JP2010115617A - Method of controlling oxidizing agent concentration, method of controlling water based treating agent concentration using the control method, and method of sterilizing water base - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of precisely controlling concentration of an oxidizing agent in a water base. <P>SOLUTION: The method of controlling the concentration of the oxidizing agent in the water base includes at least: performing a first natural potential measuring step of measuring the natural potential of a metal dipped in the water base; and performing an oxidizing agent generating step of generating the oxidizing agent in the water base. The natural potential of the metal has a positive correlation with the concentration of the oxidizing agent and then, the concentration of the oxidizing agent is controllable in a prescribed range by measuring the natural potential of the metal and keeping the natural potential constant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for controlling an oxidant concentration. More specifically, the present invention relates to a technique for controlling the concentration of an oxidant to perform aqueous sterilization, a method for controlling the concentration of an aqueous treatment agent using the technique, and an aqueous sterilization method.

  In plant cooling water systems, wastewater treatment water systems, steel water systems, paper pulp water systems, cutting oil water systems, etc. in various factories, slime and the like are generated in the water systems due to bacteria, filamentous fungi, algae, and the like. This slime or the like causes troubles such as a decrease in thermal efficiency, blockage of water passage pipes, corrosion of pipe metal materials, and the like.

  In order to prevent such an obstacle, an oxidizing agent such as hypochlorite is used as a slime control agent in a cooling water system or the like. For example, in Patent Document 1, hydrazine is contained in cooling water in the first stage, and (a) hypochlorous acid or a salt thereof, (b) hypobromite or the like, as related to a cooling water-based slime peeling treatment. A technique for containing a salt or the like in cooling water is disclosed.

  In many cases, a combined chlorine agent (stabilized chlorine agent) is used as the chlorine agent. When a combined chlorine agent is used, it remains as a chlorine stabilizer when consumed in the aqueous system. However, the consumption rate of the combined chlorine agent in the water system may vary depending on the cooling water load, the surrounding environment, and the like. Therefore, there is a problem that it is difficult to maintain a stable concentration even if the injection amount of the combined chlorine agent is controlled by a batch timer or a proportion of makeup water.

  As described above, in a system where the consumption amount of bound chlorine is large, the detected concentration in the aqueous system tends to be lower than the actual addition amount. Therefore, in order to ensure an effective detection concentration, the amount of the drug added is increased. However, this increases costs, and the bound chlorine agent consumed in the aqueous system remains in a large amount as a chlorine stabilizer. There was a thing.

JP 2004-012042 A

  In order to solve the above problem, the inventors of the present invention firstly generated free chlorine in the aqueous system as a method for controlling the concentration of the aqueous processing agent that can effectively use the combined chlorine agent, A method for controlling the concentration of an aqueous treatment agent that controls the amount of bound chlorine was found. That is, by generating free chlorine in the aqueous system, it can be combined with the chlorine stabilizer remaining in the aqueous system to form combined chlorine, and as a result, the remaining chlorine stabilizer can be effectively used. It is a method that can be utilized for. At this time, if the concentration of the oxidizing agent such as free chlorine in the aqueous system can be controlled within a certain range, the concentration of the aqueous processing agent can be controlled more accurately and the aqueous system can be efficiently sterilized.

  Thus, the main object of the present invention is to provide a novel method for more accurately controlling the oxidant concentration in the aqueous system.

  As a result of earnest research on the method for controlling the oxidant concentration in the aqueous system, the present inventors have found a method capable of operating the oxidant concentration more accurately by focusing on the natural potential of the metal, and completed the present invention. I came to let you.

