Operation and Maint for Energy Efficiency

1 Cooling Tower Operation and Maintenance is the Key for Improved Energy EfficiencyCooling Tower Operation and Maintenance is the Key for Improved Energy EfficiencyPrinciple of Operation and Layout Principle of Operation and Layout Kavita AnujeKavita AnujeMaintenanceMaintenanceRegimens Regimens Trevor Trevor HeggHeggOperating Strategies & Water Treatment Operating Strategies & Water Treatment --Paul LindahlPaul LindahlCooling Tower Operation and Maintenance for Improved Energy EfficiencyTerminologyForced Draft CounterflowForced Draft CounterflowInduced Draft CounterflowInduced Draft CounterflowForced Draft CrossflowForced Draft CrossflowInduced Draft CrossflowOpen Cooling TowersOpen Cooling TowersClosed Circuit Closed Circuit Cooling TowersCooling TowersInduced Draft CrossflowCooling Tower Operation and Maintenance for Improved Energy EfficiencyOpen Cooling TowerOpen Cooling TowerAn evaporative piece of equipment that exposes An evaporative piece of equipment that exposes water directly to the cooling atmosphere, thereby water directly to the cooling atmosphere, thereby transferring the source heat load directly to the the source heat load directly to the Tower Operation and Maintenance for Improved Energy EfficiencyClosed Circuit Cooling TowerClosed Circuit Cooling TowerAn evaporative piece of equipment that contains twoAn evaporative piece of equipment that contains twoseparate fluid circuits.

2 The first is an external circuitseparate fluid circuits. The first is an external circuitwhere water is exposed to the atmosphere as itwhere water is exposed to the atmosphere as itcascades over the tubes of a coil bundle. The secondcascades over the tubes of a coil bundle. The secondis an internal circuit in which the fluid to be cooledis an internal circuit in which the fluid to be cooledcirculates inside the tubes of the coil inside the tubes of the coil Tower Operation and Maintenance for Improved Energy EfficiencyForced DraftForced DraftType of mechanical draft tower in which one orType of mechanical draft tower in which one ormore fans are located at the air inlet to force air into more fans are located at the air inlet to force air into the cooling cooling Tower Operation and Maintenance for Improved Energy EfficiencyInduced DraftInduced DraftType of mechanical draft tower in which one orType of mechanical draft tower in which one ormore fans are located in the air outlet to induce air more fans are located in the air outlet to induce air through the air the air Tower Operation and Maintenance for Improved Energy

3 EfficiencyCounterflowCounterflowIn a counterflow cooling tower, the air enters at theIn a counterflow cooling tower, the air enters at thebase of the tower, flows upward and interfacesbase of the tower, flows upward and interfacescounter currently with the falling hot currently with the falling hot Tower Operation and Maintenance for Improved Energy EfficiencyCrossflowCrossflowIn a crossflow cooling tower, the air flowsIn a crossflow cooling tower, the air flowshorizontally through the cooling tower and interfaceshorizontally through the cooling tower and interfacesperpendicularly with the falling hot with the falling hot Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionCooling Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionFluid InletFluid OutletCooling Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionCooling Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionFluid InletFluid OutletCooling Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionCooling Tower Operation and Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionCooling Tower Operation

4 And Maintenance for Improved Energy EfficiencyAir Flow DirectionWater Flow DirectionCooling Tower Operation and Maintenance for Improved Energy EfficiencyCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzWater Distribution SystemsWater Distribution Systems Gravity distribution systemGravity distribution system Spray distribution systemSpray distribution systemCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzGravity Distribution SystemGravity Distribution System Open basinsOpen basins Large orifice, 360 nozzlesLarge orifice, 360 nozzles Easily accessed for maintenance Easily accessed for maintenance Basin water level used to balance flowBasin water level used to balance flowCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzSpray 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 inletCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzHeat Transfer Surface (Fill or Wet Deck)Heat Transfer Surface (Fill or Wet Deck)

5 PVC wet deck surfacePVC wet deck surface Specialty wet deck materialsSpecialty wet deck materialsCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzPVC Wet Deck SurfacePVC Wet Deck Surface Impervious to rot, decay, fungus and biological Impervious to rot, decay, fungus and biological attackattack 130 F limitation for counterflow cooling towers130 F limitation for counterflow cooling towers 120 F limitation for crossflow cooling towers 120 F limitation for crossflow cooling towers Cooling Tower Operation and Maintenance for Improved Energy EfficiencyzzHigh Temperature PVC Wet Deck SurfaceHigh Temperature PVC Wet Deck Surface Impervious to rot, decay, fungus and biological Impervious to rot, decay, fungus and biological attackattack 150 F limitation for counterflow cooling towers150 F limitation for counterflow cooling towers 135 F limitation for crossflow cooling towers 135 F limitation for crossflow cooling towers Cooling Tower Operation and Maintenance for Improved Energy EfficiencyzzSpecialty Wet Deck SurfacesSpecialty Wet Deck Surfaces Available for process type applicationsAvailable for process type applications Galvanized or stainless steel wet deck Galvanized or stainless steel wet deck surfacesurface Dirty water fillDirty water fill Splash fillSplash fill Contact equipment manufacturer for Contact equipment manufacturer for performance information performance information Cooling Tower Operation and Maintenance for Improved Energy EfficiencyzzAir Moving SystemsAir Moving Systems Axial fansAxial fans Centrifugal fansCentrifugal fansCooling Tower Operation

6 And Maintenance for Improved Energy EfficiencyzzAxial FansAxial Fans Over 80% of cooling towers on HVAC Over 80% of cooling towers on HVAC applications use axial fansapplications use axial fans High volume/ Low static pressureHigh volume/ Low static pressure High efficiencyHigh Efficiency Low Energy consumptionLow Energy consumption Improved sound ratingsImproved sound ratingsCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzCentrifugal 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 requirementsCooling Tower Operation and Maintenance for Improved Energy Efficiencyzz1,500 GPM of Water1,500 GPM of Waterzz95 F EWT95 F EWTzz85 F LWT85 F LWTzz78 F EWBzzCounterflow, centrifugal Counterflow, centrifugal fan unit requires 60 HPfan unit requires 60 HPzzCrossflow, axial fan unit Crossflow.

