JPH11211529A - Coriolis flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such merit of a Coriolis flowmeter of a loop type, that has no branching part or merging part, pressure loss is not generated and the clogging with fluid is not generated, and to eliminate complicated and difficult work in the curving work of a flow tube. SOLUTION: This Coriolis flowmeter is constituted of the one of a so-called loop type for which the flow tubes 1 and 2 are constituted of two parallel curved tubes in an optional shape and measurement fluid serially flows inside the two flow tubes 1 and 2. In order to constitute the flow tubes 1 and 2 for making it serially flow, the flowmeter is provided with a manifold 3 inside which an entrance flow passage 4, an exit flow passage 6 and an interconnection flow passage 5 are formed. Thus, the flow passage of a loop shape is constituted so as to make the measurement fluid flow by the three flow passages 4, 5 and 6 formed inside the manifold 3 without performing unreasonable curving work to the flow tubes 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Coriolis flowmeter, and more particularly to a Coriolis flowmeter in which two parallel double curved tubes are connected in series.
It relates to a so-called loop type Coriolis flowmeter.

[0002]

2. Description of the Related Art One end or both ends of a flow tube through which a fluid to be measured flows is supported, and when the flow tube is vibrated around the supporting point in a direction perpendicular to the flow direction of the flow tube, the flow tube (hereinafter referred to as vibration A mass flow meter (Coriolis flow meter) utilizing the fact that Coriolis force acting on a flow tube to be added is referred to as a flow tube is proportional to a mass flow rate. The shape of the flow tube in this Coriolis flowmeter is roughly classified into a curved tube and a straight tube.

[0003] A straight tube type Coriolis flow meter, when vibrated in a direction perpendicular to the center straight tube axis of a straight tube supported at both ends,
A mass flow rate is detected as a displacement difference of the straight pipe due to the Coriolis force between the support portion and the central portion of the straight pipe, that is, a phase difference signal.
Although such a straight tube type Coriolis flowmeter has a simple, compact and robust structure, it cannot obtain high detection sensitivity.

On the other hand, the curved tube type can detect mass flow rate with high sensitivity in that a shape for effectively extracting Coriolis force can be selected. In order to more efficiently drive the bending measurement tube, it is also known that the bending tube through which the measurement fluid flows has a configuration of two parallel tubes.

FIG. 3 is a conceptual diagram of such a conventional parallel twin curved tube type Coriolis flowmeter. As shown in the figure, the flow tube is constituted by two parallel U-shaped tubes, and has a branch portion on the measurement fluid inlet side and a junction portion on the outlet side. The measuring fluid is split equally into the two flow tubes on the inlet side and merges on the outlet side of the flow tubes. In this way, by flowing the measurement fluid equally to the two fluids, the natural frequencies of the two flow tubes can always be equalized even if the type of fluid changes or the temperature changes, by this,
It is known that a Coriolis flowmeter which can be driven efficiently and stably and has no external vibration or temperature influence can be constructed.

However, a pressure loss or a clogging of a fluid may occur at a branch portion at a measurement fluid inlet and at a junction at a measurement fluid outlet. This is a problem especially when the liquid is easily rotten and easily clogged, such as a highly viscous fluid or food. In addition, if there is a branch, if one flow tube penetrates during cleaning, the other tube becomes very poor in cleanability and requires a long time.

As an improvement of this, as shown in FIG. 4, a loop type Coriolis in which two substantially parallel curved tubes are formed by bending one tube to flow a measuring fluid in series. Flow meters are also known.

[0008] However, such a pipe can solve the above-mentioned problems caused by the formation of the branch and the merge, but needs to be bent not three-dimensionally but three-dimensionally. In addition, there arises a problem that the bending processing becomes complicated and difficult, and that distortion at the time of processing affects measurement accuracy.

