Cooling Technology Institute
www.cti.org
Cooling Tower Operation andCooling Tower Operation and
Maintenance for ImprovedMa...
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Air Moving SystemsAir Moving Systems
–– Axial fansAxial fans
–– Centrifugal fansC...
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Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance
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Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance
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Drive SystemsDrive Systems
–– Belt driveBelt drive
–– Gear driveGear drive
Coolin...
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Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance
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Maintenance GuidelinesMaintenance Guidelines
forfor
Open Cooling Towers &Open Coo...
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MAINTENANCEMAINTENANCE
Maintenance and water treatment areMaintenance and water t...
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MAINTENANCE? Who needs it?MAINTENANCE? Who needs it?
Cooling Technology Institute
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MAINTENANCEMAINTENANCE
Maintenance and water treatment are theMaintenance and wat...
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MAINTENANCEMAINTENANCE
Objectives:Objectives:
•• Review basic elements of a goodR...
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MAINTENANCE REGIMENSMAINTENANCE REGIMENS
Review major cooling tower systems andRe...
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MAINTENANCE REGIMENSMAINTENANCE REGIMENS
•• Reputable manufacturers provide maint...
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MAINTENANCE REGIMENSMAINTENANCE REGIMENS
•• Manufacturer and ASHRAEManufacturer a...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water System TypesCirculati...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water System TypesCirculati...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Circulating Water SystemCirculating Wat...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Th...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
••...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Be...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Ge...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Ge...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Fa...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Mo...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Mo...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Fan & Drive SystemFan & Drive System
Mo...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Heat Transfer SurfaceHeat Transfer Surf...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Heat Transfer SurfaceHeat Transfer Surf...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Heat Transfer SurfaceHeat Transfer Surf...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Heat Transfer SurfaceHeat Transfer Surf...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Heat Transfer SurfaceHeat Transfer Surf...
Cooling Technology Institute
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Drift EliminatorsDrift Eliminators
Sepa...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Drift EliminatorsDrift Eliminators
Prop...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Air Inlet LouversAir Inlet Louvers
Exam...
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MAINTENANCE REGIMENMAINTENANCE REGIMEN ––
Air Inlet LouversAir Inlet Louvers
Prop...
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Winter OperationWinter Operation
Maintenance & Energy Saving TipsMaintenance & En...
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Winter OperationWinter Operation
Maintenance & Energy Saving TipsMaintenance & En...
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Winter OperationWinter Operation
Maintenance & Energy Saving TipsMaintenance & En...
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Maintenance & Energy Efficient OperationMaintenance & Energy Efficient Operation
...
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Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance
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WHY WATER TREATMENT?WHY WATER TREATMENT?
Air
Debris
Gases
Air
Water
Air and water...
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Biological GrowthBiological Growth
Bacteria, AlgaeBacteria, Algae
–– Fouling exch...
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CorrosionCorrosion
Consider metals in entire water systemConsider metals in entir...
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Deposits Impact CorrosionDeposits Impact Corrosion
CELL METABOLISM LOWERS pH UNDE...
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Deposits Impact CorrosionDeposits Impact Corrosion
PITTING FAILURE
Oxide Layer
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MICROBES (MB)
CORROSION DEPOSITION
Each Treatment Impacts the OthersEach Treatmen...
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Control MethodsControl Methods
BiocideBiocide to reduce Microbe andto reduce Micr...
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Water QualityWater Quality
General GuidelinesGeneral Guidelines::
Note: for tower...
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Water QualityWater Quality
Sulfates: If calcium > 800Sulfates: If calcium > 800 p...
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Water QualityWater Quality
Total Suspended Solids (TSS):Total Suspended Solids (T...
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Water QualityWater Quality
Combinations of treatment chemicals mayCombinations of...
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Concentrations andConcentrations and BlowdownBlowdown
Evaporating water leaves mi...
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Concentrations andConcentrations and BlowdownBlowdown
Example:Example:
–– Evapora...
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Concentrations andConcentrations and BlowdownBlowdown
Range 1.5 2 2.5 3 4 5 6
5 0...
Operation for System EfficiencyOperation for System Efficiency
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Condensing Water TemperatureCondensing Water Temperature
•• 3 GPM/TR (95°/85°/78°...
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Capacity Control MethodologiesCapacity Control Methodologies
•• Capacity Control ...
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Capacity Control DampersCapacity Control Dampers
•• Offers precise system control...
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Effect of Fan Speed on CapacityEffect of Fan Speed on Capacity
0
20
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60
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Single Speed, Full PowerSingle Speed, Full Power
45
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20...
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Two SpeedTwo Speed
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20 30 40 50 60 70 80
FULL SPEED ...
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Two Cell, Two SpeedTwo Cell, Two Speed
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20 30 40 50 ...
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VariableVariable
FrequencyFrequency
35° 45° 55° 65° 75° 85°
80%
60%
40%
20%
0
90°...
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Compressor ImpactCompressor Impact
45
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55
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20 30 40 50 60 7...
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Compressor PowerCompressor Power
84
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70 75 80 85
COMPRESS...
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Free Cooling RegionFree Cooling Region
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“Free Cooling”“Free Cooling”
••When the tower can produce sufficientlyWhen the to...
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Free Cooling OperationFree Cooling Operation
Graph assumes that the system will g...
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Benefit Depends on LocationBenefit Depends on Location
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Cooling Tower Operation andCooling Tower Operation and
Maintenance for ImprovedMa...
