METHOD FOR DETERMINING THE VOLUME PROPORTION OF A PHASE OF A MULTIPLE-PHASE MEDIUM AND CORRESPONDING MEASURING DEVICE

Description

[0001] Patent application US 2020 / 0080877 A1 describes a magnetic flow meter with electrode sensors in which a module for identifying impurities uses the noise level in the sensor signal to determine whether there is an impurity in the line, according to the prior art of the present invention.

[0002] The invention relates to a method for determining the volume fraction of a phase of a multiphase medium according to claim 1, wherein the medium has a first phase with a first value for a first electrical parameter and at least temporarily a second phase with a second value for the first electrical parameter, wherein the medium is subjected to a plurality of electrical excitation signals via a pair of electrodes and a plurality of corresponding electrical response signals are recorded for the electrical excitation signals, wherein a plurality of values ​​for the first electrical parameter of the medium are determined from the plurality of excitation signals and the plurality of response signals.Furthermore, the invention also relates to a measuring device with a measuring volume for receiving a medium according to claim 13, wherein the medium has a first phase with a first value for a first electrical parameter and at least temporarily a second phase with a second value for the first electrical parameter, with a control and evaluation unit, with electrodes in contact with the medium, wherein, in the operating state of the measuring device, the control and evaluation unit applies a plurality of electrical excitation signals to the medium via the electrode pair and detects a plurality of corresponding electrical response signals to the electrical excitation signals, wherein a plurality of values ​​for the first electrical parameter of the medium are determined from the plurality of excitation signals and the plurality of response signals.

[0003] Methods and measuring instruments of the aforementioned type are often used in conjunction with other measurement methods, such as flow measurement. In flow measurement, a volumetric flow rate is calculated—also indirectly via the flow velocity of the medium (for example, with magnetic-inductive flow meters)—or a mass flow rate (for example, with Coriolis mass flow meters). If it is known that the medium in question may have several phases, then it is obvious that not only the volumetric flow rate or the mass flow rate of the multiphase medium is of interest, but also the composition of the medium, i.e., the proportions of the different phases in the multiphase medium. The term "phase" here is therefore not to be understood restrictively in the sense of a state of matter, but rather as a multi-component system.Such multi-component systems are found in many applications in the chemical industry, oil and gas extraction, wastewater treatment, etc.

[0004] The prerequisite for carrying out this method is the presence of electrodes that are in contact with the medium and through which the medium can be subjected to an electrical excitation signal. For example, it is known to apply an electrical voltage to the medium as the electrical excitation signal and to measure the resulting electrical current as the electrical response signal. From the values ​​of the electrical voltage and the electrical current, values ​​for the ohmic resistance or impedance of the medium can then be determined as the first electrical parameter of the medium.Assuming that the first electrical parameter of the first phase in its pure form differs from that of the second phase in its pure form, it follows that the first electrical parameter of the multiphase medium also changes with changing proportions of the first and second phases. The proportion of the second phase (and thus also of the first phase) can then be determined via the relationship between the first electrical parameter and the mixing ratio of the known phases. This method is used, for example, in magnetic-inductive flowmeters, which, by their very nature, have electrodes primarily designed to detect induced electrical voltages in the medium. When implementing this method to determine the volume fraction of a phase, these electrodes are used to apply the electrical excitation signal to the medium.

[0005] A problem with the described method is that the reliability of the result for determining the volume fractions of the phases involved depends heavily on the assumption that only the assumed phases with the well-known values ​​for the first electrical parameter of the phases are actually present, and that the phases involved in the multiphase medium remain unchanged. It is quite common for at least one of the phases involved to actually change its properties (and thus also its first electrical parameter). For example, consider a two-phase medium consisting of oil and seawater, where the salinity (and thus the electrical conductivity) of the seawater changes. Therefore, the determination of the volume fractions of the phases in the medium using the described method is very sensitive to changes in the media involved.

[0006] The object of the present invention is therefore to further develop the method and also the measuring device for determining the volume fraction of a phase of a multiphase medium in such a way that it is less sensitive to a change in the phases involved and their values ​​for the first electrical parameter.

