Measurement assembly for determining properties of multiphase flowable medium

Abstract

The invention relates to a measuring arrangement (1) for determining a property of a multiphase flowable medium, comprising:-a measuring tube (2) for conveying the medium, the measuring tube (2) having a first antenna socket (3),-a first microwave antenna arrangement (5) arranged in the first antenna socket (3), wherein the first microwave antenna arrangement (5) is designed to emit a first microwave signal (A) and a second microwave signal (B), the first microwave signal (A) having a first main radiation direction and the second microwave signal (B) having a second main radiation direction different from the first main radiation direction; and-a measurement circuit (9), where the measurement circuit (9) is connected to the first microwave antenna arrangement (5), where the measurement circuit (9) has a high frequency generator for providing a first microwave signal (A) and a second microwave signal (B) to the first microwave antenna arrangement (5), where the measurement circuit (9) is configured to determine a property of the medium based at least on the measured first microwave signal (# imgabs0 #), wherein the measurement circuit (9) is configured to detect non-uniformities in the measurement tube (2) on the basis of the measured first microwave signal (# imgabs1 #) and the measured second microwave signal (# imgabs2 #).

Description

Technical Field

[0001] The present invention relates to a measuring assembly for determining the properties of a multiphase flowable medium by means of a microwave antenna device. Background Art

[0002] By means of microwaves, physical quantities such as the dielectric constant and loss factor of a medium in a production line can be determined. From these two variables - measured at one or more different frequencies - conclusions can be drawn about specific application parameters, such as the proportion of water in a mixture of water and other non-polar or weakly polar components, or the solid content in a liquid medium.

[0003] The established transmission / reflection measurement is described in "Microwave Electronics, Measurements, and Material Characterization" by L.F. Chen, C.K. Ong, C.P. Neo, V.V. Varadan, V.K. Varadan, John Wiley & Sons Ltd., 2004. For this purpose, microwave signals are docked at two different positions on the medium in a container or measuring tube, the scattering parameters (transmission and optionally reflection) are measured between these interface structures, and the physical properties of the medium are calculated based on the measured scattering parameters.

[0004] WO 2018 / 121927 A1 teaches a measuring assembly for analyzing the properties of a flowing medium by means of microwaves. In addition to the microwave antennas, the measuring assembly has an electrically insulating lining layer on the inner peripheral surface of the measuring tube. This lining layer forms a dielectric waveguide through which at least a part of a microwave signal can propagate from a first microwave antenna to a second microwave antenna. One application of such a measuring assembly is to determine the proportion of solids in the conveyed liquid medium. WO2021 / 099152A1 teaches a microwave antenna having a front section in contact with the medium, and an excitation signal is emitted into the medium via this front section.

[0005] The process in which solid components are present in the medium is affected by the deposition and sedimentation of solids on the inner wall of the measuring tube. WO 2016 / 075367 A1 discloses a method for detecting deposition on the microwave antennas used in contact with the medium. For this purpose, in addition to the traditional two opposite microwave antennas, at least one additional microwave antenna is used, which is arranged on the measuring tube in such a way as to produce two measurement paths of different lengths. The presence of the coating is determined based on the time (flight time) between the emission and reception of microwave signals of the two measurement paths. The disadvantage of this solution is that at least one third microwave antenna is required. Summary of the Invention

[0006] The object of the present invention is to provide an alternative solution.

[0007] This object is achieved by a measurement assembly according to claim 1 and a method according to claim 16.

[0008] A measurement assembly for determining the properties of a multiphase flowable medium according to the present invention comprises:

[0009] - a measurement tube for conveying the medium,

[0010] wherein the measurement tube has a first antenna socket,

[0011] - a first microwave antenna device arranged in the first antenna socket,

[0012] wherein the first microwave antenna device is designed to emit a first microwave signal and a second microwave signal,

[0013] wherein the first microwave signal has a first main radiation direction, and the second microwave signal has a second main radiation direction different from the first main radiation direction; and

[0014] - a measurement circuit,

[0015] wherein the measurement circuit is connected to the first microwave antenna device,

[0016] wherein the measurement circuit has a high-frequency generator for supplying the first microwave signal and the second microwave signal to the first microwave antenna device,

[0017] wherein the measurement circuit is configured to determine the properties of the medium based at least on the measured first microwave signal,

[0018] wherein the measurement circuit is configured to detect any inhomogeneities in the measurement tube based on the measured first microwave signal and the measured second microwave signal.