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Cooling tower operation & maintenance for improved effeciency

  1. 1. Cooling Technology Institute www.cti.org Cooling Tower Operation andCooling Tower Operation and Maintenance for ImprovedMaintenance for Improved Energy EfficiencyEnergy Efficiency Russell E. Lindemann
  2. 2. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Principle of Operation and LayoutPrinciple of Operation and Layout -- Russ LindemannRuss Lindemann MaintenanceMaintenance RegimensRegimens -- Randy BradleyRandy Bradley Operating Strategies & Water TreatmentOperating Strategies & Water Treatment -- Paul LindahlPaul Lindahl
  3. 3. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Open Cooling TowersOpen Cooling Towers Closed Circuit CoolingClosed Circuit Cooling TowersTowers Forced DraftForced Draft CounterflowCounterflow Induced DraftInduced Draft CounterflowCounterflow Forced DraftForced Draft CrossflowCrossflow Induced DraftInduced Draft CrossflowCrossflow
  4. 4. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Open Cooling TowerOpen Cooling Tower An evaporative piece of equipment that exposesAn evaporative piece of equipment that exposes water directly to the cooling atmosphere, therebywater directly to the cooling atmosphere, thereby transferring the source heat load directly to the air.transferring the source heat load directly to the air.
  5. 5. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Closed Circuit Cooling TowerClosed Circuit Cooling Tower An evaporative piece of equipment that contains twoAn evaporative piece of equipment that contains two separate fluid circuits. The first is an external circuitseparate fluid circuits. The first is an external circuit where water is exposed to the atmosphere as itwhere water is exposed to the atmosphere as it cascades over the tubes of a coil bundle. The secondcascades over the tubes of a coil bundle. The second is an internal circuit in which the fluid to be cooledis an internal circuit in which the fluid to be cooled circulates inside the tubes of the coil bundle.circulates inside the tubes of the coil bundle.
  6. 6. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Forced DraftForced Draft Type of mechanical draft tower in which one orType of mechanical draft tower in which one or more fans are located at the air inlet to force air intomore fans are located at the air inlet to force air into the cooling tower.the cooling tower.
  7. 7. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Induced DraftInduced Draft Type of mechanical draft tower in which one orType of mechanical draft tower in which one or more fans are located in the air outlet to induce airmore fans are located in the air outlet to induce air through the air inlets.through the air inlets.
  8. 8. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency CounterflowCounterflow In aIn a counterflowcounterflow cooling tower, the air enters at thecooling tower, the air enters at the base of the tower, flows upward and interfacesbase of the tower, flows upward and interfaces counter currently with the falling hot water.counter currently with the falling hot water.
  9. 9. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency CrossflowCrossflow In aIn a crossflowcrossflow cooling tower, the air flowscooling tower, the air flows horizontally through the cooling tower and interfaceshorizontally through the cooling tower and interfaces perpendicularly with the falling hot water.perpendicularly with the falling hot water.
  10. 10. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Water Flow Direction Air Flow Direction
  11. 11. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction Fluid Inlet Fluid Outlet
  12. 12. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction
  13. 13. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction Fluid Inlet Fluid Outlet
  14. 14. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction
  15. 15. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction
  16. 16. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Air Flow Direction Water Flow Direction
  17. 17. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Water Distribution SystemsWater Distribution Systems –– Gravity distribution systemGravity distribution system –– Spray distribution systemSpray distribution system
  18. 18. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Gravity Distribution SystemGravity Distribution System –– Open basinsOpen basins –– Large orifice, 360° nozzlesLarge orifice, 360° nozzles –– Easily accessed for maintenanceEasily accessed for maintenance –– Basin water level used to balance flowBasin water level used to balance flow
  19. 19. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Spray Distribution SystemSpray Distribution System –– Pressurized systemPressurized system –– Large orifice, 180° directional nozzlesLarge orifice, 180° directional nozzles –– Spray header and branchesSpray header and branches –– 2 PSI spray pressure at the header inlet2 PSI spray pressure at the header inlet
  20. 20. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Heat Transfer Surface (Fill or Wet Deck)Heat Transfer Surface (Fill or Wet Deck) –– PVC wet deck surfacePVC wet deck surface –– Specialty wet deck materialsSpecialty wet deck materials
  21. 21. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency PVC SurfacePVC Surface –– Impervious to rot, decay, fungus and biological attackImpervious to rot, decay, fungus and biological attack –– 130°F limitation for130°F limitation for counterflowcounterflow cooling towerscooling towers –– 120°F limitation for120°F limitation for crossflowcrossflow cooling towerscooling towers
  22. 22. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency High Temperature PVC SurfaceHigh Temperature PVC Surface –– Impervious to rot, decay, fungus and biological attackImpervious to rot, decay, fungus and biological attack –– 150°F limitation for150°F limitation for counterflowcounterflow cooling towerscooling towers –– 135°F limitation for135°F limitation for crossflowcrossflow cooling towerscooling towers
  23. 23. Cooling Technology Institute www.cti.org Air Moving SystemsAir Moving Systems –– Axial fansAxial fans –– Centrifugal fansCentrifugal fans Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency
  24. 24. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Axial FansAxial Fans –– Over 80% of cooling towers on HVAC applications useOver 80% of cooling towers on HVAC applications use axial fansaxial fans –– High volume/ Low static pressureHigh volume/ Low static pressure –– High efficiencyHigh efficiency –– Low energy consumptionLow energy consumption –– Improved sound ratingsImproved sound ratings
  25. 25. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Centrifugal FansCentrifugal Fans –– High volume/Static pressuresHigh volume/Static pressures –– Indoor installationsIndoor installations –– Inlet or discharge ductworkInlet or discharge ductwork –– High energy consumptionHigh energy consumption –– Quiet operationQuiet operation –– Tight layout requirementsTight layout requirements
  26. 26. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency 1,500 GPM of Water1,500 GPM of Water 95°F EWT95°F EWT 85°F LWT85°F LWT 78°F EWB78°F EWB CounterflowCounterflow, centrifugal, centrifugal fan unit requires 60 HPfan unit requires 60 HP CrossflowCrossflow, axial fan unit, axial fan unit requires 30 HPrequires 30 HP Axial fan units require lessAxial fan units require less HP than centrifugal fanHP than centrifugal fan unitsunits
