Cooling water (CW) system

A brief description of cooling water system in power generation and as well as Saba Power Plant

1. Preparedby:
MohammadShoebSiddiqui
SeniorShiftSupervisor
SabaPowerPlant

2. Coolingwateristhewaterremoving
heatfromamachineorsystem.Cooling
watermayberecycledthroughare-
circulatingsystemorusedinasingle
passonce-throughcooling(OTC)
system.Recirculatingsystemsmay
beopeniftheyrelyuponcooling
towersorcoolingpondstoremoveheat
orclosedifheatremovalisaccomplished
withnegligibleevaporativelossof
coolingwater.
Prepared by: Mohammad Shoeb Siddiqui

3. Industrialcoolingtowersmayuseriverwater,coastalwater
(seawater),orwellwaterastheirsourceoffreshcooling
water.Thelargemechanicalinduced-draftorforced-draft
coolingtowersinindustrialplantscontinuouslycirculate
coolingwaterthroughheatexchangersandotherequipment
wherethewaterabsorbsheat.Thatheatisthenrejectedto
theatmospherebythepartialevaporationofthewaterin
coolingtowerswhereupflowingairiscontactedwiththe
circulatingdownflowofwater.Thelossofevaporatedwater
intotheairexhaustedtotheatmosphereisreplacedby
"make-up"freshriverwaterorfreshcoolingwater.Sincethe
evaporationofpurewaterisreplacedbymake-upwater
containingcarbonatesandotherdissolvedsalts,aportionof
thecirculatingwaterisalsocontinuouslydiscardedas
"blowdown"watertopreventtheexcessivebuild-upofsalts
inthecirculatingwater.
Prepared by: Mohammad Shoeb Siddiqui

4. Cooling
Tower
Condenser
CW
Pumps
CTF
From Bore Wells
CT Makeup
Ambient Condition
Temp. 27.5
o
C
Humidity 88.5 %
CW I/L
Temp.
30
o
C
CW O/L
Temp. 45
o
C
Air flow
Air flow
Raw & Fire
Water Tank
Capacity
2155 m
3
CCW Heat
Exchanger
Prepared by: Mohammad Shoeb Siddiqui

5. Condenser:
Thecondenseristhemostimportantcomponentoftheturbinecyclethat
affectstheturbineheatrate.Thefunctionofthecondenseristocondense
exhauststeamfromthesteamturbinebyrejectingtheheatofevaporationto
thecoolingwaterpassingthroughthecondenser.Generally,twinshell-
doublepass-surfacetypecondensersareemployedforhighercapacityunits
Condense
r
Cooled
Water
Coolin
g
Tower
AirAir
Make-up
Water
Hot
Water
Prepared by: Mohammad Shoeb Siddiqui

6. COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

7. Prepared by: Mohammad Shoeb Siddiqui

8. Different types of
cooling towers are
used in the power
plants depending upon
the location, size,
infrastructure and
water resources etc.
Close cycle –wet
cooling systems:
-Induced draft
-Forced draft
-Natural draftcooling
towers
Prepared by: Mohammad Shoeb Siddiqui

9. Natural draft
Large concrete chimneys
generally used for water flow rates above 45,000 m
3
/hr
utility power stations
Mechanical draft
Lrge fans to force or suck air through circulated water.
The water falls downward over fill surfaces, which help
increase the contact time between the water and the air
maximising heat transfer between the two.
Cooling rates ofMechanicaldraft towers depend upon
their fan diameter and speed of operation
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

10. •Hot air moves through tower
•Fresh cool air is drawn into the
tower from bottom
•No fan required
•Concrete tower <200 m
•Used for large heat duties
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

11. Natural Draft Cooling Towers
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

12. Counter flow
•Air drawn up
through falling water
•Fill located inside
tower
Cross flow
•Air drawn across
falling water
•Fill located
outside tower
Natural Draft Cooling Towers
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

13. Mechanical Draft Cooling Towers
•Large fans to force air through
circulated water
•Water falls over fill surfaces:
maximum heat transfer
•Cooling rates depend on many
parameters
•Large range of capacities
•Can be grouped, e.g. 4-cell tower
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

14. Three types
•Forced draft
•Induced draft cross flow
•Induced draft counter flow
Mechanical Draft Cooling Towers
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

15. Induced Draft Cooling Towers
•Two types
•Cross flow
•Counter flow
•Advantage: less recirculation than
forced draft towers
•Disadvantage: fans and motor drive
mechanism require weather-
proofinh
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

16. •Hot water enters at the top
•Air enters at bottom and exits at top
•Uses forced and induced draft fans
Induced Draft Counter Flow CT
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

17. Induced Draft Cross Flow CT
•Water enters top and passes over fill
•Air enters on one side or opposite sides
•Induced draft fan draws air across fill
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

