JP2001183312A - Concentration meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized concentration meter capable of accurately measuring the density of a fluid to be measured by efficiently propagating an electromagnetic energy into a liquid containing a suspended substance. SOLUTION: In the densitometer, a microwave transmitting and receiving system is oppositely disposed to a detecting tube or a detecting container. An opening window is formed in a columnar shape so as to be opposed to the tube or the container. An antenna mounting insulator is airtightly mounted in the window. A microwave transmitting and receiving antenna is closely mounted at the insulator. Thus, the concentration meter measures the phase delay of a microwave passing through a material to be measured in the tube or the container and measured the concentration of the material. In this case, the radius r of the window satisfies (0.293λ/√εr)<r<(0.485λ/√εr), wherein λis the wavelength of the desired frequency, and εr is the permittivity of the insulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the concentration of suspended substances,
For example, the present invention relates to a densitometer for measuring the concentration of a fluid containing various substances and various soluble substances using sludge, pulp, and other substances using a microwave. The present invention relates to a densitometer provided with a microwave transmitting and receiving antenna capable of transmitting electromagnetic energy and accurately measuring the concentration of a fluid to be measured.

[0002]

2. Description of the Related Art Conventionally, as a device for measuring the concentration of a suspended substance or the like in a liquid, an ultrasonic densitometer for measuring the concentration by measuring the attenuation rate of an ultrasonic wave, a transmitted light attenuation ratio using light, or the like. Optical densitometers that measure a scattered light increase rate to obtain a densitometer are widely used.

However, in the case of an ultrasonic densitometer, if air bubbles are mixed in the liquid, the influence of the air bubbles is greatly affected and the measurement error is increased. If dirt or the like adheres to the optical window for light reception, it is greatly affected by the dirt and the measurement error increases.

Therefore, recently, as a densitometer which is hardly affected by dirt on the optical bubble window in the liquid, a microwave type densitometer has been considered and put into practical use.

FIG. 21 shows a schematic configuration of such a microwave type concentration measuring apparatus. A microwave transmitting antenna 2 and a microwave receiving antenna 3 are provided on a side wall of a pipe 1 through which a liquid to be measured passes. Are arranged facing each other, the microwave from the microwave oscillator 4 is input to the microwave transmitting antenna 2 via the power splitter 5, and the microwave transmitted from the microwave transmitting antenna 2 is The liquid to be measured is propagated, received by the microwave receiving antenna 3 and input to the phase difference measuring circuit 6, while the microwave from the microwave oscillator 4 is supplied to the power splitter 5.
Is input directly to the phase difference measuring circuit 6 via the. The phase difference measuring circuit 6 calculates the phase delay θ2 of the microwave propagating through the liquid to be measured in the pipe 1 with respect to the microwave directly received from the microwave oscillator 4 through the power splitter 5, and further calculates the phase delay. Compare θ2 with the phase delay θ1 when the pipe 1 is previously filled with a reference liquid (for example, tap water that can be regarded as having a concentration of zero) and microwaves that propagate in the reference liquid in the same state as the liquid to be measured are measured. And the phase difference Δθ = (θ2−θ
From 1), the concentration X of the liquid to be measured is obtained using a calibration curve as shown in FIG. Specifically, the concentration X is obtained by a calibration curve X = a corresponding to each type of the liquid to be measured.
It is determined based on Δθ + b. Here, a is the slope of the calibration curve, b is the intercept of the calibration curve, and b is usually 0.

According to such a microwave type densitometer measuring apparatus, the phase difference is measured instead of measuring the attenuation rate of the microwave, and the window through which the microwave is incident or received is transparent. Since there is no necessity, it is hardly affected by bubbles and dirt, and it is possible to continuously detect the concentration of the liquid to be measured.

[0007] Japanese Patent Application Laid-Open No. 11-83758 discloses a technique in which a microwave transmission system and a reception system are arranged opposite to a detection tube or a detection container, and the microwave is used as a reference in the detection tube or the detection container. The first obtained by propagating microwaves
And the second phase delay obtained by propagating the microwave in the measurement fluid containing the substance to be measured in the detection tube or the detection container to determine the phase difference,
The invention relates to a densitometer for measuring the concentration of a fluid to be measured from the phase difference. In the present invention, a specific configuration of the densitometer is shown. First, an opening window for microwave transmission and reception is formed at a position facing each other across the tube axis of the detection tube or the detection container, and an antenna is attached to this opening window via an airtight seal packing. Plate is installed. Further, a transmitting antenna and a receiving antenna are individually attached to the antenna mounting plate, and a dielectric material is filled in openings of the transmitting antenna and the receiving antenna, thereby forming the microwave transmitting system and the receiving system. . The transmission system and the reception system of the microwave have a microwave frequency of 1.7 GHz or more.
A first phase delay and a second phase delay are obtained using a microwave in a frequency range of 2.0 GHz, and a phase difference is measured from each of the phase delays.

