WO2002097376A1

WO2002097376A1 - Coriolis flowmeter

Info

Publication number: WO2002097376A1
Application number: PCT/JP2002/005161
Authority: WO
Inventors: Kazumasa Ohnishi; Akihisa Inoue
Original assignee: Kazumasa Ohnishi; Inoe Akihisa
Priority date: 2001-05-29
Filing date: 2002-05-28
Publication date: 2002-12-05
Also published as: JP2002350207A

Abstract

A high-sensitivity Coriolis flowmeter measuring the mass flow rate of a fluid by detecting a Coriolis force generated in a fluid for measuring the flow rate flowing through a measuring tube under oscillatory state, in which the measuring tube can be formed of an alloy composition having a Young’s modulus of not higher than 90 Gpa and an yield strength of not lower than 100 Mpa.

Description

Description Coriolis flowmeter

[Technical field] ,

The present invention relates to a Coriolis flow meter.

[Background technology]

Flow meters are used in a variety of fields, such as metering various fluids in plants or measuring gas and tap water consumed at home. Flow meters are classified into volume flow meters and mass flow meters. Mass flow meters have the advantage that they are less susceptible to fluctuations in fluid temperature and pressure, and are attracting attention as flow meters that exhibit higher measurement accuracy than volume flow meters.

A Coriolis flowmeter, which is a type of mass flowmeter, is a flowmeter that measures the mass flow rate of a fluid by detecting Corioliska generated in the fluid flowing inside a vibrating measurement tube. The Coriolis flowmeter is composed of a measurement tube through which the fluid to be measured is to flow, a vibration generator for vibrating the measurement tube to generate Coriolis in the fluid, and a sensor for detecting the Coriolis. Coriolis is proportional to the product of fluid mass and velocity. Therefore, the mass flow rate of the fluid can be measured by detecting Coriolis. Due to the Coriolis force generated in the fluid, the measuring tube undergoes elastic deformation such as bending and torsion. Coreica is detected by measuring the amount of natural deformation of the measuring tube. Generally, the measurement tube is made of a metal material such as titanium, zirconium, and stainless steel.

Since the Coriolisa generated in the fluid is very weak, the amount of unidirectional deformation of the measurement tube by the Coriolisa is small. Therefore, in order to increase the flow rate measurement sensitivity of the Coriolis flowmeter, studies are being made on the shape of the measurement tube, the method of detecting Coriolis, or the enhancement of the sensor sensitivity.

An object of the present invention is to provide a Coriolis flowmeter exhibiting high measurement sensitivity. [Disclosure of the Invention].

The present inventor studied the material of the measurement tube of the Coriolis flowmeter, and as a result, formed the measurement tube from an alloy composition having a small Young's modulus and a high yield strength, thereby providing a Coriolis flowmeter exhibiting high measurement sensitivity. Can be provided. The present invention relates to a Coriolis flowmeter for measuring a mass flow rate of a fluid by detecting Coriolisa generated in a fluid having a flow measurement symmetry, which flows inside a measurement tube in an oscillating state, wherein the measurement tube has a Young's modulus. A Coriolis flowmeter characterized by being formed from an alloy composition having an OGPa of not more than 9 and a yield strength of not less than 10 OMPa. Preferred embodiments of the Coriolis flow meter of the present invention are as follows.

(1) The alloy yarn composition contains 40 atomic% or more of titanium.

(2) The alloy composition has a composition represented by the following formula.

Τ ί! 00-a -bc-dM _a M ' _b M ,, c V d

[However, M is one or both of Zr and H}, M 'is one or both of Nb and Ta, and M "is Cr, Mo, W, and Is one or more elements selected from the group consisting of Sn, where a, b, c, and d are 5≤a≤40, 1≤b≤30, 0≤c≤10, 0≤d≤ 20, 10≤ a + b + c + d ≤ 60.]

(3) The alloy composition further has a composition represented by the following formula.

T i! oo-abcd Z r _a M ' _b M "c Vd

The present invention also includes a straight tube-type measuring tube provided with a sensor and through which a fluid to be measured flows, and two counter rods arranged in parallel on both sides of the measuring tube with a space therebetween. One end of the measuring tube and one end of each counter rod are fixed to a support, and the other end of the measuring tube and the other end of each counter rod are separate. A vibration generator that vibrates the measurement tube and each counter port so that the vibration phases are opposite to each other, and the measurement tube and each counter port are provided with a vibration generator. Both of the above supports are fixed on a rigid substrate, and the measuring tube has a Young's modulus of 90 GPa or less. There is also a Coriolis flowmeter characterized by being formed from an alloy composition having a lower yield strength of 10 O MPa or more. The preferred embodiment of the alloy composition is the same as the above-mentioned Coriolis flowmeter.

