Patent Application
20210102832
The invention relates to a method for detecting a measuring error during a measurement of a media property of a medium located in a container by means of a field device in measurement and automation technology, and an ultrasonic flow meter or ultrasonic fill level measuring device used for carrying out said method.
In the technical field of measuring and automation technology, various field devices are used, by means of which at least one property of a medium can be measured. Frequently, at least one further sensor for measuring one or more other medium properties is assigned to the field device.
For example, document DE 100 57 188 A1 shows an ultrasonic flow meter comprising a temperature sensor for temperature compensation since, for example, an ultrasonic signal propagation time is dependent on the temperature of a medium flowing through a measuring tube.
However, technical devices are, in principle, prone to errors and can fail, such a failure being able to occur gradually over an extended period of time, which makes the detection of the failure significantly more difficult.
The object of the invention is therefore to propose a method and an ultrasonic flow or an ultrasonic fill level measuring device, so that a failure of a field device or of an assigned sensor can be detected.
The object is achieved by a method according to independent claim 1, and by devices according to independent claim 11.
In a method according to the invention for detecting a measuring error during a measurement of a media property of a medium located in a container by means of a field device in measurement and automation technology, at least one measurement of at least one first media property is taken by means of the field device, wherein an electronic measuring/operating circuit provides at least one measured value of the first media property,
wherein at least one second media property different from the at least one first media property is measured in each case directly by means of at least one sensor provided therefor, wherein the electronic measuring/operating circuit provides at least one sensor measured value based on a measurement signal generated by the sensor;
wherein
a known relationship between the first media property and the second media property is used to calculate the second media property from the at least one first media property by means of the electronic measuring/operating circuit, wherein the electronic measuring/operating circuit in each case provides at least one calculation value;
wherein a statement about the functional capability of the corresponding sensor or of the field device is derived by comparing the sensor measured value with the calculation value.
By taking advantage of the known relationship between at least one first media property and at least one second media property, it is thus possible to check, by means of measured medium properties and by means of the relationship of calculated medium properties, whether the field device or the assigned sensor is functioning, in the event that functioning is ensured in the assigned sensor or in the field device. A minimum deviation between measured medium properties and calculated medium properties may be interpreted as an indication of a malfunction or of a failure.
In one embodiment of the method, in the case of at least two different sensor measured values, at least one calculation value is used in each case for detecting a measuring error of the first media property or of the second media property.
This can be advantageous in the case of a non-linear relationship between the at least one first media property and the at least one second media property. For example, if the relationship is not monotonic, there may be exactly one value of a first media property in the case of different values of a second media property. Adding a measured value of a second media property provides valuable additional information, by means of which the described ambiguity can be eliminated. A plurality of first measured values can be determined for each second measured value in order to thereby reduce an uncertainty of a measurement of the corresponding first media property. The same also applies to the second media property.
In one embodiment of the method, different sensors are used for measurements of n different second medium properties, wherein the electronic measuring/operating circuit provides a group of sensor measured values,
wherein each element of the group is assigned sensor measured values of each media property to be measured,
wherein in each case at least one calculation value for at least two and, especially, at least n different elements is used for detecting a measuring error of a media property, wherein n is a natural number greater than 1.
If the known relationship encompasses at least n second medium properties and is thus multidimensional, it may be advantageous to use a plurality of measured values, especially of different second medium properties.
In one embodiment of the method, the first media property and the second media property are at least one of the following list: temperature, pressure, density, viscosity, electrical conductivity, thermal conductivity, compressibility, adiabatic coefficient, pH value.
In one embodiment of the method, the field device is a magnetically inductive flow meter and measures the electrical conductivity of the medium,
or wherein the field device is a Coriolis measuring device, especially, a Coriolis flow meter, and measures the density and, especially, the viscosity of the medium,
or wherein the field device is an ultrasonic flow meter or an ultrasonic fill level measuring device and measures the speed at which sound travels in the medium,
or wherein the field device is a thermal flow meter and measures a temperature or thermal conductivity of the medium.
