DE102020121677A1 - Flow measurement arrangement - Google Patents

Abstract

The invention relates to a flow measuring arrangement (1) for measuring a flow of a flowing medium, comprising: a Coriolis measuring device (10) set up for measuring a density of the medium; an effective pressure measuring device (20) including a measuring tube (21) with an effective pressure transmitter (22) with a flow cross-section constriction (22.1) set up for measuring a first pressure drop in the medium; and at least two pressure sensors (23.1) and/or a differential pressure sensor (23.2) and an electronic measuring/operating circuit (24) for operating the pressure sensors and for outputting differential pressure readings of the first pressure drop;wherein the Coriolis meter and the differential pressure meter are integrated into the pipeline, the differential pressure meter being located downstream of the Coriolis meter,wherein electronic measurement/operation circuitry (14, 24, 34) is provided which is set up to calculate a mass from the measured density and the measured first pressure drop to determine the flow of the medium through the pipeline, characterized in that the Coriolis measuring device is set up to include the presence of the gaseous medium component in a calculation of measured density values when a gaseous medium component is detected.

Description

The invention relates to a flow measuring arrangement for measuring a flow of a medium flowing through a pipeline with at least two medium components of different states of aggregation, comprising a Coriolis measuring device and a differential pressure measuring device.

Flow measurement arrangements with a Coriolis meter and a differential pressure meter are already known, as from W02012129603A2 emerges. However, a variety of interferences in such a measuring arrangement can lead to inaccurate measured values of the flow.

It is therefore the object of the invention to propose a robust flow measuring arrangement with a Coriolis measuring device and an effective pressure measuring device.

The object is solved by a flow meter arrangement according to independent claim 1.

• Ein Coriolis-Messgerät eingerichtet zur Messung einer Dichte des Mediums, umfassend zumindest ein Messrohr, mindestens einen Schwingungserreger zum Anregen von Messrohrschwingungen, mindestens zwei Schwingungssensoren zum Erfassen der Messrohrschwingungen, und eine elektronische Mess-/Betriebsschaltung zum Betreiben des Schwingungserregers sowie zum Aufnehmen von Messsignalen der Schwingungssensoren und zum Ausgeben von Dichtemesswerten des Mediums;

A flow measuring arrangement according to the invention for measuring a flow of a medium flowing through a pipeline with at least two medium components of different states of aggregation comprises:

• A Coriolis measuring device set up to measure a density of the medium, comprising at least one measuring tube, at least one vibration exciter for exciting measuring tube vibrations, at least two vibration sensors for detecting the measuring tube vibrations, and an electronic measuring/operating circuit for operating the vibration exciter and for recording measurement signals from the vibration sensors and for outputting density readings of the medium;

A differential pressure measuring device set up to measure a mass flow rate or a flow rate of the medium, comprising a measuring tube with a differential pressure transmitter with a flow cross-section constriction set up to measure a first pressure drop in the medium, which first pressure drop is caused by the differential pressure transmitter, and at least two pressure sensors and/or a differential pressure sensor and electronic measurement/operation circuitry for operating the pressure sensors and for outputting differential pressure readings of the first pressure drop;
wherein the Coriolis measuring device and the effective pressure measuring device are integrated into the pipeline, wherein the effective pressure measuring device is arranged downstream of the Coriolis measuring device,
wherein an electronic measuring/operating circuit is provided, which is set up to determine a mass flow rate, a volume flow rate or a flow rate of the medium through the pipeline from the measured density and from the measured first pressure drop,
characterized in that
the Coriolis meter is placed in a vertical or horizontal section of the pipeline, wherein the differential pressure meter is placed in a horizontal section of the pipeline.

In this way, a very similar hydrostatic pressure can be ensured between the Coriolis meter and the differential pressure meter since there is no hydrostatic pressure in a horizontal line. In addition, in this case no hydrostatic pressure difference between media pressure pick-up points falsifies a differential pressure measurement. An arrangement of the Coriolis measuring device in a vertical section of the pipeline is particularly preferred, since in this way there is less segregation of the medium.

