Vibration measurement recorder for measuring mass flow rate of flowable medium

Abstract

A vibratory measurement recorder (100) for measuring a mass flow rate, comprising: a line inlet portion (18); a vibratable S-shaped measuring line (10) for conducting the medium, having a dual rotational symmetry with respect to an axis running perpendicular to the plane of the measuring line; a line exit portion (19); at least one vibration exciter (53) for exciting a flexural vibration of the measuring line (10) in a flexural vibration mode of operation; at least two vibration sensors for detecting vibrations of the measurement line; a support body (30); an inlet-side bearing body (21) and an outlet-side bearing body (22); wherein the measuring line (10) is fixedly connected to the support body (30) by means of the bearing body and is delimited by the bearing body; wherein the measuring line (10) adjoins the line inlet portion and the line outlet portion; wherein the measuring line (10) has two vibration nodes spaced apart from the bearing body in an F3 flexural vibration mode of operation; wherein two damper mass bodies (56, 58) are attached to the measurement pipeline (10), each having a center of gravity that does not exceed half of the outer diameter of the measurement pipeline (10) from a position where the closest vibration node is positioned when the measurement pipeline is filled with water.

Description

Technical Field

[0001] The present invention relates to a vibration measurement recorder for measuring the mass flow rate of a flowable medium, particularly a measurement recorder having an S-shaped profile. Background Technology

[0002] This type of measurement recorder includes: a line inlet section; a vibratory measuring line for guiding the medium, wherein the measuring line is bent in its rest position in the plane of the measuring line, wherein the measuring line has a substantially S-shaped profile with double rotational symmetry relative to an axis extending perpendicularly to the plane of the measuring line; a line outlet section; at least one vibration exciter for exciting the bending vibration of the measuring line in a bending vibration operating mode; at least two vibration sensors for detecting the vibration of the measuring line; a support body; an inlet-side bearing body and an outlet-side bearing body; wherein the measuring line is fixedly connected to the support body by means of the inlet-side bearing body and by means of the outlet-side bearing body, and the measuring line is defined by the bearing body; wherein the measuring line is connected to the line inlet section on the inlet side and the line outlet section on the outlet side, and is capable of being connected to the line via the outlet section; wherein the measuring line in the bending vibration operating mode—which is the F3 bending vibration mode—has two vibration nodes spaced apart from the bearing body. The designation F3 indicates that this bending vibration mode typically has the third lowest natural frequency of the bending vibration mode of the measuring line.

[0003] This type of measurement recorder is disclosed, for example, in European patents EP 0518124 B1, EP 3631379 B1, and EP3631378 B1. This type of measurement recorder is designed such that interfering vibrations from the surrounding environment are coupled into the measurement pipeline via its components, and the dissipation of vibration energy from the measurement pipeline into its surrounding environment is minimized via the components of the measurement recorder. However, further research on this type of measurement recorder has shown that sound waves propagating through the medium into the measurement pipeline affect the vibration behavior of the pipeline, and thus cause zero-point errors in flow measurement. Therefore, the object of the present invention is to find a remedy. Summary of the Invention

[0004] According to the present invention, this objective is achieved by a measurement recorder according to independent claim 1.

[0005] A vibration measurement recorder for measuring the mass flow rate of a flowable medium according to the present invention comprises: a line inlet portion; a vibratory measuring line for guiding the medium, wherein the measuring line is bent in its rest position in the plane of the measuring line, wherein the measuring line has a substantially S-shaped profile having double rotational symmetry about an axis perpendicular to the plane of the measuring line; a line outlet portion; at least one vibration exciter for exciting bending vibration of the measuring line in a bending vibration operating mode; at least two vibration sensors for detecting vibration of the measuring line; a support body; an inlet-side bearing body and an outlet-side bearing body; wherein the measuring line is fixedly connected to and defined by the bearing body on the inlet side and on the outlet side by means of the bearing body; wherein the measuring line is connected to the line inlet portion on the inlet side and to the line outlet portion on the outlet side and is connectable to the line via the outlet portion; wherein, in the bending vibration mode as F3... The measuring pipeline in the bending vibration operating mode has two vibration nodes spaced apart from the bearing body; wherein, the measuring recorder according to the invention further includes two damper mass bodies attached to the measuring pipeline, wherein each damper mass body has a center of gravity no more than twice the outer diameter of the measuring pipeline, for example no more than one outer diameter of the measuring pipeline, and particularly no more than half the outer diameter of the measuring pipeline, at a distance from the location where the vibration node closest to the bending vibration operating mode is located when the measuring pipeline is filled with water, wherein, in the case of acoustic coupling via the medium, a zero-point error drift is caused, wherein the zero-point error drift has a maximum value depending on the sound frequency, wherein the amplitude of the frequency-dependent maximum value of the zero-point error drift caused by the damper mass bodies (56, 58) is less than 50% of the amplitude of the frequency-dependent maximum value of the zero-point error drift of a reference measuring recorder that is identical in design except for the damper mass bodies, wherein the reference measuring recorder does not have any damper mass bodies. The reference measuring recorder corresponds to the prior art, and the present invention is based on this reference measuring recorder.

