JP2650196B2 - Water treatment agent and water treatment method for soft water boiler - Google Patents

Description

The present invention relates to a soft water boiler water treating agent and a treating method. More specifically, the present invention relates to a soft water boiler water treatment chemical and a treatment method capable of preventing corrosion of iron-based metals that come into contact with soft water, particularly pitting corrosion, in a boiler water system using high-temperature soft water.

(B) Conventional technology In addition to raw water boilers that use raw water such as industrial water and well water as they are, soft water boilers and pure water boilers are generally used as boilers. It is set at 110 ° C to critical temperature under the internal pressure.

Among these, the soft water boiler uses water (soft water) from which most of the hardness components have been removed by ion exchange treatment or the like, so that scale generation is small even in a highly concentrated water use system in which this is repeatedly used. However, components other than the hardness component, particularly anion components such as chloride ion and sulfate ion, are not removed, and the iron-based metal in the system corrodes due to the presence of the anion component and dissolved oxygen in the soft water. In particular, pitting, which leads to a major accident, is likely to occur.

Therefore, in such a soft water boiler, soft water is passed through a deaerator and deoxidized by adding a deoxidizing agent such as sulfite or hydrazine. A method for preventing the corrosion of iron-based metals, particularly pitting corrosion, by adding an agent and, if necessary, adjusting the pH to 10 to 12 by adding an alkali agent (deoxygenation- Alkali treatment method).

However, the above-described deoxygenation-alkali treatment requires frequent deoxygenation treatment and has an insufficient effect of preventing corrosion of iron-based metals.

Therefore, the applicant of the present application has previously (a) selected from molybdic acid and its alkaline salts, tungstic acid and its alkaline salts and alkaline salts of nitrous acid.
(B) a compound capable of easily releasing heavy metal ions in water; and (d) a water-soluble olefin compound having a molecular weight of 500 to 100,000. A four-component anticorrosive containing a polymer or a copolymer as an active ingredient (Japanese Patent Publication No. 62-57715) and a five-component anticorrosive further containing a monoamine having 2 to 8 carbon atoms in addition to these four components (Japanese Patent Publication No. 62-27157).

All of these anticorrosives are applied to the surface of iron-based metal in a soft water boiler water system, with strong and dense Fe that cannot be seen in normal anticorrosion treatment.
_{A 3} O ₄ black film is formed to prevent corrosion. According to this treating agent, corrosion of the iron-based metal in the water system of the soft water boiler in which the anion component is present, especially occurrence of pitting corrosion, can be prevented without performing the above-described deoxidizing treatment at all.

(C) Problems to be Solved by the Invention As described above, the soft water used in the soft water boiler has a hardness component substantially removed, so that even in a system that is recycled and reused, the total hardness is usually 1 mg / mg. Within.

However, with the increase in the amount of evaporation and the heat transfer load with respect to the boiler water capacity in recent years, the processing capacity of the water softener that supplies the soft water becomes insufficient and the ion exchange resin is likely to deteriorate. (Hardness leak)
When such soft water was circulated, the hardness increased to 20 mg / min or more.

And in the soft water boiler water system mixed with such a hardness component, the above-mentioned JP-B-62-27157 and JP-B-6-27157 are mentioned.
In the case where the anticorrosive agent of JP-A-2-57715 is added, the formation of the black film is not uniform due to the adhesion of scale to the surface of the iron-based metal, and as a result, the effect of preventing corrosion of the iron-based metal is insufficient. The tendency is that the hardness component is 20 mg /
It was remarkable when it exceeded.

The present invention has been made in order to solve such a problem, and even in a soft water boiler water system in which a hardness leak may occur, it is possible to reliably prevent the corrosion of iron-based metals in the system without performing deoxidation treatment. It seeks to provide a way.

