This Project Is Done Over ONGC Hazira Plant At Phase-I Cooling Tower.In This Slide Show,We Want To Give You Some New Ideas About Equipment Like Fills,Drift Eliminator,Storage Tank,ect.

1. PROJECT
PRESENTED BY:- Abhimanyu Meena
Karan Manek
Mayur Solanki
Mohamed Zaid Afzal
STUDENT OF: – CHEMICAL ENGINEERING DEPARTMENT,
SVNIT, Surat.
MENTOR:- Mr.CHANCHLESH KABRA

2. ACKNOWLEDGEMENTS
Industrial Training is an integral part of engineering curriculum providing engineers with first
hand and practical aspects of their studies. It gives us the knowledge about the work and
circumstances existing in the company.
It gives us great pleasure to have completed my project at Gas Processing Plant of
ONGC at Hazira and submitting the project report for the same.
I express my deep sense of gratitude to Mr.CHANCHLESH KABRA for giving me the
project on cooling tower.
My sincere thanks to Mrs. D. SWAROOPA, E.E. (P)-RE CELL, ONGC Hazira for allotting me
appropriate schedule, guiding me through various aspects, functioning and processing of
plant, and giving their effective coordination for undertaking the training.
I thank Oil and Natural Gas Corporation Limited, Hazira for giving me an opportunity to
have an industrial exposure under the guidance of the experts. I also thank all of them who
have directly or indirectly helped us during the tenure of our training.
Sincerely thanking all of the above once again, we hope to continue to take the guide
from the aforementioned in near future. It has been a great experience for me.

3. Abstract
The main purpose of the project is to work on cooling tower of ONGC Plant , Hazira . The
total number of cooling tower are four.
There are two types of cooling tower in ONGC Plant.
a) Induced counter flow
b) Induced cross flow
The more efficient is induced cross flow as compare to the counter flow.
The number of towers are four in which one is induced counter flow (Phase II) and three
are induced cross flow(Phase I , Phase III , Phase III(A)).
The project is based on the induced cross flow (Phase I).
The height of tower is 50 meters.
Mild steel are been used in most of the piping.
Stainless steel is used for acid pass piping.

4. Cooling Tower
1.1.Cooling Towers for Refrigeration
An importantdevice usedinanyrefrigerationorairconditioningsystemisacondenser.A condenser
isusedin the highpressure side of arefrigerationorairconditioningsystemtoconvertthe high-
pressure vapourrefrigerantfromthe compressorintoliquidrefrigerant.The mediumusedina
condensermaybe wateror air, dependinguponthe application.Inthe case of watercooled
condensers,the warmwaterbeingpumpedbythe condensershouldbe cooledwiththe helpof
coolingtowerssothat the same watermay be re-circulatedtothe condenser.
1.2 Principle of Operation for Cooling Towers
The principle of operationof coolingtowersisverysimilartothatof the evaporative type of
condensers,inwhichthe warmwatergetscooledbymeansof evaporation.Waterevaporatesasa
resultof the hot waterdropletcomingincontact withthe air (whichisbeingpumpedoutbymeans
of a fan).Thisevaporatingwateralsoabsorbsthe latentheatfromthe watersurroundingit.By
losinglatentheat,the wateriscooled.
1.3.Classification Of Cooling Tower
1.4TYPES OF COOLING TOWER
1.4.1.Natural Draft Cooling Towers
->Hot air movesthrough tower
->Freshcool air isdrawn intothe towerfrombottom
->Nofan required
->Concrete tower<200 m
->Usedfor large heatduties

5. 1.4.2.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. 8-cell tower
1.4.3.Types Of Mechanical Draft Cooling Tower
(A) Forced Draft
(B) Induced Draft Cross Flow
(C) Induced Draft Counter Flow
(A) Forced Draft Cooling Towers
Air blown through tower by centrifugal fan at air inlet
Advantages:-suitedforhighairresistance &fansare relativelyquiet
Disadvantages:- recirculationdue tohighair-entryandlow air-exitvelocities
(B) Induced Draft Cross Flow
=>According To Flow Direction,There is Tow Types:
(A)Induced Draft Cross flow Tower (B)Induce Draft Counter flow Tower

