Coriolis flow-measuring device and method for calibrating and / or operating a coriolis flow-measuring device

Abstract

The invention relates to a Coriolis flow-measuring device (1) for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a process line, comprising: - a measuring system (10), wherein the measuring system (10) has a measuring line (11) for carrying the measuring medium, wherein the measuring system (10) has at least one measuring tube (12); - a calibrating system (20), wherein the calibrating system (20) has, separate from the measuring line (11), a calibrating line (21) for carrying a calibrating medium, wherein the calibrating system (20) comprises at least one calibrating tube (22); - a (combination) exciter system (30) for exciting mechanical oscillations both of the measuring system and of the calibrating system; - a (combination) sensor system (40) for detecting mechanical oscillations both of the measuring system and of the calibrating system, wherein the exciter system (30) and the sensor system (40) are each connected, in particular re-releasably, to the measuring system (10) and to the calibrating system (20), in particular the exciter system (30) and the sensor system (40) are each connected, preferably re-releasably, to the measuring system (10) and to the calibrating system (20); - and also measuring and calibrating electronics (50), wherein the measuring and calibrating electronics (50) are electrically connected both to the exciter system (30) and to the sensor system (40) and are set up to make both the measuring tube (12) and the calibrating tube (22) perform oscillations by means of the exciter system (30) and to determine oscillations of the measuring tube (12) and the calibrating tube (22) by means of the sensor system (40), wherein the measuring and calibrating electronics (50) are set up to determine at least one calibrating variable of an overall system formed by the measuring system (10) and the calibrating system (20) on the basis of oscillations, determined by means of the sensor system (40), both of the measuring system (10) and of the calibrating system (20) carrying the calibrating medium and wherein the measuring and calibrating electronics (50) are set up to determine the mass flow, the medium density and / or the medium viscosity of the measuring medium carried in the measuring system (10), in dependence on the at least one calibrating variable and / or a variable derived from it.

Description

[0001] Coriolis flowmeter and method for calibrating and / or operating a Coriolis flowmeter

[0002] The invention relates to a Coriolis flowmeter for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a process line and to a method for calibrating and / or operating a Coriolis flowmeter, in particular the Coriolis flowmeter according to the invention.

[0003] WO 2021 / 021116 A1 discloses a Coriolis flowmeter with a measuring system comprising a measuring line and a measuring tube that can no longer be detached from the measuring line, and a compensation system. The compensation system comprises a compensation tube for conveying a compensation medium. Using the measuring device's electronics, the mass of the compensation system can be adjusted by introducing the compensation medium into the compensation tube in such a way that it corresponds to the mass of the measuring system or deliberately deviates from it. The basic idea is to expand the density range of the measuring medium—the limits of which are limited and fixed by the constant mass of the conventionally used compensation body—by making the mass of the compensation body variable.

[0004] WO 99 / 51946 A1 discloses a clamp-on Coriolis flowmeter, which can be reconnected or re-connected to the outer surface of existing process lines. EP 1 150 104 A2 discloses a clamp-on Coriolis flowmeter with a housing that can be attached to a process line and contains a support plate with a vibration generator and a transducer. The housing is attached to the process line in such a way that the vibration generator can cause the process line to vibrate mechanically during operation, and vibration in the process line can be detected by the transducer.

[0005] From WO 2019 / 017891 A1 or WO 2021 / 121867 A2 as well as the German patent applications DE 102021105397 A1, DE 102020133614 A1, DE 102020132685 A1, DE 102020133851 A1, DE 102020133566 A1, DE 102020132986 A1, DE 102020132686 A1, DE 102020132685 A1, DE 102020131452 A1, DE 102020132223 A1, DE 102020127356 A1, DE 102020114519 A1 and DE 102020112154 A1 respectively disclose modular vibronic measuring systems which are formed by means of a carrier system, a pipe module mechanically connected to the carrier system and a measuring system electronics electrically connected to the carrier system and which are used to record at least one measured variable of a fluid measuring medium flowing in a (measuring medium) line, namely to determine measured values ​​for one or more measured variables, for example a mass flow, a volume flow, a density and / or a viscosity, of the measuring medium.The support system of such a (modular) vibronic measuring system comprises a (protective) housing with at least one chamber at least partially enclosed by a housing wall, as well as one or more electrical coils, for example cylindrical and / or designed as air-core coils, which are placed (spaced apart from one another) within the chamber of the (protective) housing and are at least indirectly mechanically connected to the housing wall. Each of the coils is also electrically connected to the measuring system electronics. The measuring system electronics can be accommodated at least partially within the (protective) housing and / or at least partially outside the (protective) housing, for example in a separate electronics housing. The support system is also particularly designed to accommodate the tube module of the measuring system and to be mechanically firmly yet detachably connected thereto (forming a vibration-type measuring transducer), in particular.namely, by forming the vibronic measuring system itself; this is especially true in such a way that the tube module is locked in the support system or is not movable.

[0006] The pipe module of the respective measuring system, in turn, is also designed to be replaceable, such that it can be inserted into the chamber, especially on-site, from outside the (protective) housing of the carrier system or through a (sliding) opening provided in the housing wall of the housing, and that it can be removed from the carrier system again non-destructively, if necessary even without tools, in particular from outside the housing and / or through the (sliding) opening of the housing, or without the carrier system itself having to be handled or removed from the (process) system. This also makes it possible, among other things, to subsequently insert a pipe module on-site, namely into an already installed carrier system, or to replace a defective or worn pipe module on-site with a new, intact pipe module that can be used only once or only for a specified period of time (“disposable”).The tubular module further comprises one or more, for example cylindrical, permanent magnets and is also designed to be installed in the support system in such a way that each of the permanent magnets is placed within the aforementioned chamber, but is spaced apart from the housing wall, in particular in such a way that each of the permanent magnets is held in a static installation position predetermined with regard to an orientation and / or a smallest distance from one of the electrical coils of the support system, and that a respective imaginary longitudinal axis of each of the permanent magnets and an imaginary longitudinal axis of at least one of the electrical coils are aligned with one another or extend parallel to one another.

