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EFFECTIVE BOILER WATER
SYSTEM PROTECTION
Presented by
Paul R. Puckorius
Puckorius & Associates, Inc
December 7, 2010
Presented by Process Heating
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EFFECTIVE BOILER WATER
SYSTEM PROTECTION
Presented by
Paul R. Puckorius
Puckorius & Associates, Inc
December 7, 2010
Presented by Process Heating
THIS WEBINAR WILL
COVER THESE TOPICS
LOW PRESSURE BOILERS- < 900 psi
WHAT WATER QUALITY IS NEEDED
HOW TO PROTECT THE BOILER
WHAT TREATMENTS WORK WELL
WHAT CONTROLS ARE IMPORTANT
HOW TO PROTECT YOUR
BOILER
Feed it Good Quality Water
Maintain Good Water Treatment Control
Handle Varying Steam Demand
Handle Startup and Shut Down Properly
Protect Boiler When it is Layed Up
Objectives of Boiler Water
Treatment Program To Prevent Deposits on Boiler Tubes
To Prevent Corrosion of all Metals in Entire Boiler Cycle
To Produce Good Steam Quality for all Uses at all Times
To Prevent Boiler Tube Failures
To Properly Startup, Shut Down, & Layup Boilers
An Effective Boiler Water
Treatment Program Prevent Deposits on Boiler Surfaces
(causes loss of heat transfer & weakens
metal due to over heating)
Prevent Oxygen Corrosion (causes
pitting of boiler tubes & rust deposits)
Prevent low pH (below 9 will cause
corrosion and produce red water)
Prevent condensate contamination (may
result in iron, copper, & oil into boiler)
Produce Acceptable Steam Quality
WHAT IS GOOD QUALITY
WATER?
Provides Efficient Equipment Operation
Increases Life Expectancy & ROI
Optimizes Water Use and Waste
Cost Effective Programs
Reduces Maintenance and Labor
GOOD QUALITY WATER
DEPENDS UPON
Boiler Pressure
Boiler Operation
Boiler Design
Consistent & Effective Makeup Water
ASME Boiler WaterGuidelinesNo Superheaters & Turbines
Steam Purity 1 ppm Maximum
0-300 psig 301-600 psig
SiO2 <150 <90
T. Alkalinity; ppm <1000 <850
OH Alkalinity; ppm NS NS
Mmho <7000 <5500
ASME Boiler Water GuidelinesFiretube Boilers
1 ppm TDS Maximum Steam Purity
0 to 300 psig
SiO2; ppm <150
T. Alkalinity; ppm <700
OH Alkalinity; ppm NS
Mmho <7000
ASME Boiler Water GuidelinesWatertube Boilers
With Super heaters/ Turbines
SiO2 Total Alk. OH Alk. Mmho
0-300 <150 <350 NS 5400-1100
301-450 <90 <300 NS 4600-900
451-600 <40 <250 NS 3800-800
601-750 <30 <200 NS 1500-300
751-900 <20 <150 NS 1200-200
901-1000 <8 <100 NS 1000-200
1001-1500 <2 NS NS <150
1501-2000 <1 NS NS <80
ABMA Boiler Water Limits
BW TDS Steam TDS TSS FCO
0-300 psig 3500 1.0 15 0.0003
301-450 psig 3000 1.0 10 0.0003
451-600 psig 2500 1.0 8 0/0004
601-750 psig 1000 0.5 3 0.0005
751-900 psig 750 0.5 2 0.0006
901-1000 psig 625 0.5 1 0.0007
1001-1800 psig 100 0.1 1 0.001
1801-2350 psig 50 0.1 1 0.002
2351-2600 psig 25 0.05 1 0.002
2601-2900 psig 15 0.05 1 0.003
TYPICAL BOILER SYSTEM
Boiler
Steam
Uses
Deaerator
Makeup
System
SteamCondensate Makeup
Boiler
Feedwater
Boiler
Feedwater Pump
Losses
Losses
Blowdown
FIRE TUBE BOILER
Firetube Boilers
Heat on Inside of Tubes
Water on Outside of Tubes
Advantages
– Suitable for low pressure operation
– Reliable
