Measuring system with a vibration-type transducer

Abstract

Measuring system, in particular compact measuring device and / or Coriolis mass flow meter, for flowing media, in particular in pipelines, which measuring system comprises: - a vibration-type measuring transducer (MW) through which a medium, in particular a gas and / or a liquid, a paste or a powder or another flowable material, flows during operation to generate primary signals corresponding to parameters of the flowing medium, in particular a mass flow rate, a density and / or a viscosity, as well as converter electronics (ME) electrically coupled to the measuring transducer to control the measuring transducer and to evaluate primary signals supplied by the measuring transducer, - where the transducer -- at least one measuring tube (10; 10') for guiding flowing medium, -- at least one electromechanical, in particular electrodynamic, vibration exciter for exciting and / or maintaining vibrations of the at least one measuring tube, in particular bending vibrations of the at least one measuring tube about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube with a natural resonance frequency of the measuring transducer, -- a first vibration sensor (51), in particular an electrodynamic one, for detecting vibrations, in particular on the inlet side, of at least the at least one measuring tube and for generating a first primary signal (s) representing vibrations, in particular on the inlet side, of at least the at least one measuring tube 1 ) of the transducer, and -- a second vibration sensor (52), in particular an electrodynamic one, for detecting vibrations, in particular on the outlet side, of at least the at least one measuring tube and for generating a second primary signal (s) representing vibrations, in particular on the outlet side, of at least the at least one measuring tube 2 ) of the transducer; and - where the converter electronics -- at least one driver signal causing vibrations, in particular bending vibrations, of the at least one measuring tube (i exc ) for the vibration exciter, and -- by means of the first primary signal and by means of the second primary signal and using a Reynolds number measurement value generated during operation by means of the driver signal and representing a Reynolds number, Re, for the medium flowing in the transducer, a pressure difference measurement value (X Δp) is generated which represents a pressure difference occurring between two predetermined reference points in the flowing medium, in particular those located within the measuring transducer, in particular such that a first of the two reference points is located on the inlet side and a second of the two reference points is located on the outlet side in the measuring transducer.

Description

[0001] The invention relates to a measuring system for flowable, especially fluid, media, in particular designed as a compact measuring device and / or a Coriolis mass flow meter, which comprises a vibration-type measuring transducer through which the medium flows at least temporarily during operation and which generates primary signals influenced by at least one measured variable characterizing the flowing medium, in particular a mass flow, a density, a viscosity, etc., as well as converter electronics which are electrically coupled to the measuring transducer and process primary signals supplied by the measuring transducer into measured values.

[0002] In industrial measurement technology, particularly in connection with the control and monitoring of automated process engineering processes, to determine characteristic measured variables of media flowing in a process line, e.g., a pipeline, such measuring systems are often used. These systems, by means of a vibration-type measuring transducer and connected converter electronics, usually housed in a separate electronics housing, induce reaction forces, e.g., Coriolis forces, in the flowing medium. Derived from these, they generate measured values ​​corresponding to at least one measured variable, e.g., a mass flow rate, a density, a viscosity, or another process parameter. Such systems, often using an in-line measuring device in a compact design with an integrated measuring transducer, such as a Coriolis mass flowmeter,formed - measuring systems have been known for a long time and have proven themselves in industrial use. Examples of such measuring systems with a vibration-type transducer or individual components thereof are, for example, in EP-A 317 340, JP-A 8-136311, JP-A 9-015015, US-A 2007 / 0119264, US-A 2007 / 0119265, US-A 2007 / 0151370, US-A 2007 / 0151371, US-A 2007 / 0186685, US-A 2008 / 0034893, US-A 2008 / 0141789, US-A 46 80 974, US-A 47 38 144, US-A 47 77 833, US-A 48 01 897, US-A 48 23 614, US-A 48 79 911, US-A 50 09 109, US-A 50 24 104, US-A 50 50 439, US-A 52 91 792, US-A 53 59 881, US-A 53 98 554, US-A 54 76 013, US-A 55 31 126, US-A 56 02 345, US-A 56 91 485, US-A 57 34 112, US-A 57 96 010, US-A 57 96 011, US-A 57 96 012, US-A 58 04 741, US-A 58 61 561, US-A 58 69 770, US-A 59 45 609, US-A 59 79 246, US-A 60 47 457, US-A 60 92 429, US-A 6073495,described in US-A 63 111 36, US-B 62 23 605, US-B 63 30 832, US-B 63 97 685, US-B 65 13 393, US-B 65 57 422, US-B 66 51 513, US-B 66 66 098, US-B 66 91 583, US-B 68 40 109, US-B 68 68 740, US-B 68 83 387, US-B 70 17 424, US-B 70 40 179, US-B 70 73 396, US-B 70 77 014, US-B 70 80 564, US-B 71 34 348, US-B 72 16 550, US-B 72 99 699, US-B 73 05 892, US-B 73 60 451, US-B 73 92 709, US-B 74 06 878, WO-A 00 / 14 485, WO-A 01 / 02 816, WO-A 2004 / 072588, WO-A 2008 / 013545, WO-A 2008 / 07 7574, WO-A 95 / 29386, WO-A 95 / 16897 or WO-A 99 40 394. Each of the measuring transducers shown therein comprises at least one substantially straight or curved measuring tube accommodated in a transducer housing for guiding the, possibly also extremely fast or extremely slow flowing,Medium. During operation of the measuring system, at least one measuring tube is vibrated to generate oscillation modes influenced by the medium flowing through it.

[0003] In transducers with two measuring tubes, these are usually integrated into the process line via a flow divider on the inlet side extending between the measuring tubes and an inlet-side connection flange, and via a flow divider on the outlet side extending between the measuring tubes and an outlet-side connection flange. In transducers with a single measuring tube, the latter usually communicates with the process line via a substantially straight connecting pipe section opening on the inlet side and a substantially straight connecting pipe section opening on the outlet side.Furthermore, each of the transducers shown with a single measuring tube comprises at least one single-piece or multi-piece counteroscillator, for example, tubular, box-shaped, or plate-shaped, which is coupled to the measuring tube on the inlet side to form a first coupling zone and which is coupled to the measuring tube on the outlet side to form a second coupling zone. During operation, the counteroscillator is essentially stationary or oscillates inversely to the measuring tube, i.e., at the same frequency and in opposite phase. The inner part of the transducer, formed by the measuring tube and counteroscillator, is usually held in a protective transducer housing solely by means of the two connecting tube pieces through which the measuring tube communicates with the process line during operation, particularly in a manner that enables oscillations of the inner part relative to the measuring tube.In the measuring transducers shown, for example, in US-A 52 91 792, US-A 57 96 010, US-A 59 45 609, US-B 70 77 014, US-A 2007 / 0119264, WO-A 01 02 816, or WO-A 99 40 394, with a single, essentially straight measuring tube, the latter and the counteroscillator are aligned essentially coaxially with one another, as is quite common in conventional measuring transducers. In commercially available measuring transducers of the aforementioned type, the counteroscillator is usually also essentially tubular and designed as a substantially straight hollow cylinder, which is arranged in the measuring transducer such that the measuring tube is at least partially encased by the counteroscillator. The materials used for such counter-oscillators are usually comparatively inexpensive steel grades, such as structural steel or free-cutting steel, especially when titanium, tantalum or zirconium are used for the measuring tube.

[0004] For transducers with curved measuring tubes, e.g., U-, V-, or Ω-shaped, the excited oscillation mode—the so-called useful mode—is typically chosen as the natural oscillation mode in which the measuring tube oscillates at least partially at a lowest natural resonance frequency around an imaginary longitudinal axis of the transducer, like a cantilever clamped at one end, thereby inducing Coriolis forces in the flowing medium that are dependent on the mass flow rate. These forces, in turn, lead to the excited oscillations of the useful mode—in the case of curved measuring tubes, pendulum-like cantilever oscillations—being superimposed with equal-frequency bending oscillations according to at least one second, equally natural oscillation mode, the so-called Coriolis mode.In transducers with a curved measuring tube, these cantilever oscillations in the Coriolis mode, forced by Coriolis forces, usually correspond to the natural vibration mode in which the measuring tube also performs torsional vibrations about an imaginary vertical axis oriented perpendicular to the longitudinal axis. In transducers with a straight measuring tube, however, in order to generate mass flow-dependent Coriolis forces, a useful mode is often selected in which the measuring tube at least partially performs bending vibrations essentially in a single imaginary vibration plane, so that the oscillations in the Coriolis mode are coplanar with the useful mode oscillations and have the same oscillation frequency. Due to the superposition of the useful and Coriolis modes, the oscillations of the vibrating measuring tube detected by the sensor arrangement on the inlet and outlet sides exhibit a measurable phase difference that also depends on the mass flow.Typically, the measuring tubes of such transducers, e.g. those used in Coriolis mass flowmeters, are excited during operation at a momentary natural resonance frequency of the oscillation mode selected for the desired mode, particularly with a constantly controlled oscillation amplitude. Since this resonance frequency is particularly dependent on the instantaneous density of the medium, commercially available Coriolis mass flowmeters can be used to measure not only the mass flow but also the density of flowing media. Furthermore, it is also possible, as shown, for example, in US-B 66 51 513 or US-B 70 80 564, to directly measure the viscosity of the flowing medium using vibration-type transducers, for example based on the excitation energy required to maintain the oscillations.Excitation power and / or based on a damping of vibrations of the at least one measuring tube resulting from a dissipation of vibration energy, in particular those in the aforementioned useful mode. Furthermore, other measured variables derived from the aforementioned primary measured values ​​of mass flow rate, density, and viscosity, such as the Reynolds number according to US-B 65 13 393, can also be determined.

