DE19713267A1 - Method for determining the dielectric constant and / or the conductivity of at least one medium and device for carrying out the method - Google Patents

Abstract

The aim of the present invention is to optimize a capacitative level detector, which is particularly suitable for determining the location of a boundary layer (12) between water (10) and oil (11) in a separator tank. The known sensor principle consists of measuring the environment-dependent capacity between neighbouring electrodes (13, 4; 4, 5; 5, 6) of a rod-shaped probe (1). The invention is characterized in that the probe (1) is designed in such a way that in a more conductive medium (10) large ionic double-layer capacities occur at the electrodes (4, 5, 6, 13) and in a more isolating medium (11) small capacities are present between the electrodes (4, 5, 6, 13). To this end, the invention provides for a large electrode size (h), a relation of electrode size (h) to electrode distance (a) preferably in the range 1 < h / a < 6, and, in particular, a measuring frequency (f) between the dielectric limit frequencies of the media (10, 11). This enables a large capacity shift for a digital level indicator and/or a largely continuous capacity increase for an analogue level indicator to be obtained. In addition, the effect of conductive and/or isolating contaminant films (14) on the capacity signal is eliminated by suitable measuring frequencies and/or radial displacement of the electrodes (4, 5, 6, 13).

Description

Technical field

The present invention relates to the field of level indicators. It relates to a method for determining the dielectric constant and / or the conductivity of at least one medium, in particular suitable for determining the location of a boundary that shifts in the vertical direction layer between two media lying on top of each other different dielectric constant and / or conductivity, according to the upper concept of the first claim. The present invention further relates to a Device for performing the method.

State of the art

The invention is based on a not previously published German Pa tent registration with the file number 197 04 975.3. From the state of the Technology are also a variety of methods and devices for Determination of the level of a container known to be very low different physical measurement principles are based. Representing this be optical methods, gamma absorption methods, ultrasonic running time methods, radar reflection methods and electrical (capacitive or resistive) methods.

The capacitive methods can be used successfully anywhere where the boundary layer indicating the level two media (liquid-gas  or liquid-liquid) that separates one from the other have different dielectric constant ε, as z. B. with water (ε = 81) and petroleum (ε = 2.2-2.6) is the case.

So-called separation tanks are used for offshore oil production, which the different occurring during drilling or production "Phases" sand, water, oil and gas due to their density differences into different, superimposed layers. It is very important important to increase the height of the interface between the water and the oil know to accordingly the drain valves on the tank for the to operate and regulate the media. This is a reliable filling level measuring device required. Such a level gauge does not work or not correctly, and z. B. Oil in the water outlet has this around serious consequences in terms of world and cost. This event is therefore in the Industry viewed as "GAU".

The level measurement must therefore have at least two redundant systems men. Besides the usual systems, there are other possible systems the aforementioned gamma absorption method, an ul ultrasonic transit time method and a radar reflection method conceivable. Except it would be desirable if the separation tank in the case of offshore change on the sea floor (a few 100 meters below the ocean floor surface) could be instilled (what steel tank walls with 20 cm thickness required). This would allow only the oil extracted to be pumped up and not additionally water that is generated with great energy expenditure, which is pumped back into the sea after separation from the oil. Due to the arrangement of the separation tank on the sea floor and the fact that the pressure of the extracted oil (60-150 bar at temperatures of 55-120 ° C) is only released to atmospheric pressure on the surface of the sea, there are demands on the measuring system that are mentioned with the and other measuring methods partially used in normal pressure separators that are difficult to fulfill.

The focus is therefore on the use of capacitive measuring instruments methods. From the pressure and temperature conditions mentioned arise however, a reduced selection of materials and certain restrictions regarding the geometry of the measuring probe. The condition of the quasi-war  Freedom of movement requires a very reliable evaluation electronics also long-term stable measurement results for one and the same level. Soon the measuring probe should be robust in construction and simple and safe Connection to the measuring electronics located outside the separation tank enable. For the previously unpublished German Patent application, these requirements can be largely met. The Measurement according to the principle given there is essentially on egg NEN close range of the probe is limited, so that contamination by air blow, an emulsion layer some distance from the probe are barely detectable. It would also be desirable if any Abla wrestled on the probe. The redundancy of the Meßsy stems should also be increased so that an overall still reliable right, less error-prone, longer available and more precise measurement is enough.

Presentation of the invention

It is therefore an object of the invention, an electrical method and a Device for determining the dielectric constant and / or the conductance Ability to specify at least one medium, which process in particular which is suitable for determining the location of a shift in the vertical direction boundary layer between two layers lying one above the other Media of different dielectric constant and / or conductivity should, and which even under very difficult external conditions such. B. increased pressure and elevated temperatures a safe and trouble-free Level display possible. In particular, the above ge called procedures are improved so that the difficulties mentioned and disadvantages regarding redundancy, deposits and contamination in a certain distance from the probe can be avoided. This on in a method of the type mentioned at the outset by the Merk solved the first claim.