[0009]

SUMMARY OF THE INVENTION Accordingly, in order to solve the above-mentioned problems, the present invention provides a loop in which a parallel double curved tube is formed as a flow tube by bending a single tube as described above. The advantages of the type Coriolis flowmeter, that is, there is no branch or confluence, pressure loss occurs,
While maintaining the advantage of preventing clogging of fluid, it solves the problem of bending processing, which makes the processing complicated and difficult, and improves measurement accuracy by reducing distortion during processing. It is an object of the present invention to provide a Coriolis flowmeter using a parallel double curved tube.

[0010]

In the Coriolis flowmeter of the present invention, flow tubes 1 and 2 for vibrating and detecting a Coriolis force based thereon are constituted by two parallel curved tubes of arbitrary shapes. It is assumed that a so-called loop type in which a measurement fluid flows in series in the two flow tubes 1 and 2. In order to constitute such flow tubes 1 and 2 flowing in series, the Coriolis flowmeter of the present invention comprises a manifold 3 in which an inlet channel 4, an outlet channel 6 and an interconnecting channel 5 are formed. Have. The inlet channel 4 of the manifold 3 connects an inlet pipe through which the measurement fluid flows and one end of one of the flow tubes 2. The interconnection flow path 5 connects the other end of the one flow tube 2 and one end of the other flow tube 1 via the interconnection flow path 5. And the outlet channel 6
Connects the other end of the other flow tube 1 to an outlet pipe through which the measurement fluid flows out.

The connection between the inlet pipe and the outlet pipe and the inlet flow path 4 and the outlet flow path 6 of the manifold 3 can be made directly, but via flanges 7 and 8 fixed to the manifold 3. Alternatively, it can be carried out via connecting pipes 9, 10 fixed to the manifold 3 and flanges 7, 8 connected thereto.

As described above, the Coriolis flowmeter 2 of the present invention
The flow tubes 1 and 2 have a loop-shaped flow path so that a measurement fluid flows in series by three flow paths 4, 5 and 6 formed inside the manifold 3 without excessive bending. Can be configured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a Coriolis flowmeter as a premise of the present invention will be described with reference to FIG. 2 showing an external view of a general parallel double U-tube type Coriolis flowmeter. The present invention is characterized by an internal configuration of a manifold 3 described later, and in other configurations, the configuration can be the same as a general Coriolis flow meter as exemplified.

In the figures, 1 and 2 are flow tubes,
3 is a manifold, 7 and 8 are flanges, 11 and 1
2 is a vibration detection sensor, 13 and 14 are supports, and 16 is a vibrator. In the flow tubes 1 and 2 having the two parallel U-shaped tubes, the measurement fluid flows in the same direction as in the conventional configuration. However, the flow is not caused by the branch and the junction formed inside the manifold 3. As described below, the unique manifold internal configuration of the present invention is based on virtually one loop-shaped flow path formed in series.

The measurement of the flow rate of the Coriolis flow meter thus constructed is performed as usual. The supports 13 and 14 for obtaining a stable vibration are attached, and the vibrator 16 provided at the central portion of the flow tubes 1 and 2 causes one of the flow tubes to be in the opposite phase to the other so that the flow tubes 1 and Resonance drive is performed in a direction perpendicular to the plane where 2 exists. And the phase difference due to Coriolis force based on it,
It is detected by a pair of vibration detection sensors 11 and 12 provided between the fixed ends of the flow tubes 1 and 2 and the central portion, respectively.

That is, when a vibration is applied from a vibrator 16 installed at the center in a state where the measurement fluid is flowing through the flow tubes 1 and 2, the flow tube is formed in a first-order mode shape in which the center has the maximum amplitude. Vibrate. When this vibration is considered on the upstream side and the downstream side of the flow tubes 1 and 2, it can be considered that each of the vibrations is rotating around the vicinity of the fixed end. Therefore, the mass m and the angular velocity “ ω ”, and the flow velocity of the measurement fluid“ V ”(hereinafter, the symbol enclosed by“ ”represents a vector quantity), the Coriolis force of Fc = −2 m ·“ ω ”·“ V ”acts.