[0005] To excite vibrations of the at least one measuring tube, vibration-type measuring transducers further comprise an exciter arrangement controlled during operation by an electrical driver signal generated by the aforementioned driver electronics and appropriately conditioned, e.g., a regulated current. This exciter arrangement excites the measuring tube to bending vibrations in the useful mode by means of at least one electromechanical, particularly electrodynamic, vibration exciter through which a current flows during operation and acts practically directly on the measuring tube. Furthermore, such measuring transducers comprise a sensor arrangement with, particularly electrodynamic, vibration sensors for at least selectively detecting inlet-side and outlet-side vibrations of the at least one measuring tube, particularly those in the Coriolis mode, and for generating electrical sensor signals influenced by the process parameter to be detected, such as mass flow or density, which serve as primary signals of the measuring transducer.As described, for example, in US-B 72 16 550, in measuring transducers of the type in question, the vibration exciter can optionally also be used, at least temporarily, as a vibration sensor and / or a vibration sensor can be used, at least temporarily, as a vibration exciter. The exciter arrangement of measuring transducers of the type in question typically comprises at least one vibration exciter acting electrodynamically and / or differentially on the at least one measuring tube and the possibly present counter-oscillator or the possibly present other measuring tube, while the sensor arrangement comprises an inlet-side, usually also electrodynamic, vibration sensor and at least one essentially identically constructed outlet-side vibration sensor.Such electrodynamic and / or differential vibration exciters of commercially available vibration-type measuring transducers are formed by a magnetic coil through which a current flows at least temporarily – in the case of measuring transducers with a measuring tube and a counteroscillator coupled to it, usually fixed to the latter – and a rather elongated, particularly rod-shaped, permanent magnet that interacts with the at least one magnetic coil, particularly immersed in it, and serves as an armature. The permanent magnet and the magnetic coil serving as the excitation coil are usually aligned such that they run essentially coaxially with one another. Furthermore, in conventional measuring transducers, the excitation arrangement is usually designed and positioned in the measuring transducer such that it engages the at least one measuring tube essentially centrally.In this case, the vibration exciter and, to that extent, the exciter arrangement, as shown, for example, in the measuring transducers proposed in US-A 57 96 010, US-B 68 40 109, US-B 70 77 014 or US-B 70 17 424, is usually fixed to the outside of the measuring tube at least at certain points along an imaginary central circumferential line of the latter. As an alternative to an excitation arrangement formed by means of vibration exciters acting centrally and directly on the measuring tube, it is also possible, as proposed in US-B 65 57 422, US-A 60 92 429 or US-A 48 23 614, for example, to use two excitation arrangements not formed in the center of the measuring tube, but rather on the inlet or outlet side of the latter, or, as proposed in US-B 62 23 605 or US-A 55 31 126, for example, to use an excitation arrangement formed between the possiblyExcitation arrangements formed by the existing counteroscillator and the vibration exciter acting on the transducer housing can be used. In most commercially available vibration-type transducers, the vibration sensors of the sensor arrangement are, as already indicated, essentially identical in design to the at least one vibration exciter, at least insofar as they operate according to the same operating principle. Accordingly, the vibration sensors of such a sensor arrangement are usually each formed by at least one permanent-magnetic armature - usually fixed to the possibly present counteroscillator - which is at least temporarily permeated by a variable magnetic field and thus at least temporarily subjected to an induced measuring voltage, as well as a permanent-magnetic armature fixed to the measuring tube and interacting with the at least one coil, which supplies the magnetic field.Each of the aforementioned coils is also connected to the aforementioned converter electronics of the in-line measuring device by means of at least one pair of electrical connecting lines, which are usually routed along the shortest possible path from the coils via the counteroscillator to the measuring transducer housing.

[0006] As discussed, inter alia, in the above-mentioned US-B 74 06 878, US-B 73 05 892, US-B 71 34 348, US-B 65 13 393, US-A 58 61 561, US-A 53 59 881 and WO-A 2004 / 072588, another parameter that is quite relevant for the operation of the measuring system as such and / or for the operation of the plant in which the measuring system is installed can be a pressure loss in the flow - for example, caused by the measuring transducer and, to that extent, the measuring system itself; This is particularly true if the medium is two- or multi-phase, for example as a liquid-gas mixture, and / or if undesirable cavitation is to be expected during operation as a result of the flowing medium falling below a minimum static pressure or if this must be avoided at all costs.In the measuring systems shown in US-A 53 59 881 or US-B 74 06 878, a pressure difference falling across the measuring transducer during operation is determined, for example, by a first static pressure in the flowing medium being detected at a first pressure measuring point in the inlet area of ​​the measuring transducer or immediately upstream thereof by means of a first pressure sensor and a second static pressure in the flowing medium being detected at a second pressure measuring point in the outlet area of ​​the measuring transducer or immediately downstream thereof by means of an additional second pressure sensor. This pressure is then converted into a corresponding pressure difference measured value by means of a hydraulic pressure measuring device and / or the respective converter electronics. In US-B 73 05 892 orUS-B 71 34 348 further describes a method for measuring a pressure difference which can be carried out by means of a vibration-type measuring transducer, in which method a pressure or a pressure drop in the medium flowing through the measuring transducer is determined on the basis of a vibration response of the at least one measuring tube to a multimodal vibration excitation and physical-mathematical models stored in the transducer electronics for a dynamics of the measuring system - designed here as a Coriolis mass flow meter.

[0007] However, one disadvantage of the state-of-the-art solutions for pressure measurement, particularly for pressure difference measurement, using vibration-type transducers is that either modified excitation arrangements and / or modified driver electronics must be used, or additional pressure sensors must be provided. This can significantly increase both the design effort of the measuring system itself and the experimental effort required to calibrate such measuring systems, since the underlying physical and mathematical models for pressure or pressure difference measurement are very complex in order to achieve high measurement accuracy and thus require a large number of additional coefficients to be calibrated, possibly even during a wet calibration performed on-site on the installed measuring system.

[0008] One object of the invention is therefore to improve measuring systems formed by means of vibration-type measuring transducers in such a way that a sufficiently accurate measurement of a pressure difference in the flowing medium is possible, at least for the purposes of detecting or alarming undesirably high pressure drops in the flowing medium, and possibly also a highly precise measurement in the sense of generating validated measured values; this is particularly also possible using the measuring technology proven in such measuring systems, such as established vibration sensors and / or actuators, or also proven technologies and architectures of established converter electronics.

[0009] To achieve this object, the invention consists in a measuring system, for example a compact measuring device and / or Coriolis mass flow meter, for media flowing, for example, in pipelines. This measuring system comprises a vibration-type measuring transducer through which a medium, for example a gas and / or a liquid, a paste or a powder or another flowable material, flows during operation, for generating primary signals corresponding to parameters of the flowing medium, for example a mass flow rate, a density and / or a viscosity, as well as converter electronics (ME) electrically coupled to the measuring transducer for controlling the measuring transducer and for evaluating primary signals supplied by the measuring transducer. The measuring transducer has at least one measuring tube for guiding the flowing medium, at least one electromechanical, for example electrodynamic,Vibration exciter for exciting and / or maintaining vibrations of the at least one measuring tube, for example bending vibrations of the at least one measuring tube about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube with a natural resonance frequency of the measuring transducer, a, for example electrodynamic, first vibration sensor for detecting, for example inlet-side, vibrations of at least the at least one measuring tube and for generating a, for example inlet-side, vibrations of at least the at least one measuring tube first primary signal of the measuring transducer representing, for example inlet-side, vibrations of at least the at least one measuring tube, and a, for example electrodynamic, second vibration sensor for detecting, for example outlet-side, vibrations of at least the at least one measuring tube and for generating a, for example outlet-side,The second primary signal of the measuring transducer represents vibrations of at least one measuring tube. The converter electronics, in turn, supplies at least one driver signal for the vibration exciter, causing vibrations, for example, bending vibrations, of the at least one measuring tube. Using the first primary signal and the second primary signal, as well as a Reynolds number measurement value generated during operation by the driver signal and representing a Reynolds number, Re, for the medium flowing in the measuring transducer, generates a pressure difference measurement value that represents a pressure difference occurring in the flowing medium between two predetermined reference points, for example, located within the measuring transducer, for example, such that a first of the two reference points is located on the inlet side and a second of the two reference points is located on the outlet side of the measuring transducer.

[0010] Furthermore, the invention consists in a method for measuring a pressure difference occurring within a flowing medium using the above-mentioned measuring system, which method comprises the following steps: Allowing the medium to flow through at least one measuring tube; Generating a Reynolds number measurement value representing a Reynolds number, Re, for the flowing medium, and Using the Reynolds number measurement value to generate a pressure difference measurement value that represents a pressure difference occurring between two reference points in the flowing medium, for example, located within the transducer.

[0011] According to a first embodiment of the measuring system of the invention, it is further provided that the converter electronics generates the Reynolds number measurement value by means of the driver signal.

[0012] According to a second embodiment of the measuring system of the invention, it is further provided that the converter electronics generates the Reynolds number measurement value by means of the first primary signal and / or by means of the second primary signal.

[0013] According to a third embodiment of the measuring system of the invention, it is further provided that the transducer electronics generate the pressure difference measured value using a viscosity measured value, which is stored internally, for example, in a volatile data memory of the transducer electronics and / or generated during operation by means of the driver signal and / or by means of at least one of the primary signals, which represents a viscosity, η, of the medium flowing in the measuring transducer. Further developing this embodiment of the invention, it is further provided that the transducer electronics generate the viscosity measured value using the driver signal and / or that the transducer electronics generate the viscosity measured value using the first primary signal and / or the second primary signal.

[0014] According to a fourth embodiment of the measuring system of the invention, it is further provided that the transmitter electronics for determining the pressure difference measured value by means of the first primary signal and by means of the second primary signal generates a phase difference measured value which represents a phase difference, Δφ, existing between the first primary signal and the second primary signal, for example, dependent on a mass flow rate, m , of medium flowing in the measuring transducer. l , represents.