The present invention also includes a curved measuring tube provided with a sensor through which a fluid to be subjected to flow rate measurement flows, and a support for fixing both ends of the measuring tube, and supported on each of both ends of the measuring tube. A Coriolis flowmeter provided with a flow path for flowing a fluid through a body, wherein two auxiliary vibrators that are curved in the same shape as the measurement tube are arranged in parallel on both sides of the measurement tube with an interval therebetween. The measuring tube and each auxiliary vibrator each include a vibration generator that vibrates the measuring tube and each auxiliary vibrating body so that the vibration phases are opposite to each other. The Coriolis flowmeter is also characterized in that the tube is formed from an alloy composition having a Young's modulus of 90 GPa or less and a yield strength of 10 OMPa or more. The preferred embodiment of the alloy composition is the same as that of the above-mentioned Coriolis flowmeter.

The Coriolis flowmeter of the present invention will be described with reference to the attached drawings. FIG. 1 is a perspective view showing a configuration of an example of a Coriolis flow meter according to the present invention. Figure 2 is a cross-sectional view of the Coriolis flow meter of Figure 1. The Coriolis flowmeter shown in Fig. 1 and Fig. 2 is a U-shaped measuring tube 1 through which the fluid to be measured flows, a vibration generator 2 that vibrates the measuring tube 1, and a 弹 1 "raw deformation of the measuring tube 1. It consists of sensors 3a and 3b that detect Corioliska from the amount, etc. At each end of the U-shaped measuring tube 1, a Coriolis flowmeter uses a flange 5 to control the flow rate of the fluid to be measured. It is connected to a flowing system (such as a plant), and the measurement tube 1 through which the fluid to be measured flows is vibrated by the vibration generator 2, and the elastic deformation of the measurement tube 1 detected by the sensors 3a and 3b Obtain the mass flow rate of the fluid from the amount (deflection, twist, etc.) The configuration of the Coriolis flow meter shown in Fig. 1 and Fig. 2 is well known. To The measuring tube 1, and a Young's modulus of 9 0 GP a less and yield strength you formed from the alloy composition is 1 0 0 MP a more. For more information on the alloy composition will be described later. Generally, an electromagnetic oscillator including a coil and a magnet is used as the vibration generator 2. As the sensors 3a and 3b, an electromagnetic pickup, a piezoelectric element, or the like that detects Coriolis from the amount of elastic deformation of the measurement tube 1 is used. There is also known a method for detecting Coriolis from the speed at which the measurement tube elastically deforms using an electromagnetic pickup. Details of vibration generators and sensors are described in “Flow Measurement A to Z” (edited by Japan Federation of Metrology Instruments, Chapter 10, 1995).

Next, the relationship between the Young's modulus of the material forming the U-shaped measurement tube 1 and the measurement sensitivity of the Coriolis flowmeter will be described. Assuming that the U-shaped measurement tube 1 is a simple cantilever, the deflection of the beam is expressed by the following equation (1).

^{(1) y = p L 3} /3 EI

In equation (1), y is the deflection, p is the load, L is the length of the beam, E is the Young's modulus, and Ϊ is the second moment of area. Equation (1) shows that if the Young's modulus of the beam material is halved, the deflection is doubled. That is, for example, if the Young's modulus of the material forming the U-shaped measurement tube is halved, the deflection of the measurement tube is about twice even if the size of the Coriolisa generated in the fluid is the same. It is supposed to be. That is, it is presumed that the measurement sensitivity of the Coriolis flowmeter becomes twice as high.

Next, assuming that the oscillation angular velocity of the U-shaped measuring tube is Ω, the unit mass of the fluid moving inside the measuring tube is Δπι, and the moving speed of the fluid is V, Coriolis force AF generated in the fluid is It is represented by (2).

(2) Δ F == 2 X Δ πι Χ Ω X V,

From equation (2), for example, if the Young's modulus of the measuring tube is reduced by half, the measuring tube bends approximately twice by the driving force of the vibration generator 2, so that the vibration angular velocity Ω is approximately doubled. Therefore, by halving the Young's modulus of the measuring tube, it is estimated that the Coriolis flower ΔF generated in the fluid with the same flow rate is approximately doubled, and the measurement sensitivity of the Coriolis flowmeter is approximately doubled.

In this way, by halving the Young's modulus of the material used for the measurement tube, for example, halving the size of the Coriolisa generated in the fluid, the amount of elastic deformation of the measurement tube by the Corioliser also doubles Therefore, the measurement sensitivity of the Coriolis flowmeter is four It is estimated to be about twice as high.