That is, in the present invention, first, a first natural potential measuring step for measuring a natural potential of a metal immersed in an aqueous system,
An oxidizing agent generating step for generating an oxidizing agent in the aqueous system based on the natural potential measured in the first natural potential measuring step;
And a method for controlling the oxidant concentration in an aqueous system.
Since the natural potential of the metal has a positive correlation with the oxidant concentration, it is possible to control the oxidant concentration within a predetermined range by measuring the natural potential of the metal and keeping this natural potential constant. is there.
In the control method according to the present invention, before performing the first natural potential measurement step, an analysis step of analyzing a correlation between the natural potential of the metal and the concentration of the oxidizing agent is further performed, and based on this correlation By generating the oxidant, the oxidant concentration can be easily controlled.
The metal used in the control method according to the present invention is not particularly limited as long as it is a metal that does not affect the aqueous treatment, but stainless steel and copper are particularly preferable in the present invention. These may be used alone or in combination.
In addition, a second natural potential measuring step of immersing an electrode made of a metal material other than the metal in the aqueous system and measuring a natural potential of the electrode is performed, and the natural potential of the electrode is combined with the natural potential of the metal. Based on the above, the oxidant concentration can be more accurately controlled by generating the oxidant.
As the metal material used in this case, for example, if the same metal material as the water-based piping material or the component equipment in contact with water is used, it is possible to prevent the corrosion of the component equipment in contact with the pipe or water.
For example, before performing the second natural potential measurement step, a corrosion generation potential measurement step for obtaining the corrosion occurrence potential of the electrode is further performed, and the natural potential of the electrode is maintained at a value lower than the corrosion occurrence potential, thereby the piping material It is possible to prevent corrosion of components that come into contact with water.

The concentration of the aqueous treatment agent can be controlled by accurately controlling the amount of the aqueous oxidant using the method for controlling the oxidant concentration according to the present invention.
At this time, the type of the oxidizing agent to be controlled is not particularly limited as long as it can be used for sterilization of an aqueous system. For example, in the case of a free halogen, the presence of a halogen stabilizer in the aqueous system allows the release Accurate concentration control of the aqueous treatment agent can be realized by combining halogen and a halogen stabilizer to form a combined halogen.
And the aqueous | water-based disinfection is possible by performing exact density | concentration control of an aqueous | water-based processing agent.

  According to the method for controlling the oxidant concentration according to the present invention, the oxidant concentration can be accurately controlled, so that the concentration control of the aqueous treatment agent in the aqueous system can also be accurately performed. As a result, the water system can be efficiently and effectively sterilized.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

  FIG. 1 is a flowchart of an oxidant concentration control method 1 according to the present invention. The oxidant concentration control method according to the present invention is a method of performing at least the first natural potential measurement step 11 and the oxidant generation step 12. Further, if necessary, the analysis step 13, the second natural potential measurement step 14, and the corrosion occurrence potential measurement step 15 can be performed. Hereinafter, each process will be described in detail.

(1) First natural potential measurement step 11
The first natural potential measuring step 11 is a step of measuring the natural potential of the metal immersed in the water system. Since the natural potential of the metal has a positive correlation with the oxidant concentration, the oxidant generation step described later is performed so as to measure the natural potential of the metal in the first natural potential measurement step 11 and keep this natural potential constant. By generating the oxidant, it is possible to control the oxidant concentration within a predetermined range.

  The metal that can be used is not particularly limited as long as it does not affect the aqueous treatment, and one or more known metals can be freely selected and used. For example, stainless steel, copper, gold, platinum, titanium, a copper alloy, a nickel base alloy, and the like can be given. Among these, stainless steel and copper are particularly preferable in the present invention.

  As described above, the natural potential of a metal has a positive correlation with the oxidant concentration, but the reactivity varies depending on the type of metal. For example, as shown in FIG. 2 showing the results of Example 1 described later, copper reacts sensitively to an oxidizing agent such as free chlorine, whereas stainless steel reacts relatively slowly. Therefore, when the change in the oxidant concentration in the aqueous system is gradual, it is possible to control the oxidant concentration based on the natural potential of a moderately reactive metal such as stainless steel. On the other hand, in an aqueous system in which the amplitude of the oxidant concentration varies greatly, a reactive sensitive metal such as copper may be used, or both a reactive sensitive metal and a mild reactive metal may be used in combination. It is valid.