The essence of the invention is therefore that the complex impedance is at least one the electrodes arranged on the probe and a counter electrode will. Precisely because of the conductivity covered by the impedance measurement speed measurement, one achieves an improvement in the precision of the method  Redundancy. The capacity or conductivity of the impedance can not only between a first electrode of the probe and another one assigned to the first neten electrodes of the probe, but also between a first electrode and a counter electrode, e.g. B. the wall of a container or to one in the Container inserted metal plate can be measured. Especially the Kombinati On both measurement methods has great advantages, because the measurement to Ge Genelektrode examines the properties of the media surrounding the probe essentially in a far range while a measurement between two Electrodes of the probe provides information about the vicinity of the probe. By combining both methods, the media in the gan zen area can be measured. The near and far measurement can also can be achieved by using different electrode geometries. Large, widely spaced pairs of electrodes enable measurement essentially in the long range, while small areas were close to each other Measure the relevant electrodes, especially in the vicinity of the probe. The same ef fect is achieved by utilizing the skin effect: with very high fre sequences in the MHz range, the skin effect occurs and displaces the field lines so that they are no longer deep into the medium when viewed from the probe pass. Thus, using a multi-frequency method if in the depth (low frequencies and no skin effect) as well as in the near rich (high frequencies and skin effect) can be measured.

The conductivity is also measured at low frequencies, at which the ohmic properties of a capacitor, or a complex Impedance dominate, while at higher frequencies the capacitive egg properties prevail.

A preferred embodiment of the method according to the invention is characterized by the fact that a probe in the form of a tube is used, the associated electrodes are arranged on the outside or inside thereof are, and its interior against that surrounding the probe, with the medi en filled outdoor space is completed.

Another preferred embodiment of the method according to the invention is characterized in that on the outside or inside of the tube go through on one side in the direction of the pipe axis de electrode and on another side a plurality of in the direction of  Tube axis arranged below each other arranged segment-shaped electrodes hen, and each the stray capacitance between the continuous elec trode and one of the segment-shaped electrodes is measured, or that on the outside or inside of the pipe in the direction of the pipe axis on the other a plurality of pairs of electrodes made of opposing segment-shaped electrodes are arranged, and each the stray capacitance measured between the assigned electrodes of a pair of electrodes will, or that on the outside or inside of the tube towards the Pipe axis with each other a plurality of segment and ring-shaped elec troden are arranged, and that in each case the stray capacitance between in Rich direction of the tube axis adjacent electrodes or pairs of electrodes measured becomes.

In a first preferred development of this embodiment, the Measurements of the stray capacitance of the various associated electrodes used for digital display of the respective location of the boundary layer.

In a second preferred development of this embodiment, the measurements of the stray capacitance of the various associated electrical devices which is the mean value and for the analog display of the respective location of the Boundary layer used.

The device according to the invention is characterized in that the inside right of the probe against the outside space surrounding the probe is.

A preferred embodiment of the device according to the invention is characterized in that the probe be essentially from a tube stands, on the outside or inside of the assigned electrodes are brought that the assigned electrodes connected to test leads sen are that the measuring lines in the interior of the tube to the electrodes are guided that the tube consists of a non-conductive material, and that the measuring lines in the interior of the tube with a non-conductive Filler, preferably an epoxy resin, are cast.

The method and the device according to the invention can also advantageously for determining the composition of a mixture at least one  first and a second medium can be used, the first and second media with regard to their dielectric constants and / or their Differentiate conductivity.

Further embodiments result from the corresponding dependent ones Claims.

Brief description of the drawings

The invention is intended to be explained in the following using exemplary embodiments connection with the drawing will be explained in more detail. Show it

Fig. 1a, b in side view ( Fig. 1a) and in cross section ( Fig. 1b) the basic structure of a first preferred Ausführungsbei game of a device according to the invention;

FIG. 2 shows an exemplary measurement result achieved with an arrangement according to FIG. 1 in a container with a water / air interface; FIG.

Fig. 3 to Fig 2 corresponding mean value of the measurement results of all the electrode pairs.

Fig. 4a, b shows the schematic measuring arrangement for the measurement of the scattering capacity between two stacked annular electrode segments with the aid of two ring capacitors according to a preferred embodiment of the invention ( Fig. 4a) and the associated equivalent circuit diagram ( Fig. 4b);

Fig. 5 is a similar to Figure 2 with exemplary measurement result of an arrangement in accordance with Fig. 4.

FIG. 6 shows a measurement result comparable to FIG. 3 with an arrangement according to FIG. 4;

Fig. 7a, b the calculated partial field distribution for a configuration according to Fig 1b in the medium oil ( Fig. 7a) and water ( Fig. 7b);

FIG. 8a-d show various embodiments of probe or electrode geometries according to the invention;

Fig. 9a, b the structure of a pre-finished probe according to another embodiment of the invention; and

FIG. 10 shows the arrangement of the probe according to FIG. 9 in a separation tank;

Fig. 11 shows the structure of a probe toroidal electrodes;

Fig. 12 shows the construction of a probe with electrodes of different shapes and dimensions.