[0007] The previously derived problem is solved in the method described at the outset for determining the volume fraction of a phase of a multiphase medium and in the measuring instrument described at the outset, by the features of the characterizing parts of the independent claims. The method according to the invention is characterized in that a standard deviation value of a statistical measure of dispersion is determined from the plurality of determined values ​​for the first electrical parameter of the medium, and that, using a mathematical relationship between the statistical measure of dispersion of the first electrical parameter and a volume fraction of the second phase in the medium with the determined standard deviation value of the first electrical parameter, the volume fraction of the second phase in the medium is determined.What is remarkable about the method is that it is independent of the direct values ​​of the first electrical parameter (such as the determined electrical conductivity or impedance of the medium) and that, instead, a statistical measure of dispersion of the first electrical parameter is used based on a plurality of values ​​for the first electrical parameter. According to the invention, it has been recognized that there is a relationship between the dispersion values ​​of this statistical measure of dispersion and the volume fraction of the second phase in the medium. The use of such a relationship in itself already reduces the dependence on the absolute values ​​of the first electrical parameter of the medium.

[0008] According to an advantageous embodiment of the method, the excitation signal is an electrical voltage or an electrical current. Correspondingly, the electrical response signal is an electrical current or an electrical voltage, in particular where the excitation signal is a harmonic oscillation with an excitation frequency. Choosing the excitation signal as a harmonic oscillation enables the evaluation of first electrical parameters, which are defined as harmonic alternating quantities.

[0009] According to a further advantageous embodiment of the method, the application of electrical excitation signals to the medium is carried out during a time interval in which no other measurement is being performed in the medium. This measure prevents different measurement processes from interfering with each other and thus leading to an overall less accurate measurement result. If the method is performed with a magnetic-inductive flowmeter, which—as previously explained—already has corresponding electrodes interacting with the medium, then the method is used to determine the volume fraction of a phase when no magnetic-inductive flow measurement is being performed.In particular, the procedure is then carried out after a switch in the polarity of the magnetic field which is always required for magnetic-inductive flow measurement, especially in the time domain of a non-stationary magnetic field, since these time domains are not very suitable for flow measurement.

[0010] In another preferred embodiment of the method, the standard deviation is calculated as a statistical measure of dispersion. Calculating the standard deviation is simple, and it has been found that in many cases the standard deviation shows a good correlation with the volume fraction of the second phase of the medium.

[0011] A feature of the method according to the invention is that the first electrical parameter of the medium is the electrical conductivity of the medium and / or the magnitude of the impedance of the medium and / or the phase angle of the impedance of the medium, in particular wherein the electrical conductivity is determined from the real part of the impedance of the medium taking into account the geometry of the measuring volume in which the medium is located.

[0012] In a preferred embodiment of the method, a significantly greater insensitivity to changes in the material properties of the phases involved and their values ​​for the first electrical parameter of the phases can be achieved by normalizing the determined dispersion value of the first electrical parameter to the absolute value of the first electrical parameter, in particular to an absolute mean value of the first electrical parameter calculated from the majority of determined values ​​for the first electrical parameter of the medium. This normalization also renders the standard deviation independent of the absolute values ​​and possible fluctuations in the absolute values ​​of the first electrical parameter of the phases.Even if the material composition of one or both of the phases involved changes, there is still a good correlation between the change in the determined scatter value of the first electrical parameter and the volume fraction of the second phase of the medium when using normalized quantities.

[0013] A further preferred embodiment of the method is characterized in that a plurality of values ​​for a second electrical parameter of the medium are determined from the plurality of excitation signals and the plurality of response signals, that a dispersion value of a statistical measure of dispersion is determined from the plurality of determined values ​​for the second electrical parameter of the medium, and that, using a mathematical relationship between the statistical measure of dispersion of the second electrical parameter and the volume fraction of the second phase in the medium with the determined dispersion value of the second electrical parameter, the volume fraction of the second phase in the medium is determined.The relationship between the volume fraction of the second phase in the medium (and thus also the volume fraction of the first phase in the medium) and the value of the statistical measure of dispersion used for various electrical parameters of the medium has proven to be widely applicable with respect to different electrical parameters, so that further electrical parameters can also be readily used to determine the volume fraction of the second phase of the medium. This opens up numerous possibilities for the mutual verification of calculation results, including redundancy and / or combination of different calculation results obtained via different methods, as well as possibilities for the mutual verifiability and plausibility checks of results obtained via different methods regarding the volume fraction of the second phase of the medium.

[0014] The aforementioned preferred embodiment of the method offers the possibility of further developing the method by calculating an average volume fraction of the second phase of the medium from the volume fraction determined using the first electrical parameter of the medium and from the volume fraction determined using the second electrical parameter of the medium. The possibility of combining volume fractions of the second phase of the medium determined based on different electrical parameters is advantageous because the relationship between the value of the statistical measure of dispersion used for an electrical parameter of the medium and the volume fraction of the second phase of the medium has proven to be relatively universal.

