Level radar, level measurement method and computer readable medium

Abstract

The present invention provides a level radar for continuous level measurement. The level radar comprises a radar device and an impedance spectrum device. The impedance spectrum device is integrated in the radar device and is used to detect attachments on the radar device or to detect the gas phase of a filling material.

Description

Technical Field

[0001] The present invention relates to a material level measurement technology, and in particular to a material level radar for continuous material level measurement, a method for continuous material level measurement, a program element and a computer-readable medium. Background Art

[0002] Continuous level measurement can be carried out with the aid of a level radar which generates radar signals and emits them freely toward the surface of the filling material, or has an elongated probe, for example in the form of a rod, rope or tube, along which or in which the radar signals can be conducted toward the surface of the filling material.

[0003] In the latter case, the probe is usually immersed in the filling material, so that an impedance jump is generated at the interface between the filling material and the container environment, which can be detected in the reflected signal from the evaluation electronics of the level radar. In the case of a freely radiating level radar, an antenna is provided which transmits the radar signal toward the surface of the filling material.

[0004] Contamination on the antenna or probe can lead to distortion of the measuring signal and, in some cases, incorrect level output. Summary of the invention

[0005] Against this background, it is an object of the present invention to provide an improved level measuring device.

[0006] The first aspect of the present invention relates to a level radar for continuous level measurement, in particular to a free radiation level radar or a level radar using a guided radar signal. The level radar has a radar device for generating a radar signal and transmitting the radar signal toward a surface of a filling material.

[0007] Furthermore, an impedance spectroscopy device is provided, by means of which deposits on the radar device, in particular on the probe (in the case of guided radar signals) or on the antenna (in the case of free-radiating radar devices), can be detected.

[0008] The impedance spectroscopy device can also detect the gas phase of the filling material through impedance spectroscopy.

[0009] The impedance spectroscopy device is integrated in the radar device. Usually, the probe of the impedance spectroscopy device is installed in or on the radar device at a position where contaminants may appear and may cause interference.

[0010] If, for example, there are several locations where contamination from the filling material has a negative influence on the measurement result, the level radar can also have several such impedance spectroscopy devices.

[0011] The impedance spectroscopy device can reliably detect deposits. In particular, the measuring device can determine whether it is deposits or a filling state, that is, whether the corresponding position of the antenna / probe where the impedance spectroscopy device is installed is covered by the filling material or is only contaminated by the filling material.

[0012] Impedance spectroscopy equipment can also be used to determine if there is a vapor environment originating from the fill material or if there is just "normal" air on the fill material surface.

[0013] The impedance spectroscopy device can determine the AC resistance in the vicinity of the device. This AC resistance (also called impedance) is measured depending on the frequency of the applied AC current. To this end, the impedance is determined at multiple frequencies within a defined frequency range (spectrum). The "impedance peak" or the frequency dependence of the impedance varies with the medium at which the impedance spectroscopy device is located. If the antenna / probe is immersed in the medium, the impedance curve has a different shape and usually has a shifted peak compared to the case where the antenna / probe is not surrounded by a filler material. The situation is similar for attachments.

[0014] According to an embodiment of the invention, the radar device has a probe in the form of a rod, a rope or a tube for directing the radar signal to the surface of the filling material.

[0015] According to another embodiment of the invention, the impedance spectroscopy device has a sensor integrated in a seal of the probe head.

[0016] By integrating the sensor into, for example, a sealing cone of the probe, the sensor can be effectively protected from the vessel environment. The sealing cone is made of, for example, an insulating material such as PEEK, PPS, PTFE or ceramic.

[0017] According to another embodiment of the present invention, the sensor is designed in a ring shape.

[0018] According to another embodiment of the present invention, the fill level radar has an antenna for emitting radar signals toward the surface of the filling material. In this case, the sensor can be integrated in the antenna.

[0019] In particular, the sensor can be designed in the form of a strip or a cross.

