JPH0347982A - Water treating agent for soft water boiler and treatment of water - Google Patents

Abstract

PURPOSE:To prevent the corrosion, especially pitting corrosion of an iron-based metal in the water system of a soft water boiler and the formation of scale by using a water treating agent contg. molybdic acid or tungstic acid, aliphatic oxycarboxylic acid ions, a heavy metal compd. and polyamine as effective components. CONSTITUTION:This water treating agent for a soft water boiler contains a compd. selected among molybdic acid, tungstic acid, nitrous acid and alkali salts of the acids, a compd. capable of releasing aliphatic oxycarboxylic acid ions in water, a heavy metal compd. and polyamine or an acid adduct thereof as effective components. The heavy metal compd. releases Zr, Sn, Mn or Ni ions in water. The polyamine is represented by a general formula H2N(CH2CH2 NH)nH (where n is an integer of 2-5).

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a water treatment agent for soft water boilers and a treatment method. More specifically, the present invention relates to a soft water boiler water treatment agent and treatment method that can prevent corrosion, particularly pitting corrosion, of iron-based metals that come into contact with soft water in a boiler water system in which high-temperature soft water is used.

(b) Conventional technology Boilers generally include raw water boilers that use raw water such as industrial water and well water as is, soft water boilers, and pure water boilers, and in many cases, these = 3-boilers. The water temperature is set at 110° C. to the critical temperature under the pressure inside the boiler.

Among these, soft water boilers use water (soft water) from which most of the hardness components have been removed by ion exchange treatment, etc., so there is little scale formation even in highly concentrated water systems where this water is repeatedly recycled. However, components other than hardness components, especially anion components such as chlorine ions and sulfate ions, are not removed, and due to the presence of these anion components and dissolved oxygen in soft water, iron-based metals in the system corrode. However, pitting corrosion, which can lead to serious accidents, is likely to occur.

Therefore, in conventional soft water boilers, soft water is passed through a deaerator and deoxidized by adding oxygen scavengers such as sulfite and hydrazine. A method has been adopted to prevent corrosion of the above-mentioned iron-based metals, especially pitting corrosion, by adjusting I) H to 10 to 2 by adding an alkaline agent as necessary. deoxidation-alkali treatment method).

However, the above-mentioned deoxidation treatment-alkali treatment required frequent deoxidation treatment and was insufficient in preventing corrosion of iron-based metals.

Therefore, the applicant of the present application has previously proposed (a) one or more selected from molybdic acid and its alkaline salts, tungstic acid and its alkaline salts, and alkali salts of nitrous acid, and (b) aliphatic oxycarboxylic acid. an acid or an alkali salt thereof, (c) a compound that can easily release heavy metal ions in water, and (d) a molecular weight of 500 to 10,000.
A four-component anticorrosive agent containing a water-soluble polymer or copolymer of an olefin compound as an active ingredient (Japanese Patent Publication No. 62-5
No. 7715) and these four components further contain 2 to 2 carbon atoms.
Five-component anticorrosive agent containing 8 monoamines
-27157 Publication).

All of these anticorrosive agents create strong and dense Fe on the surface of iron-based metals in the water system of soft water boilers, which cannot be seen with normal anticorrosion treatments.
30a type black coating is formed to prevent corrosion. According to this treatment agent, corrosion of iron-based metals in a soft water boiler water system where anionic components are present, in particular, the occurrence of pitting corrosion, can be prevented without performing the above-mentioned deoxidation treatment. .

(c) Problems to be Solved by the Invention As mentioned above, the soft water used in soft water boilers has the hardness components substantially removed, so even in systems where it is recycled and reused, the total hardness is usually 1 mg/ It can be suppressed within σ.

However, in recent years, as the amount of evaporation and heat transfer load has increased relative to the water capacity of boilers, the processing capacity of water softeners that supply softened water is becoming insufficient, and ion exchange resins tend to deteriorate, resulting in the so-called hardness. Hardness leakage often occurs, and when such soft water is recycled, the hardness increases to 20 mg/Q or more.

When the anticorrosive agent disclosed in Japanese Patent Publication No. 62-27157 and Japanese Patent Publication No. 62-57715 mentioned above is added to a soft water boiler water system containing such hardness components, scale formation on the surface of ferrous metals may occur. Due to the adhesion, the formation of the black wave film is not uniform, and as a result, the corrosion prevention effect of iron-based metals may become insufficient, and this tendency becomes remarkable when the hardness component exceeds 20 mg/4. This invention was made to solve this problem, and even in soft water boiler water systems where hardness leaks may occur,
The present invention aims to provide a method that can reliably prevent corrosion of iron-based metals in a system without performing oxygen removal treatment.

