O3 Greentech Application – Cooling Tower
Cooling towers are used by huge manufacturing plants to eject waste heat from the plant. For this, the extra heat produced by the machinery is transferred to water. As this water gets heated, it is brought in contact with air which helps small amounts of water evaporate thereby cooling the water.
This cycle keeps going on – Water enters the cooling tower hot after absorbing the heat from the machinery and leaves the cooling tower cold, ready to absorb heat again.
Suffice to say that the route followed by the water within the cooling tower is highly susceptible to microbial contamination such as bacteria, legionella, algae, fungi, and mollusc. Such contamination can affect the quality of water, creating problems such as:
- Heat transfer efficiency
- Increased corrosion
- Potential system failure
Ozone – the natural decontaminant
While injecting biocides in the cooling tower may seem like a good idea, but there is a high risk of water pollution which may create a new set of problems for the machinery and the environment.
In such a situation we need a natural gas like Ozone to help disinfect the water in the cooling tower without any negative side effects.
How Does it Work?
The use of ozone in the cooling tower is a simple process:
- Ozone is produced on-site from the atmosphere.
- It is then introduced directly into the cooling water via side stream injection. Alternatively, it may also be introduced directly into the cooling tower reservoir under certain pre-defined conditions.
- Once dissolved in water, the ozone proceeds to oxidize the contaminants in the water, thereby leaving behind cleaner water for reuse.
The amount of ozone injected is depends specifically on the system and can be adjusted automatically according to the water demand.
It is also possible to combine the Ozone with suitable corrosion inhibitors to produce even better results – a cleaner cooling tower and purer water for the same.
Chemical Treatment Vs Ozone Treatment
| Chemical Treatment | Ozone Treatment |
|---|---|
| Water is treated using chemicals involving different types of metal compounds, organics, biocides, pH stabilizers | Water is injected with a steady stream of ozone which dissolves in water |
| After a few cycles, water becomes unfit for reuse | Water can used again and again |
| Bacteria and other such contaminants develop an immunity towards the chemicals, rendering them ineffective after some time | Ozone reacts with the bacteria and oxidises it, there is no way the bacteria can develop immunity towards oxidation. |
| Risk of biofouling | No such risk |
| Shorter blowdown cycles as the water gets more and more polluted due to the chemical treatment | Longer blowdown cycles because the resulting water is cleaner. |
| Too much concentrated chemical residue in water | Less chemical residue which can be easily discharged in the sewer |
| Biofilm created by chemicals protect the bacteria | Ozone removes existing biofilms and prevents any new ones from forming. |
Features of Ozone Treatment
- Low maintenance cost of tower and condenser unit
- No more storage of chemicals
- Complete elimination of algae growth and bio-fouling/biological slime
- Removal of scaling on condenser and sheets
- Limited blowdown resulting in major water saving
- Organic and inorganic disinfection using precipitation
- Reduced rate of corrosion – increased life of equipment
Advantages of Ozone Treatment
- Ozone is a powerful disinfectant
- Assured excellent quality of cooling water
- Effective control of legionella
- No storage or handling of hazardous chemicals – safe working environment
- Compliance of blow down water with strict AOX and COD standards
- Improved cooling system efficiency through better heat transfer
- Fully automated transfer – no manual intervention
- No harmful by products
- Prevention of microbial regrowth
- Easy integration process in existing plants