[0015] In a further advantageous embodiment of the method, the volume fraction of the second phase in the medium determined with the first electrical parameter of the medium and / or the volume fraction of the second phase of the medium determined with the second electrical parameter of the medium and / or the averaged volume fraction of the second phase in the medium is signaled, in particular the determined volume fraction is stored in a memory of a control and evaluation unit of the measuring device and / or displayed and / or transmitted via a communication interface of the measuring device of a flow meter, in particular a magnetic-inductive flow meter, to a connected communication partner.

[0016] In a further preferred embodiment of the method, it is provided that if a first limit value is exceeded by the volume fraction of the second phase in the medium determined with the first electrical parameter of the medium and / or if a second limit value is exceeded by the volume fraction of the second phase of the medium determined with the second electrical parameter of the medium and / or if a third limit value is exceeded by the averaged volume fraction of the second phase in the medium, the presence of a two-phase flow is signaled, in particular stored in a memory of the control and evaluation unit of the measuring device and / or displayed and / or transmitted via a communication interface of the measuring device, in particular a magnetic-inductive flowmeter, to a connected communication partner.

[0017] In a preferred embodiment of the method, it is provided that the mathematical relationship between the statistical measure of dispersion of the first electrical parameter and the volume fraction of the second phase of the medium and / or the mathematical relationship between the statistical measure of dispersion of the second electrical parameter and the volume fraction of the second phase of the medium is determined by determining the dispersion value of the first electrical parameter and / or the dispersion value of the second electrical parameter at at least two different but known volume fractions of the second phase, in particular where a linear dependence between the statistical measure of dispersion of the first electrical parameter and the volume fraction of the second phase of the medium and / or between the statistical measure of dispersion of the second electrical parameter and the volume fraction of the second phase of the medium is assumed.If there are only two data points, then a linear equation can be immediately derived as the relationship between the volume fraction of the second phase of the medium and the variance value of the statistical measure of dispersion β of the second medium. With more than two data points, the relationship can be formulated linearly as a regression line. It has been shown that assuming such linear relationships is a suitable approximation of the actual behavior.

[0018] In a further preferred embodiment of the method, more than two support points are recorded, i.e., more than two relationships between the statistical measure of dispersion of an electrical parameter and the volume fraction of the second phase of the medium, and a polynomial description of the relationship is determined as a mathematical relationship between the statistical measure of dispersion of an electrical parameter and the volume fraction of the second phase of the medium, or a description of the relationship is determined using spline interpolations, in particular by optimizing the descriptions of the relationships by minimizing a deviation measure.

[0019] In the measuring device described at the outset, the derived problem is solved by designing the control and evaluation unit in such a way that the measuring device performs the previously described procedure during operation. In particular, the procedure is carried out in a flow meter, especially a magnetic-inductive flow meter, in which the necessary electrodes are already provided, or in a Coriolis mass flow meter, a vortex flow meter, a magnetic resonance flow meter, or a variable area flow meter. In the latter flow meters, the electrodes required for carrying out the procedure are not necessarily implemented; if necessary, they must be provided additionally.

[0020] In detail, there are numerous possibilities for designing and further developing the inventive method and measuring device. Reference is made, on the one hand, to the claims subordinate to the independent claims, and on the other hand, to the following description of exemplary embodiments in conjunction with the drawing. The drawing shows Fig. 1 schematically shows, in partial aspects, the fundamentals of a method for determining the volume fraction of a phase of a multiphase medium; Fig. 2 schematically shows the steps of a method for determining the volume fraction of a phase of a multiphase medium; Fig. 3 schematically shows the method for determining the volume fraction of a phase of a multiphase medium based on electrical conductivity; Fig. 4 schematically shows the method for determining the volume fraction of a phase of a multiphase medium based on electrical impedance; Fig. 5 schematically shows the method for determining the volume fraction of a phase of a multiphase medium based on the absolute value of the electrical impedance; Fig. 6 schematically shows the method for determining the volume fraction of a phase of a multiphase medium based on the phase information of the electrical impedance; and Fig.7. Schematic representation of a measuring device for determining the volume fraction of a phase of a multiphase medium using the methods described above.

