Thermosyphon Reboiler - Distillation Columns

I think perhaps a diagram of your apparatus would be helpful, along with a clearer definition of what you are trying to achieve, as well as better description of what is happening.

I am no expert in this subject, but I don't think there is enough information here to give a thorough answer. Good luck!

As YoshP said, more information please.

Need more information but...

Thermosyphen reboilers can be problematic.

I assume that it is steam heated. I have seen many instances where the design fouling factor gives you a much higher heat capacity than needed to circulate and reboil. If the condensate is being trapped and sent to a condensate return system than you may not be able to get a low enough steam pressure in the shell to maintain proper operation. It may not be able to be tuned out, although some will insist it can.

The result is:

1. The level gets high and calls for steam. The steam supply opens and blows out the condensate as the shell pressure increases.

2. The Vaporization and pressure in the tubes blows all the bottoms out and the level drops.

3. The steam controller hunts for a controlling point that is low. The shell pressure drops below the condensate return pressure and the shell fills with condensate.

4. The low level shuts off the steam and the level rises again.

5. Return to step 1.

There are several solutions that you need to determine with more information.

You can allow the reboiler to foul and reduce the capacity and allow the steam controller work in a range compatible with the condensate return (Higher pressure in the shell)

Or you can change the control system to a re boiler shell side level control that maintains steam pressure and drains out condensate and uncovers more tubes to increase heat and lower level and cover tubes by raising the condensate in the shell to raise the level. I wish I could take credit for that one but it was proposed in Chemical Engineering magazine many years ago.

Best I can do wtih the limited details.