JP4166248B2 - Coriolis meter - Google Patents

Description

  The present invention relates to a Coriolis meter having two arcuate flow tubes in parallel.

  The Coriolis meter supports both ends of the flow tube through which the fluid to be measured flows. When the flow tube is vibrated in the direction perpendicular to the flow direction around the support point, the Coriolis force acting on the flow tube is proportional to the mass flow rate. It is a mass flow meter that uses

  FIG. 8 is a schematic configuration diagram showing an example of such a conventional Coriolis meter (see, for example, Patent Document 1), and shows a parallel two-bow curved tube type. FIG. 8 is a partial cross-sectional view (left side) viewed from the front and a side view (right side) cut at the flow dividing pipe section, assuming that the inlet pipe and the outlet pipe are mounted horizontally. The measurement fluid flows in from the external flow pipe connected through the flange 18 and is equally branched into the two flow tubes 1 and 2 at the inlet side branch pipe. Then, on the outlet side of the flow tubes 1 and 2, they merge at the outlet side branch pipe 25 and flow out to the external flow pipe connected via the flange 19. The flow tubes 1 and 2 are composed of two parallel arcuate curved tubes, and the two flow tubes 1 and 2 are placed in opposite phases by a driving device 15 composed of a coil and a magnet at the center. Resonant drive. In addition, a pair of vibration detection sensors 16 and 17 composed of coils and magnets are installed at symmetrical positions on both the left and right sides with respect to the mounting position of the driving device 15 to detect a phase difference proportional to the Coriolis force. Yes.

  Such a Coriolis meter has a large diameter (large size), and the flow tube drive energy is large, and vibration energy is transmitted to the shunt pipe (manifold) and the support member, so that vibration is generated in the shunt pipe and the support member itself. The stability of the performance as a flow meter is reduced. If the rigidity of the shunt pipe and the support member is insufficient, the shunt pipe and the support member themselves vibrate with the vibration of the flow tube. If the mass of the shunt pipe and the support member is not sufficient, the vibration energy leaked from the flow tube It cannot be absorbed and the entire flowmeter vibrates. Therefore, in order to stabilize the performance as a flow meter, it is necessary to ensure both rigidity and mass in the support member. However, since the shunt pipe has a complicated shape and needs to be manufactured as a cast product, it is not preferable to have a large mass due to manufacturing problems.

  Since the shunt pipe shown in FIG. 8 is connected to the flow tube by welding, the connecting portion of the shunt pipe with the flow tube must be in the same shape as the flow tube. Therefore, for example, since the thickness of the connecting portion of the shunt pipe cannot be increased, the rigidity of that portion is further deteriorated. As a result, vibration is generated in the shunt pipe, which causes a decrease in the performance of the flowmeter.

As the simplest method for giving rigidity to the support member, it is possible to use a member having no space in the cross section of the support member (solid material or the like), but this method is expensive. Therefore, in the past, as a method of giving rigidity to the support member at low cost, a shape (pipe, channel, etc.) in which the mass points of the cross section are gathered with a uniform width at a position away from the center of gravity of the cross section in the cross section is used. There are many. However, in order to obtain a sufficient mass by this method, the wall thickness must be increased. In particular, in a large-diameter flow meter, the wall thickness is difficult to manufacture and the cost is increased.
JP 2001-174307 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such problems and suppress the vibrations of the shunt pipe and the support member due to the driving of the flow tube and stabilize the performance as a flow meter.

The Coriolis meter of the present invention includes two flow tubes in parallel, an inflow side diversion tube and an outflow side diversion tube to which both ends of the two flow tubes are respectively coupled, and spacers that connect and support both the diversion tubes. And a functioning support member. A flow tube coupled moiety attached to each of both distribution pipe, Ru provided with a reinforcing member attached in order to give rigidity to the coupling portion of the distribution pipe. The flow tube coupling portion is formed as two tubular projecting portions, and the reinforcing member is constituted by a plate-like member having holes corresponding to the two projecting portions. By inserting the protruding portion of the diverter pipe into the two holes of the reinforcing member and fixing it by vacuum brazing or welding, each of the diverter pipes formed to join each of the two flow tubes Combine the flow tube coupling parts together.

