JP2003199812A - Method for sterilizing air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for sterilizing indoor supply air of the air conditioning system of a building or the like, having sufficient sterilization effect, reducing the adverse effect on the health of a person, low in cost and reducing the use amount of a sterilizing solution. <P>SOLUTION: In the method for sterilizing the air conditioning system, the sterilizing solution is sprayed on indoor supply air of the air conditioning system to sterilize the same. In the method for sterilizing the indoor supply air of the air conditioning system, the indoor supply air of the air conditioning system is filtered by a filter and the sterilizing solution is sprayed on the filter or the filter is wetted with the sterilizing solution. The sterilizing solution is a chlorine-containing aqueous solution containing effective chlorine content in a concentration of 0.2-1,000 ppm or a hypochlorous acid-containing aqueous solution of which the pH is adjusted to 2.0-8.0 by adding an acid. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sterilizing indoor air supplied to an air conditioning system of a building.

[0002]

2. Description of the Related Art At present, infectious diseases such as Legionella bacteria and local illnesses are becoming a serious problem, and sterilization of indoor air supply for air conditioning systems such as buildings is a serious problem. Conventionally, for stored water or circulating water, these bacteria, bacteria,
It has been known and used that chlorine-based bactericides and organic drugs are effective for suppressing the growth of mold and algae. Not only are organic drugs harmful to the human body, they also cause the development of resistant bacteria, which makes us hesitant to use them. Chlorine-based bactericides are preferable because they are less harmful to humans and do not generate resistant bacteria. However, chlorine has drawbacks such as accelerated damage to mechanical equipment and generation of chlorine odor. Therefore, there has been a demand for a method of sterilizing indoor air supplied to an air conditioning system of a building or the like that can sterilize with a chlorine-based sterilizing agent in the smallest possible amount.

[0003]

[Problems to be Solved by the Invention] A sterilizing method for indoor supply air of an air conditioning system such as a building, which has a sufficient sterilizing effect, has less adverse effects on human health, is inexpensive, and can use a small amount of sterilizing liquid. Is to provide.

[0004]

Means for Solving the Problems The present inventor has found that the above problems can be achieved by a sterilizing method of an air conditioning system in which sterilizing water is sprayed on indoor air supplied to the air conditioning system to sterilize the air. Further, it can be achieved by a method of sterilizing the indoor supply air of the air conditioning system by spraying or wetting the filter with sterilizing water in the air conditioning system which filters the indoor supply air of the air conditioning system. Furthermore, the sterilizing solution is an aqueous solution containing chlorine, and the sterilizing solution has an effective chlorine concentration of 0.2 to 1000 ppm and a pH of 2.0 to 8.
This can be achieved by the sterilization method of the air conditioning system, which is an aqueous solution containing hypochlorous acid adjusted to 0. In the present invention, the term sterilization is used as a term including the concepts of antibacterial, antifungal, disinfecting, sterilizing, sterilizing, sterilizing and deodorizing.

One of the sterilization methods for the indoor supply air of the air conditioning system of the present invention is a method of spraying a sterilizing solution on the indoor supply air. As a result, it becomes possible to more effectively sterilize with a smaller amount of sterilizing liquid than when a sterilizing agent is added to cooling water. As the spraying method, any known method can be used.

Another method of sterilizing the indoor supply air of the air conditioning system of the present invention is a method of filtering the indoor supply air with a filter and spraying or moistening the sterilizing liquid on the filter. Similar to the method described above, this method also enables more effective sterilization with a smaller amount of sterilizing solution than adding a sterilizing agent to cooling water. The method of wetting the filter with the sterilizing solution is not particularly limited, but any method such as supplying the sterilizing solution from the upper part of the filter, supplying the sterilizing solution from the lower part of the filter and sucking it up by capillary action, or supplying the sterilizing solution from the side of the filter is possible. Good. Further, it is preferable to install the filter at a position further indoors than the filter for spraying the sterilizing liquid or moistening the sterilizing liquid. This is preferable because the sterilizing liquid can be prevented from entering the room.