Here, in particular, by using a dielectric having a relative permittivity of 21 ± 1 as the dielectric, the concentration resolution can be increased, and the concentration of the specific measurement fluid can be measured more accurately than in the past. States what can be done.

Further, by filling the openings of the transmitting antenna and the receiving antenna with a dielectric such as ceramics, the transmitting antenna and the receiving antenna can be downsized and the dielectric constant is high (about 80) as compared with the prior art. It also states that impedance matching with the device under test can be facilitated.

FIG. 23 is a sectional view showing an example of a configuration of a conventional main part.

In FIG. 23, open windows 23a and 23'a for microwave transmission and reception are formed at positions facing each other across the tube axis of the detection tube 1. In addition, antenna mounting plates 23c and 23'c are attached to the opening windows 23a and 23'a via airtight seal packings 23b and 23'b.

Here, the antenna mounting plate 23c, 2
As 3′c, as shown in FIG. 23, the insulators 23d and 23′d are fitted or the whole is made of an insulator so as to maintain the airtightness of the microwave transmission port and the reception port. It is preferred to use. Insulators 23d, 23 '
For d, since a liquid containing a suspended substance, which is an object to be measured, in the detection tube 1 is flowing, stress resistance, pressure resistance, heat resistance, and the like are required. As a result, the structure becomes thick, and the insulators 23d, 2
In fact, the effect of 3′d cannot be ignored, and the concentration resolution cannot be increased to accurately measure the concentration of the specific measurement fluid.

The structure of the transmitting antenna 28 and the receiving antenna 29 shown in FIG.

FIG. 24 shows a first quarter wavelength monopole antenna. The antenna elements 7a and 7b are provided on the bottom surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b.
This is a linear monopole antenna having a contact surface (5c) with the ground as a ground. The length of the antenna elements 7a, 7b is a quarter wavelength of the desired frequency. The power supply unit F is provided vertically at the contact point between the contact surface (5c) and the antenna elements 7a and 7b.

FIG. 25 shows a second quarter wavelength monopole antenna. The antenna elements 8a and 8b are connected to the side surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b.
b (5d) is grounded, and the antenna 5a,
This is a linear monopole antenna arranged on the contact surface (5e) between the upper surface of 5b and the opening windows 2a, 2b. The length of the antenna elements 7a, 7b is a quarter wavelength of the desired frequency. It is configured vertically from the feeder F at the contact point between the contact surface 5d and the antenna element 7.

FIG. 26 shows a dipole antenna. The antenna elements 9a and 9b are formed at the center of the antennas 5a and 5b on the contact surface (5e) between the upper surfaces of the antennas 5a and 5b and the opening windows 2a and 2b. Antenna elements 9a, 9b
Is half the wavelength of the desired frequency.

[0017]

Conventionally, an antenna is
The oscillatory electromagnetic energy generated by the oscillator is efficiently converted from an electric circuit including a transmission line to an electromagnetic wave propagating in space so as to meet a certain purpose, that is, the electromagnetic wave is radiated, or conversely, the electromagnetic wave is converted into an electric wave including the transmission line. It is a device that efficiently converts to circuit energy. The space is generally in the air, but is underwater in the case of a densitometer antenna. Until now, sound waves and the like have been used to radiate vibration energy into water, but microwaves are rarely used. This is because the relative permittivity of water is as high as about 80, so that electromagnetic energy is difficult to propagate, and there is a problem that the matching between the antenna and the water must be improved.

Here, the structure of the antenna which is easily analogized and the problems will be described.

FIG. 24 shows a first quarter-wave type monopole antenna. The antenna elements 7a and 7b are provided on the bottom surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b.
This is a linear monopole antenna having a contact surface (5c) with the ground as a ground. The length of the antenna elements 7a, 7b is a quarter wavelength of the desired frequency. The power supply unit F is provided vertically at the contact point between the contact surface (5c) and the antenna elements 7a and 7b.

In this method, the directivity of the antenna is directed toward the wall surfaces (5d) of the antenna mounting cases 4a and 4b. Further, an electric field is hardly generated in the opening windows 2a and 2b in which only the TE10 mode can be generated in a direction perpendicular to the contact surface 5c, and impedance matching is hardly performed. Therefore, there is a problem that electric power cannot be efficiently transmitted to the liquid containing the suspended substance, which is the object to be measured.

