JP6524759B2 - Method and apparatus for dosing an open circulation cooling water system - Google Patents

Description

  The present invention relates to a method and apparatus for adding calcium hypochlorite as an antibacterial and bactericidal agent for preventing slime damage in an open circulation cooling water system, and more particularly to a calcium hypochlorite added site. The present invention relates to an injection method and an injection apparatus for an open-type circulating cooling water system that prevents calcium scale. The invention also relates to an open circulating cooling water installation comprising this dosing device.

  Waste heat generated by a compressor of a factory, a building or the like or a refrigerator is cooled by a cooling water (cooling medium) via a heat exchanger. In the heat exchanger, the cooling water whose temperature has risen by heat exchange with waste heat is evaporated in contact with the air in the open cooling tower to evaporate, dissipate heat, be cooled, and circulated again to the heat exchanger. Therefore, in such an open-type circulating cooling water system, the operation is performed by supplying makeup water corresponding to the amount of water that has been evaporated or scattered in the cooling tower and reduced, but the makeup water components include organic components and phosphorus. When nutrients are contained, or depending on the external environment, nutrient components may be mixed into the cooling tower. The water temperature of the cooling water is around 30 ° C, which is an environment where slime and mold grow easily, and if slime treatment is not performed, heat exchange efficiency decreases due to slime adhesion to heat exchangers and pipes, flow resistance increases, or microorganisms It will cause various operation problems such as corrosion.

  Therefore, in order to prevent slime damage in the open circulation cooling water system, an antibacterial and bactericidal agent such as hypochlorite is added, and calcium hypochlorite used for such applications is used. A tablet is also marketed (for example, Kurita Kogyo Co., Ltd. product "kritite CW-300").

  As a dissolution apparatus for dissolving a tablet type water treatment drug in water, according to Japanese Utility Model Registration No. 3173540, a solid drug is filled in a cylindrical container having a water flow hole, and this is placed in a water flow channel It has been proposed that a solid drug is brought into contact with water flowing through the water flow hole to elute the drug. Although this publication describes the application to a cooling tower, there is no recognition about the problem of calcium scale when dissolving calcium hypochlorite solid drug.

  JP-A-2010-162476 discloses hypochlorite having a pH of 5 to 6 which is used for sterilization of medical instruments, sterilization of linen, sterilization of cooking utensils, sterilization of foods such as vegetables, meat, fish and shellfish, etc. in hospitals and kitchens. As a continuous automatic generator of sodium acid solution, one having an acid inlet in a feed pipe and a sodium hypochlorite inlet downstream thereof is described. The acid is added here to adjust the sodium hypochlorite solution to around pH 5 to obtain a high bactericidal effect.

Utility model registration No. 3173540 JP, 2010-162476, A

In the case of performing water treatment using calcium hypochlorite tablets in an open circulation cooling water system, for example, calcium hypochlorite tablet is used in a solid drug dissolving apparatus as described in Utility Model Registration No. 3173540. It is possible to fill the water, distribute the water extracted from the circulating cooling water system, and return the water from which calcium hypochlorite has been eluted back to the circulating cooling water system, according to the study of the present inventors. As a result, calcium-based scales are generated in the piping where the calcium hypochlorite elution portion and the water in which calcium hypochlorite is eluted are returned to the circulating cooling water system, and the water-flowing holes of the tablet filling container are generated. Because the water is blocked, stable water flow and elution of calcium hypochlorite can not be performed, and the passage of water is blocked with time, Joteki a chemical feeding, chemical dosing may not be able to be carried out water treatment by was found.
That is, in the open circulation cooling water system, in order to prevent corrosion in the system, an operation is performed to maintain the pH of the circulating cooling water at 6 to 10, but a neutral to alkaline pH 6 to 10 When calcium hypochlorite is eluted in water, the calcium component precipitates and scales.

  The present invention relates to hypochlorous acid after maintaining the corrosion resistance environment of a circulating cooling water system in water treatment to which calcium hypochlorite is added as an antibacterial and bactericidal agent for preventing slime damage in an open circulating cooling water system. It is an object of the present invention to provide an injection method and injection apparatus for an open circulation cooling water system that prevents calcium scale at a calcium addition site, and an open circulation cooling water facility equipped with the injection apparatus.

