Steps in the production process of Lube oils.

The production process of lubricants comprises several steps. The main steps will be described below.

•        Atmospheric distillation:

In this first step the oil is heated to 400 ° C in a furnace. A mixture of gases and liquids is then produced, which passes to the fractionation tower or condenser. The gases condense in the column and are collected at different heights depending on the different boiling points. These are the raw materials for the manufacture of various types of fuels.

The liquid residue from the first distillation, which is in the bottom of the distillation column is the raw material for the manufacture of lubricant oils.

Figure 1. Atmospheric distillation.

• Vacuum distillation:

The liquid residue obtained is subjected to a second distillation, which takes place under reduced pressure (vacuum distillation) and separated into several fractions.

The more volatile fraction is used as fuel.

The residue is used for the production of heavy oils and asphalts.

The intermediate fractions are used for the production of base oils for the manufacture of lubricant oils. Up to four fractions of base oils can be produced.

Figure 2. Vacuumm distillation.

•  Deasphalting

The less volatile fraction of the base oils contains large amounts of asphaltenes. These compounds are removed by deasphalting. In this step t the oil is blended with propane, which is capable of solving most of the asphaltenes and these can be separated afterwards.

                                                                          Figure 3. Deasphalting process.

• Solvent extraction

In this operation the base oil is blended with solvents that have the ability to dissolve aromatics. Alkanes and cycloalkanes are not solved and can be separated subsequently. The product of this stage has a higher viscosity index and is more stable to oxidation than the previous base oil.

Figure 4. Solvent extraction.

•  Dewaxing

The next step is the dewaxing, where  the alkanes with high melting point are removed  and oil properties at low temperature are improved. The conventional technique involves blending the oil with a suitable solvent and then the mixture is cooled. The wax solidifies and it is separated by filtering the oil. Alternatively, the catalytic dewaxing can take place, in which the molecular structure of the alkanes is altered by treatment with hydrogen in the presence of a catalyst.

                                                                              Figure 5. Dewaxing process.

• Hydrogenation

Hydrogenation  is used for oils where the aromatic and asphaltene content must be further reduced. In this process the oil is treated under pressure with hydrogen in the presence of a catalyst.

Finally the refined base oil is ready to be blended with other base oils and reinforced with additives for the production of different types of lubricating oils.

Author: Silvia Fernández Castejón. Chemical Engineer. Complutense University of Madrid.

Bibliography:

Introducción a los lubricantes y la lubricación. Tutorial de lubricación Shell.

https://es.scribd.com/doc/18198822/10/LA-FABRICACION-DE-ACEITES-LUBRICANTES