JP6515634B2 - Electromagnetic induction type conductivity detector and electromagnetic induction type conductivity meter - Google Patents

Description

  In the present invention, an electromagnetic induction type conductivity detector (hereinafter sometimes simply referred to as a "detector") that outputs a signal according to the conductivity of a fluid to be measured flowing inside a pipe, and this detector The present invention relates to an electromagnetic conductivity meter using

  Conventionally, as an inductive conductivity detector for measuring the electrical conductivity of a fluid to be measured flowing inside a pipe, a loop including two electrodes in contact with the fluid to be measured and the fluid to be measured between the electrodes as a resistance A detector including an excitation coil and a detection coil arranged in a linkage with respect to a path, and detecting an induced current flowing in a loop path when an AC voltage is applied to the excitation coil It has been known.

  FIG. 7 of Patent Document 1 shows an example of the conventional electromagnetic induction conductivity detector described above. The pipe line (pipe P: the symbol of FIG. 7 of Patent Document 1 is indicated in parentheses below) is the one in which the fluid to be measured (fluid to be measured S) flows inside. In the conduit (P), two ring-shaped electrodes (T11, T12) are arranged as part of the conduit (P). The two electrodes (T11, T12) are connected by a lead (lead LD). Between the two electrodes (T11, T12), a cylindrical insulating pipe (insulating pipe M) made of an insulating material is formed. In the insulating pipe (M), two toroidal coils serving as an exciting coil (C11) and a detecting coil (C12) are disposed in a ring shape so as to surround a part of the insulating pipe (M).

  When an AC power supply (AC) applies an AC voltage to the exciting coil (C11), an induced current is generated in a loop path constituted by the fluid to be measured (S) and the lead (LD) between the two electrodes (T11, T12) (I) flows. The induced current (I) generates an electromotive force in the detection coil (C12), and a voltage corresponding to the electrical conductivity of the fluid to be measured (S) from the amplifier (A) connected to the detection coil (C12) (Eo) is output.

  Since such a detector is used by being incorporated into piping in a factory or piping in other devices, it is necessary to match the inner diameter of the piping into which the detector is incorporated and the inner diameter of the conduit of the detector. Also, in general, the outer diameter of the conduit changes in accordance with the inner diameter. Therefore, in the detector which arranges the toroidal coil on the pipeline between the electrodes, it is necessary to prepare various toroidal coils in accordance with the outer diameter of the pipeline (that is, the outer diameter of the pipe to be incorporated). For this reason, the cost for manufacturing a toroidal coil will increase, and a delivery date will become long. Further, since the number of turns and the size of the toroidal coil are limited depending on the characteristics, it is difficult to manufacture the toroidal coil used particularly for a detector incorporated in a pipe having a large outer diameter.

  On the other hand, in FIGS. 20 to 23 of Patent Document 2, two electrodes which are provided in a pipe line made of an insulator and which are in contact with the fluid to be measured, and these electrodes are connected, and an excitation coil and detection coil (toroidal coil An inductive conductivity detector comprising a wire passing through). In the detector having such a configuration, since the toroidal coil is disposed on the lead wire, the toroidal coil can be selected without considering the outer diameter of the conduit.

JP 9-329633 A Japanese Patent Application Publication No. 2007-518079

  The detector as disclosed in Patent Document 2 does not have to consider the outer diameter of the pipe to which it is incorporated, so for example, it may be incorporated into a large diameter pipe in a factory or a small diameter in another device. It can be freely incorporated into piping. However, on the outside of the detector (pipe line made of insulator), an electrical short circuit (externally connected) via the conductive pipe itself to be incorporated or parts (for example, a solenoid valve and a joint) installed on the pipe If a short circuit occurs, accurate measurement can not be performed.

For example, in the case where an external short circuit occurs in a pipe incorporating a detector as disclosed in Patent Document 2, when the fluid to be measured flows in the detector pipeline, the external short circuit occurs via the fluid to be measured. As a result, it conducts with the electrode of the detector. In this case, a path (external short circuit path) through which an induced current flows is different from the loop path (measurement path) formed by the wire connecting the two electrodes and the fluid to be measured between the two electrodes. Are connected from the outside, and are formed outside the measurement path. The external short circuit path is connected in parallel with the measurement path by using two electrodes as terminals.
In this state, when an alternating voltage is applied to the exciting coil, the induced current flowing through the lead is divided into an induced current flowing through the measurement path and an induced current flowing through the external short circuit path at one electrode. These induced currents merge at the other electrode and flow to the lead wire, causing an electromotive force proportional to the merged induced current to be generated in the detection coil.

  The induced current in the state where the external short circuit occurs is changed according to the resistance in the external short circuit path (hereinafter referred to as "external resistance"), and the induced current in the state where the external short circuit does not occur is The corresponding value is added. Therefore, the electrical conductivity of the fluid to be measured is detected as large as the added portion of the induced current according to the external resistance.