[0015] According to a fifth embodiment of the measuring system of the invention, it is further provided that the transmitter electronics generates a frequency measurement value for determining the pressure difference measurement value and / or for generating a density measurement value representing a density, ρ, of medium flowing in the measuring transducer, based on at least one of the primary signals and / or based on the at least one driver signal, which frequency measurement value represents an oscillation frequency, f exc, of vibrations of the at least one measuring tube, for example of bending vibrations of the at least one measuring tube about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube with a natural resonance frequency of the measuring transducer.

[0016] According to a sixth embodiment of the measuring system of the invention, it is further provided that the transmitter electronics generates a mass flow measurement value for determining the pressure difference measurement value by means of the first primary signal and by means of the second primary signal, which represents a mass flow rate, m , of medium flowing in the measuring transducer,

[0017] According to a seventh embodiment of the measuring system of the invention, it is further provided that the converter electronics generates the Reynolds number measured value using a mass flow measured value representing a mass flow rate, m , of medium flowing in the measuring transducer.

[0018] According to an eighth embodiment of the measuring system of the invention, it is further provided that the converter electronics generates the Reynolds number measured value using a viscosity measured value representing a viscosity, η, of the medium flowing in the measuring transducer.

[0019] According to a ninth embodiment of the measuring system of the invention, it is further provided that the converter electronics generates the Reynolds number measured value using both a mass flow measured value representing a mass flow rate, m , of medium flowing in the measuring transducer and a viscosity measured value representing a viscosity, η, of medium flowing in the measuring transducer.

[0020] According to a tenth embodiment of the measuring system of the invention, it is further provided that the transmitter electronics generates the pressure difference measured value using a density measured value, which is stored internally, for example, in a volatile data memory of the transmitter electronics and / or generated during operation by means of the driver signal and / or by means of at least one of the primary signals, and which represents a density, ρ, of medium flowing in the measuring transducer.

[0021] According to an eleventh embodiment of the measuring system of the invention, it is further provided that the converter electronics for determining the pressure difference measured value by means of the first primary signal and by means of the second primary signal generates a flow energy measured value which is a kinetic energy, ρU, dependent on a density, ρ, and a flow velocity, U, of the medium flowing in the measuring transducer 2 , represented by the medium flowing in the transducer.

[0022] According to a twelfth embodiment of the measuring system of the invention, it is further provided that the transducer electronics generates a pressure drop coefficient for determining the pressure difference measured value, which represents a pressure drop across the transducer dependent on the instantaneous Reynolds number, Re, of the flowing medium, related to an instantaneous kinetic energy of the medium flowing in the transducer.

[0023] According to a thirteenth embodiment of the measuring system of the invention, it is further provided that the transmitter electronics, using the pressure difference measured value and based on a first pressure measured value, for example, stored internally in a volatile data memory of the transmitter electronics, which represents a first pressure prevailing in the flowing medium, for example upstream of an outlet end of the measuring transducer and / or downstream of an inlet end of the measuring transducer, for example measured by means of a pressure sensor communicating with the transmitter electronics and / or determined by means of the first and second primary signals of the measuring transducer, generates a second pressure measured value, which represents a static pressure, for example, minimal and / or classified as critical for the measuring system, p krit, within the flowing medium. Further developing this embodiment of the invention, it is further provided that the transmitter electronics generate an alarm using the second pressure measurement value, which signals, for example, visually and / or acoustically, when the pressure in the medium falls below a predefined, minimum permissible static pressure; and / or that the transmitter electronics generate an alarm using the second pressure measurement value, which signals, for example, the impending occurrence of cavitation in the medium, for example, visually and / or acoustically.

[0024] According to a fourteenth embodiment of the measuring system of the invention, in order to generate a pressure measurement value representing a static pressure prevailing in the flowing medium, it further comprises a pressure sensor which serves to detect a static pressure prevailing in a pipeline carrying the medium, for example upstream of an inlet end of the measuring transducer or downstream of an outlet end of the measuring transducer, and which communicates with the converter electronics during operation.

[0025] According to a fifteenth embodiment of the measuring system of the invention, it is further provided that the transducer electronics generate an alarm using the pressure difference measured value, which signals an exceeding of a predefined, maximum permissible reduction in static pressure in the medium flowing through the transducer, for example visually and / or acoustically perceptible; and / or that the transducer electronics generate an alarm using the pressure difference measured value, which signals an excessive pressure drop in the medium provoked by the transducer, for example visually and / or acoustically perceptible.

[0026] According to a sixteenth embodiment of the invention, it is further provided that the measuring transducer further comprises a measuring transducer housing with an inlet-side first housing end, in particular having a connection flange for a line segment supplying the measuring transducer, and an outlet-side second housing end, in particular having a connection flange for a line segment discharging the medium from the measuring transducer. Further developing this embodiment of the invention, it is further provided that the inlet-side first housing end of the measuring transducer housing is formed by means of an inlet-side first flow divider having two spaced-apart flow openings, and the outlet-side second housing end of the measuring transducer housing is formed by means of an outlet-side second flow divider having two spaced-apart flow openings, and that the measuring transducer has two parallel measuring tubes for guiding flowing medium.of which a first measuring tube opens with an inlet-side first measuring tube end into a first flow opening of the first flow divider and with an outlet-side second measuring tube end into a first flow opening of the second flow divider, and a second measuring tube opens with an inlet-side first measuring tube end into a second flow opening of the first flow divider and with an outlet-side second measuring tube end into a second flow opening of the second flow divider.

[0027] According to a first embodiment of the method of the invention, this further comprises steps of exciting the at least one measuring tube to vibrate, for example bending vibrations about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube; and of generating a first primary signal representing inlet-side vibrations of at least the at least one measuring tube and a second primary signal representing outlet-side vibrations of at least the at least one measuring tube. Further developing this embodiment of the invention, the method further comprises a step of using the first primary signal and / or the second primary signal to generate the Reynolds number measured value, in particular.also for generating a density measurement value representing a density of the flowing medium and / or for generating a mass flow measurement value representing a mass flow rate of the flowing medium.

[0028] A basic idea of ​​the invention is to determine a pressure difference as a further measured variable of interest using a few measured values ​​established for the measurement of flowing media, such as the mass flow rate, the density, the viscosity and / or the Reynolds number, which are typically present anyway in measuring systems of the type in question, in particular are also determined internally, and / or using a few operating parameters typically generated internally by the converter electronics of such measuring systems, such as a phase difference between the primary signals representing the inlet and outlet oscillations of the at least one measuring tube, their signal frequency and / or amplitude, or those typically derived therefrom anyway. The invention is also based on the surprising finding that even solely on the basis of the aforementioned operating parameters orFrom the derived measured values, which are typically determined anyway in measuring systems of the type in question, as well as from a few measuring system-specific fixed values ​​to be determined in advance - for example, during a wet calibration that is to be carried out anyway - pressure differences in the medium flowing through the measuring transducer can be determined with a sufficiently good measuring accuracy, even for the purpose of alarming critical operating conditions, such as cavitation in the flowing medium; this can also be done over a very wide Reynolds number range, i.e. for both laminar and turbulent flow. A particular advantage of the invention is that, to implement the pressure difference measurement according to the invention, both tried-and-tested conventional measuring transducers and tried-and-tested conventional converter electronics can be used - of course, with the software implemented for the evaluation being adapted accordingly.

[0029] The invention and further advantageous embodiments thereof are explained in more detail below using exemplary embodiments illustrated in the figures of the drawing. Identical parts are provided with the same reference numerals in all figures; where clarity requires it or it otherwise seems expedient, previously mentioned reference numerals are omitted in subsequent figures. Further advantageous embodiments or developments, in particular combinations of partial aspects of the invention initially explained only individually, will become apparent from the figures of the drawing as well as from the dependent claims themselves.

[0030] In detail: Fig. 1a, b a variant of a measuring system designed as a compact measuring device for media flowing in pipelines in different side views; Fig. 2a, b show a further variant of a measuring system designed as a compact measuring device for media flowing in pipelines in different side views; Fig. 3 schematically in the form of a block diagram, in particular also for a measuring system according to the Fig. 1a, Fig. 1b, Fig. 2a, Fig. 2b, suitable converter electronics with connected vibration type transducer; Fig. 4, Fig. 5 in partially sectioned and perspective views a variant of a measuring system according to the Fig. 1a, Fig. 1b suitable vibration type transducer; Fig. 6, Fig. 7 in partially sectioned and perspective views a further variant of a measuring system according to the Fig. 2a, Fig. 2b suitable vibration type transducer; Fig. 8 to 10 Results of experimental investigations carried out in connection with the invention, in particular using computer-based simulation programs and / or by means of real measuring systems in the laboratory, or results derived therefrom, for the determination of a pressure difference in a chamber formed by a vibration-type measuring transducer - for example according to Fig. 4, Fig. 5 or 6, Fig. 7 - characteristic curves serving the flowing medium; and Fig. 11 experimentally determined pressure loss profiles, in particular using computer-based simulation programs, in a conventional vibration-type transducer.

