JP4096288B2 - Water treatment agent for steam generation plant - Google Patents
Water treatment agent for steam generation plant Download PDFInfo
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- JP4096288B2 JP4096288B2 JP2001348236A JP2001348236A JP4096288B2 JP 4096288 B2 JP4096288 B2 JP 4096288B2 JP 2001348236 A JP2001348236 A JP 2001348236A JP 2001348236 A JP2001348236 A JP 2001348236A JP 4096288 B2 JP4096288 B2 JP 4096288B2
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- tannin
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Description
【0001】
【発明の属する技術分野】
本発明は、ボイラその他の高温水・蒸気発生プラントの腐食防止のために、該プラントに添加される水処理剤に関する。
【0002】
【従来の技術】
ボイラ等の蒸気発生設備を備える水系プラントに対して供給される給水中に含まれている溶存酸素は、ボイラ缶体や蒸気復水経路その他の水系プラント設備の腐食原因となる。このため、現在では、蒸気発生プラントに供給される給水に対して溶存酸素除去作用のある水処理剤を添加し、給水中の溶存酸素を除去する技術が一般的に普及している。
【0003】
前記水処理剤として、天然有機物系のタンニン、タンニン酸及びその加水分解物である没食子酸等の還元性フェノールを包含するタンニン類は、安全性等の点で有利であるとともに、酸素除去作用に加えて金属表面に対する防食皮膜形成能を有する。このため、ボイラ等の高温水系、蒸気発生プラント系において、タンニン類が腐食抑制剤として利用されている。
【0004】
ここで、タンニンは酸性であることから、中和剤として、アルカリ剤をタンニンと同時にプラントへ添加する場合が多い。使用されるアルカリ剤としては、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム等の中から、その作用、機能の違いが特別検討されることがなく、適宜選択されているのが現状であり、強いて言えば、主にコスト面から水酸化ナトリウム又は炭酸ナトリウムが採用されることが多かった。
【0005】
【発明が解決しようとする課題】
しかしながら、アルカリ剤として、水酸化ナトリウム又は炭酸ナトリウムを採用し、これらをタンニンに配合させた水処理剤を製造する場合においては、タンニン濃度を高めていくと、前記水処理剤を貯留する薬液タンク内で、次第に析出物が生成し、沈殿が発生してしまうという技術的課題が新たに見出された。
【0006】
前記技術的課題は、タンニン濃度を低減するという対策によって解決可能であるが、タンニン濃度の低下、とりわけタンニン濃度が7重量%未満となると、タンニンによってもたらされる溶存酸素除去作用が急激に低下するという事態を招ねく。この事態を防止するためには、水処理剤の大量添加を行って、水系中のタンニンの絶対量を確保するという対策が考えられるが、この対策は、水処理剤の単位量当たりの処理効率が悪化し、水処理剤の使用量が増えてコスト高にもなるので採用することはできない。
【0007】
そして、純度の低いタンニン抽出物を選択して使用し、高濃度のタンニン水溶液を製造して用いると、タンニン抽出物に含まれているタンニン以外の他の有機化合物等により、薬剤がゲル化してしまい、取り扱いが困難になってしまうという問題もある。
【0008】
また、薬液タンク内での沈殿を無くすための抜本的対策として、タンニン水溶液とアルカリ剤水溶液を別々の薬液タンクに貯留し、水系プラントに別々に添加することが考えられる。しかし、二つの薬液タンクとそれに付随する添加設備が必要になるので設備が複雑化し、設備コストも嵩み、更には薬剤の管理が二系統になるため、作業が煩雑となってしまう。
【0009】
更には、アルカリ剤として、従来から一般的に用いられてきた炭酸ナトリウム、炭酸カリウムその他の炭酸塩は、高温水中で熱分解して炭酸ガスが発生し、この炭酸ガスが蒸気復水系配管に移行して、配管の腐食を増大させるという技術的課題があった。
【0010】
そこで、本発明では、一液で高い酸素除去作業を有するとともに、薬液タンク内での析出及び沈澱(ゲル化物)の生成がない蒸気発生プラント用水処理剤を提供することを目的とする。
【0011】
【課題を解決するための手段】
上記目的を達成し、上記技術的課題を解決するために、本発明では、蒸気発生プラント水系中の溶存酸素を除去するための一液型の水処理剤であって、少なくとも、タンニンとして加水分解型タンニンを7重量%以上と、アルカリ剤として水酸化カリウムを前記タンニンに対して重量比で0.5倍以上とを含有し、各成分が予め混合され一液化されていることを特徴とする蒸気発生プラント用水処理剤を提供する。
