JP4244983B2 - Metal corrosion control method - Google Patents
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- JP4244983B2 JP4244983B2 JP2005312980A JP2005312980A JP4244983B2 JP 4244983 B2 JP4244983 B2 JP 4244983B2 JP 2005312980 A JP2005312980 A JP 2005312980A JP 2005312980 A JP2005312980 A JP 2005312980A JP 4244983 B2 JP4244983 B2 JP 4244983B2
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
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Description
本発明は、金属の腐食抑制方法に係り、特に毒性や閉鎖性水域における富栄養化等の環境汚染問題を発生させることなく、水と接触する金属、特に鋼材の腐食を効果的に抑制する方法に関するものである。 The present invention relates to a method for inhibiting corrosion of metal, and in particular, a method for effectively inhibiting corrosion of a metal in contact with water, particularly a steel material, without causing environmental pollution problems such as toxicity and eutrophication in closed water areas. It is about.
冷却水系に設けられた金属部材、例えば、炭素鋼、銅、又は銅合金製の熱交換器や反応釜、配管は、冷却水と接触することにより腐食を受けることから、一般に、薬剤添加による防食処理が施されている。 Metal members provided in the cooling water system, such as heat exchangers, reaction kettles and piping made of carbon steel, copper, or copper alloys, are generally corroded by contact with cooling water. Processing has been applied.
例えば、炭素鋼製の熱交換器、反応釜や配管の腐食を抑制するために、従来、オルトリン酸塩、ヘキサメタリン酸塩、ヒドロキシエチリデンジホスホン酸塩、ホスホノブタントリカルボン酸塩などのリン化合物が冷却水に添加されている。また、亜鉛塩や重クロム酸塩のような重金属塩を単独で或いは併用して添加する場合もある。しかし、これらのリン化合物や重金属塩の大量使用、特に重金属塩の大量使用は、水質を汚染し環境に重篤な影響を招く恐れがあるため、その取り扱いや排水処理に多大な注意と費用が必要になる。 For example, phosphorus compounds such as orthophosphate, hexametaphosphate, hydroxyethylidene diphosphonate, and phosphonobutanetricarboxylate have been conventionally used to suppress corrosion of carbon steel heat exchangers, reaction kettles and piping. It is added to the cooling water. Further, a heavy metal salt such as zinc salt or dichromate may be added alone or in combination. However, large amounts of these phosphorus compounds and heavy metal salts, especially heavy metal salts, can contaminate the water quality and have a serious impact on the environment. I need it.
このような環境問題を引き起こすことなく金属の腐食を効果的に抑制する方法として、マレイン酸とイソブチレンの共重合体を添加し、ランジェリア指数を１．５以上かつシリカ濃度とカルシウム硬度の積を２０００以上として管理する腐食抑制方法（特許１８０６２９５号）が開示されている。 As a method for effectively suppressing the corrosion of metals without causing such environmental problems, a copolymer of maleic acid and isobutylene is added, the Langerian index is 1.5 or more, and the product of silica concentration and calcium hardness is increased. A corrosion suppression method (Japanese Patent No. 1806295) that is managed as 2000 or more is disclosed.
また、補正リツナー指数が３．０〜６．０になるように調整した循環水中に１９０ｎｍにおける吸光係数が０．０９〜０．２ｍｇ−１・ｄｍ３・ｃｍ−１である水溶性マレイン酸重合体を添加する金属の腐食抑制方法（特開２００４−９１８３５）が開示されている。 In addition, water-soluble maleic acid heavy acid having an extinction coefficient at 190 nm of 0.09 to 0.2 mg −1 · dm 3 · cm −1 in circulating water adjusted so that the corrected Ritzner index is 3.0 to 6.0. A method for inhibiting corrosion of a metal to which a coalescence is added (Japanese Patent Application Laid-Open No. 2004-91835) is disclosed.
