[Cooling Water Treatment] Discussion Points

• Prologue• Cooling Tower Concepts• Design & Operating Factors• Troubles & Solutions• Chemical Products

INDUCTION PROGRAM

- Md Nahid ParvezMechanical Engineer

[Cooling Water Treatment] PrologueCooling towers are used to remove excess heat that is generated in places such as power stations, chemical plants and even domestically in air conditioning units.

Cooling water is needed in the heat exchanger and it is this cooling water that is cycled through the cooling tower. In chemical processes excess heat can be generated. This heat is removed using heat exchangers and cooling water which is cycled through a cooling tower.

Process

[Cooling Water Treatment] Prologue : Cooling Tower Types

Spray Pond

Windage Loss:1 – 5%

Natural Draft

[Cooling Water Treatment] Prologue : Cooling Tower Types

Windage Loss:1 – 5%

Induced Draft

Windage Loss:0.02 - 0.3 %

[Cooling Water Treatment] Prologue : Cooling Tower Types

[Cooling Water Treatment] Prologue : Cooling Tower Types

Forced Draft

Windage Loss:0.02 - 0.3 %

[Cooling Water Treatment] Cooling Tower Concept

[Cooling Water Treatment] Operating Factors : Water Loss

[Cooling Water Treatment] Design & Operating Factors

Cooling Tower Type

No. of Cooling Towers

Circulation Volume per Cooling Tower

Total Hold-on Volume per Cooling Tower

Change in Temperature, Δ T

Evaporation Loss

Blow- Down

Make-up Water

Cycle of Concentration, COC

Water Parameters

pHConductivityTotal HardnessTDSTurbiditySilicaIronChlorideTotal AlkalinityArsenicSulfitePhosphate

[Cooling Water Treatment] Ryznar’s Stability Index (RSI)

Naturally occurring impurities in water can cause equipment to be subjected to fouling, scale formation, corrosion or rusting, and growth of microorganisms.

Left uncontrolled, any of these conditions will causes a loss of system capacity, reduced energy efficiency, shortened equipment life and frequent shutdowns.

Through effective water management, industries can achieve maximum return on investment by extending equipment life, increasing efficiency and preventing costly repairs as well as down time.

[Cooling Water Treatment] Troubles & Solutions : Water Problems

Three (3) types of water impurities

1. Total dissolved solids (TDS) – minerals naturally dissolved in water (cations & anions).

2. Total suspended solids (TSS) – silts, clay, dust, microoragamism, etc that carried by water.

3. Total dissolved gases – oxygen, carbon dioxide, nitrogen, etc that naturally dissolved in water.

[Cooling Water Treatment] Troubles & Solutions : Water Impurities

Corrosion is a general term that indicates the conversion of a metal into a soluble compound.

Two types of corrosion are prevalent: 1) Oxygen pitting corrosion, 2) Low pH corrosion.

Corrosion of either type can reduce equipment life-span and lead to failure of the system., deposition of corrosion products in critical heat exchange areas, and overall efficiency loss.

[Cooling Water Treatment] Troubles & Solutions : Corrosion

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[Cooling Water Treatment] Troubles & Solutions : Corrosion

Water formed deposits result from naturally occurring minerals precipitating from water to form scale as temperature increases.

As water is heated and converted into vapor, contaminants brought into a cooling tower with makeup water are left behind.

Scale buildup on surfaces can be extremely hard and difficult to remove.

Some examples of scale are calcium carbonate, calcium sulfate, and magnesium silicate.

[Cooling Water Treatment] Troubles & Solutions : Scaling & Deposition

Fouling occurs when solid materials form or contribute to the formation of deposits on equipment surfaces. They are introduced to the system as suspended solids and may enter by the makeup water, from corrosion products, or as airborne materials. Examples include mud, sand, silt, clay, oils, debris, organics, microbes, etc.

[Cooling Water Treatment] Troubles & Solutions : Fouling

Microbial problems associated with industrial cooling water systems are caused by algae, fungi, and bacteria.

They cause plugging, fouling, corrosion, and destruction of wooden cooling tower components.

Many different bacteria species may exist in cooling water systems.

Some of the problems caused include severe bacterial slimes and fouling, sulfuric acid, under-deposit corrosion and health hazards.

[Cooling Water Treatment] Troubles & Solutions : Microbiological Contamination

• Examples of Algae, Bacteria & Fungi.

[Cooling Water Treatment] Troubles & Solutions : Microorganism Growth

Anodic Inhibitors (Molybdate, Nitrite, Orthophosphate) to form stable, tenacious, oxide films at the anodic sites in metal surfaces. Cathodic Inhibitors (Polyphosphate, Zinc, Phosphonate) to form locally precipitated films at the cathodic sites on metal surfaces. Absorbed Layer Films (Azole compound) that provide protection layer on both anodic & cathodic sites to prevent copper and its alloy corrosion.

[Cooling Water Treatment] Troubles & Solutions : Corrosion Control Technology

Threshold Inhibitors (Phosphonate) to inhibit or retard crystal growth.

Sequestrant Inhibitors (Polyphosphate) to react with the metal ions to form soluble complexes.

Dispersants (Polymer, Copolymer) to control particle size by interfering with particle agglomeration and modify crystal growth.

[Cooling Water Treatment] Troubles & Solutions : Scale & Deposit Control

[Cooling Water Treatment] Troubles & Solutions : Scale Inhibition

Dispersants (Multi-polymer) to disperse silica particle by promoting adsorption on colloidal silica surfaces, thus preventing precipitation and agglomeration.

Polymers (Weak acid) that attach to metal ions in solution and to the surfaces of particles or crystal.

[Cooling Water Treatment] Troubles & Solutions : Silica & Silicate Scale Control

Dispersants (Polymer, Copolymer) to disperse particle and suspended to prevent particle agglomeration.

Surfactants to disperse or emulsify oils, greases, biofilms and biological deposits.

[Cooling Water Treatment] Troubles & Solutions : Anti-Fouling Technology

Oxidizing Biocide- sodium hypochlorite- calcium hypochlorite- bromine

Non-Oxidizing Biocidea) Metabolic Inhibitors

(Enzyme Poisons)- isothiazolin, carbamates, etc

b) Surface Active Agents (Membrane Disrupters)

- quats, glut, tris-nitro, etc

[Cooling Water Treatment] Troubles & Solutions : Microbiological Growth Control

DO: PERIODIC ANALYSIS REPORT & TECHNICAL SERVICE

[Cooling Water Treatment] Existing Chemical Products at plant

Product Name Almergard CWEU 2110

Almergard CWEU 2160

Almergard CWEU 2150

Almergard CWEU 2190

Almergard CWEU 2250

Type Cooling Tower Cooling Tower Cooling Tower Cooling Tower Cooling Tower

ApplicationCorrosion &

Scale Inhibitor plus

Antifoulant

Corrosion & Scale Inhibitor

plus Antifoulant for Closed system.

Dispersant & Antifoulant

Biocide for control of

Bacteria, fungi, Algae.

Microbiocide for control of

Bacteria, fungi, Algae.

QUESTIONS ?