  27. 27. Cooling Technology Institute www.cti.org Drive SystemsDrive Systems –– Belt driveBelt drive –– Gear driveGear drive Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency
  28. 28. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Proven performance on coolingProven performance on cooling tower applicationtower application Efficient and designed for moistEfficient and designed for moist air applicationsair applications
  29. 29. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Cooling Tower Equipment LayoutCooling Tower Equipment Layout
  30. 30. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Prevent warm air or drift from being introduced into freshPrevent warm air or drift from being introduced into fresh air intakes or from being carried over populated areasair intakes or from being carried over populated areas Consider the potential for plumeConsider the potential for plume Note the direction of the prevailing windsNote the direction of the prevailing winds Ensure adequate supply of fresh air to the air intakeEnsure adequate supply of fresh air to the air intake Provide adequate space for piping and proper servicing andProvide adequate space for piping and proper servicing and maintenancemaintenance Top of the unit discharge must be at least level with theTop of the unit discharge must be at least level with the adjacent walladjacent wall
  31. 31. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Layout ExamplesLayout Examples –– Adjacent to a wall or buildingAdjacent to a wall or building –– In an enclosureIn an enclosure –– Adjacent to a louvered or slotted wallAdjacent to a louvered or slotted wall
  32. 32. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency NominalNominal –– 1,500 GPM 95/85/781,500 GPM 95/85/78 1°F Recirculation1°F Recirculation –– 1,384 GPM 95/85/791,384 GPM 95/85/79 –– 8%8% DerateDerate 2°F Recirculation2°F Recirculation –– 1,258 GPM 95/85/801,258 GPM 95/85/80 –– 19%19% DerateDerate Prevailing Wind Induced Draft Cooling Tower
  33. 33. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency NominalNominal –– 1,500 GPM 95/85/781,500 GPM 95/85/78 1°F Recirculation1°F Recirculation –– 1,500 GPM1,500 GPM 95.77/85.77/7995.77/85.77/79 2°F Recirculation2°F Recirculation –– 1,500 GPM1,500 GPM 96.56/86.56/8096.56/86.56/80 Prevailing Wind Induced Draft Cooling Tower
  34. 34. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Every 1°F Increase in CWT Corresponds to aEvery 1°F Increase in CWT Corresponds to a 2% Decrease in Chiller Efficiency2% Decrease in Chiller Efficiency
  35. 35. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Correct cooling towerCorrect cooling tower installation wheninstallation when located adjacent to alocated adjacent to a building or wallbuilding or wall Induced Draft Cooling Tower
  36. 36. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency What is the distanceWhat is the distance between the wall and thebetween the wall and the air inlet to the coolingair inlet to the cooling tower?tower? –– Maximum air velocity shouldMaximum air velocity should not exceed 300 FPMnot exceed 300 FPM –– Air entry envelope consists ofAir entry envelope consists of top and two sidestop and two sides –– Based on 125,900 CFM, anBased on 125,900 CFM, an inlet height of 10 feet and aninlet height of 10 feet and an air inlet length of 12 feet, theair inlet length of 12 feet, the distance to the wall is 6.5 feetdistance to the wall is 6.5 feet Induced Draft Cooling Tower D
  37. 37. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency When cooling towersWhen cooling towers are positioned with airare positioned with air inlets facing eachinlets facing each other, the distanceother, the distance between coolingbetween cooling towers is 2 x Dtowers is 2 x D
  38. 38. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency What is the distance betweenWhat is the distance between the wall and the air inlet to thethe wall and the air inlet to the cooling tower for a wellcooling tower for a well enclosure?enclosure? –– Maximum air velocity should notMaximum air velocity should not exceed 400 FPMexceed 400 FPM –– Center the cooling tower within theCenter the cooling tower within the enclosure for uniform air flow to theenclosure for uniform air flow to the air inletsair inlets –– Air entry is from the top onlyAir entry is from the top only –– Based on 125,900 CFM, an air entryBased on 125,900 CFM, an air entry area as indicated by the shaded area,area as indicated by the shaded area, the distance to the wall is 8 feetthe distance to the wall is 8 feet D D Well Installation with an Induced Draft Cooling Tower
  39. 39. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency D D Louvered Well Installation with an Induced Draft Cooling Tower What is the distance betweenWhat is the distance between the louvered wall and the airthe louvered wall and the air inlet to the cooling tower for ainlet to the cooling tower for a well enclosure?well enclosure? –– Center the cooling tower within theCenter the cooling tower within the enclosure for uniform air flow to theenclosure for uniform air flow to the air inletsair inlets –– Louver must provide at least 50% netLouver must provide at least 50% net free areafree area –– Louver air velocity should not exceedLouver air velocity should not exceed 600 FPM600 FPM –– Maintain at least 3 feet between theMaintain at least 3 feet between the tower air inlets and the louvered walltower air inlets and the louvered wall
  40. 40. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Maintenance Regimens - Randy Bradley
  41. 41. Cooling Technology Institute www.cti.org Maintenance GuidelinesMaintenance Guidelines forfor Open Cooling Towers &Open Cooling Towers & Closed Circuit Cooling TowersClosed Circuit Cooling Towers
  42. 42. Cooling Technology Institute www.cti.org MAINTENANCEMAINTENANCE Maintenance and water treatment areMaintenance and water treatment are the most important factors affectingthe most important factors affecting the life and energy efficient operationthe life and energy efficient operation of evaporative cooling equipment!of evaporative cooling equipment!
  43. 43. Cooling Technology Institute www.cti.org MAINTENANCE? Who needs it?MAINTENANCE? Who needs it?
  44. 44. Cooling Technology Institute www.cti.org MAINTENANCEMAINTENANCE Maintenance and water treatment are theMaintenance and water treatment are the most neglected regimens of coolingmost neglected regimens of cooling tower operation, and cooling towers aretower operation, and cooling towers are generally the most neglectedgenerally the most neglected components in the mechanical system.components in the mechanical system. Why?Why? •• Remotely located & difficult to accessRemotely located & difficult to access •• Limited maintenance resourcesLimited maintenance resources PeoplePeople TrainingTraining BudgetsBudgets
  45. 45. Cooling Technology Institute www.cti.org MAINTENANCEMAINTENANCE Objectives:Objectives: •• Review basic elements of a goodReview basic elements of a good maintenance regimen.maintenance regimen. •• Develop an understanding of theDevelop an understanding of the costs of poor maintenance on the lifecosts of poor maintenance on the life & energy efficiency of cooling towers.& energy efficiency of cooling towers.
