JP4968881B2 - Boiler corrosion inhibitor and corrosion inhibition method - Google Patents
Boiler corrosion inhibitor and corrosion inhibition method Download PDFInfo
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- JP4968881B2 JP4968881B2 JP2006065826A JP2006065826A JP4968881B2 JP 4968881 B2 JP4968881 B2 JP 4968881B2 JP 2006065826 A JP2006065826 A JP 2006065826A JP 2006065826 A JP2006065826 A JP 2006065826A JP 4968881 B2 JP4968881 B2 JP 4968881B2
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- 238000005260 corrosion Methods 0.000 title claims description 80
- 230000007797 corrosion Effects 0.000 title claims description 80
- 239000003112 inhibitor Substances 0.000 title claims description 30
- 238000000034 method Methods 0.000 title claims description 25
- 230000005764 inhibitory process Effects 0.000 title claims description 9
- 229920002125 Sokalan® Polymers 0.000 claims description 46
- 239000004584 polyacrylic acid Substances 0.000 claims description 46
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 24
- 150000002443 hydroxylamines Chemical class 0.000 claims description 21
- 230000002401 inhibitory effect Effects 0.000 claims description 14
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 9
- 125000000217 alkyl group Chemical group 0.000 claims description 8
- 125000004432 carbon atom Chemical group C* 0.000 claims description 5
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 5
- 239000004480 active ingredient Substances 0.000 claims description 3
- 238000005536 corrosion prevention Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 75
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 18
- 239000012986 chain transfer agent Substances 0.000 description 16
- -1 iron ions Chemical class 0.000 description 15
- 238000012360 testing method Methods 0.000 description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 12
- 229910052760 oxygen Inorganic materials 0.000 description 12
- 239000001301 oxygen Substances 0.000 description 12
- 229910052742 iron Inorganic materials 0.000 description 10
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 9
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000000178 monomer Substances 0.000 description 9
- 238000006116 polymerization reaction Methods 0.000 description 8
- 229920001174 Diethylhydroxylamine Polymers 0.000 description 7
- FVCOIAYSJZGECG-UHFFFAOYSA-N diethylhydroxylamine Chemical compound CCN(O)CC FVCOIAYSJZGECG-UHFFFAOYSA-N 0.000 description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 5
- 229920001577 copolymer Polymers 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 238000005342 ion exchange Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 3
- DKIDEFUBRARXTE-UHFFFAOYSA-N 3-mercaptopropanoic acid Chemical compound OC(=O)CCS DKIDEFUBRARXTE-UHFFFAOYSA-N 0.000 description 2
- ATVJXMYDOSMEPO-UHFFFAOYSA-N 3-prop-2-enoxyprop-1-ene Chemical compound C=CCOCC=C ATVJXMYDOSMEPO-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 229940123973 Oxygen scavenger Drugs 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 2
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000005227 gel permeation chromatography Methods 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011976 maleic acid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000000 metal hydroxide Inorganic materials 0.000 description 2
- 150000004692 metal hydroxides Chemical class 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- ODHYIQOBTIWVRZ-UHFFFAOYSA-N n-propan-2-ylhydroxylamine Chemical compound CC(C)NO ODHYIQOBTIWVRZ-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000010526 radical polymerization reaction Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000008400 supply water Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 239000012085 test solution Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- MUZDXNQOSGWMJJ-UHFFFAOYSA-N 2-methylprop-2-enoic acid;prop-2-enoic acid Chemical compound OC(=O)C=C.CC(=C)C(O)=O MUZDXNQOSGWMJJ-UHFFFAOYSA-N 0.000 description 1
- AGBXYHCHUYARJY-UHFFFAOYSA-N 2-phenylethenesulfonic acid Chemical compound OS(=O)(=O)C=CC1=CC=CC=C1 AGBXYHCHUYARJY-UHFFFAOYSA-N 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- CIWBSHSKHKDKBQ-DUZGATOHSA-N D-araboascorbic acid Natural products OC[C@@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-DUZGATOHSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910001423 beryllium ion Inorganic materials 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- XEVRDFDBXJMZFG-UHFFFAOYSA-N carbonyl dihydrazine Chemical compound NNC(=O)NN XEVRDFDBXJMZFG-UHFFFAOYSA-N 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003635 deoxygenating effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000004318 erythorbic acid Substances 0.000 description 1
- 235000010350 erythorbic acid Nutrition 0.000 description 1
- DNJIEGIFACGWOD-UHFFFAOYSA-N ethyl mercaptane Natural products CCS DNJIEGIFACGWOD-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 239000003864 humus Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 150000002483 hydrogen compounds Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical class [H]O* 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229940026239 isoascorbic acid Drugs 0.000 description 1
- 229940035429 isobutyl alcohol Drugs 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229920003145 methacrylic acid copolymer Polymers 0.000 description 1
- 229940117841 methacrylic acid copolymer Drugs 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 150000002763 monocarboxylic acids Chemical class 0.000 description 1
- OQAIUHLITJGRMM-UHFFFAOYSA-N n,n-di(propan-2-yl)hydroxylamine Chemical compound CC(C)N(O)C(C)C OQAIUHLITJGRMM-UHFFFAOYSA-N 0.000 description 1
- VMESOKCXSYNAKD-UHFFFAOYSA-N n,n-dimethylhydroxylamine Chemical compound CN(C)O VMESOKCXSYNAKD-UHFFFAOYSA-N 0.000 description 1
- RRUADNNEIGVWSQ-UHFFFAOYSA-N n-ethyl-n-methylhydroxylamine Chemical compound CCN(C)O RRUADNNEIGVWSQ-UHFFFAOYSA-N 0.000 description 1
- VDUIPQNXOQMTBF-UHFFFAOYSA-N n-ethylhydroxylamine Chemical compound CCNO VDUIPQNXOQMTBF-UHFFFAOYSA-N 0.000 description 1
- CPQCSJYYDADLCZ-UHFFFAOYSA-N n-methylhydroxylamine Chemical compound CNO CPQCSJYYDADLCZ-UHFFFAOYSA-N 0.000 description 1
- XWESXZZECGOXDQ-UHFFFAOYSA-N n-tert-butylhydroxylamine Chemical compound CC(C)(C)NO XWESXZZECGOXDQ-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 150000003009 phosphonic acids Chemical class 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229910000160 potassium phosphate Inorganic materials 0.000 description 1
- 235000011009 potassium phosphates Nutrition 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- RZKYDQNMAUSEDZ-UHFFFAOYSA-N prop-2-enylphosphonic acid Chemical compound OP(O)(=O)CC=C RZKYDQNMAUSEDZ-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 235000019832 sodium triphosphate Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- PXQLVRUNWNTZOS-UHFFFAOYSA-N sulfanyl Chemical class [SH] PXQLVRUNWNTZOS-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 125000004964 sulfoalkyl group Chemical group 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 125000003396 thiol group Chemical group [H]S* 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 229940001496 tribasic sodium phosphate Drugs 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- ZTWTYVWXUKTLCP-UHFFFAOYSA-N vinylphosphonic acid Chemical compound OP(O)(=O)C=C ZTWTYVWXUKTLCP-UHFFFAOYSA-N 0.000 description 1
- NLVXSWCKKBEXTG-UHFFFAOYSA-N vinylsulfonic acid Chemical class OS(=O)(=O)C=C NLVXSWCKKBEXTG-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- DGVVWUTYPXICAM-UHFFFAOYSA-N β‐Mercaptoethanol Chemical compound OCCS DGVVWUTYPXICAM-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
本発明は有害なヒドラジンを用いない環境調和型のボイラの腐食抑制剤及び腐食抑制方法に関する。 The present invention relates to a corrosion inhibitor and a corrosion inhibition method for an environmentally friendly boiler that does not use harmful hydrazine.
