Cooling tower side stream filtration. Why all open cooling tower systems do not have side stream filtration? 1. Specifier not aware of technolog...

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Cooling tower side stream filtration. Why all open cooling tower systems do not have side stream filtration? 1. Specifier not aware of technology 2. The savings are minuscule compared to investment 3. Will low cost investment equipment, will be adapted in future? 4. Clear evaluation of filtering systems for this application is not available. These are my thoughts, looking forward to participation and evaluation by experts, specifier, system vendors, and operating personnel.

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  1. Side stream filters in cooling towers are recomended where one has contaimimnation because of dust particles which causes increase in suspended solids . These suspended solids tends to deposit / accumulates at plces where water slows down . These filters are used to remove these particles from circulation water. The places where this contaimination is less or is avoided by other supplimentary methods may avoid these filters.

  2. Most cooling tower specifications require water treatment controls and chemicals including conductivity control to handle the concentration of dissolved solids. In most environments surfactants used in the cooling tower treatment program will control the small amounts of suspended and airborne solids in the water volume. These are typically removed through blowdown.

    The not so typical cooling tower which may have higher solids loading due to high dissolved solids or high suspended solids may require additional help with these solids removal as they precipitate out of solution. Typically these are smaller particles which grow much larger as they remain in the system. FIltration methods such as centrifugal separation can remove these more troublesome larger particles. The smaller ones are addressed by proper chemical addition.


    There are a few cooling technologies which encourage the precipitation of solids such as electrocoagulation, Ozone, and pulsed electromagnetic current technologies which should never be operated on a cooling system without a good filtration program.


    Flow and chemical treatment is key to understanding filtration sizing. You will need to know the size of the particles you need to remove. From experience you will want to remove 98% of particles which are 40 microns or larger. Smaller micron sizes are not an issue as long as flow and chemistry are correct.


    Solids are designed to precipitate out in the hot and cold deck of the cooling tower so sweeper piping systems are recommended to keep these systems free of debris. As always a good biocide program is key to successful water management practices.