6. (A)Induced Draft Cross flow Tower (B)Induce Draft Counter flow Tower
->Hot waterentersat the top ->Waterenterstopand passesoverfill
->Airentersat bottomand exitsattop ->Airentersonone side or opposite sides
->Usesforcedand induceddraftfans ->Induceddraftfandraws airacross fill
Advantage : less recirculation than forced draft towers
Disadvantage : fans and motor drive mechanism require weather-proofing.
1.8.We Need To Maintain 16 Parameters
(1) PH Balance:- Maintain7to 8 (9) Free Chlorine
(2) Conductivity:- Maximum2000 (10) Total Phosphate
(3) Total Hardness:- Maximum350 (11) Ortho Phosphate
(4) Calcium Hardness (12) Inorganic
(5) Magnesium Hardness (13) Organic
(6) P-Alkality:- Most ProbablyNill (14) TDS
(7) M-Alkality:- MostProbablyNill (15) Zinc
(8) Total Chlorides (16) Turbidity

7. 1.9.MEASURED PARAMETERS
(A) Wet bulb temperature of air
(B) Dry bulb temperature of air
(C) Cooling tower inlet water temperature
(D) Cooling tower outlet water temperature
(E) Exhaust air temperature
(F) Electrical readings of pump and fan motors
(G) Water flow rate
(H) Air flow rate
1.5.Cooling Tower ConstructionMateria
1.5.1.Fills
In a coolingtower,hotwaterisdistributedabove fill mediawhichflowsdownandiscooleddue to
evaporationwiththe intermixingair.Airdraftisachievedwithuse of fans. Thussome poweris
consumedinpumpingthe watertoa heightabove the fill andalsobyfanscreatingthe draft.
An energyefficientorlowpowerconsumingcoolingtoweristohave efficientdesignsof fillmedia
withappropriate waterdistribution,drifteliminator,fan,gearbox andmotor.Powersavingsina
coolingtower,withuse of efficientfill design,isdirectlyreflectedassavingsinfanpower
consumptionandpumpingheadrequirement.
Heat exchange betweenairandwaterisinfluencedbysurface areaof heatexchange,time of heat
exchange (interaction)andturbulence inwatereffectingthoroughnessof intermixing.Fill mediaina
coolingtowerisresponsible toachieve all of above.
=> Splash and Film Fill Media: As the name indicates,splashfill mediageneratesthe
requiredheatexchange areabysplashingactionof wateroverfill mediaandhence breakinginto
smallerwaterdroplets.Thus,surface of heatexchange isthe surface areaof the waterdroplets,
whichisin contact withair.
=> Film Fill and its Advantages : In a filmfill,waterformsathinfilmoneitherside of fill
sheets.Thusareaof heatexchange 7.CoolingTowerBureauof EnergyEfficiency144 isthe surface
area of the fill sheets,whichisincontactwithair.Due tofewerrequirementsof airand pumping

8. head,there isa tremendoussavinginpowerwiththe inventionof filmfill.Recently,low-clogfilm
fillswithhigherflute sizeshave beendevelopedtohandle highturbidwaters.Forseawater,low
clog filmfillsare consideredasthe bestchoice intermsof powersavingandperformance compared
to conventional splashtype fills.
Examples:-PVC Honeycombed : ThisIs FilmFill systemdesignedtosignificantlyreduce the
riskof biological foulingwithoutsacrificinghighperformance heattransfer.
The filmfill isabottomsupportlow-cloglogfill configuration.Open,angularcrosscorrugations
allowdebrisandbiologicalgrowthfoulanttopass,while providingmaximumsurface areaand
turbulence todevelopefficientheattransfer.Texturingcreatesthermal capabilityimprovementwith
little effectonfouling.The fillsofferslow pressure dropinanaerodynamic,durable design.
Product Code: PFT-001050
Product Code: PFT-001052 Product Code: PFT-001050 Product Code: PFT-001061
Product Code: PFT-001072 Product Code: PFT-001073 Product Code:PFT-001202

