CORIOLIS MEASURING TRANSMITTER AND CORIOLIS MEASURING DEVICE

Abstract

The present disclosure relates to a Coriolis measuring transmitter of a Coriolis measuring device for measuring a mass flow or a density of a medium flowing through a pipe, which includes: at least one pair of measuring tubes arranged to oscillate relative to each other, wherein each measuring tube includes a centrally arranged bend, at least one driver and at least two vibration sensors; two guiding devices, each including a fluid chamber with a first opening for connection with the pipe and second openings for each measuring tube for connection with the measuring tubes, wherein the guiding devices are each formed from multiple parts, for example, formed from two parts, wherein a first part forms a pipe connecting part, and wherein at least one second part forms a measuring tube connecting part.

Claims

1. A Coriolis measuring transmitter of a Coriolis measuring device for measuring a mass flow or a density of a medium flowing through a pipe; the measuring transmitter comprising: at least one pair of measuring tubes arranged to oscillate relative to each other, wherein each measuring tube includes a central bend, wherein in an equilibrium position the measuring tubes of the at least one pair of measuring tubes are symmetrical with respect to a symmetry plane extending between both measuring tubes; at least one driver configured to oscillate the measuring tubes; at least two sensors configured to measure the oscillations of the measuring tubes; and two guiding devices configured and arranged to guide the medium, wherein one guiding device is configured and arranged to guide the medium from the pipe into each measuring tube, and wherein the other guiding device is configured and arranged to guide the medium from each measuring tube into the pipe, wherein each guiding device comprises a fluid chamber with a first opening configured to connect to the pipe and with second openings for each measuring tube, the second openings each configured to connect to a measuring tube of the at least one pair of measuring tubes, wherein each guiding device comprises multiple parts, wherein a first part is configured to connect to the pipe, and wherein at least one second part is configured to connect to the measuring tubes of the at least one pair of measuring tubes, wherein in a projection of the fluid chamber onto the symmetry plane, the fluid chamber follows a chamber bend connecting a measuring tube volume with a pipe volume, and wherein the first part and the at least two second parts are connected together leak-tightly by a corresponding interface, wherein each interface comprises a protrusion and a recess at least partially complementary to the projection.

2. The measuring transmitter of claim 1, wherein each guiding device comprises two parts, the first part and a second part of the at least one second part.

3. The measuring transmitter of claim 1, wherein the connection of the interface is secured by one of screwing, locking, clicking, gluing, welding, bonding, sintering and brazing.

4. The measuring transmitter of claim 1, wherein the fluid chamber comprises a bifurcation including a first bifurcated part and a second bifurcated part, wherein within the first bifurcated part each cross-section of the fluid chamber defines a single coherent area having a single center of area, wherein within the second bifurcated part each cross-section of the fluid chamber defines two disconnected areas, each corresponding to an associated measuring tube of the at least one measuring tube pair and each with a separate center of area, wherein a center line is defined by a projection of the centers of area of the cross-sections of the second bifurcated part onto the symmetry plane, wherein a section of the center line, which coincides with the chamber bend, confines an angle, Θ, and defines a length, R.sub.CL, at Θ=0° from a center of the angle to the center line, wherein a start of the chamber bend where Θ=0° is adjacent the pipe, and wherein an end of the chamber bend is adjacent a corresponding measuring tube, wherein a shape of each cross-section is characterized by two circles each having a center and a same radius, wherein a separation of the centers of the circles perpendicular to the symmetry plane and the radii depend on the angle as defined by:
R(Θ)=R.sub.P*F.sub.R(Θ), wherein R as a radial length measured from a center of area, R.sub.P is a scalar constant representing a pipe radius, F.sub.R is a monotonically non-increasing function with a maximum at Θ=0°, and S(Θ) is a monotonically non-decreasing function with a minimum at Θ=0°, and wherein cross-section planes defined by the cross-sections comprise the center of the angle.

5. The measuring transmitter of claim 4, wherein a ratio of the length to the pipe radius is 1.8<R.sub.CL/R.sub.P<2.4.

6. The measuring transmitter of claim 5, wherein the ratio of the length to the pipe radius is 2<R.sub.CL/R.sub.P<2.2.

7. The measuring transmitter of claim 4, wherein the length is 16.5 mm<R.sub.CL<20.5 mm, and/or the pipe radius is 8.5 mm<R.sub.P<9 mm.

8. The measuring transmitter of claim 7, wherein the length is 18 mm<R.sub.CL<19 mm, and/or the pipe radius is 8.7 mm<R.sub.P<8.8 mm.

9. The measuring transmitter of claim 4, wherein the bifurcation occurs at a bifurcation angle greater than 45° and less than 75°.

10. The measuring transmitter of claim 9, wherein the bifurcation angle is greater than 55° and less than 65°.

11. The measuring transmitter of claim 4, wherein the monotonically non-increasing function is defined by:
F.sub.R=−a*Θ+1, wherein 0.0031<a<0.0051.