18. •Airblownthrough
towerbycentrifugal
fanatairinlet
•Advantages:suited
forhighairresistance
&fansarerelatively
quiet
•Disadvantages:
recirculationdueto
highair-entryandlow
air-exitvelocities
Forced Draft Cooling Towers
TYPES OF COOLING TOWER
Prepared by: Mohammad Shoeb Siddiqui

19. Frame and casing
Fill
Cold water basin
Drift eliminators
Air inlet
Louvers
Nozzles
Fans
Pumps
Chemical Dosing System
Prepared by: Mohammad Shoeb Siddiqui

20. •Frame and casing: support exterior
enclosures
•Fill: facilitate heat transfer by maximizing
water / air contact
•Splash fill
•Film fill
•Cold water basin: receives water at bottom
of tower
Prepared by: Mohammad Shoeb Siddiqui

21. •Drift eliminators: capture droplets in air stream
•Air inlet: entry point of air
•Louvers: equalize air flow into the fill and retain
water within tower
•Nozzles: spray water to wet the fill
•Fans: deliver air flow in the tower
•Pumps: deliver the water flow in the tower
Prepared by: Mohammad Shoeb Siddiqui

22. Wooden components included the frame, casing,
louvers, fill, and often the cold water basin
Galvanized steel, various grades of stainless steel, glass
fiber, and concrete
enhance corrosion resistance, reduce maintenance, and promote reliability and
long service life
Plastics are widely used for fill, including PVC,
polypropylene, and other polymers. Plastics also find
wide use as nozzle materials
Aluminum, glass fiber, and hot-dipped galvanized steel
are commonly used fan materials.
Centrifugal fans are often fabricated from galvanized
steel. Propeller fans are fabricated from galvanized,
aluminum, or molded glass fiber reinforced plastic
Components of Cooling Tower
Prepared by: Mohammad Shoeb Siddiqui

23. Heatexchangebetween
airandwateris
influencedbysurface
areaofheatexchange,
timeofheatexchange
(interaction) and
turbulenceinwater
effectingthoroughness
ofintermixing.Fill
mediainacoolingtower
isresponsibletoachieve
allofabove.
Components of Cooling Tower
Prepared by: Mohammad Shoeb Siddiqui

24. Assessment of Cooling Towers
Measured Parameters
•Wet bulb temperature of air
•Dry bulb temperature of air
•Cooling tower inlet water temperature
•Cooling tower outlet water temperature
•Exhaust air temperature
•Electrical readings of pump and fan
motors
•Water flow rate
•Air flow rate
Prepared by: Mohammad Shoeb Siddiqui

25. Performance Parameters
1.Range
2.Approach
3.Effectiveness
4.Cooling capacity
5.Evaporation loss
6.Cycles of concentration
7.Blow down losses
8.Liquid / Gas ratio
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

27. Heat dissipation (in kCal/hour) and circulated
flow rate (m
3
/hr) are not sufficient to
understand cooling tower performance.
Forexample,acoolingtowersizedtocool4540
m
3
/hrthrougha13.9
o
Crangemightbelarger
thanacoolingtowertocool4540m
3
/hr
through19.5
o
Crange.
Prepared by: Mohammad Shoeb Siddiqui

28. Cooling Water Treatment
Drift Loss in the Cooling Towers
driftlossrequirementtoaslowas0.003–0.001%
CoolingTowerFans
FlowControlStrategies
Prepared by: Mohammad Shoeb Siddiqui

29. Prepared by: Mohammad Shoeb Siddiqui

30. Difference between
cooling water inlet
and outlet
temperature:
Range (°C) = CW inlet
temp –CW outlet
temp
High range = good
performance
Range
Approach
Hot Water Temperature (In)
Cold Water Temperature (Out)
Wet Bulb Temperature (Ambient)
(In) to the Tower
(Out) from the
Tower
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

31. Range
Approach
Hot Water Temperature (In)
Cold Water Temperature
(Out)
Wet Bulb Temperature
(Ambient)
(In) to the Tower
(Out) from the
Tower
Difference between cooling
tower outlet cold water
temperature and ambient
wet bulb temperature:
Approach (°C) =
CW outlet temp –Wet bulb
temp
Low approach = good
performance
2. Approach
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

32. 3. Effectiveness
Effectiveness in %
= Range / (Range +
Approach)
= 100 x (CW temp –CW
out temp) / (CW in
temp –Wet bulb temp)
High effectiveness =
good performance
Range
Approach
Hot Water Temperature (In)
Cold Water Temperature
(Out)
Wet Bulb Temperature
(Ambient)
(In) to the Tower
(Out) from the
Tower
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

