JP3455774B2 - Device for measuring the amount of mixture in the substance to be measured - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the amount of mixture in a substance to be measured, which measures the amount of mixture of the components of the substance to be measured from the measured values of conductivity in the substance to be measured by at least four electrodes.

[0002]

2. Description of the Related Art Since the conductivity of water increases as the amount of pollutants dissolved in water increases, the conductivity of water is one of the indicators of water pollution due to the increasing interest in environmental protection in recent years. Measurements have become widespread. Since the conductivity reflects the concentration of impurities contained in the substance, it can be expected to be applied not only to water pollution but also to the field of component measurement.

Further, if the amount of water or salt water contained in the soil is large, the conductivity of the soil is high. Therefore, for example, in irrigation agriculture, the amount of irrigation water is grasped, and further, in the case of sediment-related disasters, water is contained. It can be expected to be applied to grasping the condition of soil weakening, grasping saltwater invasion in cultivated land in coastal areas, and grasping the situation of salt accumulation in soil due to excessive irrigation in arid areas.

[0004]

However, in the conventional measurement of conductivity in water pollution, the water to be measured is interposed between two electrodes, and the conductivity between the electrodes is calculated as the reciprocal of the conductivity. Therefore, at the contact portion between the measurement electrode and water, polarization occurred due to electrochemical action, and a correct value could not be obtained. Furthermore, when measuring a large number of samples, it was necessary to wash the electrodes with fresh water every time the samples were replaced.

If four electrodes are used, two out of four
If the current is applied to the mixed substance at the poles, the potential difference in the mixed substance is measured at the remaining two poles, and the ratio (division) between the current and voltage measured at each electrode is calculated, the effect of polarization will be calculated. It is possible to obtain the removed conductivity. However, in the case of this method, it is not easy to divide between two analog signals, so turn the dial by an artificial operation,
Read the value on the dial when the zero point of the signal is established,
A method is used in which each current is read as a digital signal and division is performed by a computer.

Further, the resistivity varies depending on the temperature of the object to be measured regardless of whether the electrode has two poles or four poles. Therefore, even if the impurity component is constant, it is the reciprocal of the resistivity. However, there is a drawback that the electric conductivity fluctuates.

Further, when a plurality of impurities are present,
Since the mixing amount of each impurity contributes to the overall conductivity, it was not possible to measure the mixing amount or fluctuation of only the component of interest.

As described above, an accurate value cannot be obtained by the method of using the two electrodes which can be easily measured on site, and the method of using the four electrodes requires a lot of labor for the measurement on site, and both of them can be measured. There is a drawback that it is affected by the temperature of the product and a plurality of components.

[0009]

Means for Solving the Problems The present invention is to solve the above problems and simplifies the work in the field and reflects the temperature change in the substance to be measured in the measurement of the current signal, The conductivity can be measured without the influence of the change, and the measurement accuracy of the mixed amount of the specific substance can be improved.

To this end, the present invention is a device for measuring a mixed amount in a substance to be measured, which measures a mixed amount of a specific substance mixed and present in the substance to be measured, wherein a plurality of electrodes and one of the electrodes are provided. An electrode support that supports resistors that are connected in series integrally and is arbitrarily arranged in the substance to be measured, a power supply that supplies an alternating current between the two poles of the electrode via the resistor, and both ends of the resistor. Resistance end measuring means for measuring the voltage, voltage measuring means for measuring the potential difference between electrodes other than the electrode supplying the alternating current from the power supply, voltage measured by the resistance end measuring means and the voltage measurement The electric conductivity is obtained by multiplying the ratio with the potential difference measured by the means by a coefficient determined by the arrangement of the electrodes, and the mixture amount of the component of the specific substance of interest in the substance to be measured is converted by the calibration data. And the calculation means For example, the temperature characteristic of the resistor is characterized in that the temperature characteristics close to the substance to be measured, said support is characterized in that of one or a plurality of plate-like body or a rod-shaped body.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an apparatus for measuring a mixed amount in a substance to be measured according to the present invention, in which 1 is an applied current supply unit, 2 is a substance to be measured, 3 is a current measuring unit, 4 is a voltage measuring unit. 5 is a division unit, 6 is an effective value conversion unit, 7 is a conductivity conversion unit, 8 is a reference value setting unit, 9 is a comparison unit, and 10 is a mixed amount display unit.

