Cooling water treatment

COOLING WATER TREATMENT
By
Prem Baboo
National Fertilizers Ltd.India.
Fellow of Institution of Engineers,
India

INTRODUCTION
• Location- At Vijaipur, Dist-Guna Around
850km from Mumbai.
• Plant details
Unit Vijipur I Vijaypur II
Ammonia Plant MTPD 1520 1520
Urea Plant MTPD 2620 2620
CPP MW 3 x 17.5 3 x 17.5
Raw Material NG NG/Naphtha
Commisioning 1987 1998

Details of Cooling Tower
.
Ammonia I Urea I Ammonia II Urea II
Type Induced
draft
Cross flow
Induced
draft
Cross flow
Induced
draft
Cross flow
Induced
draft
Cross flow
No. Of Cells 6 5 6 5
Delta T 10 10 10 10
CR m3/hr 17000 16000 18000 17000
System Hold
Up
7500 7000 7500 7000

Make up Water Quality
Parameter UNITS Typical Range
pH 7.5 – 8.2
Total Hardness Ppm 75 – 120
Ca-Hardness Ppm 50 – 80
Mg-Hardness Ppm 25 – 40
Silica Ppm 10 – 25
Chlorides Ppm 10 – 25
M-Alkalinity Ppm 60 – 150
Sulphates Ppm 10 – 50
TDS Ppm 150 – 200

Re-circulating Water Parameters
.
Parameter Units Normal Operating Range
pH NTU 6.8 – 7.5
Turbidity Ppm 5
Total Hardness Ppm 700 – 800
TDS Ppm 2200max
Silica Ppm 100max
Chlorides Ppm 150 – 250
Iron Ppm 1.5max
Zinc Ppm 1.0max
Total PO4 Ppm 4 – 8
COC 6-8
TBC Counts/ml 1 x 105
SRB Counts/100ml 100

Monitoring Tools
1. Corrosion Coupons
2. Deposit monitor
3. Bio-fouling monitors
4. Test heat exchanger
5. Microbial counts
6. ORP meter
7. Inspection of cooler during shut down

Cooling Systems
• Once-through systems
• Closed recirculating systems
• Open evaporative recirculating

Simple Cooling Water
Diagram
Simple cooling water diagram.
Cooling tower
Blow down
[evaporation]
Return water
Coolers
Heat exchangers

Cooling Water Terminology
• Cooling water - water used to cool process fluid,
condense steam, cool oil, air, etc
• Make-up water - fresh water added to make-up
for loss water
• Evaporation - droplets of hot return water that
evaporate taking heat with them cooling the
remaining water
• Blow-down or bleed-off - water that is being
drained or loss beyond control

Terminology
• Cycle of concentration - how many times
concentrated the cooling water is
compared to the make up water (dissolved
solid concentration)
• Drift loss - loss of water through windage
• Circulation Rate - total circulation pump
flow rate

Terminology
• Supply temperature - temperature of the
supply water
• Return temperature - temperature of the
return water
• Delta T (temperature different) - the
difference between return and supply
temperature (T return - T supply)

Relationship of various
parameters
• Cycles Of Concentration
C = Concentration in Recirculation
Concentration In Make-up
• Evaporation Loss
E = 0.0018 x deltaT x R x TF (Tower Factor)*
( T expressed in oC)
* Tower factor is based on humidity/%
contribution of evaporation to delta T

Relationship of various
parameters
• Windage Loss
W = 0.05 to 0.2 x R / 100
• Blow Down
B = E / ( C – 1 )
• Make-up
M = E + W + B

Cooling Water Chemistry
• pH
• Conductivity or Total Dissolved Solid
• Turbidity or Total Suspended Solid
• Total hardness
• Calcium hardness
• Alkalinity (p and m)
• Chloride
• Sulfate
• Silica

More Parameters
• Total Iron
• Inhibitor residuals (i.e. o-phosphate, phosphonate, zinc,
molybdate, etc.)
• Bacteria counts (TBC , SRB, Nitrifying )
• Chlorine i.e FRC
• ORP
• CLO2 levels

pH
• Low pH means more hydrogen ions
• Hydrogen ions depolarizes corrosion
cells accelerating corrosion
• High pH means more hydroxyl ions
• Environment for scales formation
• Environment for microbiological
activities

Conductivity or TDS
• High values mean more dissolved
minerals
• Higher ions movement improves
electrical conduction
• Increase the rate of electrochemical
corrosion.