Due to this Coriolis force, a vibration mode in which the bending vibration is symmetrical at the upstream portion and the downstream portion with respect to the center point of the flow tubes 1 and 2 is generated. Actually, the flow tubes 1 and 2 vibrate in a form in which the two types of vibration patterns are superimposed. By measuring this deformation with the vibration detection sensors 11 and 12, the mass flow rate Q can be known.

FIG. 1 is a block diagram showing the principle of a Coriolis flowmeter to which the present invention is applied. In the figures, 1 and 2 are flow tubes, 3 is a manifold, 4 is an inlet channel formed on the inlet side of the manifold 3, and 5 is an interconnecting channel for connecting two flow tubes 1 and 2 in series. , 6 are outlet channels formed on the outlet side of the manifold 3, and 9 and 10 are connecting pipes provided on the inlet side and the outlet side, respectively.

The flanges 7 and 8 connect the inlet pipe and the outlet pipe (not shown) to one ends of the connecting pipes 9 and 10, respectively. The other end of the connection pipe 9 on the inlet side is fixed to the manifold 3 using an appropriate means such as welding so as to communicate with the inlet flow path 4 in the manifold 3. Similarly, the connection pipe 10 on the outlet side is fixed to the manifold 3 so as to communicate with the outlet flow path 6 in the manifold 3. In the illustrated example, when connecting the inlet pipe and the outlet pipe to the manifold 3, the connection pipes 9, 10 and the flanges 7, 8 connected thereto are used, but the inlet pipe and the outlet pipe are directly connected to the manifold. It is also possible. Alternatively, a flange is directly fixed to each of the inlet flow path side and the outlet flow path side of the manifold 3 (in other words, the function of the connection pipe is integrated into the manifold 3 as shown in FIG. 2), and the inlet pipe and the outlet are connected to this flange. Each pipe can be connected.

Therefore, in the present specification, the connection between the inlet pipe and the outlet pipe and the manifold is not limited to the case where the pipe is directly connected, but also the connection pipes 9 and 10 and the flanges 7 and 8.
Is used in the meaning including the case where the connection is made via one or both of the above.

Inlet channel 4 formed in manifold 3
The other end is the inlet end of the flow tube 2, the outlet end of the flow tube 2 is connected to one end of an interconnecting channel 5 formed in the manifold 3, and the other end of the interconnecting channel 5 is connected to the inlet of the flow tube 1. At its end, its outlet end is connected to one end of an outlet channel 6 formed in the manifold 3 by using an appropriate means such as welding. The other end of the outlet channel 6
In the example shown, it is connected to a connecting pipe 10, which is connected to the outlet pipe via the flange 8 as described above. Although a flange is used in the description, any type of joint such as a screw-in type or a clamp type may be used.

The measurement fluid flows from the inlet pipe connected by the flange 7 to the connection pipe 9, the inlet channel 4 of the manifold 3, the flow tube 2, the interconnecting channel 5, the flow tube 1, the outlet channel 6, Pass through tube 10 in this order,
It will flow out to the outlet pipe connected to the flange 8. In the present invention, it is not necessary to complicately curve the flow tube as described above, and the flow path configuration formed in the manifold 3 can form one continuous flow path having the same diameter without branching or merging. it can.

The material of the manifold 3 and the flow tubes 1 and 2 is stainless steel, Hastelloy,
Conventional ones in this technical field such as titanium alloys can be used. In this specification, the term “manifold” is used to refer to “JI edited by the Japan Standards Association.
As described in the S Technical Dictionary (4th edition), "a block that forms a passage serving as a pipe inside and has a connection port for attaching two or more devices to the outside"
Is used in the sense of

The manifold 3 can be formed integrally by casting, or can be divided and cast, and then joined together by welding or the like. Alternatively, after the channels 4, 5, and 6 are divided and machined, they can be integrally joined by welding or the like.

