JP2002066550A - Water processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water processor giving germicidal effect to microorganisms in water. SOLUTION: The water processor is provided with a reaction container having first and second parts and having a rotary symmetrical shaft, a first cover covering an opening part on the first part of the reaction container, a second cover covering an opening part on the side of the second part of the reaction container, a first ultrasonic vibrator having the rotary symmetrical shaft which sequentially connects the first ultrasonic vibrator, a first vibration transmission body and a first column and a second ultrasonic vibrator having a rotary symmetrical shaft which sequentially connects the second ultrasonic vibrator, a second vibration transmission body and a second column. The shaft of the first ultrasonic vibrator is aligned with that of the reaction container. The first column is included in the first part and is supported by the first cover. The shaft of the second ultrasonic vibrator is aligned with that of the reaction container. The second column is included in the second part and is supported by the first cover. The first ultrasonic vibrator is driven by the frequency of >=100 kHz and the second ultrasonic vibrator is driven by the frequency of <=100 kHz. Thus, the mechanical destruction operation of cavitation is given to the microorganisms with high probability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment apparatus for generating cavitation by ultrasonic waves in film-form water, and sterilizing microorganisms in the water by the action of cavitation.

[0002]

2. Description of the Related Art In water treatment, it has been pointed out that chlorination widely used in the past is not very effective in killing pathogenic microorganisms such as Cryptosporidium having excellent chlorine resistance. As means capable of killing pathogenic microorganisms, for example, according to EP-A-567225,
A water treatment method using cavitation by ultrasonic waves of 20 kHz or more is known.

[0003] Cavitation, which causes a sterilization effect in a water treatment method using ultrasonic waves, is a phenomenon in which a gas such as oxygen existing in water becomes a nucleus due to a change in pressure and bubbles are generated. As described in “Ultrasonic Technology Handbook (New Edition): Nikkan Kogyo Shimbun, 1991, pp. 844-858”, the water generated by cavitation collapses under the impact pressure generated when it collapses. It is widely known that microorganisms are mechanically destroyed.

[0004]

SUMMARY OF THE INVENTION In order to impart cavitation action to microorganisms in water with a high probability to improve the sterilization efficiency, Japanese Patent Application Nos. 11-182903 and 2000 have been disclosed.
At 163137, the present inventor shows a water treatment apparatus for generating cavitation in film water.

[0005] Ultrasonic cavitation can generate cavitation with a small amount of energy if a relatively low frequency of 100 kHz or less is used, and the cavitation has a strong mechanical destruction effect. It is considered desirable to use ultrasonic waves of 100 kHz or less in the above-described ultrasonic water treatment apparatus, but ultrasonic waves of a single frequency are used in each case.

Normally, a large number of bubbles having different sizes are present in water, and most bubbles having a radius of several tens of μm are most present. When cavitation is generated by irradiating ultrasonic waves of 100 kHz or less into such water, bubbles having a radius of several μm to several hundred μm are efficiently crushed and strong shock waves are generated, but a small diameter or a large diameter is generated. Bubbles have a reduced impact force when crushed or do not crush.

In the above-mentioned water treatment apparatus, since ultrasonic waves of a single frequency are used, some bubbles of various sizes contained in the water are crushed. In order to destroy microorganisms in water efficiently, it is better to crush as many bubbles as possible and generate a large impact pressure in many places.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a water treatment apparatus for generating cavitation in water in a film form and disinfecting microorganisms in the water. It is an object of the present invention to provide a water treatment apparatus for efficiently sterilizing microorganisms in water by generating the water in a place.

[0009]

[Means for Solving the Problems] "Ultrasonic Technology Handbook (New Edition): Nikkan Kogyo Shimbun, 1991, p. 1085-
p. As described in “1086”, when the bubble vibrates, the bubble grows and becomes larger due to the rectified diffusion. This effect is most prominent in resonant bubbles. Therefore, in the water treatment apparatus of the present invention, ultrasonic waves having a frequency of 100 kHz or more are irradiated,
Small bubbles are grown by ctifed diffusion to increase the frequency (density) of bubbles of several μm to several hundred μm that can be crushed at a frequency of 100 kHz or less. Thereafter, by irradiating an ultrasonic wave of 100 kHz or less, many of the bubbles existing in the water are crushed.

