pipe section 15 close to the outlet end of the flow tube, the included angle between the direction vector of the intermediate pipe section and the direction vector of the transition straight pipe section is denoted as α. The included angle β and the included angle α are equal in angle, satisfying the design requirement of axial symmetry of the flow tube.

[0071] Taking the first included angle β close to the inlet end of the flow tube as an example, the first included angle β satisfies the angle greater than or equal to 90° and less than or equal to 105°. Through this design, as shown in FIG. 5, in the case that the axial direction of the intermediate pipe section 11 of the flow tube tends to be horizontal, the axial direction of the transition straight pipe section 15 can be kept in a state tending to be vertical, so that the flow tube can realize self-emptying.

[0072] Further, as an optional implementation manner, the angle of the first included angle satisfies: the angle is greater than or equal to 95° and less than or equal to 105°.

[0073] As shown in FIG. 6, which shows a schematic diagram of the mass flowmeter in a flag installation application provided by the embodiment. In the application scenario of flag installation, the axial direction of the intermediate straight pipe section tends to be vertical. At this time, based on the design requirement that the first included angle is greater than or equal to 95°, the transition straight pipe section 15 can still keep a certain included angle with the horizontal direction, so as to meet the requirement of self-emptying.

[0074] According to the above description, the angle of the first included angle satisfies: the angle is greater than or equal to 95° and less than or equal to 105°. Through this design, the mass flowmeter can adapt to the self-emptying requirement in the two application scenarios of horizontal installation and flag installation, and widen the application scenarios of the mass flowmeter.

[0075] For ease of description, in the embodiment, a first straight line is defined, the first straight line coincides with the axis of the intermediate pipe section 11, a second straight line is defined, the second straight line is parallel to the first straight line, and the second straight line passes through the center of the opening end of the transition elbow section 16.

[0076] As shown in FIG. 7, as an optional implementation manner, the opening direction of the transition elbow section 16 is parallel to the axial direction of the intermediate pipe section 11. The ratio of the distance between the first straight line and the second straight line (i.e. the C-C distance shown in FIG. 7) to the outer pipe diameter of the flow tube is less than or equal to 12. Through this design, the overall height of the mass flowmeter can be small, satisfying the design requirement of compactness.

[0077] As an optional implementation, the bending angle of the inner elbow pipe section 12 is equal to the bending angle of the transition elbow pipe section 16. The bending angle of the elbow pipe refers to the smallest positive angle formed by the intersection of the two end faces of the elbow pipe. The bending angle of the inner elbow pipe section 12 is equal to the bending angle of the transition elbow pipe section 16, so that the transition straight pipe section 15 can be tangent to the inner elbow pipe section 12 and the transition elbow pipe section 16 at the same time, ensuring the stability of the fluid flow.

[0078] As an optional implementation, the mass flow meter provided by the embodiment of the present application further includes a processing module (not shown in the figure), which is configured to send an excitation signal to the excitation unit 13 to make the flow pipe vibrate at the resonance frequency, and receive and process the vibration signal transmitted by the vibration sensing unit 14, the vibration signal being used to characterize the vibration of the flow pipe.

[0079] The processing module generates at least a mass flow measurement value based on the vibration signal, the mass flow measurement value representing the instantaneous mass flow rate of the measured fluid flowing through the mass flow meter.

[0080] As an optional implementation, the processing module further generates a density measurement value based on the vibration signal, the density measurement value representing the instantaneous density of the measured fluid flowing through the mass flow meter.

[0081] According to the above description, the embodiment of the present application provides a compact mass flow meter, the vibration frequency of which is less sensitive to pressure, and the detection is more accurate.

[0082] As shown in FIG. 8, the present application provides a mass flow meter, which includes two or more flow pipes, the structure of the flow pipe is the same as the above-mentioned flow pipe structure, any flow pipe is axisymmetric about an imaginary symmetry axis 101, and includes a middle pipe section passing through the imaginary symmetry axis 101; an inner elbow pipe section located at both ends of the middle pipe section, the middle pipe section and the inner elbow pipe section being smoothly connected; a transition straight pipe section smoothly connected to one end of the inner elbow pipe section; and a transition elbow pipe section smoothly connected to the other end of the transition straight pipe section. The middle pipe section of the flow pipe is a straight pipe, according to the foregoing, a first straight line is defined, and the first straight line coincides with the axis of the middle pipe section.

