Oil refining. Oil refineries. Modern technologies for deepening oil refining Technology for the production of petroleum products

Oil is a complex substance consisting of mutually soluble organic substances (hydrocarbons). Moreover, each individual substance has its own molecular weight and boiling point.

Crude oil, in the form in which it is extracted, is useless to humans and only a small amount of gas can be extracted from it. To obtain other types of petroleum products, oil is repeatedly distilled through special devices.

During the first distillation, the substances contained in oil are separated into separate fractions, which further contributes to the emergence of gasoline, diesel fuel, and various engine oils.

Installations for primary oil refining

Primary oil processing begins with its arrival at the ELOU-AVT installation. This is far from the only and not the last installation necessary to obtain a high-quality product, but the efficiency of the remaining links in the technological chain depends on the work of this particular section. Installations for primary oil refining are the basis for the existence of all oil refining companies in the world.

It is under the conditions of primary distillation of oil that all components of motor fuel, lubricating oils, and raw materials for the secondary refining process and petrochemicals are released. The operation of this unit determines both the quantity and quality of fuel components, lubricating oils, and technical and economic indicators, knowledge of which is necessary for subsequent cleaning processes.

A standard ELOU-AVT installation consists of the following blocks:

• electric desalination unit (EDU);


• atmospheric;


• vacuum;


• stabilization;


• rectification (secondary distillation);


• alkalizing.

Each block is responsible for highlighting a specific faction.

Oil refining process

Freshly extracted oil is divided into fractions. For this, the difference in the boiling point of its individual components and special equipment - an installation - are used.

Crude oil is transported to the CDU unit, where salts and water are separated from it. The desalted product is heated and sent to an atmospheric distillation unit, in which the oil is partially topped, divided into lower and upper products.

The stripped oil from the bottom is redirected to the main atmospheric column, where kerosene, light diesel and heavy diesel fractions are separated.

If the vacuum unit does not work, then the fuel oil becomes part of the commodity base. When the vacuum unit is turned on, this product is heated, enters the vacuum column, and light vacuum gas oil, heavy vacuum gas oil, darkened product, and tar are separated from it.

The upper products of the gasoline fraction are mixed, freed from water and gases, and transferred to the stabilization chamber. The upper part of the substance is cooled, after which it evaporates as condensate or gas, and the lower part is sent for secondary distillation to be separated into narrower fractions.

Oil refining technology

In order to reduce oil refining costs associated with the loss of light components and wear of processing equipment, all oil is subjected to pre-treatment, the essence of which is the destruction of oil emulsions by mechanical, chemical or electrical means.

Each enterprise uses its own method of refining oil, but the general template remains the same for all organizations involved in this area.

The refining process is extremely labor-intensive and lengthy; this is due, first of all, to the catastrophic decrease in the amount of light (well-processed) oil on the planet.

Heavy oil is difficult to process, but new discoveries in this area are made every year, so the number of effective ways and methods of working with this product is increasing.

Chemical processing of oil and gas

The resulting fractions can be converted into each other, for this it is enough:

• use the cracking method - large hydrocarbons are broken down into small ones;


• unify fractions - perform the reverse process, combining small hydrocarbons into large ones;


• make hydrothermal changes - rearrange, replace, combine parts of hydrocarbons to obtain the desired result.

During the cracking process, large carbohydrates are broken down into small ones. This process is facilitated by catalysts and high temperature. A special catalyst is used to combine small hydrocarbons. Upon completion of the combination, hydrogen gas is released, also serving for commercial purposes.

To produce a different fraction or structure, the molecules in the remaining fractions are rearranged. This is done during alkylation - mixing propylene and butylene (low molecular weight compounds) with hydrofluoric acid (catalyst). The result is high-octane hydrocarbons used to increase the octane number in gasoline mixtures.

Primary oil refining technology

Primary oil refining helps to separate it into fractions, without affecting the chemical characteristics of individual components. The technology of this process is not aimed at radically changing the structural structure of substances at different levels, but at studying their chemical composition.

