Method for determining a quantitative deposit indicator and Coriolis mass flow meter for carrying out the method

Abstract

A method (100) is used to determine a quantitative coating indicator (h rel ), for a Coriolis mass flow sensor with at least one oscillating measuring tube for guiding a medium, wherein the fouling indicator depends on an amount of fouling in the at least one measuring tube, wherein a device parameter (A) is given that is specific for the Coriolis mass flow sensor, wherein the device parameter (A) is a relationship between a viscosity (η) of a medium guided in the at least one measuring tube and a medium-specific damping contribution (D). η ) describes for damping a vibration mode of the at least one measuring tube and in particular for determining a viscosity measurement value (η m ) based on the media-specific attenuation contribution (D η) serves, wherein the coating (C) has a coating material with a material-specific damping property which, depending on the amount of coating, causes damping of the vibration mode of the at least one measuring tube, wherein a material parameter (M) is given that represents the material-specific damping property, wherein the method comprises: determining a damping measurement value (D m ) (110) of at least one vibration mode; determining a surface-specific damping contribution (D c ) (120) based on the damping measurement value (D m ) of at least one vibration mode; providing the material parameter (M) specific to the coating; and determining the coating indicator (h) rel ) (139), based on the surface-specific damping contribution, the material parameter and the device parameter.

Description

[0001] The present invention relates to a method for determining a quantitative deposit indicator and a Coriolis mass flow meter for carrying out the method.

[0002] Detecting deposits in the measuring tubes of Coriolis mass flow meters is important for plant operators because it may necessitate cleaning the measuring devices and, if applicable, any media-contacting components in communication with them. Deposits in Coriolis mass flow meters have been addressed, among others, in DE 10 2017 101 923 A1, DE 10 2005 050 898 A1, DE 10 2020 132 949 A1, and DE 10 2022 134 589 A1. In these cases, an increase in the damping of a vibration mode is typically interpreted as an indication of deposit formation.

[0003] However, a model of the relationship between damping and fouling is currently lacking, making it impossible to describe fouling formation with a uniform model across a multitude of fouling types and configurations of Coriolis mass flow meters. This would allow, for example, the application of findings on fouling formation to different configurations of Coriolis mass flow meters or to different fouling types. The object of the invention is therefore to remedy this lack.

[0004] The problem is solved according to the invention by the method according to independent patent claim 1 and the Coriolis mass flow meter according to independent patent claim 14.

[0005] The method according to the invention serves to determine a quantitative coating indicator (h rel), for a Coriolis mass flow sensor with at least one oscillating measuring tube for guiding a medium, wherein the fouling indicator depends on an amount of fouling in the at least one measuring tube, wherein a device parameter (A) is given that is specific for the Coriolis mass flow sensor, wherein the device parameter (A) is a relationship between a viscosity (η) of a medium guided in the at least one measuring tube and a medium-specific damping contribution (D). η ) describes for damping a vibration mode of the at least one measuring tube and in particular for determining a viscosity measurement value (η m ) based on the media-specific attenuation contribution (D η) serves, wherein the coating (C) comprises a coating material, wherein the coating material has a material-specific damping property, which, depending on the amount of coating, causes damping of the vibration mode of the at least one measuring tube, wherein a material parameter (M) is given that represents the material-specific damping property, wherein the method comprises: determining a damping measurement value (D m ) of at least one vibration mode; determining a surface-specific damping contribution (D c ), based on the damping measurement value (D m ) of at least one vibration mode; providing the material parameter (M) specific to the coating; and determining the coating indicator (h) rel ), based on the surface-specific damping contribution, the material parameter and the device parameter.

[0006] In a further development of the invention, the device parameter (A) is viscosity-independent.

[0007] In a further development of the invention, the material parameter (M) is independent of the device.

[0008] In a further development of the invention, determining the coating-specific damping contribution (D) includes c ): Clean up damping measurement value (D m ) by a self-damping contribution (D0) of at least one measuring tube.

[0009] In a further development of the invention, determining the coating-specific damping contribution (D) includes c ): Clean up damping measurement value (D m ) to achieve a media-specific damping contribution (D η ).

[0010] In a further development of the invention, the correction of the damping measurement value (D) comprises m ) to account for the media-specific damping contribution (D η ), determining the media-specific attenuation contribution (D η ) based on a viscosity value (η) for the medium.

[0011] In a further development of the invention, the method further comprises: checking whether a gas loading of the medium is negligible; and discarding the damping measurement value if this is not the case.