【0012】
この本発明に係る蒸気発生プラント用水処理剤は、タンニンが高濃度で配合されていながら、薬液タンク内での析出物、沈殿物(ゲル化物)が生成してしまうことがないため、取り扱いが容易である。また、前記水処理剤は、タンニンが高濃度で配合されている構成であるので、少ない添加量でプラントの腐食抑制を確実に行うことが可能となる。
【0013】
なお、本発明に係る蒸気発生プラント用水処理剤においては、タンニン及びタンニン抽出物の配合濃度をより好ましくは9重量%以上、更に好ましくは11重量%以上とする。本発明で採用するタンニンは、加水分解型タンニンであり、例えば、五倍子タンニン、没食子タンニン、スマックタンニン、タラタンニン、バロニアタンニン、チェストナットタンニン等を挙げることができる。また、特にコスト面を考慮して、タンニン分として90%以下の純度の低いタンニン抽出物を使用することも可能である。
【0014】
本発明では、タンニンの配合量、種類によらず、アルカリ剤である水酸化カリウムを、重量比でタンニンの0.5倍以上を含むように構成する。これは、水酸化カリウムが、重量比でタンニンの0.5倍未満になると、タンニンがボイラ水中において、タンニンが加水分解されて生じる没食子酸等のフェノール酸及びこれらが分解して生じる有機酸を完全に中和することができなくなるからであり、この結果、ボイラ水のpHが低下して腐食が進行してしまうからである。
【0015】
また、本発明では、必要に応じて、亜硫酸(塩)、重亜硫酸(塩)、メタ重亜硫酸(塩)、アスコルビン酸(塩)、エリソルビン酸(塩)、没食子酸(塩)、没食子酸プロピル、グルコース等の脱酸素剤、リン酸(塩)、トリポリリン酸(塩)、ヘキサメタリン酸(塩)、ポリアクリル酸(塩)、アクリル酸とアクリルアミドメチルプロパンスルホン酸のコポリマー(塩)等のスケール防止剤、分散剤、リグニンスルホン酸(塩)、グルコヘプトン酸(塩)、コハク酸(塩)、グルコン酸(塩)、クエン酸(塩)、リンゴ酸(塩)、グルタミン酸(塩)等の防食剤、2−アミノ−2−メチル−1−プロパノール、モルホリン、ジエチルエタノールアミン、アンモニア、シクロヘキシルアミン等の給復水系処理剤を併用してよい。これらの薬剤は、予め本発明に係る水処理剤中に配合してもよく、プラント水系に別添加してもよい。
【0016】
以上のように、本発明は、高い酸素除去作用を発揮できるとともに、かつ薬液タンク内での析出及び沈殿(ゲル化物)の発生がないという機能を備える蒸気発生プラント用水処理剤を提供するという技術的意義を有している。
【0017】
【実施例】
実施例1〜6。
タンニンと水酸化カリウム(KOH)をそれぞれ後掲する表1に示す濃度とした薬液を調整し、容量500mlのポリプロピレン製容器に300g入れ、該容器の蓋に直径5mmの穴を開け、30℃にて静置保管した。これを表1に示す濃度条件毎に4サンプル作製し、1週間後、2週間後、3週間後、4週間後に各条件群から1サンプルずつ取り出して、薬液の析出、沈殿状況を確認した。なお、本実施例で採用したタンニンは、高純度五倍子タンニン(局方タンニン)(表1中、Aで示す。)、五倍子タンニン抽出物(粗生成品)(表1中、Bで示す。)、チェストナットタンニン抽出物(粗生成品)(表1中、Cで示す。)である。
【0018】
【実施例】
結果。
実施例1〜6は、1〜4週間後のいずれにおいても、析出や沈殿がなく、薬液が非常に安定していることが明らかになった。より具体的には、実施例1〜6のすべてにおいて薬液の安定性が実証されたことから、タンニンに配合されるアルカリ剤として水酸化カリウムが非常に適していること、7.0重量%以上のタンニンが配合された薬液においても、水酸化カリウムを重量比でタンニンに対して0.5倍以上配合することによって、析出又は沈殿の発生を確実に防止できることがわかった。
【0019】
比較例1〜10。
タンニンと水酸化ナトリウム(NaOH)又は炭酸ナトリウム(Na2CO3)をそれぞれ後掲する表1に示す濃度とした薬液を調整し、容量500mlのポリプロピレン製容器に300g入れ、該容器の蓋に直径5mmの穴を開け、30℃にて静置保管した。これを表1に示す各濃度条件毎に4サンプル作製し、1週間後、2週間後、3週間後、4週間後に各条件群から1サンプルずつ取り出して、薬液の析出、沈殿状況を確認した。なお、本比較例で採用したタンニンは、高純度五倍子タンニン(局方タンニン)(表1中、Aで示す。)、五倍子タンニン抽出物(粗生成品)(表1中、Bで示す。)、チェストナットタンニン抽出物(粗生成品)(表1中、Cで示す。)である。
【0020】
結果。
上記比較例では、タンニン濃度が6.0重量%と低い比較例1を除き、時間が経過するにつれて、薬液中に析出又は沈殿が発生し、薬液が不安定化することが明らかになった。これにより、本発明に係る蒸気発生プラント用水処理剤は、タンニン濃度が高い場合でも、酸薬液が安定であることが実証できた。
【0021】
【表1】