During the use of special instruments and installations, the following are separated from the oil supplied to production:

• gasoline fractions (boiling point is set individually, depending on the technological purpose - obtaining gasoline for cars, airplanes, and other types of equipment);


• kerosene fractions (kerosene is used as motor fuel and lighting systems);


• gas oil fractions (diesel fuel);


• tar;


• fuel oil

Separation into fractions is the first step in purifying oil from various types of impurities. To obtain a truly high-quality product, secondary purification and deep processing of all fractions are necessary.

Deep oil refining

Deep oil refining involves the inclusion of already distilled and chemically treated fractions into the refining process.

The purpose of the treatment is to remove impurities containing organic compounds, sulfur, nitrogen, oxygen, water, dissolved metals and inorganic salts. During processing, the fractions are diluted with sulfuric acid, which is removed from them using hydrogen sulfide scrubbers, or with hydrogen.

The processed and cooled fractions are mixed to produce various types of fuel. The quality of the final product - gasoline, diesel fuel, engine oils - depends on the depth of processing.

Technician, technologist for oil and gas processing

The oil refining industry has a significant impact on various areas of society. The profession of oil and gas processing technologist is considered one of the most prestigious and at the same time dangerous in the world.

Technologists are directly responsible for the process of purification, distillation and refining of oil. The technologist ensures that the quality of the product meets existing standards. It is the technologist who retains the right to choose the sequence of operations performed when working with the equipment; this specialist is responsible for setting it up and choosing the desired mode.

Technologists constantly:

• explore new methods;


• apply experimental processing technologies in practice;


• identify the causes of technical errors;


• looking for ways to prevent problems that have arisen.

To work as a technologist, you need not only knowledge in the oil industry, but also a mathematical mind, resourcefulness, accuracy and precision.

New technologies for primary and subsequent oil refining at the exhibition

The use of ELOU plants in many countries is considered an outdated method of oil refining.

The need to build special furnaces made of refractory bricks is becoming urgent. Inside each such furnace there are pipes several kilometers long. Oil moves through them at a speed of 2 meters per second at temperatures up to 325 degrees Celsius.

Condensation and cooling of steam is carried out by distillation columns. The final product enters a series of tanks. The process is continuous.

You can learn about modern methods of working with hydrocarbons at the exhibition "Neftegaz".

During the exhibition, participants pay special attention to product recycling and the use of methods such as:

• visbreaking;
• coking of heavy oil residues;
• reforming;
• isomerization;
• alkylation.

Oil refining technologies are improving every year. The latest achievements in the industry can be seen at the exhibition.

Primary oil refining involves a continuous production process. Production facilities included in the structure of oil refineries are in constant load mode, performing functional tasks. In order to carry out timely major repairs of process equipment, oil refineries are forced to stop production at least once every 3 years.

Preparation for the stage of primary oil refining

The equipment on which primary oil refining is carried out, coming into direct contact with the aggressive components of the processed product, is subject to corrosive wear. One of them is salts, which are saturated with crude oil mass. Salt components are highly soluble in water. The method for desalting petroleum feedstock is based on this principle.

From the storage tanks, the processed products enter a special container, where they are mixed with a consolidated filler. The resulting emulsion is fed to a special electric desalting unit (EDU), consisting of units of a cylindrical structure (electric dehydrators). In the inner part of each of them, electrode devices are fixed, which are exposed to high voltage (from 25 kV).

During the primary oil refining process, the emulsion passes through electric dehydrators, where, under the influence of current and high temperature (100-120C), it begins to collapse. Salt water, having a higher density in relation to oil, accumulates at the bottom of the apparatus and is pumped out by a pump. As a catalyst for the process of separating water from the oil mass, special demulsifiers are added to the solution.

Primary oil refining process

The oil mass, cleared of salts, is moved for further processing to atmospheric-vacuum devices, where primary oil processing - AVT - is performed. The name of the installation is due to the processing process (dividing into individual particles), which consists of heating and filtering oil through tubular-shaped furnace coils. For heating, the heat from the burning component and the released smoky gas substances is used. The atmospheric-vacuum device provides two types of processing.

