Brief description of the main technological processes of fuel production. Deep oil refining

Primary oil refining

In Russia, the main volumes of crude oil supplied for processing are supplied to refineries from production associations via main oil pipelines. Small quantities of oil, as well as gas condensate, are supplied by railway. In oil importing countries with access to the sea, supplies to port refineries are carried out by water transport. Raw materials received at the plant are supplied to the appropriate containers commodity base, connected by pipelines to all process units of the refinery. The amount of oil received is determined according to instrument metering data, or by measurements in raw material tanks.

Crude oil contains salts that are highly corrosive technological equipment. To remove them, oil coming from raw material tanks is mixed with water in which the salts are dissolved and supplied to the ELOU - electrical desalination plant. The desalting process is carried out in electric dehydrators- cylindrical devices with electrodes mounted inside. Under the influence of high voltage current (25 kV or more), the mixture of water and oil (emulsion) is destroyed, water collects at the bottom of the apparatus and is pumped out. For more effective destruction of the emulsion, special substances are introduced into the raw materials - demulsifiers. Process temperature 100-120°C.
Desalted oil from the ELOU is supplied to an atmospheric-vacuum distillation unit, which at Russian refineries is designated by the abbreviation AVT - atmospheric-vacuum tube. This name is due to the fact that the heating of the raw material before dividing it into fractions is carried out in coils tube furnaces due to the heat of fuel combustion and the heat of flue gases. AVT is divided into two blocks - atmospheric and vacuum distillation.
Atmospheric distillation is intended for selection light oil fractions- gasoline, kerosene and diesel, boiling up to 360°C, the potential yield of which is 45-60% of oil. The remainder of atmospheric distillation is fuel oil.
The process consists of separating oil heated in a furnace into separate fractions into distillation column- a cylindrical vertical apparatus, inside of which there are contact devices (plates), through which vapor moves upward and liquid moves downward. Distillation columns of various sizes and configurations are used in almost all oil refining installations; the number of trays in them varies from 20 to 60. Heat is supplied to the bottom of the column and heat is removed from the top of the column, and therefore the temperature in the apparatus gradually decreases from the bottom to the top. As a result, the gasoline fraction is removed from the top of the column in the form of vapor, and the vapors of the kerosene and diesel fractions are condensed in the corresponding parts of the column and removed, the fuel oil remains liquid and is pumped out from the bottom.
Vacuum distillation is intended for selection from fuel oil oil distillates at refineries of fuel-oil profile, or wide oil fraction (vacuum gas oil) at a fuel profile refinery. The remainder of vacuum distillation is tar. The need to select oil fractions under vacuum is due to the fact that at temperatures above 380°C the thermal decomposition of hydrocarbons begins (cracking), and the boiling point of vacuum gas oil is 520°C or more. Therefore, distillation is carried out at a residual pressure of 40-60 mm Hg. Art., which allows you to reduce the maximum temperature in the apparatus to 360-380°C. Vacuum in the column is created using appropriate equipment; the key devices are steam or liquid ejectors.
The gasoline fraction obtained in an atmospheric unit contains gases (mainly propane and butane) in a volume exceeding quality requirements and cannot be used either as a component of motor gasoline or as commercial straight-run gasoline. In addition, oil refining processes aimed at increasing the octane number of gasoline and the production of aromatic hydrocarbons use narrow gasoline fractions as raw materials. This explains the inclusion of this process in the technological scheme of oil refining, in which liquefied gases are distilled from the gasoline fraction, and it is distilled into 2-5 narrow fractions on the appropriate number of columns.
Primary oil refining products are cooled in heat exchangers, in which heat is transferred to cold raw materials supplied for processing, due to which process fuel is saved, in water and air refrigerators and are taken out of production. A similar heat exchange scheme is used in other refinery units.
Modern primary processing plants are often combined and can include the above processes in various configurations. The capacity of such installations ranges from 3 to 6 million tons of crude oil per year.
Several primary processing units are being built at factories to avoid a complete shutdown of the plant when one of the units is taken out for repairs.
Table 14 shows the products of primary oil refining

Table 14 Products of primary oil refining

*) - n.k. - beginning of boiling **) - k.k. - end of boiling

Technological installations for oil refining are designed to separate oil into fractions and subsequent processing or use them as components of commercial petroleum products. They are the basis of all refineries. Almost all components of motor fuels, lubricating oils, raw materials for secondary processes and petrochemical production are produced here. The range and quality of the resulting components and the technical and economic indicators of subsequent petroleum processing processes depend on their work.

