As an atmospheric and vacuum distillation device, in addition to the total extraction of the device and the yield of light oil, there are several parameters that are mainly concerned: the salt content after electric desalination, the outlet temperature of the atmospheric and vacuum furnace, the outlet temperature of the vacuum furnace, and the residual oil 500°C distillate.

The salt content of crude oil after electrical desalination will affect the operation of subsequent atmospheric towers and vacuum towers. Generally speaking, the salt content after electrical desalination is not more than 3.0mg/L. The high salt content of crude oil is mainly due to the continuous use of new technologies in oil fields, such as alkali flooding, steam flooding and chemical driving oil, to increase crude oil production, resulting in a continuous increase in the salt content of crude oil.

If the inorganic salts (mainly oilfield additives) in crude oil enter the atmospheric and vacuum towers, they will be easily hydrolyzed to form HCl in a high temperature environment. After HCl condenses with water, a highly corrosive hydrochloric acid solution will be formed, resulting in normal and Corrosion of the vacuum tower overhead system, therefore, it is more important to control the salt content of the crude oil after removal and strengthen the "one removal and three injections" of the atmospheric and vacuum distillation unit.

Generally speaking, the most concern of atmospheric and vacuum distillation units is the distillate of residual oil at 500°C. How to control the distillate of atmospheric and vacuum distillation units at 500°C? Here we will talk about decompression. The cutting point temperature of vacuum residue in domestic atmospheric and vacuum distillation units is 535-540°C, and the cutting point temperature of vacuum residue in the newly designed large-scale atmospheric and vacuum distillation unit is 565°C, and some units even reach 580°C. Generally speaking, deep drawing under reduced pressure means that the cutting point temperature of the vacuum residue is above 565°C.

As far as crude oil processed by atmospheric and vacuum distillation is concerned, paraffin-based crude oil with low sulfur and low metal content does not need vacuum deep drawing; crude oil with high sulfur and high metal content requires vacuum deep drawing. The quality of decompression and deep drawing is related to the outlet temperature of the decompression furnace. To reduce the pressure and deep drawing, the outlet temperature of the decompression furnace must be increased.

When the atmospheric and vacuum distillation unit is deep-drawing under reduced pressure, the outlet temperature of the vacuum furnace is controlled at 410-430°C, which is about 30°C higher than the general atmospheric and vacuum distillation unit. The residence time of the vacuum heating furnace is controlled within 40S, mainly to prevent the vacuum residue from staying too long and the vacuum residue from coking in the furnace tube. Although deep drawing under reduced pressure can improve the yield of wax oil, the yield of light oil and the extraction rate of the device, it will increase the energy consumption of the device.

The crude oil designed and processed by the atmospheric and vacuum distillation unit determines the API° range of crude oil that can be processed. Domestic coastal refineries and newly built large refining and chemical projects have designed API° of 28-33, which cannot process API° greater than If the U.S. crude oil above 33% is processed, the load of the atmospheric tower will be too high, which will cause the atmospheric tower to “pump the tower”, which will lead to disordered material distribution in the entire atmospheric and vacuum distillation unit, resulting in the shutdown of the unit. The general operation is to reduce the load of the device (to 50-70% of the normal load), and then process it after mixing with other heavy crude oil.

The atmospheric and vacuum distillation unit controls the content after electric desalination, mainly to prevent the subsequent atmospheric and vacuum tower top corrosion;

Controlling the distillate at 500°C of vacuum residue is mainly to reduce residue products;

The oil type of the atmospheric and vacuum distillation unit design determines the API° of the crude oil it processes.