JP6885266B2 - Sulfurous acid-based water treatment agent and water treatment method - Google Patents
Sulfurous acid-based water treatment agent and water treatment method Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 178
- 239000003795 chemical substances by application Substances 0.000 title claims description 107
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 title claims description 41
- 238000000034 method Methods 0.000 title claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 37
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 27
- 235000012239 silicon dioxide Nutrition 0.000 claims description 26
- 150000003839 salts Chemical class 0.000 claims description 22
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 20
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 18
- 239000000377 silicon dioxide Substances 0.000 claims description 18
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 18
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 17
- 239000011734 sodium Substances 0.000 claims description 17
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 229910001414 potassium ion Inorganic materials 0.000 claims description 13
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 claims description 11
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims description 11
- 229910001415 sodium ion Inorganic materials 0.000 claims description 11
- 239000000126 substance Substances 0.000 claims description 11
- 239000004111 Potassium silicate Substances 0.000 claims description 9
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 9
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 9
- 235000019353 potassium silicate Nutrition 0.000 claims description 9
- 235000010265 sodium sulphite Nutrition 0.000 claims description 9
- 239000003109 Disodium ethylene diamine tetraacetate Substances 0.000 claims description 2
- ZGTMUACCHSMWAC-UHFFFAOYSA-L EDTA disodium salt (anhydrous) Chemical compound [Na+].[Na+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O ZGTMUACCHSMWAC-UHFFFAOYSA-L 0.000 claims description 2
- 235000019301 disodium ethylene diamine tetraacetate Nutrition 0.000 claims description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical class [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 23
- 238000005260 corrosion Methods 0.000 description 20
- 230000007797 corrosion Effects 0.000 description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 18
- 239000001301 oxygen Substances 0.000 description 18
- 229910052760 oxygen Inorganic materials 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 230000000694 effects Effects 0.000 description 15
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 7
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 6
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- 239000011575 calcium Substances 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 229940123973 Oxygen scavenger Drugs 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 229910021645 metal ion Inorganic materials 0.000 description 4
- 239000003002 pH adjusting agent Substances 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 230000003078 antioxidant effect Effects 0.000 description 3
- 239000002738 chelating agent Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- BDOYKFSQFYNPKF-UHFFFAOYSA-N 2-[2-[bis(carboxymethyl)amino]ethyl-(carboxymethyl)amino]acetic acid;sodium Chemical compound [Na].[Na].OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O BDOYKFSQFYNPKF-UHFFFAOYSA-N 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- PAFZNILMFXTMIY-UHFFFAOYSA-N cyclohexylamine Chemical compound NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 235000013373 food additive Nutrition 0.000 description 2
- 239000002778 food additive Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910001425 magnesium ion Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000008234 soft water Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- ZZZCUOFIHGPKAK-UHFFFAOYSA-N D-erythro-ascorbic acid Natural products OCC1OC(=O)C(O)=C1O ZZZCUOFIHGPKAK-UHFFFAOYSA-N 0.000 description 1
- PQUCIEFHOVEZAU-UHFFFAOYSA-N Diammonium sulfite Chemical compound [NH4+].[NH4+].[O-]S([O-])=O PQUCIEFHOVEZAU-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 229930003268 Vitamin C Natural products 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000004202 aminomethyl group Chemical group [H]N([H])C([H])([H])* 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 235000006708 antioxidants Nutrition 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- ZETCGWYACBNPIH-UHFFFAOYSA-N azane;sulfurous acid Chemical compound N.OS(O)=O ZETCGWYACBNPIH-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- LNUIUONEPHRXHM-UHFFFAOYSA-L disodium acetic acid ethane-1,2-diamine diacetate Chemical compound [Na+].[Na+].CC(O)=O.CC(O)=O.CC([O-])=O.CC([O-])=O.NCCN LNUIUONEPHRXHM-UHFFFAOYSA-L 0.000 description 1
- OPGYRRGJRBEUFK-UHFFFAOYSA-L disodium;diacetate Chemical compound [Na+].[Na+].CC([O-])=O.CC([O-])=O OPGYRRGJRBEUFK-UHFFFAOYSA-L 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 239000000693 micelle Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- DJEHXEMURTVAOE-UHFFFAOYSA-M potassium bisulfite Chemical compound [K+].OS([O-])=O DJEHXEMURTVAOE-UHFFFAOYSA-M 0.000 description 1
- 235000010259 potassium hydrogen sulphite Nutrition 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- BHZRJJOHZFYXTO-UHFFFAOYSA-L potassium sulfite Chemical compound [K+].[K+].[O-]S([O-])=O BHZRJJOHZFYXTO-UHFFFAOYSA-L 0.000 description 1
- 235000019252 potassium sulphite Nutrition 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 239000002455 scale inhibitor Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 229940079827 sodium hydrogen sulfite Drugs 0.000 description 1
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 235000018553 tannin Nutrition 0.000 description 1
- 229920001864 tannin Polymers 0.000 description 1
- 239000001648 tannin Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 235000019154 vitamin C Nutrition 0.000 description 1
- 239000011718 vitamin C Substances 0.000 description 1
Description
本発明は、ボイラの防食剤として用いられる、亜硫酸塩を含む亜硫酸系水処理剤に関する。 The present invention relates to a sulfite-based water treatment agent containing a sulfite, which is used as an anticorrosive agent for boilers.
従来、ボイラ水と接触するボイラ水管等の伝熱面に生じる腐食を抑制するために、ボイラ給水に水処理剤として脱酸素剤を添加する技術が知られている。ボイラの伝熱面の腐食は水中の溶存酸素が主原因となって起こるため、ボイラ給水に脱酸素剤を添加することで水中の溶存酸素量を減少させ、腐食を抑制することができる。このような脱酸素剤としては、例えば、亜硫酸塩等が用いられる。 Conventionally, a technique of adding an oxygen scavenger as a water treatment agent to boiler water supply has been known in order to suppress corrosion occurring on a heat transfer surface such as a boiler water pipe that comes into contact with boiler water. Corrosion of the heat transfer surface of the boiler is mainly caused by dissolved oxygen in the water. Therefore, by adding an oxygen scavenger to the boiler water supply, the amount of dissolved oxygen in the water can be reduced and corrosion can be suppressed. As such an oxygen scavenger, for example, sulfites and the like are used.