The filter is not particularly limited, but a membrane filter can be used. As this material, cellulose, cellulose acetate, diacetyl cellulose, triacetyl cellulose,
Preference is given to polyolefins such as nitrocellulose, polystyrene, polyethylene, polypropylene, acrylonitrile and PTFE.

The sterilizing solution of the present invention will be described. The sterilizing solution of the present invention is preferably used as long as it contains chlorine ions. Particularly, a sterilizing solution containing hypochlorous acid and chlorine dioxide is preferable. Effective chlorine concentration of sterilizing solution is 0.2
-1000 ppm is preferable. 0.5-300 ppm is more preferable, and 1-150 ppm is the most preferable. Further, the pH is preferably 2.0 to 8.0, more preferably 4.0 to 7.2, and most preferably 4.5 to 6.5. It is desirable that the effective chlorine concentration is the minimum required concentration to exert the bactericidal effect.
If the concentration is high, there is an unfavorable effect such as chlorine odor, and if the concentration is low, a sufficient bactericidal effect cannot be obtained. The bactericidal effect varies with temperature. At temperatures near room temperature, higher temperatures have a greater bactericidal effect. pH is an important factor that determines the concentration of undissociated hypochlorous acid. When the pH is 8 or more, hypochlorous acid is dissociated and the bactericidal effect is significantly reduced. Also, the pH is 2
Chlorine is emitted below and is harmful to the human body.

Hypochlorous acid is supplied as a hypochlorite or an aqueous solution of hypochlorous acid. The hypochlorite is not particularly limited, but sodium hypochlorite and potassium hypochlorite are preferable.

The pH of the sterilizing solution of the present invention is preferably adjusted by adding an inorganic acid such as hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid, or an organic acid such as acetic acid, formic acid, citric acid and tartaric acid. . Although not usually required, an alkali such as sodium hydroxide can be added when the pH becomes too low. As the acid, hydrochloric acid, phosphoric acid, acetic acid, citric acid and tartaric acid are more preferable, hydrochloric acid and acetic acid are further preferable, and hydrochloric acid is particularly preferable. When adjusting these pHs, it is preferable to dilute both the acid and the alkali with water. In particular,
When adjusting the pH to between 5.0 and 7.0, it is preferable to use a sufficiently diluted acid.

Further, an aqueous solution of acid and alkali, an aqueous solution of hypochlorous acid (preferably an aqueous solution of sodium hypochlorite) and water are mixed to prepare an aqueous solution of hypochlorous acid having a predetermined concentration and pH. It does not matter whether this preparation is carried out well before use or just before use. However, since hypochlorous acid in the aqueous solution of hypochlorous acid is unstable with respect to heat, light and an oxidizing agent, it is preferable to put it in a closed container, shield it from light and store it at a low temperature. It is preferable to use a sufficiently washed container. Further, in order to accurately adjust the concentration of each composition to a predetermined value, it is preferable to use a mixing device capable of adjusting the addition amount with high precision. With this device, the hypochlorous acid aqueous solution can be prepared immediately before use. In that case, an aqueous solution of acid or alkali, an aqueous solution of hypochlorous acid (preferably an aqueous solution of sodium hypochlorite) and water can be mixed, or an aqueous solution of acid or alkali and / or It is also preferable to use an aqueous solution of chlorous acid (preferably an aqueous solution of sodium hypochlorite) diluted with water to a predetermined concentration in advance. The method for adjusting the hypochlorous acid-containing sterilizing solution of the present invention is not particularly limited, but a sodium hypochlorite aqueous solution on one side of the container separated by a porous filter, water on the other side. A continuous mixing apparatus in which hydrochloric acid diluted with is added, and both solutions are gradually mixed through a filter to adjust to a predetermined pH is preferable. As these methods, the method described in Japanese Patent No. 2852461 is preferably used. Further, these solutions are preferably stored in a closed container, and more preferably in the form of a cartridge which can be easily attached and detached.