  46. 46. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENSMAINTENANCE REGIMENS Review major cooling tower systems andReview major cooling tower systems and their appropriate maintenance regimens:their appropriate maintenance regimens: •• Circulating WaterCirculating Water •• Fan and DriveFan and Drive •• Heat Transfer Surface (Fill or Coil)Heat Transfer Surface (Fill or Coil) •• Air Entry LouversAir Entry Louvers •• Drift EliminatorsDrift Eliminators
  47. 47. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENSMAINTENANCE REGIMENS •• Reputable manufacturers provide maintenanceReputable manufacturers provide maintenance instructions and check sheets. It is best to followinstructions and check sheets. It is best to follow the manufacturer’s recommendations!the manufacturer’s recommendations! •• ASHRAE Handbook also provides a good generalASHRAE Handbook also provides a good general guide.guide.
  48. 48. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENSMAINTENANCE REGIMENS •• Manufacturer and ASHRAEManufacturer and ASHRAE guidelines are for normal coolingguidelines are for normal cooling season regimens.season regimens. •• Unusual operating conditions willUnusual operating conditions will require additional operator attention.require additional operator attention. •• Winter operation and longWinter operation and long--term shutterm shut-- down requires additional servicing.down requires additional servicing. Consult the manufacturer.Consult the manufacturer.
  49. 49. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water System TypesCirculating Water System Types CrossCross--flow Tower Operation View of Water Distribution Boxflow Tower Operation View of Water Distribution Box Gravity Flow Water Distribution SystemGravity Flow Water Distribution System Common to crossCommon to cross--flow cooling towers.flow cooling towers.
  50. 50. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water System TypesCirculating Water System Types Closed Circuit Tower View of Pressurized DistributionClosed Circuit Tower View of Pressurized Distribution Operation System and NozzlesOperation System and Nozzles Pressurized Flow Water Distribution SystemPressurized Flow Water Distribution System
  51. 51. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Spray Nozzles & Water Distribution BoxesSpray Nozzles & Water Distribution Boxes need to be inspected & cleanedneed to be inspected & cleaned •• After startAfter start--up andup and •• Monthly thereafter.Monthly thereafter. Regular inspection allows quick treatmentRegular inspection allows quick treatment and control of corrosion and mechanicaland control of corrosion and mechanical failures.failures.
  52. 52. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Clogged distribution nozzles cause:Clogged distribution nozzles cause: •• Reduced or malReduced or mal--distributed water flow =distributed water flow = capacity reductioncapacity reduction •• Overflowing distribution boxes = water &Overflowing distribution boxes = water & chemical losschemical loss •• Heat Exchanger surface scaling/fouling =Heat Exchanger surface scaling/fouling = capacity reductioncapacity reduction •• Excessive drift = water & chemical lossExcessive drift = water & chemical loss •• Fan motor overFan motor over--ampingamping (forced draft) =(forced draft) = reduced motor lifereduced motor life
  53. 53. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Suction Strainers:Suction Strainers: •• Designed to protect pumpDesigned to protect pump and nozzles.and nozzles. •• Inspect & clean weekly.Inspect & clean weekly. •• Operating environmentsOperating environments laden with airborne fibrousladen with airborne fibrous materials (agricultural,materials (agricultural, paper, textile processing)paper, textile processing) demand more frequentdemand more frequent strainer cleaning.strainer cleaning.
  54. 54. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Poor Strainer maintenance leads to:Poor Strainer maintenance leads to: ••Reduced flow = reduced capacityReduced flow = reduced capacity ••PumpPump cavitationcavitation = pump repair costs and= pump repair costs and objectionable plant noiseobjectionable plant noise ••Collapsed strainers = tower repair costsCollapsed strainers = tower repair costs
  55. 55. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Basin Maintenance:Basin Maintenance: ••Clean and flush monthly.Clean and flush monthly. ••Inspect and repair corrosion.Inspect and repair corrosion. Accumulated solids:Accumulated solids: Clog equalizer & bypass linesClog equalizer & bypass lines Hide corrosion cellsHide corrosion cells Give breeding environment for bioGive breeding environment for bio--growthgrowth
  56. 56. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Closed Circuit Tower Water Pumps:Closed Circuit Tower Water Pumps: ••Inspect seals & free rotation of shaft monthly.Inspect seals & free rotation of shaft monthly. ••Lubricate bearings per motor manufacturerLubricate bearings per motor manufacturer instructions.instructions. Leaking seals are costlyLeaking seals are costly with lost water andwith lost water and treatment chemicals.treatment chemicals.
  57. 57. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System MakeMake--up water and operating level controlsup water and operating level controls Mechanical Float ValveMechanical Float Valve Electric Valve & SensorElectric Valve & Sensor
  58. 58. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Set operating level and water supply pressure toSet operating level and water supply pressure to manufacturer’s recommendations.manufacturer’s recommendations. ••Inspect water level and adjust float monthly.Inspect water level and adjust float monthly. ••Inspect valve seals and full shutInspect valve seals and full shut--off monthly.off monthly. Clean electronic sensing elements as required.Clean electronic sensing elements as required.
  59. 59. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Circulating Water SystemCirculating Water System Malfunctioning levelMalfunctioning level control can be costly withcontrol can be costly with water and chemical losswater and chemical loss and even equipmentand even equipment damage.damage. Proper water level control is required for pumpProper water level control is required for pump priming and prevention of air entrainment inpriming and prevention of air entrainment in suction lines.suction lines.
  60. 60. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System The fan system moves the air which cools theThe fan system moves the air which cools the water.water. It is critical to keep the fan systemIt is critical to keep the fan system in top operating condition!in top operating condition! ••Daily walk around the tower and listen for unusualDaily walk around the tower and listen for unusual noises or vibration.noises or vibration. ••If reasons for vibration are easily detected, (loose belts,If reasons for vibration are easily detected, (loose belts, loose motor base, loose bearing locking collars, looseloose motor base, loose bearing locking collars, loose fan or sheave bushings) correct as required.fan or sheave bushings) correct as required. ••If causes of vibration are not easily detected, consult aIf causes of vibration are not easily detected, consult a specialty vibration analysis contractor.specialty vibration analysis contractor.