The measurement tube of a conventional Coriolis flowmeter is formed from materials such as stainless steel, zirconium, and titanium. These materials are selected from the viewpoint of mechanical strength and corrosion resistance to withstand the vibration of the measuring tube. The present inventor has studied formation of the measurement tube from various metal materials (eg, aluminum) having a smaller Young's modulus than these metal materials. However, metal materials with low Young's modulus often have low mechanical strength (yield strength, hardness, etc.), indicating that the vibrations that generate Coriolis force may cause the measurement tube to be plastically deformed. Was. If the measuring tube is plastically deformed, the amount of elastic deformation of the measuring tube due to Corioliser cannot be measured accurately. Table 1 shows the Young's modulus and yield strength of typical materials (titanium, zirconium, and stainless steel) that form the measurement tube of the conventional Coriolis flowmeter. Table 1 shows the Young's modulus and yield strength of aluminum as a typical example of a metal having a low Young's modulus. Table 1

As shown in Table 1, it can be seen that aluminum, which has a lower Young's modulus than the material forming the measurement tube of the conventional Coriolis flowmeter, has extremely low mechanical strength such as yield strength. The present inventor studied various metal materials having a small Young's modulus, but found no metal material suitable for a Coriolis flowmeter.

The present inventor has proposed a method of increasing the measurement sensitivity up to now by forming the measurement tube of the Coriolis flow meter from an alloy composition having a small Young's modulus and a large yield strength (eg, increasing the sensitivity of a sensor). Higher sensitivity of Coriolis flowmeter Found that Specifically, the measurement tube of the Coriolis flowmeter was

And a yield rate of not more than 100 MPa and a yield strength of not less than 100 MPa.

The Young's modulus of the alloy composition forming the measurement tube shall be 90 GPa or less. The Young's modulus is preferably 80 GPa or less, more preferably 70 GPa or less, and even more preferably 60 GPa or less. If the Young's modulus is extremely low, the measuring tube will bend due to vibration in the operating environment, and noise will be generated in the sensor output. Therefore, the Young's modulus of the alloy composition forming the measurement tube is preferably 4 OGPa or more.

The yield strength of the alloy composition forming the measuring tube is 10 OMPa or more. The yield strength is preferably at least 25 OMPa, more preferably at least 500 MPa. The higher the yield strength, the better, but it is generally less than 2000 MPa. An alloy composition having a yield strength of 10 OMPa or more can be used without problems as a material for forming a measurement tube.

By forming the measurement tube from an alloy composition satisfying the above characteristics, the measurement sensitivity of the Coriolis flowmeter can be increased. As the alloy composition, a known alloy composition having the above characteristics can be used. The alloy composition contains 40 atoms of titanium. / ₀ or more is preferable. The measurement tube formed from the alloy composition containing titanium has excellent corrosion resistance.

The alloy thread may be crystalline or amorphous. When the alloy composition is amorphous, it may have a mixed phase structure in which a crystal phase having an average particle size of less than 1 βm is dispersed in the amorphous phase. An alloy composition containing an amorphous phase is obtained by quenching after melt-mixing each composition of the alloy composition. An alloy composition containing an amorphous phase has advantages of high mechanical strength and excellent corrosion resistance.

Coriolis flow meters are used in various environments such as homes and plants. Therefore, it is preferable to adjust the Young's modulus and the yield strength to appropriate values in consideration of the sensitivity of the flow meter and the vibration in the use environment. In order to adjust the Young's modulus and the yield strength, the alloy yarn and the composition may be subjected to a heat treatment. Examples of heat treatment include quenching, tempering, annealing, and normalizing. The alloy composition preferably has a composition represented by the following formula.

T i] oo -b-c-dMoM 'bM "c Vd

[However, M is one or both of Zr and Hf, M 'is one or both of Nb and Ta, and M "is Cr, Mo, W, and S is one or more elements selected from the group consisting of n, where a, b, c, and d are 5≤a≤40, 1≤b≤30, 0≤c≤10, 0≤d≤ 20, 10≤a + b + c + d≤60.]

The alloy composition represented by the above formula (1) and containing at least Ti, Μ, Μ ′ exhibits the values of the aforementioned Young's modulus and yield strength. In order to fine-tune mechanical properties such as Young's modulus and yield strength, toughness, and corrosion resistance, the alloy composition contains one or more of Cr, Mo, W, and Sn elements. , 0 to 10 atoms. /. It is preferable to include it in the range. For the same reason, the alloy composition preferably contains V in the range of 0 to 20 atomic%.

