Method for the contactless determination of condensate formation

Abstract

The invention relates to a method for the contactless determination of a condensate formation on a measuring tube surface (34) of, in particular metallic, a measuring tube (3) by means of an optical temperature sensor (12) for the contactless detection of a temperature of the measuring tube (3) and to a modular Coriolis flowmeter (1).

Description

[0001] Method for contactless detection of condensate formation

[0002] The invention relates to methods for contactless detection of condensate formation on a measuring tube surface of a measuring tube, in particular a metallic one, by means of an optical temperature sensor for contactless detection of a temperature of the measuring tube and a modular Coriolis flowmeter for determining a process variable of a flowable medium.

[0003] Field devices for process measurement technology with a vibration-type sensor, and in particular Coriolis flowmeters, have been known for many years. The basic design of such a measuring device is described, for example, in EP 1 807 681 A1, whereby the design of a generic field device is fully incorporated by reference in this publication within the scope of the present invention.

[0004] Typically, Coriolis flowmeters have at least one or more oscillating measuring tubes, which can be set into vibration by a vibration exciter. These vibrations are transmitted along the length of the tube and are influenced by the type of fluid contained in the measuring tube and its flow velocity. A vibration sensor, or in particular two spaced-apart vibration sensors, can record the varied vibrations at another location in the measuring tube in the form of one or more measurement signals. An evaluation unit can then determine the mass flow, viscosity, and / or density of the medium from the measurement signal(s).

[0005] The measuring tubes are typically connected to the housing via a distributor piece. The three components mentioned are welded together. However, Coriolis flowmeters with replaceable disposable measuring tube assemblies based on a modular design are also known. For example, WO 2011 / 099989 A1 teaches a method for producing a monolithic measuring tube assembly of a Coriolis flowmeter with bent measuring tubes. The measuring tube body of the respective measuring tubes is first formed from a solid polymer, and the channel for guiding the flowable medium is then machined into the housing. WO 2011 / 099989 A1, like US Pat. No. 10,209,113 B2, teaches a connecting body designed to accommodate and support a replaceable measuring tube module comprising thin-walled plastic tubes.The measuring tube module is attached to a support device equipped with the necessary exciters and sensors via the connecting body.

[0006] Coriolis flowmeters are known from the prior art in which the temperature sensor is attached to the measuring tube, for example, by a soldered connection. However, such a solution is extremely disadvantageous for disposable applications, since in this case, electrical contact between the temperature sensor and a measuring circuit must be ensured when arranging the measuring tube module in the holder. Furthermore, this would result in the temperature sensor being disposed of after each use of the measuring tube module. Optical temperature sensors are generally known. US 2017 / 0102257 A1 discloses the use of an optical temperature sensor in a conventional Coriolis flowmeter. The temperature sensor is arranged inside the housing and faces the measuring tube.However, such a solution is not suitable for disposable applications where the measuring tube module is constantly replaced, as inserting the measuring tube module into the measuring tube module holder may result in collision with the optical temperature sensor, thus damaging both components. Furthermore, the disclosed solution is not cleanable and therefore unsuitable for most biopharmaceutical applications.

[0007] Unlike conventional Coriolis flowmeters, the measuring tube modules in modular Coriolis flowmeters are not hermetically sealed in a housing. This is due to the interchangeability of the measuring tubes. However, when replacing the measuring tube modules and cleaning the carrier module, atmospheric moisture can enter the measuring tube holder, which can then condense on the measuring tubes of the measuring tube module. It is known from WO 2004 / 005089 A1 that dew point sensors, which are in contact with the humidity present in the measuring space, are used in addition to temperature sensors. However, the additional use of a dew point sensor in the holder of the modular Coriolis flowmeter would be extremely disadvantageous, as this would not ensure that the carrier module can be cleaned, and it would also not allow any guaranteed conclusions to be drawn about the actual dew behavior of the moisture on the measuring tube.

[0008] The invention is based on the object of remedying the problem and simplifying the method for determining condensate formation.

[0009] The object is achieved by the method according to claim 1 and the modular Coriolis flowmeter according to claim 4.

