5 replies to this topic

[aragorn]

what is the reason we use air cooler before water cooler in top of the tower but in bottom of tower, we install water cooler before air cooler ?

[fallah]

what is the reason we use air cooler before water cooler in top of the tower but in bottom of tower, we install water cooler before air cooler ?

Do you think the above statement covers overhead /bottom lines of all towers?What about the reference?

[aragorn]

I don't know this is cover all unit, but i saw that in most of oil refinery unit for example distillation,catalytic reforming and etc.

[Himanshu Sharma]

Sir,

Surprisingly i have never designed or seen such a configuration.It would be a real knowledge addition if you post any PFD or throw some light on the process objective.

In my humble opinion,Air coolers are alwyas upstream of the trim coolers.This makes sense as at the first step of cooling, i would bring down the temperature within a range(typical what i have seen 55`65 deg C because of Air cooler's design and economics limitation) such that further cooling can be done by reasonable quantity of cooling water.(can be cooled raesonably depending upon cooling water outlet temp)

Reversing the configuration and maintaining the process objective is really doubtful to me.It will involve huge quantity of cooling water and downstream air cooler temperature will be limited in range of say 50`65 deg C.

Please note that these views are based on Hot summer conditions in Asia/Middle-East.

[WeiJie]

Air cooler usually cool it down to 55C (normal design), and for trim cooler (top column) you usually cooled it down to lets say 45C for phase separation which can only be done by water cooler

as for bottom column
you will need an extreme large air cooler which by means uneconomical compared to a water cooler
this is due to the properties, higher flowrate etc of the bottom product which give lower tube heat transfer coefficient


to simplify this, u will need an extreme larger air cooler to cool down bottom product compared to top product from the same operation

[Art Montemayor]

This query can't be answered without any basic data.

We don't know what the tower is, what you are doing, what you are cooling, what you are heating, etc., etc......

Spend some of your own time gathering and putting together a meaningful and well-written query and you will probably get a positive response with expert advice.