9. Parameters Splash Fill Film Fill Low Clog Film Fill
Possible L/G Ratio 1.1 – 1.5 1.5 – 2.0 1.4 – 1.8
Effective Heat Exchange
Area
30 – 45 m2/m3 150 m2/m3 85 - 100 m2/m3
Fill Height Required 5 – 10 m 1.2 – 1.5 m 1.5 – 1.8 m
Pumping Head
Requirement
9 – 12 m 5 – 8 m 6 – 9 m
Quantity of Air Required High Much Low Low
1.5.2.Drift Eliminators
Application : These capture waterdropletsentrappedinthe airstreamthat otherwise wouldbe
lostto the atmosphere.
PERFECT offersDriftEliminators, made outof rigidPVC,are designedtoremove entrainedparticles
fromair steamefficiently,withminimumpressure drop,therebyreducingthe fanpower
requirementwhenthe airpassesthroughthe DriftEliminator.
Water dropletsare separatedfromthe air driftat the three directionchange pointsonthe drift
eliminator.Ourdrifteliminatorprovidesacellularruggedstructure withaverylow pressure drop.
Thisresultsinhighdrifteliminationefficiencywhile exertingminimumdrivingforce onfan.
http://www.perfectcoolingtowers.com/PVC%20HONEYCOMB%20FILLS.html

10. 1.5.3.Sprinklers
Application : To DistributesHotWaterOverEntire Space Of Fillers.
Product Code :PFT-002035 Product Code:PFT-002060 Product Code:PFT-002140
Product Code:PFT-002020 Product Code:PFT-002030 Product Code:PFT-002050
Perfect offers cooling tower sprinkler with rotary head and sprinkler pipe distributes the hot water over the
entire space of the filler. Sprinkler pipes are non corrosive, require low pressure to operate and assure
uniform water flow with minimal operating pump head.
Consists of a set of sprinkler pipes and one sprinkler head that is mounted on top of the stand pipe on the
cooling tower. The sprinkler is rotated by the pressure of circulating water. There are numerous holes in the
sprinkler pipe to allow the water to jet out as the pump impacts
rotation.http://www.perfectcoolingtowers.com/cooling_tower_sprinkler.html

11. 1.5.4.Nozzel
Application : These provide the water sprays to wet the fill. Uniform water distribution at the top of the
fill is essential to achieve proper wetting of the entire fill surface. Nozzles can either be fixed in place and
have either round or square spray patterns or can be part of a rotating assembly as found in some circular
cross-section towers.
=>High Performance Nozzle
The Variable Flow Nozzle solution is not only simple, but it can be applied to both existing and new cooling
towers. And not just cooling towers: fluid coolers, scrubbers, trickling filters and other water-cooled
equipment. These nozzles are where the rubber meets the road in cooling tower performance. Increase your
cooling tower efficiencey, maximize your towers efficincey. Increase your cooling by 10-20% by simply
using NK-100 series variable flow nozzles.
NK-100 "Non clogging" square pattern spinning nozzle. 2" NPT with insert orifice selections. VariableFlow
NK-101 Square pattern spinning nozzle. 2" NPT
$35.00 each / 2" NPT thread
The Variable Flow Nozzlehas a spring-loaded orifice that automatically opens and closes with
changing water pressure: in other words, the Variable Flow Nozzle doubles as a flow-control valve. That
means you can turn OFF one or more of your cooling tower pumps as the wet bulb or load conditions
dictate. This will conserve enormous amounts of energy.

12. NK-103 1" Variable Flow Nozzle
Square Pattern 3 x 3'
Low pump turn-downwithout loosingnozzle performance. Reducespumpingheadbyas muchas 2'
Acts like its own balancing valve
1.5.5.Louvers : Generally, cross-flow towers have inlet louvers. The purpose of louvers is to equalize air
flow into the fill and retain the water within the tower. Many counter flow tower designs do not require
louvers.
Anti-Splash Louvers Cost 882$ Per Cooling Tower Of 6 Unit.