これらの技術を用い、適正な管理を行うことにより、冷却水系の腐食を抑制することができるが、より一層効果的な腐食抑制技術の開発が望まれている。
本発明は、環境汚染問題を惹き起こすことなく、かつ公知の腐食抑制方法よりも優れた効果を発揮する金属の腐食抑制方法を提供することを目的とする。 An object of the present invention is to provide a method for inhibiting corrosion of a metal that does not cause environmental pollution problems and exhibits an effect superior to that of known corrosion inhibition methods.
本発明者らは、上記課題を解決すべく、水中に存在するカルシウム、シリカ、Ｍアルカリ度等の防食成分を有効に利用できる方法の検討を行った結果、特定のランジェリア指数、特定の［ＳｉＯ２］×［ＣａＨ］値となるように水質を調整した水系に、特定の２種類のポリマーを添加することにより、公知技術よりも優れた防食効果が得られることを見出し、本発明を完成させた。
即ち、本発明は以下を要旨とする。
［１］ 水系の金属の腐食を抑制する方法において、ランジェリア指数が１．５以上で、かつ［ＳｉＯ２］×［ＣａＨ］≧２０００（ただし、［ＳｉＯ２］は水中のＳｉＯ２濃度（ｍｇ／Ｌ）、［ＣａＨ］は水中のＣａＣＯ３としてのカルシウム硬度（ｍｇ／Ｌ））となるように調整された該水系の水に、マレイン酸及び／又はその水溶性塩から選ばれる１種以上の重合体（以下、「重合体Ａ」と称す。）と、マレイン酸、無水マレイン酸及びこれらの水溶性塩から選ばれる１種以上と非イオン性モノエチレン系不飽和単量体の１種以上との共重合体（以下、「重合体Ｂ」と称す。）とを添加する金属の腐食抑制方法であって、重合体Ａと重合体Ｂとを固形分濃度比で重合体Ａ：重合体Ｂ＝１：４〜４：１の範囲となるように該水系に添加することを特徴とする金属の腐食抑制方法。
［２］ ［１］において、重合体Ｂの非イオン性モノエチレン系不飽和単量体がイソブチレンであることを特徴とする金属の腐食抑制方法。
［３］ ［１］又は［２］において、重合体Ａと重合体Ｂとを固形分濃度比で重合体Ａ：重合体Ｂ＝１：２〜２：１の範囲となるように該水系に添加することを特徴とする金属の腐食抑制方法。
［４］ ［１］ないし［３］のいずれかにおいて、重合体Ａの分子量が８００〜１５００であることを特徴とする金属の腐食抑制方法。
［５］ ［１］ないし［４］のいずれかにおいて、重合体Ｂを構成するマレイン酸成分と非イオン性エチレン成分との合計１００モル％に対してマレイン酸成分が２５〜７５モル％の重合体Ｂを用いることを特徴とする金属の腐食抑制方法。
In order to solve the above problems, the present inventors have studied a method that can effectively use anticorrosive ingredients such as calcium, silica, and M alkalinity existing in water, and as a result, a specific Langerian index, a specific [ It was found that the anticorrosion effect superior to the known technique can be obtained by adding two specific types of polymers to an aqueous system whose water quality is adjusted so as to have a SiO 2 ] × [CaH] value, and the present invention is completed. I let you.
That is, the gist of the present invention is as follows.
[1] In the method for suppressing corrosion of an aqueous metal, the Langeria index is 1.5 or more, and [SiO 2 ] × [CaH] ≧ 2000 (where [SiO 2 ] is the concentration of SiO 2 in water (mg / L), [CaH] is one or more selected from maleic acid and / or water-soluble salts thereof in the aqueous water adjusted to have calcium hardness (mg / L) as CaCO 3 in water A polymer (hereinafter referred to as “polymer A”), one or more selected from maleic acid, maleic anhydride, and water-soluble salts thereof, and one nonionic monoethylenically unsaturated monomer A method for inhibiting corrosion of a metal by adding a copolymer (hereinafter referred to as “polymer B”) to the polymer A and the polymer B in a solid content concentration ratio. Addition to the aqueous system so that coalescence B = 1: 4-4: 1 Metal method corrosion inhibition, characterized in that that.