A mass flow or a flow rate or volume flow of the medium through the pipeline can be determined from the first pressure drop measured with the differential pressure measuring device and the density of the medium determined with the Coriolis measuring device.

In one embodiment, the Coriolis measuring device is set up to include the presence of the gaseous medium component in a calculation of measured density values when a gaseous medium component is detected.

The presence of gas bubbles in the medium can greatly falsify a density measurement using a Coriolis measuring device, even with a very small proportion of a total volume, since these gas bubbles in the medium react to measuring tube vibrations. Correcting for this influence can therefore greatly improve a measurement of the density of the medium.

The gas bubbles in the medium move in the measuring tube of the Coriolis measuring device, depending on the gas bubble diameter, among other things, perpendicular to an inner wall of the measuring tube in a direction parallel to the measuring tube movement and thus influence measured values with regard to density and viscosity. By using a mathematical-physical model, for example, this relative movement can be taken into account and the disruptive influence of the gas bubbles can thus be corrected. The person skilled in the art can find more about the model, for example, in H. Zhu, Application of Coriolis Mass Flowmeters in Bubbly and Particulate Two-Phase Flows, Shaker, ISBN 978-3-8322-8216-5, 2009.

• Eine Blende, eine Venturidüse, eine Messrohrverjüngung.

In one embodiment, the narrowing of the flow cross section is brought about by one of the following elements:

• An orifice, a Venturi nozzle, a measuring tube taper.

In one embodiment, the flow rate measuring arrangement has a mixing device between the Coriolis measuring device and the differential pressure measuring device, which is set up to mix the media components.

In this way, it can be ensured that different media components are sufficiently evenly distributed spatially and that an effective pressure measurement therefore supplies measured values that are at most slightly falsified.

In one embodiment, the mixing device is a T-piece, a pipe bend, or a flow resistance element arranged in a pipe bend.

In one embodiment, a distance between a media outlet of the mixing device and the narrowing of the flow cross section of the differential pressure measuring device is at most 10 internal diameters of the pipeline and at least 5 internal diameters of the pipeline.

In this way it can be avoided that the spatial uniform distribution is canceled.

In one embodiment, the pipeline has an inner diameter and a center line
wherein the Coriolis measuring device has a media inlet and a media outlet,
where a distance between media outlet and flow cross-section constriction flow cross-section constriction of the differential pressure measuring device is at most 10 internal diameters and at least 5 internal diameters.

In this way it can be ensured that media properties are the same or at least similar in the Coriolis measuring device and in the differential pressure measuring device. For example, with regard to hydrostatic pressure, physical proximity between the Coriolis measuring device and the effective pressure measuring device can be important.

In one embodiment, the electronic measuring/operating circuit of the Coriolis measuring device or the differential pressure measuring device, or the electronic measuring/operating circuit is part of a separate evaluation point.

In one embodiment, the measuring arrangement has, in addition to the differential pressure sensor, a pressure sensor which is set up to measure the media pressure upstream of the narrowing of the flow cross section.

In one embodiment, the pressure sensor is part of the differential pressure measuring device, with the pressure sensor being connected to a measuring input of the differential pressure measuring device.

The pressure sensor can, for example, be connected to a pressure line of the differential pressure measuring device or have its own pressure line to the pipeline. Other configurations are also conceivable. The pressure sensor can transmit its own measured pressure values to the differential pressure measuring device via the measuring input.

In one embodiment, a water content measuring device is provided for measuring a water content of the medium.

Thus, separate flow measurement values for water and other media components can be determined.

In one embodiment, the Coriolis measuring device is set up to store measured values of the density of the medium if there is no gaseous medium component, and to use the stored measured values to determine a ratio of the gaseous medium component to the remaining medium component if a gaseous medium component is present.

In one configuration, a differential pressure measuring device is provided, which is set up to determine a second pressure drop along the Coriolis measuring device,
wherein the electronic measuring/operating circuit is set up to determine a viscosity of the medium by means of the second pressure drop when a gaseous medium compartment is present.

