Oil refining

Newly-extracted crude oil is hardly ever used directly: it is more useful after it has been transformed in refineries to obtain different types of fuel: petrol for cars, kerosene for aviation, diesel for heating, propane, etc.

Structure of a refinery

First of all, the oil is analysed in the laboratory, because not all crudes are the same, and the same substances cannot be extracted from all of them. It is then sent on to the main process, DISTILLATION.

The crude oil is heated to 360ºC and pumped into distillation columns up to 50 metres high. Here the oil is divided up into its different component fractions and residual material on the basis of their different boiling temperatures.

1. Distillation column
   • Light fractions 22%
     Gases (2%)
     Petrols and naphtha (20%)
   • Medium fractions 65%
     Kerosene and solvents (25%)
     Diesel (40%)
   • Heavy fractions 13%Lubricants (3%)
     Residues (10%)
    
2. Burner for heating the crude oil to 360ºC
3. Distillation process in which the salt is extracted from the crude oil
4. Tank where the oil is stored

Distilling process

The separated fractions are extracted through different outlet devices and then cooled. They then undergo additional enhancement processes to produce the different commercial products.

• 

  GAS 60º

  Gases do not require any special treatment and are stored in tanks.

  Methane and ethane are used in the refinery itself as fuel, while butane and propane are distributed to end consumers to be used as domestic and industrial fuel.

   

• NAPHTHA 60º-120º

  The principal and most valuable product of the refining process is obtained from naphtas: PETROL.

  The petrol undergoes a chemical process to increase its octane rating and the necessary additives are added to obtain commercial petrol.

   

• KEROSENE 150º-250º

  Kerosene is used mainly as aviation fuel.

   

• DIESEL 170º-370º

  In chemical terms, the diesel used for heating and for fuel for vehicles is identical. Diesel is used as fuel in engines for al types of transport: buses, trucks, trains, ships, etc.

  Using an additional process called "Catalytic Cracking" more valuable light products such as PETROL can be obtained from diesel and heavier fractions.

• RESIDUE 370º

  Residual products of less value, such as fuel oil, are used as industrial fuel and in some conventional thermal power stations to generate electricity. Nowadays, they are increasingly being replaced by other much less pollutant fuels, such as natural gas, for example.

  • Wax
  • Lubricants
  • Asphalt