[0031] In the Fig. 1a, Fig. 1b or 2a, Fig. 2b shows a variant of a measuring system for flowable, in particular fluid, media, which can be inserted into a process line, for example a pipeline of an industrial plant, for example formed by a Coriolis mass flow meter, density meter, viscosity meter or the like, which system serves in particular to measure and / or monitor a pressure difference of a medium flowing in the process line, possibly also to measure and / or monitor at least one further physical measured variable of the medium, such as a mass flow rate, a density, a viscosity or the like.The measuring system – implemented here using a compact in-line measuring device – comprises a vibration-type measuring transducer MW connected to the process line via an inlet end #111 and an outlet end #112. During operation, the medium to be measured, such as a low-viscosity liquid and / or a high-viscosity paste and / or a gas, flows through this measuring transducer and is connected to a converter electronics ME of the measuring system, which is supplied with electrical energy externally via a connecting cable and / or by means of an internal energy storage device. This has, as shown in . Fig. 3 schematically depicted in the form of a block diagram, a driver circuit Exc serving to control the measuring transducer and a measuring and evaluation circuit µC of the measuring system processing primary signals of the measuring transducer MW, formed, for example, by means of a microcomputer and / or communicating with the driver circuit Exc during operation, are electrically connected, which during operation supplies measured values ​​representing at least one measured variable, such as the instantaneous or totalized mass flow. The driver circuit Exc and the evaluation circuit µC as well as further electronic components of the converter electronics serving to operate the measuring system, such as internal power supply circuits NRG for providing internal supply voltages U Nand / or the connection to a higher-level measurement data processing system and / or a fieldbus serving communication circuits COM, are further accommodated in a corresponding, in particular impact- and / or explosion-proof and / or hermetically sealed, electronics housing 200. For the visualization of measured values ​​generated internally by the measuring system and / or possibly status messages generated internally by the measuring system, such as an error message or an alarm, on site, the measuring system can further have a display and control element HMI that communicates at least temporarily with the converter electronics, such as an LCD, OLED or TFT display placed in the electronics housing behind a correspondingly provided window therein, as well as a corresponding input keyboard and / or a touchscreen.The programmable and / or remotely parameterizable converter electronics ME can also be designed such that, during operation of the in-line measuring device, it can exchange measurement and / or other operating data with a higher-level electronic data processing system, for example a programmable logic controller (PLC), a personal computer and / or a workstation, via a data transmission system, for example a fieldbus system and / or wirelessly via radio, such as current measured values ​​or setting and / or diagnostic values ​​used to control the in-line measuring device. The converter electronics ME can, for example, have such an internal power supply circuit NRG, which is fed during operation by an external power supply provided in the data processing system via the aforementioned fieldbus system.According to one embodiment of the invention, the converter electronics are further configured such that they can be electrically connected to the external electronic data processing system by means of a two-wire connection 2L, configured, for example, as a 4-20 mA current loop, and can be supplied with electrical power via this connection and transmit measured values ​​to the data processing system. If the measuring system is intended for connection to a fieldbus or other communication system, the converter electronics ME can have a corresponding communication interface COM for data communication in accordance with one of the relevant industry standards. The electrical connection of the measuring transducer to the aforementioned converter electronics can be established by means of corresponding connecting cables that are routed out of the electronics housing 200, for example, via a cable feedthrough, and are laid at least partially within the measuring transducer housing.The connecting lines can be formed, at least in part, as electrical conductors, at least partially covered by electrical insulation, e.g., in the form of twisted pair cables, ribbon cables, and / or coaxial cables. Alternatively or additionally, the connecting lines can also be formed, at least in part, by conductor tracks of a printed circuit board, especially a flexible one, possibly coated. See also the aforementioned US-B 67 11 958 or US-A 53 49 872.

[0032] In the Fig. 4 and Fig. 5 or 6 and Fig. 7, a first and a second exemplary embodiment of a vibration-type measuring transducer MW suitable for implementing the measuring system are schematically shown for further explanation of the invention. The measuring transducer MW generally serves to generate mechanical reaction forces, e.g. mass flow-dependent Coriolis forces, density-dependent inertial forces and / or viscosity-dependent friction forces, in a medium flowing through it, such as a gas and / or a liquid, which react measurably, in particular detectably, on the measuring transducer. Derived from these reaction forces, a mass flow m, a density ρ and / or a viscosity η of the medium can thus be measured. Each of the measuring transducers comprises an internal part arranged in a measuring transducer housing 100, which actually effects the physical-electrical conversion of the at least one parameter to be measured.In addition to accommodating the internal part, the transducer housing 100 can also be used to hold the electronics housing 200 of the in-line measuring device with the driver and evaluation circuitry housed therein.

[0033] To guide flowing medium, the inner part of the measuring transducer generally comprises at least a first - in the Fig. 4 and Fig. 5, a single measuring tube 10 is curved at least in sections, which extends between a first measuring tube end 11# on the inlet side and a second measuring tube end 12# on the outlet side with an oscillating length. To generate the aforementioned reaction forces, it is vibrated during operation at least over its oscillating length and, in the process, is repeatedly elastically deformed while oscillating around a static rest position. The oscillating length corresponds to the length of an imaginary center line or center of gravity (an imaginary connecting line through the centers of gravity of all cross-sectional areas of the measuring tube) running within the lumen; in the case of a curved measuring tube, this corresponds to an extended length of the measuring tube 10.

[0034] It should be expressly pointed out at this point that - although the measuring transducer in the Fig. 4 and Fig. 5 has only a single curved measuring tube and at least insofar as its mechanical construction and its operating principle are similar to those proposed in US-B 73 60 451 or US-B 66 66 098 or also to the measuring transducers commercially offered by the applicant under the type designation "PROMASS H", "PROMASS P" or "PROMASS S" - to implement the invention, measuring transducers with a straight and / or more than one measuring tube can of course also be used, comparable to those in the aforementioned US-A 60 06 609, US-B 65 13 393, US-B 70 17 424, US-B 68 40 109, US-B 69 20 798, US-A 57 96 011, US-A 57 31 527 or US-A 56 02 345 or, for example, the measuring transducers offered for sale by the applicant under the type designation “PROMASS I”, “PROMASS M” or “PROMASS E” or “PROMASS F”, each with two parallel measuring tubes.Accordingly, the measuring transducer can also have a single straight measuring tube or at least two measuring tubes for guiding the medium to be measured, which are mechanically coupled to one another and / or are of identical construction and / or are curved and / or are parallel to one another, for example by means of an inlet-side flow divider and an outlet-side flow divider, if necessary additionally also by means of at least one inlet-side coupling element and at least one outlet-side coupling element, and which vibrate at least temporarily during operation to generate the primary signals, for example at the same frequency on a common oscillation frequency, but in antiphase to one another. According to a development of the invention, the measuring transducer comprises, as shown for example in . Fig. 6 and Fig. 7 schematically shown, therefore, in addition to the first measuring tube 10, a second measuring tube 10', which is mechanically connected to the first measuring tube 10 by means of a, for example, plate-shaped, first coupler element to form a first coupling zone on the inlet side and by means of a second coupler element to form a second coupling zone on the outlet side, for example, plate-shaped and / or identical to the first coupler element. In this case too, the first coupling zone defines a respective inlet-side first measuring tube end 11#, 11'# of each of the two measuring tubes 10, 10' and the second coupling zone defines a respective outlet-side second measuring tube end 12#, 12'# of each of the two measuring tubes 10, 10'. Since, in the event that the inner part is formed by means of two measuring tubes, each of the two, in particularIn a further embodiment of this second variant of the measuring transducer according to the invention, each of the two measuring tubes opens on the inlet side into one of two spaced-apart flow openings of a first flow divider 15 serving to divide the inflowing medium into two partial flows, and on the outlet side into one of two spaced-apart flow openings of a second flow divider 16 serving to recombine the partial flows, so that the medium flows through both measuring tubes simultaneously and in parallel during operation of the measuring system. Fig. 6 and Fig. In the embodiment shown in Figure 7, the flow dividers are an integral part of the transducer housing in that an inlet-side first housing end defining the inlet end #111 of the transducer is formed by means of the first flow divider and an outlet-side second housing end defining the outlet end #112 of the transducer is formed by means of the second flow divider.

[0035] As can be seen from the summary of Fig. 4 and Fig. 5 or 6 and Fig. 7, the at least one measuring tube 10 is shaped such that the aforementioned center line, as is quite common with measuring transducers of the type in question, lies in an imaginary tube plane of the measuring transducer. According to one embodiment of the invention, the at least one measuring tube 10 is vibrated during operation such that it oscillates about an axis of oscillation, in particular in a bending vibration mode, which is parallel or coincident with an imaginary connecting axis imaginarily connecting the two measuring tube ends 11#, 12#. The at least one measuring tube 10 is further shaped and arranged in the measuring transducer such that the aforementioned connecting axis runs essentially parallel to an imaginary longitudinal axis L of the measuring transducer imaginarily connecting the inlet and outlet ends of the measuring transducer, and possibly also coincides therewith.

[0036] The at least one measuring tube 10 of the measuring transducer, made for example of stainless steel, titanium, tantalum or zirconium or an alloy thereof, and in this respect also an imaginary center line of the measuring tube 10 running within lumens, can be, for example, essentially U-shaped or, as also in the Fig. 4 and Fig. 5 or 6 and Fig. 7 or also Fig. 8, be essentially V-shaped. Since the measuring transducer is intended to be usable for a wide variety of applications, particularly in the field of industrial measurement and automation technology, it is further provided that the measuring tube has a diameter ranging between approximately 1 mm and approximately 100 mm, depending on the use of the measuring transducer.

