JP3199577B2 - Industrial seawater cooling water treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating industrial seawater cooling water which suppresses the adhesion and growth of seawater-adhering organisms in an industrial seawater cooling water system. In more detail, in a seawater cooling water system for industrial use, by using hydrogen peroxide or a hydrogen peroxide generator and chlorine gas or an effective chlorine generator together, by-products of trihalomethanes are not generated, and The present invention relates to a method for treating industrial seawater cooling water that efficiently suppresses the attachment and growth of organisms.

[0002]

2. Description of the Related Art In thermal power plants and nuclear power plants, a large amount of seawater is used as cooling water for condensers. In this case, a large amount of marine organisms such as barnacles, mussels, and bryozoa adhere to the seawater intake channel walls, pipes, and heat exchangers. Above all, bivalves such as mussels growing on foot yarns grow fast, and when they become adults, they block the flow of water and cause turbulence by blocking part of the heat exchanger tube, resulting in erosion corrosion, etc. Cause obstacles.

[0003] For this reason, conventionally, a method of peeling and removing by a machine or manually has been performed regularly, but the amount is enormous, and not only is it difficult to dispose environmentally, such as in terms of pollution,
The disadvantage is that the operation must be stopped for the removal work. Therefore, in order to prevent these marine organisms from becoming densely adhered, chlorine gas such as sodium hypochlorite and electrolytic chlorine or an effective chlorine generator (hereinafter referred to as a chlorine agent), hydrogen peroxide or hydrogen peroxide generation is used. Agent (hereinafter referred to as a hydrogen peroxide agent) and tri-n-butyltin or tri-n-
Application of paints containing organotin compounds such as chlorides, oxides and hydroxides of phenyltin has been performed.

[0004] However, there is a concern that the addition of a chlorinating agent may produce trihalomethanes and, in some cases, dioxin. Use of an organotin compound-containing paint has residual toxicity and accumulation toxicity, and both are bio-concentrated. Therefore, it is not preferable for environmental pollution prevention. In addition, hydrogen peroxide has recently been widely used as a compound that has the least effect on the environment because it becomes oxygen and water when decomposed.However, because of its low toxicity, selectivity to attached organisms appears, and the amount of hydrogen peroxide added is small. When the amount is reduced, it becomes difficult to suppress the attachment of the attached organism.

In particular, bivalves such as mussels having a large amount of hydrogen peroxide-degrading enzymes have high resistance to hydrogen peroxide and cannot be treated without adding a large amount of hydrogen peroxide. In view of the above circumstances, the inventors of the present invention have proposed a method for suppressing the adhesion of seawater-adhering organisms by adding a hydrogen peroxide agent and a chlorine agent in combination (Japanese Patent Publication No.
No. 61-2439).

[0006]

In general, when two kinds of drugs are injected into seawater, it is preferable in terms of workability to use a one-part preparation. However, the hydrogen peroxide agent and the chlorinating agent described in the above-mentioned patent publication have a risk of heat generation due to a rapid oxidation-reduction reaction when mixed at a high concentration, and to avoid the danger, store them in separate tanks. It had to be separately injected into the seawater cooling water system.

A first embodiment of the invention described in the above-mentioned patent publication is a method for simultaneously and separately injecting a hydrogen peroxide agent and a chlorine agent into seawater (simultaneous addition method 1). Since the effect of singlet oxygen (active oxygen) generated by the oxidation-reduction reaction with available chlorine is expected to suppress the adhesion of attached organisms, it is preferable to provide an injection point at the same approximate location.

In this case, both chemicals are consumed by the oxidation-reduction reaction, and the addition site and a part of the region after the agent exhibit an effective adhesion and growth inhibitory effect to marine organisms. However, there was a problem that a sufficient suppression effect was not exhibited (Technical problem 1). Therefore, when adding a hydrogen peroxide agent and a chlorine agent, in order to avoid contact between the two agents, a method of adding them alternately at a time interval and at the same time at another time (see the second patent document described above). Embodiment: intermittent addition method) was implemented.

However, in this case, only the hydrogen peroxide agent or the chlorine agent is temporarily added. When only the chlorine agent is added, the concentration of the chlorine agent is 0.07 mg / l or more as available chlorine. Then, a problem that trihalomethanes were generated by reacting with bromide ions in seawater (see Comparative Example 11) was confirmed (technical problem 2).