[2] Oite to [1], metal method corrosion inhibition, wherein the non-ionic monoethylenically unsaturated monomer is isobutylene polymer B.
[3] In [1] or [2], the polymer A and the polymer B are mixed in the aqueous system so that the solid content concentration ratio is in the range of polymer A: polymer B = 1: 2 to 2: 1. A method for inhibiting corrosion of a metal, comprising adding the metal.
[4] The method for inhibiting corrosion of a metal according to any one of [ 1] to [3], wherein the molecular weight of the polymer A is 800 to 1500.
[5] In any one of [ 1] to [4], the weight of maleic acid component is 25 to 75 mol% with respect to 100 mol% of the total of maleic acid component and nonionic ethylene component constituting polymer B. A method for inhibiting corrosion of a metal, characterized by using coalescence B.
本発明の金属の腐食抑制方法によれば、リン系化合物や重金属塩を使用することなく、従って、環境汚染問題を惹き起こすことなく、水系の金属の腐食を効果的に防止あるいは抑制することが可能となり、冷却水系等の安定運転に寄与することができる。 According to the method for inhibiting corrosion of a metal of the present invention, it is possible to effectively prevent or inhibit corrosion of an aqueous metal without using a phosphorus compound or a heavy metal salt, and without causing environmental pollution problems. It becomes possible and can contribute to stable operation of a cooling water system or the like.
なお、本発明において、
(1) ランジェリア指数≧１．５
(2) ［ＳｉＯ２］×［ＣａＨ］≧２０００の水系に
(3) 重合体Ａと重合体Ｂとを添加する
という、(1)〜(3)の要件は極めて重要であり、本発明においては、これらのうちの１条件でも欠けると良好な効果は得られない。
In the present invention,
(1) Langeria index ≧ 1.5
(2) To an aqueous system of [SiO 2 ] × [CaH] ≧ 2000
(3) The requirement of (1) to (3) that the polymer A and the polymer B are added is very important. In the present invention, if one of these conditions is missing, a good effect can be obtained. I can't.
例えばランジェリア指数が１．５以上で［ＳｉＯ２］×［ＣａＨ］≧２０００の水系であっても、重合体Ａと重合体Ｂの一方のみの添加では、十分な防食効果は得られない。また、重合体Ａと重合体Ｂとを添加しても、水系の水質が(1)及び／又は(2)を満たさない場合には、良好な防食効果は得られない。 For example, even in the case of an aqueous system having a Langeria index of 1.5 or more and [SiO 2 ] × [CaH] ≧ 2000, the addition of only one of the polymer A and the polymer B cannot provide a sufficient anticorrosive effect. Further, even when the polymer A and the polymer B are added, if the water quality of the aqueous system does not satisfy (1) and / or (2), a good anticorrosive effect cannot be obtained.
一般に、開放循環冷却水等の水系において、水の濃縮度を上げると、水中に含まれるカルシウムイオンや重炭酸イオンの濃度及びｐＨは増加し、ＣａＣＯ３皮膜の生成により腐食が抑制されることはよく知られている。この水系のＣａＣＯ３析出傾向を示す尺度として、ランジェリアの飽和指数が提案されている。これは、カルシウム濃度、Ｍアルカリ度、全溶解固形物及び水温、ｐＨから、その水のＣａＣＯ３析出傾向を一つの目安として示すものである。しかして、このランジェリア指数が１．５以上であると、ＣａＣＯ３のスケールが付着する傾向が大きくなるため、水の防食性も大きくなる。 Generally, in an aqueous system such as open circulation cooling water, when the concentration of water is increased, the concentration and pH of calcium ions and bicarbonate ions contained in the water are increased, and corrosion is suppressed by the formation of a CaCO 3 film. well known. As a scale indicating the water-based CaCO 3 precipitation tendency, the Langerian saturation index has been proposed. This shows the CaCO 3 precipitation tendency of the water as one standard from the calcium concentration, M alkalinity, total dissolved solid, water temperature, and pH. Accordingly, when the Langeria index is 1.5 or more, the CaCO 3 scale tends to adhere, and the corrosion resistance of water also increases.