  Here, the external resistance changes according to the material, length, and cross-sectional area of the substance that becomes resistance in the external short circuit path, but the external short circuit is not always generated at a constant site, and in the external short circuit path The elements (resistance of the piping itself and parts on the piping, the electrical conductivity of the fluid in the piping, etc.) are not always constant. Therefore, the value of the external resistance is not always constant. Therefore, even if the calibration of the conductivity meter including the addition is performed at a certain point, if the external resistance fluctuates, the true value of the measured value is deviated. In addition, it is not easily known whether an external short circuit has occurred. For this reason, in the detector as disclosed in Patent Document 2, there is a problem that it is always difficult to measure with high accuracy.

  This invention solves the said subject, The place made into the objective aims at the outer diameter and the structure of the piping in which an electromagnetic induction type electrical conductivity detector is integrated. It is an object of the present invention to provide an inductive conductivity detector capable of stably and accurately measuring without being affected by the above parts and the like, and an inductive conductivity meter using this detector. .

  In order to solve the above problems, an electromagnetic conductivity detector according to the present invention is formed of a tubular insulating pipe made of an insulator, and a pipe through which a fluid to be measured flows inside, and the pipe, A first electrode and a second electrode, which are provided mutually spaced in the longitudinal direction of the conduit and contact the fluid to be measured in the conduit, and the conduit, A third electrode and a fourth electrode which are provided on both sides of the electrode and the second electrode and are in contact with the fluid to be measured in the conduit, and are disposed outside the conduit, A first conducting wire connecting the first electrode and the second electrode, the first conducting wire passing through the center hole of the first conducting wire, and an alternating voltage is applied from an alternating current power supply; Excitation to generate an induced current in a loop path formed by the lead wire and the fluid to be measured in the conduit A coil, a toroidal ring, the first conducting wire passing through the center hole thereof, a detection coil for generating an electromotive force due to the induced current flowing in the loop path, and a coil disposed outside the pipe; And a second conducting wire connecting the third electrode and the fourth electrode.

  According to this configuration, the first electrode and the second electrode disposed on the conduit made of an insulator are electrically connected by the first conductor, and the first conductor, the first electrode, and the first electrode are electrically connected. An electrical path (first loop path) is formed through the fluid to be measured between the two electrodes. In addition, the third electrode and the fourth electrode disposed on the conduit made of an insulator are electrically connected by the second conducting wire, and the first conducting wire, the first electrode, and the third electrode Or an electrical path through the fluid to be measured between the fluid to be measured, the second electric wire, and the fourth electrode (or the third electrode) and the second electrode) A (second loop path) is formed.

  For this reason, the induced current does not flow out to the outside of the third electrode and the fourth electrode, and the value of the induced current flowing in the first lead is always equal to the value of the induced current flowing in the first loop path, The value of the induced current flowing through the second loop path is added, and the value can be made to correspond to the electrical conductivity of the fluid to be measured.

  In the above configuration, the first conducting wire may be passed through the center hole of the exciting coil and / or the center hole of the detecting coil a plurality of times.

  According to this configuration, the induced current flowing in the loop path increases in proportion to the number of times (the number of turns) the first wire forming a part of the loop path passes through the central hole of the exciting coil. Further, the electromotive force generated in the detection coil increases in proportion to the number of times (the number of turns) the first wire passes through the center hole of the detection coil. As a result, the detection sensitivity of the detector can be enhanced without significantly changing the component configuration of the insulating tube, the electrode, the coil, etc., and even if the electrical conductivity of the fluid to be measured is low, the measurement can be performed accurately be able to.

  In the above-described configuration, at least one of the number of times the first wire is passed through the center hole of the exciting coil and the number of times the first wire is passed through the center hole of the detection coil. May be provided with a number-of-turns switching means.

  According to this configuration, the detection sensitivity of the detector can be easily changed by the number-of-turns switching means, and accurate measurement can be easily performed in a wide range from low electric conductivity to high electric conductivity. Can.

  Further, in order to solve the above-mentioned problems, the electromagnetic induction type conductivity meter according to the present invention is constituted by a tubular insulating pipe made of an insulator, and a pipe through which a fluid to be measured flows inside, and the pipe The first electrode and the second electrode which are provided mutually spaced apart in the longitudinal direction of the pipe, and which contact the fluid to be measured in the pipe, and the pipe, A third electrode and a fourth electrode in contact with the fluid to be measured in the conduit, and an electrode disposed on the outside of the conduit, A first conducting wire connecting the first electrode and the second electrode; and an annular ring, the first conducting wire passing through the center hole thereof, and an AC voltage is applied from an AC power supply. To generate an induced current in a loop path formed by the lead 1 and the fluid to be measured in the conduit A coil for detection, an annular coil having a first hole passing through the center hole thereof, a detection coil for generating an electromotive force due to the induced current flowing in the loop path, and a coil disposed outside the pipe A detector having a second lead connecting a third electrode and the fourth electrode, the number of times the first lead passes through the center hole of the excitation coil, and the first lead In the number of times of being passed through the center hole of the detection coil, the number-of-turns switching means for switching at least one of them and the electromotive force generated in the detection coil are converted to measure the electric conductivity of the fluid to be measured. And a converter having an operation unit to be obtained.

