3 phase separator 1

[Darsh73]

First of all, I would like to express my deep appreciation to your website, its really helpful and interesting

Currently, i'm in the phase of plant upgrading, so we are looking for a 3 phase separator (Gas/Oil/Water) as a first stage separator, to coop with a flow rate of 10,000 bopd with 30% W/C and 70 mmscfd GAS. Feed Inlet Temperature is 25 C and 20 Bar as an inlet pressure.

So, if you can advice me in a rough or brief form about the size and estimated cost of such separator.

Your time and efforts are much appreciated,

 

[Monagas]

Well, Mr Engineer,

Have you ever heard about the GPSA databook, or Campbell?

Take a look at those books

I think it is your work. Do it

Regards from Venezuela

 

[Darsh73]

Thanx for your help, but currently i don't have an access for these refrences.

 

[Homayun]

Darsh73,

Usually you would size a separator based on two criterias:
Criteria1) sufficient low velocity in order to allow for liquid droplets to separate from the gas. Try to size a vessel with a diamtere giving you a velocity less than 1 m/s on the liquid surface.

Criteria 2): You need a hold up time in the vessel. Depending where the liquid goes to after the separation, the hold up time cam vary between 3 - 10 minutes.

As an example, try 3 minutes for each liquid phase, and use a length / Diamtere (L/D) ratio of 3.

These should give you enough hints to size the vessel roughly. You would certainly also need a weir in the vessel for a better seperation of the two liquids.

I have no idea of the costs.

 

[Montemayor]

Darsh73:

No serious oil producer or processor that I've ever known would think of designing their own 3-phase separator. It just doesn't equate to common economical sense when you've got to have assurance that you can deliver on what you contract to sell. All producers maintain a reliable, experienced and recognized designer and fabricator and pay them for the finished and warranted product.

Unless you've done this before many times (and successfully), why would you attempt it? There are persons in industry who specialize in this and dominate the field in producing a guaranteed separator cheaper than you can design and build it. I would, like all others I know, go to them for advice and supply.

 

[Darsh73]

Dear Montemayor,
This is exactly what we are doing, but i was just trying to have a rough design/feeling about the size and overall design stages that the consultant is going through it.

 

[Buchi]

Hi Darsh73,

you did not tell us whether your separator is two phase or three phase separator. It makes a whole lot of difference in the calculations algorithm.

The vertical separator pretty straight forward:

The calculation steps are

1. Determine the maximun superficial velocity (which uses the density of Gas and oil and the K constant)

2. Determine the cross sectional area of the vessel by diving the Vapor flow rate with the maximum superficial velocity.


3. With the formular for Area of a circle, determine the minimum diameter of the shell.

4. For the height of the vessel, use the resident time for the liquid and assume that the liquid will occupy a particular percentage of an assumed total height (usually 30 -70%)

5. ensure that this volume capacity is adequate to handle the liquid flowrate, if not assume another height and repeat the process.

Although, this is really a rough method, a more rigorious method will involve the control levels (LLL,LL,NLL,HLL,HHLL)

The horizontal vessel is a different ball game.

i hope this helps

Buchi