また、水系に含有されるシリカも防食上極めて重要な役割を果す。しかるに、ランジェリア指数には、水系のシリカ含有量は全溶解固形物の１種として扱われており、ランジェリア指数にはシリカ濃度が直接的に表示されていない。 Silica contained in the water system also plays an extremely important role in preventing corrosion. However, the silica content of the aqueous system is treated as one of the total dissolved solids in the Langeria index, and the silica concentration is not directly displayed in the Langeria index.
そこで、良好な防食効果が得られる水系のシリカ濃度について検討した結果、ランジェリア指数が１．５以上のもののうち、特に［ＳｉＯ２］×［ＣａＨ］≧２０００のもののみが、本発明に係る重合体Ａと重合体Ｂとの併用による相乗効果において共奏効果を発揮することが解明された。 Therefore, as a result of examining the silica concentration in water based on which a good anticorrosive effect can be obtained, only those having [SiO 2 ] × [CaH] ≧ 2000 in particular according to the present invention out of those having a Langeria index of 1.5 or more. It has been elucidated that the synergistic effect of the combined use of the polymer A and the polymer B exhibits a concerto effect.
本発明において、重合体Ａと重合体Ｂとは、固形分濃度比で重合体Ａ：重合体Ｂ＝１：４〜４：１の範囲となるように添加することが好ましい（請求項２）。また、重合体Ｂの非イオン性モノエチレン系不飽和単量体としては、イソブチレンが好ましい（請求項３）。 In the present invention, the polymer A and the polymer B are preferably added so that the solid content concentration ratio is in the range of polymer A: polymer B = 1: 4 to 4: 1 (Claim 2). . Further, as the nonionic monoethylenically unsaturated monomer of the polymer B, isobutylene is preferable (Claim 3).
以下に本発明の金属の腐食抑制方法の実施の形態を詳細に説明する。
なお、本発明において、「分子量」とは「重量平均分子量」を指す。
Embodiments of the metal corrosion inhibiting method of the present invention will be described in detail below.
In the present invention, “molecular weight” refers to “weight average molecular weight”.
［重合体Ａ］
重合体Ａは、マレイン酸及び／又はマレイン酸の水溶性塩の重合体である。
ここで、マレイン酸の水溶性塩としては、マレイン酸ナトリウム、マレイン酸カリウム、マレイン酸アンモニウム等が挙げられる。
重合体Ａの分子量としては、５００〜５０００程度、特に８００〜１５００程度であることが好ましい。
[Polymer A]
The polymer A is 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 about 500 to 5000, particularly about 800 to 1500.
［重合体Ｂ］
重合体Ｂは、マレイン酸、無水マレイン酸及びこれらの水溶性塩から選ばれる１種以上（以下、「マレイン酸成分」と称す。）と非イオン性モノエチレン系不飽和単量体１種以上（以下「非イオン性エチレン成分」と称す。）との共重合体である。
マレイン酸成分の水溶性塩としては、ナトリウム塩、カリウム塩、アンモニウム塩等が挙げられる。
[Polymer B]
Polymer B is at least one selected from maleic acid, maleic anhydride and water-soluble salts thereof (hereinafter referred to as “maleic acid component”) and at least one nonionic monoethylenically unsaturated monomer. (Hereinafter referred to as “nonionic ethylene component”).
Examples of the water-soluble salt of the maleic acid component include sodium salt, potassium salt, ammonium salt and the like.
非イオン性エチレン成分としては、炭素数２〜８のオレフィン炭化水素が挙げられ、例えばイソブチレン、エチレン、プロピレン、ブチレン、１−ペンテン、１−ヘキセン、１−オクテン等が好ましく、特にイソブチレンが好ましい。 Examples of the nonionic ethylene component include olefin hydrocarbons having 2 to 8 carbon atoms. For example, isobutylene, ethylene, propylene, butylene, 1-pentene, 1-hexene, 1-octene and the like are preferable, and isobutylene is particularly preferable.
