WO2019230757A1

WO2019230757A1 - Initial treatment agent for circulating cooling water and method for preventing corrosion in circulating cooling water system

Info

Publication number: WO2019230757A1
Application number: PCT/JP2019/021219
Authority: WO
Inventors: 藤田　和久; 健吾渡辺
Original assignee: 栗田工業株式会社
Priority date: 2018-05-30
Filing date: 2019-05-29
Publication date: 2019-12-05

Abstract

The initial treatment agent according to the present invention for circulating cooling water is one that is to be added to a circulating cooling water system at the time of startup thereof in order to form an anticorrosion film on the surface of metallic members of said water system, and that contains at least one member selected from among tartaric acid and tartaric acid salts.

Description

Initial treatment agent for circulating cooling water and method for preventing corrosion of circulating cooling water system

The present invention relates to an initial treatment agent for circulating cooling water that is added to the aqueous system at the time of starting the circulating cooling water system to form an anticorrosive film on the surface of the metallic member of the aqueous system, and a method for preventing corrosion of the circulating cooling water system.

The cooling water used in the circulating cooling water system contains impurities (such as dissolved oxygen, chloride ions, sulfate ions, etc.) that become a corrosive factor. The problem is that troubles such as corrosion occur.

For this reason, as an initial treatment process at the start of the circulating cooling water system, an anticorrosive film is formed on the surface of the metal member by adding inorganic phosphate and zinc compound to the cooling water and circulating the cooling water for a certain period of time. Thus, an initial treatment method for a circulating cooling water system has been proposed to obtain a corrosion prevention effect.

For example, in Patent Document 1, a phosphate is added to a cooling water system so that the total phosphoric acid concentration is 70 to 120 mg PO ₄ / L, and a zinc compound is added so that the zinc concentration is 10 to 30 mg Zn / L. A cooling water treatment method is disclosed in which a basic treatment step of adding and forming an initial anticorrosion film on the surface of a cooling water metal member is disclosed.

JP 2011-202243 A

In the cooling water treatment method disclosed in Patent Document 1, a phosphate and a zinc compound are used as an initial treatment agent used for forming a corrosion protection film on the surface of a metal member, and a corrosion prevention effect is obtained. . However, in recent years, due to increasing interest in the water quality environment, it has also been desired to reduce the amount of phosphorus and zinc contained in sewage and waste liquid discharged from factories and offices.

Therefore, the present invention has been made to solve the above-described problems, and can satisfactorily form an anticorrosion film on the surface of a metal member without using a phosphate and a zinc compound as an initial treatment agent. An object of the present invention is to provide an initial treatment agent for circulating cooling water and an anticorrosion method for circulating cooling water, which can provide an excellent corrosion prevention effect.

As a result of intensive studies to solve the above problems, the present inventor added a specific initial treatment agent to a water system in a specific amount (20 to 150 mg / L, preferably 30 to 100 mg / L in terms of tartaric acid), It has been found that the above problems can be solved by setting the pH of the aqueous system after adding the initial treating agent to a specific range (pH 6.0 to 8.0), and the present invention has been completed.
That is, the present invention is as follows.

[1] An initial treatment agent for circulating cooling water which is added to the aqueous system at the time of starting the circulating cooling water system to form an anticorrosive film on the surface of the metallic member of the aqueous system, and is at least 1 selected from tartaric acid and tartrate An initial treatment agent for circulating cooling water containing seeds.
[2] The circulating cooling water use according to [1], wherein the content of at least one selected from tartaric acid and tartrate is 90 to 100% by mass in 100% by mass of the initial processing agent for circulating cooling water. Initial treatment agent.
[3] A method for preventing corrosion of a circulating cooling water system including an initial treatment step of forming an anticorrosive film on the surface of a metallic member of the aqueous system when the circulating cooling water system is started up. An initial treatment agent for circulating cooling water containing at least one selected from the tartaric acid and tartrate salt according to [1] or [2] is added so as to be 20 to 150 mg / L in terms of tartaric acid, and the circulating cooling water A method for preventing corrosion of a circulating cooling water system, wherein the pH of the aqueous system after adding the initial treating agent is 6.0 to 8.0.
[4] The method for preventing corrosion of the circulating cooling water system according to the above [3], wherein the initial treatment agent for circulating cooling water comprises at least one selected from tartaric acid and tartrate.
[5] The method for preventing corrosion of a circulating cooling water system according to the above [3] or [4], wherein in the initial treatment step, the water system is circulated for 20 to 48 hours without applying a heat load to the water system.
[6] In the initial treatment step, an initial treatment agent for circulating cooling water containing at least one selected from the tartaric acid and tartrate is added to the aqueous system so as to be 30 to 100 mg / L in terms of tartaric acid, The method for preventing corrosion of the circulating cooling water system according to any one of [3] to [5] above, wherein the pH of the aqueous system after adding the initial treatment agent for circulating cooling water is 6.0 to 8.0. .
[7] Corrosion of the circulating cooling water system according to any one of [3] to [6], wherein in the initial treatment step, the temperature of the aqueous system is 10 to 40 ° C. and the aqueous system is circulated for 20 to 48 hours. Prevention method.
[8] The circulating cooling water system according to any one of [3] to [7], including a normal operation step for holding the anticorrosion film formed in the initial treatment step after the initial treatment step. Corrosion prevention method.
[9] The method for preventing corrosion of the circulating cooling water system according to [8], wherein a retention treatment agent is added to the aqueous system after the initial treatment process in the normal operation process.
[10] The circulating cooling water system according to [8] or [9], wherein in the normal operation step, the retention treatment agent is added to the aqueous system after the initial treatment step so as to be 20 to 100 mg / L. Corrosion prevention method.