It was observed that the amount of trihalomethanes produced tended to increase as the amount of the chlorine agent added increased (see Comparative Examples 12 to 18). In the simultaneous addition method 1,
In order to reduce the high-concentration contact between hydrogen peroxide and available chlorine in seawater and to suppress the consumption of both chemicals by redox reaction,
For example, a method of injecting one drug from above the cross section of the cooling water pipe and injecting the other drug from below the cross section of the pipe, that is, isolating the injection points of both drugs can be considered (simultaneous addition method 2).

However, even with this method, technical problem 1 could not be solved, and the production of trihalomethanes was confirmed in the same manner as described above, although the amount of production was reduced (Comparative Examples 4, 8, 10, 10). 23 and 24). Therefore, in the invention described in Japanese Patent Publication No. Sho 61-2439, the amount of the chlorine agent must be less than 0.07 mg / l in order to prevent the formation of trihalomethanes. The effect of inhibiting the growth and adhesion of marine organisms to marine organisms cannot be expected. Therefore, especially for bivalves such as mussels, the inhibitory effect is small unless hydrogen peroxide is used in an amount of 2 mg / l or more.

[0012] Despite its low concentration, a cooling water system that uses a large amount of seawater, such as a thermal power plant or a nuclear power plant, has a problem that it is not economical because the amount of use is enormous. Challenge 3). Therefore, an object of the present invention is to solve the above technical problems 1 to 3, that is, while suppressing the generation of trihalomethanes and reducing the amount of the hydrogen peroxide agent, the addition site and subsequent An object of the present invention is to provide a method for treating industrial seawater cooling water, which effectively suppresses the attachment and growth of marine organisms not only in a partial area but also in an area thereafter.

[0013]

Means for Solving the Problems In view of this situation and recognition, the present inventors have conducted intensive studies on the method and amounts of hydrogen peroxide and chlorine agents and the generation mechanism of trihalomethanes to achieve the above object. As a result, when a small amount of a hydrogen peroxide agent is added in advance, and a specific ratio and a specific amount of a chlorine agent are added to seawater in which hydrogen peroxide is dispersed by applying diffusion means to the hydrogen peroxide addition amount. Experimentally found that trihalomethanes were not substantially produced (Examples 1 to 3).
15 and Comparative Examples 1, 2, 3, and 9).

The fact based on this experimental confirmation is that even when a specific ratio and a specific amount of a chlorine agent are added to the amount of hydrogen peroxide added, the intermittent addition method, the simultaneous addition method 2, If the method of adding hydrogen peroxide to seawater in which chlorinating agents are dispersed by applying diffusion means is adopted, it is considered to be a surprising fact that trihalomethanes are not expected from the fact that trihalomethanes are generated (comparison Examples 5-7).

Further, in the present invention, even when the amount of the hydrogen peroxide agent is reduced to less than 2 mg / l, the effect of inhibiting the adhesion of marine organisms and the growth inhibition (particularly mussels, etc.) is reduced by the combined use with the chlorine agent. Was confirmed by experiments (see Examples 21 to 24). further,
It was also confirmed that the effect was not reduced not only at the addition site and a partial area thereafter, but also at the subsequent sites (see Examples 16 to 20).

That is, if the concentration of hydrogen peroxide is low,
Although a high concentration of the chlorine agent should be required, the present invention has an effect of suppressing the adhesion of marine organisms by using a low concentration of the hydrogen peroxide agent which does not generate trihalomethanes as the chlorine agent. That is surprising. Further study these facts,
Upon confirmation, the present invention has been completed. Thus, according to the present invention, seawater in which hydrogen peroxide or a hydrogen peroxide generator is dispersed in an industrial seawater cooling water system in advance to a concentration of 0.01 to 2 mg / l (as hydrogen peroxide). It is characterized by adding chlorine gas or an effective chlorine generator to the cooling water at a concentration that can prevent the generation of trihalomethanes or lower, to prevent the adhesion of marine organisms or suppress the growth of industrial seawater cooling water systems. And a method for treating industrial seawater cooling water.

The hydrogen peroxide used in the present invention includes:
Those having a concentration of 3 to 60% which are commercially available for industrial use are preferably used. Further, those generated by electrolysis or the like on the spot may be used. Examples of the hydrogen peroxide generator include, for example, perboric acid, percarbonic acid, inorganic peracids such as peroxysulfuric acid, organic peracids such as peracetic acid or salts thereof, and hydrogen peroxide adducts of urea. used.