亜硫酸塩は優れた脱酸素効果を有するが、自身が酸化されることで腐食性因子である硫酸イオン（ＳＯ４ ２−）を生成し、ボイラの伝熱面の腐食要因となる問題があった。そこで、亜硫酸塩に加えケイ酸やケイ酸塩等を水処理剤に添加することで伝熱面のボイラ水との接触面側に皮膜を形成し、腐食を抑制する技術が知られている（例えば、後述の特許文献１参照）。 Has a deoxidizing effect sulphite excellent, itself generates the Sulfate ion (SO 4 2-) are corrosive factors by being oxidized, there is a problem that the corrosion factor in the heat transfer surface of the boiler .. Therefore, a technique is known in which silicic acid, silicate, etc. are added to a water treatment agent in addition to sulfites to form a film on the heat transfer surface on the contact surface side with boiler water to suppress corrosion ( For example, see Patent Document 1 below).
また、水処理剤中に含まれる亜硫酸塩は、保存中に空気中の酸素と反応して劣化する傾向があり、劣化すると脱酸素効果が低下してしまう。
このような要求に対して、亜硫酸塩の安定剤としてキレート剤等を含む水処理剤が知られている（例えば、後述の特許文献２参照）。
Further, the sulfite contained in the water treatment agent tends to react with oxygen in the air during storage and deteriorate, and when it deteriorates, the deoxidizing effect is lowered.
In response to such a demand, a water treatment agent containing a chelating agent or the like is known as a stabilizer for sulfites (see, for example, Patent Document 2 described later).
しかし、特許文献１に記載された水処理剤の実施例に開示されるように、亜硫酸塩に対してケイ酸塩の配合濃度が比較的低い場合には、ボイラの伝熱面の腐食を十分に抑制できない場合があった。
また、特許文献２に記載された発明に係る水処理剤には、ケイ酸やケイ酸塩等は含まれておらず、安定剤としてのキレート剤に加え、脱酸素効果の向上目的で２価以上の金属イオンが含まれている。この水処理剤に対しケイ酸やケイ酸塩等を添加すると、沈殿や結晶化が生じ、水処理剤の保存安定性に問題があった。
すなわち、従来の亜硫酸塩を含む水処理剤においては、ボイラ水管の好ましい防食性及び亜硫酸イオンの酸化防止と水処理剤の保存安定性を両立できていないのが現状である。
However, as disclosed in the examples of the water treatment agent described in Patent Document 1, when the blending concentration of the silicate with respect to the sulfite is relatively low, the heat transfer surface of the boiler is sufficiently corroded. In some cases, it could not be suppressed.
Further, the water treatment agent according to the invention described in Patent Document 2 does not contain silicic acid, silicate or the like, and is divalent for the purpose of improving the deoxidizing effect in addition to the chelating agent as a stabilizer. The above metal ions are contained. When silicic acid, silicate or the like is added to this water treatment agent, precipitation or crystallization occurs, and there is a problem in the storage stability of the water treatment agent.
That is, the current situation is that the conventional water treatment agent containing sulfite cannot achieve both the preferable corrosion resistance of the boiler water pipe, the antioxidant of sulfite ions, and the storage stability of the water treatment agent.
本発明は、上記に鑑みてなされたものであり、好ましい防食性を付与できると共に亜硫酸イオンの酸化を防止し、かつ優れた保存安定性を有する亜硫酸系水処理剤を提供することを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to provide a sulfite-based water treatment agent which can impart preferable anticorrosion properties, prevent oxidation of sulfite ions, and have excellent storage stability. ..
本発明は、ボイラ給水に添加される亜硫酸系水処理剤であって、亜硫酸塩と、ケイ酸又はケイ酸塩と、エチレンジアミン四酢酸又はその塩と、を含み、亜硫酸塩の濃度は、１０〜２５質量％であり、ケイ酸又はケイ酸塩由来の二酸化ケイ素濃度は、１〜１５質量％であり、エチレンジアミン四酢酸又はその塩の濃度は、０．０１〜５質量％である、亜硫酸系水処理剤に関する。 The present invention is a sulfite-based water treatment agent added to boiler water supply, which contains a sulfite, silicic acid or silicate, ethylenediamine tetraacetic acid or a salt thereof, and the concentration of the sulfite is 10 to 10. Sulfurous acid-based water, which is 25% by mass, the concentration of silicon dioxide derived from silicic acid or silicate is 1 to 15% by mass, and the concentration of ethylenediamine tetraacetic acid or a salt thereof is 0.01 to 5% by mass. Regarding treatment agents.
また、本発明における亜硫酸系水処理剤は、更に、水酸化カリウムを含み、前記亜硫酸塩は、亜硫酸ナトリウムであることが好ましい。 Further, it is preferable that the sulfite-based water treatment agent in the present invention further contains potassium hydroxide, and the sulfite is sodium sulfite.
また、本発明における亜硫酸系水処理剤において、カリウムイオン濃度（［Ｋ＋］）とナトリウムイオン濃度（［Ｎａ＋］）との比（［Ｋ＋］／［Ｎａ＋］）は、２／５〜２／１であることが好ましい。 Further, in the sulfite-based water treatment agent of the present invention, the ratio ([K + ] / [Na + ]) of the potassium ion concentration ([K + ]) to the sodium ion concentration ([Na +]) is 2/5. It is preferably ~ 2/1.
また、前記ケイ酸又はケイ酸塩として、ケイ酸カリウムを含むことが好ましい。 Moreover, it is preferable to contain potassium silicate as the silicic acid or silicate.
また、前記エチレンジアミン四酢酸又はその塩として、エチレンジアミン四酢酸二ナトリウムを含むことが好ましい。 Further, it is preferable that disodium ethylenediaminetetraacetate is contained as the ethylenediaminetetraacetic acid or a salt thereof.
また、本発明は、亜硫酸系水処理剤を、ボイラ給水１００容量部に対し０．００１〜０．１容量部添加する薬注ステップを備える水処理方法に関する。 The present invention also relates to a water treatment method comprising a chemical injection step of adding 0.001 to 0.1 parts by volume of a sulfite-based water treatment agent to 100 parts by volume of boiler water supply.
本発明によれば、好ましい防食性を付与できると共に亜硫酸イオンの酸化を防止し、かつ優れた保存安定性を有する亜硫酸系水処理剤を提供できる。 According to the present invention, it is possible to provide a sulfite-based water treatment agent which can impart preferable anticorrosion properties, prevent oxidation of sulfite ions, and have excellent storage stability.
以下、本発明の実施形態について説明する。なお、本発明は以下の実施形態に限定されるものではない。
本実施形態に係る亜硫酸系水処理剤は、ボイラ水と接触するボイラの伝熱面に生じる腐食やスケールを抑制するために用いられる。
Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.
The sulfite-based water treatment agent according to the present embodiment is used to suppress corrosion and scale generated on the heat transfer surface of the boiler that comes into contact with the boiler water.