  According to this configuration, it is possible to always set the induced current that generates an electromotive force in the detection coil to a value according to the electrical conductivity of the fluid to be measured, and to use the number-of-turns switching means It can be provided outside the detector, and stable and accurate measurement can be easily performed in a wide range from low electric conductivity to high electric conductivity.

  According to the present invention, an electromagnetic induction type conductivity detector capable of stably and accurately measuring without being affected by the outer diameter and configuration of a pipe in which the detector is incorporated, and an electromagnetic using this detector An inductive conductivity meter can be provided.

It is a schematic block diagram of an electromagnetic induction type conductivity meter using an electromagnetic induction type conductivity detector concerning a 1st embodiment of the present invention. It is a schematic block diagram of an electromagnetic induction type conductivity detector concerning a 2nd embodiment of the present invention. It is a schematic block diagram of the electromagnetic induction type conductivity meter concerning a 3rd embodiment of the present invention.

Hereinafter, an electromagnetic induction conductivity meter 10 using an electromagnetic induction conductivity detector 20 (hereinafter referred to as a “detector 20”) according to a first embodiment of the present invention will be described with reference to FIG. explain.
As shown in FIG. 1, the electromagnetic induction type conductivity meter 10 includes a detector 20 and a converter 30 for applying a voltage to the detector 20, performing calculation, control, and the like. The detector 20 is incorporated in an external pipe (not shown) through which the fluid F to be measured flows, such as a pipe in a factory or a pipe in another device, and flows in the detector 20 based on the induced current to be detected. The electrical conductivity of the measurement fluid F is measured.

  The detector 20 has a conduit P through which the fluid to be measured F flows and four electrodes 22, 23, 24, 25 provided in the conduit P at intervals in the longitudinal direction of the conduit P. , A first conducting wire 26 which is a lead wire connecting the two inner electrodes 22 and 23, a second conducting wire 29 which is a lead wire connecting the two outer electrodes 24 and 25, an exciting coil 27 And a detection coil 28.

The pipeline P is formed of an insulating pipe 21 made of an insulator and formed in a cylindrical shape having a constant inner diameter, and from the upstream side, the first insulating pipe 21a, the second insulating pipe 21b, the third insulating pipe 21c, and the third A fourth insulating pipe 21d and a fifth insulating pipe 21e are provided. Inside the conduit P, the fluid to be measured F flows from the upstream end to the downstream end of the conduit P.
The insulating tube 21 is made of, for example, a fluorine resin such as PTFE (polytetrafluoroethylene) or the like, an insulating synthetic resin such as polypropylene, or the like.

  The four electrodes 22 to 25 are formed of a conductive metal and formed in a ring shape having the same inner diameter as the inner diameter of the conduit P. The two inner electrodes 22 and 23 electrically connected by the first conducting wire 26 outside the conduit P are a pair of measurement electrodes, and the first measurement electrode 22 which is the first electrode from the upstream side. And the second measurement electrode 23 which is the second electrode. Further, the two outer electrodes 24 and 25 electrically connected by the second conducting wire 29 outside the conduit P are a pair of guard poles, and a first guard which is a third electrode from the upstream side, respectively. The pole 24 is a second guard pole 25 which is a fourth electrode. That is, the four electrodes 22 to 25 are arranged in the order of the first guard pole 24, the first measurement pole 22, the second measurement pole 23, and the second guard pole 25 from the upstream side of the conduit P.

  These four electrodes 22 to 25 have a first guard pole 24 between the first insulation pipe 21a and the second insulation pipe 21b, and a first measurement pole between the second insulation pipe 21b and the third insulation pipe 21c. The second measurement pole 23 is interposed between the third insulating pipe 21c and the fourth insulating pipe 21d, and the second guard pole 25 is interposed between the fourth insulating pipe 21d and the fifth insulating pipe 21e. The pipes P are arranged at equal intervals in the longitudinal direction of the pipe P.

  With the pipe line P configured in this manner, when the fluid to be measured F does not enter the pipe line P, the first insulating pipe 21a, the second insulating pipe 21b, and the third insulating pipe that are insulators The electrodes 22 to 25 are prevented from conducting to each other in the pipeline P by the 21c, the fourth insulating pipe 21d, and the fifth insulating pipe 21e, and the installation destination connected to both ends of the pipeline P There is no continuity with the piping. Further, since the metal portions of the electrodes 22 to 25 are exposed to the inside of the conduit P, when the fluid to be measured F enters the conduit P, the electrodes 22 to 25 become conductive via the fluid F to be measured.