[0007] In the measuring systems in question, each tube module further comprises at least one (measuring tube), for example at least partially straight and / or at least partially curved, with a tube wall forming an outer surface of the tube, in particular made of a metal or a plastic, and with a lumen enclosed by the same tube wall, in particular two essentially identical parallel (measuring tubes), and each of the aforementioned permanent magnets is fixed to the outside of the tube wall, in particular to a middle segment of the tube wall extending between a first segment end and a second segment end remote therefrom, in particular is integrally connected to the tube wall. In addition, the tube module or at least one (measuring tube) thereof is designed to be installed in the housing, if necessary even without tools, in such a way that the tube at least partially, in particularcompletely, placed within the chamber, yet spaced from the housing wall, and that each of the permanent magnets, in the respective installation position, together with the respective electrical coil, forms a moving coil, particularly useful as an electrodynamic vibration exciter, and / or a plunger coil, particularly useful as an electrodynamic vibration sensor. In the case of a (measuring tube) that is bent at least in sections, the aforementioned segment can, for example, be essentially U-shaped or V-shaped. In such a vibronic measuring system, each of the aforementioned (measuring tubes) is additionally designed to guide a fluid measuring medium flowing within the lumen during operation, particularly with a predeterminable flow direction and / or flow direction pointing from the first segment end to the second segment end, and to be vibrated during this time in order to generate measuring effects correlated with one or more measured variables of the measuring medium, particularlysuch that the middle segment carries out oscillating movements around a static rest position and / or that the (measuring tube is driven by means of at least one of the aforementioned (energized) voice coils and / or that by means of the aforementioned voice coils an (alternating voltage) representing oscillating movements of the at least one tube, thus serving as an oscillation signal, is generated. The measuring system electronics of such a measuring system is in turn accordingly set up to do so by means of an electrical drive signal, in particularwith an impressed alternating current and / or an impressed (alternating current) frequency which essentially corresponds to a resonance frequency of the at least one tube, to feed electrical power into the at least one electrical coil forming the aforementioned moving coil and / or to determine measured values ​​for the one or more measured variables to be recorded of the medium flowing through the (measuring) tube or tubes on the basis of the (alternating) voltage generated by the at least one electrical coil forming the aforementioned moving coil, in the case of a Coriolis mass flow measuring device orFor example, a measuring system designed as a Coriolis mass flow / density measuring device can generate (mass flow) measured values ​​representing the mass flow based on a (measurement) phase difference between two of the aforementioned vibration signals caused by Coriolis forces in the medium flowing through the vibrating pipe, as well as a phase difference to the measured value characteristic function set up in the measuring system electronics. The phase difference to the mass flow measured value characteristic function can, for example, be a (linear) parameter function with a (scale) zero point that corresponds to a (measurement) phase difference between the two vibration signals that is measurable when the medium is at rest or when the mass flow is zero, and with a gradient that corresponds to a (measurement) sensitivity of the measuring system or a change in the (measurement) phase difference related to a change in the mass flow.Since one or more resonance frequencies of the at least one pipe are particularly dependent on the instantaneous density of the respective measuring medium, such a measuring system can be used to directly measure not only the mass flow but also the density of the measuring medium flowing through it using the (alternating current) frequency of the driver signal and / or a (signal) frequency of at least one of the oscillation signals. Accordingly, the measuring system electronics of measuring systems of the type in question are typically also configured to generate density measured values ​​representing the density based on the aforementioned (alternating current) frequency of the driver signal and / or a corresponding signal frequency of at least one of the oscillation signals, for example using a useful frequency-to-measurement characteristic function configured accordingly in the measuring system electronics.Furthermore, it is also possible to directly measure the viscosity of the flowing medium using vibronic measuring systems of the type in question, for example, based on the excitation energy or excitation power required to maintain the useful vibrations and / or based on the damping of the excited (resonance) vibrations resulting from the dissipation of vibration energy, or using a damping-to-measurement characteristic function configured accordingly in the measuring system electronics. Furthermore, other derived measured variables, such as the Reynolds number, can be readily determined from the aforementioned flow and / or material parameters using such vibronic measuring systems.

[0008] To simplify the commissioning of a measuring system formed in this way, the pipe module can further comprise at least one identification element relating to or carrying identifying information about the pipe module, for example a barcode, QR code or radio label (RFID-TAG) attached to at least one pipe, and / or the carrier system can comprise at least one light-emitting semiconductor element positioned within the (protective) housing and connected to the measuring system electronics, for example a light-emitting diode (LED), and / or one or more radio transmitters / receivers (RF transceivers) and / or photosensors, for example one or more CCD photosensors and / or one or more CMOS photosensors, each positioned within the (protective) housing and connected to the measuring system electronics.

[0009] Vibronic measuring systems of the type in question must also be regularly checked for their functionality and / or any deviations from a previously determined reference state, for example the one specified by the manufacturer or in the manufacturing plant and / or a reference state determined on-site during calibration or commissioning of the measuring system, for example in order to be able to detect as early as possible any reductions in functionality or measurement accuracy of the measuring system, with which it ultimately maps the measured variables to be recorded, not least the mass flow and the density, into the corresponding measured values, which are associated with increased deviations from the reference state.Measurement accuracy of such a measuring system can occur, for example, in the form of mostly irreversible changes in the electrical impedance of the aforementioned oscillating and / or moving coils and / or a permanently reduced stability of the mechanical connection between the base and the tube module or the precision of the positioning of the tube module in the carrier system or can be caused, for example, by thermal and / or mechanical overloads, for example as a result of very high or very low temperatures within the carrier system, by aging, by increased or condensing moisture occurring within the carrier system and / or by wear of components of the carrier system caused by frequent replacement of tube modules.Other influencing factors that at least indirectly and / or at least temporarily impair the functionality of the measuring system include multi- and / or high-frequency electromagnetic (external) radiation or fields (EMC) propagating within the carrier system or (external) sound waves propagating within the carrier system, for example in the form of structure-borne sound.

