Sterilized water production apparatus and sterilized water production method

Abstract

[Problem] To provide a device for producing sterile water containing hypochlorous acid or chlorous acid as a main component by making the pH more stable. [Solution] This device for producing sterile water containing hypochlorous acid or chlorous acid comprises, between a raw material water inlet 1 and a sterile water outlet 2: a carbonic acid gas-injecting pipe 4 having a check valve 3; a sodium hypochlorite aqueous solution- or sodium chlorite aqueous solution-injecting pipe 6 having a check valve 5; and a stirring tank 7 having a static mixer 8 in which stirring blades are inserted into a pipe. A main pipe 9, which has a water pumping part for sending raw material water 14 upward and extends from the raw material water inlet 1 to the inlet of the stirring tank 7, is connected to the carbonic acid gas-injecting pipe 4 and the sodium hypochlorite aqueous solution- or sodium chlorite aqueous solution-injecting pipe 6 in this order in a state where the sodium hypochlorite aqueous solution- or sodium chlorite aqueous solution-injecting pipe 6 is placed on the upper side, so that the main pipe 9 is connected to the inlet of the stirring tank 7. The lower part of the pipe of the static mixer 8 in the stirring tank 7 has a hole serving as an inlet 13 for the raw material water to which carbonic acid gas and a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution are added, and a discharge pipe 18 for discharging sterile water 15 containing hypochlorous acid or chlorous acid from the sterile water outlet 2 is connected to the outlet of the pipe of the static mixer 8.

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for producing bactericidal water containing hypochlorous acid or chlorous acid.

Background Art

[0002] It is widely known that bactericidal water mainly composed of hypochlorous acid or chlorous acid is harmless to the human body and has an excellent bactericidal effect. Hypochlorous acid is contained in a sodium hypochlorite aqueous solution obtained by diluting sodium hypochlorite with water to have an available chlorine concentration of about 200 ppm and a pH value of about 8.6 at about 10%. It has been known for a long time that the ratio of hypochlorous acid increases by lowering the pH value to make it a weak acid, and it becomes almost 100% when the pH value is near 5.

[0003] As a method for producing bactericidal water mainly composed of hypochlorous acid or chlorous acid, a method of mixing a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution with an acidic aqueous solution such as hydrochloric acid is known.

[0004] FIG. 5 shows the respective existence ratios when chlorine molecules, hypochlorous acid, and hypochlorite ions are in an equilibrium state at each pH. 501 in FIG. 5 shows the existence ratio of hypochlorous acid, and the existence ratio of hypochlorous acid exceeds 80% in the range of approximately pH 4 to pH 7. From this, it can be said that in order to stably exist hypochlorous acid, it is necessary to stably maintain the pH in the range of 4 to 7.

[0005] FIG. 4 shows the respective existence ratios when carbonic acid, bicarbonate ions, and carbonate ions are in an equilibrium state at each pH. 401 in FIG. 4 shows the existence ratio of bicarbonate ions, and the existence ratio is high from pH 6 to pH 10. In this pH range, bicarbonate ions having a buffering action against pH changes exist, so the pH of the solution hardly changes.

[0006] In order to stably produce bactericidal water, it is important to efficiently and stably generate bicarbonate ions with a buffering action and keep the bactericidal water at a weakly acidic pH of 6 to 7 where hypochlorous acid can stably exist.

[0007] As another example of a method for producing bactericidal water mainly composed of hypochlorous acid, a method of electrolyzing an aqueous hydrochloric acid solution is known. Furthermore, by injecting an aqueous sodium chloride solution into an electrolytic cell having a diaphragm between the anode and the cathode and electrolyzing it, a method of generating an aqueous hypochlorous acid solution on the anode side, or a method of directly electrolyzing a mixed aqueous solution of hydrochloric acid and sodium chloride to produce it is known.

[0008] Also, as a method of using the bactericidal water produced by the above method, there is a method of mixing an aqueous sodium hypochlorite solution and an acidic aqueous solution with a dedicated device to generate it, or generating bactericidal water with a dedicated electrolytic device and taking out the bactericidal water discharged from the device from a stop valve or a faucet for use.