Ways of Carrying Out the Invention

In Fig. 1, the basic structure of an embodiment of a device according to the invention is shown in side view ( Fig. 1a) and in cross section ( Fig. 1b). Fig. 1a shows a portion of a rod-shaped probe 10 , which is made of a cylindrical, electrically insulating tube 11 , which surrounds an interior 12 . On the outside of the tube 11 , a plurality of pairs of electrodes 13 , 14 and 15 are arranged in the direction of the tube axis or probe axis. The electrodes can also be arranged on the inside of the tube 11 .

As the cross section shown in Fig. 1b shows through the probe 10 along the plane AA in Fig. 1A, each electrode pair of two opposing electrodes 14 a, b. The electrodes 14 a, b assigned in pairs in the electrode pairs 13 , 14 , 15 each form a capacitor with a complex impedance, the capacitance and conductivity of which are determined by the matter lying between the electrodes 14 a, b, namely the material of the tube 11 and the medium filling the interior 12 , but is also determined by the stray capacitance which results from the distribution of the electric field lines in the exterior around the probe 10 . The probe 10 and thus the electrodes 14 a, b are coated on the outside with an electrically insulating thin cover 16 which protects the electrodes 14 a, b against mechanical or chemical environmental influences.

The probe 10 is immersed for measuring the level in the stratification of the media to be sent with different dielectric constant, so that when the level changes, the interface between various media increases or decreases in the direction of the probe axis on the probe 10 . With such a shift in the interface of one of the electrode pairs 13 , 14 and 15 changes from a medium with a first dielectric constant (e.g. water with an ε of 81) to an adjacent medium with a second, significantly different dielectric constant (e.g. B. petroleum with an ε of 2.2-2.6) changes the capacitance and conductivity of the capacitor formed by the pair of electrodes. Since the interior 12 of the raw res 11 is closed to the outside surrounding the probe 10, however, the impedance of the electrode arrangement here is not caused by changing media inside, but only by the change of the medium in the outside or caused by this more or less strong displacement of the stray field is affected.

In order to make the change in the stray field clear, the field distribution in the presence of oil or water in the exterior was calculated for a configuration according to FIG. 1b for a segment of 90 °. The results are shown graphically in Fig. 7a (oil) and Fig. 7b (water). They clearly show how, with the distribution of the inner field remaining the same, the distribution of the stray field changes due to the change in the medium in the outside.

According to the present invention, it is not only possible to measure the influence of the media 103 , 104 surrounding the probe on the complex impedance of electrodes assigned to one another in pairs, but it is also possible to measure an influence on the conductivity always adhering to a capacitor. Oil is an extremely good insulator, while water and especially sea water conduct electricity well. Further important information can thus be obtained by alternative or combined recording of the influences on the conductivity. By choosing the measuring frequency, the conductivity, which dominates at low frequencies, or the capacitance, which dominates the characteristic of a capacitor at high frequencies, can be measured.

In addition, it is possible to measure not only between two electrodes of the probe assigned in pairs, but also between one or more electrodes of the probe and a counter electrode, e.g. B. in the form of embedded in a container comprising the media metal plates or the container wall 106 ( Fig. 10). This type of measurement provides information about the nature of the media at a certain distance from the probe, ie in a distant area from the probe, while the previously presented measurement method provides information about the media in the immediate vicinity of the probe. By combining both methods, the totality of the medium can be measured.

The same is achieved in that electrode pairs 13 and 14 with different shapes and dimensions are used as shown in FIG. 12 by way of example. The upper pair 13 in the figure has a comparatively large-area shape and the two electrodes are spaced far apart, while the lower pair 14 is designed to be small-area and close to one another. In the first pair 13 , the field lines or current paths will extend further into the adjacent medium (not shown), while the lower pair 14 can only be measured locally.

Another variant results from the use of the skin effect. By the skin effect displaces the field lines and is no longer sufficient far into the medium as without. The skin effect only occurs from Fri. frequencies from a few MHz to GHz, so that by appropriate choice of Measurement frequency with skin effect, d. H. at close range or without skin effect, d. H. can be measured in the far range.

Measurements were carried out with an exemplary probe 10 of the type shown in FIG. 1, the results of which are shown in the form of measurement curves in FIGS . 2 and 3. The electrode pairs had a height (in the direction of the probe axis) of 15 mm and a distance (center-center) of 30 mm. For practical reasons, the measurements were carried out in a water / air system (interface between water and air). Because the dielectric constants of air and oil are of the same order of magnitude, the results are practically the same as for a water and oil system. In the experiment, the capacity of the respective (a total of 7) pairs of electrodes was determined for different immersion depths of the probe 10 in a container filled with water. The measurement was carried out using an AC voltage method. A measuring frequency of 140 kHz was used. In principle, the capacitances can be measured with frequencies between some Hertz and some GHz, preferably between some 100 Hz and some MHz. In principle, the individual pairs of electrodes can also be measured with different frequencies of the AC voltage, for example to avoid crosstalk between adjacent pairs of electrodes. It is also possible to use an electrical pulse instead of an alternating voltage. In this case, low frequencies correspond to long pulse durations, high frequencies correspond to short pulse durations.

The complex impedance of the individual electrode pairs was that the probe was in the air, set to zero (offset correction). The value of this impedance, which is determined by the geometry of the electrode pairs, through their environment, but also through their electrical connection to the Given the measuring device was about 20-30 pF for the structure used. He is therefore of the same order of magnitude as the change in immersion the arrangement into the water. This high offset compared to the measurement result but did not result in measurement problems or measurement inaccuracies.

