JP2002039820A - Mixing ratio measuring device and fluid mixing device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the mixing ratio of the mixture fluid of conductive fluid and insulating fluid at low cost and with high accuracy over the wide flow conditions. SOLUTION: This mixing ratio measuring device is equipped with a vortex generator generating Karman vortex 3; a pair of measuring electrodes 4a, 4b installed in positions downstream than the vortex generator and detecting the change of induced electromotive force generating when the Karman vortex 3 passes through a magnetic field; a pair of reference potential measuring electrodes 6a, 6b for measuring the potential difference which is an upstream reference and a downstream reference; a detecting circuit 5 for measuring a frequency output signal of the Karman vortex 3 by contracting the potential difference from the induced electromotive force; and in addition a mixing ratio computing part 11 for computing the mixing ratio by comparing a frequency output signal of the Karman vortex 3 measured when only the conductive fluid is made to flow as the fluid with a frequency output signal of the Karman vortex 3 measured when the mixture fluid of the conductive fluid and the insulating fluid 9 is made to flow as the fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixing ratio measuring device for measuring a mixing ratio of a mixed fluid of a conductive fluid and an insulating fluid flowing in a measuring tube, and a mixing of the conductive fluid and the insulating fluid using the same. The present invention relates to a fluid mixing device that controls a ratio to a predetermined mixing ratio.

[0002]

2. Description of the Related Art Conventionally, when a first fluid flowing in a measuring tube is mixed with a second fluid at a predetermined mixing ratio, when the flow rate of the first fluid is fluctuating, the first fluid is mixed. The flow rate was measured by a flow meter, and the flow rate of the second fluid was calculated and mixed based on the measurement result. However, this method does not measure the mixing ratio of the actually mixed fluids, but is merely a predicted value based on the flow rate before mixing, so that feedback control or the like cannot be performed. And to measure the actual mixing ratio,
Each of the two components being mixed has to be measured, and it is extremely difficult to measure each separately, and in effect the measuring device for measuring the mixing ratio has been abandoned.

However, the present inventor has discovered and noticed that a difference in induced electromotive force appears depending on the mixing ratio in the case of a conductive fluid and an insulating fluid even in a mixed fluid. The conductive fluid may be a liquid containing water or an electrolyte, or a conductive liquid such as an acid or an alkali, and the insulating fluid is a non-conductive fluid such as gas or oil. With such a fluid, if the amount of change in the induced electromotive force is measured, the mixing ratio can be known using a calibration curve.

However, even if the mixing ratio can be calculated by measuring the induced electromotive force of such a mixed fluid, the accuracy of the practical fluid mixing apparatus is poor with the ratio alone, and is not useful. Again, it must be able to measure the absolute amount of flow as well as the mixing ratio. It is necessary to use a flow measuring device as a device for measuring the flow rate, and what kind of flow measuring device has been conventionally used will be described below.

[0005] As a conventional flow rate measuring device for measuring the flow rate of a fluid flowing in a measuring tube, a Karman vortex flow rate measuring device is well known. This Karman vortex flow rate measuring device generates Karman vortices in a flowing fluid and counts the number of generated Karman vortices (hereinafter referred to as frequency) as described in, for example, Japanese Patent Application Laid-Open No. 60-40914. The flow rate is calculated from this frequency. This utilizes the phenomenon that the frequency of the Karman vortex is proportional to the flow rate. For this reason, the Karman vortex flow rate measurement device must count the frequency of Karman vortices. However, conventionally, as described in Japanese Patent Application Laid-Open No. 60-40914, the frequency is detected using ultrasonic waves or vibration. ing. When the Karman vortex flows down, it utilizes the fact that ultrasonic waves, vibrations, and the like incident thereon cause a change in frequency and phase.

However, in order to detect changes in ultrasonic waves, vibrations, and the like, there is a problem that a large, complicated, and expensive detecting device is required although the size of the conduit itself is not so large. Was. Moreover, even with such expensive detectors, the accuracy of the flow rate depends primarily on the Karman vortex generation mechanism, and if the temperature or other disturbances affect the Karman vortex generation, the measurement accuracy is immediately increased. It was worse. When the Karman vortex flow rate measuring device is used, the flow rate can be measured, but a device for measuring a different mixing ratio is required, and the size is further increased.