[0019] Compared with WO 2016 / 075367 A1, the two measurement paths are achieved by two microwave signals having different main radiation directions, rather than by two pairs of microwave antennas. This can already be achieved by precisely using one microwave antenna, which is configured to not only emit the first microwave signal and the second microwave signal into the measurement tube, but also receive them once they have passed through the medium.

[0020] The advantage of this is that, in addition to the number of microwave antenna devices that are already sufficient to determine the properties of the multiphase medium, no additional microwave antenna devices are required. Each additional microwave antenna device requires a corresponding antenna socket on the measurement tube, which can form potential leakage points. In addition, each microwave antenna device is accompanied by additional costs. Furthermore, providing electronic devices that can handle more than two signal paths is also more complex.

[0021] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0022] One embodiment provides for selecting a second main radiation direction such that the propagation direction of the microwave signal changes between the emission and reception of the second microwave signal.

[0023] The second main radiation direction for emitting the second microwave signal is preferably selected such that the propagation direction changes at least once during the propagation of the second microwave signal through the medium. The change in the propagation direction is caused by the reflection of the second microwave signal at the inner wall of the measuring tube and / or the medium boundary.

[0024] One embodiment provides that the first main radiation direction points radially into the measuring tube.

[0025] One embodiment provides that the first microwave antenna device is in particular mechanically pivotable.

[0026] By designing the first microwave antenna to be mechanically pivotable, the generation of two microwave signals with different main radiation directions can be achieved. Thus, the first microwave antenna device includes mechanical pivoting means configured to mechanically align the microwave antenna. This allows for setting two main radiation directions. For example, the pivoting means may include at least one piezoelectric element, which may be electrically actuated and interacts with the microwave antenna such that the main radiation direction of the microwave signal emitted by the microwave antenna can be controlled via the voltage applied to the piezoelectric element. Thus, an electromechanical solution for pivoting the microwave antenna device can be achieved.

[0027] Pivoting allows operation in at least two modes. On the one hand, there is a standard mode for optimally determining the solid content. On the other hand, there is a diagnostic mode for detecting deposits or partial filling.

[0028] One embodiment provides that the first microwave antenna device is designed to electronically pivot the first main radiation direction of the second microwave signal.

[0029] By designing the first microwave antenna device to be electronically pivotable, the generation of two microwave signals with different main radiation directions can be achieved. Microwave antenna devices are known which are suitable for generating microwave signals with different main radiation directions.

[0030] One example is a phased array antenna, which is a phase-controlled antenna array with strong directivity. It achieves the bundling of radiation energy, thus enabling electronic beam pivoting through an array of individual transmission elements and connections (at least two microwave antennas). The antenna array uses the phase shift of the individual transmission elements arranged in the array to achieve energy bundling, which is caused by the interference of separately generated microwave signals. The transmitted energy is amplified in the desired main field direction, while the unwanted directions are eliminated by destructive interference.

[0031] One embodiment provides that two microwave signals are fed into the medium simultaneously, especially due to the excitation of two modes of the microwave antenna device, either by means of an excitation signal having at least two different excitation frequencies or by means of at least two excitation signals each having a different excitation frequency.

[0032] The waveguide of the microwave antenna can be designed such that not only one mode with exactly one characteristic field pattern propagates in the desired frequency band, but at least two modes are formed. These can be excited by different frequencies, thereby generating microwave signals with different main radiation directions. Therefore, an excitation signal having at least two different frequencies or two excitation signals having different frequencies can be fed into the waveguide at different times to generate two microwave signals. If two sufficiently different frequencies are to be selected, the two measured microwave signals can be separated.

[0033] One embodiment provides that the measurement assembly further includes:

[0034] - A second microwave antenna device, which is arranged in the second antenna socket of the measuring tube and is especially oriented opposite to the first antenna socket,

[0035] wherein the second microwave antenna device is configured to measure the first microwave signal and the second microwave signal.