Fig. 2 shows the curves of the capacity curve for the 7 individual electrode pairs depending on the water level. Individual measurements were carried out with the water level in the middle of a pair of electrodes or in the middle between two vertically adjacent pairs of electrodes. It can be clearly seen that the capacity of the individual electrode pairs changes only (and then suddenly) when the water surface moves over it. This steep "switching" between two relatively constant capacitance values can be used to make a qua si-digital display of the level when z. B. each pair of electrodes individually controls a level indicator in the form of a lamp or the like. The lamp is switched on or off by the change in the capacitance value.

Another (analog) form of the display is conceivable if, as shown in FIG. 3, the mean value is formed between the capacitance values of the individual electrode pairs. This results in a linear curve between the fill level and the capacity, which can be implemented in a correspondingly linear manner on a display.

In the electrode arrangement shown in FIG. 1, the capacity, but above all the capacity difference used by the method according to the invention between oil and water as the medium surrounding the probe, decreases with increasing diameter of the probe 10 or of the tube 11 . Therefore, if for reasons of mechanical stability (bending stiffness) for large oil / water separators a larger probe diameter has to be selected due to the required length of the probe of several meters, it may be necessary or advantageous to choose a different measurement geometry as described in Fig. 8d is shown schematically. The electrode arrangement according to FIG. 8d does not comprise segment-shaped, opposite electrode pairs, but rather ring-shaped electrodes 84 , 84 , 85 arranged one above the other in the direction of the tube axis. Such a probe is advantageously used in an arrangement according to FIG. 4.

In the rod-shaped probe 40 from FIG. 4a, a plurality of mutually spaced-apart annular electrodes are arranged on a tube 41 , which in turn surrounds an interior 42 which is closed off from the outside, of which only two ( 43 and 44 ) are exemplary in the figure are shown. In this case, two adjacent electrodes 43 , 44 (arranged one above the other) each form a pair of electrodes whose capacitance is measured. Even better properties are achieved with toroidal electrodes, as shown in FIG. 11. With toroidal electrodes, which can be realized in particular in the form of a wire, there are no field line distortions due to sharp edges, but the rounded edges enable an even field distribution.

This arrangement of the ring electrodes also enables an even finer measurement by using the knife replacement circuit diagram as shown in Fig. 4b. The equivalent circuit diagram of the arrangement shown in FIG. 4b comprises three dominant capacitances, namely the stray capacitance 47 (Cs) changing with the surrounding medium and the constant ring capacitances 46 (Cr1) and 48 (Cr2) between the electrodes 43 , 44 and the tube 41 . For measurement solution, the arrangement is acted upon by an AC voltage source 45 with the AC voltage Ui and the output voltage Uo falling across the resistor Rm of the measuring device 49 is measured. This type of measurement is particularly suitable for measuring a changing capacitance, and the finest differences in the dielectric constants of the media surrounding the probe can be detected. It is also possible with such a measuring arrangement to detect the height of the interface between the oil phase and any gas phase that may be present.

However, the probe 40 of FIG. 4 can also be used for in connection with Figs. 1 to 3 described measuring method by direct measurement of the com plex impedance between two neighboring electrode rings. The advantage of the arrangement according to FIG. 4 in both measuring methods is that the capacitance values increase linearly as the diameter of the probe 40 increases.

To check the applicability of such a measurement geometry, the electrodes 14 a, b of each pair of electrodes 13 , 14 , 15 were used in the above-described probe according to FIG. 1, which was used for the measurements shown in FIGS . 2 and 3 electrically connected, and the capacitance measurements are carried out when the water level changes between two pairs of electrodes lying one on top of the other. The measurement results analogous to FIGS . 2 and 3 are shown in FIG. 5 (individual measurements) and FIG. 6 (mean value of the individual measurements). They make it clear that quasi-digital and analog level indicators can also be realized in the same way with the measuring arrangement according to FIG. 8d.

Fig. 8 shows examples of the various electrode geometries and measuring arrangements possible within the scope of the invention, with a partially sectioned section of a probe 50 , 60 , 70 or 80 being shown in each of the partial figures Fig. 8a-d. The electrodes are arranged, for example, on the outside of a tube; but they can just as well be arranged on the inside. In the example of Fig. 8a, two, extending in the direction of the tube axis de, opposing, continuous electrodes 53 , 54 are arranged inside the probe 50 on the outside of a tube 51 , which is laid by measuring lines laid inside the tube 51 and provided with a jacket 55 56 are connected to remote measuring electronics and are protected from the outside by a cover 52 . It is immediately apparent that with the probe 51 due to the lack of segmentation of the electrodes 53 , 54 no quasi-digital but only analog fill level determinations are possible.

