JPH09243575A - Microwave type densitometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the microwave-type tensitometer, which can measure the concentration of the suspension liquid of excellent conducting particle such as carbon and metal powder and can also measure the concentration of mixed fluid with rmonconducting material. SOLUTION: This densitometer detects the phase delay θ1 6f the microwave, which is obtained by the measurement of the reference fluid in concentration measuring pipe 20, and the phase delay θ2 of the microwave, which is obtained by the measurement for fluid to be measured. The densitometer is constituted so as to perform these detections and to measure the concentration of the fluid to be measured from the phase difference Δθ=θ2 -θ1 of both phase delays. In this case, the following means are provided. The concentration operating means computes the concentration X by the calibration curve X=a.Δθ+b in correspondence with every kind of the fluid to be measured. The calibration-curve selecting means performs the discrimination of the positive/negative values of the phase difference Δθ, selects the calibration curve, where the value of the inclination (a) of the calibration curve becomes the positive numerical value, when Δθ is positive, and selects the calibration curve, where the value of the inclination (a) of the calibration curve becomes the negative numerical, when Δθ is negative.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a concentration of a suspended substance,
For example, it relates to a densitometer for measuring the concentration of a fluid to be measured containing sludge, pulp, and other various substances, and particularly a micrometer having a function capable of measuring the concentration of both non-good and good conductive substances and suspensions. The present invention relates to a wave type densitometer.

[0002]

2. Description of the Related Art When measuring the concentration in a liquid, an ultrasonic densitometer has conventionally been used to obtain the concentration by measuring the attenuation factor of ultrasonic waves, and the transmitted light attenuation factor and scattered light increase factor are measured using light. Optical densitometers are widely used to calculate the concentration.

However, in the former case, when air bubbles are mixed in the fluid, the influence thereof is greatly affected and the measurement error becomes large.
On the other hand, in the latter case, if dirt adheres to the optical window that receives or receives light, it is greatly affected and the measurement error increases. Therefore, in recent years, a densitometer that measures the concentration using microwaves has been developed as a densitometer that is less likely to be affected by bubbles and dirt.

FIG. 6 shows an example of the structure of a densitometer using microwaves. As shown in the figure, a microwave transmitting antenna 11 and a microwave receiving antenna 12 are arranged to face each other in a pipe 1 through which a fluid flows, and a microwave oscillator 13
The microwave is emitted from.

As a microwave passage, the first path introduced into the phase difference measuring circuit 15 through the power splitter 14, the transmission antenna 11, the in-tube fluid, and the reception antenna 12, and similarly the microwave is the power splitter. 1
And a second path which is introduced into the phase difference measuring circuit 15 through the line 4.

In the phase difference measuring circuit 15, the phase difference is obtained from the phase delay of the microwave from the first path with respect to the microwave from the second path. In this densitometer, the phase delay θ _{2 of the} microwave propagating the fluid under measurement in the pipe with respect to the microwave directly received from the microwave oscillator 13 via the power splitter 14 and the reference fluid (for example, water supply) in the pipe. water) was filled with comparing the phase delay theta ₁ of microwaves when measured under the same conditions as in the fluid to be measured, the phase difference Δθ = (θ ₂ -θ
Measure the concentration using the calibration curve from ₁ ). In particular,
The density is calculated by calculating the density X = aΔθ + b. Note that a is the slope of the calibration curve, and b is the intercept of the calibration curve.

[0007]

The microwave densitometer as described above is not a method for measuring the attenuation rate of microwaves but a method for measuring the phase difference, and it receives or receives microwaves. Since the window does not need to be transparent, it is less susceptible to air bubbles and dirt, and the concentration can be continuously measured.

However, the microwave densitometer described above can be applied to the measurement of the concentration of suspension of non-conductive substance such as sludge and pulp. The wave characteristics have not been clarified in the past and could not be applied to the concentration measurement.

The present invention has been made in consideration of such circumstances, and measures the concentration of a suspension of good conductive particles such as charcoal and metal powder, and further measures the concentration of a fluid mixed with a non-good conductive substance. Another object is to provide a microwave densitometer that is also possible.