[0010] As a result, it can generally be assumed that one or more of the measuring system's inherent system functions (transfer functions), each of which characterizes a functional dependency of the aforementioned vibration signals on the respective driver signal or one or more functional dependencies of the vibration signals on the driver signal and the respective flow and / or material parameters of the measured material, is changed compared to a (reference) system function inherent in the respective original measuring transducer. An example of such system functions of the measuring system is, among others,a mass flow to phase difference system function, according to which the aforementioned (measurement) phase difference of the vibration signals depends on the mass flow, or a density to resonance frequency system function of the measuring transducer, according to which one or more resonance frequencies of the at least one pipe depend on the density of the measuring medium.Equally affected by such (over)loading of the measuring transducer are the measuring functions of the measuring system involving the aforementioned system functions, according to which the measuring system as a whole converts the respective measured variable to be recorded into the respective measured values, for example a mass flow to measured value measuring function of the measuring system composed of the aforementioned mass flow to phase difference system function and a phase difference to mass flow measured value characteristic function, namely a characteristic function implemented in the measuring system electronics, according to which a determined phase difference is converted into mass flow measured values, according to which the determined mass flow measured values ​​are dependent on the mass flow.The phase difference to mass flow measured value characteristic function can, for example, be a (linear) parameter function with a (scale) zero point corresponding to a (measurement) phase difference measured when the medium is at rest and a (measurement) sensitivity that corresponds to a change in the (measurement) phase difference related to a change in the mass flow (slope of the characteristic function). Further examples of such system functions that are potentially also affected by disturbances or measurement functions formed with them can include a density to resonance frequency system function of the measuring transducer or a density to measured value (measurement) function of the measuring system involving this and a resonance frequency to density measured value characteristic function of the measuring system electronics and / or a viscosity to damping system function of the measuring transducer ora viscosity to measured value (measurement) function of the measuring system involving this as well as a damping of the viscosity to measured value characteristic function of the measuring system electronics. The change in the respective system function can accordingly result, for example, in a drift of one or more of the respective characteristic parameters of one or more of the aforementioned characteristic functions, in the case of a linear parameter function, for example, in their zero point and / or their gradient. The aforementioned, possibly irreversible changes to one or more of the system or measuring functions of the measuring system can occasionally also lead to the measuring system as a whole operating incorrectly to such an extent that the high measuring accuracy typically sought for such measuring systems is no longer guaranteed, and thus the functionality of the measuring system is considerably impaired, possibly even suspended ora correspondingly critical fault in the affected measuring system exists.

[0011] To take this into account, measuring systems of the type in question are typically calibrated accordingly at the factory. It goes without saying that a factory calibration can never fully replicate the specific on-site use case. Especially for measuring systems of the type in question, it is typical that the measuring environment—i.e., the measuring medium, the process line, and / or parts of the measuring system—can change frequently.

[0012] Furthermore, especially in applications that place heavy demands on the measuring system, it may be of interest to carry out a (re-)calibration of the Coriolis flowmeter without having to remove the entire measuring system or parts of the measuring system from the process line.

[0013] Furthermore, when using sterile (disposable) measuring tubes, it is desirable that they do not come into contact with a calibration medium before use.

[0014] The invention is based on the object of providing a suitable solution for on-site calibrations.

[0015] The object is achieved by the Coriolis flowmeter according to claim 1 and the method for calibrating and / or operating a Coriolis flowmeter according to claim 19. The Coriolis flowmeter according to the invention for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a process line, comprising:

[0016] - a measuring system, wherein the measuring system has a measuring line for guiding the measuring medium, wherein the measuring system has at least one measuring tube, in particular a sterile one and / or a measuring tube that is detachably connected to the measuring line and / or designed as a disposable product,

[0017] - a calibration system, wherein the calibration system has a calibration line separate from the measuring line for carrying a calibration medium, in particular water or glycerol, wherein the calibration system comprises at least one calibration tube, in particular a non-sterile one and / or one arranged parallel to the measuring tube,

[0018] - a (“combination”) excitation system for exciting mechanical vibrations of both the measuring system and the calibration system;

[0019] - a ('combination') sensor system for detecting mechanical vibrations of both the measuring system and the calibration system; wherein the excitation system and the sensor system are each connected to the measuring system and the calibration system, in particular the excitation system and the sensor system are each connected, preferably detachably, to the measuring system and the calibration system;

[0020] - and measuring and calibration electronics, wherein the measuring and calibration electronics are electrically connected to both the excitation system and the sensor system and are configured to cause both the measuring tube and the calibration tube to oscillate by means of the excitation system and to detect the oscillation by means of the sensor system, wherein the measuring and calibration electronics are configured to determine at least one calibration variable of an overall system formed by the measuring system and the calibration system based on oscillations of both the measuring system, in particular the one carrying the measuring medium, and the calibration system carrying the calibration medium, determined by means of the sensor system, in particular when the calibration medium is guided in the calibration system with a predetermined (reference) mass flow and / or a predetermined (reference) density and / or a predetermined (reference) viscosity, wherein the measuring and calibration electronics are configured toin particular based on vibrations detected by the sensor system both of the measuring system carrying the measuring medium, in particular through which the measuring medium flows, and of the calibration system, in particular carrying the calibration medium, to determine the mass flow, the medium density and / or the medium viscosity of the measuring medium carried in the measuring system as a function of the at least one calibration variable and / or a variable derived therefrom, in particular when the measuring medium flows in the measuring system.

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

[0022] One embodiment provides that the excitation system and the sensor system are either each permanently connected to the measuring system and detachably connected to the calibration system, each permanently connected to the calibration system and detachably connected to the measuring system, or each detachably connected to the calibration system and detachably connected to the measuring system.

[0023] One embodiment provides that the measuring system and the calibration system are configured to be flowed through independently of each other by the measuring medium or calibration medium, in particular such that the measuring medium and the calibration medium flow simultaneously with differing mass flows and / or at different times through the Coriolis flowmeter.

[0024] One embodiment provides that the calibration system comprises a pump which is designed to pump the calibration medium through the calibration line with a predetermined or predeterminable mass flow, in particular such that the mass flow of the calibration medium is equal to a mass flow of the measuring medium and / or that the mass flow of the calibration medium corresponds to a target mass flow determined based on vibrations determined by means of the sensor system of both the measuring system carrying the measuring medium and the calibration system carrying the calibration medium.

[0025] One embodiment provides that the calibration system has a calibration fastening device with which the calibration tube can be attached to the measuring tube for assembly, in particular radially, and can be mechanically detachably connected to the measuring tube.

[0026] One embodiment provides that the measuring system has a measuring fastening device with which the measuring tube can be attached to the calibration tube for assembly, in particular radially, and can be mechanically detachably connected to the calibration tube.

[0027] In one embodiment, the Coriolis flowmeter comprises:

[0028] - a carrier system, wherein the excitation system and the sensor system are connected, in particular inseparably, to the carrier system.

[0029] One embodiment provides that the measuring tube and the calibration tube are mechanically connected to one another, in particular in a non-detachable manner, and form a tube module, wherein the tube module can be arranged on the carrier system in a mechanically detachable manner.

[0030] One embodiment provides that the carrier system has a carrier fastening device via which the measuring tube and / or the calibration tube can be mechanically detachably connected to the carrier system.