  As a result of intensive investigations to solve the above problems, the present inventors added acid to the water extracted from the circulating cooling water system on the upstream side of the site to which calcium hypochlorite is added to lower the pH. There is a concern that calcium-based scale can be prevented, and if water to which acid has been added in this way is returned to the circulating cooling water system, the pH of the circulating cooling water system may be lowered and the corrosiveness may be increased. It has been found that the corrosion resistance environment in the circulating cooling water system can be maintained by adjusting the amount of water such that the pH of the circulating cooling water system can be maintained at 6 to 10.

  The present invention has been achieved based on such findings, and the gist of the present invention is as follows.

[1] In the pharmaceutical injection method of injecting calcium hypochlorite into an open circulation cooling water system, part of circulating cooling water is extracted from the circulation cooling water system, and the extracted water (hereinafter referred to as “extracted water”) After the addition of the acid, calcium hypochlorite is added, and the water to which the calcium hypochlorite is added is returned to the circulating cooling water system, wherein the pH of the circulating cooling water system is An acid is added to the extracted water so as to maintain 6 to 10, and the amount of extracted water is adjusted so that the pH of the water to which the calcium hypochlorite is added is 5 or less. Method of chemical injection in an open circulation cooling water system characterized by

[2] The method according to [1], wherein the acid is an inorganic acid.

[3] The method according to [2], wherein the inorganic acid is at least one selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid.

[4] The method according to any one of [1] to [3], wherein nicotinamide is added to the extracted water.

[5] In [1], by bringing the extracted water to which the acid is added into contact with a calcium hypochlorite-containing solid agent, calcium hypochlorite is eluted from the solid agent into the water. And calcium hypochlorite is added to the water.

[6] [5], wherein the solid agent is a tablet, and the method of injecting an open-type circulating cooling water system.

[7] In any one of [1] to [6], the extraction amount of the extracted water is adjusted so that the pH of the water to which the calcium hypochlorite is added is 3 or less. Injection method of open circulation cooling water system.

[8] In a chemical feeder for injecting calcium hypochlorite into an open circulation cooling water system, an extraction means for extracting a portion of circulating cooling water from the circulation cooling water system, and water extracted by the extraction means An acid addition means for adding an acid to (hereinafter referred to as “extracted water”), a calcium hypochlorite addition means for adding calcium hypochlorite to extracted water to which the acid is added, and the hypochlorite And a return means for returning the water to which the calcium acid has been added to the circulating cooling water system, wherein the acid adding means adds an acid to the withdrawn water so that the pH of the circulating cooling water system is maintained at 6-10. The extracting means is a means for extracting a portion of the circulating cooling water from the circulating cooling water system so that the pH of the water to which the calcium hypochlorite is added is 5 or less. An open circulation water cooling system with a chemical feeder.

[9] In [8], the extraction means is an extraction pipe for extracting a part of circulating cooling water from the open circulation cooling water system, and the acid addition means injects an acid into the extraction pipe It is an acid injection piping, The said calcium hypochlorite addition means is filled with the water-permeable container installed in the said water tank, the water-permeable container installed in the said water tank, and the said water container to which the said acid was added. And a solid agent containing calcium hypochlorite, wherein calcium hypochlorite is eluted from the solid agent by contacting the solid agent with the extracted water to which the acid is added. And the return means is a return pipe for returning the water in the water tank to the open circulation cooling water system.

[10] In [7] or [8], the chemical injection device for an open-type circulating cooling water system, further comprising nicotinamide addition means for adding nicotinamide to the extracted water.

[11] An open circulation cooling water system comprising the injection apparatus of the open circulation cooling water system according to any one of [7] to [10].

  According to the present invention, in the water treatment to which calcium hypochlorite is added as an antibacterial and bactericidal agent for preventing slime damage in the open circulation cooling water system, the corrosion resistance environment of the circulation cooling water system is maintained, Calcium scale at the calcium chlorate addition site can be prevented.