Turbidity and Total
Suspended Solid
• The content of suspended solid in the
water - silt, debris, air-borne materials
• Higher values indicate potential fouling
due to deposition of the solid
• The deposition might be combined with
microbiological activities -
microbiological sludge and MIC

Total Hardness
• The contents of permanent hardness -
calcium, magnesium, barium, strontium
• Generally indicates the total content of
calcium and magnesium as CaCO3
• Read as CaCO3 due to the molecular weight -
100
• High values indicate potential scales
formation when there is a presence of
complexing anions

Calcium Hardness
• The content of calcium in water read
as CaCO3
• The most common component of
scales in water system
• May form calcium carbonate, calcium
phosphate and calcium sulfate scales
• High values may also indicate less
corrosive (electrochemically) water

Alkalinity
• Acid neutralizing ability
• Free mineral acidity - CO2 at pH < 4.2
• M-alkalinity consisting of HCO3
- and CO3
2-
beginning from methyl-orange point pH >4.2
• P-alkalinity consisting of CO3
2- and OH-
beginning from phenolpthalien point pH >8.2

Chloride and Sulfate
• Corrosive ions - form metal chloride
and sulfate then mineral acids
• Cause pitting corrosion
• Chloride - environment for SCC -
stainless steel
• Sulfate - required element for SRB

Total Iron
• High values may indicate corrosion
activities
• Potential deposition of corrosion
products - fouling and under-deposit
corrosion

Inhibitor Residuals
• Depending of inhibitors used and control
ranges
• Inhibitors - phosphate (ortho or total),
phosphonate, zinc, molybdate, toly-triazole
• Low level - insufficient protection
• High level - potential scales formation
(precipitative chemistry) and non economical

Why do we treat cooling
water?
• Corrosion of ferrous and non-ferrous
metals - electrochemical
• Precipitation and deposition of mineral
scales
• Deposition of suspended solid
• Microbiological sludge deposit
• Biofilm or microbiological slime
• Microbiologically influenced corrosion

Corrosion Scaling
PROBLEMS
Fouling
General Fouling Microbial Fouling
Algae,
Fungi,

CORROSION
• Corrosion is an electrochemical process by
which metals return to their native state
• Mild Steel reverts back to Iron Oxide
• This is also true for copper alloys, Zinc,
Aluminum etc.

Localised corrosion
• c
+ Cathode +
Fe(OH)3
Fe2O3
Fe(OH)2
Fe++
- Anode -
Fe
Metal
e-
e-
e-
e-
+ Cathode +OH-
02+H2O

Corrosion Cell
2Fe + O2 + 2H2O ---> 2Fe (OH )2
Ferrous Hydroxide
2Fe(OH)2+H2O+1/2O2 ->2Fe(OH )3
Hydrated Ferric
Oxide

Prevention Of Corrosion
• Condition the metal
– coating (Zinc,Epoxy Resin)
.
– Alloy the metal (Stainless Steel)
• Condition the environment
Remove Oxygen
• Use corrosion inhibitors

Corrosion Inhibition
Mechanisms
• Oxidation
• Oxidation with film strengthening
• Cathodic polarization
• Cathodic precipitants

Anodic Inhibitors
An anodic Inhibitor interferes with the Anodic
process
• Chromate
• Molybdate
• Phosphate
• Nitrite
• Phosphonates