[0036] One embodiment provides that the second microwave antenna device is designed to be mechanically pivotable, or

[0037] wherein the second microwave antenna device is designed to electronically pivot the second main radiation direction of the second microwave signal.

[0038] The advantage of limiting the number of microwave antenna devices to exactly two is that the design of the measurement assembly is more compact, especially shorter.

[0039] One embodiment provides that the first main radiation direction is guided along the shortest connection between the first microwave antenna device and the second microwave antenna device.

[0040] One embodiment provides that the measuring assembly includes a position sensor configured to determine the current orientation of the measuring tube and / or the first microwave antenna device relative to the earth,

[0041] wherein the measuring circuit is configured to take into account the current orientation of the measuring tube when detecting inhomogeneities, in particular when determining the cause of the inhomogeneities.

[0042] By means of the position sensor, it is possible to distinguish whether any determined inhomogeneity is caused by the formation of deposits or by the partial filling of the measuring tube.

[0043] One embodiment provides that the measuring circuit is configured to determine a first measured value of the solids content of the medium based on the measured first microwave signal,

[0044] wherein the measuring circuit is configured to determine a second measured value of the solids content based on the measured second microwave signal,

[0045] wherein the first measured value and the second measured value are included when detecting inhomogeneities, in particular when determining the cause of the inhomogeneities.

[0046] One embodiment provides that the first microwave antenna device is configured to emit a third microwave signal having a third main radiation direction,

[0047] wherein the third main radiation direction of the third microwave signal is different from the first main radiation direction and the second main radiation direction,

[0048] wherein the measuring circuit is configured to detect inhomogeneities in the measuring tube based on the first microwave signal, the second microwave signal, and the third microwave signal.

[0049] One embodiment provides that the longitudinal cross-section of the measuring tube passing through the first microwave antenna device divides the measuring tube into a first measuring tube section and a second measuring tube section,

[0050] wherein the second main radiation direction points to the first measuring tube section and the third main radiation direction points to the second measuring tube section.

[0051] One embodiment provides that the inhomogeneities particularly include asymmetric deposit formation, partial filling of the measuring tube, and / or precipitate formation.

[0052] One embodiment provides that the first main radiation direction and the second main radiation direction are located in a common measuring tube cross-section that intersects at least the first microwave antenna device.

[0053] One embodiment provides that the second main radiation direction, in particular the second main radiation direction and the third main radiation direction, have a direction component pointing in the longitudinal direction of the measuring tube.

[0054] If the second main radiation direction has a component pointing in the longitudinal direction of the measuring tube, additional information regarding the properties of the medium outside the measuring cross-section can be determined. Given the vertical orientation of the measuring assembly on the production line and the partial filling of the measuring tube, the partial filling itself can be detected.

[0055] According to the method of the invention for determining any non-uniformities in the measuring tube, by means of a measuring assembly according to any one of the preceding claims, the method comprises the following method steps:

[0056] - Transmitting a first microwave signal having a first main radiation direction into the measuring tube by means of a first microwave antenna device;

[0057] - Receiving the first microwave signal after transmission, in particular by means of a second microwave antenna device,

[0058] wherein the received first microwave signal is produced by at least the transmitted first microwave signal and its interaction with the medium;

[0059] - Transmitting a second microwave signal having a second main radiation direction into the measuring tube by means of the first microwave antenna device,

[0060] wherein the first main radiation direction is different from the second main radiation direction;

[0061] - Receiving the second microwave signal after transmission, in particular by means of the second microwave antenna device,

[0062] wherein the received second microwave signal is produced by at least the second transmitted microwave signal and its interaction with the medium,

[0063] wherein the second microwave signal is reflected at least once on the inner surface of the measuring tube such that the second propagation direction changes spatially at least once between the emission and the reception of the second microwave signal;

[0064] - Detecting whether any non-uniformities are present in the measuring tube based on the received first and second microwave signals.