It is a systematic diagram showing an open type circulating cooling water installation provided with a chemical feeder of an open type circulating cooling water system concerning an embodiment of the invention. It is a schematic cross section which shows the principal part of FIG. It is a graph which shows the result of example 1 of an experiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a system diagram showing an open circulation cooling water facility equipped with an injection system of an open circulation cooling water system according to an embodiment.
A cooling tower 1 is provided with a casing (a tower body) 1A, an air inlet 1B is formed on the side of the casing 1A, and a water tank (pit) 1C for cooling water is provided at the bottom. A filler 1D is accommodated in the casing 1A, and a water spray nozzle 1E for cooling water is disposed above the filler 1D. An opening 1F is provided at the top of the casing 1A, and a blower 1G is provided in the opening 1F.
From the cooling tower 1 of the tank 1C, the cooling water by the circulation pipe 2 having a pump P ₁ is fed to heat exchanger 3, the return water is returned to the cooling tower 1 via piping 4, the filling material 1D from water spray nozzle 1E Watering is done. 5 is a supply water introduction pipe, 6 is a blow pipe.

The filler 1 D of the cooling tower 1 is provided with an extraction pipe 11 for extracting the circulating cooling water, and a part of the circulating cooling water is extracted by the extraction pipe 11. An acid is added from the pipe 12 to the extracted water extracted from the extracting pipe 11, and then calcium hypochlorite is added by the calcium hypochlorite addition means 10, and the water tank of the cooling tower 1 from the return pipe 13 (Pit) It is returned to 1C.
In addition, the extraction part of circulating cooling water is not limited to filler 1D at all, You may extract from circulation piping 2 or water tank (pit) 1C. Moreover, the return location of water after calcium hypochlorite addition is not limited to the water tank (pit) 1C at all.

In the present embodiment, as shown in FIG. 2, the calcium hypochlorite addition means 10 includes a water tank 7 into which extracted water from the extraction pipe 11 is introduced, and a container 8 provided in the water tank 7. Mainly composed of In the container 8, tablets 9 of calcium hypochlorite are filled. The container 8 is cylindrical, and water flow holes 8a are provided at a plurality of locations on the wall surface.
In the present embodiment, four containers 8 are provided in the water tank 7, but in FIG. 2, only two containers 8 are illustrated in a simplified manner. However, the number of containers is not limited to four.
When the extracted water introduced into the water tank 7 flows from the water passage hole 8a of the container 8 into the container 8 and comes into contact with the calcium hypochlorite tablet 9, the calcium hypochlorite tablet 9 is Calcium chlorate elutes. The calcium hypochlorite solution containing the eluted calcium hypochlorite is returned from the water tank 7 to the water tank (pit) 1 C through the return pipe 13.

In the present invention, the acid is added to the withdrawn water so as to maintain the pH of the circulating cooling water system at 6 to 10, preferably 7 to 9. If the pH of the circulating cooling water system is less than 6, corrosion in the system becomes a problem, and if it exceeds 10, there is a problem of scale precipitation.
The pH of the circulating cooling water system may be affected by returning the returned water, which has been lowered in pH by adding an acid, from the piping 13 to the water tank (pit) 1C, and the pH may decrease. If the acid is added to the extracted water so as to maintain 6 to 10, preferably 7 to 9, this problem does not occur.
The acid may be added continuously or intermittently to the water if it can be maintained at the above pH.

  In the present invention, the pH of the extracted water after the addition of calcium hypochlorite, that is, the pH of the water discharged from the calcium hypochlorite addition means 10 and returned to the water tank (pit) 1C in FIGS. The amount of extracted water extracted through the extraction pipe 11 is adjusted so as to be 5 or less. When this pH value is higher than 5, the precipitation preventing effect of the calcium-based scale by the addition of the acid can not be sufficiently obtained. From the viewpoint of the precipitation prevention effect of the calcium-based scale, it is preferable that the pH value is as low as possible, and it is preferable to adjust the amount of extracted water extracted through the extraction pipe 11 so that the pH value is 3 or less .

Make the pH of water after addition of calcium hypochlorite added to be 5 or less, preferably 3 or less, returned to the circulating cooling water system with the amount of acid added to maintain the pH of the circulating cooling water system at 6 to 10 Although the amount of water withdrawn for the purpose varies depending on the pH of the return water from the return pipe 13 and the amount of circulating water in the circulating cooling water system, the amount of withdrawn water is 1/100 or less of the circulating water amount in the circulating cooling water system, eg 1/500 By setting the pH to 1/10000, it becomes possible to stably maintain the pH of the circulating cooling water system at 6 to 10, even if the returned water having a pH of 5 or less, preferably pH 1 to 3 is returned.
Here, the amount of circulating water is the amount of water circulating in the open circulating cooling water system, which is obtained by subtracting the amount of water stored in the water tank (pit) 1C out of the total holding water of the open circulating cooling water system. Applicable

  As an acid to be added to extracted water, an inorganic acid is preferably used, and for example, sulfuric acid, hydrochloric acid, nitric acid and the like can be used. These acids may be used alone or in combination of two or more. These inorganic acids are usually injected as an aqueous solution of about 1 to 50% by weight.