– Low Space Requirements
Firetube Boilers
Disadvantages
– Limited pressure; ~300 psig
– Relatively poor steam quality; small
steam release space
WATER TUBE BOILER-TYPE D
Watertube Boilers
Water on Inside of Tubes
Heat in Furnace Surrounding Tubes
Various Types/Designs
– “A” Type
– “O” Type
– “D” Type
– “L” Type
“Unlimited” Pressure
Good Steam Quality
Watertube Boilers
+ Advantages –
-Suitable for High Pressures
-Reliable
-Excellent Steam Quality
+Disadvantages
-Large Space Required
-Requires Very Good Water Quality
-Sensitive to Deposits/Corrosion
PROTECTING BOILER
FROM CORROSION
Boilers are Made of Carbon Steel
Must Form a Protective Coating
Coating is a Form of Iron Oxide
Coating is Called Magnetite
Coating is Black and Hard and Thin
HOW TO FORM MAGNETITE
Remove Oxygen to Zero in Boiler
Raise pH of Boiler Water above 10
Prevent all Deposits on Boiler Surface
Carry a High Hydrate Alkalinity in Boiler
MAGNETITE- WELL PROTECTED BOILER TUBES
DEPOSIT CONTROL
METHODS
Remove Before Boiler- Known as
External Treatment of Makeup Water
Condition Potential Water Deposits in
the Boiler- Known as Internal treatment
of Boiler Water
BOILER WATER DEPOSIT
CONTROL – EXTERNAL
VERY COMMON Sodium Zeolite Softening- removes only
the hardness
Cold /Hot Lime Softening- removes
hardness, some alkalinity, and some
dissolved solids
Demineralizers- removes Everything
Reverse Osmosis- removes Everything
BOILER DEPOSIT CONTROL–
INTERNAL METHOD-
KEEPING DEPOSITS SOLUBLE
Specialty Chemicals such as
Phosphonates, and Polymers- Very
Common in Boilers Operating at <600 psi
Previous Chemicals used were Chelants
such as EDTA and NTA- Not very common
currently due to Corrosion Concerns
BOILER DEPOSIT CONTROL–
INTERNAL METHOD-
KEEPING DEPOSITS SOLUBLE
Often requires low hardness Feed Water
+ Usually less that 2 ppm hardness needed
+ If higher Hardness, Costs for WT higher
Produces a much Cleaner Boiler
+ Due to Solubilized Hardness- no Sludge
+ Maximizes Boiler Heat Transfer
BOILER DEPOSIT CONTROL–
INTERNAL METHOD-
FORMING DEPOSITS (SLUDGE)
Most Common- add Phosphate to Boiler
+ Will form hardness “sludge”
+ Will be removed by Blowdown
Use of Phosphate w/Polymer/Phosphonate
+ Will form some soluble and some “sludge”
+ Will provide a “cleaner” Boiler
Sludge Conditioners & Dispersants
Sludge conditioners allowed sludge to
remain free flowing and accumulate in
bottom drum
Current approaches
– Low feedwater hardness
– Keep precipitated particles dispersed so
they can be removed with surface
blowdown
Naturally Occurring Sludge Conditioners and Dispersants
Tannins
Lignins
Starch
Seaweed derivatives
Sugars
Carboxymethyl cellulose
BOILER DEPOSIT CONTROL–
INTERNAL METHOD-
FORMING DEPOSITS (SLUDGE)
Phosphate Levels 20-40ppm in Boiler
+ Ortho Phosphate can cause deposits in
feed water line
+ Poly Phosphate will not cause deposits in
feed water line
Polymers/ Phosphonates Levels often 10-
30ppm in Boiler
Summary of Phosphate Treatment Programs
PO4 OH- Na:PO4 Ratio pH
Conventional 20-40 100-350 N/A 11 - 12
Coordinated 5-25 Trace 2.85:1 to 3:1 (9 - 10.5)
