Side stream filtration is the diversion of a small portion of the circulating cooling water (typically a few percent of total flow) through a filter. It removes suspended solids, debris and biological growth keeping the whole cooling loop cleaner, more efficient and better protected.
Where Filtration Is Required for Cooling Tower:
- Cooling tower basin: Removes dirt, airborne dust and debris that is washed in from the air.
- Recirculation loop: Prevents solids from entering the pumps, heat exchangers and condenser tubes.
- Chiller and condenser circuit: Protects heat transfer surfaces from scale and fouling particles.
- Spray nozzles and fill media: Prevents clogging that reduces cooling efficiency.
Contaminants Impacting the Cooling Tower:
- Dust and dirt in the air: Enters through the open tower and settles in the basin.
- Silt and suspended solids buildup in the basin and on heat transfer surfaces.
- Scale particles (calcium carbonate) Deposits on tubes and lowers heat transfer.
- Rust and corrosion products: Pumps, nozzles and tubes should be abraded.
- Algae and biological growth – forms slime that soils surfaces and provides substrate for microbes.
- Oil and process leakage: Coats heat exchangers and lowers the efficiency.
Process Problems in Cooling System:
| Issue | Cause | Impact on the Cooling System | How Side Stream Filtration Helps |
|---|---|---|---|
| Fouling | Silt, dirt, and sludge | Lowers heat transfer and raises condenser temperatures | Removes solids before they settle on surfaces |
| Scaling | Scale-forming particles and high cycles of concentration | Insulates tubes, cuts efficiency, and increases energy use | Removes scale particles and reduces deposit formation |
| Biofouling | Algae, slime, and microbial growth | Blocks flow, promotes corrosion, and raises microbial risk | Captures biological matter and supports treatment programs |
| Corrosion | Rust, corrosion products, and under-deposit attack | Damages tubes, pumps, and piping | Removes abrasive and corrosive particles |
| Plugging | Debris and fine particles | Clogs spray nozzles and fill, reducing cooling capacity | Keeps the circulating water clean and free-flowing |
| Basin Sediment | Dust and debris from air | Reduces basin volume and encourages microbial growth | Continuously cleans the basin water |
Advantages of Filtration for Cooling Towers:
- Cleans heat transfer surfaces for improved cooling efficiency.
- Reduces fouling, corrosion and scaling in condensers, chillers and piping.
- Lower energy and water costs due to reduced blowdown cycles and improved heat transfer.
- Prolongs equipment life and reduces unplanned shutdowns.
- Reduces solids and biological load supports treatment programs.