Separator Nozzle Energy

[PonchonSavarit]

I am wondering if you guys can help me. Some of my technical mentors taught me years ago to size separator nozzles with nozzle energies (rho * v-squared) being no more than 800-1000 for the inlets and 1200 for the outlet. (English units)

I get challenged on this a lot at work. I need a technical reference.. One engineer told me Kister has a paper on it. I can't find it. Anyone have any ideas!?!?

My separators work just fine BTW.

 

[MJCronin]

Ponchon,

I believe that the following may be of use to you. Nozzles are sized on a momentum or velocity basis:

http://petrowiki.org/Separator_sizing

In addition, the maximum velocity should be checked for erosion potential (see API RP14E)

Please share with us your final design or any other references that you find.....

Separator nozzle sizing must not be confused with nozzle sizing and limitations for TEMA shell-and-tube heat exchangers.


MJCronin
Sr. Process Engineer

 

[MJCronin]

http://www.eng-tips.com/viewthread.cfm?qid=155207

MJCronin
Sr. Process Engineer

 

[EmmanuelTop]

If you are speaking of references, almost every design standard I have come across uses the fluid momentum for sizing inlet and gas outlet nozzles of a separator vessel. Some of these resources can even be found online, e.g.:

http://det-mop.ir/ips/pr/e-pr-880.pdf

An important thing to be aware of is that an increasing momentum of the separator inlet stream increases dispersion of liquid droplets. Energy of an excessive momentum is converted into breaking of the liquid phase into smaller droplets and ultimately into a very fine mist, which can make the separator almost completely inefficient. The higher the momentum, the more intensive is atomization of liquid phase.

Excessive momentum in the gas outlet nozzle can create something that is called a "sucking effect" and render a major part of the cross-sectional area of the demister useless. I've also heard of excessive momentum in the gas outlet nozzle being able to damage/dislodge vessel internals, but I never came across a document which would substantiate this statement.

Dejan IVANOVIC
Process Engineer, MSChE

 

[gr2vessels]

Hi Ponchon,
Another good reference is DEP 31.22.05.12 which has some generous allowance for inlet momentum. Their limit on using a Schoepentoeter is 8000 Pa for G/L/L separation and no device limit is 1400 Pa, provided liquid velocity is less than 1 m/s. The use of inlet devices allows the control of separator size, feasibility of the equipment being as important as the separation process. A simple half pipe inlet device can increase the inlet momentum to 2100 Pa. You can also free download the DEP from the net.
Cheers,
gr2vessels