24 Power Engineering International June 2017 www.PowerEngineeringInt.com
Cooling tower technology
gearbox pain points
Plant operators and
must effectively manage
a variety of cooling tower
service issues, whether
scheduled or unplanned.
Jerome Jennings explains
the role of gearboxes in
addressing these issues
Industries that require process heat rejection often use feld-erected cooling towers to keep pace with their heat load. Cooling towers have large fans and powerful motors, which can present
a host of challenges, including excessive
sound, vibration and expense. Gearboxes are
employed to address these challenges.
Gearboxes are used as speed reducers to
slow the rotational speed from the incoming
motor to the outgoing fan of a cooling tower.
Companies that operate high-capacity
production plants, such as those in the power
industry, require cooling towers with large
amounts of heat rejection capacity.
Without gearbox technology, cooling tower
motors would be massive to directly handle
the torque required by the fan. Something so
large and heavy would be too expensive and
Instead, the speed reduction from the
gearbox acts as a torque multiplier, keeping
the motor a reasonable size and the overall
mechanical system more cost-effective.
The speed reduction from gearboxes also
optimizes the performance of the cooling
tower fan. As fan diameters increase, the fan
speed must decrease to maintain acceptable
sound and vibration levels, as well as to ensure
the structural integrity of the fan itself. Improper
gearbox sizing as it relates to the motor and