[0037] To minimize interferences acting on the inner part formed by a single measuring tube as well as to reduce the total vibration energy emitted by the respective measuring transducer to the connected process line, the inner part of the measuring transducer comprises, in accordance with the Fig. 4 and Fig. 5 further comprises a counter-oscillator 20 which is mechanically coupled to the measuring tube 10 - the only curved one here - and which, for example, is U- or V-shaped similar to the measuring tube. This counter-oscillator is, as in Fig. 2, arranged laterally spaced from the measuring tube 10 in the measuring transducer and fixed to the measuring tube 10 to form a first coupling zone on the inlet side, which ultimately defines the aforementioned first measuring tube end 11#, and a second coupling zone on the outlet side, which ultimately defines the aforementioned second measuring tube end 12#. The counteroscillator 20, which here runs essentially parallel to the measuring tube 10 and is possibly also arranged coaxially thereto, is made of a metal compatible with the measuring tube in terms of thermal expansion behavior, such as steel, titanium or zirconium, and can, for example, be tubular or essentially box-shaped. As in Fig. 2 or also proposed in US-B 73 60 451, the counteroscillator 20 can be formed, for example, by means of plates arranged on the left and right sides of the measuring tube 10 or also by means of blind tubes arranged on the left and right sides of the measuring tube 10. Alternatively, the counteroscillator 20 can also be formed - as proposed in US-B 66 66 098 - by means of a single blind tube running parallel to the side of the measuring tube. As can be seen from a summary of the Fig. 2 and Fig. 3, the counteroscillator 20 in the embodiment shown here is mounted by means of at least one inlet-side first coupler 31 at the first measuring tube end 11# and by means of at least one outlet-side second coupler 32, which is essentially identical to the coupler 31, at the second measuring tube end 12#. Simple node plates can serve as couplers 31, 32, for example, which are fastened in a corresponding manner on the inlet side and outlet side to the measuring tube 10 and counteroscillator 20. Furthermore, as in the Fig. 2 and Fig. 3, a completely closed box or possibly also a partially open frame formed by means of node plates spaced apart in the direction of the imaginary longitudinal axis L of the transducer together with projecting ends of the counteroscillator 20 on the inlet side and outlet side respectively, can serve as coupler 31 or as coupler 32. As shown in the Fig. 2 and Fig. 3, the measuring tube 10 is further connected to the process line (not shown) supplying or discharging the medium via a straight first connecting pipe section 11 opening into the region of the first coupling zone on the inlet side and a straight second connecting pipe section 12 opening into the region of the second coupling zone on the outlet side, in particular essentially identical to the first connecting pipe section 11, wherein an inlet end of the inlet-side connecting pipe section 11 practically forms the inlet end of the measuring transducer and an outlet end of the outlet-side connecting pipe section 12 forms the outlet end of the measuring transducer. Advantageously, the measuring tube 10 and together with the two connecting pipe sections 11, 12 can be designed in one piece, so that for their production, for example, a single tubular semi-finished product made of a material customary for such measuring transducers, such asStainless steel, titanium, zirconium, tantalum or corresponding alloys thereof. Instead of the measuring tube 10, inlet tube section 11 and outlet tube section 12 each being formed by segments of a single, one-piece tube, these can, if necessary, also be manufactured using individual, subsequently joined, e.g. welded, semi-finished products. In the . Fig. 2 and Fig. 3, it is further provided that the two connecting pipe sections 11, 12 are aligned with one another and with an imaginary longitudinal axis L of the measuring transducer imaginarily connecting the two coupling zones 11#, 12#, such that the inner part formed here by means of counter-oscillator and measuring tube, accompanied by twisting of the two connecting pipe sections 11, 12, can oscillate about the longitudinal axis L. For this purpose, the two connecting pipe sections 11, 12 are to be aligned with one another such that the essentially straight pipe segments run essentially parallel to the imaginary longitudinal axis L or to the imaginary oscillation axis of the bending oscillations of the measuring tube, such that the pipe segments are essentially aligned both with the longitudinal axis L and with one another.Since the two connecting pipe sections 11, 12 in the embodiment shown here are essentially straight over their entire length, they are accordingly essentially aligned with one another and with the imaginary longitudinal axis L. As can be seen from the . Fig. 2 and Fig. 3, the transducer housing 100, which is particularly rigid and flexurally and torsionally stiff compared to the measuring tube 10, is fixed to an inlet end of the inlet-side connecting tube section 11, which is distal with respect to the first coupling zone, and to an outlet end of the outlet-side connecting tube section 12, which is distal with respect to the first coupling zone. In this respect, the entire inner part—formed here by means of the measuring tube 10 and the counter-oscillator 20—is not only completely enclosed by the transducer housing 100, but is also held in the transducer housing 100 in a manner capable of oscillating due to its inherent mass and the spring action of both connecting tube sections 11, 12.

[0038] For the typical case where the MW measuring transducer is to be detachably mounted to the process line, for example, a metallic pipe, a first connection flange 13 is provided on the inlet side of the measuring transducer for connection to a line segment of the process line supplying the medium to the measuring transducer, and a second connection flange 14 is provided on the outlet side for a line segment of the process line discharging the medium from the measuring transducer. The connection flanges 13, 14 can also be integrated into the end of the measuring transducer housing 100, as is quite common with measuring transducers of the type described. If necessary, the connecting pipe sections 11, 12 can also be connected directly to the process line, e.g., by welding or brazing. Fig. 2 and Fig. 3, the first connecting flange 13 is formed on the inlet-side connecting pipe section 11 at its inlet end and the second connecting flange 14 is formed on the outlet-side connecting pipe section 12 at its outlet end, while in the embodiment shown in Fig. 4 and Fig. In the embodiment shown in Figure 5, the connecting flanges are connected to the corresponding flow dividers accordingly.

[0039] For actively exciting mechanical vibrations of the at least one measuring tube (or the measuring tubes), in particular on one or more of its natural frequencies, each of the Fig. 4 to 7 further comprises an electromechanical, in particular electrodynamic, excitation arrangement 40, i.e. formed by means of plunger coils. This serves - controlled by an excitation signal supplied by the driver circuit of the converter electronics and, if necessary in interaction with the measuring and evaluation circuit, appropriately conditioned, e.g. with a regulated current and / or a regulated voltage - in each case to convert electrical excitation energy or power E fed in by means of the driver circuit exc into an excitation force F acting on at least one measuring tube 10, e.g. pulse-shaped or harmonic, and deflecting it in the manner described above exc The excitation force F exccan, as is usual with such transducers, be bidirectional or unidirectional and can be adjusted in a manner known to those skilled in the art, e.g. by means of a current and / or voltage control circuit, with regard to its amplitude and, e.g. by means of a phase-locked loop, with regard to its frequency. The excitation arrangement 40 can be, for example, an excitation arrangement 40 formed in a conventional manner by means of an - for example single - electrodynamic vibration exciter 41 acting centrally, i.e. in the region of half the oscillation length, on the respective measuring tube. The vibration exciter 41 can, in the case of an inner part formed by means of a counter-oscillator and measuring tube, as in the Fig. 4, for example, by means of a cylindrical excitation coil attached to the counteroscillator 20, through which a corresponding excitation current flows during operation and, consequently, is flooded by a corresponding magnetic field, as well as a permanent-magnetic armature which is at least partially immersed in the excitation coil and which is fixed from the outside, in particular centrally, to the measuring tube 10. Further excitation arrangements for oscillations of the at least one measuring tube - which are also entirely suitable for the measuring system according to the invention - are shown, for example, in the aforementioned US-A 57 05 754, US-A 55 31 126, US-B 62 23 605, US-B 66 66 098 or US-B 73 60 451.

[0040] According to a further embodiment of the invention, the at least one measuring tube 10 is actively excited during operation by means of the excitation arrangement at least temporarily in a useful mode in which it executes, in particular predominantly or exclusively, bending vibrations about the aforementioned imaginary vibration axis, for example predominantly with exactly one natural natural frequency (resonance frequency) of the respective inner part of the measuring transducer or of the inner part formed thereby, such as that which corresponds to a fundamental bending vibration mode in which the at least one measuring tube has exactly one vibration antinode. In particular, it is further provided that the at least one measuring tube 10, as is quite common in such measuring transducers with a curved measuring tube, is excited by means of the excitation arrangement to bending vibrations at an excitation frequency f exc, is excited in such a way that, in the useful mode, it oscillates around the aforementioned imaginary oscillation axis - approximately like a cantilever clamped at one end - and bends at least partially according to one of its natural bending oscillation modes. The bending oscillations of the measuring tube have an inlet-side oscillation node in the region of the inlet-side coupling zone defining the inlet-side measuring tube end 11# and an outlet-side oscillation node in the region of the outlet-side coupling zone defining the outlet-side measuring tube end 12#, so that the measuring tube extends with its oscillation length between these two oscillation nodes, essentially oscillating freely.If necessary, the vibrating measuring tube can also be specifically influenced in its oscillation movements by means of spring-elastic and / or electromotive coupling elements additionally acting on the measuring tube in the range of the oscillation length, as proposed, for example, in US-B 70 77 014 or JP-A 9-015015. The driver circuit can, for example, be designed as a phase-locked loop (PLL), which is used in a manner known to those skilled in the art to determine an excitation frequency, f. exc , the excitation signal is constantly adjusted to the current natural frequency of the desired useful mode. The design and use of such phase-locked loops for actively exciting measuring tubes to oscillate at a mechanical natural frequency is described in detail in US-A 48 01 897, for example. Of course, other methods for adjusting the excitation energy E excsuitable driver circuits known per se to the person skilled in the art can be used, for example also in accordance with the prior art mentioned at the beginning, such as the aforementioned US-A 47 77 833, US-A 48 01 897, US-A 48 79 911, US-A 50 09 109, US-A 50 24 104, US-A 50 50 439, US-A 58 04 741, US-A 58 69 770, US-A 6073495 or US-A 63 111 36. Furthermore, with regard to the use of such driver circuits for vibration-type transducers, reference is made to the transducer electronics provided with transducers of the "PROMASS 83" series, as used by the applicant, for example, in conjunction with transducers of the "PROMASS E" series, "PROMASS F," "PROMASS H," "PROMASS I," "PROMASS P," or "PROMASS S." Their driver circuits, for example, are designed in such a way that the lateral bending oscillations in the desired mode are controlled to a constant amplitude, which is largely independent of the density, ρ.