1. Atmospheric processing method. This stage of primary oil refining is tasked with isolating light components that boil away at high temperatures (350 degrees). The resulting petroleum products are gasoline, kerosene and diesel fuel. The yield of the light fractional composition is determined to be about sixty percent of the total mass of petroleum feedstock. A by-product of atmospheric distillation is fuel oil.

The distillation of oil mass heated in furnaces takes place in a vertical cylindrical device - a rectification tube, the inner zone of which is equipped with contact mechanisms. Through the holes of the contact elements, steam rises to the upper sector, and the liquid composition is drained into the lower zone. To perform an operation such as primary oil refining, the required number of contact devices is up to sixty pieces, which depends on the size and configuration processes of the rectification column devices.

2. Vacuum distillation is intended for processing fuel oil at fuel and oil profile plants. The primary product of distillation is oil distillates, and the by-product is tar. A vacuum environment (40-60 mm Hg) allows the process temperature to be reduced to 360-380 C, above which thermal decomposition of hydrocarbons occurs. Due to this, the selection of vacuum gas oil, the end boiling point of which is above 520 C, increases.

The amount of oil for carrying out a process such as primary oil refining is determined according to data from stationary metering devices, or by measuring the level in where it is stored, and from where it is supplied through the pipeline system to all technological installations.

The oil refining process can be divided into 3 main technological processes:

1. Primary processing - Separation of petroleum feedstock into fractions of different boiling point ranges;

2. Recycling - Processing of primary processing fractions by chemical transformation of the hydrocarbons they contain and the production of components of commercial petroleum products;

3. Commercial production - Mixing components using various additives to obtain commercial products with specified quality indicators.

The product range of an oil refinery can include up to 40 items, including:

Motor fuel,

Raw materials for petrochemical production,

Lubricating, hydraulic and other oils,

Other n/products.

The range of non-products produced at specific refineries depends on the composition and properties of the supplied crude oil and the demand for non-products.

Faction characteristics:

Gases dissolved in oil in an amount of 1.9% by weight of oil, and obtained during the primary distillation of oil, consist mainly of propane and butane. These are the raw materials of gas fractionation plants and fuel (domestic liquefied gas).

Fractions nc -62 and 62-85 o C have a low octane number, so they are sent to an isomerization unit to increase the octane number.

The 85-120 o C fraction is the raw material of catalytic reforming for the production of benzene and toluene, components of high-octane gasoline.

Fractions 85-120 and 120-180 o C - raw materials for catalytic reforming for the production of high-octane gasoline components and jet fuel components.

The 180-230 o C fraction is a component of jet and diesel fuel.

Fractions 230-280 o C and 280-350 o C are fractions of summer and winter diesel fuel. The cetane number of the combined fraction is 240 - 350 o C = 55. The pour point is -12 o C. Dewaxing of the 230 - 350 o C fraction makes it possible to obtain winter diesel fuel.

Fraction 350-500 o C - vacuum gas oil - raw material for catalytic cracking and hydrocracking processes to produce high-octane gasoline.

The fraction that boils away at temperatures above 500 o C - tar - is used as a raw material for thermal cracking, viscosity breaking, coking, and bitumen production plants.

Oil refining is a continuous technological process, the stopping of which is provided only for scheduled preventive maintenance (PPR), approximately every 3 years.

One of the main objectives of refinery modernization carried out by companies is to increase the turnaround period, which, for example, at the Moscow Refinery is about 4.5 years.

The main technical unit of a refinery is a technological installation, the complex of equipment of which makes it possible to perform all operations of the main technological processes of refining.

Basic Operations

1. Supply and receipt of oil.

The main routes for delivering raw materials to refineries:

Main oil pipelines (MOP) are the main option for crude oil delivery in the Russian Federation,

By rail using tank cars,

Oil tankers for coastal refineries

Oil is supplied to the plant oil terminal (Fig. 1) (usually Shukhov type), which is connected by oil pipelines to all process units of the plant.

Accounting for oil received at the oil terminal is carried out using instruments or by measurements in oil tanks.

2. Primary processing

2.1. Preparation of oil for refining (electric desalting).

Desalting serves to reduce corrosion of process equipment from crude oil.

