JPH02262019A - Mass flowmeter - Google Patents

Abstract

PURPOSE:To detect the abnormal vibration of a pipe, to prevent breakdown and to decrease erroneous measurements by detecting voltages which are generated in correspondence with the amplitudes of the vibrations of the pipes imparted by an exciting means, and comparing the voltage values. CONSTITUTION:Voltages which are generated with first and second exciting means are detected with a first absolute-value circuit 1 and a second absolute circuit 2. Thus the amplitudes of first and second pipes (sensor tubes) are detected. A threshold value is set with a threshold setting circuit 3 in correspondence with the detected signal of the first absolute value circuit 1. The threshold value is compared with the output signal of the second absolute value circuit 2 in a window comparator 4. When the amplitude is changed from the value at the normal time, the threshold value or the output detected signal of the second absolute value circuit 2 is changed. Abnormality is detected based on the relationship, and the vibration is stopped. Therefore, breakdown of the pipes can be prevented, and the reading of the erroneously measured value is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to flowmeters, and more particularly to mass flowmeters that utilize the Coriolis force to measure the mass flow rate of a fluid.

BACKGROUND OF THE INVENTION It is desirable that the F amount of a conventional fluid be expressed in terms of mass, which is not influenced by the type of fluid, physical properties (density, viscosity, etc.), and process conditions (temperature, pressure). As the mass flow range for measuring the mass flow (6) of the fluid, for example, the volumetric flow rate S1 of the fluid is measured 4 times, and this measurement value is converted into a mass flow rate of 1 m.
Directly measure the mass flow l of the fluid with the contact type "Fim flow meter bar 1",
There is a direct type mass flowmeter that can measure indirect type Pil flow hanging flow with high accuracy.

As this direct type flow rate 4, there is a type in which the fluid is caused to flow through a vibrating sensor sub 1-b, and the Coriolis force generated at this time is used to directly measure the flow rate.

BACKGROUND ART In this type of Coriolis mass flow ff1Rf, for example, as described in Japanese Patent Laid-Open No. 54-4168, fluid is caused to flow through a pair of O-shaped sensor tubes, and the pair of sensor tubes are connected to each other. Vibrate in the direction of proximity and distance. Since the Coriolis force acts in the vibration direction of each sensor sub 1-b and is in opposite directions on the input side and the outlet side, the sensor sub 1-b twists, and this twist angle is proportional to the mass flow rate. Therefore, a sensor for detecting the change (Q) of the sensor sub V-7 based on the twist is provided at the twisting position of the inlet side and the outlet of the pair of sensor tubes, and the time difference between the output detection signals of both sensors is measured. The torsion of the sensor sub 1-b, that is, the mass flow ω is measured.

Problems to be Solved by the Invention However, the conventional mass flow ΦJ1 uses a pair of sensor tubes in a resonant state, and if one of the pair of sensor tubes becomes clogged and the fluid stops flowing or is damaged, etc. If one sensor tube stops vibrating due to an abnormality in the fluid flow, abnormal vibrations will occur, such as doubling the vibration amplitude of the other tube. There were problems such as damage to the 1-b.

The present invention has been made in view of the above points, and an object of the present invention is to provide a quality flow meter that detects abnormality when abnormal vibration occurs in the sensor tube and prevents damage to the sensor tube.

Means for Solving the Problems The present invention provides a first pipe line vibrated by a first excitation means;
A Coriolis force generated by flowing fluid through the first excitation means and a second conduit vibrated by a synchronized second excitation means deforms the first and second conduits, and Relative vibrations between the first and second pipes are detected on the inflow and outflow sides of the first and second pipes, respectively, and the time difference between the detected signals determines the temperature of the fluid. In the quality ω flowmeter for measuring the flow rate of suspended flow, the first excitation means includes a first detection circuit for detecting electric current generated by vibration of the first pipe line, and the second excitation means includes a first detection circuit for detecting electric current generated by vibration of the first pipe line. a second detection circuit that detects FsVr generated in response to the vibration of the second conduit; a threshold setting circuit that sets two thresholds according to the output detection signal of the first detection circuit; It is equipped with a comparison circuit that compares the output detection signal of the circuit with two P8Ifi set by the Moeki area value setting circuit and outputs a signal according to the relative relationship.

