Method for contactless determination of condensate formation

Abstract

The invention relates to a method for contactlessly determining a condensate formation on a measuring tube surface (34) of a measuring tube (3) by means of an optical temperature sensor (12) for contactlessly detecting a temperature of the measuring tube (3), in particular a metal, and to a modular Coriolis flow meter (1).

Description

Technical Field

[0001] The invention relates to a method for contactlessly determining condensate formation on a measuring tube surface of a measuring tube by means of an optical temperature sensor for contactlessly detecting the temperature of an, in particular metallic, measuring tube, and to a modular Coriolis flowmeter for determining a process variable of a flowable medium. Background Art

[0002] Process measurement technology field devices with vibration sensors, in particular Coriolis flowmeters, have been known for many years. The basic structure of such measuring devices is described, for example, in EP 1 807 681 A1, to which disclosure reference is made in its entirety with regard to the structure of a generic field device in the context of the present invention.

[0003] Typically, a Coriolis flowmeter has at least one or more vibratable measuring tubes, which can be set to vibration by means of a vibration exciter. These vibrations are transmitted along the tube length and are influenced by the type of flowable medium located in the measuring tube and its flow velocity. At another point in the measuring tube, a vibration sensor, or in particular two vibration sensors spaced apart from one another, can record the changing vibrations in the form of a measurement signal or a plurality of measurement signals. An evaluation unit can then determine the mass flow rate, the viscosity and / or the density of the medium from the measurement signals.

[0004] The measuring tube is usually connected to the housing via a distributor. In this case, the three components mentioned are welded together. However, Coriolis flowmeters with interchangeable, disposable measuring tube arrangements based on a modular design are also known. For example, in WO 2011 / 099989 A1, a method for producing a monolithically formed measuring tube arrangement of a Coriolis flowmeter with a curved measuring tube is taught, wherein the measuring tube body of the respective measuring tube is first formed as a solid made of a polymer and subsequently a channel for conducting a flowable medium is machined into the solid. WO 2011 / 099989 A1, similar to US 10,209,113 B2, teaches a connector configured to receive and support a replaceable measuring tube module comprising a thin-walled plastic tube. The measuring tube module is fixed via the connector in a carrier device equipped with the necessary exciters and sensors.

[0005] Coriolis flowmeters are known from the prior art in which a temperature sensor is attached to the measuring tube by, for example, a welded connection. However, this solution is extremely disadvantageous for disposable applications, since in this case an electrical contact of the temperature sensor with the measuring circuit must be ensured when the measuring tube module is arranged in the container. Furthermore, this means that the temperature sensor must be discarded after each use of the measuring tube module. Optical temperature sensors are known in principle. US 2017 / 0102257A1 discloses the use of an optical temperature sensor in a conventional Coriolis flowmeter. The temperature sensor is located inside the housing and faces the measuring tube. However, this solution is not suitable for disposable applications in which the measuring tube module is constantly replaced, since when the measuring tube module is inserted into the measuring tube module container, it may collide with the optical temperature sensor and thus damage both components. Furthermore, the disclosed solution is not cleanable and is therefore not suitable for most biopharmaceutical applications.

[0006] Unlike conventional Coriolis flowmeters, the measuring tube modules in modular Coriolis flowmeters are not arranged to be hermetically sealed in a housing. This is due to the interchangeability of the measuring tubes. However, replacing the measuring tube modules and cleaning the carrier modules means that moisture can enter the container provided for the measuring tubes, which can condense on the measuring tubes of the measuring tube modules. It is known from WO 2004 / 005089 A1 to use, in addition to a temperature sensor, a dew point sensor which is in contact with the moisture present in the measuring chamber. However, the additional use of a dew point sensor in the container of a modular Coriolis flowmeter would be very disadvantageous, since it does not ensure that the carrier module can be cleaned and no reliable conclusions can be drawn about the actual condensation behavior of moisture on the measuring tubes. Summary of the invention

[0007] The invention is based on the object of solving this problem and simplifying the method for determining condensate formation.

[0008] This object is achieved by a method according to claim 1 and a modular Coriolis flow meter according to claim 4 .