According to the present invention, it is possible to satisfactorily form an anticorrosion film on the surface of a metal member without using a phosphate and a zinc compound as an initial treatment agent, and an excellent corrosion prevention effect can be obtained. A treatment agent and a method for preventing corrosion of a cooling water system can be provided.

It is a figure which shows the change of the corrosion rate measured with time in the initial treatment process and the corrosion treatment process of Examples A1 to A3 and Comparative Examples A1 to A9. In Example B1 and Comparative Examples B1 and B2, the initial treatment step and the blank treatment step are taken as one set, and this set is repeated three times, and shows the change in corrosion weight loss measured over time. It is a schematic diagram which shows the structure of a heat-transfer surface evaluation test apparatus.

[Initial treatment agent for circulating cooling water]
An initial treatment agent for circulating cooling water (hereinafter referred to as “initial treating agent”) of the present invention is added to the aqueous system at the time of starting the circulating cooling water system, and is used for forming an anticorrosive film on the surface of the metallic member of the aqueous system. An initial treatment agent for cooling water, containing at least one selected from tartaric acid and tartrate.
Thereby, even if it does not use a phosphate and a zinc compound as an initial treatment agent, an anticorrosion film can be satisfactorily formed on the metal member surface, and an excellent corrosion prevention effect can be obtained.

(Tartaric acid and tartrate)
The initial treating agent of the present invention contains at least one selected from tartaric acid and tartrate.
The content of at least one selected from tartaric acid and tartrate is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass, in 100% by mass of the initial treatment agent. More preferably, it is 95 to 100% by mass, and still more preferably 100% by mass.
Here, “the content of at least one selected from tartaric acid and tartrate” means the total content of tartaric acid and tartrate in the initial treatment agent.
The content of at least one selected from the above tartaric acid and tartrate is in the above range, so that an anticorrosion film can be satisfactorily formed on the metal member surface without using a phosphate and a zinc compound as an initial treatment agent. It is easy to be obtained and an excellent corrosion prevention effect is easily obtained.

Tartaric acid used in the present invention is also referred to as 2,3-dihydroxybutanedioic acid, and is represented by (CH (OH) COOH) _{2 in the} formula, and refers to a hydroxy acid having two asymmetric carbons in the molecule. .
Tartaric acid includes L-form, D-form, meso-form and racemic form, but is not particularly limited.

The tartrate used in the present invention has tartaric acid in which at least one hydrogen atom selected from two hydrogen atoms of two OH groups in the tartaric acid molecule and two hydrogen atoms of two COOH groups in the tartaric acid molecule is used. This refers to a compound produced by the reaction of tartaric acid, which is ionized from the anion and reacted with a cation. Tartrate is one of the two OH groups and two COOH groups in the tartaric acid molecule. One or two hydrogen atoms of the COOH group are ionized from tartaric acid, and the tartaric acid that has become an anion reacts with the cation. The compound produced is preferred.
Here, examples of the cation include alkali metal ions, alkaline earth metal ions, ammonium ions, zinc ions, aluminum ions, iron ions (II) and the like.

Specific examples of the tartrate formed by ionizing one hydrogen atom from tartaric acid include lithium tartrate, potassium tartrate, sodium tartrate and the like.
Specific examples of tartrate formed by ionizing two or more hydrogen atoms from tartaric acid include dilithium tartrate, potassium sodium tartrate, diammonium tartrate, calcium tartrate, iron (II) tartrate, zinc tartrate and the like. Can be mentioned.
These tartrate salts may be used alone or in combination of two or more.
Among these tartrates, sodium tartrate is preferable as the tartrate formed by ionizing one hydrogen atom from tartaric acid from the viewpoint of satisfactorily forming an anticorrosive film on the metal member surface, and two from tartrate. As the tartrate formed by ionizing the above hydrogen atoms, calcium tartrate and iron (II) tartrate are preferable.

(Other ingredients)
The initial treating agent in the present invention contains at least one selected from tartaric acid and tartrate as an essential component, but may contain other components as long as the object effects of the present invention are not impaired.
Examples of other components include zinc salts and calcium salts.

The content of other components is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and still more preferably 0% by mass in 100% by mass of the initial treating agent.
When the content of the other components is within the above range, an anticorrosion film is easily formed on the metal member surface without using a phosphate and a zinc compound as an initial treatment agent, and excellent corrosion prevention. The effect is easily obtained.

[Corrosion prevention method for circulating cooling water system]
The method for preventing corrosion of a circulating cooling water system according to the present invention (hereinafter referred to as “corrosion preventing method”) includes an initial treatment step of forming an anticorrosive film on the surface of a metal member of the water system when the circulating cooling water system is started. Corrosion prevention method, wherein an initial treatment agent containing at least one selected from tartaric acid and tartrate in an initial treatment step is 20 to 150 mg / L, preferably 30 to 100 mg / L in terms of tartaric acid. The pH of the aqueous system after adding the initial treating agent is adjusted to 6.0 to 8.0.
Thereby, even if it does not use a phosphate and a zinc compound as an initial treatment agent, an anticorrosion film can be satisfactorily formed on the metal member surface, and an excellent corrosion prevention effect can be obtained.