Crude oil coming from oil tanks is mixed with water to dissolve salts and sent to an ELOU - an electrical desalting plant.

2.2.3. Stabilization and secondary distillation of gasoline

The gasoline fraction obtained from the AVT unit cannot be used for the following reasons:

Contains gases, mainly propane and butane, in volumes exceeding quality requirements, which does not allow their use as components of motor gasoline or commercial straight-run gasoline,

Oil refining processes aimed at increasing the octane number of gasoline and the production of aromatic hydrocarbons use narrow gasoline fractions as raw materials.

Therefore, a technical process is used, as a result of which liquefied gases are distilled from the gasoline fraction, and it is distilled into 2-5 narrow fractions on the appropriate number of columns.

Products of primary oil refining, in fact, like products in other refining processes, are cooled:

In heat exchangers, which ensures savings in process fuel,

In water and air refrigerators.

Primary processing unit - usually combined ELOU -AVT - 6 with a processing capacity of up to 6 million tons/year of oil, consisting of:

An ELOU unit designed to prepare oil for processing by removing water and salts from it,

AT block, designed for distillation of light petroleum products into narrow fractions,

VT block, designed for distillation of fuel oil (>350 o C) into fractions

A stabilization unit designed to remove gaseous components from gasoline, including corrosive hydrogen sulfide and hydrocarbon gases,

A unit for secondary distillation of gasoline fractions, designed to separate gasoline into fractions.

In the standard installation configuration, crude oil is mixed with a demulsifier, heated in heat exchangers, desalted in 4 parallel flows in 2 stages of horizontal electric dehydrators, additionally heated in heat exchangers and sent to the topping column.

Heat is supplied to the bottom of this column by a hot stream circulating through the furnace.

Next, the partially stripped oil from the column, after heating in a furnace, is sent to the main column, where rectification is carried out to produce gasoline vapors in the upper part of the column, 3 side distillates from stripping columns and fuel oil in the lower part of the column.

Heat removal in the column is carried out by upper evaporative irrigation and 2 intermediate circulation irrigations.

The mixture of gasoline fractions from the columns is sent for stabilization to the column, where light head fractions (liquid head) are selected from above, and stable gasoline is taken from below.

Stable gasoline in columns is subjected to secondary distillation to obtain narrow fractions used as feedstock for catalytic reforming.

Heat is supplied to the bottom of the stabilizer and secondary distillation columns by circulating reflux heated in a furnace.

Photos of primary processing plants of various configurations

3. Oil recycling

Products of primary oil refining, as a rule, are not commercial products.

For example, the octane number of the gasoline fraction is about 65 points, the sulfur content in the diesel fraction can reach 1.0% or more, while the standard, depending on the brand, is 0.005% - 0.2%.

In addition, dark oil fractions can be subjected to further qualified processing.

Therefore, oil fractions are supplied to secondary process plants, which improve the quality of oil products and deepen oil refining.

Catalytic cracking () is the most important oil refining process, significantly affecting the efficiency of the refinery as a whole.

The essence of the process is the decomposition of hydrocarbons included in the raw material (vacuum gas oil) under the influence of temperature in the presence of a zeolite-containing aluminosilicate catalyst.

The target product of the CC installation is a high-octane component of gasoline with an octane number of 90 p or more, its yield is 50 - 65% depending on the raw materials used, the technology used and the mode.

The high octane number is due to the fact that isomerization also occurs during cat cracking.

During the process, gases are formed containing propylene and butylenes, used as raw materials for petrochemicals and the production of high-octane gasoline components, light gas oil - a component of diesel and heating fuels, and heavy gas oil - a raw material for the production of soot, or a component of fuel oils.

The capacity of modern installations is on average 1.5 - 2.5 million tons/year, but there is also 4.0 million tons/year.

The key section of the installation is the reactor-regenerator unit.

The unit includes a raw material heating furnace, a reactor in which cracking reactions directly occur, and a catalyst regenerator.

The purpose of the regenerator is to burn out the coke formed during cracking and deposited on the surface of the catalyst. The reactor, regenerator and raw material input unit are connected by pipelines (pneumatic transport lines) through which the catalyst circulates.

