boiler water chemistry
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Boiler water chemistryTRANSCRIPT
Boiler Water ChemistryBoiler Water Chemistry
ByByB.A.ChemmannoorB.A.Chemmannoor
STEAGSTEAG--encotecencotec
Nalco Chemical Co.Nalco Chemical Co.
BoilerBoilerPrePre--Treatment
CondensateCondensateReceiverReceiver
ProcessProcess
ProcessProcess
ProcessProcess
Treatment
BlowdownBlowdownflash tank
Flash Flash tank
Low Low pressure pressure steamsteam
flash tank tank
Major ProblemsMajor Problems
Corrosion Corrosion
ScaleScale
SolubilitiesSolubilitiesCompound ppm as CaCO3
32 oF (0 oC) 212 oF (100 oC)CalciumBicarbonate 1620 decomposesCarbonate 15 13Sulfate 1290 1250
MagnesiumBicarbonate 37,100 decomposesCarbonate 101 75Sulfate 170,000 356,000
SodiumBicarbonate 38,700 decomposesCarbonate 61,400 290,000Chloride 225,000 243,000Hydroxide 370,000 970,000Sulfate 33,600 210,000
Scale Formation MechanismsScale Formation Mechanisms
Precipitation of insoluble hardnessPrecipitation of insoluble hardness
Ca(HCOCa(HCO33 ))22 + HEAT + HEAT ------> CaCO> CaCO33 + H+ H22O + COO + CO22
MgMg+2+2 + OH+ OH-- ------>> MgOHMgOH++
HH22SiOSiO33 ------> H> H++ + HSiO+ HSiO33--
MgOHMgOH++ + HSiO+ HSiO33-- ------> MgSiO> MgSiO33 + H+ H22OO
Exceeding saturation through evaporation, resulting Exceeding saturation through evaporation, resulting in crystallizationin crystallization
egeg. CaSO. CaSO44, SiO, SiO22
Found in Boiler DepositsFound in Boiler DepositsName FormulaAcmite Na2O•Fe2O 3•4SiO 2Analcite Na2O•Al2O 3•4SiO 2•2H2OAnhydrite CaSO 4Aragonite CaCO 3 (gamma form)Basic magnesium phosphate Mg3(PO 4)2•Mg(OH)2Brucite Mg(OH)2Calcium hydroxide Ca(OH)2Calcite CaCO 3 (beta form)Copper CuCuprite Cu2OFerrous oxide FeOGoetnite Fe2O 3 • H2O (alpha form)Gypsum CaSO 4•2 H2OHematite Fe2O 3Hydroxyapatite Ca10(PO 4)6(OH)2Magnetite Fe3O 4Serpentine (magnesium silicate) 3MgO•SiO 2•2 H2OSodium ferrous phosphate NaFePO 4Tenorite CuOThenardite Na2SO 4Xonotlite 5 CaO•5 SiO 2 •H2O
SilicaSilica
Forms deposits in boilers Forms deposits in boilers
Occurs as magnesium silicate orOccurs as magnesium silicate or silicicsilicic acidacid
Selective silica carryoverSelective silica carryover
Cannot be controlled mechanically by steam Cannot be controlled mechanically by steam separatorsseparators
Not usually a problem with boilers with less than Not usually a problem with boilers with less than 600 psig pressure600 psig pressure
Selective Silica CarryoverSelective Silica Carryover
Silica is selectively dissolved into Silica is selectively dissolved into the steamthe steamControlled by limiting the silica Controlled by limiting the silica concentration in the boiler waterconcentration in the boiler waterControlled by limiting boiler Controlled by limiting boiler pressurepressureControlled by maintaining high Controlled by maintaining high pHpH
Forms of Iron ScaleForms of Iron Scale
Iron is usually found in a boiler as one or more of the followinIron is usually found in a boiler as one or more of the following:g:
A complex with calciumA complex with calcium
A complex with phosphateA complex with phosphate
Hematite FeHematite Fe22OO33
Magnetite FeMagnetite Fe33OO44
Effect of Scale on Heat TransferEffect of Scale on Heat Transfer
Effect of Scale on Tube TemperatureEffect of Scale on Tube Temperature
Effect of Scale Effect of Scale -- ExampleExample
Effect of Scale Effect of Scale -- ExampleExample
Temp Drop Across Water Film = 76Temp Drop Across Water Film = 76o o F.F. Max. Tube Temp (1004Max. Tube Temp (1004o o F.) is above allowableF.) is above allowableTemp Drop Across Internal Scale = 362Temp Drop Across Internal Scale = 362ooF.F. Oxidation Temp limit of SAOxidation Temp limit of SA--210 Carbon Steel210 Carbon SteelTemp Drop Across Tube Wall = 66Temp Drop Across Tube Wall = 66o o F.F.Assume CaSOAssume CaSO4 4 scale (0.024”)scale (0.024”)Thermal Conductivity = 10 BTU/ftThermal Conductivity = 10 BTU/ft22--hrhr--o o F/inF/in
