TWI568994B - Fill measuring device having a heated antenna - Google Patents

Description

Filling degree measuring device with heating antenna

According to the introduction of claim 1, the present invention relates to a filling level measuring device, and more particularly to a radar wave filling level measuring device for measuring the degree of filling in a container or for measuring the height of bulk goods in a container.

It is known to use a sensor for measuring the degree of filling in a container filled with liquid or bulk cargo. The measurement of the degree of filling is often performed here via high frequency signal runtime detection, and the sensor is embodied as a horn antenna or a parabolic antenna.

Such filling level measuring devices can be used to measure the degree of filling of a liquid, or to measure the degree of filling of a bulk cargo, or to limit the determination of a liquid or bulk cargo. The measurements here often occur in containers that must be hermetically sealed from the surrounding atmosphere, either because the container is pressurized or exhibits a high temperature atmosphere, or because corrosive media must be used to measure the degree of filling in the container. The container or hopper may also be open to the atmosphere.

When the high-frequency signal operation time is used to measure the degree of filling, the high-frequency pulse is radiated by the antenna and reflected on the surface of the medium. The reflected high frequency pulses are received by the sensor. Sensor away from each other The distance of the surface of the medium can be determined by the time difference between the transmission of the high frequency pulse and the reception of the reflected high frequency pulse. The high frequency pulse train is in the range of the radar wave, so that the respective fill level measuring devices often display a microwave transceiver that radiates microwave radiation in the C band, the K band, or the W band. Antennas of this range are typically horn antennas or horn antennas coupled to parabolic antennas. The microwave transceiver generates microwave radiation which is then radiated by a hollow conductor and a horn antenna disposed at one end of the hollow conductor. The antenna is aligned with the interior of the container to allow for the determination of the degree of filling of the bulk cargo contained in the container or the liquid contained in the container.

Since the antenna assembly must be protected from environmental influences such as dust or condensation, the antenna of the filling level measuring device generally has an antenna cover. On the one hand, the antenna cover must protect the antenna assembly from the atmosphere of the container, and on the other hand avoid affecting the microwave or radar signals emitted by the microwave transceiver.

In such an antenna cover, the disadvantage is that dust and condensate will precipitate on the antenna cover (if it accumulates, it may cause encrustation), and thus the reference echo is attenuated and noise echo may occur (noise Echo). This results in an inability to measure, or at least not sufficiently accurate, the distance between the filling level measuring device and the surface of the bulk cargo or liquid to be measured.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a filling level measuring device which can be reliably used even in a corrosive ambient atmosphere as long as it measures the degree of filling.

The device of claim 1 achieves this purpose. The dependent items disclose advantageous embodiments.

To achieve this object, the present invention provides a filling level measuring apparatus comprising: a microwave transceiver; an antenna connected to the microwave transceiver, comprising an exit hole for a targeted emission of microwave radiation; and The exit aperture and the antenna cover of the exit aperture are closed in a sealed manner. According to the invention, the filling level measuring device additionally comprises a heating device, which can be heated by the heating device. In this manner, when dust is generated so as to be combined with coagulation, formation of coagulum on the antenna is prevented, and the soaping is reduced, and the crust is not formed again. In this way, the attenuation of the noise echo and the reference echo are reduced, which ensures that the measurement of the filling level is reliable even in the atmosphere of aggressive and condensate forming environments.

Advantageously, the heating device is arranged in an electrical resistance heater of the antenna cover. Preferably shown is at least one dual core supply line for electrical connection of a resistive heater comprising a power source, the resistive heater being disposed on the antenna cover such that it directly heats the antenna cover via thermal conduction when connected to a live power source. The electric resistance heater is directly disposed on the antenna cover and can be directly heated, and can be designed to have a relatively simple means.

The antenna cover preferably exhibits a surface in the form of a cone on the outside of the antenna, and an advantageous surface repels the fluid. The antenna cover is formed in such a way that during any liquid condensation formation, the condensate can drain down and drip.

The antenna cover may, for example, represent an antenna lens for aggregating microwave radiation into a bundle. In this way, simple mechanical means can be used to ensure that the microwave signal is focused and precisely aligned.

In order to ensure uniform heating of the surface of the antenna cover that is directed from the measurement direction, the electrical resistance heater is configured to extend at or within the antenna cover.

