DE102017130970B4 - Method for detecting a measurement error when measuring a media property of a medium by means of a field device of measurement and automation technology and an ultrasound flow meter or ultrasound level meter used to implement the method - Google Patents

Abstract

Method (100) for detecting a measurement error when measuring a media property of a medium in a container of a medium by means of a field device of measurement and automation technology, wherein in a first method step (101) at least one measurement of at least one first media property (M1) by means of the field device is carried out, an electronic measuring / operating circuit (77) each providing at least one measured value (MF) of the first media property, in a second method step (102) at least one second media property (M2) different from the at least one first media property directly by means of in each case at least of a sensor provided for this purpose, the electronic measuring / operating circuit (77) providing at least one sensor measured value (SM) on the basis of a measurement signal generated by the sensor; in a third method step (103) a known relationship (Z) between the at least one first en 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 each providing at least one calculation value (BW); in a fourth method step (104), by comparing the at least one sensor measured value with the at least one calculated value, a statement about the functionality of the corresponding sensor or the measuring device is derived, characterized in that the field device is an ultrasonic flow measuring device and measures the speed of sound of the medium, wherein the sensor measures temperature, pressure, density, thermal conductivity, compressibility or adiabatic coefficient, wherein the ultrasonic flow meter works according to the time difference principle, and wherein the container is a measuring tube through which ch measuring tube the medium flows.

Description

The invention relates to a method for detecting a measurement error in a measurement of a media property of a medium in a container of a medium by means of a field device of measurement and automation technology, and an ultrasonic flow meter or ultrasonic level measuring device used to implement the method.

A wide range of field devices are used in the technical field of measurement and automation technology, by means of which at least one property of a medium can be measured. The field device is often assigned at least one further sensor for measuring one or more other media properties.

The DE 102 40 550 A1 shows, for example, a level measuring device based on the radar principle, with a further measuring value sensor being provided for measuring a further physical quantity.

The DE 10 2012 104 042 A1 describes a method for monitoring an operating state of an ultrasonic transducer of an ultrasonic flow measuring device.

The DE 10 2007 042 043 A1 shows a device for determining and monitoring the fill level of a filling material in a container based on a transit time measurement method of emitted signals, an ultrasonic sensor and a microwave sensor being provided.

The DE 10 2015 122 292 A1 shows a field device of automation technology for determining a process variable of a liquid medium in a container with a first sensor for detecting the process variable and a second sensor for determining a distance between a sensor head and a container wall.

DE 10 2013 106 108 A1 shows a method for determining a compensated flow of a medium flowing through a pipeline.

The DE 600 30 715 T2 describes a fault diagnosis of a process device using a process-dependent sensor signal.

The US20100305882A1 describes a method and a device for monitoring a multi-phase flow of a medium.

For example, the font shows DE 100 57 188 A1 an ultrasonic flow meter, which has a temperature sensor for temperature compensation, since, for example, an ultrasonic signal transit time is dependent on the temperature of a medium flowing through a measuring tube.

However, technical devices are fundamentally faulty and can fail, whereby such a failure can creep over a longer 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 ultrasound flow or an ultrasound fill level measuring device so that a failure of a field device or an assigned sensor can be detected.

The object is achieved by a method according to independent claim 1 and by devices according to the independent claim 8.

In a method according to the invention for detecting a measurement error when measuring a media property of a medium in a container of a medium by means of a field device of measurement and automation technology, at least one measurement of at least one first media property is carried out by means of the field device, with an electronic measurement / operating circuit in each case at least provides a measurement of the first media property,
wherein at least one second media property, different from the at least one first media property, is measured directly by means of at least one sensor provided for this purpose, the electronic measuring / operating circuit providing at least one sensor measured value based on a measurement signal generated by the sensor;
in which
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, the electronic measuring / operating circuit each providing at least one calculation value;
whereby a comparison of the functionality of the corresponding sensor or the field device is derived by comparing the measured sensor value with the calculated value,
wherein the first media property and the second media property is at least one from the following list: temperature, pressure, density, viscosity, electrical conductivity, thermal conductivity, compressibility, adiabatic coefficient, pH value,
the field device measuring a magnetic-inductive flow meter and the electrical conductivity of the medium,
or wherein the field device is a Coriolis measuring device, in particular a Coriolis flow measuring device, and measures the density and in particular the viscosity of the medium,
or wherein the field device is an ultrasonic flow measuring device or an ultrasonic level measuring device and measures the speed of sound of the medium,
or wherein the field device is a thermal flow meter and measures a temperature or a thermal conductivity of the medium.
wherein the ultrasonic flow meter works on the time difference principle, and wherein the container is a measuring tube, through which measuring tube the medium flows.

By utilizing the known relationship between at least one first media property and at least one second media property, it can thus be checked by means of measured media properties and by means of the relationship of calculated media properties whether the field device or the assigned sensor works, in the event that the assigned sensor or the field device is guaranteed to function. A minimum deviation between measured media properties and calculated media properties can be interpreted as an indication of a malfunction or failure.