Therefore, in order to solve such a problem,
For example, as disclosed in JP-A-5-172598, it has been proposed to detect the frequency of Karman vortices using a magnetic field. Therefore, such a conventional flow rate measuring device using a magnetic field will be described. FIG. 5 is a cross-sectional view showing a configuration of a conventional flow rate measuring device using a magnetic field.

As shown in FIG. 5, reference numeral 1 denotes a measuring tube through which a fluid having conductivity is passed, and 2 denotes a vortex generator provided in the measuring tube 1. 3 is a Karman vortex generated by the vortex generator 2,
4a and 4b are measurement electrodes. On the downstream side of the vortex generator 2 placed in the flow, a pair of Karman vortex streets whose rotation directions are alternately reversed are generated at a frequency proportional to the representative dimension of the vortex generator 2. The measurement electrode 4b is provided on the downstream side of the vortex generator 2, while the measurement electrode 4a is provided on the upstream side of the measurement electrode 4b as a counter electrode of the measurement electrode 4b, and at the same time, on the downstream side of the vortex generator 2. However, the measurement electrode 4 a shown in FIG. 5 is integrated with the vortex generator 2.

Reference numeral 5 denotes a detection circuit which is electrically connected to the measurement electrodes 4a and 4b and detects a voltage between the measurement electrodes 4a and 4b to calculate a flow rate of a fluid flowing in the measurement tube 1. Reference numeral 8 denotes a measurement tube. 1 is a magnetic field generating device provided around 1, wherein two magnets are disposed with a S-pole and an N-pole facing each other with a measurement tube 1 interposed therebetween. And the magnetic field generator 8
The magnetic field is provided so that the direction of the magnetic field from the north pole to the south pole is perpendicular to the axial direction of the vortex generator 2 and the measurement electrodes 4a and 4b.

According to the conventional flow rate measuring device, when the Karman vortex generated by the vortex generator 2 flows down on the flow, the flow velocity of the flow changes by the velocity of the vortex,
This causes a change in magnetic flux in the magnetic field applied by the magnetic field generator 8. Since this magnetic flux change causes an induced electromotive force between the measurement electrodes 4a and 4b, if this is detected by the detection circuit 5, the number of voltage changes is proportional to the Karman vortex, and the detection circuit 5
The flow rate can be calculated by counting the number of times of voltage change detected in step (1).

[0011] The flow rate measuring device disclosed in Japanese Patent Application Laid-Open No. Hei 5-172598 measures the induced electromotive force to measure the flow rate.
It can be said that it is the most suitable flow rate measuring device to apply to a fluid mixing device using it.

[0012]

However, when the conventional flow rate measuring device as described above is used, when a disturbance is applied to the flow or the magnetic field, noise is added to the magnetic field to be measured.
It has been difficult to calculate an accurate flow rate.
In the case of a fluid having low electrical conductivity (insulating fluid), since the induced electromotive force is originally low and the signal level is low, it has been difficult to accurately detect the flow rate. Therefore, when the proportion of the insulating fluid in the mixed fluid increases, the accuracy decreases.

When the flow rate changes from the flow rate range optimal for measurement, the frequency of the Karman vortex does not change in proportion to the change in the flow rate, and the accuracy of the theoretical formula falls, the proportional relationship is broken, and the detection accuracy decreases. In addition, the flow is disturbed with an increase in the flow rate, and the turbulence increases noise, so that the measurement accuracy is reduced.

Further, when a permanent magnet is used as the magnetic field generator, the performance of the magnet deteriorates due to the aging of the magnet, and the polarization generated at the electrodes causes a reduction in the induced electromotive force, thereby lowering the signal level. Therefore, accurate flow rate detection becomes difficult.

The biggest problem is that when the mixing ratio of the fluid changes, the conductivity changes and the measuring electrodes 4a, 4b
A change in the electromotive force that occurs between them, but if there is no calibration curve or other conversion method from the electromotive force to the mixing ratio, a mixing ratio measuring device that measures the mixing ratio and a fluid that uses it Realizing a mixing device is difficult. In particular, the mixing ratio measuring device is not practical unless it is compact and inexpensive, and it cannot be used for feedback control or the like at all unless the accuracy is high.

As described above, if it is attempted to manufacture a fluid mixing device using a conventional flow rate measuring device, it is difficult to cope with various measurement conditions, and a high level of conversion from the electromotive force for measuring the mixing ratio to the mixing ratio is required. Accuracy and inexpensive methods have not been discovered yet.