[0010] The water treatment apparatus of the present invention has first and second portions having a rotationally symmetric axis and a reaction vessel having a rotationally symmetric axis. The opening on the side of the first part of the reaction vessel is covered with a first lid with an inlet for water, and the opening on the side of the second part of the reaction vessel is a second lid with an outlet for water. Covered with.

A first ultrasonic transducer, a first vibration transmitter, and a first cylinder having a rotationally symmetric axis formed by sequentially coupling a first cylinder are connected.
The first cylinder of the ultrasonic vibrator is included in the first portion of the reaction vessel such that the axis of rotational symmetry of the first ultrasonic vibrator coincides with the axis of rotational symmetry of the reaction vessel. Supported by

A second ultrasonic transducer, a second vibration transmitter, and a second cylinder having a rotationally symmetric axis formed by sequentially coupling the second cylinder;
The second column of the ultrasonic vibrator of the present invention is arranged such that the rotational symmetry axis of the second ultrasonic vibrator and the rotational symmetry axis of the reaction vessel coincide with each other, so that one end face of the first cylinder and the second cylinder have the same shape. The reaction vessel is included in the second portion of the reaction vessel with one end face opposed to the other end face, and is supported by the second lid.

The first ultrasonic vibrator is driven at a frequency of 100 kHz or more, and the second ultrasonic vibrator is driven at 100 kHz.
It is driven at the following frequency. The distance between the inner surface of the reaction vessel constituting the first part and the side surface of the first cylinder is (（) or less of the wavelength of sound waves in water determined by the frequency of vibration of the first ultrasonic vibrator. The distance between the inner surface of the reaction vessel constituting the second part and the side surface of the second cylinder is not more than (１ ／) of the wavelength of sound waves in water determined by the frequency of vibration of the second ultrasonic vibrator. And

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 1 is a sectional view showing an embodiment of the water treatment apparatus of the present invention. The reaction vessel 10 has a rotationally symmetric axis, and has a first part 11 and a second part 12 adjacent to each other, each having a rotationally symmetric axis. The first part 11 and the second part
The section of the portion 12 perpendicular to the rotational symmetry axis is a circle. To make the inside of the reaction vessel 10 watertight, the opening of the first part 11 is closed by a first lid 21, and the opening of the second part 12 is closed by a second lid 22.

The first lid 21 has a first ultrasonic vibrator 313 connected to a drive power supply (not shown) and a vibration transmitter 31.
A first ultrasonic vibrating body 31 formed by sequentially connecting the second and the cylinders 311 is connected by a flange provided on the vibration transmitting body 312. The first ultrasonic vibrator 31 is disposed coaxially with the reaction vessel 10 and the first lid 12 and has a cylindrical shape 31.
1 is arranged so as to be included in the first portion 11 of the reaction vessel 10.

The second lid 22 has a second ultrasonic vibrator 321 connected to a drive power supply (not shown) and a vibration transmitter 32.
A second ultrasonic vibrating body 32, which is formed by sequentially connecting the second and the column 323, is connected by a flange provided on the vibration transmitting body 322. The second ultrasonic vibrator 32 is arranged coaxially with the reaction vessel 10 and the second lid 22, and has a column 323.
Is disposed so as to be included in the second portion 12 of the reaction vessel 10.

The water that has entered the reaction vessel 10 through the water pipes 411 and 412 passes through the water pipe 413 provided in the first lid 21, and first enters the first portion 11 of the reaction vessel 10. The ultrasonic vibrator 31 vibrates at a frequency of 100 kHz or more, and the water that has entered the first portion 11 particularly vibrates between the side surface of the column 311 and the inner surface of the reaction vessel 10. As a result, bubbles of various sizes existing in the water also oscillate.