[0010]

In order to solve the above problems, the invention according to claim 1 provides a concentration measuring tube in which a microwave transmitter and a microwave receiver are arranged to face each other. While the reference fluid is flowing, the phase delay θ ₁ of the microwave transmitted from the microwave transmitter and received by the microwave receiver through the reference fluid is detected, and the fluid to be measured flows into the concentration measuring tube. During this period, the phase delay θ ₂ of the microwave transmitted from the microwave transmitter and received by the microwave receiver through the fluid to be measured is detected, and the phase difference between both phase delays Δθ = θ ₂ −θ ₁ In the microwave densitometer for measuring the concentration of the fluid to be measured, the concentration calculation means for calculating the concentration X from the calibration curve X = a · Δθ + b corresponding to each type of the fluid to be measured, and whether the phase difference Δθ is positive or negative are determined. If Δθ is positive, the calibration curve You can select the calibration curve the value of a is a positive numerical value, the gradient a of the calibration curve when Δθ is negative
And a calibration curve selecting means for selecting a calibration curve having a negative value.

The invention according to claim 2 is the same as the invention according to claim 1, in which a calibration curve having a positive slope a of the calibration curve and a calibration curve having a negative slope are combined to form one measurement target. The microwave densitometer is provided with a measurement target mode setting means for setting any one of a plurality of measurement target modes as a selection target of the calibration curve selection means.

[0012] In inventing a microwave type densitometer corresponding to each claim constructed as described above, in order to investigate the microwave characteristics for particles of a good conductive substance, which has not been clarified hitherto, a particle of charcoal is used. An experiment was conducted to investigate the relationship between particle concentration and phase difference by injecting microwave into a liquid suspended in water.

As a result, as shown in FIG. 4, it was found that the phase difference Δθ with respect to the concentration X is shown by a calibration curve having a linear relationship with a negative slope. Where θ ₁ is the phase lag in the zero-concentration reference liquid (usually water), and the zero-point phase value θ ₁
Call. θ ₂ is the phase delay of the measured liquid. θ ₂ and θ ₁
The difference Δθ = θ ₂ −θ ₁ is called the phase difference Δθ.

The relationship between the suspension concentration X of sludge and pulp, which has been measurable in the past, and the phase difference Δθ is as shown in FIG. 5, and Δθ is a positive slope with respect to X. It is shown by a calibration curve having a linear relationship with.

Therefore, first, in the microwave densitometer of the invention according to claim 1, the calibration curve selecting means determines whether the phase difference Δθ is positive or negative. When Δθ is positive, the slope a of the calibration curve is determined. A calibration curve with a positive value is selected, and when Δθ is negative, a calibration curve with a negative slope curve a value is selected.

Then, the concentration X is calculated by the concentration calculating means from the selected calibration curve X = a.Δθ + b.
Therefore, when applying a microwave densitometer to a pipeline in which both a suspension of a non-good conductive material and a suspension of a good conductive material flow separately or alternately and mixed,
Depending on whether θ ≧ 0 or Δθ ≦ 0, it is possible to automatically select whether the value of the slope a of the calibration curve is positive or negative.

Further, in the microwave type densitometer of the invention according to claim 2, the same operation as in the invention according to claim 1 is achieved, and in addition, a calibration curve and a negative curve having a positive slope a of the calibration curve are provided. One of the plurality of measurement object modes is set by the measurement object mode setting means as a selection object of the calibration curve selection means.

Therefore, it is possible to obtain the concentration by automatically selecting the value of the slope a of the calibration curve that suits the object of measurement in each mode and calculating the concentration X = aΔθ + b.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram of a microwave densitometer according to the present embodiment. This microwave densitometer is composed of a microwave transmitter / receiver 40 and a signal processor 41. Further, the microwave transmitting / receiving unit 40 is provided with a transmitting antenna 31 and a receiving antenna 32, and is attached to the concentration detecting tube 20.

The concentration detecting pipe 20 is provided with an upstream pipe 21.
And the downstream side pipe 22 are provided via sluice valves 23 and 24. Further, a water supply valve 26 and a drain valve 27 are provided in the concentration detecting pipe 20. A water pipe 2 for guiding a reference fluid such as tap water to the water supply valve 26.
8 is connected, and a water distribution pipe 29 is connected to the drain valve 27.

Further, the suspension of the non-good conductive material and the suspension of the good conductive material flow alternately in the pipeline including the concentration detecting pipe 20. Alternatively, the mixed suspension having non-good conductivity and the mixed suspension having good conductivity flow alternately.

