Forced Draft Cooling Towers

Miscellaneous Mechanical Components DOE-HDBK-1018/2-93 COOLING TOWERS Makeup valve - The makeup valve is a valve that introduces fresh water into the collection basin to maintain the desired collecting basin water level. Overflow - The overflow is a drain that prevents the collecting basin from overflowing. Partition - The partition is a baffle within a multicell cooling tower that is used to prevent air and/or water flow between adjacent cells. Plenum - The plenum is the internal cooling tower area between the drift eliminators and the fans. Speed reducer - The speed reducer is a right-angle gear box that transmits power to the fan while reducing the driver speed to that required for optimal fan performance. Sump - The sump is a depressed portion of the collecting basin from which cold water is drawn to be returned to the connected system. The sump usually contains strainer screens, antivortex devices, and a drain or cleanout connection. Distribution system - The distribution system is that portion of a cooling tower that distributes water over the fill area. It usually consists of one or more flanged inlets, flow control valves, internal headers, distribution basins, spray branches, metering orifices, and other related components. Forced Draft Cooling Towers Forced draft cooling towers are very similar to induced draft cooling towers. The primary difference is that the air is blown in at the bottom of the tower and exits at the top. Forced draft cooling towers are the forerunner to induced draft cooling towers. Water distribution problems and recirculation difficulties discourage the use of forced draft cooling towers. Natural Convection Cooling Towers Natural convection cooling towers, illustrated in Figure 12, use the principle of convective flow to provide air circulation. As the air inside the tower is heated, it rises through the tower. This process draws more air in, creating a natural air flow to provide cooling of the water. The basin at the bottom of the tower is open to the atmosphere. The cooler, more dense air outside the Rev. 0 ME-05 Page 21