As described in "Ultrasound Technology Handbook (New Edition): Nikkan Kogyo Shimbun, 1991, p.1085-p.1086", the respiratory vibration of this bubble is a non-linear vibration. Bubble of small size is rectify
Due to the effect of d diffusion, the cells grow into large bubbles. Therefore, when the water moves from the first part 11 to the second part 12, the water becomes a water containing many bubbles of several μm to several hundred μm.

The water flowing to the second portion 12 in this manner is subjected to the vibration of the second ultrasonic vibrator 32, especially between the side surface of the column 323 and the inner surface of the reaction vessel 10 at a frequency of 100 kHz.
The following ultrasonic vibrations are given. The water in the second portion 12 is crushed by an ultrasonic wave of 100 kHz or less, and contains many bubbles of several μm to several hundred μm that can generate a strong impact pressure. For this reason, microorganisms existing in water are subjected to the action of impact pressure with high probability and are mechanically destroyed.

The water sterilized in the second part 12 in this manner is supplied to the water pipe 423 provided on the second lid 22.
Through the pipes 422 and 421.

Next, the frequency of the first ultrasonic vibrators 31 and 32 will be described with reference to FIGS. Figure 2
FIG. 6 shows the results of a theoretical analysis when the bubble is assumed to be spherically symmetric. The equation of motion of the bubble is given by (Equation 1), assuming that the pressure inside the bubble is uniform, the vapor pressure of water is constant, and there is no gas diffusion inside and outside the bubble ("JB Kelleran").
dM. Miksis: Bubble oschilla
Tion of offset amplitude, Jo
urnal of Acoustic Society
of America, Vol. 68, No. 2, 1980,
p. 628-p. 633 ").

[0023]

(D ² R / dt ² ) {R (1-M) +4 m / r ₀ c ₀ } + (1/2) (dR / dt) ² (3-M) = (1 / r ₀ ) _{{P v - (1 + M} ) P 0 + (1-3kM) (P 0 + 2s / R 0) × (R 0 / R) 3k -2s / R-4mR t / R + Psinw (t + R / c 0)} ... ( number 1) In (Equation 1), R is the radius of the bubble, R ₀ is the initial radius of the bubble,
t is time, P is the pressure amplitude of the sound field, and w is each frequency of the sound field. r ₀ (= 1000 kg / m ³ ) is the density of water and m (=
1.31 × 10 ⁻³ Pa · s) is the viscosity coefficient of water, and s (=
7.2 × 10 ⁻² N / m) is the surface tension of water, P _v (= 1.
227 kPa) is the vapor pressure of water, c ₀ (= 1466 m /
s) is the speed of sound in water, k (= 1.33) is the specific heat ratio of gas,
M (= (dR / dt) / c ₀ ) is the Mach number.

For example, a reaction vessel 1 for the purpose of sterilization
0 in the second part 12 is 20 kHz
z (w = 3.14 × 10 ⁵ rad / s), and the pressure amplitude of the sound field is assumed to be P = 1.2 × 10 ⁵ Pa.

With respect to the sound pressure change shown in FIG. 2A, the temporal variation of the radius of the bubble having a radius of 10 μm at the beginning is shown in FIG.
(B), and the moving speed of the bubble wall at that time is shown in FIG.
(C). From the results shown in FIG. 2, it can be seen that the bubble collapses in about half a cycle, and a shock wave pulse is generated due to the large change in the moving speed of the bubble wall at that time.

A similar analysis was performed by setting the initial radius of the bubble to 5 μm.
m, 3 μm, and 2 μm, and the obtained results are shown in FIGS. 3 (A) to 3 (C) and FIGS.
(C) and FIGS. 5 (A) to 5 (C).

From the results shown in FIG. 2 to FIG.
There is little change in the impact pressure at the time of collapse of the bubble between the bubble having an initial m and the bubble having a radius of 5 μm.