[0041] To vibrate the at least one measuring tube 10, the exciter arrangement 40, as already mentioned, is driven by means of a likewise oscillating exciter signal of adjustable exciter frequency, f exc , so that the excitation coil of the - here the only vibration exciter acting on the measuring tube 10 - is driven by an excitation current i which is correspondingly regulated in its amplitude exc which generates the magnetic field required to move the measuring tube. The driver or excitation signal or its excitation current i exc can be harmonic, multi-frequency, or rectangular. The excitation frequency, f exc, of the excitation current required to maintain the bending vibrations of the at least one measuring tube 10 can be advantageously selected and adjusted in the measuring transducer shown in the exemplary embodiment such that the laterally vibrating measuring tube 10 oscillates at least predominantly in a fundamental bending vibration mode with a single antinode. Accordingly, according to a further embodiment of the invention, the excitation or useful mode frequency, f exc, adjusted so that it corresponds as closely as possible to a natural frequency of bending vibrations of the measuring tube 10, in particular that of the fundamental bending vibration mode. When using a measuring tube made of stainless steel, in particular Hastelloy, with a caliber of 29 mm, a wall thickness s of approximately 1.5 mm, an oscillation length of approximately 420 mm and a chorded length, measured between the two measuring tube ends, of 305 mm, the resonance frequency of the same corresponding to the fundamental bending vibration mode would be approximately 490 Hz, for example at a density of practically zero, e.g. with the measuring tube filled only with air.

[0042] In the Fig. 4 and Fig. 5, with an inner part formed by a measuring tube and a counteroscillator, the measuring tube 10 executes the bending vibrations actively excited by the excitation arrangement predominantly relative to the counteroscillator 20, in particular in antiphase to each other at a common oscillation frequency. In the case of an excitation arrangement acting simultaneously, for example differentially, on both the measuring tube and the counteroscillator, the counteroscillator 20 is also necessarily excited to simultaneous cantilever vibrations, in such a way that it oscillates at the same frequency but at least partially out of phase, in particular essentially in antiphase, to the measuring tube 10 oscillating in the useful mode. In particular, the measuring tube 10 and the counteroscillator 20 are further coordinated or excited in such a way that, during operation, they execute at least temporarily and at least partially anti-equivalent, i.e., same-frequency, but essentially antiphase, bending vibrations about the longitudinal axis L.The bending vibrations can be designed such that they are of the same modal order and thus essentially uniform, at least when the fluid is at rest; in the other case of using two measuring tubes, these are actively excited by means of the exciter arrangement, which acts particularly differentially between the two measuring tubes 10, 10', as is usual with measuring transducers of the type in question, so that during operation they at least temporarily execute counter-synchronous bending vibrations about the longitudinal axis L. In other words, the two measuring tubes 10, 10' or measuring tube 10 and counter-oscillator 20 then each move in the manner of tuning fork tines vibrating against one another. For this case, according to a further embodiment of the invention, the at least one electro-mechanical vibration exciter is designed to generate counter-synchronous vibrations of the first measuring tube and the second measuring tube, in particularTo excite or maintain bending vibrations of each of the measuring tubes around an imaginary vibration axis that imaginarily connects the respective first measuring tube end and the respective second measuring tube end.

[0043] In the operational case where the medium flows in the process line and thus the mass flow rate m is different from zero, Coriolis forces are also induced in the flowing medium by means of the measuring tube 10 vibrating in the manner described above. These forces, in turn, act back on the measuring tube 10 and thus cause an additional, sensor-detectable deformation of the same, essentially according to another natural mode of vibration of a higher modal order than the useful mode. The instantaneous manifestation of this so-called Coriolis mode, which is superimposed on the excited useful mode at the same frequency, is also dependent on the instantaneous mass flow rate m, particularly with regard to its amplitude. The Coriolis mode can, as is usual with such transducers with a curved measuring tube, be, for example,the natural vibration form of the anti-symmetric twist mode, i.e. the one in which the measuring tube 10, as already mentioned, also performs torsional vibrations about an imaginary torsional vibration axis aligned perpendicular to the bending vibration axis, which imaginarily intersects the center line of the measuring tube 10 in the region of half the vibration length.

[0044] To detect vibrations, especially bending vibrations, of the at least one measuring tube 10, especially those in the Coriolis mode, the measuring transducer further comprises a corresponding sensor arrangement 50. This comprises, as in the Fig. 4 to 7 schematically show a first vibration sensor 51, for example an electrodynamic one, arranged at a distance from the at least one vibration exciter on at least one measuring tube 10, which sensor detects a first primary signal s representing vibrations of the measuring tube 10 1of the measuring transducer, for example a voltage corresponding to the vibrations or a current corresponding to the vibrations, as well as a second vibration sensor 52, in particular an electrodynamic one, arranged at a distance from the first vibration sensor 52 on at least one measuring tube 10, which second primary signal s representing vibrations of the measuring tube 10 2 of the transducer. A length of the region of the associated at least one measuring tube extending between the two, for example identical, vibration sensors, in particular the essentially freely vibrating region, corresponds to a measuring length of the respective transducer. Each of the - typically broadband - primary signals s 1 , s 2 of the measuring transducer MW has a signal component corresponding to the desired mode with a current oscillation frequency, f exc, of the at least one measuring tube 10 oscillating in the actively excited useful mode corresponding signal frequency and a phase shift dependent on the current mass flow of the medium flowing in the at least one measuring tube 10 relative to the, for example by means of a PLL circuit in dependence on a between at least one of the oscillation measuring signals s 1 , s 2 and the excitation current in the excitation arrangement existing phase difference, excitation signal i exc Even when using a rather broadband excitation signal i excDue to the usually very high oscillation quality of the MW transducer, it can be assumed that the signal component of each of the primary signals corresponding to the wanted mode outweighs other signal components, in particular those corresponding to any external interference and / or which can be classified as noise, and is therefore dominant at least within a frequency range corresponding to a bandwidth of the wanted mode.

[0045] In the exemplary embodiments shown here, the first vibration sensor 51 is arranged on the inlet side and the second vibration sensor 52 is arranged on the outlet side of at least one measuring tube 10, in particular at the same distance from the at least one vibration exciter or from the center of the measuring tube 10 as the first vibration sensor. As is quite common with such vibration-type measuring transducers used in measuring systems designed as Coriolis mass flow meters, the first vibration sensor 51 and the second vibration sensor 52 are, according to one embodiment of the invention, each arranged on a side of the measuring tube in the measuring transducer occupied by the vibration exciter 41. Furthermore, the second vibration sensor 52 can also be arranged on the side of the measuring tube in the measuring transducer occupied by the first vibration sensor 51.The vibration sensors of the sensor arrangement can advantageously also be designed such that they supply primary signals of the same type, for example a signal voltage or a signal current. According to a further embodiment of the invention, both the first vibration sensor and the second vibration sensor are further each placed in the measuring transducer MW such that each of the vibration sensors at least predominantly detects vibrations of the at least one measuring tube 10. For the case described above, in which the inner part is formed by means of a measuring tube and a counteroscillator coupled to it, according to a further embodiment of the invention, both the first vibration sensor and the second vibration sensor are designed and placed in the measuring transducer such that each of the vibration sensors predominantly detects vibrations of the measuring tube relative to the counteroscillator, for example differentially, so that both the first primary signal s. 1as well as the second primary signal s 2 , in particular, represent counter-synchronous, oscillation movements of the at least one measuring tube 10 relative to the counter-oscillator 20. For the other described case, in which the inner part is formed by means of two measuring tubes, in particular, which oscillate counter-synchronously during operation, according to another embodiment of the invention, both the first oscillation sensor and the second oscillation sensor are designed and placed in the measuring transducer in such a way that each of the oscillation sensors predominantly detects oscillations of the first measuring tube 10 relative to the second measuring tube 10', for example, differentially, so that both the first primary signal s 1 as well as the second primary signal s 2, in particular opposite, vibrational movements of the two measuring tubes relative to one another, in particular such that - as is usual with conventional measuring transducers - the first primary signal generated by the first vibration sensor represents inlet-side vibrations of the first measuring tube relative to the second measuring tube and the second primary signal generated by the second vibration sensor represents outlet-side vibrations of the first measuring tube relative to the second measuring tube. According to a further embodiment of the invention, it is further provided that the sensor arrangement has exactly two vibration sensors, i.e., in addition to the first and second vibration sensors, no further vibration sensors, and in this respect corresponds to a conventional sensor arrangement with regard to the components used.

[0046] The vibration measurement signals s supplied by the sensor arrangement, which serve as primary signals of the transducer 1 , s 2, each of which has a signal component with an instantaneous oscillation frequency, f exc , of the at least one measuring tube 10 oscillating in the actively excited useful mode have the corresponding signal frequency, as also in Fig. 3, are fed to the converter electronics ME and then to the measuring and evaluation circuit µC provided therein, where they are first preprocessed, in particular pre-amplified, filtered, and digitized, by means of a corresponding input circuit FE, in order to then be suitably evaluated. Established circuit technologies already used in conventional Coriolis mass flowmeters for the purpose of converting the primary signals or determining mass flow rates and / or totalized mass flow rates, etc., can be used as the input circuit FE and as the measuring and evaluation circuit µC, for example, including those according to the state of the art mentioned above.According to a further embodiment of the invention, the measuring and evaluation circuit µC is accordingly also implemented by means of a microcomputer provided in the converter electronics ME, for example realized by means of a digital signal processor (DSP), and by means of program codes implemented accordingly and running therein. The program codes can, for example, be stored persistently in a non-volatile data memory EEPROM of the microcomputer and, when the microcomputer is started, can be loaded into a volatile data memory RAM, for example integrated in the microcomputer. Processors suitable for such applications are, for example, those of the type TMS320VC33, as offered on the market by Texas Instruments Inc. It practically goes without saying that the primary signals s. 1 , s 2As already indicated, they must be converted into corresponding digital signals for processing in the microcomputer by means of corresponding analogue-to-digital converters A / D of the converter electronics ME, see for example the above-mentioned US-B 63 11 136 or US-A 60 73 495 or also the aforementioned measuring converters of the “PROMASS 83” series.