The sterilizing solution of the present invention may be electrolyzed of water containing chlorine ions to prepare an aqueous solution of hypochlorous acid. Further, it is preferable to electrolyze water containing sodium chloride and / or potassium chloride. Further, the electrolysis can be carried out in a diaphragm electrolyzer or a non-diaphragm electrolyzer. In the case of a diaphragm electrolyzer, patent type application number 63-
The technique described in 300998 is preferably used. Further, in the case of the diaphragmless electrolytic cell, the technique described in Patent Registration 2619756 is preferably used. For these electrolysis methods, the methods described in "Basics and Utilization Technologies of Electrolyzed Water" (Masaki Matsuo, Gihodo Publishing Co., Ltd., issued January 25, 2000) can be preferably used.

The pH of the sterilizing solution of the present invention can also be adjusted with a pH buffer. Also, the pH of the aqueous solution of hypochlorous acid
It is also preferred to use a pH buffer to adjust the pH. The pH buffer solution is a solution in which a change in pH (hydrogen ion concentration) when an acid or a base is added to the solution is smaller than a change in pH when an acid or a base is added to pure water. The pH buffer solution can be obtained by mixing an acid, a base, or a salt thereof. As an example of the pH buffering agent, any of those described in the second edition, pages 336 to 339, of the revised fourth edition of the Chemical Handbook (September 1993, Maruzen Publishing Co., Ltd.) is preferably used. it can.

The concentration of each component of these pH buffers is preferably any concentration as long as the required pH can be obtained. When used for a short period of time after opening, it is preferable that the concentration of each component of the pH buffer solution is low, and for a sterilizing solution for hands used for a long period after opening, the concentration of each component is preferably high. The method of mixing the components can be used in any order.
The hypochlorous acid may be mixed either after completion of the pH buffer solution or before completion. The mixing of hypochlorous acid and pH buffer may be done at any time prior to use.

It is also preferred that the hypochlorous acid aqueous solution contains a spreading agent. For the hypochlorous acid aqueous solution of the present invention. As the spreading agent, any of anionic, cationic, nonionic and betaine surfactants and water-soluble polymers are preferably used. The concentration of the spreading agent is preferably 20 to 2000 ppm. Linear alkyl benzene sulfonate, dialkyl succinate, lignin sulfonate, polynaphthyl sulfonate, sulfonate of alkyl ester of fatty acid (JP-A-2-167202, etc.) Alkyl sulfosuccinate-based anion, etc. System surfactant. Polyacrylic acid salt, alkyl sulfate, alkyl amine oxide, cationic surfactant such as chitosan having a degree of deacetylation of 30% or more and quaternary ammonium salt are preferably used. Among them, monoalkyl sulfate, trialkylamine-N-oxide, sodium fatty acid, and alkyltrimethylammonium are particularly preferable. Although the spreading agent may be added well before use, it is preferably added just before use. In actual use, it is preferable to mix it with an acid for pH adjustment or with dilution water. It is not preferable to add it to the aqueous solution of hypochlorous acid in advance because it may accelerate the decomposition of hypochlorous acid.

The preparation method of the sterilizing solution of the present invention is not particularly limited, but when it is stored after mixing, it is stored at a low temperature by blocking light, especially ultraviolet rays, and as an organic substance or an impurity such as protein and alcohol. It is preferable to minimize the amount of metal ions mixed in. Therefore, it is preferable to use thoroughly washed containers and instruments. When the hypochlorous acid-containing aqueous solution itself is also stored, it is preferable to block light, especially ultraviolet rays, and store at low temperature.

The method for sterilizing an air conditioning system (such as a cooling tower) of the present invention is used for preventing the reproduction of bacteria, bacteria, algae and mold. It is also effective in preventing poisoning caused by Legionella bacteria, and local military illness. Mucor, Alternaria, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus,
Lactic acid bacteria, actinomycetes, Legionella, salmonella, black mold, blue mold, cladosporium, fusarium, white bacterium, candida, exophyala, saccharomyces,
It can be used to suppress or reduce microorganisms, molds, moss, algae, slime, etc., which are generally targeted by water filtration such as Acantham, Nichia, Cladomonas, Hematomacox, Oshiratoria, Formidium, Ring beer, and Crococox.

Specific examples of the present invention will be described below.

