JPH08226840A - Coriolis mass flowmeter - Google Patents

Abstract

PURPOSE: To provide a Coriolis mass flowmeter in which the stay, the clogging and the pressure loss of a fluid to be measured can be reduced by a method wherein one end of one measuring tube out of a pair of measuring tubes is made to communicate with one end of the other measuring tube. CONSTITUTION: A connecting tube 11 makes one end of one measuring tube 12 communicate with one end of the other measuring tube 13, and a fluid (f) to be measured flows into from the other end of one measuring tube 12 so as to flow out from the other end of the other measuring tube 13. A vibration is applied to the measuring tubes 12, 13 by a vibrator 3. When the fluid (f) to be measured flows at this time, Coriolis' force is generated, and the measuring tubes 12, 13 are vibrated in a form in which vibration patterns are superposed. When their vibration is measured by vibration detection sensors 4, 5, a mass flow rate can be found. Since no branch or no juncture exists in the flow passage of the fluid (f) to be measured, there is no fear that the fluid (f) to be measured is stayed or clogged in a branch part or a juncture part and that a pressure loss is increased. Consequently, it is possible to obtain a Coriolis mass flowmeter which even a high-viscosity fluid or a fluid which is easy to corrode or clog such as a food or the like can be measured stably at a low pressure loss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Coriolis mass flowmeter which has less stagnant flow, clogging and pressure loss of a measuring fluid.

[0002]

2. Description of the Related Art FIG. 10 is a structural explanatory view of a conventional parallel two U-tube type Coriolis mass flowmeter which is generally used in the past. For example, US Pat. No. 4,491,025, title of the invention. "PARALLEL PATH CORIOLIS MASS FLOW RATE ME
TER "filed on Nov. 3, 1982, patent on Jan. 1, 1985. 11 and 12 are operation explanatory diagrams of FIG. 10.

In the figure, reference numeral 1 is a U-shaped measuring tube having both ends attached to a fixed body 2, which branches into two at the inlet of the flowmeter and joins again at the outlet. Therefore, the measurement fluid f flows in from the flow meter inlet and flows out from the flow meter outlet.

Reference numeral 2 is a fixed body for mounting the measuring pipe 1 on the pipe line A. Reference numeral 3 denotes an exciter provided in the central portion of the U-shaped measuring tube 1, which vibrates the measuring tube 1 in a direction perpendicular to the plane in which the U-shaped measuring tube 1 is present. Reference numerals 4 and 5 are vibration detection sensors respectively provided between the fixed end and the central portion of the measuring tube 1. In this case, an electromagnetic coil (speed sensor) is used.

In the above-described structure, when a vibration is applied from the vibrator 3 installed in the central portion while the measuring fluid is flowing in the measuring pipe 1, as shown in FIG. The measurement tube 1 vibrates in a first-order mode shape in which is an antinode of vibration.

Considering these vibrations on the upstream side and the downstream side of the measuring pipe 1, it can be considered that they are rotating around the fixed end, respectively. Therefore, the angular velocity of the vibration exciter 3 in the vibration direction " Letting “ω” be the flow velocity of the measured fluid be “V” (the symbol surrounded by “” represents a vector quantity), the Coriolis force of Fc = −2 m “ω” × “V” works.

Due to this Coriolis force, as shown in FIG. 12, vibration modes M4 and M6 in which the flexural vibrations are symmetrical in the upstream portion and the downstream portion with respect to the center point of the measuring tube 1 are generated. In addition, actually, the pipe 1 vibrates in a form in which these two types of vibration patterns are superimposed. The mass flow rate Q can be known by measuring this deformation with the vibration detecting means (usually a displacement sensor) 4, 5.

Usually, the vibration amplitude in the vibration detecting means 4 and 5 and the phase difference in the vibration detecting means 4 and 5 are obtained, correction is made by the vibration frequency and temperature, and the mass flow rate is obtained.

[0009]

However, in such an apparatus, since the measuring fluid is branched into two measuring pipes 1, fluid stagnation or clogging occurs at the branching portion and the merging portion, and pressure loss occurs. There are drawbacks such as increase in

The present invention solves this problem. An object of the present invention is to provide a Coriolis mass flowmeter which has less stagnant flow, clogging, and pressure loss of a measurement fluid.

