1. Advanced Chemical Technology, Inc.
Water Savings Through Cooling Tower Design, Construction and Proper Chemical Treatment
Advanced Chemical Technology, Inc.
April 5, 2016
Bryan Small Matt Fogle

2. Overview Water California’s Drought
Cooling Tower Design and Functionality
Maximizing Cooling Tower Water Savings
Alkalinity Programs
Acid
Makeup Water Pretreatment
Cooling Tower Design Considerations

3. Water Hydrological cycle The universal solvent High specific heat
Cheap*
Readily available*
Safe
High specific heat
Ability to store large amounts of heat (energy)
*Not so much in CA

4. Water Pure Water What makes water conductive? Non-conductive Salts
Gases
Metals

5. Water Water Sources Surface Water Ground Water Low dissolved Solids
High Suspended Solids
Quality changes through season
Ground Water
High dissolved solids
Low suspended solids
Consistent quality

6. Water Water quality effects water savings pH Conductivity (TDS)
Hardness (Ca and Mg)
Alkalinity (CO3)
Silica
Iron, Chlorides, Phosphate, etc.

7. California’s Drought Entering the 5th year Snowpack at 83% of avg
30% of water supply
25% water conservation mandate still in effect
Majority of reservoirs still well below historical averages

8. California’s Drought

9. California’s Drought Water Quality Lower quality Varying water sources
Higher dissolved solids
Lower quality
Warmer, shallow water supports algal blooms
Increased conductivity
Salt water intrusion
Parameter
2012
2014
Delta
TDS
386
538
+152
Conductivity
617
856
+239
Total Hardness
157
254
+97
Chloride 77 91
+14
Sodium 64 86
+22
Sulfate
102
193
+91
San Diego – Miramar Treatment Facility

10. Cooling Towers Open loop heat exchanger Hot water returns from chiller
Air is used to remove heat from the water through evaporation
Cold water returns to chiller to remove heat from refrigerant

11. Cooling Towers Evaporation in CT concentrates impurities
Pure water evaporates
Water is removed through tower blowdown
Makeup = Evaporation + Blowdown
Cycles of Concentration or Concentration Ratio (CR)
Determines water savings

12. Cooling Towers Evaporation determined by size of unit
Can change blowdown through increasing CR
Reducing blowdown
Increases water savings
Increases TDS
Can lead to scaling

13. Cooling Towers Water chemistry limits Scale pH Temperature Silica
Hardness
Alkalinity
Scale
Reduces efficiency
Increases energy costs
Damage equipment

14. Water Savings Through Chemistry
0.01” of calcium carbonate (scale) on heat exchangers reduces efficiency by 10%
500 tons of AC, operating 0.6 Kw/ton and a cost of $0.07/Kw will cost $184,000…10% increase is $18,400 annually
Water treatment for that system should cost $6,000 - $12,000 annually.

15. Water Savings Through Chemistry
Water tends to scale or corrode
High hardness and alkalinity
Tends to scale
Low hardness and alkalinity
Tends to corrode
Three main treatment methods for cooling towers
Alkaline program
Acid Control
Makeup water pretreatment

16. Water Savings Through Chemistry
Alkaline Program
Concentrates tower water so it tends to scale
Uses chemistry to control/inhibit scale
Limiting factors
Alkalinity
400 – 600 ppm as CaCO3
Hardness
1200 – 1400 ppm as CaCO3
Parameter
2012
2014
Delta
TDS
386
538
+152
Conductivity
617
856
+239
Total Hardness
157
254
+97
Alkalinity 91
122
+31
Chloride 77
+14
Sodium 64 86
+22
Sulfate
102
193
+91
San Diego – Miramar Treatment Facility
2012 Concentration Ratio: 4.4 – 6.6
2014 Concentration Ratio: 3.3 – 4.9
11% Increase in Water Usage
(Alkalinity Limiting Factor)

17. Water Savings Through Chemistry
pH control with acid
Additional chemical cost
Hazardous material
Reduces alkalinity, hardness limiting factor
Total Hardness Limit
1200 – 1400 ppm as CaCO3
Parameter
2012
2014
Delta
TDS
386
538
+152
Conductivity
617
856
+239
Total Hardness
157
254
+97
Alkalinity 91
122
+31
Chloride 77
+14
Sodium 64 86
+22
Sulfate
102
193
+91
San Diego – Miramar Treatment Facility
2014 Concentration Ratio: 3.3 – 4.9 (Alkaline Program)
2014 Concentration Ratio: 4.7 – 5.5 (Acid Program)
12% Decrease in Water Usage vs. Alkaline Program
(Total Hardness Limiting Factor)

18. Water Savings Through Chemistry
Makeup water pretreatment
Water softening
Removes calcium and magnesium from makeup water
Eliminates the ability for the water to form scale
Dramatically increases cycles of concentration
Reverse Osmosis
Blending RO water with makeup water to reduce overall mineral concentration