Scale ProblemsScale Problems
Boiler tube failureBoiler tube failure
Caused by reduced heat transfer and tube Caused by reduced heat transfer and tube overheatingoverheating
UnderUnder--deposit corrosiondeposit corrosion
Caused by high concentration of corrosive Caused by high concentration of corrosive agents (usuallyagents (usually NaOHNaOH))
Scale PreventionScale Prevention
Precipitation of hardness in the boilerPrecipitation of hardness in the boiler
Reduce amount of hardness entering boilerReduce amount of hardness entering boiler
Keep the hardness solubleKeep the hardness soluble
Coagulation TreatmentsCoagulation Treatments
Principles Principles
Calcium hardness is precipitated as Calcium Calcium hardness is precipitated as Calcium CarbonateCarbonate
Magnesium hardness is precipitated as Magnesium hardness is precipitated as Magnesium Hydroxide or Magnesium Magnesium Hydroxide or Magnesium SilicateSilicate
Coagulation Treatment ApplicationsCoagulation Treatment Applications
A Coagulation Program Can Be Used When: A Coagulation Program Can Be Used When:
Boiler pressure < 350 psigBoiler pressure < 350 psig
FeedwaterFeedwater hardness > 60 ppmhardness > 60 ppm
Boiler alkalinity < 500 ppmBoiler alkalinity < 500 ppm
Coagulation TreatmentsCoagulation TreatmentsAdvantageAdvantage
Can treat very highCan treat very high feedwaterfeedwater hardnesshardness
DisadvantagesDisadvantagesLow cyclesLow cycles
High boiler TDSHigh boiler TDS
HighHigh blowdownblowdown -- wastes heatwastes heat
Scale formation Scale formation
Treatment With Makeup SofteningTreatment With Makeup Softening
Requirements for SuccessRequirements for Success
Proper Operation and Maintenance of MakeProper Operation and Maintenance of Make--up Equipmentup Equipment
Chemical Conditioning for Residual HardnessChemical Conditioning for Residual Hardness
Current Treatment TechnologiesCurrent Treatment Technologies
There are three technologies in common use today:There are three technologies in common use today:
Phosphate residualPhosphate residual
ChelantsChelants
AllAll--polymer treatmentpolymer treatment
Phosphate ResidualPhosphate Residual
ChemistryChemistry
Precipitates calcium as calcium phosphatePrecipitates calcium as calcium phosphate
Precipitates magnesium as magnesium hydroxidePrecipitates magnesium as magnesium hydroxide
Phosphate TechnologyPhosphate TechnologyTypes of PhosphatesTypes of Phosphates
Ortho phosphatesOrtho phosphatesMonoMono--,, didi--, tri, tri-- sodium phosphatessodium phosphates
Poly PhosphatesPoly PhosphatesSodiumSodium hexahexa meta phosphate meta phosphate
SodiumSodium heptahepta meta phosphatemeta phosphate
SodiumSodium tripolytripoly phosphate phosphate
Tetra sodiumTetra sodium pyropyro--phosphatephosphate
Phosphate TechnologyPhosphate Technology
FeedpointsFeedpoints
Ortho phosphateOrtho phosphate
Feed to boiler drum directlyFeed to boiler drum directly
Poly phosphatePoly phosphate
Feed toFeed to feedwaterfeedwater lineline
IfIf feedwaterfeedwater hardness is > 3 ppm, feed both to steam drumhardness is > 3 ppm, feed both to steam drum
Phosphate TechnologyPhosphate Technology
Detailed ChemistryDetailed Chemistry
(poly) Na(poly) Na55PP33OO1010 + 4NaOH + 4NaOH --> 3Na> 3Na33POPO44 + 2H+ 2H22O O
((orthoortho) Na) Na22HPOHPO44 ++ NaOH NaOH --> Na> Na33POPO44 + H+ H22O O
3CaCO3CaCO33 + 2Na+ 2Na33POPO44 --> Ca> Ca33(PO(PO44))22 + 3Na+ 3Na22COCO33
3CaSO3CaSO44 + 2Na+ 2Na33POPO44 --> Ca> Ca33(PO(PO44))22 +3Na+3Na22SOSO44
Mg(HCOMg(HCO33))22 + 4NaOH + 4NaOH --> Mg(OH)> Mg(OH)22 + 2Na+ 2Na22COCO3 3 + 2H+ 2H22O O
MgClMgCl22 + 2NaOH + 2NaOH --> Mg(OH)> Mg(OH)22 + 2NaCl + 2NaCl
Phosphate TechnologyPhosphate TechnologyAdvantagesAdvantages
Easy to monitor and controlEasy to monitor and control