  61. 61. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System •• Quarterly clean fan of heavy debris (trash,Quarterly clean fan of heavy debris (trash, bird droppings, scale) and inspect the fanbird droppings, scale) and inspect the fan and drive components for tight fasteners,and drive components for tight fasteners, missing balance washers & structuralmissing balance washers & structural integrity.integrity. •• Repair or replace corroded hardware, evenRepair or replace corroded hardware, even the fan if necessary.the fan if necessary. •• Check the mechanical equipment supportCheck the mechanical equipment support for cracks and tight hardware.for cracks and tight hardware. •• Check security of fan guards.Check security of fan guards.
  62. 62. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Belt Drive Systems:Belt Drive Systems: Belt Tensioning:Belt Tensioning: Check 24 hrs after startCheck 24 hrs after start--up.up. Check monthly thereafter.Check monthly thereafter. 1/2”1/2” -- 3/4” deflection with3/4” deflection with moderate finger pressure atmoderate finger pressure at center span of belt. Checkcenter span of belt. Check manufacturer’s O&M guide.manufacturer’s O&M guide.
  63. 63. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Gear Drive Systems:Gear Drive Systems: Lubrication:Lubrication: Check oil level weekly.Check oil level weekly. Change oil 500 hours orChange oil 500 hours or 4 weeks after start4 weeks after start--up.up. Follow gear box O&MFollow gear box O&M guide for oil type andguide for oil type and change frequency.change frequency. Recommend synthetic,Recommend synthetic, oxidation inhibited oil.oxidation inhibited oil.
  64. 64. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Gear Drive Systems:Gear Drive Systems: Drive Shafts:Drive Shafts: ••Inspect drive shaftInspect drive shaft and couplingand coupling hardware monthly.hardware monthly. ••Inspect coupling flexInspect coupling flex elements for bucklingelements for buckling and fatigue damage.and fatigue damage. Replace as required.Replace as required. Drive shaft CouplingDrive shaft Coupling
  65. 65. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Fan Shaft Bearings:Fan Shaft Bearings: Bearing Lubrication:Bearing Lubrication: Lubrication ScheduleLubrication Schedule •• 1000 hours or 3 months1000 hours or 3 months -------- Induced DraftInduced Draft •• 2000 hours or 6 months2000 hours or 6 months -------- Forced DraftForced Draft •• Use water resistantUse water resistant grease approved bygrease approved by manufacturer.manufacturer.
  66. 66. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Motors:Motors: Good maintenance starts with the installationGood maintenance starts with the installation 1. Wire per nameplate and check rotation1. Wire per nameplate and check rotation •• MultiMulti--lead (9, 12 wire) motors may be confusinglead (9, 12 wire) motors may be confusing •• Check multiCheck multi--speed motor rotation at both speedsspeed motor rotation at both speeds •• Check current draw on startCheck current draw on start--upup 2. Check2. Check operational controlsoperational controls •• Set proper time delay between speed changesSet proper time delay between speed changes •• Set thermostat differentials to limit fan cyclingSet thermostat differentials to limit fan cycling (3(3--6 starts/hour)6 starts/hour)
  67. 67. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Motors:Motors: Motor life and efficiency is enhanced byMotor life and efficiency is enhanced by 1. Keeping motor body cool1. Keeping motor body cool •• Clean casing and cooling fins of scale buildClean casing and cooling fins of scale build--upup •• Do not obstruct cooling vents around motorDo not obstruct cooling vents around motor 2. Properly lubricating motor bearings2. Properly lubricating motor bearings •• Follow motor O&M guide for lubrication intervals,Follow motor O&M guide for lubrication intervals, typically 2typically 2--3 years, and compatible greases.3 years, and compatible greases. •• Some motors have sealed bearings and do notSome motors have sealed bearings and do not require lubrication.require lubrication.
  68. 68. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Fan & Drive SystemFan & Drive System Motors:Motors: Motors driven by variable frequency drives (Motors driven by variable frequency drives (vfdvfd)) 1. Offer fan energy saving at the cooling tower1. Offer fan energy saving at the cooling tower 2. Reduce fan cycling and provide soft starting2. Reduce fan cycling and provide soft starting 3. Need to be specifically selected for3. Need to be specifically selected for vfdvfd dutyduty 4. Need limits on length between motor & drive4. Need limits on length between motor & drive (Depending on drive, typically 50 to 200 feet.)(Depending on drive, typically 50 to 200 feet.) 5. Run hotter and need good cooling air5. Run hotter and need good cooling air--flowflow
  69. 69. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Heat Transfer SurfaceHeat Transfer Surface Inspect heat transfer surfaces monthly.Inspect heat transfer surfaces monthly. Inspect both the topInspect both the top andand bottom. Generally,bottom. Generally, scaling starts on the top and bioscaling starts on the top and bio--fouling buildsfouling builds from the bottom.from the bottom. Open tower surface (fill)Open tower surface (fill) Closed circuit tower coilClosed circuit tower coil
  70. 70. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Heat Transfer SurfaceHeat Transfer Surface Open Tower Packing (Fill):Open Tower Packing (Fill): ••Scale, solids and bioScale, solids and bio--foulingfouling restrict air & water passages.restrict air & water passages. ••Capacity diminishes rapidlyCapacity diminishes rapidly with increased fouling.with increased fouling. ••Extra weight can damage fillExtra weight can damage fill and structural supports.and structural supports. Typical fill clogging from bioTypical fill clogging from bio-- films and suspended solids.films and suspended solids.
  71. 71. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Heat Transfer SurfaceHeat Transfer Surface Closed Circuit Tower Coil:Closed Circuit Tower Coil: ••Scale on coilScale on coil walls is a directwalls is a direct heat transferheat transfer barrier.barrier. ••CapacityCapacity diminishes withdiminishes with increased fouling.increased fouling.