Therefore, in order to solve such a conventional problem, the present invention has a wide measuring range, can cope with a wide range of flow conditions, is low in cost and high in accuracy, and can mix a conductive fluid and an insulating fluid. An object of the present invention is to provide a mixing ratio measuring device capable of measuring a mixing ratio of a fluid.

Further, the present invention has a wide measuring range, can cope with a wide range of flow conditions, can measure the mixing ratio of a mixed fluid composed of a conductive fluid and an insulating fluid at low cost and with high accuracy, and can measure one fluid. It is an object of the present invention to provide a fluid mixing device that can obtain a mixed fluid having a predetermined mixing ratio by mixing with another fluid.

[0019]

In order to solve such a problem, a mixing ratio measuring apparatus according to the present invention is provided in a measuring tube, and a vortex generator for generating Karman vortices in a fluid flowing through the measuring tube; A pair of electromotive force measuring electrodes provided downstream of the generator and detecting a change in induced electromotive force generated by a magnetic field change generated when the Karman vortex passes through the magnetic field, and an upstream of the pair of electromotive force measuring electrodes A pair of reference potential measurement electrodes for measuring the potential difference between the upstream side and the downstream side, a magnetic field generator for generating a magnetic field, and a pair of electromotive force measurements And a pair of reference potential measurement electrodes, each of which is electrically connected to a corresponding one of the reference potential measurement electrodes, and detects a potential difference from the induced electromotive force to measure the frequency output signal of the Karman vortex. A mixing ratio calculation unit that calculates a mixing ratio by comparing the frequency output signal of the Karman vortex measured at the time of mixing with the frequency output signal of the Karman vortex when a conductive fluid and an insulating fluid are mixed and flowed as a fluid. It is characterized by having.

Thus, the mixing ratio of the mixed fluid of the conductive fluid and the insulating fluid can be measured at a low cost and with high accuracy, having a wide measuring range, capable of responding to a wide range of flow conditions.

Alternatively, a fluid mixing device according to the present invention is a fluid mixing device provided with the mixing ratio measuring device, wherein a measuring pipe is provided for mixing an insulating fluid with a conductive fluid flowing through the measuring pipe. A part is provided.

[0022] Thus, the mixing ratio of the mixed fluid of the conductive fluid and the insulating fluid can be measured at a low cost and with high accuracy, having a wide measurement range, capable of coping with a wide range of flow conditions, and allowing one fluid to be replaced by the other fluid. To obtain a mixed fluid having a predetermined mixing ratio.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is provided in a measuring tube, a vortex generator for generating Karman vortices in a fluid flowing through the measuring tube, and a vortex generator provided downstream of the vortex generator. A pair of electromotive force measuring electrodes for detecting a change in induced electromotive force generated by a magnetic field change generated when the Karman vortex passes through the magnetic field, and one pair on each of the upstream and downstream sides of the pair of electromotive force measuring electrodes A pair of reference potential measurement electrodes for measuring the potential difference between the upstream side and the downstream side, a magnetic field generator for generating a magnetic field, a pair of electromotive force measurement electrodes and a pair of reference potential measurements And a detection circuit that is electrically connected to the electrodes for measurement and measures the frequency output signal of the Karman vortex by subtracting the potential difference from the induced electromotive force, and the frequency of the Karman vortex measured when only a conductive fluid flows as the fluid. It is a mixing ratio measuring device including a mixing ratio calculating unit that calculates a mixing ratio by comparing an output signal and a frequency output signal of Karman vortex when a conductive fluid and an insulating fluid are mixed and flowed as a fluid. Even if the measurement conditions change, the change can be canceled out using the reference potential measurement electrode and the electromotive force can be measured. The flow rate of the mixed fluid and the conductive fluid can be measured, and the equipment for reducing noise is not required, so the flow rate can be measured at low cost and with high accuracy. The mixing ratio can be easily calculated based on whether or not the mixing is performed.

According to a second aspect of the present invention, there is provided a fluid mixing device provided with the mixing ratio measuring device according to the first aspect, wherein the measuring pipe is insulated from a conductive fluid flowing through the measuring pipe. Since the fluid mixing device is provided with an introduction part for mixing the anaerobic fluid, even if the measurement conditions change, the change is canceled using the reference potential measurement electrode. Since the electromotive force can be measured, it is possible to measure over a wide measurement range, and it is possible to measure the flow rate of the mixed fluid and the conductive fluid over a wide range of flow rates. The flow rate can be measured with high accuracy, and the mixing ratio can be easily calculated based on whether or not the frequency output signal of the Karman vortex is missing.
By mixing the insulating fluid with the conductive fluid, a mixed fluid having a predetermined mixing ratio can be obtained.