13. 1.5.6.VibrationIsolators
Application: Use To Reduce Vibration & Noise Control in Cooling Tower.
Vibration isolators for equipment which is subject to load variations and large external or torquing forces
shall consist of large diameter laterally stabile steel springs assembled into welded steel housing
assemblies designed to limit vertical movement of the supported equipment.
Housing assemblies shall be fabricated steel members and shall consist of a top load plate complete with
adjusting and leveling bolts, vertical restraints, isolation washers and a bottom plate with internal non-skid
noise isolation pads. Housing shall be electrozinc plated or hot dip galvanized for corrosion resistance.
Housing should be designed to provide a constant free and operating height within 1/8" (0.06 mm).
Spring elements shall have a lateral stiffness greater than 1.2 times the rated vertical stiffness and shall be
designed to provide a minimum of 50% overload capacity. Non-welded spring elements shall be polyester
powder coated, and shall have a 1000 hr rating when tested in accordance with ASTM B-117.
Springs shall be selected to provide static deflections shown on the Vibration Isolation Schedule or as
indicated on the project documents. Springs shall be color coded or otherwise identified to indicate load
capacity. Vibration isolators shall be Model FLS, as manufactured by Kinetics Noise Control, Inc..>
http://www.kineticsnoise.com/hvac/fls.html

14. 1.5.7.Cooling Tower Motors
The company offers cooling tower motors that are specially designed flange mounted motors in totally
enclosed construction to suit extreme environmental conditions. They are provided with special long shaft
construction with external threaded end to directly mount the fan blades this also helps in the better
cooling of the motor. Motors are compact in design & less in weight to facilitate easy maintenance
Cooling Tower Motors are specially designed ,flange mounted motors in totally enclosed construction to
suit air conditioning & refrigeration industries. They are provided with special long shaft construction with
external threaded end to directly mount the fan blades. This also helps in the better cooling of the motor.
Motors are compact in design & less in weight to facilitate easy maintenance. Cooling Tower Motors
available as standard catalouge designs or as custom built.
The Motor Bearings are sealed with grease for lifetime with seals on shaft to prevent moisture and debris
from getting into the bearing.Provision for horizontal lifting is provided as standard, while vertical lifting for
easy handling of motor during installation can be provided. They are available as standard catalogue designs
or as custom built.> http://www.perfectcoolingtowers.com/cooling_tower_moters.html
Product Code: PFT-004141 ProductCode: PFT-004142 Product Code: PFT-004143
1.5.8.Cooling Tower Fans
=>Fans must overcome system resistance, pressure loss:
->impacts electricity use
->Fan efficiency depends on blade profile
->Replace metallic fans with FBR blades (20-30% savings)
->Use blades with aerodynamic profile (85-92% fan efficiency)

15. =>Fan’s Blade Angle Is Change As Per Season.
->In Winterand rainy seasons, the higher CT fan blade angle resulted in higher power consumption
although the water temperature obtained was lower (which in these seasons, was not required for the
process).
->The blade angle of the cooling tower CT was reduced from 50 0 to 45 0 . This resulted in reduced power
consumption and rationalized air flow. For the Summerseason the blade angle remains the same as
modified but the number of cooling tower cells under operation are increased.
By Using This Concept We Can Consume Financial benefits:
Investment:-none
Annual cost savings:- Rs. 2.12 lakhs or US$ 4923 (= 105,840 kWh X Rs. 2 @ Rs 43/US$) (Energy Efficiency
Guide
for Industry in Asia- www.energyefficiencyasia.org
1.5.9.Filter
Application: Filter At Inlet For Filtering Solid Dust And Feeding It Directly To Shell.
Side stream filtration systems reduce suspended solids and debris in the systemcooling water, which leads
to less fouling in the system. Decreasing suspended solids can also help reduce biological growth in the
system because suspended solids are a good source of food for microbiological organisms.(2% Filter Water
Use In Process)
1.5.10.Slump Level Maintain Techniques
There Is Two Types Of Techniques Use To Control Slum Level:
(1) Manually: By Using Of Simple Bypass Control Valve Fluid Flow & Other Person See The Slum Level.At
Required Slum Level Flow Stop Or Reduce It Manually.
(2) PneumaticControl Valve : By Using Of Special Type Of Automatically Control Valve Here We Automatically
Slum Level Is Adjust.Here As Slum Level Is Decrease,Valve Automatically Open & Adjust It.
Here At ONGC Process We Have To Maintain 75m3 Slum Level.
1.5.12.Mixing Tank
->In Mixing Tank All Chemical Mix As Per Required.
->Must Be Non-Corrosive Wall Of Mixing Tank Requires.