Further, the concentration detecting tube 20 is formed with an opening window portion for microwave incidence / emission at each of the positions opposed to each other with the tube axis interposed therebetween, and the antenna is provided in this opening window portion via an airtight seal packing. A mounting plate is attached.

The transmitting antenna 31 and the receiving antenna 32 are closely attached to the antenna mounting plate via an insulator as described above. The insulator of the antenna mounting plate is fiber resin plastic (FRP),
It is made of vinyl chloride resin or other insulating material.

The microwave transmitter / receiver 40 of this densitometer
It includes a microwave oscillator 33, a power splitter 34, a transmitting antenna 31, and a receiving antenna 32. As a microwave transmission system, a microwave oscillator 33 for generating microwaves, a power splitter 34, and a transmission antenna 31 are provided, and the output of the microwave oscillator 33 is transmitted to the transmission antenna 31 via the power splitter 34. Sent.

As the microwave receiving system, the microwave transmitted from the transmitting antenna 31 is used as the concentration detecting tube 2.
The receiving antenna 32 and the phase measuring circuit 35 for receiving via 0 are provided, and the microwave received by the receiving antenna 32 and the reference signal distributed by the power splitter 34 are input to the phase measuring circuit 35.

On the other hand, the signal processing unit 41 in this densitometer
As a phase measuring circuit 35 which is also a part of the receiving system,
A phase difference calculation circuit 36, a calibration curve slope a selection / concentration calculation circuit 37, a measurement target mode setting device 38, a signal conversion circuit 39, and other peripheral elements not particularly shown are provided.

The phase measuring circuit 35 measures the phase delay θ ₁ as a reference for zero concentration and the phase delay θ _{2 of the} liquid to be measured,
The result is input to the phase difference calculation circuit 36.
Phase difference calculation circuit 36 stores the value of theta _1, calculates a difference Δθ = θ ₂ -θ ₁ of values and theta ₁ momentary theta _2,
This is a portion for inputting Δθ to the calibration curve slope a selection and concentration calculation circuit 37.

The measuring object mode setting device 38 is, for example, as shown in FIG.
The tube for concentration detection 2 from a plurality of measurement target modes as shown in
This is a part in which a measurement target mode is set according to the type of suspension flowing through 0, and the setting contents are input to the calibration curve slope a selection and concentration calculation circuit 37. That is, the measurement target mode to be used for measurement is designated from here.

FIG. 2 is a diagram showing an example of a measurement target mode table used in the microwave densitometer of the present embodiment.
In the figure, target modes (1), (2) ,. . .
The value of the slope a of the calibration curve corresponding to (N) is set. Each a is the value of the slope of the calibration curve that is suitable for each type of liquid to be measured, and the combination of the non-good conductive substance and the good conductive substance to be measured is preset in each mode. There is.

That is, the value of the slope a of each calibration curve is
+ A ₁ , + a ₂ ,. . . (Hereinafter, represented by + a _i )
, _-Am1 , _-am2 ,. . . (Hereinafter represented by −a _mi ) is provided for each mode, and either + a _i or −a _mi is selected by the calibration curve slope a selection and concentration calculation circuit 37.

Further, since the suspension of the non-good conductive material and the suspension of the good conductive material alternately flow in the pipeline including the concentration detecting pipe 20, the suspension of the liquid to be measured is By determining whether the phase delay difference Δθ is positive or negative, the value of the slope a of the calibration curve and the value of the intercept b of the corresponding calibration curve in each mode can be selected.

Although not particularly shown in FIG. 2, the intercept b of the calibration curve
Also for the value of, the value corresponding to the slope a of each calibration curve is set in the measurement target mode table. The measurement target mode table itself is provided in the calibration curve slope a selection and concentration calculation circuit 37.

Calibration curve slope a selection and concentration calculation circuit 37
Automatically selects the value of a according to whether Δθ ≧ 0 or Δθ <0 and the designated measurement target mode, and the concentration X =
This is a part for calculating the density X by calculating a.Δθ + b and inputting it to the signal conversion circuit 39.

That is, in the present embodiment, both the suspension of the non-good conductive material and the suspension of the good conductive material are separately alternately flowed or mixed to each other, and a microwave type densitometer is installed in the pipeline. Since .DELTA..theta..gtoreq.0 or .DELTA..theta..ltoreq.0, by automatically selecting whether the value of the slope a of the calibration curve is positive + a _i or negative -a _mi , Corresponding to the difference in microwave characteristics for both conductive material particles and good conductive material particles.

