Vertical Thermosiphon Reboiler

[A.T]

Why is there a configuration of Vertical thermosiphon reboiler working with steam as heating medium in shell aide along with condensate pot with Level controller on the pot outlet which gets signal from reboiler condensate level and also condensate pot level?
why don't we use only steam trap rather than the condensate pot?

Also in the first configuration , when changing the feed rate to the column and increasing the steam flow , the reboiler frequently gets out of service?

 

[georgeverghese]

Thermosyphon reboilers do not perform well during flow turndown - the 2phase return line will see slugging flow, which leads to level instability in the product reboiler sump - it is no use trying to tune the LIC under these conditions.
To avoid this, try one or both of these :
a)keep internal descending flow from column top constant i.e. keep the reflux flow constant
b)recycle some of the bottoms product back to column feed

Ideally, for flow turndown applications, a kettle reboiler ( TEMA BKU/AKU or similar) would have avoided these problems.

A steam condensate pot type level control scheme is obviously much better than a steam trap. It has the added benefit of varying the duty of the reboiler (through column bottom tray TIC) by auto adjusting the steam condensate level on cascade control, which you cannot do with a steam trap.

 

[pierreick]

Hi,
Consider this paper to support your work.
Thermosyphon is a difficult piece of equipment, you don't want to operate it far from its design.
Make sure your steam is saturated not overheated prior to enter the unit.
Good luck
Pierre