WO2010016435A1 - Boiler water treatment agent and method for the treatment of water - Google Patents

Boiler water treatment agent and method for the treatment of water Download PDF

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Publication number
WO2010016435A1
WO2010016435A1 PCT/JP2009/063649 JP2009063649W WO2010016435A1 WO 2010016435 A1 WO2010016435 A1 WO 2010016435A1 JP 2009063649 W JP2009063649 W JP 2009063649W WO 2010016435 A1 WO2010016435 A1 WO 2010016435A1
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WO
WIPO (PCT)
Prior art keywords
boiler
water treatment
boiler water
tannin
treatment agent
Prior art date
Application number
PCT/JP2009/063649
Other languages
French (fr)
Japanese (ja)
Inventor
幸祐 志村
Original Assignee
栗田工業株式会社
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Filing date
Publication date
Application filed by 栗田工業株式会社 filed Critical 栗田工業株式会社
Priority to JP2010523841A priority Critical patent/JP6120475B2/en
Priority to CN2009801260215A priority patent/CN102084033A/en
Publication of WO2010016435A1 publication Critical patent/WO2010016435A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
    • C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
    • C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
    • C—CHEMISTRY; METALLURGY
    • 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
    • C23F11/12—Oxygen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • 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
    • C23F14/00—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes
    • C23F14/02—Inhibiting incrustation in apparatus for heating liquids for physical or chemical purposes by chemical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/56—Boiler cleaning control devices, e.g. for ascertaining proper duration of boiler blow-down
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D11/00—Feed-water supply not provided for in other main groups
    • F22D11/006—Arrangements of feedwater cleaning with a boiler
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
    • C02F2103/023—Water in cooling circuits
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/06—Controlling or monitoring parameters in water treatment pH

Definitions

  • the present invention relates to boiler water system water treatment technology.
  • a water treatment agent containing an oxygen scavenger having an action of removing dissolved oxygen is added to the water supplied to the water supply system and the steam generation facility.
  • hydrazine As such an oxygen scavenger, hydrazine has been frequently used in the past, but from the viewpoint of improving safety to the human body, use of a natural material in place of hydrazine has been studied.
  • tannin which has a capability of forming a corrosion-inhibiting film on a metal surface in addition to an oxygen removing action and can be produced from a natural material, has attracted attention as a component of an oxygen scavenger.
  • Patent Document 1 states that tannic acid is used in combination with a saccharide and aldonic acid
  • Patent Document 2 indicates that tannic acid is used in combination with a reducing phenol
  • Patent Document 3 discloses that tannic acid is used as aldonic acid. And that it is used in combination with an alkali compound.
  • the corrosion inhibitor shown in Patent Document 4 contains both condensed tannin and hydrolyzable tannin
  • the corrosion inhibitor shown in Patent Document 5 contains hydrolyzable tannin together with potassium hydroxide.
  • the above-described conventional corrosion inhibitor has an excellent ability to suppress corrosion in a boiler can, but has a problem that the ability to inhibit corrosion in a water supply system or a steam condensate system is not sufficient.
  • the main object of the present invention is to provide a boiler water treatment agent and a water treatment method capable of obtaining excellent corrosion inhibiting ability in a wider area of the boiler water system.
  • the present inventor has found that corrosion in almost the entire area of the boiler water system can be sufficiently suppressed by using condensed tannin and caustic alkali in a predetermined range ratio, and has completed the present invention.
  • the boiler water treatment agent according to the present invention is a boiler water treatment agent containing condensed tannin and / or a derivative thereof and caustic alkali, and the content (A) of the condensed tannin and / or the derivative thereof.
  • the mass ratio (B / A) of the content (B) of the caustic alkali relative to is 0.4 or more.
  • the water treatment agent can further contain a scale dispersant.
  • substantially not containing includes not only containing it at all, but also containing a small amount inevitably mixed in, or containing an amount within an allowable limit for detour purposes.
  • the boiler water treatment method according to the present invention is a water treatment method in a boiler water system, wherein condensed tannin and / or a derivative thereof and caustic alkali are added to the boiler water system, and the condensed tannin and / or a derivative thereof are added. It adds so that the mass ratio (B / A) of the addition amount (B) of the caustic alkali to the amount (A) may be 0.4 or more.
  • a scale dispersant can be further added to the boiler water system.
  • condensed tannin and caustic alkali are used in combination within a predetermined range, corrosion not only in the boiler can but also in other places can be sufficiently suppressed, and a wider range of boiler water systems can be obtained. In the region, the ability to suppress corrosion can be improved.
  • the boiler water treatment agent of this embodiment contains condensed tannin and / or a derivative thereof and caustic alkali in a predetermined amount ratio, and is added to the boiler water system to exert actions such as corrosion inhibition.
  • hydrolyzable tannin refers to a pyrogallol tannin group that is decomposed into an alcohol and an acid by an acid, an alkali, or an enzyme (tannase), and specifically includes a pentaploid tannin and a gallic tannin.
  • This hydrolyzed tannin has been conventionally used as a component of a water treatment agent, but is easily pyrolyzed in a boiler can to generate carbon dioxide. For this reason, if a hydrolyzable tannin in an amount suitable for the dissolved oxygen concentration in the feed water is used, a high concentration of carbon dioxide gas is generated, which shifts to a steam condensate system and lowers the condensate pH. This promotes corrosion in the steam condensate system and the water supply system.
  • the boiler water treatment agent of this embodiment does not contain hydrolyzable tannin and its derivative substantially.
  • substantially not containing includes not only containing at all, but also containing a small amount that is inevitably mixed in, or containing an amount within the allowable limit for detour purposes. To do.
  • condensed tannin is similar to hydrolyzed tannin in terms of its general properties, but is a heterogeneous group of compounds in terms of chemical structure.
  • Condensed tannin has excellent deoxygenation action, so it has excellent corrosion inhibition ability.
  • Condensed tannin is less likely to generate carbon dioxide than hydrolyzed tannin.
  • corrosion in the steam condensate system and water supply system is suppressed.
  • corrosion in a wider area for example, in a boiler can, a steam condensate system, a feed water system
  • condensed tannins especially keprachotannin and mimosa (wattle) tannin, are hardly hydrolyzed even when coexisting with an alkaline agent. For this reason, the inhibition of the corrosion suppression effect of the water supply system by the alkaline agent can be suppressed.
  • condensed tannin examples include catechol tannin condensed with flavanol (so-called catechin).
  • catechin catechol tannin condensed with flavanol
  • the condensed tannin blended in the boiler water treatment agent of the present embodiment is not particularly limited, for example, extracted from plants such as kepracho tannin, mimosa tannin, radiata pine tannin, gambian tannin, mangrove tannin And condensed tannins. Furthermore, these may be contained alone or in combination of two or more.
