JP6843329B2 - How to prevent adhesion damage of marine organisms in seawater cooling water system - Google Patents

Description

The present invention relates to a method for preventing attachment disorders of marine organisms in a seawater cooling water system. More specifically, the present invention is a method for preventing adhesion disorders of marine organisms in a seawater cooling water system, which can maintain its effect for a long period of time by adding a low concentration of chemicals and can prevent attachment disorders of a wide range of marine organisms and slime. Regarding.

Seawater is used in large quantities as industrial cooling water, especially as cooling water for condensers of thermal power plants and nuclear power plants. Therefore, a large amount of mussels such as mussels and marine species such as barnacles, mussels, and hydroins adhere to the walls of seawater intake channels, pipes, and heat exchangers, causing various obstacles. Wake up. Among these, bivalves such as mussels that grow on byssus grow fast, and when they become adults, they block part of the heat exchanger tube, obstructing the passage of seawater and causing turbulence. Causes obstacles such as erosion corrosion.

In order to prevent the dense formation (adhesion) of these marine species, conventional chlorine generators such as sodium hypochlorite, electrolytic chlorine or chlorine gas (also called "chlorine agents"), hydrogen peroxide or excess A hydrogen peroxide generator (also referred to as a "hydrogen peroxide agent") has been added.
On the other hand, chlorine dioxide has a strong bactericidal activity and does not form harmful organic chlorine compounds such as trihalomethane, so that it has an advantage of having a small impact on the environment.
For example, Japanese Patent Application Laid-Open No. 1-275504 (Patent Document 1) relates to an aqueous solution-adhering biological control agent containing chlorine dioxide or a chlorine dioxide generator as an active ingredient, which contains at least 0.015 ppm or more, preferably 1 ppm or more of chlorine dioxide. According to Japanese Patent Application Laid-Open No. 6-153759 (Patent Document 2), a relatively low concentration of 0.1 to 2.0 ppm is found in a channel for passing fresh water or seawater installed in a facility using fresh water or seawater. A technique relating to a method for preventing or controlling the adhesion of organisms adhering to a water channel, which comprises continuously or intermittently injecting a relatively high concentration chlorine dioxide aqueous solution of 10.0 to 30.0 ppm, is disclosed. There is.
In addition, the applicant of this application has proposed a method for preventing the adhesion of marine organisms in which chlorine dioxide and hydrogen peroxide are used in combination and an anti-adhesion agent used therein (see Patent No. 5879596: Patent Document 3).

Japanese Unexamined Patent Publication No. 1-2755004 Japanese Unexamined Patent Publication No. 6-153759 Japanese Patent No. 5879596

However, chlorine dioxide is extremely unstable as a chemical substance, and even if it is used in a target system, there is a problem in sustainability of the effect of preventing adhesion disorders of marine organisms, and its storage and transportation are extremely difficult. For example, as described in Patent Document 2, chlorine dioxide can be produced on-site using a chlorine dioxide producing apparatus, but there is a new problem that the unit price of the drug becomes expensive.
Therefore, it is required to effectively prevent adhesion disorders of a wide range of marine sessile organisms by using chlorine dioxide and further reduce the running cost thereof.

The present invention provides a method for preventing adhesion disorders of marine organisms in a seawater cooling water system, which can maintain the effect for a long period of time by adding a low concentration of a drug and can prevent attachment disorders of a wide range of marine organisms and slimes. Is the subject.

Therefore, the inventor of the present invention sets conditions such as the concentration of chlorine dioxide in seawater and the contact time with marine organisms within a specific range to specifically impair the attachment of desired marine organisms. When the minimum concentration of chlorine dioxide in seawater where the preventive effect can be obtained is set as the standard concentration, chlorine dioxide is added almost continuously so as to be less than this standard concentration, and chlorine dioxide is added so as to be above the standard concentration. By adding it intermittently in a short period of time, it effectively prevents attachment disorders of a wide range of marine organisms including mussels such as purple mussels, fujitsubos, pectinatella magnifica, hydroins and slimes for a long period of time. Surprisingly, we found that even if the amount of chemicals added was reduced, an effective effect of preventing adhesion disorders such as marine organisms and slime could be obtained, and the present invention was completed. It was.
That is, the inventor of the present invention can effectively prevent a wide range of marine species and slime adhesion disorders by adopting the configuration of the present invention, even though the total amount of the drug used is reduced. I found an unexpected effect.

Thus, according to the present invention, the minimum concentration of chlorine dioxide in seawater of a transient seawater cooling water system, which can obtain a desired effect of preventing adhesion disorders of marine organisms when chlorine dioxide is continuously added at a constant concentration, is determined. Use as the reference concentration
Before the chlorine dioxide concentration of Kiumi underwater, so that the periods of high concentration of more than the reference concentration and low concentration period of less than the reference concentration is alternately may generate chlorine dioxide in the chlorine dioxide or該海water It consists of alternating low and high concentrations of the compound.
Low concentrations of less than the reference concentration, Ri concentration der of 1 / 4-9 / 10 of the reference concentration, the reference concentration or a high concentration, wherein 0.02 to 0.5 / L der Rukoto A method for preventing adhesion disorders of marine organisms in a transient seawater cooling water system is provided.