33. 4. Cooling Capacity
Heat rejected in kCal/hr
or tons of refrigeration
(TR)
= mass flow rate of water
X specific heat X
temperature difference
High cooling capacity =
good performance
Range
Approach
Hot Water Temperature (In)
Cold Water Temperature
(Out)
Wet Bulb Temperature
(Ambient)
(In) to the Tower
(Out) from the
Tower
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

34. 5. Evaporation Loss
Water quantity (m3/hr)
evaporated for cooling duty
= theoretically, 1.8 m3for
every 10,000,000 kCal heat
rejected
= 0.00085 x 1.8 x circulation
rate (m3/hr) x (T1-T2)
T1-T2 = Temp. difference
between inlet and outlet water
Range
Approach
Hot Water Temperature
(In)
Cold Water Temperature
(Out)
Wet Bulb Temperature
(Ambient)
(In) to the Tower
(Out) from the
Tower
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

35. 6. Cycles of concentration (C.O.C.)
Ratio of dissolved solids in circulating water to
the dissolved solids in make up water
Depend on cycles of concentration and the evaporation
losses
Blow Down = Evaporation Loss / (C.O.C. –1)
7. Cycles of concentration (C.O.C.)
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

36. 8. Liquid Gas (L/G) Ratio
Ratio between water and air mass flow rates
Heat removed from the water must be equal to the heat
absorbed by the surrounding air
L(T1 –T2) = G(h2 –h1)
L/G = (h2 –h1) / (T1 –T2)
T1 = hot water temp (oC)
T2 = cold water temp (oC)
Enthalpy of air water vapor mixture at inlet wet bulb temp (h1) and outlet wet
bulb temp (h2)
Assessment of Cooling Towers
Prepared by: Mohammad Shoeb Siddiqui

37. Energy Efficiency Opportunities
1.Selecting a cooling tower
2.Fills
3.Pumps and water distribution
4.Fans and motors
Prepared by: Mohammad Shoeb Siddiqui

38. Theheatloadimposedonacoolingtoweris
determinedbytheprocessbeingserved
Inmostcases,alowoperatingtemperatureis
desirabletoincreaseprocessefficiencyorto
improvethequalityorquantityoftheproduct.In
someapplications(e.g.internalcombustion
engines),however,highoperatingtemperaturesare
desirable
Thesizeandcostofthecoolingtoweris
proportionaltotheheatload
Prepared by: Mohammad Shoeb Siddiqui

39. Minimumcoldwatertemperaturetowhichwatercanbe
cooledbytheevaporativemethod
Thus,thewetbulbtemperatureoftheairenteringthecooling
towerdeterminesoperatingtemperaturelevelsthroughout
theplant,process,orsystem.
Theoretically,acoolingtowerwillcoolwatertotheentering
wetbulbtemperature,whenoperatingwithoutaheatload.
However,athermalpotentialisrequiredtorejectheat,soitis
notpossibletocoolwatertotheenteringairwetbulb
temperature,whenaheatloadisapplied
Thetemperatureselectedisgenerallyclosetotheaverage
maximumwetbulbforthesummermonthswhetheritis
specifiedasambientorinlet
Prepared by: Mohammad Shoeb Siddiqui

40. Rangeisadirectfunctionofthequantityofwatercirculatedand
theheatload.Increasingtherangeasaresultofaddedheatload
doesrequireanincreaseinthetowersize.Ifthecoldwater
temperatureisnotchangedandtherangeisincreasedwithhigher
hotwatertemperature,thedrivingforcebetweenthewetbulb
temperatureoftheairenteringthetowerandthehotwater
temperatureisincreased,thehigherlevelheatiseconomicalto
dissipate.
If the hot water temperature is left constant and the range is
increased by specifying a lower cold water temperature, the tower
size would have to be increased considerably. Not only would the
range be increased, but the lower cold water temperature would
lower the approach. The resulting change in both range and
approach would require a much larger cooling tower.
Prepared by: Mohammad Shoeb Siddiqui

41. Saba Power
Plant Data
Prepared by: Mohammad Shoeb Siddiqui

42. 1 x 4 cell cooling tower
Design data: GEA
Type: Counter flow.
Number of cells: 4
Cell Size (ft x ft)60 x 60.
Overall Length/ Width (ft x ft) 240 x 60.
Distribution type: Up spray.
Snow Load: 0
Design wind velocity: 100 mph.
Prepared by: Mohammad Shoeb Siddiqui

43. Cooling Tower Performance Data:
Water circulation: 58,558 gpm(13300 m³/hour)
Inlet water circulation temperature: 91.4ºF
(33ºC)
Outlet Water Temperature: 71.42ºF (22ºC)
Design wet bulb temperature 62.96ºF (17.2ºC)
Prepared by: Mohammad Shoeb Siddiqui