  • the condensed tannin blended in the boiler water treatment agent of the present embodiment may be a crude product extracted and concentrated from a plant or a purified product purified to a high purity.
  • the boiler water treatment agent of the present embodiment may contain a condensed tannin derivative instead of or together with the condensed tannin.
  • the condensed tannin derivative includes a salt, an oxidized form, a reduced form, a substituted form, and the like.
  • the salt of condensed tannin includes, but is not limited to, alkali metal (for example, sodium, potassium) salt and alkaline earth metal (for example, magnesium, calcium) salt of condensed tannin. .
  • alkali metal salt for example, sodium, potassium
  • alkaline earth metal for example, magnesium, calcium
  • blend an alkali metal salt with the boiler water treatment agent of this embodiment from the point of scale generation prevention.
  • Condensed tannin derivatives include those that have been bleached with sulfurous acid and those that have been modified so that insoluble components are water-soluble.
  • (Caustic) Caustic is added for the purpose of suppressing corrosion by increasing the pH of the water in the boiler water system to a desired range and increasing the pH of the water supply line after the injection point by adding it to the water supply.
  • alkali agents such as sodium carbonate and potassium carbonate have been used for the purpose of increasing pH, but sodium carbonate and potassium carbonate are also used for these purposes.
  • an alkali agent comprising these carbonates is used, a large amount of carbon dioxide gas is transferred to the steam condensate system and the pH of the condensate is lowered, so that corrosion in the steam condensate system and the water supply system is promoted.
  • caustic is a strong base, so it has a high effect of raising pH, has excellent corrosion inhibition ability, and does not generate carbon dioxide, so it does not promote corrosion in steam condensate systems or water supply systems.
  • the boiler water treatment agent of this embodiment using caustic can sufficiently suppress corrosion in a wider range (for example, in a boiler can, a steam condensate system, and a feed water system).
  • the caustic alkali to be blended in the boiler water treatment agent of the present embodiment is not particularly limited, and examples thereof include alkali metal or alkaline earth metal hydroxides. Therefore, it is preferable to use hydroxides of alkali metals such as sodium and potassium.
  • the mass ratio (B / A) of the content (B) of caustic alkali to the content (A) of condensed tannin and / or its derivative is 0.4 or more.
  • B / A is less than 0.4, the remaining amount of caustic alkali after being consumed in the boiler can is insufficient, so that the suppression of corrosion becomes insufficient.
  • B / A is preferably 0.8 or more, more preferably 1.0 or more.
  • the upper limit of B / A is not specifically limited, It is normally desirable to set it as 10 or less from a viewpoint of the cost-effectiveness and the influence on the concentration multiple of boiler water.
  • the boiler water treatment agent of this embodiment further contains a scale dispersant in addition to the components described above.
  • a scale dispersant for example, the corrosion of the accumulated sludge (for example, the oxygen in the outside air mixed in the boiler can be converted into water while the boiler pressure is low as when the boiler is stopped). It is possible to prevent the corrosion by the oxygen concentration cell due to the difference in oxygen concentration between the water and the sludge lower portion.
  • the scale dispersant is not particularly limited, and examples thereof include acrylic acid polymers and copolymers such as sodium polyacrylate, polyacrylic acid / acrylamidomethylpropane sulfonic acid or salts thereof, sodium polymaleate, polysodium methacrylate. Carboxymethylcellulose (sodium), polymerized phosphoric acid or a salt thereof, and the like can be used. Moreover, these dispersing agents may be mix
  • the boiler water treatment agent of this embodiment may further contain optional components such as anticorrosives.
  • Anticorrosives are those that prevent corrosion by forming an anticorrosion film in the boiler can, those that volatilize and move to the steam system to raise the pH of the steam condensate, and form a film on the surface of the steam condensate system
  • a boiler water treatment agent according to the present embodiment may be a well-known one.
  • the anticorrosive agent in the boiler can includes aldonic acid (salt) such as gluconic acid (salt) and ⁇ -glucoheptonic acid (salt), succinic acid (salt), citric acid (salt), malic acid ( Salt) and other amino acid (salt) such as glutamic acid (salt).
  • aldonic acid such as gluconic acid (salt) and ⁇ -glucoheptonic acid (salt)
  • succinic acid (salt) succinic acid
  • citric acid salt
  • malic acid Salt
  • other amino acid (salt) such as glutamic acid (salt).
  • the anticorrosive material for the steam condensate include neutral amines such as aminomethylpropanol, monoisopropanolamine, cyclohexylamine, diethylethanolamine and morpholine, and long-chain aliphatic amines such as octadecylamine.
  • the water treatment method of the present embodiment is a method for suppressing the occurrence of corrosion in the boiler water system using the water treatment agent of the first embodiment described above.
  • condensed tannin and / or its derivative and caustic alkali are added to the boiler water system, and caustic to the added amount (A) of condensed tannin and / or its derivative. It has the process of adding so that the mass ratio (B / A) of the addition amount (B) of alkali may be 0.4 or more.
  • substantially no hydrolyzable tannin and its derivatives are added to the boiler water system.
  • substantially no hydrolyzable tannin and its derivatives are added to the boiler water system.
  • substantially not add includes not only adding at all, but also unavoidably adding a very small amount, or adding an amount within an allowable limit for detour purposes. .
  • each component is not particularly limited, and an arbitrary location of the boiler water system can be appropriately selected. Usually, it is the location which should suppress a scale and corrosion, or its upstream, for example, a water supply system may be sufficient.
  • the addition of each component to the boiler water system may be performed after mixing part or all of them, or may be performed independently.
  • adding independently means adding to an independent timing and / or an independent location.
  • the composition shown in Table 1 below was carried out using quebracho tannin (type: A), wattle tannin (type: B), and pentaploid tannin (type: C).
  • quebracho tannin type: A
  • wattle tannin type: B
  • pentaploid tannin type: C
  • the boiler water treatment agents of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared.
  • NaOH type: a
  • KOH type: b
  • sodium polyacrylate type: ⁇
  • the corrosion rate was high in any of the water supply system, the boiler can, and the steam condensate system, and particularly the corrosion rate in the boiler can was extremely high.
  • the M alkalinity of the feed water is increased by setting the mass ratio (B / A) of the content (B) of the caustic alkali to the content (A) of the condensed tannin and / or derivative thereof to 0.4 or more. It was confirmed that even in a boiler with a relatively low value of 15 mg CaCO 3 / L, the ability to inhibit corrosion in a wider area, particularly in a boiler can, can be improved.