重合体Ｂを構成するマレイン酸成分と非イオン性エチレン成分との合計１００モル％に対してマレイン酸成分が１０モル％以上、好ましくは２５〜７５モル％の重合体Ｂを用いることが好ましい。 It is preferable to use the polymer B in which the maleic acid component is 10 mol% or more, preferably 25 to 75 mol%, based on the total 100 mol% of the maleic acid component and the nonionic ethylene component constituting the polymer B.
また、重合体Ｂの分子量は５０００〜５００００程度、特に１００００〜３００００程度であることが好ましい。 Moreover, it is preferable that the molecular weight of the polymer B is about 5000-50000, especially about 10,000-30000.
［水質調整］
本発明においては、処理対象水系の水を、ランジェリア指数が１．５以上で、かつ［ＳｉＯ２］×［ＣａＨ］≧２０００（ただし、［ＳｉＯ２］は水中のＳｉＯ２濃度（ｍｇ／Ｌ）、［ＣａＨ］は水中のＣａＣＯ３としてのカルシウム硬度（ｍｇ／Ｌ））となるように調整する。
[Water quality adjustment]
In the present invention, water in the water system to be treated has a Langeria index of 1.5 or more and [SiO 2 ] × [CaH] ≧ 2000 (where [SiO 2 ] is the concentration of SiO 2 in water (mg / L ) And [CaH] are adjusted so as to have a calcium hardness (mg / L) as CaCO 3 in water.
処理対象水のランジェリア指数と［ＳｉＯ２］×［ＣａＨ］がこのような特定値以上となるように、水中にＣａＣＯ３及びシリカが含有されていると、この水に添加された重合体Ａと重合体Ｂとが確実にＣａＣＯ３等をまき込んで、金属表面に良好な防食皮膜を形成し、優れた防食抑制効果が得られる。ランジェリア指数が１．５未満でも、［ＳｉＯ２］×［ＣａＯ］＜２０００でも、良好な腐食抑制効果が得られない。従って、処理対象水系がこの規定値をはずれるような水質であった場合には、重合体Ａと重合体Ｂとの添加に先立って、処理対象水の水質を調整する。 If CaCO 3 and silica are contained in the water so that the Langerian index and [SiO 2 ] × [CaH] of the water to be treated are not less than the specific value, the polymer A added to the water And polymer B surely entrap CaCO 3 or the like to form a good anticorrosive film on the metal surface, and an excellent anticorrosive effect can be obtained. Even if the Langeria index is less than 1.5, even if [SiO 2 ] × [CaO] <2000, a good corrosion inhibiting effect cannot be obtained. Therefore, when the water quality of the water to be treated is such that it does not exceed this specified value, the water quality of the water to be treated is adjusted prior to the addition of the polymer A and the polymer B.
この水質の調整方法としては特に制限はないが、例えば、開放循環冷却水系等であれば、水の濃縮度を上げる方法が挙げられる。その他、水質の調整は必要な成分を水系へ添加することによっても行うことができる。 Although there is no restriction | limiting in particular as this water quality adjustment method, For example, if it is an open circulation cooling water system etc., the method of raising the concentration of water will be mentioned. In addition, the water quality can be adjusted by adding necessary components to the aqueous system.
［固形分濃度比及び添加濃度］
重合体Ａと重合体Ｂとは、固形分濃度比が重合体Ａ：重合体Ｂ＝１：４〜４：１、好ましくは１：２〜２：１となるように処理対象水系に添加する。この使用割合が上記範囲をはずれると良好な腐食抑制効果が得られない。
[Solid content concentration ratio and additive concentration]
Polymer A and 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 4: 1, preferably 1: 2 to 2: 1. The When this use ratio is out of the above range, a good corrosion inhibiting effect cannot be obtained.