Another example of the Coriolis flowmeter of the present invention will be described. FIG. 3 is a perspective view showing a configuration of another example of the Coriolis flow meter according to the present invention. FIG. 4 is a cross-sectional view of the Coriolis flow meter of FIG. The Coriolis flowmeter shown in FIGS. 3 and 4 has the same configuration as the Coriolis flowmeter of FIG. 1 except that a straight tube type measurement tube 11 is used. An electromagnetic oscillator composed of a magnet 7 and two coils 8 is used for the vibration generator 2 of the Coriolis flowmeter shown in FIG. Each of the coils 8 described an image of the cross section of the coil (the same applies to the following drawings). The configuration of the Coriolis flow meter shown in FIGS. 3 and 4 is well known. In the present invention, the measuring tube 11 is formed of an alloy composition having a Young's modulus of 9 OGPa or less and a yield strength of 10 OMPa or more in order to degrade the measurement sensitivity of the Coriolis flowmeter. I do. Coriolis flowmeters using straight-tube measuring tubes have the advantages of low fluid pressure loss and easy cleaning.

In the Coriolis flowmeter shown in FIGS. 3 and 4, both ends of the straight tube type measurement tube 11 are supported. Assuming that the straight tube type measuring tube is a simple support beam, the deflection of the beam is expressed by the following equation (3).

_{(3) y max = p L} 3/48 EI In equation (3), y is the deflection, p is the load, L is the length of the beam, E is the Young's modulus, and I is the second moment of area.

From equation (3) and equation (1) above, it can be seen that for beams of the same length and made of the same material, the deflection of the simply supported beam is smaller for the same load. Therefore, although the straight-tube type measurement tube has the above-mentioned advantages (small pressure loss of fluid, etc.), the deflection is smaller than that of the U-shaped measurement tube, that is, the sensitivity for detecting Coriolis force. Has the disadvantage of being small. By forming the straight tube type measurement tube from the above alloy composition, it is possible to make up for the drawbacks of the straight tube type measurement tube. As with the U-shaped measurement tube, forming the intuitive measurement tube from the alloy tartar described above makes it possible to double the Coriolisa generated in the fluid and the deflection of the measurement tube due to the Coriolisa about twice, respectively. It is estimated that the measurement sensitivity of the Coriolis flowmeter is about four times higher.

A preferred configuration of the Coriolis flowmeter of the present invention including a straight tube type measurement tube will be described. FIG. 5 is a perspective view showing a configuration of another example of the Coriolis flow meter according to the present invention. FIG. 6 is a plan view of the Coriolis flow meter of FIG. The vibration generator and sensor are shown only in Fig. 6. The Coriolis flowmeter shown in FIGS. 5 and 6 is composed of a straight tube-type measuring tube 11 through which a fluid having a symmetric flow rate flows, and two counter rods 12a and 12b. The measurement tube 11 is formed from the above alloy composition. In the Coriolis flowmeter shown in Figs. 5 and 6, a straight tube is used as the counter rod. The counter rods 12 a and 12 b are respectively arranged in parallel on the 两 side of the measuring tube 11. One end of the measuring tube 11 and one end of each counter rod are fixed to a support 13a. The other end of the measurement tube 11 and the other end of each counter rod are fixed to a support 13b. The supports 13 a and 13 b are fixed on the rigid substrate 14.

The measurement tube 11 is connected to a flow rate measuring system (plant or the like) by flanges 5 provided at both ends thereof. A measurement tube 1 1, between the respective counter rod 1 2 a及Pi 1 2 b, the vibration generator 2 _a and 2 b consisting of the magnet and the coil are arranged. Vibration generator 2a, measuring tube 1 1 and counter When the rod 12a is pulled, the vibration generator 2b keeps the measuring tube 11 and the counter rod 12b away. The measuring tube 11 is provided with sensors 3a and 3b for detecting Coriolisa. The sensors 3a and 3b are symmetrically arranged on both sides of the vibration generator 2a. Piezoelectric elements are used as the sensors 3a and 3b.

The supports 13a and 13b and the counter rods 12a and 12b can be formed from a metal material such as stainless steel or Hastelloy, or an alloy composition. The counter rods 12a and 12b are preferably formed from an alloy composition used for the measurement tube. Examples of the material for forming the rigid substrate 14 include a metal material and ceramics.