(D) Means for Solving the Problems Thus, according to the present invention, (a) at least one compound selected from molybdic acid, tungstic acid, nitrous acid or an alkali salt thereof; A compound capable of releasing oxycarboxylate ions, (c) a heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water, and (d) a general formula: H ₂ N (CH ₂ CH ₂ NH) nH (formula Where n is 2
A polyamine represented by an integer of 5) or an acid addition salt thereof;
Is provided as a soft water boiler water treatment agent. Furthermore, according to the present invention, the above components (a) to (b)
A soft water boiler water treatment method comprising adding a specific amount of (d) to a boiler water system is provided.

According to the present invention, when a specific amount of the above components (a) to (d) is added to a soft water boiler water system, a strong and dense anticorrosive Fe ₃ O ₄ black film is formed on the surface of the iron-based metal in the boiler water system. The fact that the anticorrosion treatment can be carried out without using any oxygen scavenger, and the effect of the above can be found in a soft water boiler water system having a leaked hardness. .

Even if only the above three components (a), (b), and (c) are used, the above effect is not obtained at all. Component (d) is itself known as a boiler water treating agent (Japanese Patent Publication No.
No. 50-35601), as in the present invention (a) to
(C) Use in combination with the component has not been known so far, and formation of a strong anticorrosive black film in a boiler water system has never been known before.

The soft water boiler water system of the present invention means an apparatus system of a soft water boiler, in which the provided boiler water exists or circulates.

In addition, the boiler water here means the water used for the supply water of the soft water boil, and the soft water and its concentrated water are basically targeted. For example, the hardness component is 20 to 400 mg /
Includes those mixed to the extent. The present invention is particularly effective when such hardness leaks.

The “alkali salt” in the component (a) of the present invention includes:
It means an alkali metal salt such as sodium and potassium and an ammonium salt.

The component (A) used in the present invention is molybdic acid, tungstic acid, nitrous acid or an alkali salt thereof,
These are compounds common as oxidation-type anticorrosion components. These may be used alone or in combination of two or more.

The component (b) used in the present invention is a compound capable of releasing an aliphatic oxycarboxylate ion in water, and specific examples thereof include citric acid, gluconic acid, malic acid, mannonic acid, and sodium, potassium and ammonium thereof. And the like. In addition, an intramolecular condensate such as glucono-δ-lactone can be used. Two or more of these may also be used.

The component (c) used in the present invention is a heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water, for example, zirconium sulfate, zirconyl chloride, zirconyl nitrate, stannous chloride, stannic chloride, Chlorides such as stannous sulfate, manganese chloride, manganese sulfate, nickel chloride, nickel sulfate, nickel nitrate, etc., oxychlorides, nitrates, sulfates and the like.

The component (d) used in the present invention is a polyamine represented by the general formula: H ₂ N (CH ₂ CH ₂ NH) nH (where n is an integer of 2 to 5) or an acid addition salt thereof. Diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and their hydrochlorides,
Nitrate, sulfate and the like can be mentioned. These (d) components may also be used in combination of two or more.

(A)-(d) Each component is (a) component 1-100mg /, preferably 2.5-100mg /, (b) in soft water boiler water.
Ingredient 50-5000mg /, preferably 100-5000mg /
(C) component 0.5-100 mg /, preferably 1-100 mg /
(D) Component 20 to 5000 mg /, preferably 50 to 5000 mg /
Is added so that However, the component (c) is expressed in terms of the amount of metal ions.

When the amount of addition of at least one component is smaller than the minimum value, the other components are not suitable because an effective anticorrosive effect cannot be obtained even if an effective amount is present, and the effect increases as the amount of addition increases. Becomes better accordingly, but it is rarely necessary to add more than the respective maximum value for economic reasons.

By adding the above-mentioned four components to the soft water boiler water system in the above-mentioned effective amounts and using the same, a strong anticorrosive coating is formed on the surface of the iron-based metal of the soft water system. This film was confirmed to be made of triiron tetroxide, and was very dense and had a uniform thickness without any missing portions.

