JP2007117876A - Scale adhesion preventing agent and treatment method of cooling water system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively inhibit scale adhesion caused by suspended solid, in a cooling waster system where the suspended solid exists in water. <P>SOLUTION: A polymer of maleic acid and/or a water-soluble salt of maleic acid, and a copolymer of one or more kinds of monomer components selected from a group consisting of (meth)acrylic acid and its water-soluble salts, one or more kinds of monomer components selected from monoethylenic unsaturated sulfonic acid monomers, and one or more kinds of monomer components selected from a group consisting of (meth)acrylamide and substituted (meth)acrylamide are added to the cooling waster system where the suspended solid exists in water, which inhibits the scale adhesion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a scale adhesion preventing agent and a method for treating a cooling water system, and in particular, a scale adhesion preventing agent for preventing a scale failure in a cooling water system in which suspended substances exist in water, and cooling using the scale adhesion preventing agent. The present invention relates to an aqueous processing method.

  When the suspended water is contained in the cooling water, the stable operation of the cooling water system is hindered due to the adhesion of the scale caused by the suspended material. Such scales vary depending on the situation, but are composed of various components including calcium, magnesium, silica, aluminum, iron, ignition loss, anhydrous carbonic acid and the like.

Conventionally, as a technique for preventing such scale, various scale adhesion preventing agents have been added to cooling water. For example, Japanese Patent No. 3055815 discloses any one of the following 1 to 4 as an aqueous system. Describes a method for preventing silica scale added to.
1. 2. A mixture of a copolymer 2.1 of (meth) acrylic acid, (meth) acrylamidomethylpropanesulfonic acid and substituted (meth) acrylamide, and aluminum ions or magnesium ions. 3. Mixture of polyacrylic acid (salt) or polymaleic acid (salt) and aluminum ion or magnesium ion Magnesium ion
Japanese Patent No. 3055815

  However, the additive described in Japanese Patent No. 3055815 alone does not provide a sufficient scale prevention effect, and its improvement is desired.

  Accordingly, the present invention provides a scale adhesion preventive agent for effectively suppressing the adhesion of scale due to suspended substances in a cooling water system in which suspended substances exist in water, and cooling using the scale adhesion preventive agent. An object is to provide an aqueous treatment method.

  The scale adhesion preventing agent of the present invention (Claim 1) includes maleic acid and / or a polymer of a water-soluble salt of maleic acid (hereinafter referred to as “polymer A”), (meth) acrylic acid, and water-soluble thereof. Monomer selected from the group consisting of organic salts (hereinafter referred to as “monomer component b1”) and a monomer selected from monoethylenically unsaturated sulfonic acid monomers One or more components (hereinafter referred to as “monomer component b2”) and a monomer component selected from the group consisting of (meth) acrylamide and substituted (meth) acrylamide (hereinafter “monomer component”) and a copolymer (hereinafter referred to as “Polymer B”).

  The scale adhesion preventive agent according to claim 2 contains the polymer A and the polymer B in the ratio of polymer A: polymer B = 1: 4 to 9: 1 in a solid content concentration ratio in claim 1. Features.

  The scale adhesion inhibitor according to claim 3 is characterized in that, in claim 1 or 2, the monomer component b2 is 2-acrylamido-2-methylpropanesulfonic acid.

  The scale adhesion inhibitor according to claim 4 is characterized in that the monomer component b3 is N-tert-butylacrylamide in any one of claims 1 to 3.

  The cooling water system treatment method of the present invention (Claim 5) is a cooling water system treatment method that suppresses the adhesion of scale in a cooling water system in which suspended substances exist in water, and the cooling water system contains maleic acid and / or maleic acid. A polymer of a water-soluble salt of an acid (hereinafter referred to as “polymer A”), a monomer component selected from the group consisting of (meth) acrylic acid and a water-soluble salt thereof (hereinafter “monomer component b1”). 1 type or 2 types or more and a monomer component selected from monoethylenically unsaturated sulfonic acid monomers (hereinafter referred to as “monomer component b2”). A copolymer (hereinafter referred to as “one” or two or more types of monomer components selected from the group consisting of (meth) acrylamide and substituted (meth) acrylamide (hereinafter referred to as “monomer component b3”). "Polymer B") is added. To.