Oxidation
(With complexation)
• .
Fe++
2e--
PO4PO4
Fe3(PO4)2 FePO4

Cathodic Inhibitors
A Cathodic inhibitor interferes with the cathodic
process by precipitating an insoluble species
onto the cathodic site.
• Zinc
• Calcium Carbonate
• Polyphosphate
• Phosphate
• Phosphonates

Cathodic Precipitants
• .
Zn
e-
e-
e-
e-
e-
O2
O2
O2
O2
O2
OH-
OH-
OH-
Zn
Ca
HCO3
HCO3
HCO3
HCO3
HCO3
HCO3Ca
Ca
Ca
Zn
Zn
Zn
Zn
Zn(OH)2
HCO3 + OH H2O +CO3
CO3
CO3Zn CaCO3

Zinc
• Forms zinc hydroxide and zinc carbonate
complexes at cathode
• Good for soft water
• Above pH 8 will begin to precipitate in
bulk water
• Zn is stabilised by phosphonates and
polymers
• Levels from 0.25-3.0 ppm used

Poly and Ortho-phosphate
• Form complexes with Ca at cathode
• Need to formulate stabilizing polymer with
package
• Also reacts at anode to form iron
phosphate complex
• Levels of 2-15ppm typically used
depending on program

Scaling
Caused by crystalline growth of salts on the
system surfaces
• CaCO3 (Calcite) : Major Scale
• Silica :Amorphous silica precipitates,when
*SiO2 > 150 ppm at pH < 8.0
. > 180 ppm at pH > 8.0
• MgSiO2 :Adsorption of silica on precipitated
Mg(OH)2 (Brucite)
• Ca5(PO4)3OH (Hydroxyapatite)
• CaF2 (Fluorite) : Potential foulant

Solubilities (20 / 100 deg C)
• Sodium Chloride
• Sodium Sulphate
• Sodium Carbonate
• Sodium Bicarbonate
• Sodium Phosphate
• Calcium Chloride
• Calcium Sulphate
• Calcium Carbonate
• Calcium Bicarbonate
• Calcium phosphate
36% / 39%
16% / 30%
32% / 31%
8% / Dec
11% / Dec
43% / 61%
0.3% / 0.06%
0.005% /0.002%
0.08% / Dec
0.0003%/ 0.0002%

Solubilities ( 20 deg C )
• Silica
• Ferrous Hydroxide
• Ferric Hydroxide
• 0.005%
• 0.0007%
• 0.0001%

Formation of Hardness scale
• Calcium Carbonate has inverse solubility
• Ca(HCO3)2-------> CaCO3 + H2O + CO2
• Mg(HCO3 )2------> MgCO3 + H2O + CO2
• MgCO3+ H2O-----> Mg(OH)2 + CO2

Scale Formation
• CaCO3 precipitates at Saturation pHs and
depends primarily upon:
– Level Of calcium hardness
– Level Of Bicarbonate alkalinity
– pH
– TDS
– Temperature
– Water velocity

Scale Inhibition
• Remove hardness salts.
• pH control with Acid
• Dose scale inhibitor

Acid Dosing
• Used to limit pH in hard water systems.
• Helps in inhibitor selection
• Potential for water and treatment savings by allowing an
increase in COC
• Each 1ppm M Alkalinity will require:
• 1.0 ppm sulphuric acid
• 2.0 ppm Hydrochloric acid
• 1.8 ppm Nitric acid

Scale Inhibitors
• Added to extend Induction time beyond Retention time
• Induction time decreases with increase in Saturation
level ( Driving force)
• Effectiveness of Inhibitor depends on the extent to
which it increases Induction time at lesser dosage
• Inhibitor dosage is increased with increase in Induction
time
• If retention time is less than induction time there is very
little need of scale inhibitors

Dispersion
• A process by which charged particles are
prevented from agglomerating into larger
particles rendering them less settleable.
• Most cooling water particulates have a net
negative charge. Acrylate dispersants also have
a net negative charge. Addition of dispersant
increases charge inhibiting agglomeration.