The exciting coil 27 and the detecting coil 28 are annular toroidal coils in which a conductor such as a copper wire is wound around a toroidal core of an annular magnetic body, and have center holes 27a and 28a, respectively. . The first conducting wire 26 is passed through the center hole 27 a of the exciting coil 27 and the center hole 28 a of the detecting coil 28 once. The exciting coil 27 is disposed on the first measurement pole 22 side, and the detection coil 28 is disposed on the second measurement pole 23 side.
As described above, by arranging the exciting coil 27 and the detecting coil 28 not on the conduit P but on the first conducting wire 26, the exciting coil 27 can be formed without considering the outer diameter of the conduit P. It is possible to select a toroidal coil as the detection coil 28.

  In the detector 20 configured as described above, when the fluid to be measured F flows in the pipe line P, the fluid to be measured F1 between the first measurement electrode 22 and the first measurement electrode 22 and the second measurement electrode 23, and An electrical loop (hereinafter referred to as "first loop path") Lc1 is formed by the two measurement poles 23 and the first conducting wire 26. That is, the first loop path Lc1 to be the loop path is formed by the first conducting wire 26 and the fluid to be measured F1 via the first measurement pole 22 and the second measurement pole 23.

  In addition, the first measurement pole 22, the measured fluid F2a between the first measurement pole 22 and the first guard pole 24, the first guard pole 24, the second conducting wire 29, the second guard pole 25, the second guard pole An electrical loop (hereinafter referred to as "second loop path") Lc2 is formed by the fluid to be measured F2b between the second measurement pole 23 and the second measurement pole 23, the second measurement pole 23, and the first conducting wire 26. . That is, the second loop path Lc2 includes the first conducting wire 26, the fluid to be measured F2a, and the second fluid via the first measurement pole 22, the first guard pole 24, the second guard pole 25 and the second measurement pole 23. The lead wire 29 and the fluid to be measured F2b are formed so that the first loop path Lc1 and a part (the first measurement pole 22, the first lead wire 26, the second measurement pole 23) are common.

  By thus forming the first loop path Lc1 and the second loop path Lc2, the first loop path Lc1 and the second loop path Lc2 can be formed by the exciting coil 27 and the detecting coil 28, and the first conducting wire 26. Each part is linked.

The converter 30 will now be described.
The converter 30 outputs a power supply unit 31 which is an AC power supply, a calculation unit 32 for calculating the electric conductivity, an input unit 33 for inputting various information and settings from the outside, and the electric conductivity and the like to the outside. The output unit 34 and a control unit 35 that controls these units are schematically configured.
The power supply unit 31 is connected to the excitation coil 27 and applies an AC voltage to the excitation coil 27 based on an instruction from the control unit 35.
Arithmetic unit 32 is connected to detection coil 28, amplifies the voltage input from detection coil 28 at a predetermined amplification factor based on an instruction from control unit 35, and refers to information required for the operation with reference to the information. The electric conductivity of the measurement fluid F is obtained.
The input unit 33 is for externally inputting information (reference data of electric conductivity, cell constant, and the like) necessary for calculation, operation setting of the electromagnetic induction type conductivity meter 10, and the like.
The output unit 34 causes the display (not shown) to display the calculation result, various information, settings, etc. received from the calculation unit 32, and outputs the result to an external computer (not shown) or the like.

Next, the operation of the electromagnetic induction type conductivity meter 10 using the detector 20 according to the present embodiment will be described.
When the fluid to be measured F flows in the conduit P, the detector 20 detects the first loop path Lc1 including the fluid to be measured F1 as the resistance r1, the fluid to be measured F2a and the fluid to be measured F2b (hereinafter referred to as “to be measured A second loop path Lc2 is formed, which includes the fluid F2)) as a resistance r2. Here, the resistance r2 is a combination of the resistance r2a of the fluid to be measured F2a and the resistance r2b of the fluid to be measured F2b. The resistance r1 and the resistance r2 are connected in parallel to the first conducting wire 26.
In this state, when an AC voltage is applied to the exciting coil 27 from the power supply unit 31, a first induction current is generated by electromagnetic induction in the first loop path Lc1 and the second loop path Lc2 that interlink with the exciting coil 27. The current i1 and the second induced current i2 flow respectively.
Here, when the flowing direction of each induced current i1 and i2 at a certain timing is the direction shown by the broken line arrow in FIG. 1, the first induced current i1 and the second induced current i2 merge at the second measurement pole 23 , And the first induced current I flows in the first conductor 26. The induced current I is divided into a first induced current i1 and a second induced current i2 at the first measurement pole 22.

