prof. osama el masry
DESCRIPTION
Prof. Osama El Masry. COOLING TOWER DESIGN. COOLING TOWER DESIGN IS A COMPROMISE Specification Water flow rate Hot water temperature Cold water temperature Location Material of construction Water quality Target Low capital cost Low operating cost Meeting specifications. - PowerPoint PPT PresentationTRANSCRIPT
Prof Osama El Masry
COOLING TOWER DESIGN IS A COMPROMISE Specificationbull Water flow ratebull Hot water temperaturebull Cold water temperaturebull Locationbull Material of constructionbull Water qualityTargetbull Low capital costbull Low operating costbull Meeting specifications
COOLING TOWER DESIGN
Water Flow Ratebull Increased flow provides design marginbull Too much margin causes loss of efficiencybull Tower should be testable at real flowWet Bulb Temperaturebull Unrealistic value makes testing difficultbull Possibility of unfair designRangebull Increased range makes testing difficultbull Tower size increase not linear with range
PITFALLS - SPECIFICATION
Cold Water Temperaturebull Low specification increases tower costbull Increases fan powerbull Provides design marginbull Cost increase not linear
PITFALLS - SPECIFICATION
Select fill typebull Water qualitybull ApplicationSelect tower typebull Fill typebull Specificationbull ApplicationSelect materials of constructionbull Tower sizebull Specificationbull EconomicsSelect and design model
DESIGN PROCESS
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
COOLING TOWER DESIGN IS A COMPROMISE Specificationbull Water flow ratebull Hot water temperaturebull Cold water temperaturebull Locationbull Material of constructionbull Water qualityTargetbull Low capital costbull Low operating costbull Meeting specifications
COOLING TOWER DESIGN
Water Flow Ratebull Increased flow provides design marginbull Too much margin causes loss of efficiencybull Tower should be testable at real flowWet Bulb Temperaturebull Unrealistic value makes testing difficultbull Possibility of unfair designRangebull Increased range makes testing difficultbull Tower size increase not linear with range
PITFALLS - SPECIFICATION
Cold Water Temperaturebull Low specification increases tower costbull Increases fan powerbull Provides design marginbull Cost increase not linear
PITFALLS - SPECIFICATION
Select fill typebull Water qualitybull ApplicationSelect tower typebull Fill typebull Specificationbull ApplicationSelect materials of constructionbull Tower sizebull Specificationbull EconomicsSelect and design model
DESIGN PROCESS
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Water Flow Ratebull Increased flow provides design marginbull Too much margin causes loss of efficiencybull Tower should be testable at real flowWet Bulb Temperaturebull Unrealistic value makes testing difficultbull Possibility of unfair designRangebull Increased range makes testing difficultbull Tower size increase not linear with range
PITFALLS - SPECIFICATION
Cold Water Temperaturebull Low specification increases tower costbull Increases fan powerbull Provides design marginbull Cost increase not linear
PITFALLS - SPECIFICATION
Select fill typebull Water qualitybull ApplicationSelect tower typebull Fill typebull Specificationbull ApplicationSelect materials of constructionbull Tower sizebull Specificationbull EconomicsSelect and design model
DESIGN PROCESS
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Cold Water Temperaturebull Low specification increases tower costbull Increases fan powerbull Provides design marginbull Cost increase not linear
PITFALLS - SPECIFICATION
Select fill typebull Water qualitybull ApplicationSelect tower typebull Fill typebull Specificationbull ApplicationSelect materials of constructionbull Tower sizebull Specificationbull EconomicsSelect and design model
DESIGN PROCESS
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Select fill typebull Water qualitybull ApplicationSelect tower typebull Fill typebull Specificationbull ApplicationSelect materials of constructionbull Tower sizebull Specificationbull EconomicsSelect and design model
DESIGN PROCESS
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
LOW FAN POWER
Increase Tower Sizebull Reduce air velocitybull Reduce air pressure drop and fan powerIncrease Fill Volumebull Increase water residence timebull Reduce air requiredbull Reduce fan powerIncrease Fan Diameterbull Reduce exit velocitybull Reduce fan power
DESIGN OPTIONS
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Flow Patternbull Crossflow cooling towersbull Counterflow cooling towersStructurebull Steelfrp structurebull Timber structurebull Rcc structureFill Typebull Splash fillbull Film flow fill
COOLING TOWER TYPES
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
TOWER TYPESCROSSFLOW
bull Water and air inCrossflow
bull Commonly used withSplash fill
bull Low fan powerbull Higher pump headbull Higher capital cost
Than counterflOW
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
bull The Dominant tower type for 30 yearsbull Very efficient utilization of splash fillbull Low fan power consumption with splash Fillbull Resistant to poor water qualitybull Low plan area
WHY CROSSFLOW
High pump head (up to 12 m)Not efficient with film fillsHigher tower size-higher civil costsHigher capital cost than counterflow with film fills
PROBLEMS
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
SPLASH FILLSbull Rectangular timberbull Triangular timberbull PVC Veebarbull Triangular PVCbull Pre stressed RCC
CROSS FLOW FILLS
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
TOWER TYPES
COUNTER FLOW bull Water and air in