44. 2 x 100% duty mixed flow centrifugal pumps.
Capacity: 60,000 gpm.
2 x 1000 HP motors use to drive the circulating water pumps
Speed: 500 RPM.
Voltage: 6.6Kv.
4 x cooling tower with induce draft fans.
Speed: 98.3 RPM.
Number of blades: 6 per fan.
4 x cooling tower fan motors.
Speed: 1500 RPM.
Rated capacity:200 HP.
Rated Voltage:415 Volts.
4 x Amarillo gearboxes.
Reduction ratio: 15:1
Prepared by: Mohammad Shoeb Siddiqui

45. 1 x Condenser
Design Data: Made Ecolaire
Steam load: 588,694 LB/HR
Steam Temperature: 100.61
o
F
Heat rejected to circulating water: 555.5161 million BTU/HR.
Effective Tube length: 9398 mm
Effective Condenser surface: 62,462 Sq.Ft.
Circulating water flow: 55,256 gpm
Circulating water inlet temperature: 21.6
o
C
Cleanliness factor: 90%
Average Circulating water velocity in tubes: 7.2 FT/SEC
Absolute Pressure: 50 mm HgA
Circulating water friction loss through clean tubes and water box: 16.22 Ft. of
water.
Number of tubes: 7777
Tubes material: SS-A249 TP 304L, 22BWG
Tubes outer diameter: 25 mm
Prepared by: Mohammad Shoeb Siddiqui

46. BentlyNevada vibration monitoring system (3300 series).
The main components of the cooling tower dosing system are:
1 x Acid storage tank . Capacity 16.5 cubic meters
2 x Acid dosing pumps, Neptune. Capacity 125 lph, 7 kg/cm
2
Motor capacity 1 KW
1 x Anti-scalantdosing tank, Capacity 190 liters
2 x Anti-scalantdosing pumps, Neptune. Capacity 5 lph, 50 kg/cm
2
Motor 1 KW
Prepared by: Mohammad Shoeb Siddiqui

47. 2 x Chlorination booster pumps, Jonson March
Capacity 43.14 m
3
/h, 28 mlc
Motor 5.6 KW, 1,440 rpm
1 x Chlorine evaporator
Capacity 2,727 Kg/day
1 x Chlorinator
Capacity 2,727 Kg/day
2 x Ton chlorine cylinder containers for liquid chlorine
1 x Weigh scale for the chlorine cylinder container
capacity 0 to 1,800 Kg.
Prepared by: Mohammad Shoeb Siddiqui

48. Duringnormaloperation,onecirculatingwaterpumpisin
servicesupplyingapproximately60,000gallonsofwaterat
atemperatureof30ºCandapressureof1.4kg/cm²tothe
Maincondenserandtheclosedcoolingwaterplateheat
exchangers.
Thecirculatedwatermakestwopassesinthecondenser.
Waterentersthecondenserwaterboxinletandflows
throughthetubesintothereturnwaterbox,andthen
throughthesecondsetoftubesandintotheoutlet
waterbox.
Asthecirculatingwaterflowsthroughthetubes,theexhaust
steamthermalenergyistransferredtothecirculating
water.Rapidcondensationofthesteamoccursanda
vacuumiscreatedinthecondenser.
Prepared by: Mohammad Shoeb Siddiqui

49. Theheatedwaterreturnstothetopofthecoolingtowervia
fourpiperisersandintoahorizontaldistributionheader
pipe.Fromthere,itbranchesintoasystemoflateral
distributionpipes,wherethenozzlesspraythewater
downwardinapredeterminedpatternovertheheat
exchangemedium,orfill.
Beforetheairflowispermittedtoexitthroughthetopofthe
tower,itmustpassthroughthedrifteliminators.The
shapeofthismaterialcausestheairtochangedirections
andthusprovidesimpactsurfaceswhichpreventwater
dropletsfrombeingcarriedoutofthetowerwiththeair
flow.
Thecoldwaterbasinofthecoolingtowercatchesthefalling
water,whichthenflowsbacktothecirculationpumps.
Prepared by: Mohammad Shoeb Siddiqui

50. Asthisprocesstakesplace,asmallpercentageofwaterislossdue
toevaporation.AmbienttemperatureandRelativeHumidity
alsoaffecttherateofevaporation.Thecoolwateristhen
recirculatedtotheusers.
Whenthewaterevaporatesinthecoolingtoweroperations,mostof
thedissolvesolidsremainbehindinanon-evaporativestate.If
theratiooftheseconcentrationsbecomeexcessivelyhigh,scale
anddepositswillformintheMaincondensertubesandother
piping.Thiswilldrasticallyaffecttheefficiencyofthe
condenser,whichwillinturncauseahighbackpressureforthe
steamturbine.
Toreducetheamountoftotaldissolvesolids(TDS)inthesystem,
blowdownisrequired.Theoperating(TDS)rangeisblow(3500
PPM).Coolingtowermakeupisthereforenecessarytoreplace
thewaterlosscausedbyevaporation,blowndown,windageand
carryover.
Prepared by: Mohammad Shoeb Siddiqui

