Fundamentals of Main Oil Refinery Processes

CRUDE OIL PRETREATMENT (DESALTING)

The figure provided here illustrates the block diagram of a desalting process. Notice the four sections in this block diagram:

a. Source and nature of feedstock

b. Type of process

c. Products created by the process

d. Usual destination for the products created.

Crude oil often contains water, inorganic salts, suspended solids, and water-soluble trace metals. As a first step in the refining process, to reduce corrosion, plugging, and fouling of equipment, and to prevent poisoning the catalysts in processing units, these contaminants must be removed by the desalting (dehydration) process.

The two most common methods of crude-oil desalting are chemical and electrostatic separation. Both of these processes use hot water as the extraction agent. In the chemical desalting process, water and chemical surfactant (de-emulsifiers) are added to the crude. After that the crude is heated so that salts and other impurities dissolve into the water or attach to the water. After that the mixture is held in a tank where the impurities settle out.