[0021] The Figs. 1 to 7 In different aspects, a method 1 and a measuring device 2 for determining the volume fraction V% of a phase of a multiphase medium M are shown, wherein the medium M has a first phase P1 with a first value E1 for a first electrical parameter E and at least temporarily a second phase P2 with a second value E2 for the first electrical parameter E.

[0022] The figures use both numbers and letters as reference symbols. For the most part, the letters serve only as reference symbols, but they significantly facilitate understanding and establish the connection between the description and the drawing. In some cases, the reference symbols also function as formula symbols. While these formula symbols are helpful for understanding the claims, for example, they are not essential. Therefore, both the letter reference symbols and formula symbols in the claims are enclosed in parentheses and are treated as reference symbols in the subsequent figure descriptions.

[0023] The measurements under consideration are frequently encountered measurement tasks where the proportion of the different phases P1 and P2 in the medium M is of interest. For example, if a volumetric flow rate is measured simultaneously, information about the phase proportions of phases P1 and P2 in the medium M can be crucial for the measurement process, such as for invoicing raw materials delivered. This is immediately obvious if, for example, the first phase P1 of the medium M is liquid crude oil and the second phase P2 of the medium M is water. Fig. 7 ).

[0024] While the Figs. 1 to 6 rather procedural characteristics are highlighted in Fig. 7 A measuring device 2 for determining the volume fraction V% of a phase of the multiphase medium M is shown.

[0025] To determine the volume fraction V% of a phase of the multiphase medium M, it is known to apply a plurality of electrical excitation signals to the medium M via an electrode pair 3 and to record a plurality of corresponding electrical response signals. From the plurality of excitation signals and the plurality of response signals, a plurality of values ​​En for the first electrical parameter E of the medium M are determined.If the phase components P1, P2 are known with known values ​​for the first electrical parameter E, for example the specific electrical conductivities, for the phases P1, P2 in pure form, then it is obvious that a changing proportion of the phases P1, P2 in the medium M also leads to a changing value for the first electrical parameter E of the medium M, and a determination of the first electrical parameter E of the medium M also enables a determination of, for example, the volume fraction V%_P2 of the second phase P2 of the medium M.

[0026] At measuring device 2 in Fig. 7The device is a magnetic-inductive flowmeter with a measuring volume 6 for holding a medium M, which in this case is a measuring tube through which the medium M flows. The medium M has a first phase P1 with a first value E1 for a first electrical parameter E and at least temporarily a second phase P2 with a second value E2 for the first electrical parameter E. The measuring device 2 has a control and evaluation unit 4 and an electrode pair 3 in contact with the medium M. In the operating state of the measuring device 2, the control and evaluation unit 4 generates a magnetic field B by means of a magnetic field generation device 5 to fulfill the primary measurement task, namely the measurement of a volumetric flow rate through the measuring tube 6. Assuming a conductive medium M, this magnetic field generates a measuring voltage U in the medium M that depends on and is proportional to the flow velocity.This measuring voltage U is tapped via the electrode pair 3. In this way, flow information is obtained using the measuring device 2, which in this embodiment is a magnetic-inductive flowmeter. The magnetic-inductive flowmeter is a typical example of a measuring device 2 that already has an electrode pair 3, although this electrode pair 3 has a different function in the original measurement task – the flow measurement – ​​namely, the passive detection of the induced measuring voltage U in the medium M.

[0027] Measuring devices 2 do not need to be as in the case of the one in Fig. 7 In the example shown, they can perform an additional measurement task; they can also simply be used to determine the volume fraction V% of a phase of the multiphase medium M.

[0028] To determine the volume fraction V% of a phase of the multiphase medium M, the medium M is subjected to a plurality of electrical excitation signals via the electrode pair 3, and a plurality of corresponding electrical response signals are recorded. From the plurality of excitation signals and the plurality of response signals, a plurality of values ​​En for the first electrical parameter E of the medium M are determined. In the prior art, for example, the conductivity of the medium M is determined as the first electrical parameter E, and the volume fraction V% of the participating phases P1, P2 of the medium M is deduced from the determined conductivity of the medium.

[0029] The direct determination of the volume fraction V% of a phase of the medium M has several disadvantages, some of which are related to a material change of at least one of the phases of the medium M involved in the considered measurement volume 6 and thus to a change in the properties of the first electrical parameter E of the phases P1, P2 involved.