  • the boiler water treatment agent of Examples 1 to 3 has a lower corrosion rate in any of the water supply system, the boiler can, and the steam condensate system than the boiler water treatment agent of Example 4, and particularly in the boiler can.
  • the corrosion rate at was significantly lower. Thereby, it was confirmed that the corrosion in a wide area
  • the boiler water treatment agent having the composition shown in Table 3 below was used, except that the condensate recovery rate was 50% and the feed water temperature was 40 ° C.
  • the boiler operation was performed in the same procedure as in Example 1. The results are shown in Table 4 below.
  • Example 5 Moreover, about each boiler water treatment agent of this Example 5 and the comparative example 4, it measured the pH (25 degreeC) of steam condensate water, and was spent for adjusting pH to 7.0 or 8.5. The addition concentration of isopropanolamine (neutralizing amine) was determined. The results are shown in Table 5 below.

Abstract

A boiler water treatment agent which exerts excellent anticorrosive performance in a wider region of a boiler water system; and a method for the treatment of water. Use of a boiler water treatment agent which contains both a condensed tannin and/or a derivative thereof and a caustic alkali and in which the B/A mass ratio of the content (B) of the caustic alkali to the content (A) of the condensed tannin and/or derivative thereof is 0.4 or above; or addition of both a condensed tannin and/or a derivative thereof and a caustic alkali to a boiler water system in such amounts as to give a B/A mass ratio of 0.4 or above wherein (B) is the amount of the added caustic alkali and (A) is the amount of the added condensed tannin and/or derivative thereof.

Description

ボイラ水処理剤及び水処理方法Boiler water treatment agent and water treatment method
　本発明は、ボイラ水系の水処理技術に関する。 The present invention relates to boiler water system water treatment technology.
　ボイラ水系を流通する水に含まれる溶存酸素は、給水系の配管、ボイラ缶体、蒸気復水配管その他の水系プラント設備の腐食原因となる。このため、一般に、給水系や蒸気発生設備に供給される水には、溶存酸素の除去作用を有する脱酸素剤を含有する水処理剤が添加されている。 The dissolved oxygen contained in the water flowing through the boiler water system will cause corrosion of water supply system piping, boiler cans, steam condensate piping and other water plant equipment. For this reason, in general, a water treatment agent containing an oxygen scavenger having an action of removing dissolved oxygen is added to the water supplied to the water supply system and the steam generation facility.
　このような脱酸素剤としては、従来ヒドラジンが多用されていたが、人体への安全性を向上する観点から、ヒドラジンに代わる天然素材の使用が検討されている。そして、近年、酸素除去作用に加えて金属表面に対する腐食抑制皮膜形成能を有し、天然素材から生成できるタンニンが、脱酸素剤の成分として着目されている。 As such an oxygen scavenger, hydrazine has been frequently used in the past, but from the viewpoint of improving safety to the human body, use of a natural material in place of hydrazine has been studied. In recent years, tannin, which has a capability of forming a corrosion-inhibiting film on a metal surface in addition to an oxygen removing action and can be produced from a natural material, has attracted attention as a component of an oxygen scavenger.
　例えば、特許文献１には、タンニン酸を糖類及びアルドン酸と併用する旨が、特許文献２には、タンニン酸を還元性フェノールと併用する旨が、特許文献３には、タンニン酸をアルドン酸及びアルカリ化合物と併用する旨が示されている。また、特許文献４に示される腐食抑制剤は縮合型タンニン及び加水分解性タンニンの双方を含有し、特許文献５に示される腐食抑制剤は加水分解性タンニンを水酸化カリウムとともに含有している。 For example, Patent Document 1 states that tannic acid is used in combination with a saccharide and aldonic acid, Patent Document 2 indicates that tannic acid is used in combination with a reducing phenol, and Patent Document 3 discloses that tannic acid is used as aldonic acid. And that it is used in combination with an alkali compound. Moreover, the corrosion inhibitor shown in Patent Document 4 contains both condensed tannin and hydrolyzable tannin, and the corrosion inhibitor shown in Patent Document 5 contains hydrolyzable tannin together with potassium hydroxide.
特開平１－２１２７８１号公報Japanese Unexamined Patent Publication No. 1-212781 特開平４－２６７８３号公報JP-A-4-26783 特開２００５－２８１７６０号公報JP 2005-281760 A 特開平８－１６５５８７号公報Japanese Patent Laid-Open No. 8-165588 特開２００３－１４７５５４号公報JP 2003-147554 A
　しかし、前述した従来の腐食抑制剤には、ボイラ缶内における腐食の抑制能には優れるが、給水系や蒸気復水系における腐食の抑制能が充分でないという問題点がある。 However, the above-described conventional corrosion inhibitor has an excellent ability to suppress corrosion in a boiler can, but has a problem that the ability to inhibit corrosion in a water supply system or a steam condensate system is not sufficient.
　そこで、本発明は、ボイラ水系のより広範な領域において、優れた腐食抑制能が得られるボイラ水処理剤及び水処理方法を提供することを主目的とする。 Therefore, the main object of the present invention is to provide a boiler water treatment agent and a water treatment method capable of obtaining excellent corrosion inhibiting ability in a wider area of the boiler water system.
　本発明者は、縮合型タンニン及び苛性アルカリを所定範囲の比率で併用することにより、ボイラ水系のほぼ全域における腐食が充分に抑制されることを見出し、本発明を完成するに至った。 The present inventor has found that corrosion in almost the entire area of the boiler water system can be sufficiently suppressed by using condensed tannin and caustic alkali in a predetermined range ratio, and has completed the present invention.
　即ち、本発明に係るボイラ水処理剤は、縮合型タンニン及び／又はその誘導体と、苛性アルカリとを含有するボイラ水処理剤であって、縮合型タンニン及び／又はその誘導体の含有量（Ａ）に対する苛性アルカリの含有量（Ｂ）の質量比（Ｂ／Ａ）が、０．４以上となっている。
　この水処理剤は、更に、スケール分散剤を含有することができる。
　また、加水分解型タンニン及びその誘導体を実質的に含有しないことが好ましい。ここで「実質的に含有しない」とは、全く含有しないことのみならず、不可避的に混入する僅少量を含有すること、あるいは迂回目的で許容限度内の量を含有することも包含する。 That is, the boiler water treatment agent according to the present invention is a boiler water treatment agent containing condensed tannin and / or a derivative thereof and caustic alkali, and the content (A) of the condensed tannin and / or the derivative thereof. The mass ratio (B / A) of the content (B) of the caustic alkali relative to is 0.4 or more.
The water treatment agent can further contain a scale dispersant.