ボイラの給水には酸素やニ酸化炭素等の気体が溶解しているが、これらはボイラの腐食を促進する作用を示す。例えば水に溶解している酸素は鉄表面で鉄から電子を引き抜いて水酸化物イオンを生成することにより、鉄が鉄イオンとして溶解する反応を促進する。また、ニ酸化炭素は水に溶解して炭酸となり、水素イオンを放出して水のｐＨを低下させる。水素イオンは鉄表面で鉄から電子を引き抜いて水素を生成することにより、鉄が鉄イオンとして溶解する反応を促進する。特に、ボイラ水のような高温下では水の解離定数が大きくなり、２５℃における純水のｐＨは7であるが、１００℃ではｐＨ６.１５、２５０℃ではｐＨ５.６まで低下するため、水素イオン濃度が増加して腐食が促進される。また、ボイラ給水中に塩化物イオンや硫酸イオン等の腐食性イオンが含まれていると、上記の腐食反応を促進する作用を示す。更には腐食により生成した金属の水酸化物や酸化物はボイラの伝熱表面に沈着し易く、これらの沈着物の下の隙間部と健全部の間で酸素濃淡電池を形成したり、隙間内部に塩化物イオン等の腐食性イオンが濃縮されて腐食が進行し易くなる。 Gases such as oxygen and carbon dioxide are dissolved in the boiler feed water, and these show the action of promoting the corrosion of the boiler. For example, oxygen dissolved in water promotes a reaction in which iron dissolves as iron ions by extracting hydroxide from iron on the iron surface to generate hydroxide ions. Carbon dioxide is dissolved in water to become carbonic acid, releasing hydrogen ions to lower the pH of the water. Hydrogen ions pull out electrons from iron on the iron surface to generate hydrogen, thereby promoting a reaction in which iron dissolves as iron ions. In particular, the dissociation constant of water increases at a high temperature such as boiler water, and the pH of pure water at 25 ° C. is 7. However, it decreases to pH 6.15 at 100 ° C. and pH 5.6 at 250 ° C. The ion concentration increases and corrosion is promoted. Moreover, when corrosive ions, such as a chloride ion and a sulfate ion, are contained in boiler feed water, the effect | action which accelerates | stimulates said corrosion reaction is shown. Furthermore, metal hydroxides and oxides generated by corrosion are likely to deposit on the heat transfer surface of the boiler, forming an oxygen concentration cell between the gap and the healthy part under these deposits, Corrosion ions such as chloride ions are concentrated to cause corrosion to proceed easily.
上記の要因によりボイラにおける水と接触する金属は腐食が発生し易いため、腐食抑制のために水中の溶存酸素の除去やｐＨ上昇により水素イオン濃度を低下させる方法が実施されてきた。具体的には従来から溶存酸素の除去のためにヒドラジンや亜硫酸塩等の脱酸素剤が使用されてきたが、ヒドラジンはＩＡＲＣ（国際癌研究機関）における評価においてクラス２Ｂの人に対して発癌性を示す可能性がかなり高い物質とされている。亜硫酸塩は、ヒドラジンほど毒性は高くないが、酸素と反応すると腐食性の高い硫酸イオンとなるため、亜硫酸イオンの残留濃度を十分に維持しないと、かえって腐食を促進する問題点があった。 Because of the above factors, the metal in contact with water in the boiler is likely to corrode, and therefore, a method of reducing the hydrogen ion concentration by removing dissolved oxygen in the water or increasing the pH has been implemented to suppress corrosion. Specifically, deoxygenating agents such as hydrazine and sulfite have been conventionally used to remove dissolved oxygen, but hydrazine is carcinogenic to class 2B people in evaluation at IARC (International Cancer Institute). It is considered to be a substance with a high possibility of showing. Although sulfite is not as toxic as hydrazine, it reacts with oxygen to form highly corrosive sulfate ions. Therefore, unless the residual concentration of sulfite ions is sufficiently maintained, there is a problem of promoting corrosion.
そこで、ヒドラジンや亜硫酸塩に替わる脱酸素剤として、エリソルビン酸（例えば特許文献１参照）、ヒドロキシルアミン化合物（例えば特許文献２参照）、オキシム化合物（例えば特許文献３参照）、カルボヒドラジド（例えば特許文献４参照）等が開示されているが、未だ十分な腐食抑制効果を示すものは得られていない。 Therefore, as an oxygen scavenger in place of hydrazine or sulfite, erythorbic acid (see, for example, Patent Document 1), hydroxylamine compound (see, for example, Patent Document 2), oxime compound (see, for example, Patent Document 3), carbohydrazide (for example, Patent Document) 4), etc. are disclosed, however, no sufficient corrosion inhibiting effect has been obtained yet.
本発明は、ボイラ本体だけでなく脱気器、給水配管、給水ポンプ、給水プレヒーター、エコノマイザー等のボイラの給水系統も含むボイラシステムにおいて、有害なヒドラジンを用いることなく、環境調和型のボイラの腐食抑制剤及び腐食抑制方法を提供することである。 The present invention is an environmentally friendly boiler without using harmful hydrazine in a boiler system including not only a boiler body but also a boiler water supply system such as a deaerator, a water supply pipe, a water supply pump, a water supply preheater, and an economizer. The present invention provides a corrosion inhibitor and a method for inhibiting corrosion.
