5589107Method and composition for inhibiting corrosion.docx
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5589107Methodandcompositionforinhibitingcorrosion
(1of1)
UnitedStatesPatent
5,589,107
Scheurman,III
December31,1996
Methodandcompositionforinhibitingcorrosion
Abstract
Corrosionofferrousmetalsurfacesinanaqueoussystem,suchasaboilersystem,isinhibitedbyaddingafirstcomponentandasecondcomponent,thefirstcomponentbeingpreferablycarbohydrazide,hydrazine,orasaltthereof,thesecondcomponentbeingselectedfromthegroupconsistingofcertainhydroxylaminecompoundsormixturesthereof,preferablyN,N-diethylhydroxylamine.Theweightratiooftheaddedfirstcomponenttotheaddedsecondcomponentisbetweenabout4:
1andabout1:
4.
Inventors:
Scheurman,III;Clarence(Westlake,OH)
Assignee:
AppliedSpecialties,Inc.(AvonLake,OH)
Appl.No.:
08/291,589
Filed:
August15,1994
CurrentU.S.Class:
252/392;106/14.37;210/750;252/188.28;252/389.61;252/389.62;252/390;422/16
CurrentInternationalClass:
C23F11/10 (20060101);C23F11/14 (20060101);C23F011/14 ();C23F015/00 ();C23C022/00 ()
FieldofSearch:
252/188.28,392,390,389.61,389.62210/750422/16106/14.37
ReferencesCited[ReferencedBy]
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4067690
January1978
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4079018
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Noack
4124500
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Arghiropoulosetal.
4269717
May1981
Slovinsky
4350606
September1982
Cuisiaetal.
4487708
December1984
Muccitelli
4496761
January1985
Lange,Jr.
4569783
February1986
Muccitelli
4626411
December1986
Nemesetal.
4681737
July1987
Walkeretal.
4689201
August1987
Longworthetal.
4891141
January1990
Christensenetal.
4968438
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Soderquistetal.
4980128
December1990
Cuisiaetal.
5091108
February1992
Harderetal.
5094814
March1992
Soderquistetal.
5164110
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Haraer
5167835
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Harder
5213678
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Rondumetal.
5256311
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Rossietal.
5258125
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5271847
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Chenetal.
PrimaryExaminer:
Lovering;RichardD.
AssistantExaminer:
Fee;Valerie
Attorney,AgentorFirm:
Pearne,Gordon,McCoy&Granger
Claims
Whatisclaimedis:
1.Acompositionwhichisusefulforinhibitingcorrosionofferrousmetalsurfacesinanaqueoussystemcomprisingafirstcomponentandasecondcomponent,saidfirstcomponentbeingselectedfromthegroupconsistingofcarbohydrazide,water-solublesaltsofcarbohydrazide,hydrazine,water-solublesaltsofhydrazine,andmixturesofanyoftheforegoing,saidsecondcomponentbeingselectedfromthegroupconsistingofcertainhydroxylaminecompoundsormixturesthereof,saidcertainhydroxylaminecompoundshavingtheformula##STR2##whereR.sub.1,R.sub.2,andR.sub.3areeitherthesameordifferentandareselectedfromthegroupconsistingofhydrogenandloweralkylcontaining1toabout6carbonatoms,orawater-solublesaltthereof;theweightratioofthefirstcomponenttothesecondcomponentbeingacorrosioninhibitingratiobetweenabout4:
1andabout1:
4.
2.Acompositionaccordingtoclaim1,saidfirstandsecondcomponentsbeinginanaqueoussolution.
3.Acompositionaccordingtoclaim2,saidcompositionconsistingessentiallyofsaidfirstandsecondcomponents.
4.Acompositionaccordingtoclaim3whereinsaidfirstcomponentiscarbohydrazideandsaidsecondcomponentisN,N-diethyhydroxylamine.
5.Acompositionaccordingtoclaim4,whereintheweightratioofthefirstcomponenttothesecondcomponentisbetweenabout2:
1andabout1:
2.
6.Acompositionaccordingtoclaim2,whereinsaidfirstcomponentiscarbohydrazide.
7.Acompositionaccordingtoclaim6,whereinsaidsecondcomponentisN,N-diethylhydroxylamine.
8.Acompositionaccordingtoclaim7,whereintheweightratioofthefirstcomponenttothesecondcomponentisbetweenabout2:
1andabout1:
2.
9.Acompositionaccordingtoclaim2,whereinsaidsecondcomponentisN,N-diethylhydroxylamine.
10.Acompositionaccordingtoclaim2,whereintheweightratioofthefirstcomponenttothesecondcomponentisbetweenabout2:
1andabout1:
2.
Description
BACKGROUNDOFTHEINVENTION
Thisinventionrelatesgenerallytoinhibitionandcontrolofcorrosionofmetalsurfacesinanaqueoussystemandmorespecificallytocompositionsandmethodstopassivateironandsteelsurfacesinboilerandcoolingsystems.
DESCRIPTIONOFRELATEDART
Inboilers,closedloopcoolingsystems,heatexchangers,andotheraqueoussystems,corrosionofmetalsurfacesisasevereproblem.Inboilersystems,corrosionmayoccurinfeedlines,theboiler,steamlines,steamcondensatereturnlines,heaters,economizers,andotherpartsoftheboilersystem.Similarcorrosionmayoccurinclosedloopcoolingsystems.Corrosiongenerallyarisesfromdissolvedoxygenandotherchemicalsattackingtheironorsteelsurfaces,whichattackisacceleratedbythehightemperaturesfoundinboilersystems.Sinceacidicconditionstendtoacceleratethistypeofcorrosion,mostboilerandcoolingsystemsareoperatedunderalkalineconditions.
