Oil extracted from wells usually contains a certain amount of water. Therefore, the so-called oil "slimming" is actually oil "dehydration". The "slimming" of petroleum is divided into three steps-desalination and dehydration, atmospheric distillation and vacuum distillation. Every step is related to the effect of oil "slimming".

Step 1: Desalination and dehydration

Oil is mixed with water, salt, sediment and other substances. These substances will produce corrosive acids. These acids will accelerate the corrosion of equipment, containers and pipelines. Therefore, in the first step of "losing weight", the refinery staff will add demulsifier to the oil (we can imagine it as "the master of oil-water separation"); At the same time, under the conditions of high voltage electric field and high temperature, the purpose of oil-water separation is finally achieved. Because most of the salt is dissolved in water, it is removed at the same time of dehydration.

Step 2: "Sauna"

Atmospheric distillation is a bit like the "sauna" of oil-desalted and dehydrated oil is "heated" at room temperature and then cooled. According to the boiling point of substances contained in oil, oil is further separated from other liquid mixtures. After atmospheric distillation, light oil such as gasoline, diesel oil and kerosene and some heavy oil as raw materials of petrochemical products were born.

Step 3: Turn waste into treasure.

The step of vacuum distillation is very interesting, which can "turn waste into treasure"-under vacuum condition, heavy oil and part of residual oil are processed twice and converted into light oil. Through vacuum distillation, raw materials for manufacturing lubricating oil can also be obtained. In addition, in order to improve the octane number of gasoline, catalytic reforming of fractionated light oil should be carried out. At this point, the preliminary processing of oil has been completed.