Catalytic cracking capacity at Russian refineries is currently insufficient, and by introducing new units, the problem with the predicted gasoline shortage is being solved.

Raw materials with a temperature of 500-520°C, mixed with a dusty catalyst, move upward through the elevator reactor for 2-4 seconds and undergo cracking.

The cracking products enter a separator located on top of the riser reactor, where chemical reactions are completed and the catalyst is separated, which is removed from the lower part of the separator and flows by gravity into the regenerator, in which coke is burned at a temperature of 700°C.

After this, the restored catalyst is returned to the raw material input unit.

The pressure in the reactor-regenerator unit is close to atmospheric.

The total height of the reactor-regenerator unit is 30 - 55 m, the diameters of the separator and regenerator are 8 and 11 m, respectively, for a plant with a capacity of 2.0 million tons/year.

Cracking products leave the top of the separator, are cooled and sent for rectification.

Cat cracking can be part of combined installations, including preliminary hydrotreating or light hydrocracking of raw materials, gas purification and fractionation.

On the right side is the reactor, to the left of it is the regenerator

Hydrocracking is a process aimed at producing high-quality kerosene and diesel distillates, as well as vacuum gas oil, by cracking feedstock hydrocarbons in the presence of hydrogen.

Simultaneously with cracking, products are purified from sulfur, olefins and aromatic compounds are saturated, which results in high performance and environmental characteristics of the resulting fuels.

The resulting gasoline fraction has a low octane number; its heavy part can serve as reforming raw material.

Hydrocracking is also used in the oil industry to produce high-quality base oils with performance characteristics similar to synthetic ones.

The range of hydrocracking raw materials is quite wide - straight-run vacuum gas oil, catalytic cracking and coking gas oils, oil block by-products, fuel oil, tar.
Hydrocracking units, as a rule, are built with a large unit processing capacity - 3-4 million tons/year.

Typically, the volumes of hydrogen produced at reforming units are not enough to support hydrocracking, so separate units are built at refineries to produce hydrogen by steam reforming of hydrocarbon gases.

The technological schemes are fundamentally similar to hydrotreating units - raw materials mixed with hydrogen-containing gas (HCG) are heated in a furnace, enter a reactor with a catalyst bed, and the products from the reactor are separated from the gases and sent for rectification.

However, hydrocracking reactions proceed with the release of heat, so the technological scheme provides for the introduction of cold VSG into the reaction zone, the flow of which regulates the temperature. Hydrocracking is one of the most dangerous oil refining processes; when the temperature regime gets out of control, a sharp increase in temperature occurs, leading to an explosion of the reactor unit.

The hardware design and technological mode of hydrocracking units vary depending on the tasks determined by the technological scheme of a particular refinery and the raw materials used.

For example, to produce low-sulfur vacuum gas oil and a relatively small amount of light oil (light hydrocracking), the process is carried out at a pressure of up to 80 atm in one reactor at a temperature of about 350°C.

For maximum light output (up to 90%, including up to 20% of the gasoline fraction of the raw material), the process is carried out in 2 reactors.

In this case, the products after the 1st reactor enter the distillation column, where the light products obtained as a result of chemical reactions are distilled off, and the residue enters the 2nd reactor, where it is again subjected to hydrocracking.

In this case, when hydrocracking vacuum gas oil, the pressure is about 180 atm, and when hydrocracking fuel oil and tar - more than 300.

The process temperature, accordingly, varies in the range of 380 - 450°C and higher.

In Russia, hydrocracking technology was introduced in the 2000s at refineries in Perm, Yaroslavl and Ufa; at a number of plants, hydrotreating units were reconstructed for the light hydrocracking process.

The joint construction of hydrocracking and catalytic cracking units within the framework of deep oil refining complexes seems to be the most effective for the production of high-octane gasolines and high-quality middle distillates.

4. Commodity production

During the above technological processes, only components of motor, aviation and boiler fuels with various quality indicators are produced.

For example, the octane number of straight-run gasoline is about 65, reformate - 95-100, coking gasoline - 60.