  The method for treating a cooling water system according to claim 6 is the method according to claim 5, wherein the polymer A and the polymer B are cooled at a solid content concentration ratio of polymer A: polymer B = 1: 4 to 9: 1. It is added to an aqueous system.

  The cooling water processing method according to claim 7 is characterized in that, in claim 5 or 6, the monomer component b2 is 2-acrylamido-2-methylpropanesulfonic acid.

  The cooling water treatment method according to claim 8 is characterized in that in any one of claims 5 to 7, the monomer component b3 is N-tert-butylacrylamide.

  According to the present invention, two types of polymers, that is, a polymer A that is a component that suppresses the adhesion of scale in a state where there is no influence of the suspended substance, and a component that suppresses the adhesion of scale caused by the suspended substance By using together with a certain polymer B, it is possible to effectively suppress the adhesion of scale regardless of the presence or absence of the influence of suspended substances and contribute to the stable operation of the cooling water system.

  Embodiments of the scale adhesion inhibitor and cooling water processing method of the present invention will be described in detail below.

  In the present invention, “(meth) acryl” refers to both “acryl” and “methacryl”. “Molecular weight” refers to “weight average molecular weight”.

[Polymer A]
The polymer A is a component that suppresses the adhesion of scales in a state where there is no influence of suspended substances, and is made of a polymer of maleic acid and / or a water-soluble salt of maleic acid.

  Here, examples of the water-soluble salt of maleic acid include sodium maleate, potassium maleate, and ammonium maleate.

  The molecular weight of the polymer A is preferably in the range of 500 to 5000, particularly 800 to 1500.

[Polymer B]
The polymer B is a component that suppresses the adhesion of the scale caused by the suspended substance, and is a monomer component selected from the group consisting of (meth) acrylic acid and water-soluble salts thereof (hereinafter “monomer component b1”). 1 type or 2 types or more and a monomer component selected from monoethylenically unsaturated sulfonic acid monomers (hereinafter referred to as “monomer component b2”). And a copolymer of one or more monomer components selected from the group consisting of (meth) acrylamide and substituted (meth) acrylamide (hereinafter referred to as “monomer component b3”).

<Monomer component b1>
Examples of the water-soluble salt of (meth) acrylic acid as the monomer component b1 include sodium salt, potassium salt and ammonium salt of (meth) acrylic acid.

<Monomer component b2>
As the monoethylenically unsaturated sulfonic acid monomer of the monomer component b2, (meth) acrylamidomethylpropanesulfonic acid is preferable, and those represented by the following general formula (1) are particularly preferable. 2-methylpropanesulfonic acid is preferred.

（式中、Ｒ^１はＨ又はＣＨ_３であり、Ｒ^２は炭素数１〜８のアルキレン基又はフェニレン基であり、Ｒ^３はＨ又は炭素数１〜４のアルキル基であり、Ｘ^１は水素又は１価の金属陽イオン（例えば、Ｎａ，Ｋ等）である。）

(In the formula, R ¹ is H or CH ₃ , R ² is an alkylene group having 1 to 8 carbon atoms or a phenylene group, R ³ is H or an alkyl group having 1 to 4 carbon atoms, and X ¹ is Hydrogen or a monovalent metal cation (for example, Na, K, etc.))

<Monomer component b3>
As substituted (meth) acrylamide of monomer component b3, what is represented by following General formula (2) is preferable, and N-tert- butylacrylamide is especially preferable.

（式中、Ｒ^４はＨ又はＣＯＯＸ^２（Ｘ^２はＨ又は１価の金属陽イオン（例えば、Ｎａ，Ｋ等）を表す。）を表し、Ｒ^５は、Ｈ又はＣＨ_３を表し、Ｒ^６，Ｒ^７は各々独立にＨ又は炭素数１〜８のアルキル基を表す。ただし、Ｒ^６，Ｒ^７が同時にＨであることはない。）

(Wherein R ⁴ represents H or COOX ² (X ² represents H or a monovalent metal cation (eg, Na, K etc.)), R ⁵ represents H or CH ₃ , R ⁶ and R ⁷ each independently represent H or an alkyl group having 1 to 8 carbon atoms, provided that R ⁶ and R ⁷ are not H at the same time.)