According to the present invention, the addition of a low concentration of a drug reduces the total amount of the drug used, but the effect is maintained for a long period of time, and the adhesion disorder of a wide range of marine organisms and slime is prevented. It is possible to provide a method for preventing adhesion disorders of marine organisms in the obtained seawater cooling water system.
That is, an excellent effect of preventing adhesion disorders of marine organisms can be obtained even if a small amount of chlorine dioxide is added as compared with the conventional method of adding chlorine dioxide alone. In addition, this reduction in the amount of the drug added brings about a further reduction effect of the running cost including the amount of the drug used.
In addition, the method for preventing adhesion disorders of marine organisms of the present invention does not use chlorine agents or bromine agents whose residual chlorine concentration in wastewater is subject to regulation, has strong bactericidal activity, and does not form harmful organic chlorine compounds. Has the advantage of having a small impact on the environment.
The method for preventing attachment disorders of marine organisms of the present invention is effective in preventing attachment disorders of a wide range of marine organism species, for example, mussels such as mussels, barnacles, mussels, hydroins and other marine organisms and slimes. Is.
The mechanism of the present invention is considered as follows.
In sessile organisms, bacteria and the like first adhere to the surface of the substrate to form slime, then diatoms (phytoplankton) adhere to form a bacterial film, and these bacterial films produce acidic polysaccharides, resulting in large attachment. It is thought that the transition is caused by the attraction of biological larvae.
In the method for preventing attachment disorders of marine organisms of the present invention, a high concentration of chlorine dioxide efficiently inhibits the succession process of attached organisms, and even if a period of concentration lower than the reference concentration is provided, sufficient prevention of adhesion disorders is provided. Is considered to be obtained.

In addition, the method for preventing attachment disorders of marine organisms of the present invention more exerts the above effects when any one of the following conditions is satisfied.
(1) A low concentration less than the reference concentration is a concentration of 1/4 to 9/10 of the reference concentration.
(2) A low concentration less than the reference concentration is a concentration of 1/3 to 9/10 of the reference concentration.

(How to prevent adhesion disorders of marine organisms)
The method for preventing adhesion disorders of marine organisms in a seawater cooling water system of the present invention is the minimum amount of chlorine dioxide in seawater that can obtain a desired effect of preventing adhesion disorders of marine organisms when chlorine dioxide is continuously added at a constant concentration. Using the concentration as the reference concentration
Chlorine dioxide or chlorine dioxide in the seawater is added so that the chlorine dioxide concentration in the seawater of the seawater cooling water system alternates between the low concentration period below the reference concentration and the high concentration period above the reference concentration. It is characterized by adding a compound that can be generated.

(Chlorine dioxide)
Chlorine dioxide used in the present invention is an extremely unstable chemical substance, and therefore its storage and transportation are extremely difficult. Therefore, chlorine dioxide or a compound capable of generating chlorine dioxide in seawater may be added directly to seawater, but chlorine dioxide is produced (produced) by a known method on the spot, or chlorine dioxide is produced in seawater. It is preferable to add a compound that can be generated to water to generate chlorine dioxide and adjust the concentration to a desired value before use. Here, the "water" is not particularly limited, and examples thereof include industrial water and clean water.
For example, chlorine dioxide can be produced by the following reaction, and a commercially available chlorine dioxide generator (equipment) can also be used.
(1) Reaction of sodium hypochlorite with hydrochloric acid and sodium chlorite NaOCl + 2HCl + 2NaClO ₂ → 2ClO ₂ + 3NCl + H ₂ O
(2) Reaction of sodium chlorite with hydrochloric acid 5NaClO ₂ + 4HCl → 4ClO ₂ + 5 NaCl + 2H ₂ O
(3) Reaction with sodium chlorate, hydrogen peroxide and sulfuric acid _{2 NaClO 3} + H 2 O ₂ + H ₂ SO ₄ → 2ClO ₂ + Na ₂ SO ₄ + O ₂ + 2H ₂ O

(Reference concentration)
In the method for preventing adhesion disorders of marine organisms of the present invention, a specific concentration of chlorine dioxide in seawater of a seawater cooling water system or a compound capable of generating chlorine dioxide in seawater based on a reference concentration of chlorine dioxide (hereinafter, these are combined). (Also called "chlorine dioxide") is added for a specific time.
In the present invention, the "reference concentration" of chlorine dioxide means the minimum concentration of chlorine dioxide in seawater where a desired effect of preventing adhesion damage to marine organisms can be obtained when chlorine dioxide is continuously added at a constant concentration. To do.
The "reference concentration" varies depending on the addition time of chlorine dioxide. For example, when considering the daily addition, the longer the addition time, the lower the reference concentration. On the contrary, the shorter the addition time, the higher the reference concentration. Therefore, the reference concentration in the present invention means the minimum concentration of chlorine dioxide in seawater at which a desired effect of preventing the adhesion of marine organisms can be obtained when chlorine dioxide is continuously added at a constant concentration for an arbitrary time. The above-mentioned arbitrary time may be adjusted to the time actually added.