12. The measuring transmitter of claim 11, wherein 0.0039<a<0.0043.

13. The measuring transmitter of claim 4, wherein a ratio of the monotonically non-decreasing function to the pipe radius is defined by:
S(Θ)/R.sub.P=b*Θ, wherein 0.0109<|b|<0.0169.

14. The measuring transmitter of claim 13, wherein 0.0134<|b|<0.0144.

15. The measuring transmitter of claim 4, wherein the length defines an arc of a circle confining the angle with a radius of the length, wherein within cross-sectional planes, projections of individual centers of area onto the symmetry plane deviate from the arc of a circle towards the center of the angle by a deviation, wherein for angles less than a critical angle, an absolute value of a ratio of the deviation to the pipe radius is less than 0.01, wherein for angles greater than the critical angle, the ratio of the deviation to the pipe radius is:
y/R.sub.P=|c1*Θ{circle around ( )}−c2*Θ+c3|, wherein 0.000024<c1<0.000064, wherein 0.00577<c2<0.00977, wherein 0.053<c3 <0.093 and wherein 6°<Θ.sub.C<15°.

16. The measuring transmitter of claim 15, wherein 0.000039<c1<0.000049, wherein 0.00727<c2<0.00827, wherein 0.068<c3<0.078 and wherein 9°<Θ.sub.C<11°.

17. A measuring device for measuring a mass flow or a density of a medium flowing through a pipe, the measuring device comprising: a measuring transmitter according to claim 1; and an electronic circuit configured to operate the at least one driver and the at least two sensors and to generate measuring values for the mass flow and/or the density of the medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In the following drawings, the present disclosure is described on the basis of exemplary embodiments, in which:

[0038] FIG. 1 shows a partial cut-away view of a Coriolis measuring device with a Coriolis measuring transmitter;

[0039] FIGS. 2a and 2b show perspective views of exemplary guiding device according to the present disclosure;

[0040] FIG. 2c shows an exemplary fluid chamber according to the present disclosure;

[0041] FIG. 2d illustrates a schematic projection of the fluid chamber onto a symmetry plane;

[0042] FIG. 3a shows a perspective view of an exemplary fluid chamber according to the present disclosure; and

[0043] FIG. 3b shows multiple cross-sections of the exemplary fluid chamber of FIG. 3a.

[0044] FIG. 1 shows an exemplary Coriolis measuring device 1 with a Coriolis measuring transmitter 10 for measuring a mass flow or a density of a medium flowing through a pipe comprising at least one pair of measuring tubes 11 arranged to oscillate relative to each other, wherein each measuring tube comprises a centrally arranged bend.

[0045] In an equilibrium position, the measuring tubes 11 of a pair of measuring tubes are symmetrical with respect to a symmetry plane 71 between both measuring tubes. At least one driver 12 is arranged to oscillate the measuring tubes, and at least two sensors 13 are arranged for measuring the oscillations of the measuring tubes. The oscillations cause deflections of the measuring tubes perpendicular to the symmetry plane 71.

[0046] Two guiding devices 20 are arranged for guiding the medium from a pipe to the measuring tubes and vice versa, wherein each guiding device comprises a fluid chamber 21 with a first opening for connection 21.1 with the pipe and with a second opening 21.2 for each measuring tube for connection with the measuring tubes. In FIG. 1, the guiding devices 20 are guiding devices according to the state of the art and designed with a level progression of the flow path. This design leads to less compact Coriolis measuring transmitters and seriously limits flow path optimizations.

[0047] FIGS. 2a and 2b show perspective views of an exemplary guiding device according to the present disclosure, namely, an exploded view graphic in FIG. 2a and a joint part graphic including measuring tubes in FIG. 2b, wherein the guiding device 20 is formed from two parts, wherein a first part 20.01 forms a pipe connecting part, and wherein a second 20.02 part forms a measuring tube connecting part. As shown in FIGS. 2a and 2b, the second parts 20.02 may be formed from one piece; alternatively, they may also be formed from two separate pieces.

[0048] In a projection of the fluid chamber onto the symmetry plane 71, the fluid chamber follows a chamber bend 21.3 connecting a measuring tube volume 11.1 with a pipe volume 40.1, see also FIG. 2d. The guiding device may alternatively also be formed from more than two parts. First part 20.01 and second part 20.02 are connected via an interface 22 comprising a protrusion 22.1 and a corresponding recess 22.2, such that a leak-tight connection is arranged. As shown here the protrusion 22.1 can be part of the first part 20.01, and the recess can be part of the second part. However, alternatively, the protrusion 22.1 can be part of the second part 20.02, and the recess can be part of the first part 20.01.

[0049] FIG. 2c shows an exemplary fluid chamber 21 within a guiding device according to the present disclosure with a first opening for connection 21.1 with the pipe and with a second opening 21.2 for each measuring tube for connection with the measuring tubes, wherein according to the present disclosure the fluid chamber follows a chamber bend 21.3 connecting a measuring tube volume 11.1 with a pipe volume 40.1, see also FIG. 2d.