51. WATERTREATMENT
Coolingtowermaintenancecanbe
veryhighunlessthewateristreated
topreventcorrosion,biological
growth,anddeposits.Water
treatmentalsoprotectsthecooling
towerwoodfromchemicalattack.
Prepared by: Mohammad Shoeb Siddiqui

52. WATERTREATMENT
Duetotheevaporationthattakesplaceinthecooling
tower,thedissolvedsolidsinthewaterbecome
concentrated.Theevaporatedwatermustbereplacedby
makeupwater.Thecirculatingwaterbecomesmore
concentratedthanthemakeupwaterduetothis
evaporationloss.Thecycleofconcentrationistheterm
appliedtoindicatethedegreeofconcentrationofthe
circulatingwaterwiththemakeupwater.Somewaterof
thecoolingtowerisalsolostduetowindordriftloss,this
isthelossoffinedropletsofwaterthatarecarriedawayby
thecirculatingair.Inmechanicaldrafttowers,0.1%to0.3
%windlossesarepossible.Thewatertreatmentprocess
playsavitalroleinthecoolingtoweroperation.
Prepared by: Mohammad Shoeb Siddiqui

53. WATERTREATMENT
Calciumbicarbonatewhichisnormallypresentin
rawwater,breaksdowntoformrelatively
insolublecalciumcarbonate.Calciumcarbonate
scaleisthemostcommontypeofwaterformed
depositsinacoolingsystem.TheLanglierIndex
measuresthetendencyofCaCO
3toprecipitate
undergivenconditionsofcalciumhardness,
alkalinity,pH,temperatureandtotaldissolved
solids.Apositiveindexmeansthatwaterwilltend
todepositscalewhileanegativeindextendsto
dissolvescale.
Prepared by: Mohammad Shoeb Siddiqui

54. WATER TREATMENT
The Saba Power Plant cooling water system has
three (3) dosing systems.
Sulfuric acid dosing
Anti-scalant dosing
Chlorination injection
Prepared by: Mohammad Shoeb Siddiqui

55. WATER TREATMENT
Sulfuric Acid Dosing System
Chemical treatment with sulfuric acid
keeps the scale forming salts of calcium
and magnesium in solution by lowering
the pH of the circulating system. At Saba,
the pH is controlled between 7.8 to 8.5.
Prepared by: Mohammad Shoeb Siddiqui

56. Anti-scalantDosingSystem
Chemicalinhibitorsareneededtocheckcorrosion.Surface
activechemicalsorchelatingagentssuchassodium
hexametaphosphatepreventcrystalgrowth&
thereforescaleformation.Ineffect,theyincreasethe
solubilityrangeofscaleformingsalts.Controlledscale
treatmentadjuststhecompositionofwatersothata
thinimperviouslayerofcalciumcarbonatescale
depositsonthesurfaceofthecirculatingwatersystem.
Thescalemustbethickenoughtopreventany
corrosion,butthinenoughnottoeffecttheoverallheat
transfer.
FortheAnti-scalantdosingsystem,thereisonedosing
tankof220litterscapacitywithtwodosingpumps.
Prepared by: Mohammad Shoeb Siddiqui

57. Chlorination System
Microbiological growth, slimes & algae,
retard cooling, cut cooling efficiency and
increases the maintenance cost of the
cooling system. When growth breaks
loose, it will clog pipelines, pumps &
equipment. Mechanical cleaning is the
best way to get rid of accumulated
growths. But to keep slime & algae from
getting a toehold in the first place,
chlorine gas is used.
Prepared by: Mohammad Shoeb Siddiqui

58. Precautions,
Limitations and
Setpoints
Prepared by: Mohammad Shoeb Siddiqui

59. Beforestartinganycirculatingwaterpump(CW-PP-1/2),
verifythatallfour(4)riserisolationvalvestothedistribution
headeratthecoolingtower,arefullyopened.
Thecirculatingwaterpumps(CW-PP-1-2)motorsarelimited
tothenumberofstarts,dependingontheexistingconditions.
Thislimitationisdesignedtoprotectthestatorandrotorfrom
excessiveheatthatisgeneratedfromthehighinrushcurrent
whenamotorisstarted.Ifthemotorisinacoldcondition
(standby),three(3)consecutivestartsareallowed.Ifthe
motorwasrunningandachievednormaloperating
temperature,themotorwillbelimitedtotwo(2)consecutive
starts.Ifthenumberofstartsisexceeded,theIQ-1000whichis
thesupervisoryinstrumentationlocatedontherespective
motorbreakerswill“lockout”themotortoinhibitarestart.
Thenumberofstartsshouldnotaveragemorethansix(6)
startsperday.
Prepared by: Mohammad Shoeb Siddiqui