Dispersants
• Polyacrylate
• Acrylate /Acrylamide
• Acrylate terpolymers
• Sulfonated styrene
• Maleic Acid Homopolymer
• Maleic acid co and terpolymers

Bio Fouling
• Caused by the excessive growth of
microorganisms.
• Cooling water system-ideal incubator for
growth

Problems
• Pitting corrosion-depolarising action of O2
released during their metabolic process.
• Shield metal surfaces from the action of
inhibitors
• cause legionella pneumophila disease

Chemical Control
• Microbiocides
e.g. Bacteriacides,Fungicides,Algaecides
• Microbiostats
e.g. Bacteriastats,Fungistats,Algaestats
• Surfactants

Microorganisms
• Viruses
– Consists of protein & DNA/RNA (Nucleic acids)
– Survive by multiplying in other
host cells - plant or Animals

Cooling Water as a
Medium
Ideal temperature (200C-600C)
pH 6 to 8
Often exposed to sunlight
Some made of wood
Nitrogen and phosphorous based inhibitors
Suspended and airborne debris
Good aeration
Presence of process fluids like ammonia,
urea, other organics and sunlight

.
• Algae
– Photosynthesis
– Uni/Multicellular
– Diverse Forms
 Filamentous
 Colonial
 Plantlike
• Diatoms
– A Group of Algae
– Organic walls impregnated with silica

.
• Blue Green Algae
– Photosynthetic bacteria
• Fungi
– Aerobic growth above the waterline
– Do not contain chlorophyll

.
• Mould
– Fungus which forms visible layer on the surfaces
- Wood/Walls/Foods
• Yeast
– Unicellular Fungi
• Protozoa
– Diverse group of unicellular Microorganisms

Bacteria
• Unicellular
• Cells may grow attached to each other in clusters ,
chains , rods or filaments
• Require carbon source for growth
• Different shapes
– Rods Bacillus
– Spherical Coccus
– Spiral Spirill
• Protected by slime
• Multiply by cell division

Bacteria (Classification )
• Aerobic Requires O2 & CO2
• Anaerobic Grow in O2 free atmosphere
• Facultative Grow in both conditions
• Autotrophes Inorganic nutrients
• Heterotrophes Organic nutrients
• Psychrophiles < 22 0c
• Mesophiles 22 ~ 45 0 C
• Thermophiles > 45 0 C
• Planktonic Free floating organisms in .
Water
• Sessile Surface attached growing in .
Biofilm

Methods Of Control
• Physical
– Nutrient Removal - Remove food or energy
source .
e.g. Sunlight , Dead Leaves.Process Contamination.
– Temperature Control - Increase temperature
Not really practical on a Cooling System

Methods Of Control
• Chemical
– pH Adjustment
• With the help of Acid / Caustic
(pH’s Over 10.0 Required)
– Microbiocide Control
• Kill Organisms by use of toxic material
e.g. Algaecides,Fungicides, Bacteriacides

Biocide Classification
• Oxidising Materials
– Have the ability to oxidise organic matter
– Irreversibly oxidise protein groups
• Non-Oxidising Materials
– Destroy or inhibit normal cell metabolism by any of
the following ways:-
• Altering permeability of cell wall
• Destroying protein groups
• Precipitating protein
• Blocking metabolite reaction

Sulphate Reducing Bacteria
• Anaerobic and convert dissolved sulphur
compounds to H2S
10 H++ SO4
-2+ 4Fe --> 4Fe+2+H2S +4H2O
H2S + Fe+2 --> FeS + H+
• H2S released corrodes Carbon steel and Copper
based alloys.
• Localised pH depressions cause further attack
• Exist mainly below deposits devoid of oxygen
• Corrosion rate as high as 100 mpy occurs

