SPX Cooling Technologies 600 manual Mechanical Equipment, Fans, Fan Cylinders

/ Mechanical Equipment /

Fans

Marley designed and manufactured fans are used on all Marley crossflow towers. The fan selection and fan speed for a given tower are based on tower cell size, system losses, and horsepower requirements. Depending on fan size, blade material is FRP (fiber reinforced polyester), GRE (glass reinforced epoxy), or cast aluminum alloy. Above 20′-0″ diameter, Marley’s HP7000 hollow core fan with erosion-resistant leading edge is standard. Large fan hubs are heavy-duty steel plate and ductile cast iron components, hot dip galvanized after fabrication. Smaller fan hubs are either epoxy-coated cast iron or heat-treated aircraft aluminum alloy plate. All fans are assembled with series 300 stainless steel hardware, and all materials have been selected for the harsh cooling tower environment.

Marley fans are applied in accordance with data from model tests conducted in the wind tunnel at the SPX Cooling Technologies’ Research and Development Center. Model fan designs are tested in simulated cooling towers, and are fine-tuned to maximize efficiencies

at actual conditions. The commercially available fans used by other cooling tower suppliers lack this design advantage. Consequently, they are often applied at flow and pressure conditions for which they are ill suited. Unpredictable lower efficiencies result, with proportional reduction in tower capacity.

Fan Cylinders

Venturi-shaped FRP cylinders combine minimal entrance losses with close blade tip clearances to produce optimum fan performance. As cylinder heights increase, cylinders are progressively flared to promote recovery of velocity pressure—allowing fans to move the required amount of air at significantly reduced horsepower.

Unlike those used on other towers, Marley fan cylinders have exceptionally large entrance diameters which contribute to the “eased inlet” effect so necessary to good fan performance. Smaller entrances do not provide sufficient transition to deter turbulent flow at the fan. Marley fan cylinders are through-bolted to the fan deck and supporting framework. The combination of a large foundation “footprint” and through-bolting has enabled Marley fan cylinders to withstand wind velocities in which other fan cylinders have failed.

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