本発明者は、有害なヒドラジンを用いることなく、ボイラにおける水と接触する金属の腐食を抑制する腐食抑制剤について鋭意検討した結果、ボイラ水系において特定の末端修飾ポリアクリル酸とＮ−アルキル置換ヒドロキシルアミンを併用することにより優れた腐食防止効果が得られることを見出し、本発明に到達した。 As a result of intensive investigations on a corrosion inhibitor that suppresses corrosion of metals that come into contact with water in a boiler without using harmful hydrazine, the present inventor has found that specific end-modified polyacrylic acid and N-alkyl-substituted hydroxyl in a boiler water system. The present inventors have found that an excellent corrosion prevention effect can be obtained by using an amine in combination, and have reached the present invention.
すなわち、請求項１に係る発明は、（Ａ）重量平均分子量が１，０００〜３，０００の、末端イソプロピルアルコール修飾ポリアクリル酸、及び／又は末端チオエーテル修飾ポリアクリル酸と、（Ｂ）一般式（１）（式中、Ｒ１，Ｒ２はそれぞれ独立に水素原子、炭素数１から３のアルキル基である。）で表されるＮ−アルキル置換ヒドロキシルアミンを有効成分として含有することを特徴とするボイラの腐食抑制剤である。
That is, the invention according to claim 1 includes (A) a terminal isopropyl alcohol-modified polyacrylic acid and / or a terminal thioether-modified polyacrylic acid having a weight average molecular weight of 1,000 to 3,000 , and (B) a general formula. (1) (wherein R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), containing N-alkyl-substituted hydroxylamine as an active ingredient It is a corrosion inhibitor for boilers.
請求項２に係る発明は、請求項１記載のボイラの腐食抑制剤であり、（Ａ）成分と（Ｂ）成分を重量比１０：９０〜９０：１０で含むことを特徴とする。
The invention according to claim 2 is a corrosion inhibitor according to claim 1 Symbol placement of the boiler, (A) component and (B) weight ratio of components 10: characterized in that it contains 10: 90-90.
請求項３に係る発明は、ヒドラジンを用いないボイラシステムの腐食防止方法であって、（Ａ）重量平均分子量が１，０００〜３，０００の、末端イソプロピルアルコール修飾ポリアクリル酸、及び／又は末端チオエーテル修飾ポリアクリル酸と、（Ｂ）一般式（１）（式中、Ｒ１，Ｒ２はそれぞれ独立に水素原子、炭素数１から３のアルキル基である。）で表されるＮ−アルキル置換ヒドロキシルアミンを組み合わせて添加することを特徴とするボイラの腐食抑制方法である。
請求項４に係る発明は、請求項３記載のボイラの腐食抑制方法であり、（Ａ）成分と（Ｂ）成分を重量比１０：９０〜９０：１０で添加することを特徴とする。
The invention according to claim 4 is the method for inhibiting corrosion of a boiler according to claim 3 , wherein the component (A) and the component (B) are added at a weight ratio of 10:90 to 90:10.
本発明のボイラの腐食抑制剤あるいはボイラの腐食抑制方法の使用により、溶存酸素に起因する腐食を抑制できるだけでなく、腐食により生成した金属の水酸化物や酸化物の沈着を抑制することにより、沈着物の下の隙間部で発生する腐食を抑制することができるため、ボイラの腐食による事故やボイラの補修・更新等による経済的損失を未然に防止できる。またヒドラジン等の有害な化合物を使用していないため、環境への影響が小さい。 By using the corrosion inhibitor for boilers or the method for inhibiting corrosion of boilers according to the present invention, not only can corrosion caused by dissolved oxygen be suppressed, but also by suppressing the deposition of metal hydroxides and oxides generated by corrosion, Since corrosion occurring in the gaps under the deposits can be suppressed, accidents due to boiler corrosion and economic loss due to boiler repair and renewal can be prevented. In addition, since no harmful compounds such as hydrazine are used, the impact on the environment is small.
本発明におけるボイラシステムは、ボイラ本体だけでなく脱気器、給水配管、給水ポンプ、給水予熱器、エコノマイザー等のボイラの給水系統ならびに過熱器、タービン、蒸気配管、復水器、復水配管等の蒸気・復水系統も包含し、ボイラシステム水系は補給水、給水、復水、ボイラ循環水、蒸気に関わるボイラの給水系統から蒸気・復水系統を含むボイラシステム全般を流れる水系であり、脱酸素剤としてヒドラジンを用いていない水系である。 The boiler system according to the present invention includes not only a boiler body but also a boiler water supply system such as a deaerator, a water supply pipe, a water supply pump, a water supply preheater, an economizer, and a superheater, a turbine, a steam pipe, a condenser, and a condenser pipe. The boiler system water system is a water system that flows through the boiler system including the steam / condensation system from the supply water system of the boiler related to makeup water, feed water, condensate, boiler circulating water, and steam. It is an aqueous system that does not use hydrazine as an oxygen scavenger.
本発明のボイラの腐食抑制剤及び腐食抑制方法の対象となるボイラの種類は、立てボイラ、炉筒ボイラ、煙筒ボイラ、炉筒煙筒ボイラ等の丸ボイラ、水管ボイラ、特殊循環ボイラ、各種廃熱ボイラ等であるが、蒸気圧が７.５ＭＰａを超える貫流ボイラでは固形分を含むため適用できない。また、本発明のボイラの腐食抑制剤及び腐食抑制方法を適用するボイラの蒸気圧は１２ＭＰａ以下であることが好ましい。蒸気圧が１２ＭＰａを超えるボイラでは、本発明のボイラの腐食抑制剤及び腐食抑制方法で用いる末端修飾ポリアクリル酸が熱分解するため十分な腐食抑制効果が期待できない。 The types of boilers that are subject to the corrosion inhibitor and the corrosion suppression method of the boiler of the present invention are round boilers such as vertical boilers, furnace tube boilers, smoke tube boilers, furnace tube smoke tube boilers, water tube boilers, special circulation boilers, various waste heats Although it is a boiler or the like, it cannot be applied to a once-through boiler having a vapor pressure exceeding 7.5 MPa because it contains a solid content. Moreover, it is preferable that the steam pressure of the boiler which applies the corrosion inhibitor and the corrosion suppression method of the boiler of the present invention is 12 MPa or less. In a boiler having a vapor pressure exceeding 12 MPa, the end-modified polyacrylic acid used in the boiler corrosion inhibitor and the corrosion inhibition method of the present invention is thermally decomposed, so that a sufficient corrosion inhibition effect cannot be expected.