  The present invention can reduce the vibration of the flow dividing tube without giving a large mass to the flow dividing tube, and can obtain the stability of the performance as a flow meter.

  Hereinafter, the present invention will be described based on examples. FIG. 1 is a view showing an example of an arcuate tube type Coriolis meter using two parallel arcuate flow tubes embodying the present invention, and (A) assumes that an inlet pipe and an outlet pipe are mounted horizontally. Then, in a partial cross-sectional view (left side) as seen from the front, (B) is a side view (right side) cut at the center.

  The flow tubes 1 and 2 of the illustrated Coriolis meter are flow tubes having the same shape curved in an arcuate shape, and both ends of each are connected to an inlet side and outlet side branch pipe (manifold) 25 by welding or the like. It is assumed that the measurement fluid flows in from the left side of FIG. 1 and flows out to the right side. The measurement fluid flows in from the external flow pipe connected through the flange 18 and is equally branched into the two flow tubes 1 and 2 at the inlet side branch pipe. Then, on the outlet side of the flow tubes 1 and 2, they merge at the outlet side branch pipe 25 and flow out to the external flow pipe connected via the flange 19.

  Since the inflow side and the outflow side are configured symmetrically, the illustrated outflow side will be described. The flow dividing pipe 25 smoothly draws a circular arc from the outflow port (connecting portion with the flange 19) in a predetermined angular direction upward. To the connection port with the flow tubes 1 and 2. In this way, by setting the tube connection port of the flow dividing tube to the tube rising angle, the flow tube itself only needs to bend in a simple direction, and the connected flow tube and flow divided tube have a smooth arcuate shape as a whole. Configure. The branch pipe forms two flow paths so as to branch into two flow tubes 1 and 2 from one outlet.

  Thus, the flow tubes 1 and 2 themselves that perform an important function for vibration measurement have only a simple curved configuration in one direction, and the flow path is connected to the external piping from the two flow tubes. Complex flow path changes in the direction are handled by shunt tubes. The flow tubes 1 and 2 are fixed to the shunt tube by welding.

  Also, a substrate 28 is provided near both ends of the flow tubes 1 and 2 to form a vibration node when driven, and this is secured to the flow tubes 1 and 2 so that the flow tubes 1 and 2 are maintained in parallel. is doing. When the substrate 28 is provided, the fixing point by the substrate 28 becomes a first fulcrum of vibration, and the coupling end of the flow tubes 1 and 2 and the upper ends of the inlet side and outlet side branch pipes 25 is the second end. Vibrates as a fulcrum.

  In the central portion of the arcuate flow tube, the drive device 15 has a drive device coil attached to one flow tube 1 and a drive device magnet attached to the other flow tube 2 via attachments. In the pair of vibration detection sensors 16 and 17, on both sides of the driving device 15, a detection sensor magnet is attached to one flow tube 1 and a detection sensor coil is attached to the other flow tube 2 via attachments. The wiring to the drive device coil and the detection sensor coil is led to the outside of the Coriolis meter through the wiring extraction portion 34 located at the center after being arranged along the outer surface of the flow tube. The wiring extraction part 34 is supported by the support member 30 and penetrates through it. The support member 30 holding the entire flow meter with both side branch pipe portions is joined to the pressure-resistant case 31 by welding so as to form a sealed state.

  As described above, the Coriolis meter illustrated in FIG. 1 includes two branch pipes (manifolds) at both ends of the flow tube, and a support member 30 that functions as a branch pipe spacer that connects the two branch pipes. In the Coriolis meter having such a configuration, the present invention is provided with a reinforcing member 8 at the flow tube connecting portion of the flow dividing tube, and the support member has both rigidity and mass in order to make the flow dividing tube have rigidity. For this purpose, the supporting member is formed in a predetermined shape with a uniform thickness and coupled by the mass member 9.