In the example of FIG. 8b, inside the probe 60 on the outside of a tube 61 on one side there is a continuous electrode 63 which extends in the direction of the tube axis and on another side a plurality of electrodes which are arranged one below the other and spaced apart in the direction of the tube axis, segment-shaped electrodes 64 , 65 , 66 are provided. Each of the seg ment-shaped electrodes 64 , 65 , 66 forms together with a portion of the opposite continuous electrode 63 a measuring arrangement, the impedance, capacitance or stray capacitance is measured individually. Here, too, the electrodes are protected by a cover 62 and connected to the measuring electronics by measuring lines laid in the interior of the tube 61 and provided with a casing 67 . By segmenting the electrical 64 , 65 and 66 on one side of the tube 61 , a similar measurement behavior (optionally quasi-digital and analog) is achieved, as in the arrangement according to FIG. 1 and FIG. 8c.

In the example of FIG. 8c, as already shown in FIG. 1, in the probe 70 on the outside of a tube 71 in the direction of the tube axis, a plurality of electrode pairs of mutually opposing, segment-shaped electrodes 73a , b, 74a , b and 75 a, b are arranged, which are protected by a cover 72 and connected via test tubes 77 which are laid inside the tube 71 and surrounded by a sheath 76 . The measurement can be carried out here either between the opposing electrodes 73 a, b or 74 a, b or 75 a, b. The results then correspond to those explained in connection with FIG. 1. However, it can also take place between two pairs of electrodes lying one above the other if the individual electrodes of each pair are connected to one another. The results then correspond to those for the arrangement shown in FIG. 8d.

In the example of Fig. 8d are in the probe 80 on the outside of a pipe 81 in the direction of the tube axis with each other a plurality of annular electrodes 83, 84, arranged 85, which is protected by a cover 82 who to and provided by a jacket 86, measuring lines 87 laid inside the tube 81 are connected. In this case, the capacitance measurement is carried out between electrodes one above the other, as has been explained above in connection with FIG. 4.

All embodiment shown in Fig. 8 of the Son de invention are characterized by a compact and robust structure. In all of them, the change in the capacitance between the electrodes is not measured directly, but rather the change in the stray capacitance due to the change in the medium surrounding the probe. The tube 51 , 61 , 71 and 81 consists of a non-conductive material such as plastic, plexiglass, PVC, glass, ceramic or the like. The electrodes 53 , 54 , 63-66 are on the tube 51 , 61 , 71 and 81 , respectively , 73 a, b- 75 a, b and 83 - 85 attached. You will be contacted by the inside of the tube 51 , 61 , 71 and 81 installed measuring lines 56 , 68 , 77 and 87 through bushings (simple boreholes). The inside of the tube with the sheathed measuring lines 56 , 68 , 77 and 87 is preferably poured out with an epoxy resin. This ensures stable basic capacities and makes the probe 50 , 60 , 70 and 80 resistant to high pressure. The electrodes 53 , 54 , 63-66 , 73 a, b- 75 a, b and 83 - 85 are preferably made by means of a tubular shape with a thin non-conductive cover 52 , 62 , 72 or 82 made of epoxy resin or another suitable, non-conductive material covered (poured). Since the signal difference between water and oil or between media with different dielectric constants is particularly large if the cover 52 , 62 , 72 or 82 is thin, a thin glass fiber covering, which is coated with epoxy resin, is also suitable for this. Except for electrodes 53 , 54 , 63-66 , 73 a, b- 75 a, b and 83 - 85 and measuring lines 56 , 68 , 77 and 87, the same material type for the whole probe 50 , 60 , 70 and . 80 used, there is an increased (mechanical) temperature resistance because mechanical stresses due to different thermal expansion coefficients are missing.

The complete probe 90 shown in FIG. 9 with the tube 91 , the cover 92 , the electrodes 93 a, b to 95 a, b and the measuring lines 97 provided with a jacket 96 ( FIG. 9b) is closed at the lower end and ends at the upper end in a probe head 99 , which comprises a pressure-tight passage of the measuring lines 97 ( FIG. 9a). The electrodes 93 a, b to 95 a, b of this exemplary embodiment, when unrolled from tube 91 , have a shape which differs from the rectangular shape, unlike the electrodes described above. Such a deviating form can be expedient in order to influence the measurement curve of the capacitance over the fill level. In particular, the segment-shaped electrodes can have a triangular and / or trapezoidal shape in the unrolled state in order to achieve quasi-linearization within a segment. By means of a flange 98 , the probe 90 can be installed in an opening provided in the container to be monitored.

The example of such a container 100 in the form of an oil / water separator for offshore use is shown in FIG. 10. The container 100 is by means of legs 101 , 102 on a support z. B. set up the sea floor, the deck of a ship or an oil rig. The probe 90 with probe head 99 and flange 98 is inserted from above and screwed ver with the container 100 . Inside the container 100 is a layer of oil 104 (top) and water 103 (bottom), which is separated by an oil / water boundary layer 105 . The level of this boundary layer is monitored by probe 90 .

However, the invention can also be used to determine the composition of a Mixture of at least a first and a second medium, the first and second media with respect to their dielectric constants and / or differentiate their conductivity. Depending on the proportion of One medium in the other will be the impedance between the electrodes to change. Due to this change, the composition of the Mixture can be determined.