19. Water Savings Through Chemistry
Water Softening of Makeup Water
Allows for 10+ CR in cooling tower
Not limited by alkalinity
No hardness
No scale
Parameter
2012
2014
Delta
TDS
386
538
+152
Conductivity
617
856
+239
Total Hardness
157
254
+97
Alkalinity 91
122
+31
Chloride 77
+14
Sodium 64 86
+22
Sulfate
102
193
+91
San Diego – Miramar Treatment Facility
2014 Concentration Ratio: 3.3 – 4.9 (Alkaline Program)
2014 Concentration Ratio: 4.7 – 5.5 (Acid Program)
2014 Concentration Ratio: 20+ (Makeup Water Pretreatment – Water Softening )
27% Decrease in Water Usage vs. Alkaline Program
17% Decrease in Water Usage vs. Acid Program
(*No Limiting Factors With Soft Water*)

20. Alkaline Program Pros and Cons
Low equipment cost
Low chemical cost
Simple control system
Typically, water treatment chemistry is not corrosive
Achieve most significant water savings from 1 – 6 cycles
Cons
Water savings may be severely limited (dependent on makeup water mineral content)
Possibility of scale formation if there is a change in water quality

21. Acid Program Pros and Cons
Increased water savings over non-chemical or alkaline treatment program
Low equipment cost
Add pH control to system ($500 - $1500)
Add acid tank and pump
Low acid cost
$ $4.00 per gallon
Cons
Highly corrosive material
Can severely damage equipment if overfed
Hazardous for employees
More complicated chemistry program than Alkaline

22. Pretreatment Program Pros and Cons
Significant water savings over alkaline or acid program
Eliminates the systems ability to form scale which can increase energy costs
Cons
High upfront equipment cost
Water treatment system
Filtration
Complicated treatment program
May require equipment coating or painting to protect metals

23. Water Savings Considerations
Increasing your CR saves water
Additional costs to increasing CR
Chemical
Service
Equipment
Reduced blowdown can cause accumulation of debris in basin
20+ CR
High tower conductivity
Mineral rich water
Bulk water chemically treated to prevent corrosion
Air-Water interface can be corrosive
Splash zones can build up minerals
Drift becomes mineral rich (can be corrosive)

24. Water Savings Considerations
Downsides to water savings can be addressed
Reduced Blowdown
Basin sweepers/side stream filtration
Mineral buildup in splash zones
Wash down/clean these areas more frequently
Mineral rich drift
Epoxy coat metals in drift zones
Coat chiller end bells and tube sheets

25. Cooling Tower Design Considerations
Metallurgy of Tower
Galvanized
Low cost
White rust
Stainless Steel
High cost
High corrosion resistance
Composite
Not as durable as metal
Filtration system
Reduces debris in CT
Reduces cost of operation (cleaner heat exchanger surfaces)
Reduces biocide feed
Reduces cost of cleanout
Coating
End bells and tube sheets
Inside and outside CT

26. Case Study – County of San Diego
County Administration Center (CAC)
900 tons of cooling
Alkaline program
CR = 2.2
High hardness
High alkalinity
No filtration
Stainless steel towers
County Operations Center (COC)
2700 tons of cooling
Acid Program
CR = 4.5
High hardness
Centrifugal filtration system with basin sweepers on all cooling towers
Stainless steel towers

27. Case Study – County of San Diego
CAC
Filtration system installed
Piping in CT drift zones coated with epoxy paint
Makeup water pretreatment equipment installed (removal of hardness)
New controller installed for monitoring pretreatment system and CT control
COC
Piping in CT drift zones coated with epoxy paint
Makeup water pretreatment equipment installed (removal of hardness)
New controller installed for monitoring pretreatment system and CT control
Acid removed from site

28. Case Study – County of San Diego
CAC (estimated values)
Annual water savings of over 600,000 gallons
94% reduction in blowdown
44% reduction in overall water consumption
COC (estimated values)
Annual water savings of over 1,700,000 gallons
88% reduction in blowdown
20% reduction in overall water consumption

29. Case Study – County of San Diego
Actual values exceeded estimated water savings

30. Case Study – County of San Diego
Cooling tower load conditions were higher than anticipated (verified with water meters after estimates were calculated)
Resulted in higher than anticipated water savings
Estimated project ROI between two sites was 31 months
COC = 18 months, CAC = 55 months
With higher than expected water savings, this number is reduced even further

31. Case Study – County of San Diego
State mandated 25% reduction in water usage
County of San Diego exceeded this mandate at both sites
4 more sites online now
All anticipated to exceed the 25% state mandated reduction in water usage
Total water savings to date across all systems is over 7,700,000 gallons
At current San Diego water rates, this equates to a monetary savings of over $100,000

32. Q & A

33. THANK YOU!
ACT has over 20 years as a leader in industrial water treatment throughout California, Arizona and Nevada. For more information on our water treatment services, please visit us at
You can also directly contact us at:
Bryan Small
Matt Fogle