本実施形態に係る亜硫酸系水処理剤は、亜硫酸塩と、ケイ酸又はケイ酸塩と、エチレンジアミン四酢酸又はその塩と、を含む。また、溶媒としては水、特に純水が好ましく用いられる。 The sulfite-based water treatment agent according to the present embodiment contains a sulfite, silicic acid or silicate, and ethylenediaminetetraacetic acid or a salt thereof. Further, water, particularly pure water, is preferably used as the solvent.
亜硫酸塩は、分子中に亜硫酸基を有する亜硫酸の塩である。亜硫酸塩は水溶液中で電離して亜硫酸イオンを生じる。亜硫酸イオンは以下の式により溶存酸素と反応し硫酸イオンとなる。すなわち溶存酸素量を低減させる脱酸素効果を有する。
２ＳＯ３ ２−＋Ｏ２→２ＳＯ４ ２−
亜硫酸塩を含む水処理剤は、ボイラ給水に添加されて上記のようにボイラ給水中の溶存酸素と反応するだけでなく、水処理剤の保存中にも空気中の酸素と反応して硫酸イオンとなる可能性がある。硫酸イオンは脱酸素効果を有しないばかりか、ボイラの伝熱面に腐食を発生させる腐食性因子である。そのため、亜硫酸塩を含む水処理剤の保存時においてはこのような亜硫酸イオンの酸化が防止される必要がある。
Sulfites are salts of sulfites that have a sulfite group in the molecule. Sulfites are ionized in aqueous solution to produce sulfite ions. Sulfate ion reacts with dissolved oxygen according to the following formula to become sulfate ion. That is, it has a deoxidizing effect that reduces the amount of dissolved oxygen.
2SO 3 2- + O 2 → 2SO 4 2-
A water treatment agent containing sulfites is added to the boiler water supply and reacts with dissolved oxygen in the boiler feed water as described above, and also reacts with oxygen in the air during storage of the water treatment agent to produce sulfate ions. There is a possibility that Sulfate ion is a corrosive factor that not only has no deoxidizing effect but also causes corrosion on the heat transfer surface of the boiler. Therefore, it is necessary to prevent such oxidation of sulfite ions during storage of a water treatment agent containing a sulfite.
本実施形態で用いられる亜硫酸塩としては、例えば、亜硫酸ナトリウム（Ｎａ２ＳＯ３）、二亜硫酸ナトリウム（Ｎａ２Ｓ２Ｏ５）、亜硫酸水素ナトリウム（ＮａＨＳＯ４）、亜硫酸アンモニウム（（ＮＨ４）２ＳＯ３）、亜硫酸水素アンモニウム（（ＮＨ４）ＨＳＯ３）、亜硫酸カリウム（Ｋ２ＳＯ３）、亜硫酸水素カリウム（ＫＨＳＯ３）等が挙げられるが、中でも亜硫酸ナトリウムを用いることが好ましい。亜硫酸ナトリウムは食品添加物としても使用されているような安全性の高い化合物であるため、亜硫酸ナトリウムを水処理剤に用いることで、取扱時の安全性が確保される。 Examples of the sulfite used in the present embodiment include sodium sulfite (Na 2 SO 3 ), sodium dissulfite (Na 2 S 2 O 5 ), sodium hydrogen sulfite (NaHSO 4 ), and ammonium sulfite ((NH 4 ) 2 ). SO 3 ), ammonium hydrogen sulfite ((NH 4 ) HSO 3 ), potassium sulfite (K 2 SO 3 ), potassium hydrogen sulfite (KHSO 3 ) and the like can be mentioned, but it is preferable to use sodium sulfite. Since sodium sulfite is a highly safe compound that is also used as a food additive, the use of sodium sulfite as a water treatment agent ensures safety during handling.
亜硫酸塩の水処理剤中における濃度は、１０〜２５質量％であり、１５〜２５質量％であることが好ましい。亜硫酸塩の必要量はボイラ給水に対する水処理剤の添加量や、ボイラ給水中の溶存酸素濃度等によっても変化するが、未処理のボイラ給水１００容量部に対し０．００１〜０．１容量部の水処理剤を添加する場合においては、一般に水処理剤中の亜硫酸塩の濃度が１０質量％未満である場合、十分な脱酸素効果が得られない。また、水処理剤中における亜硫酸塩の濃度が２５質量％を超える場合、水処理剤保存中の亜硫酸塩の結晶化が起こりやすくなる。また、腐食性因子である硫酸イオンが多量に生成することから、ボイラ水管の好ましい防食性が得られない。 The concentration of sulfite in the water treatment agent is 10 to 25% by mass, preferably 15 to 25% by mass. The required amount of sulfite varies depending on the amount of water treatment agent added to the boiler water supply, the concentration of dissolved oxygen in the boiler water supply, etc., but 0.001 to 0.1 parts by volume with respect to 100 parts by volume of untreated boiler water supply. When the water treatment agent is added, generally, when the concentration of sulfites in the water treatment agent is less than 10% by mass, a sufficient deoxidizing effect cannot be obtained. Further, when the concentration of sulfites in the water treatment agent exceeds 25% by mass, crystallization of sulfites during storage of the water treatment agent is likely to occur. In addition, since a large amount of sulfate ion, which is a corrosive factor, is generated, preferable corrosion resistance of the boiler water pipe cannot be obtained.
ケイ酸はケイ素・酸素・水素を含む化合物であり、ケイ酸塩はケイ酸とアルカリ金属等の塩である。これらの化合物は二酸化ケイ素（ＳｉＯ２）によって構成され、総称して「シリカ」と呼ばれる。
シリカは、伝熱面のボイラ水との接触面側に吸着されて皮膜を形成し、ボイラ水管の伝熱面をこの皮膜で被覆することでボイラ水管に好ましい防食性を付与する皮膜形成成分として機能する。すなわち、シリカによって形成された皮膜がボイラ水管の伝熱面を被覆することで、ボイラ水中に含まれる溶存酸素や、硫酸イオン、塩化物イオン等の腐食性因子による影響が抑制されるため、ボイラ水管の好ましい防食性が得られる。特に、溶存酸素や塩化物イオンは伝熱面に局部的なアノードを発現させ、これにより腐食が進行する場合があるが、ボイラ水中でアニオンや負電荷のミセルとして存在するシリカはそのようなアノードに吸着しやすく、当該部分で選択的に防食皮膜を形成しやすい。従って他の皮膜形成型防食剤と比較し、シリカは比較的少ない添加量で好ましい防食性をボイラ水管に付与できる。
Silicic acid is a compound containing silicon, oxygen, and hydrogen, and silicate is a salt of silicic acid and an alkali metal. These compounds are composed of silicon dioxide (SiO 2 ) and are collectively called "silica".