[0010] The method according to the invention for contactless detection of condensate formation on a measuring tube surface of a measuring tube, in particular a metallic one, by means of an optical temperature sensor for contactless detection of a temperature of the measuring tube, comprising the method steps:

[0011] - Receiving a light beam emitted from the measuring tube surface of the measuring tube by means of the temperature sensor,

[0012] - Output of an output signal correlating with the temperature of the measuring tube to an evaluation circuit,

[0013] - Identification of condensate on the measuring tube surface if the output signal and / or a temporal change of the output signal is outside a tolerance range by means of the evaluation circuit,

[0014] - Optional: Issue a warning that condensate has formed on the measuring tube.

[0015] In the context of the patent application, contactless detection is understood to mean a determination of the formation of condensate on a measuring tube surface, in which the temperature sensor or components of the temperature sensor do not come into mechanical contact with the measuring tube surface and the condensate.

[0016] The temperature sensor comprises a sensor suitable for detecting the light beam and determining the light beam intensity. The optical temperature sensor can be, for example, an infrared temperature sensor. For this purpose, the temperature sensor can comprise, for example, a photodiode. Alternatively, the temperature sensor can comprise a light beam generating device configured to generate a light beam directed onto the surface, in particular the measuring tube surface, of the measuring tube. The optical temperature sensor is then configured to detect the light beam reflected from the surface, in particular the measuring tube surface.

[0017] The output signal essentially comprises the temperature of the measuring tube or a current signal correlating with the temperature of the measuring tube.

[0018] Non-contact detection of condensate formation is particularly advantageous for vibrating measuring tubes. A beneficial application is found in a conventional Coriolis flowmeter and / or a modular Coriolis flowmeter for use in disposable applications for biopharmaceutical processes. In this case, the temperature sensor is oriented relative to the measuring tube surface to be monitored so that the temperature measuring point is located on the vibrating measuring tube during operation.

[0019] Coriolis flowmeters are also known in which the measuring tube has a measuring tube section that does not oscillate during operation.

[0020] Alternatively, the temperature sensor can be arranged so that the temperature measuring point is located on the section of the measuring tube that does not vibrate during operation.

[0021] Advantageous embodiments of the invention are the subject of the subclaims.

[0022] One embodiment includes the following procedural step:

[0023] - Identify a dissolution of the condensate when the output signal that was previously out of tolerance returns to within tolerance.

[0024] One embodiment provides that the tolerance range has a first tolerance limit, wherein the temperature sensor has a measuring range, wherein the tolerance limit lies outside the measuring range.

[0025] Temperature sensors have a measuring range specified by the manufacturer, which indicates a temperature range within which the temperature sensor measures within its specifications. If measured values ​​of the output signal and / or the temporal change of the output signal lie outside the tolerance range and thus also outside the measuring range, condensate formation is assumed.

[0026] The modular Coriolis flowmeter according to the invention for determining a process variable of a flowable medium, comprising:

[0027] - a measuring tube module, wherein the measuring tube module comprises at least one measuring tube for guiding the medium, wherein the measuring tube module has a primary excitation component, wherein the measuring tube module has a primary sensor component;

[0028] - a carrier module, wherein the carrier module has a receptacle in which the measuring tube module can be detachably arranged, wherein the carrier module has a secondary excitation component complementary to the primary excitation component, wherein the carrier module has a secondary sensor component complementary to the primary sensor component,

[0029] - a contactless temperature sensor, wherein the contactless temperature sensor is arranged in / on the carrier module such that when the measuring tube module is arranged in the carrier module, the contactless temperature sensor is directed towards a measuring tube surface of the measuring tube and receives a light beam emitted from the measuring tube surface of the measuring tube, wherein the modular Coriolis flowmeter is configured to carry out the method according to one of the preceding claims.

[0030] Condensate on the measuring tube leads to an asymmetric mass distribution of the measuring tube and thus to errors in the mass flow determination.

[0031] By using a contactless temperature sensor, locating the temperature sensor in the electronics chamber, and separating the electronics chamber and accommodating it via an opening with protective glass, a solution for temperature measurements is created that is suitable for disposable applications and avoids damage when mounting the measuring tube modules.

[0032] A dew point sensor is used. The temperature sensor is separated from the humidity in the recording and does not come into contact with it.

[0033] To carry out the method according to the invention, the modular Coriolis flowmeter has electronic components - such as a processor, logical electronic components, etc. - which are suitable for carrying out the method steps of the method according to the invention themselves and / or in conjunction with the temperature sensor.

[0034] The alignment of the temperature sensor to the surface, in particular to the measuring tube surface of the metallic measuring tube, can also be carried out with or via one or more mirrors and / or prism lenses.

[0035] Advantageous embodiments of the invention are the subject of the subclaims.