【0022】
なお、表1における実1〜7は実施例1〜7、比1〜10は比較例1〜10をそれぞれ表している。表1の○は、析出又は沈殿が観察されず薬液が安定していると判定されたもの、×は、析出又は沈殿が観察され薬液が不安定と判定されたものを示している。
【0023】
実施例8,9。
容量5Lの実機蒸気発生プラントを模擬した試験装置に、25℃で空気中の酸素で飽和させた軟化水(酸消費量4.8 10mgCaCO3/L)を給水し、この給水に対して後掲する表2に示した配合の水処理剤を添加し、圧力1MPa、蒸気発生量10L/hr、ブロー率10%の各条件で運転し、蒸気を発生させた。発生した蒸気を熱交換器で冷却して凝縮水とし、45℃に調整してからテストピースカラムに通水した。このカラムの内部に、予め炭素鋼(SS400)製のテストピース(50×30×1mm)を設置しておき、これらのテストピースの96時間の腐食量を測定し、腐食速度を算出し、これを蒸気復水系の腐食速度とした。また、蒸気凝縮水を20℃に冷却し、この水中に溶存酸素濃度及び溶存酸素二酸化濃度を測定した。
【0024】
比較例11〜13。
後掲する表2に示した種類及び配合の水処理剤を実施例8,9同様に給水に対して添加し、実施例8、9同様の手法で測定を行った。以上の実施例8,9及び比較例11〜13に関する測定結果を次の表2に示す。
【0025】
【表2】
【0026】
結果。
前掲した表2に示されているように、実施例8,9は、比較例11〜13よりも腐食速度が遅いことが明かである。このことから、本発明に係る蒸気発生プラント用水処理剤は、腐食抑制作用が充分に発揮されていることが実証できた。
【0027】
具体的には、タンニンの種類と、タンニンとアルカリ剤の配合構成とが全く同じ条件であって、アルカリ剤が水酸化カリウムである実施例9と、アルカリ剤が炭酸カリウム(K2CO3)である比較例12を比べると、特に蒸気復水系の腐食速度において、実施例9では8.8mdd、比較例12では22mddと大きな差が生じ、実施例9は、比較例12の40%の腐食速度であった。このことから、水酸化カリウムは、タンニンの腐食抑制作用を充分に発揮させるためのアルカリ剤として特に好適であることが明らかになった。
【0028】
また、表2によれば、アルカリ剤が水酸化カリウムである実施例8,9は、アルカリ剤が炭酸カリウムである比較例11に比べて、蒸気凝縮水中の二酸化炭素濃度を低く抑えることができるという作用が発揮されることが明らかであるので、蒸気復水系配管の腐食を抑制できる。
【0029】
更に、表2を参照して、実施例8と比較例13を比べると、タンニンに対して重量比50%(6.5÷13.0)以上の構成である実施例8の方が、同重量比38%(5.0÷13.0)である比較例13よりも、ボイラ内の腐食速度、蒸気凝縮水中の溶存酸素濃度、蒸気復水系の腐食速度のいずれにおいても良い成績が得られた。
【0030】
このことから、タンニンに対して水酸化カリウムを重量比0.5倍以上添加することにより、水酸化カリウムが、タンニンが加水分解されて生じる没食子酸等のフェノール酸やそれらが分解して生じる有機酸を完全に中和してボイラ水のpHの低下を防止し、腐食を確実に抑制していることが明らかである。即ち、前記重量比0.5倍以上という数値には臨界的意義が存在することが実証できた。
【0031】
【発明の効果】
本発明に係る蒸気発生プラント用水処理剤は、タンニン配合濃度が高い構成でありながら、薬液タンク内での析出物、沈殿物が生成してしまうことがないため、タンニンとアルカリ剤を、薬液タンクにおいて一液で取り扱うことができるので、装置構成を簡素化でき、作業や管理も容易であるという有利な効果が奏される。
【0032】
また、前記水処理剤は、タンニン配合濃度が高いので、少ない添加量でプラントの腐食抑制を確実に行うことができるという有利な効果が奏される。[0001]
BACKGROUND OF THE INVENTION
The present invention, in order to prevent corrosion of the boiler other high temperature water and steam generating plant, relates to a water treatment agent added to the plant.
[0002]
[Prior art]
The dissolved oxygen contained in the feed water supplied to the water-based plant equipped with steam generation equipment such as a boiler causes corrosion of the boiler can body, the steam condensate path and other water-based plant equipment. For this reason, at present, a technique for removing dissolved oxygen in the feed water by adding a water treatment agent having a function of removing dissolved oxygen to the feed water supplied to the steam generation plant is generally widespread.