  72. 72. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Heat Transfer SurfaceHeat Transfer Surface Closed Circuit Tower CoilClosed Circuit Tower Coil Closed Circuit Cooling Tower Performance vs. Scale Accumulation on Heat Transfer Coil 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0 0.002 0.004 0.006 Fouling Factor & Approximate Scale Thickness On Coil TowerPerformance Capability 1/32" Scale 1/16" ScaleClean Tube 3/32" Scale High Heat Flux Coil Low Heat Flux Coil ( 0.8 mm ) ( 1.6 mm ) ( 2.4 mm )
  73. 73. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Heat Transfer SurfaceHeat Transfer Surface Cleaning heavy scale or bioCleaning heavy scale or bio--fouling is difficult.fouling is difficult. Often the fill or coil are damaged in the process.Often the fill or coil are damaged in the process. IT IS ESSENTIAL TO MAINTAIN AIT IS ESSENTIAL TO MAINTAIN A PREVENTATIVEPREVENTATIVE WATER TREATMENTWATER TREATMENT PROGRAM.PROGRAM. Results of a scaled coilResults of a scaled coil cleaned with acid. Thiscleaned with acid. This coil is ruined.coil is ruined.
  74. 74. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Drift EliminatorsDrift Eliminators Separate water droplets from leaving air streamSeparate water droplets from leaving air stream ••Subject to damage from weather & vandalismSubject to damage from weather & vandalism ••Subject to corrosionSubject to corrosion Damaged eliminatorDamaged eliminator section, which shouldsection, which should be replaced.be replaced.
  75. 75. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Drift EliminatorsDrift Eliminators Proper placement and good physical conditionProper placement and good physical condition ••Minimizes water and treatment chemical lossMinimizes water and treatment chemical loss ••Minimizes air restriction for maximum capacityMinimizes air restriction for maximum capacity ••Minimizes airborne bacterial transmissionMinimizes airborne bacterial transmission Inspect condition and placement monthly.Inspect condition and placement monthly. Remove bioRemove bio--growth and debris. Notifygrowth and debris. Notify treatment service of biotreatment service of bio--growth.growth. Replace damaged eliminators.Replace damaged eliminators.
  76. 76. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Air Inlet LouversAir Inlet Louvers Examples of scaled, bioExamples of scaled, bio--fouled and debris laden inlet louvers.fouled and debris laden inlet louvers.
  77. 77. Cooling Technology Institute www.cti.org MAINTENANCE REGIMENMAINTENANCE REGIMEN –– Air Inlet LouversAir Inlet Louvers Proper placement and good physical conditionProper placement and good physical condition ••Minimizes water and treatment chemical lossMinimizes water and treatment chemical loss from basin splashfrom basin splash--out.out. ••Minimizes air restriction for maximum capacityMinimizes air restriction for maximum capacity ••Minimizes airborne bacterial transmissionMinimizes airborne bacterial transmission Inspect condition and placement monthly.Inspect condition and placement monthly. Remove bioRemove bio--growth and debris. Notifygrowth and debris. Notify treatment service of biotreatment service of bio--growth.growth. Repair damaged louvers.Repair damaged louvers.
  78. 78. Cooling Technology Institute www.cti.org Winter OperationWinter Operation Maintenance & Energy Saving TipsMaintenance & Energy Saving Tips Prevent freezing and expensive ice damagePrevent freezing and expensive ice damage before the winter season arrives:before the winter season arrives: ••Check heat tracing and insulation on drains,Check heat tracing and insulation on drains, makemake--up and circulating water lines.up and circulating water lines. ••Test basin heaters and controls.Test basin heaters and controls. ••Charge coils with glycol or drain completely.Charge coils with glycol or drain completely. ••Test operation of positive closure dampersTest operation of positive closure dampers -- open with fan on and closed with fan off.open with fan on and closed with fan off.
  79. 79. Cooling Technology Institute www.cti.org Winter OperationWinter Operation Maintenance & Energy Saving TipsMaintenance & Energy Saving Tips More tips:More tips: ••Do not run fans with pumps off unless basin isDo not run fans with pumps off unless basin is drained. Ensure that fan drives are selected fordrained. Ensure that fan drives are selected for dry operation.dry operation. ••Interlock heater “off” when pump or fanInterlock heater “off” when pump or fan operates.operates. ••Keep a heat load on the tower. Cold waterKeep a heat load on the tower. Cold water temperature should stay above 40°F (4.4C)temperature should stay above 40°F (4.4C)
  80. 80. Cooling Technology Institute www.cti.org Winter OperationWinter Operation Maintenance & Energy Saving TipsMaintenance & Energy Saving Tips Ice can cause expensive damage to the fill andIce can cause expensive damage to the fill and tower structure.tower structure. ••Schedule regularSchedule regular defrost cycles.defrost cycles. ••Keep water flow inKeep water flow in safe range of thesafe range of the distribution nozzle.distribution nozzle.
  81. 81. Cooling Technology Institute www.cti.org Maintenance & Energy Efficient OperationMaintenance & Energy Efficient Operation A basic maintenance regimen is an investment to:A basic maintenance regimen is an investment to: maximize the energy efficiency of the tower and themaximize the energy efficiency of the tower and the mechanical system,mechanical system, minimize capital investment in equipment byminimize capital investment in equipment by extending its life and replacement intervals,extending its life and replacement intervals, minimize annual maintenance expenses throughminimize annual maintenance expenses through preventative measures rather than costly repairs.preventative measures rather than costly repairs. Towers lacking a good maintenance regimen, whichTowers lacking a good maintenance regimen, which includes water treatment, routinely operate at well belowincludes water treatment, routinely operate at well below design capability.design capability.
  82. 82. Cooling Technology Institute www.cti.org Cooling Tower Operation and MaintenanceCooling Tower Operation and Maintenance for Improved Energy Efficiencyfor Improved Energy Efficiency Operating Strategies and Water Treatment Paul Lindahl
  83. 83. Cooling Technology Institute www.cti.org WHY WATER TREATMENT?WHY WATER TREATMENT? Air Debris Gases Air Water Air and water contents enter and build in the tower.