Silica is adsorbed on the contact surface side of the heat transfer surface with the boiler water to form a film, and by covering the heat transfer surface of the boiler water tube with this film, as a film forming component that imparts favorable corrosion resistance to the boiler water tube. Function. That is, since the film formed by silica covers the heat transfer surface of the boiler water pipe, the influence of dissolved oxygen contained in the boiler water and corrosive factors such as sulfate ion and chloride ion is suppressed, so that the boiler is suppressed. The preferable anticorrosive property of the water pipe can be obtained. In particular, dissolved oxygen and chloride ions develop local anodes on the heat transfer surface, which can lead to corrosion, but silica, which exists as anions and negatively charged micelles in boiler water, is such an anode. It is easy to be adsorbed on the surface, and it is easy to selectively form an anticorrosive film on the portion. Therefore, as compared with other film-forming anticorrosive agents, silica can impart preferable anticorrosive properties to the boiler water pipe with a relatively small amount of addition.
本実施形態で用いられるケイ酸としては、無水ケイ酸（ＳｉＯ２）、オルトケイ酸（Ｈ４ＳｉＯ４）、メタケイ酸（Ｈ２ＳｉＯ３）、メタ二ケイ酸（Ｈ２Ｓｉ２Ｏ５）等が挙げられ、ケイ酸塩としては、ケイ酸ナトリウム（Ｎａ２Ｏ・ｎＳｉＯ２）、ケイ酸カリウム（Ｋ２Ｏ・ｎＳｉＯ２）等が挙げられるが、中でもケイ酸カリウムを用いることが好ましい。上述のように本実施形態に係る水処理剤において、亜硫酸塩としては亜硫酸ナトリウムを用いることが好ましいため、ケイ酸カリウムを水処理剤に用いることで、ケイ酸カリウムがカリウムイオンの供給源となり後述のカリウムイオン及びナトリウムイオンのイオンバランスを取ることが容易となる。ひいては、亜硫酸塩の結晶化を抑制できるため、優れた保存安定性を有する水処理剤が得られる。 The silicic acid used in the present embodiment, silicic anhydride (SiO 2), orthosilicate (H 4 SiO 4), metasilicate (H 2 SiO 3), meta disilicate (H 2 Si 2 O 5), etc. Examples of the silicate include sodium silicate (Na 2 O · nSiO 2 ), potassium silicate (K 2 O · nSiO 2 ), and the like, and among them, potassium silicate is preferably used. As described above, in the water treatment agent according to the present embodiment, it is preferable to use sodium sulfite as the sulfite. Therefore, by using potassium silicate as the water treatment agent, potassium silicate becomes a source of potassium ions, which will be described later. It becomes easy to balance the potassium ion and sodium ion of the above. As a result, the crystallization of sulfites can be suppressed, so that a water treatment agent having excellent storage stability can be obtained.
ケイ酸又はケイ酸塩由来の二酸化ケイ素の水処理剤中における濃度は、１〜１５質量％であり、５〜１５質量％であることが好ましい。シリカの必要量はボイラ給水に対する水処理剤の添加量や、亜硫酸塩の添加量、ボイラ給水中の腐食性因子によっても変化するが、ボイラ給水１００容量部に対し０．００１〜０．１容量部の水処理剤を添加する場合においては、一般に水処理剤中における二酸化ケイ素濃度が１質量％未満である場合、十分な皮膜形成効果が得られず、ボイラ水管の好ましい防食性が得られない。また、水処理剤中における二酸化ケイ素濃度が１５質量％を超える場合、水処理剤の保存中にシリカが析出する恐れがあり、好ましい水処理剤の保存安定性が得られない。 The concentration of silicic acid or silicate-derived silicon dioxide in the water treatment agent is 1 to 15% by mass, preferably 5 to 15% by mass. The required amount of silica varies depending on the amount of water treatment agent added to the boiler water supply, the amount of sulfite added, and the corrosive factors in the boiler water supply, but 0.001 to 0.1 volume per 100 parts by volume of the boiler water supply. When the water treatment agent is added, generally, when the silicon dioxide concentration in the water treatment agent is less than 1% by mass, a sufficient film-forming effect cannot be obtained, and preferable corrosion resistance of the boiler water pipe cannot be obtained. .. Further, when the silicon dioxide concentration in the water treatment agent exceeds 15% by mass, silica may be precipitated during the storage of the water treatment agent, and preferable storage stability of the water treatment agent cannot be obtained.
エチレンジアミン四酢酸又はその塩は、いわゆるキレート剤であり、ボイラ水中に含まれるカルシウムイオンやマグネシウムイオン等の硬度成分を捕捉してキレート化する。キレート化されたこれらのイオンは、伝熱面のボイラ水との接触面側にスケールとして付着することができなくなる。従って、エチレンジアミン四酢酸又はその塩は、ボイラ水管の伝熱面におけるスケールを抑制するスケール抑制剤として機能する。
なお、エチレンジアミン四酢酸又はその塩は、上記のようにカルシウムイオンやマグネシウムイオンなどの多価金属イオンを捕捉してキレート化するため、水処理剤中に多価金属イオンが含まれる場合、上記スケール抑制剤としての機能が阻害される恐れがある。しかし、本実施形態に係る水処理剤は多価金属イオンを含んでおらず、そのような恐れがない。
Ethylenediaminetetraacetic acid or a salt thereof is a so-called chelating agent, which captures and chelates hardness components such as calcium ions and magnesium ions contained in boiler water. These chelated ions cannot adhere as scale to the contact surface side of the heat transfer surface with the boiler water. Therefore, ethylenediaminetetraacetic acid or a salt thereof functions as a scale inhibitor that suppresses scale on the heat transfer surface of the boiler water pipe.
Ethylenediaminetetraacetic acid or a salt thereof captures and chelate polyvalent metal ions such as calcium ions and magnesium ions as described above. Therefore, when the water treatment agent contains polyvalent metal ions, the scale described above. The function as an inhibitor may be impaired. However, the water treatment agent according to the present embodiment does not contain polyvalent metal ions, and there is no such risk.
更に、エチレンジアミン四酢酸又はその塩は、水処理剤の保存中において亜硫酸イオンの酸化防止効果を有する。すなわち、エチレンジアミン四酢酸又はその塩が水処理剤中に存在することで、亜硫酸イオンが空気中の酸素により酸化されて脱酸素機能を失うことが防止される。 Further, ethylenediaminetetraacetic acid or a salt thereof has an antioxidant effect of sulfite ion during storage of the water treatment agent. That is, the presence of ethylenediaminetetraacetic acid or a salt thereof in the water treatment agent prevents sulfite ions from being oxidized by oxygen in the air and losing the deoxidizing function.