  First, the reinforcing member 8 will be described. FIG. 2 shows a state (A) before attaching the reinforcing member 8 to the flow tube connecting portion of the flow dividing pipe and a state (B) after the attachment. FIG. 3 is a schematic cross-sectional view showing a state after attachment shown in FIG.

  Since the shunt pipe is connected to the flow tube by welding, the connection part of the shunt pipe with the flow tube must be the same shape as the flow tube, and the thickness of the connecting part of the shunt pipe should be too thick. I can't. Therefore, as shown in the figure, the tube welded portion of the shunt pipe becomes two tubular protruding portions (joined portions), and each protruding portion is welded to the flow tube. The reinforcing member is composed of one plate-like member having holes corresponding to the two protruding portions. Such a reinforcing member 8 is arranged so that the protruding portion of the flow dividing tube is inserted into the two holes, and is fixed by vacuum brazing or welding. As a result, the two protruding portions formed for each of the two flow tubes are joined together.

  The rigidity of the reinforcing member 8 fixed in this way can increase the rigidity of the connecting portion of the flow dividing pipe and prevent vibration from leaking into the flow dividing pipe.

  Next, the mass member for giving the support member rigidity and mass will be described. The support member 30 is for holding the entire flow meter with both side branch pipe portions, and in the example shown in FIG. 1, the support member 30 is formed in a U-shaped cross section in which the upper part on the flow tube extension side is open. . The support member 30 is combined with the pressure resistant case 31 to form a sealed state. The support member 30 can have a predetermined rigidity by being configured in a U-shaped cross section with a predetermined uniform thickness. However, considering the workability and the like, the thickness cannot be increased more than a predetermined thickness, and from the shape, there is no mass around the center of gravity of the cross section.

  The mass member 9 is coupled to the open side of the support member 30 in order to add rigidity and mass to the support member 30. By configuring the mass member in a simple plate shape, the cross-sectional shape can easily be a thick member that is at least thicker than the thickness of the support member. Such a mass member is attached except for the bifurcated branch pipe (manifold) portion so as to close the upper open portion of the U-shaped support member. FIG. 4 shows a sectional view of the support member in the attached state. 4A illustrates a U-shaped support member 30 and FIG. 4B illustrates a support member 30 having a U-shaped cross section. The support member 30 and the mass member 9 are coupled by welding, screws, or the like. Thus, by connecting the mass member 9 to the U-shaped or U-shaped support member 30, the overall shape can be practically changed to a cross-sectional box shape, and the rigidity can be further increased. .

  In a Coriolis meter using two flow tubes in parallel, the two flow tubes are driven in opposite phases, so the vibration should ideally not leak outside the meter. Vibration leaks. The present invention can reduce pipe vibration by efficiently increasing the mass of the base portion to obtain sufficient rigidity and mass to receive vibration energy.

  The supporting member has a shape in which the mass points of the cross section are gathered with a uniform thickness at a position away from the center of gravity of the cross section in the cross section in order to have a large rigidity, that is, a shape having a large cross sectional second moment, for example, The shape illustrated in FIGS. 4A and 4B is desirable.

  It is desirable that the mass member be positioned below the vibration fulcrum (position where the flow tube and the diversion tube are connected) and close to the vibration fulcrum from the viewpoint of increasing the rigidity of the support member. In addition, the mass member and the support member are configured symmetrically with respect to a plane that passes through the center of gravity of the meter and is perpendicular to the pipe axis, and are also substantially symmetrical with respect to a plane that passes through the center of gravity of the detector and is perpendicular to the axis of the tube drive direction Composed.

  The plate thickness h required by the mass member will be further described with reference to FIG. As illustrated, the support member has a U-shaped cross section (width A, height B, plate thickness t, length L), and the mass member has a plate shape (plate thickness) having a rectangular cross section. h, length 2/3 L).