Settings primary distillation we have received the name tubular (apparently, during the period of transition from still distillation units to installations with oil heating in a furnace coil). Accordingly, if the installation is designed for the distillation of oil with the selection of only light distillates (gasoline, kerosene, diesel fuel), boiling up to 350 ° C, then it is called an atmospheric tubular (AT) installation. If the installation is designed to distill only fuel oil under vacuum, it is called a vacuum tube (VT) installation. In the general case, when the installation is intended for complete, deep distillation of oil, it is called an atmospheric-vacuum tubular (AVT) installation. When combined with a deep oil desalting unit, the installation is called ELOU-AVT.

Modern oil distillation processes are combined with the processes of dehydration and desalting, secondary distillation and stabilization of the gasoline fraction: ELOU-AT, ELOU-AVT, ELOU-AVT-secondary distillation, etc. In Fig. Figure 2 shows a basic technological diagram of such an installation, which includes 4 blocks - ELOU, AT, VT and a unit for stabilization and secondary distillation of gasoline (VTB).

Depending on the direction of use of fractions, oil distillation plants are usually called fuel, oil or fuel-oil and, accordingly, oil refining options.

At AT installations, shallow oil is processed to produce fuel (gasoline, kerosene, diesel) fractions and fuel oil. VT units are designed for fuel oil distillation. The gas oil, oil fractions and tar obtained from them are used as raw materials for subsequent (secondary) processing processes to produce fuels, lubricating oils, coke, bitumen and other petroleum products.

The capacities of currently operating AVTs range from 0.5 to 10 million tons/year. Small installations (0.5 - 2.0 million tons/year) were built mainly until the end of the 1950s. In the 1960s Mass construction of ELOU-AVT units began, first at 3, and then at 6 and 8 million tons per year. The largest ABT plant with a capacity of 11 million tons/year was built in 1975 in Antwerp. In the same years, two plants with a capacity of 10.5 million tons/year were launched in the United States. Subsequently, the construction of such powerful installations was not carried out, and for the most part the capacity of ELOU-AVT installations remained at the level of 6-8 million tons/year both in our country and abroad. In the future, due to a further decline in oil production, it is possible that medium- and low-capacity AVT installations (2-3 million tons/year) will again become more profitable.

Rice. 2.

/ - oil tank; 2 - electric dehydrators; 3, 4 and 5 - topping, atmospheric and vacuum columns; 6 - strippings; 7 and 8 - stabilization and secondary distillation columns; 9, 10 - atmospheric and vacuum furnaces; // - two-stage steam ejector pumps; / - oil, // and /// - hydrocarbon gas of low and high pressure; IV - liquefied gas; V" - gasoline head (Cf - 85 ° C); VI - gasoline fraction (85-180 ° C); VII - unstable gasoline; VIII - stripped oil; IX - heavy component of gasoline (100-180 "C); X-kerosene (140-240 °C); XI - diesel fuel (200-350 °C), XII - fuel oil; XIII - mixture of non-condensable gases; XIV - light gas oil fraction (up to 300 °C); XV - light vacuum gas oil (280-360 °C); XVI - vacuum gas oil (350-500 °C); XVII - tar (above 500 °C); VP and KB - water vapor and its condensate; GS - hot jet; VCO and PCO - upper and intermediate circulation irrigation

At a modern refinery, AVT units are the main ones in the entire technological chain of oil refining and determine the capacity of the plant as a whole. The total number of distillates separated from oil at AVT ranges from 7 to 10, and each of them is sent for further technological operations (cleaning, upgrading of the chemical composition, catalytic processing). /

