Cooling water (CW) system

Prepared by:
Mohammad Shoeb Siddiqui
Senior Shift Supervisor
Saba Power Plant

Cooling water is the water removing
heat from a machine or system. Cooling
water may be recycled through a re-
circulating system or used in a single
pass once-through cooling (OTC)
system. Recirculating systems may
be open if they rely upon cooling
towers or cooling ponds to remove heat
or closed if heat removal is accomplished
with negligible evaporative loss of
cooling water.
Prepared by: Mohammad Shoeb Siddiqui

Industrial cooling towers may use river water, coastal water
(seawater), or well water as their source of fresh cooling
water. The large mechanical induced-draft or forced-draft
cooling towers in industrial plants continuously circulate
cooling water through heat exchangers and other equipment
where the water absorbs heat. That heat is then rejected to
the atmosphere by the partial evaporation of the water in
cooling towers where upflowing air is contacted with the
circulating downflow of water. The loss of evaporated water
into the air exhausted to the atmosphere is replaced by
"make-up" fresh river water or fresh cooling water. Since the
evaporation of pure water is replaced by make-up water
containing carbonates and other dissolved salts, a portion of
the circulating water is also continuously discarded as
"blowdown" water to prevent the excessive build-up of salts
in the circulating water.Prepared by: Mohammad Shoeb Siddiqui

Cooling
Tower
Condenser
CW
Pumps
CTF
From Bore Wells
CT Makeup
Ambient Condition
Temp. 27.5 oC
Humidity 88.5 %
CW I/L
Temp.
30 oC
CW O/L
Temp. 45 oC
Air flow
Air flow
Raw & Fire
Water Tank
Capacity
2155 m3
CCW Heat
Exchanger

Condenser:
The condenser is the most important component of the turbine cycle that
affects the turbine heat rate. The function of the condenser is to condense
exhaust steam from the steam turbine by rejecting the heat of evaporation to
the cooling water passing through the condenser. Generally, twin shell-
double pass- surface type condensers are employed for higher capacity units
Condense
r
Cooled
Water
Coolin
g
Tower
AirAir
Make-up
Water
Hot
Water

COOLING TOWER

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 draft cooling
towers

Natural draft
 Large concrete chimneys
 generally used for water flow rates above 45,000 m3/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 of Mechanical draft towers depend upon
their fan diameter and speed of operation
TYPES OF COOLING TOWER

• 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

Natural Draft Cooling Towers

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

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

Three types
• Forced draft
• Induced draft cross flow
• Induced draft counter flow
Mechanical Draft Cooling Towers

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

• 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

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

• Air blown through
tower by centrifugal
fan at air inlet
• Advantages: suited
for high air resistance
& fans are relatively
quiet
• Disadvantages:
recirculation due to
high air-entry and low
air-exit velocities
Forced Draft Cooling Towers

 Frame and casing
 Fill
 Cold water basin
 Drift eliminators
 Air inlet
 Louvers
 Nozzles
 Fans
 Pumps
 Chemical Dosing System

• 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

• 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

 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

 Heat exchange between
air and water is
influenced by surface
area of heat exchange,
time of heat exchange
(interaction) and
turbulence in water
effecting thoroughness
of intermixing. Fill
media in a cooling tower
is responsible to achieve
all of above.
Components of Cooling Tower

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

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

 Heat dissipation (in kCal/hour) and circulated
flow rate (m3/hr) are not sufficient to
understand cooling tower performance.
 For example, a cooling tower sized to cool 4540
m3/hr through a 13.9oC range might be larger
than a cooling tower to cool 4540 m3/hr
through 19.5oC range.

 Cooling Water Treatment
 Drift Loss in the Cooling Towers
 drift loss requirement to as low as 0.003 – 0.001%
 Cooling Tower Fans
 Flow Control Strategies

 Difference between
cooling water inlet
and outlet
temperature:
 Range (°C) = CW inlet
temp – CW outlet
temp
 High range = good
performance
RangeApproach
Hot Water Temperature (In)
Cold Water Temperature (Out)
Wet Bulb Temperature (Ambient)
(In) to the Tower
(Out) from the
Tower

RangeApproach
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

3. Effectiveness
Effectiveness in %
= Range / (Range +
Approach)
= 100 x (CW temp – CW
out temp) / (CW in
temp – Wet bulb temp)
High effectiveness =
good performance
RangeApproach
(Out)
(Ambient)
(In) to the Tower
(Out) from the
Tower

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
RangeApproach
(Out)
(Ambient)
(In) to the Tower
(Out) from the
Tower

5. Evaporation Loss
Water quantity (m3/hr)
evaporated for cooling duty
= theoretically, 1.8 m3 for
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
RangeApproach
Hot Water Temperature
(In)
(Out)
(Ambient)
(In) to the Tower
(Out) from the
Tower

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.)