  84. 84. Cooling Technology Institute www.cti.org Biological GrowthBiological Growth Bacteria, AlgaeBacteria, Algae –– Fouling exchangersFouling exchangers –– Fouling Cooling TowerFouling Cooling Tower –– Health Effects, such as Legionnaire’s DiseaseHealth Effects, such as Legionnaire’s Disease Water TreatmentsWater Treatments –– Oxidizing BiocidesOxidizing Biocides –– NonNon--oxidizing Biocidesoxidizing Biocides Deposits assist growth ofDeposits assist growth of biofilmsbiofilms andand biofoulingbiofouling,, side stream filtration is recommendedside stream filtration is recommended
  85. 85. Cooling Technology Institute www.cti.org CorrosionCorrosion Consider metals in entire water systemConsider metals in entire water system –– Steel and Iron vs. Stainless SteelSteel and Iron vs. Stainless Steel –– Copper and its AlloysCopper and its Alloys –– AluminumAluminum Appropriate Water Treatments withAppropriate Water Treatments with qualified WT vendor/consultantqualified WT vendor/consultant Control deposition of solids, side streamControl deposition of solids, side stream filtration recommendedfiltration recommended
  86. 86. Cooling Technology Institute www.cti.org Deposits Impact CorrosionDeposits Impact Corrosion CELL METABOLISM LOWERS pH UNDER BIOFILM WHICH CORRODES METAL Oxide Layer
  87. 87. Cooling Technology Institute www.cti.org Deposits Impact CorrosionDeposits Impact Corrosion PITTING FAILURE Oxide Layer
  88. 88. Cooling Technology Institute www.cti.org MICROBES (MB) CORROSION DEPOSITION Each Treatment Impacts the OthersEach Treatment Impacts the Others
  89. 89. Cooling Technology Institute www.cti.org Control MethodsControl Methods BiocideBiocide to reduce Microbe andto reduce Microbe and BiofilmBiofilm GrowthGrowth [corrosion and scaling effect][corrosion and scaling effect] –– 0.2 to 0.50.2 to 0.5 ppmppm freefree ClCl residual control range typicalresidual control range typical InhibitorsInhibitors to protect Metals from Corrosionto protect Metals from Corrosion InhibitorsInhibitors to prevent Scale Precipitationto prevent Scale Precipitation SurfactantSurfactant = Bio= Bio--penetrationpenetration AntiAnti--foamfoam = Reduce visible effect of biocide= Reduce visible effect of biocide
  90. 90. Cooling Technology Institute www.cti.org Water QualityWater Quality General GuidelinesGeneral Guidelines:: Note: for tower water, not makeNote: for tower water, not make--upup High TemperatureHigh Temperature:: < 120< 120 °°FF PH: 6.5PH: 6.5 –– 9.09.0 Chlorides: < 750Chlorides: < 750 ppmppm for Galvanized Steel,for Galvanized Steel, < 1500< 1500 ppmppm for 300 Series Stainless Steelfor 300 Series Stainless Steel Calcium: (as CaCO3) < 800Calcium: (as CaCO3) < 800 ppmppm should notshould not result in calcium sulfate scaleresult in calcium sulfate scale
  91. 91. Cooling Technology Institute www.cti.org Water QualityWater Quality Sulfates: If calcium > 800Sulfates: If calcium > 800 ppmppm, sulfates <, sulfates < 800800 ppmppm (or less in arid climates) to limit(or less in arid climates) to limit scale.scale. –– Otherwise, < 5000Otherwise, < 5000 ppmppm is acceptable.is acceptable. Silica: < 150Silica: < 150 ppmppm as SiO2 to prevent silicaas SiO2 to prevent silica scalescale Iron: < 3Iron: < 3 ppmppm Manganese: < 0.1Manganese: < 0.1 ppmppm
  92. 92. Cooling Technology Institute www.cti.org Water QualityWater Quality Total Suspended Solids (TSS):Total Suspended Solids (TSS): –– < 25< 25 ppmppm for film fillfor film fill Total Dissolved Solids (TDS):Total Dissolved Solids (TDS): –– < 5000< 5000 ppmppm for thermal performancefor thermal performance Oil and Grease:Oil and Grease: –– Avoid with film fill (contributes to fill plugging,Avoid with film fill (contributes to fill plugging, prevents proper seasoning).prevents proper seasoning). Ammonia:Ammonia: –– Limit to 50Limit to 50 ppmppm if copper alloys are presentif copper alloys are present
  93. 93. Cooling Technology Institute www.cti.org Water QualityWater Quality Combinations of treatment chemicals mayCombinations of treatment chemicals may cause reactions which reduce treatmentcause reactions which reduce treatment effectivenesseffectiveness Certain chemicals such as surfactants,Certain chemicals such as surfactants, biodispersantsbiodispersants and antifoams may increaseand antifoams may increase drift ratedrift rate Consult CT & WT vendors/consultantsConsult CT & WT vendors/consultants
  94. 94. Cooling Technology Institute www.cti.org Concentrations andConcentrations and BlowdownBlowdown Evaporating water leaves minerals,Evaporating water leaves minerals, concentrates over timeconcentrates over time BlowdownBlowdown of a small amount of waterof a small amount of water keeps concentration at desired levelkeeps concentration at desired level C = (R x EPD + BD + D)/(BD + D)C = (R x EPD + BD + D)/(BD + D)
  95. 95. Cooling Technology Institute www.cti.org Concentrations andConcentrations and BlowdownBlowdown Example:Example: –– Evaporation = 0.08% circulating water perEvaporation = 0.08% circulating water per degree of rangedegree of range –– Drift = 0.02% of circulating water rateDrift = 0.02% of circulating water rate –– Range = 10 Deg FRange = 10 Deg F –– Concentrations = 5Concentrations = 5 –– BlowdownBlowdown = 0.18% of circulating water rate= 0.18% of circulating water rate