60. Thecirculatingwaterpumps(CW-PP-1-2)areequippedwith
temperaturesensingdevices(TE-1028A-JforCW-PP-1and
TE-1031A-JforCW-PP-2)thatcontinuouslymonitorthe
motorbearingandwindingtemperatures.Ifanywinding
temperaturesexceeds170°Canalarmwillannunciateonthe
DCS(TAH-1028A-FforCW-PP-1andTAH-1031A-FforCW-
PP-2)andifthewindingtemperatureexceeds180°Cthe
respectivemotorwilltripandanalarmwillannunciateonthe
DCS(TAHH-1028A-FforCW-PP-1andTAHH-1031A-Ffor
CW-PP-2).
Ifanymotorbearingtemperatureexceeds90°C,analarmwill
annunciateontheDCS(TAH-1028G-JforCW-PP-1andTAH-
1031G-JforCW-PP-2)andifbearingtemperatureexceeds
95°Ctherespectivemotorwilltripandanalarmwill
annunciateontheDCS(TAHH-1028G-JforCW-PP-1and
TAHH-1031G-JforCW-PP-2).Prepared by: Mohammad Shoeb Siddiqui

61. Acirculatingwaterpump(CW-PP-1-2)willbeprohibited
fromstartingifthedischargemotoroperatedvalve(MOV-
2007,MOV-2009)isopen.Thisrequirementistopreventsthe
motorfromoverloadingandalsopreventthesystemfroma
suddenshock,whichwillresultifthesystemisrapidly
pressurized.
Duringnormaloperation,onecirculatingpump(CW-PP-1or
2)willbeinserviceandonewillbeinthestandbymode.The
dischargeMOV-2007and2009controllersmustbeinthe
AUTOmode.IfAUTOmodeisnotselectedwhenthepumpis
running,analarmwillannunciateontheDCS(PUMPIS
RUNNING andVALVEISNOTINAUTO).Thestandby
pumpmustbeintheAUTOmodeintheeventthatthe
runningpumpfailsandthestandbypumpwillstart
automatically.
Prepared by: Mohammad Shoeb Siddiqui

62. Alowlevelinthecoolingtowerbasinwillannunciateon
theDCS(LAL-1036)towarnthecontrolroomOperator.
TheLowlevelalarmissetat–700mm.Notethatthis
alarmgetsitssignalfromthecoolingtowerbasinlevel
transmitter.
Alowlowlevelinthecoolingtowerbasinwilltripthe
pumpthatisinserviceandannunciateontheDCS
(LALL-1004).Thelevelswitch(LSLL-1041)issetat–800
mm.
Alowpressswitch,(PSL-1005)islocatedonthe
circulatingwaterheader,ifthisswitchdetectsalow
pressure<1kg/cm²>,thestandbypumpwillstartandan
alarmwillannunciateontheDCS(PAL-1005).
Prepared by: Mohammad Shoeb Siddiqui

63. Allfour(4)coolingtowerfangearboxes(CT-FN-1-4)are
providedwithvibrationmonitoringinstrumentation(VE-
1050A-D),thatwillgenerateanalarmontheDCS(VAHor
VAHH-1050A-D)iftherespectivevibrationsupervisory
circuitdetectsaHiorHiHivibrationonthefangearbox.The
HiandHiHivibrationalarmissetat0.075in/sec.and0.1
in/sec.respectively.
Allfour(4)ofthecoolingtowerfangearboxesareprovided
withtemperaturemeasuringdevicesthatwillgeneratean
alarmontheDCS(TAH-1051A-D)ifthetemperatureexceeds
100ºCandiftemperatureexceeds111ºC,thefanwilltrip.
Prepared by: Mohammad Shoeb Siddiqui

64. SulifuricAcid
Sulfuricacidmistbeginstoirritatetheeyes,noseandthroatat
0.5mg/m
3
;thethresholdlimitvalueof1mg/m
3
may
corrodeteeth,withfrequentexposure.Sulfuricacidismore
irritatinginahighhumidityenvironment.Liquidsulfuric
acidwillburnskinandeyesanditwilldeeplyburnthe
stomachandthroatifswallowed.Sulfuricacidisnon-
flammablebutreactsviolentlywithwaterandorganic
materials.Poisonousgasmaybeproducedinafire.
Flammablehydrogengasmaybeproducedatacidfacilities.
Firefightersshouldwearprotectiveequipmentwhen
exposedtosuchconditions.
LowLowlevelswitchesareprovidedinthesulfuricacidand
Anti-scalantdosingtanks,theseswitcheswilltripthepump
andwillannunciateontheDCS,whenactuated.
Prepared by: Mohammad Shoeb Siddiqui