[0020] In particular, the antenna can be used to transmit radar signals in polarized form, wherein the polarization plane of the radar signal is at a non-0 degree angle relative to the sensor, i.e. is not oriented parallel to the strips or the arms of the cross, but is tilted relative to the strips or the arms of the cross, so that the radar signal can pass through the sensor as unhindered as possible or only slightly hampered.

[0021] According to a further embodiment of the invention, the filling level radar has evaluation electronics for evaluating the radar signal reflected by the filling material surface in order thereby to calculate the filling level and for evaluating the measurements performed by the impedance spectroscopy device (i.e. the impedance spectrum) in order to determine whether there is accumulation on the radar device.

[0022] In particular, the fill level radar or the evaluation electronics is used to determine buildup in the connection region of the probe by means of impedance spectroscopy.

[0023] In the case of detection of buildup or vapor environments, the evaluation device can also be used to carry out a measured value correction of the fill level detected by the fill level radar. In this way, the measurement result can be improved.

[0024] A further aspect of the invention relates to a method for continuous fill level measurement, wherein buildup on a radar device of a fill level radar is detected by means of impedance spectroscopy.

[0025] A further aspect of the invention relates to a program element which, when executed on evaluation electronics of a fill level radar, instructs the evaluation electronics to detect buildup on a radar device of the fill level radar by means of impedance spectroscopy.

[0026] Another aspect of the invention relates to a computer medium on which the above-mentioned program element is stored.

[0027] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. The views in the accompanying drawings are schematic and not to scale. If the same reference numerals are used in the following description of the drawings, these same reference numerals describe the same or similar elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A level radar according to an embodiment of the present invention is shown.

[0029] Figure 2 A level radar according to another embodiment of the present invention is shown.

[0030] Figure 3 A level radar according to another embodiment of the present invention is shown.

[0031] Figure 4 A schematic diagram showing the configuration of a level radar according to an embodiment of the present invention.

[0032] Figure 5 A schematic diagram showing the structure of a level radar according to another embodiment of the present invention.

[0033] Figure 6 A flow chart showing a method according to an embodiment of the present invention is shown.

[0034] Figure 7 Three impedance measurement curves of a level radar according to another embodiment of the present invention are shown.

[0035] Figure 8 Two impedance measurement curves of a filling level radar according to an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0036] Figure 1 A level radar 100 is shown, which has a radar device 101 including a probe 104 in the form of a rod and an impedance spectrometer device including a sensor 106. An insulating sealing cone is located at a connection position (connection area) 111 of the probe 104, and the sensor 106 is integrated in the sealing cone to protect the sensor 106 from the container environment. For example, the sensor is arranged annularly around the probe 104 and is used to perform the impedance spectrometer technique.

[0037] Figure 2 A further embodiment of a level radar 100 is shown, wherein the level radar 100 is in the form of a free-radiating radar device having an antenna 105 with an insulating element, for example in the form of a PTFE lens, in which a sensor 107 of an impedance spectroscopy device is integrated.

[0038] exist Figure 2 In the case of a sensor 107, the sensor can also be designed in annular form and have a surface arranged, for example, parallel to the surface of the radome or lens. At least one thin layer of lens or radome material is located between the sensor 107 and the container environment or the filling material, so that the sensor is electrically insulated relative to the container environment.

[0039] like Figure 2 In the form of a free-radiation radar device, Figure 3 A further embodiment of a level radar 100 is shown, in which, however, the sensor 108 is designed in the shape of a cross. Figure 3 The left area of ​​​​the antenna shows a top view, in which the cross-shaped embodiment can be seen. The polarization plane of the emitted radar signal is indicated by arrow 120.

[0040] exist Figure 3 The right area of ​​​​the figure shows a cross-sectional view of the antenna 105. Here, it should be understood that the sensor 108 basically follows the shape of the radome or lens, but is arranged inside the lens so that the sensor is insulated in the direction of the container environment by the lens material.