また、重合体Ａ及び重合体Ｂの添加濃度は、処理対象水系の水質や運転状況などを考慮して、十分なスケール抑制効果が得られるような濃度に設定されるが、通常、処理対象水系中の保持濃度（固形分換算濃度）で、重合体Ａと重合体Ｂの合計濃度として１〜５００ｍｇ／Ｌ、特に５〜１００ｍｇ／Ｌとなるように連続的に又は間欠的に添加するのが望ましい。 In addition, 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 added continuously or intermittently so that the total concentration of the polymer A and the polymer B is 1 to 500 mg / L, particularly 5 to 100 mg / L, with the retained concentration (concentration in terms of solid content). desirable.
重合体Ａと重合体Ｂとは、その固形分濃度比及び添加濃度が上記好適範囲内となるように個別に添加しても良く、予め重合体Ａと重合体Ｂとを所定の比率で混合したものを添加しても良い。重合体Ａと重合体Ｂとを個別に添加する場合、これらを同一箇所で添加しても異なる箇所で添加しても良い。 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.
なお、本発明においては、重合体Ａと重合体Ｂとを処理対象水系に添加した際に得られる各処理効率を妨げない範囲において、他の腐食抑制剤、スケール抑制剤、分散剤、スライムコントロール剤、剥離剤、消泡剤などを併用しても良く、濾過器などの各種水処理機器との併用も可能である。例えば、水系内に銅材質を含む場合には、ベンゾトリアゾールやトリルトリアゾールなどのアゾール類誘導体を併用すれば、銅材質に対する防食性能を向上させることができる。 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.
［処理対象水系］
本発明の処理対象水系としては、冷却水系が挙げられ、例えば、開放循環式冷却水系等が挙げられる。
[Treatment target water system]
Examples of the water system to be treated of the present invention include a cooling water system such as an open circulation cooling water system.
このような冷却水系では、冷却塔のピットに重合体Ａと重合体Ｂとを添加すれば良い。 In such a cooling water system, the polymer A and the polymer B may be added to the pits of the cooling tower.
以下に実施例及び比較例を挙げて本発明を更に具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例に限定されるものではない。 EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to the following examples unless it exceeds the gist.
実施例１〜５、比較例１〜４
図１に概要を示すベンチスケール冷却水系評価試験装置を用いて、実施例及び比較例の腐食抑制効果を調べる実験を行った。
Examples 1-5, Comparative Examples 1-4
Using the bench scale cooling water system evaluation test apparatus outlined in FIG. 1, an experiment was conducted to investigate the corrosion inhibition effects of the examples and comparative examples.
図１の評価試験装置において、冷却塔１から、ポンプＰ１を有する循環配管２により循環冷却水が熱交換器３に送給され、戻り水が配管４より冷却塔１に戻される。５は補給水の導入配管、６は次亜塩素酸ナトリウム水溶液の導入配管、７は表３に示す評価薬剤の導入配管、８はブロー配管であり、各々ポンプＰ２，Ｐ３，Ｐ４，Ｐ５を備える。熱交換器３は、外径１９ｍｍ、長さ１３００ｍｍ、厚さ２．３ｍｍの炭素鋼製チューブ２本が設けられた蒸気加熱シェル側通水熱交換器である。
In the evaluation test apparatus of FIG. 1, the circulating cooling water is supplied from the cooling tower 1 to the heat exchanger 3 through the
この評価試験装置の運転条件は次の通りである。
［運転条件］
保有水量：３５０Ｌ
流速：０．１ｍ／秒
熱交換器入口水温：３０℃
熱交換器出口水温：３５℃（蒸気加熱）
次亜塩素酸ナトリウム添加方法：冷却水の残留塩素濃度が０．３〜０．５ｍｇ／Ｌと
なるように連続注入
評価薬剤添加方法：表２に示す評価薬剤を用い、表３に示す通り、冷却水中の保持濃
度（固形分換算濃度）が２０ｍｇ／Ｌとなるように連続注入
The operation conditions of this evaluation test apparatus are as follows.