Does not require high purity makeupDoes not require high purity makeup
Can be used at high pressureCan be used at high pressure
Well understoodWell understood
Can be FDA and/or USDA approvedCan be FDA and/or USDA approved
Can handleCan handle feedwaterfeedwater hardness fluctuationshardness fluctuations
Residual POResidual PO44 is non corrosiveis non corrosive
Large POLarge PO44 residual residual -- buffer for excursionsbuffer for excursions
Relatively low cost ingredientsRelatively low cost ingredients
Phosphate TechnologyPhosphate TechnologyDisadvantagesDisadvantages
Produces precipitates in boiler waterProduces precipitates in boiler water
Excess alkalinity can produce corrosionExcess alkalinity can produce corrosion
May require moreMay require more blowdownblowdown
If so, more heat lost, more chemical usedIf so, more heat lost, more chemical used
Possibility of scalingPossibility of scaling
Normally used with sludge dispersantNormally used with sludge dispersant
Sludge ConditioningSludge Conditioning
Insoluble Calcium Phosphate and Magnesium Insoluble Calcium Phosphate and Magnesium Hydroxide solids formed (Sludge)Hydroxide solids formed (Sludge)
Particulate Iron Oxide returned in condensateParticulate Iron Oxide returned in condensate
Solids settle on hot boiler surfacesSolids settle on hot boiler surfaces
Heat transfer impaired, tube failure riskHeat transfer impaired, tube failure risk
Types of Sludge ConditionersTypes of Sludge Conditioners
Synthetic polymersSynthetic polymers
TanninsTannins
LigninsLignins
StarchesStarches
Use of Sludge Conditioners Use of Sludge Conditioners
Starch Organic ProductsStarch Organic Products
When Mg:SiOWhen Mg:SiO22 ratio < 2ratio < 2
When oil contaminates the boilerWhen oil contaminates the boiler
In food processing plantsIn food processing plants
Lignin Organic ProductsLignin Organic Products
To condition Calcium Phosphate & Iron OxideTo condition Calcium Phosphate & Iron Oxide
Feed & Control of Sludge ConditionersFeed & Control of Sludge Conditioners
Feed toFeed to feedwaterfeedwater as far ahead of boiler as possible. preferred as far ahead of boiler as possible. preferred addition points are:addition points are:
Deaerator storageDeaerator storage
BoilerBoiler feedwaterfeedwater lineline
Direct to steam drumDirect to steam drum
PhosphatePhosphate--Polymer ProgramsPolymer Programs
Affects Calcium & Magnesium precipitationAffects Calcium & Magnesium precipitation
Same precipitation chemistry as other phosphate Same precipitation chemistry as other phosphate programs but different dosage requirements for sludge programs but different dosage requirements for sludge conditioner & phosphateconditioner & phosphate
Provides cleaner boilers Provides cleaner boilers
Application of PhosphateApplication of Phosphate--Polymer Polymer ProgramsPrograms
FeedwaterFeedwater hardness less than 3 ppmhardness less than 3 ppm
Softeners or naturally low hardnessSofteners or naturally low hardness
PhosphatePhosphate--Polymer ProgramsPolymer Programs
AdvantageAdvantage
Can provide much cleaner boilers than other Can provide much cleaner boilers than other conventional Phosphate programsconventional Phosphate programs
DisadvantageDisadvantage
Requires much stricter control ofRequires much stricter control of feedwaterfeedwaterhardness and chemical programhardness and chemical program
ChelantsChelants
Act on dissolved metal ionsAct on dissolved metal ions
Create very soluble complexesCreate very soluble complexes
Competing ions (POCompeting ions (PO44, SiO, SiO22, OH) reduce effectiveness, OH) reduce effectiveness
CommonCommon ChelantsChelants
EDTAEDTA((EEthylenethylene ddiamine iamine ttetraceticetracetic aacid)cid)
Has 6 metalHas 6 metal complexingcomplexing sites which sites which include nitrogen and oxygen atomsinclude nitrogen and oxygen atoms
