JPH1164409A - Sensor for measuring phase ratio of each component of mixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor for measuring a phase ratio of each component of a mixture capable of preventing an error, based on the non-uniform distribution of a mixture. SOLUTION: This sensor is constituted of plural electrodes 3a-3p mutually insulated and arranged so as to surround the periphery of a pipe line 2 where the mixture 1 fowls, a driving electrode group 131 for AC voltage driving the plural electrodes, a measurement electrode group 132 at a position opposite to the driving electrode group 131 and a dummy electrode group 133 positioned on both sides of the measurement electrode group 132. The combination of the respective electrode groups is electrically switched so as to rotate the respective electrode groups around the pipe line 2 once corresponding to the number of the plural electrodes, capacitance between the driving electrode group 131 and the measurement electrode group 132 is measured for each changeover and the phase ratios of respective components are found from the measured capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for measuring the ratio (phase ratio) of each component of a mixture comprising water and oil.

[0002]

2. Description of the Related Art FIG. 20 is a block diagram of a conventional mixture phase ratio measuring sensor utilizing capacitance. According to this sensor, the drive electrode 111 and the measurement electrode 112 are arranged around the conduit 110 through which the mixture 100 flows, and an AC voltage is applied to the drive electrode 111 so that a gap between the drive electrode 111 and the measurement electrode 112 is generated. The mixture 100 inside the line 110
Is measured by the capacitance measuring circuit 113. For example, in the case of a mixture of water, oil and air, the relative permittivity of water is about 80, the relative permittivity of oil is about 2-3, the relative permittivity of gas is 1, and the dependence on temperature is small. Assuming that the capacitance of each component can be obtained by multiplying the phase ratio of each component by each relative dielectric constant and a coefficient, the ratio (phase ratio) of the components in the mixture is determined. Examples of such prior art include, for example, U.S. Pat.
There is a number.

[0003]

However, in the above-mentioned method, for example, when the distribution of water is not uniform, it is not possible to measure the phase ratio accurately due to the influence of the distribution. The same is true even if the measurement target is another substance. The reason is that a plurality of substances existing between the electrodes form a parallel capacitor in an electric circuit, a series capacitor, or a combination of them to form a capacitor. It is also attempted to improve these problems by devising the electrode shape,
The effects of the non-uniform distribution have not yet been sufficiently removed. The present invention has been made to solve these problems, and an object of the present invention is to provide a mixture phase ratio measurement sensor capable of preventing an error based on a non-uniform distribution of a mixture.

[0004]

The invention according to claim 1 is
In a mixture phase ratio measurement sensor for determining a phase ratio of the mixture by measuring a capacitance between a voltage driving electrode and a measurement electrode provided in a conduit through which a mixture composed of a plurality of phases flows, A plurality of electrodes arranged so as to be insulated from each other so as to surround the periphery; a drive electrode group for driving the plurality of electrodes with an AC voltage; a measurement electrode group at a position opposed to the drive electrode group; A dummy electrode group is arranged on both sides of the electrode group, and a combination of the electrode groups is electrically switched so that each of the electrode groups makes one rotation around the pipeline in accordance with the number of the electrodes. A switching device, a potential supply device that applies the same potential as the measurement electrode group to the dummy electrode group, and an electrostatic capacitance that measures the capacitance between the drive electrode group and the measurement electrode group each time the switching device is switched. And quantity measuring device, a mixture phase ratio measuring sensor with the measured capacitance and a phase fraction calculation device for determining the phase ratio of each component.

According to a second aspect of the present invention, in the first aspect of the present invention, the average dielectric constant ε _{m of the} mixture obtained from the capacitance obtained from the capacitance measuring device, and the first dielectric constant of the mixture The mixing coefficient Y of the mixture obtained from the dielectric constant ε _w of the component, the dielectric constant ε _o of the second component of the mixture, and the value of the change in capacitance with each switching of the switching device.
, The phase ratio φ of the first component is determined by the following equation: φ = 1 − {(ε _m −ε _w ) / (ε _o −ε _w )} · (ε _o
/ Ε _m ) ^Determined as ^Y.

The invention according to claim 3 is the invention according to claim 1, further comprising an electric resistance measuring device for measuring electric resistance between the driving electrode group and the measuring electrode group every time the switching device is switched. and average dielectric constant epsilon _m of the mixture obtained from the capacitance obtained from the capacitance measuring device,
The dielectric constant ε _w of the first component of the mixture and the second
Using the dielectric constant ε _o of the component and the mixing coefficient Y of the mixture obtained from the fluctuation value of the electric resistance obtained from the electric resistance measuring device, the phase ratio φ of the first component is defined as φ = 1 − ｛(Ε _m −ε _w ) / (ε _o −ε _w )｝ · (ε _o
/ Ε _m ) ^Determined as ^Y.

