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Training Boiler Water Treatment
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Boiler Overview
• Steamisthebasicenergytransfermedium Usesinclude
Residen7alandcommercialhea7ng Plantprocesssteam Plantpowergenera7on U7lityplantopera7on
• Cri7caltotheopera7onoftheboileriswaterpurity• Thecomponentssurroundingatypicalboilersystem
includethefollowing:
Pretreatment(ionexchange,filtra7on) Dearator(combinedwithcondensatereturn) Economizer(heatreuse) Steammanagementequipment(headers,traps)
Pretreatment
• Preparethewatertobeboiled Calciumandmagnesiumsaltsaremost
insolubleinthehoHestareas
• Goalofpretreatment Minimizewateruseorwastage Minimizechemicaluseandreduceoverallcosts
• Commonmethods SoLening‐exchangehardnessforlessharmfulion LimesoLening‐precipitatehardness Filtra7on‐removesolids Demineraliza7on‐exchangeallionsforH+&OH‐
Reverseosmosis‐removeallionstoconcentrate
Softening
• Removeshardnessinexchangeforsodium
• RegeneratesoLenerwithsodiumchloride
• Hardnessproblemsandconsequences Ironfouling,organicfouling,poorregenera7on,poorcontrol,
damagedinternals Increaseddeposi7oninboiler,lossofheattransfer
ZeoliteSoLener
Na*Resin
Ca/Mg*Resin
[Ca&Mg]*[SO42Cl2HCO3]
[Na2SO42NaCl2HCO3]
Deaeration
BasedonDalton’sandHenry’sLawsofgassolubilityinwaterrela7ngtopressureandtemperature.
Deaeration
• Toomuchoxygenintheboilercausesrust4Fe3O4(magne7te)+O26Fe2O3(hema7te)
• Canremovethisoxygenmechanicallyorchemically Mechanically
Increasetemperaturedrivingoffoxygen Increasesurfaceareaofwaterdrivingoffoxygen
Chemically Sulfitereactswithoxygentomakesulfateinwater Organicacid,hydrazine,DEHA,hydroquinone
• Combina7onofmechanicalandchemicalmeansistypical
Boiler System
• Firetubeboilers Combus7ontakesplaceinsidetubes Wateronshellside,mustkeepimpuri7esfrom
s7ckingtotheoutsideofthecombus7ontubes MudgravityseHlestoboHomtobeblowndown,withsteam
outthetopofthevessel Commonpackagedsystems
• Watertubeboilers Waterontubeside,tubesconsistofrisersanddowncomers.
Steamisontopinthesteamdrum,withdepositscollectedinboHommuddrum
Severalshapesandsizesexist Inspec7on
Water Treatment Programs • Inaboiler,mineralcontentinthe
remainingboilerwaterisconcentrated;ionsdonotevaporate
• Cyclesofconcentra7on
• Internalboilerwatertreatmentprograms Precipita7ngprograms
− Phosphatebasedprograms (10Ca2+6PO4
2‐+2OH‐Ca10(OH)2(PO4)6) Analy7caltes7ngproceduresandreview
Solubilizingprograms− Allpolymerdispersantprograms
Analy7caltes7ngproceduresandreview− Chelantprograms
Analy7caltes7ngproceduresandreview
Condense Treatment
• Oncesteamisused,itiscondensedandreturnedtothefeedwatersystem ThemorereturnedthebeHer
Savingsinmakeupwater,becausefeedwateriscomposedofmakeupandcondensatereturn
Savingsinheat,withcondensateabout140degreeshoHerthanmakeup,sofor1lbofwater,ittakes140BTUofenergytogetmakeuptoanequivalenttemperature
• Thecarbondioxideinsteamcondensesandcanformcarbonicacid,unlesspHiscontrolled
• Neutralizingamines Theycondenseinselec7veloca7ons
inthecondensatesystem(near,intermediate,andfar)
Testing Methods
• Analysisofimpuri7espresentinwater
• Repor7ngquan77es Explana7onofpartspermillion
• Titra7ons Alkalinity,sulfite,hardnessandchlorides
• ColorimetricTests Phosphate,molybdates
• On‐lineinstrumentaltests TDS/conduc7vitymeasurement/pH
Forsurfaceblowdownandcondensate
Test Procedures
• HardnessTest–SoLener&Condensate1. Measure100mLofsample2. Add2brassdipperfulofHardnessBufferReagent(Code291)
ands7r3. Add1brassdipperfulofHardnessIndicatorReagent
(Code290)ands7r.Ifsampleisblue,thewaterissoL4. AddHardnessTitra7ngSolu7ondropbydropun7lcolor
turnsblue5. Mul7plybureHereadingby10todeterminepartspermillion
totalhardness6. Controlatlessthan1.0ppm
Test Procedures
• SulfiteTest–BoilerWater1. Measure50mLofsample2. Add4dropsofPhenolphthaleinIndicator(Code212)3. Add1plas7cdipperfulofSulfiteIndicator(Code219)ata
7meands7rbetweeneachaddi7on.Con7nueaddi7onun7lredcolordisappears,thenaddoneaddi7onaldipperful
4. SlowlyaddPotassiumIodide‐Iodatesolu7on(Code237).S7rconstantlyun7lafaintpermanentbluecolordevelops
5. Mul7plybureHereadingby10todeterminepartspermillionsulfite.
6. Controlat30–60ppmsulfite
Test Procedures
• NeutralizedConduc7vity–BoilerWater1. To50mLboilerwater,add1mLofLiquidConduc7vity
Reagent(Code944)ata7meandswirltomixun7lcolorless2. Measureconduc7vityonMyronconduc7vitymeter3. Controlat4000–5000umhos
Test Procedures
• Orthophosphate–BoilerWater1. Add5mLoffilteredsampletomixingtube(Code152)2. AddMolybdateReagent(Code236)tosecondmark(15mL)3. Stopperandmix.AddonebrassdipperfulofStannous
Reagent(Code239),stopperandmixwell4. Placemixingtubeinviewingcompartment,compare,
andrecordresult5. Controlat30–60ppmphosphate
Test Procedures
• HydroxylAlkalinity–BoilerWater1. Fillmixingcylinderto25mLmarkwithboilerwater2. Add1mLbariumchloridesolu7on,swirltomix3. Add2dropsPhenolphthaleinindicator,swirltomix4. Addsulfuricacidreagentonedropata7me,un7lcolor
changesfrompinktoclear5. Mul7plynumberofdrops7mes506. Controlat200–400ppm(4–8drops)hydroxylalkalinity
• pH–Condensate1. UsepHmeter,controlatpH8.2–8.8
Safety Precautions
• Handlingboilerwatertreatmentchemicals
• Samplingsteamgenera7ngsystems Boilerwatersampling Highpuritysteamsampling
Samplingquillexplana7on Condensatesampling Coolingcoilexplana7onanddiscussion
• Boilerhousesafetyconcerns
• Analy7caltes7ngprecau7ons Reagenthandling Handlingprecau7ons
Review Quiz
• Whydoweworryabouthardness(calciumandmagnesium)intheboiler?
• Whatarethetwowaysthathardnessismanaged(inmakeupandboilerwater)?
• Whateffectdoesoxygenhaveontheboiler?
• Ifmakeupcalciumis1ppm,andtheboilerisrunningat20cyclesofconcentra7on,howmanyppmcalciumisintheboilerwater?
• Whattwopiecesofsafetyequipmentshouldyouhavewhenhandlingchemicals?