Moreover, it is preferable not to contain hydrolyzable tannin and its derivative substantially. Here, “substantially not containing” includes not only containing it at all, but also containing a small amount inevitably mixed in, or containing an amount within an allowable limit for detour purposes.
　本発明に係るボイラ水処理方法は、ボイラ水系における水処理方法であって、前記ボイラ水系に、縮合型タンニン及び／又はその誘導体と、苛性アルカリとを、縮合型タンニン及び／又はその誘導体の添加量（Ａ）に対する苛性アルカリの添加量（Ｂ）の質量比（Ｂ／Ａ）が０．４以上になるように添加する。
　この水処理方法では、ボイラ水系に、更に、スケール分散剤を添加することができる。
　また、ボイラ水系に、加水分解型タンニン及びその誘導体を実質的に添加しないことが好ましい。 The boiler water treatment method according to the present invention is a water treatment method in a boiler water system, wherein condensed tannin and / or a derivative thereof and caustic alkali are added to the boiler water system, and the condensed tannin and / or a derivative thereof are added. It adds so that the mass ratio (B / A) of the addition amount (B) of the caustic alkali to the amount (A) may be 0.4 or more.
In this water treatment method, a scale dispersant can be further added to the boiler water system.
Moreover, it is preferable not to add hydrolyzable tannin and its derivative substantially to a boiler water system.
　本発明によれば、縮合型タンニン及び苛性アルカリを所定範囲の比率で併用しているため、ボイラ缶内のみならず他の箇所における腐食も充分に抑制することができ、ボイラ水系のより広範な領域において、腐食の抑制能を向上することができる。 According to the present invention, since condensed tannin and caustic alkali are used in combination within a predetermined range, corrosion not only in the boiler can but also in other places can be sufficiently suppressed, and a wider range of boiler water systems can be obtained. In the region, the ability to suppress corrosion can be improved.

　以下、本発明を実施するための形態について、詳細に説明する。なお、本発明は、以下に説明する実施形態に限定されるものではない。　
Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.
［ボイラ水処理剤］
　先ず、本発明の第１の実施形態に係るボイラ水処理剤について説明する。本実施形態のボイラ水処理剤は、縮合型タンニン及び／又はその誘導体と、苛性アルカリとを所定量比で含有するものであり、ボイラ水系に添加されて腐食抑制などの作用を奏する。 [Boiler water treatment agent]
First, the boiler water treatment agent according to the first embodiment of the present invention will be described. The boiler water treatment agent of this embodiment contains condensed tannin and / or a derivative thereof and caustic alkali in a predetermined amount ratio, and is added to the boiler water system to exert actions such as corrosion inhibition.
（縮合型タンニン）
　一般に、タンニンは加水分解型タンニン及び縮合型タンニンの２群に分類される。このうち、加水分解型タンニンは、酸、アルカリ又は酵素（タンナーゼ）によってアルコール及び酸に分解されるピロガロールタンニン群を指し、具体的には五倍子タンニン、没食子タンニンが挙げられる。 (Condensed tannin)
In general, tannins are classified into two groups: hydrolyzed tannins and condensed tannins. Among these, hydrolyzable tannin refers to a pyrogallol tannin group that is decomposed into an alcohol and an acid by an acid, an alkali, or an enzyme (tannase), and specifically includes a pentaploid tannin and a gallic tannin.
　この加水分解型タンニンは、水処理剤の成分として従来汎用されているが、ボイラ缶内で熱分解して炭酸ガスを発生しやすい。このため、給水中の溶存酸素濃度に適合した量の加水分解型タンニンを使用すると、高濃度の炭酸ガスが発生し、蒸気復水系に移行して復水のｐＨを低下させる。これにより、蒸気復水系や給水系における腐食が促進されてしまう。 This hydrolyzed tannin has been conventionally used as a component of a water treatment agent, but is easily pyrolyzed in a boiler can to generate carbon dioxide. For this reason, if a hydrolyzable tannin in an amount suitable for the dissolved oxygen concentration in the feed water is used, a high concentration of carbon dioxide gas is generated, which shifts to a steam condensate system and lowers the condensate pH. This promotes corrosion in the steam condensate system and the water supply system.
　また、加水分解型タンニンは、アルカリ剤と併存すると速やかに加水分解されて没食子酸などを生成する。そして、没食子酸などでアルカリ剤が中和されるため、アルカリ剤による給水系の腐食抑制作用が阻害されてしまう。このため、本実施形態のボイラ水処理剤は、加水分解型タンニン及びその誘導体を実質的に含有しないことが好ましい。なお、ここでいう「実質的に含有しない」とは、全く含有しないことのみならず、不可避的に混入する僅少量を含有すること、あるいは迂回目的で許容限度内の量を含有することも包含する。 Also, when hydrolyzed tannin coexists with an alkaline agent, it is rapidly hydrolyzed to produce gallic acid and the like. And since an alkali agent is neutralized with gallic acid etc., the corrosion inhibitory action of the water supply system by an alkali agent will be inhibited. For this reason, it is preferable that the boiler water treatment agent of this embodiment does not contain hydrolyzable tannin and its derivative substantially. As used herein, “substantially not containing” includes not only containing at all, but also containing a small amount that is inevitably mixed in, or containing an amount within the allowable limit for detour purposes. To do.
　これに対して縮合型タンニンは、加水分解型タンニンとその一般的性状について類似するものの、化学構造上は異種の化合物群である。縮合型タンニンは優れた脱酸素作用を有するため、腐食抑制能に優れるとともに、縮合型タンニンは、加水分解型タンニンに比べ炭酸ガスを発生しにくいことから、復水のｐＨ低下が抑制され、結果的に蒸気復水系や給水系における腐食が抑制される。このように、縮合型タンニンを用いることで、より広範な領域（例えば、ボイラ缶内、蒸気復水系、給水系）における腐食を充分に抑制できることになる。 Contrary to this, condensed tannin is similar to hydrolyzed tannin in terms of its general properties, but is a heterogeneous group of compounds in terms of chemical structure. Condensed tannin has excellent deoxygenation action, so it has excellent corrosion inhibition ability. Condensed tannin is less likely to generate carbon dioxide than hydrolyzed tannin. In particular, corrosion in the steam condensate system and water supply system is suppressed. Thus, by using condensed tannin, corrosion in a wider area (for example, in a boiler can, a steam condensate system, a feed water system) can be sufficiently suppressed.
　また、縮合型タンニン、特にケプラチョタンニン及びミモザ（ワットル）タンニンは、アルカリ剤と併存してもほとんど加水分解されない。このため、アルカリ剤による給水系の腐食抑制作用の阻害を、抑制することができる。 In addition, condensed tannins, especially keprachotannin and mimosa (wattle) tannin, are hardly hydrolyzed even when coexisting with an alkaline agent. For this reason, the inhibition of the corrosion suppression effect of the water supply system by the alkaline agent can be suppressed.