The invention according to a fourth aspect is the invention according to the first aspect, further comprising a flow velocity measuring device for measuring a flow velocity of the mixture, wherein the flow rate of the mixture obtained from the capacitance obtained from the capacitance measuring device is measured. Mixing of the mixture determined from the average dielectric constant ε _m , the dielectric constant ε _w of the first component of the mixture, the dielectric constant ε _o of the second component of the mixture, and the flow velocity obtained from the flow velocity measuring device Using the coefficient Y, the phase ratio φ of the first component is calculated as follows: φ = 1 − {(ε _m −ε _w ) / (ε _o −ε _w )} · (ε _o
/ Ε _m ) ^Determined as ^Y.

According to a fifth aspect of the present invention, in the first aspect of the present invention, there is provided a pressure measuring device for measuring a pressure in the pipeline, wherein the pressure is obtained from the capacitance obtained from the capacitance measuring device. From the average dielectric constant ε _m of the mixture, the dielectric constant ε _w of the first component of the mixture, the dielectric constant ε _o of the second component of the mixture, and the pressure variation obtained from the pressure measuring device, Using the obtained mixture coefficient Y of the mixture, the phase ratio φ of the first component is calculated as follows: φ = 1 − {(ε _m −ε _w ) / (ε _o −ε _w )} · (ε _o
/ Ε _m ) ^Determined as ^Y.

According to a sixth aspect of the present invention, in the invention of the second to fifth aspects, the mixing coefficient is calculated using a neural network.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram of a phase ratio measurement sensor according to the present invention, which performs control and calculation with a plurality of electrodes 3 arranged insulated from each other over the entire circumference of a pipe 2 through which a mixture 1 as a measurement fluid flows. Consists of multiple devices. 2 and 3 are a perspective view and a side view, respectively, specifically showing the relationship between the conduit 2 and the plurality of electrodes 3. FIG. 4 is an electrode group configuration diagram showing an arrangement example of each electrode group when a plurality of electrodes 3 are used as a drive electrode group, a measurement electrode group, and a dummy electrode group.

In this case, 16 electrodes 3 (3a to 3p) are provided around the pipe line 2, and they are connected to the driving electrode group 131 and the measurement electrode group 1 by the switching device 18.
32 and the dummy electrode group 133. In the example of FIG. 4, the electrodes 3 a to 3 in the range of 180 degrees around the pipe 2 are shown.
h is a drive electrode group 131, electrodes 3k to 3n facing the drive electrode group 131 and within a range of 90 degrees around the pipe line 2 are a measurement electrode group 132, and the drive electrode group 131 and the measurement electrode group 132 Electrodes 3i, 3j, 3o, 3p between
Are the dummy electrode group 133. Dummy electrode group 133
Are set to the same potential as the measurement electrode group 132 by the potential supply device 19. The capacitance between the drive electrode group 131 and the measurement electrode group 132 is measured by the capacitance measurement device 16.
Based on the measured capacitance, the arithmetic processing unit 17
The phase ratio of the mixture is calculated from the following relationship. Note that the number of electrodes and the angle range in which each electrode group is included need not be limited to this example.

For example, if the mixture is composed of water, oil and air, and ε _w is the permittivity of water, ε _o is the permittivity of oil, and ε _a is the permittivity of air, the capacitance C is , a relationship of _{C = Hw · Kw · ε w} + Ho · Kp · ε o + Ha · Ka · ε a (1). Here, Hw, Ho, and Ha are phase ratios of water, oil, and air, respectively, and Kw, Ko, and Ka are constants. Further, variation △ C for capacitance at different frequencies f1, f2 can be expressed by _{△ C = K {ε m (} f1) -ε m (f2)} (2). Where K is a constant and ε _m is the average dielectric constant of the mixture. Further, if ρ _m is the average density of the mixture, ρ _w is the density of water, ρ _o is the density of oil, and ρ _a is the density of air, ρ _m = Hw · ρ _w + Ho · ρ _o + Ha · ρ _a ( 3) and 1 = Hw + Ho + Ha (4)