The cross-sectional shape of the tube used as the counter rod is not limited to a circle, but may be a polygon or an ellipse. Since it is not necessary to supply a fluid to the counter rod, a rod shape may be used. The shape and mass of the two counter rods are preferably equal to each other. It is preferable that the shape and mass of the measuring tube and each counter rod are equal to each other. The mass of the measuring tube means the mass when the fluid to be measured is filled inside the measuring tube. When the vibration generating device and the sensor are arranged on the measuring tube and the counter rod, it is further preferable that the shape and the mass of the measuring tube and each of the counter rods are equal to each other in a state where they are arranged. When a straight tube is used as the counter rod, it is preferable to fill the inside of the tube with the same fluid as the fluid of the measurement component. '' Each counter rod is symmetrically arranged on both sides of the measuring tube to obtain the vibration mode of the tripod tuning fork vibrator. Tripod tuning fork vibrators are known to provide very stable vibrations and are widely used in resonators and the like. In the Coriolis flowmeter shown in Fig. 5, the primary bending vibration mode of the tripod tuning fork vibrator is used to generate vibration of the measuring tube and counter port, and the tripod tuning fork vibrator is used to detect the amount of elastic deformation of the measuring tube. The second-order bending vibration mode is used.

Some of the vibrations excited by the measuring tube or counter rod are transmitted to the support, causing loss, and lowering the Coriolisa detection sensitivity. In order to suppress such vibration loss, the length of the support (L 2) with respect to the length of the measurement tube (L 1) It is preferable that the ratio (L 2 LI) be 3 Z 10 or more. The length of the support is preferably as long as possible. However, if the length of the support is extremely long, there is a disadvantage that the flow meter becomes large. Therefore, practically, it is preferable that the upper limit of L 2 / L 1 is about 10−10. The length (L 2) of the support means the length of the support along the longitudinal direction of the measurement tube 11.

FIG. 7 is a perspective view showing the configuration of still another example of the Coriolis flowmeter according to the present invention. The measurement tube 11 is formed from the above alloy composition. As shown in FIG. 7, each of the supports 13a and 13b is preferably fixed to the rigid substrate 14 via an elastic body 15 (eg, silicone rubber). With such a configuration, the Coriolis flowmeter can be protected from external vibration in the use environment. FIG. 8 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention. FIG. 9 is a plan view of the Coriolis flow meter of FIG. The measurement tube 11 is formed from the alloy composition described above. Straight tubular tubes are used as the counter rods and 12a and 12b.

Each of the supports 13 a and 13 b is fixed to the rigid substrate 14 via the elastic body 15. The thickness of each of the supports 13 a and 13 b is preferably larger than the diameter of the measurement tube 11. It is also preferable that the thickness of each of the supports 13a and 13b is larger than the diameter of each of the counter rods 12a and 12b. Here, the thickness of the support means the length of the support in a direction perpendicular to the plane formed by the measurement tube and the two counter rods.

A vibration generating device including a magnet 7a and a coil 8a, and a magnet 7b and a coil 8b is disposed between the measuring tube 11 and the counter rods 12a and 12b. Each counter rod is provided with a magnet 7c and a sensor 3c as balance weights on both sides thereof. The magnets, coils, and sensors are described only in FIG. In FIG. 9, the sensor 3c provided on the measuring tube and two counter rods is provided to make the shape and mass of the measuring tube 11 and each counter rod equal to each other (obtain stable vibration). . The sensor 3c arranged in the measurement tube 11 can also detect the amount of elastic deformation of the measurement tube caused by Coriolis. FIG. 10 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention. The Coriolis flowmeter shown in FIG. 10 includes a curved measurement tube 21 through which a fluid to be measured flows, and a support 27 fixing both ends thereof. Each of the two ends of the measurement tube 21 is provided with a flow path for flowing a fluid through the support 27. The measurement tube 21 is formed from the above alloy composition. The measuring tube 21 is provided with sensors 3a and 3b for detecting the amount of elastic deformation of the tube caused by Coriolis, and the like.

On both sides of the measurement tube, two net tang auxiliary vibrators 22 a and 22 b that are curved in the same shape as the curved measurement tube 21 are arranged in parallel with an interval therebetween. Each of the measurement tube and each of the auxiliary vibrators is provided with vibration generators 2a and 2b that vibrate the measurement tube and each of the auxiliary vibrators so that the vibration phases are opposite. The measurement tube 21 is connected to a flow rate measuring system (a plant or the like) via an inflow port 23 and an outflow port 24 of a flow path provided at both ends thereof. It is preferable to attach a flange to each of the inlet 23 and the outlet P 24. The curved measuring tube through which the fluid to be measured flows and each auxiliary vibrator are vibrated by the vibration generators 2a and 2b so that the vibration phases are reversed, and the elastic deformation and strain of the measuring tube are measured. By detecting with 3a and 3b, the mass flow rate of the fluid can be obtained.

In order to obtain stable vibration of the measurement tube and the two auxiliary vibrators, it is preferable that the two auxiliary vibrators have the same shape and mass. It is more preferable that the distances from the measuring tube to the respective auxiliary vibrators are equal to each other. Further, it is more preferable to use the same tube as the measurement tube as the two auxiliary vibrators. When tubes are used as the two auxiliary vibrators, it is more preferable to seal the same fluid as the fluid whose flow rate is to be measured inside each of the tubes.