65. Chlorine
Chlorineisknownasapotentialdangertoworker
health.Chlorinecausesirritationoftheeyes,nose,
throatandlungs.Exposuretoasufficientlyhigh
concentrationofchlorinewillbefatal.Chlorinegas
exhibitsasharppungentodor.Therefore,its
presenceisreadilydetectedanditisunlikelythat
anyonecouldremaininacontaminatedarea.
Fortunately,chlorinegasdoesnotproducea
cumulativephysiologicaleffectandcomplete
recoverywilloccurfollowingmildexposure.
Prepared by: Mohammad Shoeb Siddiqui

66. Thephysiologicaleffectsofchlorineare;
detectableodorat3.5ppm,throatirritationat
15.1ppm,coughingat30.2ppmandextreme
dangerin30-60minutesat40-60ppm.The
characteristicpenetratingodorofchlorinegas
giveswarningofitspresenceintheair.Its
greenishyellowcolormakesitvisiblewhen
highconcentrationsarepresent.Thehandling
anduseofbothliquidandgaseouschlorine
requirecloseattentiontosafetyprecautions
andpractices.
Prepared by: Mohammad Shoeb Siddiqui

67. ○Gas masks for chlorine protection are available at;
○The closed cooling water pump area/green box
○The air heater washing basin /green box
○The firewater foam tank /green box
○The raw water building, north wall/green box
○The main control room, SCBA is also available in
the control room
Prepared by: Mohammad Shoeb Siddiqui

68. (If a chlorine ton/cylinder container develops a leak, its contents
are disposed of by placing it in position for gas withdrawal
and bubbling the gas into the neutralization bath as describe
below.)
1.4 pounds of Caustic Soda (NaOH) is required for neutralization
of one pound of Chlorine.
3.7 pounds of Soda Ash (Na
2CO
3) is required for neutralization of
one pounds of Chlorine.
1.3 pond of Hydrated Lime [Ca(OH)
2] is required for neutralization
of one pounds of ch
Prepared by: Mohammad Shoeb Siddiqui

69. Therearetwo(2)chlorineleakdetectorsinstalledatthe
chlorinationcontrolroombuilding,oneinsidethe
chlorinationroomandtheotherattheton/cylinder
containerskidarea.Theseleakdetectorswillgivea
ChlorineleakalarmattheDCSandstartthe
strobe/hornattheChlorinationcontrolroombuilding.
Twowindsocksareprovidedintheplanttoestablish
thewinddirectionincaseofachlorinegasleak.
Personnelshouldcheckthedirectionofthesewindsocks
beforerushingtofixtheleak.
Note
Don’trushintheoppositedirectionofthewind
Prepared by: Mohammad Shoeb Siddiqui

70. Chlorine
TheControlPanel:
Thecontrolpanelcontainsalltheequipmentrequiredto
operatethechlorinationsequence.Aprogrammable
timercanbeprogrammedtocontrolthechlorination
processautomatically.
TheSystemControlPanelAlarmLightsareasfollows;
Chlorineevaporatorlowwaterlevel
Chlorineevaporatorwatertemperaturehigh
Evaporatorwatertemperaturelow
Liquidchlorinemanifoldpressurelow(2.8Kg/cm
2
)
Prepared by: Mohammad Shoeb Siddiqui

71. Chlorine
Expansionchamberpressurized(2.8Kg/cm
2
)
Evaporatordischargepressurereliefvalve(2.8Kg/cm
2
)
Evaporatordischargepressurehigh(17.6Kg/cm
2
)
Evaporatordischargegastemperaturelow
Filterexitlowpressure(4.2Kg/cm
2
)
Ejectorpressuresupplylow
Boosterpumpsdischargepressurelow(3.9Kg/cm
2
)
Boosterpumpssuctionpressurelow(1.05Kg/cm
2
)
Chlorinatorvacuumlow
Chlorinatorvacuumhigh
Prepared by: Mohammad Shoeb Siddiqui

72. The purpose of starting this system is to provide cooling
water to the following users.
1.Main condenser.
2.Plate heat exchangers.
3.Chlorination booster pumps.
The following support systems should be aligned so that
they may be placed in service when required.
Acid injection system
Anti scalantinjection system
Chlorination system
Water Well pumps and raw water system
Startup
Prepared by: Mohammad Shoeb Siddiqui