本発明のボイラの腐食抑制剤及び腐食抑制方法を適用するボイラの補給水は、イオン交換水、軟化水、工業用水、水道水、地下水等が使用できるが、好ましくはイオン交換水と軟化水である。また蒸気圧が３ＭＰａを超えるボイラでは補給水としてイオン交換水を使用するのが好ましい。また、ボイラのブロー率は特に制限はないが、通常は給水量に対して１〜２０％のブローダウンを連続的あるいは断続的に実施する。 The boiler replenishing water to which the boiler corrosion inhibitor and the corrosion inhibiting method of the present invention are applied can be ion exchange water, softened water, industrial water, tap water, ground water, etc., preferably ion exchange water and softened water. is there. In a boiler having a vapor pressure exceeding 3 MPa, it is preferable to use ion exchange water as makeup water. Moreover, although the blow rate of a boiler does not have a restriction | limiting in particular, Usually, 1 to 20% of blowdown is implemented continuously or intermittently with respect to a water supply amount.
本発明で用いる末端イソプロピルアルコール修飾ポリアクリル酸、及び末端チオエーテル修飾ポリアクリル酸（以下、「末端修飾ポリアクリル酸」とする）は、重量平均分子量が１，０００〜３，０００の末端修飾ポリアクリル酸である。重量平均分子量の測定は、特に限定されるものではなく、一般的なゲル・パーミエーション・クロマトグラフィーの手法により分子量既知のポリエチレングリコールを標準物質として測定され、市販の分子量計算用コンピュータソフトウェア、例えば日立製作所（株）製「Ｄ−２５２０型ＧＰＣデータ処理システム」（商品名）を用いて重量平均分子量が計算される。重量平均分子量が１，０００未満では、本発明の腐食抑制効果が低下し、重量平均分子量が３，０００を超えると腐食抑制効果が低下するだけでなく、Ｎ−アルキル置換ヒドロキシルアミンとの相溶性が低下するため、好ましくない。
The terminal isopropyl alcohol-modified polyacrylic acid and terminal thioether-modified polyacrylic acid (hereinafter referred to as “terminal-modified polyacrylic acid”) used in the present invention are terminal-modified polyacrylic having a weight average molecular weight of 1,000 to 3,000. It is an acid. The measurement of the weight average molecular weight is not particularly limited. The weight average molecular weight is measured by a general gel permeation chromatography method using polyethylene glycol having a known molecular weight as a standard substance, and commercially available computer software for molecular weight calculation such as Hitachi The weight average molecular weight is calculated using “D-2520 type GPC data processing system” (trade name) manufactured by Seisakusho Co., Ltd. When the weight average molecular weight is less than 1,000, the corrosion-inhibiting effect of the present invention is reduced. When the weight average molecular weight exceeds 3,000, not only the corrosion-inhibiting effect is reduced, but also the compatibility with N-alkyl-substituted hydroxylamine. Is unfavorable because of lowering.
前記の末端修飾ポリアクリル酸はラジカル重合法により製造できるが、該分子量範囲に調整するための分子量調整手段としてラジカル開始剤の増量のみでは不十分であり、重合時において十分な量の連鎖移動剤を添加する必要がある。必要な連鎖移動剤の量は重合条件や連鎖移動剤の種類によって異なるが、通常はアクリル酸モノマーに対して５〜１００モル％、好ましくは１０〜５０モル％の範囲である。連鎖移動剤としては、イソプロピルアルコ−ル、イソブチルアルコール等のアルコール、メルカプト酢酸、メルカプトプロピオン酸、メルカプトエタノール、アルキルメルカプタン等のメルカプト基を有する化合物等の活性水素を有する化合物が使用できる。重合時においてアクリル酸モノマーに対する連鎖移動剤の比率を増加させるほど、重合度の低い末端修飾ポリアクリル酸が製造でき、連鎖移動剤の比率を調整することにより任意の重量平均分子量の末端修飾ポリアクリル酸が製造できる。
The terminal-modified polyacrylic acid can be produced by a radical polymerization method, but it is not sufficient to increase the radical initiator as a molecular weight adjusting means for adjusting the molecular weight range, and a sufficient amount of chain transfer agent at the time of polymerization. Need to be added. The amount of chain transfer agent required varies depending on the polymerization conditions and the type of chain transfer agent, but is usually in the range of 5 to 100 mol%, preferably 10 to 50 mol%, based on the acrylic acid monomer. The chain transfer agent, isopropyl alcohol - le, alcohols such as isobutyl alcohol, main mercapto acid, mercaptopropionic acid, mercaptoethanol, compounds with active hydrogen compounds having a mercapto group such as an alkyl mercaptan can be used. As the ratio of the chain transfer agent to the acrylic acid monomer is increased during polymerization, a terminal-modified polyacrylic acid having a lower degree of polymerization can be produced. By adjusting the ratio of the chain transfer agent, the end-modified polyacrylic having an arbitrary weight average molecular weight is prepared. Acid can be produced.
連鎖移動剤共存下におけるラジカル重合は連鎖移動剤ラジカルを経由して開始され、連鎖移動剤への連鎖移動によって比較的重合度の低い末端修飾ポリアクリル酸が生成するため、生成物は連鎖移動剤断片を末端に有する構造を有する。例えば、連鎖移動剤としてイソプロピルアルコ−ルを使用した場合、下記一般式（２）に示す末端イソプロピルアルコール修飾ポリアクリル酸が生成する。必要な連鎖移動剤の量は、重合条件によって異なるが、通常はアクリル酸モノマーに対して２０〜１００モル％、好ましくは３０〜６０モル％の範囲である。 Radical polymerization in the presence of a chain transfer agent is initiated via a chain transfer agent radical, and chain transfer to the chain transfer agent produces a terminally modified polyacrylic acid with a relatively low degree of polymerization, so the product is a chain transfer agent It has a structure with a fragment at the end. For example, when isopropyl alcohol is used as a chain transfer agent, terminal isopropyl alcohol-modified polyacrylic acid represented by the following general formula (2) is generated. The amount of chain transfer agent required varies depending on the polymerization conditions, but is usually in the range of 20 to 100 mol%, preferably 30 to 60 mol%, based on the acrylic acid monomer.