(d) Means for Solving the Problems Thus, according to the present invention, (i) at least one compound selected from molybdic acid, tungstic acid, nitrous acid, or an alkali salt thereof; a compound capable of releasing oxycarboxylic acid ions, (c) a heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water, and (d) general formula: 13
．． N(CI(,C13.NH)nH (where n is 2 to 5
Provided is a soft water boiler water treatment agent containing a polyamine represented by (an integer of ) or an acid addition salt thereof as an active ingredient. Furthermore, according to this invention, the above components (a) to (d)
A method for treating soft water boiler water is provided, which comprises adding a specific amount of the following to a boiler water system.

This invention provides that, when specific amounts of the above components (a) to (d) are added to a soft water boiler water system, (1) a strong and dense corrosion-resistant Fe30-based black film is formed on the surface of iron-based metals in the boiler water system; This was achieved by discovering the fact that corrosion prevention treatment can be carried out without using any oxygen scavenger, and that the effects of ■ and ■ are similarly expressed in soft water boiler water systems with hardness leaks. It is something.

Note that even if only the three components (a), (b), and (c) are used, the above effects cannot be obtained at all. In addition, component (d) itself is known as a treatment agent for boiler water (Special Publication No. 5
0 to 35601), as in the present invention (A) to
It has not been previously known to use it in combination with component (iii), and it has also not been known at all that it forms a strong anti-corrosive black coating in the boiler water system.

The soft water boiler water system of the present invention refers to a system of a soft water boiler in which supplied boiler water exists or circulates.

In addition, boiler water here means water used for supply water to soft water boilers, and basically includes soft water and its concentrated water, but as mentioned above, it also includes water with hardness leaks. For example, the hardness component is 20 to 400 as total hardness.
It also includes those mixed up to about mg/Q. This invention is particularly effective when such hardness leaks.

The "alkali salt" in component (a) of this invention means alkali metal salts such as sodium and potassium salts and ammonium salts.

Component (a) used in this invention is molybdic acid, tungstic acid, nitrous acid, or an alkali salt thereof, and these are common compounds as oxidized anticorrosion components. Not only one kind of these may be used, but two or more kinds thereof may be used.

The (oral) ingredients used in this invention are compounds that can release aliphatic oxycarboxylic acid ions in water, and specific examples include citric acid, gluconic acid, malic acid, mannonic acid, and their sodium, potassium, and ammonium ions. Examples include salt. In addition to this, intramolecular condensates such as glucono-δ-lactone can also be used. Two or more types of these may also be used.

The component (c) used in this invention is zirconium in water,
Heavy metal compounds capable of releasing tin, manganese or nickel ions, such as zirconium chloride, zirconium sulfate, zirconium nitrate, zirconyl chloride, zirconyl nitrate, zirconylrum sulfate, stannous chloride, stannic chloride, stannous sulfate , chlorides such as manganese chloride, manganese sulfate, nickel chloride, nickel sulfate, nickel nitrate,
Examples include oxychlorides, nitrates, sulfates, etc.

Component (2) used in this invention is a polyamine or an acid addition salt thereof represented by the general formula: % (%) (where n is an integer of 2 to 5), such as diethylenetriamine, triethylenetetramine, tetra Ethylenepentamine, pentaethylenehexamine and their hydrochlorides,
Examples include nitrates and sulfates. Two or more of these components (ii) may also be used in combination.

Each component (a) to (d) is added to the soft water boiler water at a concentration of (a) component 1 to 1100 rz/(1, preferably 2.5 to IQQ).
H/ρ (b) component 50-500011? /l. Preferably, 1oO to 5000R9/e (c) component 0.5 to 1o
Off9/L preferably 1 to 100 mg/Q (knee) component 20 to 5000ff9/L preferably 50 to
It is added so that it becomes 5000ff9/l.

However, the component (c) is expressed in terms of metal ion equivalent.

Of these, if the amount of addition of at least component I is less than the minimum value, it is not suitable because a good corrosion prevention effect cannot be obtained even if an effective amount of the pond component is present, and the more the addition amount increases, the less this effect becomes. However, it is rare for economic reasons to require addition of more than the maximum value of each.

