CC BY
24ТЕХНИЧЕСКИЕ НАУКИ (TECHNICAL SCIENCE)
УДК 665.71
Nasrutdinova M.D.
Student, Kazan National Research Technological University
(Russia, Kazan)
Khadeev R.I.
Student, Kazan National Research Technological University
(Russia, Kazan)
ATMOSPHERE-VACUUM DISTILLATION OF OIL
Abstract: The role of atmospheric-vacuum distillation in the course of oil refining is studied, various types of technological schemes of this process and possible products are given.
Key words: atmospheric-vacuum distillation, oil, rectification, column.
Installations of atmospheric-vacuum distillation of oil are the main objects that produce raw materials for recycling plants.
During the process of atmospheric vacuum distillation of oil, the following fractions are obtained:
- gasoline fractions (NK - 180 ° С);
- fractions of jet fuel (120 - 240 ° С);
- fractions of diesel fuel (240 - 350 ° С).
Gasoline fractions are accelerated to narrow fractions:
- N.K. - 85 ° С - are used as a component for motor gasolines;
- 85 - 180 ° С - is a raw material for the production of high-octane components of commercial gasoline;
- narrow fractions 62 - 85, 85 - 120, 120 - 140 ° С are used to obtain individual aromatic hydrocarbons in the process of catalytic reforming.
The fractions with a boiling point of up to 350 ° C are distilled off at atmospheric pressure. The residue after atmospheric distillation - the oil is subjected to vacuum distillation. The residue of vacuum distillation - tar (fraction with a boiling point of more than 500 ° C) is used as a raw material for thermal cracking, visbreaking, coking, and bitumen production. It may be a component of the boiler fuel. It is also possible to obtain narrow oil fractions (350-400, 400-450, 450-500 ° C) from vacuum distillation, from which distillate oils are subsequently produced. In addition to these products, the AVT unit produces dry and oily gases, liquefied gas, and light vacuum gas oil.
Rectification is intended to separate inhomogeneous liquid mixtures into fractions that differ in boiling point. The meaning of oil rectification is the two-way heat and mass transfer between the vapor and liquid streams with high turbulization of the contacting phases. As a result of mass transfer, the evaporating vapors are enriched with low-boiling components, and the liquid with high-boiling components.
Rectification occurs in the counter flow of liquid and vapor. During vapor rectification, liquid irrigation is condensation of a portion of the vapor from the top of the column, and steam irrigation during liquid rectification occurs due to evaporation of part of this liquid phase at the bottom of the column. The main apparatus of the primary processing process is a distillation column, which is a cylindrical vertical apparatus. Inside each other there are plates.
On the surface of these plates is the contact of the liquid and vapor phases. The lightest components of the liquid reflux evaporate and, together with the vapors, enter the upper part of the column, and the heavier components of the vapor phase condense and flow to the lower part. Thus, evaporation and condensation processes occur constantly in distillation columns. [1]
According to the method of carrying out the process, simple and complex distillation is distinguished. Simple distillation consists of gradual, single or multiple evaporation.
Distillation with gradual evaporation consists in gradually heating the oil from the initial temperature to the final one with a constant drain and condensation of the resulting vapors.
Single distillation consists in heating to a predetermined temperature, upon reaching
which equilibrium vapors are formed, which are separated from the liquid phase - the
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residue. This method gives a large proportion of the distillate at the same temperature and pressure as gradual evaporation at the same temperature and pressure.
Distillation with repeated evaporation consists in repeating the method of single distillation only at higher temperatures or lower pressures with respect to the remainder of the previous process.
Complicated distillation is divided into distillation with reflux and with distillation.
During distillation with reflux, the vapors are condensed and part of them is sent to irrigate the vapors in the upper part of the column. As a result, couples leaving the system are further enriched with low-boiling components, thereby increasing the clarity of separation of mixtures.
The main factor in choosing the technological scheme and distillation mode is the fractional composition.
When choosing a technological scheme, it is necessary to choose such values of pressure and temperature as:
- exclude the possibility of decomposition of raw materials and products of distillation or the occurrence of deposits in pipelines;
- do not require expensive refrigerants for vapor condensation (water, air) and heat carriers for heating and evaporating a liquid (for example, high-pressure water vapor);
- ensure the normal operation of the apparatus and processes associated with the rectification column with material and heat fluxes;
- provide good performance, do not require large capital and operating costs. [2]
BIBLIOGRAPHY
Gurevich I.L. Oil and gas processing technology. - M: Chemistry, 1979. Aleksandrov, I.A. Distillation and rectification in oil refining. - M: Chemistry, 1981.