[0031] One embodiment provides that the excitation system comprises a mechanical exciter which interacts mechanically with the measuring tube and the calibration tube.

[0032] One embodiment provides that the excitation system comprises an electromagnetic exciter which is in magnetic interaction with a measuring tube magnet and a calibration tube magnet, wherein the measuring tube magnet is arranged on the measuring tube, wherein the calibration tube magnet is arranged on the calibration tube.

[0033] One embodiment provides that the sensor system comprises at least one electrodynamic, electromagnetic or optical sensor.

[0034] One embodiment provides that the measuring tube and the calibration tube are mechanically coupled to each other, in particular by means of mechanical couplers.

[0035] One embodiment provides that the calibration medium has a predetermined density, a predetermined temperature and / or a predetermined viscosity.

[0036] One embodiment provides that the measuring tube has at least one resonance frequency that is equal to a resonance frequency of the calibration tube, in particular such that a resonance frequency of a first-order bending vibration mode inherent in the measuring tube is equal to a resonance frequency of a first-order bending vibration mode inherent in the calibration tube; and / or wherein the measuring tube and the calibration tube match with respect to one or more geometric parameters, in particular a (tube) length and / or a (tube) wall thickness and / or a caliber.

[0037] One embodiment provides that the tube wall of the measuring tube is made of a metal, in particular stainless steel; and / or wherein the tube wall of the calibration tube is made of a metal, in particular stainless steel; and / or wherein the tube wall of the calibration tube is made of the same material as the tube wall of the measuring tube.

[0038] One design provides that the measuring tube and calibration tube are identical in construction.

[0039] One design provides that the measuring tube is part of the measuring line.

[0040] One embodiment provides that the calibration tube is a, in particular integral, part of the calibration line.

[0041] One embodiment provides that the calibration medium is different from the measuring medium.

[0042] One design provides that the calibration medium is routed exclusively in the calibration line and does not originate from the measuring line or process line.

[0043] The method according to the invention for calibrating and / or operating a Coriolis flowmeter, in particular a Coriolis flowmeter according to one of the preceding claims, wherein the Coriolis flowmeter has a measuring and calibration electronics, a sensor system, an excitation system, a measuring system with a measuring line for conducting a measuring medium and a calibration system with a calibration line separate from the measuring line for conducting a calibration medium, which method comprises the following steps:

[0044] - Passing the calibration medium through the calibration line,

[0045] - Carrying out a calibration when the calibration medium flows through the calibration line at a predetermined mass flow, wherein the calibration comprises exciting the calibration line and the measuring line to oscillate by means of the excitation system, wherein the calibration comprises measuring the oscillations of the calibration tube and the measuring tube by means of the sensor system, wherein the calibration comprises determining at least one calibration variable as a function of the measured oscillations for an overall system represented by the measuring system and the calibration system by means of the measuring and calibration electronics; - Passing the measuring medium through the measuring line;

[0046] - as well as determining the mass flow, the medium density and / or the medium viscosity of the measuring medium depending on the determined calibration value.

[0047] One embodiment provides that the measuring tube is free of the measuring medium during the calibration.

[0048] One embodiment provides that the measuring tube carries a measuring medium, in particular a stationary one, during the calibration.

[0049] One embodiment provides that the calibration tube is free of the calibration medium during the determination of the mass flow, the medium density and / or the medium viscosity of the measuring medium.

[0050] One embodiment provides that the calibration tube carries a calibration medium, in particular a flowing one, during the determination of the mass flow, the medium density and / or the medium viscosity of the measuring medium.

[0051] In one embodiment, the procedure includes:

[0052] - Setting a mass flow of the calibration medium, in particular by means of a pump, such that the mass flow of the calibration medium corresponds to a predetermined target mass flow and / or is equal to a mass flow of the measuring medium (carried in the measuring line); and / or

[0053] - Using the pump to set a mass flow of the calibration medium, especially while the measuring line is carrying measuring medium and / or while no measuring medium is flowing in the measuring line.

[0054] One embodiment provides that the measuring medium and the calibration medium correspond with regard to at least one material parameter, in particular a density and / or a viscosity, in particular in such a way that the measuring medium is used as the calibration medium or the calibration medium corresponds to the measuring medium.

[0055] One embodiment provides that the measuring medium and the calibration medium differ from each other with regard to at least one material parameter, in particular a density and / or a viscosity.

[0056] One embodiment provides that the calibration medium contains water, in particular (distilled) water.

[0057] One embodiment provides that the calibration medium contains glycerol. One embodiment provides that the calibration medium contains oil or is an oil.

[0058] In one embodiment, the procedure includes:

[0059] - Excitation of the calibration line and the measuring line to oscillate by means of the excitation system while the measuring line carries the measuring medium, in particular while the measuring medium flows through it.

[0060] In one embodiment, the procedure includes:

[0061] - Comparison of the determined calibration value with a specified value and / or specified range, in particular one provided by the factory.

[0062] The invention is explained in more detail with reference to the following figures. They show:

[0063] Fig. 1 : a longitudinal section through a Coriolis flowmeter according to the state of the art;

[0064] Fig. 2: a longitudinal section through a first embodiment of the Coriolis flowmeter according to the invention;

[0065] Fig. 3: a longitudinal section through a second embodiment of the Coriolis flowmeter according to the invention;

[0066] Fig. 4: a longitudinal section through a third embodiment of the Coriolis flowmeter according to the invention;

[0067] Fig. 5a: a representation of a calibration process of the Coriolis flowmeter;

[0068] Fig. 5b: a representation of a measuring process of the Coriolis flowmeter; and

[0069] Fig. 6 : a perspective view of a further embodiment of a Coriolis flowmeter according to the invention.