FIG. 25 shows a second quarter wavelength monopole antenna. The antenna elements 8a and 8b are connected to the side surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b.
b (5d) is grounded, and the antenna 5a,
This is a linear monopole antenna arranged on the contact surface (5e) between the upper surface of 5b and the opening windows 2a, 2b. The length of the antenna elements 7a, 7b is a quarter wavelength of the desired frequency. It is configured vertically from the feeder F at the contact point between the contact surface 5d and the antenna element 7.

In this method, the ground (5d) of the antenna elements 8a and 8b becomes a curved surface, and the mechanical configuration becomes complicated. Further, there is a problem that the matching is not good at a desired frequency due to the influence of the curved surface.

FIG. 26 shows a dipole antenna. The antenna elements 9a and 9b are formed at the center of the antennas 5a and 5b on the contact surface (5e) between the upper surfaces of the antennas 5a and 5b and the opening windows 2a and 2b. Antenna elements 9a, 9b
Is half the wavelength of the desired frequency.

This method is difficult to realize because power cannot be supplied from outside without contacting the detection tube 1. in this way,
There is a problem that it is difficult to obtain good performance with an antenna different from the embodiments described below.

The inner diameter of the pipe through which the fluid flows is set within a certain range (for example, 100 mm to 30 mm) depending on the installation place of the concentration meter.
0 mm), there is a problem that it cannot be freely selected.

Further, in order to allow a fluid to flow, stress resistance, pressure resistance,
Heat resistance is required. Therefore, an insulator is necessary between the contact surface of the antenna and the liquid containing the suspended substance, but the electromagnetic energy propagates in the liquid containing the suspended substance.
There is a problem that the shape and material constant of the protective material, especially the dielectric constant and the loss were not taken into account.

According to the present invention, in order to solve such a problem, to reduce the size and enhance the concentration resolution, the electromagnetic energy is efficiently propagated into the liquid containing the suspended substance, and the concentration of the fluid to be measured is measured with high accuracy. It is an object of the present invention to provide a densitometer capable of performing the measurement.

[0028]

In order to solve the above-mentioned problems, the present invention has a microwave transmitting / receiving system disposed opposite to a detecting tube or a detecting container, and the detecting tube or the detecting container is opposed to the detecting tube or the detecting container. The opening window is formed in a cylindrical shape so that the antenna mounting insulator is hermetically attached to the opening window, and the microwave transmitting / receiving antenna is closely attached to the antenna mounting insulator, and the detection is performed. In a densitometer for measuring the phase delay of a microwave passing through an object to be measured in a vessel or a container for detection and measuring the concentration of the object to be measured, a wavelength of a desired frequency is λ, the insulator for mounting the antenna, Is the relative dielectric constant of ε _r , the radius r of the opening window is (0.293λ / √ε _r ) <r <(0.4
85λ / √ε _r ).

Further, a microwave transmission / reception system is opposed to the detection tube or the detection container, and at least two or more cylindrical columns having different radii are provided so as to face the detection tube or the detection container. In addition to being formed in a stacked form, an antenna mounting insulator is hermetically attached to the opening window, the microwave transmitting / receiving system antenna is closely attached to the antenna mounting insulator, and the detection tube or the detection In a densitometer for measuring the phase delay of the microwave passing through the object to be measured in the container and measuring the concentration of the object to be measured, the wavelength of a desired frequency is λ, and the relative permittivity of the insulator for mounting the antenna is ε. When _r, of the opening window portion formed in the shape of repeated different radii cylinder, the radius r of the cylinder of the opening window portion of the object side (0.293λ / √
ε _r ) <r <(0.485λ / √ε _r ).

Further, the opening window is formed by stacking three or more cylinders having different radii on each other, and at least one of the inner cylinders with respect to the radius of the cylinder of the opening window closest to the object to be measured. It is characterized in that one radius is large.

The microwave transmission / reception system antenna is a linear monopole antenna having a length of three quarters of a desired frequency, and is formed in an inverted L-shape from a feeding part.
The length from the power supply section to the L-shaped bend is a quarter wavelength of the desired frequency, and the length from the L-shaped bend to the open end is a half wavelength of the desired frequency. It is characterized by.