Congruent 2-5 Zero 2.3:1 to 2.6:1 (8.8 - 9.4)
Equilibrium <2.4 <1.0 N/A (9.3 - 9.6)
Phosphate ProgramsAlternatives Based on Pressure
PSIG 0-300 301-450 450-600 450-600 601-750 751-900
PO4; ppm 30-60 30-60 20-40 5-25 <2.4 <2.4
Mmho 1100-5400 900-4600 800-3800 200-800 <150 <150
TDS; ppm 550-2700 450-2300 400-1900 100-400 <75 <75
OH Alk;
ppm
20-200 6-50 2-20 1-4 0.17-1.0 .17-1.0
pH 11-12 10.5-11.5 10-11 9.7-10.4 9.0-9.7 9.0-9.7
SO3; ppm 20-40 20-40 15-30 10-20 5-10 3-8
SiO2; ppm <150 <90 <40 <8 <2 <2
Polymer 5-10 5-10 3-8 2-5 2-5 1-3
Makeup Soft Soft Soft DI DI DI
BOILER DEPOSIT CAUSES
Loss in Heat Transfer- Wasted Fuel
Possible Gradual Boiler Tube Softening
and Eventual Failure
Corrosion Under Deposits due to
Caustic Concentration
Effect of Overheating Due to Deposits
Long-term Overheating Tube Failure
OXYGEN REMOVAL
METHODS
Mechanical Deareation of Feed Water
+ Various Types Of Equipment using
Heat and Steam
Chemical Oxygen Scavengers
+ Various Types Of Chemicals
Oxygen Pitting
DEAREATOR OPERATION
Maintain Adequate Temperature- This is
at Full Saturation for the Pressure
Maintain Good Agitation- This is to
Obtain Steam & Water Mixing to Strip
Gases from Water
Maintain Proper Steam Plume for
Proper Partial Pressure of Atmosphere
Principles of Deaeration
Heating
Agitation
Adequate Venting
Practical Considerations
90 - 95% of oxygen is removed easily by mechanical separation; the remaining 5 -10% must be removed by molecular diffusion.
Types of O2 Scavengers
Non-Volatile Oxygen Scavengers– Stay in boiler water
» Sodium sulfite most common
» Erythorbic acid (iso ascorbic acid-vitamin C)
» Sodium erythorbate
» Amine neutralized-proprietary
Volatile Oxygen Scavengers– Exit boiler with steam
– Hydrazine most common; also other “hydrazine substitutes”
OXYGEN SCAVENGERS
Sulfite is most Common
Often Sodium Sulfite with Catalyst (Co)
and is a Dry Product
Recently Sodium Bisulfite which is
much more Soluble and thus a liquid but
it is acid and needs more alkali
Common Dosage is 20-40 ppm Sulfite
Volatile Oxygen Scavengers
Hydrazine
Diethylhydroxylamine - DEHA
Carbohydrazide
Hydroquinone
Methylethylketoxime - MEKO
CONDENSATE SYSTEM
CORROSION CONTROL
Need to Prevent Low pH due to Carbon
dioxide
Need to be sure Oxygen is not Present
since will Cause Pitting Corrosion
Carbon Dioxide Gouging
CONDENSATE SYSTEM LOW PH
CORROSION CONTROL Need to Neutralize the Carbonic acid
(carbon dioxide dissolved in water)
Consider using a Dealkalizer if very high
Carbon Dioxide
Use Organic Chemicals known as
Neutralizing Amines
Neutralizing Amine will not protect against
Oxygen corrosion
Dealkalization of Boiler Feedwater
Purpose of alkalinity reduction– Bicarbonates in makeup water decompose in
boiler to produce carbon dioxide
2NaHCO3 + Heat Na2CO3 + CO2 + H2O
Carbon dioxide is carried with steam
– CO2 combines with water to form carbonic acid. Low pH condensate causes acid corrosion of condensate piping
CO2 + H2O H2CO3
H2CO3 H+ + HCO3-
CONDENSATE SYSTEM-
NEUTRALIZING AMINES +Most common are these three amines
+Morpholine/ Cyclohexylamine/ and
Diethylaminoethanol (DEAE)