[0070] Fig. 1 shows a cross-section through a prior art Coriolis flowmeter (Fig. 5 from WO 2021 / 021116 A1). The vibronic flowmeter 500 shown comprises a measuring tube 510 for guiding the measuring medium in a flow direction 111, 112. A housing 560 is arranged on the measuring tube 510 to protect the measuring tube 510 and the components arranged in the housing. The measuring tube 510 is mechanically connected to a compensating rod 520 with a variable mass via a first coupler 570a and a second coupler 570b. The compensating rod 520 has a compensating body 522, which is designed such that a compensating medium 524 can be guided through it or into it. Like the measuring tube 510, the compensating rod 520 also extends at least partially within the housing 560.A left sensor coil 530a, a right sensor coil 530b, and a driver 540 positioned between the left and right sensor coils 530a, b are arranged between and coupled to the measuring tube 510 and the balance rod 520. The left sensor coil 530a, the right sensor coil 530b, and the driver 540 are also coupled to a measuring device electronics 550. The measuring device electronics 550 is also electrically connected to an inlet valve 520a and an outlet valve 520b, each of which is connected to the balance rod 520 and configured to admit and discharge the compensation medium 524, respectively. The measuring device electronics 550 is configured to control the inlet and outlet valves 520a, b in order to adjust the mass of the compensating rod 520 via the quantity of compensating medium 524 in the compensating body 522. When determining the mass flow of the medium, the mass of the compensating rod is kept constant over time.Unlike the present invention, the balance rod 520 is not used to (re)calibrate the Coriolis flowmeter.

[0071] Fig. 2 shows a schematic representation of a first embodiment of the Coriolis flowmeter 1 according to the invention for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a process line with a measuring system 10, a calibration system 20, a (“combination”) excitation system 30 for exciting mechanical vibrations, a (“combination”) sensor system 40 for detecting mechanical vibrations, a measuring and calibration electronics 50, and a carrier system 60 on which the (“combination”) excitation system 30, the (“combination”) sensor system 40 and the measuring and calibration electronics 50 are arranged.

[0072] The measuring system 10 has a measuring line 11 for conveying the measuring medium and a sterile measuring tube 12 that can be detachably connected to the measuring line 11. The measuring line 11 can comprise at least two process connections for connecting the measuring tube 12 to a process line or a hose system. Alternatively, the measuring line 11 can comprise an adapter that forms a transition between the measuring tube 12 and the process line or hose system. The measuring tube 12 shown is a disposable product that can be replaced whenever the measuring medium is changed. The measuring tube 12 can be made of metal, glass and / or plastic. Together, the measuring line 11 and the measuring tube 12 form a measuring channel for conveying the measuring medium.

[0073] The calibration system 20 has a calibration line 21 separate from the measuring line 11 for carrying a calibration medium, in particular water or glycerol. A calibration tube 22 arranged parallel to the measuring tube 12 is formed, in the illustrated embodiment, as an integral part of the calibration line 21. The calibration tube 22 can, for example, also be non-sterile, unlike the measuring tube 12 shown.

[0074] The measuring tube 12 and the calibration tube 22 can be identical with regard to one or more geometric parameters, in particular a (tube) length and / or a (tube) wall thickness and / or a caliber, for example they can be structurally identical. The excitation system 30 and the sensor system 40 are each connected to the measuring system 10 and to the calibration system 20. In the variant shown, the excitation system 30 and the sensor system 40 are each permanently connected to the calibration system 20 and detachably connected to the measuring system 10. Furthermore, the excitation system 30 and the sensor system 40 are permanently connected to the carrier system 60. The excitation system 30 shown can comprise at least one electromagnetic exciter, i.e., an excitation coil, which has a magnetic effect on a measuring tube magnet 12* and is configured to cause the measuring tube 12 to vibrate.The same electromagnetic exciter or a further electromagnetic exciter can be in magnetic contact with a calibration tube magnet 22* and be configured to cause the calibration tube 22 to vibrate. In the illustrated embodiment, the measuring tube magnet 12* is arranged on the measuring tube 12, and the calibration tube magnet 22* is arranged on the calibration tube 22. Alternatively, the excitation system 30 can comprise an excitation coil arranged on the calibration tube 22 and an excitation magnet attached to the measuring tube 12, which are each arranged such that they are in magnetic contact with one another when the measuring tube 12 is arranged. Alternatively, the excitation system 30 can comprise an excitation coil arranged on the measuring tube 12 and an excitation magnet attached to the calibration tube 12, which are each arranged such that they are in magnetic contact with one another when the measuring tube 12 is arranged.Likewise, the sensor system 40 can comprise one or two sensor coils arranged on the calibration tube 22 and one or two sensor magnets arranged on the measuring tube 12, each of which is arranged such that it has a magnetic effect on one another when the measuring tube 12 is arranged on the support system 60. In this case, a support system 60 would not be necessary.

[0075] The sensor system 40 can comprise at least one electrodynamic, electromagnetic, or optical sensor. In the illustrated embodiment, the sensor system 40 has a sensor coil that interacts with a measuring tube magnet 12' and a calibration tube magnet 22'. Alternatively, the sensor system can have two spaced-apart sensor coils that are positioned in or on the support system 60 such that the excitation coil is located between them. The measuring tube magnet 12' is arranged offset from the measuring tube magnet 12* on the measuring tube 12 in the longitudinal direction of the measuring tube 12. The calibration tube magnet 22' is arranged offset from the calibration tube magnet 22* on the calibration tube 22 in the longitudinal direction of the calibration tube 22.

[0076] The measuring and calibration electronics 50 is electrically connected to both the excitation system 30 and the sensor system 40 and is configured to cause both the measuring tube 12 and the calibration tube 22 to oscillate by means of the excitation system 30 and to detect the oscillation by means of the sensor system 40. Furthermore, the measuring and calibration electronics 50 is configured to determine at least one calibration variable of an overall system formed by the measuring system 10 and the calibration system 20 based on oscillations of both the measuring system 10, in particular the system carrying the measuring medium, and the calibration system 20 carrying the calibration medium, determined by means of the sensor system 40, in particular when the calibration medium is conveyed in the calibration system 20 with a predetermined (reference) mass flow and / or a predetermined (reference) density and / or a predetermined (reference) viscosity.

[0077] In the illustrated embodiment, the measurement and calibration electronics 50 are arranged on the carrier system 60. Alternatively, it can also be arranged detached from the carrier system 60 in a separate transmitter housing.

[0078] Furthermore, the measuring and calibration electronics 50 are configured, in particular based on vibrations determined by means of the sensor system 40, both of the measuring system 10 carrying the measuring medium, in particular through which the measuring medium flows, and of the calibration system 20 carrying the calibration medium, in particular to determine the mass flow, the medium density and / or the medium viscosity of the measuring medium carried in the measuring system 10 as a function of the at least one calibration variable and / or a variable derived therefrom, in particular when the measuring medium flows in the measuring system 10.

[0079] The measuring system 10 and the calibration system 20 are configured to be flowed through independently of one another by the measuring medium or calibration medium, in particular such that the measuring medium and the calibration medium flow simultaneously with differing mass flows and / or at different times through the Coriolis flowmeter 1.