The chlorine agent used in the present invention includes chlorine gas, hypochlorite, dichloroisocyanurate, and other compounds that generate effective chlorine in seawater, and hypochlorous acid obtained by electrolysis of seawater. Salt can be used. In using the agent of the present invention, the agent can be appropriately diluted with seawater or fresh water and added.

In the present invention, a hydrogen peroxide agent is added to an industrial seawater cooling water system in advance in an amount of 0.01 to 2 mg / l, preferably 0.1 to 1.8 mg / l, more preferably 0.3 to 1.5 mg / l.
mg / l (but as hydrogen peroxide), and preferably chlorine or an effective chlorine generator is added to the dispersed seawater cooling water by subjecting it to a diffusion means at a concentration capable of preventing the formation of trihalomethanes or lower. It must be added at a concentration.

The concentration of the hydrogen peroxide added is 0.01 mg / l
If it is less than this, not only the effect of inhibiting adhesion or growth to marine organisms becomes insufficient, but also a chlorine agent added later and bromine ions in seawater react to generate trihalomethanes. It is not preferable because the object of the invention cannot be achieved. Further, when the concentration of the hydrogen peroxide added becomes 2 mg / l or more as hydrogen peroxide, the oxidation-reduction reaction with the chlorine agent added later rapidly proceeds, and the effective agent is consumed. It is not preferable because the growth suppressing effect cannot be sufficiently maintained.

In the present invention, the concentration of the chlorine agent added is 0.03 to 0.8 mol, preferably 0.05 to 0.6 mol, as effective chlorine per mol of hydrogen peroxide used.
At a concentration corresponding to 0.1 mol / mol, and 0.01 to 1.0 mg / l, preferably 0.0
The concentration ranges from 2 to 0.8 mg / l. Where available chlorine 1
The mole refers to an amount equivalent to the same oxidation equivalent as 1 mole of chlorine, and 1 mg of available chlorine refers to an amount corresponding to the same oxidation equivalent as 1 mg of chlorine.

The lower limit of the concentration of the chlorine agent to be added is less than a concentration corresponding to 0.03 mol as effective chlorine per mol of hydrogen peroxide used (see Comparative Examples 21 and 28), or seawater cooling. 0.01 as available chlorine for water
When the amount is less than mg / l, the effect of inhibiting the attachment and growth of marine organisms is insufficient, which is not preferable. In addition, the upper limit of the concentration of the chlorine agent added is higher than the concentration equivalent to 0.8 mol as effective chlorine per mol of hydrogen peroxide used, or 1.0 mg as effective chlorine with respect to seawater cooling water. /
If it is more than 1, the chlorine agent reacts with bromide ions in seawater to produce trihalomethanes, which is not preferable (see Comparative Examples 1 to 3 and 9).

In the present invention, the term "diffusion means" refers to a physical means for stirring seawater so that hydrogen peroxide in seawater quickly becomes substantially uniform in concentration. Specifically, installation of a diffuser having the shape shown in FIGS. 1 and 3, installation of a stirrer, installation of a so-called “jama plate” in a pipe or at an intake, and the like can be mentioned. In the industrial seawater cooling water system, there is a portion corresponding to the diffusion means of the present invention, and a hydrogen peroxide agent can be added before that, and a chlorine agent can be added after that.

More specifically, for example, it is necessary to preliminarily connect (a) the tip of the intake port of the industrial seawater cooling water system, (b) the upstream side of the bar screen, and (c) the upstream pipe of the water feed pump or the pressure pump. Add a hydrogen oxide agent, and at a suitable place downstream of it,
For example, corresponding to the above (a) seawater pump pit,
A method of adding a chlorine agent to (b) the downstream side of the bar screen, (c) the downstream side pipe of the water supply pump or the pressure pump, or the like.

The effect of the present invention is that the amounts of the hydrogen peroxide agent and the chlorine agent can be substantially reduced, and harmful trihalomethanes are not produced as by-products. Treatment, that is, adhesion of marine organisms such as bivalves such as mussels and green mussels, hydroptera such as barnacles and winged hydra, bryozoans and scuttlefishes, and the growth of marine organisms attached to the walls of the seawater cooling water system can be suppressed.

In particular, it is possible to effectively attach and suppress the growth of bivalves such as mussels, which had been difficult to control with a low addition amount.

[0027]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples.
FIGS. 1 to 4 are conceptual diagrams for explaining Examples or Comparative Examples.

