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Cooling water filtration


Cooling towers are an effective way to remove waste heat from or to cool the circulating water for systems including air conditioning units, oil refineries, thermal power stations and petrochemical plants. 
 
 
 
 
However, the nature of cooling tower operation lends itself to large amounts airborne debris such as dirt and dust washing into the cooling system water. This can then create a very dirty, warm and bio-nutrient rich environment within the cooling tower, which is a perfect breeding ground for micro-organisms, algae and fungi. This can potentially cause serious health concerns (Legionella is one such type of harmful bacteria that can breed in water cooling systems).

These fungi and bacteria developments can resist treatment because they are usually hidden under a layer of dirt, which absorbs these treatment chemicals.

An adequate filtration system removes the suspended dirt and debris, allowing your treatment chemicals to properly address bacterial threats. They also reduce the chemical consumption of the cooling water system in two ways:
  • Reduced blowdown and treatment make up water lends itself to a decrease in overall chemical treatment
  • Reduced need for algaecide/biocide treatments
Waterco provides Sidestream filtration systems for cooling water systems. This type of solution continually extracts part of the total system’s water volume to be filtered; after several circulation cycles, all water has passed through the filtration system. This combined with an agitation system (which can be installed in the basin of the cooling tower), is a particularly effective combination to ensure high water quality. Agitation creates a turbulent environment below the water level to minimise the amount of suspended matter that settles into sludge on the low velocity areas of the basin. To achieve high quality water in the system, filtration once per hour is recommended.

Waterco’s Sidestream filtration options include:
 
  • Trimline bag filtration: Bag filters are a user friendly option, with an ergonomic screw down lid designed especially for quick filter changeover. Offering favourable operating cost benefits, bag filters are effective at removing dirt and debris particles that are more than 1-30µm in size. These are suited better to smaller cooling water systems because of their limited dirt holding capacity.
 
  • Trimline cartridge filtration: Like bag filters, cartridges are a cost effective filtration solution for smaller cooling water systems. Cartridge filter media is constructed from a polyester pleated fabric with a larger surface area to maximise dirt holding capacity and extend times between cleaning. An easy locking ring system allows for easy cartridge removal; however they can be costly to replace.
 
  • Granular/sand filtration: This is the best choice for HVAC applications, as it requires minimal operator attention. This type of filtration removes particles between 20-40 microns in size. Granular filters only require a turn of the multiport lever to reverse the flow of the filter to flush out trapped contents to waste. This process can be automated for ease of maintenance.  
 
  • Centrifugal filtration: Waterco’s Multicyclone uses the most advanced hydro cyclone technology to ensure high water quality and clarity, in addition to reducing maintenance and water waste. MultiCyclone PRO operates by using centrifugal filtration; incoming water enters 16 hydro cyclones tangentially, generating a strong centrifugal effect. This process draws the unfiltered water into its spinning chamber, which sends sediment to the wall, leaving clean water in the centre. The filtered water then migrates towards the centre of the hydro cyclone, where the flow reverses and spirals upwards through the outlet.