[0080] The calibration system 20 further comprises a pump 24 which is configured to pump the calibration medium through the calibration line 21 at a predetermined or predeterminable mass flow, in particular such that the mass flow of the calibration medium is equal to a mass flow of the measuring medium and / or such that the mass flow of the calibration medium corresponds to a target mass flow determined based on vibrations determined by means of the sensor system 40 of both the measuring system 10 carrying the measuring medium and the calibration system 20 carrying the calibration medium.

[0081] The measuring system 10 has a measuring fastening device 25, with which the measuring tube 12 can be attached, in particular radially, to the calibration tube 22 for assembly and can be mechanically releasably connected to the calibration tube 22. Fasteners for forming a positive and / or non-positive connection are suitable as the measuring fastening device 25. Examples of such fastening devices are disclosed in WO 2019017891 A1, DE 102020114519 A1, and DE 102020127356 A1.

[0082] The above statements regarding the measuring and calibration electronics 50 also refer to the following embodiments.

[0083] Fig. 3 shows a schematic representation of a second embodiment of the Coriolis flowmeter 1 according to the invention for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a conventional process line, comprising a measuring system 10, a calibration system 20, a ("combination") excitation system 30 for exciting mechanical vibrations, a ("combination") sensor system 40 for detecting mechanical vibrations, and a support system 60. The support system 60 can be mechanically permanently or mechanically detachably connected to the calibration tube 22. The measuring line 11 and the measuring tube 12 are part of the process line in the illustrated embodiment.

[0084] The calibration system 20 has a calibration fastening device 23, with which the calibration tube 22 can be attached, in particular radially, to the measuring tube 12 or the process line for assembly and can be mechanically detachably connected to the measuring tube 12 or the process line. As a result, the support system 60 can also be at least indirectly mechanically detachably connected to the measuring system 10, in particular to the measuring tube 12.

[0085] In the illustrated embodiment, the excitation system 30 comprises a mechanical exciter that interacts mechanically with the measuring tube 12 when the calibration system 20 is mechanically connected to the measuring line 11, and continuously with the calibration tube 22 when the excitation system is permanently connected to the calibration tube 22. The sensor system 40 comprises at least one electrodynamic or optical sensor configured to detect vibration of the measuring tube 12 and the calibration tube 22.

[0086] The illustrated design is a clamp-on solution that can be arranged on existing process lines or hose systems and is designed not only to determine a process variable of the measuring medium flowing through the process line or hose system, but also to calibrate the measuring point.

[0087] Fig. 4 shows a third embodiment of the Coriolis flowmeter 1 according to the invention. In the illustrated embodiment, the measuring tube 12 and the calibration tube 22 are mechanically connected to one another, in particular non-detachably, via at least one mechanical coupler 71. The measuring tube 12 has at least one resonance frequency that is equal to a resonance frequency of the calibration tube 22, in particular such that a resonance frequency of a first-order bending vibration mode inherent in the measuring tube 12 is equal to a resonance frequency of a first-order bending vibration mode inherent in the calibration tube 22. Furthermore, the illustrated measuring tube 12 and the calibration tube 22 agree with regard to one or more geometric parameters, in particular a (tube) length and / or a (tube) wall thickness and / or a caliber. In the illustrated embodiment, the measuring tube 12 and the calibration tube 22 are structurally identical.

[0088] The measuring tube 12 and the calibration tube 22 form a tube module which is designed as a disposable article. The tube module can be mechanically detachably arranged on and detached from the support system 60 and / or the measuring line 11 and / or the calibration line. In the arranged state, the tube module, or the measuring tube 12 of the tube module, is connected to the measuring line 11, via which the measuring medium to be monitored can be introduced into the measuring tube 12 and discharged. In the arranged state, the calibration tube 22 is further connected to a calibration line 21, via which the calibration medium can be introduced into the calibration tube 22 and discharged. The support system 60 comprises a support fastening device (not shown), via which the measuring tube 12 and / or the calibration tube 22 or the tube module can be mechanically detachably connected to the support system 60. Suitable carrier fastening devices are disclosed in DE 102020114519 A1 and DE 102020127356 A1.

[0089] Fig. 5a shows a representation of the calibration process, and Fig. 5b shows the measurement process of the Coriolis flowmeter. The method for calibrating and / or operating a Coriolis flowmeter 1 according to the invention comprises the following steps:

[0090] A calibration medium is passed through the calibration line 21. A suitable calibration medium contains water - in particular distilled water - glycerol or oil. The measuring tube 12, however, remains free of the measuring medium during the calibration. Alternatively, a measuring medium, in particular a static one, can be present in the measuring tube 12 during the calibration. If the calibration medium flows at a predetermined mass flow, a calibration is performed. The predetermined mass flow of the calibration medium can be adjusted, for example by means of a pump, such that the mass flow of the calibration medium corresponds to a predetermined target mass flow and / or is equal to a mass flow of the measuring medium conducted in the measuring line 11.

[0091] For calibration, the calibration tube 22 and the measuring tube 12 are set into vibration by the excitation system 30. Furthermore, the vibration of the calibration tube 22 and the measuring tube 12 is detected by a sensor system 40 in order to determine a calibration variable as a function of an overall system represented by the measuring system 10 and the calibration system 20. Once the (re)calibration is complete, the specified mass flow of the calibration medium can be maintained or stopped. Alternatively, the calibration tube 22 can be free of the calibration medium while the mass flow, the medium density, and / or the medium viscosity of the measuring medium are being determined.

[0092] Once the calibration variable has been determined, a measuring medium with a mass flow, medium density, and / or medium viscosity to be monitored is passed through the measuring line 11 (see Fig. 5b), and the calibration line 21 and the measuring line 11 are excited to oscillate by means of the excitation system 30. Since the calibration variable is known, the mass flow, the medium density, and / or the medium viscosity of the measuring medium can be determined depending on the detection signal determined via the sensor system 40 and the determined calibration variable.

[0093] The measuring medium and calibration medium are selected to match at least one material parameter, in particular density and / or viscosity, and in particular to match such that the measuring medium is used as the calibration medium or the calibration medium corresponds to the measuring medium. This can be achieved, for example, via a bypass through which the measuring medium is fed from the process line into the calibration line, where it is used as the calibration medium.

[0094] Alternatively, the measuring medium and the calibration medium may differ from each other with regard to at least one material parameter, in particular a density and / or a viscosity.