In one embodiment, the at least one measuring tube is bent at least in sections, and/or the Coriolis measuring device has a number of measuring tubes.

This results in a mixing effect of the medium, so that the mixing device is assisted or no longer necessary.

• 1 skizziert schematisch eine beispielhafte erfindungsgemäße Durchfluss-Messanordnung;
• 2 skizziert ein beispielhaftes Coriolis-Messgerät;
• 3 a) bis c) skizzieren beispielhafte Messrohre eines Wirkdruckmessgeräts mit Wirkdruckgeber;
• 4 a) bis c) skizzieren beispielhafte Umsetzungen einer Mischvorrichtung.

The invention is described below using exemplary embodiments.

• 1 schematically outlines an exemplary flow measurement arrangement according to the invention;
• 2 outlines an example Coriolis meter;
• 3 a) until c ) outline exemplary measuring tubes of a differential pressure measuring device with differential pressure transducer;
• 4 a) until c ) outline exemplary implementations of a mixing device.

1 1 shows an exemplary flow rate measuring arrangement 1 with a Coriolis measuring device 10 and a differential pressure measuring device 20, the differential pressure measuring device being arranged in a pipeline 60 downstream of the Coriolis measuring device. The Coriolis measuring device is set up to record a density of the medium flowing through the pipeline. The differential pressure measuring device is set up for this purpose by means of a differential pressure transmitter 22 in the form of a flow cross-section constriction 22.1, see also 3 to cause and measure a first pressure drop in the flowing medium and to calculate a flow rate from this first pressure drop. The differential pressure sensor is part of a measuring tube 21 of the differential pressure measuring device. Due to the fact that the differential pressure measuring device is arranged downstream of the Coriolis measuring device, the differential pressure measuring device experiences a medium with an approximately uniform spatial distribution of these media components in the case of media with at least two immiscible media components, since Coriolis measuring devices at a flow outlet contribute to such a uniform distribution if at least one measuring tube of the Coriolis measuring device is designed at least in sections arcuately or the medium is distributed over several measuring tubes of the Coriolis measuring device. A differential pressure caused by the narrowing of the flow cross section can thus be determined with sufficient accuracy.

A mass flow or a flow rate of the medium through the pipeline can be determined from the first pressure drop measured with the differential pressure measuring device or the flow rate derived therefrom in a flow cross section and the density of the medium determined with the Coriolis measuring device.

The measuring arrangement is set up to determine a mass flow rate of a medium with a number of medium components, with the pressure drop recorded by the differential pressure measuring device and the density of the medium recorded by the Coriolis measuring device being used. For example, when determining the density of the medium, the presence of gas bubbles in the medium can be checked and, if they are present, an interference effect of the gas bubbles on a density measurement can be corrected. The check is based, among other things, on the measurement of a viscosity of the medium, which measurement is strongly influenced by gas bubbles.

The presence of small gas bubbles in the medium, even with a very small proportion of a total volume, can greatly falsify a density measurement using a Coriolis measuring device, since these gas bubbles in the medium react to measuring tube vibrations. Correcting for this influence can therefore greatly improve a measurement of the density of the medium. The gas bubbles in the medium move in the measuring tube of the Coriolis measuring device, depending on the gas bubble diameter, among other things, perpendicular to an inner wall of the measuring tube in a direction parallel to the measuring tube movement and thus influence measured values with regard to density and viscosity. By using a mathematical-physical model, for example, this relative movement can be taken into account and the disruptive influence of the gas bubbles on a density measurement can thus be corrected. The basis for the correction is the measured viscosity of the medium. The person skilled in the art can find more information on this, for example, in H. Zhu, Application of Coriolis Mass Flowmeters in Bubbly and Particulate Two-Phase Flows, Shaker, ISBN 978-3-8322-8216-5, 2009.