7 Axial fan unit requires 30 HPrequires 30 HPzzAxial fan units require less Axial fan units require less HP than centrifugal fan HP than centrifugal fan units78 F EWBunitsCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzDrive SystemsDrive Systems Belt driveBelt drive Gear driveGear driveCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzProven performance on cooling Proven performance on cooling tower applicationtower applicationzzEfficient and designed for moist Efficient and designed for moist air applicationsair applicationsCooling Tower Operation and Maintenance for Improved Energy EfficiencyCooling Tower Equipment LayoutCooling Tower Equipment LayoutCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzPrevent warm air or drift from being introduced into fresh Prevent 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 areaszzConsider the potential for plumeConsider the potential for plumezzNote the direction of the prevailing windsNote the direction of the prevailing windszzEnsure adequate supply of fresh air to the air intakeEnsure adequate supply of fresh air to the air intakezzProvide adequate space for piping and proper servicing and Provide adequate space for piping and proper servicing and maintenancemaintenancezzTop of the unit discharge must be at least level with the Top of the unit discharge must be at least level with the adjacent wall adjacent wall Cooling Tower Operation and Maintenance for Improved Energy EfficiencyzzLayout ExamplesLayout Examples Adjacent to a wall or buildingAdjacent to a wall or building In an enclosureIn an enclosure Adjacent to a louvered or slotted

8 WallAdjacent to a louvered or slotted wallCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzNominalNominal 1,500 GPM 95/85/781,500 GPM 95/85/78zz1 F Recirculation1 F Recirculation 1,384 GPM 95/85/791,384 GPM 95/85/79 8% 8% DerateDeratezz2 F Recirculation2 F Recirculation 1,258 GPM 95/85/801,258 GPM 95/85/80 19% 19% DerateDeratePrevailing WindInduced DraftCooling TowerCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzNominalNominal 1,500 GPM 95/85/781,500 GPM 95/85/78zz1 F Recirculation1 F Recirculation 1,500 GPM 1,500 GPM F Recirculation2 F Recirculation 1,500 GPM 1,500 GPM WindInduced DraftCooling TowerCooling Tower Operation and Maintenance for Improved Energy EfficiencyEvery 1 F Increase in CWT Corresponds to aEvery 1 F Increase in CWT Corresponds to a2% Decrease in Chiller Efficiency2% Decrease in Chiller EfficiencyCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzCorrect cooling tower Correct cooling tower installation when installation when located adjacent to a located adjacent to a building or wallbuilding or wallInduced DraftCooling TowerCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzWhat is the distance What is the distance between the wall and between the wall and the air inlet to the the air inlet to the cooling tower?

9 Cooling tower? Maximum air velocity Maximum air velocity should not exceed 300 should not exceed 300 FPMFPM Air entry envelope Air entry envelope consists of top and two consists of top and two sidessides Based on 125,900 Based on 125,900 CFM, an inlet height of CFM, an inlet height of 10 feet and an air inlet 10 feet and an air inlet length of 12 feet, the length of 12 feet, the distance to the wall is distance to the wall is feetInduced DraftCooling TowerDCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzWhen cooling towers When cooling towers are positioned with air are positioned with air inlets facing each inlets facing each other, the distance other, the distance between cooling between cooling towers is 2 x Dtowers is 2 x DCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzWhat is the distance between What is the distance between the wall and the air inlet to the the wall and the air inlet to the cooling tower for a well cooling tower for a well enclosure?

10 Enclosure? Maximum air velocity should not Maximum air velocity should not exceed 400 FPMexceed 400 FPM Center the cooling tower within Center the cooling tower within the enclosure for uniform air flow the enclosure for uniform air flow to the air inletsto the air inlets Air entry is from the top onlyAir entry is from the top only Based on 125,900 CFM, an air Based on 125,900 CFM, an air entry area as indicated by the entry area as indicated by the shaded area, the distance to the shaded area, the distance to the wall is 8 feetwall is 8 feetDDWell Installation with anInduced Draft Cooling TowerCooling Tower Operation and Maintenance for Improved Energy EfficiencyzzWhat is the distance between What is the distance between the louvered wall and the air the louvered wall and the air inlet to the cooling tower for a inlet to the cooling tower for a well enclosure?well enclosure? Center the cooling tower within Center the cooling tower within the enclosure for uniform air flow the enclosure for uniform air flow to the air inletsto the air inlets Louver must provide at least 50% Louver must provide at least 50% net free areanet free area Louver air velocity should not Louver air velocity should not exceed 600 FPMexceed 600 FPM Maintain at least 3 feet between Maintain at least 3 feet between the tower air inlets and the the tower air inl