  There is no problem even if one kind of metal is used. However, if the metal reaches a certain potential or more, corrosion of the metal occurs. As a result, the potential drops and it may be difficult to accurately control the oxidant concentration. It is preferable to use a metal. In the present invention, for example, by using a reactive sensitive metal such as copper and a mild reactive metal such as stainless steel, the trend of the oxidant concentration in the aqueous system can be grasped. At the same time, it is possible to detect the occurrence of corrosion of reactive sensitive metals such as copper.

(2) Oxidant generation step 12
The oxidizing agent generating step 12 is a step of generating an oxidizing agent in the water system based on the natural potential measured in the first natural potential measuring step 11. By generating the oxidizing agent in the aqueous system, it can be combined with a predetermined stabilizer remaining in the aqueous system in order to control the aqueous processing agent described later and to sterilize the aqueous system. Thereby, an aqueous processing agent can be regenerated and aqueous sterilization can be performed efficiently and effectively.

  In the oxidizing agent generating step 12, the oxidizing agent is generated based on the measured value of the natural potential measured in the first natural potential measuring step 11. This is because the natural potential of the metal has a positive correlation with the oxidant concentration as described above. For example, if the oxidant is generated / stopped so that the natural potential of the metal immersed in the water system is kept constant, the oxidant concentration in the water system can be kept constant.

  By generating an oxidant based on the measured value of the natural potential of the metal, the oxidant concentration measured by continuously performing polarography, absorptiometry, DPD (N, N-diethylphenylenediamine) method, etc. Compared with the method of generating an oxidant based on the measured value, the measuring instruments are inexpensive, and it is possible to reduce the complexity of supplying the measuring reagent.

  Further, as shown in Example 2 described later, the natural potential of the metal is highly stable in the measured value with respect to the oxidant concentration. Therefore, by generating the oxidant based on the measured value of the natural potential of the metal, Compared to the method of generating an oxidant based on the measured value of Oxidation-reduction Potential (ORP), it is possible to manage the oxidant stably over a long period of time.

  In addition, as long as the control of the oxidant concentration is performed based on the measured value of the natural potential of the metal, it is included in the present invention, and for more certainty, polarography, absorptiometry, DPD (N, N It is also possible to use a method of controlling the oxidant concentration based on the measured value of the oxidant concentration by the -diethylphenylenediamine) method or the measured value of the oxidation-reduction potential.

  In the present invention, the type of oxidizing agent to be generated in the aqueous system is not particularly limited, and any oxidizing agent that is effective for aqueous sterilization can be selected and generated. For example, free halogen, ozone, hydrogen peroxide, etc. can be mentioned. Of these, free halogen is particularly preferred in the present invention. This is because by combining with a halogen stabilizer present in the aqueous system to form a combined halogen, the aqueous processing agent can be regenerated and the aqueous system can be sterilized efficiently and effectively. As a specific example of the free halogen, free chlorine can be preferably used in the present invention.

  The method for generating the oxidizing agent in the aqueous system is not particularly limited, and a known method can be freely selected and used. For example, a method of injecting a drug into an aqueous system, a method of generating an oxidizing agent such as hypochlorite ion using an electrolytic reaction such as a saline solution or an aqueous potassium chloride solution, and the like can be mentioned.

  As a specific example, as a drug that can be used when generating free chlorine, which is one of the oxidizing agents, by chemical injection, hypochlorous acid or a salt thereof, chlorous acid or a salt thereof, chloric acid or The salt, perchloric acid or its salt, chlorinated isocyanuric acid or its salt, chlorine gas, chlorine dioxide, etc. are mentioned. More specific salts include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite, and alkaline earth metal hypochlorites such as calcium hypochlorite and barium hypochlorite. Salts, alkali metal chlorites such as sodium chlorite and potassium chlorite, alkaline earth metal chlorites such as calcium chlorite and barium chlorite, and other chlorites such as nickel chlorite Examples include acid metal salts, alkali metal chlorates such as ammonium chlorate, sodium chlorate and potassium chlorate, and alkaline earth metal chlorates such as calcium chlorate and barium chlorate.

