JPH06207840A - Vortex flowmeter - Google Patents

Abstract

PURPOSE:To detect plugging of a gap between a nozzle and a force receiving body (vortex production body) in simple constitution by calculating a square of output/measured flow speed of plugging piezoelectric elements at a specified time and comparing it with a constant of a storing means. CONSTITUTION:Piezoelectric elements 36, 37 are inserted into a recess part 35 axially provided on a vortex production body 33 at an end side of the vortex production body 33, fixed thereon and a constant K=a square of output/ measured flow speed of the elements 36 at the time when a vortex flowmeter is set is stored to a storing means 41. In order to detect plugging of a gap between a nozzle 31 and the vortex production body 33, at a specified time, for instant, at the time of periodic repair a value of the square of the output/ measured flow speed of the element is calculated with CPU 42, compared it with the constant K stored in the storing means 41, when its difference exceeds a specified value (a value determined in consideration of some degree of a margin for the constant K), it is judged that plugging such as dust produces in the gap 34 between the nozzle 31 and the vortex production body 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex flowmeter capable of detecting clogging of a gap between a nozzle of a pipe and a force receiver due to dust or the like.

[0002]

2. Description of the Related Art FIG. 2 is a structural explanatory view of a conventional example which has been generally used, for example, Japanese Patent Application Laid-Open No. 3-02061.
No. 8 (Japanese Patent Application No. 1-033256). 1
Reference numeral 0 is a pipe through which the fluid flows, and 11 is a cylindrical nozzle provided at a right angle to the pipe 10.

Reference numeral 12 is a pipe line 1 with a distance from the nozzle 11.
It is a columnar vortex generator having a trapezoidal cross section that is inserted at a right angle to 0, and one end thereof is supported by a pipe 13 by a screw 13,
The other end is fixed to the nozzle 11 with a flange 14 by screws or welding. Reference numeral 15 denotes a concave portion provided on the flange portion 14 side of the vortex generator 12.

Inside the recess 15, metal first common electrode 16, piezoelectric element 17 and electrode plate 1 are arranged in this order from the bottom.
8, the insulating plate 19, the electrode plate 20, and the piezoelectric element 21 are arranged in a sandwich shape, and these are pressed and fixed by a metal pressing rod 22. Further, from the electrode plate 18, the lead wire 2
3, lead wires 24 from the electrode plate 20 are terminals A,
B has been pulled out.

The piezoelectric elements 17 and 21 are the piezoelectric elements 17 and 2, respectively.
The left side and the right side of FIG. 1 are polarized in opposite directions, and charges of opposite polarities are generated in the upper and lower electrodes with respect to stress in the same direction.

The electric charge generated in the piezoelectric element 17 is applied to the electrode plate 18
The electric charge generated between the terminal A connected to and the conduit 10 connected via the pedestal 16 and generated in the piezoelectric element 21 was connected to the terminal B connected to the electrode plate 20 and the pressing rod 20. It is obtained between the pipe 10 and the pipe 10.

The charges generated on the two electrode plates 18 and 20 are input to charge amplifiers 25 and 26 as shown in FIG. The output of the charge amplifier 25 and the output of the charge amplifier 26 are added to the output via the volume 27 by the adder 28 to obtain a flow rate signal. This flow rate signal is converted into, for example, a current output and transmitted to the load via the two wires (not shown). next,
The operation of the vortex flowmeter configured as above will be described with reference to FIGS. 4 and 5.

When the fluid flows into the conduit 10, the vortex generator 1
The vibration due to the Karman vortex occurs in the direction indicated by arrow F in FIG. This vibration causes the vortex generator 12 to repeat a stress distribution as shown in FIG.
Charges + Q and −Q corresponding to the signal stress having the vortex frequency shown in FIG. 4A are repeated in each piezoelectric element 17 and 21. In FIG. 4, the electrode plate 18 is illustrated for convenience of explanation.
Alternatively, 21 is divided into two parts to the left and right with respect to the paper surface, and one of the upper and lower electrodes corresponds to the pedestal 16 or the pressing rod 22.

On the other hand, in the pipeline 10, pipeline vibration that causes noise is also generated. This pipeline vibration is divided into a drag force direction that is the same as the fluid flow direction, a lift force direction that is perpendicular to the fluid flow direction, and a longitudinal component of the vortex generator. this house,
The stress distribution with respect to the vibration in the drag direction is as shown in FIG. 9 (b), and positive and negative charges are canceled out within one electrode, and noise charges are not generated. Further, as to the vibration in the longitudinal direction, as shown in FIG. 4 (c), it is canceled in the electrode and no noise charge is generated as in the drag direction.