  Although tablet-type calcium hypochlorite is used in FIG. 2, if it is a solid agent containing calcium hypochlorite, it can apply to the calcium hypochlorite addition means 10 of FIG. The solid agent may contain another water treatment agent other than calcium hypochlorite, and a filler for adjusting the elution amount of calcium hypochlorite. The shape of the solid agent is not limited to a disc shape, other tablet shapes, and may be other different shapes.

The amount of calcium hypochlorite added to the extracted water, that is, the amount of calcium hypochlorite eluted from the tablet 9 of calcium hypochlorite in FIG. 2 is calcium hypochlorite in the circulating cooling water system. So long as the antibacterial and bactericidal effects can be obtained.
In order to obtain sufficient antibacterial and bactericidal effects by calcium hypochlorite in circulating cooling water system, calcium hypochlorite concentration in circulating cooling water system is usually 1 to 10 mg Cl ₂ / L, preferably 0 in total residual chlorine concentration. 0.2 to 1.0 mg Cl ₂ / L or so. Here, “mg Cl ₂ / L” is a residual chlorine concentration in water which is shown by converting calcium hypochlorite into chlorine. Therefore, the calcium hypochlorite concentration of the return water from the return pipe 13 is adjusted according to the amount of extracted water and the total amount of retained water of the open circulation cooling water system so that the total residual chlorine concentration is obtained in the circulation cooling water system. It is preferable to set and adjust the amount of calcium hypochlorite elution in the calcium hypochlorite addition means 10 to be such a concentration. The amount of calcium hypochlorite elution changes the flow rate of extracted water, the hole diameter and number of water passage holes 8a of container 8, the form of arrangement, the filling amount of calcium hypochlorite 9 in container 8, etc. It can be adjusted by

  In the present invention, the calcium hypochlorite addition means 10 is not limited to what is shown in FIG. 2 as long as it can add calcium hypochlorite to extracted water. For example, a high concentration calcium hypochlorite slurry may be added to extracted water after acid addition, and calcium hypochlorite powder is dispersed in a water tank into which extracted water after acid addition flows. May be Also in this case, the calcium-based scale preventing effect by the addition of acid can be effectively obtained.

By the way, in an aqueous system where water treatment with a chlorine-based oxidizing agent such as calcium hypochlorite is carried out, the corrosion reaction is promoted as a result of the presence of strongly oxidizing residual chlorine in the system, a copper-based member It is known that the corrosion tendency of the
Since nicotinamide, which is a food additive material, is effective for reducing corrosion of such aqueous copper-based members, nicotinic acid amide is further added to the extracted water to suppress corrosion of the copper-based members in the circulating cooling water system. Can also be

  In this case, nicotinic acid amide may be added to the extracted water separately from the acid, but it is preferable to inject from the acid injection pipe 12 a mixture previously mixed with the above-mentioned acid.

  Thus, nicotinamide added to the aqueous system reacts with the free chlorine derived from calcium hypochlorite in water to convert the free chlorine into bound chlorine. Since the combined chlorine has no problem of corrosion to the copper-based member, the corrosion of the copper-based member due to calcium hypochlorite can be reduced.

  As an addition amount of nicotinic acid amide, it is preferable to add so that the active ingredient concentration of nicotinic acid amide in the circulating cooling water system to which calcium hypochlorite is added at the above-mentioned concentration is 0.1 to 20 mg / L. .

If the addition amount of nicotinic acid amide is too small, the corrosion reduction effect of the copper-based member due to the addition of nicotinic acid amide can not be sufficiently obtained, while nicotinic acid amide is added more than the above upper limit value. Also, the effect corresponding to the addition amount can not be obtained, and the amount of the drug used is too large for practical use.
The nicotinic acid amide may also be added continuously or intermittently.

  In the present invention, in addition to acids and nicotinic acid amide, scale inhibitors, antibacterial and bactericidal agents other than calcium hypochlorite, anticorrosive agents, dispersants, release agents, antifoaming agents, surfactants, chelating agents, etc. Other water treatment agents may be added to the withdrawal water.