[0009] The method of producing bactericidal water by mixing an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution with an acidic aqueous solution has the advantage that bactericidal water can be easily generated, but it is difficult to control the amount of the acidic aqueous solution to be mixed. If the amount of the acidic aqueous solution is even slightly large, the pH drops rapidly and enters the gasification region, generating problems such as chlorine gas and chlorine dioxide gas.

[0010] As a device for controlling the reaction with an acidic aqueous solution and stably producing bactericidal water containing hypochlorous acid or chlorous acid, there is a device that mixes an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution with carbon dioxide gas to generate bactericidal water (see Patent Document 1).

[0011] Patent Document 1 describes "a method and apparatus for producing sterilized water with a predetermined chlorine concentration by diluting an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution with tap water, well water, seawater, etc., having a branching step and mechanism for branching and supplying the tap water, well water, or seawater to at least two or more pipelines, and having a step and mechanism for adding an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution to the tap water, well water, or seawater upstream of the branching step and mechanism to produce sterilized water, or having a step and mechanism for mixing an aqueous solution obtained by diluting an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution with tap water, well water, seawater, etc. and an aqueous solution obtained by diluting an acidic aqueous solution such as hydrochloric acid, sulfuric acid, or acetic acid with tap water, well water, seawater, etc. to produce sterilized water, or having a step and mechanism for electrolyzing an aqueous sodium chloride solution or seawater in a diaphragm-free electrolytic cell or a diaphragm electrolytic cell to produce sterilized water, having a step and mechanism for supplying carbon dioxide gas to a pressure vessel at a predetermined pressure above atmospheric pressure, having a step and mechanism for injecting and / or spraying the sterilized water into the pressure vessel through each of the branched pipelines, further having a step and mechanism for simply delivering water, having a drainage step and mechanism for draining the sterilized water from the pressure vessel, and having a water level maintenance step and mechanism for storing the injected and / or sprayed and delivered sterilized water at a water level within a predetermined range at the bottom of the pressure vessel" (paragraph

[0013] ).

[0012] Also, when mixing an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution with carbon dioxide gas to produce sterilized water, it is also known to mix or stir with a static mixer (see Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Patent Document 2

Patent Document 3

Disclosure of the Invention

Problems to be Solved by the Invention

[0014] In the apparatus described in Patent Document 1, when an aqueous solution of sodium hypochlorite or an aqueous solution of sodium chlorite is injected into a pressure vessel filled with carbon dioxide gas, the injected droplets react with the carbon dioxide gas before landing on the liquid surface of the sterilizing water accumulated at the bottom of the pressure vessel, generating hypochlorous acid and chlorous acid. However, the above apparatus has a problem that the water level of the sterilizing water changes due to malfunction of the water level maintaining mechanism (float), the flight time of the sprayed sterilizing water in the carbon dioxide gas changes, and the pH of the sterilizing water cannot be stably produced.

[0015] Patent Document 2 describes a carbon dioxide-containing sterilizing water generating apparatus that mixes an aqueous solution of sodium hypochlorite or an aqueous solution of sodium chlorite with carbon dioxide gas and stirs it with a static mixer or the like (Claims 5 and 6). However, it is described that the structure of the stirrer is not limited (paragraph

[0031] ), and since carbon dioxide gas is mixed after mixing sodium hypochlorite (paragraph

[0030] ), the action and effect of stirring a mixture of the two in a different order with a static mixer are not clear.

[0016] Patent Document 3 describes that an apparatus for generating sterilizing water by mixing sodium hypochlorite or sodium chlorite (a sterilizing agent) with carbon dioxide gas has a mixing section such as a static mixer in the middle of a water supply pipe (Claims 2 and 6). However, it has a special structure for sucking up the sterilizing agent using negative pressure and mixing it with raw water, and it is described that the mixing section may not be provided (paragraph

[0034] ). There is no specific description about the static mixer, and the action and effect of using the static mixer are not clear.

[0017] In addition, the sterilizing water produced by the conventional apparatus as described above also has a problem that the pH starts to change to the neutral range from about one week, and the pH changes to a region where hypochlorous acid cannot exist stably.

