JP3401909B2 - Water-based metal corrosion inhibitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is corrosion inhibition instrumentation metal aqueous
In particular, an apparatus that suppresses corrosion of metals such as mild steel in a water system, stainless steel, copper, and copper alloy by performing anion exchange treatment, and prevents precipitation of scale in the anion exchange resin tower, The present invention relates to a device for continuing stable and efficient processing for a long period of time.

[0002]

2. Description of the Related Art Open and closed circulating cooling water system,
BACKGROUND ART Mild steel, stainless steel, copper, copper alloys and the like are used as a base material for various devices and pipes used in water systems such as heat storage water systems and closed cold / hot water systems. These base materials used for immersion in water are chlorinated (C
l ^-), sulfate ion (SO ₄ ^2-), nitrate ion (N
O ₃ ^-) is corroded by such, to generate pitting. Therefore,
In order to suppress the corrosion of the metal material in contact with such an aqueous system, conventionally, as corrosion inhibitors, chromate, molybdate, nitrite, phosphate, phosphonate, zinc salt, benzotriazole, tolyltriazole. , Mercaptobenzothiazole, etc. are available.

Also, a method of treating an aqueous system with an OH type anion exchange resin having chromium ions and zinc ions adsorbed as an anticorrosion agent and eluting the anticorrosion agent in water to prevent corrosion (Japanese Patent Publication No. 4).
No. 8-39704) is also proposed.

However, when water containing the above corrosion inhibitor is released to the outside of the system, it may cause environmental pollution. Also, in the method described in JP-B-48-39704, there is concern that the eluted chromium and zinc ions may affect the environment.

As a method for solving such conventional problems and effectively preventing corrosion of water-based metals without causing problems such as environmental pollution, the present applicant has previously proposed that water-based corrosive ions A method has been proposed in which the contained water is brought into contact with an anion exchanger carrying an anticorrosive anion, and a low molecular weight polymer is added to the water system (Japanese Patent Application No. 4-3184).
No. 38. Hereinafter referred to as "first application". ).

That is, according to the method of the prior application, raw water is directly passed through the anion exchange resin regenerated in the form of OH ⁻ or HCO ₃ ⁻ which is an anticorrosive anion to obtain a corrosive anion (Cl ⁻ ,
(NO ₃ ⁻ , SO ₄ ^2−, etc.) is removed by ion exchange.

[0007]

However, according to the method of the prior application, when raw water containing the hardness component (water to be treated) is directly passed through the anion exchange resin, scale (precipitation) occurs in the resin tower. In particular, when the ionic form of the anion exchange resin is the OH ⁻ form, the generation of this scale is remarkable.

This scale can be removed by regenerating the resin with hydrochloric acid or sulfuric acid, but in this case, two types of alkali metal salts of anticorrosive anions and mineral acids are required as regenerants, and in terms of equipment. There was a problem that it became complicated in terms of operation.

On the other hand, in the case where the water to be treated of the strongly basic anion exchange resin contains Mg ions unless regeneration with mineral acid is carried out (normal raw water contains Mg ²⁺ ). Due to the pH change in the resin tower, Mg ions
(OH) ₂ is deposited and precipitates, and due to the rise of the differential pressure, the operation of the resin tower cannot be continued until long.

The present invention prevents scale formation in a resin tower in an apparatus for suppressing corrosion of an aqueous metal by treatment with such an anion exchange resin without using a mineral acid,
It is an object of the present invention to provide a water-based metal corrosion inhibitor capable of continuing stable and efficient treatment for a long period of time.

[0011]

Corrosion inhibiting system of the metal of the aqueous of the invention To achieve the above object, according to a corrosion inhibiting device for a metallic aqueous corrosive ions supplied to a corrosive ion-containing water or water-based water-based Means for adding a low molecular weight polymer to the contained water,
The low molecular weight polymer is added water, means for creating come in contact with the carrying anticorrosion anionic strong base anion exchange resin
And having .

The present invention will be described below in detail with reference to the drawings.

[0013] Figure 1 is a system diagram showing an embodiment of an aqueous metal corrosion inhibiting device <br/> of the present invention.

The apparatus of this embodiment is provided with Cl ⁻ , S in the storage tank 1.
The treated water containing corrosive ions such as O ₄ ²⁻ and NO ₃ ⁻ and the hardness component, that is, the corrosive ion-containing water extracted from the water system or the corrosive ion-containing water supplied to the water system, has a lower molecular weight than the pipe 11. Water to be treated to which a polymer has been added and a low molecular weight polymer has been added is passed through the pipe 12 to the strongly basic anion exchange resin tower 2 for treatment, and the treated water flowing out from the pipe 13 is returned or supplied to the water system. Is.

Reference numeral 14 is a pipe for introducing the regenerant of the strongly basic anion exchange resin, and 15 is a pipe for discharging the regeneration waste liquid.