The details of the mechanism by which the excellent anticorrosion effect by the anticorrosion method of the present invention is not clear, but are considered as follows.
An initial treatment agent containing at least one selected from tartaric acid and tartrate is bonded to calcium ions present in water, and an anticorrosion film mainly composed of calcium salt that is hardly soluble in water is formed on the surface of the metal member. It is thought that it is done.
Moreover, it is thought that the initial processing agent containing at least 1 sort (s) chosen from tartaric acid and tartrate reacts with the iron component of a metal member, and iron (II) tartrate is formed.
The formation of such an anticorrosion film prevents an aqueous system containing impurities (for example, dissolved oxygen, chloride ions, sulfate ions, etc.) that are corrosive factors from coming into direct contact with the surface of the metal member, thereby causing corrosion on the surface of the metal member. It is considered that the traveling speed (corrosion speed) can be lowered.

(Initial processing step)
The corrosion prevention method of the present invention includes an initial treatment step of forming an anticorrosion film on the surface of the aqueous metal member when the circulating cooling water system is activated.
In the initial treatment step of the present invention, an initial treatment agent containing at least one selected from tartaric acid and tartrate in an aqueous system is 20 to 150 mg / L, preferably 30 to 100 mg / L, more preferably 40 in terms of tartaric acid. It is added so as to be -90 mg / L, more preferably 50-70 mg / L.
When the addition amount of the initial treatment agent is less than the above range (less than 20 mg / L), the initial treatment agent is too little, so that the anticorrosion film is not sufficiently formed on the surface of the metal member, preventing corrosion. The effect may not be obtained.
On the other hand, when the addition amount of the initial treatment agent exceeds the above range (exceeds 150 mg / L), the initial treatment agent is too much, and inconvenience such as chelate corrosion is likely to occur. The rate at which corrosion proceeds (corrosion rate) may be accelerated.

As described above, the content of at least one selected from tartaric acid and tartrate is more preferably 100% by mass in 100% by mass of the initial treating agent.
That is, the initial treating agent is preferably composed of at least one selected from tartaric acid and tartrate.
In this case, in the aqueous system, at least one selected from tartaric acid and tartrate is preferably 20 to 150 mg / L, more preferably 30 to 100 mg / L, still more preferably 40 to 90 mg / L, and still more preferably, in terms of tartaric acid. Is added so as to be 50 to 70 mg / L.
The addition amount of at least one selected from the above tartaric acid and tartrate is in the above range, so that an anticorrosion film can be satisfactorily formed on the metal member surface without using a phosphate and a zinc compound as an initial treatment agent. It is easy to be obtained and an excellent corrosion prevention effect is easily obtained.

In the present invention, after adding an initial treating agent containing at least one selected from tartaric acid and tartrate, the pH of the aqueous system is 6.0 to 8.0, preferably 6.0 to 7.5, More preferably, it is 6.5 to 7.5.
If the pH of the aqueous system after adding the initial treatment agent is less than the above range (less than 6.0), inconvenience such as acid corrosion is likely to occur, and the rate at which corrosion proceeds on the metal member surface (corrosion rate). ) May accelerate.
On the other hand, when the pH of the aqueous system after adding the initial treatment agent exceeds the above range (exceeds 8.0), the tartaric acid that has become an anion binds to calcium ions present in the water, Therefore, there is a risk that an anticorrosion film mainly composed of a hardly soluble calcium salt is hardly formed on the surface of the metal member.

PH in this specification refers to the value calculated | required based on operation of a glass electrode method based on the method as described in JISZ8802: 2011.
For pH calibration, phthalate, neutral phosphate, and carbonate pH standard solutions can be used.

In the present invention, the pH of the aqueous system after the addition of the initial treating agent specified in the present invention can be set within a specific range (pH 6.0 to 8.0).
However, even when the pH of the aqueous system after addition of the initial treating agent specified in the present invention is out of a specific range (pH 6.0 to 8.0), sulfuric acid, sodium hydroxide, potassium hydroxide, etc. It is only necessary that the pH of the aqueous system can be adjusted to a specific range (pH 6.0 to 8.0) using the pH adjuster.

The water quality of the aqueous system applied to the initial treatment step of the corrosion prevention method of the present invention, that is, the water quality of the aqueous system before the addition of the initial treatment agent affects the pH of the aqueous system after the addition of the initial treatment agent, thereby preventing corrosion. An effect may not be exhibited suitably.
In the present invention, from the viewpoint of easily adjusting the pH of the aqueous system after addition of the initial treating agent specified in the present invention to a specific range (pH 6.0 to 8.0), the initial stage of the corrosion prevention method of the present invention is used. The water quality of the water system applied to the treatment process preferably has the following parameters.

The pH of the water quality is preferably 6.0 to 8.0, more preferably 6.0 to 7.5, and still more preferably 6.5 to 7.5.
Calcium hardness of water is preferably 30 ~ 150mgCaCO ₃ / L, more preferably 30 ~ 120mgCaCO ₃ / L, more preferably 30 ~ 100mgCaCO ₃ / L.
The water quality ionic silica is preferably 5 to 35 mg SiO ₂ / L, more preferably 10 to 30 mg SiO ₂ / L, and still more preferably 15 to 25 mg SiO ₂ / L.

In the present invention, the initial treatment step for forming the anticorrosive film on the surface of the metal member is preferably carried out in the water system circulation preferably 20 to 48 hours, more preferably 24 to 36 hours without applying a heat load to the water system.
Thereby, the corrosion weight loss after passing through an initial treatment process and a normal operation process can be made small. And an anticorrosion film | membrane is easy to be formed favorably with respect to the metal member surface, and it becomes easy to obtain the outstanding corrosion prevention effect.