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)

Energy Efficiency Opportunities
1. Selecting a cooling tower
2. Fills
3. Pumps and water distribution
4. Fans and motors

 The heat load imposed on a cooling tower is
determined by the process being served
 In most cases, a low operating temperature is
desirable to increase process efficiency or to
improve the quality or quantity of the product. In
some applications (e.g. internal combustion
engines), however, high operating temperatures are
desirable
 The size and cost of the cooling tower is
proportional to the heat load

 Minimum cold water temperature to which water can be
cooled by the evaporative method
 Thus, the wet bulb temperature of the air entering the cooling
tower determines operating temperature levels throughout
the plant, process, or system.
 Theoretically, a cooling tower will cool water to the entering
wet bulb temperature, when operating without a heat load.
However, a thermal potential is required to reject heat, so it is
not possible to cool water to the entering air wet bulb
temperature, when a heat load is applied
 The temperature selected is generally close to the average
maximum wet bulb for the summer months whether it is
specified as ambient or inlet

 Range is a direct function of the quantity of water circulated and
the heat load. Increasing the range as a result of added heat load
does require an increase in the tower size. If the cold water
temperature is not changed and the range is increased with higher
hot water temperature, the driving force between the wet bulb
temperature of the air entering the tower and the hot water
temperature is increased, the higher level heat is economical to
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.

Saba Power
Plant Data

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.

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)

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

1 x Condenser
Design Data: Made Ecolaire
Steam load: 588,694 LB/HR
Steam Temperature: 100.61oF
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: 21.6oC
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

Bently Nevada 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/cm2
Motor capacity 1 KW
1 x Anti-scalant dosing tank, Capacity 190 liters
2 x Anti-scalant dosing pumps, Neptune. Capacity 5 lph, 50 kg/cm2
Motor 1 KW

2 x Chlorination booster pumps, Jonson March
Capacity 43.14 m3/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.

During normal operation, one circulating water pump is in
service supplying approximately 60,000 gallons of water at
a temperature of 30ºC and a pressure of 1.4 kg/cm² to the
Main condenser and the closed cooling water plate heat
exchangers.
The circulated water makes two passes in the condenser.
Water enters the condenser waterbox inlet and flows
through the tubes into the return waterbox, and then
through the second set of tubes and into the outlet
waterbox.
As the circulating water flows through the tubes, the exhaust
steam thermal energy is transferred to the circulating
water. Rapid condensation of the steam occurs and a
vacuum is created in the condenser.

The heated water returns to the top of the cooling tower via
four pipe risers and into a horizontal distribution header
pipe. From there, it branches into a system of lateral
distribution pipes, where the nozzles spray the water
downward in a predetermined pattern over the heat
exchange medium, or fill.
Before the air flow is permitted to exit through the top of the
tower, it must pass through the drift eliminators. The
shape of this material causes the air to change directions
and thus provides impact surfaces which prevent water
droplets from being carried out of the tower with the air
flow.
The cold water basin of the cooling tower catches the falling
water, which then flows back to the circulation pumps.

As this process takes place, a small percentage of water is loss due
to evaporation. Ambient temperature and Relative Humidity
also affect the rate of evaporation. The cool water is then
recirculated to the users.
When the water evaporates in the cooling tower operations, most of
the dissolve solids remain behind in a non-evaporative state. If
the ratio of these concentrations become excessively high, scale
and deposits will form in the Main condenser tubes and other
piping. This will drastically affect the efficiency of the
condenser, which will in turn cause a high back pressure for the
steam turbine.
To reduce the amount of total dissolve solids (TDS) in the system,
blowdown is required. The operating (TDS) range is blow (3500
PPM). Cooling tower make up is therefore necessary to replace
the water loss caused by evaporation, blowndown, windage and
carryover.

WATER TREATMENT
Cooling tower maintenance can be
very high unless the water is treated
to prevent corrosion, biological
growth, and deposits. Water
treatment also protects the cooling
tower wood from chemical attack.

WATER TREATMENT
Due to the evaporation that takes place in the cooling
tower, the dissolved solids in the water become
concentrated. The evaporated water must be replaced by
make up water. The circulating water becomes more
concentrated than the make up water due to this
evaporation loss. The cycle of concentration is the term
applied to indicate the degree of concentration of the
circulating water with the make up water. Some water of
the cooling tower is also lost due to wind or drift loss, this
is the loss of fine droplets of water that are carried away by
the circulating air. In mechanical draft towers, 0.1 % to 0.3
% wind losses are possible. The water treatment process
plays a vital role in the cooling tower operation.

