CW treatment

1. EssentialEssential
Cooling TowerCooling Tower
TreatmentTreatment

2. Why Treat The Water?Why Treat The Water?
•To Control CorrosionTo Control Corrosion
•To Prevent ScaleTo Prevent Scale
•To Control Algae and Bacterial GrowthTo Control Algae and Bacterial Growth
•To extend equipment life and efficiencyTo extend equipment life and efficiency

3. What’s Wrong with Water?What’s Wrong with Water?
•Water is a natural solvent, it dissolves thing.Water is a natural solvent, it dissolves thing.
•Natural waters contain significant amounts ofNatural waters contain significant amounts of
minerals like calcium and magnesium.minerals like calcium and magnesium.
•Natural waters typically contain significant amountsNatural waters typically contain significant amounts
of oxygen.of oxygen.
•Water, particularly warm water, is a greatWater, particularly warm water, is a great
environment for living micro-organismenvironment for living micro-organism

4. What are Solids?What are Solids?
•Any material that is or becomes dissolved in waterAny material that is or becomes dissolved in water
is referred to as a dissolved solid, oris referred to as a dissolved solid, or solidssolids..
Common DissolvedCommon Dissolved
SolidsSolids
•Calcium and MagnesiumCalcium and Magnesium
Salts, akaSalts, aka HardnessHardness
•IronIron
•CopperCopper
•SulfatesSulfates
•PhosphatesPhosphates
•Silica and SilicatesSilica and Silicates

5. More about SolidsMore about Solids
Typical Conductivity in parts of Missouri,Typical Conductivity in parts of Missouri,
Arkansas and KansasArkansas and Kansas
The measure of all of the solids in a sample ofThe measure of all of the solids in a sample of
water is its Conductivitywater is its Conductivity..
St. LouisSt. Louis 430 micro Siemens430 micro Siemens
KCMOKCMO 480480
Little RockLittle Rock 440440
St. JoeSt. Joe 700700
ColumbiaColumbia 480480
LenexaLenexa 530530
Cape GirardeauCape Girardeau 500500
JonesboroJonesboro 540540
Another name for ConductivityAnother name for Conductivity
isis Total Dissolved SolidsTotal Dissolved Solids. Both. Both
are a measure of total mineralare a measure of total mineral
content, but they differ in units.content, but they differ in units.
TDS is expressed in parts perTDS is expressed in parts per
million and Conductivity ismillion and Conductivity is
expressed in micro Siemensexpressed in micro Siemens

6. Not All Solids Are AlikeNot All Solids Are Alike
Some solids are more problematic than others. Two of the most importantSome solids are more problematic than others. Two of the most important
solids in water treatment aresolids in water treatment are Calcium Carbonate and MagnesiumCalcium Carbonate and Magnesium
CarbonateCarbonate, aka, aka HardnessHardness
HardnessHardness
•Is naturally occurring in most all watersIs naturally occurring in most all waters
•Account of nearly 40% of the Conductivity in naturalAccount of nearly 40% of the Conductivity in natural
waters in the Midwestwaters in the Midwest
•Is the primary component of white scale depositsIs the primary component of white scale deposits
•Becomes less soluble as water gets hotterBecomes less soluble as water gets hotter

7. Cycles of ConcentrationCycles of Concentration
1 Cycle1 Cycle
When water evaporates is leaves it solids behind. If you completelyWhen water evaporates is leaves it solids behind. If you completely
evaporate a sample of water and then refill the container with the sameevaporate a sample of water and then refill the container with the same
water the mineral content doubles. This is calledwater the mineral content doubles. This is called Cycling UpCycling Up..