<Monomer component ratio>
The content ratio of each monomer component in the polymer B is mol%. Monomer component b1: Monomer component b2: Monomer component b3 = 30 to 92: 5 to 40: 3 to 30
In particular, monomer component b1: monomer component b2: monomer component b3 = 50 to 90: 7 to 20: 3 to 30
It is preferable that

<Molecular weight>
The molecular weight of the polymer B is preferably in the range of 1000 to 25000, particularly 2000 to 10,000.

[Solid content concentration ratio]
It is preferable that the polymer A and the polymer B are added to the water system to be treated so that the solid content concentration ratio is polymer A: polymer B = 1: 4 to 9: 1.

  When the proportion of the polymer A used is larger than the above range and the polymer B is small, there is a possibility that it is greatly affected by the suspended matter. Conversely, when the polymer B is large and the polymer A is small, depending on the water quality, There is a concern that calcium scale is deposited.

  Therefore, it is preferable that the scale adhesion preventing agent of the present invention containing the polymer A and the polymer B contains the polymer A and the polymer B in the above range.

  In addition, the scale adhesion preventing agent of the present invention may be prepared by mixing the polymer A and the polymer B in advance, or may be provided separately.

[Addition concentration and addition method]
The addition concentration of the polymer A and the polymer B is set to such a concentration that a sufficient scale suppression effect can be obtained in consideration of the water quality and operating conditions of the treatment target water system. It is desirable that the total concentration of the polymer A and the polymer B is 1 to 500 mg / L, particularly 5 to 100 mg / L in terms of the holding concentration (concentration in terms of solid content).

  The polymer A and the polymer B may be added individually so that the solid content concentration ratio and the addition concentration are within the above-mentioned preferable range, and the polymer A and the polymer B are mixed in advance at a predetermined ratio. You may add what you did. When polymer A and polymer B are added separately, they may be added at the same location or at different locations.

  In the present invention, other corrosion inhibitors, scale inhibitors, dispersants, slime controls are used as long as each treatment efficiency obtained when polymer A and polymer B are added to the water system to be treated is not hindered. An agent, a release agent, an antifoaming agent, and the like may be used in combination, and may be used in combination with various water treatment devices such as a filter. For example, when a copper material is included in the aqueous system, the anticorrosion performance for the copper material can be improved by using an azole derivative such as benzotriazole or tolyltriazole in combination.

  Therefore, the scale adhesion preventing agent of the present invention contains, in addition to the polymer A and the polymer B, these other corrosion inhibitors, scale inhibitors, dispersants, slime control agents, release agents, antifoaming agents, and the like. It may be a thing.

[Treatment target water system]
Examples of the water system to be treated of the present invention include a cooling water system in which suspended substances are present in water, and examples thereof include an open circulation cooling water system using industrial water as makeup water.

  Among such cooling water systems, in the open circulation cooling water system, the scale adhesion preventing agent of the present invention may be added to the pit of the cooling tower.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Examples 1 to 5, Comparative Examples 1 and 2
[Scale adhesion inhibitor]
The following were prepared as the polymer A and the polymer B.
<Polymer A>
Polymylene acid Molecular weight: 1000
<Polymer B>
Copolymer of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid and N-tert-butylacrylamide Acrylic acid: 2-acrylamido-2-methylpropanesulfonic acid: N-tert-butylacrylamide (molar ratio) = 77:12:11
Molecular weight = 10000
Polymer A and Polymer B have the following solid content concentration ratio, and the addition concentration (water-based retention concentration (converted to solid content)) is 20 mg / mg in total of Polymer A and Polymer B. It added so that it might become L.

[Evaluation equipment]
Using the cooling water system evaluation test apparatus outlined in FIG. 1, the scale prevention effect was evaluated.

  In the evaluation test apparatus of FIG. 1, test water is supplied from the test water tank 1 to the evaluation unit 5 by the pump 2 and returns to the test water tank 1 again. The flow rate of the test water is adjusted by the valve 3. Test water is supplied to the test water tank 1 by a pump 8 from a test water supply tank 7. The supply amount of the test water is adjusted to have a predetermined residence time. The temperature of the test water is adjusted to a predetermined temperature by the temperature controller 6. 4 is a flow meter.