Further, in the present invention, the microwave transmitting and receiving system antenna is characterized in that a side having an open end of the linear monopole antenna is mounted so as to be perpendicular to a side surface of the opening window.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view (FIG. 1A) and a cross-sectional view (FIG. 1B) of an example of a configuration of a main part according to an embodiment of the present invention as viewed from an oblique direction. For other configurations, see FIG.
Since it is the same as the densitometer shown in FIG.

In FIG. 1A, open windows 2a and 2b for microwave transmission and reception are formed at positions facing each other across the tube axis of the detection tube 1. In addition, the opening windows 2a and 2b are provided with an antenna mounting housing 4a containing a transmitting antenna 5a and a receiving antenna 5b via airtight seal packings 3a and 3b.
4b (FIG. 1C). Here, the opening window 2a
And 2b are filled with insulating parts.

FIGS. 2 and 3 show examples of the antenna elements of the antennas 5a and 5b. 2 and 3, the antenna elements 6a and 6b are linear monopole antennas whose ground is a contact surface 5c between the bottom surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b. It is formed in an inverted L-shape from a feeding part F at a contact point between the contact surface 5c and the antenna element 6.

Here, the insulating portions in the opening windows 2a and 2b, the transmitting antenna 5a and the receiving antenna 5b are formed by filling an antenna element with a dielectric material in order to make it easy to reduce the size. Further, when forming the opening windows 2a and 2b, a hole is actually made by drilling, and a columnar type (FIG. 1)
D) is simpler, and there is no fear that a large stress or pressure is applied locally such as at a corner as compared with a polygon. Therefore, it is preferable that the transmitting antenna 5a and the receiving antenna 5b are also formed in a cylindrical shape. Since the fluid flows through the insulating portions in the opening windows 2a and 2b, stress resistance, pressure resistance, heat resistance, and the like are required. Therefore, it is necessary to increase the thickness, which is a kind of a circular waveguide in which the cross section is circular, surrounded by a metal surface, and filled with a dielectric. The fundamental mode of the cylindrical waveguide is TE11,
Conditions for transmission

(Equation 1) subscripts a of y _ab represents the order of the Bessel function _{J a,} b
Indicates a number in which the numbers of the root _yab are arranged in ascending order. For example, y ₁₁ ≒ 1.84, relative dielectric constant 15 in the cylindrical waveguide, wavelength λ = 157.9 [mm] (1.9 GH)
z), the radius must be r> 12.5 [mm]. If the radius is smaller than 12.5 [mm], the cutoff frequency becomes higher than 1.9 GHz, and electromagnetic energy cannot be propagated in the cylindrical waveguide. Note that the inner diameter of the detection tube 1 is determined within a certain range (for example, 100 mm to 300 mm) according to the installation place of the densitometer, and thus there is a problem that it cannot be freely selected. In this case, the relative permittivity of the insulating portions in the opening windows 2a and 2b may be adjusted.

Therefore, it is important that only the TE11 wave can be transmitted. The condition under which only the TE11 wave can be transmitted is determined by determining the condition under which the TE11 wave can propagate and the condition under which the TE21 wave, which is the next higher-order mode, cannot be transmitted.
Can be identified. The conditions under which TE21 waves cannot be transmitted are:

(Equation 2) For example, y ₂₁ ≒ 3.05, relative dielectric constant 1 in a cylindrical waveguide
5. If the wavelength λ = 157.9 [mm] (at 1.9 GHz), the radius r <19.8 [mm].

When the radius r is 12.5 <r <19.8 [m
m] and a relative dielectric constant of 15, only 1.9 GHz and TE11 waves can propagate as electromagnetic energy in the cylindrical waveguide.

As described above, according to the present invention, the opening window 2a
And 2b are made of a cylindrical waveguide filled with a dielectric, so that the effect of the cutoff frequency is taken into consideration and the opening window 2
It is possible to realize a densitometer in which electromagnetic energy of a desired frequency propagates in the insulating portions in a and 2b with TE11 waves as a fundamental mode.

FIG. 4 shows an example of the configuration of a main part according to the second embodiment of the present invention. Since the other configuration is the same as that of the densitometer shown in FIG. 21, the illustration and description thereof are omitted here. Further, only the differences from the embodiment shown in FIG.