[0012] In a further development of the invention, the material parameter represents a loss factor of the material, particularly for a frequency range from 10^2 Hz to 3^3 Hz. In one embodiment of this further development of the invention, for a ratio R := M / V between the loss factor V and the material parameter: ¼ < R < 4, where the loss factor V applies particularly for a frequency range below a lowest natural frequency of vibrations of the coating at a temperature of 300 K or at an effective medium temperature at which the method is carried out.

[0013] In a further development of the invention, a literature value of the loss factor tan(δ) for the material of the coating is used as a material parameter.

[0014] In a further development of the invention, a reference value of the loss factor tan(δ) is used as a material parameter, wherein the reference value was determined on the basis of a reference measurement. In the reference measurement, damping values ​​of a vibration mode of at least one measuring tube of a Coriolis mass flow meter were measured as a function of the relative ballast strength h. rel determined, and a surface-specific damping contribution Dc of the surface material as a function of the relative ballast thickness h rel The damping of the vibration mode was determined, from which the reference value can be derived, for example according to: M=A⋅Dc(hrel)1−(1−hrel)4

[0015] In a further development of the invention, one or more measured values ​​selected from a list comprising a media temperature measurement; a measuring pipe temperature measurement and a media density measurement are included in the determination of the self-damping contribution and / or media damping contribution and / or the coating indicator.

[0016] In a further development of the invention, the coating indicator comprises a relative coating thickness value h. rel in relation to the inner radius of the measuring tube, where the relative coating thickness value h rel with a monotonically increasing function of the surface-specific damping contribution D c , is calculated, in particular with a function of the type: hrel(Dc)=1−41−AM⋅Dc where A is the device parameter; where M is the material parameter; and where, in particular, the surface-specific damping contribution D c , is calculated according to Dc=Dm−D0−Dη.; or where the coating indicator is a function f(D c ) is calculated, which determines the behavior of the function h rel (D c ) at least over an initial fit range between h rel = 0 and an upper control value of h rel = 0.2, in particular at least over a second fit range between h rel = 0 and an upper control value of h rel = 0.3 approximated, so that for a coefficient of determination R 2 a fit of the function f(D c ) to the function h rel (D c ) Regarding the second fitness area: 1 - R 2 < 1.5%, for example 1 - R 2 < 0.5%, especially 1 - R 2 < 0.25%, or where R is the coefficient of determination 2 a fit of the function f(D c ) to the function h rel (D c ) Regarding the first fitness area: 1 - R 2 < 1.0%, for example 1 - R 2 < 0.3%, especially 1 - R 2< 0.1%. Suitable function types for f(D c Examples include square root functions, linear functions, or quadratic functions.

[0017] In a further development of the invention, the coating indicator comprises a linear function of the relative coating thickness value, wherein the coating indicator is in particular proportional to the relative coating thickness value.

[0018] In a further development of the invention, the method further comprises: comparing the coating indicator with at least one limit value; and outputting a warning signal if the comparison detects an exceedance of the limit value.

[0019] In a further development of the invention, the method further comprises: initiating a maintenance measure in response to the warning signal, wherein the maintenance measure in particular is a cleaning of the at least one measuring tube.

[0020] The Coriolis mass flow meter according to the invention comprises: a Coriolis mass flow meter with at least one oscillating measuring tube for guiding a medium; and a measuring and operating circuit which is configured to control the method according to one of the preceding claims.

[0021] The invention will now be explained in more detail with reference to the exemplary embodiments shown in the drawings. These show: Fig. 1a: A diagram showing damping measurements as a function of the relative pad thickness h rel represents various types of Coriolis mass flow meters. Fig. 1b: A diagram showing surface indicators whose values ​​are a function of the damping measurements from Fig. 1a were determined, and the relative surface thicknesses corresponding to the damping measurements are shown. Fig. 2a: A schematic cross-section of a measuring tube with a coating. Fig. 2b: A schematic cross-section of a measuring tube under the influence of a viscous medium. Fig. 3: A flowchart of an embodiment of the method according to the invention. Fig. 4: A schematic representation of an embodiment of a mass flow meter according to the invention.

