Cooling Water Treatment

COOLING WATER TREATMENT

Advanced training course Cairo – 22 to 24 Ma Cairo May y 2005 2200 0055

Jean Michel Fréal-Saison Technical Support Group Leader MEAGCC 

Attendees Welcome to all of you to our first Regional Advanced Technical Training Course Than Th ankk you you for for atten attendin ding g th this is tr train ainin ing g cour course se.. We are particular particularly ly pleased pleased to welco welcome me our collea colleagues gues from System Technique. Atte At tend ndan ance ce Li List st.x .xls ls We which you every success in this training course.

Attendees Welcome to all of you to our first Regional Advanced Technical Training Course Than Th ankk you you for for atten attendin ding g th this is tr train ainin ing g cour course se.. We are particular particularly ly pleased pleased to welco welcome me our collea colleagues gues from System Technique. Atte At tend ndan ance ce Li List st.x .xls ls We which you every success in this training course.

Agenda Day 1 –22 May 2005 08:30 to 08:45 Introduction 08:45 to 09:00 Pre-training Quizz 09:00 to 10:30 Water Chemistry 10:30 to 11:00 Coffee break 11:00 to 12:30 Cooling System hydraulics 12:30 to 13:30 Lunch 13:30 to 15:00 Cooling Water Treatment 15:00 to 15:30 Coffee Break 15:30 to 17:00 Scaling and Scale control

Agenda Day 2 –23 May 2005 08:30 to 10:00 Corrosion and Inhibitors 10:00 to 10:30 Coffee break 10:30 to 12:30 Corrosion control 12:30 to 13:30 Lunch 13:30 to 15:00 Microbiological control 15:00 to 15:30 Coffee Break 15:30 to 17:00 Treatment and Product Guidelines

Agenda Day 3 –24 May 2005 08:30 to 10:30 Monitoring and control 10:30 to 11:00 Coffee break 11:00 to 12:00 Troubleshooting 12:00 to 12:30 Final Quizz 12:30 to 13:30 Lunch

Pre-Training Quizz (10 mn) Read the questions carefully. Do not extrapolate. T - F (T (Tru rue e – Fa Fals lse e): Se Sele lect ct th the e rig right ht st stat ate eme ment nt A-B-C: one or more answer(s) is(are) correct

Team work Form For m 4 or 5 team teamss (4 to to 5 member memberss in each each team team)) Team A: Team B: Team C: Team D:

INDEX 1. 2. 3. 4.

Basic water chemistry Cooling systems Cooling system hydraulics Cooling water treatment programmes 1. Scale inhibition 2. Corrosion inhibition 3. Yellow metal corrosion inhibition 4. Closed system inhibitors 5. Microbiological control 6. Treatment programme design 7. Monitoring and troubleshooting

Chap 1 BASIC WATER CHEMISTRY

Basic Water Chemistry

WATER •Pure water contains one part of oxygen and two parts of hydrogen and is > COLOURLESS > ODOURLESS > TASTELESS •PHYSICAL PROPERTIES > Melting Point 0°C (32°F) > Boiling Point 100°C (212°F) > Typical Density 1 gramme / ml > Maximum Density at 4°C

Water Cycle

Atmospheric moisture

Precipitation Evaporation and Transportation from Surface Water Bodies, Land Surface and Vegetation Consumptive use

Well

Evaporation from Oceans

Stream flow to Oceans

Percolation Total Surface and Ground Water flow to Oceans

Water Table Fresh Ground Water

Ocean Saline Ground Water

WATER

Water is the UNIVERSAL SOLVENT and dissolves to some degree every known substance Water will contain impurities in the form of dissolved solids, suspended solids and dissolved gasses It is essential for industry that abundant supplies are continuously available

SOURCES of WATER •Surface Water > Lower quantities of Solubilised Minerals > High amounts of Particulate Matter > Variable Organic Matter Content > Influences from Terrain and Geological Composition •Ground Water > Higher Mineral content > Less Suspended Solids > Influences from Geological Composition •Other Water Sources > Recycled / Reclaimed Water > Sea Water

Purification of Water •Suspended Solids > Clarification > Filtration •Dissolved Salts > Precipitating Softening > Ion Exchange > Reversed Osmosis > Multiple Flash Evaporators •Dissolved Gases > Degasification > Deaeration

ATMOSPHERIC GASES •The atmosphere is a mixture of gases ,the main components are Nitrogen 78 %, Oxygen 21 %, Argon 0.9 % and Carbon Dioxide 0.033 % > Other gases include Hydrogen, Helium and Neon •Nitrogen is Inert •Oxygen : > The solubility is approx.10 mg/l at ambient temperature and pressure. The solubility decreases as temperature increases.