Counterflowbull Usually with film fillbull Low pump headbull Low fan powerbull Low capital costbull Economical civil designbull Default option for power
Plants
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
bull The original cooling tower typebull Very efficient utilization of film fillbull Competitive fan power with film fillbull Low pump headbull Easy construction low civil costsbull Lowest capital cost with film fills
WHY COUNTER FLOW
1048766 High fan power with splash fill1048766 Film fill is sensitive to water quality
PROBLEMS
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
FILM FLOW FILLSbull High efficiency cross corrugated fillsbull Range of flute sizesbull Special vertical fluted fills for poor
Water quality
COUNTERFLOW FILLS
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
bull DRIFT ELIMINATORSbull Timber and PVC herringbonebull Cellular PVCbull PVC extruded profilebull Low drift lossesbull Low pressure drop
COMPONENTS
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
FAN POWERbull Can be reduced by designbull Operating cost reduced with speed controlPUMP POWERbull Usually overlooked in analysisbull Lower for film filled towersbull Operating cost is fixedWATER TREATMENT COSTbull Biological controlbull Corrosion controlbull Scaling control
OPERATING COSTS
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Cooling Towers DefinitionsCooling towers are evaporative coolers used for
cooling water or other working medium to near the ambient wet-bulb air temperature
Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries chemical plants power plants and building cooling
The towers vary in size from small roof-top units to very large hyperboloid structures that can be up to 200 m tall and 100 m in diameter or rectangular structures that can be over 40 m tall and 80 m long Smaller towers are normally factory-built while larger ones are constructed on site
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Definitions Range Difference between entering and leaving water
temperature Approach Difference between leaving water temperature and
entering air wet bulb Evaporation Method by which cooling towers cool the water Drift Entrained water droplets carried off by the cooling tower Blow down Water intentionally discharged from cooling tower
to maintain water quality Plume Hot moist air discharged from the cooling tower
forming a dense fog
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Natural Draft Cooling Tower
bull Natural Draft Cooling Tower This type depends upon the natural driving pressure caused by the difference in density between the cool outside air and the hot humid air inside The driving pressure ΔPD is given by
bull Δ PD = (ρo ndash ρi) H gc
Where
ndash ρo is density of outside air kgm3
ndash H height of the tower in m
ndash ρi is density of inside air kgm3
ndash gc is gravitatinal acc =981 ms2
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Psychrometric Chart
bull Dry bulb tempbull Wet bulb tempbull Relative Humiditybull Dew pointbull Moisture contentbull Enthalpybull Sp volume
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Psychrometric Chart
bull used to determine wet-bulb air temperature
Psychrometricsexe
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
A Psychrometer
The psychrometer is a device composed of two thermometers mounted on a sling One thermometer is fitted with a wet gauze and reads the wet-bulb temperature The other thermometer reads thedry-bulb or ordinary temperature
Sling Psychrometer
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Energy and Mass Balance
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Cooling Tower as steady-state steady-flow System
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Energy Balance
for a unit mass of dry air
ha1+whv1+WAhwA= ha2+whv2+WBhwB (1)wherebull ha = Enthalpy of dry air Jkgbull w = water vapordry air (humidity ratio)bull hv= Enthalpy of water vapor Jkgbull W= mass of watermass of dry airbull hw= Enthalpy of water Jkg
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
hv = hg amphw =hf from steam tables
ha2 - ha1 =Cp (T2-T1)Mass Balance
w2 ndashw1= WA ndash WB
Eq (1) can be written aswhg1+WAhfA= Cp (T2-T1) +[WA ndash(w2 ndashw1)] hfB (2)
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Air Density
bull Δ PD = (ρo ndash ρi) H gc where
ρo =mV= P1 Ra T1
ρi =mV= P2 Ra T2
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-
Useful formulas in design of system of cooling tower
Circulation rate (CR) Cooling tower capacity tons x 0189 litresec
Evaporation rate (ER) Circulation rate x 0008 litresec
Drift rate (DR) Circulation rate x 0002 litresec
Average bleed-off rate (ABF) Circulation rate x 0006 litresec
Make-up water (BR + ER + ABF) 15768 m3yr
Make-up water cost Make up water in m3yr x $458 $
Bleed-off cost ABF x 15768 x $12m3 $
Annual chemical treatment cost Circulation rate x 400 $yr
- Slide 1
- COOLING TOWER DESIGN
- PITFALLS - SPECIFICATION
- PITFALLS - SPECIFICATION (2)
- DESIGN PROCESS
- DESIGN OPTIONS
- COOLING TOWER TYPES
- TOWER TYPES CROSSFLOW
- WHY CROSSFLOW
- CROSS FLOW FILLS
- TOWER TYPES COUNTER FLOW
- WHY COUNTER FLOW
- COUNTERFLOW FILLS
- COMPONENTS
- OPERATING COSTS
- Cooling Towers Definitions
- Definitions
- Natural Draft Cooling Tower
- Psychrometric Chart
- Psychrometric Chart (2)
- A Psychrometer
- Slide 22
- Energy and Mass Balance
- Cooling Tower as steady-state steady-flow System
- Energy Balance
- Slide 26
- Air Density
- Slide 28
- Slide 29
- Slide 30
- Slide 31
- Useful formulas in design of system of cooling tower
-