[0095] Fig. 6 shows a perspective view of a modular Coriolis flowmeter (see Fig. 4). The modular Coriolis flowmeter comprises a tubular module M2 and a base module M1. The base module M1 comprises a (protective) housing 111 with at least one chamber 111* at least partially enclosed by a housing wall 111+. The tubular module M2 can be arranged in the chamber 111* in a mechanically fixed and yet mechanically detachable manner to form a vibration-type measuring sensor or a vibronic measuring system and / or such that the vibronic module M2 is locked in the base module M1 or is immovable.

[0096] Within the chamber 11* of the protective housing, there is at least one electrical excitation coil 112, in particular a cylindrical coil and / or an air-core coil, which is at least indirectly mechanically connected to the housing wall 111+ and electrically connected to a measuring and calibration electronics unit ME. The illustrated embodiment has two excitation coils arranged opposite one another in the chamber 111*, which are designed to excite the tubular module M2 to vibrate. Furthermore, there are at least two electrical sensor coils 114, 116, in particular placed within the chamber 111* of the (protective) housing 111, in particular each cylindrical coil and / or an air-core coil and / or structurally identical to the electrical excitation coil 112, which are positioned in particular remote from the first electrical coil and at least indirectly mechanically connected to the housing wall 111+, which are electrically connected to the measuring and calibration electronics unit ME.The at least two sensor coils 114, 116 are configured to detect the vibration of the tube module M2. The illustrated embodiment has a total of four sensor coils, which are arranged in pairs on opposite sides of the housing wall 111+.

[0097] The tube module M2 comprises a measuring tube 131 for guiding the measuring medium and a calibration tube 132 for guiding the calibration medium. An excitation magnet 122 and two sensor magnets 124, 126 are positioned on an outer surface 131+ of the measuring tube 131 such that, when the tube module M2 is arranged in the base module M1, they interact with the respective associated excitation coil or sensor coil. An excitation magnet and two sensor magnets (concealed by the calibration tube) are also positioned on an outer surface 132+ of the calibration tube 132 such that, when the tube module M2 is arranged in the base module M1, they interact with the respective associated excitation coil or sensor coil (not shown). The illustrated tube module M2, in particular the arrangement of the excitation magnets and sensor magnets, is mirror-symmetrical with respect to a longitudinal plane intersecting the tube module M2 and running between the measuring tube 131 and the calibration tube 132.The measuring and calibration electronics ME is designed to carry out method steps of the method according to the invention for calibrating and / or operating a Coriolis flowmeter.

Claims

PATENT CLAIMS 1. Coriolis flowmeter (1) for determining a mass flow, a medium density and / or a medium viscosity of a fluid measuring medium, in particular a liquid, in a process line, comprising: - a measuring system (10), wherein the measuring system (10) has a measuring line (11) for guiding the measuring medium, wherein the measuring system (10) has at least one measuring tube (12), in particular a sterile one and / or a releasably connected one to the measuring line (11) and / or a disposable one, - a calibration system (20), wherein the calibration system (20) has a calibration line (21) separate from the measuring line (11) for carrying a calibration medium, in particular water or glycerol, wherein the calibration system (20) comprises at least one calibration tube (22), in particular a non-sterile one and / or one arranged parallel to the measuring tube (12), - a (combination) excitation system (30) for exciting mechanical vibrations of both the measuring system and the calibration system; - a (combination) sensor system (40) for detecting mechanical vibrations of both the measuring system and the calibration system; wherein the excitation system (30) and the sensor system (40) are each connected, in particular detachably, to the measuring system (10) and to the calibration system (20), in particular the excitation system (30) and the sensor system (40) are each connected, preferably detachably, to the measuring system (10) and to the calibration system (20); - and a measuring and calibration electronics (50), wherein the measuring and calibration electronics (50) are electrically connected to both the excitation system (30) and the sensor system (40) and are designed to cause both the measuring tube (12) and the calibration tube (22) to oscillate by means of the excitation system (30) and to determine oscillations of the measuring tube 12 and the calibration tube 22 by means of the sensor system (40), wherein the measuring and calibration electronics (50) are designed to determine at least one calibration variable of an overall system formed by the measuring system (10) and the calibration system (20) based on values ​​determined by means of the sensor system (40). Vibrations of both the measuring system (10), in particular the one carrying the measuring medium, and the calibration system (20) carrying the calibration medium, in particular when the calibration medium is guided in the calibration system (20) with a predetermined (reference) mass flow and / or a predetermined (reference) density and / or a predetermined (reference) viscosity, and wherein the measuring and calibration electronics (50) are configured, in particular based on vibrations determined by means of the sensor system (40), of both the measuring system (10) carrying the measuring medium, in particular through which the measuring medium flows, and the calibration system (20), in particular the calibration medium, to determine the mass flow, the medium density and / or the medium viscosity of the measuring medium guided in the measuring system (10) as a function of the at least one calibration variable and / or a variable derived therefrom, in particular when the measuring medium is flowing in the measuring system (10).

2. Coriolis flowmeter (1) according to claim 1, wherein the excitation system (30) and the sensor system (40) are either each permanently connected to the measuring system (10) and detachably connected to the calibration system (20), each permanently connected to the calibration system (20) and detachably connected to the measuring system (10), or each detachably connected to the calibration system (20) and detachably connected to the measuring system (10).

3. Coriolis flowmeter (1) according to one of the preceding claims, wherein the measuring system (10) and the calibration system (20) are configured to be flowed through independently of one another by the measuring medium or calibration medium, in particular such that the measuring medium and the calibration medium flow simultaneously with differing mass flows and / or at different times through the Coriolis flowmeter (1).

4. Coriolis flowmeter (1) according to one of the preceding claims, wherein the calibration system (20) comprises a pump which is configured to pump the calibration medium through the calibration line (21) with a predetermined or predeterminable mass flow, in particular such that the mass flow of the calibration medium is equal to a mass flow of the measuring medium and / or that the mass flow of the calibration medium corresponds to a target mass flow determined based on vibrations determined by means of the sensor system (40) of both the measuring system (10) carrying the measuring medium and the calibration system (20) carrying the calibration medium.

5. Coriolis flowmeter (1) according to one of the preceding claims, wherein the calibration system (20) has a calibration fastening device (23) with which the calibration tube (22) can be attached to the measuring tube (12) for assembly, in particular radially, and can be mechanically detachably connected to the measuring tube (12).