[0041] By integrating the impedance spectroscopy device into the level radar, reliable overflow identification can be ensured. It is also possible to identify attachments in the connection area of ​​the probe / antenna, and it is possible to allow the level radar to switch between various applications (separation layers with and without an overlapping gas phase). "Separation layer with an overlapping gas phase" means that the (material) vapor environment is located above the fluid filling material. "Separation layer without an overlapping gas phase" means that there is no vapor environment above the material, but a lighter medium, such as oil.

[0042] Whether in guided radar devices or in free-radiation radar devices, the continuous level measurement can be improved by means of a level radar with an integrated impedance spectroscopy device, thus ultimately increasing the plant availability and the measurement reliability.

[0043] In particular, buildup in the connection area can be reliably detected. This detection can be used to adjust the sensitivity in the vicinity of the antenna and / or to update the interference signal suppression to avoid sudden changes in measured values.

[0044] Predictive maintenance of the radar can also be carried out by identifying buildup, and information that may affect the measurement can be provided to the customer in a timely manner.

[0045] The conditions detected by the impedance spectroscopy device (probe with deposits / steam environment in the container / probe without deposits but covered by filler material) can also be used to correct the measured values. For example, a propagation time correction can be performed in the case of a steam environment. This is also possible in the case of deposits, since the propagation time can depend on the layer thickness of the deposits.

[0046] Impedance spectroscopy ensures reliable overflow detection in all media situations, independent of the DK value of the filling material or the environment in the container and independent of whether the filling material is a fluid or bulk material. Because the impedance spectroscopy device is integrated into the level radar, no additional mechanical components are required in the process. Ultimately, it is also a redundant method for overflow detection.

[0047] By combining level measurement and impedance spectroscopy, the measured values ​​of the impedance spectroscopy can be used to optimize the level measurement and, by means of the redundant structure, ie the use of two measuring principles (radar signal / impedance spectroscopy), additional possibilities for identifying overflow situations are provided.

[0048] Figure 4 A schematic diagram of a level radar 100 according to an embodiment of the invention is shown. A common evaluation electronic device 103 is provided, which is associated not only with the radar device 101 but also with the impedance spectrometer device 102 and processes both measured values. In this common evaluation electronic device, control devices and signal generation devices for both the radar device and the impedance spectrometer device can be arranged in particular.

[0049] By switching the frequency of the generated measurement signal, both measurement physics components can be realized by the same evaluation electronics (hardware).

[0050] Figure 5 Another example of a filling radar 100 is shown, in which two measuring physics components 109 , 110 are designed separately to achieve a redundant structure. However, here too, the measured value evaluation is performed by the common evaluation electronics 103 .

[0051] Figure 6 6 is a flow chart of a method according to an embodiment of the present invention. In step 601, a radar signal is generated by an electronic device of a continuous level radar device. In step 602, the radar signal is emitted toward the surface of the filling material, in step 603, the radar signal is reflected at the surface of the filling material, and in step 604, the radar signal is detected again by the electronic device. In step 605, an impedance spectrum is performed to verify the correctness of the obtained measurement value by means of the impedance spectrum, and to correct the obtained measurement value if necessary, or to determine whether there is attachment / contamination on the measuring probe or antenna, or to determine whether the measuring probe / antenna is covered by the filling material at the connection position or immersed in the filling material.

[0052] A steam environment can also be detected. In the event of a steam environment or a detection of contaminants, the measured value of the level measurement can be corrected accordingly.

[0053] Figure 7 The impedance characteristics of an impedance spectroscopy device for a ketchup medium are shown as an example. The impedance (Z) is shown as a function of the frequency (f). Curve 600 describes the resonance characteristics of a clean measuring probe. Curve 601 shows the characteristics of a measuring probe contaminated with ketchup. If the measuring probe is completely covered with ketchup, the resonance characteristics of curve 602 result. Figure 7 As shown, the minima of the two measurement curves 602 and 600 differ in frequency by Δf. The impedances of the two minima of the measurement curves 602 and 600 differ by ΔZ. If the minimum of the resonance curve is located in region I, the evaluation electronics outputs the switching command "empty". If the minimum is located in region II, the switching command "full" is detected and output. The two defined switching ranges can be permanently programmed into the sensor at the factory or adjusted and changed by user target calibration (Kundenabgleich). Ideally, these ranges should be defined so that the default settings are sufficient for as many media as possible, since (time-consuming) user target calibration is undesirable. Basically, the entire frequency range is always traversed and analyzed in the evaluation of each measurement.