[0018] The present invention aims to solve such conventional problems and provides an apparatus for producing bactericidal water containing hypochlorous acid or chlorous acid with a more stable pH.

Means for Solving the Problems

[0019] The present invention employs the following means to solve the above problems. (1) A bactericidal water production apparatus containing hypochlorous acid or chlorous acid, comprising a carbon dioxide gas injection pipe having a check valve, a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution injection pipe having a check valve, and a stirring tank having a static mixer with stirring blades inserted into a pipe, between a raw water inlet and a bactericidal water outlet, and having a pumping section for sending raw water upward. On the main pipe from the raw water inlet to the stirring tank inlet, the carbon dioxide gas injection pipe, the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection pipe are connected in this order with the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection pipe on the upper side, the main pipe is connected to the inlet of the stirring tank, and at the lower part of the pipe of the static mixer in the stirring tank, there is a hole serving as an inlet for raw water added with carbon dioxide gas and the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution. A discharge pipe for discharging bactericidal water containing hypochlorous acid or chlorous acid from the bactericidal water outlet is connected to the outlet of the pipe of the static mixer. A bactericidal water production apparatus. (2) The bactericidal water production apparatus according to (1), wherein the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution is transported by a tube pump. (3) The bactericidal water production apparatus according to (1) or (2), wherein the static mixer is made of resin. (4) A tee joint for injecting carbon dioxide gas is connected to the main pipe, and a tee joint for injecting an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution is connected immediately after the tee joint for injecting carbon dioxide gas. The tee joint for injecting carbon dioxide gas is connected to a pipe for injecting carbon dioxide gas, and the tee joint for injecting an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution is connected to a pipe for injecting an aqueous sodium hypochlorite solution or an aqueous sodium chlorite solution. The sterilized water production device according to any one of (1) to (3) above. (5) The particle Reynolds number of the water in the flow path from the connection position of the carbon dioxide gas injection pipe in the main pipe through the stirring tank to the sterilized water outlet with respect to carbon dioxide gas bubbles having a representative length (diameter) of 0.3 mm calculated by the following formula (1) is 500 or less. The sterilized water production device according to any one of (1) to (4) above. Particle Reynolds number = (flow rate * carbon dioxide gas bubble diameter) / (water kinematic viscosity * pipe cross-sectional area) ··· (1) (6) The flow rate of water in the flow path from the raw water inlet through the stirring tank to the sterilized water outlet is 500 L / h or less, and the diameters of the main pipe, the pipe of the static mixer, and the discharge pipe are 11 mm or more. One to eight holes with a diameter of 4 mm or more are provided in the pipe of the static mixer. The sterilized water production device according to any one of (1) to (5) above. (7) The static mixer in the stirring tank constitutes a hydrocyclone that separates the coarse bubbles and fine bubbles of carbon dioxide gas in the raw water to which the carbon dioxide gas and the aqueous sodium hypochlorite solution or the aqueous sodium chlorite solution are added. The sterilized water production device according to any one of (1) to (6) above. (8) The sterilized water production device according to any one of (1) to (7) above, having a member that separates the excess carbon dioxide gas that did not dissolve in the stirring tank from the sterilized water and discharges the excess carbon dioxide gas to the atmosphere. A method for producing bactericidal water containing hypochlorous acid or chlorous acid, which uses a bactericidal water production apparatus having a stirring tank with a carbon dioxide gas injection pipe, a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution injection pipe, and a static mixer with stirring blades inserted into the pipe between a raw water inlet and a bactericidal water outlet. The method has a water pumping section for sending raw water upward. Carbon dioxide gas is injected from the carbon dioxide gas injection pipe into the main pipe leading from the raw water inlet to the stirring tank inlet. Next, a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution is injected from the sodium hypochlorite aqueous solution or sodium chlorite aqueous solution injection pipe. Raw water added with carbon dioxide gas and a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution is supplied from the main pipe to the stirring tank. The raw water is allowed to flow in from an inlet (hole) provided at the lower part of the pipe of the static mixer in the stirring tank and is stirred by the static mixer to produce bactericidal water containing hypochlorous acid or chlorous acid. The bactericidal water containing hypochlorous acid or chlorous acid is discharged from the bactericidal water outlet of the discharge pipe connected to the outlet of the pipe of the static mixer. (10) The method for producing bactericidal water according to (9) above, wherein the particle Reynolds number with respect to carbon dioxide gas bubbles having a representative length (diameter) of 0.3 mm of water in the flow path from the connection position of the carbon dioxide gas injection pipe in the main pipe through the stirring tank to the bactericidal water outlet is 500 or less. Particle Reynolds number = (flow rate * carbon dioxide gas bubble diameter) / (water kinematic viscosity * pipe cross-sectional area) ··· (1) (11) The method for producing bactericidal water according to (9) or (10) above, wherein the flow rate of water in the flow path from the raw water inlet through the stirring tank to the bactericidal water outlet is 500 L / h or less, the diameters of the main pipe, the pipe of the static mixer, and the discharge pipe are 11 mm or more, and 1 to 8 holes with a diameter of 4 mm or more are provided in the pipe of the static mixer.