　このような縮合型タンニンとしては、例えば、フラバノール（いわゆるカテキン）が縮合したカテコールタンニンがある。また、本実施形態のボイラ水処理剤に配合される縮合型タンニンは、特に限定されるものではなく、例えば、ケプラチョタンニン、ミモザタンニン、ラジアータパインタンニン、ガンビアタンニン、マングローブタンニンなどの植物から抽出される縮合型タンニンが挙げられる。更に、これらは１種単独で含有されてもよいし、複数種併せて含有されてもよい。なお、本実施形態のボイラ水処理剤に配合される縮合型タンニンは、植物から抽出及び濃縮した粗生成品であっても、高純度に精製された精製品であってもよい。 Examples of such condensed tannin include catechol tannin condensed with flavanol (so-called catechin). Further, the condensed tannin blended in the boiler water treatment agent of the present embodiment is not particularly limited, for example, extracted from plants such as kepracho tannin, mimosa tannin, radiata pine tannin, gambian tannin, mangrove tannin And condensed tannins. Furthermore, these may be contained alone or in combination of two or more. The condensed tannin blended in the boiler water treatment agent of the present embodiment may be a crude product extracted and concentrated from a plant or a purified product purified to a high purity.
　一方、本実施形態のボイラ水処理剤は、縮合型タンニンの代わりに又は縮合型タンニンとともに、縮合型タンニンの誘導体を含有してもよい。この縮合型タンニンの誘導体には、塩、酸化体、還元体、置換体などが含まれる。例えば、縮合型タンニンの塩としては、縮合型タンニンのアルカリ金属（例えばナトリウム、カリウム）塩、及びアルカリ土類金属（例えばマグネシウム、カルシウム）塩などが挙げられるが、これらに限定されるものではない。また、本実施形態のボイラ水処理剤には、スケール発生防止の点から、アルカリ金属塩を配合することが好ましい。なお、縮合型タンニンの誘導体には、亜硫酸によって漂白処理されたもの、不溶性成分が水溶性になるよう改質処理されたものも含まれる。 On the other hand, the boiler water treatment agent of the present embodiment may contain a condensed tannin derivative instead of or together with the condensed tannin. The condensed tannin derivative includes a salt, an oxidized form, a reduced form, a substituted form, and the like. For example, the salt of condensed tannin includes, but is not limited to, alkali metal (for example, sodium, potassium) salt and alkaline earth metal (for example, magnesium, calcium) salt of condensed tannin. . Moreover, it is preferable to mix | blend an alkali metal salt with the boiler water treatment agent of this embodiment from the point of scale generation prevention. Condensed tannin derivatives include those that have been bleached with sulfurous acid and those that have been modified so that insoluble components are water-soluble.
（苛性アルカリ）
　苛性アルカリは、ボイラ水系における水中のｐＨを所望の範囲に上昇させるとともに、給水に添加することで注入点以降の給水ラインのｐＨも上昇させて、腐食を抑制する目的で配合している。従来、ｐＨを上昇させる目的には、苛性アルカリの他に、炭酸ナトリウム及び炭酸カリウムなどのアルカリ剤も使用されていたが、これらのアルカリ剤には、ボイラ缶内などで分解して炭酸ガスを発生しやすい。このため、これら炭酸塩からなるアルカリ剤を使用すると、多量の炭酸ガスが蒸気復水系に移行し、復水のｐＨを低下させるため、蒸気復水系や給水系における腐食が促進されてしまう。 (Caustic)
Caustic is added for the purpose of suppressing corrosion by increasing the pH of the water in the boiler water system to a desired range and increasing the pH of the water supply line after the injection point by adding it to the water supply. Conventionally, alkali agents such as sodium carbonate and potassium carbonate have been used for the purpose of increasing pH, but sodium carbonate and potassium carbonate are also used for these purposes. Likely to happen. For this reason, when an alkali agent comprising these carbonates is used, a large amount of carbon dioxide gas is transferred to the steam condensate system and the pH of the condensate is lowered, so that corrosion in the steam condensate system and the water supply system is promoted.
　これに対して苛性アルカリは、強塩基であるため、ｐＨを上昇させる効果が高く、腐食抑制能に優れるとともに、炭酸ガスを発生しないため、蒸気復水系や給水系における腐食を促進しない。これにより、苛性アルカリを用いている本実施形態のボイラ水処理剤は、より広範な領域（例えば、ボイラ缶内、蒸気復水系、給水系）における腐食を充分に抑制できることになる。 On the other hand, caustic is a strong base, so it has a high effect of raising pH, has excellent corrosion inhibition ability, and does not generate carbon dioxide, so it does not promote corrosion in steam condensate systems or water supply systems. Thereby, the boiler water treatment agent of this embodiment using caustic can sufficiently suppress corrosion in a wider range (for example, in a boiler can, a steam condensate system, and a feed water system).
　本実施形態のボイラ水処理剤に配合される苛性アルカリは、特に限定されるものではなく、例えば、アルカリ金属又はアルカリ土類金属の水酸化物などが挙げられるが、特に、スケール発生防止の点から、ナトリウム及びカリウムなどのアルカリ金属の水酸化物を使用することが好ましい。 The caustic alkali to be blended in the boiler water treatment agent of the present embodiment is not particularly limited, and examples thereof include alkali metal or alkaline earth metal hydroxides. Therefore, it is preferable to use hydroxides of alkali metals such as sodium and potassium.
　また、本実施形態のボイラ水処理剤では、縮合型タンニン及び／又はその誘導体の含有量（Ａ）に対する苛性アルカリの含有量（Ｂ）の質量比（Ｂ／Ａ）が０．４以上である。Ｂ／Ａが０．４未満になると、ボイラ缶内で消費された後の苛性アルカリの残存量が不足するため、腐食の抑制が不充分になる。特に、純水が給水されるボイラ、復水回収率の高いボイラ、補給する軟水のＭアルカリ度が低いボイラなどでは、ボイラ水系を流通する水のｐＨが大幅に低下し、ボイラ缶内などでの腐食が顕著化しやすくなる。Ｂ／Ａは、好ましくは０．８以上、より好ましくは１．０以上である。なお、Ｂ／Ａの上限は、特に限定されないが、費用対効果及びボイラ水の濃縮倍数への影響の観点から、通常は１０以下とすることが望ましい。 Moreover, in the boiler water treatment agent of this embodiment, the mass ratio (B / A) of the content (B) of caustic alkali to the content (A) of condensed tannin and / or its derivative is 0.4 or more. . When B / A is less than 0.4, the remaining amount of caustic alkali after being consumed in the boiler can is insufficient, so that the suppression of corrosion becomes insufficient. In particular, in boilers with pure water supply, boilers with high condensate recovery, boilers with low M alkalinity of soft water to be replenished, the pH of water circulating in the boiler water system is greatly reduced, such as in boiler cans Corrosion of the steel becomes prominent. B / A is preferably 0.8 or more, more preferably 1.0 or more. In addition, although the upper limit of B / A is not specifically limited, It is normally desirable to set it as 10 or less from a viewpoint of the cost-effectiveness and the influence on the concentration multiple of boiler water.