As described above, the initial treatment step in the present invention is preferably in a state where no heat load is applied to the water system. Specifically, the temperature of the aqueous system in the initial treatment step without applying a heat load is preferably 10 to 40 ° C., more preferably 15 to 35 ° C., and still more preferably 20 to 30 ° C.
Here, the “state where no heat load is applied to the water system” refers to a state before entering the normal operation process and a state where the object to be cooled is not introduced into the circulating cooling water system.
When the temperature of the aqueous system in the initial treatment step is in the above range, evaporation of the aqueous system can be minimized, and the concentration of the initial treatment agent in the aqueous system can be easily kept constant.

Further, as described above, the initial treatment step in the present invention is preferably circulated in an aqueous system for 20 to 48 hours. In the course of the initial treatment step, the concentration of the initial treatment agent in the aqueous system is preferably kept constant from the viewpoint of forming the anticorrosion film uniformly on the surface of the metal member.

In the course of the initial treatment step, if the concentration of the initial treatment agent in the aqueous system is lower than the initial concentration, the concentration of the initial treatment agent in the aqueous system is 20 to 150 mg / L in terms of tartaric acid, preferably 30 to It is preferable to add an initial treatment agent so as to be 100 mg / L.
Here, the reason why the concentration of the initial treatment agent in the aqueous system is lower than the initial concentration may be exhaustion in the system, adsorption to a corrosion product, or the like.

On the other hand, in the course of the initial treatment step, if the concentration of the initial treatment agent in the aqueous system is higher than the initial concentration, the concentration of the initial treatment agent in the aqueous system is preferably 20 to 150 mg / L in terms of tartaric acid, preferably It is preferable to add an aqueous system so as to be 30 to 100 mg / L.

(Normal operation process)
The corrosion prevention method of the present invention may include a normal operation step for holding the anticorrosion film formed in the initial treatment step after the aforementioned initial treatment step.
Here, the “normal operation process” refers to a process performed for the purpose of holding the anticorrosion film formed on the surface of the metal member so as not to be peeled off in the initial treatment process.

In order to retain the anticorrosion film formed in the initial treatment step, it is preferable to add a retention treatment agent to the aqueous system after the initial treatment step.
As a result, the retention treatment agent is adsorbed on the surface of the anticorrosion film formed on the surface of the metal member, making the anticorrosion film difficult to peel off, and the corrosion prevention effect is easily maintained. Furthermore, a scale adhesion preventing effect that prevents insoluble components from adhering to the surface of the anticorrosion film can be easily obtained.

In the normal operation step of the present invention, the retention treatment agent is preferably 20 to 100 mg / L, more preferably 30 to 80 mg / L, still more preferably 50 to 80 mg / L in the aqueous system after the initial treatment step. Added.
When the amount of the retention treatment agent is within the above range, the retention treatment agent is adsorbed on the surface of the anticorrosion film formed on the surface of the metal member, making the anticorrosion film difficult to peel off, and the corrosion prevention effect is easily maintained. . Furthermore, a scale adhesion preventing effect that prevents insoluble components from adhering to the surface of the anticorrosion film can be easily obtained.

Further, the amount of the initial treatment agent containing at least one selected from tartaric acid and tartrate contained in the aqueous system in the normal operation process is selected from tartaric acid and tartrate contained in the aqueous system in the above-described initial treatment process. There is no particular limitation as long as it is less than the amount of the initial treating agent containing at least one kind.
Even if a part of the anticorrosion film is peeled off from the surface of the metal member, an anticorrosion film is formed again on the surface of the metal member at the part where the initial treatment agent is present in the aqueous system in the normal operation process. You can also.

The retention treatment agent is not particularly limited as long as it is adsorbed on the surface of the anticorrosion film, makes the anticorrosion film difficult to peel off, and the corrosion prevention effect is easily maintained.
Examples of the retention treatment include polymer compounds such as a copolymer of acrylic acid and maleic acid, a copolymer of isobutylene and maleic acid, a maleic acid polymer, and a copolymer of acrylic acid / AMPS; zinc sulfate, chloride Zinc compounds such as zinc; phosphates such as inorganic phosphates and organic phosphates; and the like. These retention treatment agents may be used alone or in combination of two or more. AMPS means 2-acrylamido-2-methylpropanesulfonic acid.

In the normal operation process, the water quality of the aqueous system applied when no phosphate is used preferably has the following parameters.
The pH of the water quality is preferably 8.0 to 9.2, more preferably 8.5 to 9.0, and still more preferably 8.6 to 9.0.
The calcium hardness of water quality is preferably 350 to 650 mg CaCO ₃ / L, more preferably 400 to 600 mg CaCO ₃ / L, still more preferably 450 to 550 mg CaCO ₃ / L. By setting it as the range, the anticorrosion film is hardly peeled off, and the corrosion prevention effect is easily maintained. In addition, in order to adjust the calcium hardness of the water quality to the above range, a calcium source may be added to the aqueous system. An example of the calcium source is calcium chloride.
The acid consumption of water quality is preferably 130 to 170 mg CaCO ₃ / L, more preferably 140 to 160 mg CaCO ₃ / L, and still more preferably 145 to 155 mg CaCO ₃ / L.

Further, in the course of the normal operation process, the concentration of the retention treatment agent in the aqueous system is kept constant from the viewpoint of easily exerting the effect of retaining the anticorrosion film formed on the surface of the metal member so as not to peel off. It is preferable.

In the course of the normal operation process, if the concentration of the retention treatment agent in the aqueous system is lower than the initial concentration, the retention treatment agent is adjusted so that the concentration of the retention treatment agent in the aqueous system is 20 to 100 mg / L. It is preferable to add.
Here, the reason why the concentration of the retention treatment agent in the aqueous system is lower than the initial concentration may be exhaustion in the system, adsorption to a corrosion product, or the like.