By adding the above-mentioned four components to a soft water boiler water system in the above-mentioned effective amounts, a strong anticorrosive film is formed on the iron-based metal surface of the soft water system. This film was confirmed to be made of triiron tetroxide, and that's it! The shape of No. 1 is very dense, with no missing parts and a film thickness similar to that of the film.

Furthermore, it has been confirmed that this triiron tetroxide coating has reached the surface layer of the base material (iron VI).

Moreover, since there is no organic substance such as polyamine, which is component (2), in this coating, component (2) is considered to have some kind of catalytic action. This coating is unaffected by the effects of anions present in boiler water (which has the effect of generating and promoting corrosion) and dissolved oxygen, and has the effect of preventing corrosion, eliminating the need for the addition of oxygen scavengers, which were previously essential. It has the advantage of being unnecessary.

Each of these components (a) to (d) may be added simultaneously or separately, but it is preferable to prepare a formulation containing these four components and then add it.

It is suitable that the blending ratio of such a preparation (soft water boiler water treatment agent) corresponds to the above-mentioned addition ratio, and usually, when the total amount of components (a) to (d) is 100 parts by weight, (i) ) Ingredients 0. O1 to 58.7 parts by weight, component (b) 0.95
99.6 parts by weight, component (c) 0.0052-58.5 parts by weight (metal ion equivalent), and component (d) 0.38 to 99.0 parts by weight. It is appropriate to leave it there.

From the viewpoint of workability, drug storage stability, etc., it is desirable that the soft water boiler water treatment agent of the present invention containing these four components be in the form of a liquid preparation. In this case, the preparation method is to first dissolve component (B) using an aqueous medium such as water or a mixed solvent of water/hydrophilic organic solvent as a solvent, and then add component (C) and dissolve by stirring thoroughly.

Next, add ingredient (d) and stir thoroughly.
b) It is desirable to add the ingredients and stir thoroughly to dissolve them.

The total concentration of components (a) to (d) in this solvent is 10
~70% by weight is suitable. Furthermore, it is preferable to mix component (b) and component (d) in a molar ratio of 6:1 to 10:1O from the viewpoint of forming a stronger anticorrosion coating.

When implementing 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 blended in the processing agent in advance.

Examples of such additives include water-soluble dispersants, pH
Examples include conditioning agents and anti-corrosion ingredients for ponds.

Among these, water-soluble dispersants include homopolymers containing acrylic acid, methacrylic acid, shishike, and maleic acid as monomers, copolymers of two or more of these, or other ethylenic polymers that can be copolymerized with any of the above. A copolymer with a compound having a double bond, containing 20m of the above monomer components.
A copolymer containing 1% or more of O, or a mixed polymer of two or more of these homopolymers and copolymers. Water-soluble polymers having a molecular weight of 500 to 100,000 are included. Such water-soluble polymers are used as one of the essential components of the four-component and five-component anticorrosive agents described in Japanese Patent Publications No. 62-57715 and No. 62-27157. However, in this invention, such a water-soluble polymer is not an essential component, and the effects of this invention are exhibited and a strong anticorrosive film is formed regardless of whether or not this water-soluble polymer is used. Therefore, in this invention, the water-soluble polymer is used mainly for the purpose of preventing or suppressing scale formation.

Other water-soluble dispersants that can be used include (1) (where k is θ~2, m is an integer from 2 to 6, M is a hydrogen atom, sodium or potassium, and the same or may be different) General formula (■): \P (OXOM).

(X is OH or NH2, M is a hydrogen atom, sodium or potassium and may be the same or different), a phosphonic acid represented by the general formula (II[) (M is a hydrogen atom, sodium or potassium 16-, m and n are positive integers and m+n=4 to 20)
Examples include phosphinic acid and amino-substituted phosphinic acids represented by the following structural formula (%).

Examples of pH adjusters that can be used in combination with this invention include alkali hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia for adjusting to the alkaline side, and hydrochloric acid, sulfuric acid, and nitric acid for adjusting to the acid side. etc. These pHi adjusters are optionally added depending on the optimum pH of the soft water boiler to which they are added. Note that if copper or aluminum-based metals are present in the system, addition of ammonia should be avoided. Also, the use of nitric acid and hydrochloric acid should generally be avoided.