WATER TREATMENT
Calcium bicarbonate which is normally present in
raw water, breaks down to form relatively
insoluble calcium carbonate. Calcium carbonate
scale is the most common type of water formed
deposits in a cooling system. The Langlier Index
measures the tendency of CaCO3 to precipitate
under given conditions of calcium hardness,
alkalinity, pH, temperature and total dissolved
solids. A positive index means that water will tend
to deposit scale while a negative index tends to
dissolve scale.

WATER TREATMENT
The Saba Power Plant cooling water system has
three (3) dosing systems.
Sulfuric acid dosing
Anti-scalant dosing
Chlorination injection

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.

Anti-scalant Dosing System
Chemical inhibitors are needed to check corrosion. Surface
active chemicals or chelating agents such as sodium
hexameta phosphate prevent crystal growth &
therefore scale formation. In effect, they increase the
solubility range of scale forming salts. Controlled scale
treatment adjusts the composition of water so that a
thin impervious layer of calcium carbonate scale
deposits on the surface of the circulating water system.
The scale must be thick enough to prevent any
corrosion, but thin enough not to effect the overall heat
transfer.
For the Anti-scalant dosing system, there is one dosing
tank of 220 litters capacity with two dosing pumps.

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.

Precautions,
Limitations and
Setpoints

Before starting any circulating water pump (CW-PP-1/2),
verify that all four (4) riser isolation valves to the distribution
header at the cooling tower, are fully opened.
The circulating water pumps (CW-PP-1-2) motors are limited
to the number of starts, depending on the existing conditions.
This limitation is designed to protect the stator and rotor from
excessive heat that is generated from the high inrush current
when a motor is started. If the motor is in a cold condition
(standby), three (3) consecutive starts are allowed. If the
motor was running and achieved normal operating
temperature, the motor will be limited to two (2) consecutive
starts. If the number of starts is exceeded, the IQ-1000 which is
the supervisory instrumentation located on the respective
motor breakers will “lockout” the motor to inhibit a restart.
The number of starts should not average more than six (6)
starts per day. Prepared by: Mohammad Shoeb Siddiqui

The circulating water pumps (CW-PP-1-2) are equipped with
temperature sensing devices (TE-1028A-J for CW-PP-1 and
TE-1031A-J for CW-PP-2) that continuously monitor the
motor bearing and winding temperatures. If any winding
temperatures exceeds 170°C an alarm will annunciate on the
DCS (TAH-1028A-F for CW-PP-1 and TAH-1031A-F for CW-
PP-2) and if the winding temperature exceeds 180°C the
respective motor will trip and an alarm will annunciate on the
DCS (TAHH-1028A-F for CW-PP-1 and TAHH-1031A-F for
CW-PP-2).
If any motor bearing temperature exceeds 90°C, an alarm will
annunciate on the DCS (TAH-1028G-J for CW-PP-1 and TAH-
1031G-J for CW-PP-2) and if bearing temperature exceeds
95°C the respective motor will trip and an alarm will
annunciate on the DCS (TAHH-1028G-J for CW-PP-1 and
TAHH-1031G-J for CW-PP-2).Prepared by: Mohammad Shoeb Siddiqui

A circulating water pump (CW-PP-1-2) will be prohibited
from starting if the discharge motor operated valve (MOV-
2007, MOV-2009) is open. This requirement is to prevents the
motor from overloading and also prevent the system from a
sudden shock, which will result if the system is rapidly
pressurized.
During normal operation, one circulating pump (CW-PP-1 or
2) will be in service and one will be in the standby mode. The
discharge MOV-2007 and 2009 controllers must be in the
AUTO mode. If AUTO mode is not selected when the pump is
running, an alarm will annunciate on the DCS (PUMP IS
RUNNING and VALVE IS NOT IN AUTO). The standby
pump must be in the AUTO mode in the event that the
running pump fails and the standby pump will start
automatically.

A low level in the cooling tower basin will annunciate on
the DCS (LAL-1036) to warn the control room Operator.
The Low level alarm is set at –700 mm. Note that this
alarm gets its signal from the cooling tower basin level
transmitter.
A low low level in the cooling tower basin will trip the
pump that is in service and annunciate on the DCS
(LALL-1004). The level switch (LSLL-1041) is set at –800
mm.
A low press switch, (PSL-1005) is located on the
circulating water header, if this switch detects a low
pressure <1 kg/cm²>, the standby pump will start and an
alarm will annunciate on the DCS (PAL-1005).