Primary oil refining is a thermal process, and therefore it is associated with significant energy costs (fuel, water, air for cooling, electricity for pumping, water steam). Specific energy consumption (energy consumption per 1 ton of processed oil) for automatic turbines with a capacity of 6 million tons/year are:

fuel burned in furnaces - 35-38 kg/t (separately for AT - 20-25 kg/t);

recycled water for cooling process flows - 3-7 m3/t;

electricity - 7-8 kW * h/t; water steam - 100-150 MJ/t.

If we convert all these energy carriers into fuel equivalent using the corresponding equivalents, then the primary distillation of 1 ton of oil requires on average 50 - 60 kg of fuel with a calorific value close to the calorific value of oil (or 60 -80 kg of standard fuel).

Oil distillation at AVT is a multi-stage process (desalting, topping, atmospheric and vacuum distillation, stabilization and secondary distillation of gasoline), therefore both general and stepwise material balance of oil distillation can be considered. In the first case, the material balance is understood as the yield [in% (wt.)] of all final distillation products from the original oil, the amount of which is taken as 100%. In the second case, the material balance of each stage is understood as the yield [in% (wt.)] of distillation products at a given stage (they may not be final, but intermediate, as, for example, in a topping column) from the raw materials of a given stage, which is accepted for each steps beyond 100%.

Below we will talk about the general material balance of the final products of distillation. A step-by-step material balance is compiled during technological calculations of AVT.

Oil (I) (100%) is supplied to the installation with a content of mineral salts from 50 to 300 mg/l and water 0.5 - 1.0% (May).

Hydrocarbon gas (II). Its yield from oil depends on the content of gas dissolved in it after field treatment. If the oil is light (density 0.8 - 0.85), then the yield of this gas can be 1.5 - 1.8% (wt). For heavy oils this yield is less, and for oils that have undergone stabilization it is zero.

Of the above total gas yield, about 90% is the gas taken in the topping column. The composition of this gas includes saturated hydrocarbons C1 - C4 with an admixture of C5. The low pressure of this gas and its small quantities do not allow its use in gas fractionation units (GFU) for the separation of individual hydrocarbons, and this gas is often used as an energy fuel in AVT furnaces. If the yield of this gas is sufficiently high (1.5% and above), it may be economically profitable to compress it with a gas compressor to a higher pressure (2-4 MPa) and process it into HFCs.

Dry hydrocarbon gas of gasoline stabilization (III) is the part of light hydrocarbons C1 - C3 remaining dissolved in gasoline. Its output is small. Its pressure is up to 1.0 MPa, so it can be sent to HFC, but due to the small amount it is often sent to the gas line and burned in furnaces.

The liquefied gasoline stabilization head (IV) contains mainly propane and butanes with an admixture of pentanes. Its yield is also small. It is used as a component of liquefied household gas or gas motor fuel for cars (SPBTL or SPBTZ).

Light gasoline (V) is the fraction of gasoline n. k. -85 °C. Its yield from oil is 4-6% (May). The octane number, depending on the chemical composition, does not exceed 70 (by the motor method), most often it is 60 - 65. It is used for the preparation of petroleum solvents or sent for catalytic processing (isomerization) in order to increase the octane number to 82 - 85 and be included in commercial motor gasoline .

Gasoline fraction 85 - 180°C (VI). Its yield from oil, depending on the fractional composition of the latter, can vary widely, but is usually 10 - 14%. The octane number of this gasoline fraction is low (ROM = 45 t55), and therefore it is sent for catalytic upgrading (catalytic reforming), where due to the conversion of n-alkanes and naphthenes into aromatic hydrocarbons, its octane number increases to 88 - 92, and is then used as a basic component of motor gasoline.