Overall, the invention results in a level measurement, which is characterized by the following characteristic features and advantages:

• - It is very simple and therefore durable and inexpensive. Nothing else as a rod-shaped probe hangs vertically in the separator or a belie other tank.
• - There are no active elements inside the tank. The relatively simple The evaluation electronics are outside the volume to be measured mens.  
• - The implementation from a high pressure tank is simple; the electrical test leads offer because they are installed inside the probe are no implementation problems.
• - The method uses with the dielectric constant or the conductivity the physical property of the two media water and oil from, in who differ the most.
• - If a temperature measurement is necessary (as an additional measured variable or as a compensation variable for large temperature fluctuations), can a corresponding measuring probe simply, for. B. in the tube between the Electrodes.
• - Especially when using segmented electrodes is a gefor derte measurement resolution or accuracy by the selected vertical Distance inherently between two pairs of electrodes or ring electrodes given. Distances <2 cm are easy to implement; they are theoretical Even small distances are possible, but the capacity decreases.
• - The stray capacitance is preferably measured in order to switch on the fill level demonstrate.
• - The method is suitable for high pressures (e.g. 300 bar) and / or aggressive ve and / or contaminated media and / or media which are the measurement direction with time.
• - The measurement can in the embodiments with segmented electrical either digital (discrete level measurement) and / or analog be carried out (continuously).
• - The method is also particularly suitable to fill a water level filled tanks (there is air above the water) e.g. B. in water treatment systems, water purification systems or saturated steam tanks voices.
• - The measurement both at close range and at far range, be it under Utilization of the skin effect, the electrode geometries or a counterpart  electrode, allows a more precise detection of an emulsion layer, e.g. B. be standing in oil in water or water in oil or air bubbles in one the media.
• - The targeted measurement at close range can also cause unwanted Deposits can be found on the probe. Their influence on the The measurement result can be compensated if necessary.
• - The same is possible with a clever choice of field distribution by Be influence of the shape and dimensions of the electrodes.
• - The use of an additional conductivity measurement results in valuable le Additional information that can be used redundantly if necessary.
• - The various methods for measuring at close range and in the far range rich as well as the use of capacitance or conductivity measurement can be combined in large quantities, so that for the special Optimal measurement accuracy is achieved.

Reference list

10th

Probe (rod-shaped)

11

pipe

12th

Interior (pipe)

13

,. . .,

15

Pair of electrodes

14

a, b electrode

16

cover

40

Probe (rod-shaped)

41

pipe

42

Interior (pipe)

43

,

44

Electrode (ring-shaped)

45

AC voltage source

46

,

48

Ring capacity

47

Stray capacity

49

Measuring device

50

,

60

,

70

,

80

Probe (rod-shaped)

51

,

61

,

71

,

81

pipe

52

,

62

,

72

,

82

cover

53

,

54

Electrode (continuous)

55

,

67

,

76

,

86

Sheathing (test leads)

56

,

68

,

77

,

87

Test leads

63

Electrode (continuous)

64

,. . .,

66

Electrode (segment-shaped)

73

a, b electrode (segmented)

74

a, b electrode (segmented)

75

a, b electrode (segmented)

83

,. . .,

85

Electrode (segment-shaped, ring-shaped)

90

Probe (rod-shaped)

91

pipe

92

cover

93

a, b electrode

94

a, b electrode

95

a, b electrode

96

Sheathing (test leads)

97

Test leads

98

flange

99

Probe head

100

container

101

,

102

Mainstay

103

water

104

oil

105

Oil / water interface

106

Wall of the container

Claims (36)