Furthermore, the apparatus further includes vibration stopping means for stopping the vibrations of the first and second conduits when the output signal of the comparison circuit is a signal in a vibration state different from a normal state.

Operation The first and second pipes vibrate with the same amplitude under normal conditions, but when an abnormality occurs in either of the first or second pipes, the amplitude changes. A change in amplitude causes a change in the voltages produced in the first and second excitation means that vibrate the first and second conduits. Therefore, the electric current r generated in the first and second excitation means by the first and second detection circuits is
, f, the amplitudes of the first and second pipes can be detected. Further, a threshold setting circuit sets a threshold according to the output detection signal of the first detection circuit, and a comparison circuit compares this threshold with the output detection signal of the second detection circuit. If the amplitude changes from normal, the threshold value or the output detection signal of the second detection circuit will change, so the relationship between these changes and an abnormality can be detected.

Embodiment FIG. 1 shows a block diagram of a mass flowmeter according to an embodiment of the present invention. In the figure, 1 is a first absolute value circuit which is a first detection circuit, 2 is a second absolute value circuit which is a second detection circuit,
3 is a comparison circuit, and 4 is a comparison circuit, which is a window comparator.

The quality fM f according to the present embodiment explained with reference to FIG.
The structure of i ffi Xi will be explained using FIGS. 3 to 5. Figure 3 shows quality P15 flow rate 1 according to this example.
FIGS. 4(A) and 4(B) are a plan view and a front view of the mass flowmeter according to the present embodiment, and FIG. 5(A) is a perspective view of FIG.

(B) is the mass flow rate x-x' and Y- according to this example.
A Y' sectional view is shown.

The mass flow ff1il is made up of a pair of sensor ribs 1-b9 and 10 assembled in the manifold 11 (-j). Fig. 4 (△)
, <B), the manifold 11 is installed between the inflow pipe 12 and the outflow pipe 13, and has an inflow passage 11a connected to the inflow pipe 12 and an outflow passage 11b connected to the outflow pipe 13.
to the right. Further, as shown in FIG. 5, the inflow passage 11a communicates with connection ports 11 and 11a2 that branch left and right with respect to the flow direction.

In addition, as shown in FIGS. 4 and 5, the outflow path 11bt
3 inlet channel 11a and connection port 11b1.1 branched into 1]
It communicates with 1b2.

The sensor probe 9 on the left side with respect to the flow direction is connected to the connection port 118 of the inflow path 11a. The straight pipe portion 9a, which is connected to the straight pipe portion 9a and extends in the piping direction, and the connection port 116. of the outflow path 11b. A straight pipe part 9b connected to the straight pipe part 9a and extending parallel to the straight pipe part 9a, curved parts 9c and 9d bent back at the tips of the straight pipe parts 9a and 9b, and these curved parts 9C and 9d. tangent f-0
It consists of a letter-shaped connecting portion 9e.

In addition, the sensor sensor 1-710 on the right side with respect to the flow direction is formed in the same shape as the sensor sensor 1-71 described above, and has a straight pipe portion 10a,
10b is disposed symmetrically to the left and right sides of the central tube 9 via the outflow pipe 13 so that the straight pipe portions 9a and 9b are parallel to each other. In addition, the connection part 91 of the sensor sub-up 9.10
3.108 is fixed to single-shaped brackets 14a and 14b fixed to a ring 14C having a gap around the outflow pipe 13 and the outflow pipe 13.

A straight pipe portion 9a of a pair of Senrib l-bubs 9 and 10.

9b, 10a, 10b pass through the support plate 15, and the support plate 1
5 by welding, and its ends are connected to each connection port 11a1.11,2゜1 Tol, 1 of the manifold 11.
It is connected and fixed to 1b2.

Therefore, at the n0 flow rate δI, the sensor sensor 1-79°10 is installed near the outflow pipe 13 so as to extend in the piping direction, making it less susceptible to the effects of piping vibration, and controlling the flow rate with better viscosity. Can be measured.

Note that a hole 15a is formed in the center of the support plate 15 with an r! 1, and the outflow pipe 13 passes through this hole 15a.