O2 SOLUBILITY IN WATER TEMPERATURE, C

0

10

21

32

43

54

66

77

88

99

cm3/l 16

110 121 22.9 ppm 20.0

14 10

12

8 6 4 2

10

14.3 VACUUM INCHES MERCURY

0

8

4 8

6 4

8.6 5.7

20

2.9

28

32 50

11.4

12 16 24

2

17.2

GAUGE PRESSURE PSI

70

90

110 130

150

170

0.0 190 210 230 250

ATMOSPHERIC GASES

•Carbon Dioxide : The solubility goes up to 1,700 mg/l in water. CO2 + H2O H+ + HCO3 = > When Carbon Dioxide dissolves in water a WEAKLY ACIDIC solution is produced. This is commonly known as Carbonic Acid > Typical pH is 6.5 to 6.8

INDUSTRIAL GASES

•Industrial gases produced by burning fossil fuels and by-products from industrial processes include Sulphur Dioxide / Trioxide, Nitrous Oxides, Hydrogen Sulphide and Ammonia SO2 + H2O SO3 + H2O

H2SO3 H2SO4

Sulphurous Acid Sulphuric Acid

INDUSTRIAL GASES •Nitrous Oxides > These include Nitrous Oxide NO Nitrogen Dioxide NO2 Dinitrogen Tetraoxide N204 •Hydrogen Sulphide H2S in H2O H+ + HSBisulphide •Ammonia NH3 + H2O

OH- + NH4+ Ammonium

DISSOLVED SALTS •Water dissolves, to some extent, all known substances. However from a water treatment point of view we are mainly concerned with the salts of Calcium, Magnesium and to a lesser extent Sodium and Potassium. •The salts of Calcium and Magnesium are known as HARDNESS salts . •In most naturally occurring waters the Calcium concentration is higher than the Magnesium concentration. In sea waters the reverse is true .

DISSOLVED SALTS

•Typical Calcium and Magnesium salts are : Bicarbonates Carbonates Chlorides Sulphates Silicates

Ca(HCO3)2 CaCO3 CaCl2 CaSO4 CaSiO3

Mg(HCO3)2 MgCO3 MgCl2 MgSO4 MgSiO3

SILICA •Soluble ( Reactive ) > Form : Silicic Acid H2SiO3 > Removal :Adsorption on Coagulator Floc Strong Base Anion Exchanger Resin •Colloidal ( Non-Reactive ) > Form : Complex,High molecular weight polymeric colloid > Removal : Adsorption on Coagulator Floc > Converts to reactive silica in the boiler

UNITS OF CONCENTRATION •Dosage rates for continuous feed are expressed as mg/l on either BLOWDOWN or MAKE UP water flow for cooling systems. •Shot doses are expressed as mg/l based on SYSTEM VOLUME: > 1 ppm equals: – 1 mg / l of water – 1000 mg/m³ of water – 1 g/m³ of water – 1 kg /1000 m³ of water •In some instances solution strength is expressed as a percentage: > 1 % solution = 10,000 mg/l or 10,000 ppm

UNITS OF CONCENTRATION Parts per Million ppm = mg/l Parts per Billion ppb = µg/l Normally hardness and alkalinity are expressed as mg/l CaCO3. This allows us to calculate the concentration of the different ionic species present in any given sample Total hardness 150 ppm as CaCO3 Calcium hardness 100 ppm as CaCO3 Magnesium hardness 50 ppm as CaCO3 M-Alkalinity 80 ppm as CaCO3 Chloride 40 ppm as Cl-

UNITS OF CONCENTRATION •Total hardness and Calcium hardness are obtained by titration and therefore Magnesium hardness is determined by difference . > Total hardness 150 ppm as CaCO3 > Calcium hardness 100 ppm as CaCO3 > Magnesium hardness 50 ppm as CaCO3 > M-Alkalinity 80 ppm as CaCO3 > Alkaline hardness 80 mg/l as CaCO3 > Non-alkaline hardness (150 - 80 ) = 70 mg/l

EQUIVALENT WEIGHTS •Equivalent weight refers to the amount of an element combining with a unit weight of hydrogen. •As a rule of thumb , the molecular weight divided by the valency . > Equivalent weight of CaCO3 = 100 g > Molecular weight of CO3 = 60 g > Equivalent weight of CO3 = 60/2 = 30 g – 10ppm CaCO3 = 0.2 me CO3 > Atomic weight of Calcium = 40 g > Equivalent weight of Calcium = 40/2 = 20 g – 10ppm CaCO3 = 0.2 me Ca •Ionic balance should be calculated in milli-equivalents

Corrosion Rate Measurement •mils per year = 1/1000 inch per year •mm/y = millimetres per year > 1 mpy = 0.025 mm/y (0.0254) > 1 mm/y = 40 mpy

Other important Measurements pH Alkalinity Conductivity* Chloride Sulphate Soluble Iron (in Make Up Water) Manganese * essentially Total Dissolved Solids (TDS)

Carbon dioxide species versus pH in natural waters 100% 90% H2CO3

80%    2    O    C   e   g   a    t   n   e   c   r   u   o    P

CO3--

HCO3-

70% %HCO3 -/C O3 --

60%

%HCO 3 -/ H2 C O2 %H2 CO2 / HC O3 -

50%

%CO3 --/HCO3 -

40%

P alk.

30% 20%

M alk.

10% 0% 2

3

4

5

6 7 K1 6 3

8

9

10 11 K2 10 3

12

13

14

P Alkalinity

P and M ALKALINITY

• P = Alkalinity - phenolphthalein alkalinity (pH=8.3) > This titration includes all the HYDROXIDE and half of the CARBONATE +

H

+

H

+ +

OH CO

-

2-

3

H O 2 -

HCO 3