DE102012112577A1 - Device for determining and / or monitoring a process variable - Google Patents

Abstract

Device (16) for determining and / or monitoring a process variable, with at least one pipe (21) serving to carry a measuring medium, which is excited to determine the process variable to a bending vibration (S), characterized in that at least one for temperature determination Serving reference element (RE) is provided, which undergoes a phase change at at least one predetermined temperature, which reference element (RE) is operatively connected to the pipeline in such a way that damping of the vibration (S) of the pipeline (21) as a function of the present phase of the reference element (RE) takes place.

Description

The invention relates to a device for determining and / or monitoring a process variable with at least one pipeline serving to guide a medium, which is excited to determine the process variable to a bending vibration.

Such bending vibrators are used for example for mass flow measurement of a medium through a pipeline. Such a mass flow meter is for example in the European patent application EP 1154243 A1 described. With such Coriolis transducers whose measuring tubes are known to be vibrated with or without superimposed torsional vibration, not only the instantaneous mass flow of a medium, which is currently flowing through a pipe can be measured, but it can also the density of the medium due to the instantaneous oscillation frequency Measuring tubes and the viscosity of the medium to be measured due to the power required to maintain vibration. Since the temperature of the medium during operation is not constant and its density is known to be temperature-dependent, such a sensor is usually also provided with at least one temperature sensor for measuring the temperature of the fluid.

Furthermore, such devices have become known, such as for determining the level in a container, in which a vibrating probe is excited to bending vibrations. Such devices are for example from the published patent applications EP 0985916 A1 and DE 10 203 461 A1 known. In addition, from the German patent application DE 10 2011 089 010 Such a device with self-monitoring properties or for determining a predetermined temperature has become known.

Based on this, it is an object of the present invention to enable the self-monitoring or temperature determination of a device according to the preamble of claim 1.

The object is achieved by a device for determining and / or monitoring a process variable, wherein the device has at least one serving for guiding a medium pipeline, which is excited to determine the process variable to at least one bending vibration, at least one of the temperature determination serving reference element provided is that undergoes a phase transformation at least one predetermined temperature, wherein the reference element is operatively connected to the pipeline such that a damping of the vibration of the pipeline takes place in dependence on the present phase of the reference element.

It is thus an idea of the present invention to use a reference element and operatively connect to the pipeline, for example, to attach to the pipeline or to design the pipeline to include a reference element. The reference element is preferably configured or consists of such a material that it undergoes at least one phase transformation in the range of the predetermined temperature. It is also an idea of the present invention to utilize the effect of this phase transformation on the vibration of the pipeline in order to determine the achievement of the predetermined temperature or the predetermined temperature range. The reference element may be designed or connected to the pipeline such that reaching the phase transformation point or passing through the phase transformation point of the reference element is reflected in a damping of the vibration of the pipeline or in a change in the resonance frequency of the pipeline.

In one embodiment of the device, the device is a device for mass flow measurement according to the Coriolis principle. Such measuring devices are for example from the prior art, in particular the European patent application EP 1154243 A1 known.

In a further embodiment of the device, the reference element has a reference substance, which reference substance has at least one, preferably repeatedly, entering phase transition temperature. As a reference substance is, for example, a material in question, which consists at least partially or completely of a salt or a salt-containing mixture. Furthermore, the reference substance may also be a material that comprises a eutectic or consists of a eutectic.

In a further embodiment of the device, the reference element has a compartment in which the reference substance is enclosed. Such a compartment or a reference element with such a compartment may for example be part of the pipeline or attached to the pipeline later.

In a further embodiment of the device, the damping of the oscillation of the Piping of the phase of the reference substance or the phase mixture of the reference substance or the temperature of the medium from. For example, it can be concluded from the measured attenuation of the pipeline to the present phase of the reference substance or to the temperature of the medium.

In a further embodiment of the device, the reference element is in thermal contact with the medium. For example, the reference element via the pipe or the wall of the pipeline or via corresponding guide elements, which serve for the thermal coupling of the reference element with the medium to be connected.

In a further embodiment of the device, the reference element is attached to the pipeline or component of the pipeline or mechanically coupled to the pipeline. In this way, it can be achieved that a phase transition, also referred to as phase transformation, of the reference element or the reference substance has an effect on the bending vibration of the pipeline.