Kerosene (X). There may be two options for selecting this oil stream. One option is to select aviation kerosene - a fraction of 140 - 230 "C. Its yield is 10 - 12% and it is used as ready-made commercial jet fuel TS-1. If such fuel cannot be obtained from oil (based on sulfur content, starting temperature crystallization or other indicators), then the first side stream X in the atmospheric column removes the component of winter or arctic diesel fuel. The yield of such a component (fractions 140 - 280 °C or 140 - 300 °C) is 14 - 18% (wt). It is used either directly as a component of these fuels (if it meets the standards for sulfur content and cloud point and pour point), or is sent for purification from sulfur and separation of n-alkanes (dewaxing).

Diesel fuel (XI). Its yield is 22 - 26% (wt), if jet fuel is taken from stream A, or 10 - 12% (wt), if a component of winter or arctic diesel fuel is taken from stream X. As a rule, this stream is a component of winter or summer diesel fuel directly ( if it meets the standards for sulfur content and cloud point) or after purification from sulfur and n-alkanes.

Light gas oil fraction (XIV). Its yield is 0.5 -1.0% (wt.) of oil. As already noted, this is a fraction of 100 -250 °C, it is the result of partial thermal destruction of fuel oil when heated in a furnace. Therefore, it contains not only saturated but also unsaturated alkanes. It is used as a component of diesel fuel, if the latter is sent for hydrotreating from sulfur, or is sent to light boiler fuel.

Light vacuum gas oil (XV) - fraction 240 - 380 °C, its yield from oil is 3 - 5% (wt). In terms of its quality indicators, it is close to summer diesel fuel XI and is most often therefore mixed with it and used accordingly.

Vacuum gas oil (XVI) is the main distillate of vacuum distillation of fuel oil using the fuel option (if oil does not allow obtaining high-quality oils). Its boiling range is 350 - 500 °C (in some cases 350 - 550 °C). The yield from oil is accordingly 21 - 25% (wt.) (or 26 - 30%). It is used as a raw material for the catalytic cracking process (to produce high-octane gasoline and other motor fuels) or hydrocracking (to produce aviation kerosene or high-index oils). It can be used either directly [if the sulfur content in vacuum gas oil is below 0.5% (wt.)], or after purification from sulfur and other impurities (nitrogen, metals).

If oil (and, accordingly, fuel oil) makes it possible to obtain high-index oils, then from vacuum column 5, instead of one run XVI, two runs of oil distillates are removed at 350 - 420 ° C [oil yield 10 - 14% (wt.)] and 420 - 500 ° C [ yield 12 -16% (wt.)] - Both cuts are sent for purification (from resins, high molecular weight aromatic compounds, paraffin, sulfur) to obtain from them base distillate oils of medium and high viscosity.

Tar (XVII) is the residual part of the oil that boils above 500 °C if vacuum gas oil with an end boiling point of 550 °C is taken. Its yield from oil, depending on the content of asphalt-resinous substances and heavy hydrocarbon fractions in it, ranges from 10 to 20% (wt). In some cases, for example, when refining Tengiz oil, it reaches 5, and Karazhanbas oil - up to 45% (wt).

Tar can be used in several ways:

as a component of heavy boiler fuels;

as residual bitumen (if oil allows it to be obtained) or as a raw material for the production of oxidized bitumen;

as a raw material for coking and obtaining valuable petroleum coke from it (if the oil is low-sulfur);

as a raw material for obtaining base residual oil (for oils of groups 1 and 2 and subgroups).

In addition to the listed end products of oil distillation at the AVT, several processing wastes are obtained, which include the following.

ELOU waste water is mainly water used to wash oil from salts. The amount of this water is quite large - 1-3% (wt.) of the amount of oil processed (at an ELOU-AVT installation with a capacity of 6 million tons/year this will be about per day 250 - 700 t).

This water contains dissolved mineral salts, washed from oil (from 10 to 30 g/l, pH 7.0 - 7.5), significant amounts of demulsifier, as well as oil emulsified in water (up to 1%).

Due to such contamination, ELOU wastewater cannot be reused in the water recycling system as a refrigerant and is therefore sent for treatment. Cleaning is usually multi-stage.