In the present invention, the low molecular weight polymer has a molecular weight of 500 to 100,000, particularly 1000 to 2
A water-soluble polymer of about 10,000, specifically, a maleic acid-isobutylene copolymer, a polyacrylic acid, a partial hydrolyzate of polyacrylamide, an acrylic acid-allyloxy-2-hydroxypropanesulfonic acid copolymer, Acrylic acid-hydroxyethyl methacrylic acid copolymer, acrylamide and allyl sulfonic acid copolymer, acrylic acid-maleic acid copolymer, acrylic acid-styrene copolymer, acrylic acid-styrene sulfonic acid copolymer, polymaleic acid, Polystyrene sulfonic acid, acrylic acid-itaconic acid copolymer, polyitaconic acid, acrylic acid-acrylonitrile copolymer, acrylic acid-vinyl sulfonic acid copolymer, known low molecular weight polymers such as methyl vinyl ether-maleic acid copolymer. To be

The addition amount of such a low molecular weight polymer varies depending on the water quality of the water to be treated, but is usually 0.1 to 500 mg / l with respect to the water to be treated.

Further, the anticorrosion anion carried on the strongly basic anion exchange resin which is brought into contact with the water to be treated to which the low molecular weight polymer is added is dissolved in water by ion exchange even if it does not exhibit anticorrosion, Refers to an anion capable of forming an anticorrosive film by reacting with a dissolved cation in water. OH
^{_{-, HCO 3 -, CO 3}} 2- and the like. Therefore, the method of the present invention can be easily carried out using a strongly basic anion exchange resin having an ionic form of OH ⁻ form, HCO ₃ ⁻ form or CO ₃ ²⁻ form.

[0019] No particular limitation is imposed on the method for contacting with the low molecular weight polymer treatment water corrosion resistance anion loaded with strongly basic anion exchange resin added, but in general, as shown in FIG. 1, OH ^- form, CO ₃ ^2- form or HCO ₃ ^- is preferable to passed through contact with the strongly basic anion exchange packed column resin was filled in the form, water passing conditions of this case, as appropriate depending on the water quality of the water to be treated It is determined.

If the ion exchange performance of the strongly basic anion exchange resin is lowered by continuing the water flow, N
Regeneration is performed with a regenerant such as aOH, NaHCO ₃ , Na ₂ CO ₃ . In the present invention, since the regeneration of the scale in the resin tower is prevented by the action of the low molecular weight polymer, the strongly basic anion exchange resin can be reused by the regeneration with the regenerant, without causing an increase in the differential pressure. Can be used repeatedly over a long period of time.

[0021] ^Cl as apparatus, corrosive ions such invention _{^{-, SO 4 2-, NO 3}} - while containing, aqueous containing ^{Mg 2+,} etc. as hardness components, for example corrosion of the freshwater-based metal It is extremely effective for suppression.

In the present invention, if necessary,
Inorganic phosphates (orthophosphates and polymeric phosphates), organic phosphates, phosphonic acids, zinc, nickel salts, tungstates, molybdates, nitrites, borates, silicates, oxycarboxylic acids Corrosion inhibitors such as acid salts, benzotriazole, and mercaptobenzothiazole, scale inhibitors such as lignin derivatives, tannic acids, and polysaccharides such as tempun may be added together with the ion-exchange treated water.

[0023]

Function: Corrosive ions in water such as Cl ⁻ , SO ₄ ²⁻ , NO ₃ ⁻ are brought into contact with a strongly basic anion exchange resin carrying anticorrosion anions such as CO ₃ ²⁻ , HCO ₃ ⁻ , OH ^−. by ion exchange Te, water corrosive ions OH ^-,
It is ion-exchanged with anticorrosive anions such as HCO ₃ ⁻ and CO ₃ ²⁻ , the content thereof is reduced, and the corrosiveness of the water system is reduced.

In the present invention, since the low molecular weight polymer is added to the water to be treated before the ion exchange,
Due to the scale inhibition effect of this low molecular weight polymer,
Generation of scale in the resin tower is prevented, and stable and efficient water flow can be continued for a long period of time.

By the way, the addition of the low molecular weight polymer
OH eluted in water by ion exchange^- , HC
O₃ ^-, CO₃ ^2- Anticorrosive anions such as C and water-derived C
a²⁺, SiO ₂ A water-based anticorrosive film with a uniform anticorrosive component
Effectively forms on the metal surface of the
Although it has the effect of suppressing it, ION
Low molecular weight polymer added to the water to be treated before the exchange treatment
-Removing corrosive ions from strongly basic anion exchange resin
Strongly basic with little effect on performance
Adsorbed on anion exchange resin and almost removed from water
It will not be

Therefore, in the present invention, the added low molecular weight polymer migrates into the ion-exchange treated water as it is, and effectively exhibits the anticorrosive action and scale inhibiting action by forming the anticorrosive film in the water system.

[0027]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 Raw water 1 of the water quality shown in Table 1 to which an isobutylene-maleic acid copolymer (molecular weight 6,500) was added as a low molecular weight polymer was treated as water to be treated in the following strong basic anion exchange resin tower. Water was passed at a flow rate of liter / hr.