However, the vibration in the lift direction has the same stress distribution as the signal stress, and noise charge is generated. Therefore, the following calculation is executed in order to erase this noise charge. The charges of the piezoelectric elements 17 and 21 are Q ₁ and Q ₂ , the signal component is S ₁ ,
If S ₂ and the noise components in the lift direction are N ₁ and N _2, and the polarization is reversed in the piezoelectric elements 17 and 21, Q ₁ and Q ₂ are represented by the following equations. _{Q 1 = S 1 + N 1} -Q 2 = -S 2 -N 2

However, the vector directions of S ₁ and S ₂ , and N ₁ and N ₂ are the same. Here, the relationship between the signal component and the noise component of the piezoelectric elements 17 and 21 is shown in FIG. 5 (this figure shows the relationship between the noise in the lift direction and the bending moment of the vortex generator with respect to the signal). Therefore, as shown in FIG. 7, when the output of the charge amplifier 25 on the piezoelectric element 17 side is added by the adder 28, it is multiplied by N ₁ / N ₂ together with the volume 27 and added to the output of the charge amplifier 26 on the piezoelectric element 21 side. Then, Q ₁ −Q ₂ (N ₁ / N ₂ ) = S ₁ −S ₂ (N ₁ / N ₂ ), and the pipeline noise is removed.

The first common electrode 16, the piezoelectric element 17, the electrode plate 18, the insulating plate 19, the electrode plate 20, and the piezoelectric element 21 are pressed and fixed in the recess 15 by the pressing rod 22.
Here, the vortex generator 12, the first common electrode 16, the piezoelectric element 1
7, electrode plate 18, insulating plate 19, electrode plate 20, piezoelectric element 2
1. If the temperature expansion of the pressing rod 22 is made equal, the initial pressing force does not change even if the measured fluid temperature changes, so there is no problem.

[0013]

However, in such a device, the clogging due to dust or the like in the gap between the nozzle 11 and the force receiving body 12 in the conduit reduces the measurement signal.
When the vortex generator 12 was pulled out from the conduit 10, the S / N ratio became poor and measurement became impossible. Until now, the predictive diagnosis of clogging has not been possible.

The occurrence of clogging due to dust or the like in the gap between the nozzle 11 of the conduit and the force receiving member 12 has gradually become a problem as the fields in which the vortex flowmeter is used expands. Today, there is a demand for predictive diagnosis of clogging. The present invention solves this problem. An object of the present invention is to provide a vortex flowmeter capable of detecting clogging due to dust or the like in a gap between a nozzle of a pipeline and a force receiving body.

[0015]

In order to achieve this object, the present invention is directed to a nozzle provided in a pipe line, and a highly rigid columnar force receiving member inserted in the nozzle with a gap. A vortex for measuring the flow rate by detecting an alternating force acting on the force receiving body by a Karman vortex, which has a concave portion axially provided on one end side of the force receiving body and a piezoelectric element inserted and fixed in the concave portion. In the flowmeter, memory means for storing a constant K such that the output of the piezoelectric element at the time of installation of the device / square of measured flow velocity = K
The square of the output of the piezoelectric element / measured flow velocity is calculated at a predetermined time and compared with the K of the memory means. If the difference exceeds a predetermined value, it is determined that the gap between the nozzle and the force receiving body is clogged. The vortex flowmeter is characterized by comprising a CPU for judging.

[0016]

In the above construction, the square of the output of the clogging detection piezoelectric element / the square of the measured flow velocity is calculated at a predetermined time, and compared with the value of K in the memory means. CP that judges that the gap with the force body is clogged
Since U is provided, clogging of the gap between the nozzle and the force receiver can be detected. Hereinafter, detailed description will be given based on examples.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential structure of an embodiment of the present invention. Reference numeral 31 is a nozzle provided in the conduit 32. Three
Reference numeral 3 denotes a highly rigid columnar vortex generator inserted in the nozzle 31 with a gap 34.

Reference numeral 35 is a recess provided axially on one end side of the vortex generator 33. 36 and 37 are piezoelectric elements inserted and fixed in the recess 35. Reference numeral 41 is a memory means for storing a constant K such that the output of the piezoelectric element 36 / the square of the measured flow velocity = K when the vortex flowmeter is installed.

Reference numeral 42 denotes an output of the piezoelectric element 36 at a predetermined time.
A CPU that calculates the square of the measured flow velocity, compares it with K in the memory means 41, and judges that the gap between the nozzle 31 and the vortex generator 33 is clogged when the difference exceeds a predetermined value.
Is.

In the above structure, the flow velocity and flow rate are measured by
It is measured in the same manner as the conventional example. On the other hand, to detect the clogging of the gap between the nozzle and the force receiving body, first, when the vortex generator 33 is installed, the output of the piezoelectric element 41 / the square of the measured flow velocity = K, a constant K, is stored in the memory means 41. Next, CPU4
2, the square of the output / measured flow velocity of the output piezoelectric element 36 is calculated at a predetermined time, for example, at the time of periodic repair, and when the difference exceeds K of the memory means 41 and exceeds the predetermined value A,
It is determined that the gap 34 between the nozzle 31 and the vortex generator 33 is clogged. The predetermined value A is determined in consideration of the constant K and some margin.