[0030] Method 1 described here takes a significantly different approach. Method 1 provides that, from the majority of determined values ​​En for the first electrical parameter E of the medium M, a standard deviation S(En) of a statistical measure of dispersion S is determined, and that, using a mathematical relationship f between the statistical measure of dispersion S of the first electrical parameter E and a volume fraction V%_P2 of the second phase in the medium M, the volume fraction V%_P2 of the second phase P2 in the medium M is determined using the determined standard deviation S(En) of the first electrical parameter.

[0031] The insight underlying Method 1 is that not only the direct value – as known from the prior art – of the first electrical parameter E of the medium M provides information about the volume fraction V%_P2 of the second phase P2 in the medium, but surprisingly also the standard deviation S(En) of the statistical measure of dispersion S, based on a plurality of measured values ​​of the first electrical parameter E. This makes the determination of the volume fraction V%_P2 of the second phase P2 in the medium M to a certain extent independent of the absolute values ​​for the first electrical parameter E of the medium M.

[0032] The underlying connections discovered in procedure 1 are in Fig. 1 exemplified by real measurements with a magnetic-inductive flowmeter 2, as in Fig. 7As shown, various measurements have been carried out for the first electrical parameter E of the medium M. Firstly, the conductivity σ of the medium M was determined as the first electrical parameter E, and secondly, the impedance of the medium, which is an alternating current quantity and as such has a magnitude (abs(impedance)) and a phase. These measurements are shown in the diagrams of the top row of Fig. 1 shown. In the bottom line of Fig. 1 The standard deviations S of a plurality of measurements En of the corresponding first electrical parameter E, in the form of the electrical conductivity σ and the absolute value and phase of the impedance of the medium M, are shown. The measurements were carried out at different frequencies.

[0033] The measurements in Fig. 1The measurements were carried out such that, while maintaining a constant volumetric flow rate of the first conductive phase P1 of the medium (liquid water at 2.4 l / s), the admixture of the second phase P2 (gaseous air) was continuously increased. In this respect, a change in the volumetric flow rate of one phase corresponds analogously to a change in the volume fraction of that phase. The graph shows measurements of the conductivity σ of the medium M as well as those of the complex-valued impedance of the medium, here divided into the absolute value of the impedance and the phase of the impedance. For each admixture of the second phase (air) P2 of the medium M, a plurality of values ​​En of the aforementioned electrical parameters E of the medium M were recorded. From the plurality of determined values ​​En for the first electrical parameter E of the medium M, a standard deviation S(En) of the statistical measure of dispersion S was then calculated.The standard deviation has been chosen as the statistical measure of dispersion S. It is surprising, but nevertheless recognizable, that a relationship f exists – often approximated linearly – between the volume fraction V%_P2 of the second phase in the medium M (which arises directly from the added proportion of air in the second phase P2) and the standard deviation S of the corresponding values ​​S(En) for the first electrical parameter E.

[0034] In the procedures described here, the excitation signal is an electrical voltage or an electrical current, and the electrical response signal is consequently an electrical current or an electrical voltage. If the electrical parameters E of the medium M are alternating current quantities, such as impedance or admittance, then the excitation signal is typically a harmonic oscillation with a corresponding excitation frequency.

[0035] The application of electrical excitation signals to the medium M takes place in a time range in which no other measurement data is acquired in the medium M, specifically in the case of the magnetic-inductive flowmeter 2 according to Fig. 7 The measurements are carried out after a switch in the polarity of the magnetic field B, which is generated by the magnetic field device 5, namely in the time domain of a non-stationary magnetic field B. If a measuring device is used to carry out the procedure 1 that has no other measuring task at all, i.e., that serves only to determine the volume fraction V% of a phase of a multiphase medium M, or only has a measuring task that does not physically conflict with the determination of the volume fraction, then of course no attention needs to be paid to a possible collision with another measurement acquisition.

[0036] Fig. 2Figure 1 shows the essential procedural steps for carrying out procedure 1. The first step depicts the multiphase medium M, with phases P1 and P2, located in a measuring volume 6. A pair of electrodes 3 applies a plurality of electrical excitation signals to the medium M, and a plurality of corresponding electrical response signals are recorded. From these signals, a plurality of values ​​En for the first electrical parameter of each medium are determined, for example, the electrical conductivity, impedance, admittance, etc. In the middle step, a dispersion value S(En) of the statistical measure of dispersion S, for example, the standard deviation, is determined from the plurality of values ​​En of the first electrical parameter E. Finally, in the last step, the mathematical relationship f between the statistical measure of dispersion S and the standard deviation is used to calculate the variance S(En).The specific volume fraction V%_P2(S(En)) of the second phase P2 is determined from the resulting dispersion value S(En) and the volume fraction V%_P2 of the second phase in the medium M.