NTANTA((NNitrilo itrilo ttriaceticriacetic aacid)cid)
Has 4 metalHas 4 metal complexingcomplexing sitessites
Comparison ofComparison of ChelantsChelants
NTA is more thermally stable NTA is more thermally stable –– 900 psig max. for NTA,900 psig max. for NTA,–– 600 psig max. for EDTA600 psig max. for EDTA
NTA has lower cost than EDTANTA has lower cost than EDTA
EDTAEDTA chelateschelates Magnesium better than NTAMagnesium better than NTA
EDTAEDTA chelateschelates ferrous iron better than NTAferrous iron better than NTA
EDTA has full FDA approvalEDTA has full FDA approval
Application ofApplication of ChelantsChelants
Must be fed continuously toMust be fed continuously to feedwaterfeedwater using a using a stainless steel injection quill & pipingstainless steel injection quill & piping
Oxygen must be absentOxygen must be absent
Residual concentration must be kept below 10 Residual concentration must be kept below 10 ppm as CaCOppm as CaCO33 in boiler water to minimize in boiler water to minimize corrosioncorrosion
Accurate feed control is requiredAccurate feed control is required
ChelantChelant Control RangesControl Ranges
Boiler PressureBoiler Pressure ChelantChelant Residual Residual psigpsig (Bar)(Bar) ppm as CaCOppm as CaCO33
400400 (30)(30) 4 4 -- 88
401 401 -- 600 600 (30 (30 -- 40)40) 3 3 -- 66
601 601 -- 10001000 (40 (40 -- 70)70) 3 3 -- 55
ChelantChelant AdvantagesAdvantages
No precipitates formedNo precipitates formed
Heat transfer surfaces cleanerHeat transfer surfaces cleaner
Less frequent acid cleaningLess frequent acid cleaning
Can sometimes reduceCan sometimes reduce blowdownblowdown
ChelantChelant DisadvantagesDisadvantages
Cost more than phosphatesCost more than phosphates
Require stricter control ofRequire stricter control of feedwaterfeedwater qualityquality
More difficult control testMore difficult control test
Excessive residuals are corrosiveExcessive residuals are corrosive
Competing ions can form depositsCompeting ions can form deposits
AllAll--Organic Polymer ProgramsOrganic Polymer Programs
AllAll--polymer program, polymeric blendpolymer program, polymeric blend
Contains noContains no chelantschelants or phosphates, does not require or phosphates, does not require supplemental dispersants supplemental dispersants
Functions byFunctions by solubilizationsolubilization for Calcium and Magnesium for Calcium and Magnesium and byand by dispersancydispersancy for iron and other particulatesfor iron and other particulates
NonNon--aggressive to boiler metalsaggressive to boiler metals
AllAll--Organic Polymer ProgramsOrganic Polymer Programs
Feed to deaerator storage for boilers at < 600 psig and Feed to deaerator storage for boilers at < 600 psig and using softened waterusing softened water
Use other feed points for high pressure boilers using Use other feed points for high pressure boilers using high purity (e.g. high purity (e.g. demineralizeddemineralized) makeup) makeup
Feed program based on statistical upper control limit Feed program based on statistical upper control limit for hardness and iron, not average valuesfor hardness and iron, not average values
Under dosing (<20% of requirement) can produce Under dosing (<20% of requirement) can produce CalciumCalcium AcrylateAcrylate deposits in boilerdeposits in boiler
AllAll--Organic Polymer ProgramsOrganic Polymer Programs
Non corrosive to boiler internalsNon corrosive to boiler internals
Offers clean boilers Offers clean boilers -- enhanced heat transferenhanced heat transfer
Transports 100% of hardnessTransports 100% of hardness
NonNon--volatile volatile -- safe for turbinessafe for turbines
Can test for boiler hardnessCan test for boiler hardness
Simple product test Simple product test -- easy to test for producteasy to test for product