As the curved measurement tube 21, it is preferable to use a U-shaped measurement tube as shown in FIG. The measuring tube 21 is not limited to a U-shaped measuring tube, and a known curved measuring tube such as a triangle type can be used. The thickness of the support 27 is preferably at least twice the diameter of the measuring tube 21. The thickness of the support means the thickness of the support along the direction perpendicular to the plane on which the measuring tube is fixed.

The vibration generators 2a and 2b for vibrating the measuring tube and the auxiliary vibrator are composed of a magnet and a coil. The vibration generator 2a vibrates the measurement tube 21 and the auxiliary vibrator 22a. The vibration generator 2a includes a coil 28a and magnets 27a and 27b. The vibration generator 2b vibrates the measuring tube 21 and the auxiliary vibrator 22b. The configuration of the vibration generator 2b is the same as that of the vibration generator 2a. When the measurement tube 21 and the auxiliary vibrator 22a are moved away from each other by the vibration generator 2a, the measurement tube 21 and the auxiliary vibrator 22b are attracted to each other by the vibration generator 2b, and the measurement tube And the two auxiliary vibrators are vibrated so that the vibration phases are opposite.

Fig. 11 (a) shows an example of the drive mode (vibration mode of the measurement tube and auxiliary vibrator) of the Coriolis flowmeter of Fig. 10. This drive mode corresponds to the primary bending vibration mode of a tripod tuning fork vibrator. In the drive mode shown in Fig. 11 (a), when the measurement tube 21 and the auxiliary vibrator 22a are moved away from each other by the vibration generator 2a, the measurement tube 21 and the auxiliary vibrator are used by the vibration generator 2b. It is obtained by vibrating the measuring tube and each auxiliary vibrator so that 22b attracts each other. The dotted line in Fig. 11 (a) shows the displacement of the measurement tube and each auxiliary vibrator, and the dashed line shows the displacement of the measurement tube and the tip of each auxiliary vibrator.

Fig. 11 (b) shows an example of the Coriolis flow meter detection mode of the Coriolis flowmeter. This detection mode corresponds to the primary torsional vibration mode of the tripod tuning fork vibrator. The detection mode shown in Fig. 11 (b) is generated by Coriolis when the fluid to be measured flows inside the measurement tube 21 in the drive mode. The dotted line in Fig. 11 (b) shows the displacement of the measuring tube and each auxiliary vibrator, and the dashed line shows the displacement of the measuring tube and the tip of each auxiliary vibrator. By detecting this torsional vibration with sensors 3a and 3b, the mass flow rate of the fluid is measured.

The Coriolis flowmeter shown in Fig. 10 uses the bending vibration mode and the torsional vibration mode of the tripod tuning fork vibrator. High sensitivity and sensitivity because it is hardly affected by external vibrations.

FIG. 12 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention. The Coriolis flowmeter in Fig. 12 uses a tube that is curved in the same shape as the measurement tube as the auxiliary vibrator, and the direction of fluid flow in all three tubes is the same on the support 27. In addition, the channels 25b and 25c connecting the three tubes in series, the channel 25a supplying fluid through the support to one end of the tubes connected in series, and the channels connected in series It has the same configuration as the Coriolis flowmeter of FIG. 10 except that a flow path 25 d for discharging the fluid from the other end of the tube through the support is provided.

Fluid is supplied to flow paths 25b and 25c connecting measurement tube 21 and two auxiliary vibrators 22a and 22b in series, and to one end of three tubes connected in series It is not necessary to provide the flow channel 25a for discharging the fluid and the flow channel 25d for discharging the fluid from the other end inside the support body 27. That is, by additionally providing a pipe below the support, three tubes can be connected in series outside the support, and fluid can be supplied and discharged from below the support.

The Coriolis flowmeter shown in Fig. 12 exhibits high measurement sensitivity because Coriolisa acts on both the measurement tube 21 and the auxiliary oscillators 22a and 22b.

The Coriolis flowmeter of the present invention is characterized by using an alloy composition suitable for a measuring tube. Therefore, the configuration of a known Coriolis flow meter can be applied to the Coriolis flow meter of the present invention.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an example of a Coriolis flow meter according to the present invention.

FIG. 2 is a cross-sectional view of the Coriolis flow meter of FIG.

FIG. 3 is a perspective view showing a configuration of another example of the Coriolis flow meter according to the present invention. FIG. 4 is a cross-sectional view of the Coriolis flow meter of FIG.

