Miscellaneous Mechanical ComponentsDOE-HDBK-1018/2-93COOLING TOWERSMakeup valve -The makeup valve is a valve that introduces fresh water into thecollection basin to maintain the desired collecting basin waterlevel.Overflow -The overflow is a drain that prevents the collecting basin fromoverflowing.Partition -The partition is a baffle within a multicell cooling tower that isused to prevent air and/or water flow between adjacent cells.Plenum -The plenum is the internal cooling tower area between the drifteliminators and the fans.Speed reducer -The speed reducer is a right-angle gear box that transmitspower to the fan while reducing the driver speed to thatrequired for optimal fan performance.Sump -The sump is a depressed portion of the collecting basin fromwhich cold water is drawn to be returned to the connectedsystem. The sump usually contains strainer screens, antivortexdevices, and a drain or cleanout connection.Distribution system -The distribution system is that portion of a cooling tower thatdistributes water over the fill area. It usually consists of one ormore flanged inlets, flow control valves, internal headers,distribution basins, spray branches, metering orifices, and otherrelated components.ForcedDraftCoolingTowersForced draft cooling towers are very similar to induced draft cooling towers. The primarydifference is that the air is blown in at the bottom of the tower and exits at the top. Forced draftcooling towers are the forerunner to induced draft cooling towers. Water distribution problemsand recirculation difficulties discourage the use of forced draft cooling towers.NaturalConvectionCoolingTowersNatural convection cooling towers, illustrated in Figure 12, use the principle of convective flowto provide air circulation. As the air inside the tower is heated, it rises through the tower. Thisprocess draws more air in, creating a natural air flow to provide cooling of the water. The basinat the bottom of the tower is open to the atmosphere. The cooler, more dense air outside the Rev. 0ME-05Page 21
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