On the other hand, if the concentration of the retention treatment agent in the aqueous system is higher than the initial concentration in the normal operation process, the aqueous system is adjusted so that the concentration of the retention treatment agent in the aqueous system is 20 to 100 mg / L. It is preferable to add.

The following evaluation tests A to C are conducted to more specifically explain the present invention, but the present invention is not limited to these examples.

(1) Evaluation test A for corrosion prevention effect
A test for evaluating the corrosion prevention effect on the surface of the metal member was conducted by the following method for the solutions for the initial treatment step prepared in Examples A1 to A3 and Comparative Examples A1 to A9.

(Example A1)
<Preparation of specimen>
An iron sensor (material: SS400, 10φ × 30 mm iron bar, surface area: 10.3 cm ² ) degreased with toluene and dried was used as a test piece.

<Preparation of solution for initial treatment process>
As the raw water, Nogi-cho water (hereinafter referred to as “Nogi-cho water”) in Shimotsuga-gun, Tochigi Prefecture was used.
At this time, the water quality of Nogi-cho water was pH 7.0, calcium hardness: 40 mg CaCO ₃ / L, and ionic silica: 20 mg SiO ₂ / L.
Nogicho water was put into a 1 L beaker, and sodium tartrate was added to Nogicho water as an initial treatment agent so as to be 30 mg / L. This beaker was moved to a thermostat set at 30 ° C. and heated to prepare the solution for the initial treatment step of Example A1.

<Measurement of pH of solution for initial treatment process>
Here, an appropriate amount of the prepared solution for the initial treatment step was collected, and based on the operation of the glass electrode method in accordance with the method described in JIS Z8802: 2011, the pH of the solution for the initial treatment step of Example A1 (Example) The pH of the aqueous system after addition of the A1 initial treatment agent was measured and found to be pH 7.3.
For pH calibration, phthalate, neutral phosphate, and carbonate pH standard solutions were used.

<Preparation of corrosion acceleration liquid>
A 10% by mass chloride ion solution (sodium chloride solution) and a 10% by mass sulfate ion solution (sodium sulfate solution) were used as corrosion treatment agents.
Into a 1L beaker, add Nogicho water and add 10% by mass chloride ion solution (sodium chloride solution) and 10% by mass sulfate ion solution (sodium sulfate solution) to 80 mg / L respectively. Then, a corrosion acceleration liquid was prepared.

<Initial treatment process>
The test piece was immersed in the solution for the initial treatment step of Example A1 prepared above. And stirring of the solution for initial process steps was started by rotating a stirrer at 300 rpm, and after stirring was continued for 24 hours at room temperature, stirring was terminated.
Using the corrosion meter (“K-600” manufactured by Toho Giken Co., Ltd.) from the start to the end of stirring of the solution for the initial treatment process, the rate at which the corrosion of the test piece proceeds (corrosion rate) over time Measured. The measurement results are shown in FIG.
Here, the “corrosion rate” refers to a weight reduction amount (mdd: mg / dm ² · day) of the test piece due to corrosion per unit area and unit time of the test piece.

<Corrosion treatment process>
After completion of the stirring in the initial treatment step, the solution for the initial treatment step was switched to the corrosion accelerating solution, and the test piece was immersed in the corrosion accelerating solution in the same manner as in the initial treatment step. Then, the stirring of the corrosion accelerating liquid was started by rotating the stirrer at 300 rpm, and this stirring was continued for 48 hours, and then the stirring was terminated.
From the start to the end of stirring of the corrosion accelerating liquid, the rate at which the corrosion of the specimen proceeds using a corrosion meter (“K-600” manufactured by Toho Giken Co., Ltd.) in the same manner as in the initial treatment step ( Corrosion rate) was measured over time. The measurement results are shown in FIG.

(Example A2)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Example A2 was conducted in the same manner as in Example A1, except that sodium tartrate was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test to evaluate the effect was conducted.
It was pH 6.9 when pH of the solution for initial process steps of Example A2 (pH of the water system after adding the initial process agent of Example A2) was measured.

(Example A3)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Example A3 was performed in the same manner as in Example A1, except that sodium tartrate was added to Nogi-cho water as an initial treatment agent so as to be 100 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Example A3 (the pH of the aqueous system after the addition of the initial treatment agent of Example A3) was measured and found to be 7.0.

(Comparative Example A1)
In the preparation of the solution for the initial treatment step of Example A1, corrosion prevention of Comparative Example A1 was conducted in the same manner as in Example A1, except that sodium tartrate was added as an initial treatment agent to Nogi-cho water so as to be 300 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Comparative Example A1 (water-based pH after addition of the initial treatment agent of Comparative Example A1) was measured to be pH 7.1.

(Comparative Example A2)
In the preparation of the solution for the initial treatment step of Example A1, the anti-corrosion effect of Comparative Example A2 is the same as that of Example A1, except that tartaric acid is added to Nogi-cho water as an initial treatment agent so as to be 100 mg / L. The test which evaluates was conducted.
The pH of the solution for the initial treatment step of Comparative Example A2 (water-based pH after the addition of the initial treatment agent of Comparative Example A2) was measured and found to be 5.0.

(Comparative Example A3)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Comparative Example A3 was performed in the same manner as in Example 1 except that gluconic acid was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Comparative Example A3 (the pH of the aqueous system after addition of the initial treatment agent of Comparative Example A3) was measured and found to be pH 7.3.

(Comparative Example A4)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Comparative Example A4 was performed in the same manner as in Example A1, except that citric acid was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Comparative Example A4 (the pH of the aqueous system after the addition of the initial treatment agent of Comparative Example A4) was measured and found to be 6.1.

