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Cooling Tower


Scaling, corrosion and biological contamination are usual
causes for functional failure in most cooling plants.

Ozonation helps in treating the water without the use of expensive chemicals making it the most Eco-friendly process. Ozone reduces corrosion rates and scaling and thus increases the life of the cooling tower.

Dirty cooling towers are the main cause of Legionella infection which goes unnoticed in India.

killer germs stalk india


Comparison of Ozone treatment vis-a-vis chemical treatment of cooling tower

Parameter Ideal Ozone Treatment Chemical Treatment
TDS With Ozone- 2000 to 3000ppm with chemicals – upto 1500ppm only No increase other than due to evaporation ;Operation under high TDS conditions possible with little risks Besides evaporation, constant build up owing to addition of chemicals necessitation frequent bleeding and so, water loss
Chloride Below 200 ppm No increase other that due to evaporation Besides evaporation, constant build up owing to addition of chemicals necessitating frequent bleeding and so, water loss
Scaling Langlier: not above + 0.5 Rhiezner : not above 7.5 Easily maintainable, scaling is reduced as the organic matrix for seeding is destroyed by Ozone Heavy scale buildup in spite of chemicals, leading to frequent overhaul and wire scrubbing of condenser tubes.
De - Scaling 7.5 - 9.5 LPM Ozone destroys scale already formed by breaking the organic matrix Questionable action .De scaling agents only add to the problem
Heat transfer efficiency No loss in efficiency No loss in efficiency with reduction in scaling upto 10 to 15% energy saving can be expected providing considerable savings in operation costs Considerable loss owing to poor and erratic control. Scale build up reduces heat transfer efficiency
Corrosion Langlier : not below -0.5 Rhiezner : not below 6.5 Industry standard - 5 mpy Easily maintainable. Ozone acts similar to Chromates used in earlier corrosion inhibitor process - passivates the metal surfaces Difficult to maintain. Heavy does of chemicals will be required, which upset other critical parameters drastically
Algae Nil in water Nil in water under controlled conditions Highly Dependant on chemicals addition
Frothing Nil Nil. No Organic sediments to cause froth. Copious due to quaternary compounds used as biocides as well as other organic
Bacterial count Below 10000 cfu / ml About 1000 cfu / ml counts is a possibility . Erratic bacterial counts .Often builds up above 10000 cfu
Legionella Nil Nil Very difficult to eradicate. Resistant to most chemicals and killed by chemicals too toxic to humans. Ironically chemicals commonly used in tower maintenance promote growth of Legionella
Sludge Minimal. Water clear Water clear. High-density sediments. Easily filterable. Increased sludge. Low density sediments not easily filterable.
Blow down To control TDS No controlled blow down will be required Water savings Controlled blow down requires large amounts of make up water increing cost of raw water treatment and effluent treatment costs
COC As high as possible to save water costs High COC , sometimes even above 25 cycles possible with good make up water quality Low COC s .Costs on water, raw water treatment and Blowdown water treatment costs

Cooling Tower Water Before and After Ozonation




Power plants are water guzzlers. In India more than 80% of the industries water consumption is by power plants. Loads of money is spent on chemical treatment of cooling towers. Millions of gallons of highly contaminated and polluted blow down water are discharged from these power plants. This is of great concern, especially when India is planning a massive growth in the power plant sector in the next 5-6 years. Each 250 Mega watt power plant blows down an average of 13 lakhs M3 of polluted water every year. With an approximate additional requirement of 2 Lakhs Mega Watt of power requirement in the next 5 years, we would be wasting atleast an additional 1000 Billion liters per year.

Adopting of a clean technology that can save water and allow the possibility of reusing the water will be the single and most important consideration for the designers of power plants.

Using Ozone as a primary biocide comes as a boon to power plants. The power plant operator will drastically reduce the consumption of chemicals required for the conventional treatment. Lots of water is saved as the use of ozone permits operation under higher cycles of concentration. Further more whenever blow down is made, the water will be less polluted as it does not contain the dangerous chemicals such as chromate, phosphates etc that are added in conventional treatment. Very often the operator is not aware of the composition other chemicals that are used during routine treatment.

World’s Largest ozonated in a Power plant : WEDECO brand of Xylem Water Solutions have won the ozone project for the Yerramarus Thermal Power Plant of KPCL . This is the largest ozonator in any power plant in the world .It comprises of 2 Units of 36 Kg per hour Ozonator and project under Turnkey including supply of oxygen plant. This is through BHEL who are the main EPC contractors . The project is likely to be commissioned end of 2017/1st quarter 2018


OTSIL can offer the following consultancy services to Power plants


Certain physical aspects of a prospective client's cooling system should be reviewed in advance of any proposal submittals to the client to ensure any potential future problems are minimized.

1. Review of Cooling Tower and Plumbing Turnover Times - Necessary to ensure adequate ozone residuals can be obtained throughout the cooling circuit.

2. Review of Heat Exchanger Process Temperatures and Flow Rates - Necessary to ensure that no low flow or high temperature conditions exist.

3. Review of Makeup Water Chemistry - Necessary to calculation maximum and minimum safe operating cycles of concentration

4. Review of Possible Contamination Sources - Necessary to identify possible prevention solutions.


1. Performance of Bubble-Froth Mixing Calculations and Preparation of First Draft Sketch of Side stream Mixing Loop and Basin Distribution Plumbing Flow Schematic Drawings

2. Performance of Injection Loop Pressure Drop Calculations and Preparation of First Draft Sketch of Injection Detail Drawings.

3. Assistance in Preparation of Equipment Layout and Plan View Drawing

4. Assistance in Preparation of List and Generic Description of Other Major System Components and Recommended Instrumentation

Phase III :Detailed Engineering, Equipment Supply , Erection, Commissioning

Phase IV : Training of operators, Maintenance of Ozone System, Trouble shooting, Cooling Tower Chemistry with respect to Ozone

Phase V: Optional: Operation and Maintenance




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