At this time, the value of the first induction current i1 flowing in the first loop path Lc1 and the value of the second induction current i2 flowing in the second loop path Lc2 are the fluid to be measured F1 that each loop path Lc1, Lc2 includes as a resistance And F2 are determined by the values of the resistances r1 and r2 (the values corresponding to the electric conductivity of the fluid to be measured F). Here, the resistance value of the fluid is inversely proportional to the cross-sectional area of the fluid and proportional to the length of the fluid. In the present embodiment, the inner diameter of the conduit P is constant (the cross-sectional area of the fluid to be measured is constant). Because of this, the values of the resistances r1 and r2 are proportional to the length of the fluid to be measured F1 and F2.
Further, in the present embodiment, since the electrodes 22 to 25 are arranged at equal intervals, assuming that the value of the resistance r1 of the fluid to be measured F1 is R, the value of the resistance r2 of the fluid to be measured F2 is 2R Become. Assuming that the electromotive force induced in the first conducting wire 26 is V, the value of the first induction current i1 is V / R, and the value of the second induction current i2 is V / 2R.

  And since the first induction current i1 and the second induction current i2 merge at the second measurement pole 23, the value of the induction current I flowing through the first conducting wire 26 is the value of the first induction current i1 and the second induction It becomes 3V / 2R which added the value of electric current i2. That is, the value of the induced current I flowing through the first conductor 26 is always equal to the value of the first induced current i1 flowing through the first loop path Lc1, and the value of the second induced current i2 flowing through the second loop path Lc2 is It will be added.

Thus, the excitation coil 27 and the detection coil 28 are not on the pipe line P between the measurement poles 22 and 23 but on the first conducting wire 26 connecting the measurement poles 22 and 23 outside the pipe line P. When arranged, the induced current I flowing through the first conducting wire 26 also flows out of the measuring electrodes 22, 23 via the measuring electrodes 22, 23 and the fluid F to be measured. In this state, if there is no first guard pole 24 and second guard pole 25 and an electrical short circuit (external short circuit) has occurred in the pipe to be incorporated, the measurement poles 22 and 23 and the fluid F to be measured are As a result, the external short circuit and the first conductor 26 form an external short circuit path through which the induced current flows. In this case, the value of the induced current I flowing through the first conducting wire 26 is obtained by adding the value of the induced current flowing through the external short circuit path to the value of the first induced current i1 flowing through the first loop path Lc1. As described above, since the value of the resistance (external resistance) in the external short circuit path is not necessarily constant, when the external resistance fluctuates, the true value of the measured value is shifted.
However, as in the present embodiment, the first guard pole 24 and the second guard pole 25 are provided, and these are electrically connected by the second conducting wire 29 so that the second loop path Lc2 is formed. In this case, the induced current that has flowed out of the measurement poles 22 and 23 does not flow to the outside of the guard poles 24 and 25 through the second loop path Lc2. Therefore, the value of the induced current I flowing through the first conducting wire 26 is obtained by adding the value of the second induced current i2 flowing through the second loop path Lc2 to the value of the first induced current i1 flowing through the first loop path Lc1 Therefore, the value can always be set to a value corresponding to the resistance value (electrical conductivity) of the fluid F to be measured.

Then, since both the first loop path Lc1 and the second loop path Lc2 are linked to the detection coil 28 at the first conducting wire 26, the detection coil 28 is caused by electromagnetic induction by the induced current I. Power is induced. The electromotive force is a value proportional to the electrical conductivity of the fluid F to be measured.
The voltage value of the electromotive force is input to the calculation unit 32 connected to the detection coil 28. Then, the input voltage value is calculated by the calculation unit 32, and the electrical conductivity of the fluid F to be measured is obtained.

  As described above, in the electromagnetic induction type conductivity meter 10 using the detector 20 according to the present embodiment, the first guard pole 24 and the second guard pole 24 are arranged so as to sandwich the first measurement pole 22 and the second measurement pole 23. By arranging the guard pole 25 and connecting the first guard pole 24 and the second guard pole 25 with the second conducting wire 29, when the fluid to be measured F flows inside the conduit P, the second loop path Lc 2 Is configured. The value of the first induction current i1 flowing in the first loop path Lc1 and the value of the second induction current i2 flowing in the second loop path Lc2 both have values corresponding to the electrical conductivity of the fluid F to be measured. It is possible to always set the value of the induced current I that generates an electromotive force in the coil 28 to a value according to the electrical conductivity of the fluid F to be measured. Therefore, in the electromagnetic induction type conductivity meter 10 using the detector 20 according to the present embodiment, it is possible to stably and accurately measure the conductivity without being affected by the piping configuration to which it is incorporated. Can.

In the present embodiment, the pipe line P includes the insulating pipe 21 formed of the first to fifth insulating pipes 21a to 21e. However, the present invention is not limited to this. It can design suitably according to the method of installation, for example, the insulation pipe 21 may be one member.
Further, the intervals between the electrodes 22 to 25 are not limited to equal intervals.
Furthermore, the shape of each of the electrodes 22 to 25 is not limited to a ring shape, and may be provided in any shape as long as part of each of the electrodes 22 to 25 is in contact with the fluid F to be measured.