The signal conversion circuit 39 is a portion for converting the concentration value X obtained by the calibration curve slope a selection and concentration calculation circuit 37 into a unified signal such as 4-20 mA DC and outputting it.

Although not particularly shown, 4-20 m
After being converted into a unified signal such as ADC, the concentration value of the suspension may be further converted, and the unified signal and the concentration value may be output from an output means such as a CRT or a printer.

The configuration described in this embodiment and the configuration in the claims correspond as follows. First, the concentration calculation means is composed of, for example, a calibration curve slope a selection and concentration calculation circuit 37.

The calibration curve detecting means is composed of, for example, a phase difference computing circuit and a calibration curve slope a selection / concentration computing circuit 37. Next, the operation of the microwave densitometer of the embodiment of the present invention configured as described above will be described.

First, from the measurement object mode setting device 38, a number suitable for the measurement object to be measured is designated in advance. The data of the designated mode number is sent to the calibration curve slope a selection and concentration calculation circuit 37.

Before measuring the liquid whose concentration is to be measured, such as a suspension, the reference phase delay θ ₁ at zero concentration is measured. When measuring the reference phase delay θ ₁ of zero concentration, the sluice valve 2
After closing 3, 24, the drain valve 27 is opened to discharge the measurement fluid remaining in the pipe 20, and then the water supply valve 2
After opening 6 to supply tap water to wash dirt in the pipe 20, the drain valve 27 is closed to fill the pipe 20 with tap water.

When the microwave signal is generated from the microwave oscillator 33 as shown in FIG. 1 after the tap water is thus filled up, this microwave is transmitted from the transmission antenna 31 through the power splitter 34. Then, the tap water in the pipe 20 is propagated and received by the receiving antenna 32. The microwave received by the receiving antenna 32 is sent to the phase measuring circuit 35. On the other hand, part of the microwave transmission wave is sent from the power splitter 34 to the phase measuring circuit 35 as a reference signal.

[0042] In the phase measurement circuit 35, the reference phase delay theta ₁ measured with respect to a reference fluid by comparing the microwave transmission wave that is, the reference signal and the microwave receiving wave, a phase difference reference phase delay theta ₁ This the measured It is sent to the arithmetic circuit 36 and stored therein.

After that, the drain valve 27 is opened to open the pipe 20.
After discharging the tap water inside, the sluice valves 23 and 24 are opened, the measurement fluid containing the measurement substance is caused to flow, and the concentration measurement is started. First, the microwave signal is transmitted from the microwave oscillator 33 while the measurement fluid containing the measurement substance is flowing.

This microwave signal is sent to the transmitting antenna 31 and the phase measuring circuit 35 via the power splitter 34 as described above. When the microwave emitted from the transmitting antenna 31 propagates through the fluid to be measured in the concentration detecting tube 20 and reaches the receiving antenna 32, the receiving antenna 32 has a phase delay corresponding to the concentration of the fluid to be measured. Output a signal.

In the phase measuring circuit 35, the phase shift θ ₂ of the microwave signal having a phase delay corresponding to the concentration of the fluid to be measured is measured by comparing the reference signal and the microwave received wave, as described above.

Next, in the phase difference calculation circuit 36, the phase difference Δθ =
θ ₂ −θ ₁ is calculated, and according to the value of Δθ and the measurement target mode preset by the measurement target mode setting unit 38, the calibration curve slope a selection and concentration calculation circuit is performed according to the operation flow as shown in FIG. The operation at 37 is performed.

FIG. 3 is a flow chart showing the operation of the calibration curve slope a selection and the concentration calculation circuit of the microwave type densitometer of this embodiment. First, the calibration curve slope a selection and concentration calculation circuit 3
When the phase difference Δθ is input to the 7 from the phase difference calculation circuit 36 (ST1), it is determined whether the phase difference Δθ is positive or negative (ST2).

When the phase difference Δθ is positive (ST2),
Among the measurement object modes designated by the measurement object mode setter 38, a calibration curve having + a _{i as} the inclination a of the calibration curve is selected (ST3).

Further, the density value X is obtained by the calculation of density X = a · Δθ + b. At this time, for example, when the measurement target mode (1) is designated, Δθ ≧ 0, and therefore the calculation is performed by X = + a ₁ Δθ + b ₁ (1) (ST4).