エチレンジアミン四酢酸又はその塩の水処理剤中における濃度は、０．０１〜５．０質量％であり、０．０１〜２．０質量％であることが好ましい。水処理剤におけるエチレンジアミン四酢酸又はその塩の濃度が０．０１質量％未満である場合、十分なスケール抑制効果及び亜硫酸イオンの酸化防止効果が得られない。また、水処理剤におけるエチレンジアミン四酢酸又はその塩の濃度が５．０質量％を超える場合、水処理剤の保存中に析出が起こりやすくなり、水処理剤の好ましい保存安定性が得られない。 The concentration of ethylenediaminetetraacetic acid or a salt thereof in the water treatment agent is 0.01 to 5.0% by mass, preferably 0.01 to 2.0% by mass. When the concentration of ethylenediaminetetraacetic acid or a salt thereof in the water treatment agent is less than 0.01% by mass, a sufficient scale suppressing effect and an antioxidant effect of sulfite ion cannot be obtained. Further, when the concentration of ethylenediaminetetraacetic acid or a salt thereof in the water treatment agent exceeds 5.0% by mass, precipitation is likely to occur during storage of the water treatment agent, and preferable storage stability of the water treatment agent cannot be obtained.
本実施形態で用いられるエチレンジアミン四酢酸の塩としては、エチレンジアミン四酢酸カルシウム二ナトリウムやエチレンジアミン四酢酸二ナトリウム等が挙げられるが、硬度成分を含まず、かつ食品添加物としても用いられているエチレンジアミン四酢酸二ナトリウムを用いることがスケール抑制、取扱時の安全性の観点から好ましい。 Examples of the ethylenediaminetetraacetic acid salt used in the present embodiment include ethylenediaminetetraacetic acid disodium and ethylenediaminetetraacetic acid disodium, but the ethylenediaminetetraacetic acid salt does not contain a hardness component and is also used as a food additive. It is preferable to use disodium acetate from the viewpoint of scale suppression and safety during handling.
本実施形態に係る亜硫酸系水処理剤においては、更にｐＨ調整剤として水酸化カリウムが含まれることが好ましい。
水酸化カリウムは、ボイラ水管の伝熱面が腐食されにくいｐＨとなるようにボイラ給水のｐＨを上昇させるｐＨ調整剤としての機能を有する。すなわち、ｐＨ調整剤によりボイラ給水のｐＨがアルカリ側に調整されることでボイラ水管の腐食が抑制される。このようなｐＨ調整剤としての水酸化カリウムは、強塩基のためｐＨを上昇させる効果が高く、あるいはアルカリ金属の水酸化物としてスケール発生防止の観点から好ましく用いられる。また、上述のように本実施形態に係る水処理剤において、亜硫酸塩としては亜硫酸ナトリウムを用いることが好ましいため、水酸化カリウムを水処理剤に用いることで、水酸化カリウムがカリウムイオンの供給源となり後述のカリウムイオン及びナトリウムイオンのイオンバランスを取ることが容易となる。ひいては、亜硫酸塩の結晶化を抑制できるため、優れた保存安定性を有する水処理剤が得られる。
The sulfite-based water treatment agent according to the present embodiment preferably further contains potassium hydroxide as a pH adjuster.
Potassium hydroxide has a function as a pH adjuster that raises the pH of the boiler feed water so that the heat transfer surface of the boiler water pipe is less likely to be corroded. That is, the pH of the boiler feed water is adjusted to the alkaline side by the pH adjuster, so that corrosion of the boiler water pipe is suppressed. Potassium hydroxide as such a pH adjuster is a strong base and therefore has a high effect of raising the pH, or is preferably used as an alkali metal hydroxide from the viewpoint of preventing scale generation. Further, as described above, in the water treatment agent according to the present embodiment, it is preferable to use sodium sulfite as the sulfite. Therefore, by using potassium hydroxide as the water treatment agent, potassium hydroxide is a source of potassium ions. Therefore, it becomes easy to balance the ions of potassium ion and sodium ion, which will be described later. As a result, the crystallization of sulfites can be suppressed, so that a water treatment agent having excellent storage stability can be obtained.
本実施形態に係る亜硫酸系水処理剤において、カリウムイオン濃度（［Ｋ＋］）とナトリウムイオン濃度（［Ｎａ＋］）との比（［Ｋ＋］／［Ｎａ＋］）は、２／５〜２／１であることが好ましく、２／５〜３／２であることが更に好ましい。
本発明者らは、原理については必ずしも定かではないが、亜硫酸塩とともにケイ酸塩やｐＨ調整剤を配合する場合、ケイ酸カリウムや水酸化カリウムのようなカリウム塩を用いた方がナトリウム塩を用いる場合に比べて、亜硫酸塩の結晶化を抑制でき、良好な保存安定性が得られる事を確認した。すなわち、カリウムイオン濃度とナトリウムイオン濃度との比が上記範囲内にあることで、亜硫酸塩が析出し結晶化することを抑制できる。
In the sulfite-based water treatment agent according to the present embodiment, the ratio ([K + ] / [Na + ]) of the potassium ion concentration ([K + ]) to the sodium ion concentration ([Na +]) is 2/5. It is preferably ~ 2/1, more preferably 2/5 to 3/2.
Although the principle is not always clear, the present inventors use potassium salts such as potassium silicate and potassium hydroxide to use sodium salts when silicates and pH regulators are mixed with sulfites. It was confirmed that the crystallization of sulfite can be suppressed and good storage stability can be obtained as compared with the case of using it. That is, when the ratio of the potassium ion concentration to the sodium ion concentration is within the above range, it is possible to suppress the precipitation and crystallization of sulfites.
本実施形態に係る亜硫酸系水処理剤は上記の効果を阻害しない範囲内で、上述した成分以外の成分を含んでもよい。例えば、亜硫酸塩の脱酸素能力を向上させるために用いられる触媒や、ビタミンＣ及びその塩、タンニン等の他の脱酸素剤、クエン酸やポリアクリル酸塩等の他のスケール分散剤、アミノメチルプロパンール、シクロヘキシルアミン等の中和性アミンが含まれていてもよい。 The sulfite-based water treatment agent according to the present embodiment may contain components other than the above-mentioned components as long as the above-mentioned effects are not impaired. For example, catalysts used to improve the deoxidizing capacity of sulfites, other oxygen scavengers such as vitamin C and its salts, tannins, other scale dispersants such as citric acid and polyacrylic acid salts, aminomethyl. Neutralizing amines such as propanol and cyclohexylamine may be contained.