The calcium hardness of the open circulation cooling water system to be treated with water in the present invention is usually 30 to 500 mg CaCO ₃ / L, and the acid consumption (pH 4.8) is usually 30 to 500 mg CaCO ₃ / L.

  The present invention will be more specifically described by way of experimental examples and examples.

[Experimental Example 1]
Dissolution test of calcium scale was conducted according to the following procedure.
(1) Put 100 L of tap water into a 100 L tank.
(2) The pH of the water in the tank was adjusted to 8.4, and the water temperature was set to 25 to 30 ° C.
(3) In place of calcium hypochlorite 9 was added 0.5 g of the calcium-based scale in the container 8 of the water tank 7 of the calcium hypochlorite addition means 10 shown in FIG.
(4) The pH adjusted water of (2) was passed through the water tank 7 of the calcium hypochlorite addition means 10 at 60 L / hour. At this time, on the inlet side of the water tank 7, sulfuric acid was added while changing the addition amount so that the pH of the outlet water of the water tank 7 becomes each pH value.
(5) The pH and calcium hardness of the outlet water of the water tank 7 were measured.
The relationship between the pH of the outlet water of the water tank 7 and the calcium hardness is shown in Table 1 and FIG.
Here, the calcium hardness difference is calculated by the following equation, and corresponds to the amount of dissolution of the calcium-based scale.
Calcium hardness difference = calcium hardness at outlet water pH value
-Calcium hardness when the outlet water pH is 8.4
= Calcium-based scale dissolution amount (mg CaCO ₃ / L)

  From Table 1, the calcium-based scale starts to dissolve when the pH of the outlet water is about 5, and the dissolution amount increases when the pH is 3 or less. Therefore, according to the present invention, an acid is added to the extracted water to have a pH of 5 or less, preferably It can be seen that, by lowering calcium to 3 or less, addition of calcium hypochlorite can prevent the precipitation of a calcium-based scale.

[Experimental Example 2]
The corrosion test was performed in the following procedure using a rotary corrosion test apparatus that corrodes the test piece by immersing and rotating the test piece in the test water.

(1) 1.0 L of tap water dechlorinated water was placed in a 1 L beaker.
(2) In a beaker of (1), 2.5 mL of sodium chloride aqueous solution (chloride ion concentration 10 wt%), 2.5 mL of sodium sulfate aqueous solution (sulfate ion concentration 10 wt%), and 0.1 wt% nicotinic acid amide After adding 1.5 mL of the aqueous solution, sodium hydroxide was added to adjust to pH 8.0. The calcium hardness of this test water is 40 to 60 mg CaCO ₃ / L and the acid consumption (pH 4.8) is 40 to 60 mg CaCO ₃ / L. The chloride ion concentration is 250 mg / L, the sulfate ion concentration is 250 mg / L, the total residual chlorine concentration is 0.5 mg Cl ₂ / L, and the nicotinamide concentration is 3.0 mg / L.
(3) The beaker of (2) was placed in a 40 ° C. test water tank.
(4) A copper test piece (50 mm × 30 mm × 1 mm) was attached to the support bar and set in the apparatus so as to be immersed in the test water in the beaker of (3). The copper test pieces were degreased with toluene and weighed beforehand.
(5) The test was started by rotating the support bar of (4) at a rotational speed of 145 rpm.
After the test for 3 days, the copper test piece was taken out, dried and weighed, and the corrosion rate (mg / dm ² / day) was calculated from the corrosion loss.
(6) The corrosion rate (mg / dm ² / day) is determined by conducting the corrosion test in the same manner as in the above (1) to (5) except that the aqueous nicotinic acid solution is not added to the test water. This value is 100%.
(7) When the ratio of the corrosion rate calculated | required by said (5) with respect to the corrosion rate calculated | required by said (6) was calculated | required by percentage, it was 47.5%.
From this result, it is possible to reduce the corrosion rate of the copper-based member to 1/2 or less by adding nicotinic acid amide, and for reducing the corrosion of the aqueous copper-based member in which nicotinic acid amide contains a chlorine-based oxidizing agent. It was confirmed to be effective.