Next, the operation of this sensor will be described using a mixture of water (w) and oil (o) as an example. FIG. 5 shows a case where water is around the oil, and the drive electrode group 131 to the measurement electrode group 132
And lines of electric force run toward the dummy electrode group 133, which can be represented by an equivalent circuit of a capacitor using water and oil as shown in FIG. On the other hand, FIG. 7 shows the same phase ratio (moisture percentage) as in FIG. 5 when water is present in the oil, which can be represented by an equivalent circuit of a capacitor using water and oil as shown in FIG. Can be. In these two cases, measuring electrode group 1
When all outputs of the dummy electrode group 32 and the dummy electrode group 133 are measured as output values, the output capacitance values are significantly different while having the same phase ratio.
Is larger than when surrounding oil is present. However, if the output of the dummy electrode group 133 on both sides of the measurement electrode is not taken as a measurement value, the respective capacitance values measured in the above two cases become close,
The influence of the distribution of the mixture can be reduced. The present invention utilizes this.

When the measurement of the capacitance is completed in the configuration shown in FIG. 4, the switching device 18 electrically shifts the electrodes one by one to form each electrode group again. For example, if the electrodes 3b to 3i are shifted clockwise,
To the drive electrode group 131, and the electrodes 31 to 3o to the measurement electrode group 1
32, the electrodes 3j, 3k, 3p, and 3a are connected to the dummy electrode group 1
33. Then, the drive electrode group 131 at this position
The capacitance between the measurement electrode group 132 and the measurement electrode group 132 is measured again.
In this manner, a total of 16 electrodes in this example is used until each electrode group goes around the circumference of the conduit 2 in accordance with the number of the plurality of electrodes 3.
Times of capacitance measurement, and from the obtained capacitance,
The phase ratio of water in this section is obtained by the arithmetic processing unit 17. In the case where the phase ratio of each component changes over time, the measurement is continuously performed to measure the change over time of the phase ratio of each component.

The average dielectric constant ε _m of the mixture is obtained by multiplying the measured capacitance value by a coefficient obtained in advance by an experiment. In the case of a mixture of water and oil, assuming that the dielectric constant of water is ε _w and the dielectric constant of oil is ε _o , the phase ratio of water is φ = 1− φ (ε _m −ε _w ) / (ε _o − ε _w )｝ · (ε _o / ε _m ) ^Y (4) Y in the equation (4) is a mixing coefficient of the mixture taking a value from 0 to 1, and can be obtained in advance by an experiment when the mixing state is known.

When the mixing state of the mixture cannot be predicted, the mixing coefficient Y can be obtained by various methods as described below. One of the methods is a method of obtaining from a capacitance variation value obtained by each measurement. When the flow velocity is low, water and oil flow in layers as shown in FIG. Then, the capacitance value measured each time becomes as shown in FIG. 10, and the change in the measured value becomes large. At this time, a mixing coefficient Y that can calculate the water phase ratio most accurately from the equation (4) is obtained in advance. When the flow velocity increases, water and oil are mixed as shown in FIG. 11, and the capacitance value measured each time has less fluctuation as shown in FIG. Again,
A mixing coefficient Y that can calculate the water phase ratio most accurately from the equation (4) is obtained in advance. Based on these values, the arithmetic processing unit 17 obtains the mixing coefficient Y of the mixture whose mixing state is unknown, using the variation ratio of the measured capacitance value at each time as a parameter.

Embodiment 2 FIG. The second method for obtaining the mixing coefficient Y utilizes the fluctuation of the electric resistance between the drive electrode group 131 and the measurement electrode group 132. In the case of a mixed state as shown in FIG. 9, the drive electrode group 131 and the measurement electrode group 13
Since the electric resistance value when water and oil are connected in series between the two is increased, and the electric resistance value when they are connected in parallel is reduced, the electric resistance value at each measurement is shown in FIG.
become that way. At this time, a mixing coefficient Y that can calculate the water phase ratio most accurately from the equation (4) is obtained in advance. On the other hand, in the case of the mixed state as shown in FIG. 11, the electric resistance value at each measurement is little changed and becomes as shown in FIG. Also at this time, the mixing coefficient Y that can calculate the water phase ratio most accurately from the equation (4) is obtained in advance. Based on these values, the mixing coefficient Y of the mixture whose mixing state is unknown can be obtained by using the variation ratio of the electric resistance value at each measurement as a parameter. FIG. 13 is a configuration diagram of a mixture phase ratio measurement sensor using this method. This is achieved by adding an electric resistance measuring device 20 for measuring the electric resistance between the driving electrode group 131 and the measuring electrode group 132 at each time of the capacitance measurement to the configuration of FIG. Using the fluctuation ratio as a parameter, the arithmetic processing unit 17 obtains the mixing coefficient Y of the mixture whose mixing state is unknown.

