1/6/14 Chemical plant design & operations - Separator Vessel Nozzle Velocity and Momentum

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Separator Vessel Nozzle Velocity and Momentum thread124-155207

bmp28 (Chemical) 19May

066:34

Hi guys,

I'm checking 2 phase separator vessel inlet nozzle velocity and momentum,, using various guidelines and refereces, but nothing conclusive.

One company internal guideline for separator inlet nozzle rho v2 suggests,-No inlet device rho-v2 <1000 kg/ms²-Pipe inlet device rho-v2 <1500 kg/ms²-Vane type inlet device rho-v2 <6000 kg/ms²

When used inconjunction the velocity limits of 10-25 m/s for vapor and 8-15 for mixed phase flow, the rho v2 limits are breached.

Is there a guideline like API RP or Shell DEP that suggest the maximum velocity and momentum limitation in separators?

Which is governing, velocity or the momentum?

Thanks in advance,bmp28

katmar (Chemical) 19May

067:34

One free standard that is available is the NORSOK P-100

http://www.standard.no/pronorm-3/data/f/0/01/41/0_10704_0/P-100.pdf

Katmar SoftwareEngineering & Risk Analysis Softwarehttp://katmarsoftware.com

sethoflagos (Chemical) 19May

0612:06

bmp28,

The DEP reference is 31.11.05.11-Gen which gives rho-v2 limits identical to those you quote (december 1996 revision).

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1/6/14 Chemical plant design & operations - Separator Vessel Nozzle Velocity and Momentum

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It's very conservative.

roker (Chemical) 20May

062:44

hello bmp28,

beside the rov^2 a very useful design is a tangential inlet.

regards,roker

skyporker (Chemical) 29Jun06

7:21

So is separation efficiency reduced if momentum is above these guidelines? or are the concerns excessive pressure loss and erosion?

Regards,

skyP

25362 (Chemical) 29Jun06

9:12

Please note that kg/(ms2) = N/m2 = Pa, a pressure unit.

Wear by erosion depends on the impacting particle velocity and the angle of impingement. At a 20o angle erosion may already be considerable.

For liquid droplets impinging on a solid surface at 90o the pressure on impact is:

p = ρ × vs × v

where:

p = pressure on impact [Pa];

ρ = liquid density [kg/m3];vs = sound velocity in liquid [m/s];

v = liquid droplet velocity [m/s].

As an example, for water droplets travelling at 100 m/s,

p = 1000×1500×100 = 150 [MPa] !

Wear by impact can form holes or pits, and may even cause fracture if the material is brittle. This is a subject covered -among others- in tribologyengineering books.

The following threads and the links therein may show to be helpful with regard to corrosive-erosive wear of piping:

thread794-57906thread378-66050thread378-64478thread378-30500thread338-23463thread124-70976

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1/6/14 Chemical plant design & operations - Separator Vessel Nozzle Velocity and Momentum

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