It can be seen that the impact pressure is small for bubbles having a radius of 3 μm at the beginning, and no collapse of the bubbles is observed for bubbles having a radius of 2 μm at the beginning.

Therefore, when irradiating the second part 12 of the reaction vessel 10 with ultrasonic waves of 20 kHz, the bubbles having a radius of 3 μm or less in the first part 11 can be grown into bubbles having a radius of about 5 μm. The presence frequency (density) of the air bubbles to be crushed in the second portion 12 can be increased, and the sterilization efficiency is improved.

FIGS. 6 (A) to 6 (C) show that the pressure amplitude of the sound field is P = 1.2 × 10 ⁵ Pa, assuming the same as the above analysis, the frequency is 900 kHz, and the initial radius of the bubble is shown. 3 μm
It is an analysis result when it is set as. Under this condition, the bubbles gradually become larger, and the maximum radius becomes about 7 μm. Also, the change in the sound pressure of the sound field and the change in the radius of the bubble are in phase. Such a state is a state in which the bubble is resonating. Looking at the change in the radius of the bubble per cycle, the time when the radius is larger than the initial radius is smaller than the initial radius. Longer than. Therefore, the gas diffuses from the water into the bubble, and the pressure inside the bubble gradually increases, and as a result, the initial radius increases, that is, so-called r.
Optimized diffusion occurs.

From the above, for example, the first portion 11
Then, the first ultrasonic vibrator 31 is vibrated at 900 kHz to increase the frequency (density) of bubbles having an initial radius of about 5 μm, and the second ultrasonic vibrator 32 is By vibrating at 20 kHz and crushing bubbles of 5 μm or more, an efficient sterilizing effect can be obtained.

Since relatively small bubbles grow in the first portion 11, the frequency of the first ultrasonic vibrating body 31 is
Is necessarily higher than the frequency of the ultrasonic vibrator 32.
Since the frequency of the second ultrasonic vibrator 32 is desirably 100 kHz or less, which has a high mechanical destruction effect of cavitation, the frequency of the first ultrasonic vibrator 31 is 100 kHz.
Hz or higher.

Bubbles are present in the first portion 11 and the second portion, and when the vibrations of the bubbles become intense, a part of the water changes to a gas, so that the apparent acoustic impedance of the apparent water changes. Based on the above-described theoretical analysis of bubbles, for example, assuming that the initial radius of the bubbles is 4 μm and the frequency of occurrence (density) of the bubbles is 10 ¹⁰ bubbles / m ³ , water at a frequency of 25 kHz is assumed. FIG. 7 shows the values of the real part and the imaginary part of the time-averaged natural acoustic impedance (ρc) of the mixed fluid of air and bubbles with respect to the acoustic power.

As the acoustic power changes, the intrinsic acoustic impedance (ρc) of the mixture of water and bubbles greatly changes both in the real part and the imaginary part. In the water treatment apparatus according to the embodiment of the present invention, the first portion 11 and the second portion 12 in the reaction vessel 10 are:
Separate roles are divided between bubble growth and bubble collapse. In the first part, the sound power may be small because it is not necessary to crush the bubbles, and in the second part 12,
Relatively large sound power is required. Therefore, the specific acoustic impedance of the mixture of water and bubbles present in the first part 11 is significantly different from the specific acoustic impedance of the mixture of water and bubbles present in the second part 12. Therefore, a drive power source (not shown) for driving the first ultrasonic vibrator 31 and the second ultrasonic vibrator 32 is
It is desirable to separate them.

Cavitation occurs at a place where the sound pressure fluctuates greatly. Therefore, cavitation usually occurs remarkably near the ultrasonic vibration surface or at the antinode of the sound pressure in the standing wave sound field, but bubbles in the water are uniformly distributed. Therefore, the distance between the side surface of the column 311 and the side surface of the column 323 and the inner surface of the reaction vessel 10 is different from that of the water at the respective frequencies of the first ultrasonic oscillator 31 and the second ultrasonic oscillator 32, respectively. (１ ／) of the wavelength of
It is desirable to make the following.