Nitrifying / Iron Bacteria
• Nitrifying Bacteria :
– Oxidation of Ammonia .
NH3 + 2O2 ---> HNO3 + H2O
– Nitrosomonas , Nitrobacter
• Iron Bacteria :
– Oxidation of ferrous ions .
++ .
– Fe + O2 ----> Fe2O3
– Crenothrex

Limitations Of Chlorination
• Not effective in alkaline water
Cl + H2O = HOCl + HCl
HOCl -> OCl- + H+
OCl- is 1/80 th time as effective as HOCl
Deactivated by the reducing agents H2S ,SO2,,NH3,polyacrylamide,
Monoethnolamine,etc.
• Deactivates some Organo phosphonates, Does not penetrate slimes
• Extremely corrosive to many metals-maintenance of chlorinator is difficult.
• Environmental limitations - 0.1 ppm. Free Cl2 can kill fish
• When not effective use bromine compounds,chlorine dioxide,ozone

Chlorine
A strong smelling, greenish-yellow
gas with pungent odor which is
extremely irritating to mucous
membranes.

Chlorine Gas
• Hazardous
• Heavier than air
• Strong oxidizer
• Low capital requirements
• Produces chlorinated by-products
• Efficacy - pH dependent

Chemistry Chlorination
Chlorine gas dissolves in water and hydrolyses as:
Cl2 + H2O  HCl + HOCl (hypoclorous acid)
HOCl ↔ H+ + OCl- – (hypo chlorite ion)
The percentage distribution of hypochlorite ion and
undissociated hypochlorous acid can be calculated for
various pH values.
The amount of hypochlorite ion becomes appreciable above pH
6 while molecular chlorine is non-existent.
HOCl is about 80 times more effective than OCl- as a biocide

Microbicidal Efficiency
• HOCl – the microbicidal efficiency is due to the
relative ease with which it can penetrate cell walls.
The penetration is quite comparable to water.
• OCl- - Poor disinfectant (about 1/80% efficiency of
HOCl). It is unable to diffuse cell wall of
microorganisms due to negative electrical charge.

Chlorine Effectiveness
At Various pH
0
10
20
30
40
50
60
70
80
90
100 0
10
20
30
40
50
60
70
80
90
100
4 5 6 7 8 9 10
Percentage HOCl
pH Value
Percentage OCl -

Microbiological Action
• Diffusion of active agent through cell wall and attack
the enzymes group whose destruction results in death
to the organism. Hence microorganisms are not
immune to chlorine
Factors affecting chlorine efficiency:
1.Concentration of Free Chlorine
2.Contact time
3.Temperature
4.Types and concentration of organisms
5.pH
6.Contaminants

Chlorine Di-Oxide
• Draw backs of chlorine can be over come
with help of Clo2 mainly in NH3
contaminated water.
• It can be produced on site as
• 2NaClO2 + Cl2  2 ClO2 + 2NaCl
• ClO2 does not react with ammonia thus
gets effective in controlling
microorganisms.

Limitation of Chlorine
• Chlorine reacts with organics, hence
exerts a chlorine demand leading to
higher chlorine consumption and non-
maintenance of residual
• Difficult to handle and dose
• Efficacy of chlorine is pH dependent
• Chlorine is highly corrosive

Chlorine Reactivity
1. With Ammonia
- HOCl + NH3  NH2Cl (mono chloramines) + H2O
- NH2Cl + HOCl  NHCl2 (dichloramine) + H2O
- NHCl2 + HOCl  NCl3 (trichloramine) + H2O
It means one ppm of ammonia can react with 3
ppm of chlorine, hence will increase chlorine
demand

Chlorine Reactivity
2. With Organic Nitrogen
• Proteins hydrolyzes to amino acids.
• Chlorination chemistry of these are
extremely complex
• Because of various hydrolysis
products.
• Finally the products are mono/di-
chloramines.