[0006] The damper mass body is used to suppress interfering vibrations introduced into the measuring pipeline, eliminating them at the location of the vibration node and thus suppressing them to a large extent.

[0007] In a further development of the invention, each damper mass body has a principal axis of inertia formed at an angle not exceeding 15°, for example, not exceeding 10° and particularly not exceeding 5°, to the direction vector of the bending of the measuring pipeline in the cross-section of the measuring pipeline passing through the center of gravity of the damper mass body, and extending particularly parallel to the direction vector. In one embodiment of this further development of the invention, the principal axis of inertia is, in every case, the maximum principal axis of inertia.

[0008] In a further development of the invention, each of the two damper mass bodies has an extension in the direction of the direction vector of the bending of the measuring pipeline not exceeding four times the diameter of the measuring pipeline, for example, not exceeding two times the diameter of the measuring pipeline.

[0009] In a further development of the invention, the center of gravity of each mass body of the damper is bent from the measuring pipeline by no more than one-tenth of the outer radius of the measuring pipeline.

[0010] In a further development of the invention, each of the two damper mass bodies has a mass not less than eight times, and particularly not less than twelve times, the mass of the portion of the measuring pipeline having the diameter of the measuring pipeline.

[0011] In a further development of the invention, the two damper mass bodies are arranged according to double rotational symmetry.

[0012] In a further development of the invention, compared with the reference natural frequency of the bending vibration operating mode of the measuring line without damper mass bodies, the natural frequency of the bending vibration operating mode in the air-filled measuring line with two damper mass bodies will be reduced by no more than 4%, and particularly no more than 2%, by 0.1 MPa pressure and 300 K temperature.

[0013] In a further development of the invention, for a temperature of 300 K, a pressure of 0.1 MPa, and and The position L of the vibration node is changed by altering the density of the medium. K The following formula applies to the displacement along the bend of the measuring pipeline.

[0014] , In particular, , Where, d a It measures the outer diameter of the pipeline.

[0015] In a further development of the invention, the line inlet and line outlet portions have substantially the same line cross-section as the measuring line, particularly the same line material as the measuring line, and are preferably manufactured integrally with the measuring line.

[0016] In further development, the measuring pipeline has an outer diameter of no more than 20 mm, and in particular no more than 10 mm.

[0017] In a further development of the invention, the measuring tube has an outer diameter of no more than 0.5 mm, particularly no more than 1.0 mm.

[0018] In further development, when the measuring pipeline is filled with water, the bending vibration operating mode corresponding to the second symmetrical bending vibration mode exhibits a natural frequency of not less than 100 Hz, and in particular not less than 400 Hz.

[0019] In a further development, when the measuring pipeline is filled with water, the bending vibration operating mode corresponding to the second symmetrical bending vibration mode has a natural frequency of no more than 1200 Hz, and in particular no more than 900 Hz.

[0020] In a further development of the invention, the support body has a support plate that extends substantially parallel to the plane of the measuring pipeline. Attached Figure Description

[0021] The present invention will now be described in more detail based on the exemplary embodiments shown in the figures. Wherein: Figure 1a This is a top view of an exemplary embodiment of the measurement recorder according to the present invention; Figure 1b This is a spatial view of the damper mass body mounted on a measurement pipeline according to an exemplary embodiment of the measurement recorder according to the present invention; Figure 1c A longitudinal section is shown of a damper mass body mounted on a measurement pipeline according to an exemplary embodiment of a measurement recorder based on the invention. Figure 1d A cross-sectional view is shown of a damper mass body mounted on a measurement pipeline according to an exemplary embodiment of a measurement recorder based on the invention. Figure 1e A cross-sectional view is shown of an alternative damper mass body mounted on a measurement pipeline according to an exemplary embodiment of a measurement recorder based on the invention; and Figure 2 Data on zero-point error drift due to acoustic coupling and associated damping are shown for a measurement recorder according to the prior art and a measurement recorder according to the present invention. Detailed Implementation