In a further embodiment of the device, the compartment is completely or at least partially filled with the reference substance.

In a further embodiment of the device, the reference substance is a phase transformation of a solid phase into a fluid phase or of a fluid phase into a solid phase. This phase transformation can occur, for example, when the phase transition temperature is reached.

In a further embodiment of the device, a temperature, preferably the temperature of the medium, is determined by means of the change in the dependency of the present phase on existing damping of the bending vibration of the pipeline. For this purpose, for example, an evaluation unit can be provided, which is part of the device. Furthermore, this can be used to determine, for example, the passage through a temperature of the medium. By way of example, it is thereby also possible to determine the passage through specific process steps. Such process steps include, for example, the so-called SIP (Steam In Place) and CIP (Clean In Place) are achieved at the usual temperature of about 100 ° C.

In a further embodiment of the device, a reference value for validating, calibrating and / or adjusting a temperature sensor is determined by means of the changes in the damping of the bending vibration which is present as a function of the instantaneous phase. For this purpose, an evaluation unit may also be part of the device. The reference value can then be sent to calibrate a thermally coupled to the pipe temperature sensor.

In a further embodiment of the device, the excitation of the pipeline to bending vibration (s) and the detection of the bending vibration (s) by means of at least one electromagnetic excitation or detection device takes place. Such excitation or detection devices are used to detect the mechanical bending vibration and are also for example also from the EP 1154243 A1 known.

In a further embodiment of the device, the device has a first and a second pipeline, wherein the first and / or the second pipeline have at least one reference element.

In a further embodiment of the device, the reference element is adapted to the pipeline and is preferably attached to the location of the largest bending vibration amplitude of the pipeline on the pipeline. Further, the reference element and the tubing may be configured such that the reference element couples with a portion of the tubing located at the location of the largest flexural vibration amplitude of the tubing.

In a further embodiment of the device, the reference element on the measuring tube side has a higher thermal conductivity than the side of the reference element facing away from the measuring tube. For this purpose, corresponding guide elements or insulation elements may be provided on the reference element.

In a further embodiment of the device, the reference element is thermally substantially insulated on the ambient side.

The object is further achieved by a device for determining and / or monitoring a process variable of at least one serving for guiding a medium pipeline, which is excited to determine the process variable to a bending vibration, at least one temperature determination serving reference element is provided that at least undergoes a predetermined temperature of a phase transformation, wherein the reference element is connected to the pipeline such that a change in the Resonance frequency of the pipe of the dependence of the present phase of the reference element takes place.

In one embodiment of this device, at least a portion of the pipeline serves as a reference element. This section preferably consists of a material which undergoes a phase transformation at a predetermined temperature. Furthermore, this section may comprise a material, that is, for example, consist only partially of a material which undergoes a phase transformation at a predetermined temperature. For example, the pipeline can be constructed in layers, wherein a layer consists of the reference element or the reference substance.

The aforementioned embodiments thus relate to a device which, in addition to the primary measured variable, has a temperature monitoring device with a described reference element. Such devices may preferably be used in process automation technology. A serving as a reference element compartment may for example consist of an inert temperature-resistant material. For example, a reference substance enclosed in a reference element, which has at least one reproducible phase transition at at least one phase transition temperature, can be operatively connected to the pipeline in such a way that temperature-dependent attenuation of the vibration of the pipeline occurs at different temperatures, in particular at temperatures above or below the phase transition temperature. The proposed device may for example consist of one, two or more pipes that are excited to bending vibrations.

A pipeline may, for example, comprise one, two or more reference elements. These reference elements may for example be adapted to the cylindrical diameter of the pipeline and preferably be arranged at the locations of the greatest vibration deflection of the pipeline.

According to the present invention, it is possible to provide in-situ monitoring of a temperature measurement by means of a device comprising a reference element according to one of the previous embodiments. The device is particularly preferably a Coriolis mass flowmeter. In this case, the excitation and detection device already present in the Coriolis mass flow meter can be used for the detection of measured values for the detection of the damping or the changed resonance frequency of the pipeline.

The object can be achieved according to the invention by a method in which by means of an evaluation unit, the attenuation of the bending vibration of the pipeline is monitored, and is used for temperature determination. For example, a special operating mode of the device may be provided for this purpose. Thus, for example, in a first operating mode, the process variable can be determined while in a second operating mode by means of the reference element, a temperature or a temperature value is preferably determined based on the present damping of the vibration of the pipe.