[0022] Fig. Figure 1a shows the results of an experiment in which the measuring tubes of various Coriolis mass flow meters from the applicant's portfolio were coated with different relative thicknesses of a wax-like coating. The corresponding damping measurements of the bending vibration mode, or F1 mode, were recorded. The data marked with an asterisk are from a Coriolis mass flow meter designated Promass F 50. The data marked with an asterisk are from a Coriolis mass flow meter designated Promass F 25. The data marked with a circle are from a Coriolis mass flow meter designated Promass Q 50. In this experiment, the measuring tubes were filled with air to observe the effect of the coating without the influence of a damping medium.In principle, the method according to the invention can also be operated with measuring tubes filled with liquid and viscous media.

[0023] From the diagram in Fig. Figure 1a shows that the same relative coating thickness has very different effects on the damping of the bending vibration mode for the different configurations of the Coriolis mass flow meters. Therefore, it is not possible to directly infer the relative coating thickness from an observed damping measurement using a uniform model. The method according to the invention provides a remedy for this, as shown in Figure 1a. Fig. 1b. The coating indicators C(D) shown here m ) were determined using the inventive method as a function of the damping measurement values ​​D m out of Fig. 1a determined and relative coating thickness h above the causative factor relThe data is plotted. A clear linear or proportional relationship is evident, which now allows for a simple interpretation of the damping measurements.

[0024] To explain the modeling according to the invention, reference is made to Fig. 2a and Fig. 2b referred to. In the modeling of the damping of a vibration mode of a measuring tube 210 by a coating 212 with the relative coating thickness h rel The invention is based on an analogy to viscous damping by a medium 214, whose damping effect can be described by the relative strength ε of the Stokes layer. This analogy is helpful insofar as device-specific parameters required to describe the relationship between vibration damping and the viscosity of a medium are established for various types of Coriolis mass flow meters and, based on the above analogy, can now be used to characterize deposits.

[0025] Assuming a coating with relative coating thickness h rel and with a coating-specific loss factor tan(δ) a coating-specific damping contribution D c The relative thickness of the covering, which is proportional to the area moment of inertia of the covering, can be expressed as: hrel=1−41−k'tan(δ)Dc, where k' is initially a factor yet to be defined, which incorporates device-specific properties.

[0026] As a general rule: hrel≈14k'tan δDc

[0027] The relative thickness of the Stokes layer, given by the Stokes number St, is given by: St=2εdi≈A1f2ρDη, where Dη is a viscosity-specific damping contribution, and where A1 describes a device-specific factor in the relationship between Stokes number and viscosity-specific damping, where the factor is further divided by the square of the natural frequency f of the vibration mode, which depends on the medium density, and the density ρ of the damping medium. In practice, it has been found that the medium density remains constant at 1000 kg / m³. 3 can be applied and f is the device-specific associated natural frequency.

[0028] By comparing the last two equations, the following can be deduced by analogy: k'=4 A1f2ρ

[0029] An embodiment 100 of the method according to the invention will now be described using the following examples: Fig. 3 explained.

[0030] The procedure 100 begins with the acquisition 110 of a damping measurement value D m .

[0031] The next step is determining 120 of a surface-specific damping contribution D. m based on the damping measurement value. This includes correcting 122 of the damping measurement value D. m to account for the self-damping contribution D0 of the measuring tube, as well as the correction 124 of the damping measurement value D m to determine a viscosity-specific damping contribution D η ...so that the surface-specific damping contribution D c is given as: Dc=Dm−D0−Dη.;

[0032] The determination of the relative coating thickness follows, according to section 130. hrel(Dc)=1−41−AM⋅Dc where the device parameter A is given by: A = k', and where the loss factor tan(δ) is used for the material parameter M. The loss factor describes the ratio between the imaginary and real parts of the complex modulus of elasticity of the lining material, with the imaginary part representing the damping effect of the lining material. If available, the loss factors can be obtained from material data literature, or they can be experimentally determined for the lining types of interest and then made available in a database. The experimental determination of a loss factor essentially involves determining a lining-specific damping contribution for a given relative lining thickness h. rel carried out, from which the material parameter M or the loss factor can then be determined according to the following equation: M=A⋅Dc(hrel)1−(1−hrel)4

[0033] If necessary, the coating indicator can be further normalized, for example in such a way that the maximum permissible relative coating thickness results in a coating indicator with the value 1.

[0034] Finally, a limit value comparison 150 can follow, whereby if the limit value is exceeded by the coating indicator, a maintenance requirement, in particular a cleaning requirement, is signaled.

[0035] The in Fig. 4. An embodiment of a Coriolis mass flow meter 200 according to the invention comprises a sensor 202 in the interior of which two measuring tubes 212 run parallel to each other and are mounted to be oscillatable relative to each other.