Advantages of the Invention

[0020] According to the present invention, bactericidal water containing hypochlorous acid or chlorine dioxide can be obtained from a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution by the stable pH adjustment action of carbon dioxide gas.

[0021] In addition, mixing carbon dioxide gas with an aqueous solution of sodium hypochlorite or an aqueous solution of sodium chlorite in raw water in a pipe and stirring with a static mixer in a stirring tank after mixing are effective in stabilizing the pH of the sterilized water produced.

[0022] The sterilized water produced by the apparatus of the present invention can maintain a pH of 5.6 to 5.8, at which hypochlorous acid can stably exist, for six months or more.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0024] An embodiment of the present invention for producing sterilized water containing hypochlorous acid or chlorous acid will be described below with reference to the drawings. FIG. 1 is a diagram showing the structure of a typical sterilized water production apparatus of the present invention. Raw water 14 such as tap water, well water, or seawater is supplied to the main pipe 9 from the raw water inlet 1. As a pre-step of supplying the raw water 14 to the raw water inlet 1, it is preferable to provide a pressure reducer (regulator) for making the pressure of the tap water (raw water) constant. The main pipe 9 from the raw water inlet 1 to the inlet of the stirring tank 7 has a water pumping section for sending the raw water 14 upward.

[0025] A tee joint 10 for injecting carbon dioxide gas is connected to the water pumping section of the main pipe 9, and carbon dioxide gas 16 that has passed through the carbon dioxide gas injection pipe 4 and the carbon dioxide gas injection check valve 3 is added to the raw water therefrom.

[0026] Immediately after the tee joint 10 for injecting carbon dioxide gas in the pumping section of the main pipe 9, a tee joint 11 for injecting an aqueous sodium hypochlorite solution (an aqueous sodium hypochlorite solution when producing a bactericidal water containing chlorous acid) is connected, and the aqueous sodium hypochlorite solution 17 transported by the tube pump 12 therefrom passes through the aqueous sodium hypochlorite solution injection pipe 6 and the check valve 5 for sodium hypochlorite injection and is added to the raw water.

[0027] The tee joint 11 for supplying the aqueous sodium hypochlorite solution is located above the tee joint 10 for injecting carbon dioxide gas. Thus, due to buoyancy, the carbon dioxide gas floats between the tee joint 10 and the tee joint 11 faster than the flow of tap water supplied from the raw water inlet 1, and dissolution is promoted. The raw water added with carbon dioxide gas and the aqueous sodium hypochlorite solution enters the stirring tank 7 through the main pipe 9.

[0028] The raw water that has entered the stirring tank 7 passes through the static mixer inlet 13, enters the static mixer 8, and is stirred. By stirring the raw water added with carbon dioxide gas and the aqueous sodium hypochlorite solution with the static mixer 8, a bactericidal water containing chlorous acid is produced. The static mixer 8 is one in which stirring blades having a structure in which twisted blades as shown in FIG. 2 are arranged in series at different angles are inserted into a pipe. The raw water passes through there along the path of the arrow in FIG. 2 to perform stirring. Since the static mixer is a part that directly contacts the raw water, it is necessary to use a material that is not prone to corrosion. In this embodiment, it is made of resin. Polyvinyl chloride, polyacetal, polypropylene, etc. can be used.

