7 replies to this topic

[ajayd]

Dear All,

Can anybody tell me the formulae to calculate Length & Diameter of Three Phase Separator.?

Thankx,

[Shubhasis]

Dear All,

Can anybody tell me the formulae to calculate Length & Diameter of Three Phase Separator.?

Thankx,

Hi,

For sizing of three phase separator first you have to calculate maximum allowable vapour velocity from you can get the allowable vapour space area of the vessle. Now you have to assume some value of drum diameter on the basis of past project reference or opeartional/engineering knowledge. Then you have to strat iteration for calculation of Tan-Tan length by considering different levels of liquids on the basis of project philosophies and design guidelines and calculate hold-up liquid volume. now using the basic correlation you can get the height. In this case you have to calculate the curve area. Last calculate the boot dia and length (easiest one)
Actually Three phase separator design is very critical and could not be described and explained in a few lines unless you start working on it. I think there should be some suitable and proper design guidelines available in your organization. Just read it off and first do a sample calculation. In this way you would be start accumulating knowledge. Take the help of your seniors (This will be more effective and desirable than sending a mail query to a forum like this) and apply your basic engineering knowledge.

Many thanks,
Shubhasis.

[Technocrat]

Dear Ajay,

Please give us complete process data to think of some practical design.

If your question is of general nature please read Shell DEP* no. 31.22.05.11-Gen. December 2007 version or the latest one.

*DEP: Design Engg. Practice.

Regards.

[roghi]

Dear All,

Can anybody tell me the formulae to calculate Length & Diameter of Three Phase Separator.?

Thankx,

Dear sir;
It does not have a rough formula. A little rules exist in the manuals of different companies like Shell. Get help of them.

[Zauberberg]

Here is some starting information for you: http://www.mop.ir/st...pr/e-pr-880.pdf

[Lenard Lutino]

Dear Ajay,

Please give us complete process data to think of some practical design.

If your question is of general nature please read Shell DEP* no. 31.22.05.11-Gen. December 2007 version or the latest one.

*DEP: Design Engg. Practice.

Regards.

Since the question is about 3-phase separation (G-L-L), the appropriate DEP is 31.22.05.12. The DEP 31.22.05.11 you mentioned is for G-L separation.

[Lenard Lutino]

Ajay,

Three-phase separator can be horizontal or vertical. If your vapor feed rate is large compared to the total liquid flow, vertical separator is recommended. Otherwise choose horizontal.

With regards to diameter and length:
Diameter of vessel should satisfy gas handling, de-gassing and de-foaming criteria. Most of the time the gas handling criteria governs. It is based on the principle of vapor disengagement. If you will add mist extractor in the vessel the diameter can be significantly reduced compared to separator without demisting internals.
Total length or height determination doesnt follow a single formula. It depends on the type of separator you have. A horizontal separator for example can have different configurations (single weir, weir and gutter, double weir, with boot)the selection of which depends on the fluid characteristics that you are handling. In each config there are industry standards that should be followed (i.e. inlet length, settling compartment length, collection compartment length).

I should say that I cant just post here formulae and you will be able to get the diameter and length. You need to read more on the principles behind.
Suggested references are the following:
GPSA Engineering Data Book Vol.1 Section 7
Shell DEP 31.22.05.12-Gen. (This is not for public use but if you have a friend from Shell maybe he can discuss with you how they do it, but dont expect to get a copy of this doc, it has copyright!)