[Operating conditions]
Retained water volume: 350L
Flow rate: 0.1 m / sec Heat exchanger inlet water temperature: 30 ° C
Heat exchanger outlet water temperature: 35 ° C (steam heating)
Sodium hypochlorite addition method: residual chlorine concentration of cooling water is 0.3 to 0.5 mg / L
As shown in Table 3, the concentration of retention in cooling water is as follows.
Continuous injection so that the concentration (concentration in terms of solid content) is 20 mg / L
市販の初期処理薬剤により初期防食皮膜を形成した炭素鋼製テストチューブを用い、上記の運転を２０日間行い、熱交換器チューブに生じた局部腐食の最大深さで腐食抑制効果の評価を行った。２０日間の運転後に、熱交換器よりテストチューブを取り出し、チューブの腐食状況（外観）を観察した。インヒビター入り塩酸でテストチューブを酸洗し、腐食生成物を取り除いた。テストチューブ表面に生じた局部腐食深さをデプスゲージで測定し、その最大値を求めた。 Using a carbon steel test tube on which an initial anticorrosion film was formed with a commercially available initial treatment chemical, the above operation was performed for 20 days, and the corrosion inhibition effect was evaluated at the maximum depth of local corrosion that occurred in the heat exchanger tube. . After the operation for 20 days, the test tube was taken out from the heat exchanger, and the corrosion state (appearance) of the tube was observed. The test tube was pickled with hydrochloric acid containing inhibitor to remove corrosion products. The depth of local corrosion occurring on the test tube surface was measured with a depth gauge, and the maximum value was obtained.
試験中の冷却水の平均的水質を表１に、評価薬剤を表２に、試験結果を表３にそれぞれ示す。 Table 1 shows the average water quality of the cooling water during the test, Table 2 shows the evaluation drugs, and Table 3 shows the test results.
表３より明らかなように、本発明の実施例では、比較例に比べ良好な金属の腐食抑制効果を示した。 As is apparent from Table 3, the examples of the present invention showed a better metal corrosion inhibition effect than the comparative examples.
１ 冷却塔
２ 熱交換器
1
Claims (5)
ランジェリア指数が１．５以上で、かつ［ＳｉＯ２］×［ＣａＨ］≧２０００（ただし、［ＳｉＯ２］は水中のＳｉＯ２濃度（ｍｇ／Ｌ）、［ＣａＨ］は水中のＣａＣＯ３としてのカルシウム硬度（ｍｇ／Ｌ））となるように調整された該水系の水に、
マレイン酸及び／又はその水溶性塩から選ばれる１種以上の重合体（以下、「重合体Ａ」と称す。）と、
マレイン酸、無水マレイン酸及びこれらの水溶性塩から選ばれる１種以上と、非イオン性モノエチレン系不飽和単量体の１種以上との共重合体（以下、「重合体Ｂ」と称す。）とを添加する金属の腐食抑制方法であって、
重合体Ａと重合体Ｂとを固形分濃度比で重合体Ａ：重合体Ｂ＝１：４〜４：１の範囲となるように該水系に添加することを特徴とする金属の腐食抑制方法。 In a method for suppressing corrosion of water-based metals,
Langerian index is 1.5 or more, and [SiO 2 ] × [CaH] ≧ 2000 (where [SiO 2 ] is SiO 2 concentration in water (mg / L), [CaH] is CaCO 3 in water The aqueous water adjusted to have a calcium hardness (mg / L))
One or more polymers selected from maleic acid and / or water-soluble salts thereof (hereinafter referred to as “polymer A”);
A copolymer (hereinafter referred to as “polymer B”) of at least one selected from maleic acid, maleic anhydride and water-soluble salts thereof and at least one nonionic monoethylenically unsaturated monomer. )) Is a method for inhibiting corrosion of a metal,
A method for inhibiting corrosion of metal , comprising adding polymer A and polymer B to the aqueous system so that the solid content concentration ratio of polymer A: polymer B = 1: 4 to 4: 1 .
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