[0029] The stirring tank 7 is a hydrocyclone that separates the coarse bubbles and fine bubbles of the carbon dioxide gas bubbles in the raw water added with carbon dioxide gas and the aqueous sodium hypochlorite solution, and is effective in stabilizing the pH. Connect the main pipe 9 to the upper part of the stirring tank 7, provide a static mixer inlet (hole) 13 at the lower part, and in the process of moving the raw water containing carbon dioxide gas from the lower part to the upper part of the static mixer 8, hydrogen carbonate ions are efficiently generated by the fine bubbles of carbon dioxide gas separated to the upper part. As will be described later, by reducing the flow rate of the raw water in the main pipe 9, the residence time of the fine bubbles of carbon dioxide gas in the static mixer 8 also becomes longer. Since the static mixer 8 stirs without destroying the laminar flow structure in principle, it is considered that hydrogen carbonate ions are efficiently generated by the fine bubbles of carbon dioxide gas. Also, in order to increase the residence time, it is preferable to provide the static mixer inlet 13 as close to the bottom as possible.

[0030] The stirring tank 7 is essentially a continuous reactor and is a hybrid of a tubular reactor (static mixer 8) and a tank-type reactor. It is preferable to monitor the temperature and pressure for the quality stability of the sterilized water 15 to be produced. For this reason, it is preferable to provide a temperature sensor and a pressure sensor in the main pipe 9 and the stirring tank 7 which are flow paths. A microphone may be attached to the flow path and its impedance may be analyzed. Thereby, the generation state of the carbon dioxide gas fine bubbles can be monitored, and by analyzing the sound, the quality of the sterilized water can be determined, which is useful for the quality stability of the sterilized water.

[0031] A discharge pipe 18 is connected to the outlet of the pipe of the static mixer 8 in the stirring tank 7, and the sterilized water 15 containing hypochlorous acid is discharged from the sterilized water outlet 2 of the discharge pipe 18. It is preferable to have a member that separates the excess carbon dioxide gas that did not dissolve in the stirring tank 7 from the sterilized water 15 and releases the excess carbon dioxide gas to the atmosphere.

[0032] The flow rate of water in the flow path from the raw water inlet 1 through the stirring tank 7 to the sterilized water outlet 2 is 500 L / h or less, and the diameters of the main pipe 9 from the raw water inlet 1 to the inlet of the stirring tank 7, the pipe of the static mixer 8, and the discharge pipe 18 connected to the outlet of the static mixer 8 are 11 mm or more. By providing 1 to 8 holes with a diameter of 4 mm or more in the pipe of the static mixer 8, it is preferable to configure a laminar flow with a particle Reynolds number of 500 or less for carbon dioxide gas bubbles with a diameter of 0.3 mm as the representative length. Here, the flow path from the raw water inlet 1 through the stirring tank 7 to the sterilized water outlet 2 consists of the flow path of the main pipe 9 from the raw water inlet 1 to the inlet of the stirring tank 7, the flow path from the outlet of the main pipe 9 (inlet of the stirring tank 7) in the stirring tank 7 to the static mixer inlet 13, the flow path in the static mixer 8, and the flow path of the discharge pipe 18 from the outlet of the static mixer 8 to the sterilized water outlet 2.