[0003]
As the water treatment agent, tannins including natural organic tannins, tannic acid and reducing phenols such as gallic acid which is a hydrolyzate thereof are advantageous in terms of safety and the like, and have an oxygen removal effect. In addition, it has the ability to form an anticorrosive film on the metal surface. For this reason, tannins are used as corrosion inhibitors in high-temperature water systems such as boilers and steam generation plant systems.
[0004]
Here, since tannin is acidic, an alkali agent is often added to the plant simultaneously with tannin as a neutralizing agent. The alkali agent used is currently selected from sodium hydroxide, potassium hydroxide, sodium carbonate, etc., without any special consideration on the difference in action and function, and is currently selected. In other words, sodium hydroxide or sodium carbonate was often adopted mainly from the viewpoint of cost.
[0005]
[Problems to be solved by the invention]
However, in the case of producing a water treatment agent in which sodium hydroxide or sodium carbonate is used as an alkaline agent and these are mixed with tannin, a chemical tank that stores the water treatment agent as the tannin concentration is increased. In particular, a new technical problem has been found that precipitates are gradually formed and precipitation occurs.
[0006]
The technical problem can be solved by measures to reduce the tannin concentration. However, when the tannin concentration is lowered, especially when the tannin concentration is less than 7% by weight, the dissolved oxygen removal effect caused by the tannin is drastically reduced. Invite the situation. In order to prevent this situation, a measure to add a large amount of water treatment agent to ensure the absolute amount of tannin in the water system can be considered, but this measure depends on the treatment efficiency per unit amount of the water treatment agent. However, the amount of water treatment agent used increases and the cost becomes high, so it cannot be adopted.