16. 1.6.TANK DETAILS (CAPACITYIN M^3)
(A) H2SO4
TYPE l
C.T
I II III III A
MAIN
STORAGE
(H2) (Vt)
18.6 7.85 7.85 7.85
DOING 0.78 0.78 0.78 0.78
(B)CHEMICALS (SHMP, HEDP, ZNSO4) DOSINGTANK
=>CHEMICALS DETAILS
SR.NO NAME MEANING FORM PURPOSE
1. HEDP HYDROXY
ETHYLINE DI-
PHOSPHONIC ACID
LIQUID ANTI SCALE
FORMATION & FREE
FLOW CREATION
2. SHMP SODIUM HEXA
META PHOSPHATE
SOLID ANTI-CORROSIVE
LAYER
3. ZnSO4 ZINC SULPHATE SOLID ANTI-CORROSIVE
LAYER
4. H2SO4 SULPHURIC ACID LIQUID TO MAINTAINPH LEVEL
5. Cl2 CHLORINE GAS TO KILL ALGAE,
BACTERIA & FUNGUS
I II III III A
3.2 1.0 1.0 1.0

17. 1.7.Make Up Water
As water evaporates in a cooling tower system, the water vapor enters the atmosphere while any dissolved solids
remain behind, building concentration in the remaining water.
Most water treatment systems control this concentration by bleeding off the high concentration water, which is
made up by fresh city water with a lower solid concentration. The amount of water that is bled off by the water
treatment system is usually less than or equal to the amount of water that evaporates.
=>To compensate the water loss due to:
1. Evaporation,
2. Drift (water entrained in discharge vapor), estimated to be About 0.2% of water supply
3. Blow down (water released to discard solids).
1.8.Chlorine Leakage:
There Is Three Types Of Leakage Occurs:
(A) Body Leakage:On The Surface Of Tank,If Leakage Is Occurs Than By Using Of Liquid Ammonia We Detected
Leakage
(B) Valve Leakage: At Valve of Chlorine Tank These Type Of Leakage Occurs.
(C) Plug Leakage: At Any Plug Of Chlorine Tank Or Process Its Occurs.
=>Chlorine Leakage Detection Absorption System with Neutralization
Chlorine Leakage Detection Absorption System with Neutralization support provided works as safety device
that assists in reducing risk of spreading of chlorine gas into atmosphere. The system works by automatically
absorbing/controlling heavy leaks from 100 kg/from 900 kg ton containers and absorb in caustic solution that
allows creation of hypo chlorine which can be reused/used as cleaning agent. The neutralizing system comprises -
->Blower
->Absorption tower packed with ranching rings
->Alkali (NaOH) tanks
->Alkali circulation pump
->Piping valves
->Light weight FRP & PVC duct

18. We Use Chlorine Neutralization System Compostion:
Caustic + Water
(40%) (60%)
1.9.Termidology Of Cooling Tower
Drift - Water droplets that are carried out of the cooling tower with the exhaust air. Drift droplets have the same
concentration of impurities as the water entering the tower. The drift rate is typically reduced by employing
baffle-like devices, called drift eliminators, through which the air must travel after leaving the fill and spray zones
of the tower.
Blow-Out - Water droplets blown out of the cooling tower by wind, generally at the air inlet openings. Cooling
water may also be lost, in the absence of wind, through splashing or misting. Devices such as wind screens,
louvers, splash deflectors and water diverters are used to limit these losses.
Plume - The stream of saturated exhaust air leaving the cooling tower. The plume is visible when water vapor it
contains condenses in contact with cooler ambient air, like the saturated air in one's breath fogs on a cold day.
Under certain conditions, a cooling tower plume may present fogging or icing hazards to its surroundings.
Note that the water evaporated in the cooling tower operation process is "pure" water, in contrast to the very
small percentage of drift droplets or water blown out of the air inlets.
Blow-Down - The portion of the circulating water flow that is removed in order to maintain the amount of dissolved
solids and other impurities at an acceptable level - the higher the TDS concentration, the greater the risk of scale,
biological growth and corrosion.
Approach - is the difference in temperature between the cooled-water temperature and the entering-air wet bulb
temperature. Since cooling towers use an evaporative cooling design, cooling tower efficiency depends on the wet
bulb temperature of the air.
Range - is the temperature difference between the water inlet and water exit.
Fill - Inside the tower, fills are added to increase contact surface as well as contact time between air and water.
Thus they provide better heat transfer. The efficiency of the tower also depends on them. The two most
common types of fill that currently in use are:
(a) Film type fill - causes water to spread into a thin film
(b) Splash type fill - breaks up water and interrupts its vertical progress
The fill may consist of multiple, mainly vertical or sloped, wetted surfaces upon which a thin film of water
spreads (film fill), or several levels of horizontal splash elements which create a cascade of many small droplets
that have a large combined surface area (splash fill).
Recirculation - is a percentage of the hot, humid discharge air entering back into the inlet air stream thereby
increasing the air inlet wet bulb temperature to a value higher than that of the ambient air condition.
http://www.iwc.co.za/Common-Industry-Terms.html

