5 replies to this topic

[ahyong]

Hi all,

Lately I've been dealing a lot with vessel sizing by using SHELL DEP as the reference standard. I found out that Shell DEP does not provide a very specific explanation regarding some of the terms. Please see below.

Before start sizing, we have to choose whether the vessel is "gas handling", "liquid de-gassing" or "defoaming"

 

1)Gas Handling Capacity: Shell DEP only mentioned that this is for vessel when the liquid carry over is limited. So my understanding is that KO Drum at the suction of compressor, Flare KO drum are falling under this criterion. Is it correct? Is there any other better example for vessel that fall under "gas handling capacity" Any specific explanation on how to decide whether the vessel is "gas handling capacity"?

 

2)Liquid de-gassing: Shell DEP only mentioned that this is for vessel where the vapor under flow is not allowed. So my understanding is that vessel like stripper in SRU (to remove H2S), desalter....fall under this criterion. Am I right? How are we suppose to decide that the vessels fall under "liquid de-gassing"?

 

3)De-foaming: Shell DEP does not provide very useful informationa regarding how to decide on vessel for de-foaming. As per my understanding vessel such as slug catcher shall be de-foaming due to the MDEA from vessel upstream. Besides this, is there any other better explanation regarding de-foaming?

 

Thank you very much

[ahyong]

Hi,

Anyone any ideas??

[ankur2061]

ahyong,

 

DEP typically uses these terms (liquid handling and gas handling) for 3-phase separators. 

 

A 3-phase separator is liquid handling controlled if:

a. the feed to the separator is mainly liquid and/or

b. a low superficial liquid velocity is required

 

If the separator is 'liquid handling' controlled, a horizontal vessel is selected

 

A separator that handles relatively a large gas flow rate then it is called 'gas handling' controlled and the choice should be of a vertical vessel. 

 

Some recommendations for orientation of 3-phase separators are provided in the attachment:

 

 

Regards,

Ankur

Attached Files

•  Separators.jpg   19.63KB   10 downloads

Edited by ankur2061, 23 February 2014 - 01:38 AM.

[ahyong]

Ankur,

Thanks for the reply. So is it correct if I say vessel like Flare KO Drum , Fuel Gas KO Drum is "gas handling capacity", 3phase oil-water separator is "liquid de-gassing"?

 

Besides that, is it possible to decide whether the contents in a vessel falls under foaming tendency or not just by looking at the process data on the vessel data sheet? I am not sure, but I think it is impossible to tell whether a product has foaming tendency just by looking at the process data on vessel data sheet right? There are so many factors which affect the foaming tendency such as temperature, viscosity, chemical contents such as resin, inlet device, GOR and many more......

 

So is it ok, if I do the vessel data sheet verification by just referring to the 2 options a) gas handling capacity b)liquid de-gassing. Will there be any great consequence if I dont take foaming tendency into account?

 

Thank you

[ankur2061]

ahyong,

 

Foaming cannot be generalized. It is application specific. If you know that foaming is going to take place you choose a horizontal separator with lower downward liquid velocity. 

 

If foaming phenomena is know then it is wise to cover it as a note in the separator datasheet. Also, provision should be provided for anti-foam chemical injection upstream of the separator.

 

Regards,

Ankur.

[ahyong]

Ankur,

Thanks a lot!