As shown in FIGS. 3, 4, and 5, the straight pipe section 9 on the inflow side
Pick-ups 16 and 17 are arranged between a and 108 and between straight pipe sections 9b and 10b on the outflow side. Straight pipe parts 10a, 10b where the coil part is on the right side with respect to the flow direction
The magnet portion facing the end face of the coil portion is fixed to the straight pipe portions 9a and 9b on the left side with respect to the flow IJ'' direction.

Reference numeral 18 and 19 denote vibrating arms, which are provided between the tips of the straight tube sections 9a and 9b and between the tips of the straight tube sections 10a and 10b.

The vibrator 18.19 has a similar configuration to an electromagnetic solenoid, and includes coil parts 18a, 19a and magnet parts 18b, 1.
9b, and the coil part 18a has a magnet part 18.
b is inserted into the coil portion 19b, and the magnet portion 19b is inserted into the coil portion 19b.
is inserted. ] By repeatedly applying current to the coil parts 18a, 19a, an attractive or repulsive force is generated between the coil parts 18a, 19a and the magnet parts 18b, 19b, and vibration is performed.

The tJn vibrator 18 has a coil part 18a fixed to the outflow side 9b of the sensana 1-19, and a straight pipe part 9a on the inflow side.
A magnet ff1l 8b is fixed to and vibrates in the direction of bringing the straight pipe portion 9a and the straight pipe portion 9b closer to each other and separating them from each other.

Further, in the vibration exciter 19, a coil part 19a is fixed to the straight pipe part 10a on the inflow side of the sensor chi 1-110, a magnet PIS 19b is fixed to the straight pipe part 10b on the outflow side, and the straight pipe part 10a and the straight pipe part 10b are fixed to the straight pipe part 10b on the outflow side. Vibration is applied in the direction of approaching and separating.

In addition, at this time, sensor tube 1 and sensor tube 1
0, when the sensor probe 1-79 is close to each other, the sensor tube 10 is moved away, and when the sensor probe 1-79 is spaced m apart, the sensor tube 1-79 is vibrated so that it approaches. .

l fi 54 At the time of measurement, a pair of center pipes 9.10 are vibrated with fluid flowing inside 3, inflow pipe 1
The fluid to be measured that has flowed into the inflow path 11a of the manifold 11 from 2 is divided into straight pipe portions 9 of sensor data 1-79°10.
a, flows into 10a and bends 9C.

It passes through the 10C2 connecting parts 9e and 10e, the curved parts 9d and 10d, reaches the straight pipe parts 9b and 10b, merges at the outflow path 11b of the manifold 11, and flows out from the outflow pipe 13. Also, the sensor rib 9.10 is excited by the vibrator 18.19, and the spring constant of the sensor rib 1-b 9.10 and the sensor rib 1-
The tubes 9 and 10 vibrate at a natural frequency determined by the mass of the fluid within them.

Therefore, when fluid passes through the vibrating tubes 9 and 10, a Frioli force is generated and the straight tube portions 9a, 9b, 1
Coriolis causes displacement at 0a and 10b. The pair of sensor duplexes 1-19 and 10 are excited with a phase difference of approximately 180 degrees. For example, when the straight pipe parts 9a and 9b of the upper sensor duplex 9 are separated, the lower sensor duplex 1-10 is excited. The straight pipe portions 10a and 10b are close to each other.

That is, when the sensor duplex 1-9 is displaced as shown in FIGS. 6(A) and ([3), the sensor duplex 10 is displaced as shown in FIGS. 6(C) and (D).

Therefore, as shown in FIG. 7(A), ([3> Straight pipe part 10a of Kachi l-110.

Coriolis as shown in FIGS. 7(C) and 7(D) occurs in 10b.

The pickups 16 and 17 detect the relative displacement of the vibrating sensor sensors 9 and 10, respectively, as shown in FIG. Then, based on the signals from the pickups 16 and 17, the sensor sensor 1
- The mass flow rate of the fluid flowing in the pipes 9, 10 is determined. At a mass flow rate of 4, the relative displacement of the straight pipe sections 9a, 10a and 9b, 10b due to Coriolis generated in the sensor tube 9.10 is doubled and can be detected, and the flow rate can be measured with high accuracy.

In addition, Sensana 1-19 due to the outbreak of Coriolica.
When detecting a phase difference of 10, even if external vibration (1f! dynamic noise) is input, it is canceled out and the outflow can be stably performed without being affected by external vibration.

