The CDU consists of several key sections, each playing a vital role in the crude oil separation process:

1. Preheat Train

✔ Crude oil is preheated using heat exchangers that recover heat from hot product streams.
✔ This improves energy efficiency and reduces the fuel required in the furnace.

2. Desalter

✔ Removes water, salts (NaCl, MgCl₂, CaCl₂), and sediments from crude oil.
✔ Prevents corrosion & fouling in downstream equipment.
✔ Uses electrostatic separation to extract salt and water.

3. Crude Furnace (Heater)

✔ Heats crude oil to 340-370°C before entering the distillation column.
✔ Ensures efficient vaporization of light and medium hydrocarbons.

4. Atmospheric Distillation Column

✔ Separates hydrocarbons based on boiling points into different fractions.
✔ Has trays & packing to improve vapor-liquid contact for better separation.

5. Pump-Around & Side Strippers

✔ Pump-arounds control heat balance in the column.
✔ Side strippers remove light hydrocarbons from heavier fractions.

6. Overhead Condenser & Reflux Drum

✔ Condenses light hydrocarbons and returns reflux to the column to improve separation efficiency.