6. Coriolis flowmeter (1) according to one of the preceding claims, wherein the measuring system (10) has a measuring fastening device (25) with which the measuring tube (12) can be attached to the calibration tube (22) for assembly, in particular radially, and can be mechanically detachably connected to the calibration tube.

7. Coriolis flowmeter (1) according to one of the preceding claims, comprising: - a carrier system (60), wherein the excitation system (30) and the sensor system (40) are connected, in particular in a non-detachable manner, to the carrier system (60).

8. Coriolis flowmeter (1) according to claim 7, wherein the measuring tube (12) and the calibration tube (22) are mechanically connected to one another, in particular non-detachably, and form a tube module, wherein the tube module can be arranged on the support system (60) in a mechanically detachable manner.

9. Coriolis flowmeter (1) according to 7 or 8, wherein the support system (60) has a support fastening device via which the measuring tube (12) and / or the calibration tube (22) can be mechanically detachably connected to the support system (60).

10. Coriolis flowmeter (1) according to one of the preceding claims, wherein the excitation system (30) comprises a mechanical exciter which is in mechanical interaction with the measuring tube (12) and the calibration tube (22).

11. Coriolis flowmeter (1) according to one of the preceding claims, wherein the excitation system (30) comprises an electromagnetic exciter which is in magnetic effect with a measuring tube magnet (12*) and a calibration tube magnet (22*), wherein the measuring tube magnet (12*) is arranged on the measuring tube (12), wherein the calibration tube magnet (22*) is arranged on the calibration tube (22).

12. Coriolis flowmeter (1) according to one of the preceding claims, wherein the sensor system (40) comprises at least one electrodynamic, electromagnetic or optical sensor.

13. Coriolis flowmeter (1) according to one of the preceding claims, wherein the measuring tube (12) and the calibration tube (22) are mechanically coupled to one another, in particular by means of mechanical couplers (71).

14. Coriolis flowmeter (1) according to one of the preceding claims, wherein the measuring tube (12) has at least one resonance frequency that is equal to a resonance frequency of the calibration tube (22), in particular such that a resonance frequency of a first-order bending vibration mode inherent in the measuring tube (12) is equal to a resonance frequency of a first-order bending vibration mode inherent in the calibration tube (22); and / or wherein the measuring tube (12) and the calibration tube (22) match with respect to one or more geometric parameters, in particular a (tube) length and / or a (tube) wall thickness and / or a caliber.

15. Coriolis flowmeter (1) according to one of the preceding claims, wherein the tube wall of the measuring tube (12) is made of a metal, in particular stainless steel; and / or wherein the tube wall of the calibration tube (22) is made of a metal, in particular stainless steel; and / or wherein the tube wall of the calibration tube (22) is made of the same material as the tube wall of the measuring tube (12); and / or wherein the measuring tube (12) and the calibration tube (22) are structurally identical to one another.

16. Coriolis flowmeter (1) according to one of the preceding claims, wherein the measuring tube (12) is part of the measuring line (11).

17. Coriolis flowmeter (1) according to one of the preceding claims, wherein the calibration tube (22) is a, in particular integral, part of the calibration line (21).

18. Coriolis flowmeter (1) according to one of the preceding claims, wherein the calibration medium differs from the measuring medium.

19. A method for calibrating and / or operating a Coriolis flowmeter (1), in particular a Coriolis flowmeter (1) according to one of the preceding claims, wherein the Coriolis flowmeter (1) comprises measuring and calibration electronics (50), a (combination) sensor system (40), a (combination) excitation system (30), a measuring system (10) with a measuring line (11) for conducting a measuring medium and a calibration system (20) with a calibration line (21) separate from the measuring line (11) for conducting a calibration medium, which method comprises the following steps: - Passing the calibration medium through the calibration line (21), - Carrying out a calibration when the calibration medium flows through the calibration line (21) at a predetermined mass flow, wherein the calibration comprises exciting the calibration line (21) and the measuring line (11) into vibrations by means of the excitation system (30), wherein the calibration comprises measuring the vibrations of the calibration tube (22) and the measuring tube (12) by means of the sensor system (40), wherein the calibration comprises determining at least one calibration variable as a function of the measured vibrations for an overall system represented by the measuring system (10) and the calibration system (20) by means of the measuring and calibration electronics (50); - passing the measuring medium through the measuring line (11); - as well as determining the mass flow, the medium density and / or the medium viscosity of the measuring medium depending on the determined calibration value.

20. The method according to claim 19, wherein the measuring tube (12) is free of the measuring medium during the calibration.

21. Method according to claim 19, wherein the measuring tube (12) carries a measuring medium, in particular a stationary one, during the calibration.

22. Method according to one of claims 19 to 21, wherein the calibration tube (22) is free of the calibration medium during the determination of the mass flow, the medium density and / or the medium viscosity of the measuring medium.

23. Method according to one of claims 19 to 22, wherein the calibration tube (22) carries a, in particular flowing, calibration medium during the determination of the mass flow, the medium density and / or the medium viscosity of the measuring medium.

24. The method according to any one of claims 19 to 23, further comprising: - Setting a mass flow of the calibration medium, in particular by means of a pump, such that the mass flow of the calibration medium corresponds to a predetermined target mass flow and / or is equal to a mass flow of the measuring medium (carried in the measuring line (11)); and / or - Using the pump to set a mass flow of the calibration medium, in particular while the measuring line (11) carries measuring medium and / or while no measuring medium flows in the measuring line (11).

25. Method according to one of claims 19 to 24, wherein the measuring medium and the calibration medium correspond with respect to at least one material parameter, in particular a density and / or a viscosity, in particular such that the measuring medium is used as the calibration medium or the calibration medium corresponds to the measuring medium.

26. Method according to one of claims 19 to 25, wherein the measuring medium and the calibration medium differ from one another with respect to at least one material parameter, in particular a density and / or a viscosity.

27. The method according to any one of claims 19 to 26, wherein the calibration medium contains water, in particular (distilled) water; and / or wherein the calibration medium contains glycerol; and / or wherein the calibration medium contains oil or is an oil.

28. The method according to any one of claims 19 to 27, further comprising: - Excitation of the calibration line (21) and the measuring line (11) to oscillate by means of the excitation system (40) while the measuring line (11) carries the measuring medium, in particular while the measuring medium flows through it.

29. Method according to one of claims 19 to 28, wherein the calibration medium differs from the measuring medium.

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