続いて、本実施形態に係る水処理剤を用いた水処理方法について説明する。
本実施形態に係る水処理方法は、本実施形態に係る水処理剤を、ボイラ給水１００容量部に対し０．００１〜０．１容量部添加する薬注ステップを備える。
Subsequently, a water treatment method using the water treatment agent according to the present embodiment will be described.
The water treatment method according to the present embodiment includes a chemical injection step of adding 0.001 to 0.1 parts by volume of the water treatment agent according to the present embodiment to 100 parts by volume of boiler water supply.
本実施形態に係る薬注ステップにおいては、ボイラ給水中の水処理剤の注入量が上記範囲内となるよう調整され、水処理剤がボイラへ給水を供給する給水路内に薬注される。ボイラ給水中における水処理剤の注入量を上記範囲内とすることで、ボイラ給水中の亜硫酸イオン、シリカ等を好ましい濃度とすることができる。また、水処理剤の注入量をボイラ給水中の溶存酸素濃度に応じて上記範囲内で調整してもよい。ボイラ給水中の溶存酸素濃度は水温による寄与が大きいため、ボイラ給水の水温に応じて注入量を調整してもよい。注入量をボイラ給水中の溶存酸素濃度に応じて調整することで、水処理剤による好ましい防食性が得られると共に、不要な薬注を抑制できるためコストを削減できる。また、不要な薬注による腐食性因子の増大や、シリカのスケーリングを防止することができ、安定した水管理を行うことができる。 In the chemical injection step according to the present embodiment, the injection amount of the water treatment agent in the boiler feed water is adjusted to be within the above range, and the water treatment agent is dispensed into the water supply channel that supplies water to the boiler. By setting the injection amount of the water treatment agent in the boiler feed water within the above range, the sulfite ion, silica and the like in the boiler feed water can be set to a preferable concentration. Further, the injection amount of the water treatment agent may be adjusted within the above range according to the dissolved oxygen concentration in the boiler feed water. Since the dissolved oxygen concentration in the boiler feed water is greatly contributed by the water temperature, the injection amount may be adjusted according to the water temperature of the boiler feed water. By adjusting the injection amount according to the dissolved oxygen concentration in the boiler feed water, favorable corrosion resistance of the water treatment agent can be obtained, and unnecessary chemical injection can be suppressed, so that the cost can be reduced. In addition, it is possible to prevent an increase in corrosive factors due to unnecessary chemical injection and scaling of silica, and stable water management can be performed.
ボイラ給水中の水処理剤の注入量が上記範囲内となる限り、薬注の方法は特に制限されず、ボイラ給水に対して連続的に注入されてもよいし、断続的に注入されてもよい。また、薬注されたボイラ給水がボイラ系内に供給される前に一定時間貯留しておくタンクを設け、そのタンク中のボイラ給水に対する水処理剤の注入量が上記範囲内となるよう、注入量が調整されるようにしてもよい。 As long as the injection amount of the water treatment agent in the boiler water supply is within the above range, the method of chemical injection is not particularly limited, and the water treatment agent may be continuously injected into the boiler water supply or intermittently. Good. In addition, a tank is provided to store the medicated boiler water supply for a certain period of time before it is supplied into the boiler system, and the water treatment agent is injected so that the amount of the water treatment agent injected into the boiler water supply in the tank is within the above range. The amount may be adjusted.
次に、本発明を実施例に基づいて更に詳細に説明するが、本発明はこれに限定されるものではない。 Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
＜実施例１〜１１及び比較例１〜７＞
亜硫酸ナトリウム（和光純薬製、特級試薬）、ケイ酸カリウム（和光純薬製、けい酸カリウム溶液）、エチレンジアミン四酢酸二ナトリウム（和光純薬製、特級試薬）、水酸化カリウム（和光純薬製、特級試薬）及び溶媒としての蒸留水が、それぞれ表１に示す含有量（単位：質量％）となり、かつ水処理剤中のカリウムイオン濃度とナトリウムイオン濃度の比（［Ｋ＋］／［Ｎａ＋］）が表１に示す数値となるように混合することで、各実施例及び比較例の水処理剤を調製した。なお、比較例７は、従来技術である特許文献２に記載の多価金属を含む水処理剤に対応する。
<Examples 1 to 11 and Comparative Examples 1 to 7>
Sodium sulfite (Wako Pure Chemicals, special grade reagent), potassium silicate (Wako Pure Chemicals, potassium silicate solution), ethylenediamine disodium tetraacetate (Wako Pure Chemicals, special grade reagent), potassium hydroxide (Wako Pure Chemicals, special grade reagent) , Special grade reagent) and distilled water as a solvent have the contents (unit: mass%) shown in Table 1, respectively, and the ratio of potassium ion concentration to sodium ion concentration in the water treatment agent ([K + ] / [Na]. The water treatment agents of each Example and Comparative Example were prepared by mixing so that +]) became the numerical value shown in Table 1. In addition, Comparative Example 7 corresponds to the water treatment agent containing a multivalent metal described in Patent Document 2, which is a prior art.
［保存安定性］
実施例及び比較例の水処理剤を−５℃、５℃、２５℃で２７０日間保管した。保管後の水処理剤の外観を目視で観察し、変化の有無を確認した。変化が無い場合は「Ａ」とし、−５℃で結晶や析出物等の沈降が生じている場合を「Ｂ」、−５℃及び５℃で結晶や析出物等の沈降が生じている場合を「Ｃ」、全ての温度帯で結晶や析出物等の沈降が生じている場合は「Ｄ」と評価し、評価Ｃ以上を合格、Ｄを不合格と判定した。結果を表１に示す。
[Storage stability]
The water treatment agents of Examples and Comparative Examples were stored at −5 ° C., 5 ° C. and 25 ° C. for 270 days. The appearance of the water treatment agent after storage was visually observed to confirm the presence or absence of changes. If there is no change, it is set as "A", if the crystals and precipitates are settled at -5 ° C, it is set as "B", and if it is settled at -5 ° C and 5 ° C, the crystals and precipitates are settled. Was evaluated as “C”, and when precipitation of crystals, precipitates, etc. occurred in all temperature zones, it was evaluated as “D”, and evaluation C or higher was evaluated as acceptable, and D was determined as rejected. The results are shown in Table 1.