[0036] One embodiment provides for the temperature sensor to be an infrared sensor, and the light beam to be infrared light. By using an infrared sensor, the temperature of the medium being conveyed remains unaffected, enabling contactless temperature measurements at short distances and in a light-tight space.

[0037] One embodiment provides that the at least one measuring tube is bent in a measuring tube section, wherein the measuring tube surface lies in the measuring tube section.

[0038] One embodiment provides that the carrier module has a chamber for accommodating the temperature sensor, wherein the chamber is separated from the receptacle by a carrier module wall, wherein the temperature sensor is arranged in the chamber.

[0039] One embodiment provides that the temperature sensor in the chamber is sealed from the air in the receptacle.

[0040] One embodiment provides that an opening is arranged in the carrier module wall, wherein a protective glass is arranged in the opening, wherein the temperature sensor is arranged in the chamber and the measuring tube is arranged in the receptacle in such a way that the light beam passes through the opening, in particular through the protective glass which is at least partially transparent to the light beam, to the temperature sensor.

[0041] One embodiment provides that the protective glass comprises zinc sulfide at least in sections or is formed from zinc sulfide.

[0042] One embodiment provides that the protective glass comprises chalcogenides or is formed from chalcogenides at least in sections.

[0043] The two materials mentioned for the protective glass are particularly suitable for use with infrared sensors, as they are particularly transparent to radiation with a wavelength between 8 and 12 pm. The invention is explained in more detail with reference to the following figures. It shows:

[0044] Fig. 1a: a perspective view of an embodiment of the Coriolis flowmeter according to the invention, in which the measuring tube module is arranged next to the carrier module and its holder;

[0045] Fig. 1 b: a perspective view of an embodiment of the Coriolis flowmeter according to the invention, in which the measuring tube module is arranged in the receptacle;

[0046] Fig. 1c: a perspective view of an embodiment of the Coriolis flowmeter according to the invention, in which the measuring tube module is fixed in the receptacle by a fastening device; and

[0047] Fig. 2: a detailed view of a longitudinal section through an embodiment of the Coriolis flowmeter according to the invention.

[0048] Fig. 3a-c: three embodiments of the modular Coriolis flowmeter according to the invention;

[0049] Fig. 4: a process chain for an embodiment of the method according to the invention for contactless detection of condensate formation; and

[0050] Fig. 5: a graph in which the measured temperature of a flowing medium is plotted over the contactless temperature sensor and two reference sensors as a function of time.

[0051] An embodiment according to the invention is shown in Figs. 1a to 1c. These show the step-by-step assembly of the measuring tube module 4 in the receptacle 11 of the carrier module 10. Fig. 1a shows a perspective view of an embodiment of the Coriolis flowmeter 1 according to the invention, in which the measuring tube module 4 is arranged next to the carrier module 10 and its receptacle 11. The 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 guiding the flowable medium. The measuring tube 3 is preferably made of metal. However, it can additionally or alternatively comprise a plastic, a ceramic and / or a glass. In the embodiment shown, the measuring tube module 4 comprises exactly two measuring tubes 3a, 3b. A primary excitation component 23 is arranged on the outer surface of the measuring tubes 3a, 3b.The primary excitation component 23 comprises at least one permanent magnet. Furthermore, two primary sensor components 24a, 24b are each attached to the outer surfaces of the measuring tubes 3a, 3b. The primary sensor component 24a, 24b also comprises at least one permanent magnet. The respective inlet sections and the outlet sections of the two measuring tubes are connected to one another via a plate-shaped connecting body 7. This serves to attach a distributor piece (not shown) to the measuring tubes 3a, 3b and has the contact surface for the fastening device 48. Alternatively, the distributor piece can also be connected to the measuring tubes 3a, 3b without a connecting body 7. In this case, the measuring tube module 4 is attached to the fastening device 48 via the distributor piece. According to the illustrated embodiment, the mechanical connection of the carrier module 10 to the measuring tubes 3a, 3b is established via the connecting body 7.In the final assembled state, the connecting body 7 rests on a support surface 26 recessed into the carrier module body 22. Furthermore, mechanical couplers 6 are provided which connect the inlet sections or the outlet sections of the measuring tubes 3a, 3b to one another. The carrier module 10 comprises a receptacle 11 into which the measuring tube module 4 can be arranged with a detachable connection. The receptacle 11 is delimited by the carrier module wall 31 and, according to the embodiment shown, is essentially an opening into which or a free volume in the carrier module 10 into which the measuring tube module 4 can be arranged in a vibratable manner. The carrier module wall 31 is preferably made of metal. The measuring tube module 4 can be arranged in the receptacle 11 laterally, perpendicular to its own longitudinal axis (not shown), or frontally in the direction of its own longitudinal axis.Separated from the receptacle 11 by the support module wall 31 is a chamber 30 in which electronic components 40 for operating the modular Coriolis flowmeter 1 and for determining the process variable are arranged. The electronic components 40 can include connectors, cables, circuit boards, amplifiers, electronic circuits with resistors, capacitors, diodes, transistors, and coils, digital and / or analog circuits, and / or a programmable microprocessor, i.e., a processor embodied as an integrated circuit. The electronic components 40 also include the operating circuit, control circuit, measuring circuit, evaluation circuit, and / or display circuit.