Further, it has been confirmed that the coating of triiron tetroxide reaches the surface layer of the base material (iron material). In addition, since there is no organic substance such as polyamine as the component (d) in the coating, the component (d) is considered to have some catalytic action. This coating has the effect of preventing corrosion without being affected by the anions present in the boiler water (which has the effect of generating and promoting the catalyst) and the dissolved enzymes. It has an unnecessary advantage.

These components (a) to (d) may be added simultaneously or separately, but it is preferable to prepare a preparation containing these four components and add them.

The blending ratio of such a formulation (soft water boiler water treatment agent) is suitable to correspond to the above-mentioned addition ratio.
When the total amount of the components (a) to (d) is 100 parts by weight, 0.01 to 58.7 parts by weight of the component (a), 0.95 to 99.6 parts by weight of the component (b), and 0.005 to 58.5 parts by weight of the component (c) (metal ion It is suitable to mix the components so as to be in the range of (converted value) and (d) component (0.38-99.0 parts by weight).

From the viewpoints of workability and storage stability of the drug, it is desirable that the soft water boiler water treatment agent of the present invention containing these four components be a liquid preparation. In this case, the preparation method uses an aqueous medium such as water or a water / hydrophilic organic solvent mixed solvent as a solvent,
The component (b) is dissolved, and then the component (c) is added and sufficiently stirred to dissolve. Next, it is desirable to add the component (d) and stir well, then add the component (a) and stir well to dissolve.

The total concentration of the components (a) to (d) in such a solvent is 10
~ 70% by weight is suitable. Furthermore, (b) component and (d)
It is preferable to mix the components in a molar ratio of 6: 1 to 1:10 in order to form a stronger anticorrosive coating.

In carrying out the soft water boiler treatment method of the present invention, in addition to the above four components (a), (b), (c), and (d), various additives may be used in combination. It may be previously blended in the composition. Examples of such combined additives include an aqueous dispersant, a pH adjuster, and other anticorrosive components.

Among these, a water-soluble dispersant includes a homopolymer having acrylic acid, methacrylic acid, or maleic acid as a monomer, or a copolymer of two or more of these, or another ethylenic doublet copolymerizable with any of the above. 20mo of the above monomer component in a copolymer with a compound having a bond
It is a copolymer containing 1% or more, or a mixed polymer of two or more of these homopolymers and copolymers. It contains a water-soluble polymer having a molecular weight of 500,000 to 100,000. Such a water-soluble polymer is disclosed in Japanese Patent Publication No. Sho 62-5771.
It is used as one of the essential components of the four-component and five-component anticorrosives disclosed in JP-A-5-227 and JP-A-62-27157. However, in the present invention, such a water-soluble polymer is not an essential component, and regardless of use or non-use of the water-soluble polymer, a strong anticorrosive film is formed because the effect of the present invention was exhibited. Therefore, in the present invention, the above water-soluble polymer is mainly used only for the purpose of preventing or suppressing scale generation.

Other water-soluble dispersants which can be used include compounds of the general formula (I): (Where k is 0 to 2, m is an integer of 2 to 6, M is a hydrogen atom, sodium or potassium, and may be the same or different) General formula (II): (X is OH or NH ₂ , M is a hydrogen atom, sodium or potassium, which may be the same or different), a general formula (III): (M represents a hydrogen atom, sodium or potassium,
m and n are positive integers and m + n = 4 to 20), and have the following structural formula: and bis (poly) -2-carboxyethyl) phosphinic acid.

Examples include amino-substituted phosphinic acids.

Examples of the pH adjusting agent that can be used in the present invention include alkali hydroxides such as sodium hydroxide and potassium hydroxide and ammonia for adjusting to the alkali side, and examples of the adjusting agent for the acid side include hydrochloric acid, sulfuric acid, and nitric acid. And the like. These pH adjusters are arbitrarily added according to the optimum pH of the soft water boiler to be added. When copper or aluminum-based metal exists in the system, addition of ammonia should be avoided. Also, the use of nitric acid or hydrochloric acid should normally be avoided.