[0047] In the measuring system according to the invention, the transducer electronics ME serves in particular to measure, by means of the first primary signal and the second primary signal, and taking into account a Reynolds number determined for the flowing medium, a pressure difference occurring in the flowing medium between two predetermined reference points, for example, those located within the transducer, such as a pressure drop in the flowing medium caused by the transducer itself. For this purpose, the transducer electronics generates, by means of the first and second primary signals and by using a Reynolds number measurement value X stored internally, for example in the volatile data memory RAM. Re , which represents a Reynolds number, Re, for the medium flowing in the transducer, during operation recurringly produces a pressure difference measured value X Δp, which represents the aforementioned pressure difference accordingly, for example in such a way that a first of the two reference points are located on the inlet side and a second of the two reference points on the outlet side in the measuring transducer and in this respect a pressure difference falling overall across the measuring transducer, Δp tota , is determined. The Reynolds number measurement value X Re is generated during operation by means of the driver signal, for example also by means of at least one of the primary signals, for example according to one of the methods described in the aforementioned US-B 65 13 393 directly in the converter electronics ME.

[0048] According to a further embodiment of the invention, the transmitter electronics determines the pressure difference measured value using the Reynolds number measured value X Re as well as a flow energy measurement value X which is also stored internally in the measuring system, for example in the volatile data memory RAM Ekin, which has a kinetic energy, ρU, dependent on a density, ρ, and a flow velocity, U, of the medium flowing in the transducer 2 , of the medium flowing in the transducer. For this purpose, a corresponding calculation algorithm is implemented in the transmitter electronics, which calculates the pressure difference measured value based on the Fig. 8 exemplary relationship XΔp=(Kς,1+Kς,2⋅XReKς,3)⋅XEkin generated, where K ζ,1 , K ζ,2 , K ζ,3, are measuring system parameters determined experimentally in advance, for example during calibration of the measuring system and / or by means of computer-aided calculations, e.g. by means of FEM or CFD, and especially stored as fixed values ​​in the converter electronics, which ultimately also define the respective location of the reference points underlying the pressure difference to be determined. The function formed by means of these measuring system parameters, of which an example determined by experimental investigations is shown in Fig. 9, represents a quasi-interaction between the instantaneous or currently valid Reynolds number Re of the flowing medium and a dependent kinetic energy, ρU 2 , the specific pressure drop of the medium flowing in the measuring transducer, the pressure drop characteristic of the measuring system, which is generated internally by the converter electronics and is referred to as the pressure drop coefficient X ζ , designated function values Kς=Kς,1+Xς,2⋅XReKς,3 depend only on the instantaneous Reynolds number. The measuring system parameters K that define the pressure drop characteristic curve ζ,1 , K ζ,2 , K ζ,3 can, for example, be selected so that a first of the reference points is located in the inlet end #111 of the transducer - formed here by the first housing end of the transducer housing - and that a second of the reference points is located in the outlet end #112 of the transducer - formed here by the second housing end of the transducer housing, so that the pressure difference measured value X Δp As a result, a total pressure difference occurring in the flowing medium from the inlet end to the outlet end, Δp total , represents, cf. Fig. 9 and Fig. 11. The measuring system parameters and, in this respect, the reference points can, for example, also be selected so that the pressure difference measured value X Δp , as in Fig. 10, a maximum pressure drop, Δp max , in the medium flowing within the transducer. This maximum pressure drop, Δp max , as is also the case in Fig. 12, as can be seen from the pressure loss profiles shown as examples for transducers of the type in question, between the inlet end #111 of the transducer formed by the first housing end and an area of ​​increased turbulence located upstream of the outlet end #112 of the transducer formed by the second housing end. Taking into account the pressure drop characteristic curve or the pressure drop coefficient X ζ The functional relationship proposed for determining the pressure difference measured value can be further reduced to the relationship X Δp = X ζ ·X Ekin simplify.

[0049] According to a further embodiment of the invention, the measuring and evaluation circuit µC also serves to determine the pressure difference measured value X Δp , especially for determining the required flow energy measured value X Ekin , and / or the required Reynolds number measurement value X Re , using the primary signals s supplied by the sensor arrangement 50 1 , s 2 , for example, using a primary signal s generated between the measuring tube 10 oscillating proportionally in useful and Coriolis mode 1 , s 2 of the first and second vibration sensors 51, 52 detected phase difference, recurring a mass flow measurement value X m to determine the represents the mass flow rate to be measured, m , of the medium guided through the measuring transducer as accurately as possible. For this purpose, according to a further embodiment of the invention, the measuring and evaluation circuit repeatedly generates a phase difference measured value X during operation. Δφ, which is between the first primary signal s 1 and the second primary signal s 2 existing phase difference, Δφ, currently represents the mass flow rate X. m can, using a frequency measurement value X, which is also stored in the converter electronics and represents an oscillation frequency of vibrations, for example the above-mentioned lateral bending vibrations of the at least one measuring tube 10 in the useful mode f thus, for example, based on the known relationship: Xm=Km⋅XΔφXf where K ma previously determined experimentally, e.g. during calibration of the measuring system and / or by means of computer-aided calculations, e.g. in the non-volatile data memory, internally stored as fixed values, measuring system parameter, which is between the here by means of the phase difference measured value X Δφ and the frequency measurement value X f educated quotients and the mass flow rate to be measured, m , is conveyed accordingly. The frequency measurement value X f itself can be determined in a simple manner, for example, based on the primary signals supplied by the sensor arrangement or also based on the at least one driver signal feeding the excitation arrangement in a manner known to the person skilled in the art.

[0050] According to a further embodiment, it is further provided that the converter electronics, for example in the volatile data memory RAM, a density measurement value X ρ, which represents a density, ρ, of the medium to be measured at the moment, and / or a viscosity measurement value X η , which represents the current viscosity of the medium. Based on the mass flow measurement value X m and the density measurement value X ρ can thus be determined by means of the converter electronics of the pressure difference measurement value X Δp required flow energy measured value X Ekin be determined internally, for example by implementing the relationship XEkin=KEkin⋅(Xm)2Xρ, while using the mass flow measurement value X m and the viscosity measurement value X η , in a simple way to determine the pressure difference measured value X Δp required Reynolds number measurement value X Re can be determined in the converter electronics, for example based on the relationship XRe=KRe⋅XmXη. X Re The corresponding measuring system parameters K Ekin or K Reare essentially dependent on the effective flow cross-section of the measuring transducer and can be easily determined experimentally in advance, e.g. during calibration of the measuring system and / or by means of computer-aided calculations, and stored in the converter electronics as measuring system-specific fixed values.

[0051] Taking into account the above functional relationships, the pressure difference measured value X Δp can also be determined based on one of the following relationships: XΔp=Xξ⋅KEkin⋅(Xm)Xρ, XΔp=(Kς,1+Kς,2⋅XReKς,3)⋅KEkin⋅(Xm)Xρ, XΔp=[Kς,1+Kς,2⋅(KRe⋅XmXη)Kς,3]⋅XEkin, or XΔp=[Kς,1+Kς,2⋅(KRe⋅XmXη)Kς,3]⋅XEkin⋅(Xm)2Xρ.

[0052] The above-mentioned measuring system parameters K required for determining the pressure difference measured value ζ,1 , K ζ,2 , K ζ,3 or K Ekin or K Rerequired defined flows with known Reynolds numbers, Re, known kinetic energy, ρU 2, and known pressure curves can be easily realized with sufficient precision on appropriate calibration systems, for example by means of calibration media which are known in terms of their flow properties, such as water, glycerol, etc., which are fed to the measuring system to be calibrated as an impressed flow by means of appropriately controlled pumps. Alternatively or in addition to this, the flow parameters required to determine the measuring system parameters, such as the Reynolds number, the kinetic energy, the pressure difference, etc., can also be determined metrologically, for example by means of a pressure difference measuring system which, together with the measuring system to be calibrated, forms one of the measuring systems proposed in the aforementioned US-B 74 06 878 and which, for the purpose of wet calibration, is subjected to flows with correspondingly varied mass flow rates, densities and viscosities.

[0053] Using the pressure difference measured value X Δp it is now possible to determine the phase difference between the primary signals s, which is also influenced to a certain extent by the pressure conditions in the flowing medium. 1 , s 2 or to correct the oscillation frequency, which is also affected, in order to increase the accuracy of the mass flow and / or density measured values ​​during operation. It is also possible, however, to use the pressure difference measured value X Δp to monitor the measuring system or a piping system connected to it for conditions that are critical for operation, such as the extent of a pressure drop in the flowing medium inevitably caused by the measuring transducer itself and / or the associated risk of mostly harmful cavitation in the flowing medium as a result of an excessive pressure drop.

[0054] Therefore, according to a further embodiment of the invention, the converter electronics are further designed to use the pressure difference measured value X Δp to generate an alarm that signals an exceedance of a predefined, maximum permissible reduction in static pressure in the medium flowing through the transducer or an excessive pressure drop in the medium caused by the transducer, for example, visually and / or acoustically perceptible in the vicinity of the measuring system. The alarm can be displayed on-site, for example, via the aforementioned HMI display and control element, and / or made audible by a signal horn controlled by the measuring system.

[0055] Alternatively or in addition, according to a further embodiment of the invention, the converter electronics are designed to use the pressure difference measured value and an internally stored first pressure measured value X p1, which has a first pressure, p, prevailing in the flowing medium, for example, impressed by a pump conveying the flowing medium and / or adjusted by means of a valve and / or measured by means of an additional pressure sensor and / or determined by means of the converter electronics on the basis of at least one of the primary signals and / or static Ref , represents a second pressure measurement value X p2 , with X p2 = X p1 - X Δp to generate a static second pressure, p krit, within the flowing medium, for example, a pressure at the location of the outlet-side reference point - in this case, the second of the two reference points that define the pressure difference represented by the pressure difference measured value. For the aforementioned case that one of the two reference points, by appropriately selecting the measuring system parameters for the pressure drop coefficient or the pressure drop characteristic, is set to the previously precisely determined location of minimum pressure (Δp = Δp max ) within the medium flowing in the transducer, can be based on the second pressure measurement value X p2For example, during operation of the measuring system, it can be determined whether an inadmissibly low static pressure in the flowing medium is to be expected within the measuring transducer or, if applicable, directly in the downstream outlet area of ​​the connected pipeline. Therefore, according to a further embodiment, the transmitter electronics are designed to use the second pressure measurement value X p2 if necessary, to generate an alarm that signals, for example in a visually and / or acoustically perceptible manner, when the pressure in the medium falls below a predefined, minimum permissible static pressure and / or that signals, for example, the onset of cavitation in the medium.