To measure the pressure drop, a medium pressure upstream of the flow cross-section constriction and a medium pressure in the area of the flow cross-section constriction or downstream of the flow cross-section constriction are recorded. As shown here, this can be carried out using a differential pressure sensor 23.2 or using two pressure sensors. In the case of a differential pressure sensor, two pressure lines 23.3 are brought together, for example in a pressure chamber, with the medium remaining separated in the region of the meeting, for example by means of a membrane. A deflection of the membrane is used as a measure of a pressure difference. This is significantly more accurate than determining the differential pressure using two individual pressure measurements. As shown here, the differential pressure measuring device usually provides an electronic measuring/operating circuit 24 which is set up to operate the differential pressure sensor or the pressure sensors and to provide differential pressure measurement values. In addition to the differential pressure sensor, the differential pressure measuring device can have a pressure sensor 70 which is set up to detect an absolute pressure of the medium upstream of the narrowing of the flow cross section, this detecting, for example, the medium pressure in one of the pressure lines 23.3. The pressure lines can have a significantly smaller cross-section than the pipeline and thus act as a low-pass filter, which can be advantageous for a signal-to-noise ratio of a pressure measurement.

As shown here, according to the invention, the Coriolis measuring device is in a vertical or in a horizontal pipe section 61, and the differential pressure measuring device according to the invention can be arranged in a horizontal pipe section 62. In this way, a very similar hydrostatic pressure can be ensured for the Coriolis meter and the differential pressure meter. In addition, in this case no hydrostatic pressure difference between media pressure pick-up points of a differential pressure measurement is falsified. An arrangement of the Coriolis measuring device in a vertical section of the pipeline is particularly preferred, since in this way there is less segregation of the medium.

In addition, as shown here, the flow measuring arrangement can have a differential pressure measuring device 80 which is set up to determine a second pressure drop of the medium along the Coriolis measuring device. The differential pressure measuring device uses two pressure lines 81 to pick up a media pressure in front of and a media pressure behind the Coriolis measuring device. An electronic measuring/operating circuit 84 is configured to operate the differential pressure gauge and to output differential pressure readings or readings of the second pressure drop. An electronic measuring/operating circuit 14 of the Coriolis measuring device is set up to determine a viscosity of the medium using measured values of the second pressure drop when a gaseous medium compartment is present. What was said above applies to the functioning of a differential pressure or pressure drop determination.

At low Reynolds numbers, for example below 5000, the measuring accuracy of the differential pressure transmitter can be improved by means of the viscosity determined via the second pressure drop. A calibration factor, which describes a relationship between the pressure drop and the measured flow value of the differential pressure transducer, is practically constant at high Reynolds numbers over a wide Reynolds number range, but is subject to changes that cannot be ignored at low Reynolds numbers. With sufficiently high Reynolds numbers, the calibration factor can be calculated according to the standards ISO 5167-1:2003, ISO 5167-2:2003, ISO 5167-3:2003, ISO 5167-4:2003, ISO 5167-5:2015, ISO 5167-6 :2019 are calculated.

In addition, the flow rate measuring arrangement can have a water content measuring device 90 as shown here. In the case of a medium that consists largely of an oil-water mixture, mass flow rates for oil and water can be specified separately if the water content is known. The water content measuring device can use one of the following measured variables, for example: speed of sound of the medium, transparency with regard to electromagnetic radiation such as microwave radiation or THz radiation or infrared radiation or optical radiation or gamma radiation.

The mass flow of the medium through the pipeline can be determined, as shown here, by means of a separate evaluation point 30 with an electronic operating circuit 34 . For this purpose, measured values of the individual measuring devices are transmitted to the evaluation center. This can be done wirelessly or, as indicated here with the Coriolis measuring device and the differential pressure measuring device, by means of electrically conductive connections. Alternatively, however, the measured values can also be fed to an electronic measuring/operating circuit (14, 24, 84) of one of the measuring devices. What has just been said applies accordingly to the transmission of measured values.

In one embodiment, the flow rate measuring arrangement has a mixing device 40 between the Coriolis measuring device and the differential pressure measuring device, which is set up to mix the media components or to swirl the medium, so that different media components that are difficult or impossible to mix are spatially evenly distributed to a good approximation are. In this way, it can be ensured that an effective pressure measurement delivers measured values that are at most slightly falsified.