[0009] The method according to the invention for contactlessly determining condensate formation on the surface of a measuring tube by means of an optical temperature sensor for contactlessly detecting the temperature of a particularly metallic measuring tube comprises the following method steps:

[0010] - receiving the light beam emitted from the measuring tube surface of the measuring tube by means of a temperature sensor,

[0011] - outputs an output signal which is dependent on the temperature of the measuring tube to an evaluation circuit,

[0012] - condensation on the measuring tube surface is detected by means of the evaluation circuit if the output signal and / or the temporal variation of the output signal is outside the tolerance range,

[0013] - Optionally: Warning that condensate has formed on the measuring tube.

[0014] In the context of the present patent application, contactless determination is understood to mean determination of condensate formation on the measuring tube surface, wherein the temperature sensor or components of the temperature sensor do not come into mechanical contact with the measuring tube surface and the condensate.

[0015] The temperature sensor comprises a sensor suitable for detecting a light beam and determining the intensity of the light beam. The optical temperature sensor can be, for example, an infrared temperature sensor. For this purpose, the temperature sensor can, for example, have a photodiode. Alternatively, the temperature sensor can comprise a light beam generating device designed to generate a light beam directed onto a surface of the measuring tube, in particular the measuring tube surface. The optical temperature sensor is then designed to detect the light beam reflected at the surface, in particular the measuring tube surface.

[0016] The output signal mainly includes the temperature of the measuring tube or a current signal related to the temperature of the measuring tube.

[0017] The contactless determination of condensate formation is particularly advantageous in the case of vibrating measuring tubes. Conventional Coriolis flow meters and / or modular Coriolis flow meters find advantageous application in the use in single-use applications in biopharmaceutical processes. In this case, the temperature sensor is oriented relative to the measuring tube surface to be monitored so that the temperature measurement point is located on the measuring tube which vibrates during operation.

[0018] Also known are Coriolis flow meters in which the measuring tube has a measuring tube portion which does not vibrate during operation. Alternatively, the temperature sensor can be arranged accordingly such that the temperature measurement point is located on the portion of the measuring tube which does not vibrate during operation.

[0019] Advantageous embodiments of the invention are subject matter of the dependent claims.

[0020] One embodiment includes the following method steps:

[0021] - Dissolution of condensate is detected when the output signal, which was previously outside the tolerance range, returns to within the tolerance range.

[0022] One embodiment provides that the tolerance range has a first tolerance limit,

[0023] Among them, the temperature sensor has a measurement range,

[0024] The tolerance limits lie outside the measuring range.

[0025] The temperature sensor has a measuring range specified by the manufacturer, which indicates the temperature range that the temperature sensor measures within its specifications. If the measured value of the output signal and / or the temporal variation of the output signal is outside the tolerance range and therefore also outside the measuring range, the formation of condensate is inferred.

[0026] A modular Coriolis flowmeter for determining a process variable of a flowable medium according to the invention comprises:

[0027] - Measuring tube module,

[0028] The measuring tube module comprises at least one measuring tube for guiding the medium.

[0029] The measuring tube module has a primary exciter assembly.

[0030] Wherein, the measuring tube module has a primary sensor assembly;

[0031] - carrier module,

[0032] The carrier module has a container in which the measuring tube module can be arranged detachably.

[0033] wherein the carrier module has a secondary actuator component complementary to the primary actuator component,

[0034] wherein the carrier module has a secondary sensor component complementary to the primary sensor component,

[0035] - Non-contact temperature sensor,

[0036] wherein the non-contact temperature sensor is arranged in / on the carrier module such that when the measuring tube module is arranged in the carrier module, the non-contact temperature sensor is guided at a measuring tube surface of the measuring tube and receives a light beam emitted from the measuring tube surface of the measuring tube,

[0037] Therein, the modular Coriolis flow meter is designed for carrying out the method according to any of the preceding claims.

[0038] Condensate on the measuring tube leads to an asymmetrical mass distribution of the measuring tube and thus to errors in the determination of the mass flow.

