The present application is related to and claims the priority benefit of German Patent Application No. 10 2018 107 450.6, filed on Mar. 28, 2018, and International Patent Application No. PCT/EP2019/053935, filed on Feb. 18, 2019, the entire contents of which are incorporated herein by reference.
The present invention relates to a device for determining fill level of a liquid in a pipeline and to a flowmeter having such a device.
In different fields of application of flow measurement, there exist instances, where pipelines are not completely filled. This can be the case, for instance, in water/wastewater technology. Also in these pipelines, flow velocity of the fluid can be measured with the magneto-inductive measuring principle or comparable methods. In order, however, to calculate a volume flow from a measured flow velocity, it is necessary, supplementally, to have information concerning the fill level in the pipeline. Magneto-inductive flowmeters with a monitoring electrode for monitoring a degree of filling of the pipeline are disclosed in Offenlegungsschrifts DE 10 2010 001 993 A1 and DE 10 2012 109 308 A1. With the monitoring electrodes, however, it can only be determined, whether a pipeline is essentially completely filled. A continuous, quantitative determining of the degree of filling is not possible with the monitoring electrodes.
It is, therefore, an object of the present invention to provide a remedy for this problem.
The device of the invention for measuring fill level of a liquid includes: a measuring tube for guiding the liquid, which measuring tube has a tube wall, which extends between a first tube opening at one end and a second tube opening at an opposite end and which surrounds a volume, in which the liquid is guided, wherein a tube axis extends between the first tube opening and the second tube opening; a first conductor, which extends at least sectionally around the volume, in which the liquid is guided, wherein the first conductor is electrically insulated from the volume; a second conductor, which extends at least sectionally around the volume, in which the liquid is guided, wherein the second conductor is electrically insulated from the first conductor and from the volume, wherein the first conductor extends essentially in parallel with the second conductor, wherein the first conductor and the second conductor form a waveguide for microwaves; an HF circuit for in-coupling a microwave signal into the waveguide and for receiving reflected microwave signals out-coupled from the waveguide; an operating- and evaluating circuit, which is adapted to determine fill level of liquid in the measuring tube based on received microwave signals.
In another development of the invention, the tube wall comprises a metal support body and an electrically insulating lining, wherein the support body surrounds the first conductor, and wherein the first electrical conductor is electrically insulated by the lining from the volume and from the support body.
In another development of the invention, the support body surrounds the second conductor, wherein the second electrical conductor is electrically insulated by the lining from the first conductor, from the volume and from the support body.
In another development of the invention, the second conductor comprises the support body and is especially formed by the support body.
In another development of the invention, the tube wall comprises an electrically insulating, tube wall body, wherein the waveguide surrounds the tube wall body and is electrically insulated from the volume by the tube wall body.
In another development of the invention, the first conductor and the second conductor are placed on the tube wall body.
In another development of the invention, the first conductor and the second conductor comprise metal strips, which are applied on the tube wall body.
In another development of the invention, the waveguide extends essentially perpendicularly to the tube axis.
In another development of the invention, the waveguide extends essentially helically around the volume.
In another development of the invention, the operating- and evaluating circuit is adapted to determine fill level of liquid in the measuring tube based on one or more reflected signals out-coupled from the waveguide.
In another development of the invention, the HF circuit is adapted to couple FMCW signals into the waveguide and to out-couple such from the waveguide.
The flowmeter of the invention includes a device of the invention for measuring fill level; and a measuring transducer for registering flow velocity of a liquid flowing in the measuring tube, wherein the measuring transducer is arranged in or on the measuring tube; and wherein the operating- and evaluating circuit is adapted to ascertain volume flow through the measuring tube based on flow velocity and fill level.
In another development of the invention, the measuring transducer comprises a magneto inductive measuring transducer.
In another development of the invention, the operating- and evaluating circuit is adapted to determine electric or dielectric properties of the liquid based on signals out-coupled from the waveguide, and to take into consideration such properties for determining flow velocity of the liquid.
The invention will now be explained based on the examples of embodiments illustrated in the drawing, the figures of which show as follows:
As shown in
In order to prepare the device for measurement operation, for example, the following procedure can be used:
First, an empty measurement is performed with the measuring tube 102 filled completely with air. The reflection signals arising in such case are not caused by a reflection on the fill level. The result of this empty measurement is stored in the frequency domain as s11,empty(ƒ).
Then, a full measurement is performed with the measuring tube 102 completely filled with water. The reflected signal is registered and stored as s11,full(ƒ).
After a transforming of s11(ƒ) from the frequency domain to s11(t) in the time domain by Fourier transformation, undesired reflection signals are removed by forming the complex valued difference between s11(ƒ) and s11,empty(ƒ).
Finally, the time position of the fill level dependent reflection for the maximum filled case is ascertained. In this way, the prerequisites for measuring fill level are put in place.
In measurement operation after registering the reflection s11(ƒ), firstly, undesired reflection signals are eliminated by forming the complex valued difference between s11(ƒ) and s11,empty(ƒ). Transformation of s11(ƒ) from the frequency domain to s11(t) in the time domain by Fourier transformation follows. Then, the time position of the fill level dependent reflection compared with the position of the measurement in the case of the full measurement tube 102 is ascertained, and, as a function of the time position, a fill level is calculated. This fill level can be taken into consideration for calculating a volume flow.
The measuring tube wall shown in
The measuring tube wall 110 shown in
The measuring tube wall 210 shown in
The above examples show that any conductor arrangements led around the volume of the measuring tube are suitable for guiding a microwave signal, which interacts with a medium located in the volume of the measuring tube, and therewith make the surfaces of the medium detectable based on partial reflections of the microwave signal.
As a result, the fill level in a measuring tube can be ascertained therewith, in order also to be able to calculate a correct volume flow measured value in the case of partially filled measuring tubes.
Number | Date | Country | Kind |
---|---|---|---|
10 2018 107 450.6 | Mar 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2019/053935 | 2/18/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2019/185240 | 10/3/2019 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
6198424 | Diede et al. | Mar 2001 | B1 |
6691570 | Neuhaus et al. | Feb 2004 | B1 |
7368922 | Zangl | May 2008 | B2 |
7712381 | Allenberg | May 2010 | B2 |
8266970 | Hencken | Sep 2012 | B2 |
20030019291 | Pchenikov et al. | Jan 2003 | A1 |
20070090992 | Edvardsson | Apr 2007 | A1 |
20150241260 | Voigt | Aug 2015 | A1 |
20180328769 | Hughes | Nov 2018 | A1 |
20200309580 | Godager | Oct 2020 | A1 |
20210215527 | Eriksson | Jul 2021 | A1 |
Number | Date | Country |
---|---|---|
1592845 | Mar 2005 | CN |
101929883 | Dec 2010 | CN |
202041237 | Nov 2011 | CN |
103697952 | Apr 2014 | CN |
104685323 | Jun 2015 | CN |
2526860 | Feb 1976 | DE |
102004057087 | Jan 2006 | DE |
102005044143 | Mar 2007 | DE |
102007010627 | Sep 2008 | DE |
102007061573 | Jun 2009 | DE |
102010024680 | Dec 2011 | DE |
2501165 | Oct 2013 | GB |
2007046752 | Apr 2007 | WO |
Number | Date | Country | |
---|---|---|---|
20210123786 A1 | Apr 2021 | US |