Sustained Vibrations in Cooling Towers: Should These Be a Cause for Alarm

12 September 2019

Used as mansion-sized heat exchangers, cooling towers scoop heat out of industrial-scale complexes. If a large-scale processing plant, power generation station, or petrochemical installation produces an unmanageable thermal envelope, these monolithic, open-topped concrete towers will reject the energy. But there’s a problem: industrial buildings are often filled with working machines, and those machines generate vibrations. We need to know, will this vibrational energy affect a cooling tower’s performance?

Vibrational Analysis in Cooling Tower Equipment

There are different types of inner workings within the towers. Passive equipment configurations use convection currents to remove heat from large tube bundles. A little like a conventional stacked tube heat exchanger, as used in boiler systems, large tube surface areas eject heat from the fluids flowing inside those bunched pipes. At most, a pump is needed to push the hot water through the pipe network. Vibrations won’t impact this layout, not if there are few moving parts to influence. All the same, a vibration sensing device can be fitted to track the occasional mechanically induced tremor. Sensors set off alarms or record the shake and shiver of propagating mechanical noise waves onto digitally enhanced graphs.

Active Systems Suffer When Attacked By Vibrations

The problems handled here get worse when the open-topped edifice adopts an active system layout. Let’s explain that last statement a little more clearly. Inside the cooling edifice, certain choices must be made. For a passive heat rejection architecture, natural drafts remove thermal energy to the outside atmosphere, where winds then distribute the energy far and wide. The hot water moves, it rises upwards to the wet deck and fill material because that’s what warm water does, it naturally flows to the top of a pipe or tank. These passive systems aren’t as efficient as their active counterparts, but they are definitely less susceptible to vibrational energy. With powered equipment, things alter dramatically. There are motorized pumps and fans and fanbelts moving, plus gearboxes driving the air and water. If equipment engendered noise penetrates this far, those working subsystems will age and eventually fail. Again, at least one vibration sensing device must be in place to measure and record the severity of these propagating noise waves.

Is there anything that can be done to dampen industrial-scale vibrations? Well, rubber hoses and mountings can be utilized as propagation pathway breaks. That noise buffering strategy works on industrial equipment and inside cooling towers, too. For the maintenance team, they can do their own part when encountering a clattering metal assembly. With tools on-hand, a technician can tighten up any loose fittings. Fan and gearbox inspections should also add this measure, for tiny hairline fracture can develop if vibrations aren’t tackled properly.

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