JP2004350891A - Purification method and purification device - Google Patents

Abstract

An object of the present invention is to provide a purification method and a purification apparatus that can sterilize an object to be purified that passes at a high speed.
A streamer discharge is generated by applying a high voltage of a pulse waveform between a discharge electrode (3) having an insulator (10) in the vicinity of the discharge region (5) and a counter electrode (4). Sterilize and purify the object to be purified. By restricting the discharge region 5 by the insulator 10, it is possible to efficiently generate a streamer discharge without discharging to an extra place. Scattered particles such as radicals and potential differences can cause physical and chemical changes in microorganisms, odor components, and harmful components contained in the object to be purified, and the object to be purified that passes through the discharge region 5 at a high speed. Can also sterilize, deodorize and remove harmful substances.
[Selection] Figure 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a purification method and a purification apparatus for sterilizing and purifying an object to be purified such as air using streamer discharge.
[0002]
[Prior art]
Conventionally, using active particles such as ions and ozone, microorganisms existing on the surface of food-related objects such as foods and cooking utensils, the surface of objects where microorganisms pose a problem in public health, and the space that contains these objects Methods and devices for preventing breeding are known.
[0003]
For example, by controlling a discharge current when a gas such as air is introduced into the ionization chamber to ionize and ozonize, a gas containing a predetermined low concentration of ozone and a high concentration of ions is generated, and the ionization chamber or the There is a method of preventing the propagation of microorganisms by synergistic effect of ozone and ions by blowing gas generated in a communicating space or in an ionization chamber to an object (for example, see Patent Document 1).
[0004]
Further, when sterilizing an object to be sterilized by generating a pulse streamer discharge, the half width of a high-voltage pulse waveform to be applied is narrowed, and a high voltage peak and a sharp waveform are used to increase sterilization efficiency. There is a method (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-9-108313
[Patent Document 2]
JP-A-2002-263170
[Problems to be solved by the invention]
However, the method utilizing the synergistic effect of ozone and ions described above is intended for processing microorganisms present on the surface of an object or a storage space, and is therefore applied to equipment in which gas flows at a very high speed. However, there is a problem that the effect is small, and the microorganisms often pass through without being damaged.
[0008]
Further, in the sterilization method using pulse streamer discharge, there is a problem that streamer discharge cannot be efficiently generated and sterilization cannot be sufficiently performed only by using a high-voltage pulse waveform having a high voltage peak and a sharp shape. there were. Similarly to the above, there is a problem that the effect is small even when applied to a device in which gas flows at a very high speed.
[0009]
An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a purification method and a purification apparatus that can sterilize an object to be purified that passes at a high speed.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the purification method of the present invention generates a streamer discharge by applying a high voltage of a pulse waveform between a discharge electrode and an opposite electrode having an insulator for regulating a discharge region in the vicinity. It is characterized in that the object to be purified present in the discharge region is sterilized and purified.
[0011]
Further, the purification device of the present invention includes a discharge electrode and a counter electrode, a high voltage applying means for applying a high voltage having a pulse waveform for generating a streamer discharge between these electrodes, and a discharge region provided near the discharge electrode. A regulating insulator.
[0012]
As described above, since the discharge region is regulated by the insulator, the streamer discharge per unit area is strengthened without discharging to an extra place, and the streamer discharge can be efficiently generated. And the scattering of particles, such as electrons, ions, and radicals, scattered at high speed in the discharge area, and the potential difference can cause physical and chemical changes in microorganisms, odorous substances, and harmful substances contained in the purification target. As a result, it is possible to sterilize, deodorize, and remove harmful substances even from a purification target that passes through the discharge region at a high speed. The object to be purified may be a gas, a liquid, or a solid.
[0013]
For example, the discharge electrode is formed in a strip shape, and the insulator is set on one side of the discharge electrode, and is provided so as to surround the discharge electrode such that the discharge portion on the other side is exposed. According to this, the discharge region can be restricted to one side of the discharge electrode.
[0014]
Alternatively, the discharge electrode is formed in a band shape having a plurality of protrusions on one side, and an insulator is provided so as to surround the discharge electrode so that the protrusions are exposed. According to this, the discharge region can be restricted to one side of the discharge electrode, and the discharge from the tip of the protrusion becomes the majority, so that the overlap between the discharge regions of each protrusion is a flat surface set at the same pitch. As compared with the overlapping of the discharge regions of the respective discharge portions, the discharge regions can be reduced, and more efficient streamer discharge can be realized.