FIG. 4 shows that the insulating portions in the opening windows 2a and 2b are constituted by two cylinders (10a and 10b), and the side 6c of the antenna elements 6a and 6b having an open end is determined by the diameter of the antennas 5a and 5b. It is slightly smaller. TE1
The electric field component of one wave is shown in FIG. 5 which is a cross-sectional view of the cylindrical waveguide. When power is supplied by the antenna elements 6a and 6b as described above, it may be desirable that the side 6c having the open end is supplied with a diameter length. However, the length of the side 6c having the open end of the antenna elements 6a and 6b is desirably a half wavelength of a desired frequency. If the side 6c having the open end of the antenna elements 6a and 6b is too small compared to the length of the diameter, impedance matching becomes difficult. Therefore, the column 10 of the insulating portion in the opening windows 2a and 2b
b is made smaller in accordance with the length of the side 6c having the open end of the antenna elements 6a and 6b, so that excitation is facilitated by the electric field component of the TE11 wave. The radius r of the column 10a of the insulating portions in the opening windows 2a and 2b is (0.293λ /
By setting the fundamental as √ε _r ) <r <(0.485λ / √ε _r ), it is possible to realize a densitometer in which electromagnetic energy of a desired frequency propagates in TE11 wave which is a fundamental mode.

As described above, according to the present invention, the opening window 2a
And 2b is made of a cylindrical waveguide filled with a dielectric, so that the effect of the cutoff frequency of the cylinder 10a in contact with the liquid containing the suspended substance in the detection tube is taken into consideration, and the opening window 2a and Electromagnetic energy of a desired frequency propagates through the insulating portion inside 2b, and a densitometer with enhanced stress resistance and pressure resistance can be realized.

FIG. 6 shows an example of a configuration of a main part according to a third embodiment of the present invention. Since the other configuration is the same as that of the densitometer shown in FIG. 21, the illustration and description thereof are omitted here. Further, only the differences from the embodiment shown in FIG.

As shown in FIG. 6, the opening windows 2a and 2a
The inner insulating portion b is composed of three cylinders (10a, 10b, 10c), and the radius of the middle cylinder (10b) is increased, so that the detection tube 1 and the antenna mounting housing 4 are formed.
a, 4b, the stress resistance and pressure resistance are increased.

Further, for example, the relative dielectric constant of the cylindrical waveguide is 1
5. If the wavelength λ = 157.9 [mm] (at 1.9 GHz), the radius r = 13.5 [mm] and the minimum value of the length of the cylindrical waveguide is about 40 mm, so that it is easy to match with water. However, the insulating portions in the opening windows 2a and 2b shown in FIG.
Each of the cylinders (10a, 10b, 10c) is 6 [m
m], 15 [mm], 8 [mm] (here, the radius r of the middle cylinder (10b) r = 21.25 [mm]), and the total thickness is the minimum, which is about 29 [mm]. That is, since the diameter of the middle column (10b) is large, there is a combination of thicknesses that can be reduced in thickness.

As described above, according to the present invention, the opening window 2a
And 2b is made of a cylindrical waveguide filled with a dielectric, so that the effect of the cutoff frequency of the cylinder 10a in contact with the liquid containing the suspended substance in the detection tube is taken into consideration, and the opening window 2a and Electromagnetic energy of a desired frequency propagates through the insulating portion inside 2b, and by increasing the radius of the middle cylinder, stress resistance and pressure resistance can be strengthened, and a more compact densitometer can be realized.

FIGS. 2 and 3 show examples of the configuration of the main part according to the fourth embodiment of the present invention. Since the other configuration is the same as that of the densitometer shown in FIG. 21, the illustration and description thereof are omitted here.

In FIGS. 2 and 3, the antenna elements 6a, 6
b is a linear monopole antenna whose ground is a contact surface 5c between the bottom surfaces of the antennas 5a and 5b and the antenna mounting housings 4a and 4b. The length of the antenna elements 6a, 6b is three-quarter wavelength of the desired frequency. Contact surface 5c
And an antenna element 6a, 6b. One length from the feeder F (6 in FIG. 2)
d) has a quarter wavelength of the desired frequency, open end,
The other length (6c in FIG. 2) is a half wavelength.

On the other hand, the inverted-L-shaped three-quarter-wavelength monopole antenna shown in FIG. 7 has a ground plane, and the image current 6c 'is symmetrically placed on the ground by utilizing the ground. Can be generated, which is equivalent to arranging two dipole antennas in parallel, and has the advantage of increasing the directivity in the front direction.

FIG. 8 shows an electromagnetic field simulation.
26 shows the results of analyzing the impedance of the L-shaped antenna for a densitometer (FIGS. 2 and 3) and the second quarter-wave monopole antenna (FIG. 25) according to the fourth embodiment of the present invention. Looking at the impedance at a frequency of 1.7 to 2.0 GHz using a Smith chart, the L-shaped antenna has a frequency of 1.942G.
In Hz, it is close to the center indicating 50Ω, which indicates that the matching is improved. In comparison, it can be seen that the monopole antenna has low impedance and is not matched. It can be seen that the impedance is low at the desired frequency due to the influence of the curved surface.