In addition, the "reference concentration" varies depending on the pollution state and temperature (water temperature) of the seawater of the seawater system cooling water system to be added, the marine organism species (attached organism species) that inhabit the seawater, etc., so the following method is used in advance. Therefore, it is possible to provide a water channel test device in the seawater system cooling water system to be added, measure the "effect of preventing adhesion of marine organisms", and determine from the result.

(1) A flow rate of seawater to be measured is 1 m in a multi-system waterway (test plot) equipped with an acrylic column (inner diameter 64 mm x length 300 mm x thickness 2 mm, surface area 602.88 cm ^{2) for confirming the adhesion prevention effect.} Water is passed transiently at ^{3 / h.}
(2) A chemical-free (blank) channel is provided, and chlorine dioxide having different concentrations (set concentration in the column) is added to each channel from the upstream side (front) of the column in each channel at a constant concentration for an arbitrary time. Add continuously (if any time less than 24 hours per day is acceptable, the addition time shall be 20 hours per day).
(3) When 50 g of marine organisms adhere to the column of the chemical-free waterway, the passage of seawater and the addition of chemicals are stopped.
(4) The column of each channel is taken out, the mass W1 (g) of the column containing the attached marine organisms is measured, and the difference from the mass W0 (g) of the column at the time of drying measured in advance before the test. The amount of attached organisms [W1-W0 (g)] is obtained from.
(5) When the amount of attached organisms is 5 g / 600 cm ² or less, it is judged that there is a sufficient effect of preventing the attachment of marine organisms, and the drug concentration is defined as the "reference concentration".
In addition, when the amount of attached organisms in (3) above is less than 50 g, and when the amount of attached organisms is 0.1 times or less of the amount of attached organisms, it is judged that "there is a sufficient effect of preventing attachment disorders of marine organisms". The drug concentration may be defined as the "reference concentration", and the minimum concentration of the drug when there is no attachment of marine organisms to be damaged by the addition of the drug in the seawater cooling water system may be determined as the "reference concentration".

The period for passing seawater and the period for adding chemicals vary depending on the state of seawater in the seawater system cooling water system, but are usually about 20 to 90 days.
When chlorine dioxide is prepared and used on the spot as described in the test example, the generation of chlorine dioxide should be confirmed in a preliminary test.
The amount of attached organisms includes sessile organisms such as mussels and marine attached organisms such as barnacles and mussels, as well as detritus, which contains a large amount of organic substances such as slime excreta, carcasses, and extracellular secretions that adhere to columns, in seawater. The viscous particles and suspended matter contained are also included.

In addition, the "reference concentration" is sufficient for marine organisms by continuously adding chlorine dioxide at a constant concentration in heat exchangers, condensers, or piping in front of them, which are subject to adhesion disorders of marine organisms. It can be said that it is the minimum concentration of chlorine dioxide that can prevent adhesion damage.
Therefore, in a seawater cooling water system in which chlorine dioxide is continuously added at a constant concentration to prevent adhesion damage to marine organisms, heat exchangers and condensers are effective in preventing adhesion of marine organisms. Since it is considered that the minimum concentration is maintained, the chlorine dioxide concentration near the outlet can be used as the reference concentration.
As described above, the "reference concentration" varies depending on the pollution state and temperature (water temperature) of the seawater of the seawater system cooling water system to be added, the marine organism species (attached organism species) that inhabit the seawater, etc., but usually heat It is about 0.02 to 0.10 mg / L in the vicinity of the outlet of the target facility for marine organism adhesion in the exchanger and condenser.

In the present invention, it is necessary to alternately provide "low concentration period" and "high concentration period", and by adopting such a configuration, the total amount of the drug used can be reduced. However, it is possible to continuously prevent a wide range of marine species and slime adhesion disorders.
That is, in the present invention, chlorine dioxide is used to prevent adhesion damage of marine organisms in the seawater cooling water system, for example, chlorine dioxide in seawater at a desired place such as a heat exchanger has a desired concentration. So, more specifically, chlorine dioxide is added to any place in the seawater cooling water system so that the "low concentration period" and the "high concentration period" alternate to increase the concentration of chlorine dioxide. adjust.
Therefore, from the viewpoint of chlorine dioxide addition, the "low concentration period" and the "high concentration period" may be rephrased as the "low concentration addition period" and the "high concentration addition period", respectively.