8. More on CyclesMore on Cycles
When water evaporates is leaves it solids behind. If you completelyWhen water evaporates is leaves it solids behind. If you completely
evaporate a sample of water and then refill the container with the sameevaporate a sample of water and then refill the container with the same
water the mineral content doubles. This is calledwater the mineral content doubles. This is called Cycling UpCycling Up..
As cycles increase the amount of solidsAs cycles increase the amount of solids
increaseincrease..
This means:This means:
•The Conductivity increases.The Conductivity increases.
•The total hardness increasesThe total hardness increases
•The pH will go up as the alkalinity increasesThe pH will go up as the alkalinity increases
•The risk of scale formation increasesThe risk of scale formation increases

9. Still More on CyclesStill More on Cycles
In a cooling tower system, evaporation is the main means to removeIn a cooling tower system, evaporation is the main means to remove
heat. This evaporation causes the water toheat. This evaporation causes the water to cycle upcycle up, or increase in, or increase in
mineral content.mineral content.
The cycles of concentration in a cooling tower systemThe cycles of concentration in a cooling tower system
are limited via bleed-off. The cycles limit is based on:are limited via bleed-off. The cycles limit is based on:
•The Conductivity of the makeup waterThe Conductivity of the makeup water
•The Total Hardness of the makeup waterThe Total Hardness of the makeup water
•The Total Alkalinity (pH) of the makeup waterThe Total Alkalinity (pH) of the makeup water
•The heat load or temperature differential of the systemThe heat load or temperature differential of the system
•The type of water treatment chemistry usedThe type of water treatment chemistry used

10. Bleed Off is the removal of high Conductivity water in favor of lowBleed Off is the removal of high Conductivity water in favor of low
Conductivity makeup. Bleed off generally based on TDS or Conductivity.Conductivity makeup. Bleed off generally based on TDS or Conductivity.
This is because the maximum hardness or alkalinity of a given water isThis is because the maximum hardness or alkalinity of a given water is
relative to its Conductivity.relative to its Conductivity.
Bleed OffBleed Off
A Conductivity Controller and a Bleed Valve are generallyA Conductivity Controller and a Bleed Valve are generally
used to control cycles. It follows this process:used to control cycles. It follows this process:
•Sensor continuously measures the Conductivity of the tower water.Sensor continuously measures the Conductivity of the tower water.
•If the Conductivity is higher than the maximum, the bleed valve is opened.If the Conductivity is higher than the maximum, the bleed valve is opened.
•Bleed off removes high Conductivity water and forces the system toBleed off removes high Conductivity water and forces the system to
makeup low Conductivity raw water.makeup low Conductivity raw water.
•Bleed off continues as it dilutes the Conductivity is the system, until the setBleed off continues as it dilutes the Conductivity is the system, until the set
point is satisfied.point is satisfied.

11. ScaleScale
Scale is the formation of mineral deposits. It can occur in anyScale is the formation of mineral deposits. It can occur in any
area that experiences heat transfer or evaporation. Solidsarea that experiences heat transfer or evaporation. Solids
precipitate when they reach the limit of their solubility; whenprecipitate when they reach the limit of their solubility; when
there is more of a solid than the water can keep dissolvedthere is more of a solid than the water can keep dissolved
Common ScalesCommon Scales
•Calcium / Magnesium Carbonate - Lime ScaleCalcium / Magnesium Carbonate - Lime Scale
•Calcium / Magnesium PhosphateCalcium / Magnesium Phosphate
•Calcium / Magnesium SulfateCalcium / Magnesium Sulfate
•Calcium / Magnesium SilicateCalcium / Magnesium Silicate
•SilicaSilica

12. UnderstandingUnderstanding
Scale ControlScale Control
Scale Control works by changing the scaling solids to moreScale Control works by changing the scaling solids to more
soluble solids, using water treatment chemistrysoluble solids, using water treatment chemistry
Assuming that the Conductivity is under control, scaleAssuming that the Conductivity is under control, scale
can be prevented by:can be prevented by:
Converting calcium carbonate to more soluble calciumConverting calcium carbonate to more soluble calcium
phosphates and phosphonatesphosphates and phosphonates
Keeping calcium phosphates part or “dispersed” throughKeeping calcium phosphates part or “dispersed” through
the use of polymersthe use of polymers
Keeping calcium carbonate dispersedKeeping calcium carbonate dispersed
Keeping the pH and alkalinity in checkKeeping the pH and alkalinity in check