In one embodiment of the method, at least one calculation value with at least two different sensor measurement values is used in each case for the detection of a measurement error of the first media property or 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. If, for example, the relationship is not monotonous, then one value of a first media property can be given with different values of a second media property. The addition of a measured value of a second media property provides valuable additional information by means of which the ambiguity described can be eliminated. Several first measured values can be determined per second measured value in order to reduce an uncertainty of a measurement of the corresponding first media property. The same applies to the second media property.

In one embodiment of the method, different sensors are used for measurements n of different second media properties, the electronic measuring / operating circuit providing a group of sensor measured values,
where each element of the group is assigned sensor measured values of each media property to be measured,
wherein at least one calculation value for at least two and in particular at least n different elements is used to identify a measurement error of a media property, where n is a natural number greater than 1.

If the known relationship comprises at least n second media properties and is therefore multidimensional, it can be advantageous to use a plurality of measured values, in particular different second media properties,

• Wasser, einen oder mehrere Kohlenwasserstoffverbindungen, Luft.

In one embodiment of the method, the medium is gaseous or liquid,
where the medium contains at least one of the following substances:

• Water, one or more hydrocarbon compounds, air.

In one embodiment of the method, a message is output if a calculated value deviates from an associated sensor measured value of more than 20% and in particular more than 10% and preferably more than 2%.

In one embodiment of the method, the sensor belonging to the sensor measured value is recalibrated on the basis of the measured deviation.

In one embodiment of the method, the electronic measuring / operating circuit tracks the course of a deviation between the sensor measured values and the associated calculation values and records them in particular.

• mindestens einen ersten Ultraschallwandler zum Erzeugen und Erfassen eines Ultraschallsignals;
• mindestens einen Sensor zum Erfassen einer Medieneigenschaft und/oder mindestens einen Anschluss zum Anschließen eines Sensors zum Erfassen einer Medieneigenschaft;
• eine elektronische Mess-/Betriebsschaltung zum Betreiben des Feldgeräts.

An ultrasonic flow measuring device or ultrasonic level measuring device according to the invention used to implement a method according to one 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 connection for connecting a sensor for detecting a media property;
• an electronic measuring / operating circuit for operating the field device.

In one embodiment, the ultrasound fill level measuring device is attached to a container,
wherein the container is in particular a tank.

In one configuration, the ultrasonic flow meter has a container,
wherein the container is a measuring tube which is set up to guide the medium.

In one configuration, the ultrasonic flow measuring device has a second ultrasonic transducer for measuring the speed of sound of the medium.

The invention is described below using exemplary embodiments.

1 outlines the sequence of a method according to the invention; and 2 shows an exemplary relationship between a first media property and a second media property, by means of which relationship sensor measurement values are verified by calculation values or calculation values by sensor measurement values; and 3 shows an ultrasonic flow meter; and 4 shows an ultrasonic level meter.

1 outlines the sequence of method steps of a method according to the invention 100 to identify a measurement error when measuring a media property of a medium in a container of a medium by means of a field device of measurement and automation technology,
being in a first process step 101 by means of the field device at least one measurement of at least one first media property M1 is carried out, an electronic measuring / operating circuit each having at least one measured value MF provides the first media property, in a second method step 102 at least one second media property, different from the at least one first media property, is measured directly by means of at least one sensor provided for this purpose, the electronic measuring / operating circuit providing at least one sensor measured value on the basis of a measurement signal generated by the sensor, in a third method step 103 a known relationship between the 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 at least one calculation value BW provides, in a fourth step 104 by comparing the at least one sensor measurement SM With the at least one calculation value, a statement about the functionality of the corresponding sensor or the measuring device is derived.

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 cannot be regarded as dependent only 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 the case of an ultrasonic flow measuring device or in an ultrasonic level measuring device with an additional temperature sensor.

By providing at least one calculation value BW at least one second media property and comparison with the corresponding sensor measured values SM In 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 reliable. If there is a connection between a first media property and a second media property, the calculation of a single calculation value can be sufficient for a verification of the field device or 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 measurement accuracy can be increased and thus the meaningfulness of a statement regarding the reliability of the field device or the sensor can be increased. If a detection of a lack of reliability by the electronic measuring / operating circuit 77 for example, a warning message can be issued. As a result, a repair or an exchange of the field device or the sensor can be arranged. When creating multiple calculation values BW on the basis of different measured values of a first media property belonging to a measurement variable, the statement regarding the reliability of the field device or the sensor can also include a statement about the form of a deviation of the field device or sensor from a desired state. Knowledge of the deviation allows, for example, compensation of the deviation, which ensures that the field device or the sensor functions until it is replaced or repaired. The same applies correspondingly in the case of more complex, multidimensional relationships between at least one first media property and at least one second media property.

2 outlines an exemplary relationship between a first media property M1 and a second media feature M2 , by means of which connection sensor measured values can be verified by calculation values or calculation values by sensor measured values.