(Period of low concentration)
In the method for preventing adhesion disorders of marine organisms of the present invention, a period for adding chlorine dioxide is provided so that the chlorine dioxide concentration in the seawater of the seawater cooling water system becomes a low concentration below the reference concentration.
A low concentration below the reference concentration is preferably a concentration of 1/4 to 9/10 of the reference concentration.
If the low concentration is less than 1/4 of the standard concentration, a sufficient effect of preventing adhesion disorders of marine organisms may not be obtained. On the other hand, if the low concentration exceeds 9/10 of the reference concentration, the effect of reducing the amount of the drug added may not be obtained.
The preferred low concentration is 1/3 to 9/10 of the reference concentration, more preferably 2/5 to 9/10, and even more preferably 2/3 to 9/10 of the reference concentration.
As described above, the low concentration varies depending on the pollution state and temperature (water temperature) of the seawater of the seawater system cooling water system to be added, the marine organism species (attached organism species) that inhabit the seawater, etc., but usually marine organisms. It is about 0.008 to 0.09 mg / L, preferably about 0.01 to 0.05 mg / L in the vicinity of the outlet of the equipment to be adhered.

The addition time of chlorine dioxide in the "low concentration period" depends on the chlorine dioxide concentration, but when the concentration is 0.008 to 0.09 mg / L, it is 6 hours or more per day. preferable.
If the addition time is less than 6 hours, a sufficient effect of preventing adhesion disorders of marine organisms may not be obtained even if "high concentration periods" are alternately provided.
More preferable addition times are 8 hours or more, and more preferably 10 hours or more, 16 hours or more, 18 hours or more, 20 hours or more, and 22 hours or more in that order.
The "low concentration period" may be added in several portions at the above time per day.

(Period of high concentration)
In the method for preventing adhesion disorders of marine organisms of the present invention, a period for adding chlorine dioxide is provided so that the chlorine dioxide concentration in the seawater of the seawater cooling water system becomes a high concentration equal to or higher than the reference concentration.
High concentrations above the standard concentration vary depending on the pollution state and temperature (water temperature) of the seawater of the seawater system cooling water system to be added, marine organism species (attached organism species) that inhabit the seawater, etc., but usually marine organisms It is about 0.02 to 0.5 mg / L, preferably about 0.03 to 0.5 mg / L, and more preferably about 0.05 to 0.5 mg / L in the vicinity of the outlet of the equipment to be adhered.

The chlorine dioxide addition time in the "high concentration period" depends on the chlorine dioxide concentration, but when the concentration is 0.02 to 0.5 mg / L, it is 0.2 to 8 hours per day. It is preferable to have it.
If the addition time is less than 0.2 hours, a sufficient effect of preventing adhesion disorders of marine organisms may not be obtained even if "low concentration periods" are alternately provided. On the other hand, if the addition time exceeds 8 hours, the effect of reducing the amount of the drug added may not be obtained.
The more preferable addition time is 0.2 to 7 hours, and more preferably 0.2 to 6 hours, 0.35 to 6 hours, 0.35 to 4 hours, 0.5 to 4 hours, and 1 to 4 hours in that order. Is.

The chlorine dioxide concentration and the addition time in the "high concentration period" usually tend to be shorter as the concentration is higher and longer as the concentration is closer to the reference concentration, with respect to the desired effect.
Further, the "low concentration period" and the "high concentration period" may be alternately provided for more than one day, and there is no drug between the "low concentration period" and the "high concentration period". A period of addition may be provided.

(Other additives)
In the method for preventing marine biofouling of the present invention, other marine biofouling preventive agents known in the art may be used in combination, and hydrogen peroxide; diamine, tertiary amine, quaternary ammonium salt may be used in combination. Cationic surfactants such as; dialkyldithiocarbamate; other chlorine agents (including electrolytic chlorine); bromine agents are particularly preferred.
Further, in the method for preventing adhesion disorders of marine organisms of the present invention, other additives known in the art may be used in combination as long as the effects of the present invention are not impaired. Examples include metal corrosion inhibitors and antifoaming agents.

(Addition place)
The seawater cooling water system includes, for example, water intake system equipment, equipment to be cooled such as a condenser and other equipment, and water discharge system equipment. The water intake system equipment consists of a headrace, a screen for removing foreign substances in seawater, a circulating water pump (water intake pump), a circulating water pipe (water intake pipe), and the like.

The place where chlorine dioxide is added in the present invention may be in the intake channel, the pipe attached to the heat exchanger or the condenser, the headrace, the inlet of the heat exchanger or the inlet of the condenser, but the sea. In terms of the effect of preventing damage due to the adhesion of living organisms, the vicinity of the intake of the intake pump and the inlet of the heat exchanger or condenser are preferable.
Further, the place where chlorine dioxide is added in the present invention is not limited to one place, and it is desired to meet the addition conditions of the present invention, that is, to prevent adhesion damage of marine organisms in a seawater cooling water system by using chlorine dioxide. Regarding the concentration of chlorine dioxide in seawater at a place, as long as a "low concentration period" and a "high concentration period" are alternately provided, a plurality of places may be provided.