As a result, at a predetermined time, the square of the output of the piezoelectric element 36 / measured flow velocity is calculated and compared with K of the memory means 41, and when the difference exceeds a predetermined value A, the nozzle 31 and the vortex generator are generated. Since the CPU 423 for determining that the gap 34 with the CPU 33 is clogged is provided,

(1) It is possible to monitor the clogging of dust in the gap 34 with a simple structure. (2) The monitor makes it possible to clarify the setting of the repair / replacement cycle and reduce the number of repair / replacement steps.

(3) Presence / absence, amount, type, etc. of dust and dust in the plant can be checked, and self-diagnosis and life diagnosis of the plant can be performed. (4) Since the piezoelectric element 36 for measurement is used, it is not necessary to separately provide a piezoelectric element, the structure is simple, and the cost can be reduced. Incidentally, in the above-mentioned embodiment, the memory means 41 and the CP
Although U42 is described as being connected to the piezoelectric element 36, it is not limited to this, and may be connected only to the piezoelectric element 37, or may be connected to both the piezoelectric element 36 and the piezoelectric element 37 at the same time. May be.

[0024]

As described above, according to the present invention, the nozzle provided in the conduit, the columnar force receiving member having a high rigidity inserted in the nozzle with a gap maintained, and one end of the force receiving member. In a vortex flowmeter for measuring a flow rate by detecting an alternating force acting on a force receiving body by a Karman vortex, the vortex flowmeter including a concave portion axially provided on the side and a piezoelectric element inserted and fixed in the concave portion, Memory means for storing a constant K such that output of the piezoelectric element / square of measured flow velocity = K when installed, and square of output / measured flow velocity of the piezoelectric element at a predetermined time are calculated and compared with K of the memory means. When the difference exceeds a predetermined value, it is determined that the gap between the nozzle and the force receiving body is clogged.
A vortex flowmeter characterized by including a PU was constructed.

As a result, the square of the output of the clogging detection piezoelectric element / the square of the measured flow velocity is calculated at a predetermined time, and compared with K of the memory means, and when the difference exceeds a predetermined value, the nozzle and the vortex generator are separated. Since the CPU that determines that the gap has been clogged is provided, (1) it is possible to monitor the clogging state of dust in the gap with a simple configuration. (2) The monitor makes it possible to clarify the setting of the repair / replacement cycle and reduce the number of repair / replacement steps.

(3) Presence / absence, amount, type, etc. of dust and dust in the plant can be checked, and self-diagnosis, life diagnosis, etc. of the plant can be performed. (4) Since the piezoelectric element for measurement is used, it is not necessary to separately provide a piezoelectric element, the structure is simple, and the cost can be reduced.

Therefore, according to the present invention, it is possible to realize an inexpensive vortex flowmeter capable of detecting clogging due to dust in the gap between the nozzle of the conduit and the force receiving body.

[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 explanatory diagram of a configuration of a conventional example that is generally used in the past.

FIG. 3 is a block diagram showing a configuration of a conversion unit that converts charges detected by the detection unit shown in FIG. 2 into a voltage.

FIG. 4 is an operation explanatory diagram of FIG. 2;

5 is an operation explanatory diagram of FIG. 2;

[Explanation of symbols]

 13 ... screw 14 ... flange 16 ... first common electrode 18 ... electrode plate 19 ... insulating plate 20 ... electrode plate 22 ... pressing bar 23 ... lead wire 24 ... lead wire 25 ... charge amplifier 26 ... charge amplifier 27 ... Volume 28 ... Adder 31 ... Nozzle 32 ... Pipeline 33 ... Vortex generator 34 ... Gap 35 ... Recess 36 ... Piezoelectric element 41 ... Memory means 42 ... CPU

Claims (1)

[Claims] 1. A nozzle provided in a pipe line, a highly rigid columnar force receiving body inserted in the nozzle with a gap maintained, and a recess provided in one end side of the force receiving body in the axial direction. A vortex flowmeter which comprises a piezoelectric element inserted and fixed in the recess and measures the flow rate by detecting an alternating force acting on a force receiving body by a Karman vortex, the output / measurement of the piezoelectric element when the device is installed. Square of velocity =
Memory means for storing a constant K, K, and the nozzle when the square of output / measured flow velocity of the piezoelectric element is calculated at a predetermined time and compared with the constant K of the memory means and the difference exceeds a predetermined value. A vortex flowmeter, comprising: a CPU that determines that clogging has occurred in a gap between the force receiving body.