[0052] Fig. 1b shows a measuring tube module 4 arranged in the receptacle 11. The connecting body 7 rests on the support surface 26. The measuring tubes 3a, 3b protrude into the receptacle 11 in a manner capable of oscillating, without touching the support module wall 31. The connecting body 7 serves to form a connection with a connecting body (not shown), in particular a distributor piece, with which the measuring tube module 4 can be connected to a process line. The measuring tube module 4 shown is not fixed.

[0053] Fig. 1c shows a Coriolis flowmeter 1 in which the measuring tube module 4 is fixed in the receptacle 11 by a fastening device 48 such that it can be removed and replaced by the operator. The measuring tube module 4 is mechanically detachably connected or connectable to the carrier module 10. After the measuring tube module 4 is fixed and thus properly arranged and configured, the secondary excitation component 13 and the secondary sensor component 14 are activated. In the arranged state of the measuring tube module 4, the secondary excitation component 13 and the primary excitation component 23, and accordingly the secondary sensor component 14 and the primary sensor component 24a, 24b, have a magnetic effect. The secondary excitation component 13 is configured to cause the at least one measuring tube 3 to oscillate. For this purpose, the secondary excitation component 13 typically comprises a magnetic coil which is operated via an operating circuit.The operating circuit can be part of the electronic components 40. The coil generates a time-varying magnetic field in accordance with the operating signal with which it is driven. This exerts a force on the primary excitation component 23, which causes the at least one measuring tube 3 to oscillate. The oscillation behavior of the at least one measuring tube 3 is measured via the secondary sensor component 14. The time-varying magnetic field of the primary sensor component 24a, 24b present locally at the secondary sensor component 14—which results from the oscillation of the at least one measuring tube 3—generates an electrical measurement signal in the sensor component 14, which preferably also comprises a magnetic coil. This electrical measurement signal is used to determine the process variable. According to the illustrated embodiment, exactly two secondary excitation components 13 and four secondary sensor components 14 are provided.Alternatively, exactly one secondary excitation component 13 and exactly two secondary sensor components 14 may be sufficient for two measuring tubes 3a, 3b, provided they are arranged in the carrier module 10 such that they are located between the two measuring tubes 3a, 3b, and thus also between the primary excitation components 23 and primary sensor components 24a, 24b in the arranged state. The secondary excitation component 13 and the secondary sensor component 14 are arranged in / on the carrier module 10. They can, for example, be arranged such that they are separated from the receptacle 11 by the carrier module wall 31. Alternatively, the carrier module wall 31 can have excitation openings corresponding to the number of secondary excitation components 13, in which the secondary excitation components 13 are arranged. The same applies to the secondary sensor component 14.The carrier module wall 31 can have sensor openings corresponding to the number of secondary sensor components 14, in which the secondary sensor components 14 are arranged.

[0054] Fig. 2 shows a detailed view of a longitudinal section through an embodiment of the Coriolis flowmeter 1 according to the invention. The support module wall 31 separates the receptacle 11 from the chamber 30. Electronic components 40 are arranged in the chamber 30 and are electrically connected to the secondary excitation component and / or the secondary sensor component (not shown). A measuring tube 3a of a measuring tube module is arranged in the receptacle 11. The support module wall 31 has a through opening 32 that connects the receptacle 11 to the chamber 30. A protective glass 33 is arranged in this opening 32.