[0039] By using a contactless temperature sensor, arranging the temperature sensor in the electronics chamber and separating the electronics chamber and the container via an opening with a protective glass, a temperature measurement solution suitable for single-use applications is obtained and damages during installation of the measuring tube module are avoided.

[0040] A dew point sensor is used. The temperature sensor is arranged to be separate from the moisture in the container and not in contact with it.

[0041] To carry out the method according to the invention, the modular Coriolis flow meter has electronic components, such as processors, logic electronics, etc., which are suitable for carrying out the method steps of the method according to the invention themselves and / or in combination with a temperature sensor.

[0042] It is also possible to align the temperature sensor with or via one or more mirrors and / or prisms to the surface of a metallic measuring tube, in particular the measuring tube surface.

[0043] Advantageous embodiments of the invention are subject matter of the dependent claims.

[0044] One embodiment provides that the temperature sensor is designed as an infrared sensor and that the light beam comprises infrared light.

[0045] By using infrared sensors, the temperature of the medium to be conveyed is not affected and non-contact temperature measurement can be carried out over short distances and in light-tight spaces.

[0046] One embodiment provides that at least one measuring tube is bent in a measuring tube section,

[0047] Therein, the measuring tube surface is located in the measuring tube section.

[0048] One embodiment provides that the carrier module has a cavity for accommodating a temperature sensor,

[0049] The chamber is separated from the container by a carrier module wall.

[0050] Therein, a temperature sensor is arranged in the chamber.

[0051] One embodiment provides that the temperature sensor in the chamber is sealed against the air in the container.

[0052] One embodiment provides that the opening is arranged in the carrier module wall,

[0053] wherein a protective glass is arranged in the opening,

[0054] Therein, the temperature sensor is arranged in the chamber and the measuring tube is arranged in the container, so that the light beam reaches the temperature sensor through the opening, in particular through a protective glass at least partially transparent for the light beam.

[0055] One embodiment provides that the cover glass at least partially comprises zinc sulfide or consists of zinc sulfide.

[0056] One embodiment provides that the cover glass at least partially comprises a chalcogenide or is formed from a chalcogenide.

[0057] The two materials mentioned for the protective glass are particularly suitable for use with infrared sensors, since they are particularly transparent for radiation with a wavelength between 8 and 12 µm. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The present invention will be described in more detail with reference to the following drawings, in which:

[0059] Figure 1a is a perspective view of an embodiment of a Coriolis flow meter according to the invention, in which a measuring tube module is arranged next to a carrier module and its container;

[0060] Figure 1b is a perspective view of an embodiment of a Coriolis flow meter according to the present invention, wherein a measuring tube module is arranged in a container;

[0061] Figure 1c is a perspective view of an embodiment of a Coriolis flow meter according to the present invention, in which a measuring tube module is fixed in a container by a fastening device; and

[0062] Figure 2 is a detailed view of a longitudinal section of an embodiment of a Coriolis flow meter according to the present invention;

[0063] Figure 3a to Figure 3c Three embodiments of a modular Coriolis flow meter according to the present invention are shown;

[0064] Figure 4 A process chain for contactless determination of condensate formation according to an embodiment of the method according to the invention is shown; and

[0065] Figure 5 is a diagram in which the temperature of the flowing medium determined via the contactless temperature sensor and two reference sensors is plotted over time. DETAILED DESCRIPTION

