Water Chemistry in Steam Generators:Opportunities for Investigation

IAPWS Workshop – Canadian National Committee 11 May 2009

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Who Is B&W

Supercritical Boilers

Baghouses

Wet Scrubbers

Pulp & Paper

Renewables

Small Industrial Boilers

Subcritical Boilers

Nuclear Steam Generators

Dry Scrubbers

SCR Systems

Replacement Parts

Auxiliary Equipment

Construction

Electric Utilities

Nuclear Services

Customers• Utility Companies• Industries• Pulp & Paper Mills

Original Equipment• Supercritical Boilers• Subcritical Boilers• Small Industrial “Package” Boilers• Nuclear Steam Generators• Environmental Equipment

• Baghouses/Fabric Filters• Particulate Control Systems

• Wet/Dry SO2 Scrubbers

• Selective Catalytic NOx Reduction (SCR)

Aftermarket Products/Services• Construction• Replacement Parts• Plant Upgrades• Manufacturing

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We Wrote The Book… We Wrote The Book… Steam: Its Generation and UseSteam: Its Generation and Use

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History of Babcock & Wilcox in Canada

1844 Small foundry starts in Cambridge, Ontario

1859 John Goldie and Hugh McCulloch purchase foundry

1923 Goldie and McCulloch amalgamate with B&W

1963 B&W becomes sole owner

1978 McDermott International, Inc. purchases B&W

1999 Last major plant expansion

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Opportunities in Steam Generation

Schematic - NuclearSteam Generator

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Opportunities in Steam Generation

Stress Corrosion Cracking Intergranular Attack

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Opportunities in Steam Generation

Schematic - Utility RadiantBoiler

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Opportunities in Steam Generation

Schematic - Oil & Gas FiredIndustrialBoiler

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Opportunities in Steam Generation

Long Term Overheat/Creep

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Opportunities in Steam Generation

Long Term Overheat/Creep

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Opportunities in Steam Generation

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Opportunities in Steam Generation

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Opportunities in Steam Generation

Steam Generator Water Treatment Initiatives

Nuclear Steam Generation• All volatile treatment (AVT)• Advanced amines for pH control• Polymer dispersants for deposition control

Thermal Steam Generation• Congruent phosphate treatment• Reducing AVT• Equilibrium phosphate• Polymer dispersants/• Oxygenated treatment (OT)

Few Initiatives over the Last 10-Years

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Opportunities in Steam Generation

Deposition/Fouling Research Needs

Oxide Growth/Corrosion Product Generation (CPG)Corrosion Product Transport (CPT)

• Filterable/Non-filterable materials• Sampling

Steam Generator (Boiler) Fouling (SGF)• Systematic study of variables• Hard collars versus loose sludge• Influence of silica (slippage through water treatment plant/role in

deposition, etc.)

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Opportunities in Steam Generation

Example of a Hard Collar

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Opportunities in Steam Generation

Variables to be Considered in Deposition Studies

Heat FluxFluid VelocityParticle ConcentrationFilterable/Non-Filterable MaterialsChemical Treatment and ImpuritiesSurface RoughnessFlowParticle Size DistributionTemperature

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Opportunities in Steam Generation

Oxide Formation/Dissolution/Exfoliation

Oxide on Austenitic Material

Supercritical Conditions

Oxide on Austenitic Material

Supercritical Conditions

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Opportunities in Steam Generation

Oxide formation in steam generator environment

Oxides on Alloy 690 after exposure in AVT water (a) and AVT water+830ppm SO4 (b) for 1000 hr at 282C

(a) (b)

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Opportunities in Steam Generation

Role/Nature of Organics

Boiler Tolerance for Individual Organic CompoundsEffects on Deposition Process

• Deposit enhancers• Deposit inhibitors• Resulting deposit morphology

Thermal Stability/Decomposition Products• Nature of decomposition products• Steam partitioning

Effects on Boiler Performance• Effects on nucleate boiling• Foaming characteristics

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Opportunities in Steam Generation

Boiler Carryover in a Superheater Tube

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Opportunities in Steam Generation

Integrated Exposure/Crevice Chemistry

Integrated Exposure Concept• Relative assessment of impurities collecting in crevices• Being used on a relatively simplistic basis at many plants• Improved correlations would be useful

CPG/CPT/SGFRole of OrganicsSteam PartitioningExamine/Improve Crevice Chemistry Predictive Codes

• EPRI MULTEQ• AECL ChemSolv™