  These chlorine-based oxidizing agents may be used alone or in combination of two or more. In the present invention, among these, hypochlorite can be preferably used from the viewpoint of easy handling.

  For example, when free chlorine is generated as an oxidizing agent, the lower limit of the suitable free chlorine concentration in the aqueous system is 0.05 mg-Cl / L or more, more preferably 0.1 mg-Cl / L or more, Preferably it is 0.4 mg-Cl / L or more. By setting it as this free chlorine density | concentration, it can couple | bond more efficiently with the chlorine stabilizer which remains in an aqueous system for control of the aqueous processing agent mentioned later and aqueous | water-based disinfection. As a result, bound chlorine can be regenerated more efficiently, and aqueous sterilization can be performed efficiently and effectively. On the other hand, the upper limit value of the free chlorine concentration is preferably 5 mg-Cl / L or less, more preferably 1 mg-Cl / L or less, from the viewpoint of preventing corrosion of metals in the aqueous system.

(3) Analysis step 13
The analysis step 13 is a step of analyzing the correlation between the natural potential of the metal and the concentration of the oxidizing agent before performing the first natural potential measurement step 11. Based on this correlation, the oxidant concentration can be easily controlled by generating the oxidant in the oxidant generation step 12.

  Although the specific value of the natural potential varies depending on the aqueous system and the metal used, for example, in the case of Example 1 described later, the natural potential of stainless steel for maintaining the free chlorine concentration at about 0.8 mg / L is 33 to It can be seen that 35 mV and the natural potential of copper is 140 to 160 mV. By obtaining this correlation in advance, it is possible to save the trouble of periodically monitoring the concentration of an oxidizing agent such as free chlorine.

(4) Second natural potential measurement step 14
The second natural potential measuring step 14 is a step of immersing an electrode made of a metal material different from the metal used in the first natural potential measuring step in the aqueous system, and measuring the natural potential of the electrode. In addition to the natural potential of the metal used in the first natural potential measurement step, the oxidizing agent concentration can be controlled more accurately by generating the oxidizing agent based on the natural potential of the electrode.

  The metal material to be used can be freely selected and used as long as it is a metal material different from the metal used in the first natural potential measurement step and does not affect the aqueous treatment. For example, the same metal material as the water-based piping material or the component equipment in contact with water can be suitably used. This is because it is possible to control the oxidant concentration in consideration of the influence on the constituent materials in contact with the piping material and water.

  For example, stainless steel, carbon steel, titanium, copper, copper alloys, and other metals are often used for water-based piping materials or components that come into contact with water, but depending on the type of piping materials and components used By using the electrodes made of the same metal material, it becomes possible to control the oxidant concentration taking into account the influence of the occurrence of corrosion of the piping material and the component equipment.

  In the present invention, the residual natural oxidant concentration is maintained within a certain range by performing the second natural potential measurement step 14 and generating the oxidant based on the natural potential of the same metal electrode as that of the piping material and the component equipment. Compared with control that focuses only on this, it is possible to reliably prevent exceeding the potential at which the piping material and components are affected.

(5) Corrosion occurrence potential measurement step 15
The corrosion occurrence potential measurement step 15 is a step of obtaining the corrosion occurrence potential of the electrode before performing the second natural potential measurement step 14. By keeping the natural potential of the electrode at a value lower than the corrosion occurrence potential, it is possible to prevent corrosion of the component equipment that comes into contact with the piping material or water.