[0066] Figure 1a to Figure 1c An embodiment according to the invention is shown. The figures show the step-by-step assembly of a measuring tube module 4 in a receptacle 11 of a carrier module 10 . Figure 1a1 is a perspective view of an embodiment of a Coriolis flowmeter 1 according to the present invention, in which a measuring tube module 4 is arranged next to a carrier module 10 and its container 11. A modular Coriolis flowmeter 1 for determining a process variable of a flowable medium comprises a measuring tube module 4 and a carrier module 10. The measuring tube module 4 comprises at least one measuring tube 3 for conducting a medium. The measuring tube 3 is preferably made of metal. However, it may additionally or alternatively comprise plastic, ceramic and / or glass. In the illustrated embodiment, the measuring tube module 4 comprises exactly two measuring tubes 3a, 3b. A primary exciter assembly 23 is arranged on the outer surface of each of the measuring tubes 3a, 3b. The primary exciter assembly 23 comprises at least one permanent magnet. In addition, two primary sensor assemblies 24a, 24b are attached to the outer surfaces of the measuring tubes 3a, 3b. The primary sensor assemblies 24a, 24b also comprise at least one permanent magnet. The corresponding inlet and outlet portions of the two measuring tubes are interconnected via a plate-shaped connector 7. This serves to attach a distributor (not shown) to the measuring tubes 3a, 3b and has a contact surface for the fastening device 48. Alternatively, the distributor can also be connected to the measuring tubes 3a, 3b without a connecting body 7. In this case, the measuring tube module 4 is fastened to the fastening device 48 via the distributor. According to the embodiment shown, the mechanical connection of the carrier module 10 to the measuring tubes 3a, 3b is realized via the connecting body 7. In the final assembled state, the connecting body 7 rests on a contact surface 26 embedded in the carrier module body 22. In addition, a mechanical coupler 6 is provided, which connects the inlet section or outlet section of the measuring tubes 3a, 3b to each other. The carrier module 10 comprises a container 11, in which the measuring tube module 4 can be arranged in a detachably connected manner. The container 11 is delimited by a carrier module wall 31 and, according to the embodiment shown, is essentially an opening or a free volume in the carrier module 10, in which the measuring tube module 4 can be arranged, so that the measuring tube module 4 can vibrate. The carrier module wall 31 is preferably made of metal. The measuring tube module 4 can be arranged transversely in the container 11, perpendicular to its own longitudinal axis (not shown), or arranged frontally in the container 11 in the direction of its own longitudinal axis. The chamber 30 separated from the container 11 by the carrier module wall 31 is arranged in which the electronic assembly 40 for operating the modular Coriolis flowmeter 1 and determining the process variables is arranged. The electronic assembly 40 can include connectors, cables, circuit boards, amplifiers, electronic circuits with resistors, capacitors, diodes, transistors and coils, digital and / or analog circuits and / or programmable microprocessors, i.e. processors implemented as integrated circuits. The electronic assembly 40 also includes operating circuits, control circuits, measuring circuits, evaluation circuits and / or display circuits.

[0067] Figure 1bThe measuring tube module 4 is shown arranged in a container 11. In this case, the connecting body 7 rests on the contact surface 26. The measuring tubes 3a, 3b protrude into the container 11 so that they can vibrate without contacting the carrier module wall 31 in the process. The connecting body 7 serves to form a connection with a connecting body (not shown), in particular a distributor, via which the measuring tube module 4 can be connected to a process line. The measuring tube module 4 shown is not fixed.

[0068] Figure 1cA Coriolis flowmeter 1 is shown, wherein the measuring tube module 4 is fixed in the container 11 by means of a fastening device 48, so that the operator can remove it and replace it again. The measuring tube module 4 is connected or can be connected to the carrier module 10 in a mechanically detachable manner. After the measuring tube module 4 has been fixed and thus correctly arranged and set, the secondary exciter assembly 13 and the secondary sensor assembly 14 are activated. In the arranged state of the measuring tube module 4, the secondary exciter assembly 13 and the primary exciter assembly 23 and correspondingly the secondary sensor assembly 14 and the primary sensor assembly 24a, 24b interact magnetically. The secondary exciter assembly 13 is designed to vibrate at least one measuring tube 3. For this purpose, the secondary exciter assembly 13 generally comprises a magnetic coil which is operated via an operating circuit. The operating circuit can be part of the electronic assembly 40. The coil generates a magnetic field which varies with time depending on the operating signal of the operating coil. This causes a force to be generated on the primary exciter assembly 23, so that at least one measuring tube 3 vibrates. The vibration behavior of at least one measuring tube 3 is measured via the secondary sensor assembly 14. The time-varying magnetic field of the primary sensor components 24a, 24b which is locally present at the secondary sensor component 14 - generated by the vibration of at least one measuring tube 3 - generates an electrical measurement signal in the sensor component 14, which preferably also includes a magnetic coil, which signal is included in the determination of the process variable. According to the embodiment shown, exactly two secondary exciter components 13 and four secondary sensor components 14 are provided. Alternatively, exactly one secondary exciter component 13 and exactly two secondary sensor components 14 are sufficient for the two measuring tubes 3a, 3b if exactly one secondary exciter component 13 and exactly two secondary sensor components 14 are arranged in the carrier module 10 so that they are located between the two measuring tubes 3a, 3b and therefore also between the primary exciter component 23 and the primary sensor components 24a, 24b in the arranged state. The secondary exciter component 13 and the secondary sensor component 14 are arranged in / on the carrier module 10. For example, they can be arranged so that they are separated from the container 11 by a carrier module wall 31. Alternatively, the carrier module wall 31 can have exciter openings corresponding to the number of secondary exciter assemblies 13, in which the secondary exciter assemblies 13 are arranged. The same applies to the secondary sensor assemblies 14. The carrier module wall 31 can have sensor openings corresponding to the number of secondary sensor assemblies 14, in which the secondary sensor assemblies 14 are arranged.