（スケール分散剤）
　本実施形態のボイラ水処理剤は、前述した成分に加えて、更に、スケール分散剤を含有することが好ましい。これにより、ボイラ缶内におけるスラッジの堆積が抑制されるため、堆積したスラッジによる腐食（例えば、ボイラ停止時のようにボイラ圧力が低い間に、ボイラ缶内に混入した外気中の酸素が水に溶解し、水とスラッジ下部との酸素濃度差による酸素濃淡電池による腐食）を予防することができる。 (Scale dispersant)
It is preferable that the boiler water treatment agent of this embodiment further contains a scale dispersant in addition to the components described above. As a result, the accumulation of sludge in the boiler can is suppressed, so that the corrosion of the accumulated sludge (for example, the oxygen in the outside air mixed in the boiler can be converted into water while the boiler pressure is low as when the boiler is stopped). It is possible to prevent the corrosion by the oxygen concentration cell due to the difference in oxygen concentration between the water and the sludge lower portion.
　このスケール分散剤は、特に限定されるものではなく、例えば、ポリアクリル酸ナトリウム、ポリアクリル酸・アクリルアミドメチルプロパンスルホン酸又はその塩などのアクリル酸系ポリマー及びコポリマー、ポリマレイン酸ナトリウム、ポリメタクリル酸ナトリウム、カルボキシメチルセルロース（ナトリウム）、重合リン酸又はその塩などを使用することができる。また、これら分散剤は、単独で配合してもよく、また、２種以上を組み合わせて配合してもよい。 The scale dispersant is not particularly limited, and examples thereof include acrylic acid polymers and copolymers such as sodium polyacrylate, polyacrylic acid / acrylamidomethylpropane sulfonic acid or salts thereof, sodium polymaleate, polysodium methacrylate. Carboxymethylcellulose (sodium), polymerized phosphoric acid or a salt thereof, and the like can be used. Moreover, these dispersing agents may be mix | blended independently and may be mix | blended in combination of 2 or more type.
（その他）
　本実施形態のボイラ水処理剤は、更に、防食剤などの任意成分を含有してもよい。防食剤には、ボイラ缶内に防食皮膜を形成することで腐食を防止するもの、揮発して蒸気系に移行し蒸気凝縮水のｐＨを上昇するもの、蒸気復水系配管の表面に皮膜を形成し配管の腐食を抑制するものなどがあるが、特に限定されず、本実施形態のボイラ水処理剤では、周知のものを使用することができる。 (Other)
The boiler water treatment agent of this embodiment may further contain optional components such as anticorrosives. Anticorrosives are those that prevent corrosion by forming an anticorrosion film in the boiler can, those that volatilize and move to the steam system to raise the pH of the steam condensate, and form a film on the surface of the steam condensate system However, it is not particularly limited, and a boiler water treatment agent according to the present embodiment may be a well-known one.
　具体的には、ボイラ缶内の防食剤としては、グルコン酸（塩）、α－グルコヘプトン酸（塩）などのアルドン酸（塩）、コハク酸（塩）、クエン酸（塩）、リンゴ酸（塩）などの多価カルボン酸（塩）、グルタミン酸（塩）などのアミノ酸（塩）などが挙げられる。蒸気復水管の防食材としては、アミノメチルプロパノール、モノイソプロパノールアミン、シクロヘキシルアミン、ジエチルエタノールアミン、モルホリンなどの中和性アミン、オクタデシルアミンなどの長鎖脂肪族アミンが挙げられる。 Specifically, the anticorrosive agent in the boiler can includes aldonic acid (salt) such as gluconic acid (salt) and α-glucoheptonic acid (salt), succinic acid (salt), citric acid (salt), malic acid ( Salt) and other amino acid (salt) such as glutamic acid (salt). Examples of the anticorrosive material for the steam condensate include neutral amines such as aminomethylpropanol, monoisopropanolamine, cyclohexylamine, diethylethanolamine and morpholine, and long-chain aliphatic amines such as octadecylamine.
　前述したように、蒸気ドレンの凝縮水の一部又は全部を復水として回収するボイラ水系において、加水分解型タンニンを用いた場合、多量の炭酸ガスが発生するため、水のｐＨを所定範囲に調節するために揮発性の中和性アミンなどの防食剤を多量に添加しなければならない。これに対して、本実施形態のボイラ水処理剤は、縮合型タンニン及び／又はその誘導体を配合しているため、加水分解型タンニンを使用する場合に比べて、揮発性の中和性アミンなどの防食剤の配合量を低減することができる。 As described above, when hydrolyzed tannin is used in a boiler water system that recovers part or all of condensate of steam drain as condensate, a large amount of carbon dioxide gas is generated. In order to adjust, a large amount of an anticorrosive agent such as a volatile neutralizing amine must be added. On the other hand, since the boiler water treatment agent of this embodiment is blended with condensed tannin and / or a derivative thereof, compared with the case where hydrolyzed tannin is used, a volatile neutralizing amine, etc. The amount of the anticorrosive agent can be reduced.
［水処理方法］
　次に、本発明の第２の実施形態に係る水処理方法について説明する。本実施形態の水処理方法は、前述した第１の実施形態の水処理剤を使用して、ボイラ水系における腐食の発生などを抑制する方法である。 [Water treatment method]
Next, a water treatment method according to the second embodiment of the present invention will be described. The water treatment method of the present embodiment is a method for suppressing the occurrence of corrosion in the boiler water system using the water treatment agent of the first embodiment described above.