[0007]
Then, when a low-purity tannin extract is selected and used to produce and use a high-concentration tannin aqueous solution, the drug is gelled by other organic compounds other than tannin contained in the tannin extract. Therefore, there is also a problem that handling becomes difficult.
[0008]
In addition, as a drastic measure for eliminating precipitation in the chemical solution tank, it is conceivable to store the tannin aqueous solution and the alkaline agent aqueous solution in separate chemical solution tanks and add them separately to the aqueous plant. However, since two chemical tanks and additional equipment associated therewith are required, the equipment becomes complicated, the equipment cost increases, and the management of the medicine becomes two systems, which complicates the work.
[0009]
Furthermore, sodium carbonate, potassium carbonate, and other carbonates that have been commonly used as alkali agents have been pyrolyzed in high-temperature water to generate carbon dioxide, and this carbon dioxide is transferred to steam condensate piping. Thus, there has been a technical problem of increasing the corrosion of the piping.
[0010]
Therefore, an object of the present invention is to provide a water treatment agent for a steam generation plant that has a high oxygen removal operation with a single solution and that does not generate precipitation and precipitation (gelation product) in a chemical solution tank.
[0011]
[Means for Solving the Problems]
In order to achieve the above object and solve the above technical problem, the present invention is a one-component water treatment agent for removing dissolved oxygen in a steam generating plant water system, and at least hydrolyzed as tannin. It contains 7% by weight or more of type tannin and 0.5 times or more by weight ratio of potassium hydroxide as an alkali agent with respect to the tannin, and each component is premixed and made into one solution. A water treatment agent for a steam generation plant is provided .
[0012]
The water treatment agent for a steam generating plant according to the present invention is easy to handle because tannin is blended at a high concentration, but precipitates and precipitates (gelated products) are not generated in the chemical tank. It is. Moreover, since the said water treatment agent is the structure with which the tannin is mix | blended with high concentration, it becomes possible to perform the corrosion control of a plant reliably with a small addition amount.
[0013]
In the water treatment agent for steam generating plant according to the present invention, the blending concentration of tannin and tannin extract is more preferably 9% by weight or more, and further preferably 11% by weight or more. The tannin employed in the present invention is hydrolyzable tannin, and examples thereof include pentaploid tannin, gallic tannin, smack tannin, tara tannin, valonia tannin, and chestnut tannin. In consideration of the cost, it is also possible to use a tannin extract having a purity of 90% or less as the tannin content.
[0014]
In this invention, it is comprised so that the potassium hydroxide which is an alkaline agent may contain 0.5 times or more of tannin by weight ratio irrespective of the compounding quantity and kind of tannin. This is because when the weight ratio of potassium hydroxide is less than 0.5 times that of tannin, the tannin is converted into phenolic acid such as gallic acid generated by hydrolysis of tannin in the boiler water and the organic acid generated by the decomposition thereof. This is because complete neutralization cannot be achieved, and as a result, the pH of the boiler water decreases and corrosion proceeds.
[0015]
In the present invention, as necessary, sulfite (salt), bisulfite (salt), metabisulfite (salt), ascorbic acid (salt), erythorbic acid (salt), gallic acid (salt), propyl gallate , Scale inhibitors of oxygen scavengers such as glucose, phosphoric acid (salt), tripolyphosphoric acid (salt), hexametaphosphoric acid (salt), polyacrylic acid (salt), copolymer of acrylic acid and acrylamidomethylpropanesulfonic acid (salt) Agents, dispersants, lignin sulfonic acid (salt), glucoheptonic acid (salt), succinic acid (salt), gluconic acid (salt), citric acid (salt), malic acid (salt), glutamic acid (salt), etc. , 2-amino-2-methyl-1-propanol, morpholine, diethylethanolamine, ammonia, cyclohexylamine, etc., may be used in combination with a feed and water recovery treatment agent. These chemical | medical agents may be previously mix | blended in the water treatment agent which concerns on this invention, and may be separately added to a plant water system.
[0016]
As described above, the present invention provides a water treatment agent for a steam generation plant that has a function of exhibiting a high oxygen removing action and having no function of precipitation and precipitation (gelation product) in a chemical tank. It has special significance.