19. 1.10.PERFORMANCE PARAMETERS
(A) Range: Hot Water Temp (Inlet) – Cold Water Temp (Outlet)
(B) Approach: Cold Water Temp (Outlet) - WBT
(C) Effectiveness: Rang / (Range+Approach)
(D) Cooling capacity: The processof coolingiscalledrefrigeration.Refrigerationorcoolingcapacityismeasuredintons.
A water-chillerrefrigerationtonisdefinedas:
1 Ton Refrigeration = 1 TONScond = 12000 Btu/h = 200 Btu/min = 3025.9 k Calories/h = 12661 kJ/h = 3.517 KW
(E) Evaporation loss: 0.00085 x 1.08 x Flow rate (M3/HR) x Range [M3/Hr]
(G) Cycles of concentration: The term used in calculating and determining the amount of bleed is called cycles
of concentration. Cycles can be defined as the number of times the dissolved minerals in the system cooling water
are concentrated versus the level in the raw makeup water.
(H) Blow down losses: Evaporation losses / (COC-1)
(I) Liquid/Gas ratio: Liquid/Gas (L/G)ratio, of a cooling tower is the ratio between the water and the air mass
flow rates.
1.11.Efficient System Operation
(A) Cooling Water Treatment:-Cooling water treatment is mandatory for any cooling tower whether with
splash fill or with film type fill for controlling suspended solids, algae growth, etc.
With increasing costs of water, efforts to increase Cycles of Concentration (COC), by Cooling Water Treatment
would help to reduce make up water requirements significantly. In large industries, power plants, COC
improvement is often considered as a key area for water conservation.
(B) Drift Loss in the Cooling Towers:- It is very difficult to ignore drift problem in cooling towers. Now-a-days
most of the end user specification calls for 0.02% drift loss.
With technological development and processing of PVC, manufacturers have brought large change in the drift
eliminator shapes and the possibility of making efficient designs of drift eliminators that enable end user to
specify the drift loss requirement to as low as 0.003 – 0.001%.
(C) Cooling Tower Fans:- The purpose of a cooling tower fan is to move a specified quantity of air through the
system, overcoming the system resistance which is defined as the pressure loss. The product of air flow and the
pressure loss is air power developed/work done by the fan; this may be also termed as fan output and input kW
depends on fan efficiency. The fan efficiency in turn is greatly dependent on the profile of the blade. An

20. aerodynamic profile with optimum twist, taper and higher coefficient of lift to coefficient of drop ratio can
provide the fan total efficiency as high as 85–92 %. However, this efficiency is drastically affected by the factors
such as tip clearance, obstacles to airflow and inlet shape, etc.
1.12.Cooling Tower Performance
The important parameters, from the point of determining the performance of cooling towers, are:
(1)."Range" is the difference between the cooling tower water inlet and outlet temperature (See Figure)
(2)"Approach" is the difference between the cooling tower outlet cold water temperature and ambient wet bulb
temperature. Although, both range and approach should be monitored, the 'Approach' is a better indicator of
cooling tower performance. (see Figure).
(3)"Approach" is the difference between the cooling tower outlet cold water temperature and ambient wet bulb
temperature. Although, both range and approach should be monitored, the 'Approach' is a better indicator of
cooling tower performance. (see Figure).
(4)Cooling capacity is the heat rejected in kCal/hr or TR, given as product of mass flow rate of water, specific heat