Typicallyinboilersystemsthreethingsaredonetoprotectferrousmetalfromcorrosion.Mostofthedissolvedoxygenandothergasesarefirstmechanicallyremovedbyvacuumdegasifiersordeaeratingheaters.Secondly,chemicalsareaddedtochemicallyscavengeremainingoxygen.Thirdly,thesameordifferentchemicalsareaddedtopassivatethemetalsurfaces,thatis,protectthemfromattackbyoxygenorotherchemicals.Similarapproachesareusedwithcoolingsystems.
Hydrazinehasbeenusedformanyyearsasaboilerwatertreatment.Itcanreactwithresidualdissolvedoxygentoformwaterandgaseousnitrogen.Undercertainconditionsitcanactasametalpassivatorbyformingaprotectivelayerofmagnetiteoverironsurfaces.However,hydrazineisatoxicchemicalandindustryisattemptingtominimizeitsuse.
Otherboilerandcoolingwatertreatmentshavebeensuggested.See,forexample,U.S.Pat.Nos.5,258,125;4,689,201;4,626,411;4,350,606;4,269,717;and4,067,690,thecontentsofwhichareincorporatedbyreferenceintheirentirety.However,mostofthesetreatmentsfocustoomuchonoxygenremovalandnotenoughonmetalsurfacepassivation.Whatisneededisatreatmentwhichpassivatesandcoversandcoatsthemetalsurfacestosuchanextentthatanydissolvedoxygenwhichispresentisunabletoeffectivelyattackthesurface.Whenthemetalsurfaceissufficientlypassivated,certainlevelsofdissolvedoxygencanbetolerated.Itisanobjectofthepresentinventiontoprovideeffectivemetalsurfacepassivation,particularlyinhighpressure,hightemperatureboilersystems.
SUMMARYOFTHEINVENTION
Amethodforinhibitingcorrosionofferrousmetalsurfacesinanaqueoussystemisprovided.TheaqueoussystemcontainssystemwaterhavinganalkalinepH,themethodcomprisingaddingtothesystemwaterafirstcomponentandasecondcomponent.Thefirstcomponentisselectedfromthegroupconsistingofcarbohydrazide,water-solublesaltsofcarbohydrazide,hydrazine,water-solublesaltsofhydrazine,andmixturesofanyoftheforegoing.Thesecondcomponentisselectedfromthegroupconsistingofcertainhydroxylaminecompoundsormixturesthereof,moreparticularlydescribedhereinafter.Theweightratiooftheaddedfirstcomponenttotheaddedsecondcomponentisbetweenabout4:
1andabout1:
4.Thetotaldosageofthefirstcomponentandthesecondcomponenttothesystemwatertogetherisaneffectiveferrousmetalsurfacepassivatingamount.Acompositioncomprisingthefirstcomponentandthesecondcomponentisalsoprovided.
DETAILEDDESCRIPTIONOFTHEPREFERREDEMBODIMENTS
Partspermillion(ppm)andpartsperbillion(ppb)asusedhereinarepartsbyweight.
Thepresentinventionisusefulasatreatmentoradditivetoinhibitandcontrolcorrosionofmetalsurfaces,suchasferrousmetalsurfaces,inanaqueoussystemsuchasacoolingsystem(particularlyaclosedloopcoolingsystem)oraboilersystem.Anaqueoussystemcontainssystemwater;forexampleacoolingsystemcontainscoolingwaterandaboilersystemcontainsboilerwater.Thesystemwater,intheformofwaterorsteam,typicallyandgenerallycontactstheferrousmetalsurfaceoftheaqueoussystem,forexample,theinnersurfacesofmetalpipes,tubes,tanks,etc.
Thepresentinventionincludesaddingafirstcomponentandasecondcomponenttosystemwatertopassivateferrousmetalsurfacesinanaqueoussystemandtocontrolandinhibitcorrosion.Thefirstcomponentisselectedfromthegroupconsistingofcarbohydrazide,water-solublesaltsofcarbohydrazide,hydrazine,water-solublesaltsofhydrazine,andmixturesofanyoftheforegoingandispreferablycarbohydrazideduetothetoxicnatureofhydrazineandtheperformanceresultsshownbycarbohydrazide.Water-solublesaltsarelesspreferredduetothepresenceofionicmaterial.
Thesecondcomponentisselectedfromthegroupconsistingofcertainhydroxylaminecompoundsormixturesthereof,saidcertainhydroxylaminecompoundshavingthegeneralformula##STR1##whereR.sub.1,R.sub.2,andR.sub.3areeitherthesameordifferentandareselectedfromthegroupconsistingofhydrogenandloweralkylcontaining1toabout6(morepreferably1to3)carbonatoms,orawater-solublesaltthereof.Typicalwater-solublesaltsarethephosphate,sulfate,andchloridesalts,althoughthereareothersknownintheart.Preferablythesecondcomponentisusedwithoutthesesalts,inordertominimizeionicmaterialinthesystemwater.PreferablyR.sub.3ishydrogen.Thesecondcomponentispreferablyhydroxylamine,N,N-diethylhydroxylami