73. The normal operating level is (-325 mm). If filling of the basin is
required, verify on the DCS that the raw water tank level is
at normal operating level of 12 meters as indicated on (LT-
1505) and the water well pumps are in auto. Place the level
control valve (MOV-1521) in <Manual> and commence
filling the basin by giving the controller a 25% output, this
will allow water to flow by gravity from the raw water tank
to the cooling tower basin.
Note
The water well pumps will only start when the raw water tank
level drops to 3.5 meters.
Verify that the Low and Low Lowlevel (LAL-1036 and LALL-
1040) alarms are cleared, “normal” status, as indicated on the
DCS alarm summary and also have the field operator verify
the actual level.
Prepared by: Mohammad Shoeb Siddiqui

74. Once the normal operating level of the cooling tower basin is
established, verify that all the permissive are satisfied, Proceed
to start the CW pump .
The field operator should verify that the circulating water pump
discharge motor operated valve (MOV-1007 or 1009) opens to
approximately 25%. When the system is pressurized > 1
Kg/cm², the discharge MOV should continue to open, when
the valve is fully open the valve indication on the DCS will
change color from green to red. If the valve fails to open , the
valve is provided with a hand wheel that can be used to open
the valve. In order to open the valve locally through the motor,
the field operator will have to switch from REMOTE to LOCAL
control.
The field operator must check the pump and motor for abnormal
noise and vibration. If any abnormal noise or vibration is
detected, immediately shutdown the pump and inform the
Shift Supervisor.
Prepared by: Mohammad Shoeb Siddiqui

75. The system should be vented once circulation is established.
The high point vents (GW-GA-06, GW-GA-07 and GW-GA-08)
are located on the Main condenser water box inlet, outlet and
return respectively.
Align and place the plate heat exchangers in service as
required.
Check the gearbox oil level before starting the cooling tower
fans. Cooling tower fans will be started as required to control
the circulating water temperature. Proceed to start the cooling
tower fans
Start and maintain the circulating water chemistry as per the
Plant Chemistry Manual.
Place the Blowdownsystem in service by opening (CW-GA-01)
as required to control the Total Dissolve Solids (TDS) as per the
Chemistry manual.
Prepared by: Mohammad Shoeb Siddiqui

76. Acid dosing system
Align all the valves per procedure.
Align all the electrical breakers as per procedure.
Make sure that the acid storage tank level is notlow.
Start the Acid dosing pump A or B from DCS
Anti-scalantdosing system
Align all the valves per procedure.
Align all the electrical breakers as per procedure.
Make sure that the acid storage tank level is notlow.
Start the Acid dosing pump A or B from DCS
Prepared by: Mohammad Shoeb Siddiqui

77. Chlorination System
Close the drain valves in the water piping system and open all
shutoff valves in the water supply line to the water supply piping
system.
Fill the water chamber to the operating level, as confirmed by
water being discharged to the drain through the open drain
connection in the rear of the evaporator. Observe the sight glass to
check the water level.
When the chamber is filled to the operating level, gradually close
the throttling valve.
Apply 120 V. ac power to the control circuit connection box.
Observe the position of the indicating pointer of the cathodic
protection ammeter; turn the adjustment screw of the
potentiometer, if necessary, to bring the pointer just within the
lower portion of the green band on the scale. If the reading in the
green portion of the scale cannot be achieved, this is indicative that
the conductivity of the water is too low to permit a sufficient flow
of protection current. In such instances, it will be necessary to
increase the conductivity by adding sodium sulfate or magnesium
sulfate to the water via the standpipe provided for this purpose in
the top of the water chamber.
Prepared by: Mohammad Shoeb Siddiqui

78. Chlorination System
Set the water temperature control to 155 oF, the high temperature
control to 170 oFand the low temperature control to 140 oF.
Energize the immersion heater by closing the circuit breaker in the
power supply line to the heater. While the Evaporator is warming
up, leak test all piping.
Inspect all joints in the liquid chemical supply and the gas
discharge lines to ensure that the joints are tight.
Verify that the blow-off valve in the bypass line is closed.
To test for leaks, open all in-line valves between the liquid
chemical supply valve and the gas dispenser, including the valve
in the bypass line around the electrically operated pressure
reducing and shut-off valve, to provide a path around the de-
energized valve.
Prepared by: Mohammad Shoeb Siddiqui

79. CAUTION
Do not open the header valve that is closest to the chemical supply
WARNING
Damaging or breaking of the chemical piping, valves or fittings can
cause a major hazardous chemical spill. Never tighten or adjust
any leaking fitting when the chemical supply cylinder valve is
open.
WARNING
When system leaks occur, the procedures required to find these
leaks may cause exposure to hazardous chemicals at levels that
exceed the Occupational Safety and Health Administration
(OSHA) limits.
Prepared by: Mohammad Shoeb Siddiqui

80. Cooling Towers
THANK YOU
FOR YOU ATTENTION
Prepared by: Mohammad Shoeb Siddiqui