[0054] Figure 8The characteristics when there is an overlying environment (for example, by steam) are described as an example. Curve 700 shows the resonance characteristics when there is no overlying environment, and curve 701 shows the resonance characteristics when there is an overlying environment. Figure 7 , Figure 8 Impedance (Z) is shown as a function of frequency (f). Due to the overlying environment, the location of the resonance point is shifted by the amount of frequency 702 according to the DK value. In the case of steam, the DK value is mainly determined by the factors of pressure and temperature, wherein there is a fixed relationship between the two.

[0055] Related Applications Cross Reference

[0056] This application claims the benefit of European Patent Application No. 18 156 673.8 filed on February 14, 2018, which is incorporated herein by reference in its entirety.

Claims

1. A level radar (100) for continuous level measurement, comprising: A radar device (101) for generating a radar signal and transmitting the radar signal to a surface of a filling material; an impedance spectrum device (102), which is used to detect attachments on the radar device or to detect the gas phase of the filling material by means of impedance spectrum, in, The radar device (101) has an antenna (105), and the antenna (105) is used to transmit the radar signal to the surface of the filling material. The impedance spectrum device (102) has a ring-shaped, strip-shaped or cross-shaped measuring sensor, and the sensor is integrated in the antenna (105).

2. The level radar (100) according to claim 1, in, The antenna (105) is used to transmit the radar signal in a polarized manner. The polarization plane of the radar signal forms a certain angle with respect to the measuring sensor.

3. The level radar (100) according to claim 1 or 2, further comprising: Evaluation electronics (103) for evaluating the radar signal reflected by the surface of the filling material in order to calculate the fill level therefrom and for evaluating the measurement performed by the impedance spectroscopy device (102) in order to determine whether there is buildup on the radar device (101).

4. A level radar (100) for continuous level measurement, comprising: A radar device (101) for generating a radar signal and transmitting the radar signal to a surface of a filling material; an impedance spectrum device (102), which is used to detect attachments on the radar device or to detect the gas phase of the filling material by means of impedance spectrum, in, The impedance spectroscopy device is integrated in the radar device (101) The radar device (101) has a probe (104) for guiding the radar signal to the surface of the filling material. The impedance spectroscopy device (102) has a measuring sensor which is arranged in a ring shape around the probe (104) and is integrated in a seal (109) of the probe (104).

5. The level radar (100) according to claim 4, further comprising: Evaluation electronics (103) for evaluating the radar signal reflected by the surface of the filling material in order to calculate the fill level therefrom and for evaluating the measurement performed by the impedance spectroscopy device (102) in order to determine whether there is buildup on the radar device (101).

6. The level radar (100) according to claim 5, in, The evaluation electronics (103) are used to detect buildup in the connection region (111) of the probe (104) by means of impedance spectroscopy.

7. A method for continuous level measurement using the level radar (100) according to any one of claims 1 to 6, comprising the following steps: Impedance spectroscopy is used to detect deposits on a radar device (101) of a level radar (100).

8. The method according to claim 7, comprising the steps of: The material level is detected by using a level measuring device, wherein: The obtained measurements were verified with the help of impedance spectroscopy.

9. A computer-readable medium having a program element stored thereon, which, when executed on an evaluation electronic device (103) of a level radar (100) according to any one of claims 1 to 6, instructs the evaluation electronic device to execute the following steps: Impedance spectroscopy is used to detect deposits on a radar device (101) of a level radar (100).

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