GoodGood passivatingpassivating programprogram
AllAll--Organic Polymer ProgramsOrganic Polymer Programs
Limited to boiler pressures <1000 psigLimited to boiler pressures <1000 psig
Requires low hardnessRequires low hardness feedwaterfeedwater
Some formulations contribute ammonia to steamSome formulations contribute ammonia to steam
Cannot be used as a cleanCannot be used as a clean--up programup program
Boiler CorrosionBoiler Corrosion
Types of CorrosionTypes of Corrosion
Oxygen corrosionOxygen corrosion
Alkalinity concentrationAlkalinity concentration
Caustic corrosionCaustic corrosion
Acid corrosionAcid corrosion
ChelantChelant corrosioncorrosion
Erosion/CorrosionErosion/Corrosion
Oxygen CorrosionOxygen Corrosion
Can be found throughout the systemCan be found throughout the system
Mechanism same as other oxygen corrosion cellsMechanism same as other oxygen corrosion cells
Corrosion mechanisms affected by:Corrosion mechanisms affected by:
–– Oxygen concentrationOxygen concentration
–– TemperatureTemperature
–– pHpH
Boiler MetalBoiler Metal PassivationPassivation
Reduces general corrosionReduces general corrosion
Forms protective barrier on metalForms protective barrier on metal
Black magnetite film Black magnetite film -- FeFe33OO44
Difficult to quantify resultsDifficult to quantify results
BoilerBoiler PassivationPassivation MechanismsMechanisms
Reaction of Water With Boiler Metal:Reaction of Water With Boiler Metal:
Fe + 2 HFe + 2 H22O O --> Fe(OH)> Fe(OH)22 + H+ H22
3Fe(OH)3Fe(OH)22 --> Fe> Fe33OO4 4 + H+ H2 2 + 2H+ 2H22OO
Rate of Magnetite Formation Is:Rate of Magnetite Formation Is:
Temperature dependentTemperature dependent
Spontaneous above 180Spontaneous above 180 ooCC
Effect of pH on Boiler CorrosionEffect of pH on Boiler Corrosion
Types of Caustic Damage in BoilersTypes of Caustic Damage in Boilers
There are two forms of damage caused by caustic soda There are two forms of damage caused by caustic soda
to high pressure boilers, namely:to high pressure boilers, namely:
Caustic corrosionCaustic corrosion
Caustic embrittlementCaustic embrittlement
Caustic CorrosionCaustic CorrosionUsually found only in high pressure boilersUsually found only in high pressure boilers
Problem usually due to depositsProblem usually due to deposits
Localized in boilerLocalized in boiler
Also called crater attack or caustic gougingAlso called crater attack or caustic gouging
No embrittlement of metalNo embrittlement of metal
Requirements for Caustic CorrosionRequirements for Caustic Corrosion
Two conditions are necessary for caustic corrosion to occur:Two conditions are necessary for caustic corrosion to occur:
The presence of a corrosive material in the boiler water The presence of a corrosive material in the boiler water (caustic soda)(caustic soda)
A mechanism for concentrating this materialA mechanism for concentrating this material
Concentrating MechanismsConcentrating MechanismsThe following conditions can result in dangerously The following conditions can result in dangerously high localized caustic soda concentrationshigh localized caustic soda concentrations
Porous metal oxide depositsPorous metal oxide deposits
Metal oxide depositsMetal oxide deposits
Operation above rated capacityOperation above rated capacity
Excessive rate of load increase Excessive rate of load increase
Excessive localized heat inputExcessive localized heat input
Localized pressure differentialsLocalized pressure differentials
Restrictions in generating tube(s)Restrictions in generating tube(s)
Prevention of Caustic CorrosionPrevention of Caustic Corrosion
Prevention of caustic corrosion is achieved by minimizing Prevention of caustic corrosion is achieved by minimizing or eliminating the presence of ‘free’ caustic soda in the or eliminating the presence of ‘free’ caustic soda in the boiler water.boiler water.