In 2 is shown a situation in which calculation values BW with uncertainties regarding the first media property and the second media property a connection Z between the first media property M1 and a second media feature M2 correspond, with sensor readings SM with uncertainties regarding the first media property and the second media property do not match the corresponding calculation values. The uncertainties are represented by area markings and the calculation values or sensor measured values by points. If several calculation values and several sensor measured values are known, it can be estimated whether there is a lack of agreement, for example due to a constant offset of the sensor measured values with regard to the media property M2 is given, or whether the offset is as in 2 shown depending on the media property M1 is. In the first case, for example, a simple compensation of the offset could be carried out. When checking the match, only an uncertainty of the calculation values or the sensor measured values with regard to the first media property or the second media property can be taken into account. The same applies in the event that measured values of the field device are verified via the calculation values by means of the sensor measured values. The same applies to more complex relationships in which the at least one first media property depends on a plurality of second media properties.

3 outlines a schematic ultrasonic flow meter 1 with a measuring tube 10 and two first ultrasonic transducers U1 and an electronic measuring / operating circuit 77 , wherein the flow measuring device can be designed as a clamp-on ultrasonic flow measuring device or as an inline ultrasonic flow measuring device and preferably works according to the transit time difference principle. The flow meter 1 also has a sensor S on and can as in 3 shown have a second ultrasonic transducer, the sensor being set up to measure a second media property. For this purpose, the electronic measuring / operating circuit is set up by means of the first ultrasonic transducer U1 and / or by means of the second ultrasonic transducer U2 to determine a first media property and to carry out the method according to the invention.

4 outlines a schematic ultrasonic level measuring device ( 2 ) with a first ultrasonic transducer for determining a fill level in a container 20 or especially in a tank 21 located medium, whereby the ultrasonic flow measuring device a sensor ( S ) to determine a second media property and an electronic measuring / operating circuit 77 which is set up to operate the first ultrasonic transducer and the sensor. For this purpose, the electronic measuring / operating circuit is set up by means of the first ultrasonic transducer U1 to determine a first media property and to carry out the method according to the invention.

LIST OF REFERENCE NUMBERS

1

Ultrasonic flowmeter

10

measuring tube

2

Ultrasonic level meter

20

container

21

tank

100

method

101

first process step

102

second process step

103

third step

104

fourth step

M1

first media property

M2

second media property

MF

Measured value provided by field device

SM

Sensor reading

BW

calculation value

Z

context

U1

first ultrasonic transducer

U2

second ultrasonic transducer

77

electronic measuring / operating circuit

S

sensor

Claims (10)

Method (100) for recognizing a measurement error when measuring a media property of a medium in a container of a medium by means of a field device of measurement and automation technology, wherein in a first method step (101) at least one measurement of at least one first media property (M1) by means of the field device is carried out, an electronic measuring / operating circuit (77) each 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) different from the at least one first media property directly by means of at least one a sensor provided for this purpose is measured, the electronic measuring / operating circuit (77) providing at least one sensor measured value (SM) on the basis of a measurement signal generated by the sensor; in a third method step (103) a known relationship (Z) between the 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 each providing at least one calculation value (BW); wherein in a fourth method step (104), by comparing the at least one sensor measured value with the at least one calculated value, a statement about the functionality of the corresponding sensor or the measuring device is derived, characterized in that the field device is an ultrasonic flow measuring device and measures the speed of sound of the medium , wherein the sensor measures temperature, pressure, density, thermal conductivity, compressibility or adiabatic coefficient, wherein the ultrasonic flow meter works according to the time difference principle, and wherein the container is a measuring tube through which the medium flows. Procedure according to Claim 1 , wherein for the detection of a measurement error of the first media property (M1) or the second media property (M2) at least one calculation value (BW) is used for at least two different sensor measurement values. Method according to one of the preceding claims, different sensors being used for measurements n of different second media properties, the electronic measuring / operating circuit (77) providing a group of sensor measured values, each element of the group being assigned sensor measured values of each media property to be measured, wherein at least one calculation value for at least two and in particular at least n different elements is used to identify a measurement error of a media property, where n is a natural number greater than 1. Method according to one of the preceding claims, the medium being gaseous or liquid, where the medium contains at least one of the following substances: Water, one or more hydrocarbon compounds, air. Method according to one of the preceding claims, wherein in the event of a deviation of a calculated value from an associated sensor measured value of greater than 20% and in particular greater than 10% and preferably greater than 2%, a message is output. Procedure according to Claim 5 , the sensor belonging to the sensor measured value being recalibrated on the basis of the measured deviation. Method according to one of the preceding claims, wherein the electronic measuring / operating circuit (77) tracks and in particular records the course of a deviation between the sensor measured values and the associated calculation values. Ultrasonic flow meter (1) used to implement a method (100) according to one of the preceding claims, comprising: at least one first ultrasound transducer (U1) for generating and detecting an ultrasound signal; at least one sensor (S) for detecting a media property and / or at least one connection for connecting a sensor for detecting a media property; an electronic measuring / operating circuit (77) for operating the field device and for determining a flow or a fill level by means of the at least one first ultrasonic transducer (U1). Ultrasonic flow meter after Claim 8 The ultrasonic flow measuring device (1) has a container, the container being a measuring tube (10) which is set up to guide the medium. Ultrasonic flow meter after Claim 9 , wherein the ultrasonic flow meter has at least one second ultrasonic transducer (U2) for measuring the speed of sound of the medium.

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