(Addition method)
Examples of the method for adding chlorine dioxide in the present invention include a method using an injection pump or the like. In the present invention, conventional physical means can be used to diffuse a trace amount of the drug into the seawater cooling water system quickly and substantially uniformly. Specific examples thereof include installation of a diffuser, a stirrer, a baffle plate, etc. in the water system. In addition, since the equipment corresponding to these is attached to the seawater cooling water system, it may be diverted.

The present invention will be specifically described with reference to the following test examples, but the present invention is not limited thereto.

[Test Example 1]
We confirmed the effect of chlorine dioxide on preventing adhesion disorders of marine organisms.
A waterway test device was installed somewhere along the coast of Wakayama Prefecture facing the Pacific Ocean, and tests were conducted.
Unfiltered seawater (pH 8) pumped using a submersible pump is placed in a channel (test plot) branched into 5 systems at a flow rate of 1 m ³ / h for 70 days (August 2018 to October 2018). Chlorine dioxide was added to each channel so as to have the drug concentration shown in Table 1 and the addition time per day.

The reference concentration was measured by a preliminary test based on the above method for determining the "reference concentration". That is, seawater was passed for 21 days with the addition time of chlorine dioxide being 24 hours. As a result, 50 g of marine organisms adhered to the column of the water channel to which no chemical was added. Therefore, water flow and chemical addition were stopped, the column of the channel to which chlorine dioxide was added at each concentration was taken out, and the amount of attached organisms on the column to which marine organisms were attached was determined, and the amount of attached organisms was 5 g / 600 cm ² or less. The amount of chlorine dioxide added was used as the reference concentration. As a result, it was determined that the standard concentration of chlorine dioxide in the water system of this test was 0.025 mg / L, so 0.010 mg / L was set as the concentration for the "low concentration period" and the "high concentration period" was set. The concentrations of "." Were set to 0.10 mg / L and 0.19 mg / L.
The drug concentration is the set concentration in the acrylic column for confirming the effect of preventing adhesion disorders below, but in this test example, the route from the addition of the drug to the release from the test tube described below is short, and the set concentration. Has been confirmed to be about the same as the released concentration.

An acrylic column (inner diameter 64 mm x length 300 mm x thickness 2 mm, surface area 602.88 cm ² ) is inserted into each channel to check the effect of preventing adhesion obstacles, and the amount of attached organisms attached to the column after water flow is completed. It was measured and the effect of preventing adhesion damage was evaluated.
In addition, a test tube (inner diameter 23.4 mm, length 1000 mm, wall thickness 1.0 mm) made of titanium tube is installed in each water channel to confirm the slime stain prevention effect, and is placed on the inner surface of the test tube after water flow is completed. The amount of stains mainly composed of the formed slime was measured, and the stain prevention effect was evaluated. In addition, it was also tested that no drug was added as a blank.
The results obtained are shown in Table 1 along with the drug concentration and the time of addition per day.

(Chlorine dioxide)
As for chlorine dioxide, an aqueous solution obtained by appropriately diluting sodium chlorite and hydrochloric acid with pure water is mixed in a tube before the chemical addition point and retained for 1 hour so that chlorine dioxide having the concentration shown in Table 1 can be obtained. An aqueous solution of chlorine dioxide generated after a long period of time was added using a metering pump from the front of a test tube composed of an acrylic column for confirming the effect of preventing adhesion damage and a titanium tube. Regarding the generation of chlorine dioxide, the generation has been confirmed in a preliminary test.

(Confirmation of adhesion failure prevention effect)
After the test, the mass Wa (g) of the column removed from the water channel was measured. The amount of attached organisms (g) was calculated by the following formula together with the mass Wb (g) of the column at the time of drying, which was measured in advance before the test.
Adherent biological amount (g) = Wa-Wb
During this test period, the seawater temperature changed from 28 to 26 ° C, and the amount of sessile organisms in the column of the chemical-free channel was as large as 326 g / 600 cm ^2, and the sessile organisms were mainly mussels such as green mussels, barnacles, and bryozoa. Derived from marine sessile organisms such as species. In addition, detritus containing a large amount of organic substances such as adhering organisms, slime excrement and carcasses, and extracellular secretions, and viscous particles and suspended matter contained in seawater also adhere to the column, and these are also included in the amount of attached organisms.
From the state of attachment of marine organisms in the blank, it can be judged that in this test example, there is a sufficient effect of preventing attachment disorders of marine organisms when the amount of attached organisms is 15 g or less. Further, when the amount of attached organisms is 5 g or less, no attachment of organisms or dirt is visually confirmed, and it can be judged that the best prevention of attachment disorders of marine organisms is achieved.