FIG. 5 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention.

FIG. 6 is a plan view of the Coriolis flow meter of FIG. FIG. 7 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention. '

FIG. 8 is a perspective view showing the configuration of still another example of the Coriolis flowmeter according to the present invention.

FIG. 9 is a plan view of the Coriolis flow meter of FIG.

FIG. 10 is a perspective view showing a configuration of still another example of the Coriolis flow meter according to the present invention.

11A is a diagram illustrating a driving vibration mode of the Coriolis flowmeter of FIG. 10, and FIG. 11B is a diagram illustrating a detection vibration mode of the same Coriolis flowmeter.

FIG. 12 is a perspective view showing a configuration of still another example of the Coriolis flowmeter according to the present invention. Next, the present invention will be specifically described with reference to examples.

[Example]

Each metal material forming the alloy composition shown in Table 2 was charged into an arc furnace, and each composition was melted and mixed by arc heating, and then poured into a mold, and each alloy composition (sample Nos. 1 to 9) was used. ) Was prepared. A sample was cut out from the prepared ingot and analyzed by X-ray diffraction. As a result, it was confirmed that all the prepared alloy compositions were single-phase solid solutions and had a body-centered cubic structure.

For each of the prepared alloy compositions, Young's modulus E, yield strength cy, ultimate tensile strength (rupture strength) σ ιι, elastic extension limit £ e, fracture extension ε f, and Vickers strength Hv It was measured. Table 2 shows the measurement results. The ratio of the Young's modulus of the alloy composition (Τ) to the Young's modulus of pure Ti (E _TI ) (ΕΖΕ'Γ), the ratio of the yield strength to the Young's modulus of the alloy composition (σ y / E) Table 2 shows the results of calculating the ratio of Pickers hardness to Young's modulus of the alloy composition (Hv / E). table

In Table 2, E is Young's modulus, ay is the yield strength, σ u is the ultimate tensile strength (breaking strength), ε θ is the elastic elongation limit, is the breaking elongation, and Hv is the Vickers hardness. .

Even if the material has a small Young's modulus, if the yield strength / Vickers hardness is small, it is not preferable for practical use in a Coriolis flowmeter. For example, if a material with a small Young's modulus and low yield strength is used for the measurement tube, the measurement tube will be plastically deformed by the driving force of the vibration generator, making it impossible to measure the flow rate accurately. _σ y ZE and Η v ZE are effective for judging whether or not the alloy composition is preferable as a material for forming a measurement tube, and the larger these values are, the more preferable. The value of σγΖΕ is preferably not less than 0.010, and more preferably not less than 0.015. The value of {ν} is preferably at least 0.05.

Young's modulus of the alloy composition prepared is (referring to the value of EZE _{T i} as described in Table 2) almost half of the net T i that has been used in the measurement tube of the Coriolis flowmeter to which Ru der. In addition, the yield strength of the prepared alloy composition is at least five times that of titanium conventionally used for measurement tubes, and at least three times that of zirconium or stainless steel, indicating that it is sufficiently strong for practical use. Therefore, it can be seen that the prepared alloy composition is preferable as a material for forming the measurement tube of the Coriolis flowmeter.

Next, the obtained ingot was rolled to produce a thin plate, which was bent into a tube and welded to form a tube. This tube was cut to make a straight tube type measurement tube. The obtained tube was bent to produce a U-shaped measurement tube.

Using the obtained U-shaped measurement tube, a Coriolis flowmeter having the configuration shown in FIGS. 1, 10, and 12 was manufactured. In the production of the Coriolis flowmeter shown in FIGS. 10 and 12, the same tube as the measurement tube formed from the alloy composition was used as the auxiliary vibrator. Similarly, Coriolis flowmeters having the configurations shown in FIGS. 3, 5, 7, and 8 were produced using the obtained straight tube measurement tubes. In manufacturing the Coriolis flowmeter shown in FIGS. 5, 7, and 8, a tube formed from the above-described alloy composition was used as a counter rod. For comparison, a Coriolis flowmeter with the configuration shown in Fig. 1, Fig. 3, Fig. 5, Fig. 7, Fig. 8, Fig. 10 and Fig. 12 was fabricated using a pure Ti measurement tube. did.