In one embodiment of the method, the ultrasonic flow meter operates according to the propagation time difference principle, and wherein the container is a measuring tube through which the medium flows.
In one embodiment of the method, the medium is gaseous or liquid,
wherein the medium includes at least one of the following substances:
water, one or more hydrocarbon compounds, air.
In one embodiment of the method, a notification is output when a calculation value deviates from an associated sensor measured value by more than 20% and, especially, by more than 10% and preferably by more than 2%.
In one embodiment of the method, the sensor belonging to the sensor measured value is recalibrated based on the measured deviation.
In one embodiment of the method, the electronic measuring/operating circuit tracks the progression of a deviation between the sensor measured values and the associated calculation values and, especially, records them.
An ultrasonic flow meter or ultrasonic filling level measuring device according to the invention, used for implementing a method according to any of the preceding claims, comprises:
at least one first ultrasonic transducer for generating and detecting an ultrasonic signal;
at least one sensor for detecting a media property and/or at least one terminal for connecting a sensor for detecting a media property;
an electronic measuring/operating circuit for operating the field device.
In one embodiment, the ultrasonic fill level measuring device is attached to a container,
wherein the container is, especially, a tank.
In one embodiment, the ultrasonic flow meter comprises a container,
wherein the container is a measuring tube, which is designed to conduct the medium.
In one embodiment, the ultrasonic flow meter comprises a second ultrasonic transducer for measuring the speed at which sound travels in the medium.
The invention will now be described with reference to exemplary embodiments.
wherein, in a first method step 101, at least one measurement of at least one first media property M1 is taken by means of the field device, an electronic measuring/operating circuit providing at least one measured value MF of the first media property, wherein, in a second method step 102, at least one second media property M2, which differs from the at least one first media property, is measured in each case directly by means of a sensor provided therefor, the electronic measuring/operating circuit providing at least one sensor measured value SM based on a measurement signal generated by the sensor, wherein, in a third method step 103, a known relationship between at least one first media property and the at least one second media property is used to calculate the at least one second media property from the at least one first media property by means of the electronic measuring/operating circuit, the electronic measuring/operating circuit in each case providing at least one calculation value BW, wherein, in a fourth method step 104, a statement about the functional capability of the corresponding sensor or of the measuring device is derived by comparing the at least one sensor measured value SM with the at least one calculation value.
The relationship between the at least one first media property and the at least one second media property can be, for example, a relationship between the temperature of the medium and the speed of sound. For example, the temperature may not just be considered as being dependent on the speed of sound, but also, for example, on the density and/or the viscosity of the medium. This can be relevant, for example, in an ultrasonic flow meter or in an ultrasonic fill level measuring device comprising an additional temperature sensor.
Thus, by providing at least one calculation value BW of at least one second media property and comparing it with the corresponding sensor measured values SM of the second media property, either the measurement of the field device or the measurement of the sensor can be verified, depending on whether the field device or the sensor is recognized as being reliable. In a relationship between a first media property and a second media property, the calculation of a single calculation value may be sufficient for a verification of the field device or of the sensor. However, by means of at least one repetition of the measurement of the first media property and calculation of corresponding calculation values, a measuring accuracy can be increased, and thus the meaningfulness of a statement with respect to the reliability of the field device or of the sensor can be increased. If a lack of reliability is detected by the electronic measuring/operating circuit 77, for example, a warning can be output. As a result, a repair or a replacement of the field device or of the sensor can be prompted. When a plurality of calculation values BW are created based on different measured values of a first media property which belong to a measurement variable, the statement with respect the reliability of the field device or of the sensor can also encompass information about the form of a deviation of the field device or sensor from a target state. Having knowledge of the deviation allows, for example, for the deviation to be compensated for, which ensures that the field device or the sensor is operational until replaced or repaired. The same also applies in the case of more complex, multi-dimensional relationships between at least one first media property and at least one second media property.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 130 097.5 | Dec 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/084176 | 12/10/2018 | WO | 00 |