[0033] The particle Reynolds number is calculated by (flow rate * carbon dioxide gas bubble diameter) / (water kinematic viscosity * pipe cross-sectional area). Since the carbon dioxide gas bubble diameter and the water kinematic viscosity are constant, the smaller the flow rate and / or the larger the pipe cross-sectional area, that is, the larger the pipe diameter, the smaller the particle Reynolds number. In the present invention, since the flow rate of water is small, even if the pipe diameter is reduced, a stable laminar flow with a small particle Reynolds number can be obtained. The flow rate of water (raw water and sterilized water) is preferably 500 L / h or less, and more preferably 300 L / h or less. The diameters of the main pipe 9 and the discharge pipe 18 are preferably 11 mm or more, and more preferably 13 mm or more. The upper limit of the diameters of the main pipe 9 and the discharge pipe 18 is preferably 20 mm, and more preferably 15 mm, in order to obtain a stable laminar flow with little change in the Reynolds number. Also, the diameter of the pipe of the static mixer 8 is preferably 15 mm or more, and more preferably 20 mm or more. The diameter of this pipe is preferably 65 mm or less, and more preferably 30 mm or less. On the outer periphery of the pipe of the static mixer 8, it is preferable to provide 1 to 8 holes with a diameter of 4 mm or more, and more preferably 2 to 4 holes with a diameter of 6 mm or more. The upper limit of the diameter of this hole is preferably 20 mm, and more preferably 15 mm. The particle Reynolds number becomes laminar flow at 500 or less, but is more preferably 300 or less, and even more preferably 250 or less. By setting the particle Reynolds number as described above, the residence time of carbon dioxide gas bubbles in the flow path can be lengthened, and the contact time between the raw water mixed with sodium hypochlorite and carbon dioxide gas can be lengthened, so that hydrogen carbonate ions having a pH buffering action can be efficiently generated.

[0034] Table 1 shows the results of calculating the particle Reynolds number for carbon dioxide gas bubbles with a diameter of 0.3 mm as the representative length.

[0035]

Table 1

[0036] As described above, when the water flow rate is 300 L / h and the pipe diameter is 13 mm, the particle Reynolds number for carbon dioxide gas bubbles with a diameter of 0.3 mm is 211. When the water flow rate is 500 L / h and the pipe diameter is 11 mm, the particle Reynolds number is 491, which is 500 or less. Therefore, the diameters of the main pipe and the discharge pipe are preferably 11 mm or more. Since the diameter of the pipe (equivalent to piping) of the static mixer is usually about 20 mm, the particle Reynolds number of the raw water (sterilized water) in the static mixer is smaller than that of the raw water flowing through the main pipe. Also, when four holes with a diameter of 10 mm (the diameter of the hole is equivalent to the diameter of the pipe) are provided on the outer periphery of the pipe of the static mixer, the true pipe cross-sectional area through which the raw water flows in the stirring tank becomes four times. Therefore, if this pipe cross-sectional area is used, when the water flow rate is 500 L / h, the particle Reynolds number becomes 149. Even if the holes have a diameter of 6 mm and four are provided, the particle Reynolds number in the stirring tank will be 500 or less. Therefore, the particle Reynolds number in the flow path from the connection position of the carbon dioxide gas injection pipe in the main pipe through the stirring tank to the sterilized water outlet is 500 or less.

[0037] The raw water to which carbon dioxide gas and an aqueous sodium hypochlorite solution are added and stirred by the static mixer 8 has an increased ratio of hypochlorous acid and a decreased pH value, becoming sterilized water with a pH of from 5.6 to 5.8. The manufactured sterilized water can maintain a pH of from 5.6 to 5.8, at which hypochlorous acid can stably exist, for six months or more.

[0038] The relationship between the pH and the oxidation-reduction potential (ORP) of the sterilized water produced in this embodiment is shown in FIG. 3. From FIG. 3, in the region higher than pH 7, what exists is Cl2(g) + 2e indicated by 102 - = 2Cl - (chloride ion vs. chlorine gas), ClO indicated by 103 - + H2O + 2e - = Cl - + 2OH - (hypochlorite ion vs. chloride ion), ClO2 indicated by 104 - + H2O + 2e - = ClO - + 2OH - (chlorate ion vs. hypochlorite ion) and such equilibrium reactions, and it can be seen that hypochlorous acid does not exist. In the region of the pH of the sterilized water, from pH 5.6 to pH 5.8, HClO + H indicated by 101 + + e- = 1 / 2Cl2(g) + H2O (hypochlorous acid vs chlorine gas), HClO + H shown as 100 + + 2e- = Cl - There is an equilibrium reaction of + H2O (hypochlorous acid vs chloride ion), and it can be seen that hypochlorous acid molecules exist.

