In Crude Distillation Unit CDU, we inject caustic soda (NaOH) for treating salts in crude oil (<= 20ppm ), but if the concentration of the salt in crude became too high (e.g 40ppm), desalter (desalting system) is required for that. The query is, if the desalter is out of service, what procedures are to be taken for treating salts? And what are the disadvantages of increasing the injection of caustic soda (NaOH)?May-2022
Rigoberto Santaella Rigores, LIpesa, firstname.lastname@example.org
Whenever caustic soda is used to reduce corrosion at the top of the crude distillation column, there is a risk of fouling the cold train, the hot train and the furnace due to the excess of unreacted caustic soda that could stay.
If you have the desalter out of service, you could manage the contingency by increasing the consumption of neutralizing amine and filmic amine on top and thus you can balance the increase in the injection of caustic soda with the top amines.
Suru Patel, Patex Controls Ltd, email@example.com
At a Steam Cracker plant, the field plant Operator would measure the spent caustic strength using an At Line analyzer to control the amont of fresh Caustic added to the process. The chemistry is quite complex!