Chlorine Reactivity
3. With Urea
• Urea hydrolyzes with nitrogen breaking down to
ammonia in presence of urease enzyme.
• If the hydrolysis lacks this enzyme, the formation of
NH3 is greatly inhibited.
• If significant quantity of urea-N is present and
hydrolysis proceeds at slow rate, unstable residue
could result.
• Urea-N would then be reservoir for the production of
ammonia.

Chlorine Reactivity
4. Inorganic Carbon:
C + Cl2 + 2H2O  4 HCl + CO2
This takes place in dechlorination with
granular activated carbon.
5. Cyanide:
At alkaline pH 8.5 or higher,
2Cl2 + 4NaOH + 2NaCN  2NaCNO +
4NaCl + 2H2O

Chlorine Reactivity
6. Hydrogen sulphide:
H2S + 4Cl2 + 4H2O  H2SO4 + 8HCl
Here 8.3 ppm of chlorine is required to
oxidize 1 ppm of H2S.

Chlorine Reactivity
9. Hydrocarbons:
Hydrocarbons create high chlorine
demand due to high oxidisable
organics.

Chlorine Dioxide
Application Technology

Chlorine Dioxide
Introduction
• Strong oxidizer
• Not a halogen
• Selective reactivity
• Generated on site
• pH independent

Chlorine Dioxide (Contd.)
• Rapid acting. Lower contact time for
micobiological kill compared to chlorine
• Less corrosive compared to chlorine
• Does not hydrolyse to form acid
• Does not react to form chloramines
• Does not form trihalomethanes with organic
matter like chlorine
• Does not produce any chlorinated compounds

Chlorine Dioxide Mechanism
of Kill
 Disruption of protein synthesis or lysing of cell
 No resistivity by organisms

Chlorine Dioxide Effectiveness at
Various pHs
0
10
20
30
40
50
60
70
80
90
100
4 5 6 7 8 9 10
% Active
pHLb./Equal
Performance 1

Chlorine Dioxide
Safety Considerations
 Not handled as a gas
 Typical use is < 0.3% solutions
 On-site generator is required

Selection criteria of
suitable oxidant
• Efficacy
• Safety handling
• Regulatory reporting
• Process contamination
• pH dependence

Safety
Sodium Hypochlorite
Sodium Bromide
Chlorine Dioxide
Ozone
BCDMH
Chlorine Gas
Best
Worst

Reporting Requirements
Chlorine Dioxide
Hypochlorite
Bromine Compound
Ozone
Chlorine Gas
Least
Greatest

Performance in Contaminated
Systems
Chlorine Dioxide
Ozone
Bromine Compounds
Chlorine Gas
Sodium Hypochlorite
Best
Worst

Performance at Elevated pH
Ozone
Chlorine Dioxide
Bromine Compound
Sodium Hypochlorite
Chlorine Gas
Best
Worst

Best Alternative
• CHLORINE is still a widely used oxidant
* Inexpensive, historically established, being phased out
• HYPOCHLORITE is cheapest alternative
* Similar performance to chlorine, degradation is problem
• BROMINE CHEMISTRY, halogen alternative
* Better performance, can be costly, pH dependent
• CHLORINE DIOXIDE, non-halogen alternative Cost-effective broad
spectrum, safely fed, pH independent, non-chlorinating agent
• OZONE, New Approach
* Capital intensive, strong oxidant, no chemicals

Chlorine Dioxide
Advantages/Benefits
• Gas dissolved in water
• Strong oxidizer
• Not a halogen
• Selective reactivity

Chlorine Dioxide
Advantages/Benefits
• Generated on-site
• Rapid acting
• pH independent

Physical Characteristics
Color : Yellow-green
State : Gas
Odor : Similar to chlorine
Solubility: 2.9 gr/L