(Confirmation of stain prevention effect)
After the test, dirt mainly composed of slime formed on the inner surface of the test tube removed from the water channel was scraped off, collected in a 100 mL graduated cylinder, and the wet volume after standing for 4 hours was measured.
The slime scraped off in the blank is mainly derived from microorganisms attached to the test tube. Similar to the confirmation of the adhesion prevention effect on the column, the slime adhering to the inner surface of the test tube also contains detritus, but the titanium tube diameter of the test tube is about 1/3 of the column diameter, and seawater cooling inside the tube. It has been confirmed that the flow velocity of water is high and that there is no attachment of mussels such as mussels and marine sessile organisms such as barnacles and mussels.
From the state of slime adhesion on the blank, it can be judged that in this test example, there is a sufficient effect of preventing slime adhesion failure when the wet volume is 5 mL or less. Further, when the wet volume is 2 mL or less, the adhesion of slime is not visually confirmed at all, and it can be judged that it is the best prevention of adhesion obstacles of marine organisms.

The following can be seen from the results in Table 1.
(1) When chlorine dioxide is added in a low concentration for 20 to 22 hours per day and chlorine dioxide is added in a high concentration for 2 to 4 hours per day (Examples 1 and 2), an excellent effect of preventing adhesion disorders can be obtained. More specifically, even if the integrated amount (total amount of the drug used) is the same, compared with the method of continuously adding chlorine dioxide at the "reference concentration" (Comparative Example 1), "a period of low concentration (reference concentration)""2/5 of the concentration added for 20 to 22 hours per day)" and "High concentration period (7.6 times or 4 times the standard concentration for 2 to 4 hours per day)" alternate. (Examples 1 and 2), the "adherent biological amount" is reduced. (2) A low concentration of 0.010 mg / L of chlorine dioxide is added twice in 10 hours to a concentration of 0.10 mg / L. When the high concentration of chlorine dioxide was added twice in 2 hours (Example 2), a low concentration of 0.010 mg / L of chlorine dioxide was added for 22 hours, and the concentration of 0.19 mg / L of dioxide was only 2 hours. Compared with the case where high concentration of chlorine was added (Example 1), the amount of deposits on the column after the test was small. More specifically, the addition of chlorine dioxide was carried out during the period of low concentration (concentration of 2/5 of the standard concentration). By repeating twice a day (Example 2) so that "addition for 10 hours" and "period of high concentration (addition for 2 hours at a concentration four times the standard concentration)" are repeated (Example 2), "Amount of adherent organisms". Is significantly reduced

[Test Example 2]
It was confirmed that chlorine dioxide was added so that the "low concentration period" and the "high concentration period" alternated, and the effect of preventing adhesion damage to marine organisms was confirmed.
A waterway test device was installed somewhere along the coast of Wakayama Prefecture facing the Pacific Ocean, and tests were conducted.
Unfiltered seawater (pH 8) pumped using a submersible pump is placed in a channel (test plot) branched into 6 systems at a flow rate of 1 m ³ / h for 76 days (March 2019 to June 2019). Chlorine dioxide was added to each channel so as to have the drug concentration shown in Table 2 and the addition time per day.

The reference concentration was measured by a preliminary test based on the above method for determining the "reference concentration". That is, seawater was passed for 50 days with the addition time of chlorine dioxide being 24 hours. As a result, 45 g of marine organisms adhered to the column of the water channel to which no chemical was added. Although the amount of attached organisms did not reach 50 g, the water flow and the addition of chemicals were stopped, the column of the channel to which chlorine dioxide was added at each concentration was taken out, and the amount of attached organisms on the column to which marine organisms were attached was determined. The amount of chlorine dioxide added when the amount of attached organisms was 4.5 g / 600 cm ² or less was used as the reference concentration. As a result, it was determined that the standard concentration of chlorine dioxide in the water system of this test was 0.025 mg / L, so 0.020 mg / L was set as the concentration for the "low concentration period" and the "high concentration period" was set. The concentration was set to 0.030 mg / L to 0.070 mg / L.
The drug concentration is the set concentration in the acrylic column for confirming the effect of preventing adhesion disorders below, but in this test example, the route from the addition of the drug to the release from the test tube described below is short, and the set concentration. Has been confirmed to be about the same as the released concentration.

An acrylic column (inner diameter 64 mm x length 300 mm x thickness 2 mm, surface area 602.88 cm ² ) is inserted into each channel to check the effect of preventing adhesion obstacles, and the amount of attached organisms attached to the column after water flow is completed. It was measured and the effect of preventing adhesion damage was evaluated.
In addition, a test tube (inner diameter 23.4 mm, length 1000 mm, wall thickness 1.0 mm) made of titanium tube is installed in each water channel to confirm the slime stain prevention effect, and is placed on the inner surface of the test tube after water flow is completed. The amount of stains mainly composed of the formed slime was measured, and the stain prevention effect was evaluated. In addition, it was also tested that no drug was added as a blank.
The results obtained are shown in Table 2 along with the drug concentration and the time of addition per day.