[0069] Figure 2is a detailed view of a longitudinal section of an embodiment of a Coriolis flowmeter 1 according to the invention. A carrier module wall 31 separates a container 11 from a chamber 30. An electronic assembly 40 is arranged in the chamber 30 and is electrically connected to a secondary exciter assembly and / or a secondary sensor assembly (not shown). The measuring tube 3a of the measuring tube module is arranged in the container 11. The carrier module wall 31 has a through hole 32 connecting the container 11 to the chamber 30. A protective glass 33 is arranged in the through hole 32.

[0070] A non-contact temperature sensor 12 is arranged in the chamber 30 for determining the temperature of the measuring tube 3a or the temperature of the medium guided in the measuring tube 3a. The temperature sensor 12 is oriented so that when the measuring tube module or the measuring tube 3a is arranged in the carrier module 10, in particular in the container 11, the sensor is guided onto the measuring tube surface 34 of at least one measuring tube 3, in particular the measuring tube 3a, and receives a light beam emitted from the measuring tube surface 34 of the at least one measuring tube 3 through the opening 32.

[0071] The temperature sensor 12 has a hole 37, in particular anodized, for blocking interfering radiation, a lens and an SMD IR sensor. In this case, the hole 37 is preferably designed as a black radiator (e.g. made of anodized aluminum), so that it itself does not emit any radiation to the SMD IR sensor. In the embodiment shown, the temperature sensor 12 is arranged on a circuit board. The minimum distance of the hole 37 to the measuring tube surface 34 is 1 mm, in particular 2 mm, preferably 4 mm. In addition, the maximum distance of the hole 37 to the measuring tube surface 34 is 18 mm, in particular 12 mm, preferably 9 mm.

[0072] The protective glass 33 at least partially comprises zinc sulfide and / or chalcogenide. The protective glass is shaped, formed and arranged in the opening so that the cleaning agent does not penetrate into the chamber 40 when cleaning the carrier module 10. To this end, the protective glass 33 has a first diameter in the first section. , having a second diameter in the second portion In this case, the first diameter Larger than the second diameter , and the first diameter Greater than the minimum diameter of the opening 32 The maximum extension of the protective glass 33 in the longitudinal direction is 15 mm at most, in particular 10 mm, preferably 7 mm, and the minimum extension At least 0.5 mm, in particular 1 mm, preferably 3 mm. The container 11 and the measuring tube module 4 are designed so that the distance between the measuring tube surface 34 and the protective glass 33 is Smaller than 5 mm and larger than 0.5 mm, in particular smaller than 3 mm and larger than 0.7 mm, and preferably smaller than 2 mm and larger than 1 mm. The dimensions are selected so that as little ambient radiation as possible penetrates the temperature sensor 12 through the opening and, if possible, only the radiation emitted by the measuring tube 3 a is recorded by the temperature sensor 12 .

[0073] In the second part of the protective glass 33, a sealing device 35 for sealing the container 11 relative to the container 11 is arranged on the protective glass 33, in the illustrated case a sealing ring, in particular in such a way that it can be openly seen from the container 11. This means that the requirements for ensuring the product quality of medicinal products and active ingredients in accordance with current good manufacturing practices (cGMP) and IP56 (effective from 2022) are met.