[0022] The measurement recorder 100 shown in Figure 1 includes a measurement line 10 having a first straight outer portion 11, a second straight outer portion 12, and a central straight portion 13, as well as a first curved portion 15 and a second curved portion 16. The two straight outer portions 11 and 12 are each connected to the central straight portion 13 by means of one of the curved portions 15 and 16. The measurement line 10 is defined by two bearing bodies 21 and 22 and attached to a rigid support plate 30. The measurement line 10 extends substantially in a line plane parallel to the support plate 30. The measurement line has double rotational symmetry about an axis of symmetry that extends perpendicularly to the line plane through a point C2 at the center of the central tube portion. The measurement line has an inner diameter of, for example, 5 mm or less. It is made of metal, particularly stainless steel or titanium. The metal support plate 30 has a thickness of, for example, 5 mm. The support plate 30 has four helical spring-loaded bearings 31, 32, 33, and 34, which are specifically laser-cut and also possess double rotational symmetry relative to each other with respect to an axis of symmetry passing through point C2. The support plate 30 is anchored to the housing plate 40 of the measuring recorder housing by bearing bolts (not shown here), which are fixed at the center of the spring-loaded bearings. The effective stiffness of the spring-loaded bearings is generated by the length of the helical cut and its width relative to the width of the remaining material of the support plate 30. At the center, each spring-loaded bearing has a hole (not shown) in its housing for receiving a bearing pin. With the aid of the spring-loaded bearings 31, 32, 33, and 34, the support plate 30 has three translational vibration degrees of freedom and three rotational vibration degrees of freedom, with a natural frequency of at least 70 Hz to avoid resonant vibrations, where vibrations up to 50 Hz frequently occur in process plants. To avoid compromising the soft suspension of the support plate achieved by the spring-loaded bearings 31, 32, 33, and 34, the measuring line can be connected via a sufficiently soft line inlet portion 18 and a sufficiently soft line outlet portion 19. The housing has a first housing bearing 41 and a second housing bearing 42, which are fixedly connected to the housing plate 40. The line inlet portion 18 and the line outlet portion 19 are also fixed to the housing plate 40 to suppress the transmission of vibrations from the line to the measuring line via the line inlet portion 18 and the line outlet portion 19. The translational and rotational vibration degrees of freedom of the support plate 30 both have a natural frequency f. i The natural frequency f i With including benchmark k i and inertia term m i The quotient is proportional to the root, that is, f i (k i / m i ) 1 / 2 In summary, the line entry section 18 and the line exit section correspond to the relevant reference k. iThe contribution does not exceed 10%. Figure 1a In the diagram, the line inlet section 18 and line outlet sections 18, 19 are shown schematically. They can have reduced stiffness by using additional pipeline length and bending, thereby reducing their contribution to the corresponding reference. Figure 1a As further shown, the measurement recorder 100 for detecting vibrations of the measurement pipeline 10 has a first electrodynamic vibration sensor 51 and a second electrodynamic vibration sensor 52, each having a magnet on the measurement pipeline 10 and a coil on the support plate 30. In this case, the two vibration sensors 51, 52 are each arranged on one of the two straight outer portions 11, 12, without exceeding the radius of curvature of the curved portions 15, 16 from the adjacent curved portions. To excite the bending vibrations, the measurement recorder has an electrodynamic exciter 53, which is arranged at the center C2 of the double rotational symmetry and acts in the direction of the axis of symmetry. The electrodynamic exciter 53 includes a magnet on the measurement pipeline 10 and an excitation coil on the support plate 30.

[0023] Center C2 is the origin of the coordinate system used to describe the advantageous aspects of the measurement recorder according to the invention. The measurement pipeline lies in the xz plane, where the y-axis extends parallel to the angle bisectors w1 and w2, which each extend between the pipeline axis of the straight outer sections 11 and 12 and the pipeline axis of the central straight section 13. The z-axis extends perpendicular to the y-axis in the pipeline plane and defines the longitudinal axis of the measurement recorder 100. If this longitudinal axis is arranged vertically, the measurement recorder can be optimally discharged. The inclination of the straight section is then equal to half the angle between the pipeline axis of the straight outer sections 11 and 12 and the pipeline axis of the central straight section 13. In this exemplary embodiment of the invention, this inclination is 7°.

