Systems and methods for monitoring and controlling desalting in a crude distillation unit

A system for monitoring or controlling desalting in a crude oil unit, comprising:

• a mix valve for mixing crude oil and wash water by a pressure drop across the mix valve, thereby forming a crude oil/water phase stream;
• a desalter vessel for receiving the crude oil/water phase stream, whereupon an emulsion forms at an interface between the crude oil and the water phase, the desalter vessel configured to contact the crude oil with a dosage of an emulsion breaker in an applied electric field;
• an emulsion level indicator coupled to an outer surface of the desalter vessel, the emulsion level indicator capable of measuring at least one property associated with the emulsion;
• a chlorine analyzer capable of measuring a total chlorine of the crude oil;
• a water analyzer capable of measuring a water percentage of the crude oil;
• and
• a controller operatively coupled to the mix valve, emulsion level indicator, and either the chlorine analyzer, the water analyzer, or the chlorine analyzer and the water analyzer, wherein the controller adjusts substantially in real time at least one of the pressure drop and the dosage of the emulsion breaker in response to at least one of the measured properties, total chlorine, and water percentage.