Flare knock out drum 2

[obaetan]

I am presently working on flare knock out drum sizing and I need some help on know how to determine the liquid height in the drum which in turn help me to ultimately calculate the vessel length.All other parameters such as; flowrates for gas and liquid,densities,hold up time, droplet diameter,operating temperature and pressure were given.
Thanks for the anticipated assistance.

Obaetan.

 

[MikeClay]

Not given any details, I can only offer some guidelines

Normal liquid levels in the vessel need to give enough residence time to allow the controlls to work properly to prevent either a high or low level. If pumps are used, they should not cycle to frequently.

In the event of loss of liquid outlet, a high/high alarm or interlock is needed. This should be set so that intervention can take place before the vessel fills beyond the gas handling capability for this scenario. Note that 15 to 30 minutes for operator intervention is not unusual and can lead to excessive designs if high liquid flow scenarios exist.

--mike--

 

[mbeychok]

obaetan:

You might find it useful to read this article:

http://en.citizendium.org/wiki/Souders-Brown_equation

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[MortenA]

Flare drums are special in the way that in principle you cant count on a shutdown signal to stop the flow.

Also a HH alarm should in most cases signal a plant inlet shut down - but not a general blow down (would just cause more flow to the vessel.

Hold up time is not such a relevant parameter - its more like trying to determine your largest possible source(s) of liquids that may end up there and then make sure that from LL (your normal level in the flare KO) to HH there is at least room for that.

Best regards

Morten