+Amines are added to the Boiler and the
Steam carries into the Condensate
+These three can be used alone or often
blended to give better system protection-
they condense throughout entire system
DISTRIBUTION RATIO
DEFINED AS THE RATIO OF AMINE REMAINING IN STEAM TO AMINE IN CONDENSATE
AMINE WITH HIGH DISTRIBUTION RATIO STAYS IN STEAM LONGER
AMINE WITH LOW DISTRIBUTION RATIO CONDENSES WITH “EARLY” CONDENSATE
DISTRIBUTION RATIOS OF COMMON AMINES
AMINE DISTRIBUTION RATIO
MORPHOLINE 0.48
CYCLOHEXYLAMINE 2.6
DEAE 1.45
AMP 0.31
AMMONIA 10
METHOXYPROPYLAMINE 1.0
CONDENSATE CORROSION
CONTROL FROM OXYGEN
Need to Prevent any Oxygen Entering
System by stopping any in leakage
If Oxygen continues entering the steam and
in the condensate- Need to use a Filming
Amine to “coat” the condensate pipe
CONDENSATE CORROSION
CONTROL FROM OXYGEN
Filming Amines used are –
+Octadecylamine (ODA)
Filming Amines must be added to the
Steam line- not the boiler
Filming Amines difficult to control dosage
Often both Neutralizing & Filming Amines
are blended together to help each
STEAM QUALITY NEEDS
Need to Identify Steam Uses
If only Heating-Not as critical
If to drive Turbines- Need low Silica in
Boiler Water and No Carryover
If both Heating and Turbines- Need Low
Silica in Boiler Water and No Carryover
BOILER WATER MONITORING Advanced Method-Traces Active Treatment
Automatic Steam Quality & Purity Testing
Continous Conductivity Tests/Blowdown
Numerous Condensate Corrosion Testing
Monitoring “Transport’ of Iron
Automatic Monitoring reduces time for
Manual Testing & Improves Accuracy
Also Phosphate/pH/turbidity, etc
NEW BOILER STARTUP
Need to Implement an Alkaline “Boilout”
Will remove Oil/ Grease/Rust to prevent
Deposits and Over Heating of Tubes
Acid Needed if Much Mill Scale on Tubes
If Acid used, Follow with an Alkaline Boilout
Use of Neutral pH Boilout Treatment may
not be as efficient as Alkaline Boilout
BOILER LAYUP METHODS
Wet Layup needs “full” Boiler, hi pH. Sulfite
Dry Layup needs no moisture and nitrogen
Volatile Vapor Phase Inhibitors used for
both Wet and Dry Layup
TREAT YOUR BOILER WELL
Will Provide Long Life & Good Operation
Will Prevent Poor Quality Steam
Will Save Considerable Energy
Will Reduce Maintenance & Repair
Will Save Manpower Time
You Will Sleep Well
Good Luck with Your Boiler
WHO IS PUCKORIUS & ASSOCIATES, INC?
PROVIDE CONSULTING SERVICES ONLY
DO NOT SELL CHEMICALS OR EQUIPMENT
WORK THROUGHOUT THE WORLD
WORK ON ALL TYPES OF WATER SYSTEMS
PROVIDE TROUBLE SHOOTING, PREPARATION
OF SPECIFICATIONS, TRAINING AND LITIGATION
PROVIDE EVALUATION OF WATER TREATMENT
PROGRAMS AND COST EFFECTIVE
APPLICATIONS
SAVE OUR CLIENTS MANY TIMES OUR FEES
NEED MORE HELP?HOW TO CONTACT US?
Puckorius & Associates, Inc. 6621 West 56th Ave
Suite 200 Arvada, Colorado 80002
Phone-303-674-9897 Fax-303-674-1453
Florida Office- 9005 Lake Lynn Drive Sebring, FL 33876
Phone 863-655-1036
E-mail [email protected]
Web - www.Puckorius.com &
www.watertrainingservices.com
Paul Puckorius cell- 303-638-0587
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