Water vapor condensate (KB). During primary distillation, water vapor is used as a stripping agent in distillation columns, as an ejecting agent for suction of a vapor-gas mixture from a vacuum column, and as a coolant in reboilers. After condensation, all these streams form water condensate of varying quality.

Process condensate (from columns and ejectors) is in direct contact with petroleum products and is therefore contaminated with hydrocarbons and sulfur-containing compounds emulsified in it. Its amount is 2.5 - 3.0% for oil. It is sent to the ELOU unit as wash water or for cleaning, after which it can be reused to produce water vapor.

The energy condensate (from the reboilers) is clean and is sent to regenerate steam.

Non-condensable gas from the ejectors (XIII) is a mixture of light hydrocarbons (up to Q), hydrogen sulfide, air and water vapor. The yield of the mixture of these gases averages about 0.05% (wt.) of the original oil (maximum - up to 0.1%). The gases are directed into the firebox of one of the tubular furnaces to burn the combustible components.

An important characteristic of the AVT operation is the selection of the amount of light distillates and the selection of the amount of oil distillates.

Oil refining is a rather complex process that requires the involvement of... Many products are obtained from extracted natural raw materials - different types fuels, bitumen, kerosene, solvents, lubricants, petroleum oils and others. Oil refining begins with the transportation of hydrocarbons to the plant. The production process occurs in several stages, each of which is very important from a technological point of view.

Recycling process

The process of oil refining begins with its specialized preparation. This is caused by the presence of numerous impurities in natural raw materials. An oil deposit contains sand, salts, water, soil, and gaseous particles. Water is used to extract large quantities of products and preserve energy resource deposits. This has its advantages, but significantly reduces the quality of the resulting material.

The presence of impurities in petroleum products makes it impossible to transport them to the plant. They provoke the formation of plaque on heat exchangers and other containers, which significantly reduces their service life.

Therefore, the extracted materials undergo complex cleaning - mechanical and fine. At this stage of the production process, the resulting raw materials are separated into oil and. This happens using special oil separators.

To purify raw materials, they are generally kept in hermetically sealed containers. To activate the separation process, the material is exposed to cold or high temperature. Electric desalting plants are used to remove salts contained in raw materials.

How does the process of separating oil and water occur?

After initial purification, a sparingly soluble emulsion is obtained. It is a mixture in which particles of one liquid are evenly distributed in the second. On this basis, 2 types of emulsions are distinguished:

• hydrophilic. It is a mixture where oil particles are in water;
• hydrophobic. The emulsion consists mainly of oil with water particles in it.

The process of breaking the emulsion can occur mechanically, electrically or chemically. The first method involves settling the liquid. This happens under certain conditions - heating to a temperature of 120-160 degrees, increasing pressure to 8-15 atmospheres. Delamination of the mixture usually occurs within 2-3 hours.

In order for the emulsion separation process to be successful, it is necessary to prevent water evaporation. Also, the separation of pure oil is carried out using powerful centrifuges. The emulsion is divided into fractions when it reaches 3.5-50 thousand rpm.

The use of a chemical method involves the use of special surfactants called demulsifiers. They help dissolve the adsorption film, as a result of which the oil is cleared of water particles. The chemical method is often used in conjunction with the electrical method. The last cleaning method involves exposing the emulsion to electric current. It provokes the union of water particles. As a result, it is easier to remove from the mixture, resulting in oil of the highest quality.

Primary processing

Oil production and refining occurs in several stages. A peculiarity of the production of various products from natural raw materials is that even after high-quality purification, the resulting product cannot be used for its intended purpose.

The starting material is characterized by the content of various hydrocarbons, which differ significantly in molecular weight and boiling point. It contains substances of naphthenic, aromatic, and paraffin nature. The feedstock also contains sulfur, nitrogen and oxygen compounds of the organic type, which must also be removed.

All existing methods Oil refining is aimed at separating it into groups. During the production process, a wide range of products with different characteristics are obtained.