The damping can be determined, for example, by stimulating the pipeline to vibrate and then determining the decay behavior of the vibration. Instead of the damping can also be used depending on the present phase of the reference element changing resonant frequency of the pipe to determine the temperature. Bending vibration here means an elastic oscillation of the measuring tube. This type of vibration is also called transversal vibration. These are vibrations that take place essentially perpendicular to the longitudinal axis of the pipeline.

The invention will be explained in more detail with reference to the following drawings.

It shows:

1 : a schematic representation of a bending tube transducer as used for example for mass flow measurement,

2 FIG. 2: a cross section through a reference element arranged around a pipeline for determining the temperature, FIG.

3 FIG. 2 shows a cross section through a further embodiment of a reference element arranged around a pipeline for temperature determination, FIG.

4 : a bending tube transducer with two measuring tubes on each of which a reference element is provided.

1 shows a bender ear vibrator 16 , which comprises a measuring tube, which is connected on the input side or output side via a port A1 or A2 to a pipeline. To record the flow, the pipe serving as the measuring pipe is used 21 via an exciter device, not shown, to vibrate more precisely to bending oscillations stimulated. Amplitude, frequency and phase of the pipeline excited to the bending vibration 21 can then be used to determine the flow of the fluid through the pipeline 21 be determined on the basis of these sizes or at least one of these sizes.

2 shows a cross section through an embodiment of a reference element RE. This in 2 shown reference element RE has two compartments 5 on, some with a reference substance 6 are filled. These compartments 5 are on opposite sides of the pipeline 21 arranged. To the pipeline 21 and the compartments 5 is a thermal insulation 18 intended. The bending vibration S of the pipeline 21 is illustrated by the arrows marked with reference symbol S.

In 2 is the reference substance 6 in a liquid or solid phase. This phase state of the reference substance 6 causes a characteristic damping of the bending vibration of the pipeline 21 , For example, the temperature of the medium increases above the temperature of a phase transition of the reference substance 6 so goes the reference substance 6 for example, in a gaseous phase over. This gaseous phase also causes a characteristic damping of the bending vibration S of the pipeline 21 , In this case, the attenuation of the pipeline differs depending on the present phase of the reference substance 6 , For example, depending on the phase of the reference substance 6 a different damping factor.

The reference element RE can, for example, directly with the pipeline serving as a measuring tube 21 be connected. In particular, the compartments can 5 directly on the pipeline 21 to be appropriate.

3 shows a cross section through a further embodiment of a reference element RE according to the proposed invention. As well as in 2 is also according to the embodiment in 3 a first compartment 5 on a second compartment 5 attached to the opposite side of the pipeline. To improve the thermal coupling to the medium in the pipeline, see 3 also a thermal insulation 18 intended. The compartments 5 in 3 however are in contrast to the compartments 5 in 2 completely with the reference substance 6 filled. Further, the compartments have 5 according to 3 lamellar inserts to improve the thermal couplings of the compartments 5 or the reference substance 6 in it with the pipeline 21 flowing medium on.

4 shows a further embodiment of a Biegerohrschwingers 16 in which, however, two pipes L1, L2 are provided. These two pipes L1, L2 are connected on the input side as well as on the output side via connections A1 and A2, respectively, to an adjoining pipe, not shown. Both the first pipe L1 and the second pipe L2 have a reference element RE1 or RE2. The vibration of the pipelines takes place substantially perpendicular to the plane of the drawing surface. Due to the changing characteristic properties of the bending vibration S of the two pipes L1, L2 as a function of the present phase of the respective reference substance 6 can thus be closed to the temperature, for example, in the medium, which is located in the pipeline.

In addition to the in 1 and 4 shown curved pipes are also straight pipes possible.

The known from the prior art one or two or multi-tube bending vibrator 16 may comprise known from the prior art electromagnetic excitation and / or detection device.

In the 2 . 3 or 4 shown arrangement of the reference elements RE, RE1, RE2 takes place at the locations of the largest vibration deflection of the vibrator.

