Cooling Towers or Fluid Coolers

CHEMICALS LTD., 8321 Willard Street, Burnaby, B.C., Canada, V3N 2X3Visit our website - www.pacechem.com • Phone (604) 520-6211 • Toll Free 1-800-799-6211 • Fax (604) 521-5927“Keeping with Technology”“Since 1983”Member:Clean Up That Cooling TowerHow a simple sand filter can work for youto keep your condenser water andcooling tower sump clean.Have you ever noticed how quickly a cooling tower basin canbecome loaded with solids during the cooling season, even whenyou've just cleaned and flushed the entire condenser system? Orperhaps you've found a build up of light-brown nodules when thechiller end plate is removed for the annual inspection?This is not unusual. In fact it's what you might expect when youconsider that a cooling tower is a giant air-scrubber.The air that the fans draw though the tower is hardly clean when itenters the tower. However it's nice and clean when it leaves Insidethe tower, all that dust in the air is trapped by the falling stream ofwater and is then circulated throughout the condenser system.The composition of this debris and the amount in the air dependsupon a number of factors.• proximity to exhaust outlets from industry, feed processing etc.• local activity such as building construction and roads• pollination of conifers and deciduous trees, weeds and grasses• local insect population and life cycle• surface winds• falling leavesOnce all this dirt gets into the condenser loop where does it go?The heavier material such as grit and other inorganic particles willusually end up at the low points in the system forming “dead” areaswhere under-deposit corrosion can take place. Lighter material,Benefits of a filter in an open system:à Keeps the system cleanà Reduces biocide requirementsà Prolongs the life of mechanical equipmentà Provides a warning of sudden system disruptionsà Reduces downtimeà Reduces maintenance and energy costsà Reduces corrosionà Reduces erosion of pump parts and equipmentà Maintains heat-transfer efficiencyoften organic in nature, circulates more freely throughout thesystem and is attracted to metal parts during the periods when thecondenser pump shuts off. Once on the metal surface, theseparticles tend to “stick ” by electrostatic attraction, forming thosecharacteristic nodules. These are prime sites for under-depositcorrosion because an electrochemical cell is set up between areas ofmetal that are covered by deposits and those that are not. Inaddition the deposit effectively seals off the base metal fromcorrosion-preventing chemicals.Once corrosion begins, the metal surface forms blisters whichrelease oxide particles, adding suspended solids to the condenserwater stream.Implementing and maintaining a properly designed chemicaltreatment program is the first step towards preventing corrosiveoxygen from attacking the metals in the system. However, since it isvirtually impossible to prevent the introduction of suspendedmaterial the best way to keep the systemclean is by use of a sidestream filter.By a sidestream filter we mean onewhich filters a small portion of the totalcirculation, usually between 5 and 10%.These units are available in a variety offorms ranging from large industrialunits to relatively small, inexpensivetypes produced for the swimming poolmarket. For most applications backwashable sand filters are themost economical, user-friendly solution. In the event that the filterbecomes plugged by the sudden introduction of large amounts ofmaterial, the main circulation stream remains unrestricted.The ideal protection combination is a comprehensive chemicaltreatment program used in conjunction with a side stream filter.Suspension agents keep particles suspended until the sidestreamfilter removes them from the fluid. By keeping a note of the fre-quency of backwash cycles, any unusual arrival of dirt in the systemcan be readily detected.In addition to the continuous operation of the sand filter, the towerand condenser loop should be cleaned manually to remove anyforeign material which is not circulating in the condenser water; forexample algae and fungi that tend to cling to surfaces such as pipesand the tower fill. This should be carried out at the beginning andend of the cooling season, or more frequently in cases where a highbuild up of solids is observed.Your ACE Representative can help you select the best cleaningprogram for your system. Call ACE today for more information.See Also:Vol TWO-10a, Tower operation during the winter monthsVol. OSF-10aC310