There is a note in remarks section (Turn down is 50%)in fin-fan cooler

[hbhatti68]

There is a note in remarks section (Turn down is 50%)in fin-fan cooler specs.Can somebody explain what does it mean.

 

[unclesyd]

Normally a "turn down" is the amount of capacity that you can still operate at without affecting you controls.
50% means that you can lower the heat load on the cooler by 50% and still operate.

 

[hbhatti68]

Thanks for your help (unclesyd).
Well this is a two bay air-coolers, my point is this 50% turn down is more related to fan or fan motor or flow of fluid control to lower the heat load. I would appreciate if you can clarify.

 

[SnTMan]

hbhatti68, better ask the process guys.

Regards,

Mike

 

[JJPellin]

I work in a large oil refinery with several hundred fin-fan coolers. We are located in the Northern US. I am a machinery engineer, not a process engineer. The typical methods used for turn-down on process coolers are these:

1. Start and stop fans. Most bays have two fans with one being a two speed and one being a single speed.
2. Change the two speed fan from high to low or low to high speed.
3. Automatic controls using inlet and outlet louvers to limit the air flow through the fan.
4. Automatic controls using recirculation louvers that redirect some of the outgoing air back to the incoming side. This limits the heat transfer while keeping the steam coils from freezing up.
5. Automatic controls using variable speed drives on the fan motors. This is probably more common at other plants. We use this method rarely.

It is not common to limit the process flow rate or bypass process flow around the cooler. This is used more often on shell and tube exchangers using cooling water since pinching on the cooling water has an undesirable affect on water-side fouling.


Johnny Pellin

 

[rmw]

Read carefully the comment in the notes. Does it say 50% or 50:1? If it is the former it can range down to 2% flow. If it is the latter, it obviously only had a 2:1 turndown.

rmw