  Next, an electrical conductivity detector 120 (hereinafter referred to as a “detector 120”) according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the same members as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 2, a detector 120 according to the second embodiment differs from the first embodiment in the wiring of the first conducting wire 126.
The first conducting wire 126, which is a lead wire electrically connecting the first measurement pole 22 and the second measurement pole 23, includes the center hole 27a of the excitation coil 27 and the center hole 28a of the detection coil 28, and The coil 27 and the detection coil 28 are rotated twice around the outside of the coil 27 and through the center hole 27 a of the excitation coil 27 and the center hole 28 a of the detection coil 28 three times each. That is, the first loop path Lc1 and the second loop path Lc2 are linked to the exciting coil 27 and the detecting coil 28 three times each at the first conducting wire 126 portion.

  Hereinafter, a state in which the first conducting wire 126 passes through the center hole 27a of the excitation coil 27 and the center hole 28a of the detection coil 28 once each will be described as one turn. In the present embodiment, the first conducting wire 126 is in a state of three turns passing through the center hole 27a of the excitation coil 27 and the center hole 28a of the detection coil 28 three times each.

  In this state, when an AC voltage is applied to the exciting coil 27 from the power supply unit 31, the loop paths Lc1 and Lc2 are interlinked with the exciting coil 27 three times, so the first conducting wire 126 Three times the induced current I flows as in one turn. Further, since each of the loop paths Lc1 and Lc2 is linked to the detection coil 28 three times, an electromotive force three times as large as that in one turn is generated in the detection coil 28.

  That is, an induced current I which is three times that of one turn flows in the first conducting wire 126 that forms a part of each of the loop paths Lc1 and Lc2, and three times that of one turning is flowing in the detection coil 28. Since an electromotive force is generated, the electromotive force generated in the detection coil 28 by the induced current I is nine times that in one turn. That is, the detector 120 according to the present embodiment can increase the detection sensitivity by the product of the number of turns for the excitation coil 27 and the number of turns for the detection coil 28.

  As described above, the induced current I flowing through the first conducting wire 126 common to the loop paths Lc1 and Lc2 increases in proportion to the number of turns for the exciting coil 27, and the electromotive force generated in the detection coil 28 is detected It increases in proportion to the number of turns for the coil 28.

In general, as a method of increasing the detection sensitivity of a so-called piping type electromagnetic induction type conductivity detector as in the present embodiment, the first measurement pole in which the inner diameter of the pipeline P through which the fluid F to be measured flows is increased. The configuration of the detector 120 or converter such as shortening the distance between the second measurement pole 23 and the second measurement pole 23, increasing the applied AC voltage, and adjusting the number of turns of the excitation coil 27 or detection coil 28 It is known how to make major changes.
On the other hand, in the detector 120 according to the present embodiment, the number of times the first conducting wire 126 is passed through each of the central hole 27a of the exciting coil 27 and the central hole 28a of the detecting coil 28 is increased. The detection sensitivity can be enhanced, and the use of this detector 120 can provide an electromagnetic conductivity meter 110 having high detection sensitivity.

  In the present embodiment, the number of turns for the exciting coil 27 and the number of turns for the detecting coil 28 may be the same number or different numbers. For example, when the number of turns for the excitation coil 27 is three and the number of turns for the detection coil 28 is one, the electromotive force generated in the detection coil 28 is three times that for one turn.

  Next, an electromagnetic conductivity meter 210 according to a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the same members as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 3, the first measurement pole 22 and the second measurement pole 23 are connected to a first conductive wire 226 which is a lead wire disposed outside the conduit P. The first conducting wire 226 is passed through the center hole 27 a of the exciting coil 27 and the center hole 28 a of the detecting coil 28 three times each as in the second embodiment.

  Similar to the first embodiment, the converter 230 includes a power supply unit 231, an operation unit 232, an input unit 233, an output unit 234, and a control unit 235, and is a relay to which the first conducting wire 226 is further connected. A switch 236 is provided. The switch 236 constitutes a first loop path Lc1 together with the first conductor 226 and the fluid to be measured F1, and constitutes a second loop path Lc2 together with the first conductor 226, the fluid to be measured F2 and the second conductor 29. Do. The switch 236 is a turn number switching unit that switches the number of turns to the excitation coil 27 and the detection coil 28 of the loop paths Lc1 and Lc2 based on an instruction from the control unit 235. The switch 236 is provided with one common terminal 236a and three selection terminals 236b, 236c and 236d.

  The switch 236 is disposed between the second measurement pole 23 and the central hole 28 a of the detection coil 28 in the first conducting wire 226. The common terminal 236a of the switch 236 is connected to the second measurement pole 23 by the first conducting wire 226a. To the selection terminal 236b, a first conducting wire 226b extending to the central hole 28a of the detection coil 28 is connected. The first conducting wire 226 b extending from the selection terminal 236 b makes two and half turns around the center hole 28 a of the detection coil 28, the center hole 27 a of the excitation coil 27, and the outside of the excitation coil 27 and the detection coil 28. At the same time, each branch is branched, and the branch terminal is connected to the selection terminal 223c and the selection terminal 223d of the switch 236, respectively.

