5589107Method and composition for inhibiting corrosion.docx

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]

U.S.PatentDocuments

4067690

January1978

Cuisiaetal.

4079018

March1978

Noack

4124500

November1978

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

November1990

Soderquistetal.

4980128

December1990

Cuisiaetal.

5091108

February1992

Harderetal.

5094814

March1992

Soderquistetal.

5164110

November1992

Haraer

5167835

December1992

Harder

5213678

May1993

Rondumetal.

5256311

October1993

Rossietal.

5258125

November1993

Kellyetal.

5271847

December1993

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