  In the present invention, the corrosion occurrence potential measurement step 15 is performed, and an oxidant is generated so as to keep the natural potential of the electrode at a value lower than the corrosion occurrence potential of the same metal electrode as that of the piping material or component equipment, thereby remaining. Compared to control that focuses only on maintaining the oxidant concentration within a certain range, corrosion of piping materials and components can be reliably prevented.

  By using the oxidant concentration control method according to the present invention described above, the amount of the aqueous oxidant is accurately controlled, so that the concentration of the aqueous treatment agent can be accurately controlled. A predetermined stabilizer (for example, a chlorine stabilizer) can be generated by depleting an aqueous treatment agent (for example, bonded chlorine) in the aqueous system. In the present invention, an oxidizing agent (for example, free chlorine) is added to the By reacting with a stabilizer (for example, chlorine stabilizer), it can be regenerated as an aqueous treatment agent (for example, combined chlorine). A predetermined stabilizer (for example, a chlorine stabilizer) remaining in an aqueous system is combined with an oxidizing agent (for example, free chlorine) to become an aqueous processing agent such as combined chlorine, but an excess is an oxidizing agent ( For example, it will be present in the water system as free chlorine). By accurately controlling the concentration of this oxidizing agent (for example, free chlorine) within a certain range, it is possible to efficiently regenerate the aqueous processing agent (for example, bound chlorine), and to accurately control the concentration of the aqueous processing agent. Can be realized. This makes it possible to effectively use various stabilizers present in the aqueous system.

  The present invention also applies to the case where a predetermined stabilizer such as a chlorine stabilizer and an oxidizing agent such as free chlorine are added to an aqueous system to generate an aqueous treatment agent such as bound chlorine in the aqueous system. It is possible to apply such a method for controlling the oxidant concentration.

  Moreover, if the method for controlling the concentration of the oxidant according to the present invention is used, the amount of the aqueous aqueous treatment agent can be accurately controlled, so that the amount of the chemical added can be reduced. In particular, when a multi-drug is used as an aqueous treatment agent, it is possible to prevent excessive injection or excessive residual of other components due to an increase in the amount of drug added.

  In the method for controlling the concentration of an aqueous processing agent according to the present invention, the aqueous processing agent can be generated by combining a predetermined stabilizer and an oxidizing agent. The kind of aqueous treatment agent that can be used in the present invention is not limited, and one or more aqueous treatment agents that can be used for aqueous treatment can be freely selected and used. For example, when combined chlorine is used as an aqueous treatment agent, the types thereof include chloramine-T (sodium salt of N-chloro-4-methylbenzenesulfonamide), chloramine-B (sodium salt of N-chloro-benzenesulfonamide). ), Sodium salt of N-chloro-paranitrobenzenesulfonamide, trichloromelamine, sodium salt or potassium salt of mono- or di-chloromelamine, sodium salt or potassium salt of trichloro-isocyanurate, mono- or di-chloroisocyanuric acid Salt, sodium salt or potassium salt of mono- or di-chlorosulfamic acid, monochlorohydantoin or 1,3-dichlorohydantoin or 5,5-alkyl derivatives thereof.

  When combined chlorine is used as an aqueous treatment agent, the type of chlorine stabilizer that can be used to generate combined chlorine is not limited, and one or more agents having a chlorine stabilizing effect can be freely selected. Can be used. Examples thereof include sulfamic acid and hydantoin. In the present invention, it is particularly preferable to use a sulfamic acid compound among them. This is because it is safer than hydrazine.

  Examples of such sulfamic acid compounds include N-methylsulfamic acid, N, N-dimethylsulfamic acid, N-phenylsulfamic acid and the like. Among the sulfamic acid compounds used in the present invention, examples of the salt of the compound include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, strontium salt and barium salt, manganese salt, copper Other metal salts such as salts, zinc salts, iron salts, cobalt salts, nickel salts, ammonium salts, guanidine salts, etc., specifically, sodium sulfamate, potassium sulfamate, calcium sulfamate, sulfamine Examples include strontium acid, barium sulfamate, iron sulfamate, and zinc sulfamate. The sulfamic acid and these sulfamic acid salts can be used alone or in combination of two or more.