In the present invention, the flow tube is not limited to the above-mentioned U-shaped tube, but may be a curved tube having an arbitrary shape such as a circular shape or a portal shape, and may have an arbitrary configuration as a vibrator and a vibration detection sensor. The present invention can be applied to a Coriolis flowmeter that uses the same.

[0026]

According to the Coriolis flowmeter of the present invention, the inlet flow path, the outlet flow path, and the interconnection are used when the measurement fluid flows in series in the flow tube formed by the two parallel curved tubes. Since the flow path is performed by the manifold formed inside, the flow tube is complicated and there is no need to perform difficult processing.In addition, the measurement flow path is configured in series, there is no branch part, no junction Therefore, there is an effect that no pressure loss occurs and no fluid clogging occurs.

Further, since there is no branch in the flow path and the flow path is configured as if it were a single continuous tube, it is possible to push the pig and to improve the cleaning property. Even if the temperature of the measurement fluid fluctuates, the temperature fluctuation is transmitted uniformly to the flow tube, the temperature distribution becomes uniform, and there is an effect that no distortion is generated due to the temperature distribution.

In addition, it is possible to easily align the center of the inlet pipe with the center of the outlet pipe only by arranging the flow path of the manifold, thereby facilitating the installation of the Coriolis flowmeter in the pipe.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a Coriolis flowmeter to which the present invention is applied.

FIG. 2 shows an external view of a general parallel double U-tube type Coriolis flowmeter as a premise of the present invention.

FIG. 3 shows a conceptual diagram of a conventional parallel-bend tube type Coriolis flowmeter.

FIG. 4 shows a conceptual diagram of a loop type Coriolis flowmeter in which a single tube is bent to form a series configuration in the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Flow tube 3 Manifold 4 Inlet flow path 5 Interconnect flow path 6 Outlet flow path 7, 8 Flange 9, 10 Connection pipe 11, 12 Vibration detection sensor 13, 14 Support 16 Shaker

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[Procedure amendment]

[Submission date] January 29, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Seiji Kobayashi Oval Co., Ltd. 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo

Claims (4)

[Claims] A flow tube for exciting and detecting a Coriolis force based thereon is constituted by two parallel curved tubes, and a Coriolis flow meter through which a measurement fluid flows in series in the two flow tubes. In the above, an inlet pipe into which the measurement fluid flows, an outlet pipe from which the measurement fluid flows out, and a manifold in which two flow tubes are connected to each other to form a series flow path are provided. Features a Coriolis flowmeter. 2. A Coriolis flowmeter for vibrating and detecting a Coriolis force based thereon based on two parallel curved tubes, through which a measurement fluid flows in series within the two flow tubes. In, the inlet pipe into which the measurement fluid flows in, the outlet pipe from which the measurement fluid flows out, and the two flow tubes are interconnected to form a series flow path, so that an inlet flow path, an outlet flow path, and A manifold having an interconnecting passage formed therein; the inlet passage connects an inlet pipe to one end thereof, and connects one end of one of the flow tubes to the other end thereof; The other end of the one flow tube is connected to one end of the other flow tube, and the other end of the other flow tube is connected to the other end of the flow passage. A Coriolis flowmeter, wherein the other end of the tube is connected and an outlet pipe is connected to the other end. 3. The Coriolis flowmeter according to claim 2, wherein the connection between the inlet pipe and the outlet pipe, and the inlet flow path and the outlet flow path of the manifold is performed through a joint. 4. The connection between the inlet pipe and the outlet pipe, and the inlet flow path and the outlet flow path of the manifold, respectively, includes a connecting pipe connected to the inlet flow path and the outlet flow path, respectively, and a connecting pipe. 3. The Coriolis flowmeter according to claim 2, wherein the flow measurement is performed through a connected joint.