Other quality indicators (for example, fractional composition, sulfur content) also differ between components.

To obtain marketable non-products, the resulting components are mixed in appropriate refinery tanks in ratios that provide standardized quality indicators.

The calculation of the mixing recipe () of components is carried out using modules of mathematical models used for production planning for the refinery as a whole.

The initial data for modeling are the forecast balances of raw materials, components and marketable products, the sales plan for non-products by product range, and the planned volume of oil supplies. In this way, it is possible to calculate the most effective ratios between components when mixing.

Often, factories use established mixing recipes, which are adjusted when the technological scheme changes.

The components of non-products in a given ratio are pumped into a mixing container, where additives can also be supplied.

The resulting commercial products undergo quality control and are pumped into tanks of the commodity raw material base, from where they are shipped to the consumer.

5. Delivery of petroleum products

Transportation by rail is the main method of delivering non-products in Russia. Loading racks are used for loading.

Through the main oil product pipelines () Transnefteprodukt,

River and sea vessels.

Today, the main natural source of hydrocarbons is oil. The first oil refineries were built precisely at production sites, but the technical modernization of transportation means caused the separation of oil refining from oil production. Oil refining centers are increasingly being built far from production sites, in regions of mass consumption of petroleum products or along oil pipelines.

Oil refining process

Oil refining occurs in three main stages:

• at the first stage, the crude oil is divided into fractions that differ in boiling point ranges (primary processing)
• further processing of the resulting fractions is carried out using chemical transformations of the hydrocarbons contained in them with the formation of components of commercial petroleum products (recycling)
• at the last stage, the components are mixed with the addition, if necessary, of various additives, with the formation of commercial petroleum products with specified quality indicators (commercial production).

Oil refineries produce motor and boiler fuels, liquefied gases, various types of raw materials for petrochemical plants, as well as lubricating, hydraulic and other oils, bitumen, petroleum cokes, and paraffins. Based on the oil refining technology used, refineries produce from 5 to 40 types of commercial petroleum products. Oil refining is a continuous process; the period of production between major overhauls in current conditions reaches about 3 years.

Primary oil refining

Primary refining processes do not involve chemical changes in oil and represent its physical separation into fractions. On the territory of Russia, the main volumes of processed crude oil are brought to refineries from production companies via main oil pipelines. Small volumes of oil are transported by rail. In oil importing countries that have access to the sea, supplies to port refineries are carried out by water.
Crude oil contains salts that cause rapid corrosion of process equipment. To remove salts, oil is mixed with water in which these salts dissolve. Next, the oil is supplied to the ELOU - an electric desalting apparatus. The desalting procedure is carried out in electric dehydrators. Under conditions of high voltage current (over 25 kV), the mixture of water and oil (emulsion) is destroyed, as a result of which water accumulates at the bottom of the apparatus and is discharged. All this happens at temperatures from 100 to 120°C. Oil from which salts have been removed is supplied from the ELOU to an atmospheric-vacuum distillation apparatus, which at Russian refineries is called AVT - atmospheric-vacuum tube. The AVT process is divided into two blocks - atmospheric and vacuum distillation.
The task of atmospheric distillation is to select light oil fractions - gasoline, kerosene and diesel, which boil to 360°C. The volume of their potential output reaches 45-60% for oil. The residue from atmospheric distillation is fuel oil. The oil heated in the furnace is divided into separate fractions in a distillation column, inside of which there are contact devices (plates). Through these plates, the vapors rise up and the liquid flows down. As a result of this process, the gasoline fraction is removed at the top of the column in the form of vapor, and the vapors of kerosene and diesel fractions are converted into condensate in other parts of the column and removed, while the fuel oil does not change its state and is pumped out in liquid form from the bottom of the column.
The task of vacuum distillation is to select oil distillates from fuel oil at fuel oil refineries, as well as a wide oil fraction (vacuum gas oil) at fuel refineries. At the end of vacuum distillation, tar remains. Oil fractions must be selected under vacuum because at a temperature of about 400°C hydrocarbons undergo thermal decomposition (cracking), and the end boiling point of vacuum gas oil is 520°C. For this reason, distillation is carried out under conditions of a residual pressure of 40-60 mm Hg. Art., as a result of which the maximum temperature in the apparatus decreases to 360-380°C.
The gasoline fraction obtained in an atmospheric block contains gases (mainly propane and butane) in a volume that exceeds quality requirements and cannot be used either as a component of motor gasoline or as commercial straight-run gasoline. In addition, oil refining aimed at increasing the octane number of gasoline and producing aromatic hydrocarbons involves the use of narrow gasoline fractions as raw materials. Therefore, it is necessary to include in the oil refining process the distillation of liquefied gases from the gasoline fraction. The products of primary oil refining must be cooled in heat exchangers, where they give off heat to the cold raw material supplied for processing, resulting in savings in process fuel. High-tech primary processing devices are most often combined and can carry out the above processes in different configurations. The capacity of such devices reaches from 3 to 6 million tons of crude oil annually.