[0036] The Coriolis mass flow meter 200 further comprises an electronics housing 204 with a measuring and operating circuit 206 for driving a vibration exciter to excite the measuring tube oscillations, and for acquiring vibration sensor signals, as well as for carrying out the method according to the invention. The damping values ​​are determined in particular on the basis of an excitation current for exciting the measuring tube oscillations in relation to the achieved vibration amplitude. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 101 923 A1

[0002] DE 10 2005 050 898 A1

[0002] DE 10 2020 132 949 A1

[0002] DE 10 2022 134 589 A1

[0002]

Claims

[1] Method (100) for determining a quantitative coating indicator (h rel ), for a Coriolis mass flow sensor with at least one oscillating measuring tube for guiding a medium, wherein the fouling indicator depends on the amount of fouling in the at least one measuring tube, wherein a device parameter (A) is given which is specific for the Coriolis mass flow sensor, wherein the device parameter (A) is a relationship between a viscosity (η) of a medium guided in the at least one measuring tube and a medium-specific damping contribution (D) η ) describes for damping a vibration mode of the at least one measuring tube and in particular for determining a viscosity measurement value (η m ) based on the media-specific attenuation contribution (D η ) serves, wherein the coating (C) comprises a coating material, wherein the coating material has a material-specific damping property which, depending on the amount of coating, causes damping of the vibration mode of the at least one measuring tube, where a material parameter (M) is given that represents the material-specific damping property, the procedure includes: Determining a damping measurement value (D) m ) (110) of at least one mode of vibration; Determining a surface-specific damping contribution (D) c ) (120) based on the damping measurement value (D m ) of at least one vibration mode; Providing the material parameter (M) specific to the coating; and Determining the coating indicator (h rel ) (139), based on the surface-specific damping contribution, the material parameter and the device parameter. [2] Method according to claim 1, wherein the device parameter (A) is viscosity independent. [3] Method according to claim 1 or 2, wherein the material parameter (M) is independent of the device. [4] Method according to one of the preceding claims, wherein the determination of the surface-specific damping contribution (D c ) (120) includes: Clean (122) attenuation measurement (D m ) by a self-damping contribution (D0) of at least one measuring tube. [5] Method according to one of the preceding claims, wherein the determination of the surface-specific damping contribution (D c ) includes: Clean (124) attenuation measurement (D m ) to achieve a media-specific damping contribution (D η ). [6] Method according to claim 5, wherein the clearing (124) of the damping measurement value (D m ) to account for the media-specific damping contribution (D η ), determining the media-specific attenuation contribution (D η) based on a viscosity value (η) for the medium. [7] Method according to any of the preceding claims, further comprising: checking whether the gas loading of the medium is negligible; and discarding the attenuation measurement if this is not the case. [8] Method according to one of the preceding claims, wherein the material parameter represents a loss factor of the material, in particular for a frequency range comprising from 10^2 Hz to 3^3 Hz. [9] Method according to one of the preceding claims, wherein one or more measured values ​​selected from a list comprising a media temperature measurement; a measuring pipe temperature measurement and a media density measurement are included in the determination of the self-damping contribution and / or media damping contribution and / or the coating indicator. [10] Method according to any one of the preceding claims, where the coating indicator represents a relative coating thickness value h rel in relation to the inner radius of the measuring tube, where the relative coating thickness value h rel with a monotonically increasing function of the surface-specific damping contribution D c , is calculated, especially with a function of the type: hrel(Dc)=1−41−AM⋅Dc where A is the device parameter; where M is the material parameter; and where in particular the damping contribution D c , calculated according to D c = D m - D0 - D η . [11] Method according to any of the preceding claims, wherein the coating indicator comprises a linear function of the relative coating thickness value, wherein the coating indicator is in particular proportional to the relative coating thickness value. [12] Method according to any of the preceding claims, further comprising: Comparing the surface area indicator with at least one limit value; and Output of a warning signal if the comparison detects that the limit has been exceeded. [13] The method of claim 11, further comprising: Initiating a maintenance measure in response to the warning signal, wherein the maintenance measure includes in particular cleaning of the at least one measuring tube. [14] Coriolis mass flow meter, comprising: a Coriolis mass flow sensor with at least one oscillating measuring tube for guiding a medium; and a measuring and operating circuit designed to control the method according to one of the preceding claims.

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