[0050] FIG. 2d shows a projection of a fluid chamber 21 according to the present disclosure onto the symmetry plane 71. A center line 21.7 of the chamber bend 21.3 defined by a projection of the center of areas of cross-sections of the fluid chamber onto the symmetry plane confines an angle Θ and defines a length R.sub.CL at Θ=0° from a center 73 of the angle to the center line. Length R.sub.CL defines an arc of a circle 74 confining 0 with a radius of the length R.sub.CL. In an embodiment, in cross-section planes 72 projections of the center of area 21.51, 21.61 onto the symmetry plane 71 deviate from the arc of a circle towards the center of the angle 73; therefore, the center line 21.7 deviates from the arc of a circle towards a center 73 of the angle Θ, which at the same time is a center of the arc of a circle. The deviation takes a value y dependent on angle Θ.

[0051] The chamber bend has a start of the chamber bend 21.31 with Θ=0° facing the pipe and an end of the chamber bend 21.32 facing a corresponding measuring tube. In that way, the guiding device may be formed in a compact manner with low flow resistance.

[0052] FIG. 3a shows a cross-sectional perspective view of a fluid chamber according to the present disclosure illustrating geometric parameters radius R of circles characterizing cross-sections of the fluid chamber in corresponding cross-section planes 72 and a length R.sub.CL at Θ=0° between the center line and the center of angle Θ.

[0053] FIG. 3b shows a progression of cross-sections of an exemplary fluid chamber according to the present disclosure with increasing values of Θ, wherein radii of circles decrease monotonically with increasing Θ and wherein a separation of centers of the circles increases monotonically with increasing Θ.

[0054] With Θ=0 both circles overlap entirely and R=R.sub.P. With increasing Θ, the overlap decreases until at roughly Θ=55° the overlap becomes 0. From this point both circles are separated, such that a bifurcation of the cross-section takes place.

[0055] In an embodiment, the ratio of the length to the pipe radius is 1.8<R.sub.CL/R.sub.P<2.4, for example, 1.9<R.sub.CL/R.sub.P<2.3, and by further example, 2<R.sub.CL/R.sub.P<2.2.

[0056] In an embodiment, the length is 16.5 mm<R.sub.CL<20.5 mm, for example, 17.5 mm<R.sub.CL <19.5 mm, and by further example, 18 mm<R.sub.CL<19 mm, and/or the pipe radius is 8.5 mm<R.sub.P<9 mm, for example, 8.6 mm<R.sub.P<8.9 mm, and by further example, 8.7 mm<R.sub.P<8.8 mm. In this way a compact setup is achieved still allowing for sufficient medium flow.

[0057] In an embodiment the bifurcation occurs at an angle Θ.sub.B within an interval I of Θ, wherein 45°<Θ.sub.B<75°, for example, 50°<Θ.sub.B<70°, and by further example, 55°<Θ.sub.B<65°. In this way, the first bifurcated part and the second bifurcated part may have a well optimized flow path.

[0058] In an embodiment, the monotonically non-increasing function is F.sub.R=−a*Θ+1 with 0.0031<a<0.0051, for example, 0.0036<a<0.0046, and by further example, 0.0039<a<0.0043. This proved to be a particularly advantageous parameter range.

[0059] In an embodiment, the monotonically non-decreasing function is S(Θ)/R.sub.P=b*Θ with 0.0109<|b|<0.0169, for example, 0.0129<|b|<0.0149, and by further example, 0.0134<|b|<0.0144. This proved to be a particularly advantageous parameter range.

[0060] In the progression of the fluid chamber 21, there is a critical angle Θ.sub.C about which the flow behavior changes. In an embodiment, the length R.sub.CL defines an arc of a circle confining Θ with a radius of the length R.sub.CL, wherein within cross-section planes projections of the center of area onto the symmetry plane deviate from the arc of a circle towards the center of the angle, wherein for Θ<Θ.sub.C for a deviation y following is valid:

|y/R.sub.P|<0.01,

[0061] wherein for Θ>Θ.sub.C for the deviation y following is valid:

y/Rp=|c|*Θ2—c2*Θ+c3|,

[0062] wherein 0.000024<c1<0.000064, for example, 0.000034<c1<0.000054, and by further example, 0.000039<c1<0.000049; wherein 0.00577<c2<0.00977, for example, 0.00677<c2 <0.00877, and by further example, 0.00727<c2<0.00827; wherein 0.053<c3<0.093, for example, 0.063<c3<0.083, and by further example, 0.068<c3<0.078; and wherein 6°<Θ.sub.C<15°, for example, 8°<Θ.sub.C<12°, and by further example, 9°<Θc<11°.

[0063] These proved to be particularly advantageous parameter ranges.