Other suitable anticorrosive ingredients that can be used in combination with this invention include:
- Monoamines having 2 to 8 carbon atoms known as condensate corrosion inhibitors, such as propylamine, butylamine, morpholine, cyclohexylamine, ethanolamine, propatoolamine, aminomethylpropateol, and the like. However, although these are not directly involved in the formation of the anticorrosion coating in this invention, one preferred embodiment is that they are used to prevent corrosion in the steam condensate system of a boiler device. In addition, when forming a salt with component (a) or component (b), these may be used in the form of the salt.

(e) Examples This invention will be illustrated by the following formulation examples and test examples. The composition ratios of each formulation are all weight %, and the remainder is water.

(Margin below) Preparation (1) Sodium molybdate dihydrate gluconic acid (50%) Stannous chloride dihydrate diethylenetriamine: 1.0: 50.0 (as 50%): 1.0: 17 .0 After adding gluconic acid to water at the above mixing ratio, stannous chloride dihydrate was added, then sodium molybdate dihydrate,
Diethylenetriamine was sequentially added and dissolved to obtain a liquid preparation.

Formulation (2) Sodium molybdate dihydrate glucono δ lactone stannous chloride dihydrate diethylenetriamine 0 50 : 1.0 : 17.0 After dissolving glucono δ lactone in water at the above mixing ratio, Tin dihydrate, then sodium molybdate dihydrate, and diethylene triamine were added and dissolved in order,
A liquid preparation was obtained.

Formulation (3) Sodium molybdate dihydrate Malate Stannous chloride dihydrate Diethylenetriamine 5.15.0 0.5 :300 After dissolving malic acid in water at the above mixing ratio, stannous chloride 2 The aqueous salt, then sodium molybdate dihydrate, and diethylenetriamine were added and dissolved in this order to obtain a liquid preparation.

Formulation (4) Sodium molybdate dihydrate, citric acid l-hydrate, stannous chloride dihydrate, diethylene triamine: 0.7: 20.0 0.7: 30.0 In the above mixing ratio, citric acid l-hydrate in water =190, stannous chloride dihydrate, then sodium molybdate dihydrate, and diethylenetriamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (5) Sodium molybdate dihydrate, citric acid monohydrate, stannous chloride dihydrate, triethylenetetramine: 07: 20.0: 0゜7: 30.0 In the above mixing ratio, citric acid/l water in water After dissolving the salt, stannous chloride dihydrate, sodium molybdate dihydrate, and triethylenetetramine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (6) Sodium molybdate dihydrate, citric acid (l) hydrate, stannous chloride dihydrate (tetraethylenepentamine): 0.7: 20.0: 0.7 00 Add citric acid (l) to water at the above mixing ratio. After dissolving the salt, stannous chloride dihydrate, sodium molybdate dihydrate, and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (7) Sodium molybdate dihydrate, citric acid monohydrate, stannous chloride dihydrate, pentaethylenehexamine = 0.7 : 20.0 : 07 : 30.0 In the above mixing ratio, citric acid monohydrate in water After dissolving the salt, stannous chloride dihydrate, sodium molybdate dihydrate, and pentaethylenehexamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (8) Sodium tungstate dihydrate: 0.7 l citric acid
Water salt 20.02 Stannous chloride dihydrate: o7 Tetraethylenepentamine: 300 After dissolving citric acid monohydrate in water at the above blending ratio, stannous chloride dihydrate was added, and then tungsten Acid sodium dihydrate and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (9) Sodium tungstate dihydrate: 07 Citric acid l hydrate: 20.0 Stannous sulfate
:o, 7tetraethylenepentamine
: 30.0 After dissolving citric acid l hydrate in water at the above blending ratio, stannous sulfate, then sodium tungstate dihydrate, and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation. .

Formulation (10) Sodium molybdate dihydrate Citric acid lhydrate Zirconyl sulfate Tetraethylenepentamine 20,7: 20.0 0.7 30.0 Dissolve citric acid lhydrate in water at the above mixing ratio. After that, zirconyl sulfate, sodium molybdate dihydrate, and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Formulation (11) Sodium molybdate dihydrate, citric acid lhydrate, manganese sulfate heptahydrate, tetraethylenepentamine: 0.7:200:0.7:30.0 In the above mixing ratio, citric acid lhydrate in water. After dissolving manganese sulfate heptahydrate, sodium molybdate dihydrate, and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

3 4 Formulation (12) Sodium molybdate dihydrate Citric acid monohydrate Nickel sulfate heptahydrate Tetraethylenepentamine: 0.7 20.0 C17: 30.0 Citric acid monohydrate in water at the above mixing ratio After dissolving nickel sulfate heptahydrate, sodium molybdate dihydrate, and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Lithium and tetraethylenepentamine were sequentially added and dissolved to obtain a liquid preparation.