1. A method for determining the dielectric constant and / or the conductivity of at least one medium ( 103 , 104 ), in particular suitable for determining the location of a boundary layer ( 105 ) shifting in the vertical direction between two media ( 103 , 104 ) of different dielectric constant and one lying on top of the other / or conductivity, in which method one with at least two electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) equipped rod-shaped probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) kept immersed in the media is characterized in that the influence of the probe (10, 40, 50, 60, 70, 80, 90) surrounding media (103, 104) ness on the complex impedance, and in particular, the capacitance and / or conductivity, at least one of the electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 7 3 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and a counter electrode, in particular a wall ( 106 ) of a container ( 100 ) comprising the surrounding media ( 103 , 104 ), an electrode inserted into the container ( 100 ) or the other electrode ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) is measured. 2. The method according to claim 1, characterized in that in addition, the complex impedance between two pairs of mutually assigned electrodes th ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) ge is measured, with essentially the influence of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) surrounding media ( 103 , 104 ) on the stray field or the scattering capacity ( 47 ) of the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) ge. 3. The method according to claim 1 or 2, characterized in that for measuring the influence on the stray field or the stray capacitance ( 47 ) of the electrodes to be assigned ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) or to measure the Influence on the capacity of at least one of the electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b ; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and the counter electrode an AC voltage and / or an electrical pulse is used. 4. The method according to claim 3, characterized in that a AC voltage and / or an electrical pulse with frequencies between a few Hz and a few hundred MHz, preferably in the range between 100 and 500 kHz is used. 5. The method according to claim 1 or 2, characterized in that for measuring the influence on the conductivity between the associated electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65th , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) or to measure the influence on the conductivity between at least one of the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and the counter electrode an AC voltage and / or an electrical pulse is used. 6. The method according to claim 5, characterized in that a AC voltage and / or an electrical pulse with a frequency in the loading range from a few Hz to a few hundred Hz. 7. The method according to any one of claims 1, 2, 3 or 5, characterized records that for combined and / or successive measurement of Influence on the capacity and on the conductivity of an AC voltage which is a combination of a high and a low frequency has or switched between a high and a low frequency is, and / or an electrical pulse with two different pulse durations becomes.   8. The method according to any one of claims 1 to 7, characterized in that a probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) in the form of a tube ( 11 , 41 , 51 , 61 , 71 , 81 , 91 ) is used, on the outside of which the electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a , b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) are arranged, and its interior ( 12 , 42 ) against which the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) surrounding, filled with the media th outer space. 9. The method according to claim 8, characterized in that on the outside of the tube ( 51 ) two, extending in the direction of the tube axis, opposite, continuous electrodes ( 53 , 54 ) are arranged, and that the stray capacitance of the two electrodes ( 53 , 54 ) is measured. 10. The method according to claim 8, characterized in that on the outside of the tube ( 61 ) on one side in the direction of the Rohrach se extending, continuous electrode ( 63 ) and on another side a plurality of arranged in the direction of the tube axis with each other seg ment-shaped electrodes ( 64 , 65 , 66 ) are provided, and that in each case the stray capacitance between the continuous electrode ( 63 ) and one of the segment-shaped electrodes ( 64 , 65 , 66 ) is measured. 11. The method according to claim 8, characterized in that on the outside of the tube ( 71 ) in the direction of the tube axis with each other a plurality of pairs of electrodes ( 13 , 14 , 15 ) from opposite, segment-shaped electrodes ( 14 a, b; 73 a, b, 74 a, b; 75 a, b) are arranged, and that in each case the stray capacitance between the assigned electrodes ( 14 a, b; 73 a, b, 74 a, b; 75 a, b) of a pair of electrodes ( 13 , 14 , 15 ) is measured. 12. The method according to claim 8, characterized in that on the outside of the tube ( 71 ) in the direction of the tube axis with each other a plurality of pairs of electrodes ( 13 , 14 , 15 ) from opposite, segment-shaped electrodes ( 14 a, b; 73 a, b, 74 a, b; 75 a, b) are arranged, and that in each case the stray capacitance between adjacent pairs of electrodes ( 13 , 14 , 15 ) connected in the direction of the tube axis is measured. 13. The method according to claim 8, characterized in that a plurality of annular or toroidal electrodes ( 83 , 84 , 85 ) are arranged on the outside of the tube ( 81 ) in the direction of the tube axis, and that in each case the stray capacitance between in the direction electrodes ( 83 , 84 or 84 , 85 ) adjacent to the tube axis are measured. 14. The method according to any one of claims 10 to 13, characterized in that the measurements of the stray capacitance of the various assigned electrodes ( 63 , 64 or 63 , 65 or 63 , 66 or 73 a, b or 74 a, b or 75 a, b or 83 , 84 or 84 , 85 ) can be used for digital display of the respective location of the boundary layer. 15. The method according to any one of claims 10 to 13, characterized in that from the measurements of the stray capacitance of the various associated electrodes ( 63 , 64 or 63 , 65 or 63 , 66 or 73 a, b or 74 a , b or 75 a, b or 83 , 84 or 84 , 85 ) the mean value is formed and used for the analog display of the respective location of the boundary layer. 16. The method according to any one of the preceding claims, characterized in that for determining the complex impedance of the or each medium immediately surrounding the probe, the influence of the media ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) immediately surrounding media ( 103 , 104 ) on the capacitance of the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) ge is measured and that to determine the complex impedance of the or each of the medium surrounding the probe at a certain distance from the probe, the influence of the media surrounding the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) ( 103rd , 104 ) on the capacity and / or the conductivity of at least one of the assigned eten electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and the counterelectrode, in particular a wall ( 106 ) of a container ( 100 ) comprising the surrounding media ( 103 , 104 ) or an electrode inserted into the container ( 100 ) , is measured. 