In FIG. 1, the coil section 188. of the vibrator 18.19 is shown.
198 are connected in series and current is supplied from the drive circuit 8 1, the drive circuit 8 is the pickup 16.17
Detects the vibration of the sensor 1-10 by applying a current to the coil section 18 such that the maximum amplitude becomes a constant value.
8.19a.

The first absolute value circuit 1 includes a coil section 18a and a drive circuit 8.
It detects 1 voltage at the connection point and outputs the maximum value or average value of that voltage. The second absolute value circuit 2 has a coil section 1
The voltage at the connection point between 8a and the coil portion 19a is detected, and the maximum value or average value of the voltage is output.

The output detection voltage of the first absolute value circuit 1 is supplied to the first and second ratio setting circuits 6.7. First ratio setting circuit 6
outputs a voltage at a level of 52% of the output detection voltage from the first absolute value circuit 1. Further, the second ratio setting circuit 7 outputs a voltage at a level of 48% of the output detection voltage from the first absolute value circuit 2.

The output voltage of the first ratio setting circuit 6 is inputted to a terminal for setting the upper limit of the wind inverter 4, and the output voltage of the second ratio setting circuit 7 is inputted to the terminal for setting the upper limit of the wind inverter 4. Ru.

In addition, the input f8'F of the window comparator 4 has a second
The output voltage of the absolute value circuit 2 is inputted. As shown in FIG. 2, the window comparator 4 outputs a high level signal when the input terminal level is between a preset upper limit level and the 1-limit level, and below the T-limit level, and
Outputs a 1 or 0 level signal that is higher than the upper limit level.

The output signal of the window comparator 4 is supplied to the l packaging M5. Warning device f! F5 is configured to issue a warning with a lamp alarm sound or the like in response to the output signal of the window comparator 4.

Next, the operation will be explained 5. First, under normal conditions, the amplitudes of the sensor tubes 1-19, 10 are approximately the same, and the amplitudes of the sensor tubes 9, 10, . Pickup 16.1
7. Drive circuit 8. The loop formed by the vibrator 31.32 resonates at a natural frequency determined by the spring constant of the connecting portion of the Senrib 1-19.10.

Here, the voltage of the vibrator 1B, 19 is the coil part 18a,
Electric sweat fall due to resistance 19a and magnet part 18b
, 19b and the coil portion 18a.

19a, a voltage is generated according to the back electromotive force caused by Lenz's law. .

Since this back electromotive force is proportional to the relative speed of the coil parts 18a, 19a and the magnet parts 18b, 19b, the vibrator 18
If the amplitude of the vibration exciter 19 is the same as that of the vibrator 19, substantially equal reverse motive forces are generated in the coil portions 18a and 19a of the vibrator 18 and 19, respectively.

Then, the difference in back electromotive force is detected using the first absolute value circuit 1 and the second absolute value circuit 2.

Under normal conditions, approximately equal back electromotive force is generated in the coil section 18a and the coil section 19a, so 50% of the output detection voltage of the first absolute value circuit 1 is the output of the second absolute value circuit 2. This becomes the detection voltage. The upper and lower limit levels of the window comparator 4 are determined by the first and second comparison and setting circuits 6.7 to 48% of the output detection voltage of the first absolute value (b) path 1.
% and 52%, therefore, under normal conditions, the output detection voltage of the second absolute value circuit 2 is within this range, and the output of the window comparator 4 is at a high level. .

Therefore, when the output of the window comparator 4 is at a high level, the warning device 5 does not operate.

This electromotive force is detected by a first absolute value circuit 1 and a second absolute value circuit 2. Under normal conditions, this electromotive force is the first
50% of the output detection voltage of the absolute value circuit 1 becomes the output detection voltage of the second absolute value circuit 2, and the upper and lower limit levels of the window comparator 4 are determined by the first and second comparison setting circuits 6.7. 48 of the output detection voltage of the absolute value circuit 1 of 1
% and 52%, it is within this range under normal conditions, and the output J of the window comparator 4 is at a high level. When the output of the window comparator 4 is at a high level, the warning device 5 does not operate.