Instead of one with a reference substance 6 filled compartment 5 can also be provided, the measuring tube at least partially from a corresponding reference substance 6 to manufacture. For example, it is possible to exploit martensitic or austenitic phase transitions. Furthermore, such phase transitions can also affect the rigidity of the pipe or the pipe 21 impact. The stated stiffness can be, for example, the bending stiffness, ie the product of the modulus of elasticity and the area moment of inertia of the pipeline. Furthermore, several reference elements RE and / or compartments 5 with different reference substances 6 having different phase transition temperatures can be shipped. Thus, the reference substance 5 adapted to the respective process.

LIST OF REFERENCE NUMBERS

5

 compartment

6

 reference substance

16

 Bending tube oscillators

18

 Thermal insulation

21

 pipeline

25

 lamellar insert

A1

 Pipe connection

A2

 Pipe connection

S

 bending vibration

RE

 reference element

L1

 First pipeline

L2

 Second pipeline

RE1

 first reference element

RE2

 Second reference element

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1154243 A1 [0002, 0007, 0017]
• EP 0985916 A1 [0003]
• DE 10203461 A1 [0003]
• DE 102011089010 [0003]

Claims (18)

Contraption ( 16 ) for determining and / or monitoring a process variable, with at least one pipeline ( 21 ), which is excited to determine the process variable to a bending vibration (S), characterized in that at least one of the temperature determination serving reference element (RE) is provided which undergoes a phase transformation at least one predetermined temperature, which reference element (RE) such is operatively connected to the pipe, that damping the vibration (S) of the pipeline ( 21 ) takes place as a function of the present phase of the reference element (RE). Contraption ( 16 ) according to one of the preceding claims, wherein the device ( 16 ) around a device ( 16 ) for mass flow measurement acc. the so-called Coriolis principle. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) is a reference substance ( 6 ) having at least one, preferably repeatedly entering, phase transition temperature. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) is a compartment ( 5 ), in which the reference substance ( 6 ) is included. Device according to one of the preceding claims, wherein the damping of the vibration (S) of the pipeline ( 21 ) of the phase of the reference substance ( 6 ) or the phase mixture of the reference substance ( 6 ) or the temperature of the medium depends. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) is in thermal contact with the medium. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) on the pipeline ( 21 ), part of the pipeline ( 21 ), or mechanically with the pipeline ( 21 ) couples. Contraption ( 16 ) according to any one of the preceding claims, wherein the compartment ( 5 ) completely or at least partially with the reference substance ( 6 ) is filled. Contraption ( 16 ) according to one of the preceding claims, wherein the reference substance ( 6 ) experiences a phase transformation from a solid phase to a fluid phase or from a fluid phase to a solid phase. Contraption ( 16 ) according to one of the preceding claims, wherein a temperature, preferably the temperature of the medium is determined by means of the change in the existing depending on the existing phase damping of the bending vibration (S) of the pipeline. Contraption ( 16 ) according to one of the preceding claims, wherein a reference value for validating, calibrating or adjusting a temperature sensor is determined by means of the change in the damping of the bending oscillation (S) present as a function of the instantaneous phase. Contraption ( 16 ) according to one of the preceding claims, wherein the excitation of the pipeline to bending vibrations and the detection of the bending vibration by means of electromagnetic excitation or detection means takes place. Contraption ( 16 ) according to one of the preceding claims, wherein the device has a first and a second pipe (L1, L2) and the first pipe (L1) and / or the second pipe (L2) has at least one reference element (RE1, RE2). Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) to the pipeline ( 21 ) and preferably at the location of the largest bending vibration amplitude of the pipeline ( 21 ) on the pipeline ( 21 ) is attached. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) has a higher thermal conductivity on the measuring tube side, a side facing away from the measuring tube side. Contraption ( 16 ) according to one of the preceding claims, wherein the reference element (RE) is substantially thermally insulated from the environment side. Device for determining and / or monitoring a process variable, with at least one pipe serving for guiding a medium, which is excited to determine the process variable to a bending vibration, characterized in that at least one of the temperature determination serving reference element is provided which at least one predetermined temperature undergoes a phase transformation, which reference element is operatively connected to the pipeline such that a change in the Resonance frequency of the pipe in response to the present phase of the reference element takes place. Contraption ( 16 ) according to the preceding claim, wherein at least a portion of the pipeline ( 21 ) serves as a reference element (RE), and the pipeline ( 21 ) preferably consists of a material which undergoes a phase transformation at a predetermined temperature.

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