連鎖移動剤としてメルカプト化合物を使用した場合、末端チオエーテル修飾ポリアクリル酸が生成する。例えば、連鎖移動剤としてβ−メルカプトプロピオン酸を使用した場合、下記一般式（４）に示す末端カルボキシエチルチオエーテル修飾ポリアクリル酸が生成する。必要な連鎖移動剤の量は、重合条件によって異なるが、通常はアクリル酸モノマーに対して５〜５０モル％、好ましくは１０〜２５モル％の範囲である。 When a mercapto compound is used as the chain transfer agent, terminal thioether-modified polyacrylic acid is generated. For example, when β-mercaptopropionic acid is used as the chain transfer agent, terminal carboxyethylthioether-modified polyacrylic acid represented by the following general formula (4) is generated. The amount of chain transfer agent required varies depending on the polymerization conditions, but is usually in the range of 5 to 50 mol%, preferably 10 to 25 mol%, based on the acrylic acid monomer.
連鎖移動剤としてアルコールを用いて合成したポリアクリル酸は、Ｎ−アルキル置換ヒドロキシルアミンとの相溶性が良好であるため、両者の混合物を調製する場合に有利である。上記のように末端基を修飾したポリアクリル酸は、未修飾のポリアクリル酸よりも耐加水分解性が優れており、ボイラのような高温水で使用する場合に好適である。本発明の末端修飾ポリアクリル酸は、アクリル酸以外にアクリル酸と共重合が可能な他の不飽和モノマーとの共重合体であっても良い。アクリル酸と共重合が可能な他の不飽和モノマーの例としてマレイン酸、イタコン酸、メタクリル酸、クロトン酸、フマル酸等のモノエチレン性不飽和カルボン酸およびその水溶性塩、スチレンスルホン酸、スルホアルキル（メタ）アクリレートエステル、スルホアルキル（メタ）アリルエーテル、（メタ）アリルスルホン酸、ビニルスルホン酸等のモノエチレン性不飽和スルホン酸およびその水溶性塩、ビニルホスホン酸、アリルホスホン酸等のモノエチレン性不飽和ホスホン酸およびその水溶性塩、（メタ）アクリルアミド、アルキル（メタ）アクリレートエステル、アルキル（メタ）アリルエーテル、ヒドロキシ置換アルキル（メタ）アクリレートエステル、ヒドロキシ置換アルキル（メタ）アリルエーテル、（メタ）アリルアルコール等の非イオン性のモノエチレン性不飽和単量体等が挙げられる。アクリル酸の重合比が低下すると腐食抑制効果が低下するため、アクリル酸と共重合が可能な他の不飽和モノマーの比率はモノマー全体に対して２０重量％以下が好ましい。
Polyacrylic acid synthesized using an alcohol as a chain transfer agent has good compatibility with N-alkyl-substituted hydroxylamine, and is advantageous in preparing a mixture of both. Polyacrylic acid having a modified terminal group as described above, has excellent hydrolysis resistance than polyacrylic acid unmodified, Ru suitable der when used in high-temperature water, such as boiler. The terminal-modified polyacrylic acid of the present invention may be a copolymer with other unsaturated monomer capable of copolymerizing with acrylic acid in addition to acrylic acid. Examples of other unsaturated monomers that can be copolymerized with acrylic acid include monoethylenically unsaturated carboxylic acids such as maleic acid, itaconic acid, methacrylic acid, crotonic acid, fumaric acid, and water-soluble salts thereof, styrene sulfonic acid, sulfone. Monoethylenically unsaturated sulfonic acids such as alkyl (meth) acrylate esters, sulfoalkyl (meth) allyl ethers, (meth) allyl sulfonic acids and vinyl sulfonic acids, and water-soluble salts thereof, and mono carboxylic acids such as vinyl phosphonic acid and allyl phosphonic acid Ethylenically unsaturated phosphonic acid and water-soluble salts thereof, (meth) acrylamide, alkyl (meth) acrylate ester, alkyl (meth) allyl ether, hydroxy-substituted alkyl (meth) acrylate ester, hydroxy-substituted alkyl (meth) allyl ether, ( Meta) allyl alcohol Nonionic monoethylenically unsaturated monomers and the like of the like. When the polymerization ratio of acrylic acid is lowered, the corrosion inhibiting effect is lowered. Therefore, the ratio of the other unsaturated monomer capable of copolymerization with acrylic acid is preferably 20% by weight or less based on the whole monomer.
本発明のＮ−アルキル置換ヒドロキシルアミンは、一般式（１）で表され、式中、Ｒ１，Ｒ２はそれぞれ独立に水素原子、炭素数１から３のアルキル基である。具体的には、Ｎ−メチルヒドロキシルアミン、Ｎ−エチルヒドロキシルアミン、Ｎ−ｎ−プロピルヒドロキシルアミン、Ｎ−イソプロピルヒドロキシルアミン、Ｎ、Ｎ−ジメチルヒドロキシルアミン、Ｎ、Ｎ−ジエチルヒドロキシルアミン、Ｎ、Ｎ−ｎ−ジプロピルヒドロキシルアミン、Ｎ、Ｎ−ジイソプロピルヒドロキシルアミン、Ｎ−メチル−Ｎ−エチルヒドロキシルアミン等が挙げられる。好ましくはＮ、Ｎ−ジエチルヒドロキシルアミンである。 The N-alkyl-substituted hydroxylamine of the present invention is represented by the general formula (1), in which R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Specifically, N-methylhydroxylamine, N-ethylhydroxylamine, Nn-propylhydroxylamine, N-isopropylhydroxylamine, N, N-dimethylhydroxylamine, N, N-diethylhydroxylamine, N, N -N-dipropylhydroxylamine, N, N-diisopropylhydroxylamine, N-methyl-N-ethylhydroxylamine and the like. N, N-diethylhydroxylamine is preferred.
本発明のボイラの腐食抑制剤（以下「腐食抑制剤」とする）は、（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキルヒドロキシルアミンを含む腐食防止剤であり、目的とするボイラの腐食抑制の程度により適宜、この両者の比率を決定され、一律に決めることはできないが、通常は（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキルヒドロキシルアミンを重量比１０：９０〜９０：１０の範囲で含み、好ましくは２０：８０〜５０：５０である。 The boiler corrosion inhibitor of the present invention (hereinafter referred to as “corrosion inhibitor”) is a corrosion inhibitor containing (A) terminal-modified polyacrylic acid and (B) N-alkylhydroxylamine, The ratio between the two is appropriately determined depending on the degree of corrosion inhibition and cannot be uniformly determined. Usually, however, the weight ratio of (A) terminal-modified polyacrylic acid and (B) N-alkylhydroxylamine is 10:90 to 90. : 10, preferably 20:80 to 50:50.