[0017]
【Example】
Examples 1-6 .
Prepare a chemical solution of tannin and potassium hydroxide (KOH) having the concentrations shown in Table 1 below, put 300 g in a polypropylene container with a capacity of 500 ml, open a 5 mm diameter hole in the lid of the container, And kept stationary. Four samples were prepared for each concentration condition shown in Table 1, and one sample was taken out from each condition group after 1 week, 2 weeks, 3 weeks, and 4 weeks, and the deposition and precipitation of the chemical solution were confirmed. In addition, the tannin employ | adopted in the present Example is a high-purity pentaploid tannin (pharmacopoeia tannin) (indicated by A in Table 1), a pentaploid tannin extract (crude product) (indicated by B in Table 1). , Chestnut tannin extract (crude product) (indicated by C in Table 1).
[0018]
【Example】
result.
In Examples 1 to 6 , it was revealed that the chemicals were very stable without any precipitation or precipitation after any one to four weeks. More specifically, since the stability of the chemical solution was demonstrated in all of Examples 1 to 6 , potassium hydroxide was very suitable as an alkaline agent to be blended with tannin, and 7.0% by weight or more It was also found that, even in a chemical solution containing tannin, precipitation or precipitation can be reliably prevented by adding 0.5 times or more of potassium hydroxide to tannin by weight.
[0019]
Comparative Examples 1-10.
Prepare a chemical solution of tannin and sodium hydroxide (NaOH) or sodium carbonate (Na 2 CO 3 ) having the concentrations shown in Table 1 below, and put 300 g in a polypropylene container with a capacity of 500 ml. A 5 mm hole was opened and stored at 30 ° C. Four samples were prepared for each concentration condition shown in Table 1, and one sample was taken out from each condition group after 1 week, 2 weeks, 3 weeks, and 4 weeks to confirm the deposition and precipitation of the chemical solution. . In addition, the tannin employ | adopted by this comparative example is a high purity pentaploid tannin (Pharmacopoeia tannin) (it shows by A in Table 1), a quintuplet tannin extract (crude product) (it shows by B in Table 1). , Chestnut tannin extract (crude product) (indicated by C in Table 1).
[0020]
result.
In the comparative example, except for Comparative Example 1 having a low tannin concentration of 6.0% by weight, it became clear that precipitation or precipitation occurred in the chemical solution as time passed and the chemical solution became unstable. Thereby, the water treatment agent for steam generating plants according to the present invention has proved that the acid chemical solution is stable even when the tannin concentration is high.
[0021]
[Table 1]
[0022]
In Table 1, Examples 1 to 7 represent Examples 1 to 7, and Ratios 1 to 10 represent Comparative Examples 1 to 10, respectively. ○ in Table 1 indicates that precipitation or precipitation was not observed and it was determined that the chemical solution was stable, and × indicates that precipitation or precipitation was observed and the chemical solution was determined to be unstable.
[0023]
Examples 8 and 9.
Soft water (acid consumption 4.8 10 mg CaCO 3 / L) saturated with oxygen in the air at 25 ° C. was supplied to a test apparatus simulating an actual steam generation plant with a capacity of 5 L. The water treatment agent having the composition shown in Table 2 was added, and operation was performed under the conditions of a pressure of 1 MPa, a steam generation amount of 10 L / hr, and a blow rate of 10% to generate steam. The generated steam was cooled with a heat exchanger to form condensed water, adjusted to 45 ° C., and then passed through a test piece column. Inside this column, test pieces (50 × 30 × 1 mm) made of carbon steel (SS400) are set in advance, the amount of corrosion of these test pieces for 96 hours is measured, and the corrosion rate is calculated. Is the corrosion rate of the steam condensate system. Further, the steam condensed water was cooled to 20 ° C., and dissolved oxygen concentration and dissolved oxygen dioxide concentration were measured in this water.
[0024]
Comparative Examples 11-13.
The water treatment agents of the types and blends shown in Table 2 to be described later were added to the feed water in the same manner as in Examples 8 and 9, and measurement was performed in the same manner as in Examples 8 and 9. The measurement results regarding Examples 8 and 9 and Comparative Examples 11 to 13 are shown in Table 2 below.