Example 1
In the apparatus shown in FIGS. 1 and 2, the water treatment of the open circulation cooling water system was performed according to the present invention.
The amount of circulating water of this open-type circulating cooling water facility is 250 m ³ / hr. After extracting a part of circulating water as extraction water and adding sulfuric acid, calcium hypochlorite addition means 10 using calcium hypochlorite tablets ("Kritite CW-300" manufactured by Kurita Kogyo Co., Ltd.) Water flowed back to the water tank (pit). The flow rate of the extracted water was 1.0 to 1.5 L / min.

At this time, sulfuric acid is added to the withdrawn water so that the pH of the circulating cooling water system is maintained in the range of 6 to 10, and the pH of the outlet water of calcium hypochlorite addition means 10 is 1 to 3 In addition, 1/2500 of the amount of circulating water was extracted as extraction water.
As a result, the pH of the circulating cooling water system is maintained in the range of 6 to 10, and the circulating cooling water system contains about 0.5 mg Cl ₂ / L of calcium hypochlorite as a total residual chlorine concentration, and The slime could be prevented without causing corrosion problems and without causing scale failure.
In addition, precipitation of calcium scale on the calcium hypochlorite addition means 10 and the return pipe 13 is also prevented.

Reference Signs List 1 cooling tower 3 heat exchanger 7 water tank 8 container 9 calcium hypochlorite tablet 10 calcium hypochlorite addition means

Claims (11)

In the method of injecting calcium hypochlorite into open circulation cooling water system,
After a part of circulating cooling water is extracted from the circulating cooling water system and an acid is added to the extracted water (hereinafter referred to as "extracted water"), calcium hypochlorite is added, and the hypochlorous acid is added. It is a medicine injection method for returning the water to which the calcium acid is added to the circulating cooling water system,
An acid is added to the extracted water such that the pH of the circulating cooling water system is maintained at 6 to 10, and the pH of the water to which the calcium hypochlorite is added is 5 or less. A method of feeding an open-type circulating cooling water system characterized by adjusting the amount of withdrawal of water.   The method according to claim 1, wherein the acid is an inorganic acid.   The method according to claim 2, wherein the inorganic acid is one or more selected from the group consisting of sulfuric acid, hydrochloric acid and nitric acid.   The method according to any one of claims 1 to 3, wherein nicotinamide is added to the extracted water.   The water according to claim 1, wherein the extracted water to which the acid is added is brought into contact with a solid agent containing calcium hypochlorite to elute calcium hypochlorite from the solid agent into the water. Calcium hypochlorite is added to the above, and the injection method of the open circulation cooling water system characterized by the above-mentioned.   The method according to claim 5, wherein the solid agent is a tablet.   The open type circulation according to any one of claims 1 to 6, wherein the amount of the extracted water is adjusted so that the pH of the water to which the calcium hypochlorite is added is 3 or less. Injection method of cooling water system. In a chemical feeder for injecting calcium hypochlorite into an open circulation cooling water system,
Extracting means for extracting a part of the circulating cooling water from the circulating cooling water system;
Acid addition means for adding an acid to the water extracted by the extraction means (hereinafter referred to as "extracted water");
Calcium hypochlorite addition means for adding calcium hypochlorite to extracted water to which the acid is added;
Return means for returning the water to which the calcium hypochlorite is added to the circulating cooling water system;
The acid addition means is a means for adding an acid to the extracted water such that the pH of the circulating cooling water system is maintained at 6 to 10,
The release means is a means for extracting a part of circulating cooling water from the circulating cooling water system so that the pH of water to which the calcium hypochlorite is added is 5 or less. Chemical feeder for circulating cooling water system. In Claim 8, the extraction means is an extraction pipe for extracting a portion of circulating cooling water from the open type circulating cooling water system,
The acid addition means is an acid injection pipe for injecting an acid into the extraction pipe,
The calcium hypochlorite addition means includes a water tank into which the extracted water to which the acid is added flows, a water-permeable container disposed in the water tank, and hypochlorous acid filled in the container. A calcium-containing solid agent is provided, and calcium hypochlorite is eluted from the solid agent into the water by bringing the solid agent into contact with extracted water to which the acid is added.
The apparatus according to the open circulation cooling water system, wherein the return means is a return pipe for returning water in the water tank to the open circulation cooling water system. The apparatus according to claim 8 or 9 , further comprising nicotinamide addition means for adding nicotinamide to the extracted water. The open circulation cooling water installation provided with the pouring apparatus of the open circulation cooling water system according to any one of claims 8 to 10.

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