The same flow rate of water as the fluid to be measured was passed through the measurement tube of each Coriolis flowmeter that was fabricated. A sensor attached to the measuring tube of the Coriolis flow meter according to the invention The output voltage from was higher than that of a Coriolis flowmeter with a measuring tube made of pure Ti, confirming that the Coriolis flowmeter according to the present invention had higher measurement sensitivity. -

[Industrial applicability]

Until now, various means have been studied to increase the sensitivity of Coriolis flowmeters, such as the shape of the measuring tube, the method of detecting the Coriolis force, and increasing the sensitivity of the Corioliser sensor. In the present invention, a Coriolis flowmeter having high measurement sensitivity is formed by forming a measurement tube from an alloy composition having a Young's modulus of 9 ° GPa or less and a yield strength of 10 OMPa or more. It has gained. According to the present invention, a Coriolis flowmeter exhibiting a higher measurement sensitivity than before can be easily provided only by changing the material forming the measurement tube.

Claims

The scope of the claims

1. In a Coriolis flowmeter that measures the mass flow rate of a fluid by detecting Coriolisa that is generated in a symmetrical fluid that flows through a measuring tube that is vibrating, the measuring tube has a Young's modulus of 90 GPa. A colorimeter which is formed from an alloy composition having a yield strength of not less than 10 OMPa.

2. The Coriolis flowmeter according to claim 1, wherein the alloy composition contains at least 40 atomic% of titanium.

3. The Coriolis flowmeter according to claim 2, wherein the alloy composition has a composition represented by the following formula.

T i ₁₀₀ - _a -bc-dMaM 'bM "c Vd

[However, M is one or both of Zr and Hf, M 'is one or both of Nb and Ta, and M "is Cr, Mo, W, and Is one or more elements selected from the group consisting of S n, where a, b, c, and d are 5≤a≤40, l≤b≤3, 0≤c≤10, 0≤ d≤ 20 10≤ a + b + c + d≤ 60.]

4. The Coriolis flowmeter according to claim 3, wherein the alloy composition has a composition represented by the following formula.

T i lob -.- bcd Z r _a M 'bM "c Vd

5. A straight tube type measuring tube provided with a sensor and through which a fluid to be subjected to flow measurement flows, and two counter ports arranged in parallel on both sides of the measuring tube with a space therebetween, and the measuring tube Is fixed to one support, and the other end of the measuring tube and the other end of each counter port are separate supports. The measuring tube and each counter Each of the rods is provided with a vibration generating device for vibrating the measuring tube and each counter rod so that the vibration phases are opposite to each other, and the two supports are fixed on a rigid substrate. A Coriolis flowmeter, wherein the tube is formed of an alloy composition having a Young's modulus of 9 OGPa or less and a yield strength of 10 OMPa or more.

6. The Coriolis according to claim 5, wherein the alloy composition contains at least 40 atomic% of titanium.

7. The Coriolis flowmeter according to claim 6, wherein the alloy composition has a composition represented by the following formula.

Τ ϊ, -.- b-c-dMaM 'bM "c Vd

[However, M is one or both of Zr and Hf, M 'is one or both of Nb and Ta, and M "is Cr, Mo, W, and S is one or more elements selected from the group consisting of n, where a, b, c, and d are 5≤a≤40, 1≤b≤30 0≤c≤10, 0≤d≤20, respectively , 1 0≤ a + b + c + d≤ 60.]

8. The Coriolis flowmeter according to claim 7, wherein the alloy composition has a composition represented by the following formula.

T i, o o- _a -bcd Z r, Μ 'bM "cVd

9. The Coriolis flowmeter according to claim 5, wherein each of the two supports is fixed to a rigid substrate via an elastic body.

10. A curved measuring tube equipped with a sensor through which the fluid to be measured flows, and a support for fixing both ends of the measuring tube. Fluid is passed through the support to each of the two ends of the measuring tube. A Rioli flow meter provided with a flow channel, and two auxiliary vibrators that are curved in the same shape as the measurement tube are connected to the measurement tube. Vibration generators are arranged in parallel on both sides of the UBE with a space between them, and each of the measurement tube and each auxiliary vibrator has a vibration generator that vibrates the measurement tube and each auxiliary vibrator so that the vibration phases are opposite. A Coriolis flowmeter, wherein the measurement tube is made of an alloy composition having a Young's modulus of 9 OGPa or less and a yield strength of 10 OMPa or more. .

1 1. The colorimeter according to claim 1, wherein the alloy composition contains at least 40 atomic% of titanium.

12. The Coriolis flowmeter according to claim 11, wherein the alloy composition has a composition represented by the following formula.

[However, M is one or both of Zr and Hf, M 'is one or both of Nb and Ta, and M "is Cr, Mo, W, and Sn A, b, 'c, and d are 5≤a≤40, 1≤b≤30, 0≤c≤10, 0≤d≤ 20, 10≤ a + b + c + d≤60.

1 3. The Coriolis flowmeter according to claim 12, wherein the alloy composition has a composition represented by the following formula.

T i, ₀₀ - _a - _b _ _c _d Z r _a M 'bM "cVd