Then, the density value X as the calculation result is input to the signal conversion circuit 39 (ST5). On the other hand, when the phase difference Δθ is negative (ST2), the calibration curve whose -a _mi is the inclination a of the calibration curve is selected from the measurement target modes designated by the measurement target mode setting unit 38 ( ST6).

Then, the density value X is obtained by the calculation of density X = a.Δθ + b. At this time, for example, when the measurement object mode (1) is designated, Δθ <0.
Therefore, the calculation is performed by X = −a _m1 Δθ + b _m1 (2) (ST7).

Then, the density value X as the calculation result is input to the signal conversion circuit 39 (ST5). Hereinafter, the calculated density value is converted into a unified signal by the signal conversion circuit 39 and output as a density measurement value.

As described above, according to the microwave densitometer according to the embodiment of the present invention, whether the phase difference Δθ measured and calculated is positive or negative It is possible to select either a calibration curve for non-good conductivity measurement fluid or a calibration curve for good conductivity measurement fluid. It is possible to measure the concentration of each suspension in a pipeline in which both suspensions of a good conductive substance such as metal powder flow separately or alternately.

That is, according to the present embodiment, it is possible to measure the concentration corresponding to the fluid to be measured having such poor conductivity and good conductivity with one microwave concentration meter. In addition,
The present invention is not limited to the above embodiments,
Various modifications can be made without departing from the gist of the invention.

[0055]

As described above in detail, according to the present invention, it is possible to measure the concentration of a suspension of good conductive particles such as charcoal and metal powder, and the concentration of a fluid mixed with a non-good conductive substance. A microwave densitometer can be provided.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of a measurement target mode table used in the microwave densitometer of the present embodiment.

FIG. 3 is a flowchart showing the operation of the calibration curve slope a selection and the concentration calculation circuit of the microwave type densitometer of the present embodiment.

FIG. 4 is a diagram showing the relationship between the concentration of a good conductive substance and the phase difference Δθ.

FIG. 5 is a diagram showing the relationship between the concentration of a poor conductive material and the phase difference Δθ.

FIG. 6 is a basic configuration diagram for explaining a microwave densitometer.

[Explanation of symbols]

 20 ... Concentration detector pipe 21 ... Upstream side pipe 22 ... Downstream side pipe 23, 24 ... Partition valve 26 ... Water supply valve 27 ... Drainage valve 28 ... Water pipe 29 ... Water distribution pipe 31 ... Transmission antenna 32 ... Reception antenna 33 ... Microwave Oscillator 34 ... Power splitter 35 ... Phase measurement circuit 36 ... Phase difference calculation circuit 37 ... Calibration curve inclination a selection and concentration calculation circuit 38 ... Measurement mode selector 39 ... Signal exchange circuit

Claims (2)

[Claims] 1. A microwave transmitter and a microwave receiver are arranged in opposition to a concentration measuring tube, and when a reference fluid is flowing through the concentration measuring tube, the microwave is transmitted from the microwave transmitter and passes through the reference fluid. Detecting the phase delay θ ₁ of the microwave received by the microwave receiver, and when the fluid to be measured flows through the concentration measuring tube, it is transmitted from the microwave transmitter and passes through the fluid to be measured. In the microwave densitometer for detecting the phase delay θ ₂ of the microwave received by the microwave receiver, and measuring the concentration of the fluid to be measured from the phase difference Δθ = θ ₂ −θ _{1 of} both phase delays. A concentration calculation means for calculating the concentration X by a calibration curve X = a · Δθ + b corresponding to each type of the fluid to be measured, and whether the phase difference Δθ is positive or negative is determined, and when Δθ is positive, the calibration curve is obtained. The value of the slope a of That selects the calibration curve, a microwave densitometer when Δθ is negative, characterized in that it comprises a calibration curve selecting means for selecting a calibration curve value of slope a of the calibration curve is a negative number. 2. A calibration curve in which the value of the slope a of the calibration curve is positive and a calibration curve in which the value is negative are combined to form one measurement target mode, and one of a plurality of measurement target modes is set to the above-mentioned mode. 2. The microwave densitometer according to claim 1, further comprising a measurement target mode setting unit which is set as a selection target of the calibration curve selecting unit.