Examples 1 to 15 A 35% hydrogen peroxide solution as a hydrogen peroxide agent and a sodium hypochlorite solution (containing 5% as available chlorine) as an available chlorine generator were added to seawater according to the method of the present invention. The amount of trihalomethanes generated in seawater when added was confirmed by the following experiment.

(Experimental method) 1 l of seawater in a 1 l beaker
Was added and a predetermined amount of a hydrogen peroxide agent was added in advance while stirring with a stirrer, and a predetermined amount of a chlorine agent was added after 10 to 300 seconds. Thereafter, the amount of trihalomethanes generated in the seawater after a lapse of 60 minutes under stirring with a stirrer was determined according to JIS:
It was measured according to K-0125 (1990) [Test method for low molecular weight halogenated hydrocarbons in water and wastewater]. Table 1 shows the results. In this experiment, it was confirmed that the hydrogen peroxide agent added in advance under stirring with a stirrer was maintained at a uniform concentration after 10 seconds.

(Consideration) As is clear from the test results, 0.175 to 1.75 mg / l of hydrogen peroxide solution as hydrogen peroxide was added, and a seawater uniformly dispersed and maintained by a diffusion means using a stirrer. By adding a chlorine agent as available chlorine to a concentration of 0.05 to 0.55 mol per mol of hydrogen peroxide and 0.07 to 0.5 mg / l in seawater, trihalomethanes can be substantially reduced. It can be seen that it is not detected.

Comparative Examples 1 to 20 A method of the present invention was prepared by adding a 35% hydrogen peroxide solution as a hydrogen peroxide agent and a sodium hypochlorite solution (containing 5% as available chlorine) as an effective chlorine generator in seawater. The production amount of trihalomethanes in seawater when added without using was confirmed by the following experiment.

(Experimental method) Based on Examples 1 to 15. However, in Comparative Examples 5, 6 and 7, a chlorine agent was added in advance with stirring with a stirrer, and after a predetermined time had elapsed, a hydrogen peroxide agent was added. In Comparative Examples 4, 8 and 10, both ends of the beaker were similarly stirred. , A hydrogen peroxide agent and a chlorine agent were simultaneously added, and in Comparative Examples 11 to 19, only the chlorine agent or the hydrogen peroxide agent was added. The results are shown in Tables 1 and 2.

[0033]

[Table 1]

[0034]

[Table 2]

(Consideration) As is apparent from the test results, 0.35 to 2.0 mg / l of a hydrogen peroxide solution was added as hydrogen peroxide, and a seawater uniformly dispersed and maintained by a diffusion means using a stirrer. When a chlorine agent is added as effective chlorine to a concentration of at least 1 mol per mol of hydrogen peroxide or 1 mg / l or more in seawater (Comparative Examples 1 to 3 and 9), the amount of the chlorine agent added to the present invention , The chlorine agent is added first (Comparative Examples 5 to 7), or the hydrogen peroxide agent and the chlorine agent are added simultaneously (Comparative Examples 4, 8 and 1).
0) shows that trihalomethanes, especially tribromomethanes, are produced in large amounts.

Examples 16 to 20 and Comparative Examples 21 to 27 Using a 35% hydrogen peroxide solution as a hydrogen peroxide agent and a sodium hypochlorite solution (containing 12% as available chlorine) as an available chlorine generator, In order to investigate the degree of growth of mussels due to the combined use of both agents, a model waterway shown in FIGS. 1 and 2 was prepared using a vinyl chloride pipe (vinyl chloride pipe) having an inner diameter of 65 mm and a length of 50 m. Seawater was passed through the waterway from left to right on the PVC pipes.

In the model waterway of FIG. 1, the seawater introduction part of the PVC pipe and two pipes (inner diameter 25 mm) on the way are made thinner, and injection points for the chemicals are provided here, respectively, and between the injection points. A diffuser was provided. The diffuser was designed to disperse the hydrogen peroxide added to the injection point. In the model channel shown in FIG. 2, the inner diameter of the pipe only at the seawater introduction portion is reduced (inner diameter: 25 mm), and injection points are provided at the top, bottom, left and right of the pipe.

In each of the waterways, 0.5, 4, 8, 16, 24 and 48 are set from the injection point of the medicine (injection point in FIG. 1).
At a position of m, 20 adult mussels whose shell length was measured in advance were put into a plastic basket and inserted into a predetermined portion of each waterway, and about 1 m ³ / h of seawater was passed through in a transient manner to obtain 40 m
Tested for days. A hydrogen peroxide agent was added to the injection point of the model waterway, and a chlorine agent was added to the injection point by a chemical pump so as to have a predetermined concentration.