(Comparative Example A5)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention effect of Comparative Example A5 is the same as that of Example A1, except that acetic acid is added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. The test which evaluates was conducted.
The pH of the solution for the initial treatment step of Comparative Example A5 (the pH of the aqueous system after the addition of the initial treatment agent of Comparative Example A5) was measured and found to be 6.1.

(Comparative Example A6)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion of Comparative Example A6 was performed in the same manner as in Example A1, except that ethylenediaminetetraacetic acid was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test was conducted to evaluate the prevention effect.
The pH of the solution for the initial treatment step of Comparative Example A6 (the pH of the aqueous system after adding the initial treatment agent of Comparative Example A6) was measured to be 6.7.

(Comparative Example A7)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Comparative Example A7 was performed in the same manner as in Example A1, except that maleic acid was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Comparative Example A7 (water-based pH after the addition of the initial treatment agent of Comparative Example A7) was measured and found to be 6.2.

(Comparative Example A8)
In the preparation of the solution for the initial treatment step of Example A1, the corrosion prevention of Comparative Example A8 was carried out in the same manner as in Example A1, except that succinic acid was added to Nogi-cho water as an initial treatment agent so as to be 50 mg / L. A test to evaluate the effect was conducted.
The pH of the solution for the initial treatment step of Comparative Example A8 (the pH of the aqueous system after the addition of the initial treatment agent of Comparative Example A8) was measured and found to be 6.1.

(Comparative Example A9)
In the preparation of the solution for the initial treatment step of Example A1, as the initial treatment agent, hexametaphosphoric acid, which is a phosphate, is added to Nogi-cho water to 100 mg PO ₄ / L, and zinc chloride, which is a zinc compound, is added to 20 mg Zn / L. A test for evaluating the corrosion prevention effect of Comparative Example A9 was conducted in the same manner as in Example A1 except that this was done.
The pH of the solution for the initial treatment step of Comparative Example A9 (the pH of the aqueous system after addition of the initial treatment agent of Comparative Example A9) was measured and found to be 6.5.

The type of initial processing agent, the amount added (mg / L), and the pH of the initial processing step solution (initial value) used in the preparation of the initial processing step solutions of Examples A1 to A3 and Comparative Examples A1 to A9 described above. Table 1 shows the measurement results of the pH of the aqueous system after the treatment agent was added.

FIG. 1 shows the change in corrosion rate (mdd: mg / dm ² · day) measured over time in the initial treatment process and the corrosion treatment process of Examples A1 to A3 and Comparative Examples A1 to A9 described above. .

(Summary of results of evaluation test A)
The following can be understood from the result of the evaluation test A regarding the corrosion prevention effect shown in FIG.
The corrosion rate in Comparative Example A1 is attributed to the fact that the initial treatment agent specified in the present invention was added to the aqueous system in excess of a specific amount (20 to 150 mg / L, especially 30 to 100 mg / L in terms of tartaric acid). It was higher than the corrosion rate of ~ A3.
From this, it was found that Comparative Example A1 cannot satisfactorily form the anticorrosion film on the surface of the metal member, and the corrosion prevention effect cannot be sufficiently obtained.

The corrosion rate in Comparative Example A2 is due to the fact that the pH of the aqueous system after addition of the initial treating agent specified in the present invention was less than a specific range (pH 6.0 to 8.0). It was higher than the corrosion rate.
From this, it was found that Comparative Example A2 cannot satisfactorily form the anticorrosion film on the surface of the metal member, and the corrosion prevention effect cannot be sufficiently obtained.

Further, the corrosion rates in Comparative Examples A3 to A8 were higher than those in Examples A1 to A3 because the initial treatment agent specified in the present invention was not used.
From this, it was found that Comparative Examples A3 to A8 cannot satisfactorily form the anticorrosion film on the surface of the metal member, and the corrosion preventing effect cannot be sufficiently obtained.

On the other hand, the corrosion rates in Examples A1 to A3 were determined by adding a specific amount (20 to 150 mg / L, especially 30 to 100 mg / L in terms of tartaric acid) of the initial treatment agent specified in the present invention to the aqueous system. Due to the fact that the pH of the aqueous system after the addition of the agent is in a specific range (pH 6.0 to 8.0), it is as low as Comparative Example A9 using a phosphate and a zinc compound as the initial treatment agent Met.
From this, it was found that Examples A1 to A3 can form a good anticorrosion film on the surface of the metal member and have an excellent anticorrosion effect.

(2) Evaluation test B for corrosion prevention effect
For the initial treatment process solution prepared in Example A2 and Comparative Example A9 and the blank solution used in the evaluation test A related to the corrosion prevention effect described above, the corrosion prevention effect on the metal member surface was evaluated by the following method. A test was conducted.

(Example B1)
<Preparation of specimen>
An SPCC test piece (size: 30 mm × 50 mm × 1 mm) was etched with a 20% by mass nitric acid solution and a 10% by mass sulfuric acid solution and dried to obtain a test piece.
The weight W ₁ of the test piece before performing corrosion test B is measured in advance.

<Initial treatment process>
In the state where the test piece was immersed in the solution for the initial treatment step of Example A2 and heated to 30 ° C., the rotation of the test piece was started at 150 rpm using a rotary corrosion test apparatus (manufactured by Shinwa Kogyo Co., Ltd.). After the rotation was continued for 24 hours, the rotation was stopped and the first initial processing step was completed.

<Blank treatment process>
After completion of the first initial treatment step, the initial treatment step solution of Example A2 was switched to the blank solution, and the test piece was immersed in the blank solution and heated to 30 ° C., and the rotary corrosion was performed similarly to the initial treatment step. Using the test apparatus, the rotation of the test piece was started at 150 rpm, and this rotation was continued for 24 hours. Then, the rotation was stopped and the first blanking process was completed.
Here, the “blank solution” refers to the same as Nogimachi water used as raw water for the preparation of the initial treatment step solution of Example A1.

