4 replies to this topic

[Vivienne]

Anyone processing SOKOL Crude oil blend? Just in case you are, appreciate if you can share operational issues and concerns experienced in processing Sokol crude. In our case, we have experienced high overhead sourwater pH. We would want to know the cause of this limitation. We limit mixing to our crude mix to about 40%. Appreciate to know your experience in Sokol processing.

[Zauberberg]

Vivienne,

How many stages of desalting you have in the plant, and what sort of chemicals is injected upstream/downstream of the desalter? It's difficult to provide answers to your query without knowing any particular details. At least, a process flow diagram would be required.

I remember similar experiences when processing slop oil in refinery Crude Unit, and the problem - as identified - was the insufficient treatment/dewatering of slop oil in the Tank farm. Slop oil was contaminated with various sorts of chemicals, which was to be expected as the slop oil originates from basically all units within refinery.

With high pH in the column overheads you should definitely stop injecting the neutralizer chemical (amine), but even more important is to track the problem upstream of the column and see if it can be eliminated by proper treatment of crude oil stream, or by adjusting chemical injection (if any), or by reviewing process parameters (e.g. desalter interface level). Complete chemical analysis of water sample from the overhead receiver could give you more information about what is causing the contamination problem.

[ankur2061]

Zuaberberg,

I think what Vivienne meant was "SOKOL" and not "Slop Oil". It is a crude type from the Siberian oil fields similar to "Arabian Light" from Saudi Arabia or "Minas"
light crude from Indonesia.

Regards,
Ankur.

[Zauberberg]

Ankur,

Thank you for your comment. Yes, I was aware of the subject raised in Vivienne's question. The thing is that - based on my experience - crude oils normally do not show such behavior (high pH in the overheads) when processed in a distillation column. Presence of strong bases in light petroleum cuts does not occur naturally in crude oils and, unless we are missing some key input data, almost in 100% cases this is caused by contamination of crude - usually by the chemicals used in drilling, exploration, and crude oil transport.

I have seen crude oils contaminated with organic chlorides, resulting in instantaneous hydrolysis downstream of desalter and extremely low pH in the CDU column overheads. On the other hand, I have encountered high PH only when processing slop oil which was contaminated by numerous organic and inorganic species, that were not properly removed from the slop oil before re-processing.

[smalawi]

Hi

there are many factors that affect desalting and CL slip into the column overhead. organic CL cant be desalted so has to be controlled.

but in this case, its really the crude itself. these are transferred by long lines and as such carry lots of metals. desalters cant work effectively with this combination and shorts out, thus the high CL in overhead

cheers,

SM