Oil recycling

Secondary methods of oil refining include procedures that are aimed at increasing the amount of motor fuel produced. During such processes, chemical modification of hydrocarbon molecules found in oil is carried out, most often with their transformation into forms more convenient for oxidation.
All secondary processes are divided into three categories:

• deepening: various types of cracking, visbreaking, delayed coking, creation of bitumen and others
• upgrading: reforming, hydrotreating, isomerization
• others, for example, oil production, MTBE, alkylation, aromatic hydrocarbon production.

Cracking

There are the following types of cracking:

• thermal
• catalytic
• hydrocracking.

Motor gasoline contains hydrocarbons with 4-12 carbon atoms, diesel fuel contains hydrocarbons with 12-25 atoms, and oil - with 25-70 atoms. As the number of atoms increases, the mass of molecules also increases. Through cracking, heavy molecules are broken down into lighter ones and converted into easily boiling hydrocarbons. In this case, gasoline, kerosene and diesel fractions are formed.
In thermal cracking there are:

• vapor phase cracking, in which oil is heated to 520-550°C and a pressure of 2-6 atm. Today, this method is outdated and is not used because it is characterized by low productivity and a high content (up to 40%) of unsaturated hydrocarbons in the final product
• liquid-phase cracking is carried out at a temperature of 480-500°C and a pressure of 20-50 atm. The level of productivity increases, the volume (25-30%) of unsaturated hydrocarbons decreases. Gasoline fractions obtained by thermal cracking are used as a component of commercial motor gasoline. Fuels after this process have low chemical stability, which can be improved by introducing special antioxidant additives into the fuel.

Catalytic cracking is a more advanced technological process. During this process, the heavy molecules of oil hydrocarbons are broken down under conditions of temperature 430-530°C and pressure that is close to atmospheric in the presence of catalysts. The task of the catalyst is to direct the process and promote the isomerization of saturated hydrocarbons, as well as the conversion reaction from unsaturated to saturated. Gasoline obtained in this way is characterized by high detonation resistance and chemical stability.
In addition, a subtype of catalytic cracking is used - hydrocracking. During this process, heavy raw materials are decomposed with the help of hydrogen at a temperature of 420-500°C and a pressure of 200 atm. The reaction is possible only in a special reactor in the presence of catalysts (oxides of W, Mo, Pt). The result of hydrocracking is fuel for turbojet power units.
During the process of catalytic reforming, aromatization of gasoline fractions occurs due to the catalytic conversion of naphthenic and paraffin hydrocarbons into aromatic ones. In addition to aromatization, the molecules of paraffin hydrocarbons undergo isomerization, the heaviest hydrocarbons are split into smaller ones.