Primary processing of natural raw materials is carried out on the basis different temperatures boiling of its constituent parts. To carry out this process, specialized installations are used that make it possible to obtain various petroleum products - from fuel oil to tar.

If you process natural raw materials in this way, you will not be able to obtain material ready for further use. Primary distillation is aimed only at determining the physical and chemical properties of oil. After this, the need for further processing can be determined. They also establish the type of equipment that needs to be used to perform the required processes.

Primary oil refining

Oil distillation methods

The following methods of oil refining (distillation) are distinguished:

• single evaporation;
• repeated evaporation;
• distillation with gradual evaporation.

The flash evaporation method involves processing oil under high temperature at a given value. As a result, vapors are formed that enter a special apparatus. It is called an evaporator. In this cylindrical device, vapors are separated from the liquid fraction.

With repeated evaporation, the raw material is subjected to processing, in which the temperature is increased several times according to a given algorithm. The latter distillation method is more complex. Oil refining with gradual evaporation implies a smooth change in the main operating parameters.

Distillation equipment

Industrial oil refining is carried out using several devices.

Tube furnaces. In turn, they are also divided into several types. These are atmospheric, vacuum, atmospheric-vacuum furnaces. Using the first type of equipment, shallow processing of petroleum products is carried out, which makes it possible to obtain fuel oil, gasoline, kerosene and diesel fractions. In vacuum furnaces, as a result, more efficient work raw materials are divided into:

• tar;
• oil particles;
• gas oil particles.

The resulting products are completely suitable for the production of coke, bitumen, and lubricants.

Distillation columns. The process of processing crude oil using this equipment involves heating it in a coil to a temperature of 320 degrees. After this, the mixture enters the intermediate levels of the distillation column. On average, it has 30-60 gutters, each of which is placed at a certain interval and equipped with a bath of liquid. This causes the vapor to flow down in the form of droplets as condensation forms.

There is also processing using heat exchangers.

Recycling

After determining the properties of the oil, depending on the need for a certain end product, the type of secondary distillation is selected. Basically, it consists of a thermal-catalytic effect on the feedstock. Deep oil refining can occur using several methods.

Fuel The use of this secondary distillation method makes it possible to obtain a number of high-quality products - motor gasoline, diesel, jet, and boiler fuels. To carry out processing, you do not need to use a lot of equipment. As a result of using this method, a finished product is obtained from heavy fractions of raw materials and sediment. The fuel distillation method includes:

• cracking;
• reforming;
• hydrotreating;
• hydrocracking.

Fuel and oil. As a result of using this distillation method, not only various fuels are obtained, but also asphalt and lubricating oils. This is done using the extraction method, deasphalting.

Petrochemical. As a result of applying this method with the use of high-tech equipment, a large number of products are obtained. This is not only fuel, oils, but also plastics, rubber, fertilizers, acetone, alcohol and much more.

How the objects around us are made from oil and gas - accessible and understandable

This method considered the most common. It is used to process sulfur or high-sulfur oil. Hydrotreating can significantly improve the quality of the resulting fuels. Various additives are removed from them - sulfur, nitrogen, oxygen compounds. The material is processed using special catalysts in a hydrogen environment. In this case, the temperature in the equipment reaches 300-400 degrees, and the pressure – 2-4 MPa.

As a result of distillation, the organic compounds contained in the raw material decompose when interacting with hydrogen circulating inside the apparatus. As a result, ammonia and hydrogen sulfide are formed, which are removed from the catalyst. Hydrotreating allows you to process 95-99% of raw materials.

Catalytic cracking

Distillation is carried out using zeolite-containing catalysts at a temperature of 550 degrees. Cracking is considered very effective method processing of prepared raw materials. With its help, high-octane motor gasoline can be obtained from fuel oil fractions. The yield of pure product in this case is 40-60%. Liquid gas is also obtained (10-15% of the original volume).

