JP3248683B2 - Method and apparatus for separating and measuring liquid density and viscosity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for separating and measuring the density and viscosity of a liquid.

[0002]

2. Description of the Related Art Conventionally, methods for measuring density and viscosity (viscosity) include a static method such as a specific gravity method, a weight method, a falling ball method, a rotating disk method, and a dynamic method using elastic vibration. There is.

The former static method is difficult to perform automatic measurement, requires a long time for measurement, and is not suitable for instantaneous automatic measurement.

[0004] For this reason, the latter dynamic method is used for measurement that requires responsiveness, such as a density sensor that obtains a density from a speed change caused by a mass load, or a mechanical impedance of a shear wave. There is a viscosity sensor that obtains the product of density and viscosity from a change in sound speed (attenuation).

[0005]

In order to measure the viscosity quickly and accurately by the conventional technique, it is necessary to measure the density sensor and the viscosity sensor under the same measuring conditions such as temperature and pressure. There was a disadvantage that it became complicated and expensive. The viscosity is the output of the viscosity sensor thus obtained (density x viscosity)
Is divided by the output of the density sensor, so that it is impossible to obtain it uniquely, and the data processing becomes complicated.

An object of the present invention is to measure the density and viscosity of a liquid quickly and accurately with a simple configuration.

[0007]

According to the first aspect of the present invention, there is provided a surface acoustic wave sensor having unevenness in the vertical direction of the shear displacement on the surface of propagation of the surface acoustic wave, and a flat slip having no unevenness. When the surface acoustic wave sensor is installed on the same surface acoustic wave piezoelectric element, and the standard liquid and the liquid to be measured are loaded on each of the two sensors, the density and viscosity of the liquid to be measured are determined based on the sound speed changes of both sensors. Are measured separately.

According to a second aspect of the present invention, there is provided an apparatus for separating and measuring the density and viscosity of a liquid used for performing the method for separating and measuring the density and viscosity of a liquid according to the first aspect. A surface acoustic wave sensor with unevenness in the vertical direction of the shear displacement on the propagation surface and a flat surface acoustic wave sensor without unevenness are installed on the same surface acoustic wave piezoelectric element. .

Hereinafter, "slip surface acoustic wave" is referred to as "SH-
SAW ".

[0010]

According to the method and apparatus of the present invention, the sound velocity of each sensor under various conditions when a standard liquid is loaded and the conversion formula from the measured data are input to the computer in advance, so that The density and viscosity of the liquid to be measured can be instantaneously obtained from the outputs of both sensors when the liquid to be measured is loaded.

The principle and operation of the present invention will be described below with reference to the drawings. FIG. 1 shows an uneven SH-S
FIG. 4 is a cross-sectional view when a liquid is loaded on the propagation surface of the AW sensor. In the figure, X ₁ is the propagation direction of SH-SAW, and X ₂ is S
3 shows a displacement direction of H-SAW. As is apparent from FIG. 1, two effects are produced: an effect by shearing motion of the liquid caused by viscous coupling between the vibrating surface and the liquid, and an effect by trapping the liquid by the recess.

The former effect also occurs in a conventional SH-SAW sensor. In addition, the latter effect occurs because the liquid trapped by the concave wall behaves as a virtual film. From these two effects, it can be considered that the response of the SH-SAW sensor is the same as the state when the film is fixed on the propagation surface and the liquid is loaded thereon.

The mass load of the SH-SAW sensor (density ρ,
The speed change (ΔV / V) due to the Lame constant μ and the film thickness h) is

(Equation 1) Is represented by Here, V is the propagation velocity, P is the power flow per unit width, and v ₂ is the particle velocity in the X ₂ direction.

Here, the liquid trapped concavely is considered as a film. The speed change at that time is

(Equation 2) Is represented by Here, h is the effective film thickness, S _l and S _m are the concave bottom area and the convex bottom area, respectively, and S is the sum of the two areas. The suffixes l and m indicate liquid and metal. From this, the speed change that occurs when the standard liquid is changed to the liquid to be measured is ρ >> μ / V ² because

(Equation 3) Becomes Here, ρ _l ′ and ρ _l indicate the densities of the liquid to be measured and the standard liquid, respectively.

The speed change of an SH-SAW sensor (hereinafter, referred to as an RS sensor) having an uneven surface is the speed of an SH-SAW sensor (hereinafter, referred to as an SS sensor) having a flat surface. The result is obtained by adding Equation 3 to the change. The theoretical formula of the RS sensor is

(Equation 4) Becomes Here, ρ _l ′ and η _l ′ represent the density and viscosity of the liquid to be measured, respectively, and ρ _l and η _l represent the density and viscosity of the standard liquid.

Now, the sound speed changes between the liquid to be measured and the standard liquid by the RS and SS sensors, respectively, are shown.

(Equation 5) In other words, Equation 4 is

(Equation 6) Becomes

From Equation 6, the density ρ _l ′ of the liquid to be measured is

(Equation 7) Is obtained.

Similarly, the viscosity η _l ′ of the liquid to be measured is

(Equation 8) Is obtained.

The density and viscosity of the liquid to be measured are separately calculated by inputting sound velocity data from the RS and SS sensors to a computer in which necessary data is set in advance based on Equations 7 and 8. A way is possible.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view showing one embodiment of the solution sensor according to the present invention. In the figure, 1 and 4 are SH
-SAW transmitter (receiver), 2 and 5 are receiver (transmitter), 3
Numeral 6 denotes an SH-SAW propagation surface, and numeral 7 denotes an uneven surface provided in the SH-SAW shear displacement vertical direction.