In FIG. 1, an applied current supply unit 1 is a power supply for supplying an alternating current having a square wave, a sine wave, or an arbitrary waveform having a time average value of zero. The substance 2 to be measured is various conditions / environments, the ground / soil in which the substances are mixed, the granular material deposit,
Fluids such as soil containing water, sand dunes near the coast where salt water invades, cultivated land, irrigated cultivated land, soil for greenhouse cultivation, lakes and swamps where groundwater and pollutants flow, drainage channels These include polluted water, landslides, and hillsides where there is a risk of landslides. In the substance 2 to be measured, at least four electrodes or more and resistors for measuring an applied current are integrally supported by a plate-shaped or rod-shaped support. The current measuring unit 3 supplies an alternating current from the applied current supply unit 1 to two electrodes of the plurality of electrodes arranged in the substance to be measured and measures the current flowing in the substance to be measured. A circuit for measuring a current flowing through a resistance arranged in a substance to be measured together with an electrode. The voltage measuring unit 4 has a plurality of electrodes arranged in the substance to be measured.
It is a circuit that measures the voltage between two electrodes other than the electrode to which an alternating current is supplied. The division unit 5 is a circuit that calculates a value obtained by dividing the measured current signal by a voltage signal, the effective value conversion unit 6 is a circuit that converts the value calculated by the division unit 5 into an effective value, and the conductivity conversion unit 7 is , A circuit for converting an effective value into a conductivity. The reference setting unit 8 is a circuit for setting a value serving as a reference for conductivity measurement, the comparison unit 9 is a circuit for obtaining a deviation from the reference value, and the mixing amount display unit 10 is for displaying the conductivity as a mixing amount in a mixed substance. It is a circuit that converts and displays.

Next, the principle of measuring the conductivity and measuring the mixed amount of the specific substance will be described. First, in the applied current supply unit 1, an alternating current whose electrodes have alternating polarities and whose average value is zero is generated.
The substance to be measured 2 is supplied from two electrodes out of the plurality of electrodes arranged inside. An electric field is generated in the substance 2 to be measured by this alternating current, so that a potential difference is generated between the other two electrodes arranged in the substance 2 to be measured.
Therefore, the current measuring unit 3 measures the alternating current flowing through the resistance arranged in the substance to be measured 2, and the potential difference is measured by the voltage measuring unit 4.
To measure. Then, the division unit 5 obtains a division ratio of the current signal, which is independently measured, by the voltage signal. The ratio obtained here is proportional to the electrical conductivity of the substance to be measured, but since it contains a periodic fluctuation component due to the electrical characteristics of the substance to be measured, it is converted into a DC component equivalent to it by the effective value converter 6. To do. Since the converted DC component is proportional to the conductivity of the substance to be measured, the conductivity conversion unit 7 converts it to an actual value of conductivity. Since this conductivity is the conductivity of the entire substance to be measured, the contribution to the overall conductivity from components other than the component of interest is set by the reference value setting unit 8 and obtained by the conductivity conversion unit 7. If the difference between the conductivity of the entire substance to be measured and the conductivity due to components other than the component of interest is determined by the comparison unit 9,
This difference is the contribution to the conductivity from only the component of interest. This value is displayed on the mixing display unit 10 as a mixing amount of only the component of interest according to a calibration curve that has been calibrated in advance.

[Removal of Temperature Characteristic of Substance to be Measured] As the substance to be measured, when the target substance is spread outdoors such as salt concentration and water content in soil or pollution degree of lake water The conductivity of the substance to be measured is affected by the diurnal variation of the outside temperature. The conductivity in such a case is expressed as the following [Equation 1].

[0015]

[Equation 1]

In [Equation 1], σ is the conductivity of the substance to be measured, ρ is the resistivity of the substance to be measured, θ is the temperature of the substance to be measured,
α is the temperature coefficient of resistance of the substance to be measured, and ρ ₀ is the resistivity when θ = 0. Therefore, the voltage measured by the voltage measuring unit 4 is expressed by the following [Equation 2].

[0017]

[Equation 2]

In [Equation 2], v _p is the measured voltage, k _p is a coefficient determined by the arrangement and shape of the electrode system, and i is the applied current. In the current measuring unit 3, a resistor for measuring the applied current is inserted in the middle of the current circuit and the voltage across the resistor is expressed as the magnitude of the current.
It is represented by.

