Can fin fan cool water below outside temperature 1

[kmcoinc]

Hi,

We are trying to change our cooling tower for fin fans, the problem is that we need to cool the water from 130 to 85F. We are situated in texas so I am afraid that we will not be able to cool the system below 100F during the summer using fin fans.

Thanks for your help on this one

Aitor

 

[ash9144]

Fin fans have no evaporative cooling effect therefore will be limited to reaching ambient temperature with an infinitely long fin fan cooler. A cooling tower does have evaporative cooling effect and therefore is limited to a theoretical minimum of the wet bulb temperature which is at least a few degrees cooler than ambient even on the TX gulf coast.

I would be surprised if got to 100 deg F in summer months in TX.

 

[kmcoinc]

Thanks ash9144, we are using cooling towers now and they are working perfectly, the problem is that the facilities next to the cooling tower are getting corroded.

I guess the only solution to eliminate our corrosion problems is to move the cooling towers far from the tanks and reactors.

 

[ash9144]

Cooling tower over spray is a very corrosive mixture that is often overlooked. Many places have critical equipment too close to cooling towers leading to external corrosion issues.

You could try a painting program on the equipment next to the towers or possibly a separation wall. May be easier than relocating the towers.

 

[whammett]

"I would be surprised if got to 100 deg F in summer months in TX."

Even in mid and east Texas the temperature often get in triple digits, especially during august and september.

"Scientists dream about doing great things. Engineers do them." -James Michener

 

[Chance17]

You may want to consider a wet surface air cooler.
There is a current discussion thread
Heat transfer & Thermodynamic Engineering

 

[rmw]

The wet surface manufacturer doesn't claim to be able to get as close of an approach temperature to wet bulb (the coldest possible temperature with a cooling tower) but they do claim to reduce, if not do away with cooling tower overspray (drift).

If your process fluid is able to be run directly into the tubes of a WSAC, then you will avoid the double approach of CT to atmosphere plus HX to process. About the best you can get there with the best CT technology and the best Hx technology is 7+5 = 12 degF respectively.

If you still have to have cooling water and use Hx's, the WSAC Mfg only claims to be able to get a 10 degF approach to atmosphere (wet bulb). Then the very best you could be is 15 degF approach to wetbulb.

rmw

 

[CTDon]

Perhaps your cooling tower is in need of repair which leads to excessive spitting. Get a good sales rep out there who can check the condition of your eliminators. Maybe someone tried to squeeze more capacity out of the tower by fooling with fan pitch, sheave size or something. Spitting is rarely a huge problem for towers operating properly. If it comes to your buying a new tower, buy one that is oversize with an undersize motor. Spitting will be near zero and you'll save some energy along the way.

 

[sshep]

Finfans will struggle in the summer.

These ideas might help:
Reduce the air flow on your cooling towers (the airside flow is ultimately the energy that goes into producing drift), inspect and repair your drift eliminators, consider changing from a crossflow to more efficient counter flow design, consider segregating users that don't need as cold a water and use finfans there so as to unload the tower.

The Cooling Tower Institute (CTI) has a number of technical papers on drift measurement and control which might be of interest to you. Your cheapest bet is going to be to really understand the drift problem and address that rather than replace the whole system.

best wishes,
sshep

 

[kmcoinc]

Thanks a lot for all your comments, I think I have enough information to continue my research from here.