  96. 96. Cooling Technology Institute www.cti.org Concentrations andConcentrations and BlowdownBlowdown Range 1.5 2 2.5 3 4 5 6 5 0.78 0.36 0.23 0.21 0.11 0.08 0.06 10 1.58 0.76 0.50 0.41 0.24 0.18 0.14 15 2.38 1.16 0.77 0.61 0.37 0.28 0.22 20 3.18 1.56 1.03 0.81 0.51 0.38 0.30 25 3.98 1.96 1.30 1.01 0.64 0.48 0.38 30 4.78 2.36 1.57 1.21 0.77 0.58 0.46 35 5.58 2.76 1.83 1.41 0.91 0.68 0.54 Based on: 0.02 % drift rate and 0.08 % evaporation rate
  97. 97. Operation for System EfficiencyOperation for System Efficiency
  98. 98. Cooling Technology Institute www.cti.org Condensing Water TemperatureCondensing Water Temperature •• 3 GPM/TR (95°/85°/78°)3 GPM/TR (95°/85°/78°) •• 2 GPM/TR (105°/85°/78°)2 GPM/TR (105°/85°/78°) •• Lower condensingLower condensing temperatures, fans full,temperatures, fans full, gives coldest water atgives coldest water at chillerchiller •• Chiller energy savingsChiller energy savings almost always outweighsalmost always outweighs tower fan energytower fan energy consumptionconsumption 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 0.085 80 81 82 83 84 85 86 87 3 GPM/TON 2 GPM/TON DESIGN COLD WATER TEMP. — (°F) H P p e r T O N DESIGN COOLING TOWER FAN HP VARIATION FAN HP PER TON OF LOAD (BASIS: 75°F WET-BULB)
  99. 99. Cooling Technology Institute www.cti.org Capacity Control MethodologiesCapacity Control Methodologies •• Capacity Control DampersCapacity Control Dampers •• MultiMulti--speed Motorsspeed Motors •• Variable Frequency DrivesVariable Frequency Drives •• Single Speed Fan CyclingSingle Speed Fan Cycling •• Free CoolingFree Cooling •• Fans full SpeedFans full Speed –– Run WildRun Wild
  100. 100. Cooling Technology Institute www.cti.org Capacity Control DampersCapacity Control Dampers •• Offers precise system controlOffers precise system control •• No fan power savingsNo fan power savings
  101. 101. Cooling Technology Institute www.cti.org Effect of Fan Speed on CapacityEffect of Fan Speed on Capacity 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 100 CAPACITY (AIRFLOW) REQUIRED POWER PERCENT OF DESIGN FAN SPEED P E R C E N T FAN CHARACTERISTICS CAPACITY & HORSEPOWER RELATIVE TO SPEED
  102. 102. Cooling Technology Institute www.cti.org Single Speed, Full PowerSingle Speed, Full Power 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 10°F RANGE WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE SINGLE CELL TOWER — SINGLE SPEED FAN
  103. 103. Cooling Technology Institute www.cti.org Two SpeedTwo Speed 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 FULL SPEED HALF SPEED WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE SINGLE CELL TOWER — TWO SPEED FAN (10°F RANGE)
  104. 104. Cooling Technology Institute www.cti.org Two Cell, Two SpeedTwo Cell, Two Speed 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 FULL SPEED 1 HALF, 1 FULL HALF SPEED WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE TWO CELL TOWER — TWO SPEED FANS (10°F RANGE)
  105. 105. Cooling Technology Institute www.cti.org VariableVariable FrequencyFrequency 35° 45° 55° 65° 75° 85° 80% 60% 40% 20% 0 90° 80° Cold Water °F 100% 100% Control Temperature Variable Frequency Drive Fan Control
  106. 106. Cooling Technology Institute www.cti.org Compressor ImpactCompressor Impact 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 10°F RANGE WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE SINGLE CELL TOWER — SINGLE SPEED FAN Region for influencing compressor horsepower.
  107. 107. Cooling Technology Institute www.cti.org Compressor PowerCompressor Power 84 86 88 90 92 94 96 98 100 70 75 80 85 COMPRESSOR HORSEPOWER COLD WATER TEMPERATURE (°F) P E R C E N T POTENTIAL COMPRESSOR HP REDUCTIONS CONSTANT LOAD — REDUCING CONDENSER WATER TEMPERATURE This is a “rule of thumb” curve. Verify actual reductions with chiller manufacturer.
  108. 108. Cooling Technology Institute www.cti.org Free Cooling RegionFree Cooling Region 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 10°F RANGE WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE SINGLE CELL TOWER — SINGLE SPEED FAN Region for consideration of “free cooling”.
  109. 109. Cooling Technology Institute www.cti.org “Free Cooling”“Free Cooling” ••When the tower can produce sufficientlyWhen the tower can produce sufficiently cold water without the chiller.cold water without the chiller. ••Direct free cooling..Direct free cooling.. ••Indirect free cooling..Indirect free cooling..
  110. 110. Cooling Technology Institute www.cti.org Free Cooling OperationFree Cooling Operation Graph assumes that the system will go to free cooling when the tower is capable of producing 50°F or colder water. 40 45 50 55 60 65 70 75 80 85 90 20 30 40 50 60 70 80 CHILLER ON CHILLER OFF WET BULB TEMPERATURE — (°F) C O L D W A T E R TYPICAL COOLING TOWER PERFORMANCE FULL LOAD — FULL FAN SPEED — FULL WATER FLOW
  111. 111. Cooling Technology Institute www.cti.org Benefit Depends on LocationBenefit Depends on Location 0 2000 4000 6000 8000 10000 -10 0 10 20 30 40 50 60 70 80 ANNUAL HOURS INDICATED W.B. WILL NOT BE EXCEEDED WET BULB TEMPERATURE — (°F) H O U R S WET BULB OCCURRANCE DES MOINES VICINITY
  112. 112. Cooling Technology Institute www.cti.org Cooling Tower Operation andCooling Tower Operation and Maintenance for ImprovedMaintenance for Improved Energy EfficiencyEnergy Efficiency
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