Preparation (14 sodium molybdate dihydrate: 0.7 citric acid l hydrate: 20.0 stannous chloride dihydrate
:0.7 triethylenetetramine :
aO,O Sodium polyacrylate: 2.0 (
Molecular weight - approx. 80000) Formulation (13) Sodium nitrite citrate l hydrate stannous chloride dihydrate tetraethylene pentamine = 0.7: 20.0: 0.7: 30.0 At the above blending ratio, water After dissolving citric acid l hydrate in the solution, stannous chloride dihydrate, sodium molybdate dihydrate, triethylenetetramine, and sodium polyacrylate were sequentially added and dissolved to obtain a liquid preparation.

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

*1. Phosphinic acid has the following structure.

After dissolving citric acid hydrate in water at the above mixing ratio, stannous chloride dihydrate was added, followed by sodium molybdate dihydrate, triethylenetetramine, and acrylic acid methacrylic acid copolymer in order. A liquid preparation was obtained.

Formulation (16) Sodium molybdate dihydrate, citric acid l-hydrate, stannous chloride dihydrate, triethylenetetramine phosphinic acid = 07: 20.0 = 0.7 230.0: 2.0 in the above mixing ratio , After dissolving citric acid hydrate in water, stannous chloride dihydrate was added to the water. Examples [(17) to (19)] Preparation (17) Sodium gluconate: 20 Sodium hydroxide = monostannic chloride dihydrate
: Sodium monomolybdate dihydrate :
l Sodium polyacrylate: 2 Sodium gluconate is dissolved in water at the above mixing ratio, and then sodium hydroxide, stannous chloride dihydrate, sodium molybdate dihydrate, and sodium polyacrylate ( (molecular weight approximately 8,000) were added one after another to obtain a liquid preparation.

Formulation (18) Sodium gluconate = 20 sodium hydroxide: l stannous chloride dihydrate
: 1 Sodium molybdate dihydrate : 1
Morpholine: 10 Sodium polyacrylate: 2 (molecular weight approximately 8000) Dissolve sodium gluconate in water at the above blending ratio,
Next, sodium hydroxide, stannous chloride dihydrate, sodium molybdate dihydrate, morpholine, and sodium polyacrylate (molecular weight about 8,000) were added in sequence to obtain a solution.

Formulation (19) (Deoxygenation-alkali treatment) Potassium pyrophosphate Sodium hydroxide Hydrazine hydrate (80% content) Sodium polyacrylate (molecular weight approximately 8000): 12:50 Dissolve potassium pyrophosphate in water at the above blending ratio. , followed by sodium hydroxide, hydrazine hydrate (containing 80%),
Sodium polyacrylate (molecular weight approximately 8000) was sequentially added to obtain a liquid preparation.

Test Example (Test example to confirm corrosion prevention and scale adhesion prevention effect on iron-based heat transfer surfaces during hardness leakage) A test was conducted using the test apparatus shown in FIG. 1.

In the figure, l is a softener, 2.8 is a heat exchanger, 3 is a downcomer that constitutes the center of the boiler body, 4 is the bottom of the boiler, 5 is a heat transfer test tube, 6 is an evaporation tube, and 7 is steam Reservoirs and 9 indicate water supply tanks.

The water supply tank 9 was replenished with test water, and then a predetermined amount of the test agent was added. This water is supplied to the test boiler main body by a pump. In the boiler main body, the test water is heated by the heat transfer test tube (heating section) shown in FIG. 1 and turned into steam, which is discharged outside the boiler system and the boiler water is concentrated.

Preparation of test aquatic plants: Osaka City tap water was used in a softener as shown in Fig. 1 to remove hard components from the water, and 240σ of Osaka City tap water was added to 560Q water to prepare test water. The results of water quality analysis at this time are shown in Table 1.

Table-1 Test water quality *1 CaCO, l conversion value Test conditions Test time Near hour/day (including temperature rise, 1 hour, temperature drop: 1 hour) x 20 days - 140 hours at specified test pressure lO
The time for K97cm'' is 100 hours if you drive 7 hours/day for 20 days.