[0015]
Preferably, a filter for filtering an object to be purified passing through the discharge region is provided downstream of the discharge region. Thereby, the purifying effect can be further enhanced. The installation space of such a filter is made possible without restricting the size of the device by restricting the discharge area to one side (upstream side) of the discharge electrode.
[0016]
Preferably, the high voltage applying means controls the frequency at which the high voltage having the pulse waveform is applied at least once within the passage time of the purification target passing through the discharge region. As a result, microorganisms, odor components, and harmful components contained in the object to be purified encounter streamer discharge at least once, and can be effectively purified.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are cross-sectional views of a purification device according to an embodiment of the present invention. In the purification unit 1, a purification unit 2 disposed in a flow path of a gas such as air includes a plurality of discharge electrodes 3 arranged in a plurality of stages, and a flat counter electrode 4 sandwiches the discharge electrodes 3 in each stage. The discharge regions 5 are arranged in parallel so that a discharge region 5 is formed between each discharge electrode 3 and the counter electrode 4.
[0018]
However, an insulator 10 for regulating the discharge region 5 is provided near the discharge electrode 3. Specifically, as shown in FIG. 3, the discharge electrode 3 is formed in a band shape having a protrusion 3 a on one side, and the insulator 10 is formed in a cylindrical shape covering the band-shaped discharge electrode 3. In addition, a plurality of holes 10a exposing the protrusions 3a are formed on one side along the longitudinal direction, and the discharge region 5 is formed on one side of the discharge electrode 3 by the respective protrusions 3a. I do.
[0019]
For this reason, the discharge region 5 formed by each protrusion 3a is continuous with one side of the discharge electrode 3 along the longitudinal direction of the discharge electrode 3, and the discharge electrode 3 and the counter electrode 4 are interposed in a direction perpendicular to the discharge region. It is continuous with each other and occupies an area larger than the airflow passage area 6. 7 indicates an upstream airflow flowing into the airflow passage area 6, and 8 indicates a downstream airflow flowing out of the airflow passage area 6.
[0020]
The high voltage application device 9 has a plus electrode 9a connected to the discharge electrode 3 and a minus electrode 9b (or ground 9b) connected to the counter electrode 4, and a streamer discharge between the discharge electrode 3 and the counter electrode 4. Is applied so as to apply a high voltage having a pulse waveform capable of generating the following.
[0021]
As the high voltage application device 9, for example, a switching means such as an IGBT (Insulated Gate Bipolar Transistor) is provided in a voltage doubler circuit to generate a voltage having a desired pulse waveform and a high frequency, and boost the voltage with a high voltage transformer. An electric circuit or the like is used. Here, the applied current on the primary side of the high voltage transformer is increased, and a high voltage with a distorted pulse waveform is applied. However, the high voltage application device 9 is not limited to this and can be used as long as it can apply a high voltage having a desired pulse waveform and frequency.
[0022]
Hereinafter, the operation of the above configuration will be described.
A high voltage having a predetermined pulse waveform, that is, a high voltage having a distorted pulse waveform, is applied between the discharge electrode 3 and the counter electrode 4 by the high voltage applying device 9, and thereby a streamer discharge (hereinafter, referred to as a pulse) is applied to the discharge region 5. Streamer discharge).
[0023]
At this time, since the insulator 10 is provided as described above, the discharge region 5 is regulated so as to be formed only on one side (upstream side) of the discharge electrode 3, so that the discharge is efficiently performed without discharging to an extra place. Streamer discharge can be generated. For reference, FIG. 4 shows a discharge region 5 when the strip-shaped discharge electrode 3 is installed without an insulator. The discharge region 5 is formed so as to surround the entire discharge electrode 3.
[0024]
The generation mechanism of the pulse streamer discharge is such that the neutral molecules are ionized in front of the electrons emitted from the discharge electrode 3 and the electrons are emitted like an avalanche, which causes the next new avalanche. Occur one after another and coalesce and proceed at high speed, and most of the discharge current is due to electrons.
[0025]
At that time, since there is a remarkable electric field concentration near the discharge electrode 3 between the discharge electrode 3 and the counter electrode 4, if the applied high voltage is large enough, an avalanche of electrons will occur, and Ions and photons are created. At this time, since the discharge electrode 3 is a positive electrode, a large amount of photons are emitted in the vicinity of the discharge electrode 3, and the emitted photons are absorbed by neutral molecules in the vicinity to generate ionization. A large number of avalanches in the direction toward the discharge electrode 3 are generated, and a plasma column is formed in the simultaneously generated positive ions. At the front edge of the plasma column, positive ions toward the counter electrode 4 (that is, a negative electrode or an electrode connected to the ground) are concentrated at a high density, thereby causing a concentration of an electric field, a space charge of these positive ions and an avalanche of electrons. Since a particularly strong electric field is formed between the group space charges, the emission at the leading edge of the plasma column is further enhanced.