[0065] An embodiment of the method according to the invention comprises:

[0066] - Transmitting a third microwave signal having a third main radiation direction into the measuring tube by means of the first microwave antenna device;

[0067] - Receiving the third microwave signal after transmission, in particular by means of the second microwave antenna device,

[0068] wherein the received third microwave signal is produced by at least the transmitted third microwave signal and its interaction with the medium;

[0069] - Detect whether there is any non-uniformity in the measurement tube based on the received first microwave signal, second microwave signal, and third microwave signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The present invention will be explained in more detail with reference to the following drawings. In the drawings:

[0071] Figure 1 is a cross-section of an embodiment of a measurement assembly according to the present invention;

[0072] Figure 2 is a cross-section of another embodiment of a measurement assembly according to the present invention;

[0073] Figure 3 is a longitudinal section of another embodiment of a measurement assembly according to the present invention; and

[0074] Figure 4 is a cross-section of another embodiment of a measurement assembly according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0075] Figure 1 Shows a cross-section of an embodiment of a measurement assembly 1 for determining the properties of a multiphase flowable water-based medium according to the present invention. The measurement assembly 1 includes a measurement tube 2 for conducting a substantially water-based medium having solid components. In the embodiment shown here, the measurement tube 2 is cylindrical and has a metallic inner measurement tube wall. According to the present invention, other measurement tube shapes homeomorphic to the cylindrical geometry are also provided.

[0076] A first antenna socket 3 in the form of an opening in the measuring tube 2 is formed. The measuring tube 2 can be made of metal, and the measuring tube opening can be realized by a hole. The first microwave antenna device 5 is arranged in the first antenna socket 3 in a dielectrically sealed manner. The first microwave antenna device 5 has at least one microwave antenna. In addition, the first microwave antenna device 5 can have a holder for at least one microwave antenna, and the holder is configured to hold the microwave antenna immovably in the measuring tube opening. The first microwave antenna device 5 is designed to emit a first microwave signal A and a second microwave signal B. The two microwave signals are substantially different in a given propagation direction. The first microwave signal A has a first main radiation direction a, in which the microwave signal A is radiated into the medium, and the second microwave signal B has a second main radiation direction b, which is different from the first main radiation direction a and in which the second microwave signal B is radiated into the medium. The two microwave signals pass through the measuring tube and interact with the medium flowing through the measuring tube (see the first microwave signal A' and the second microwave signal B'). The second microwave signal B' is reflected once at the inner wall of the measuring tube. The second main radiation direction b is selected such that the propagation direction of the microwave signal changes between the emission and the reception of the second microwave signal . The first main radiation direction a and the second main radiation direction b are located in a common measuring tube cross-section Y of the measuring tube 2 that at least intersects the first microwave antenna device 5.

[0077] The first microwave antenna device 5 is suitable for beam rotation. This can be achieved by means of a mechanical or electromechanical pivoting device, such that the first microwave antenna device 5 is designed to be mechanically pivotable. Alternatively, the first microwave antenna device 5 can be designed to electronically pivot the microwave signal, thereby providing the first main radiation direction a and the second main radiation direction b. For this purpose, the first microwave antenna device 5 includes at least two microwave antennas arranged in an array. The first microwave antenna device 5 is configured to adjust the phase position at the microwave antennas, such that different main radiation directions can be set due to interference and focusing.

[0078] The shown measuring assembly 1 also has a second microwave antenna device 6, which is arranged in a second antenna socket 4 of the measuring tube 2, in particular oriented opposite to the first antenna socket 3. As a result, the first main radiation direction a is guided along the shortest connection between the first microwave antenna device 5 and the second microwave antenna device 6.

[0079] The second microwave antenna device 6 is configured to receive and measure the first microwave signal and the second microwave measurement signal . The first microwave signal A' reaches the second microwave antenna device 6 in a direct path, i.e., it is not reflected. The first microwave signal A' interacts with the medium on its way to the second microwave antenna device 6, such that the measured first microwave signal Contains information about the medium. This also applies to the second microwave signal B’ and the measured second microwave signal The second microwave antenna device 6 can also be designed to be mechanically pivotable. Alternatively, the second microwave antenna device 6 can be designed such that the second main radiation direction b of the second microwave signal B can be electronically pivoted.