If bubbles get mixed into Senrib 1-B 9 or 10 of either -h or solid matter stagnates inside, the natural frequency changes and the vibration of Senrib 1-B 9 or 10 of either -h changes. stops or its amplitude decreases. However, since the drive circuit 8 increases the current supply to the coil parts 18a and 19a so as to keep the relative amplitude of the sensor tubes 1-19.10 constant, the amplitude of the sensor tube whose vibration has not stopped is increased. is twice as much as normal.

On the other hand, the coil parts 18a and 19a have Senrib 1-79,
Due to the vibration of 10, the magnet part 18b.

19b are close to each other and separated from each other, electromotive force due to electromagnetic induction is generated according to Lenz's law. This electromotive force is applied to the magnet sections 18b, 19b and the coil section 18a.

19a, so when the - side sensor tube 9 or 10 stops vibrating, the coil part 18a or 19a of the vibrator 18 or 19 of the stopped sensor tube 9 or 10 no electromotive force is generated.

Under normal conditions, both electromotive forces are equal, and 50% of the detected voltage of the first absolute value circuit 1 is applied to the second absolute value circuit 2.
However, if one of the sensor tubes 9 or 10 stops, the electromotive force of one of them disappears, so this relationship collapses, and the output detection voltage of the first absolute value circuit 1 The output detection voltage of the second absolute value circuit 2 no longer falls within the upper and lower limit levels set by , and the output of the inverter 4 becomes O- level.

When the output of the window comparator 4 becomes low level, the warning 1iff5 is activated to notify the administrator of the abnormality by flashing a lamp or issuing an alarm. If the administrator stops the meter using a warning from this lamp or the like, damage to the sensor tube can be avoided. It can also be seen that the current displayed value is incorrect.

In this embodiment, the warning device 5 is activated in accordance with the output of the window comparator 8, and only the lamp is turned on and the alarm sound is generated. However, as shown in FIG. Coil portions 18a and 19 accordingly.
The current supply to a is cut by a latching relay and π
A configuration may be adopted in which the operation of one device is stopped.

In addition, the configuration for stopping the operation of the meter is not limited to the above, but it may be stopped by turning off the power supply or drive circuit of the meter itself, or even by cutting the signals from the pickups 16 and 17. The drive circuit 8 may not be activated.

Effects of the Invention As described above, according to the present invention, abnormal vibrations occurring in the pipe can be detected by detecting the voltage generated in the excitation means according to the amplitude of the pipe and comparing these values. Features include eliminating the risk of damage to the pipeline due to abnormally vibrating pipes, and eliminating the possibility of reading erroneous measurement values in abnormally vibrating conditions. Ru.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram for explaining the operation of essential parts of an embodiment of the invention, and Figs. FIG. 8 is a block diagram of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...First absolute value circuit, 2...Second absolute value circuit, 3...m value setting circuit, 4...Window comparator. Patent applicant: Tokiko Co., Ltd. Patent attorney: Tadahiko Ito, patent attorney, Kaneyuki Matsuura Figure 1, Figure 6, Figure 7, Figure 2

Claims (2)

[Claims] (1) It is generated by flowing a fluid through a first pipe line vibrated by a first excitation means and a second pipe line vibrated by a second excitation means synchronized with the first excitation means. deforming the first and second conduits by Coriolis force;
Relative vibrations between the first pipe line and the second pipe line are detected on the inflow side and the outflow side of the first and second pipe lines, respectively, and the time difference between the detection signals is used to detect the flow of the fluid. In a mass flowmeter that measures an interrogation flow rate, the first excitation means includes a first detection circuit that detects a voltage generated in response to the vibration of the first pipe line, and the second excitation means includes a first detection circuit that detects a voltage generated in response to vibration of the first pipe line. a second detection circuit that detects a voltage generated in response to vibrations in the conduit; a threshold setting circuit that generates a threshold according to the output detection signal of the first detection circuit; and an output of the second detection circuit. a comparison circuit that compares the detection signal with a threshold value set by the threshold value setting circuit and outputs a signal according to the relative relationship; A mass flowmeter characterized by determining a vibration state. (2) vibration stopping means for stopping the vibration of the first and second pipes when the output signal of the comparison circuit is different from the output signal of the steady state vibration state of the first and second pipes; The mass flowmeter according to claim 1, further comprising: a mass flowmeter.