<Calculation of corrosion weight loss _{W A>}
After the first blanking step is completed, pulling the test piece was dried weight W ₂ of the test piece was measured to calculate the corrosion weight loss W _A of the first test piece by the following equation 1.
The weight W ₁ of the previous test piece for evaluation test B are measured in advance.
(Formula 1): Corrosion weight loss W _A (mg) = | W ₂ −W ₁ |

Subsequently, the second initial processing step was performed for 24 hours in the same manner as the first time, and then the second blank processing step was performed for 24 hours. After completion of the second blanking step, the corrosion weight loss W _A of the second test piece was calculated by the equation 1 in the same manner as the first.
Further, the third initial treatment step was performed for 24 hours in the same manner as the first time, and then the third blank processing step was performed for 24 hours. After completion of the third blanking step, the corrosion weight loss W _A of the third test piece was calculated by the equation 1 in the same manner as the first.

(Comparative Example B1)
In the initial treatment step of Example B1, the corrosion prevention effect of Comparative Example B1 is the same as Example B1, except that the solution for the initial treatment step of Example A2 is changed to the solution for the initial treatment step of Comparative Example A9. The test to evaluate was done.

(Comparative Example B2)
In the initial treatment step of Example B1, a test for evaluating the corrosion prevention effect of Comparative Example B2 was performed in the same manner as in Example B1, except that the solution for the initial treatment step of Example A2 was changed to a blank solution.

In Example B1 and Comparative Examples B1 and B2 described above, the initial treatment step and the blank treatment step were set as one set, and this set was repeated three times, and the change in corrosion weight loss measured over time is shown in FIG.

(Summary of results of evaluation test B)
From the results of the evaluation test B relating to the corrosion prevention effect shown in FIG.
Corrosion weight loss in Comparative Example B2 was large due to the absence of the initial treatment agent.
From this, it was found that Comparative Example B2 cannot form an anticorrosion film on the surface of the metal member, and the corrosion prevention effect cannot be obtained.

On the other hand, the corrosion weight loss in Example B1 is the addition of a specific amount (20 to 150 mg / L, especially 30 to 100 mg / L in terms of tartaric acid) of the initial treatment agent specified in the present invention to the aqueous system. Due to the fact that the pH of the aqueous system after the addition was within a specific range (pH 6.0 to 8.0), it was as low as Comparative Example B1 using a phosphate and a zinc compound as an initial treatment agent. It was.
From this, it turned out that Example B1 can form an anticorrosion film | membrane favorably with respect to the metal member surface, and the outstanding corrosion prevention effect is acquired.

(3) Evaluation test C for corrosion prevention effect
Using the heat transfer surface evaluation test apparatus shown in FIG. 3, a test for evaluating the corrosion prevention effect on the surface of the metal member (specifically, the evaluation tube 2 made of iron) was performed by the following method.

<Heat transfer surface evaluation test device>
The heat transfer surface evaluation test apparatus shown in FIG. 3 adjusts the flow rate of the test water in the test water tank (100 L capacity) 1 with the circulating water pump P ₁ and supplies the test water to the test tube 3 through the circulation line L _1. , in which circulates the test water in the test water tank 1 through the circulation return line L _2.
An evaluation tube 2 made of iron is inserted into the test tube 3, and the evaluation tube 2 made of iron can be immersed in test water when the apparatus is activated.
A heater (thermocouple) 4 is inserted into the iron evaluation tube 2, and the iron evaluation tube 2 can be heated by the heater (thermocouple) 4 when the apparatus is activated.
The circulation return line L _2, the flow rate regulating valve V is provided.
The test water in the make-up water tank (300 L capacity) 5 can be supplied to the test water tank 1 through the make-up water line L ₃ as necessary.
When the test water in the makeup water tank 5 is supplied into the test water tank 1, the flow rate of the test water to be replenished is adjusted by circulating water pump P _2.
The test water tank 1, an overflow line L _4, which can be discharged to the outside when the test water exceeds a predetermined amount.

(Test 1)
<Initial treatment process>
Test water tank (100L capacity) 1 Put Nogi-cho water, add tartaric acid to Nogi-cho water as an initial treatment so as to be 50 mg / L, warm the water system to 30 ° C, and test water for the initial treatment process 1 was prepared.
Here, “Nogimachi water” refers to the same Nogimachi water used as raw water for the preparation of the initial treatment step solution of Example A1.
The water quality of the test water 1 at this time was pH: 7.0, calcium hardness: 40 mg CaCO ₃ / L, ionic silica: 20 mg SiO ₂ / L, and acid consumption: 40 mg CaCO ₃ / L.
The heater (thermocouple) 4 is driven to set the power to 2 kW and the tube temperature to 80 ° C. to apply a heat load to the water system, and the flow rate of the test water 1 in the test water tank (100 L capacity) 1 is a circulating water pump. A series of water system circulation in which the test water 1 is adjusted to 0.5 m / s at P ₁ , the test water 1 is supplied to the test tube 3 through the circulation line L ₁ , and the test water 1 is returned to the test water tank 1 through the circulation return line L _2. It went for 24 hours.
It should be noted that the actual temperature of the aqueous system was controlled to be 30 ° C. even in a state where a heat load was applied to the aqueous system in the initial treatment step.