Embodiment 3 A third method for determining the mixing coefficient Y utilizes the flow rate of the mixture. The correlation between the flow rate of the mixture and the mixing coefficient Y is determined in advance, and the mixing coefficient is determined from the actually measured flow rate. FIG. 14 is a configuration diagram of the mixture phase ratio measurement sensor of this example. This is achieved by providing a flow rate sensor 40 for measuring the flow rate of the mixture in the pipe line 2 in addition to the configuration of FIG. 1 and using the measured flow rate as a parameter to calculate the mixing coefficient Y of the mixture whose mixing state is unknown. Ask for.

Embodiment 4 A fourth method for determining the mixing coefficient Y utilizes fluctuations in the pressure of the mixture.
For each of the case where the pressure fluctuation is small as shown in FIG. 15 and the case where the pressure fluctuation is large as shown in FIG. 16, a mixing coefficient Y which can calculate the water phase ratio most accurately from the equation (4) is obtained in advance. Based on these values, using the measured pressure fluctuation as a parameter, the mixing coefficient Y of the mixture whose mixing state is unknown
Can be requested. FIG. 17 is a configuration diagram of a mixture phase ratio measurement sensor using this method. This is shown in FIG.
A pressure sensor 41 for measuring the pressure of the mixture flowing through the pipe line 2 each time, and using the fluctuation ratio of the measured resistance value as a parameter, calculates the mixing coefficient Y of the mixture whose mixing state is unknown. Find at 17.

Embodiment 5 When the pulsation of a pump or the like is large, as shown in the configuration diagram of FIG.
2 can be installed in such a manner as to cancel the pulsation inside the pipeline 2 and its output can be used. FIG. 19 is a side view showing the relationship between the pipeline 2 and the pressure sensor 42.

When the mixing coefficient Y described above is obtained, the relationship between each of the above parameters and the mixing coefficient Y can be obtained by using the learning operation of the neural network. For example, when the variation of the capacitance value is used as a parameter, the pattern recognition of the capacitance is performed via a neural network. In this case, the above parameters may be used in combination.

[0022]

According to the mixture phase ratio measuring sensor of the present invention, a plurality of electrodes arranged around a conduit through which the mixture flows are divided into a drive electrode group, a measurement electrode group, and a dummy electrode group. Measure the capacitance between the drive electrode group and the measurement electrode group while electrically switching the position of each electrode group according to the number of electrodes so that the combination of electrode groups goes around the circumference of the pipeline Therefore, the measured value is not affected by the distribution of the mixture, and therefore, the phase ratio calculated based on the capacitance is accurately determined.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a phase ratio measurement sensor of the present invention.

FIG. 2 is a perspective view specifically showing a relationship between a conduit and a plurality of electrodes.

FIG. 3 is a side view specifically showing a relationship between a conduit and a plurality of electrodes.

FIG. 4 is an electrode group configuration diagram showing an arrangement example of each electrode group when used as a drive electrode, a measurement electrode, and a dummy electrode.

FIG. 5 is a diagram showing the state of water and oil inside a pipe.

FIG. 6 is an equivalent circuit of the capacitor in the case of FIG.

FIG. 7 is a diagram showing the state of water and oil inside the pipeline.

FIG. 8 is an equivalent circuit of a capacitor in the case of FIG. 7;

FIG. 9 is a diagram showing the state of water and oil inside the pipeline.

FIG. 10 shows the result of measuring the capacitance or electric resistance between the driving electrode group and the measurement electrode group in the case of FIG. 9 while rotating the group.

FIG. 11 is a diagram showing the state of water and oil inside the pipeline.

FIG. 12 shows a result of measuring a capacitance or an electric resistance value between the drive electrode group and the measurement electrode group while rotating the drive electrode group and the measurement electrode group in the case of FIG. 11;

FIG. 13 is another configuration diagram of the phase ratio measurement sensor of the present invention.

FIG. 14 is another configuration diagram of the phase ratio measurement sensor of the present invention.

FIG. 15 is a diagram showing the relationship between the pressure of a mixture flowing through a pipe and time.

FIG. 16 is a diagram showing the relationship between the pressure of a mixture flowing through a pipe and time.

FIG. 17 is another configuration diagram of the phase ratio measurement sensor of the present invention.

FIG. 18 is another configuration diagram of the phase ratio measurement sensor of the present invention.

FIG. 19 is a side view of FIG. 18 showing a configuration of a pipeline and a differential pressure sensor.

