What are the hazards of crude oil salinity on primary processing?

MgCl2 and CaCl2 in crude oil can hydrolyze to produce corrosive HCl. MgCl2 + 2H2O == Mg(OH)2 + 2HCl; CaCl2 + 2H2O == Ca(OH)2 + 2HCl. MgCl2 and CaCl2 generally begin to hydrolyze at 200°C, although some studies indicate that this process starts at 120°C when the concentration is high. The hydrolysis reaction can take place in an aqueous solution, or it can be carried out by its own crystalline water. Recent studies have shown that NaCl also undergoes hydrolysis at a temperature of 300°C. NaCl + H2O = NaOH + HCl. HCl, when dissolved in water, forms hydrochloric acid, which has a strong corrosive effect and causes corrosion of the top sections of the atmospheric distillation column, atmospheric tower, and vacuum tower in atmospheric and vacuum distillation units. When processing sulfur-containing crude oil, sulfur compounds decompose to release H2S, which reacts with metals to form FeS; this substance can adhere to the metal surface and provide protection. When HCI is present simultaneously, HCl reacts with FeS to destroy the protective layer, releasing H2S which further exacerbates corrosion. FeS + 2HCl = FeCl2 + H2S. Therefore, to prevent equipment corrosion, it is necessary to desalt crude oil. The salts in crude oil remain concentrated in the residue after atmospheric and vacuum distillation. Heavy oil catalytic cracking, which has been developed in recent years, is a processing technique with high economic efficiency. However, sodium damages the lattice of molecular sieve catalysts, and the catalytic cracking feed requires a sodium content of less than 1 ppm. Therefore, the NaCl content in the crude oil after desalination is required to be less than 2.5 ppm. As the crude oil passes through devices such as heat exchangers and tubular heaters, the increase in temperature causes water to evaporate; salts then deposit on the tube walls, forming scale that hinders heat transfer. During the operation of electrodialysis, a large amount of filterable solid substances accumulate at the bottom of the electrodialysis tank; these can be removed along with the water by using backwashing. It reduces scaling in the heating furnace tubes and heat exchange equipment of the unit, improves heat transfer efficiency, and extends the operational cycle.

Basically correct; the three areas are in a strongly acidic environment, where there is no hydrogen sulfide corrosion – corrosion is mainly caused by hydrochloric acid. Most impurities in crude oil are caused by its high density, which is at least 0.90 or higher. However, crude oil asphaltenes have a significant impact on electrodialysis