[0074] The carrier module 10 has a fastening device 36 for fixing the protective glass 33 in the opening 32. The fastening device is arranged in the chamber 30 and is designed or configured to press the protective glass 33 from the inside of the chamber 30 in the direction of the container 11. In this case, the protective glass 33, in particular the first part of the protective glass 33, is pressed against the sealing device 35. In the embodiment shown, the fastening device 36 comprises an annular disk, which is connected to the carrier module wall 31 via screws. A hole 37 extends through a central opening in the annular disk. The annular disk contacts and interacts with a sealing ring, which is arranged on the surface of the protective glass 33 facing the inside of the chamber 30. Alternatively, the annular disk can be in direct contact with the protective glass 33. The annular disk has an annular ring facing the protective glass 33, which extends around the central opening of the annular disk. In the embodiment shown, the annular disk is rotationally symmetrical.

[0075] The individual components of the electronic assembly 40 are also electrically connected to a temperature sensor 12, which can be designed as an infrared sensor. The infrared sensor is designed to detect infrared light and, depending on this, to determine the temperature of the measuring tube 3a or a measured value related to the temperature of the measuring tube 3a. The temperature of the measuring tube 3a can be determined via an evaluation circuit. The temperature sensor 12 is suitable for determining the temperature of the measuring tube 3a in a contactless manner, i.e. without direct mechanical contact with the measuring tube 3a. The sensor is also arranged in the chamber 30 and is separated from the measuring tube 3a by a protective glass 33. In order to be able to determine the temperature of the measuring tube 3a, the temperature sensor 12 is oriented so that when the measuring tube module is arranged in a carrier module, in particular in a container 11, the temperature sensor 12 is guided onto a measuring tube surface 34 of at least one measuring tube 3 and receives a light beam emitted from the measuring tube surface 34 of the measuring tube 3 through the opening 32.

[0076] The container 11 and the measuring tube module 4 are designed such that when the measuring tube module 4 is arranged, the container 11 or the inner volume in which the at least one measuring tube is located is closed in a substantially light-tight manner.

[0077] At least one measuring tube 3 or the illustrated measuring tube 3a has a temperature measuring point 38 in the form of a mat. The surface structuring of the temperature measuring point 38 differs from the structuring present on the remaining measuring tube surfaces. The temperature sensor 12 is oriented so that it is directed toward the temperature measuring point 38. The temperature measuring point 37 can be structured by means of a laser process and / or a surface treatment by action of a blasting medium, in particular sand. Alternatively, the temperature measuring point 37 can be formed by a film applied to at least one measuring tube or the measuring tube 3a, which film can also have a structuring.

[0078] In the embodiment shown, the temperature sensor is guided at the measuring tube that vibrates during operation. Alternatively, the temperature sensor can also be aligned so that it is guided toward one of the mechanical couplers, toward a non-vibrating part of the measuring tube, the connecting body 7 or a connecting body or a distributor of a measuring tube module.

[0079] Figure 3a to Figure 3c A number of different embodiments of measuring tube modules 4 are shown, in which the temperature sensors 12 are guided at different surfaces of the measuring tube modules 4 or determine the medium temperature based on different radiating surfaces of the measuring tube modules 4. Figure 3a In the embodiment of , the non-contact temperature sensor 12 is oriented so that it is directed towards the surface of the primary exciter assembly 23 - in this case, the primary exciter assembly 23 is a permanent magnet attached to the measuring tube 3a - and receives a light beam emitted from the surface (see arrow).

[0080] exist Figure 3b In the embodiment of , the non-contact temperature sensor 12 is oriented so that it is directed towards the surface of the primary sensor component 24a - in this case, the primary sensor component 24a is a permanent magnet attached to the measuring tube 3a - and receives a light beam emitted from the surface (see arrow).