21. and temperature difference
(5)Cycles of concentration (C.O.C) is the ratio of dissolved solids in circulating water to the dissolved solids in
make up water.
(6)Blow down losses depend upon cycles of concentration and the evaporation losses and is given by relation:
Blow Down = Evaporation Loss / (C.O.C. – 1)
(7)Liquid/Gas (L/G) ratio, of a cooling tower is the ratio between the water and the air mass flow rates. Against
design values, seasonal variations require adjustment and tuning of water and air flow rates to get the best
cooling tower effectiveness through measures like water box loading changes, blade angle adjustments.
->Thermodynamics also dictate that the heat removed from the water must be equal to the heat absorbed by the
surrounding air:
where: L/G = liquid to gas mass flow ratio (kg/kg)
T1 = hot water temperature (°C)
T2 = cold water temperature (°C)
h2 = enthalpy of air-water vapor mixture at exhaust wet-bulb temperature (same units as above)
h1 = enthalpy of air-water vapor mixture at inlet wet-bulb temperature (same units as above)
1.13.TOWER PROBLEMS
(A)Scale Deposit
As a water's dissolved solids level increases, corrosion and deposition tendencies increase.
Because corrosion is an electrochemical reaction, higher conductivity due to higher
dissolved solids increases the corrosion rate (see Chapter 24 for further discussion). It
becomes progressively more difficult and expensive to inhibit corrosion as the specific
conductance approaches and exceeds 10,000 µmho.
Some salts have inverse temperature solubility; i.e., they are less soluble at higher
temperature and thus tend to form deposits on hot exchanger tubes. Many salts also are

22. less soluble at higher pH. As cooling tower water is concentrated and pH increases, the
tendency to pre-cipitate scale-forming salts increases.
Because it is one of the least soluble salts, calciumcarbonate is a common scale former in
open recirculating cooling systems. Calciumand magnesium silicate, calciumsulfate, and
other types of scale can also occur. In the absence treatment there is a wide range in
therelative solubility of calciumcarbonate and gypsum, the form of calciumsulfate normally
found in cooling systems.
Calciumcarbonate scaling can be predicted qualitatively by the Langelier Saturation Index
(LSI) and Ryznar Stability Index (RSI). The indices are determined as follows:
Langelier Saturation Index = pHa - pHs
Ryznar Stability Index = 2(pHs) - pHa
The value pHs (pH of saturation) is a function of total solids, temperature, calcium, and
alkalinity. pHa is the actual pH of the water.
With or without chemical treatment of the cooling water, cycles of concentration are
eventually limited by an inability to prevent scale formation.
=>DEPOSITION CONTROL
As noted earlier, there are many contaminants in cooling water that contribute to deposit
problems. Three major types of deposition are discussed here: scaling, general fouling, and
biological fouling.
=>Scale Formation
Scale formation in a cooling system can be controlled by:
->minimizing cycles of concentration through blowdown control
->adding acid to prevent deposition of pH-sensitive species
->softeningthe watertoreduce calcium usingscale inhibitorstoallow operationunder
supersaturatedconditions
(B) Fouling due to presence of silt, dirt, sand etc.
(C) Microbiological growth due to presence of microrganisms ,Algae, fungi
(D) Corrosion of steel parts

23. 1.14.Loss of Water
=>EvaporationRateis the fraction of the circulating water that is evaporated in the
cooling process.
->A typical design evaporation rate is about 1% for every 12.5C range at typical design
conditions.
->It will vary with the season, since in colder weather there is more sensible heat transfer
from the water to the air, and therefore less evaporation.
->The evaporation rate has a direct impact on the cooling tower makeup water
requirements.
=>Drift is water that is carried away from the tower in the form of droplets with the air
discharged from the tower.
->Most towers are equipped with drift eliminators to minimize the amount of drift to a small
fraction of a percent of the water circulation rate.
->Drift has a direct impact on the cooling tower makeup water requirements.
=>Recirculationis warm, moist air discharged from the tower that mixes with the
incoming air and re-enters the tower.
->This increases the wet bulb temperature of the entering air and reduces the cooling
capability of the tower.
->During cold weather operation, recirculation may also lead to icing of the air intake areas.