17. The method according to any one of claims 1 to 15, characterized in that to determine the complex impedance of the or each medium immediately surrounding the probe, the influence of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) immediately surrounding media ( 103 , 104 ) on the capacitance of the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a , b) is measured by means of paired first electrodes, the shape and dimensions of which are selected such that electric field lines or current paths between the electrodes essentially run only in a close range of the probe, and that the probe is used to determine the complex impedance of the or each surrounding medium at a certain distance from the probe the influence of the (104 103) on the capacitance of the associated electrode (13, 14, 14 a, b, the probe (10, 40, 50, 60, 70, 80, 90) surrounding media, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) is measured by means of paired second electrodes, whose shape Dimensions are chosen so that electrical field lines or current paths between the electrodes run in a distant area of the media surrounding the probe. 18. The method according to claim 17, characterized in that the Shape and dimensions of the first paired electrodes small flat and / or close to each other, the shape and dimensions of the second Electrodes assigned in pairs over a large area and / or further apart to get voted. 19. The method according to any one of claims 1 to 15, characterized in that to determine the complex impedance of the or each medium immediately surrounding the probe, the influence of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) immediately surrounding media ( 103 , 104 ) on the capaci ity of the associated electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a , b) is measured with an alternating voltage and / or an electrical pulse, the frequency of which is chosen so high that the skin effect occurs, and that for determining the complex impedance of the or each medium surrounding the probe at a certain distance from the probe Influence of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) surrounding media ( 103 , 104 ) on the capacitance ( 47 ) of the associated electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) and / or on the conductivity between the assigned electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) is measured with an alternating voltage and / or an electrical pulse whose frequency is selected so high that the skin effect does not yet occur. 20. Apparatus for performing the method according to claim 1, comprising a rod-shaped probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ), on the outside or inside of which at least two electrodes ( 13 , 14 , 14 a, b , 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) are arranged, characterized in that the interior of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) relative to that of the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) surrounding the outdoor space is complete. 21. The apparatus according to claim 20, characterized in that the probe ( 10 , 40 , 50 , 60 , 70 , 80 , 90 ) consists essentially of a tube ( 11 , 41 , 51 , 61 , 71 , 81 ) on which Electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) are applied. 22. The apparatus according to claim 21, characterized in that the associated electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) are connected to measuring lines ( 56 , 68 , 77 , 87 , 97 ), and that the measuring lines ( 56 , 68 , 77 , 87 , 97 ) in the interior ( 12 , 42 ) of the tube ( 11 , 41 , 51 , 61 , 71 , 81 ) to the electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) . 23. The device according to claim 22, characterized in that the tube ( 11 , 41 , 51 , 61 , 71 , 81 ) consists of a non-conductive material, in particular plastic, glass or a ceramic, and that the measuring lines ( 56 , 68 , 77 , 87 , 97 ) in the interior ( 12 , 42 ) of the tube ( 11 , 41 , 51 , 61 , 71 , 81 ) are cast with a non-conductive filler, in particular plastic, preferably an epoxy resin. 24. Device according to one of claims 20 to 23, characterized in that the electrodes ( 13 , 14 , 14 a, b, 15 ; 43 , 44 ; 53 , 54 ; 63 , 64 , 65 , 66 ; 73 a, b , 74 a, b, 75 a, b; 83 , 84 , 85 ; 93 a, b, 94 a, b, 95 a, b) with an electrically insulating cover ( 16 , 52 , 62 , 72 , 82 , 92 ) are provided. 25. The device according to claim 24, characterized in that the cover ( 16 , 52 , 62 , 72 , 82 , 92 ) contains an epoxy resin or a ceramic or consists of glass. 26. The apparatus according to claim 25, characterized in that the cover ( 16 , 52 , 62 , 72 , 82 , 92 ) is fiber reinforced. 27. The device according to one of claims 20 to 26, characterized in that on the outside of the probe ( 50 ) or the tube ( 51 ) two, extending in the direction of the probe or tube axis, opposite, continuous electrodes ( 53 , 54 ) are arranged. 28. Device according to one of claims 20 to 26, characterized in that on the outside of the probe ( 60 ) or the tube ( 61 ) on one side a continuous electrode extending in the direction of the probe or tube axis ( 63 ) and on another side a plurality of seg ment-shaped electrodes ( 64 , 65 , 66 ) arranged one below the other in the direction of the probe or tube axis. 29. Device according to one of claims 20 to 26, characterized in that on the outside of the probe ( 70 ) or the tube ( 71 ) in Rich direction of the probe or tube axis with each other a plurality of pairs of electrodes ( 13 , 14th , 15 ) from opposite, segment-shaped electrodes ( 14 a, b; 73 a, b, 74 a, b; 75 a, b) are arranged. 30. Device according to one of claims 20 to 26, characterized in that on the outside of the probe ( 80 ) or the tube ( 81 ) in Rich direction of the probe or tube axis with each other a plurality of segment, ring or toroidal electrodes ( 83 , 84 , 85 ) are arranged. 31. Device according to one of claims 28 or 29, characterized in that the segment-shaped electrodes ( 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b) have a rectangular shape in the rolled state. 32. Device according to one of claims 28 or 29, characterized in that the segment-shaped electrodes ( 64 , 65 , 66 ; 73 a, b, 74 a, b, 75 a, b) in the unrolled state a different from the rectangular, in particular have a triangular and / or trapezoidal shape. 33. Apparatus according to claim 30, characterized in that the toroidal electrodes are built up from a wire surrounding the tube ( 81 ). 34. Apparatus according to claim 28, characterized in that two Types of electrodes assigned to one another in pairs are provided where for the first type close to each other and / or small area and the second type is further apart and / or built up over a large area. 35. Method for determining the composition of a mixture at least a first and a second medium, the first and second media with regard to their dielectric constants and / or their conductance distinguish ability, characterized in that a method for loading tuning the complex impedance according to one of claims 1 to 19 ver is applied. 36. Device for determining the composition of a Gemi cal at least a first and a second medium, the he most and second media with regard to their dielectric constants and / or distinguish their conductivity, characterized in that a Vorrich device according to one of claims 20 to 35 is used.