According to a third aspect of the present invention, a mixing adjustment valve is provided in the introduction section, and the mixing ratio calculation section controls the mixing adjustment valve in accordance with the mixing ratio calculated by the mixing ratio calculation section. According to the fluid mixing device of the second aspect, the mixing adjustment valve can be controlled in accordance with the calculated mixing ratio, the mixing ratio can be feedback-controlled, and a mixed fluid having a predetermined mixing ratio can be obtained.

The invention according to a fourth aspect of the present invention is characterized in that the measuring tube has a reduced flow channel cross section upstream of the pair of reference potential measuring electrodes, and the introduction portion is connected. According to the fluid mixing device of the third aspect, the insulating fluid can be mixed with the conductive fluid without power by the ejector action.

(Embodiment 1) A mixing ratio measuring apparatus according to Embodiment 1 of the present invention will be described below with reference to FIG. Although it is not a mixing ratio measuring device, it is provided with a structure capable of measuring a flow rate, and the same members as those of the conventional flow measuring device are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a sectional view showing a configuration of a mixing ratio measuring device according to the first embodiment of the present invention, and FIG. 2 is a detection circuit when a conductive fluid is measured by the mixing ratio measuring device according to the first embodiment of the present invention. FIG. 3 is an output diagram of a detection circuit when a mixed fluid of a conductive fluid and an insulating fluid is measured by the mixing ratio measuring device according to the first embodiment of the present invention.

As shown in FIG. 1, 1 is a measuring tube, 2 is a vortex generator which is provided in a fluid and generates Karman vortices, and 3 is a rotating direction alternately at a frequency proportional to a representative dimension of the vortex generator 2. Vortex 4a and 4b are measurement electrodes, and the induced electromotive force is detected to measure the frequency of the Karman vortex 3. In addition, the inversion circuit inverts the signal of the noise component and cancels it. The circuit, 8 is a magnetic field generator, 9 is an insulating fluid, and 11 is a mixing ratio calculation unit. The mixing ratio calculation unit 11 compares the frequency of the Karman vortex measured when only the conductive fluid is flown with the frequency of the Karman vortex when the conductive fluid and the insulating fluid are mixed and flows, and determines the missing pulse. Is calculated from the ratio. The mixture ratio calculation unit 11 includes a display unit that displays a calculation result,
The mixing ratio can be displayed.

If the inside diameter of the measuring tube 1 is too small, the influence of the boundary layer of the tube wall affects the Karman vortex street, and if it is too large, the flow velocity becomes slow and the Karman vortex street does not occur. Reynolds number in proper flow velocity range is 3,000
It is in the range of about 100,000. In addition, the vortex generator 2
Is a triangular prism in the present embodiment,
Any shape may be used as long as it generates a Karman vortex street. The vortex generator 2 of the present embodiment is attached to the measurement tube 1 so that one side surface of the triangular prism is perpendicular to the flow. In the case of the flow measurement device according to the present embodiment, the flow detection range is set to 1 L / min to 10
In order to set L / min, the measuring tube 1 having an inner diameter of φ7 mm was used. Under this condition, it is most effective to provide a vortex generator 2 composed of a triangular prism having a width of 2 mm and a height of 3 mm and an isosceles triangular cross section. It was a target.

The two measuring electrodes 4a and 4b are mounted in parallel on the downstream side of the vortex generator 2 so as to be orthogonal to the axis of the vortex generator 2 and the flow. At this time, if a streamline passing through the measurement electrode 4a is drawn, the streamline always passes through the measurement electrode 4b. N-poles and S-poles of permanent magnets constituting the magnetic field generator 8 are provided on both sides so as to sandwich the measurement electrodes 4a and 4b from both sides of the measurement tube 1. When the flow rate detection range is set to 1 L / min to 10 L / min, the magnetic field generator 8 needs to increase the magnetic flux density in the measuring tube 1, and uses a rare-earth permanent magnet and uses 1.5 times the width of the vortex generator 2. The magnet has twice the width.