As described above, according to the present invention, it is possible to realize a densitometer provided with an antenna that has improved matching with water (relative permittivity of about 80) where electromagnetic energy does not easily propagate.

FIGS. 9 to 12 show an example of the configuration of a main part according to a fifth embodiment of the present invention. Other configurations are shown in FIG.
Since it is the same as the densitometer shown in FIG. 1, its illustration and description are omitted here. In addition, only the differences from the embodiment shown in FIG.

As shown in FIG. 9, the antenna element 6
The side 6c having an open end among the parts a and 6b is mounted so as to be perpendicular to the ground. The reason will be briefly described.

The inside of the detection tube 1 is not always filled with the liquid containing the suspended substance to be measured (in a full state), and the upper part of the detection tube 1 (1 in FIG. 10).
Air bubbles are generated in (1). In this case, since the microwave is not affected by the propagation path of the normal measurement state (full water state) but by the microwave propagating through the air layer formed by the bubbles and the reflected wave at the liquid level, the measurement value is also unstable. , The measured value is abnormally high compared to the result measured in a full state,
An error occurs in the measured value, such as a decrease or a sudden change, and the measured value is disturbed. If the polarization radiated into the liquid containing the suspended substance is made vertical in order to suppress the influence of the bubbles, it becomes difficult to receive the reflected wave by the bubbles. This is because the reflection surface is horizontal, so that the reflected wave becomes a horizontally polarized wave and cannot be received by an antenna mainly composed of a vertically polarized wave.

On the other hand, when the radius r is large, a higher-order mode is easily generated. When many higher-order modes are generated, the polarization and directivity of radiating radio waves into a liquid containing a suspended substance are disturbed, and the above advantages are lost.

Further, referring to FIG.
In a and 6b, lines (6d and 6e) having open ends are arranged in parallel. By doing so, the polarization of the radio wave radiated from the transmission antenna 5a and the polarization of the radio wave received by the reception antenna 5b become the same, and the reception can be facilitated.
Here, in FIG. 11, the position of the power supply unit F is in the ground direction, but both may be in the zenith direction, or as shown in FIG.

As described above, according to the present invention, in order to reduce the influence of bubbles formed in the detection tube, the directivity of the antenna is increased, and electromagnetic energy is easily propagated in a liquid containing a suspended substance. To facilitate transmission and reception between the transmitting antenna and the receiving antenna, a densitometer having the same polarization can be realized.

Here, the depth d of the insulating portions in the opening windows 2a and 2b will be described. In the case of a circular waveguide, it can be replaced with a distributed constant circuit model shown in FIG. The impedance Z ₁ is given by the following equation.

(Equation 3) Here, Z _L : the impedance of the antenna d ₁ : the depth of the insulating portion in the opening window 2 a or 2 b λ: the wavelength of a desired frequency y ₁₁ : the root of the Bessel function J ₁ and the smallest value ε _r1 : the opening windows 2a or 2b in the insulating portion of the dielectric constant Z _0: characteristic in air impedance r _1: than the radius and _{Z 1} within the opening window portion 2a or 2b insulating portion, of the water (the ratio to the dielectric constant 80) The reflection coefficient is calculated by the following equation.

(Equation 4) By obtaining a reflection coefficient (close to 0) becomes smaller depth d ₁ of the opening window portion 2a or 2b in the insulating portion, the antenna for impedance matching is obtained.

In the case of a three-layer cylinder shown in FIG. 14, the following equation is similarly obtained.

First layer impedance

(Equation 5) Z _L : Impedance of antenna d ₁ : Depth of insulating portion in opening window 2a or 2b λ: Wavelength of desired frequency y ₁₁ : Root of Bessel function for TE11 ε _r1 : Insulating portion in opening window 2a or 2b Relative permittivity Z ₀ : characteristic impedance in air r ₁ : radius of insulating portion in opening window 2a or 2b impedance of m-th layer (m = 2, 3)

(Equation 6) d _m : Depth of the insulating portion in the m-th opening window 2a or 2b λ: Wavelength of desired frequency y ₁₁ : Root of the Bessel function for TE11 ε _rm : Insulating in the m-th opening window 2a or 2b dielectric constant parts Z _0: characteristic impedance r m in _air: than the radius and Z ₁ of the _m-th layer of the opening window portion 2a or 2b in the insulating section, the reflection coefficient of the water (the ratio to the dielectric constant 80) It is calculated by the following equation.

