FRP Cooling Tower Fills Replacement

Unless your client ruined the wet deck fill with excessive water temperature, recirculated debris or lack of water treatment, 18 months useful life is certainly unacceptable.

-What is the water flow rate?

-What reason is given by the manufacturer for wet deck failure?

-Is the tower applied to an industrial process with possible rough duty or air conditioning which is typically less demanding?

-What does the tower look like? Crossflow, counterflow, blow thru, draw thru, prop fan, centrifugal fan? Motor size? Installed properly? Plenty of space to prevent recirculation?

Note the approach is very small making it difficult to achieve the design water temperature without a substantially sized tower. It may be that you are saddled with an undersize chassis that cannot ever be made to provide the design leaving water temperature. The answer may be to add a second tower after repairing the first tower.

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While a 3C approach is challenging, it is not impossible.

I assume that the tower was not operationally tested on installation to verify performance. Was the tower specified to be certified performance based on Cooling Tower Institute or was the performance up to the tower supplier?

Certified means that it is totally up to the tower manufacturer to make it right. "Supplier" means that- in order to sell the Client any more towers, this one will work as specified- again at the supplier's cost.

18 months is DEFINITELY not an appropriate time for fill replacement.

How far away from specified performance is the tower? Will it throw away the rated heat, but with a higher than desired leaving water temp OR is performance totally out of spec- reject heat AND leaving water?

Another option to offer the tower manufacturer is to furnish compensation based on the performance of the connected load (I assume it is a chiller)- ie: CURRENT kW/Ton at rated capacity vs. RATED kW per ton at rated capacity times annual equivalent full load hours times cost of a kWh times 20 years (the normal life of a tower). Example- current is 0.68 kW/Ton vs. rated 0.65 kW/ton, 1000 ton chiller with 1800 equivalent full load hours (based on recorded average daily weather data) and $0.127 per kWh (based on power cost and demand cost) = $6,858 per year times 20 years for a total of $137,160. (a lot bigger than you thought for ONLY 0.03 kW/ton)

If they will not upgrade the tower to run as specified, your client will sue them for the added costs that the Client is facing. Bet they fix the tower.

I have installed FRP cooling towers. The devices that I have in mind are of Oriental provenance and have corrugated plastic fill. They have a top-mounted exhaust fan which draws air through the fill.

If I have identified the cooling towers you are talking about then I wonder:

Did the units actually perform satisfactorily at the beginning?

Did the manufacturer's representative actually visit the site or was the advice via telephone?

What was the representative's reason for replacing the fill? Was the fill degrading in some way?

Have you examined the fill yourself? Is there evidence of precipitate build-up on the fill?

That might tell you something. Water treatment?

With an approach that small the challenge will certainly be to keep the fill as clean, from buildup and slime, as possible. If the supplier dont do fill cleaning they will promote replacement. Perhaps they felt a different design fill will help to improve duty. Nevertheless, if the supplier is not the original installer, they should do all the spec work again.

The fill may have choked partially leading to channelizing of flow. There can be flooding of the bottom portion of the fill leading to a similar situation to asthma in human lungs. Since the wet bulb temperature is near the required outlet temperature and the entering temperature is also low, any reduction in area can adversely affect performance. Have you tried removing the fill and cleaning it? It is only the available wetted area of the fill that counts. Performance cannot drop if this parameter is maintained, The fill itself does not participate in heat transfer. Even if the fill surface is having scale or other film it should continue to function. bioramani