[0019]

[Equation 3]

In [Equation 3], v _c is the voltage across the resistor, R is the resistor for measuring the applied current, and i is the applied current.
v _c is proportional to the magnitude of the applied current i.

The output of the division unit is the value of [Equation 3] divided by the value of [Equation 2], and since the value is proportional to the electrical conductivity, the conductivity obtained is 4].

[0022]

[Equation 4]

In [Equation 4], kσ is a proportional constant and k is a constant such that k = kσ / k _p . [Equation 4] includes a variation term (1 + αθ) depending on the temperature of the substance to be measured. By the way, if the resistance R for measuring the applied current is arranged in the substance to be measured in [Equation 3], R will undergo the same temperature change as that of the substance to be measured.

[0024]

[Equation 5]

Will be replaced. [In Expression 5, (1 + βθ) is a variation term of R depending on the temperature. α =
In the case of β, [Formula 4] is expressed as follows.

[0026]

[Equation 6]

That is, from [Equation 6], the output from the divider does not include the term of the temperature change of the substance to be measured, and a value proportional to the conductivity of the substance to be measured is output. In the present invention, since the resistance for measuring the applied current is arranged in the substance to be measured, it is possible to measure only the conductivity of the substance to be measured as shown in [Equation 6]. In this case, needless to say, even if the temperature characteristic of the resistance does not completely match the temperature characteristic of the substance to be measured, if the temperature characteristic is close to that, the influence of the temperature change is reduced.

[Extraction of the component of interest in the substance to be measured] In the actual measurement, the substance to be measured contains not only the component of interest (impurities) but also other components.
The conductivity of the substance to be measured in such a case is represented by the following [Equation 7].

[0029]

[Equation 7]

Where σ is the conductivity of the entire mixture, σ₀Is
Conductivity due to components (impurities) other than the component of interest, σ_a
Is the conductivity of only the component of interest. In Figure 1
The output of the conductivity converter 7 is the total conductivity expressed by [Equation 7].
Is the rate. Therefore, the reference from the output of the conductivity conversion unit 7
The conductivity σ set by the value setting unit 8 other than the component of interest
₀By subtracting, the conductivity of the component of interest can be obtained.
Is the output of the comparison unit 9 only the conductivity of the component of interest?
From a separate calibration curve, we focused on conductivity.
It can be displayed by converting it into a mixed amount of minutes.

FIG. 2 is a diagram showing an arrangement example of electrodes and resistors for measuring an applied current when measuring the amount of water in the ground, FIG. 3 is a diagram showing a configuration example of a member supporting the electrodes, and FIG. 4 is an electrode. It is a figure which shows the structural example of a switching circuit. In the figure, 11, 21, 3
1, 41 are electrode supporting members, 12, 22, 32, 42 are electrodes, 13 is a resistance for measuring applied current, 14 is a mixing amount measuring device, 51 is a current pole changeover switch, 52 is a voltage pole changeover switch, and 53 is A power supply / current detection circuit, 54 is a voltage detection circuit.

In the apparatus for measuring the amount of mixture in the substance to be measured according to the present invention having the above-mentioned structure, for example, as shown in FIG. 2, the electrode supporting member 11 integrally supporting the electrode 12 and the resistor 13 for measuring the applied current is grounded. Is placed so as to penetrate into the ground, which is the substance to be measured, and an alternating current is supplied between the two electrodes of the electrodes. Then, the applied current is measured by the resistance 13 for measuring the applied current, and the potential difference between the other electrodes is measured to measure the water content in the ground.

The electrode used in the apparatus for measuring the mixed amount of a mixed substance according to the present invention is for measuring the potential difference between the electrode for passing a current through the substance to be measured and the area of interest in the substance to be measured as described above. It consists of electrodes. Therefore, as shown in FIG. 3, the electrode support members 21, 31, 41 have a plurality of electrodes 22,
32 and 42, and their electrodes are connected to a power supply / current detection circuit 53 for selectively passing a current as shown in FIG. 4, or connected to a voltage detection circuit 54 for detecting a potential difference. So that the electrode switching circuits 51, 52
Electrode and power supply / current detection circuit 53 and voltage detection circuit 54
It may be inserted and connected between and. Of course, without using the power supply switching circuits 51 and 52, the respective electrodes may be assigned as current poles and voltage poles and directly connected to the power source / current detection circuit 53 and the voltage detection circuit 54, or the electrodes may be configured. It is also possible to provide ports corresponding to the number of the above in each of the power supply / current detection circuit 53 and the voltage detection circuit 54 and switch them sequentially.