[0026]
Since such a pulse streamer discharge occurs in the discharge region 5, if microorganisms are contained in the upstream airflow 7 flowing into the discharge region 5, a large amount of scattered particles (such as electrons) scattered at high speed in the discharge region 5. Electrons emitted from the discharge electrode 2; gas molecules (neutral molecules), electrons derived therefrom, positive ions, radicals, etc.), potential differences, etc., destroy the outer wall of microorganisms and proteins, and damage DNA and RNA. That is, the microorganisms are killed or inactivated.
[0027]
Further, for example, when NH ₃ (ammonia), which is an odorous substance and a harmful substance, is contained, even if the energy level is stable at the time of inflow, energy is supplied due to scattered particles in the discharge region 5, potential difference, etc. Leads to a reaction. NH ₃ is decomposed into N and H in the first step, and is unstable as it is, so that it is changed to N ₂ (nitrogen) and H ₂ (hydrogen) in the second step, and further to H ₂ O (water). And become odorless and harmless.
[0028]
Therefore, by mounting the purification unit 1 on an air conditioner having a large air volume, for example, the air conditioner can have purification performance of sterilization, deodorization, and removal of harmful substances. However, instead of disposing the purifying unit 2 in the gas flow path, a gas may be sealed in the purifying unit 2. A liquid such as a solid or water as a purification target may be disposed in the discharge region 5.
[0029]
As shown in FIG. 5, the discharge electrode 3 is formed in a strip shape, the insulator 10 is formed in a cylindrical shape covering the discharge electrode 3, and a predetermined discharge portion 3b of the electrode 3 is provided on one side along the longitudinal direction. The same effect can be obtained by forming a plurality of holes 10b exposing the discharge electrode 3 so as to regulate the discharge region 5 on one side of the discharge electrode 3.
[0030]
As shown in FIG. 6, it is desirable to provide a filter 11 on the downstream side of the discharge region 5 of the purification unit 2. As a result, dust, killed or inactivated bacteria, ozone generated by pulse streamer discharge, and the like can be separated and collected, and the purification effect is enhanced. The installation space of such a filter 11 is made possible by restricting the discharge region 5 to one side (upstream side) of the discharge electrode 3 without increasing the size of the device. As the filter 11, for example, an activated carbon filter or a Mn-based catalyst filter can be used, but is not limited thereto.
[0031]
The high voltage to be applied between the discharge electrode 3 and the counter electrode 4 is a high voltage having a pulse waveform that can efficiently generate a pulse streamer discharge, and varies depending on the size of the gap between the two electrodes. For example, about 7 kV or more when the gap is about 10 mm, about 6 kV or more when about 8 mm, and about 4 kV or more when about 5 mm.
[0032]
The high voltage of the pulse waveform at this time is a high-voltage pulse having a distorted waveform as described above, that is, a high-voltage pulse having a plurality of peaks at the pulse top, which efficiently generates a pulse streamer discharge. It is desirable to make it. There is no particular limitation on the number of peaks, whether the peaks are at the same height, or there is a height difference. It may or may not be accompanied by a high voltage pulse without distortion. However, when efficiency is not desired, for example, a long time for purification can be secured, a high voltage without distortion may be used.
[0033]
For reliable purification, the relationship between the speed of the airflow passing through the discharge region 5 and the pulse frequency of the high voltage is important. Microorganisms, odorous substances, and harmful substances (hereinafter, referred to as contaminants, which correspond to any one point in the airflow) in the airstream can generate a pulse streamer discharge at least once while passing through the discharge region 5. Frequency is needed.
[0034]
For example, in the case of an air conditioner, the speed of the airflow passing through the indoor unit is about 1 m / s. Therefore, when the width of the discharge region 5 in the airflow passage direction is about 10 mm, pollutants in the airflow are discharged in the discharge region in about 10 msec. Pass 5 Therefore, by applying a high voltage at about 100 Hz, the contaminants passing through the discharge region 5 can be once encountered by the pulse streamer discharge.
[0035]
For more reliable purification, a high voltage having a high frequency of several hundreds to several tens of times the frequency of about 100 Hz, that is, several hundreds to several thousand Hz may be applied. Conversely, by applying such a high-frequency high voltage, even when the airflow passes through the discharge region 5 at a very high speed, the pollutants in the airflow can be reliably purified. Such high frequencies are not essential if the gas, liquid, or solid to be purified is stationary.