6a and 6b are reference potential measuring electrodes,
The potential of each of the upstream and downstream sides of the measurement electrodes 4a and 4b is measured, and the potential difference between the upstream position and the downstream position can be measured. The four reference potential measuring electrodes 6a and 6b are provided in parallel with the measuring electrodes 4a and 4b. At this time, streamlines drawn through the reference potential measurement electrodes 6a and 6b always pass through the measurement electrodes 4a and 4b. Therefore, the four electrodes completely have a positional relationship upstream and downstream of one flow.

The Karman vortex flow rate measuring device is designed so that each member arranged in such an arrangement stably generates the Karman vortex 3 and does not generate noise due to turbulence generated in the measuring tube 1. In addition, it is necessary to carefully select the representative dimensions of each member, the Reynolds number of the fluid, and the like.

In FIG. 1, the dimensions of each member are based on a delicate balance relationship for stable generation of Karman vortices 3 and prevention of noise as described below. For example, the diameter of the reference potential measuring electrodes 6a and 6b is
Of the width D, which is the representative dimension of, is selected. Thus, when considering the diameters of the reference potential measurement electrodes 6a and 6b, the Reynolds number becomes 1/2 or less and approaches a laminar flow,
The generation of the Karman vortex 3 is not disturbed. Further, the vorticity components generated by the reference potential measurement electrodes 6a and 6b themselves are also reduced.
Since a magnetic flux change is hardly generated between the measurement electrodes 4a and 4b with a flow velocity change of about the transient component, the flow rate can be measured without reducing the measurement accuracy.

Also, it is preferable that the diameter of the measuring electrodes 4a and 4b is not more than 1/2 of the width of the vortex generator 2. This is because the Reynolds number becomes １ ／ or less, and the flow in the vicinity approaches laminar flow, so that the flow that generates the Karman vortex 3 is hardly disturbed, and the flow of the Karman vortex street is not destroyed. . When the diameters of the measurement electrodes 4a and 4b are made equal, noise generated at the measurement electrodes 4a and 4b can be reduced. That is, the flow disturbed by the measuring electrode 4a flows down the streamline while the turbulence is diffused, and flows into the measuring electrode 4b.
Fluid resistance and peeling conditions are different between a and 4b, and the surrounding flow is also a separate and complicated flow to increase noise, but the noise is relatively suppressed because of the same diameter. Moreover, in the present embodiment, the diameter is the same and the noise components are made substantially the same, and the detection circuit 5 is provided with an inversion circuit. After the noise component signal from one electrode is inverted by the inversion circuit, By canceling both the processed noise component signals, the noise level is further reduced from the viewpoint of signal processing.

Further, when the length of the measuring electrodes 4a and 4b in the tube is set to be 2 to 2.5 times the width of the vortex generator 2, the inner diameter of the measuring tube 1 is about 3 to 4 times the width of the vortex generator 2 and the flow. Since the size balance is appropriately adopted, the vicinity of the tip of the measurement electrodes 4a and 4b has the minimum height that completely surrounds exactly two Karman vortex streets, and the induced electromotive force change at the center of the generated Karman vortex streets Only the flow rate can be measured with high accuracy. If the lengths of the measuring electrodes 4a and 4b are the same, noise due to disturbances other than the Karman vortex 3, such as vortices flowing out from the tips of the measuring electrodes 4a and 4b, can be canceled by the detection circuit 5, and the noise level can be reduced. The flow rate can be measured with high accuracy.

Further, when the interval between the measurement electrodes 4a and 4b is set to be 2 to 2.5 times the width of the vortex generator 2, the interval between the pair of measurement electrodes 4a and 4b becomes the Karman vortex 3 of the Karman vortex train and the Karman vortex. 3, the measuring electrodes 4a, 4b
The number of the Karman vortices 3 existing therebetween can be one or less, that is, not present, and the noise level can be reduced, and one of the Karman vortices 3 can correspond to one pulse. In addition, frequency counting becomes easy, and high-precision flow measurement can be performed.

When the width of the magnetic field generator 8 in the radial direction is 1.5 to 2 times the width of the vortex generator 2, the magnetic field generated in the measuring tube 1 is concentrated only at the position where the Karman vortex 3 is generated. ,
The noise component due to the vorticity component generated on the side wall of the measurement tube 1 can be reduced. As described above, the flow rate measuring device of the present embodiment employs 1.5 times.