Preferably, the electric resistance heater comprises two longitudinal sections arranged in parallel with one another, which are connected to each other at their ends by means of transverse sections, the longitudinal sections being linearly extended and having a length which is at least twice the length of the transverse section, preferably At least four times. The electrical resistance heater can then be aligned with the antenna such that the longitudinal section of the electrical resistance heater is configured to be perpendicular to the polarization of the microwave radiation. In this way, the resistive heater can be aligned such that the radiated microwave radiation is as attenuated as little as possible. On the other hand, the electric resistance heater can simultaneously polarize the echo signal so that, for example, the parasitic microwave radiation reflected on the wall of the vessel and changing in the direction of the forward polarization is at least partially suppressed.

Here, a low cost and lightweight antenna embodiment can be realized such that the antenna is produced from a metal coated plastic.

The antenna cover preferably comprises a non-conductive plastic, and particularly preferably comprises polytetrafluoroethylene (PTFE). The advantage of this type of plastic is that it attenuates the microwave signal to only a trace level.

Preferably, the antenna cover is attached to the metal ring at the end of the antenna, preferably via a screw connection. This metal ring can also be advantageously embodied as a part of the device flange or as a device flange which can be arranged in a sealed manner in the container. Sealing (preferably anti-compression sealing connection) is especially necessary when the atmosphere inside the interior of the container should be safely separated from the atmosphere on the outside of the container. In this way, a simple and sealed antenna cover can be implemented on the antenna. This metal ring provides a secure connection between the antenna cover and the antenna. When metal When the ring system is embodied as a part of the device flange or on behalf of the device flange, on the one hand, the atmosphere of the inner chamber of the container can be separated from the atmosphere of the outer chamber of the container, and on the other hand, the antenna cover can be tightly attached to the antenna in a sealed manner, so that it is even effective. Prevent any corrosion of the antenna caused by the material located in the container.

Preferably, the anti-compression and sealing separation between the inner chamber of the container and the outer chamber of the container increases the safety of the bulk cargo or liquid, which should not be in contact with the external environment such that, for example, it is not contaminated, or Will not pollute the environment. The seal between the inner chamber of the container and the outer chamber of the container must be particularly good for containers that are subjected to pressure or vacuum, especially those in which environmentally hazardous or hazardous materials are built. However, good sealing between the interior of the container and the interior of the antenna is also beneficial here, on the one hand, to prevent any antenna corrosion, and on the other hand to provide a defined, homogeneous interface available on the inside of the antenna element. Electrical layer. The metal ring located on the antenna cover can perform these tasks in this way, and has a stabilizing effect.

In an advantageous embodiment, the filling level measuring device comprises a device flange for sealing the inner chamber of the container from the outer chamber of the container, the device flange preferably comprising a channel, the first end of which is open and the second end thereof The screw connection is closed, tightly attached to the device flange in a sealed manner, and the sealing screw connection includes an electrical path. This allows the electrical line supply line to be compressed from the outer chamber of the container to the inner chamber of the container to block the atmosphere and environment of the container. The supply line of the electric resistance heater is preferably disposed in the bore and electrically connected to the sealing screw connection or through the sealing screw connection. The sealing screw connection can also be embodied here as, for example, a plug-in connector. The heating line supply line extends outside the waveguide antenna, rather than inside, supplying the line so as not to pass the RF signal through the hollow conductor (eg, radiation and/or received microwave radiation) is compromised.

In a particular embodiment, the supply line may additionally or alternatively include a sealed passage that separates the atmosphere inside the antenna from the atmosphere surrounding the antenna. The sealing passage connected to the electric resistance heater is guided through the sealing passage in this example, and the sealing passage is preferably disposed in the metal ring, thereby realizing a mechanically stable sealing passage, so that the filling degree measuring device is more robust. Such a path for an electrical supply line is typically not required for devices that are configured to operate on the outside and operate in the W-band.

The filling level measuring device may further have a control unit for controlling the heating device, which is electrically connected to the supply line and connected to the heating device. By controlling the heating device, any overheating is prevented, the antenna cover heating is more effective, and the overall energy is lower and optimized.