Other suitable anticorrosive components that can be used in combination with the present invention include those having 2 to 8 carbon atoms known as general condensate anticorrosives.
Examples of monoamines having a single bond include propylamine, butylamine, morpholine, cyclohexylamine, ethanolamine, propanolamine, and aminomethylpropanol. However, these are not directly involved in the formation of the anticorrosion coating in the present invention, but one preferred embodiment is to use them in terms of preventing corrosion in the steam condensate system of the boiler device. When these form a salt with the component (a) or the component (b), they may be used in the form of the salt.

(E) Examples This is illustrated by the following preparations and test examples of the present invention. In addition, the composition ratio of each preparation is all% by weight, and the balance is water.

Formulation (1) Sodium molybdate dihydrate: 1.0
Gluconic acid (50%): 50.0 (as 50%) Stannous chloride dihydrate: 1.0 Diethylenetriamine: 17.0 After adding gluconic acid to water in the above mixing ratio, stannous chloride dihydrate was added. Then, sodium molybdate dihydrate and diethylenetriamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (2) Sodium molybdate dihydrate: 1.0 Glucono δ lactone: 25.0 Stannous chloride dihydrate: 1.0 Diethylene triamine: 17.0 At the above mixing ratio, glucono δ lactone was dissolved in water, and then stannous chloride 2 The water salt was then added successively to dissolve sodium molybdate dihydrate and diethylene triamine to obtain a solution.

Formulation (3) Sodium molybdate dihydrate: 0.5 Malic acid: 15.0 Stannous chloride dihydrate: 0.5 Diethylenetriamine: 30.0 At the above mixing ratio, malic acid was dissolved in water, and then stannous chloride dihydrate. Then, sodium molybdate dihydrate and diethylenetriamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (4) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 diethylenetriamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio,
Stannous chloride dihydrate, then sodium molybdate dihydrate and diethylenetriamine were sequentially added and dissolved to obtain a solution.

Formulation (5) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 triethylenetetramine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio. ,
Stannous chloride dihydrate, then sodium molybdate dihydrate and triethylenetetramine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (6) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 tetraethylenepentamine: 30.0 Citric acid monohydrate was dissolved in water at the above mixing ratio. rear,
Stannous chloride dihydrate, then sodium molybdate dihydrate and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (7) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 pentaethylenehexamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio. ,
Stannous chloride dihydrate, then sodium molybdate dihydrate and pentaethylenehexamine were sequentially added and dissolved to obtain a solution.

Formulation (8) Sodium tungstate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 tetraethylenepentamine: 30.0 Citric acid monohydrate was dissolved in water at the above mixing ratio. rear,
Stannous chloride dihydrate, then sodium tungstate dihydrate and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (9) Sodium tungstate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous sulfate: 0.7 tetraethylenepentamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio,
Stannous sulfate, then sodium tungstate 2
A water salt and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (10) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 zirconium sulfate tetrahydrate: 0.7 tetraethylenepentamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio. ,
Zirconyl sulfate and then sodium molybdate 2
A water salt and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (11) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 manganese sulfate heptahydrate: 0.7 tetraethylene petamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio,
Manganese sulfate heptahydrate, sodium molybdate dihydrate and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (12) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 Nickel sulfate heptahydrate: 0.7 tetraethylenepentamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio,
Nickel sulfate heptahydrate, then sodium molybdate dihydrate and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (13) Sodium nitrite: 0.7 guenoic acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 tetraethylenepentamine: 30.0 After dissolving citric acid monohydrate in water at the above mixing ratio,
Stannous chloride dihydrate, then sodium nitrite and tetraethylenepentamine were sequentially added and dissolved to obtain a solution.

Formulation (14) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 triethylenetetramine: 30.0 sodium polyacrylate: 2.0 (molecular weight = about 80000) After dissolving citric acid monohydrate in water,
Stannous chloride dihydrate, then sodium molybdate dihydrate, triethylenetetramine and sodium polyacrylate were sequentially added and dissolved to obtain a solution.