With the mixing ratio measuring apparatus having the above-described configuration, when the Karman vortex street crosses the magnetic flux passing through the portion surrounded by the measurement electrodes 4a and 4b, a magnetic field change occurs, and the measurement electrodes 4a and 4b The induced electromotive force is generated regularly in a pulsed manner. Since the potential difference in the vicinity is measured by the reference potential measurement electrodes 6a and 6b, the reference potential difference reflecting the measurement conditions (DC components and disturbance noise components other than the Karman vortex 3) in the vicinity can be measured. By canceling this reference potential difference signal in the detection circuit 5 from the electromotive force signal generated between the measurement electrodes 4a and 4b, signals other than noise components and Karman vortex streets can be easily eliminated.

The mixing ratio measuring apparatus according to the first embodiment includes a Karman vortex frequency output signal measured when only a conductive fluid flows, and a Karman vortex frequency output signal measured when a conductive fluid and an insulating fluid are mixed and flowed. It has a mixture ratio calculation unit 11 that compares the frequency output signals of the vortices and calculates the mixture ratio from the ratio of the missing frequency output signal (pulse). The mixing ratio measuring apparatus according to the first embodiment first flows only the conductive fluid and counts the 100% frequency output signal of the conductive fluid from the detection circuit. This corresponds to the measurement electrode 4 as shown in FIG.
An output signal obtained by taking the difference between the electromotive force signal generated between a and 4b and the reference potential difference signal difference is an output signal indicating the frequency of the Karman vortex 3 without any loss. Next, a mixed fluid of a conductive fluid and an insulating fluid is allowed to flow, and the output signal from the detection circuit is counted. The output signal obtained by taking the difference between the electromotive force signal and the reference potential difference signal difference is a missing frequency output signal having a missing pulse as shown in FIG.

The reason why the missing frequency output signal is generated is as follows. The flow of the insulating fluid is bent by the centrifugal force of the vortex, so that the insulating fluid gathers at the center of the three rows of low-pressure Karman vortices. The induced electromotive force is reduced by the action of the insulating fluid gathered around the Karman vortex 3, and even if the Karman vortex 3 exists between the measurement electrodes 4a and 4b, the frequency output signal has a defect. The mixing ratio calculator 11 calculates the ratio between the 100% frequency output signal 13 of the conductive fluid and the missing frequency output signal 14,
The mixture ratio corresponding to this ratio is read from the data stored in the internal memory and displayed on the display unit.

Next, the operation of the mixing ratio measuring device according to the first embodiment having such a configuration will be described. First, only the conductive fluid is caused to flow in the measurement tube 1 and is caused to flow down in the magnetic field formed by the magnetic field generator 8. At this time, the Karman vortex street generated in the vortex generator 2 has a proportional relationship between the frequency of the Karman vortex 3 and the flow velocity, as is known from the study of Strouhal. Therefore, if the frequency of the Karman vortex 3 at this time is counted, a 100% frequency output signal 13 of the conductive fluid flowing in the measurement tube 1 can be calculated. Next, a mixed fluid of a conductive fluid and an insulating fluid is caused to flow into the measurement tube 1, and is caused to flow down in the magnetic field applied by the magnetic field generator 8. Similarly, the missing frequency output signal 14 that is missing in the insulating fluid can be calculated. The number of the missing pulses corresponds to the mixing ratio. The ratio between the two is taken, and the corresponding mixing ratio is read out and displayed on the display unit.

(Embodiment 2) Hereinafter, a flow mixing device according to Embodiment 2 of the present invention will be described with reference to FIG. Note that the same members as those of the mixing ratio measuring device of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. FIG. 4 is a sectional view showing the configuration of the fluid device according to the second embodiment of the present invention.

As shown in FIG. 1, 1 is a measuring tube, 2 is a vortex generator which is provided in a fluid and generates Karman vortices, and 3 is a rotating direction alternately at a frequency proportional to a representative dimension of the vortex generator 2. 4a and 4b are measurement electrodes, 5 is a detection circuit, 8 is a magnetic field generator, 9 is an insulating fluid, and 11 is a mixing ratio calculation unit. Reference numeral 10 denotes an introduction pipe (introduction section) connected to a portion where the flow path cross section of the measurement pipe 1 is reduced.
And for introducing an insulating fluid. Reference numeral 12 denotes a mixing adjustment valve provided in the introduction pipe 10. The mixing ratio calculation unit 11 controls the mixing adjustment valve 12 so as to eliminate the difference when the calculated mixing ratio and the target mixing ratio are different.
Adjust the opening of. Thereby, even when the mixing ratio fluctuates, it is possible to control to eliminate the deviation by the feedback control. Further, since the cross section of the flow path of the measurement tube 1 is reduced and the pressure is reduced, an ejector action occurs, and the insulating fluid 9 is sucked from the introduction tube 10 without power.