(Chlorine dioxide)
Chlorine dioxide was generated in the same manner as in Test Example 1, and addition was carried out in the same manner.

(Confirmation of adhesion failure prevention effect)
In the same manner as in Test Example 1, the amount of attached organisms (g) on the column was calculated, and the effect of preventing the attachment of marine organisms was confirmed.
During this test period, the seawater temperature changed from 15 to 22 ° C, and the amount of sessile organisms in the column of the chemical-free waterway was as large as 233 g / 600 cm ^2, and the sessile organisms were mainly mussels such as mussels, mussels, and mussels. Derived from marine sessile organisms such as species. In addition, detritus containing a large amount of organic substances such as adhering organisms, slime excrement and carcasses, and extracellular secretions, and viscous particles and suspended matter contained in seawater also adhere to the column, and these are also included in the amount of attached organisms.
From the state of attachment of marine organisms in the blank, it can be judged that in this test example, there is a sufficient effect of preventing attachment disorders of marine organisms when the amount of attached organisms is 15 g or less. Further, when the amount of attached organisms is 5 g or less, no attachment of organisms or dirt is visually confirmed, and it can be judged that the best prevention of attachment disorders of marine organisms is achieved.

(Confirmation of stain prevention effect)
In the same manner as in Test Example 1, the wet volume after standing for 4 hours was measured, and the stain prevention effect was confirmed.
The slime scraped off in the blank is mainly derived from microorganisms attached to the test tube. Similar to the confirmation of the adhesion prevention effect on the column, the slime adhering to the inner surface of the test tube also contains detritus, but the titanium tube diameter of the test tube is about 1/3 of the column diameter, and seawater cooling inside the tube. It has been confirmed that the flow velocity of water is high and that there is no attachment of mussels such as mussels and marine sessile organisms such as barnacles and mussels.
From the state of slime adhesion on the blank, it can be judged that in this test example, there is a sufficient effect of preventing slime adhesion failure when the wet volume is 5 mL or less. Further, when the wet volume is 2 mL or less, the adhesion of slime is not visually confirmed at all, and it can be judged that it is the best prevention of adhesion obstacles of marine organisms.

The following can be seen from the results in Table 2.
(1) Compared with the method in which chlorine dioxide is continuously added at a "reference concentration" for 22 hours per day (Comparative Example 3), "a period of low concentration (a concentration of 4/5 of the reference concentration is 18 per day). By alternating between "time addition" and "high concentration period (2.8 times the standard concentration for 2 hours per day)" (Example 3), the integrated amount (total use of the drug) The amount) can be reduced. By assuming an actual usage situation, it can be seen that the effect of reducing the accumulated amount of chlorine dioxide added of the present invention is excellent. For example, the integrated amount of 0.50 mg / L × hours / day in Example 3 has a reduction effect of 0.05 mg / L × hours / day with respect to the integrated amount of 0.55 mg / L × hours / day in Comparative Example 3. If this is applied to the amount of seawater intake for cooling a general thermal power plant of 150,000 m ³ / hour, the amount of chlorine dioxide will be reduced by 225 kg / month.

(2) Compared with the method in which chlorine dioxide is continuously added at a "reference concentration" for 22 hours per day (Comparative Example 3), "a period of low concentration (a concentration of 4/5 of the reference concentration is 18 per day). By alternately performing "time addition)" and "high concentration period (3 hours per day at a concentration 2.4 times the standard concentration)" (Example 4), an equivalent integrated amount (of the drug) The "total amount used" significantly reduces the "adherent biological amount" (3) A method in which chlorine dioxide is continuously added at a concentration of 4/5 of the "standard concentration" for 24 hours per day (Comparative Example 4). In comparison, "low concentration period (addition of 18 hours per day at a concentration of 4/5 of the standard concentration)" and "high concentration period (4 hours per day at a concentration 1.2 times the standard concentration)" (Example 5), the "adhered biological amount" is significantly reduced at the same integrated amount (total amount of the drug used).

[Test Example 3]
We confirmed the effect of preventing adhesion damage to marine organisms when chlorine dioxide was added so that the "low-concentration period" and the "high-concentration addition period" alternated.
A waterway test device was installed somewhere along the coast of Wakayama Prefecture facing the Pacific Ocean, and tests were conducted.
Unfiltered seawater (pH 8) pumped using a submersible pump is placed in a channel (test plot) branched into four systems at a flow rate of 1 m ³ / h for 79 days (August 2019 to October 2019). Chlorine dioxide was added to each channel so as to have the drug concentration shown in Table 2 and the addition time per day.