  As shown in FIG. 1B, the evaluation unit 5 includes a column 9, an evaluation tube 10, a heater 11, and a thermocouple 12. The test water flows inside the column 9 outside the evaluation tube. A heater 11 is inserted inside the evaluation tube 10, and heating by the heater 11 simulates a heat transfer surface such as a heat exchanger on the outer surface of the evaluation tube 10. The metal portion of the evaluation tube 10 has pores into which the thermocouple 12 can be inserted, and the output of the heater 11 is controlled so that the temperature inside the metal (tube temperature) is kept constant.

[Test water]
The water quality of the test water (simulated cooling water) is as shown in Table 2 below. Suspended matter collected from industrial water was added to the test water in an amount once every day in the test water tank 7 so that the turbidity of the test water was 10.

[Operating conditions]
The operating conditions are as follows.
<Operating conditions>
Retained water volume: 100L
Test water flow rate in the evaluation section: 0.3 m / s
Residence time: 24 hours
Test water temperature: 30 ° C
Tube temperature: 90 ° C
Evaluation time: 2 days

[Evaluation results]
The evaluation tube 10 after completion of the test was dried, the adhered scale was removed, the weight was measured, and the adhesion rate was calculated from the amount of deposit, the tube area, and the evaluation time.

  The results are shown in FIG.

  As is clear from FIG. 2, when only polymer A or polymer B was added, a large amount of scales due to suspended substances adhered, whereas polymer A and polymer B were used in combination. In particular, it can be seen that when the polymer A: polymer B = 1: 4 to 9: 1 is used in combination, the scale deposition rate is low and scale deposition is effectively suppressed.

It is a figure which shows the evaluation test apparatus used in Examples 1-4 and Comparative Examples 1 and 2, (a) A figure is a systematic diagram which shows the whole structure, (b) A figure is sectional drawing which shows the detail of an evaluation part. . It is a graph which shows the result of Examples 1-4 and Comparative Examples 1 and 2. FIG.

Explanation of symbols

1 Test Water Tank 5 Evaluation Unit 6 Temperature Controller 9 Column 10 Evaluation Tube 11 Heater 12 Thermocouple

Claims (8)

A polymer of maleic acid and / or a water-soluble salt of maleic acid (hereinafter referred to as “polymer A”);
One or more monomer components (hereinafter referred to as “monomer component b1”) selected from the group consisting of (meth) acrylic acid and water-soluble salts thereof, and monoethylenically unsaturated sulfonic acid A monomer selected from the group consisting of one or more monomer components selected from monomers (hereinafter referred to as “monomer component b2”), and (meth) acrylamide and substituted (meth) acrylamide And a copolymer (hereinafter referred to as “polymer B”) with one or more of the body components (hereinafter referred to as “monomer component b3”). .   2. The scale adhesion preventing agent according to claim 1, wherein the polymer A and the polymer B are contained at a solid content concentration ratio of polymer A: polymer B = 1: 4 to 9: 1.   The scale adhesion preventing agent according to claim 1 or 2, wherein the monomer component b2 is 2-acrylamido-2-methylpropanesulfonic acid.   The scale adhesion preventing agent according to any one of claims 1 to 3, wherein the monomer component b3 is N-tert-butylacrylamide. In the cooling water system treatment method for suppressing adhesion of scale in a cooling water system in which suspended substances exist in water, the cooling water system includes:
A polymer of maleic acid and / or a water-soluble salt of maleic acid (hereinafter referred to as “polymer A”);
One or more monomer components (hereinafter referred to as “monomer component b1”) selected from the group consisting of (meth) acrylic acid and water-soluble salts thereof, and monoethylenically unsaturated sulfonic acid A monomer selected from the group consisting of one or more monomer components selected from monomers (hereinafter referred to as “monomer component b2”), and (meth) acrylamide and substituted (meth) acrylamide A cooling water system characterized by adding a copolymer (hereinafter referred to as “polymer B”) with one or more of the body components (hereinafter referred to as “monomer component b3”). Processing method.   6. The cooling water system according to claim 5, wherein the polymer A and the polymer B are added to the cooling water system in a ratio of polymer A: polymer B = 1: 4 to 9: 1 in a solid content concentration ratio. Processing method.   7. The cooling water treatment method according to claim 5, wherein the monomer component b2 is 2-acrylamido-2-methylpropanesulfonic acid.   8. A cooling water treatment method according to claim 5, wherein the monomer component b3 is N-tert-butylacrylamide.

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