1. Essential Cooling Tower Treatment

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

3. 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 of minerals like calcium and magnesium.Natural waters contain significant amounts of minerals like calcium and magnesium. Natural waters typically contain significant amounts of oxygen.Natural waters typically contain significant amounts of oxygen. Water, particularly warm water, is a great environment for living micro-organismWater, particularly warm water, is a great environment for living micro-organism

4. What are Solids? Any material that is or becomes dissolved in water is referred to as a dissolved solid, or solids.Any material that is or becomes dissolved in water is referred to as a dissolved solid, or solids. Common Dissolved Solids Calcium and Magnesium Salts, aka HardnessCalcium and Magnesium Salts, aka Hardness IronIron CopperCopper SulfatesSulfates PhosphatesPhosphates Silica and SilicatesSilica and Silicates

5. More about Solids Typical Conductivity in parts of Missouri, Arkansas and Kansas The measure of all of the solids in a sample of water is its Conductivity. St. Louis 430 micro Siemens KCMO480 Little Rock 440 St. Joe 700 Columbia480 Lenexa530 Cape Girardeau 500 Jonesboro540 Another name for Conductivity is Total Dissolved Solids. Both are a measure of total mineral content, but they differ in units. TDS is expressed in parts per million and Conductivity is expressed in micro Siemens

6. Not All Solids Are Alike Some solids are more problematic than others. Two of the most important solids in water treatment are Calcium Carbonate and Magnesium Carbonate, aka Hardness Hardness Is naturally occurring in most all watersIs naturally occurring in most all waters Account of nearly 40% of the Conductivity in natural waters in the MidwestAccount of nearly 40% of the Conductivity in natural waters 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 Concentration 1 Cycle When water evaporates is leaves it solids behind. If you completely evaporate a sample of water and then refill the container with the same water the mineral content doubles. This is called Cycling Up.

8. More on Cycles When water evaporates is leaves it solids behind. If you completely evaporate a sample of water and then refill the container with the same water the mineral content doubles. This is called Cycling Up. As cycles increase the amount of solids increase. 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 Cycles In a cooling tower system, evaporation is the main means to remove heat. This evaporation causes the water to cycle up, or increase in mineral content. The cycles of concentration in a cooling tower system 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 low Conductivity makeup. Bleed off generally based on TDS or Conductivity. This is because the maximum hardness or alkalinity of a given water is relative to its Conductivity. Bleed Off A Conductivity Controller and a Bleed Valve are generally 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 to makeup low Conductivity raw water.Bleed off removes high Conductivity water and forces the system to makeup low Conductivity raw water. Bleed off continues as it dilutes the Conductivity is the system, until the set point is satisfied.Bleed off continues as it dilutes the Conductivity is the system, until the set point is satisfied.

11. Scale Scale is the formation of mineral deposits. It can occur in any area that experiences heat transfer or evaporation. Solids precipitate when they reach the limit of their solubility; when there is more of a solid than the water can keep dissolved Common 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. Understanding Scale Control Scale Control works by changing the scaling solids to more soluble solids, using water treatment chemistry Assuming that the Conductivity is under control, scale can be prevented by: Converting calcium carbonate to more soluble calcium phosphates and phosphonates Converting calcium carbonate to more soluble calcium phosphates and phosphonates Keeping calcium phosphates part or “dispersed” through the use of polymers Keeping calcium phosphates part or “dispersed” through the use of polymers Keeping calcium carbonate dispersed Keeping calcium carbonate dispersed Keeping the pH and alkalinity in check Keeping the pH and alkalinity in check

13. Key Points of Scale Control Scale Control Hinges on a Few Key Issues Understanding the mineral content of the raw water Understanding the mineral content of the raw water Proper and complete Bleed Off Proper and complete Bleed Off Maintaining system water alkalinity in “Scale Safe” zone Maintaining system water alkalinity in “Scale Safe” zone Consistent addition of scale inhibitors Consistent addition of scale inhibitors Consistent addition of scale dispersants Consistent addition of scale dispersants

14. Corrosion Basics Corrosion is the deterioration of a metal due to interaction with its environment. Corrosion requires metal, oxygen and water. In cooling tower systems, the water contains significant amounts of air. The oxygen carried by that air reacts with the metal at the surface and starts a corrosion cell. Iron Water oxygen The key to preventing this is keeping the oxygen from interacting with with metal.

15. Corrosion Control Since we can’t remove the oxygen from the tower water, we must create a barrier between the metal and the water and oxygen. Iron Water oxygen The protective layer is thin and can be very delicate. There are three basic kinds of barriers PassivePassive PrecipitatedPrecipitated Film FormingFilm Forming

16. More on Corrosion Control The protective barrier prevents the oxygen from contacting the metal. Thereby preventing corrosion. Common Corrosion Inhibitors MolybdateMolybdate PhosphatePhosphate PhosphonatePhosphonate ZincZinc AzolesAzoles NitriteNitrite A combination of inhibitors is usually the best approach

17. Crevice and Underdeposit Corrosion When 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 a specially recognized corrosion cell. Generally, chemical treatment does not prevent or cure these corrosion issues. Hot Spots for Crevice and Underdeposit Corrosion Under dirt collected in the sump of the tower or on tube sheet Leaking threads Good and bad weld joints Under epoxy coatings Under seals and gaskets

18. Other Issues in Corrosion Aside from general corrosion, as previously described, there are other forms of corrosion that are equally important. Other Forms of Corrosion Galvanic - Corrosion between dissimilar or incompatible metals Stress Crack - Corrosion caused by mechanical stress such as vibration Flow Related - Cativation, and erosion None of these forms of corrosion can be controled chemically

19. Essential Cooling Tower Treatment Good Tower Treatment Starts with : Good Conductivity Control Good Conductivity Control Proper selection of treatment chemicals based on makeup water and operating conditions Proper selection of treatment chemicals based on makeup water and operating conditions Consistent Chemical Levels for Maximum Protection Consistent Chemical Levels for Maximum Protection Consistent and timely monitoring of the water chemistry Consistent and timely monitoring of the water chemistry Good Tower Treatment Ends with : Clean condenser tubes Clean condenser tubes Good heat transfer Good heat transfer Minimized corrosion of piping and surfaces Minimized corrosion of piping and surfaces Extended equipment life Extended equipment life Annual PM, and Cleaning Annual PM, and Cleaning

20. Boiler Standby / Summer Storage

21. Proper 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 Is NOT 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 prior Reduce treatment levels and blowdown heavily 2 days prior Increase bottom blowdown to remove mud Increase 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 header Fill boiler to header Add oxygen scavenger, phosphate and alkalinity booster Add oxygen scavenger, phosphate and alkalinity booster Fire boiler at low fire until steam begins to form Fire boiler at low fire until steam begins to form Close header Close header Low fire boiler every 4 to 6 weeks to keep chemicals mixed and active Low fire boiler every 4 to 6 weeks to keep chemicals mixed and active Wet Storage the Technique

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