  For example, when free chlorine and sulfamic acid coexist in an aqueous system, they can be combined in the aqueous system to become a chlorosulfamic acid compound and regenerated as bound chlorine. For example, when a chlorinated oxidant and a sulfamic acid compound, or a chlorosulfamic acid-based combined chlorinating agent composed of a chlorinated oxidant and a sulfamic acid compound are coexisted in the water to be treated, a wide pH range covering an acidic range to an alkaline range. Even so, there is a feature that the free chlorine concentration in the water to be treated does not change greatly.

  In addition, for example, when bound chlorine is generated as an aqueous treatment agent, the preferred lower bound value of the bound chlorine concentration in the aqueous system is preferably 0.1 mg-Cl / L or more, and the upper limit value is 50 mg-Cl. / L or less is preferable. The bound chlorine concentration in this case can be measured by the DPD method.

  As described above, according to the method for controlling the oxidant concentration according to the present invention, the oxidant concentration can be accurately controlled. Therefore, the concentration control of the aqueous treatment agent based on the amount of the oxidant in the aqueous system is also possible. Can be done accurately. As a result, the water system can be efficiently and effectively sterilized.

  The water system to which the sterilization method according to the present invention can be applied is not particularly limited, and examples thereof include plant cooling water systems, scrubbers, waste water treatment water systems, waste water treatment water systems, steel water systems, cutting oil water systems, and the like of various factories. In addition, it is possible to efficiently and effectively perform the prevention of slime adhesion to the water passage piping or the like, and the peeling of the slime constituents attached to the apparatus, the water passage piping and the like.

  As an aqueous system, it can use suitably for a circulating water system. When the circulating water system is operated for a long period of time, a stabilizer such as a chlorine stabilizer tends to remain in the water system in a large amount, but according to the present invention, the aqueous processing agent is efficiently regenerated from various stabilizers. This is preferable. Furthermore, an open circulating cooling water system or the like is suitable. For example, bacteria such as Legionella bacteria are liable to be generated in an aqueous system under such conditions because the water temperature of an open circulation cooling tower or the like, particularly an environment surrounded by algae generated in the cooling tower, is preferred. However, if the sterilization method according to the present invention is used, it is possible to sterilize the water system efficiently, effectively, and in the long term, especially for the open circulation cooling water system.

  Hereinafter, the present invention will be described in more detail based on examples, and effects of the present invention will be verified. In addition, the Example demonstrated below shows an example of the typical Example of this invention, and, thereby, the range of this invention is not interpreted narrowly.

  In Example 1, the correlation between the natural potential of the metal immersed in the aqueous system and the oxidant concentration was examined, and the oxidant concentration was controlled based on the natural potential of the metal. In this example, free chlorine was used as an example of the oxidizing agent, and stainless steel and copper were used as examples of the metal.

  Stainless steel and copper were immersed in an open cooling water system, and free effective chlorine was added while measuring the natural potential.

  For the rapid change in concentration immediately after the injection of free chlorine, the addition of free chlorine is controlled based on the spontaneous potential of copper, which shows a sensitive reaction, and for the subsequent slow reaction, the natural potential of stainless steel is controlled. Based on the results, the addition of free chlorine was controlled.

The results are shown in FIG.
As shown in FIG. 2, it was found that the natural potential of stainless steel and copper correlates with the free chlorine concentration.

  In addition, regarding the abrupt part of the concentration change immediately after the free chlorine injection, the free chlorine concentration can be controlled based on the natural potential of copper showing a sensitive reaction, and the subsequent slow reaction part is made of stainless steel. It was found that the concentration of free chlorine can be controlled based on the natural potential. Furthermore, it was found that the natural potential of stainless steel for maintaining the free chlorine concentration at about 0.8 mg / L was 33 to 35 mV, and the natural potential of copper was 140 to 160 mV.