[0083] As shown in FIG. 8, the mass flow meter further includes a coupling sheet, and the two flow pipes are coupled through the coupling sheet. A first coupling sheet 17 is fixedly connected to the transition straight pipe section, a first intersection point is defined, the first intersection point is the intersection point of the extension direction of the imaginary axis of the transition straight pipe section and the extension direction of the first coupling sheet 17, the distance from the first intersection point to the first straight line is defined as a first distance, and the ratio of the first distance to the outer pipe diameter of the middle pipe section is greater than or equal to 4 and less than or equal to 12.

[0084] Specifically, the coupling sheet can be fixedly connected with the transition straight pipe section of the flow tube in a welding manner. As shown in FIG. 8, the extension direction of the coupling sheet and the extension direction of the imaginary axis of the transition straight pipe section are shown. The intersection of the extension direction of the imaginary axis of the transition straight pipe section and the extension direction of the first coupling sheet 17 is defined as a first intersection point. As shown in FIG. 8, the distance from the first intersection point to the first straight line is a first distance, which is denoted as H1. In the embodiment of the present application, the ratio of the first distance H1 to the outer diameter of the intermediate pipe section is greater than or equal to 4 and less than or equal to 12, thereby controlling the vibration frequency of the flow tube within a reasonable range.

[0085] It should be noted that if the ratio between the first distance H1 and the outer diameter of the intermediate pipe section is too high, the vibration frequency of the flow tube is too small, which is easily disturbed by other frequencies. If the ratio is too small, the vibration frequency of the flow tube is too large, which is not conducive to accurately detecting the phase difference on both sides of the flow tube. In the present application, the ratio of the first distance to the outer diameter of the intermediate pipe section is configured to satisfy: greater than or equal to 4 and less than or equal to 12, thereby controlling the vibration frequency of the flow tube within a reasonable range.

[0086] Further, as shown in FIG. 8, as an optional implementation manner, the opening direction of the transition elbow section is parallel to the axial direction of the intermediate pipe section 11. The distance (i.e., the H0 distance shown in FIG. 8) between the first straight line (coinciding with the axis of the intermediate pipe section) and the second straight line (parallel to the first straight line, and the second straight line passes through the center of the opening end of the transition elbow section) is less than or equal to 12 times the outer diameter of the flow tube. Through this design, the overall height of the mass flow meter can be made smaller, meeting the design requirements of compactness.

[0087] As shown in FIG. 9, as an optional implementation manner, the included angle between the extension direction of the first coupling sheet 17 and the imaginary symmetry axis 101 of the flow tube is defined as a second included angle, denoted as ∠B. The angle of the second included angle ∠B satisfies: the angle is greater than or equal to 75° and less than or equal to 85°. Through the design of the installation angle of the first coupling sheet 17, the vibration frequency of the flow tube can be controlled within a reasonable range.

[0088] As shown in FIG. 10, the mass flow meter further comprises a second coupling sheet 18, which is fixedly connected with the transition elbow section;

[0089] The included angle between the extension direction of the second coupling sheet 18 and the imaginary symmetry axis 101 of the flow tube is defined as a third included angle, denoted as ∠C. The angle of the third included angle ∠C satisfies: the angle is greater than or equal to 25° and less than or equal to 35°. Through the design of the installation angle of the second coupling sheet 18, the vibration energy of the flow tube can be reduced to be transmitted to the base shell, the energy loss can be reduced, and the external vibration can be reduced to be transmitted from the base shell to the flow tube, reducing the interference of the outside to the measuring tube.

[0090] According to FIG. 10, the mass flow meter provided by the application is provided with at least two coupling pieces on one side of the imaginary symmetry axis 101 of the flow tube, the number of the coupling pieces on both sides of the imaginary symmetry axis 101 of the flow tube is the same, and the coupling pieces are substantially symmetrically distributed. In other words, at least a first coupling piece 17 and a second coupling piece 18 are provided on one side of the imaginary symmetry axis 101 of the flow tube.

[0091] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example.

[0092] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A mass flow meter, comprising: at least one flow tube, any of the flow tubes being axisymmetric about an imaginary axis of symmetry, the flow tube comprising a middle tube section passing through the imaginary axis of symmetry and inner elbow sections located at both ends of the middle tube section, the middle tube section being smoothly connected with the inner elbow sections; an excitation unit, the excitation unit being arranged at the middle tube section, for driving the flow tube to vibrate; a vibration sensing unit, comprising pick-up sensors symmetrically arranged at both sides of the excitation unit, the pick-up sensors being used for acquiring vibration of the flow tube; characterized in that the middle tube section of the flow tube is a straight tube, the inner elbow sections of the flow tube are elbow tubes, and a ratio of a length of the middle tube section to an outer tube diameter of the middle tube section is greater than 0 and less than or equal to 3. 2.The mass flow meter according to claim 1, characterized in that the ratio of the length of the middle tube section to the outer tube diameter of the middle tube section is greater than or equal to 1.