Formulation (15) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 triethylenetetramine: 30.0 acrylate methacrylic acid copolymer: 2.0 (molecular weight = about 8000, reaction molar ratio 1) : 1) After dissolving citric acid monohydrate in water at the above mixing ratio,
Stannous chloride dihydrate, then sodium molybdate dihydrate, triethylenetetramine, and methacrylic acid copolymer were sequentially added and dissolved to obtain a liquid preparation.

Formulation (16) Sodium molybdate dihydrate: 0.7 citric acid monohydrate: 20.0 stannous chloride dihydrate: 0.7 triethylenetetramine: 30.0 phosphinic acid (Belclene 400; CIBA-GEIGY): 2.0 After dissolving citric acid monohydrate in water,
Stannous chloride dihydrate, then sodium molybdate dihydrate, triethylenetetramine and phosphinic acid were sequentially added and dissolved to obtain a solution.

Comparative Formulation Examples [(17) to (19)] Formulation (17) Sodium gluconate: 20 Sodium hydroxide: 1 Stannous chloride dihydrate: 1 Sodium molybdate dihydrate: 1 Sodium polyacrylate: 2 At the above mixing ratio, sodium gluconate is dissolved in water, then sodium hydroxide, stannous chloride dihydrate,
Sodium molybdate dihydrate and sodium polyacrylate (molecular weight: about 8,000) were sequentially added to obtain a liquid preparation.

Formulation (18) Sodium gluconate: 20 Sodium hydroxide: 1 Stannous chloride dihydrate: 1 Sodium molybdate dihydrate: 1 Morpholine: 10 Sodium polyacrylate: 2 (Molecular weight about 8000) Solubilize sodium gluconate in water, then sodium hydroxide, stannous chloride dihydrate,
Sodium molybdate dihydrate, morpholine, and sodium polyacrylate (molecular weight: about 8,000) were sequentially added to obtain a liquid preparation.

Formulation (19) (deoxygenation-alkali treatment) Potassium pyrophosphate: 12 Sodium hydroxide: 5 Hydrazine hydrate (containing 80%): 50 Sodium polyacrylate: 5 (Molecular weight about 8000) Potassium acid dissolved, then sodium hydroxide, hydrazine hydrate (containing 80%),
Sodium polyacrylate (molecular weight: about 8000) was sequentially added to obtain a liquid preparation.

Test Example (Test Example for Confirming Effect of Corrosion Prevention and Scale Adhesion on Iron-Based Heat Transfer Surface During Hardness Leak) A test was performed using the test apparatus shown in FIG. In the figure,
1 is a softener, 2 and 8 are heat exchangers, 3 is a downcomer constituting the center of the main body of the boiler, 4 is a can bottom, 5 is a heat transfer test tube, 6
Denotes an evaporation pipe, 7 denotes a steam reservoir, and 9 denotes a water supply tank.

Test water ^* was supplied to the water supply tank 9, and then a predetermined amount of the test drug was added. This water is supplied to the test boiler body by a pump. In the boiler main body, the test water is heated by a heat transfer test tube (heating unit) shown in FIG. 1 to be turned into steam and discharged out of the boiler system to concentrate the boiler water.

Preparation of test water ^* : Osaka city tap water was added to water 560 from which hardness components in the water were removed using a softener shown in FIG. Table 1 shows the results of the water quality analysis.

Test conditions: Test time: 7 hours / day (heating: 1 hour, cooling: 1 hour) x 20 days = 140 hours Assuming 10 kg / cm ^{2 at} the specified test pressure, 5 hours / day
It will be 100 hours for 20 days of operation.

Test pressure: 10 kg / cm ² Test tube material: STPG38 Heat transfer load (heat transfer surface evaporation rate): No. 1 heat transfer tube = approx. 170 kg / m ² · h… High load No. 2 heat transfer tube = approx. 80 kg / m ²・ H… Low load No.3 heat transfer tube = approx. 170Kg / m ²・ h… High load (Evaporation rate of heat transfer surface of general boiler is 60-100Kg / m ²・
h, and recently, some of them exceed 100 kg / m ² · h. ) Heat transfer tube area: 0.026m ² (No. 1 to 3 heat transfer tubes) Water content: 10 Evaporation amount: Approx. 7 kg / h Blow rate: Approx. 5% (intermittent) Blow rate is the amount of boiler water drainage relative to the boiler water supply (Blow amount).