Further, the cross-section secondary moment around the axis parallel to the tube drive direction of the support member cross section is I ₁ , the cross-section secondary moment of the mass member cross-section around the axis parallel to the tube drive direction is I ₂ , and the support member mass is Assuming that W ₁ and mass member mass are W ₂ , respectively, the results are as follows.
Support member mass: W ₁ = {2Bt + (A−2t) t} × L (1)
Mass member mass: W ₂ = (A−2t) h × 2 / 3L (2)
Support member cross-section second moment:
I ₁ = 2t / 3 × (Y ₁ ³ + Y ₂ ³ ) + A / 3 × {(Y ₁ + t) ³ −Y ₁ ³ } (3)
^{_{However, Y 1 = {2 (B}} -t) 2 -At} / {4 (B-t) + 2A}
Y ₂ = BtY ₁
Mass moment of inertia of mass section:
^{_{I 2 = (A-2t)}} h 3/12 (4)
The following conditions are assumed based on the functions of the support member and the mass member. That is,
I ₁ > I ₂ (the support member is larger than the mass member at the moment of inertia of the cross section)
W ₁ <W ₂ (in mass, the mass member is larger than the support member)
At this time, the range required for the plate thickness h is (3/2) × {2Bt + (A−2t) t} / (A−2t) <h <
_{^{3 √ {{8t (Y 1}} 3 + Y 2 3) + 4A ((Y 1 + t) 3 -Y 1 3)} / (A-2t)}
(Five)
It becomes.

  FIG. 6 exemplifies the vibration results measured for the case where the reinforcing member is provided and the case where the reinforcing member is not provided. The vertical axis represents the piping vibration strength as the output voltage of the accelerometer. The measurement position is 5 at the center of the Coriolis meter, 4 and 6 are the flanges on the left and right sides, and 3, 2, 1 and the left side, and 7, 8, 9 and the right side. did. Although the vertical vibration in the vertical direction did not have a particular effect, it can be seen that the horizontal vibration in the tube driving direction is greatly reduced by providing the reinforcing member.

  FIGS. 7A and 7B illustrate the vibration results measured when the weight of the mass member is changed. The vertical axis represents the piping vibration strength as the output voltage of the accelerometer. The measurement position was measured at 10, 11, 12 at the center of the Coriolis meter, 6-9, 13-16 at the left and right flanges, and further away from the left and right sides. It can be seen that for both the vertical vibration in the vertical direction and the horizontal vibration in the tube driving direction, the vibration decreases as the weight increases.

It is a figure which shows an example of the arcuate tube type Coriolis meter using two parallel arcuate flow tubes which embody this invention. It is a figure which shows the state (A) before attaching a reinforcement member to the flow tube connection part of a shunt pipe, and the state (B) after attachment. It is a schematic sectional drawing which shows the state after the attachment shown to FIG. 2 (B). It is a figure which shows the supporting member sectional drawing of the state which attached the mass member. It is a figure explaining plate | board thickness h which a mass member requires. It is a graph which illustrates the vibration result measured about the case where a reinforcing member is provided, and the case where it does not exist, respectively. It is a graph which illustrates the vibration result measured about the case where the weight of a mass member is changed. It is a schematic block diagram which shows an example of the conventional Coriolis meter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Flow tube 8 Reinforcement member 9 Mass member 15 Drive device 16, 17 Vibration detection sensor 18, 19 Flange 25 Shunt pipe (manifold)
28 Substrate 30 Support member 31 Pressure-resistant case 34 Wiring extraction part

Claims (1)

Two flow tubes in parallel, an inflow side diversion tube and an outflow side diversion tube to which both ends of the two flow tubes are respectively coupled, and a support member functioning as a spacer for connecting and supporting both the diversion tubes are provided. In the Coriolis meter,
A flow tube coupling part that couples each of the two branch pipes, and a reinforcing member that is joined to give rigidity to the joint part of the branch pipe,
Forming the flow tube coupling portion as two tubular projections;
The reinforcing member is composed of a plate-like member having holes corresponding to the two protruding portions,
Each of the flow dividing pipes formed to join each of the two flow tubes by inserting the protruding portions of the flow dividing pipes into the two holes of the reinforcing member and fixing them by vacuum brazing or welding. A Coriolis meter formed by integrally joining the flow tube coupling portions.

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