[0036]
At this time, by setting the pulse width to the minimum pulse width, it is possible to instantaneously raise the voltage, whereby a larger amount of electrons can be scattered at high speed in the discharge region 5 and the voltage application time can be reduced. It becomes possible to reduce the generation of ozone harmful to the human body by shortening, and to suppress spark discharge. Although a pulse width as small as possible is desirable, a preferable purification effect can be obtained by setting the pulse width to about 1 μsec or less.
[0037]
In addition, by applying a high voltage having a negative pulse waveform, negative ions can be generated in the discharge region 5, and the downstream airflow 8 containing the negative ions can flow out to provide a relaxing atmosphere. Become.
[0038]
Examples of usable high-voltage waveforms are shown in FIGS.
FIG. 7 shows a pulse waveform close to a sine wave or a vibration waveform. Among the one-cycle pulse trains in which three sets of positive and negative pulses are alternately arranged, the pulse top of the positive pulse having the largest amplitude is distorted. As shown in the enlarged view, the distortion portion A has a first peak p1 and a higher second peak p2. The pulse width of this pulse is a minimum pulse width (μsec).
[0039]
FIG. 8 shows a positive pulse waveform, and FIG. 9 shows a negative pulse waveform. In both pulse waveforms, the pulse top having the largest amplitude is distorted in a one-cycle pulse train in which three positive or negative pulses are arranged.
[0040]
FIG. 10 shows a positive pulse waveform, and FIG. 11 shows a negative pulse waveform. In both pulse waveforms, a positive or negative pulse is repeated at a constant cycle, and the pulse top of each pulse is distorted.
[0041]
FIG. 12 shows a positive pulse waveform similar to that of FIG.
It goes without saying that a similar rectangular pulse waveform may be used.
[0042]
【The invention's effect】
As described above, according to the present invention, by providing an insulator that regulates a discharge region in the vicinity of a discharge electrode, it is possible to efficiently generate a streamer discharge without discharging to an extra place, , A purification target such as sterilization, deodorization, or removal of harmful substances can be effectively performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a purification device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the purification device of FIG. 1 from another direction. FIG. FIG. 4 is a cross-sectional view of a conventional purification device shown for comparison with the discharge region of the purification device of FIG. 1; FIG. 5 is another view which can be installed in the purification device of FIG. FIG. 6 is a plan view of a discharge electrode and an insulator. FIG. 6 is a cross-sectional view illustrating a schematic configuration of a purification device according to another embodiment of the present invention. FIG. 7 is a first example of a high-voltage waveform applied by the purification device of the present invention. FIG. 8 is a waveform diagram of a second example of a high voltage applied by the purification device of the present invention. FIG. 9 is a waveform diagram of a high voltage of a third example applied by the purification device of the present invention. FIG. 11 is a waveform diagram of a fourth example of a high voltage applied by the purification device of the present invention. Waveform diagram of a sixth example of a high voltage applied by the purifying apparatus of the waveform diagram Figure 12 the invention [Description of symbols]
DESCRIPTION OF SYMBOLS 1 ... Disinfection unit 3 ... Discharge electrode 3a ... Protrusion 3b ... Discharge part 4 ... Counter electrode 5 ... Discharge area 6 ... Air flow passage area 9 ... High voltage application device 10 ... Insulator 10a ... Hole 10b ... Hole 11 ... Filter

Claims (6)

A high voltage having a pulse waveform is applied between a discharge electrode having an insulator in the vicinity of a discharge region and a counter electrode to generate a streamer discharge, and a purification target existing in the discharge region is sterilized and purified. Purification method. A discharge electrode and a counter electrode, high voltage applying means for applying a high voltage having a pulse waveform for generating a streamer discharge between these electrodes, and an insulator provided near the discharge electrode and regulating a discharge region. Purification device. The purification device according to claim 2, wherein the discharge electrode is formed in a strip shape, and the insulator is provided so as to surround the discharge electrode so that a predetermined discharge portion set on one side of the discharge electrode is exposed. The purification device according to claim 2, wherein the discharge electrode is formed in a band shape having a protrusion on one side, and an insulator is provided so as to surround the discharge electrode such that the protrusion is exposed. The purification device according to any one of claims 2 to 4, further comprising a filter for filtering an object to be purified that passes through the discharge region, provided downstream of the discharge region. The purification according to any one of claims 2 to 5, wherein the high voltage applying means is controlled to a frequency at which a high voltage having a pulse waveform is applied at least once within a passage time of the purification target passing through the discharge region. apparatus.

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