13. Key Points ofKey Points of
Scale ControlScale Control
Scale Control Hinges on a Few Key IssuesScale Control Hinges on a Few Key Issues
Understanding the mineral content of theUnderstanding the mineral content of the
raw waterraw water
Proper and complete Bleed OffProper and complete Bleed Off
Maintaining system water alkalinity in “ScaleMaintaining system water alkalinity in “Scale
Safe” zoneSafe” zone
Consistent addition of scale inhibitorsConsistent addition of scale inhibitors
Consistent addition of scale dispersantsConsistent addition of scale dispersants

14. Corrosion BasicsCorrosion Basics
Corrosion is the deterioration of a metal due toCorrosion is the deterioration of a metal due to
interaction with its environment. Corrosion requiresinteraction with its environment. Corrosion requires
metal, oxygen and water.metal, oxygen and water.
In cooling tower systems, the water contains significant amounts ofIn cooling tower systems, the water contains significant amounts of
air. The oxygen carried by that air reacts with the metal at theair. The oxygen carried by that air reacts with the metal at the
surface and starts a corrosion cell.surface and starts a corrosion cell.
IronIron
WaterWater
oxygenoxygen
The key toThe key to
preventing this ispreventing this is
keeping the oxygenkeeping the oxygen
from interacting withfrom interacting with
with metal.with metal.

15. Corrosion ControlCorrosion Control
Since we can’t remove the oxygen from the tower water,Since we can’t remove the oxygen from the tower water,
we must create a barrier between the metal and the waterwe must create a barrier between the metal and the water
and oxygen.and oxygen.
IronIron
WaterWater
oxygenoxygen
The protective layerThe protective layer
is thin and can beis thin and can be
very delicate.very delicate.
There are three basic kinds of barriersThere are three basic kinds of barriers
•PassivePassive
•PrecipitatedPrecipitated
•Film FormingFilm Forming

16. More on Corrosion ControlMore on Corrosion Control
The protective barrier prevents the oxygen fromThe protective barrier prevents the oxygen from
contacting the metal. Thereby preventing corrosion.contacting the metal. Thereby preventing corrosion.
Common CorrosionCommon Corrosion
InhibitorsInhibitors
•MolybdateMolybdate
•PhosphatePhosphate
•PhosphonatePhosphonate
•ZincZinc
•AzolesAzoles
•NitriteNitrite
A combination ofA combination of
inhibitors is usually theinhibitors is usually the
best approachbest approach

17. Crevice and UnderdepositCrevice and Underdeposit
CorrosionCorrosion
When the metal is trapped under dirt, debris or scale it does not haveWhen the metal is trapped under dirt, debris or scale it does not have
normal access to corrosion inhibitors and the bulk water. This sets up anormal access to corrosion inhibitors and the bulk water. This sets up a
specially recognized corrosion cell. Generally, chemical treatment doesspecially recognized corrosion cell. Generally, chemical treatment does
not prevent or cure these corrosion issues.not prevent or cure these corrosion issues.
Hot Spots for Crevice and Underdeposit CorrosionHot Spots for Crevice and Underdeposit Corrosion
Under dirt collected in the sump of the tower or on tube sheetUnder dirt collected in the sump of the tower or on tube sheet
Leaking threadsLeaking threads
Good and bad weld jointsGood and bad weld joints
Under epoxy coatingsUnder epoxy coatings
Under seals and gasketsUnder seals and gaskets