［亜硫酸イオンの酸化抑制］
実施例及び比較例の水処理剤を２５℃で２７０日間保管した。保管後のＳＯ３ ２−イオンの量をよう素滴定法により測定し、保管前のＳＯ３ ２−イオンの量と比較して、以下の式によってＳＯ３ ２−イオン残留率を求めた。ＳＯ３ ２−イオン残留率が９５％超を「Ａ」、ＳＯ３ ２−イオン残留率が９０％〜９５％を「Ｂ」、ＳＯ３ ２−イオン残留率が９０％未満を「Ｃ」と評価し、評価Ｂ以上を合格、Ｃを不合格と判定した。結果を表１に示す。
ＳＯ３ ２−イオン残留率（％）＝（（保管後ＳＯ３ ２−イオン量）／（保管前ＳＯ３ ２−イオン量））×１００
[Oxidation suppression of sulfite ion]
The water treatment agents of Examples and Comparative Examples were stored at 25 ° C. for 270 days. Measured by titration method intoxicated the amount of SO 3 2-ion after storage, compared to the amount of before storage SO 3 2-ions were determined SO 3 2-ionic residual rate by the following equation. SO 3 2-ion residual ratio is 95 percent "A", the SO 3 2-ionic residue of 90% to 95% "B", SO 3 2-ion residual ratio "C" and less than 90% Evaluation was performed, and evaluation B or higher was judged to be acceptable, and evaluation C was determined to be unacceptable. The results are shown in Table 1.
SO 3 2- Ion Residual Rate (%) = ((SO 3 2- Ion Amount After Storage) / (SO 3 2- Ion Amount Before Storage)) x 100
［脱酸素効果］
実施例及び比較例の水処理剤を、ｐＨ１１に調整した５０℃の蒸留水に対し４００ｍｇ／Ｌ添加し、添加時から３０分経過後の溶存酸素濃度を溶存酸素濃度計で測定した。水処理剤添加前からの溶存酸素の低減量が１．０ｐｐｍ未満を「Ａ」、１．０〜２．０ｐｐｍを「Ｂ」、２．０ｐｐｍ超を「Ｃ」と評価し、評価Ｂ以上を合格、Ｃを不合格と判定した。結果を表１に示す。
[Deoxidizing effect]
The water treatment agents of Examples and Comparative Examples were added at 400 mg / L to distilled water at 50 ° C. adjusted to pH 11, and the dissolved oxygen concentration 30 minutes after the addition was measured with a dissolved oxygen concentration meter. The amount of reduction of dissolved oxygen before the addition of the water treatment agent is evaluated as "A" when it is less than 1.0 ppm, "B" when 1.0 to 2.0 ppm, and "C" when it exceeds 2.0 ppm, and evaluation B or higher is evaluated. Passed and C were judged to be rejected. The results are shown in Table 1.
［防食性］
実施例及び比較例の水処理剤をボイラ給水に薬注した場合における、ボイラ水管の伝熱面の防食性を評価した。ここでは、蒸発量１．３５ｋｇ／時間の実験用貫流ボイラに、水処理剤を４００ｍｇ／Ｌ添加した軟水をボイラ給水用に供給し、圧力０．３ＭＰａの蒸気を連続的に発生させながら、ブロー率１０％で当該ボイラを運転した。運転４８時間経過後の食孔（伝熱管のボイラ水との接触面側に発生する厚さ方向の反対側に向かう孔状の腐食を示す。）の深さの最大値により防食性を評価した。具体的には、食孔深さ最大値が５０μｍ未満を「Ａ」、５０〜１５０μｍを「Ｂ」、１５０μｍ超を「Ｃ」と評価し、評価Ｂ以上を合格、Ｃを不合格と判定した。結果を表１に示す。
[Anti-corrosion]
The corrosion resistance of the heat transfer surface of the boiler water pipe was evaluated when the water treatment agents of Examples and Comparative Examples were injected into the boiler water supply. Here, soft water to which 400 mg / L of a water treatment agent is added is supplied to the experimental once-through boiler with an evaporation amount of 1.35 kg / hour for boiler water supply, and blown while continuously generating steam at a pressure of 0.3 MPa. The boiler was operated at a rate of 10%. Corrosion resistance was evaluated by the maximum depth of the pitting corrosion (which indicates pitting corrosion that occurs on the contact surface side of the heat transfer tube with the boiler water and goes to the opposite side in the thickness direction) after 48 hours of operation. .. Specifically, the maximum pitting depth of less than 50 μm was evaluated as “A”, 50 to 150 μm was evaluated as “B”, and more than 150 μm was evaluated as “C”. .. The results are shown in Table 1.
［防スケール性］
実施例及び比較例の水処理剤をボイラ給水に薬注した場合における、ボイラ水中のカルシウム溶解度を評価した。ここでは、蒸発量２．８ｋｇ／時間の実験用貫流ボイラに、水処理剤を４００ｍｇ／Ｌ添加した軟水をボイラ給水用に供給し、圧力０．５ＭＰａの蒸気を連続的に発生させながら、ブロー率１０％で当該ボイラを運転した。運転４８時間経過後のボイラ水中のカルシウム溶解度の上昇量により防スケール性を評価した。ボイラ水中のカルシウム溶解度の上昇量が高ければ、カルシウムがスケールとして析出しておらず防スケール性が良好であると評価できる。具体的には、カルシウム溶解度上昇量が１０ｍｇ／Ｌ超えを「Ａ」、５〜１０ｍｇ／Ｌを「Ｂ」、５ｍｇ／Ｌ未満を「Ｃ」と評価し、評価Ｂ以上を合格、Ｃを不合格と判定した。結果を表１に示す。
[Scalability]
The calcium solubility in the boiler water was evaluated when the water treatment agents of Examples and Comparative Examples were injected into the boiler water supply. Here, soft water to which 400 mg / L of a water treatment agent is added is supplied to the experimental once-through boiler with an evaporation amount of 2.8 kg / hour for boiler water supply, and blown while continuously generating steam at a pressure of 0.5 MPa. The boiler was operated at a rate of 10%. Scalability was evaluated by the amount of increase in calcium solubility in the boiler water after 48 hours of operation. If the amount of increase in calcium solubility in the boiler water is high, it can be evaluated that calcium is not precipitated as scale and the scale-proof property is good. Specifically, if the amount of increase in calcium solubility exceeds 10 mg / L, it is evaluated as "A", if 5 to 10 mg / L is evaluated as "B", if it is less than 5 mg / L, it is evaluated as "C". It was judged as passing. The results are shown in Table 1.
実施例２と、比較例１との比較から、亜硫酸塩の量が１０質量％未満である水処理剤は好ましい脱酸素効果が得られないことが確認された。また、実施例３と、比較例２との比較から、亜硫酸塩の量が２５質量％を超える場合、水処理剤の保存安定性が悪化し、更に防食性も悪化することが確認された。
これらの結果から、水処理剤における亜硫酸塩の濃度を１０〜２５質量％とすることで、好ましい脱酸素効果と水処理剤の保存安定性及び防食性を両立できることが確認された。
From the comparison between Example 2 and Comparative Example 1, it was confirmed that the water treatment agent having a sulfite content of less than 10% by mass did not obtain a preferable deoxidizing effect. Further, from the comparison between Example 3 and Comparative Example 2, it was confirmed that when the amount of sulfites exceeds 25% by mass, the storage stability of the water treatment agent deteriorates and the anticorrosion property also deteriorates.