[0081] exist Figure 3c In the embodiment of the invention, the non-contact temperature sensor 12 is oriented so that it is directed toward the surface of a component 41 attached to the measuring tube 3a - in this case, the attached component 41 is a black plastic component - and receives a light beam emitted by the surface (see arrow). The component 41 is designed so that the measurement signal generated from the light emitted by the component 41 and received by the temperature sensor 12 is greater than the measurement signal that would be generated if the temperature sensor 12 were directed at the measuring tube surface of the measuring tube 3a. To this end, the component 41 has, for example, a cross-sectional area that is greater than the partial area of ​​the measuring tube 3a that would contribute to the measurement signal at the temperature sensor 12.

[0082] Figure 4 A process chain for contactless detection of condensate formation is shown according to an exemplary embodiment of the method according to the invention.

[0083] In a first step (I), a light beam emitted from a measuring tube surface of the measuring tube is received by the temperature sensor. Alternatively, the light beam can be generated by a light beam generating device, guided by the device onto the measuring tube surface and reflected there.

[0084] In a second step (II), an output signal which is dependent on the temperature of the measuring tube is output from the temperature sensor to an evaluation circuit of a—for example modular—Coriolis flow meter.

[0085] In a third step (III), condensation on the measuring tube surface is detected based on the output signal or an evaluation signal created based on the output signal. Condensation is present when the output signal and / or the temporal variation of the output signal is outside a previously defined tolerance range or when the output signal and / or the temporal variation of the output signal exceeds a specified tolerance limit. The detection is performed with the aid of an evaluation circuit.

[0086] In an optional fourth step (IV), a warning is issued that condensate has formed on the measuring tube.

[0087] In a fifth step (V), which is also optional, the dissolution of the condensate on the measuring tube is detected when the output signal, which was previously outside the tolerance range, is again within the tolerance range.

[0088] Figure 5A diagram of a series of tests is shown, in which the temperature of a flowing medium determined via a non-contact temperature sensor (A) and two reference temperature sensors (B, C) is plotted as a function of time. For the method and the modular Coriolis flowmeter according to the invention, only one or precisely one optical temperature sensor (A) is provided. The reference temperature sensors (B, C) are part of the test series, but not part of the method according to the invention. For the test series, a measuring tube module according to the invention is arranged in a measuring chamber and a flowable medium is passed through the measuring tubes of the measuring tube module. The characteristic curve (A) describes the course of the temperature Temp_IR measured by the non-contact temperature sensor, in this case an infrared sensor. The characteristic curve (B) is recorded with a first reference temperature sensor, which is in contact with the medium flowing through the measuring tubes and measures the medium temperature Temp_Medium. The characteristic curve (C) is recorded with a second reference temperature sensor, which interacts with the ambient temperature Temp_Ambient of the measuring chamber and determines the ambient temperature. Firstly, it can be clearly seen from the diagram that the temperature determined by the non-contact temperature sensor corresponds very well to the actual temperature of the medium. The slight deviation can be explained by the fact that the temperature of the medium is not determined directly, but only the temperature of the measuring tube or the measuring tube surface. Even if the medium temperature changes in a step-like manner, the course of the characteristic curves A and B agrees well enough with each other. If the ambient temperature Temp_Ambient also increases, a further decrease in the medium temperature and therefore in the measuring tube temperature will lead to the formation of condensate at the measuring point to be monitored. In the curve shown, this occurs at a medium temperature of approximately 17°C. During this period, the non-contact temperature sensor transmits incorrect measurement data in the output signal, which is outside the specified measuring range of the non-contact temperature sensor and therefore also outside the specified tolerance range. Condensate at the temperature measuring point leads to reflection of the light beam, and only a part of the light beam emitted from the measuring tube surface reaches the non-contact temperature sensor.

[0089] After the medium temperature has increased to above 17° C., the condensate dissolves and the temperature signal determined from the output signal corresponds again to the actual medium temperature.