[0055] A contactless temperature sensor 12 is arranged in the chamber 30 for determining a temperature of the measuring tube 3a or the medium conveyed in the measuring tube 3a. The temperature sensor 12 is oriented such that when the measuring tube module or the measuring tube 3a is arranged in the carrier module 10, in particular in the receptacle 11, it is directed toward a measuring tube surface 34 of the at least one measuring tube 3, in particular the measuring tube 3a, and receives a light beam emitted by the measuring tube surface 34 of the at least one measuring tube 3 through the opening 32.

[0056] The temperature sensor 12 has a, in particular anodized, aperture 37 for masking out interference radiation, a lens, and an SMD IR sensor. The aperture 37 is designed as a blackbody radiator (e.g., made of anodized aluminum) if possible, so that it does not itself radiate any radiation onto the SMD IR sensor. In the embodiment shown, the temperature sensor 12 is arranged on a printed circuit board. The aperture 37 has a minimum distance dßiende, min from the measuring tube surface 34 of 1 mm, in particular 2 mm, and preferably 4 mm. In addition, the aperture 37 has a maximum distance dBiende max from the measuring tube surface 34 of 18 mm, in particular 12 mm, and preferably 9 mm.

[0057] The protective glass 33 comprises zinc sulfide and / or chalcogenides, at least in sections. The protective glass is shaped, formed, and arranged in the opening in such a way that cleaning agent does not penetrate into the chamber 40 when cleaning the carrier module 10. For this purpose, the protective glass 33 has a first diameter d in a first section. ± and in a second section a second diameter d2. The first diameter d1 is larger than the second diameter d2 and the first diameter d ± is larger than a smallest diameter d oef the opening 32. The protective glass 33 has a maximum length d L max of a maximum of 15 mm, in particular 10 mm and preferably 7 mm and a minimum extension of L min von at least 0.5 mm, in particular 1 mm and preferably 3 mm. The holder 11 and the measuring tube module 4 are designed such that a distance d Schutzbetween the measuring tube surface 34 and the protective glass 33 is less than 5 and greater than 0.5 mm, in particular less than 3 and greater than 0.7 mm, and preferably less than 2 and greater than 1 mm. The dimensions are selected such that as little ambient radiation as possible penetrates through the opening into the temperature sensor 12 and that, if possible, only the radiation emitted by the measuring tube 3a is recorded by the temperature sensor 12.

[0058] In the second section of the protective glass 33, a sealing means 35 for sealing the receptacle 11 against the receptacle 11—in the illustrated case, a sealing ring—is arranged on the protective glass 33, in particular in such a way that it is openly visible from the receptacle 11. Thus, the requirement for ensuring the product quality of medicinal products and active ingredients according to current "Good Manufacturing Practice" (cGMP) and the IP56 standard valid in 2022 is met.

[0059] 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 interior of the chamber 30 towards the receptacle 11. In this case, the protective glass 33, in particular the first section of the protective glass 33, is pressed against the sealing means 35. In the embodiment shown, the fastening device 36 comprises an annular disc which is connected to the carrier module wall 31 via screws. The aperture 37 extends through a central opening in the annular disc. The annular disc is in contact with and interacts with a sealing ring which is arranged on a surface of the protective glass 33 facing the interior of the chamber 30. Alternatively, the annular disc can be in direct contact with the protective glass 33.The annular disc has a collar facing the protective glass 33 and extending around the central opening of the annular disc. In the illustrated embodiment, the annular disc is rotationally symmetrical.

[0060] Individual components of the electronic components 40 are also electrically connected to the temperature sensor 12 - which can be designed as an infrared sensor. The infrared sensor is configured to detect infrared light and, as a function thereof, to determine a temperature of the measuring tube 3a or a measured variable correlating with the temperature of the measuring tube 3a. The temperature of the measuring tube 3a can be determined via the evaluation circuit. The temperature sensor 12 is suitable for determining the temperature of the measuring tube 3a without contact, i.e. without being in direct mechanical contact with the measuring tube 3a. It is also arranged in the chamber 30 and separated from the measuring tube 3a by a protective glass 33.In order to be able to determine a temperature of the measuring tube 3a, the temperature sensor 12 is oriented such that when the measuring tube module is arranged in the carrier module, in particular in the receptacle 11, the temperature sensor 12 is directed onto a measuring tube surface 34 of the at least one measuring tube 3 and receives a light beam emitted by the measuring tube surface 34 of the measuring tube 3 through the opening 32.

[0061] The receptacle 11 and the measuring tube module 4 are designed such that the receptacle 11 or the internal volume in which the at least one measuring tube is located is essentially sealed off from light when the measuring tube module 4 is arranged.