In this manner, in an advantageous embodiment of the invention, the heating energy supplied to the heating means can be embodied in a time controlled manner. Whether or not power should be supplied to the heating device and its supply may be determined depending on additional parameters. The supply of energy to the heating device may be supplied, for example, depending on the temperature measured at the antenna cover, and/or depending on the humidity measured at the antenna cover, and/or depending on the components attached to the antenna cover, and/or Depending on other parameters, such as air pressure or the consistency of the atmosphere around the filling level measuring device, it is then supplied to the heating device.

To this end, a temperature sensor can be used, thermally connected to the antenna cover, and advantageously configured to the antenna cover and/or to the antenna cover. In addition, a humidity sensor can be used, which is configured in The antenna cover is preferably configured and fastened to the antenna cover. The temperature and/or humidity values periodically measured at the antenna cover, respectively, may preferably be transmitted to a control unit that, for example, determines whether the heating device is on, or determines the amount of energy supplied to the heater per unit of time.

In a specific embodiment, possible adhesion can be detected at the antenna cover, so that the reflected and measured microwave signals emitted by the filling level measuring device are more accurate in analysis, and depending on the analysis result, whether or not the heating device is turned on, and The heating energy supplied to the heating device or the electricity conducted through the heating device is determined in an advantageous manner. The measuring device can detect any sticking in this manner and turn the heater on when the threshold or characteristic of the microwave signal and/or critical progress is reached.

The filling level measuring device preferably comprises a control device that controls the time during which the energy is supplied to the heating device, which is supplied by the temperature measuring means and/or the humidity measuring means and/or the radiated and/or reflected microwave signals as a result of the measurement. And the analysis is used to control the energy to be supplied in order to control the heating device. Once the microwave signal has progressed to a predetermined threshold and/or characteristic, the heating device can supply the necessary heating energy to remove the adhesion again. This saves energy because the heating energy must be supplied to the heating device in a discontinuous manner and when needed. After the attachment and/or clogging material on the antenna cover has been removed, the heating device can be turned off.

For example, a resistance heater can be attached to the antenna cover. This represents an option to create a full range of thermal contact between the resistive heater and the antenna cover. The heating energy can be effectively transmitted through the solid body heat conductor to the antenna cover in this manner and heated. However, resistance plus The heat exchanger is preferably molded with a wire cover, which is here embodied in a cost-effective manner into a resistance wire. The electric resistance heater can also be embodied as a linearly extending powder sintered on the antenna cover or a conductor path vapor deposited on the antenna cover. In these examples, it is also possible to ensure good thermal contact between the electric resistance heater and the antenna cover. By adhering an electric resistance heater to the antenna cover (preferably on the side of the antenna cover or on one side of the liquid surface), or by molding, it is ensured that the heat conduction between the heater and the antenna cover is as good as possible, And protect the heater coil from corrosion.

The heating principle can be used flexibly in both the horn antenna and the blister of the parabolic antenna, so that the antenna is preferably a horn antenna or a parabolic antenna.

The terms used in the following description (e.g., top, bottom, left, and right, and the like) are for illustrative embodiments and are not to be considered as limiting, even if they are in a preferred embodiment. The terms microwave radiation, high frequency radiation, and radar wave radiation are equally used for electromagnetic radiation ranging from 1 GHz to 1,000 GHz.

1‧‧‧Filling degree measuring device

2‧‧‧Sensor cover

4‧‧‧ horn antenna

6‧‧‧ device flange

8‧‧‧Sensor electronic components

10‧‧‧Control unit

12‧‧‧Supply lines, heating cables

14‧‧‧ heating device

16‧‧‧Antenna cover, antenna lens

18‧‧‧Metal ring

20‧‧‧ Sealed access

22‧‧‧ Energy supply

24‧‧‧ Sealed spiral connection

26‧‧‧ Holes

28‧‧‧ plastic horn antenna

28a‧‧‧Metal coating

30‧‧‧ Template

32‧‧‧ collar flange

34a‧‧‧ longitudinal section

34b‧‧‧lateral section

36‧‧‧Microwave polarization direction

In the following description, the invention is explained in a more detailed manner based on the drawings. 1 is a cross-sectional view of a first exemplary embodiment of a filling level measuring device, FIG. 2 is a cross-sectional view of another exemplary embodiment of a filling level measuring device, and FIG. 3 is a heating device at an antenna Cover the configuration.

