Cooling towers act as air scrubbers, collecting dust and debris from the air and water used in their normal operation. In built-up city environments or industrial locations, airborne typical dust levels of 15 to 200 mg/m3 are typical. A 2000 kW heat rejection cooling tower would accumulate 16 kg per day of solids at only 25% duty load.
This level of dirt loading, unless removed, would cause progressive fouling of heat exchangers, leading to fouling factors of 0.0001 or above. For heat exchangers designed with typical fouling factors of 0.00004, this would reduce heat exchange performance by 20 to 25%, increasing energy consumption by 8 to 12%.
The STC Series of cyclone filtration units are designed for sidestream filtration on cooling towers, evaporative condensers and open circuit systems, for removal of suspended solids and sludge.
A sidestream flow is drawn from the cooling tower sump and cleaned continuously by the filter before being returned to the sump. Suspended solids collected in the filter are purged to drain automatically using a timer controlled auto purge valve.
Filtration of cooling water reduces chemical treatment requirements of the cooling system by removing suspended solids, which harbour and encourage biological growth.
The Health & Safety Executive Code Of Practice L8 (2000) recommends filtration of cooling systems to reduce the risk of Legionellosis, where continuous usage or access limitations preclude frequent shutdown for cleaning and fill pack removals.
The system removes settle-able solids down to less than 20 micron on continuous recirculation.
Max operating pressure 1.5 bar:
Max operating temperature 35°C
Systems for higher pressures and temperatures available, details on request.