3 replies to this topic

[kenalizer]

Hi there,

 

I am trying to design a flash drum.

 

I have read in previous posts that for a low vapour/liquid ratio, a horizontal flash drum is preferred.

 

So, is having a feed with vapour fraction of 0.1185 enough to justify why a horizontal flash drum is chosen?

 

If so, could someone recommend me literature resource to do sizing for horizontal flash drum?

 

I am using Separation Process Engineering by Wankat. P for my reference. It is a good book but there is not much calculation on the horizontal flash drum except a few empirical correlation to convert values from vertical to horizontal flash drum.

 

Thank you. 

 

 

[Himanshu Sharma]

Hey !

 

Lets optimize Flash Drum selection.

 

Liquid load translates in more liquid Hold up volume and Vapour load translates to V-L Disengaging space above feed nozzle,both combined volumes along with provision of nozzles is your flash drum size.In case,your liquid volumes are higher you have to go for Horizontal drum to optimize and vice versa for higher vapour load.

 

Just a word of caution for your design,your vapour fraction in feed you know but while flashing it to lower pressure may increase vapour load.

 

I assume you know vertical Flash Drum sizing,caclulate critical velocity for separation and a suitable margin over it (0.7 Critical velocity as  design velocity)after that design is simple,assume a higher horizontal drum volume than what is required for  liquid holdup and check for availbale vapor disengaging space (Height above High Liquid Level),iterate till you reach to required vapor disenaging space.

 

Regards

Himanshu

[Pilesar]

The total flow to the flash drum matters when selecting orientation. Vertical flash drums are the less expensive design in most cases. Size the vertical drum and see how much the sizing is affected by the required liquid residence time. If liquid capacity is a huge factor and causes you to greatly increase drum diameter or height, then size the drum for horizontal orientation and compare the two designs. The GPSA Engineering Data Book is my favorite resource for sizing flash drums.

[Bobby Strain]

You can go to my website (Google my name) and size both orientations.

 

Bobby