The structure of the electrode and the electrode supporting member constituting the measuring section is such that a plurality of projecting electrodes 22 are supported by a rod-shaped (pile-shaped) electrode supporting member 21 as shown in FIG. 3 (A). Then, as shown in FIG. 3B, the plurality of annular electrodes 32
May be supported by a rod-shaped (pile-shaped) electrode supporting member 31, or a plurality of protruding electrodes 42 may be supported by a plate-shaped electrode supporting member 41 as shown in FIG.

When a current is applied to the substance to be measured by a pair of electrodes, the detection of voltages in a plurality of areas can be detected by the plurality of pairs of electrodes. In that case, a plurality of pairs for detecting the voltage are detected. After sequentially switching the voltage detection circuit to the electrodes of, connecting the detected voltage values with the current value into analog / digital and storing them in the memory,
The amount of mixture in each area may be obtained, or the amount of mixture may be obtained in either online or offline mode. Further, the data of the obtained mixing amount may be directly displayed as a list and printed out, or may be stored in a memory and output. Of course, it is also possible to carry out an appropriate switching operation and display and output for each detection area.

Next, an example of measuring the content of the mixed substance will be shown.
FIG. 5 is a diagram showing an example of measuring the salt concentration and the level of the output signal in soil saturated with water.
m, 500 ppm, 1000 ppm, 2000 ppm,
The electrical conductivity σ is measured for each of the 3000 ppm and 5000 ppm samples. As is clear from FIG. 5, salt concentration in soil saturated with water (pp
It can be seen that m) is proportional to the conductivity σ. Therefore, the salt concentration (ppm) can be calculated from the conductivity σ. For example, if a conversion table for the conductivity σ and the salt concentration (ppm) is set by a lookup table, the conductivity σ is used to refer to the conversion table. The salt concentration (ppm) can be directly calculated. It is also possible to set a conversion table for obtaining the mixing amount from the current value and the voltage value.

FIG. 6 is a diagram showing an embodiment of a mixed amount monitoring apparatus for a mixed substance according to the present invention, in which 61 is a calculation unit and 62 is a calculation unit.
Is a reference value setting unit, 63 is a comparing unit, and 64 is an output unit.
In FIG. 6, the calculation unit 61 calculates or converts the mixing amount of the specific mixed substance based on the current value, the voltage value, the coefficient depending on the electrode, and the contribution of the components other than the specific mixed substance as described above. It is obtained from a table. The reference value setting unit 62 sets one or a plurality of reference values for evaluating the mixing amount, and the comparing unit 63 is set in the mixing amount and reference value setting unit 62 obtained by the calculating unit 61. It is for comparison with the reference value. The output unit 64 is the calculation unit 6
It outputs information indicating whether or not the mixing amount obtained by 1 exceeds the reference value set in the reference value setting unit 62. When a plurality of reference values are set, the mixing amount increases as the mixing amount increases. The comparison information can be output stepwise. For example, in the case of monitoring the amount of water in the soil, it is possible to give warnings and warnings.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above embodiment, a plurality of electrodes and resistors for measuring an applied current are integrally supported on one support and arbitrarily arranged in the substance to be measured. The resistance for measuring the applied current may be supported, and the support may be not only rod-shaped but also planar, that is, a plate-shaped member, and it may be inserted in the depth direction of the substance to be measured. The electrodes may be embedded in the bottom or the electrodes may be arranged on the bottom surface or wall surface of the storage container. Also, the measurement of the amount of water and salt mixed was explained, but if the component that changes predominantly can be identified, only the change in that component can be observed, and salt accumulation and chemical substances in semi-arid areas can be observed. It is also applicable to soil pollution caused by. Similarly, in a mixing device that mixes a specific substance, it can be applied as a means for detecting the mixing amount.

