3 replies to this topic

[akstapp]

All:

 

I have a general question about condenser orientation.  What are the reasons for installing a condenser in the vertical position vs an inclined position? 

 

Info about my specific situation:

* Current condenser is shell and tube, process is tube side, CW on shell side 

* Process fluid is mostly H2O with about 4% formaldehyde in it.  (There are also small amounts of potentially freezable components if a process upset occurs.) There is also some nitrogen, which is noncondensable.

*Current condenser is in an inclined position.

*Noncondensables are taken out at the outlet end of the tube sheet

*Process side is sub-cooled

 

I am 'copying' a current design for new installation in another location and am just wondering why this position was chosen.  The folks I've talked to at work have all said that this orientation is very common in our application, and the reason they've given for inclined orientation is that it helps the exchanger drain better - which would also be the case in vertical position.  (This is a very old installation, so all the folks that worked on this originally have long since moved on.)  It makes sense to me that the exchanger would not be horizontal because of the risk of freezable components potentially getting held up in the exchanger if it doesn't drain quickly, but I can't figure out why you would go inclined vs vertical. 

 

Thanks in advance.

 

 

[Pilesar]

In general, consider that condensing heat transfer coefficients are higher for horizontal tubes by as much as 2 or 3 times the same tube in vertical orientation. The reason is related to the layer of condensate film formed on the tube surface. The condensate film is thin only near the top of the tube. For a horizontal tube, the thin film area is larger, therefore easier condensing.

[S.R.Shah]

Well said in previous reply.Horizontal position resembles Dropwise condensation.This means that vapor condenses,form liquid drop and disengages from heat transfer area.This shall ensure thin film and greater overall co efficient.

In your case of freezing components,ii is better to have horizontal position as vapror condenses at just lower than boiling point and drops in liquid.Lower contact rimes and higher temperature prevents freezing.However it also depends on coolant selection or wall temperature.

Inclination in heat exchanger required only for easy removal of condensation. Inclination of heat exchanger should be as low As possible to take advantage of Dropwise condensation

Other point is in Horizontal position . condensate temperature is Greater than vertical position as there is minimum sub cooling possible.If it is required,one can choose separate sub cooler with colder coolant

[S.R.Shah]

Please also refer Heat Transfer by D.Q.Kern for calculation of Heat transfer coefficient