Figure 1 shows a filling level measuring device 1 comprising a sensor housing 2 connected to a horn antenna 4. The device flange 6 is disposed between the sensor housing 2 and the horn antenna 4 for sealing the filling level measuring device 1 to a container (not shown). The sensor housing 2 includes sensor electronics 8 and a control unit 10. The control unit 10 supplies the heating device 14 via the heating connection line 12, and the heating device 14 is disposed on the antenna cover 16, and the antenna cover 16 is fastened to the metal ring 18 to the lower portion of the horn antenna 4 or the radiation radiation portion.

The heater cable 12 is connected to the metal ring 18 through a sealing passage 20 and to the heating device 14. The heating connection line 12 is a supply line 12 that supplies control power to the resistance heating device 14 provided by the control unit 10. The control unit 10 is here supplied by the energy supply 22 using a battery or an external power source. The supply line 12 is guided, starting with the control unit 10, through the sealing screw connection 24, and into the opening of the channel 26 in the device flange 6, into the interior of the container. The sealing screw connection 24 is fastened to the device flange 6 in a pressure-tight manner. The device flange 6 can be placed in a pressure tight manner on a container (not shown) containing liquid or bulk cargo.

Fig. 2 shows another specific embodiment of the filling level measuring device 1. The control device 10 and the sensor housing 2 including the sensor electronics 8 are directly connected to the plastic horn antenna 28, which preferably displays the metal coating 28a on the inside. The supply line 12 connects the outlet of the control unit 10 to the input of the heating device 14, which is embodied as an antenna The antenna cover 16 of the lens 16 is designed as an electric resistance heater. The plastic horn antenna 28 includes a metal coating 28a that can be attached to a form 30 that is preferably made of plastic or metal. The supply line 12 is guided through a sealed passage 20 disposed in the die plate 30 and connected to a heating device 14 below the sealed passage 20. The seal passage 20 is similar to the seal screw connection portion 24 in Fig. 1 and the seal passage portion 20 in Fig. 1, and may represent, for example, a standard-PG-screw connection. The control unit 10 thermostats the antenna cover 16 to a temperature that prevents condensation on the antenna cover 16 and/or on the antenna lens 16 in a reliable manner. The antenna lens 16 is additionally formed in a conical shape so that the condensed material can be discharged downward and dripped. The template 30 shows a recess for the collar flange 32 to engage, the collar flange being pressure sealed to the container (not shown), the container holding the bulk cargo or liquid, the surface or volume of the bulk cargo or liquid must be carried out Determination.

Figure 3 shows a heating device 14 that is disposed in the antenna cover and/or antenna lens 16. The electric resistance heater 14 includes a plurality of longitudinal sections 34a arranged in parallel with one another, which are interconnected via a transverse section 34b. For example, the heating device 14 is molded into the antenna cover 16 such that heat conduction between the antenna cover 16 and the heating device 14 is good. The antenna cover or antenna lens 16 is disposed on the metal coated plastic horn antennas 28, 28a such that the direction of the polarization 36 radiated by the microwave generator (not shown) is configured to be coupled to the heating device 14. The longitudinal section 34a is vertical.

The present invention is explained in more detail based on two exemplary embodiments, but is not limited thereto. The invention has a pass in the field A person skilled in the art will recognize many variations and embodiments of the device in accordance with the present invention without departing from the concept of the invention.

1‧‧‧Filling degree measuring device

2‧‧‧Sensor cover

4‧‧‧ horn antenna

6‧‧‧ device flange

8‧‧‧Sensor electronic components

10‧‧‧Control unit

12‧‧‧Supply lines, heating cables

14‧‧‧ heating device

16‧‧‧Antenna cover, antenna lens

18‧‧‧Metal ring

20‧‧‧ Sealed access

22‧‧‧ Energy supply

24‧‧‧ Sealed spiral connection

26‧‧‧ Holes

Claims (20)