2 outlines an exemplary Coriolis measuring device as can be used in a flow measuring arrangement according to the invention. The Coriolis measuring device 10 has a measuring sensor with two measuring tubes 11 each with an inlet and an outlet, which measuring tubes are held by a carrier body 16 . The measuring tubes are set up to oscillate against each other. The number of measuring tubes shown here is an example; the sensor can, for example, also have only one measuring tube or four measuring tubes, which are arranged in particular in two pairs of measuring tubes, with the measuring tubes of a pair being set up to oscillate against one another. The measuring sensor has an exciter 12 which is set up to excite the measuring tubes to oscillate. The measuring pickup has two sensors 13 which are set up to detect the measuring tube vibrations. A medium flowing through the measuring tubes influences the measuring tube vibrations in a characteristic manner, so that a mass flow rate and/or a density of the medium and/or a viscosity of the medium can be derived from the measurement signals of the sensors. The measuring/operating electronic circuit 14 is housed in a housing 15 for housing the measuring/operating electronic circuit.

3 a) outlines a measuring tube 21 of a differential pressure measuring device with an exemplary differential pressure transmitter 22, which is designed as an orifice plate 22.11 and thereby causes a flow cross-section narrowing 22.1. Alternatively, as in 3 b) shown, the flow cross-section constriction can also be formed by a measuring tube narrowing extending in the direction of flow.

Alternatively, as in 3 c) Also shown is a Venturi nozzle 22.12 used as an effective pressure transducer 22 in the pipeline, which causes the flow cross-section narrowing. Pressure lines 23.3 can have a media pressure as in 3 a) shown in front of and behind the flow cross-section constriction, or as in 3 b) and c ) in front of and in an area of the flow cross-section constriction.

4 a until c ) outline exemplary mixing devices according to the invention, which are designed to swirl the medium before it enters the differential pressure measuring device, so that in the case of several immiscible medium components, there is approximately a uniform spatial distribution of the components. The mixing devices are arranged between the Coriolis measuring device and the differential pressure measuring device.

Under suitable conditions, this can already be effected by a pipeline bend 42, as is shown in 4 a) is sketched.

Suitable conditions exist, for example, when the medium is sufficiently viscous so that no significant segregation takes place up to the differential pressure measuring device.

For example, as in 4 b) outlines a flow resistance element 43 can be arranged in a pipeline section such as a pipeline bend.

For example, as in 4c) a right-angled pipe element or alternatively a T-piece can be used, which causes turbulence in the flowing medium. A T-piece, which has three connections, is integrated into the pipeline in accordance with the right-angled pipeline element.

reference list

1

Flow measurement arrangement

10

Coriolis meter

11

measuring tube

12

vibration exciter

13

vibration sensor

14

electronic measurement/operation circuit

15

housing

16

carrier body

17

electrical connection line

20

differential pressure gauge

21

measuring tube

22

primary element

22.1

flow constriction

11/22

cover

22.12

venturi nozzle

22.13

measuring tube taper

23.1

pressure sensor

23.2

differential pressure sensor

23.3

pressure line

24

electronic measurement/operation circuit

25

measuring input

30

separate evaluation point

34

electronic measurement/operation circuit

40

mixing device

41

tee

42

pipe elbow

43

flow resistance element

51

distance

52

distance

60

pipeline

61

vertical section

62

horizontal section

70

pressure sensor

80

differential pressure gauge

81

pressure line

84

electronic measurement/operation circuit

90

water content measuring device

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• WO 2012129603 A2 [0002]

Claims (14)