[0037] The Figs. 3 to 6Figures 1 and 2 show measurement results obtained using method 1 regarding the volume fraction V%_P2 of the second phase P2 of the medium M. The upper diagram in each figure shows the measured values ​​of the first electrical quantity over time t, over a relatively long period of almost two hours. The lower diagram shows the corresponding course of the actual (dashed line) and the determined volume fraction V%_P2 of the second phase P2 of the medium M. The actual course of the volume fraction V%_P2 of the medium M is constant over long periods. The measurements were taken in a measuring setup that allows the volume fractions V% of phases P1 and P2 of the medium M to be precisely specified. Measuring instrument 2 is a magnetic-inductive measuring instrument according to [reference to relevant document]. Fig. 7 has been used, whose control and evaluation unit 4 is designed in such a way that it can execute the previously described procedure 1 in operation.

[0038] In procedure 1 according to Fig. 3 The electrical conductivity sigma of the medium M was used as the first electrical parameter E of the medium M.

[0039] In procedure 1 according to Fig. 4 The first electrical parameter E of the medium M is the impedance of the medium M, i.e., a two-valued electrical parameter defined in connection with harmonic alternating quantities as excitation and response signals. In this respect, the above representation of Fig. 4 The magnitude of the impedance and the phase of the impedance are represented.

[0040] In the Fig. 5 and 6 Only one of the two quantities of the complex-valued impedance is used, in Fig. 5 with the magnitude of the impedance and in Fig. 6 with the phase of the impedance.

[0041] The representations show that the method, based on the use of a value S(En) of a statistical measure of dispersion S based on determined values ​​En for the first electrical parameter E, is very well suited to quantitatively determine the volume fraction V%_P2 of the second phase P2 of the multiphase medium M.

[0042] In the procedures 1 according to the Fig. 3 and 5Furthermore, the determined dispersion value S(En) of the first electrical parameter E (electrical conductivity, absolute value of impedance) has been normalized to the absolute value of the first electrical parameter E, in this case to an absolute mean value of the first electrical parameter E calculated from the majority of determined values ​​En for the first electrical parameter E of the medium M. This achieves considerable insensitivity to material changes in the phases P1, P2 of the medium M, since the normalization to the absolute values ​​of the first electrical parameter renders them irrelevant. Such normalization of the phase angle is, of course, unnecessary, as it can only ever lie within a limited absolute range, regardless of the material properties of the medium.

[0043] In a preferred implementation of method 1, not explicitly described here, a plurality of values ​​for a second electrical parameter of the medium M are determined from the plurality of excitation signals and the plurality of response signals. If, for example, the magnitude of the impedance is used as the first electrical parameter, the phase angle of the impedance could be used as the second electrical parameter. A variance value of a statistical measure of dispersion is then also determined from the plurality of determined values ​​for the second electrical parameter of the medium M. Using a mathematical relationship between the statistical measure of dispersion of the second electrical parameter and the volume fraction of the second phase in the medium M, the volume fraction of the second phase in the medium is determined using the determined variance value of the second electrical parameter.In this design, it is advantageous to calculate an average volume fraction of the second phase of the medium from the volume fraction V%_P2 of the second phase P2 of the medium M determined with the first electrical parameter E of the medium and from the volume fraction of the second phase of the medium determined with the second electrical parameter of the medium.

[0044] The method 1 implemented in the measuring device 2 provides that the volume fraction V%_P2 of the second phase P2 in the medium M determined with the first electrical parameter E of the medium M and / or the volume fraction of the second phase of the medium M determined with the second electrical parameter of the medium and / or the averaged volume fraction of the second phase P2 in the medium M is signaled, namely optionally stored in a memory of the control and evaluation unit 4 and / or displayed and / or transmitted via a communication interface of the measuring device 2 to a connected communication partner.

[0045] The implementation of method 1 in the measuring device 2 further provides that if a first limit value is exceeded by the volume fraction V%_P2 of the second phase P2 in the medium M determined with the first electrical parameter E of the medium M and / or if a second limit value is exceeded by the volume fraction of the second phase of the medium M determined with the second electrical parameter of the medium and / or if a third limit value is exceeded by the averaged volume fraction of the second phase in the medium, the presence of a two-phase flow is signaled, namely optionally stored in a memory of the control and evaluation unit 4 and / or displayed and / or transmitted via a communication interface of the measuring device 2 to a connected communication partner.

