Benefits of Sidestream Filtration In Cooling Towers

Cooling towers scrub large volumes of air and effectively remove solids consisting of dust, microbiological organisms, and various airborne debris. Makeup to the tower adds suspended solids as silt and mid. The cooling system itself contains solids in the form of corrosion products, microbiological growths, wood fibers from the tower, and process leaks. If allowed to settle out, these solids can and do generate many problems within the system.

A proven method to help manage these, and other issues surrounding cooling towers, is to install a properly designed sidestream filter. This can benefit your system through:

1) Reduced Corrosion Rates
2) Increased Equipment Life
3) Better System Efficiency
4) Reduced Maintenance Costs
5) Reduced Energy Costs
6) Better Chemical Control

By identifying potential threats to your systems and solutions to those threats, you can determine the paybacks of installing a sidestream filtration system. Often the payback is less time than you would think. It is strongly recommended that a particle analysis be done on the representative stream that is to be treated. This can be reviewed while planning your sidestream treatment. For most sidestream filtration, a centrifugal style filter is optimal. It will remove the major problems your system faces and require very little maintenance or repair. However, each filter does have its limits.

Centrifugal Filters. Minimum size particle typically removed is 80 micron. This happens only when the particles are all 1.2 times the density of water or higher. These types of filters are more likely to be found in a mixed stream where 200 micron can be planned upon.

Auto-Backwashable Screen. This screen size is relatively absolute so the system can be customized to the particle size desired. Screens are available down to 20 microns (10 microns listed, but is nor real durable for most tower applications). There is a problem if the particle size goes too low. The amount of water needed to backwash the screen can be excessive. Also, the debris can stick to the screen requiring manual clean up.

Bag Filters. This filter requires labor in changing out the bags when full. However, bag filters offer the flexibility of adjusting the micron filtration provided when needed (for instance in cottonwood seed time).

Cartridge Filters. The initial expense of these filters is comparable with other filters, however the ongoing expense is much higher. Cartridge filters offer flexibility like bag filters, but with little or no bypass.

Sand Filters. While sand filters are the most expensive of all the filters listed here, they are proven effective and reliable. When set up to backwash on pressure differential, they can handle load variations with manpower.

A site survey and consultation with US Water Engineering and Equipment division can be beneficial. Schedule the time before you need becomes critical. Contact our Engineering and Equipment office today at 763-553-0379 or email info@uswaterservices.com for more information.