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Salt content in desalted crude oil should be less than one PTB. However due to some reasons the salt content of desalted crude oil is higher than a PTB , what can be the effects , or the changes it can create in the downstream process?
 
Answers
02/12/2015 A: Daniel Vargas, Saudi Aramco, vargasdj@aramco.com
Additional to corrosion problems in crude unit top section, regarding other downstream units, please be careful about sodium content in VGO, which deactivates downstream catalyst systems (HDT, HCK, FCC), also sodium in VR should be below 15-20 wppm in order to avoid fouling/coking problems in coker or visbreaker furnaces.
The previous is a typical constraint when caustic soda is used downstream desalters to decrease/prevent corrosion in atmospheric column top section.
24/03/2015 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Perfecting the desalting operations is the back bone of all corrosion reduction programs of the Refinery. Desalters remove salts to reduce corrosion severity and dehydrate the crude to reduce fouling of exchangers / coking of furnaces and allow longer runs of Crude distillation Units.
20/03/2015 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Salts in the desalted crude can also contribute to fouling in the heat exchangers and furnaces downstream. If the refinery is making anode coke, then high sodium levels will hurt coke quality as well. Inadequate desalter performance can also be associated with other problems like oil under carry to the waster system, which results in excessive slop production.
20/03/2015 A: Krishna Rao Pulugurti, Retired/Consultant, pkrao2012@yahoo.com
It may create corrosion in the column and overhead
20/03/2015 A: Mahesh Kasture, BPCL, maheshwkasture@bharatpetroleum.in
Salts in crude oil are the main reason of overhead corrosion in distillation column. Common salts in crude oil are NaCl, MgCl2, CaCl2. The hydrolysis of MgCl2 starts about 120C and hydrolysis of CaCl2 starts about 210C. Because of hydrolysis HCl forms which causes overhead corrosion. If the Ca content is very high in crude oil and desalted crude is also having high amount of Ca (more than 10 ppm), this Ca will affect the FCC process because Ca acts as a catalyst poison.
19/03/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Most of the salts encountered today can cause corrosion in the piping and equipment. Inhibitors, caustic, and water washing are being used for abatement. The higher the salt content out of the desalter, the more extensive can be the corrosion. Certain chlorides, sometimes called “organic chlorides”, cannot be removed in the desalter. Your desalter licensor can help you analyze the performance of the desalter and make recommendations for improvement.