Strongly basic anion exchange resin tower Resin used: Diaion SA20A (Mitsubishi Kasei Co., Ltd.)
Regeneration level: 66 g of NaOH (calculated as CaCO ₃ ) / liter-resin resin amount: 100 ml Column specifications: inner diameter 28 mm, height 250 mm glass column ion-exchange treated water Cl ⁻ concentration change with time, low molecular weight polymer concentration with time. The change and the change over time in the differential pressure in the column are shown in FIGS. 2, 3 and 4, respectively. The BTC value of the strongly basic anion exchange resin with respect to the corrosive anions was 17.2 g (calculated as CaCO ₃ ) / liter-resin.

Comparative Example 1 Raw water 2 of water quality shown in Table 1 to which a low molecular weight polymer was not added
Was treated in the same manner as in Example 1.

The changes in the Cl ⁻ concentration of the ion-exchange treated water with time and the changes in the differential pressure in the column with time are shown in FIGS. 5 and 4, respectively.
Shown in. The BTC value for the corrosive anion of the strongly basic anion exchange resin is 16.2 g (calculated as CaCO ₃ ).
/ Liter-resin.

[0032]

[Table 1]

From the results shown in FIGS. 2 to 5, the following is clear.

That is, from the comparison between FIG. 2 and FIG. 5, the ion exchange treated water of the raw water 1 to which the low molecular weight polymer was added and the ion exchange treated water of the raw water 2 to which the low molecular weight polymer was not added had almost the same degree. The change in Cl ⁻ concentration is shown, and it is clear that the addition of the low molecular weight polymer does not affect the ability of the strongly basic anion exchange resin to remove the corrosive anions.

Further, from FIG. 3, the low molecular weight polymer is adsorbed by the resin in the initial stage of water flow, but after a while, the concentration of the low molecular weight polymer in the ion-exchange treated water becomes equal to the concentration of the low molecular weight polymer of the raw water 1, and the low molecular weight polymer is It is clear that is transferred to the ion-exchange treated water without being adsorbed by the resin.

Further, as is clear from FIG. 5, in the raw water 1 to which the low molecular weight polymer was added, the column pressure difference was 0.1.
Although it is constant at kg / cm ² , in raw water 2 to which the low molecular weight polymer is not added, the differential pressure of the column increases with time. It should be noted that precipitation of scale was observed in the column through which the raw water 2 was passed, and when the precipitate was collected and analyzed, most of it was Mg (OH) ₂ . From this result, it is clear that the addition of the low molecular weight polymer effectively prevents the scale deposition in the resin tower.

[0037]

As described above in detail, according to the corrosion inhibiting system of the metal of the water of the present invention, a corrosive ion-containing water supplied to the corrosive ion-containing water or an aqueous water-based carrying anticorrosion anion is removed by ion exchange corrosive ions is contacted with a strongly basic anion exchange resin, per the inhibiting corrosion of aqueous metal, effectively prevent the deposition of scale in a strongly basic anion exchange resin tower Therefore, stable and efficient ion exchange treatment can be performed for a long period of time. In addition, the corrosion-preventing film-forming action of the low-molecular weight polymer can more reliably prevent corrosion in the water system and also effectively prevent precipitation of scale in the water system.

[Brief description of drawings]

[1] form of implementation of the water-based metal corrosion inhibiting system of the present invention
It is a systematic diagram showing a state .

FIG. 2 is a graph showing the change over time in the Cl ⁻ concentration of ion-exchange treated water in Example 1.

FIG. 3 is a graph showing the change over time in the low molecular weight polymer concentration of ion-exchange treated water in Example 1.

FIG. 4 is a graph showing changes over time in the differential pressure in the column in Example 1 and Comparative Example 1.

FIG. 5 is a graph showing the change over time in the Cl ⁻ concentration of ion-exchange treated water in Comparative Example 1.

[Explanation of symbols]

1 storage tank 2 Strongly basic anion exchange resin tower

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23F 11/173 C02F 1/42 C02F 5/08 C23F 15/00

Claims (2)

(57) [Claims] 1. Inhibition of corrosion of water-based metalapparatusAndThe Water containing corrosive ions in water system or spoilage supplied to the water system
Addition of low molecular weight polymer to water containing food ionsMeans to do
When, The low molecular weight polymer was added waterToAnticorrosion anion
Strongly basic anion exchange resinContact withTouchmeans
HaveInhibition of corrosion of water-based metals characterized byDress
Setting. 2. The method according to claim 1, which is extracted from the water system.
Containing corrosive ions Containing corrosive ions supplied to water or water system
A pipe for adding low molecular weight polymer to water, and a low molecular weight
Anti-corrosion anion through which water containing polymer is passed
Packed with strong basic anion exchange resin
The tower and the treated water flowing out from the packed tower are returned or supplied to the water system.
A water-based metal corrosion
Food suppression device.