ClO2 Generator
Generation Methods
Chlorine Gas Method
Three Pump Method

Precursor Source
Water
Inlet
Chlorine
1
2 3
4
56
7
8
9
10
11
12
13
48"H x 42"W x 17"D
14
ClO2
15
1. Electric Control Box
2. Flow Indicator (GPM)
3. Hand/Off/Auto Switch
4. Ball Valve
5. Solenoid Valve
6. Pressure Gauge
7. In-line Flowmeter
8. Ball Check Valve
9. Chlorine Eduction
10. Chlorine Solenoid Valve
11. Chlorine Rotameter
12. Precursor Pump
13. ClO2 Generator
14. Emergency Shutdown
Switch
15. Loss Of Chlorine Switch
ClO2 Generator
Chlorine Gas Method

ClO2 Generation
Gaseous Chlorine Method
2NaClO2 + Cl2 2ClO2 + 2NaCl
Sodium Chlorine Chlorine Sodium
Chlorite Dioxide Chloride

ClO2 Generation
Three Pump Method
2NaClO2 + NaOCl + 2HCl 
Sodium Sodium Hydrochloric
Chlorite Hypochlorite Acid
2ClO2 + 3NaCl + H2O
Chlorine Sodium Water
Dioxide Chloride

Hydrochloric Acid Source
Sodium Hypochlorite Source
Precursor Source
1
2 3
456
7
8
9
10
48"H x 42"W x 17"D
11
ClO2
9 9
Water
Inlet
1. Electric Control Box
2. Flow Indicator (GPM)
3. Hand/Off/Auto Switch
4. Ball Valve
5. Solenoid Valve
6. Pressure Gauge
7. In-line Flowmeter
8. Ball Check Valve
9. Chemical Pumps
10. ClO2 Generator
11. Emergency Shutdown
Switch
ClO2 Generator
Three Pump Method

ClO2 Generator
Generation Method
Three Pump Method
Advantages
• Higher Capacity
• High Back-
Pressure
Capacities
• Higher Turndown
• No Chlorine Gas
Necessary
Disadvantages
• Slightly Higher
Cost
• Additional
Chemical Storage
• Incompatible
Chemicals

Typical ClO2 Dosages
Rendering Odor Control :2-10 ppm
Cooling Water Treatment: 0.1-0.5 ppm
Food Processing : 2-10 ppm
Paper Mill Slime Control :0.25-0.45 lb
ClO2/ton
paper

Sodium Chlorite Precautions
DO NOT
allow solution
to dry.
DO NOT mix
with any
other
chemicals.
DO NOT use wooden
pallets or paddles.
DO NOT wear leather
or cloth external
clothing.

Normal Shutdown
Procedure
• Turn operating switch to “Off”
• Water flush occurs briefly
• Drain unit
• If chlorine used, close valve
• Drain and flush all chemical systems

Equipment Site
Survey Location
• Well-ventilated area
• Eyewash/shower near generator
• Eyewash/shower near bulk storage
• Washdown water source available
• Approved drain
• Well lighted

Monitoring Tools
• Corrosion coupons
• Deposit monitor - visual indication of deposit
formation
• Biofouling monitor - indicate loss of pressure due to
biofilm
• TBC and SRB dip slides
• Test heat exchangers
• ORP meters
• Site Management
• Daily reporting

Corrosion Monitoring by
Coupons Method
• Corrosion Rate (MPY) = coupons wt loss in
gms*365*1000/ Area of coupon in cm2*density of
coupon in (gm/cm3)*Exposure period in days*2.54
Also we know that 1 Miles = 0.001 inch =0.0254 mm
Means if corrosion rate is 3 MPY will cause the metal
loss (tube thickness reduction) by 0.0762 mm per
year.

THANK YOU
for any types of queries
please contact to
Prem Baboo
Sr. Manager(Prod)
National Fertilizers Ltd, India
Designer for Plant & equipment's
pbaboo@hotmail.com
Prem.baboo@nfl.co.in
+919425735974

Cooling water treatment

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