<Normal operation process>
After completion of the water system circulation in the initial treatment process, 50 mg / L of a copolymer of acrylic acid and maleic acid as a retention treatment agent and zinc chloride which is a zinc compound are added to the test water 1 in the test water tank (100 L capacity) 1 Is added so that the calcium hardness becomes 500 mg CaCO ₃ / L, and 5 mass% weight is added so that the acid consumption becomes 150 mg CaCO ₃ / L. A sodium carbonate solution was added, and the water system was heated to 30 ° C. to prepare test water 2 for a normal operation process.
The water quality of the test water 2 at this time was pH: 8.6, calcium hardness: 500 mg CaCO ₃ / L, and acid consumption: 150 mg CaCO ₃ / L.
The heater (thermocouple) 4 is driven to set the power to 2 kW, the tube temperature to 80 ° C. to apply a heat load to the water system, and the flow rate of the test water 2 in the test water tank (100 L capacity) 1 is a circulating water pump. A series of water system circulation in which the test water 2 is adjusted to 0.5 m / s at P ₁ , the test water 2 is supplied to the test tube 3 through the circulation line L ₁ , and the test water 2 is returned to the test water tank 1 through the circulation return line L _2. It went for 48 hours.
It should be noted that the actual temperature of the aqueous system was controlled to be 30 ° C. even in a state where a heat load was applied to the aqueous system in the normal operation process.

<Calculation of corrosion weight loss _{W B>}
After the usual aqueous circulation completion of operation step, raising the iron evaluation tube 2, dried and weighed W ₄ Evaluation tube 2, and the corrosion weight loss W _B rating tube 2 Test 1 was calculated by the following equation 2.
The weight W ₃ of the evaluation tube 2 before performing the evaluation test C was measured in advance.
(Formula 2): Corrosion weight loss W _B (mg) = | W ₄ −W ₃ |

(Test 2)
In the initial treatment process of Test 1, the heater (thermocouple) 4 was not driven, that is, no heat load was applied to the water system, and a series of water system circulation was performed for 24 hours. A test was conducted to evaluate the corrosion prevention effect.
It should be noted that the actual temperature of the aqueous system was controlled to be 30 ° C. even in a state where no heat load was applied to the aqueous system in the initial treatment step.

Table 2 shows the measurement results of the weight loss after the initial treatment process and the normal operation process of Test 1 and Test 2 described above.

(Summary of results of evaluation test C)
From the results of the evaluation test C regarding the corrosion prevention effect shown in Table 2, the following can be understood.
Corrosion weight loss in Test 1 was large due to the fact that a heat load was applied to the water system and a series of water system circulation was performed in the initial treatment process.
On the other hand, the corrosion weight loss in Test 2 was small due to a series of aqueous circulation without applying a heat load to the aqueous in the initial treatment step.
From this, it was found that Test 2 can form a better anticorrosion film on the surface of the metal member than Test 1, and an excellent corrosion prevention effect can be obtained.

1: test water tank 2: evaluation tube 3: test tube 4: heater 5: makeup water tank L1: circulation line L2: circulation return line L3: makeup water line L4: overflow line P1: circulation water pump P2: circulation water pump V : Flow adjustment valve

Claims

An initial treatment agent for circulating cooling water added to the aqueous system at the time of starting the circulating cooling water system to form an anticorrosive film on the surface of the metallic member of the aqueous system,
An initial treatment agent for circulating cooling water containing at least one selected from tartaric acid and tartrate.
The initial treatment agent for circulating cooling water according to claim 1, wherein the content of at least one selected from tartaric acid and tartrate salt is 90 to 100% by mass in 100% by mass of the initial treatment agent for circulating cooling water.
A method for preventing corrosion of a circulating cooling water system including an initial treatment step of forming an anticorrosive film on the surface of a metallic member of the aqueous system when the circulating cooling water system is started,
In the initial treatment step, the initial treatment agent for circulating cooling water containing at least one selected from tartaric acid and tartaric acid salt according to claim 1 or 2 in the aqueous system is 20 to 150 mg / L in terms of tartaric acid. A method for preventing corrosion of a circulating cooling water system, wherein the pH of the aqueous system after addition of the initial treatment agent for circulating cooling water is 6.0 to 8.0.
The method for preventing corrosion of the circulating cooling water system according to claim 3, wherein the initial treatment agent for circulating cooling water comprises at least one selected from tartaric acid and tartrate.
The method for preventing corrosion of the circulating cooling water system according to claim 3 or 4, wherein in the initial treatment step, the water system is circulated for 20 to 48 hours without applying a heat load to the water system.
In the initial treatment step, an initial treatment agent for circulating cooling water containing at least one selected from the tartaric acid and tartrate is added to the aqueous system so as to be 30 to 100 mg / L in terms of tartaric acid. The method for preventing corrosion of a circulating cooling water system according to any one of claims 3 to 5, wherein the pH of the aqueous system after addition of the water initial treatment agent is 6.0 to 8.0.
The method for preventing corrosion of a circulating cooling water system according to any one of claims 3 to 6, wherein in the initial treatment step, the temperature of the aqueous system is 10 to 40 ° C and the aqueous system is circulated for 20 to 48 hours.
The method for preventing corrosion of a circulating cooling water system according to any one of claims 3 to 7, further comprising a normal operation step for holding the anticorrosion film formed in the initial treatment step after the initial treatment step.
The method for preventing corrosion of a circulating cooling water system according to claim 8, wherein a retention treatment agent is added to the aqueous system after the initial treatment process in the normal operation process.
The method for preventing corrosion of a circulating cooling water system according to claim 8 or 9, wherein, in the normal operation process, the retention treatment agent is added to the aqueous system after the initial treatment process so as to be 20 to 100 mg / L.