[0024] The measuring line 10 has a preferred symmetrical bending vibration operating mode, wherein two vibration nodes are located between bearing bodies 21 and 22. The natural frequency of this bending vibration operating mode is higher than that of the basic symmetrical bending vibration mode without vibration nodes; however, unlike the basic bending vibration mode, the center of gravity of the measuring line 10 has a lower vibration amplitude with respect to the same deflection of the exciter, thus dissipating less vibrational energy in the bending vibration operating mode. Together with the previously described mounting of the support plate 30 in the spring bearing and the associated frequency interval between the bending vibration operating mode and the vibration of the support plate, the measuring recorder 100 is well protected against unwanted mechanical coupling to the vibrations of structural elements via the measuring recorder.

[0025] The measurement recorder according to the invention is further characterized in that two damper mass bodies 56, 58 are attached to the measurement line 10, each of which ideally corresponds in weight to one of the vibration nodes in a symmetrical bending vibration operating mode. The damper mass bodies 56, 58 are identical in design and can include, for example, a perforated circular plate, such as... Figure 1b , Figure 1c and Figure 1d An example of one of the damper mass bodies 58 is shown. The damper mass bodies 56, 58 are fixed to their positions on the measuring line, for example, by brazing. A circular plate shape is obviously a simple shape that allows for symmetrical mounting of the damper mass bodies (56, 58). However, other shapes of the damper mass bodies (56, 58) may be advantageous if a more compact design is desired, as is evident from the exemplary embodiment shown in Figure 1. The damper mass body 58 "has a rectangular basic shape," whereby the extent of the rectangle perpendicular to the plane of the measuring line 10 is "significantly smaller than the extent of the rectangle parallel to the plane of the measuring line 10." In this way, the distance between the measuring line 10 "and the support body 30" can be significantly reduced. To minimize the vibration behavior of the measuring line, the damper mass bodies 56, 58 are mounted such that their centers of gravity coincide with the bending of the measuring line at the location of the vibration node. Furthermore, the maximum principal axis of inertia of the damper mass body should deviate as little as possible from the direction vector of the bending of the measuring line at the relevant vibration node.

[0026] Within the range of the damper mass bodies 56 and 58 acting at the vibration nodes of the bending vibration operating mode, they have almost no effect on their vibration characteristics. In particular, these masses cause a reduction of less than 2% in the natural frequency of the bending vibration operating mode at most. This means that the dynamic characteristics measured by density are almost unaffected by the damper mass bodies.

[0027] The following is for reference. Figure 2 To explain one effect of the damper mass body. Figure 2The data in this experiment comes from an experiment in which the measuring line is filled with a fixed liquid and excited at its natural frequency in a bending vibration operating mode—in this case, a second symmetrical bending vibration mode. In this case, zero flow measurement is desired. In this case, the flow measurement with zero deviation corresponds to a zero-point error N, which should be minimal and, in particular, constant for a given flow rate. However, in this case, an acoustic signal is coupled into the measuring line via the liquid, which interacts with the vibration of the measuring line in the bending vibration operating mode in a frequency-dependent manner, and causes a drift in itself, specifically manifested as a zero-point error drift N. In the experiment, the amplitude AN of the zero-point error drift N is maximized by changing the acoustic frequency. The figure shows a smoothed curve N1-max of the maximum zero-point drift for a measurement recorder according to the prior art and a smoothed curve N2-max of the maximum zero-point drift for a measurement recorder according to the invention. For clarity, the curves are shifted vertically relative to each other, but they are all on the same scale. It is quite evident that the amplitude AN2-max of the maximum zero-point error drift N2-max of the measurement recorder according to the present invention is significantly reduced compared to the amplitude AN1-max of the maximum zero-point error drift N1-max of the measurement recorder according to the prior art. Figure 2 The associated damping curves D1 and D2 are also shown, wherein the damping of the bending vibration operating mode has a drift similar to the drift of the zero-point error, and wherein the amplitude of damping D2 in the case of the measurement recorder according to the invention is significantly reduced compared with the amplitude of damping D1 according to the prior art.