All four (4) cooling tower fan gearboxes (CT-FN-1-4) are
provided with vibration monitoring instrumentation (VE-
1050A-D), that will generate an alarm on the DCS (VAH or
VAHH-1050A-D) if the respective vibration supervisory
circuit detects a Hi or Hi Hi vibration on the fan gearbox. The
Hi and Hi Hi vibration alarm is set at 0.075 in/sec. and 0.1
in/sec. respectively.
All four (4) of the cooling tower fan gearboxes are provided
with temperature measuring devices that will generate an
alarm on the DCS (TAH-1051A-D) if the temperature exceeds
100ºC and if temperature exceeds 111ºC, the fan will trip.

Sulifuric Acid
Sulfuric acid mist begins to irritate the eyes, nose and throat at
0.5 mg/m3; the threshold limit value of 1 mg/m3 may
corrode teeth, with frequent exposure. Sulfuric acid is more
irritating in a high humidity environment. Liquid sulfuric
acid will burn skin and eyes and it will deeply burn the
stomach and throat if swallowed. Sulfuric acid is non-
flammable but reacts violently with water and organic
materials. Poisonous gas may be produced in a fire.
Flammable hydrogen gas may be produced at acid facilities.
Fire fighters should wear protective equipment when
exposed to such conditions.
Low Low level switches are provided in the sulfuric acid and
Anti- scalant dosing tanks, these switches will trip the pump
and will annunciate on the DCS, when actuated.

Chlorine
Chlorine is known as a potential danger to worker
health. Chlorine causes irritation of the eyes, nose,
throat and lungs. Exposure to a sufficiently high
concentration of chlorine will be fatal. Chlorine gas
exhibits a sharp pungent odor. Therefore, its
presence is readily detected and it is unlikely that
anyone could remain in a contaminated area.
Fortunately, chlorine gas does not produce a
cumulative physiological effect and complete
recovery will occur following mild exposure.

The physiological effects of chlorine are;
detectable odor at 3.5 ppm, throat irritation at
15.1 ppm, coughing at 30.2 ppm and extreme
danger in 30-60 minutes at 40-60 ppm. The
characteristic penetrating odor of chlorine gas
gives warning of its presence in the air. Its
greenish yellow color makes it visible when
high concentrations are present. The handling
and use of both liquid and gaseous chlorine
require close attention to safety precautions
and practices.

○ 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

(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 (Na2CO3) 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

There are two (2) chlorine leak detectors installed at the
chlorination control room building, one inside the
chlorination room and the other at the ton/cylinder
container skid area. These leak detectors will give a
Chlorine leak alarm at the DCS and start the
strobe/horn at the Chlorination control room building.
Two windsocks are provided in the plant to establish
the wind direction in case of a chlorine gas leak.
Personnel should check the direction of these windsocks
before rushing to fix the leak.
Note
Don’t rush in the opposite direction of the wind

Chlorine
The Control Panel:
The control panel contains all the equipment required to
operate the chlorination sequence. A programmable
timer can be programmed to control the chlorination
process automatically.
The System Control Panel Alarm Lights are as follows;
Chlorine evaporator low water level
Chlorine evaporator water temperature high
Evaporator water temperature low
Liquid chlorine manifold pressure low (2.8 Kg/cm2)

Chlorine
Expansion chamber pressurized (2.8 Kg/cm2)
Evaporator discharge pressure relief valve (2.8 Kg/cm2)
Evaporator discharge pressure high (17.6 Kg/cm2)
Evaporator discharge gas temperature low
Filter exit low pressure (4.2 Kg/cm2)
Ejector pressure supply low
Booster pumps discharge pressure low (3.9 Kg/cm2)
Booster pumps suction pressure low (1.05 Kg/cm2)
Chlorinator vacuum low
Chlorinator vacuum high

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 scalant injection system
Chlorination system
Water Well pumps and raw water system
Startup

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 Low level (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.

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.

 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 Blowdown system in service by opening (CW-GA-01)
as required to control the Total Dissolve Solids (TDS) as per the
Chemistry manual.

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 not low.
 Start the Acid dosing pump A or B from DCS
Anti-scalant 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 not low.
 Start the Acid dosing pump A or B from DCS

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.

Chlorination System
 Set the water temperature control to 155 oF, the high temperature
control to 170 oF and 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.

 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.

Cooling Towers
THANK YOU
FOR YOU ATTENTION

Cooling water (CW) system

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