腐食抑制剤の製造方法は、特に限定されるものではなく、（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキル置換ヒドロキシルアミンを撹拌しながら溶媒に溶解させて調製される。溶媒としては、水が最も好ましく、場合によっては水溶性有機溶媒であるエチレングリコール、ジエチレングリコール、トリエチレングリコール、グリセリン、ジオキサン等を併用してもよい。本発明の腐食防止剤における（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキル置換ヒドロキシルアミンの合計量は、特に限定されるものではなく、通常、５〜５０重量％である。腐食抑制剤の効果を損なわない範囲で他の腐食抑制剤を配合してもよい。 The method for producing the corrosion inhibitor is not particularly limited, and is prepared by dissolving (A) terminal-modified polyacrylic acid and (B) N-alkyl-substituted hydroxylamine in a solvent while stirring. As the solvent, water is most preferable, and in some cases, water-soluble organic solvents such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and dioxane may be used in combination. The total amount of (A) terminal-modified polyacrylic acid and (B) N-alkyl-substituted hydroxylamine in the corrosion inhibitor of the present invention is not particularly limited, and is usually 5 to 50% by weight. You may mix | blend another corrosion inhibitor in the range which does not impair the effect of a corrosion inhibitor.
腐食抑制剤の添加は、対象とするボイラシステム水系の水質及び目的とする腐食抑制効果の程度を考慮して適宜決定されるものであり、一律に定めることはできないが、通常、末端修飾ポリアクリル酸の添加量として、給水に対して０.０５〜１０ｍｇ／Ｌ、ボイラ水に対して０.５〜２００ｍｇ／Ｌ、好ましくはボイラシステム水系中のカルシウム、マグネシウム、鉄、銅、亜鉛の合計量に対して２〜３０重量部の末端修飾ポリアクリル酸量になるような腐食抑制剤の添加量である。また、Ｎ−アルキル置換ヒドロキシルアミンの添加量としては、給水中の溶存酸素濃度により異なるが、通常は溶存酸素１モルに対して０.２〜５モルのＮ−アルキル置換ヒドロキシルアミンを添加するか、あるいは給水中に１０〜１０００μｇ／ＬのＮ−アルキル置換ヒドロキシルアミンが残留濃度として検出されるようなＮ−アルキル置換ヒドロキシルアミンの添加量である。 The addition of the corrosion inhibitor is appropriately determined in consideration of the water quality of the target boiler system water system and the target degree of the corrosion inhibition effect, and cannot be uniformly determined. As addition amount of acid, 0.05 to 10 mg / L for feed water, 0.5 to 200 mg / L for boiler water, preferably total amount of calcium, magnesium, iron, copper and zinc in boiler system water system The addition amount of the corrosion inhibitor is 2 to 30 parts by weight of the end-modified polyacrylic acid. Further, the amount of N-alkyl-substituted hydroxylamine added varies depending on the dissolved oxygen concentration in the feed water, but usually 0.2 to 5 mol of N-alkyl-substituted hydroxylamine is added to 1 mol of dissolved oxygen. Or the amount of N-alkyl-substituted hydroxylamine added such that 10-1000 μg / L of N-alkyl-substituted hydroxylamine is detected as a residual concentration in the feed water.
腐食抑制剤の添加方法は、特に限定されるものではなく、一般的な薬注ポンプを用いて添加される。本発明の腐食抑制剤の添加箇所は、通常、ボイラの給水に対して添加するが、ボイラに直接添加しても良く、またボイラ本体だけでなく給水系統の腐食抑制が必要な場合は、給水系統の上流側に添加するのが好ましい。 The addition method of a corrosion inhibitor is not specifically limited, It adds using a common chemical injection pump. The location where the corrosion inhibitor of the present invention is added is usually added to the boiler feed water, but it may be added directly to the boiler, and if it is necessary to inhibit corrosion of the feed water system as well as the boiler body, It is preferable to add to the upstream side of the system.
腐食抑制剤とともに給水ならびにボイラ水のｐＨを調整するためにアルカリ金属水酸化物、リン酸塩、揮発性アミン、アンモニアから選択される１種以上の化合物と併用してもよい。ボイラ水のｐＨは通常８.５〜１２.０の範囲に調整されるが、ｐＨが低過ぎてもｐＨが高過ぎても腐食が発生し易くなる。補給水として腐食性イオン濃度が高い軟化水を使用しているボイラ蒸気圧が２ＭＰａ以下のボイラではボイラ水のｐＨは１１.０〜１２.０程度に調整するのが好ましい。一方、ボイラの蒸気圧が２ＭＰａを超えるボイラではｐＨは８.５〜１１.０程度に調整するのが好ましいが、アルカリ腐食の防止のため蒸気圧が高いボイラほどｐＨの上限値を低く抑えることが好ましい。蒸気圧力が３ＭＰａを超えるボイラでは、水酸化カリウムやリン酸カリウム等のカリウム塩を使用するとアルカリ腐食が発生し易くなるため、アルカリ金属水酸化物としては水酸化ナトリウム、リン酸塩としては第２リン酸ナトリウム、第３リン酸ナトリウム、トリポリリン酸ナトリウム等のナトリウム塩を使用するのが好ましい。使用圧力別のボイラ水ｐＨの適正値は、例えばＪＩＳ Ｂ８２２３：１９９９『ボイラの給水及びボイラ水の水質』に規定されている。 You may use together with 1 or more types of compounds selected from an alkali metal hydroxide, a phosphate, a volatile amine, and ammonia in order to adjust pH of feed water and boiler water with a corrosion inhibitor. The pH of boiler water is usually adjusted to a range of 8.5 to 12.0, but corrosion is likely to occur if the pH is too low or too high. In a boiler using a softened water having a high corrosive ion concentration as makeup water and having a boiler vapor pressure of 2 MPa or less, the pH of the boiler water is preferably adjusted to about 11.0 to 12.0. On the other hand, it is preferable to adjust the pH to about 8.5 to 11.0 for a boiler whose steam pressure exceeds 2 MPa. However, the higher the steam pressure, the lower the upper limit value of the pH in order to prevent alkaline corrosion. Is preferred. In a boiler having a steam pressure exceeding 3 MPa, alkaline corrosion is likely to occur when potassium salts such as potassium hydroxide and potassium phosphate are used. Therefore, sodium hydroxide is used as the alkali metal hydroxide, and second is used as the phosphate. It is preferable to use sodium salts such as sodium phosphate, tribasic sodium phosphate and sodium tripolyphosphate. The appropriate value of the boiler water pH for each operating pressure is defined in, for example, JIS B8223: 1999 “Boiler Supply Water and Boiler Water Quality”.