[0036]

As described above, in the water treatment apparatus of the present invention, relatively small bubbles grow in the first portion and the second portion increases.
Water that has a high density of bubbles that can collapse and generate a strong impact pressure in the area flows to the second part and is further irradiated with ultrasonic vibration. Thus, an effective bactericidal action can be obtained. In addition, since small bubbles are grown, and the sound pressure distribution in the region where microorganisms are sterilized is uniform, there is no unevenness in the sound pressure distribution in the region where bubbles grow and the distribution of cavitation in the sterilized region. Bubble can be grown in the air, and microorganisms can be destroyed more efficiently.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a water treatment apparatus of the present invention.

FIG. 2 is a diagram showing an analysis result of a radial movement of a bubble in the embodiment of the present invention.

FIG. 3 is a diagram showing another analysis result of the radial movement of the bubble in the embodiment of the present invention.

FIG. 4 is a diagram showing another analysis result of the radial movement of the bubble in the embodiment of the present invention.

FIG. 5 is a diagram showing another analysis result of the radial movement of the bubble in the embodiment of the present invention.

FIG. 6 is a view showing another analysis result of the radial movement of the bubble in the embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the intrinsic acoustic impedance and acoustic power of a mixture of water and air bubbles in an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... reaction container, 11 ... 1st part, 12 ... 2nd part, 21 ... 1st lid, 22 ... 2nd lid, 31 ... 1st ultrasonic vibrator, 311 ... 1st cylinder, 312: first vibration transmitter, 313: first ultrasonic vibrator, 32: second ultrasonic vibrator, 321: second ultrasonic vibrator, 322: second vibration transmitter, 323 ... Second cylinder, 411-41
3,421-423 ... Piping.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Masuzawa 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Central Research Laboratory F-term (reference) 4D037 AA02 AB03 BA26 5D019 AA08 BB08 BB18 FF02 GG11

Claims (3)

[Claims] 1. A reaction vessel having first and second portions and having a rotationally symmetric axis, and a first lid having an inlet for water and covering an opening on the side of the first portion of the reaction vessel. A second lid having an outlet for water and covering an opening on the side of the second portion of the reaction vessel; a first ultrasonic transducer, a first vibration transmitter, a first cylinder; The first ultrasonic vibrator having a rotationally symmetric axis formed by sequentially coupling the first ultrasonic vibrator, the second ultrasonic vibrator, the second vibration transmitter, and the second cylinder are sequentially coupled by a rotationally symmetric axis. Second
Wherein the axis of rotational symmetry of the first ultrasonic vibrator and the axis of rotational symmetry of the reaction vessel coincide with each other, and the first column is included in the first portion. And supported by the first lid, the rotational symmetry axis of the second ultrasonic vibrator and the rotational symmetry axis of the reaction vessel coincide with each other, and one end face of the first cylinder and the The second column is supported by the first lid with the second column being included in the second portion, and the first ultrasonic vibrator is operated at a frequency of 100 kHz or more. The water treatment apparatus, wherein the second ultrasonic vibrator is driven at a frequency of 100 kHz or less. 2. The water treatment apparatus according to claim 1, wherein an inner surface of the reaction vessel constituting the first portion and the first surface of the reaction vessel.
Of the sound wave in water determined by the frequency of vibration of the first ultrasonic vibrating body is (1/1).
4) A water treatment device characterized by the following. 3. The water treatment apparatus according to claim 1, wherein an interval between an inner surface of the reaction vessel constituting the second part and a side surface of the second cylinder is equal to the distance of the second column. 2. The water treatment apparatus according to claim 2, wherein the wavelength is not more than (１ ／) of the wavelength of sound waves in water determined by the frequency of vibration of the ultrasonic vibrator.