FIG. 20 is a configuration diagram of a conventional mixture phase ratio measurement sensor utilizing capacitance.

[Explanation of symbols]

1 mixture, 2 conduits, 3 multiple electrodes, 16
Capacitance measurement device, 17 arithmetic processing device, 18 switching device, 19 potential supply device, 20 electric resistance measurement device, 40 flow velocity sensor, 41 pressure sensor,
42 Differential pressure sensor.

Continuation of the front page (71) Applicant 000006507 Yokogawa Electric Corporation 2-9-132 Nakamachi, Musashino-shi, Tokyo (72) Inventor Manabu Fueki 2-9-132 Nakamachi, Musashino-shi, Tokyo Inside Yokogawa Electric Corporation (72) Inventor Daisuke Yamazaki 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation (72) Inventor Shuichi Haruyama 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation (72 ) Inventor: Hitoshi Tanaka 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation

Claims (6)

[Claims] A mixture phase ratio measuring sensor for determining a phase ratio of a mixture by measuring a capacitance between a voltage driving electrode and a measurement electrode provided in a conduit through which a mixture of a plurality of phases flows. A plurality of electrodes arranged so as to be insulated from each other so as to surround the periphery of the conduit; a drive electrode group for driving the plurality of electrodes with an AC voltage; and a measurement electrode at a position facing the drive electrode group. And a dummy electrode group located on both sides of the measurement electrode group, and a combination of the electrode groups such that each electrode group makes one rotation around the conduit corresponding to the number of the electrodes. A switching device that electrically switches between the dummy electrode group, a potential supply device that applies the same potential as the measurement electrode group to the dummy electrode group, and a capacitance between the drive electrode group and the measurement electrode group. Mixture phase ratio measurement sensor having a capacitance measuring device, from the measured capacitance and phase fraction calculation device for determining the phase ratio of each component to be measured. 2. An average dielectric constant ε _m of the mixture obtained from the capacitance obtained from the capacitance measuring device, a dielectric constant ε _w of a first component of the mixture, and a second dielectric constant of the mixture. Using the dielectric constant ε _{o of the} component and the mixing coefficient Y of the mixture obtained from the variation value of the capacitance at each switching of the switching device, the phase ratio φ of the first component is calculated as φ = 1− ｛ (Ε _m −ε _w ) / (ε _o −ε _w )｝ · (ε _o
/ Ε _m ) ^Y sensor according to claim 1, determined as ^Y. 3. An electric resistance measuring device for measuring an electric resistance between the driving electrode group and the measuring electrode group each time the switching device is switched, wherein the electric resistance is obtained from a capacitance obtained from the capacitance measuring device. The average dielectric constant ε _m of the mixture, the dielectric constant ε _w of the first component of the mixture, and the dielectric constant ε _w of the second component of the mixture.
_{Using o} and the mixing coefficient Y of the mixture obtained from the fluctuation value of the electric resistance obtained from the electric resistance measuring device, the phase ratio φ of the first component is calculated as φ = 1 − ｛(ε _m − ε _w ) / (ε _o −ε _w )｝ · (ε _o
/ Ε _m ) ^Y sensor according to claim 1, determined as ^Y. 4. A flow rate measuring device for measuring a flow rate of the mixture, an average dielectric constant ε _{m of the} mixture obtained from a capacitance obtained from the capacitance measuring device, and a first component of the mixture. and the dielectric constant epsilon _w of the dielectric constant of the second component of the mixture epsilon
_{Using o} and the mixing coefficient Y of the mixture obtained from the flow rate obtained from the flow rate measuring device, the phase ratio φ of the first component is calculated as follows: φ = 1 − ｛(ε _m −ε _w ) / ( ε _o −ε _w )｝ ・ (ε _o
/ Ε _m ) ^Y sensor according to claim 1, determined as ^Y. 5. An apparatus according to claim 1, further comprising a pressure measuring device for measuring a pressure in the conduit, wherein an average dielectric constant ε _{m of the} mixture determined from a capacitance obtained from the capacitance measuring device, and a first value of the mixture. And the dielectric constant ε _w of the second component of the mixture.
_o and the mixing coefficient Y of the mixture obtained from the fluctuation value of the pressure obtained from the pressure measuring device, the phase ratio φ of the first component is calculated as follows: φ = 1 − ｛(ε _m −ε _w ) / (Ε _o −ε _w )｝ · (ε _o
/ Ε _m ) ^Y sensor according to claim 1, determined as ^Y. 6. The mixture phase ratio measuring sensor according to claim 2, wherein the mixing coefficient is calculated by processing with a neural network.