Desalter Design Specification

Client has specified salt content of < 10 PPM in crude oil at the outlet of desalter package ,which seems to be very stringent. Two stage desalter is being proposed. It is difficult to meet this spec even with the electrostatic coalescer (1st stage) & conventional desalter (2nd stage). As per my experience, and considering corrosion of downstream stabiler column, minimum spec of 50 PPM is acceptable. Did somebody experience this much lower level (< 10 ppm) of salt content, keeping corrosion of downstream stabilizer in mind.

I intend to replace the 1st stage electrostatic coalescer ( very expensive) by conventional separator ( calming baffle+plate pack +weir) with demuslifier injection & fresh water makeup and reduce the cost, this is subject to get relaxation in product spec.

Please share your experience and advice.


Is the application in an oil/gas field, or in a refinery?
In my refinery experience the outlet salt specification is expressed in PTB instead of PPM (PTB stays for Pounds per Thousand Barrels).
The typical specification requested, when Catalytic Units are foreseen in the refinery scheme for the Heavy Ends, is 1 PTB.
It is achievable with a 2-stage desalter scheme.

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