[0080] The measuring assembly 1 also has a measuring circuit 9, which is connected to the first microwave antenna device 5 and the second microwave antenna device 6. The measuring circuit 9 has a high-frequency generator for generating microwave signals. The high-frequency generator generates a first microwave signal A, which is fed into the medium or into the interior of the measuring tube via the first microwave antenna device 5. The second microwave signal B is also generated by the high-frequency generator and is fed into the medium or into the interior of the measuring tube via the first microwave antenna device 5. The measuring circuit 9 is configured to measure, at the second microwave antenna device 6, the first microwave signal and the second microwave signal that have passed through the interior of the measuring tube. The first microwave signal A and the second microwave signal B propagate through the medium. This results in an interaction between the microwave signals A, B and the medium, which in turn changes the microwave signals A and B.

[0081] The measuring circuit 9 is further configured to determine a first measured value of the solids content of the medium based on the measured first microwave signal and to determine a second measured value of the solids content based on the measured second microwave signal An algorithm is used to then detect inhomogeneities based on the first and second measured values. Inhomogeneities can in particular be asymmetric deposit formation, partial filling of the measuring tube 2, and / or precipitate formation.

[0082] Figure 2 shows a cross-section of another embodiment of the measuring assembly 1 according to the invention. The depicted measuring assembly differs substantially from the embodiment in Figure 1 that the measuring assembly 1 has only one precise microwave antenna device. This is configured to emit a first microwave signal A having a first main radiation direction a, which is directed in particular radially into the measuring tube 2. The generated first microwave signal A propagates along the measuring tube diameter (becoming the first microwave signal A’ when interacting with the medium) and is reflected back on the opposite side of the first microwave antenna device 5. The first microwave signal is measured at the first microwave antenna device 5 The resulting measurement path corresponds to twice the inner diameter of the measurement tube 2. The first microwave antenna device 5 is also configured to emit a second microwave signal B having a second main field direction b, which is emitted in this direction and which is different from the first main field direction a. The second main field direction b is selected such that the second microwave signal B is reflected three times at the inner wall and propagates back to the first microwave antenna device 5 from which it was measured. Alternatively, the second main field direction b can be selected such that the microwave signal is only reflected twice at the inner wall before being detected by the first microwave antenna device 5. Alternatively, the second main field direction b can also be selected such that the microwave signal is reflected more than three times at the inner wall before being detected by the first microwave antenna device 5.

[0083] Figure 3 Shows a longitudinal section of another embodiment of the measurement assembly 1 according to the invention. The measurement assembly 1 has a vertical mounting orientation, i.e., the longitudinal axis of the measurement assembly 1 or the measurement tube intersects the earth's surface substantially perpendicularly. A potential application is the use of the measurement assembly 1 in a riser pipe. In such an application, if the medium to be transported stops and (partial) medium backflow occurs, the measurement tube may be partially filled. To detect the installation position, the measurement assembly 1 has a position sensor 7, which is configured to determine the current orientation of the measurement tube 2 and / or the first microwave antenna device 5 relative to the earth or the earth's gravity. Then, when detecting non-uniformities, especially when determining the cause of the non-uniformities, the determined orientation is included. As shown, the position sensor 7 can be arranged in a common module together with the measurement circuit 9. Alternatively, the position sensor 7 can also be arranged in the sensor itself.

[0084] The measurement assembly 1 has a first microwave antenna device 5 and a second microwave antenna device 6. The first microwave antenna device 5 is configured to radially radiate a first microwave signal a into the measurement tube. The first main radiation direction a is substantially located in the cross-section Y that intersects the two microwave antenna devices and is oriented perpendicular to the longitudinal axis of the measurement tube. In addition, the first microwave antenna device 5 is suitable for emitting a second microwave signal B having a second main radiation direction b. The second main radiation direction b has a direction component pointing in the longitudinal direction of the measurement tube 2. Thus, the second main radiation direction b points outside the cross-section Y. If the measurement tube or the process pipeline is partially filled, the second microwave signal B' propagating through the medium is reflected at the medium boundary and measured by means of the second microwave antenna device 6. The measurement circuit 9 is configured to infer the partial filling of the measurement tube based on the measured microwave signal and the determined orientation.

