3 replies to this topic

[shihab]

Hi all,

 

I am new process engineer in crude\ vacuum  distillation unit ,during first start-up some of the stripping trays in the vacuum column has been damaged due to high level in the column bottom caused by instrument     malfunction . I am wondering how high column bottom level cause tray damage . what is role of stripping steam in this damage ? in short what is is the Mechanism of this damage . please help me understand this phenomena .

[PingPong]

what is role of stripping steam in this damage ?

Without stripping steam the trays would not be damaged as there would not be an upward force.

 

The stripping steam bubbling through the liquid will move part of that liquid upward through the tray holes, resulting in a much higher pressure drop over those trays than if only the steam flows through the holes.

[Bobby Strain]

I would replace "bubbling" with "blasting".

 

Bobby

[Himanshu Sharma]

Hi !

 

Addiny my two cents to the succint reply of bobby ,your trays are subjected to higher upward lifting force than what they are mechanically designed for.

 

The trays are already filled with liquid and steam flowing from it has to encounter the backpressure genetrated by liquid head and therafter escapes (along with entrained liquid) to a lower pressure in the column section.This genrates good amount of pressure drop in small section and ultimately your trays may lift off or damage while exceeding mechanical limits.

 

This section of vacuum tray is suspectible for damage in case even there is a sudden increase in stripping steam rates (without even a high liquid level in the column) or condensate escaping from steam line.

 

 

Thanks and regards

Himanshu