Explanation of Symbols

[0039] 1 Raw water inlet, 2 Sterilized water outlet, 3 Check valve for carbon dioxide injection, 4 Pipe for carbon dioxide injection, 5 Check valve for sodium hypochlorite aqueous solution injection, 6 Pipe for sodium hypochlorite aqueous solution injection, 7 Stirring tank, 8 Static mixer, 9 Main pipe, 10 Tee joint for carbon dioxide injection, 11 Tee joint for sodium hypochlorite aqueous solution injection, 12 Tube pump, 13 Static mixer inlet, 14 Raw water, 15 Sterilized water, 16 Carbon dioxide, 17 Sodium hypochlorite aqueous solution, 18 Discharge pipe, 100 Hypochlorous acid vs chloride ion, 101 Hypochlorous acid vs chlorine gas, 102 Chloride ion vs chlorine gas, 103 Hypochlorite ion vs chloride ion, 104 Chlorate ion vs hypochlorite ion, 400 Presence ratio of carbonic acid, 401 Presence ratio of hydrogen carbonate ion, 402 Presence ratio of carbonate ion, 500 Presence ratio of chlorine molecule, 501 Presence ratio of hypochlorous acid, 502 Presence ratio of hypochlorite ion

Claims

1. A sterilizing water production apparatus containing hypochlorous acid or chlorous acid, comprising a carbon dioxide gas injection pipe having a check valve, a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution injection pipe having a check valve, and a stirring tank having a static mixer with stirring blades inserted into a pipe, between a raw water inlet and a sterilizing water outlet, having a water pumping section for sending raw water upward, and on a main pipe leading from the raw water inlet to the stirring tank inlet, in the order of the carbon dioxide gas injection pipe, the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection pipe, with the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection pipe on the upper side, the main pipe being connected to the inlet of the stirring tank, and at the lower part of the pipe of the static mixer in the stirring tank, there is a hole serving as an inlet for raw water added with carbon dioxide gas and a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution, and at the outlet of the pipe of the static mixer, a discharge pipe for discharging sterilizing water containing hypochlorous acid or chlorous acid from the sterilizing water outlet is connected, and the static mixer in the stirring tank constitutes a hydrocyclone for separating carbon dioxide gas bubbles in the raw water added with carbon dioxide gas and a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution into coarse bubbles and fine bubbles. A sterilizing water production apparatus.

2. The sterilizing water production apparatus according to claim 1, wherein the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution is transported by a tube pump.

3. The sterilizing water production apparatus according to claim 1 or 2, wherein the static mixer is made of resin.

4. A carbon dioxide gas injection tee joint is connected to the main pipe, and a sodium hypochlorite aqueous solution or a sodium chlorite aqueous solution injection tee joint is connected immediately after the carbon dioxide gas injection tee joint. The carbon dioxide gas injection tee joint is connected to the carbon dioxide gas injection pipe, and the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection tee joint is connected to the sodium hypochlorite aqueous solution or the sodium chlorite aqueous solution injection pipe. The sterilizing water production apparatus according to any one of claims 1 to 3.

5. The particle Reynolds number with respect to carbon dioxide gas bubbles having a representative length (diameter) of 0.3 mm of the water in the flow path from the connection position of the carbon dioxide gas injection pipe in the main pipe through the stirring tank to the sterilizing water outlet is 500 or less. The sterilizing water production apparatus according to any one of claims 1 to 4. Particle Reynolds number = (flow rate * carbon dioxide bubble diameter) / (kinematic viscosity of water * pipe cross-sectional area) ... (1)

6. The flow rate of water in the flow path from the raw water inlet through the stirring tank to the sterilized water outlet is 500 L / h or less, and the diameters of the main pipe, the pipe of the static mixer, and the discharge pipe are 11 mm or more, and 1 to 8 holes with a diameter of 4 mm or more are provided in the pipe of the static mixer. The sterilized water production apparatus according to any one of claims 1 to 5.

7. The sterilized water production apparatus according to any one of claims 1 to 6, further comprising a member that separates surplus carbon dioxide gas that has not dissolved in the stirring tank from the sterilized water and discharges the surplus carbon dioxide gas to the atmosphere.

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