After the test was completed, the shell length of the mussel was measured, and the degree of growth was determined from the difference in the shell length before and after the test. Examples 16 to 20 use the model waterway of FIG.
Reference numeral 22 denotes the model channel shown in FIG. 1 except that the drug amount is out of the range of the drug amount of the present invention, and Comparative Examples 23 to 26 used the model channel shown in FIG. Tables 3 and 4 show the test conditions and test results.

[0040]

[Table 3]

[0041]

[Table 4]

Examples 21 to 24 and Comparative Examples 28 to 32 Using a 35% hydrogen peroxide solution as a hydrogen peroxide agent and a sodium hypochlorite solution (containing 12% as available chlorine) as an available chlorine generator, In order to investigate the effect of the combined use of these two agents on the marine adherent organisms, a water flow test was conducted using the model waterway shown in FIG. 3 or FIG. 4 for two months from April, which is the attachment period of the mussel. .
The model waterway is a PVC pipe (inner diameter 65) as in FIG.
mm) was used.

A diffuser was installed in the model channel of FIG. 3 in the same manner as in FIG. The diffuser was designed to disperse the hydrogen peroxide added to the injection point. Pumping seawater from the seawater introduction channel of the industrial seawater cooling water of a certain factory using a submersible pump, and about 3 m ³ / h to the model channel of FIG. 3 or 4
Of seawater was passed through in a transient manner and tested for 2 months.

An organism-attached plate (PVC net) is inserted into each model waterway, and the distance from the injection point (injection point in FIG. 3) to the center of the organism-attached plate is 1500 mm. A hydrogen peroxide agent was added to the injection point of the water channel, and a chlorine agent was added to the injection point so as to have a predetermined concentration by a chemical pump. After completion of the test, mussels and other organisms attached to the mussels were measured.

In Examples 21 to 24, the model channel shown in FIG. 3 was used, and in Comparative Examples 28 to 32, the model channel shown in FIG. 4 was used. Table 5 shows the test conditions and test results.

[0046]

[Table 5]

[0047]

According to the method of the present invention, marine marine organisms such as mussels which are difficult to prevent from being adhered can be reliably produced using low-concentration hydrogen peroxide and low-concentration chlorine agents without producing trihalomethanes. Can be controlled.

[Brief description of the drawings]

FIG. 1 is a model waterway for explaining a method (example) of the present invention.

FIG. 2 is a model waterway for explaining a method (comparative example) other than the present invention.

FIG. 3 is a model waterway for explaining a method (example) of the present invention.

FIG. 4 is a model waterway for explaining a method (comparative example) other than the present invention.

[Explanation of symbols]

 Reference Signs List 1 PVC pipe (inner diameter 25 mm) 2 Diffuser 3 PVC pipe (inner diameter 65 mm) 4 Injection point 5 Injection point 6 150 mm 7 50 mm 8 48 m 9 Flange connection part 10 Purple mussel body 11 450 mm 12 1500 mm 13

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C02F 1/50 540 C02F 1/50 540A 540B 550 550H F28F 19/01 F28F 19/00 501B (72) Inventor Shoichiro Kajiwara Ashigara, Kanagawa Prefecture 950 Koriyama-Kitamachi Kishi Sanroku Gas Chemical Co., Ltd. Yamakita Plant (56) References JP-A-54-161592 (JP, A) JP-A-55-132687 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) C02F 1 / 50,1 / 72 F28F 19/00

Claims (2)

(57) [Claims] 1. Hydrogen peroxide or a hydrogen peroxide generator is added to an industrial seawater cooling water system in advance , and hydrogen peroxide is added in an amount of 0.01%.
In a seawater cooling water dispersed to a concentration of about 2 mg / l (as hydrogen peroxide), chlorine gas or an effective chlorine generator is mixed with 0.03 to 0.8 per mol of hydrogen peroxide.
At a concentration equivalent to moles (but available chlorine)
0.01-1.0 mg / l to seawater cooling water
And an effective chlorine (as effective chlorine) at a concentration to prevent the adhesion of marine organisms to the industrial seawater cooling water system or to suppress the growth thereof . 2. The method for treating industrial seawater cooling water according to claim 1 , wherein the marine attached organism is mussel.