  From the results of Example 1, it was found that the natural potential of the metal has a correlation with the oxidant concentration, and that the oxidant concentration can be controlled based on the natural potential of the metal. It was also found that the concentration of the oxidant can be accurately controlled even in an aqueous system in which the oxidant concentration change is not constant by devising the metal to be used.

  In Example 2, the change in the natural potential of the metal with respect to the oxidant concentration in the aqueous system was examined. In this example, as in Example 1, free chlorine was used as an example of the oxidizing agent, and stainless steel and copper were used as examples of the metal.

  An electrode made of stainless steel and an electrode made of copper were immersed in a beaker to which a constant concentration of free chlorine was added, and the change with time of each potential was measured. At the same time, the oxidation-reduction potential (ORP) in the aqueous system was also measured using a silver-chloride electrode (Ag-AgCl electrode).

The results are shown in Table 1.

  As shown in Table 1, compared to the redox potential (ORP) with respect to the free chlorine concentration, the natural potential of stainless steel and the natural potential of copper with respect to the free chlorine concentration resulted in higher stability.

  From the result of Example 2, since the stability of the metal natural potential with respect to the oxidant concentration is higher than the oxidation-reduction potential (ORP) with respect to the oxidant concentration, the oxidant concentration can be obtained by using the metal natural potential. It was found that the oxidant concentration can be controlled stably over the long term.

It is a flowchart of the control method 1 of the oxidizing agent density | concentration which concerns on this invention. In Example 1, it is a drawing substitute graph which shows the measurement result of the natural potential of stainless steel and copper, and the measurement result of the free chlorine concentration in an aqueous system.

Explanation of symbols

1 Control method 1 of oxidant concentration
11 First natural potential measurement step 12 Oxidant generation step 13 Analysis step 14 Second natural potential measurement step 15 Corrosion occurrence potential measurement step

Claims (9)

A first natural potential measurement step for measuring a natural potential of a metal immersed in an aqueous system;
An oxidizing agent generating step for generating an oxidizing agent in the aqueous system based on the natural potential measured in the first natural potential measuring step;
A method of controlling the oxidant concentration in an aqueous system at least. Before performing the first natural potential measurement step, further performing an analysis step of analyzing the correlation between the natural potential of the metal and the concentration of the oxidizing agent,
The method for controlling an oxidant concentration according to claim 1, wherein, in the oxidant generation step, an oxidant is generated in the water system based on the correlation.   The method for controlling an oxidant concentration according to claim 1, wherein the metal is stainless steel and / or copper. An electrode made of a metal material different from the metal is immersed in the aqueous system, and a second natural potential measurement step for measuring the natural potential of the electrode is further performed.
The method for controlling an oxidant concentration according to any one of claims 1 to 3, wherein, in the oxidant generation step, an oxidant is generated in the water system based on the natural potential measured in the second natural potential measurement step. .   5. The method for controlling an oxidant concentration according to claim 4, wherein the metal material is the same metal material as the water-based piping material or a component device in contact with water. Before performing the second natural potential measurement step, further perform a corrosion occurrence potential measurement step for obtaining the corrosion occurrence potential of the electrode,
The method for controlling an oxidant concentration according to claim 4 or 5, wherein, in the oxidant generation step, an oxidant is generated in the water system based on the corrosion occurrence potential measured in the corrosion occurrence potential measurement step.   A method for controlling the concentration of an aqueous treatment agent, wherein the amount of the aqueous aqueous treatment agent is controlled using the method for controlling an oxidant concentration according to any one of claims 1 to 6.   The method for controlling the concentration of an aqueous treatment agent according to claim 7, wherein the oxidizing agent is free halogen and a halogen stabilizer is present in the aqueous system.   A method for sterilizing an aqueous system using the concentration control method for an aqueous processing agent according to claim 7 or 8.