[0062] The at least one measuring tube 3 or the illustrated measuring tube 3a has a temperature measuring point 38 in the form of a matted finish. The surface structuring of the temperature measuring point 38 differs from the structuring present on the remaining measuring tube surface. The temperature sensor 12 is oriented such that it is directed toward the temperature measuring point 38. The temperature measuring point 37 can be structured using a laser process and / or a surface treatment by the action of a blasting agent, in particular sand. Alternatively, the temperature measuring point 37 can be formed by a film applied to the at least one measuring tube or the measuring tube 3a, which film can also have a structuring.

[0063] In the illustrated embodiment, the temperature sensor is directed toward the measuring tube, which vibrates during operation. Alternatively, the temperature sensor can also be oriented so that it is directed toward one of the mechanical couplers, a non-vibrating section of the measuring tube, the connecting body 7, or the connecting body or distributor piece of the measuring tube module.

[0064] Fig. 3a to 3c show several different configurations of the measuring tube module 4, in which the temperature sensor 12 is directed at different surfaces of the measuring tube module 4 or determines the medium temperature based on different radiating surfaces of the measuring tube module 4. In the configuration of Fig. 3a, the contactless temperature sensor 12 is oriented such that it is directed at the surface of the primary excitation component 23 - in this case, the primary excitation component 23 is a permanent magnet attached to the measuring tube 3a - and receives a light beam emitted by the surface (see arrow).

[0065] In the embodiment of Fig. 3b, the contactless temperature sensor 12 is oriented such 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 by the surface (see arrow).

[0066] In the embodiment of Fig. 3c, the contactless temperature sensor 12 is oriented such that it is directed toward a 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 such that a measurement signal resulting from the light emitted by the component 41 and received by the temperature sensor 12 is larger than a measurement signal that would result if the temperature sensor 12 were directed toward a measuring tube surface of the measuring tube 3a. For this purpose, the component 41 has, for example, a cross-sectional area that is larger than a partial section area of ​​the measuring tube 3a that would contribute to the measurement signal at the temperature sensor 12.

[0067] Fig. 4 shows a process chain for an embodiment of the method according to the invention for the contactless detection of condensate formation.

[0068] In a first step (I), a light beam emitted from the measuring tube surface is received by the temperature sensor. Alternatively, the light beam can be generated by a light beam generating device, directed by the device onto the measuring tube surface, and reflected there. In a second step (II), an output signal correlating with the temperature of the measuring tube is output from the temperature sensor to an evaluation circuit of, for example, the modular Coriolis flowmeter.

[0069] In a third step (III), condensate on the measuring tube surface is identified based on the output signal or an evaluation signal generated based on the output signal. Condensation is present when the output signal and / or a temporal change in the output signal lies outside a predetermined tolerance range or when the output signal and / or a temporal change in the output signal exceeds a specified tolerance limit. Identification is performed by the evaluation circuit.

[0070] In an optional fourth step (IV), a warning is issued that condensate has formed on the measuring tube.

[0071] In a fifth step (V), which is also optional, a dissolution of the condensate on the measuring tube is identified when the output signal, which was previously outside the tolerance range, is again within the tolerance range

[0072] Fig. 5 shows a graph of a test series in which the temperature of a flowing medium determined via the contactless temperature sensor (A) and two reference temperature sensors (B, C) is plotted as a function of time. For the method according to the invention and the modular Coriolis flowmeter, 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 of the method according to the invention. For the test series, the measuring tube module according to the invention was arranged in a measuring chamber and a flowable medium was passed through a measuring tube of the measuring tube module. The characteristic curve (A) describes the course of the temperature TempJR determined by the contactless temperature sensor - in this case an infrared sensor.The characteristic curve (B) was recorded using a first reference temperature sensor that is in contact with the medium flowing through the measuring tube and measures the medium temperature Temp_Medium. The characteristic curve (C) was recorded using a second reference temperature sensor that is in contact with and determines the ambient temperature Temp_Ambient of the measuring chamber. Firstly, the graph shows that the temperature determined by the non-contact temperature sensor corresponds 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. The course of the characteristic curves A and B overlap sufficiently well, even with a step-like change in the medium temperature.If the ambient temperature Temp_Ambient is also increased, condensation will form at the monitored measuring point as the medium temperature and thus also the measuring tube temperature decrease further. In the curve shown, this occurs at a medium temperature of approximately 17 °C. During this period, the non-contact temperature sensor transmits erroneous measurement data in its output signals. These data lie outside the specified measuring range of the non-contact temperature sensor and thus also outside the specified tolerance range. The condensate on the temperature measuring point causes reflections of the light beam, and only a portion of the light beam emitted by the measuring tube surface reaches the non-contact temperature sensor.