In this state, when the common terminal 236a of the switch 6 is connected to the selection terminal 236b, the first measurement pole 22 and the second measurement pole 23 are electrically connected by the first conducting wires 226a and 226b and the switch 236. Be done. Then, when an AC voltage is applied to the exciting coil 27 from the power supply unit 231, the loop paths Lc1 and Lc2 are in a state of three turns. Similarly, when the common terminal 236a of the switch 236 is connected to the selection terminal 236c, the loop paths Lc1 and Lc2 are in the state of two turns, and when the common terminal 236a of the switch 236 is connected to the selection terminal 236d, the loop path Lc1 and Lc2 are in the state of one turn.
That is, when the common terminal 236a of the switch 236 is connected to the selection terminal 236b, the detection sensitivity of the detector 220 is 9 of one turn (the common terminal 236a of the switch 236 is connected to the selection terminal 236d). When the common terminal 236a of the switch 236 is connected to the selection terminal 236c, the detection sensitivity of the detector 220 is four times the state of one turn.

  Thus, in the electromagnetic induction type conductivity meter 210 according to the present embodiment, the number of turns of the loop paths Lc1 and Lc2 (the number of turns of the loop paths Lc1 and Lc2) is obtained by interposing the switch 236 which is the number of turns switching means in the first lead wire 226. That is, it is possible to easily change the number of times the first conducting wire 226 passes through the center hole 27a of the excitation coil 27 and the center hole 28a of the detection coil 28. Therefore, by switching the switch 236, the detection sensitivity of the detector 220 can be easily selected from a plurality of detection sensitivities, for example, 1 ×, 4 ×, and 9 ×. Therefore, the detector 220 capable of measuring the electrical conductivity in a wide range from low electrical conductivity to high electrical conductivity, and the electromagnetic induction conductivity meter 210 using the same can be obtained.

In the present embodiment, the number of turns for the excitation coil 27 and the number of turns for the detection coil 28 may be different numbers as in the second embodiment.
Further, the position of the switch 236 is not limited to the position of the present embodiment. It may be possible to switch the number of times the first conducting wire 226 passes through the center hole 27a of the excitation coil 27 and the center hole 28a of the detection coil 28, respectively.
Furthermore, although the number of switches 236 is one in this embodiment, the number of switches 236 is not limited to this. For example, the number of turns for the exciting coil 27 and the number of turns for the detecting coil 28 are switched. And two may be provided.
Furthermore, the switch 236 may be any switch that can switch contacts, and may be, for example, a semiconductor switch such as an IC or a dip switch.
In the present embodiment, the switch 236 is provided in the converter 230, but may be provided in the detector 220 or may be a separate unit. Further, although the switch 236 is described as being switched based on an instruction from the control unit 35, it may be switched manually. Furthermore, the switching instruction from the control unit 35 to the switch 236 may be based on a preset condition or may be based on an input from the input unit 33.

The above-mentioned electromagnetic induction type conductivity meter 10, 110, 210 can also be used for an electromagnetic densitometer which measures the concentration of a specific substance of the fluid S to be measured by converting the conductivity into a concentration.
Moreover, the electromagnetic induction type conductivity meter 10, 110, 210 is equipped with a thermometer in the detectors 20, 120, 220, and can measure the temperature-compensated conductivity and the concentration of a specific substance. Is preferred.

  Hereinafter, examples for clarifying the effects of the present invention will be shown. In the following examples, potassium chloride aqueous solution (KCl solution) was used as the fluid to be measured F. Moreover, the liquid temperature of potassium chloride aqueous solution was kept at 25 degreeC, and measured in any case, without performing temperature compensation. Furthermore, the intervals between the electrodes 22 to 25 are the same, and the number of turns for the exciting coil 27 and the detecting coil 28 is one turn unless otherwise specified.

First, the aqueous solution of potassium chloride was measured using a reference conductivity meter (a conductivity and pH meter WM-50EG manufactured by Toa DKK). The electrical conductivity at this time was 12 mS / cm.
Next, an electromagnetic conductivity meter configured in the same manner as in the first embodiment (FIG. 1) is prepared, and the potassium chloride aqueous solution is measured in a state where the second lead wire 29 is not connected. The instructions were adjusted to 12 mS / cm.