[0046] Taking into account the representation of the functional relationships f in Fig. 1(lower three figures), it is comprehensible that the mathematical relationship f between the statistical measure of dispersion S of the first electrical parameter E and the volume fraction V%_P2 of the second phase of the medium M was determined by determining the dispersion value S(En) of the first electrical parameter E for at least two different but known volume fractions V%_P2 of the second phase P2 of the medium M, where the volume fractions V% in Fig. 1 correspond to the flow constituents of the second phase P2 of the medium M. In the exemplary embodiments, a linear relationship between the statistical measure of dispersion S of the first electrical parameter E and the volume fraction V%_P2 of the second phase P2 of the medium M has been assumed. Reference sign

[0047] 1. Method 2. Measuring device 3. Electrode pair 4. Control and evaluation unit 5. Magnetic field device 6. Measuring volume, measuring tube B Magnetic field U Induced voltage V% Volume fraction M Multiphase medium P1, P2 First and second phase of the medium E First electrical parameter of the medium E1 First value for the first electrical parameter of the first phase E2 Second value for the first electrical parameter of the second phase En Plurality of determined values ​​for the first electrical parameter S Statistical measure of dispersion S(En) Scatter value for the plurality of determined values ​​En for the first electrical parameter f Relationship between the statistical measure of dispersion S of the first electrical parameter E and the volume fraction V%_P2 of the second phase in the medium MV%_P2 Volume fraction of the second phase P2 in the medium M sigma Electrical conductivity

Claims

1. Method (1) for determining the volume fraction (V%) of a phase of a multiphase medium (M), wherein the medium (M) has a first phase (P1) with a first value (E1) for a first electrical parameter (E) and, at least temporarily, a second phase (P2) with a second value (E2) for the first electrical parameter, wherein the medium (M) is impinged with a plurality of electrical excitation signals via a pair of electrodes (3) and a plurality of corresponding electrical reaction signals are captured for the electrical excitation signals, wherein a plurality of values (En) for the first electrical parameter (E) of the medium (M) is determined from the plurality of excitation signals and the plurality of reaction signals, wherein a scattering value (S(En)) of a statistical scattering measure (S) is determined from the plurality of determined values (En) for the first electrical parameter (E) of the medium (M), wherein the volume fraction (V%_P2) of the second phase (P2) in the medium (M) is determined using a mathematical relationship (f) between the statistical scattering measure (S) of the first electrical parameter (E) and a volume fraction (V%_P2) of the second phase (P2) in the medium (M) with the determined scattering value (S(En)) of the first electrical parameter (E), wherein the first electrical parameter (E) of the medium (M) is the electrical conductivity (sigma) of the medium (M) and / or the absolute value of the impedance of the medium (M) and / or the phase angle of the impedance of the medium (M)2. Method (1) according to claim 1, characterized in that the excitation signal is an electrical voltage or an electrical current, and that the electrical response signal is an electrical current or an electrical voltage, in particular wherein the excitation signal is a harmonic oscillation with an excitation frequency.

3. Method (1) according to claim 1 or 2, characterized in that the impingement of the medium (M) with the electrical excitation signals takes place in a time domain in which no other measured value acquisition is carried out in the medium (M), that, in particular in the case of a magnetic-inductive measuring device, no magnetic-inductive flow measurement is carried out, then in particular after a switching of the polarity of the magnetic field (B), in particular in the time domain of a non-stationary magnetic field (B).

4. Method (1) according to any one of claims 1 to 3, characterized in that the standard deviation is calculated as the statistical scattering measure (S).

5. Method (1) according to any one of claims 1 to 4, characterized in that the electrical conductivity is determined from the real part of the impedance of the medium (M), taking into account the diameter of a measurement volume (6) for the medium (M).

6. Method (1) according to any one of claims 1 to 5, characterized in that the determined scattering value (S(En)) of the first electrical parameter is normalized to the absolute value of the first electrical parameter (E), in particular to an absolute mean value of the first electrical parameter (E) calculated from the plurality of determined values for the first electrical parameter (E) of the medium (M).