Petroleum products

Everyone knows that oil is a valuable raw material used to produce fuel for various vehicles, for example, gasoline and diesel fuel for cars, aviation kerosene for aircraft jet engines. Fuel is the main product of oil refining. However, oil refining does not end with fuel alone. Today, oil is used to produce a huge number of other useful components used in completely unexpected things. We use similar petroleum products in our daily lives, but we are not aware of their origin.
The most popular today is polyethylene or plastic. Millions of tons of polyethylene plastic are used to create plastic bags, food containers and other consumer goods.
Probably all people have used Vaseline at some point. It was invented by the English chemist Robert Chesbrough, who was extremely curious and observant, as a result of which he was able to discern the beneficial qualities of this substance in the residues of oil refining at the end of the 19th century. Today, Vaseline is used in medicine, in cosmetology and even as a food additive.
Women have been using cosmetics, and lipstick in particular, for thousands of years. Previously, lipstick contained various harmful ingredients. However, today it has a number of useful qualities, and its composition includes hydrocarbons: liquid and solid paraffin, ceresin.
Another popular product that contains hydrocarbons is chewing gum. It is based not only on natural components, but also on polyethylene and paraffin resins. Due to the fact that chewing gum consists of polymers obtained from petroleum refining, it takes an extremely long time to decompose. For this reason, there is no need to throw chewing gum on the street, as it will lie in the ground for many many years.
Perhaps the most unique material obtained from oil is nylon. It’s hard to imagine modern life without nylon tights. Nylon is a very strong and lightweight material. Its use does not end with tights alone. It is used to make dishwashing detergents and parachutes. This polymer was invented in 1935 by DuPont specialists.

Oil is divided into fractions to obtain petroleum products in two stages, that is, oil distillation goes through primary and secondary processing.

Primary oil refining process

At this stage of distillation, crude oil is preliminary dehydrated and desalted using special equipment to separate salts and other impurities that can cause corrosion of equipment and reduce the quality of refined products. After this, the oil contains only 3-4 mg of salts per liter and no more than 0.1% water. The prepared product is ready for distillation.

Due to the fact that liquid hydrocarbons boil at different temperatures, this property is used during the distillation of oil to separate separate fractions from it at different boiling phases. The distillation of oil at the first oil refineries made it possible to isolate the following fractions depending on temperature: gasoline (boils at 180°C and below), jet fuel (boils at 180-240°C) and diesel fuel (boils at 240-350°C). What remains from oil distillation is fuel oil.

During the distillation process, oil is divided into fractions (components). The result is commercial petroleum products or their components. Oil distillation is the initial stage of its processing in specialized plants.

When heated, a vapor phase is formed, the composition of which is different from the liquid. The fractions obtained by distilling oil are usually not a pure product, but a mixture of hydrocarbons. Individual hydrocarbons can be isolated only through repeated distillation of petroleum fractions.

Direct distillation of oil is performed

By single evaporation (so-called equilibrium distillation) or simple distillation (fractional distillation);

With and without rectification;

Using a vaporizing agent;

Under vacuum and at atmospheric pressure.

Equilibrium distillation separates oil into fractions less clearly than simple distillation. Moreover, more oil goes into the vapor state at the same temperature in the first case than in the second.

Fractional distillation of oil makes it possible to obtain various products for diesel and jet engines), as well as raw materials (benzene, xylenes, ethylbenzene, ethylene, butadiene, propylene), solvents and other products.

Secondary oil refining process

Secondary distillation of oil is carried out by the method of chemical or thermal catalytic splitting of those products that are isolated from it as a result of primary oil distillation. This produces a larger amount of gasoline fractions, as well as raw materials for the production of aromatic hydrocarbons (toluene, benzene and others). The most common secondary oil refining technology is cracking.

Cracking is the process of high-temperature refining of oil and separated fractions to obtain (mainly) products that have a lower content. These include motor fuel, lubricating oils, etc., raw materials for the petrochemical and chemical industries. Cracking occurs with the rupture of C-C bonds and the formation of carbanions or free radicals. C-C bond cleavage occurs simultaneously with dehydrogenation, isomerization, polymerization, and condensation of intermediates and starting materials. The last two processes form a cracking residue, i.e. fraction with a boiling point above 350°C and coke.

Oil distillation by cracking was patented in 1891 by V. G. Shukhov and S. Gavrilov, then these engineering solutions were repeated by W. Barton during the construction of the first industrial installation in the USA.

Cracking is carried out by heating raw materials or exposure to catalysts and high temperature.

Cracking allows you to extract more useful components from fuel oil.