An SS sensor is formed by 1, 2, and 3, and the SH-SAW transmitted from the transmitter 1 propagates through the propagation surface 3 and is received by the receiver 2. Similarly, an RS sensor is formed by 4, 5, and 6, and the SH-SAW transmitted from the transmitter 4 propagates through the propagation surface 6 and the uneven surface 7 and is received by the receiver 5.

Both the SS and RS sensors have a common S
It is installed on the H-SAW piezoelectric element 8 (FIG. 3).

The uneven surface can be realized by plating or resist, and the h of the convex portion depends on the wavelength.

FIG. 3 shows a measurement state in which a liquid is loaded on the propagation surface. In the figure, reference numerals 9 and 10 denote R-S composed of the uneven surface 7.
Sectional views of the liquid dropped on the sensor, and 11 and 12 are sectional views of the liquid dropped on the SS sensor constituted by the flat surface 3.

Reference numerals 9 and 11 denote standard liquids. In this state, after measuring the sound velocity (input to a computer), the liquid is removed, the liquids 10 and 12 to be measured are dropped, and the sound velocity is measured again (input to a computer).

From the measurements of 9, 10 and 11, 12 respectively

(Equation 9) Is found.

FIG. 4 shows a measurement example based on the present invention. The figure shows a measurement example using distilled water as the standard liquid and aqueous glycerin and glucose aqueous solutions as the liquid to be measured.
3 and 15 are R of aqueous glycerin solution and aqueous glucose solution.
The values measured by the -S sensor, 14 and 16 are the values measured by the SS sensor of the aqueous glycerin solution and the aqueous glucose solution.

The chain line 17 indicates the first item on the right side of the equation (6).
This is a straight line obtained from the theoretical value of the S sensor, and is in good agreement with the measured values 14 and 16 of the SS sensor.

FIG. 5 shows measured values obtained by this method in comparison with literature values. In the figure, reference numeral 18 denotes a difference in sound speed change between the RS sensor and the SS sensor in FIG.

(Equation 10) 7 is a correlation between the measured density value according to Equation 7 and the literature value.

From FIG. 5, the measured values and the literature values are in good agreement, indicating that the density measurement according to the present invention is possible.

Change in sound speed due to SS sensor in FIG.

[Equation 11] And the above-mentioned density measurement value ρ _l ′, the viscosity η _l ′ is obtained from Expression 8.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific structure of the present invention is not limited to this embodiment, and the design can be changed without departing from the scope of the present invention. The present invention is also included in the present invention.

[0033]

As described above, according to the method and apparatus for separating and measuring the density and viscosity of a liquid according to the present invention, a pair of SH-
By simply dropping the liquid to be measured on the SAW sensor, it becomes possible to immediately separate and measure the density and viscosity of the solution, which were not possible in the past.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the principle of the present invention, and shows an uneven SH-
FIG. 4 is a cross-sectional view when a liquid is loaded on the SAW propagation surface.

FIG. 2 is a plan view showing one embodiment of a solution sensor according to the present invention.

FIG. 3 is a cross-sectional view illustrating a measurement state in which a liquid is loaded on a propagation surface.

FIG. 4 is a graph showing changes in the propagation velocity of SH-SAW with respect to the square root of the density-viscosity product of an aqueous glycerin solution and an aqueous glucose solution using an RS sensor and an SS sensor in a measurement example according to the present invention.

5 is a graph showing a correlation between a measured value of density obtained from a difference between propagation speeds of two sensors and a document value with respect to the liquid to be measured of FIG.

[Explanation of symbols]

1, 4 Transmitting / receiving element 2, 5 Receiving / transmitting element 3, 6 Propagation surface in a short-circuit state 7 Irregularity propagation surface 8 SH-SAW piezoelectric element 9, 11 Standard liquid dropped on propagation surface 10, 12 Propagation Liquid to be measured dropped on the surface 13, 15 Change in sound speed of glycerin aqueous solution and glucose aqueous solution measured by RS sensor 14, 16 Change in sound speed of glycerin aqueous solution and glucose aqueous solution measured by SS sensor 17 SS Theoretical sound velocity change value of sensor 18 Correlation graph of measured value of density and literature value

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-29916 (JP, A) JP-A-5-45338 (JP, A) JP-A-2-238357 (JP, A) JP-A-3-29 82952 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28 G01N 9/00 G01N 11/00 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A flat surface acoustic wave sensor having unevenness in the vertical direction of a shear displacement on a propagation surface of a surface acoustic wave and a flat surface acoustic wave sensor having no unevenness in the same surface acoustic wave piezoelectric element. A method for separating and measuring the density and viscosity of a liquid, wherein the standard liquid and the liquid to be measured are installed on each of the sensors, and the density and viscosity of the liquid to be measured are separately measured based on changes in the speed of sound of the two sensors. 2. A liquid density and viscosity separation / measuring apparatus used for performing the liquid density / viscosity separation / measuring method according to claim 1, wherein the vertical displacement of the shear displacement on the surface where the surface acoustic wave propagates. An apparatus for separating and measuring the density and viscosity of a liquid, in which a surface acoustic wave sensor with unevenness in the direction and a flat surface acoustic wave sensor without unevenness are installed on the same surface acoustic wave piezoelectric element.