Flow measuring arrangement (1) for measuring a flow of a medium flowing through a pipeline (60) with at least two medium components of different states of aggregation, comprising: a Coriolis measuring device (10) set up for measuring a density of the medium, comprising at least one measuring tube (11), at least one vibration exciter (12) for exciting measuring tube vibrations, at least two vibration sensors (13) for detecting the measuring tube vibrations, and an electronic measuring/operating circuit (14) for operating the vibration exciter and for recording measurement signals from the vibration sensors and for outputting measured density values of the medium ; An effective pressure measuring device (20) set up for measuring a mass flow rate or a flow rate of the medium, comprising a measuring tube (21) with an effective pressure transmitter (22) with a flow cross-section constriction (22.1) set up for measuring a first pressure drop in the medium, which first pressure drop through the effective pressure transmitter is caused, as well as at least two pressure sensors and/or a differential pressure sensor (23.2), and an electronic measuring/operating circuit (24) for operating the pressure sensors and for outputting differential pressure measured values of the first pressure drop; wherein the Coriolis measuring device and the effective pressure measuring device are integrated into the pipeline, wherein the effective pressure measuring device is arranged downstream of the Coriolis measuring device, wherein an electronic measuring/operating circuit (14, 24, 34) is provided which is set up for this purpose to determine a mass flow rate, a volume flow rate or a flow rate of the medium through the pipeline from the measured density and from the measured first pressure drop, characterized in that the Coriolis measuring device is arranged in a vertical or horizontal section (61) of the pipeline (60). is, wherein the effective pressure measuring device is arranged in a horizontal section (62) of the pipeline. flow meter arrangement claim 1 , the Coriolis measuring device is set up to include the presence of the gaseous medium component in a calculation of measured density values when a gaseous medium component is detected. Flow measuring arrangement according to 1 or 2, wherein the flow cross-section constriction (22.1) is brought about, for example, by one of the following elements: A diaphragm (22.11), a Venturi nozzle (22.12), a measuring tube taper (22.13). Flow measuring arrangement according to one of the preceding claims, wherein the flow measuring arrangement has a mixing device (40) between the Coriolis measuring device and the effective pressure measuring device, which is set up to mix the media components. flow measurement arrangement claim 4 wherein the mixing device is a T-piece (41), a right-angle pipe element, a pipe bend (42), or a flow resistance element (43) arranged in a pipe bend. flow measurement arrangement claim 5 , wherein a distance (51) between a media outlet of the mixing device and the narrowing of the flow cross section of the differential pressure measuring device is at most 10 internal diameters of the pipeline and at least 5 internal diameters of the pipeline. Flow measurement arrangement according to one of Claims 1 until 3 , wherein the pipeline has an inner diameter and a center line, wherein the Coriolis measuring device has a media inlet and a media outlet, wherein a distance (52) between the media outlet and the narrowing of the flow cross section of the differential pressure measuring device is at most 10 inner diameters and at least 5 inner diameters. Flow rate measuring arrangement according to one of the preceding claims, wherein the electronic measuring/operating circuit is the electronic measuring/operating circuit of the Coriolis measuring device or the differential pressure measuring device, or the electronic measuring/operating circuit (34) is part of a separate evaluation point (30 ) is. Flow measuring arrangement according to one of the preceding claims, wherein the measuring arrangement has a pressure sensor (70) in addition to the differential pressure sensor (23.2), which is set up to measure the media pressure upstream of the flow cross-section constriction. flow measurement arrangement claim 9 , wherein the pressure sensor (70) is connected to a measuring input (25) of the differential pressure measuring device. Flow measuring arrangement according to one of the preceding claims, wherein a water proportion measurement device (90) is provided for measuring a water content of the medium. Flow measuring arrangement according to one of the preceding claims, wherein the Coriolis measuring device (10) is set up to store measured values of the density of the medium in the absence of a gaseous medium component, and to store a ratio of the gaseous medium component by means of the stored measured values when a gaseous medium component is present to determine the remaining media share. Flow measurement arrangement according to one of the preceding claims, a differential pressure measuring device (80) being provided, which is set up to determine a second pressure drop along the Coriolis measuring device, wherein the electronic measuring/operating circuit (14) is set up to determine a viscosity of the medium by means of measured values of the second pressure drop when a gaseous medium compartment is present. Flow measurement arrangement according to one of the preceding claims, wherein the at least one measuring tube is bent at least in sections, and/or wherein the Coriolis measuring device has a plurality of measuring tubes.

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