24. 1.15.SOME PROBLEMS & IT’S REMEDY FOR COOLING TOWERS
Drift/carry-over of
wateroutside the
unit
(1) Uneven operation of
spray nozzles
(2) Blockageofthe fills
(3) Defective or displaced
droplet eliminators
(4) Excessive circulating
waterflow may be due to too
high pumping
head
(1)Adjust & cleanthe nozzle
(2) Eliminate any dirt on the top of
the fill or with suitable chemical
pretreatment
(3) Replace or realignthe
eliminators
(4) Adjust the waterflow-rate by
means of the regulating valves.
Check damage to
the fill
Lack of cooling and
hence increase in
temperatures owing
to increased
temperature range
(1) Water flow below the
design value
(2) Irregular airflow or lack
of air
(3) Recycling of humid
discharge air
(4) Intake of hot air from
other sources
(5) Blockedspray nozzles (or
even blockedwaterpipes)
(6) Scaling of joints
(7) Scaling of the fill pack
(1) Regulatedthe flow by means of
the valves
(2) Ensure adequate clearance
around cooling towers
(3) Check the air descentvelocity
(4) Install deflectors
(5) Clean the nozzles and/or the
Tubes
(6) Wash or replace the item
(7) Clean or replace the material
(washing with inhibited aqueous
sulphuric acid is possible but long,
complex and expensive)

25. 1.16. Safety
(1) Chlorine Leakage Safety
(2) During Chemical Mixing Must Be Wear Gloves, Ear Clips, Goggles ect.
(3) If the volume of decomposing debris exceeds the chemical dosage’s ability to provide
control ,the cooling tower will silently grow dangerous even while chemical dosing
continues.
(4) Keep the cooling tower free of debris and deploy a good water treatment program and
your cooling tower will operate safely and efficiently.
=>Personal Safety
No matter what procedures are adopted in maintaining cooling towers, personal safety
precautions must be integral to the maintenance procedures. Best practices require workers
to wear respirators, gloves and protective clothing to help prevent exposure to bacteria,
especially Legionella.
cooling water doesn’t haveto look dirty tobe dangerous – just because
the water is clear doesn’t mean it’s clean or free of bacteria – Every
cooling tower can harbor bacteria. Always,always takeprecautions
because unless the water is routinely tested for Legionella and other
bacteria,thebacteria will never announceitspresenceuntil it’s too
late.

26. Conclusion:
Components Current Condition RequiredCondition
1.5.1.Fill Media SplashFill Type,V-BarFill MediaIs
Use.AccordingToIts Structure Less
DropletsFormIs Generates.SoThatLess
Heat TransferIsOccurring.Hence
EfficiencyDecrease.
FilmFill Type,Honey CombFill
MediaUse. AccordingTo ItsMore
Layer Structure More Droplets
Form IsGenerates.SoThatLess
Heat TransferIsOccurring.Hence
EfficiencyDecrease.(See Product
Images)
1.5.2.Drift Eliminator Blande Type,WoodMaterial Use To
Catch Water Droplets.
->LessLifetime(20Years).
CellularType,PVCMaterial
Use.PVCMaterial IsMore Efficient
Than Wood.
->Long Life.
1.5.3.Sprinklers Same As Use Same As Use But More Efficient
ProductIs Use Now A Day.(See
ProductImages)
1.5.4.Nozzles RoundType PatternNozzle Use Square Type Variable NozzlesUse
To Increase TowerEfficiency(See
The 1.5.4. Paragraph)
1.5.5.Louvers AsbestosConcrete SheetUse.
->More Cost.
->LessLifetime
Anti-SplashLouversUse.
->LessCost.
->More Liferime.
1.5.6.Vibration
Isolators
No Use In Process. We ShouldUse VITo Reduce
VibrationOccursInCoolingTower.
1.5.7.Motors Same As Use. More EfficientProduct(Show In
Image 1.5.7.)
1.5.8.Fans PropellersType FansUse. FPR CoolingTowerFansShould
Use To Increase Efficiency.
->More Desirable Aerodynamic
Profile OverFull Blade.
->Variable AxialFlow Cooling
TowerFans.
MixingTank NotUse In Process.
ManuallyMixing.
Must Be Done SystematicallyStep
By StepTo Reduce Lumps
FormationOccursBy Solid
Chemical.
ColdStorage Tank Concreate CementTankUse.
->LessLife Time.
->Corrosive InSome Chemials.
->More Costly.
FiberGlassTank Use.
->More Life Time.
->NonCorrosive.
->LessCostly.