[0011]

In order to achieve this object, the invention is based on the fact that the measuring fluid is caused to flow in the vibrating measuring tubes of the measuring tubes arranged parallel to each other, and the flow of the measuring fluid and the angular vibration of the measuring tube. Coriolis mass flowmeter that deforms and vibrates the measuring pipe by the Coriolis force and measures the change in vibration with a vibration detection sensor to determine the mass flow rate and density. Two
One measuring pipe is connected to one measuring pipe and the other measuring pipe is connected to one measuring pipe, and the measuring fluid can flow in from the other measuring pipe and flow out from the other measuring pipe. The Coriolis mass flowmeter is characterized in that it is provided with a communication tube configured as described above.

[0012]

In the above structure, when the measuring fluid is flown into the measuring tube and the vibrator is driven, the Coriolis force acts. By measuring the amplitude of vibration proportional to this Coriolis force, the mass flow rate can be measured. . Hereinafter, detailed description will be given based on examples.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential structure of an embodiment of the present invention. In the figure, the same symbols as those in FIG. 10 represent the same functions. Only parts different from FIG. 10 will be described below.

Reference numeral 11 connects one end of one measurement pipe 12 of the measurement pipes and one end of the other measurement pipe 13 to connect one measurement pipe 1 to the other.
It is a communication tube that allows the measurement fluid f to flow in from the other end of the second tube 2 and to flow out from the other end of the other measurement tube 13.

In the above structure, the measuring tubes 12, 13
Causes the vibrator 3 to vibrate as indicated by M11, M12, and M13 in FIG. At this time, when the measurement fluid f flows in the direction as shown in FIG. 1, Coriolis force is generated and deformed into the shapes shown by M14, M15, M16 in FIG.

Actually, the measuring tubes 12 and 13 vibrate in such a manner that the two types of vibration patterns shown in FIGS. 2 and 3 are superposed.

As a result, since there is no branching or merging in the flow path of the measuring fluid f, there is no concern that the measuring fluid f will be retained or clogged at the branching or merging portion, or the pressure loss will increase. It is possible to obtain a Coriolis mass flowmeter that can stably measure even a high-viscosity fluid or a fluid such as food that easily rots or clogs, and can measure with low pressure loss.

FIG. 4 is an explanatory view of the essential structure of another embodiment of the present invention. In this embodiment, 21 connects one end of one measurement pipe 22 of the measurement pipes and one end of the other measurement pipe 23, and the measurement fluid f flows from the other end of the one measurement pipe 22,
It is a communication tube that can flow out from the other end of the other measuring tube 23.

Reference numerals 24 and 25 are vibration detection sensors symmetrically provided near the central portion between the fixed ends of the measuring tubes 22 and 23 and the central portions. 26, 27, 28 and 29 are 26 and 27 between the fixed ends of the measuring pipes 22 and 23 and the central part.
28 and 29 face each other, and 26, 27 and 28, 29
Are symmetrically provided vibrators, one end of which is fixed to a Coriolis mass flowmeter main body (not shown).

In the above structure, the measuring tubes 22,
23 is controlled by the vibrators 25 and 26 to move to M21 and M2 of FIG.
2, M23 vibrates. At this time, when the measurement fluid f flows in the direction as shown in FIG. 4, Coriolis force is generated and it is deformed into a shape as shown by M24, M25, M26 in FIG. In addition, actually, the measuring pipe vibrates in a form in which the two types of vibration patterns shown in FIGS.

FIG. 7 is an explanatory view of a main part configuration of another embodiment of the present invention. In this embodiment, 31 is one straight tube-shaped measuring tube 32 of one of the measuring tubes and the other straight tube-shaped measuring tube 3 of the measuring tube 32.
3 is a communication tube that communicates with one end of the measurement tube 32 and allows the measurement fluid f to flow in from the other end of the one measurement tube 32 and flow out from the other end of the other measurement tube 33.

34 and 35 are vibrators provided between the measuring tubes 32 and 33. Reference numerals 36 and 37 denote vibration detection sensors provided between the measuring tube 32 and the apparatus main body (not shown). Reference numerals 38 and 39 are vibration detection sensors provided between the measuring tube 33 and the apparatus main body (not shown).