[0085] Figure 4 Shows a cross-section of another embodiment of the measurement assembly 1 according to the invention. Figure 4 The embodiment of Figure 1The basic difference of the embodiment is that the first microwave antenna device 5 is further configured to transmit a third microwave signal C having a third main radiation direction c. The third main radiation direction c of the third microwave signal C is different from the first main radiation direction a and the second main radiation direction b. The measuring tube longitudinal section X passing through the first microwave antenna device 5 divides the measuring tube 2 into a first measuring tube section I and a second measuring tube section II. In the depicted embodiment, the longitudinal axis of the measuring tube is also located in the longitudinal section X of the measuring tube. Regarding the depicted embodiment, it is important that the second main radiation direction b points into the first measuring tube section I and the third main radiation direction c points into the second measuring tube section II. The measuring circuit 9 is configured to detect any non-uniformity in the measuring tube 2 based on the first microwave signal measured at the second microwave antenna device 6, the second microwave signal, and the third microwave signal. In particular, when the measuring assembly 1 is mounted horizontally, sediment may form in the second measuring tube section II. Sediment is different from deposition formation in that the solids of the medium are not deposited substantially uniformly on the entire inner circumference of the inner wall, but only on the lower part of the measuring tube. The third microwave signal C' propagates through the medium and also through the sediment. Therefore, by means of the measured third microwave signal , it is possible to distinguish whether sedimentation or deposition formation has occurred. If uniform deposition formation has occurred along the circumference of the measuring tube, the measured second microwave signal is substantially matched with the measured third microwave signal . If sedimentation has occurred, the difference between the two measured microwave signals is greater.

[0086] List of reference numerals

[0087] Measuring assembly 1

[0088] Measuring tube 2

[0089] First antenna socket 3

[0090] Second antenna socket 4

[0091] First microwave antenna device 5

[0092] Second microwave antenna device 6

[0093] Position sensor 7

[0094] Measuring circuit 9

[0095] First microwave signal A

[0096] First main radiation direction a

[0097] Second microwave signal B

[0098] Second main radiation direction b

[0099] Third microwave signal C

[0100] Third main radiation direction c

[0101] Measured first microwave signal

[0102] Measured second microwave signal

[0103] Measured third microwave signal

[0104] First measuring tube section I

[0105] Second measuring tube section II

[0106] Longitudinal section X of the measuring tube

[0107] Cross-sectional area Y of the measuring tube

Claims

1. A measuring assembly (1) for determining the properties of a multiphase flowable medium, comprising: - A measuring tube (2) for conveying the medium, wherein the measuring tube (2) has a first antenna socket (3), - A first microwave antenna device (5) arranged in the first antenna socket (3), wherein the first microwave antenna device (5) is designed to emit a first microwave signal (A) and a second microwave signal (B), wherein the first microwave signal (A) has a first main radiation direction (a) and the second microwave signal (B) has a second main radiation direction (b) different from the first main radiation direction (a); and - A measuring circuit (9), wherein the measuring circuit (9) is connected to the first microwave antenna device (5), wherein the measuring circuit (9) has a high-frequency generator for supplying the first microwave signal (A) and the second microwave signal (B) to the first microwave antenna device (5), wherein the measurement circuit (9) is configured to determine the property of the medium based at least on the measured first microwave signal ( ). wherein the measurement circuit (9) is configured to detect any inhomogeneities in the measured content of the measuring tube - in particular the medium in the measuring tube (2) - based on the measured first microwave signal ( ) and the measured second microwave signal ( ).

2. The measuring assembly (1) according to claim 1, Among them, The second main radiation direction is selected such that the propagation direction of the microwave signal changes between the emission and reception of the second microwave signal.

3. The measuring assembly (1) according to claim 1 or claim 2, Among them, The first main radiation direction (a) points radially into the measuring tube (2) and / or in the direction of the longitudinal axis of the first microwave antenna device (5).

4. The measuring assembly (1) according to at least one of the preceding claims, Among them, The first microwave antenna device (5) is configured to be mechanically pivotable, in particular.

5. The measuring assembly (1) according to any one of the preceding claims, Among them, The first microwave antenna device (5) is configured to electronically pivot the second main radiation direction (b) of the second microwave signal (B).

6. The measuring assembly (1) according to any one of the preceding claims, comprising: - A second microwave antenna device (6) arranged in a second antenna socket (4) of the measuring tube (2) which is particularly oriented opposite to the first antenna socket (3), Among them, the second microwave antenna device (6) is configured to measure the first microwave signal ( ) and the second microwave measurement signal ( ).