(A) The electric conductivity of the aqueous solution of potassium chloride was measured in the state where the second conducting wire 29 was connected (the first embodiment, the same configuration as FIG. 1). The electrical conductivity at this time was 18 mS / cm, which was 1.5 times the electrical conductivity in the state where the second conducting wire 29 was not connected. As described above, when the distance between the electrodes 22 to 25 is the same, the induced current I flowing through the first conducting wire 26 is 3 V / 2 R (V: applied voltage, R: resistance of the fluid to be measured). The state in which the lead wire 29 is connected is 1.5 times the state in which the wire 29 is not connected, but the same result was obtained.
(B) Next, the electrical conductivity of the aqueous potassium chloride solution was measured in a state in which both ends of the conduit P were shorted with a jumper wire so as to sandwich the first guard pole 24 and the second guard pole 25. The electrical conductivity at this time was 18 mS / cm, and it was found that the electrical conductivity can be accurately measured without being affected by the presence or absence of a short circuit outside the conduit P.
(C) Next, with the detector (1 turn) of the electromagnetic induction type conductivity meter which passes the first conducting wire 26 through the center holes 27a and 28a of the exciting coil 27 and the detecting coil 28 once, An aqueous solution of potassium chloride was measured. The electrical conductivity at this time was 10 mS / cm. Next, using the same detector, the first conductor 26 is passed twice through the excitation coil 27 and the center holes 27a and 28a of the detection coil 28 (2 turns) and 3 times (when The electrical conductivity of the aqueous solution of potassium chloride was measured in three turns. As a result, it was found that the value of 40 mS / cm in the case of 2 turns and 90 mS / cm (3 turns) in the case of 3 turns was exhibited, and the measurement sensitivity was improved by the ratio of the number of turns.

F ... measured fluid, P ... pipeline, Lc 1 ... first loop path (loop path), Lc 2 ... second loop path, I ... induced current, i 1 ... first induced current, i 2 ... second induced current,
10, 110, 210 ... electromagnetic induction type conductivity meter, 20, 120, 220 ... detector (electromagnetic induction type conductivity detector), 21 ... insulating pipe, 22 ... first measurement pole (first electrode) , 23: second measurement electrode (second electrode), 24: first guard electrode (third electrode), 25: second guard electrode (fourth electrode), 26, 126, 226, first wire 27: Excitation coil 27a: Center hole 28: Detection coil 28a: Center hole 29: Second conductor 30: 230 Converter 31: 231 Power source (AC power supply) 32, 32 232: Arithmetic unit, 33: Input unit, 34: Output unit, 35: Control unit, 236: Switch (turn number switching means).

Claims (4)

A pipe line constituted by a tubular insulating pipe made of an insulator and through which the fluid to be measured flows;
A first electrode and a second electrode which are provided in the pipe line mutually spaced in the longitudinal direction of the pipe line and in contact with the fluid to be measured in the pipe line;
A third electrode and a fourth electrode which are provided in the pipe with the first electrode and the second electrode interposed therebetween and which are in contact with the fluid to be measured in the pipe;
A first conducting wire disposed outside the pipeline and connecting the first electrode and the second electrode;
A loop formed by the first conducting wire and the fluid to be measured in the pipeline by being annular and having the first conducting wire passing through the center hole thereof and applying an AC voltage from an AC power supply An excitation coil that generates an induced current in the path;
A detection coil which has an annular shape, the first conductor passes through the center hole thereof, and an electromotive force is generated by the induced current flowing in the loop path;
A second conducting wire disposed outside the pipeline and connecting the third electrode and the fourth electrode;
An electromagnetic conductivity detector comprising:   The electromagnetic induction type electric motor according to claim 1, wherein the first conducting wire is passed through the center hole of the exciting coil and / or the center hole of the detecting coil a plurality of times. Conductivity detector.   Furthermore, the number of turns for switching at least one of the number of times the first conducting wire passes through the center hole of the exciting coil and the number of times the first conducting wire passes through the center hole of the detection coil The electromagnetic induction conductivity detector according to claim 2, further comprising: switching means. A pipe line constituted by a tubular insulating pipe made of an insulator and through which the fluid to be measured flows;
A first electrode and a second electrode which are provided in the pipe line mutually spaced in the longitudinal direction of the pipe line and in contact with the fluid to be measured in the pipe line;
A third electrode and a fourth electrode which are provided in the pipe with the first electrode and the second electrode interposed therebetween and which are in contact with the fluid to be measured in the pipe;
A first conducting wire disposed outside the pipeline and connecting the first electrode and the second electrode;
A loop formed by the first conducting wire and the fluid to be measured in the pipeline by being annular and having the first conducting wire passing through the center hole thereof and applying an AC voltage from an AC power supply An excitation coil that generates an induced current in the path;
A detection coil which has an annular shape, the first conductor passes through the center hole thereof, and an electromotive force is generated by the induced current flowing in the loop path;
A detector disposed outside the conduit and having a second conducting wire connecting the third electrode and the fourth electrode;
Switching means for switching at least one of the number of times the first wire is passed through the center hole of the excitation coil and the number of times the first wire is passed through the center hole of the detection coil When,
A converter having a calculation unit which converts an electromotive force generated in the detection coil to obtain an electric conductivity of the fluid to be measured;
An electromagnetic conductivity meter comprising:

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