Crude distillation process

- Jan 19, 2017-

Pretreatment of oil

Electrochemical separation or settlement of heating method by the removal of water, salts and impurities. Main purpose of which is to prevent salts (sodium, calciumand magnesium chloride) dissociation produces hydrogen chloride and corrosionof equipment and salt fouling in tube-type furnace tube deposit.

By electrochemical separation, you want to add a few to dozens of ppm in the crude oil demulsifiers (ionic or non-ionic demulsifier polyether demulsifiers) and softens the water, and then through the high-voltage electric field (electric field 1.2~1.5kV/cm), bringing together salt water settlement, and thus remove the salt, water and other impurities in crude oil. Electrochemical desalination equipment series come in two groups (secondary desalination, Figure 1) to improve the effect of desalination.

Atmospheric distillation

After pretreatment of the crude oil is heated into the atmospheric distillation unit(Figure 2) distillation towers, most distilled light gasoline. Distillation of crude oil by the end of the heat to 360~370℃, enter the atmospheric distillation Tower (platenumber 36~48), the top of the tower for gasoline (also known as naphtha), with distillation Tower light catalytic reforming of gasoline can be used as a raw material,or as a petrochemical feedstock or as gasoline blending component. AtmosphericTower side discharging into the stripper, the use of steam or heated reboiler, evaporation light component to control the light components (flash point). Typically, lateral line for Jet fuel (kerosene) or kerosene fraction, second-line for light diesel oil fractions, side line for heavy diesel oil or oil fraction (of the lubricating oil distillates), bottom product residue (heavy oil).

Vacuum distillation

Also known as vacuum distillation. Heavy fractions the boiling point of about 370~535℃ in crude oil, at normal pressure distillation fractions, need to be heated to 420 degrees centigrade above this temperature, distillation branch of a certaindegree of cracking. Therefore, usually in atmospheric and vacuum distillation of atmospheric and vacuum distillation. In about 2~8kPa of absolute pressure, withoutobvious reaction temperature distillation of heavy components. Atmospheric residue after decompression heating furnace heating to about 380~400℃ into the vacuum distillation Tower. Atmospheric and vacuum distillation can be divided into oil(Figure 3) and two types of fuel oil. The former separation of fractions requires high precision, plate number 24~26; the latter demand is not high, plate number 15~17.

Usually with a steam jet pump (or using a mechanical vacuum pump) taking the Non-Condensable Gas, to produce the vacuum. Development of dry-packed vacuumTower (see filling) using efficient packing of metal instead of trays, you can make the full pressure drop reduced to 1.3~2.0kPa, so as to improve the rate of evaporation, and the reduction or elimination of bottom of the factors.

In order to make in the same furnace outlet temperature vaporization rate of atmospheric residues have the largest, vacuum distillation will exit to the pipeline designed to form a large diameter of the Tower (see picture), in order to reduce the pressure drop, and then reduce the exit of the pressure. Vacuum Tower separated fractions subtraction (pressure, extraction) and oil, commonly used as a diesel blended with atmospheric pressure in line, vacuum line to zigzag as a feedstock or lubricant materials, bottom for crude oil, can be used as a production residue oil (SDA) and petroleum asphalt materials, or as raw materials of petroleum coke, or used as a fuel oil.