(Equation 7) By obtaining a reflection coefficient (close to zero) becomes small depth of the opening window portion 2a or 2b in the insulating portion _{d 1, d 2, d 3} , an antenna for impedance matching is obtained.

FIGS. 15 to 17 show the results of the analysis of the pointing vector by the electromagnetic field simulation. The pointing vector indicates the amount and direction of electromagnetic field energy propagation. The direction of the arrow indicates the direction, and the length indicates the magnitude of the energy propagation amount.

FIG. 15 shows the cylindrical opening window 2a or 2a.
b In the cross section of the liquid containing the suspended material and the suspended material, when the depth d of the cylindrical opening window 2a or 2b in the insulating portion is 40 mm, the radius is 13.75 mm, and the relative dielectric constant is 15, the suspended material is removed. This is an example that matches well with the contained liquid. As can be seen from this figure, the direction of the pointing vector in the liquid containing the suspended substance is directed to the front, and the magnitude of the propagation amount is slightly lower than the feeding point, but the electromagnetic field energy propagates well. It is shown that.

FIG. 16 shows an opening window 2a in which three layers of cylinders are stacked.
Alternatively, in the cross section of the liquid containing the insulating material and the suspended substance in 2b,
The depth of the insulating portion in the cylindrical opening window 2a or 2b is d = 8 mm, 15 mm, 6 mm, radius 13.7 from the antenna.
5 mm, 22.5 mm, 13.75 mm, relative dielectric constant 15
In this case, it is an example of matching with water. As described above, the direction of the pointing vector in the water is toward the front, and the magnitude of the propagation amount is slightly lower than the feeding point, but the electromagnetic field energy is well propagated into the water.

FIG. 17 shows an opening window 2a in which three layers of cylinders are stacked.
Alternatively, the cross-section of the insulating portion and the water in 2b, the cylindrical opening window portion 2
The depth of the insulating part in a or 2b is d = 5m from the antenna
m, 5mm, 6mm, radius 13.75mm, 22.5m
This is an example where it is difficult to match with water in the case of m, 13.75 mm, and relative permittivity of 15. As described above, the value of the energy transmission amount indicated by the pointing vector in the opening portion 2a or 2b and the underwater pointing vector is very small, and the electromagnetic energy is hardly radiated from the antenna. I understand.

As described above, according to the present invention, in order to enhance the concentration resolution, the electromagnetic energy can be efficiently propagated into the liquid containing the suspended substance, and the concentration of the fluid to be measured can be measured with high accuracy. A densitometer can be provided.

The present invention is not limited to the above embodiment, but can be variously modified as follows.

For example, in the above three embodiments, a linear inverted L-shaped antenna is used, but a circular or rectangular patch antenna as shown in FIG. 18 is provided on the side of the antenna element having an open end (6c in FIG. 2). Can be used, and its shape and form are not particularly limited.

In the second and third embodiments, two or three layers are used. However, as shown in FIG. 19, four or more layers may be used, and the shape and form are not particularly limited.

Further, in the above-described three embodiments, the radius of the three-layered cylinder is larger in the center and the same at both ends.
As shown in FIG. 20, the order of the sizes is not particularly limited.

[0071]

As described above, according to the present invention,
By making the insulating portions in the open windows 2a and 2b a cylindrical waveguide filled with a dielectric material, the influence of the cutoff frequency is taken into consideration, and the insulating portions in the open windows 2a and 2b can transmit electromagnetic energy of a desired frequency. Can be facilitated.

Further, by making the insulating portions in the opening windows 2a and 2b a cylindrical waveguide filled with a dielectric material, the insulating portions in the opening windows 2a and 2b can be set to a desired frequency in consideration of the effect of the cutoff frequency. Electromagnetic energy propagates, and it is possible to easily enhance stress resistance and pressure resistance.

Further, in order to reduce the influence of air bubbles generated in the detection tube, the directivity of the antenna is increased, and electromagnetic energy can be easily propagated into a liquid containing a suspended substance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of a densitometer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a configuration of an antenna element according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a main part of a densitometer according to a fourth embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a main part of a densitometer according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a state of an electric field in a fundamental mode (TE11) of a cylindrical waveguide.

FIG. 6 is a diagram showing a configuration of a main part of a densitometer according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating an operation method of an antenna element according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing impedance of a densitometer according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view showing a configuration of a main part of a densitometer according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a state of a liquid containing a suspended substance in a detection tube.

FIG. 11 is a perspective view showing a configuration of a main part of a densitometer according to a fifth embodiment of the present invention.

