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# 3-Phase Horizontal Separator Calculation

8 replies to this topic
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### #1 YJ Choong

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Posted 11 October 2018 - 11:28 PM

For a 3-phase horizontal separator, the vertical terminal velocity is calculated using liquid and vapor density. For the liquid density, it is referring to the light liquid density or the heavy liquid density or a combination of both?

Thanks

### #2 Bobby Strain

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Posted 12 October 2018 - 08:37 AM

The same forces act for liquid-liquid separation as for vapor-liquid separation.

edit:

Sorry, I didn't answer your question properly. But, neither did Shan. You should always look for answers from an authoritative source. If you don't know the answer to your query, you are probably ill equipped to size a separator that might perform properly. So, do a bit of research. Don't just poke numbers in some spreadsheet you found.

Bobby

Edited by Bobby Strain, 12 October 2018 - 10:33 PM.

### #3 shan

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Posted 12 October 2018 - 09:19 AM

Density Definition: Density = Mass/Volume

Therefore, in your case: Liquid Density = (Light Liquid Mass + Heavy Liquid Mass) / (Light Liquid Volume + Heavy Liquid Volume)

### #4 breizh

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Posted 13 October 2018 - 08:31 AM

Hi ,

Consider the document attached , you should find pointers .

Good luck

Breizh

### #5 Technical Bard

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Posted 02 November 2018 - 09:00 AM

You should use the light liquid properties for the disengagement from gas, as it has a lower density and therefore will fall a little bit slower through the gas (more buoyant).

In most 3-phase separators, the governing scenario is almost always the liquid-liquid separation of droplets from the continuous phase with the highest viscosity.

### #6 yasser kassem

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Posted 05 February 2019 - 01:12 AM

In a simple way

We want to separate two phases
1- dispersed phase (droplets)
2- Continuous phase (medium surrounding the droplet and resist the droplet settling) "Where viscosity is an important factor"

If we separate liquid from gas phase, the continuous phase is gas
If we separate water liquid from oil phase, the continuous phase is oil
If we separate oil from water phase, the continuous phase is water

Surface production facility book uses  dl or dg , do, dw  stands for density difference in equations
The same in GPSA
Fundamentals of oil and gas processing book uses (d2 for droplet, and d1 for continuous phase)

### #7 taif1999

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Posted 19 May 2024 - 05:19 PM

i am new to this community. i signed for this post

### #8 breizh

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Posted 19 May 2024 - 10:04 PM

hi,

Welcome to the community.

Breizh

### #9 shah1411

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Posted 21 May 2024 - 02:08 AM

why it is difficult to separate water from oil ( 1-2%) compared to oil in water (approx. 0.2%)