Cooling Tower Shroud 2

[JHwatkins]

Hi All,

We have a very old cooling tower that is experiencing vibration at the motor. It is reading one times motor speed and showing unbalance. From what I can see the shroud on the cooling tower is drooping down and contacting the fan blades. We need to replace the shroud but we can not get a replacement for awhile. Also we are replacing this tower in a year.

Has anyone just removed the shroud and had any problems running the cooling tower? What is your expected efficiency loss?

I would rather run the fan with no shroud than run it with a broken shroud or partially removed shroud. Any thoughts or experiences from others would be greatly appreciated.

 

[MikeHalloran]

First, tighten the motor mounting bolts.


Mike Halloran
Pembroke Pines, FL, USA

 

[JHwatkins]

Thanks Mike,

We will do a second check on that for sure. The frame/structure is pretty old and rusting out so we have considered the idea that we may not be true. The bearings in the motor seem to be okay looking at the vibration report, what we are seeing is unbalance. Could be coupling shaft is unbalanced as well. We will do all the needed checks for sure the only thing I was wondering is if anyone has had experience running their cooling tower without the fan shroud.

 

[TheTick]

Shrouds keep air moving in the right direction. Good chance you will fail to keep something cool that should be cool.

 

[LittleInch]

I doubt anyone would voluntarily remove a shrouds from such a fan so not sure you're going to get anything. Clearly more efficient but for that size of fan rotating relativity slowly can't see it being more than 20% less so long as you don't remove the shroud below fan level. Only way to do it is get a cooling tower vendor to give you a quick calc based on similar sized unit with and workout shroud. I'm sure their sizing software will allow you to run both scenarios.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Lnewqban]

Those big heavy blades are where the main imbalance should be.

I would trim off all those falling apart sections of the shroud and would balance the blades (checking for deformations, deposits, etc.) until replacement time arrives.

You could try improving the bracing of the whole structure, anchoring of motor, coupling, bearings, etc. and even patching the shroud with some sheetmetal and rivets, if you have the budget.

"Where the spirit does not work with the hand, there is no art." - Leonardo da Vinci

 

[JHwatkins]

Thanks for all the responses, I think we will see if we can patch it and if not we will just remove the broken shroud pieces. Also we have checked blade pitch and all blades are where they need to be. Mounts under gearbox are rusted out and we may be getting soft foot so I will see what we can do about making that more ridged.

 

[CouplingGuru]

Seems like you have a lot of potential sources of the vibration, I would be surprised if the coupling is one of those sources. Maybe your potential soft foot, is causing some misalignment induced vibration, but that is the couplings response to the soft foot.
If you still think the coupling could be a potential contributor, take a picture of it and I can check if anything looks out of the ordinary for you.

When it comes to couplings we are always here to help.

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