The reference concentration was measured by a preliminary test based on the above method for determining the "reference concentration". That is, seawater was passed for 50 days with the addition time of chlorine dioxide being 24 hours. As a result, 50 g of marine organisms adhered to the column of the water channel to which no chemical was added. Therefore, water flow and chemical addition were stopped, the column of the channel to which chlorine dioxide was added at each concentration was taken out, and the amount of attached organisms on the column to which marine organisms were attached was determined, and the amount of attached organisms was 5 g / 600 cm ² or less. The amount of chlorine dioxide added was used as the reference concentration. As a result, it was determined that the standard concentration of chlorine dioxide in the water system of this test was 0.015 mg / L, so 0.012 mg / L was set as the concentration for the "low concentration period" and the "high concentration period" was set. The concentration was set to 0.020 mg / L.
The drug concentration is the set concentration in the acrylic column for confirming the effect of preventing adhesion disorders below, but in this test example, the route from the addition of the drug to the release from the test tube described below is short, and the set concentration. Has been confirmed to be about the same as the released concentration.

An acrylic column (inner diameter 64 mm x length 300 mm x thickness 2 mm, surface area 602.88 cm ² ) is inserted into each channel to check the effect of preventing adhesion obstacles, and the amount of attached organisms attached to the column after water flow is completed. It was measured and the effect of preventing adhesion damage was evaluated.
In addition, a test tube (inner diameter 23.4 mm, length 1000 mm, wall thickness 1.0 mm) made of titanium tube is installed in each water channel to confirm the slime stain prevention effect, and is placed on the inner surface of the test tube after water flow is completed. The amount of stains mainly composed of the formed slime was measured, and the stain prevention effect was evaluated. In addition, it was also tested that no drug was added as a blank.
The results obtained are shown in Table 3 along with the drug concentration and the time of addition per day.

(Chlorine dioxide)
Chlorine dioxide was generated in the same manner as in Test Example 1, and addition was carried out in the same manner.

(Confirmation of adhesion failure prevention effect)
In the same manner as in Test Example 1, the amount of attached organisms (g) on the column was calculated, and the effect of preventing the attachment of marine organisms was confirmed.
During this test period, the seawater temperature changed from 29 to 24 ° C, and the amount of sessile organisms in the column of the chemical-free waterway was as large as 147 g / 600 cm ^2, and the sessile organisms were mainly mussels such as green mussels, barnacles, and bryozoa. Derived from marine sessile organisms such as species. In addition, detritus containing a large amount of organic substances such as adhering organisms, slime excrement and carcasses, and extracellular secretions, and viscous particles and suspended matter contained in seawater also adhere to the column, and these are also included in the amount of attached organisms.

(Confirmation of stain prevention effect)
In the same manner as in Test Example 1, the wet volume after standing for 4 hours was measured, and the stain prevention effect was confirmed.

The following can be seen from the results in Table 3.
(1) Compared with the method of continuously adding chlorine dioxide at a "reference concentration" (Comparative Example 5), "a period of low concentration (addition at a concentration of 4/5 of the reference concentration for 17 hours per day)". And "a period of high concentration (7 hours per day at a concentration of 4/3 times the standard concentration)" are performed alternately (Example 6), so that the integrated amount (total amount of the drug used) is small. Nevertheless, the "wet volume" is reduced to 1/3 or less. (2) Addition of chlorine dioxide is added to "low concentration period (addition at a concentration of 4/5 of the standard concentration for 8.5 hours)" and " By repeating twice a day so that "a high concentration period (added at a concentration of 4/3 times the reference concentration for 3.5 hours)" alternates (Example 7), the integrated amount (total amount of the drug used). ) Is small, but the "adherent biological amount" is reduced and the "wet volume amount" is reduced to about 1/2.

Marine organisms attach during the attached larval stage, and the mechanism of their attachment is generally assumed to be attached to the formed slime-like biofilm. The amount of wet volume in this test is the amount of slime, and creating a situation where the amount of slime, which is the basis for adhesion, is small leads to prevention of marine organism adhesion and damage caused by it. Therefore, if the wet volume is 2 mL or less, which can hardly be confirmed, it is considered that not only the direct adhesion prevention effect of the drug to marine organisms but also the indirect adhesion prevention effect can prevent the adhesion disorder. ..

Claims (2)

The minimum concentration of chlorine dioxide in the seawater of the transient seawater cooling water system, which can obtain the desired effect of preventing adhesion damage to marine organisms when chlorine dioxide is continuously added at a constant concentration, is used as the reference concentration.
Before the chlorine dioxide concentration of Kiumi underwater, so that the periods of high concentration of more than the reference concentration and low concentration period of less than the reference concentration is alternately may generate chlorine dioxide in the chlorine dioxide or該海water It consists of alternating low and high concentrations of the compound.
Low concentrations of less than the reference concentration, Ri concentration der of 1 / 4-9 / 10 of the reference concentration, the reference concentration or a high concentration, wherein 0.02 to 0.5 / L der Rukoto A method for preventing adhesion disorders of marine organisms in the transient seawater cooling water system. The method for preventing adhesion disorders of marine organisms in a transient seawater cooling water system according to claim 1, wherein a low concentration less than the reference concentration is a concentration of 1/3 to 9/10 of the reference concentration.