[0039]

As is apparent from the above description, according to the present invention, it is possible to instantaneously determine the correct conductivity or the amount of the mixed component in the mixture, and the work can be performed when using it in the field such as outdoors. It is possible to improve the sex. Moreover, since the influence of the temperature change of the conductivity of the substance to be measured, which could not be removed until now, can be removed with the analog signal as it is, the accurate conductivity or the mixed amount of the component of interest can be obtained. Furthermore, the measurement is performed by using four electrodes as a set. However, if the electrode system has the same shape, the coefficient peculiar to the electrode system for measuring the conductivity is constant, so it is necessary to calibrate one set of the electrode system. For example, even in the case of simultaneous measurement at multiple points, the conductivity can be immediately obtained, and if the density and constituent components of the material to be measured, such as soil, are the same, it is possible to obtain the calibration curve in advance, so The distributions of the amounts of the components such as water can be obtained in the same manner.

In addition, when a large number of electrode systems are embedded in a substance to be measured and long-term time fluctuations in the depth direction to the ground and the planar spreading direction such as water content are observed, ,
The most accurate variation can be observed because the density and constituent components other than the component of interest in the substance to be measured are not affected by the temperature change of the substance to be measured, and are not changed.
For example, monitoring irrigation in irrigated agriculture, which must be observed over a long period of time, grasping the condition in which water-containing soil is weakened by a sediment disaster, observation of saltwater intrusion into cultivated land in coastal areas, arid zones Fields such as grasping salt accumulation in soil due to excessive irrigation are the fields in which the present invention can be most expected.

In a mixed substance containing a plurality of impurities, if there is only one type of component of interest that is changing with time, the reference value is set so that the output of the measuring instrument becomes zero at the start of observation. This makes it possible to easily measure the amount of fluctuation of the component of interest simply by using the state before measurement as the reference value, which is extremely advantageous for field observation in the field.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an apparatus for measuring a mixed amount in a substance to be measured according to the present invention.

FIG. 2 is a diagram showing an arrangement example of electrodes and resistors for measuring an applied current when measuring the amount of water in the ground.

FIG. 3 is a diagram showing a configuration example of a member that supports electrodes.

FIG. 4 is a diagram showing a configuration example of an electrode switching circuit.

FIG. 5 is a diagram showing an example of measurement of salt concentration and output signal level in soil saturated with water.

FIG. 6 is a diagram showing an embodiment of a mixed amount monitoring apparatus for a mixed substance according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Applied current supply part, 2 ... Substance to be measured, 3 ... Current measurement part, 4 ... Voltage measurement part, 5 ... Division part, 6 ... Effective value conversion part, 7 ... Conductivity conversion part, 8 ... Reference value setting part , 9 ... Comparison unit, 10 ... Mixing amount display unit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-53-119085 (JP, A) JP-A-59-187248 (JP, A) JP-A-55-90853 (JP, A) JP-A-2000-121587 (JP, A) S. 61-152923 (JP, U) Tominaga Masaki, Journal of Groundwater Society, August 1988, Volume 30, No. 3, 151-162 (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 27/00-27/24 G01R 27/00-27/32 JISST file (JOIS)

Claims (2)

(57) [Claims] 1. A device for measuring a mixture amount in a substance to be measured for measuring the amount of a specific substance mixed in the substance to be measured, the device being connected in series to a plurality of electrodes and one of the electrodes. Resistance
An electrode support that supports the electrodes integrally and arranges them arbitrarily in the substance to be measured.
A holder , a power supply that supplies an alternating current between the two poles of the electrode via the resistance , a resistance end measuring unit that measures the voltage across the resistance , and an electrode other than the electrode that supplies the alternating current from the power supply. A voltage measuring unit that measures the potential difference between the other electrodes, and the ratio of the voltage measured by the resistance end measuring unit and the potential difference measured by the voltage measuring unit is multiplied by a coefficient determined by the arrangement of the electrodes to conduct electricity. And a calculation means for obtaining a ratio and converting the calibration data to obtain a mixed amount of the component of the specific substance of interest in the measured substance ,
An apparatus for measuring a mixed amount in a substance to be measured , wherein the temperature characteristic of resistance is a temperature characteristic close to that of the substance to be measured. 2. The apparatus for measuring the amount of a mixture in a substance to be measured according to claim 1, wherein the support comprises one or a plurality of plate-like bodies or rod-like bodies.