Shell & Tube Orientation

[ProjEngKLS]

I have an application for a single pass (both shell side and tube side) heat exchanger. This ia a low temperature (-70 °C shell, -25 °C tube) application primarily concerned with heat removal resulting from a chemical reactor in a batch process.

I would like to orient the exchanger vertically with tube side flow into the top and out the bottom. Shell side flow is to be counter-current. I expect a dT of -2 °C on the tube side and +10 °C on the shell side.

I have been told that horizontal orientation is better than vertical for heat transfer. This does not make any sense to me. I'd think the difference between horizontal and vertical should be negligible, and in the case of this application (with the dTs the way they are) vertical might be slightly better.

Anyone with thoughts on this?


thanks

 

[quark]

Proj!

I feel gravity is a factor. There may be less contact period if you are allowing fluid to flow from top to bottom. You may end up with valve controling below the heat exchanger.

Regards,

 

[MortenA]

If you have condensation the vertically could be preferred but if its pure liquid/gas then i dont think gravity has an influence on the efficiency (for a shell and tube - some other types of HX may behave differently).
Best Regards

Morten

 

[ProjEngKLS]

I probably should have mentioned that this is a liquid / liquid application - no phase change.


thanks

 

[abeltio]

selecting between vertical and horizontal S&T-HE is governed by several criteria... e.g. the big HP pre-heaters in a power plant are usually vertical.
What you have to consider is:
1. is foot print area at premium?
2. do you have enough headroom for maintenance if vertical is selected? conversely, is there enough horizontal room for tube bundle removal?
3. is piping arrangemente suitable for either position?
4. Good venting/drainage of shell and tubes is required for optimum performance (no air pockets)... careful on the venting, drainage arrangement of the shell side in vertical arrangement.
HTH
saludos.
a.

 

[melv]

Depending on how much sub-cooling you require, vertical condenser (subcoolers) can be advantageous. They can be fixed with a 'loop seal' on the shell-side outlet which is essentially an upside down U-bend. This prevents the fluid from draining from the HX at so rapid a rate that it emerges without much subcooling. You might find the book, "Process Heat Transfer" by D.Q.Kern helpful in this area.

Apart from that, and as long as the flowrates are controlled, there is no real difference in liquid-to-liquid subcoolers. However, what abeltio mentioned about maintenance is very important. Particulate deposition favours low areas in a process line and the HX should be accessible for cleaning approx. once a year. Is it fixed tubesheet or removable bundle?

regards,

melv