[0025]
[Table 2]
[0026]
result.
As shown in Table 2 above, it is clear that Examples 8 and 9 have a slower corrosion rate than Comparative Examples 11 to 13. From this, it was proved that the water treatment agent for steam generating plant according to the present invention sufficiently exerts the corrosion inhibiting action.
[0027]
Specifically, Example 9 in which the type of tannin and the composition of the tannin and the alkali agent are exactly the same, and the alkali agent is potassium hydroxide, and the alkali agent is potassium carbonate (K 2 CO 3 ) In comparison with Comparative Example 12, the corrosion rate of the steam condensate system is significantly different from Example 8 with 8.8 mdd and Comparative Example 12 with 22 mdd, and Example 9 has 40% corrosion compared to Comparative Example 12. It was speed. From this, it became clear that potassium hydroxide is particularly suitable as an alkaline agent for sufficiently exerting the corrosion inhibiting action of tannin.
[0028]
Moreover, according to Table 2, Examples 8 and 9 in which the alkali agent is potassium hydroxide can suppress the carbon dioxide concentration in the steam condensed water to be lower than that in Comparative Example 11 in which the alkali agent is potassium carbonate. Since it is clear that the effect is exhibited, corrosion of the steam condensate piping can be suppressed.
[0029]
Furthermore, referring to Table 2, when Example 8 and Comparative Example 13 are compared, Example 8 having a weight ratio of 50% (6.5 ÷ 13.0) or more with respect to tannin is the same. Better results are obtained in any of the corrosion rate in the boiler, the dissolved oxygen concentration in the steam condensed water, and the corrosion rate in the steam condensate than in Comparative Example 13 in which the weight ratio is 38% (5.0 ÷ 13.0). It was.
[0030]
From this, by adding 0.5 times or more by weight of potassium hydroxide to tannin, potassium hydroxide is converted to phenolic acid such as gallic acid produced by hydrolysis of tannin and organic produced by decomposition of them. It is clear that the acid is completely neutralized to prevent a decrease in the pH of the boiler water and the corrosion is reliably suppressed. That is, it has been proved that the numerical value of 0.5 times the weight ratio has a critical significance.
[0031]
【The invention's effect】
The water treatment agent for a steam generation plant according to the present invention has a high tannin blending concentration, but does not generate precipitates or precipitates in the chemical solution tank. Therefore, it is possible to handle with a single solution, so that it is possible to simplify the configuration of the apparatus and to achieve an advantageous effect that work and management are easy.
[0032]
Further, since the water treatment agent has a high tannin blending concentration, there is an advantageous effect that the corrosion of the plant can be reliably suppressed with a small addition amount.
Claims (1)
少なくとも、タンニンとして加水分解型タンニンを7重量%以上と、アルカリ剤として水酸化カリウムを前記タンニンに対して重量比で0.5倍以上とを含有し、
各成分が予め混合され一液化されていることを特徴とする蒸気発生プラント用水処理剤。 A one-component water treatment agent for removing dissolved oxygen in a steam generation plant water system,
Containing at least 7% by weight of hydrolyzable tannin as tannin and 0.5 times or more by weight of potassium hydroxide as an alkalinity agent,
A water treatment agent for a steam generation plant, wherein each component is premixed and liquefied .
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JP2009285530A (en) * | 2008-05-27 | 2009-12-10 | Kurita Water Ind Ltd | Water treatment agent for boiler device, and water treatment method for boiler device |
CN102084033A (en) * | 2008-08-05 | 2011-06-01 | 栗田工业株式会社 | Boiler water treatment agent and method for the treatment of water |
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JP6256538B2 (en) | 2016-07-06 | 2018-01-10 | 栗田工業株式会社 | Boiler deoxygenating agent and boiler water-based deoxygenating method |
JP2019065357A (en) * | 2017-10-02 | 2019-04-25 | 三浦工業株式会社 | Water treatment agent and corrosion inhibition method of boiler water pipe |
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