FIG. 12 is a perspective view showing another configuration of the main part of the densitometer according to the fifth embodiment of the present invention.

FIG. 13 is a diagram showing a single-layer distributed constant circuit.

FIG. 14 is a diagram illustrating a three-layer distributed constant circuit.

FIG. 15 is a diagram showing pointing vectors of the densitometer according to the fourth embodiment of the present invention.

FIG. 16 is a diagram showing pointing vectors of the densitometer according to the fourth embodiment of the present invention.

FIG. 17 is a diagram showing pointing vectors of a densitometer that does not satisfy the conditions of the fourth embodiment of the present invention.

FIG. 18 is a cross-sectional view illustrating another configuration of the main part of the densitometer according to one embodiment of the present invention.

FIG. 19 is a cross-sectional view showing another essential configuration of the densitometer according to the second embodiment of the present invention.

FIG. 20 is a cross-sectional view illustrating another configuration of a main part of the densitometer according to the third embodiment of the present invention.

FIG. 21 is a view showing a schematic configuration of a conventional microwave densitometer.

FIG. 22 is a diagram showing a calibration curve used for a conventional microwave densitometer.

FIG. 23 is a diagram showing details of a main part of an antenna mounting portion of a conventional microwave type densitometer.

FIG. 24 is a diagram showing a first monopole antenna which is a conventional example.

FIG. 25 is a view showing a second monopole antenna which is a conventional example.

FIG. 26 is a diagram showing a conventional dipole antenna.

[Description of Signs] 1 Detection tube 2 ‥‥ Open window 3 ‥‥ Airtight packing 4 ‥‥ Antenna mounting housing 5 ‥‥ Antenna 6 ‥‥ L-shaped antenna element 7,8 ‥‥ λ / 4 monopole antenna element 9 λ / 2 dipole antenna element 10 opening window (contact with liquid) 11 upper part of detection tube (bubble) 12 liquid containing suspended substance (Measurement target) 23a, 23'a {open window 23b, 23'b} hermetic seal packing 23c, 23'c {antenna mounting plate 23d, 23'd} insulator 28} transmitting antenna 28 'opening 29 reception antenna 29' opening 30, 30 'dielectric E electric field F feeding unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiro Watanabe 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd.

Claims (5)

[Claims] 1. A microwave transmission / reception system is opposed to a detection tube or a detection container, and an opening window is formed in a cylindrical shape so as to face the detection tube or the detection container. An antenna mounting insulator is hermetically attached to the window, the microwave transmitting / receiving antenna is attached to the antenna mounting insulator in close contact with the antenna, and the microwave passing through the object to be measured in the detection pipe or the detection container is used. In a densitometer for measuring the phase delay of the object and measuring the concentration of the object to be measured, when a wavelength of a desired frequency is λ and a relative permittivity of the insulator for mounting the antenna is ε _r , a radius r Is (0.293λ / √ε _r ) <r <(0.4
85λ / √ε _r ). 2. A microwave transmission / reception system is disposed to face a detection tube or a detection container, and at least two or more columns having different opening radii are provided so as to face the detection tube or the detection container. In addition to being formed in a stacked shape, an antenna mounting insulator is hermetically attached to this opening window,
The microwave transmitting / receiving system antenna is closely attached to the antenna mounting insulator, and a phase delay of a microwave passing through the object to be measured in the detection tube or the detection container is measured, and the concentration of the object to be measured is measured. at a concentration meter for measuring the wavelength of a desired frequency lambda, when the relative dielectric constant of the antenna mounting insulators and epsilon _r, of the opening window portion formed in the shape of repeated different radii cylinder, the The radius r of the cylinder of the opening window on the object side is (0.293λ / √).
A densitometer, wherein ε _r ) <r <(0.485λ / √ε _r ). 3. The opening window is formed by stacking three or more cylinders having different radii on each other, and the innermost one of the cylinders closer to the object to be measured than the cylinder of the opening window. 3. The densitometer according to claim 2, wherein at least one radius is large. 4. The microwave transmitting / receiving system antenna is a linear monopole antenna having a length of three-quarter wavelength of a desired frequency, and is formed in an inverted L-shape from a feeding part. The length from the bent portion to the open end is a quarter wavelength of the desired frequency, and the length from the bent portion to the open end is a half wavelength of the desired frequency. The densitometer according to any one of claims 1 to 3. 5. The microwave transmitting and receiving system antenna according to claim 4, wherein the side having the open end of the linear monopole antenna is mounted to be perpendicular to a side surface of the opening window. Densitometer described in 1.