Claims

1. A vibratory flowmeter (100) for measuring the mass flow of a flowable medium, comprising: a line inlet portion (18); a vibratable measurement line (10) for conducting the medium, wherein the measurement line (10) is curved in its rest position in a measurement line plane, wherein the measurement line (10) has a substantially S-shaped profile with a double rotational symmetry with respect to an axis extending perpendicular to the measurement line plane; a line outlet portion (19); at least one vibration exciter (53) for exciting a bending vibration of the measurement line (10) in a bending vibration operating mode; at least two vibration sensors for detecting a vibration of the measurement pipe; a support body (30); an inlet-side bearing body (21) and an outlet-side bearing body (22); wherein the measurement line (10) is fixedly connected to the support body (30) on the inlet side by means of the bearing body (21) and on the outlet side by means of the bearing body (22), and is delimited by the bearing bodies; wherein the measurement line (10) is connected on the inlet side to the line inlet portion (18) and on the outlet side to the line outlet portion (19), and can be connected to a line via the latter; wherein the measurement line (10) in the bending vibration operating mode as F3 bending vibration mode has two vibration nodes spaced apart from the bearing bodies; characterized in that: the measurement recorder further comprises two damper mass bodies (56, 58) attached to the measurement line (10), wherein the damper mass bodies (56, 58) each have a center of gravity which is located no more than two times the outer diameter of the measurement line, for example no more than one times the outer diameter of the measurement line (10), and in particular no more than half the outer diameter of the measurement line (10), from the position of the closest vibration node of the bending vibration operating mode when the measurement line is filled with water, wherein, in the case of acoustic coupling via the medium, a zero point error drift is caused, wherein the zero point error drift has a frequency-dependent maximum value, wherein the damper mass bodies (56, 58) cause an amplitude of the frequency-dependent maximum value of the zero point error drift which is less than 50% of the amplitude of the frequency-dependent maximum value of the zero point error drift of a reference measurement recorder which is identical in design except for the damper mass bodies, wherein the reference measurement recorder has no damper mass bodies.

2. The vibrational measurement logger (100) of claim 1, wherein, the damper mass bodies each have a main axis of inertia which forms an angle of no more than 15°, for example no more than 10° and in particular no more than 5°, with a direction vector of the measurement line bend in a measurement line cross section through the center of gravity of the damper mass body, and in particular extends parallel to the direction vector.

3. The vibrational measurement logger (100) of claim 2, wherein, The two damper mass bodies each have a mass not less than eight times, in particular not less than twelve times, the mass of the section of the measuring line (10) having the length of the measuring line diameter.

4. The vibrational measurement logger (100) according to any one of claims 2-3, wherein, The two damper mass bodies each have a mass not less than eight times, in particular not less than twelve times, the mass of the section of the measuring line (10) having the length of the measuring line diameter.

5. The vibrational measurement logger (100) according to any one of claims 2-4, wherein, The two damper mass bodies each have a mass not less than eight times, in particular not less than twelve times, the mass of the section of the measuring line (10) having the length of the measuring line diameter.

6. The vibrational measurement logger (100) according to any of the preceding claims, wherein The two damper mass bodies each have a mass not less than eight times, in particular not less than twelve times, the mass of the section of the measuring line (10) having the length of the measuring line diameter.

7. The vibrational measurement logger (100) according to any of the preceding claims, wherein The two damper mass bodies are arranged according to double rotational symmetry.

8. The vibrational measurement logger (100) according to any of the preceding claims, wherein The natural frequency of the bending vibration operating mode in the measuring line filled with air at a pressure of 0.1 MPa and a temperature of 300 K is reduced by the two damper mass bodies by not more than 4%, in particular not more than 2%, compared to the reference natural frequency of the bending vibration operating mode of the measuring line (10) without damper mass bodies.

9. The vibrational measurement logger (100) according to any of the preceding claims, wherein, For the change of the position L of the node of the vibration of the density of the medium in the reference conditions by changing the temperature of the medium K The displacement of the bend along the measuring line, the following formula applies: ， In particular, ， where d a is the outer diameter of the measurement line.

10. The vibrational measurement logger (100) according to any of the preceding claims, wherein, The line inlet portion and the line outlet portion have substantially the same pipe cross section as the measuring line, in particular the same pipe material as the measuring line, and are preferably manufactured integrally with the measuring line (10).

11. The vibrational measurement logger (100) according to any of the preceding claims, wherein The support body has a support plate which extends substantially parallel to the measuring line plane.

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