[Comparative Example 1] A sodium hypochlorite aqueous solution was added to one side of a container separated by a porous filter, and hydrochloric acid diluted with water was added to the other side of the filter, and both solutions were gradually mixed through a filter. The pH was adjusted to 5.7 and a sterilizing solution (hypochlorous acid aqueous solution) having an effective chlorine concentration of 2 ppm was prepared. This was used as cooling water for the air conditioning system (cooling tower) to sterilize the circulation system of the air conditioning system (cooling tower).

Comparative Example 2 Comparative Example 1 was repeated except that tap water was used instead of the sterilizing solution.

Example 1 After cooling the indoor supply air of an air conditioning system (cooling tower), the sterilizing liquid of Comparative Example 1 was sprayed on the air (wind) to sterilize the air (wind). Then, this sterilized air was supplied to the room.

[Embodiment 2] After cooling the indoor supply air of an air conditioning system (cooling tower), the filter is sprayed with the sterilizing liquid of Comparative Example 1, the cooled air (wind) is guided to the filter, and then this air is supplied indoors. did.

[0019]

[Embodiment 3] The indoor supply air of each of Comparative Examples 1 and 2 and Examples 1 and 2 is guided to the bottom of a water tank filled with a pipe, air is passed through the water in the water tank, and then air is supplied indoors. An experimental device was supplied. After operating the air conditioning system (cooling tower) for 7 consecutive days using this experimental apparatus, the number of bacteria in the water in the water tank was measured by a predetermined method. Comparative example 2
Although a small amount of Legionella bacteria was detected from the water in the water tank through which the air was passed, Legionella bacteria were not detected from the water in the water tanks of Comparative Example 1 and Examples 1 and 2. The amount of the sterilizing liquid used in the air conditioners of Examples 1 and 2 was 1/300 or less of the amount of the sterilizing liquid used in the air conditioner of Comparative Example 1. The method for sterilizing the indoor supply air of the air conditioning system (cooling tower) of the present invention in Examples 1 and 2 was preferable to the method for sterilizing the air conditioning system (cooling tower) in Comparative Example 1 because the amount of the sterilizing liquid used was small.
In addition, the sterilizing effect of the air conditioning system (cooling tower) of Comparative Example 2 was much larger and was preferable.

(Test method for detection of Legionella spp.) 400 mL of sample water is concentrated 100 times by cooling centrifugal precipitation treatment at 6000 rpm for 30 minutes, and heat treatment is performed at 50 ° C. for 20 minutes. Then, 50 μL of the solution is applied to a WYOα medium having the composition shown in Table 1 and cultured aerobically at 37 ° C. On the 7th day of culturing, several colonies judged to be Legionella spp. Were picked up from the situation of the colonies, and each colony was subcultured into two types of medium, BCYEα plate medium and 5% blood agar medium, and incubated at 37 ° C. Culture aerobically. On the second day of culture, colonies that grew on BCYEα plate medium and did not grow on 5% blood agar medium were confirmed to be Legionella spp. Due to L-cysteine requirement, and the number of colonies of the same species on WYOα medium was counted. The detection limit by this method is 20 pieces / 10
It is 0 mL.

WYOα medium Pure water 1000 mL Yeast extract 10.0 g ACES buffer 10.0 g L-cysteine monohydrochloride 0.4 g Soluble iron pyrophosphate 0.25g α-ketoglutaric acid 1.0 g Glycine 3.0 g Amphotericin B 80.0 mg Polymyxin B 100000 U Vancomycin 5.0 mg Activated carbon powder 1.5 g Agar 15.0 g pH 6.9

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Claims (4)

[Claims] 1. A sterilizing method for an air conditioning system, which comprises sterilizing by spraying sterilizing water on air supplied to the room of the air conditioning system. 2. An air conditioning system for filtering indoor supply air of an air conditioning system with a filter, wherein the indoor supply air of the air conditioning system is sterilized by spraying or moistening sterilizing water on the filter. Sterilization method. 3. The sterilizing method for an air conditioning system according to claim 1, wherein the sterilizing solution is an aqueous solution containing chlorine. 4. The sterilizing solution has an effective chlorine concentration of 0.2 to 100.
The method for sterilizing an air-conditioning system according to claim 3, wherein the solution is a hypochlorous acid-containing aqueous solution having a pH of 0 ppm and adjusted to 2.0 to 8.0.