7. Method (1) according to any one of claims 1 to 6, characterized in that a plurality of values for a second electrical parameter of the medium (M) is determined from the plurality of excitation signals and the plurality of reaction signals, that a scattering value of a statistical scattering measure is determined from the plurality of determined values for the second electrical parameter of the medium (M), and that, using a mathematical relationship between the statistical scattering measure of the second electrical parameter and the volume fraction of the second phase in the medium (M), the volume fraction of the second phase in the medium is determined using the determined scattering value of the second electrical parameter.

8. Method (1) according to claim 7, characterized in that an averaged volume fraction of the second phase of the medium is calculated from the volume fraction (V%_P2) of the second phase (P2) of the medium (M) determined with the first electrical parameter (E) of the medium (M) and from the volume fraction of the second phase of the medium determined with the second electrical parameter of the medium.

9. Method (1) according to any one of claims 1 to 8, characterized in that the volume fraction (V%_P2) of the second phase (P2) in the medium (M) determined with the first electrical parameter (E) of the medium (M) and / or the volume fraction of the second phase of the medium (M) determined with the second electrical parameter of the medium and / or the averaged volume fraction of the second phase (P2) in the medium (M) is signaled, in particular is stored in a memory of a control and evaluation unit (4) and / or is displayed and / or is transmitted to a connected communication partner via a communication interface of a measuring device (2).

10. Method (1) according to any one of claims 1 to 9, characterized in that when a first limit value is exceeded, the presence of a two-phase flow is signalled by the volume fraction (V%_P2) of the second phase (P2) in the medium (M) determined using the first electrical parameter (E) of the medium (M) and / or when a second limit value is exceeded, the volume fraction of the second phase of the medium (M) determined using the second electrical parameter of the medium and / or when a third limit value is exceeded, the presence of a two-phase flow is signalled by the averaged volume fraction of the second phase in the medium, in particular is stored in a memory of a control and evaluation unit (4) and / or is displayed and / or is transmitted to a connected communication partner via a communication interface of a measuring device (2).

11. Method (1) according to any one of claims 1 to 10, characterized in that the mathematical relationship (f) between the statistical scattering measure (S) of the first electrical parameter (E) and the volume fraction (V%_P2) of the second phase of the medium and / or the mathematical relationship between the statistical scattering measure of the second electrical parameter and the volume fraction of the second phase (P2) of the medium (M) is determined in that the scattering value (S(En)) of the first electrical parameter (E) and / or the scattering value of the second electrical parameter are determined for at least two different but known volume fractions (V%_P2) of the second phase (P2) of the medium (M), in particular wherein a linear dependence is assumed between the statistical scattering measure of the first electrical parameter and the volume fraction of the second phase of the medium and / or between the statistical scattering measure of the second electrical parameter and the volume fraction of the second phase of the medium.

12. Method (1) according to claim 11, characterized in that more than two supporting points are recorded, i.e. more than two correlations between the statistical scattering measure (S) of the first electrical parameter (E) and the volume fraction (V%_P2) of the second phase (P2) of the medium (M), and a polynomial description of the relationship is determined as the mathematical relationship (f) between the statistical scattering measure (S) of the electrical parameter (E) and the volume fraction (V%_P2) of the second phase (P2) of the medium (M), or a description of the relationship is determined using spline interpolations, in particular by optimizing the descriptions of the relationships using the minimization of a deviation measure.

13. Measuring device (2) with a measurement volume (6) serving to accommodate a medium (M), wherein the medium (M) has a first phase (P1) with a first value (E1) for a first electrical parameter (E) and, at least temporarily, a second phase (P2) with a second value (E2) for the first electrical parameter (E), with a control and evaluation unit (4), with a pair of electrodes (3) in contact with the medium (M), wherein the control and evaluation unit (4), in the operating state of the measuring device (2), impinges a plurality of electrical excitation signals on the medium (M) via the pair of electrodes (3) and captures a plurality of corresponding electrical response signals for the electrical excitation signals, wherein a plurality (En) of values for the first electrical parameter (E) of the medium (M) is determined from the plurality of excitation signals and the plurality of response signals, characterized in that the control and evaluation unit (4) is designed such that the measuring device (2) carries out the method (1) according to any one of claims 1 to 12 during operation.

14. Measuring device (2) according to claim 13, characterized in that the measuring device (2) is a magnetic-inductive flowmeter with a pair of electrodes (3) for recording an electrical voltage induced in the medium (M), wherein the pair of electrodes (3) is also used to impinge a plurality of electrical excitation signals on the medium.