本発明のボイラの腐食抑制方法（以下「腐食抑制方法」とする）は、ヒドラジンを用いていないボイラシステム水系に前記（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキル置換ヒドロキシルアミンを組み合わせて添加する腐食抑制方法である。 The boiler corrosion inhibiting method of the present invention (hereinafter referred to as “corrosion inhibiting method”) is a combination of (A) terminal-modified polyacrylic acid and (B) N-alkyl-substituted hydroxylamine in a boiler system water system not using hydrazine. It is a corrosion control method to be added.
末端修飾ポリアクリル酸の添加量は、対象とするボイラシステム水系の水質及び目的とする腐食抑制効果の程度を考慮して適宜決定されるものであり、一律に定めることはできないが、通常、給水に対して０.０５〜１０ｍｇ／Ｌ、ボイラ水に対して０.５〜２００ｍｇ／Ｌ、好ましくはボイラシステム水系中のカルシウム、マグネシウム、鉄、銅、亜鉛の合計量に対して２〜３０重量部の末端修飾ポリアクリル酸量である。 The amount of the terminal-modified polyacrylic acid added is appropriately determined in consideration of the water quality of the target boiler system water system and the target degree of the corrosion inhibition effect, and cannot be uniformly determined. 0.05 to 10 mg / L with respect to boiler water, 0.5 to 200 mg / L with respect to boiler water, preferably 2 to 30 weights with respect to the total amount of calcium, magnesium, iron, copper and zinc in the boiler system water system Part of the end-modified polyacrylic acid.
また、Ｎ−アルキル置換ヒドロキシルアミンの添加量は、給水中の溶存酸素濃度により異なるが、通常は溶存酸素１モルに対してＮ−アルキル置換ヒドロキシルアミンを０.２〜５モルの比率で添加する、あるいは給水中のＮ−アルキル置換ヒドロキシルアミンの残留濃度が１０〜１０００μｇ／Ｌとして検出されるように添加する。さらに（Ａ）末端修飾ポリアクリル酸と（Ｂ）Ｎ−アルキル置換ヒドロキシルアミンは、重量比として１０：９０〜９０：１０、好ましくは２０：８０〜５０：５０で組み合わせて添加される。 Moreover, although the addition amount of N-alkyl substituted hydroxylamine changes with dissolved oxygen concentration in feed water, N-alkyl substituted hydroxylamine is normally added in the ratio of 0.2-5 mol with respect to 1 mol of dissolved oxygen. Alternatively, it is added so that the residual concentration of N-alkyl-substituted hydroxylamine in the feed water is detected as 10 to 1000 μg / L. Furthermore, (A) terminal-modified polyacrylic acid and (B) N-alkyl-substituted hydroxylamine are added in a weight ratio of 10:90 to 90:10, preferably 20:80 to 50:50.
腐食抑制方法では、末端修飾ポリアクリル酸とＮ−アルキル置換ヒドロキシルアミンを混合した一液性組成物として薬注ポンプで添加する方法、両者をそれぞれ別々に薬注ポンプで添加する方法があり、いずれでもよい。末端修飾ポリアクリル酸及びＮ−アルキル置換ヒドロキシルアミンの添加箇所は、通常、ボイラの給水に対して添加するが、ボイラに直接添加しても良く、またボイラ本体だけでなく給水系統の腐食抑制が必要な場合は、給水系統の上流側に添加するのが好ましい。 In the corrosion inhibition method, there is a method of adding with a chemical injection pump as a one-component composition in which terminal-modified polyacrylic acid and N-alkyl-substituted hydroxylamine are mixed, and a method of adding both separately with a chemical injection pump. But you can. The end-modified polyacrylic acid and N-alkyl-substituted hydroxylamine are usually added to the boiler feed water, but they may be added directly to the boiler, and the corrosion of not only the boiler body but also the feed water system is suppressed. If necessary, it is preferably added to the upstream side of the water supply system.
以下に本発明を具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 The present invention will be specifically described below, but the present invention is not limited to these examples.
（末端修飾ポリアクリル酸）
Ａ−１：イソプロピルアルコール修飾ポリアクリル酸（Ｍｗ２７００）
Ａ−２：カルボキシエチルチオエーテル修飾ポリアクリル酸（Ｍｗ２０００）
Ａ−３：イソプロピルアルコール修飾ポリアクリル酸（Ｍｗ５０００）
(Terminal modified polyacrylic acid)
A-1: Isopropyl alcohol-modified polyacrylic acid (Mw2700 )
A - 2 : Carboxyethylthioether-modified polyacrylic acid (Mw2000)
A- 3 : Isopropyl alcohol-modified polyacrylic acid (Mw5000)
（Ｎ−アルキル置換ヒドロキシルアミン）
Ｂ−１：Ｎ、Ｎ−ジエチルヒドロキシルアミン
Ｂ−２：Ｎ−イソプロピルヒドロキシルアミン
Ｂ−３：Ｎ−ｔｅｒｔ−ブチルヒドロキシルアミン
(N-alkyl substituted hydroxylamine)
B-1: N, N-diethylhydroxylamine B-2: N-isopropylhydroxylamine B-3: N-tert-butylhydroxylamine
（その他）
Ｃ−１：イソプロピルアルコール修飾ポリアクリル酸（Ｍｗ５０００）
Ｃ−２：スルホン酸修飾ポリアクリル酸（Ｍｗ４５００）
Ｃ−３：アクリル酸−イタコン酸共重合体（Ｍｗ３０００）
Ｃ−４：アクリル酸−メタクリル酸共重合体（Ｍｗ３０００）
Ｃ−５：アクリル酸−マレイン酸共重合体（Ｍｗ３０００）
Ｃ−６：アクリル酸−アクリル酸エチル共重合体（Ｍｗ２０００）
Ｃ−７：マレイン酸共重合体（Ｍｗ１０００）
(Other)
C-1: Isopropyl alcohol-modified polyacrylic acid (Mw5000)
C-2: Polyacrylic acid modified with sulfonic acid (Mw4500)
C-3: Acrylic acid-itaconic acid copolymer (Mw3000)
C-4: Acrylic acid-methacrylic acid copolymer (Mw3000)
C-5: Acrylic acid-maleic acid copolymer (Mw3000)
C-6: Acrylic acid-ethyl acrylate copolymer (Mw2000)
C-7: Maleic acid copolymer (Mw1000)
（腐食試験１）
４００番研磨紙で研磨仕上げした寸法が１×１３×７５ｍｍの炭素鋼製試験片（材質：ＪＩＳ Ｇ３１４１ ＳＰＣＣ−ＳＢ）をアセトンで脱脂後、乾燥して試験前の質量を測定した。表−１に示す腐食抑制剤を添加した試験液１００ｍＬと試験片１枚をステンレス鋼製オートクレーブに入れ、温度１８０℃、蒸気圧０.７ＭＰａを３日間維持した。試験水の炭酸イオンと重炭酸イオン濃度の合計は３００ｍｇＣａＣＯ３／Ｌ、シリカは３００ｍｇ／Ｌ、塩化物イオンは１５０ｍｇ／Ｌであった。水酸化ナトリウムを添加して試験液のｐＨを１１.０に調整した。オートクレーブを冷却後、試験片を取り出して付着物を除去後、試験後の質量を測定し、下記式より腐食速度を計算した。
腐食速度（ｍｄｄ）＝（Ｗ０−Ｗ１）／（Ｓ×Ｔ）
Ｗ０：試験前の質量（ｍｇ）、
Ｗ１：試験後の質量（ｍｇ）
Ｓ：試験片の表面積（ｄｍ２）
Ｔ：試験期間（ｄａｙ）
結果を表１に示いた。
(Corrosion test 1)
A carbon steel test piece (material: JIS G3141 SPCC-SB) having a size of 1 × 13 × 75 mm polished with No. 400 polishing paper was degreased with acetone and dried to measure the mass before the test. 100 mL of a test solution to which a corrosion inhibitor shown in Table-1 was added and one test piece were placed in a stainless steel autoclave and maintained at a temperature of 180 ° C. and a vapor pressure of 0.7 MPa for 3 days. The total concentration of carbonate ion and bicarbonate ion in the test water was 300 mgCaCO 3 / L, silica was 300 mg / L, and chloride ion was 150 mg / L. Sodium hydroxide was added to adjust the pH of the test solution to 11.0. After cooling the autoclave, the test piece was taken out and the deposits were removed, the mass after the test was measured, and the corrosion rate was calculated from the following formula.