In the boiler water, of the components carried by the boiler feedwater, components that do not shift to steam remain in the water. Therefore, unless part of the boiler water is discharged continuously or intermittently, the components in the water continue to be concentrated.

The relationship between the blow rate and the concentration of boiler water will be described using an example. Assuming that the water supply is 100 t / h, the blow rate is 5 t / h and the concentration ratio is 100 t / h ÷ 5 t / h = 20.

Test water quality: Osaka City water softened water 70% + Osaka City water raw water 30% Hardness component = about 16 mg / total hardness, usually 2 to 4 mg CaCO ₃ / at hardness leak.

Confirmation of test results After the test was completed, the heat transfer test tube with a high load was taken out, and the scale adhesion amount (mg), the number of pits (pieces / dm ² ), the presence or absence of a coating film, and analysis were performed. Table 2 summarizes the test results.

Note) Test Nos. 1 to 19 are the test results using the preparations (1) to (19). Formulations (1) to (16) and (19) were adjusted to 1000 mg / in boiler water so that Formulations (17) and (1)
8) was similarly added to be 2000 mg /.

In addition, the addition amounts in the table are all concentrations in boiler water.

* 1. The scale adhesion index was calculated from the average value of the weight of calcium attached to the high-load heat transfer sections No. 1 and No. 3 by the following formula.

Here, the drug described in Test No. 36 is one of the representative inventions described in JP-B-62-27157 (introduced as prior art in the section of prior art) of the applicant of the present invention,
It shows the best effect as the prior art. The above-mentioned invention was aimed at so that the effect of this invention might become clearer. The measurement of the hardness component adhesion amount was performed by washing each heat transfer section (test tube) with a 30% concentration nitric acid solution, and subjecting the washing liquid to atomic absorption spectrometry.

* 2. Each numerical value in the column of comprehensive evaluation has the following meaning.

5: Pitching number 0 (pieces / dm ² ), anticorrosion coating, scale adhesion index of 20 or less, very good overall judgment.

4: Pitching number 0 (pieces / dm ² ), anticorrosion coating available, and can be used by judging comprehensively with a scale adhesion index of 21 to 35.

3: Pitching number 0 (pieces / dm ² ), anticorrosion coating available, and can be used by judging comprehensively with a scale adhesion index of 36 to 50.

2: Pitching number: 1 to 10 (pieces / dm ² ), no anticorrosion coating, scale adhesion index of 51 or more, cannot be used due to comprehensive judgment.

1: Number of pitching 1 to 10 (pieces / dm ² ), no anticorrosion coating, scale adhesion index 101 or more, or number of pitching 11 (pieces / dm ² )
² ) Above, no anticorrosion coating, scale adhesion index of 51 or more, cannot be used as a comprehensive judgment.

[Invention] When the X-ray diffraction analysis was performed on the coating film formed in the example of the present invention (Test No. 6), the X-ray diffraction pattern shown in FIG. 2 was obtained. When this pattern was searched using an ASTM card, triiron tetroxide was confirmed and no other iron oxide was detected, and thus the component of the coating can be said to be triiron tetroxide.

Observation of the surface and cross section of this coating film with an electron microscope confirmed that the shape was very tight, had no missing parts, and had a uniform film thickness.

When the cross section of the film was measured by an X-ray microanalyzer, as shown in FIG.
It was confirmed that it reached the surface layer of the base material.

In addition, when the absorption of the test piece on which the coating was formed was examined by reflection IR, the presence of an organic substance was not recognized at all, and it was confirmed that polyalkylene polyamine and aliphatic oxycarboxylic acid were not contained in the coating. .