5. 3.The mass flow meter according to claim 1, characterized in that the flow tube further comprises transition straight tube sections and a transition elbow section, one end of the transition straight tube section is smoothly connected with the inner elbow section, the other end of the transition straight tube section is smoothly connected with one end of the transition elbow section, and the other end of the transition elbow section serves as an outlet end or an inlet end of the flow tube; a ratio of a curvature radius of the inner elbow section to a curvature radius of the transition elbow section is greater than or equal to 1.

25. 4.The mass flow meter according to claim 3, characterized in that the transition straight tube sections and the middle tube section are coupled through the inner elbow section, any of the transition straight tube sections has an imaginary axis, the imaginary axis of the transition straight tube section has a direction vector pointing to the coupled inner elbow section; the middle tube section has an imaginary axis, the imaginary axis of the middle tube section has a direction vector pointing to the coupled inner elbow section; an included angle between the direction vector of the middle tube section and the direction vector of the transition straight tube section is defined as a first included angle, and an angle of the first included angle satisfies: the angle is greater than or equal to 90° and less than or equal to 105°. 5.The mass flow meter according to claim 4, characterized in that the angle of the first included angle is greater than or equal to 95°. 6.The mass flow meter according to claim 3, characterized in that an opening direction of the transition elbow section is parallel to an axial direction of the middle tube section; a first straight line is defined, the first straight line coincides with an axis of the middle tube section, a second straight line is defined, the second straight line is parallel to the first straight line, and the second straight line passes through a center of an opening end of the transition elbow section; a ratio of a distance between the first straight line and the second straight line to an outer tube diameter of the flow tube is less than or equal to 12. 7.The mass flow meter according to claim 3, characterized in that a bending angle of the inner elbow section is equal to a bending angle of the transition elbow section. 8.The mass flow meter according to claim 1, characterized in that The mass flow meter further comprises a processing module configured to send an excitation signal to the excitation unit to cause the flow tube to vibrate at the resonance frequency, and receive and process a vibration signal transmitted by the vibration sensing unit, the vibration signal being indicative of the vibration of the flow tube. The processing module is further configured to generate a density measurement based on the vibration signal, the density measurement being indicative of the instantaneous density of the measured fluid flowing through the mass flow meter.

9. The mass flow meter of claim 8, wherein The processing module is further configured to generate a density measurement based on the vibration signal, the density measurement being indicative of the instantaneous density of the measured fluid flowing through the mass flow meter.

10. The mass flow meter of claim 1, wherein The mass flow meter comprises two or more flow tubes, all of the flow tubes having inlet ends configured to be connected to an inlet flow divider and outlet ends configured to be connected to an outlet flow divider, the measured fluid being equally distributed into each of the flow tubes through the inlet flow divider and being equally distributed out of the flow tubes through the outlet flow divider, all of the flow tubes having substantially identical configurations, and the flow tubes being formed by bending a metal circular tube.

11. The mass flow meter of any of claims 3-7, wherein, The mass flow meter comprises two or more flow tubes, and a first straight line is defined, the first straight line being coincident with the axis of the intermediate tube segment. The mass flow meter further comprises a coupling piece, the two or more flow tubes being coupled by the coupling piece, wherein the coupling piece comprises a first coupling piece, the first coupling piece being fixedly connected to the transition straight tube segment, a first intersection point is defined, the first intersection point being an intersection of an extension direction of the imaginary axis of the transition straight tube segment and an extension direction of the first coupling piece, a first distance is defined from the first intersection point to the first straight line, the ratio of the first distance to the outer tube diameter of the intermediate tube segment being greater than or equal to 4 and less than or equal to 12.

12. The mass flow meter of claim 11, wherein, A second angle is defined between the extension direction of the first coupling piece and the imaginary symmetry axis of the flow tube, the second angle being greater than or equal to 75° and less than or equal to 85°.

13. The mass flow meter of claim 11, wherein The mass flow meter further comprises a second coupling piece, the second coupling piece being fixedly connected to the transition elbow tube segment. A third angle is defined between the extension direction of the second coupling piece and the imaginary symmetry axis of the flow tube, the third angle being greater than or equal to 25° and less than or equal to 35°.

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