Corrosion rate (mdd) = (W 0 −W 1 ) / (S × T)
W 0 : Mass (mg) before test,
W 1 : Mass after test (mg)
S: surface area of the test piece (dm 2 )
T: Test period (day)
The results are shown in Table 1.
重量平均分子量が１，０００〜３，０００のポリアクリル酸とＮ−アルキル置換ヒドロキシルアルキルアミンを併用する本発明の方法では、腐食速度は２．１〜３．５(ｍｄｄ)となり、それぞれを単独で使用した場合よりも腐食抑制効果が優れていることが確認された。また、重量平均分子量が１，０００〜３，０００の範囲を超えるポリアクリル酸を使用した場合では、腐食抑制効果が劣っていることが確認され、本発明の重量平均分子量が１，０００〜３，０００のポリアクリル酸が有効であることを示している。 In the method of the present invention in which polyacrylic acid having a weight average molecular weight of 1,000 to 3,000 and N-alkyl-substituted hydroxylalkylamine are used in combination, the corrosion rate is 2.1 to 3.5 (mdd). It was confirmed that the corrosion-inhibiting effect was superior to that when used in Moreover, when the polyacrylic acid whose weight average molecular weight exceeds the range of 1,000-3,000 is used, it is confirmed that the corrosion inhibitory effect is inferior, and the weight average molecular weight of this invention is 1,000-3. 1,000 polyacrylic acid is shown to be effective.
（腐食試験２）
蒸気圧力３ＭＰａ、給水量１５ｔ／ｈの水管ボイラーにおいて本発明の腐食抑制剤の実機試験を実施した。ボイラの補給水はイオン交換水であり、腐食抑制剤添加前の給水中の溶存酸素濃度は０.０３ｍｇ／Ｌであった。表２に示す腐植抑制剤を給水量に対して８ｍｇ／Ｌ添加した。ボイラーのブロー率は１〜３％、濃縮度は３３〜５０倍であった。ボイラー水のｐＨは１０〜１１、給水中のＮ、Ｎ−ジエチルヒドロキシルアミンの残留濃度は１００〜３００ｍｇ／Ｌの範囲であった。１年間運転後の開放結果では、ボイラのドラムと水管内は清浄であり、腐食やスケールは認められなかった。
(Corrosion test 2)
An actual machine test of the corrosion inhibitor of the present invention was carried out in a water pipe boiler with a steam pressure of 3 MPa and a water supply amount of 15 t / h. The boiler makeup water was ion exchange water, and the dissolved oxygen concentration in the feed water before the addition of the corrosion inhibitor was 0.03 mg / L. 8 mg / L of the humus inhibitor shown in Table 2 was added to the amount of water supply. The blow rate of the boiler was 1 to 3%, and the concentration was 33 to 50 times. The pH of the boiler water was 10 to 11, and the residual concentration of N, N-diethylhydroxylamine in the feed water was in the range of 100 to 300 mg / L. As a result of opening after one year of operation, the boiler drum and water pipe were clean and no corrosion or scale was observed.
（相溶性試験）
重合体を活性分として１.５重量％、Ｎ、Ｎ−ジエチルヒドロキシルアミンを５重量％、水酸化ナトリウム４.５重量％、水酸化カリウム４.５重量％を含有し、残部が水である腐食抑制剤を調製して溶解安定性を調べた。結果を表３に示した。重量平均分子量が１０００〜３０００のポリアクリル酸に替えて重量平均分子量が３０００を超えるポリアクリル酸を使用した場合、Ｎ、Ｎ−ジエチルヒドロキシルアミンとの相溶性が劣っていることが確認された。ポリアクリル酸以外のポリマーを用いると、重量平均分子量が１０００〜３０００の範囲であってもＮ、Ｎ−ジエチルヒドロキシルアミンとの相溶性が劣っていることが確認された。
(Compatibility test)
It contains 1.5% by weight of polymer as an active ingredient, 5% by weight of N, N-diethylhydroxylamine, 4.5% by weight of sodium hydroxide, 4.5% by weight of potassium hydroxide, and the balance is water. A corrosion inhibitor was prepared and the dissolution stability was investigated. The results are shown in Table 3. When polyacrylic acid having a weight average molecular weight exceeding 3000 was used instead of polyacrylic acid having a weight average molecular weight of 1000 to 3000, it was confirmed that the compatibility with N, N-diethylhydroxylamine was poor. When a polymer other than polyacrylic acid was used, it was confirmed that the compatibility with N, N-diethylhydroxylamine was poor even when the weight average molecular weight was in the range of 1000 to 3000.
Claims (4)
(A) and component (B) weight ratio of components 10: 90-90: 3. Symbol mounting of the boiler methods corrosion inhibition is added at 10.
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