(F) Effects of the Invention According to the present invention, corrosion of iron-based metals in a soft water boiler water system, particularly pitting corrosion, can be prevented or significantly suppressed without performing a deoxygenation treatment. And even when a hardness leak occurs, these effects can be exhibited, and the generation of scale which can be caused by the hardness component can be synergistically prevented or suppressed.

Therefore, its usefulness in management of the operation of the soft water boiler is extremely large.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a test apparatus used for evaluating the water treatment method of the present invention, and FIG. 2 is an X-ray diffraction chart of an anticorrosion film formed when the water treatment method of the present invention is carried out. ,
FIG. 3 is a chart of the X-ray micro analyzer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadaoki Kanada 2-10-15 Higashiawaji, Higashiyodogawa-ku, Osaka, Osaka Inside Katayama Chemical Industry Laboratory Co., Ltd. (72) Inventor Sakae Katayama Higashiyodogawa-ku, Osaka-shi, Osaka Awaji 2-chome No. 15 Katayama Chemical Industry Laboratory Co., Ltd. (56) References JP-A-59-92097 (JP, A) JP-A-47-43702 (JP, A)

Claims (13)

(57) [Claims] (1) at least one compound selected from molybdic acid, tungstic acid, nitrous acid or an alkali salt thereof; (b) a compound capable of releasing an aliphatic oxycarboxylate ion in water; ) A heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water; and (d) a general formula: H ₂ N (CH ₂ CH ₂ NH) nH (where n is an integer of 2 to 5). A soft water boiler water treatment agent comprising, as an active ingredient, a polyamine or an acid addition salt thereof. 2. The water treatment agent according to claim 1, wherein the component (b) is citric acid, gluconic acid, malic acid or mannonic acid, or a sodium, potassium or ammonium salt thereof, or glucono-δ-lactone. 3. The component (c) is zirconyl chloride, zirconyl nitrate, zirconium sulfate, stannous chloride, stannic chloride, stannous sulfate, manganese chloride, manganese sulfate, nickel chloride, nickel sulfate or nickel nitrate. The water treatment agent according to claim 1. 4. The water treatment agent according to claim 1, wherein the component (d) is diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine or a salt thereof. 5. The water treatment agent according to claim 1, further comprising a water-soluble dispersant. 6. A soft water boiler water system comprising: (a) at least one compound selected from molybdic acid, tungstic acid, nitrous acid or an alkali salt thereof: 1 to 100 mg / (b) aliphatic oxycarboxylic acid in water (C) a heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water: 0.5 to 100 mg / as a metal ion; and (d) a general formula: H ₂ N ( CH ₂ CH ₂ NH) nH (wherein, n represents a polyamine or an acid addition salt thereof represented by the integer from 2 to 5): 20-5
000 mg /, is added individually or as a single preparation to prevent corrosion of iron-based metals in the water system of the soft water boiler. 7. The component (a) is 2.5 to 100 mg / component, the component (b) is 100 to 5000 mg / component, and the component (c) is 1.0 to 100 mg / component.
(D) The water treatment method according to claim 6, wherein the component is added in an amount of 50 to 5000 mg / day. 8. The water treatment method according to claim 6, wherein the component (b) is citric acid, gluconic acid, malic acid or mannonic acid or its sodium, potassium or ammonium salt, or glucono-δ-lactone. 9. The component (c) is zirconyl chloride, zirconyl nitrate, zirconium sulfate, stannous chloride, stannic chloride, stannous sulfate, manganese chloride, manganese sulfate, nickel chloride, nickel sulfate or nickel nitrate. 7. The water treatment method according to claim 6, wherein (10) The component (d) is diethylenetriamine,
Triethylenetetramine, tetraethylenepentamine,
The water treatment method according to claim 6, which is pentaethylenehexamine or a mineral salt thereof. 11. The water treatment method according to claim 6, wherein a water-soluble dispersant is further added. 12. The water treatment method according to claim 6, wherein the soft water boiler water system comprises undeoxidized water. 13. The water treatment method according to claim 6, wherein the soft water boiler water system comprises water having a total hardness of 20 mg / or more.