Coordinated phosphate Coordinated phosphate
Congruent sodium phosphate Congruent sodium phosphate
PhosphatePhosphate--low hydroxide (trilow hydroxide (tri--ad)ad)
Equilibrium phosphate controlEquilibrium phosphate control
AllAll--volatile treatmentvolatile treatment
Coordinated PhosphateCoordinated PhosphateControl of pH comes from hydrolysis ofControl of pH comes from hydrolysis of trisodiumtrisodium phosphate in phosphate in waterwater
NaNa33POPO44 + H+ H22O O --> Na> Na22HPOHPO44 ++ NaOHNaOH
Molar ratio of sodium : phosphate is 3 : 1 in waterMolar ratio of sodium : phosphate is 3 : 1 in water
FeedwaterFeedwater contamination usually dictates causticcontamination usually dictates caustic--consuming consuming chemicals, such aschemicals, such as disodiumdisodium andand trisodiumtrisodium phosphatephosphate
Does not ensure absence of caustic under concentrating Does not ensure absence of caustic under concentrating conditionsconditions
Nalco Chemical Co.Nalco Chemical Co.
Coordinated pH/ PhosphateCoordinated pH/ PhosphateControl LimitsControl Limits
Congruent ControlCongruent Control
This program was developed to prevent free caustic in This program was developed to prevent free caustic in boiler water during concentrating conditionsboiler water during concentrating conditions
At sodium:phosphate ratio of 2.85 in boiler water, At sodium:phosphate ratio of 2.85 in boiler water, precipitated solids have same concentrationprecipitated solids have same concentration
Safe range is between ratio 2.3 Safe range is between ratio 2.3 -- 2.62.6
Control is based on pH and POControl is based on pH and PO44 valuesvalues
TriTri--Ad ProgramsAd Programs
Boiler water contains low level of caustic sodaBoiler water contains low level of caustic soda
Also called ‘Also called ‘PRECISION CONTROLPRECISION CONTROL’’
Useful when traces of hardness inUseful when traces of hardness in feedwaterfeedwater
Greater risk of caustic corrosionGreater risk of caustic corrosion
Not for high heat flux boilersNot for high heat flux boilers
Not for pressure greater than 1800 psigNot for pressure greater than 1800 psig
Equilibrium TreatmentEquilibrium TreatmentCoordinated and congruent treatments can be difficult Coordinated and congruent treatments can be difficult to controlto control
Phosphate hideout interferesPhosphate hideout interferes
POPO44 levels kept between 1 levels kept between 1 -- 5 ppm5 ppm
Controlled by pH, OH and POControlled by pH, OH and PO44 in boiler waterin boiler water
Phosphate HideoutPhosphate Hideout
Shows as drop in boiler water phosphate under high loadShows as drop in boiler water phosphate under high load
Under concentrating condition, phosphate precipitates from Under concentrating condition, phosphate precipitates from boiler waterboiler water
Further addition of chemical to compensate can cause increased Further addition of chemical to compensate can cause increased depositiondeposition
Can cause localized corrosionCan cause localized corrosion
Phenomenon reverses when heat load dropsPhenomenon reverses when heat load drops
AllAll--Volatile TreatmentVolatile Treatment
Creates a nonCreates a non--corrosive pH without adding dissolved solidscorrosive pH without adding dissolved solids
Can be used at pressures above 600 psigCan be used at pressures above 600 psig
Useful in boilers with severe phosphate hideoutUseful in boilers with severe phosphate hideout
Has no buffering forHas no buffering for feedwaterfeedwater contaminationcontamination
Useful whenUseful when ultrapureultrapure steam is neededsteam is needed
Caustic EmbrittlementCaustic Embrittlement
Should not be confused with caustic corrosionShould not be confused with caustic corrosion
Embrittlement is a special form of stress corrosion crackingEmbrittlement is a special form of stress corrosion cracking
Three conditions must be presentThree conditions must be present–– Concentrating mechanism presentConcentrating mechanism present–– Metal under high stressMetal under high stress–– Must contain silicaMust contain silica
Inhibited by improved fabrication techniques and by organic Inhibited by improved fabrication techniques and by organic and nitrateand nitrate--based inhibitorsbased inhibitors
Other Causes of Boiler CorrosionOther Causes of Boiler Corrosion
FeedwaterFeedwater acid contaminationacid contamination
Surface condenser leaksSurface condenser leaks
Acid leaks fromAcid leaks from demineralizerdemineralizer
Organic materialsOrganic materials
ChelantChelant corrosioncorrosion