In the above structure, the measuring pipes 32,
33 is driven by the vibrators 34 and 35, so that M31 and M3 of FIG.
2, M33 is vibrated. At this time, when the measurement fluid f flows in the direction as shown in FIG. 7, Coriolis force is generated and deformed into the shapes as shown by M34, M35, M36 in FIG.

Actually, the measuring tube vibrates in a form in which the two kinds of vibration patterns of FIGS. 8 and 9 are superposed. In addition, in the above-described embodiment, the measuring tube is described as a U-shaped or a straight tube, but the invention is not limited to this, and for example, an S-shaped tube, Ω.
It may be a bent tube shape such as a letter shape.

Further, in the above-described embodiment, the case where the electromagnetic coil (speed sensor) is used as the vibration detection sensor has been described, but the present invention is not limited to this, and may be, for example, a displacement sensor, a stress sensor, or a strain sensor. . In short, it is sufficient if the vibration of the measuring tube can be detected. Further, the vibration mode is not limited to the example, and it goes without saying that the vibration mode may be excited in a vibration mode other than the example.

[0026]

As described above, according to the present invention, the measuring fluid is caused to flow in the vibrating measuring tubes of the measuring tubes arranged parallel to each other, and by the flow of the measuring fluid and the Coriolis force generated by the angular vibration of the measuring tube, In a Coriolis mass flowmeter that deforms and vibrates the measuring tube and measures the change in vibration with a vibration detection sensor to determine the mass flow rate and density, two measuring tubes that have the same shape and both ends are fixed and are arranged in parallel with each other. , One end of one of the measuring pipes communicates with one end of the other measuring pipe so that the measuring fluid can flow in from the other end of the one measuring pipe and flow out from the other end of the other measuring pipe A Coriolis mass flowmeter was constructed which was equipped with a tube.

As a result, since there is no branching or merging in the flow path of the measurement fluid f, there is no concern that retention or clogging of the measurement fluid f will occur at the branching and merging points, or pressure loss will increase. It is possible to obtain a Coriolis mass flowmeter that can stably measure even a high-viscosity fluid or a fluid such as food that easily rots or clogs, and can measure with low pressure loss.

Therefore, according to the present invention, it is possible to realize a Coriolis mass flowmeter which causes less stagnant flow, clogging, and pressure loss of the measurement fluid.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is an operation explanatory diagram of FIG. 1.

FIG. 4 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

5 is an operation explanatory diagram of FIG. 4;

FIG. 6 is an operation explanatory diagram of FIG. 4;

FIG. 7 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 8 is an operation explanatory diagram of FIG. 7;

9 is an operation explanatory diagram of FIG. 7. FIG.

FIG. 10 is a structural explanatory view of another conventional example that is generally used in the past.

11 is an operation explanatory diagram of FIG. 10;

12 is an operation explanatory diagram of FIG. 10. FIG.

[Explanation of symbols]

 2 Fixed body 3 Exciter 4 Vibration detection sensor 5 Vibration detection sensor 11 Connection pipe 12 Measurement pipe 13 Measurement pipe 21 Connection pipe 22 Measurement pipe 23 Measurement pipe 24 Vibration detection sensor 25 Vibration detection sensor 26 Exciter 27 Exciter 28 Exciter 29 Exciter 31 Connection tube 32 Measuring tube 33 Measuring tube 34 Exciter 35 Exciter 36 Vibration detection sensor 37 Vibration detection sensor 38 Vibration detection sensor 39 Vibration detection sensor

Claims (1)

[Claims] 1. A measuring fluid is caused to flow in an oscillating measuring tube of measuring tubes arranged parallel to each other, and the Coriolis force generated by the flow of the measuring fluid and the angular vibration of the measuring tube causes the measuring tube to deform and vibrate, thereby changing the vibration. In a Coriolis mass flowmeter for measuring mass flow rate and density by measuring with a vibration detection sensor, two measuring tubes of the same shape and fixed at both ends and arranged parallel to each other, and one of the measuring tubes It is characterized by further comprising: a communication pipe that communicates one end with one end of the other measurement pipe and allows the measurement fluid to flow in from the other end of the one measurement pipe and to flow out from the other end of the other measurement pipe. Coriolis mass flow meter.