[0073] After increasing the medium temperature above 17°C, the condensate dissolves and the temperature signal determined from the output signal again corresponds to the actual medium temperature.

[0074] List of reference symbols

[0075] Modular Coriolis flowmeter 1

[0076] Measuring tube 3a, 3b

[0077] Measuring tube module 4

[0078] Coupler 6

[0079] Connecting body 7

[0080] Carrier module 10

[0081] Recording 11

[0082] Temperature sensor 12

[0083] Carrier module body 22 secondary excitation component 13 secondary sensor component 14 primary excitation component 23 primary sensor component 24a, 24b

[0084] Support surface 26

[0085] Chamber 30

[0086] Carrier module wall 31

[0087] Opening 32

[0088] Protective glass 33

[0089] Measuring tube surface 34

[0090] Sealant 35

[0091] Fastening device 36 for fixing the protective glass

[0092] Aperture 37

[0093] Temperature measuring point 38

[0094] Electronic components 40

[0095] Component 41

[0096] Fastening device 48 for fixing the measuring tube module

Claims

Patent claims 1. Method for non-contact detection of condensation on a surface, in particular on a measuring tube surface (34) of a measuring tube (3), in particular a metallic one, by means of an optical temperature sensor (12) for non-contact detection of a temperature of the measuring tube (3), comprising the method steps: - Receiving a light beam emitted from the measuring tube surface (34) of the measuring tube (3) by means of the temperature sensor (12), - Outputting an output signal correlated with the temperature of the measuring tube (3) to an evaluation circuit (5), - Identifying a condensate on the measuring tube surface (34) when the output signal and / or a temporal change of the output signal is outside a tolerance range using the evaluation circuit (5), - Optional: Issue a warning that condensate has formed on the measuring tube (3).

2. The method of claim 1, comprising the method step: - Identifying a resolution of the condensate when the output signal, which was previously outside the tolerance range, is again within the tolerance range.

3. Method according to claim 1 or 2, wherein the tolerance range has a first tolerance limit, wherein the temperature sensor (12) has a measuring range, wherein the tolerance limit lies outside the measuring range.

4. Modular Coriolis flowmeter (1 ) for determining a process parameter of a flowable medium, comprising: - a measuring tube module (4), wherein the measuring tube module (4) comprises at least one measuring tube (3) for guiding the medium, wherein the measuring tube module (4) has a primary excitation component (23), wherein the measuring tube module (4) has a primary sensor component (24); - a carrier module (10), wherein the carrier module (10) has a receptacle (11) in which the measuring tube module can be detachably arranged, wherein the carrier module (10) has a secondary excitation component (13) complementary to the primary excitation component (23), and wherein the carrier module (10) has a secondary sensor component (14) complementary to the primary sensor component (24). - a non-contact temperature sensor (12), wherein 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 directed towards a surface of the measuring tube module (4), in particular towards a 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 the measuring tube surface (34) of the measuring tube (3), wherein the modular Coriolis flowmeter (1) is configured to carry out the method according to one of the preceding claims.

5. Modular Coriolis flowmeter (1) according to claim 4, wherein the temperature sensor (12) is designed as an infrared sensor and the light beam includes infrared light.

6. Modular Coriolis flowmeter (1 ) according to claim 4 or 5, wherein the at least one measuring tube (3) is bent in a measuring tube section, wherein the measuring tube surface (34) lies in the measuring tube section.

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

8. Modular Coriolis flowmeter (1 ) according to claim 7, wherein the temperature sensor (12) in the chamber (40) is sealed against the air in the receptacle (11 ).

9. Modular Coriolis flowmeter (1 ) according to claim 7 or 8, wherein an opening (32) is arranged in the support module wall (31 ), wherein a protective glass (33) is arranged in the opening (32), wherein the temperature sensor (12) is arranged in the chamber (40) and the measuring tube (3) is arranged in the receptacle (11) such that the light beam passes through the opening (32), in particular through the protective glass (33) which is at least partially transparent to the light beam, to the temperature sensor (12).

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