　具体的には、本実施形態の水処理方法においては、ボイラ水系に、縮合型タンニン及び／又はその誘導体と、苛性アルカリとを、縮合型タンニン及び／又はその誘導体の添加量（Ａ）に対する苛性アルカリの添加量（Ｂ）の質量比（Ｂ／Ａ）が０．４以上になるように添加する工程を有する。これにより、前述の通り、ボイラ缶内のみならず他の箇所における腐食が充分に抑制されるため、ボイラ水系のより広範な領域における腐食の抑制能を向上できる。 Specifically, in the water treatment method of the present embodiment, condensed tannin and / or its derivative and caustic alkali are added to the boiler water system, and caustic to the added amount (A) of condensed tannin and / or its derivative. It has the process of adding so that the mass ratio (B / A) of the addition amount (B) of alkali may be 0.4 or more. Thereby, as above-mentioned, since corrosion not only in a boiler can but in another location is fully suppressed, the ability to suppress corrosion in a wider area of the boiler water system can be improved.
　また、本実施形態の水処理方法では、ボイラ水系に、前述した成分に加えて、更に、スケール分散剤を添加することが好ましい。これにより、ボイラ缶内におけるスラッジの堆積が抑制されるため、堆積したスラッジによる腐食を予防することができる。 Moreover, in the water treatment method of the present embodiment, it is preferable to add a scale dispersant to the boiler water system in addition to the components described above. Thereby, since accumulation of sludge in a boiler can is controlled, corrosion by accumulated sludge can be prevented.
　更に、ボイラ水系には、加水分解型タンニン及びその誘導体を実質的に添加しないことが好ましい。これにより、没食子酸などによるボイラ水系の腐食抑制作用の阻害を抑制することができる。ここで「実質的に添加しない」とは、全く添加しないことのみならず、不可避的に僅少量が混入して添加されること、あるいは迂回目的で許容限度内の量を添加することも包含する。 Furthermore, it is preferable that substantially no hydrolyzable tannin and its derivatives are added to the boiler water system. Thereby, inhibition of the corrosion inhibitory action of the boiler water system by gallic acid or the like can be suppressed. Here, “substantially not add” includes not only adding at all, but also unavoidably adding a very small amount, or adding an amount within an allowable limit for detour purposes. .
　更にまた、各成分の添加箇所は、特に限定されるものではなく、ボイラ水系の任意の箇所を適宜選択することができる。通常は、スケールや腐食を抑制すべき箇所又はその上流であり、例えば、給水系でもよい。なお、ボイラ水系への各成分の添加は、その一部又は全部を混合した後に行ってもよいし、各々独立に行ってもよい。ここで、独立に添加するとは、独立のタイミング及び／又は独立の箇所に添加することを指す。 Furthermore, the addition location of each component is not particularly limited, and an arbitrary location of the boiler water system can be appropriately selected. Usually, it is the location which should suppress a scale and corrosion, or its upstream, for example, a water supply system may be sufficient. In addition, the addition of each component to the boiler water system may be performed after mixing part or all of them, or may be performed independently. Here, adding independently means adding to an independent timing and / or an independent location.
　なお、ボイラ水系に添加する成分の詳細は、前述した第１の実施形態において述べたボイラ水処理剤と同様であるため、省略する。 In addition, since the detail of the component added to a boiler water system is the same as that of the boiler water processing agent described in 1st Embodiment mentioned above, it abbreviate | omits.
　以下、本発明の実施例及び比較例を挙げて、本発明の効果について具体的に説明する。先ず、本発明の第１実施例として、ケブラチョタンニン（種類：Ａ）、ワットルタンニン（種類：Ｂ）、及び五倍子タンニン（種類：Ｃ）を使用して、下記表１に示す組成の実施例１～４及び比較例１～３のボイラ水処理剤を調製した。その際、アルカリ剤には、ＮａＯＨ（種類：ａ）又はＫＯＨ（種類：ｂ）を使用し、スケール分散剤には、ポリアクリル酸ナトリウム（種類：α）を使用した。 Hereinafter, the effects of the present invention will be described in detail with reference to examples and comparative examples of the present invention. First, as a first example of the present invention, the composition shown in Table 1 below was carried out using quebracho tannin (type: A), wattle tannin (type: B), and pentaploid tannin (type: C). The boiler water treatment agents of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared. At that time, NaOH (type: a) or KOH (type: b) was used as the alkali agent, and sodium polyacrylate (type: α) was used as the scale dispersant.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　そして、軟化水（２５℃、Ｍアルカリ度：１５ｍｇＣａＣＯ３／Ｌ）を給水として、ステンレス鋼製の自然循環型テストボイラ（保有水量５Ｌ）を運転し、その給水中に実施例及び比較例の各ボイラ水処理剤を添加した。その際、ボイラの運転条件は、圧力：１．２ＭＰａ、蒸発量：７．２Ｌ／時間、ブロー量：０．８Ｌ／時間、濃縮度：１０倍とした。下記表２に、実施例及び比較例の各ボイラ水処理剤を添加したときのボイラ運転結果を示す。 And, using softened water (25 ° C., M alkalinity: 15 mg CaCO 3 / L) as water supply, a stainless steel natural circulation type test boiler (retained water amount 5 L) is operated, and each of the examples and comparative examples is included in the water supply. A boiler water treatment agent was added. At that time, the operating conditions of the boiler were as follows: pressure: 1.2 MPa, evaporation amount: 7.2 L / hour, blow amount: 0.8 L / hour, enrichment: 10 times. Table 2 below shows the boiler operation results when the boiler water treatment agents of Examples and Comparative Examples were added.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　上記表２に示すように、実施例１～４のボイラ水処理剤を添加した場合は、給水系、ボイラ缶内、及び蒸気復水系のいずれにおいても、総合的に腐食速度が低く、蒸気凝縮水中の酸素濃度及び炭酸ガス濃度が低かった。これに対して、比較例２及び３のボイラ水処理剤では、給水系、ボイラ缶内、及び蒸気復水系のいずれにおいても、特に給水系及び蒸気復水系における腐食速度が極めて高く、蒸気凝縮水中の酸素濃度及び炭酸ガス濃度が高かった。これにより、苛性アルカリと併用するタンニンとして、ボイラ水系のより広範な領域における腐食の抑制能を向上できる点で、縮合型タンニンは加水分解型タンニンよりも有用であることが確認された。 As shown in Table 2 above, when the boiler water treatment agents of Examples 1 to 4 are added, the corrosion rate is low overall in any of the water supply system, the boiler can, and the steam condensate system. The oxygen concentration and carbon dioxide concentration in water were low. On the other hand, in the boiler water treatment agents of Comparative Examples 2 and 3, the corrosion rate is particularly high in the feed water system and the steam condensate system in any of the feed water system, the boiler can, and the steam condensate system. The oxygen concentration and carbon dioxide concentration were high. As a result, it was confirmed that condensed tannin is more useful than hydrolyzed tannin in that the ability to suppress corrosion in a wider area of the boiler water system can be improved as tannin used in combination with caustic.