7. The measuring assembly (1) according to claim 6, Among them, The second microwave antenna device (6) is configured to be mechanically pivotable, in particular, or wherein the second microwave antenna device (6) is configured to be electronically pivotable, and can be aligned so that the emitted microwave signal can be measured.

8. The measuring assembly (1) according to claim 6 or claim 7, Among them, The first main radiation direction (a) is guided along the shortest connection between the first microwave antenna device (5) and the second microwave antenna device (6).

9. The measuring assembly (1) according to any one of the preceding claims, Among them, The measuring assembly (1) includes a position sensor (7) configured to determine the current orientation of the measuring tube (2) and / or the first microwave antenna device (5) relative to gravity, Wherein, the measurement circuit (9) is configured to take into account the current orientation of the measurement tube (2) when detecting the inhomogeneity, in particular when determining the cause of the inhomogeneity.

10. The measurement assembly (1) according to any one of the preceding claims, Among them, The measurement circuit (9) is configured to determine a first measured value of the solids content of the medium based on the measured first microwave signal ( ), wherein, the measurement circuit (9) is configured to determine a second measurement value of the solids content based on the measured second microwave signal ( ), and / or wherein detecting the inhomogeneity, in particular when determining the cause of the inhomogeneity, includes the first measurement value and the second measurement value.

11. The measurement assembly (1) according to any one of the preceding claims, Among them, the first microwave antenna device (5) is configured to emit a third microwave signal (C) having a third main radiation direction (c), wherein the third main radiation direction (c) of the third microwave signal (C) is different from the first main radiation direction (a) and the second main radiation direction (b). Among them, the measurement circuit (9) is configured to detect the non-uniformity in the measurement tube (2) based on the first microwave signal ( ), the second microwave signal ( ), and the third microwave signal ( ).

12. The measurement assembly (1) according to claim 11, Among them, a measurement tube longitudinal section (X) passing through the first microwave antenna device (5) divides the measurement tube (2) into a first measurement tube section (I) and a second measurement tube section (II), wherein the second main radiation direction (b) points to the first measurement tube section (I), and the third main radiation direction (c) points to the second measurement tube section (II).

13. The measurement assembly (1) according to at least one of the preceding claims, Among them, the inhomogeneity particularly includes asymmetric deposit formation, partial filling of the measurement tube (2) and / or precipitate formation.

14. The measurement assembly (1) according to at least one of the preceding claims, Among them, the first main radiation direction (a) and the second main radiation direction (b) are located in a common cross-section (Y) of the measurement tube (2) that at least intersects the first microwave antenna device (5).

15. The measurement assembly (1) according to at least one of claims 1 to 13, Among them, the second main radiation direction (b), in particular the second main radiation direction (b) and the third main radiation direction (c), has a direction component pointing in the longitudinal direction of the measurement tube (2).

16. A method for determining any inhomogeneity in a measurement tube (2), in particular by means of the measurement assembly (1) according to any one of the preceding claims, the method comprising the following method steps: - emitting a first microwave signal (A) having a first main radiation direction (a) into the measurement tube (2) by means of a first microwave antenna device (5); - In particular, the first microwave signal after transmission is received by means of the second microwave antenna device (6) ( ) wherein, The received first microwave signal ( ) is generated by at least the transmitted first microwave signal (A) and its interaction with the medium; - emitting a second microwave signal (B) having a second main radiation direction (b) into the measurement tube (2) by means of the first microwave antenna device (5), wherein the first main radiation direction (a) is different from the second main radiation direction (b); - In particular, the second microwave signal ( ) after transmission is received by means of the second microwave antenna device (6). Among them, the received second microwave signal ( ) is generated at least by the second microwave signal (B) and its interaction with the medium. Wherein, the second microwave signal (B) is reflected at least once on the inner surface of the measurement tube (2), such that the second propagation direction changes spatially at least once between the emission of the second microwave signal (B) and the reception of the second microwave signal ( ); - Detect whether there is any non-uniformity in the measurement tube (2) based on the received first microwave signal ( ) and the second microwave signal ( ).

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