From these results, it was confirmed that by setting the concentration of sulfite in the water treatment agent to 10 to 25% by mass, it is possible to achieve both a preferable deoxidizing effect and storage stability and corrosion resistance of the water treatment agent.
実施例４と、比較例３との比較から、ケイ酸又はケイ酸塩由来の二酸化ケイ素濃度が１質量％未満である水処理剤は好ましい防食性が得られないことが確認された。また、実施例５と、比較例４との比較から、ケイ酸又はケイ酸塩由来の二酸化ケイ素濃度が１５質量％を超える場合、水処理剤の保存安定性が悪化することが確認された。
これらの結果から、水処理剤におけるケイ酸又はケイ酸塩由来の二酸化ケイ素濃度を１〜１５質量％とすることで、好ましい防食性と水処理剤の保存安定性を両立できることが確認された。
From the comparison between Example 4 and Comparative Example 3, it was confirmed that the water treatment agent having a silicic acid or silicate-derived silicon dioxide concentration of less than 1% by mass did not obtain preferable anticorrosion properties. Further, from the comparison between Example 5 and Comparative Example 4, it was confirmed that when the concentration of silicon dioxide derived from silicic acid or silicate exceeds 15% by mass, the storage stability of the water treatment agent deteriorates.
From these results, it was confirmed that by setting the concentration of silicon dioxide derived from silicic acid or silicate in the water treatment agent to 1 to 15% by mass, both preferable anticorrosion property and storage stability of the water treatment agent can be achieved.
実施例６と、比較例５との比較から、エチレンジアミン四酢酸又はその塩の濃度が０．０１質量％未満である水処理剤は好ましい亜硫酸イオンの酸化抑制効果及びスケール抑制効果が得られないことが確認された。また、実施例７と、比較例６との比較から、エチレンジアミン四酢酸又はその塩の濃度が５質量％を超える水処理剤は好ましい保存安定性が得られないことが確認された。
これらの結果から、水処理剤におけるエチレンジアミン四酢酸又はその塩の濃度を０．０１〜５質量％とすることで、好ましい亜硫酸イオンの酸化抑制効果及びスケール抑制効果と保存安定性を両立できることが確認された。
From the comparison between Example 6 and Comparative Example 5, the water treatment agent having a concentration of ethylenediaminetetraacetic acid or a salt thereof of less than 0.01% by mass does not have a preferable effect of suppressing the oxidation of sulfite ion and the effect of suppressing the scale. Was confirmed. Further, from the comparison between Example 7 and Comparative Example 6, it was confirmed that a water treatment agent having a concentration of ethylenediaminetetraacetic acid or a salt thereof exceeding 5% by mass could not obtain preferable storage stability.
From these results, it was confirmed that by setting the concentration of ethylenediaminetetraacetic acid or a salt thereof in the water treatment agent to 0.01 to 5% by mass, it is possible to achieve both a preferable oxidation inhibitory effect and scale inhibitory effect of sulfite ion and storage stability. Was done.
実施例８と、実施例９との比較から、水処理剤中のカリウムイオン濃度（［Ｋ＋］）とナトリウムイオン濃度（［Ｎａ＋］）との比（［Ｋ＋］／［Ｎａ＋］）が２／５以上である場合、より好ましい水処理剤の保存安定性が得られることが確認された。また、実施例１０と、実施例１１との比較から、水処理剤中のカリウムイオン濃度（［Ｋ＋］）とナトリウムイオン濃度（［Ｎａ＋］）との比（［Ｋ＋］／［Ｎａ＋］）が２／１以下である場合、より好ましい水処理剤の保存安定性が得られることが確認された。更に、実施例８〜１１と、比較例７との比較から、水処理剤中にカリウムイオンを有さずナトリウムイオンのみが存在し、また多価金属を含む水処理剤は、好ましい水処理剤の保存安定性が得られないことが確認された。
これらの結果から、水処理剤中のカリウムイオン濃度（［Ｋ＋］）とナトリウムイオン濃度（［Ｎａ＋］）との比（［Ｋ＋］／［Ｎａ＋］）が２／５〜２／１であることで、水処理剤の好ましい保存安定性が得られることが確認された。
From the comparison between Example 8 and Example 9, the ratio of the potassium ion concentration ([K + ]) to the sodium ion concentration ([Na + ]) in the water treatment agent ([K + ] / [Na + ]] ) Is 2/5 or more, it was confirmed that more preferable storage stability of the water treatment agent can be obtained. Further, from the comparison between Example 10 and Example 11, the ratio of the potassium ion concentration ([K + ]) to the sodium ion concentration ([Na + ]) in the water treatment agent ([K + ] / [Na]). It was confirmed that when + ]) was 2/1 or less, more preferable storage stability of the water treatment agent could be obtained. Further, from the comparison between Examples 8 to 11 and Comparative Example 7, the water treatment agent having no potassium ion and only sodium ion present in the water treatment agent and containing a polyvalent metal is a preferable water treatment agent. It was confirmed that the storage stability of was not obtained.
From these results, the ratio ([K + ] / [Na + ]) of the potassium ion concentration ([K + ]) to the sodium ion concentration ([Na + ]) in the water treatment agent was 2/5 to 2 /. When it was 1, it was confirmed that preferable storage stability of the water treatment agent could be obtained.
Claims (5)
亜硫酸塩である亜硫酸ナトリウムと、ケイ酸又はケイ酸塩と、エチレンジアミン四酢酸又はその塩と、水酸化カリウムと、を含み、
前記亜硫酸塩の濃度は、１０〜２５質量％であり、
前記ケイ酸又はケイ酸塩由来の二酸化ケイ素濃度は、１〜１５質量％であり、
前記エチレンジアミン四酢酸又はその塩の濃度は、０．０１〜５質量％である、亜硫酸系水処理剤。 Sulfurous acid-based water treatment agent added to boiler water supply
It contains sodium sulfite, which is a sulfite , silicic acid or silicate, ethylenediamine tetraacetic acid or a salt thereof, and potassium hydroxide .
The concentration of the sulfite is 10 to 25 wt%,
The concentration of silicon dioxide derived from silicic acid or silicate is 1 to 15% by mass.
A sulfite-based water treatment agent having a concentration of ethylenediaminetetraacetic acid or a salt thereof of 0.01 to 5% by mass.
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