　また、比較例１のボイラ水処理剤では、給水系、ボイラ缶内、及び蒸気復水系のいずれにおいても腐食速度が高く、特にボイラ缶内における腐食速度は極めて高かった。これにより、縮合型タンニン及び／又はその誘導体の含有量（Ａ）に対する苛性アルカリの含有量（Ｂ）の質量比（Ｂ／Ａ）を０．４以上にすることで、給水のＭアルカリ度が１５ｍｇＣａＣＯ３／Ｌと比較的低いボイラにおいても、より広範な領域、特にボイラ缶内における腐食の抑制能を向上できることが確認された。 In the boiler water treatment agent of Comparative Example 1, the corrosion rate was high in any of the water supply system, the boiler can, and the steam condensate system, and particularly the corrosion rate in the boiler can was extremely high. Thereby, the M alkalinity of the feed water is increased by setting the mass ratio (B / A) of the content (B) of the caustic alkali to the content (A) of the condensed tannin and / or derivative thereof to 0.4 or more. It was confirmed that even in a boiler with a relatively low value of 15 mg CaCO 3 / L, the ability to inhibit corrosion in a wider area, particularly in a boiler can, can be improved.
　更に、実施例１～３のボイラ水処理剤は、実施例４のボイラ水処理剤に比べて、給水系、ボイラ缶内、及び蒸気復水系のいずれにおいても腐食速度が低く、特にボイラ缶内における腐食速度が大幅に低かった。これにより、縮合型タンニン及び／又はその誘導体と、苛性アルカリとともにスケール分散剤を併用することで、広範な領域、特にボイラ缶内における腐食をより抑制できることが確認された。 Furthermore, the boiler water treatment agent of Examples 1 to 3 has a lower corrosion rate in any of the water supply system, the boiler can, and the steam condensate system than the boiler water treatment agent of Example 4, and particularly in the boiler can. The corrosion rate at was significantly lower. Thereby, it was confirmed that the corrosion in a wide area | region, especially a boiler can can be suppressed more by using together a scale type dispersing agent with condensed tannin and / or its derivative, and a caustic alkali.
　次に、本発明の第２実施例として、下記表３に示す組成のボイラ水処理剤を使用して、復水回収率を５０％、給水温度を４０℃とした点以外は、前述した第１実施例と同様の手順で、ボイラ運転を行った。その結果を下記表４に示す。 Next, as a second embodiment of the present invention, the boiler water treatment agent having the composition shown in Table 3 below was used, except that the condensate recovery rate was 50% and the feed water temperature was 40 ° C. The boiler operation was performed in the same procedure as in Example 1. The results are shown in Table 4 below.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上記表４に示すように、実施例５のボイラ水処理剤では、比較例４のボイラ水処理剤に比べて、給水系、ボイラ缶内及び蒸気復水系のいずれにおいて、特に給水系及び蒸気復水系において腐食速度が低く、蒸気凝縮水中の酸素濃度及び炭酸ガス濃度が低かった。 As shown in Table 4 above, in the boiler water treatment agent of Example 5, compared with the boiler water treatment agent of Comparative Example 4, in any of the water supply system, the boiler can and the steam condensate system, The corrosion rate was low in the water system, and the oxygen concentration and carbon dioxide concentration in the steam condensed water were low.
　また、この実施例５及び比較例４の各ボイラ水処理剤について、蒸気凝縮水のｐＨ（２５℃）を測定し、ｐＨを７．０又は８．５に調整するために費やされたモノイソプロパノールアミン（中和性アミン）の添加濃度を求めた。その結果を下記表５に示す。 Moreover, about each boiler water treatment agent of this Example 5 and the comparative example 4, it measured the pH (25 degreeC) of steam condensate water, and was spent for adjusting pH to 7.0 or 8.5. The addition concentration of isopropanolamine (neutralizing amine) was determined. The results are shown in Table 5 below.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　上記表５に示すように、実施例５のボイラ水処理剤では、比較例４のボイラ水処理剤に比べて、いずれのｐＨ値に調節するのに必要な中和性アミン量も少なかった。これにより、苛性アルカリと併用するタンニンとして、防食剤の使用量を削減できる点で、縮合型タンニンは加水分解型タンニンよりも有用であることが確認された。 As shown in Table 5 above, in the boiler water treatment agent of Example 5, the amount of neutralizing amine required to adjust to any pH value was less than that of the boiler water treatment agent of Comparative Example 4. As a result, it was confirmed that condensed tannin is more useful than hydrolyzed tannin in that the amount of anticorrosive used as tannin combined with caustic can be reduced.

Claims (6)

  1. 　縮合型タンニン及び／又はその誘導体と、苛性アルカリとを含有するボイラ水処理剤であって、
    　縮合型タンニン及び／又はその誘導体の含有量（Ａ）に対する苛性アルカリの含有量（Ｂ）の質量比（Ｂ／Ａ）が０．４以上であるボイラ水処理剤。     A boiler water treatment agent containing condensed tannin and / or a derivative thereof and caustic,
    A boiler water treatment agent having a mass ratio (B / A) of a caustic content (B) to a content (A) of condensed tannin and / or a derivative thereof is 0.4 or more.
  2. 　スケール分散剤を更に含有する請求項１記載のボイラ水処理剤。 The boiler water treatment agent according to claim 1, further comprising a scale dispersant.
  3. 　加水分解型タンニン及びその誘導体を実質的に含有しない請求項１又は２記載のボイラ水処理剤。 The boiler water treatment agent according to claim 1 or 2, substantially free from hydrolyzable tannin and its derivatives.
  4. 　ボイラ水系における水処理方法であって、
    　前記ボイラ水系に、縮合型タンニン及び／又はその誘導体と、苛性アルカリとを、縮合型タンニン及び／又はその誘導体の添加量（Ａ）に対する苛性アルカリの添加量（Ｂ）の質量比（Ｂ／Ａ）が０．４以上になるように添加する水処理方法。     A water treatment method in a boiler water system,
    Condensed tannin and / or its derivative and caustic are added to the boiler water system, and the mass ratio (B / A) of the added amount (B) of caustic to the added amount (A) of condensed tannin and / or its derivative ) Is a water treatment method to be added so as to be 0.4 or more.
  5. 　前記ボイラ水系に、スケール分散剤を更に添加する請求項４記載の水処理方法。 The water treatment method according to claim 4, wherein a scale dispersant is further added to the boiler water system.
  6. 　前記ボイラ水系に、加水分解型タンニン及びその誘導体を実質的に添加しない請求項４又は５記載の水処理方法。 The water treatment method according to claim 4 or 5, wherein substantially no hydrolyzable tannin or a derivative thereof is added to the boiler water system.
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