Test pressure crab 10Kg/cm' Test tube material: 5TPG38 Heat transfer load (heat transfer surface evaporation rate): No, 1 heat transfer tube = approx. 170Kg/m' -h・
- High load No. 2 heat exchanger tube - Approx. 80Kg/m2. h・
,,Low load No. 3 heat exchanger tube - approx. 170Kg/m' ・
h-・High load (-The evaporation rate of the heat transfer surface of a boat-fished boiler is 60
~97m'・h in ~100, recently 100Kg/m'
・Some exceed h. ) Heat exchanger tube area: 0.026+++” (No, 1~2
Heat exchanger tube) Storage water amount: 1Of2 Evaporation amount: Approximately 7 to 9/h Blow rate: Approximately 5% (intermittent) Test water quality: Osaka city water softened water 70% 10 Osaka city Mizuhara water 30% 31 32- Hardness component = total hardness The hardness is approximately 16zy/ρ, and the normal value at the time of hardness leak is 2 to 4 m9cacO3/Q.

Confirmation of test results After the test was completed, the heat transfer test tube under high load was taken out and the amount of scale adhesion (1 g), number of pittings (pieces/dm), presence or absence of coating, and analysis were conducted.The test results are summarized in Table 2. Shown below.

Note) Test Nos. 1 to 19 are the above formulations (1) to (19).
These are the test results using . Preparations (1) to (16) and (19) were mixed in boiler water at a concentration of 1ooOff9/l, and preparations (17) and (18) were washed at 2000 tons in the same way.
It was added so that it became tr9IQ.

All addition amounts in the table are concentrations in boiler water.

*I. The scale adhesion index was calculated from the average weight of calcium adhering to high-load heat transfer parts No. 1 and No. 3 using the following formula.

Scale adhesion index = × 100

Claims (13)

[Claims] 1. (a) at least one compound selected from molybdic acid, tungstic acid, nitrous acid, or alkali salts thereof; (b) a compound capable of releasing aliphatic oxycarboxylic acid ions in water; (c) zirconium in water; A heavy metal compound capable of releasing tin, manganese or nickel ions, and (d) General formula: H_2N(CH_2CH_2NH)_n
A soft water boiler water treatment agent containing glyamine or its acid addition salt represented by H (where n is an integer of 2 to 5) as an active ingredient. 2. 2. The water treatment agent according to claim 1, wherein 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. (c) The component is zirconyl chloride, zirconyl nitrate,
The water treatment agent according to claim 1, which is zirconium sulfate, stannous chloride, stannic chloride, stannous sulfate, manganese chloride, manganese sulfate, nickel chloride, nickel sulfate, or nickel nitrate. 4. 2. The water treatment agent according to claim 1, wherein component (d) is diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, or a mineral acid salt thereof. 5. The water treatment agent according to claim 1, further comprising a water-soluble dispersant. 6. In the soft water boiler water system, (a) at least one compound selected from molybdic acid, tungstic acid, nitrous acid, or an alkali salt thereof: 1 to 100 mg/l; (b) releasing aliphatic oxycarboxylic acid in water; (c) Heavy metal compound capable of releasing zirconium, tin, manganese or nickel ions in water: 0.5 to 100 mg/l as metal ions, and (d) General formula: H_
2N(CH_2CH_2NH)_nH (where n is 2 to
A polyamine represented by (an integer of 5) or an acid addition salt thereof:
A method for treating water in a soft water boiler, characterized in that 20 to 5000 mg/l of the following are added individually or as a single preparation to prevent corrosion of iron metals in the water system of the soft water boiler. 7. (a) component is 2.5 to 100 mg/l, (b) component is 100 to 5000 mg/l, (c) component is 1.0 to 1
7. The water treatment method according to claim 6, wherein the component (d) is added in an amount of 50 to 5000 mg/l. 8. 7. 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. (c) The component is zirconyl chloride, zirconyl nitrate,
7. The water treatment method according to claim 6, which is zirconium sulfate, stannous chloride, stannic chloride, stannous sulfate, manganese chloride, manganese sulfate, nickel chloride, nickel sulfate, or nickel nitrate. 10. 7. The water treatment method according to claim 6, wherein component (d) is diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, or a mineral acid salt thereof. 11. 7. The water treatment method according to claim 6, wherein a water-soluble dispersant is further added. 12. 7. The water treatment method according to claim 6, wherein the soft water boiler water system comprises non-deoxygenated treated water. 13. 7. The water treatment method according to claim 6, wherein the soft water boiler water system comprises water having a total hardness of 20 mg/l or more.