A filling level measuring device (1) comprising: a microwave transceiver; an antenna (4, 28, 28a) connected to the microwave transceiver, comprising an exit hole for a targeted emission of microwave radiation; And an antenna cover (16) disposed in the outlet hole and sealingly closing the outlet hole, wherein the filling level measuring device (1) additionally comprises a heating device (14), by which the heating device (14) can The antenna cover (16) is heated. The filling level measuring device (1) of claim 1, wherein the heating device represents a resistance heater (14) disposed on the antenna cover (16), the at least one double core for electrically connecting the resistance heater to the power source A supply line (12) is disposed on the antenna cover (16) such that it directly heats the antenna cover (16) via thermal conduction when connected to a live power source. The filling level measuring device (1) of claim 1, wherein the antenna cover (16) comprises a surface formed on the outside of the antenna in a conical manner, the surface of the antenna cover preferably being a fluid repellent. A filling level measuring device (1) according to claim 1, wherein the antenna cover represents an antenna lens (16) for assembling the microwave radiation into a bundle. A filling level measuring device (1) according to claim 2, wherein the electric resistance heater (14) is configured to be stretched at the antenna cover (16) or in the antenna cover (16). A filling degree measuring device (1) according to claim 2, wherein the electric resistance heater (14) comprises longitudinal sections (34a) arranged in parallel with each other, which are interconnected at their ends via a lateral section (34b) The longitudinal section (34a) extends linearly and has a length that is at least twice, preferably four times, the transverse section (34b). The filling level measuring device (1) of claim 6, wherein the electric resistance heater is aligned with the antenna (4, 28, 28a) such that the longitudinal section (34a) of the electric resistance heater (14) is configured to The polarization of the microwave radiation (36) is vertical. The filling level measuring device (1) of claim 1, wherein the antenna (4, 28, 28a) is made of metal coated plastic. The filling level measuring device of claim 1, wherein the antenna cover (16) is made of a non-conductive plastic, preferably made of polytetrafluoroethylene (PTFE). The filling degree measuring device (1) of claim 1, wherein the antenna cover (16) is fastened to the metal ring (18) at an end of the antenna (4, 28, 28a), preferably via a screw connection. . The filling level measuring device (1) of claim 1, wherein the filling level measuring device (1) comprises a device flange (6) for sealing the inner chamber of the container to be insulated from the outer chamber of the container, The device flange (6) comprises a channel, preferably in the form of a channel (26), the first end of which is open and the second end of which is sealed by a sealing screw (24) that is fastened to the device flange (6). ) closed in a sealed manner, which is shown as an electrical path. A filling level measuring device (1) according to any one of claims 2 to 11, wherein the supply line (12) is guided through a sealed passage (20) which surrounds the atmosphere inside the antenna with the antenna Atmospheric separation The sealing passage (20) is preferably disposed on the metal ring (18). A filling level measuring device (1) according to claim 2, wherein the supply line (12) is disposed in the tunnel (26) and is electrically connected to the sealing screw connection (24) or guided through The sealing screw connection (24). A filling level measuring device (1) according to claim 13, wherein the filling level measuring device (1) comprises a control unit (10) for controlling the heating device, which is electrically connected to the supply line (12). The filling degree measuring device (1) of claim 2, wherein the electric resistance heater (14) is molded with the antenna cover (16) or adhered to the antenna cover (16), the electric resistance heater (14) ) preferably represents a resistance wire. The filling level measuring device (1) of claim 1, wherein the antenna is a horn antenna (4, 28, 28a) or a parabolic antenna. A filling level measuring device (1) according to claim 1, wherein the metal ring (18) is part of the device flange (6) or is embodied as a block having the device flange (6). The filling degree measuring device (1) of claim 1, wherein the antenna cover (16) comprises temperature measuring means and/or humidity measuring means and/or means for detecting adhesion of the material on the antenna cover (16); and a control unit ( 10) The energy supplied to the heating device (14) is controlled using measurements provided by the temperature measuring means and/or the humidity measuring means and/or the substance adhesion detecting means. The filling level measuring device (1) of claim 1, wherein the energy supplied to the heating device is supplied to the heating device in a time-controlled manner. The filling degree measuring device (1) of claim 1, wherein the measurement of the capacity of the energy supplied to the heating device is dependent on a temperature measured at the antenna cover, and/or depending on a humidity measured at the antenna cover, and And/or depending on the components adhered to the antenna cover and/or the consistency of the atmosphere depending on the air pressure or the measuring device around the filling level.