[0044]

As described above, according to the first aspect of the present invention, even when the measurement conditions change, the change is canceled by using the reference potential measurement electrode to generate the electromotive force. Measurement, it is possible to measure over a wide measurement range, and it is possible to measure the flow rate of mixed fluid and conductive fluid over a wide flow rate range, and no equipment is required to reduce noise. Thus, the mixing ratio can be easily calculated based on whether or not the frequency output signal of the Karman vortex is missing.

According to the invention of claim 2 of the present invention, the mixing ratio can be easily calculated based on whether or not the frequency output signal of the Karman vortex is missing, and the insulating fluid is mixed with the conductive fluid. Thus, a mixed fluid having a predetermined mixing ratio can be obtained.

According to the third aspect of the present invention, since the mixing ratio calculating section controls the mixing adjusting valve according to the mixing ratio, the mixing adjusting valve can be controlled according to the calculated mixing ratio, and the mixing ratio is fed back. It is possible to control and obtain a mixed fluid of a predetermined mixing ratio.

In the invention according to claim 4 of the present invention, since the measuring tube is provided with the introduction section provided with the flow path cross-section reduced on the upstream side of the pair of reference potential measuring electrodes, it is insulated without power by the ejector action. The conductive fluid can be mixed with the conductive fluid.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a mixing ratio measuring device according to a first embodiment of the present invention.

FIG. 2 is an output diagram of a detection circuit when a conductive fluid is measured by the mixing ratio measuring device according to the first embodiment of the present invention.

FIG. 3 is an output diagram of a detection circuit when a mixed fluid of a conductive fluid and an insulating fluid is measured by the mixture ratio measuring device according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a fluid mixing device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the configuration of a conventional flow measurement device using a magnetic field.

[Description of Signs] 1 Measurement tube 2 Vortex generator 3 Karman vortex 4a, 4b Measurement electrode 5 Detection circuit 6a, 6b Reference potential measurement electrode 8 Magnetic field generator 9 Insulating fluid 10 Introducing tube (introducing portion) 11 Mixing ratio calculating unit 12 Mixing adjustment valve 13 100% frequency output signal 14 Missing frequency output signal

Claims (4)

[Claims] 1. A vortex generator provided in a measurement tube and generating a Karman vortex in a fluid flowing through the measurement tube; and a vortex generator provided downstream of the vortex generator and generated when the Karman vortex passes through a magnetic field. A pair of electromotive force measurement electrodes for detecting a change in induced electromotive force generated by a change in magnetic field; and a pair of electrodes respectively provided on the upstream side and the downstream side of the pair of electromotive force measurement electrodes. A pair of reference potential measurement electrodes for measuring the potential difference between the first and second electrodes, a magnetic field generator for generating the magnetic field, the pair of electromotive force measurement electrodes and the pair of reference potential measurement electrodes. A detection circuit for measuring the frequency output signal of the Karman vortex by subtracting the potential difference from the induced electromotive force, wherein the Karman vortex is measured when only a conductive fluid is flowed as the fluid. A wave number output signal, and a mixing ratio calculation unit that calculates a mixing ratio by comparing a frequency output signal of the Karman vortex when the conductive fluid and the insulating fluid are mixed and flowed as the fluid. Mixing ratio measuring device. 2. A fluid mixing device provided with a mixing ratio measuring device according to claim 1, wherein said measuring tube has an introduction portion for mixing an insulating fluid with a conductive fluid flowing through said measuring tube. A fluid mixing device provided. 3. The mixing unit according to claim 2, wherein the mixing unit is provided with a mixing control valve, and the mixing ratio calculating unit controls the mixing control valve according to the mixing ratio calculated by the mixing ratio calculating unit. A fluid mixing device as described. 4. The fluid mixing device according to claim 3, wherein said measuring tube has a reduced flow path cross section upstream of said pair of reference potential measuring electrodes, and said introduction portion is connected thereto. apparatus.