18. Other Issues in CorrosionOther Issues in Corrosion
Aside from general corrosion, as previously described,Aside from general corrosion, as previously described,
there are other forms of corrosion that are equallythere are other forms of corrosion that are equally
important.important.
Other Forms of CorrosionOther Forms of Corrosion
Galvanic - Corrosion betweenGalvanic - Corrosion between
dissimilar or incompatible metalsdissimilar or incompatible metals
Stress Crack - Corrosion causedStress Crack - Corrosion caused
by mechanical stress such asby mechanical stress such as
vibrationvibration
Flow Related - Cativation, andFlow Related - Cativation, and
erosionerosion
None of these formsNone of these forms
of corrosion can beof corrosion can be
controled chemicallycontroled chemically

19. Essential Cooling Tower TreatmentEssential Cooling Tower Treatment
Good Tower TreatmentGood Tower Treatment
Starts with :Starts with :
Good Conductivity ControlGood Conductivity Control
Proper selection of treatmentProper selection of treatment
chemicals based on makeupchemicals based on makeup
water and operatingwater and operating
conditionsconditions
Consistent Chemical LevelsConsistent Chemical Levels
for Maximum Protectionfor Maximum Protection
Consistent and timelyConsistent and timely
monitoring of the watermonitoring of the water
chemistrychemistry
Good Tower TreatmentGood Tower Treatment
Ends with :Ends with :
Clean condenser tubesClean condenser tubes
Good heat transferGood heat transfer
Minimized corrosion ofMinimized corrosion of
piping and surfacespiping and surfaces
Extended equipment lifeExtended equipment life
Annual PM, and CleaningAnnual PM, and Cleaning

20. Boiler Standby / Summer StorageBoiler Standby / Summer Storage

21. Proper Boiler Standby Storage IsProper Boiler Standby Storage Is
•Essential for the Longevity of the BoilerEssential for the Longevity of the Boiler
•Prevention of Corrosion during offline periodsPrevention of Corrosion during offline periods
•Preventative Maintenance, but Low MaintenancePreventative Maintenance, but Low Maintenance
•On going during standbyOn going during standby

22. Proper Boiler Standby Storage IsProper Boiler Standby Storage Is
NOTNOT
•Shutting off the boiler at the end of winterShutting off the boiler at the end of winter
•Draining the boilerDraining the boiler
•Something that is forgotten once startedSomething that is forgotten once started
•Costly or Time ConsumingCostly or Time Consuming

23. • Reduce treatment levels and blowdown heavily 2 days priorReduce treatment levels and blowdown heavily 2 days prior
• Increase bottom blowdown to remove mudIncrease bottom blowdown to remove mud
• Cool and drain, then wash down and refill (optional)Cool and drain, then wash down and refill (optional)
• Fill boiler to headerFill boiler to header
• Add oxygen scavenger, phosphate and alkalinity boosterAdd oxygen scavenger, phosphate and alkalinity booster
• Fire boiler at low fire until steam begins to formFire boiler at low fire until steam begins to form
• Close headerClose header
• Low fire boiler every 4 to 6 weeks to keep chemicals mixed and activeLow fire boiler every 4 to 6 weeks to keep chemicals mixed and active
Wet StorageWet Storage
the Techniquethe Technique
Wet StorageWet Storage
the Techniquethe Technique

24. Dry StorageDry Storage
the Techniquethe Technique
• Reduce treatment levels and blowdown heavily 2 days priorReduce treatment levels and blowdown heavily 2 days prior
• Increase bottom blowdown to remove mudIncrease bottom blowdown to remove mud
• Cool and drain, then wash downCool and drain, then wash down
• Open all drain plugs and inspection portsOpen all drain plugs and inspection ports
• Close heater and feedwater valvesClose heater and feedwater valves
• Using a fan circulate air through boiler to completely dryUsing a fan circulate air through boiler to completely dry
• Place trays of desiccate at 10# per 1000 gallons of volumePlace trays of desiccate at 10# per 1000 gallons of volume
• Seal all drain plugs and inspection portsSeal all drain plugs and inspection ports