[0056] The first pressure measurement value X p1can, for example, be transmitted during operation from the aforementioned higher-level data processing system to the converter electronics and / or from a pressure sensor directly connected to the converter electronics and thus belonging to the measuring system, and stored there in the aforementioned volatile data memory RAM and / or in the non-volatile data memory EEPROM. Therefore, according to a further development, the measuring system further comprises a pressure sensor that communicates with the converter electronics during operation, for example via a direct point-to-point connection and / or wirelessly via radio, for detecting a static pressure prevailing in a pipeline carrying the medium, for example upstream of an inlet end of the measuring transducer or downstream of an outlet end of the measuring transducer. Alternatively or in addition, the pressure measurement value X p1but also, for example, using pressure measuring methods known to the person skilled in the art, inter alia from the aforementioned US-B 68 68 740, US-A 57 34 112, US-A 55 76 500, US-A 2008 / 0034893 or WO-A 95 / 29386, WO-A 95 / 16897, can be determined directly from the primary signals by means of the converter electronics. In the event that the first pressure measurement value X p1 does not exactly represent the pressure in the medium that corresponds to one of the two reference points on which the pressure difference measurement is based, for example because the pressure measurement value X p1 supplying pressure sensor or because the pressure measured value X p1 supplying pump with control is further away from the inlet end of the transducer, the pressure measurement value X p1 of course, to be converted to the reference point accordingly, for example by deducting or adding a value between the pressure measured value X p1corresponding measuring point and the known pressure drop occurring through the calibration of the measuring system, or the pressure drop characteristic curve underlying the above-mentioned pressure drop coefficient must be adjusted accordingly by selecting suitable measuring system parameters.

[0057] According to a further embodiment of the invention, the measuring and evaluation circuit of the measuring system according to the invention also serves to derive from the frequency measured value X f currently represented oscillation frequency in a manner known to the person skilled in the art, additionally the density measurement value X required to determine the pressure difference measurement value ρ to generate, for example, based on the relationship: Xρ=Kρ,1+Kρ,2Xf2, where K ρ,1 , K ρ,2, are measurement system parameters that have been determined experimentally in advance, for example in the non-volatile data memory RAM, and are stored internally as fixed values, which lie between the frequency measured value X f represented vibration frequency and the density to be measured, p, accordingly.

[0058] Alternatively or in addition, the evaluation circuit can also be used, as is common practice with in-line measuring devices of the type in question, to calculate the viscosity measurement value X required to determine the pressure difference measurement value. ηto be determined, see also the aforementioned US-B 72 84 449, US-B 70 17 424, US-B 69 10 366, US-B 68 40 109, US-A 55 76 500 or US-B 66 51 513. To determine the excitation energy or excitation power or damping required to determine the viscosity, the excitation signal supplied by the driver circuit of the converter electronics is suitable, in particular an amplitude and frequency of its current component driving the useful mode or also an amplitude of the entire excitation current, possibly also standardized to an oscillation amplitude determined on the basis of at least one of the primary signals. Alternatively or in addition to this, an internal control signal serving to adjust the driver signal or the excitation current or, for example in the case of excitation of the vibrations of the at least one measuring tube with an excitation current of a fixed predetermined or constantly regulated amplitude, also at least one of the primary signals, in particularan amplitude thereof, serve as a measure of the excitation energy or excitation power or damping required to determine the viscosity measurement value.

[0059] The above-mentioned, in particular those related to the generation of the pressure difference measured value X Δpor other of the aforementioned measured values, computing functions can be implemented very easily, for example, using the above-mentioned microcomputer of the evaluation circuit µC or, for example, a digital signal processor DSP provided therein. The creation and implementation of corresponding algorithms that correspond to the formulas described above or, for example, simulate the functioning of the aforementioned amplitude or frequency control circuit for the excitation arrangement, as well as their translation into correspondingly executable program codes in the converter electronics, is familiar to the person skilled in the art and therefore requires no detailed explanation - at least with knowledge of the present invention.other functionalities of the measuring system realized with the converter electronics can also be easily realized in whole or in part by means of corresponding discrete and / or hybrid, i.e. mixed analog-digital, computing circuits in the converter electronics ME.

Claims

[1] Measuring system, in particular compact measuring device and / or Coriolis mass flow meter, for flowing media, in particular in pipelines, which measuring system comprises: - a vibration-type measuring transducer (MW) through which a medium, in particular a gas and / or a liquid, a paste or a powder or another flowable material, flows during operation to generate primary signals corresponding to parameters of the flowing medium, in particular a mass flow rate, a density and / or a viscosity, as well as converter electronics (ME) electrically coupled to the measuring transducer to control the measuring transducer and to evaluate primary signals supplied by the measuring transducer, - where the transducer -- at least one measuring tube (10; 10') for guiding flowing medium, -- at least one electromechanical, in particular electrodynamic, vibration exciter for exciting and / or maintaining vibrations of the at least one measuring tube, in particular bending vibrations of the at least one measuring tube about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube with a natural resonance frequency of the measuring transducer, -- a first vibration sensor (51), in particular an electrodynamic one, for detecting vibrations, in particular on the inlet side, of at least the at least one measuring tube and for generating a first primary signal (s) representing vibrations, in particular on the inlet side, of at least the at least one measuring tube 1 ) of the transducer, and -- a second vibration sensor (52), in particular an electrodynamic one, for detecting vibrations, in particular on the outlet side, of at least the at least one measuring tube and for generating a second primary signal (s) representing vibrations, in particular on the outlet side, of at least the at least one measuring tube 2 ) of the transducer; and - where the converter electronics -- at least one driver signal causing vibrations, in particular bending vibrations, of the at least one measuring tube (i exc ) for the vibration exciter, and -- by means of the first primary signal and by means of the second primary signal and using a Reynolds number measurement value generated during operation by means of the driver signal and representing a Reynolds number, Re, for the medium flowing in the transducer, a pressure difference measurement value (X Δp) is generated which represents a pressure difference occurring between two predetermined reference points in the flowing medium, in particular those located within the measuring transducer, in particular such that a first of the two reference points is located on the inlet side and a second of the two reference points is located on the outlet side in the measuring transducer. [2] Measuring system according to the preceding claim, wherein the transmitter electronics measures the pressure difference value (X Δp ) using a viscosity measurement value (X η ) is generated, which represents a viscosity, η, of the medium flowing in the transducer. [3] Measuring system according to claim 2, wherein the converter electronics calculates the Reynolds number measurement value using the viscosity measurement value (X η ) is generated. [4] Measuring system according to one of the preceding claims, wherein the transmitter electronics for determining the pressure difference measured value (X Δp ) by means of the first primary signal and by means of the second primary signal a mass flow measurement value (X m ) is generated, which represents a mass flow rate, ṁ, of medium flowing in the transducer. [5] Measuring system according to one of the preceding claims, wherein the converter electronics converts the pressure difference measured value (X Δp ) using a density measurement value (X ρ ) is generated, which represents a density, ρ, of medium flowing in the transducer. [6] Measuring system according to one of the preceding claims, wherein the transmitter electronics for determining the pressure difference measured value (X Δp) by means of the first primary signal and by means of the second primary signal a flow energy measured value (X Ekin ) which generates a kinetic energy, ρU, dependent on a density, ρ, and a flow velocity, U, of the medium flowing in the transducer 2 , represented by the medium flowing in the transducer. [7] Measuring system according to claims 4, 5 and 6, in which measuring system the transmitter electronics calculates the pressure difference measured value based on the relationship: XΔp=(Kς,1+Kς,2⋅XReKς,3)⋅KEkin⋅(Xm)2Xρ generated, where K ζ,1 , K ζ,2 , K ζ,3 , K Ekin measuring system parameters determined in advance experimentally, in particular during calibration of the measuring system and / or by means of computer-aided calculations, in particular stored internally as fixed values ​​in a non-volatile data memory provided in the converter electronics. [8] Measuring system according to one of the preceding claims, which is designed to generate a pressure measurement value (X) representing a static pressure prevailing in the flowing medium. p1 ) further comprises a pressure sensor which serves to detect a static pressure prevailing in a pipe carrying the medium, in particular upstream of an inlet end of the measuring transducer or downstream of an outlet end of the measuring transducer, and which communicates with the transmitter electronics during operation. [9] Measuring system according to one of the preceding claims, - wherein the transmitter electronics generates an alarm using the pressure difference measured value, which signals an exceedance of a predefined, maximum permissible reduction in static pressure in the medium flowing through the transducer, in particular visually and / or acoustically perceptible; and / or - whereby the transmitter electronics generates an alarm using the pressure difference measured value, which signals an excessive pressure drop in the medium caused by the transducer, in particular visually and / or acoustically perceptible; and / or - wherein the converter electronics generates the Reynolds number measurement value by means of the first primary signal and / or by means of the second primary signal. [10] A method for measuring a pressure difference occurring within a flowing medium using a measuring system according to any one of claims 1-9, which method comprises the following steps: - allowing the medium to flow through at least one measuring tube; - Generating a Reynolds number measurement value representing a Reynolds number, Re, for the flowing medium, and - Using the Reynolds number measurement value to generate a pressure difference measurement value that represents a pressure difference occurring between two reference points in the flowing medium, especially those located within the transducer.

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