[0090] Reference numerals list

[0091] Modular Coriolis Flow Meter1

[0092] Measuring tubes 3a, 3b

[0093] Measuring tube module 4

[0094] Coupler 6

[0095] Connector 7

[0096] Carrier module 10

[0097] Container 11

[0098] Temperature sensor 12

[0099] Carrier module body 22

[0100] Secondary driver assembly 13

[0101] Secondary sensor assembly 14

[0102] Primary exciter assembly 23

[0103] Primary sensor assembly 24a, 24b

[0104] Contact surface 26

[0105] Chamber 30

[0106] Carrier module wall 31

[0107] Opening 32

[0108] Protective glass 33

[0109] Measuring tube surface 34

[0110] Sealing device 35

[0111] Fastening device for fixing protective glass 36

[0112] Hole 37

[0113] Temperature measurement point 38

[0114] Electronic components 40

[0115] Component 41

[0116] Fastening device for fixing measuring tube modules 48

Claims

1. A method for contactlessly determining condensate formation on a surface of a measuring tube (3), in particular a measuring tube surface (34), by means of an optical temperature sensor (12) for contactlessly detecting the temperature of a measuring tube (3), in particular a metallic measuring tube (3), comprising the following method steps: - receiving, by means of the temperature sensor (12), a light beam emitted from the measuring tube surface (34) of the measuring tube (3), - outputting an output signal which is dependent on the temperature of the measuring tube (3) to an evaluation circuit (5), - by means of the evaluation circuit (5), condensation on the measuring tube surface (34) is detected if the output signal and / or the temporal variation of the output signal is outside a tolerance range, - Optionally: issuing a warning that condensate has formed on the measuring tube (3).

2. The method according to claim 1, comprising the following method steps: - Dissolution of the condensate is detected when the output signal, which was previously outside a tolerance range, returns to within the tolerance range.

3. The method according to claim 1 or 2, in, The tolerance range has a first tolerance limit, The temperature sensor (12) has a measurement range. Therein, the tolerance limit lies outside the measuring range.

4. A modular Coriolis flowmeter (1) for determining a process variable of a flowable medium, comprising: - Measuring tube module (4), The measuring tube module (4) comprises at least one measuring tube (3) for guiding the medium. The measuring tube module (4) has a primary exciter component (23). Wherein, the measuring tube module (4) has a primary sensor component (24); - a carrier module (10), The carrier module (10) has a container (11), in which the measuring tube module can be detachably arranged. The carrier module (10) has a secondary actuator component (13) which is complementary to the primary actuator component (23). The carrier module (10) has a secondary sensor component (14) that is complementary to the primary sensor component (24). - non-contact temperature sensor (12), The non-contact temperature sensor (12) is arranged in / on the carrier module (10) such that when the measuring tube module (4) is arranged in the carrier module (10), the non-contact temperature sensor (12) is guided to the surface of the measuring tube module (4), in particular to the measuring tube surface (34) of the measuring tube (3), and receives a light beam emitted from the surface of the measuring tube module (4), in particular to the measuring tube surface (34) of the measuring tube (3), Therein, the modular Coriolis flow meter (1) is designed to perform the method according to any of the preceding claims.

5. The modular Coriolis flow meter (1) according to claim 4, in, The temperature sensor (12) is designed as an infrared sensor, and the light beam comprises infrared light.

6. A modular Coriolis flow meter (1) according to claim 4 or 5, in, The at least one measuring tube (3) is bent in a measuring tube section, Therein, the measuring tube surface (34) is located in the measuring tube section.

7. Modular Coriolis flow meter (1) according to at least one of claims 4 to 6, in, The carrier module (10) has a chamber (40) for accommodating the temperature sensor (12). The chamber (40) is separated from the container (11) by a carrier module wall (31). Wherein, the temperature sensor (12) is arranged in the chamber (40).

8. The modular Coriolis flow meter (1) according to claim 7, in, The temperature sensor (12) in the chamber (40) is sealed against the air in the container (11).

9. The modular Coriolis flow meter (1) according to claim 7 or 8, in, An opening (32) is arranged in the carrier module wall (31), wherein a protective glass (33) is arranged in the opening (32), The temperature sensor (12) is arranged in the chamber (40) and the measuring tube (3) is arranged in the container (11) so that the light beam reaches the temperature sensor (12) through the opening (32), in particular through the protective glass (33) which is at least partially transparent to the light beam.

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