Electrostatic Dehydrator - Water/Brine Reflux to a electrostatic treater???

[idavidqs]

Hi,
I began to work on a heavy oil dehydration project. The dehydration plant have a FWKO Tank and two dehydration/desalting trains. Each train have two electrostatic treaters (a two stages process). I'm doing a lot of researching because I know that the electrostatic process of the crude oil could be verey complex. But there is one thing that i can't understand.

In the process flow diagram, part of the stream that is separated from the second dehydrator (desalinator) is fed to the first electrostatic treater with the oil. This process water exiting of the second dehydrator is practically a brine. I am not confusing this with the wash water for the desalting process (second treater).
I know that a high salt content in the aqueous phase of a water in oil emulsion can promote oil dehydration because of the formation effect of dipoles in the drop. Now, It is that Ok at industrial scale? Why this salt water (brine) enters the first dehydrator? Does that promotes the separation?

Thanks.

 

[TD2K]

I suspect it's more to reduce water consumption. Do a desalter calculation assuming you use 'fresh' makeup water for each desalter and then do a second calculation with reycling the water from the second desalter to the first desalter.

The water from the second desalter may have a lot of salt in it but it's still pretty good water compared to the water you are trying to remove from the crude in the first desalter.