Catalytic reforming

Reforming is carried out using an aluminum-platinum catalyst at a temperature of 500 degrees and a pressure of 1-4 MPa. At the same time, a hydrogen environment is present inside the equipment. This method is used to convert naphthenic and paraffinic hydrocarbons into aromatic ones. This allows you to significantly increase the octane number of manufactured products. When using catalytic reforming, the yield of pure material is 73-90% of the recovered raw material.

Hydrocracking

Allows you to obtain liquid fuel when exposed to high pressure (280 atmospheres) and temperature (450 degrees). Also this process occurs with the use of strong catalysts - molybdenum oxides.

If hydrocracking is combined with other methods of processing natural raw materials, the yield of pure products in the form of gasoline and jet fuel is 75-80%. When using high-quality catalysts, their regeneration may not be carried out for 2-3 years.

Extraction and deasphalting

Extraction involves dividing the prepared raw material into the required fractions using solvents. Subsequently, dewaxing is carried out. It allows you to significantly reduce the pour point of the oil. Also, to obtain high quality products, they are hydrotreated. As a result of extraction, diesel fuel can be obtained. Also, using this technique, aromatic hydrocarbons are extracted from prepared raw materials.

Deasphalting is necessary in order to obtain resin-asphaltene compounds from the final products of distillation of petroleum feedstock. The resulting substances are actively used for the production of bitumen, as catalysts for other processing methods.

Other processing methods

Processing of natural raw materials after primary distillation can be carried out in other ways.

Alkylation. After processing the prepared materials, high-quality components for gasoline are obtained. The method is based on the chemical interaction of olefin and paraffin hydrocarbons, resulting in a high-boiling paraffinic hydrocarbon.

Isomerization. The use of this method makes it possible to obtain a substance with a higher octane number from low-octane paraffinic hydrocarbons.

Polymerization. Allows the conversion of butylenes and propylene into oligomeric compounds. As a result, materials are obtained for the production of gasoline and for various oil chemical processes.

Coking. It is used for the production of petroleum coke from heavy fractions obtained after oil distillation.

The oil refining industry is a promising and developing one. The production process is constantly being improved through the introduction of new equipment and techniques.

Video: Oil refining

Oil is a mineral that is a water-insoluble oily liquid that can be almost colorless or dark brown. The properties and methods of oil refining depend on percentage predominantly hydrocarbons in its composition, which varies in different fields.

Thus, in the Sosninskoye field (Siberia), alkanes (paraffin group) occupy a share of 52 percent, cycloalkanes - about 36%, aromatic hydrocarbons - 12 percent. And, for example, in the Romashkinskoye field (Tatarstan) the share of alkanes and aromatic carbons is higher - 55 and 18 percent, respectively, while cycloalkanes have a share of 25 percent. In addition to hydrocarbons, these raw materials may include sulfur and nitrogen compounds, mineral impurities, etc.

Oil was first “refined” in 1745 in Russia

This natural resource is not used in its raw form. To obtain technically valuable products (solvents, motor fuels, components for chemical production), oil is processed using primary or secondary methods. Attempts to transform this raw material were made back in the mid-eighteenth century, when, in addition to candles and torches used by the population, “garnish oil” was used in the lamps of a number of churches, which was a mixture vegetable oil and refined oil.

Oil purification options

Refining is often not included directly in petroleum refining processes. This is rather a preliminary stage, which may consist of:

Chemical refining, when oil is exposed to oleum and concentrated sulfuric acid. This removes aromatic and unsaturated hydrocarbons.

Adsorption cleaning. Here, tars and acids can be removed from petroleum products by treatment with hot air or by passing the oil through an adsorbent.

Catalytic purification – mild hydrogenation to remove nitrogen and sulfur compounds.

Physico-chemical cleaning. In this case, excess components are selectively released using solvents. For example, the polar solvent phenol is used to remove nitrogen and sulfur compounds, and non-polar solvents - butane and propane - release tars, aromatic hydrocarbons, etc.

No chemical changes...

Oil refining through primary processes does not involve chemical transformations of the feedstock. Here the mineral is simply divided into its component components. The first device for distilling oil was invented in 1823, in Russian Empire. The Dubinin brothers guessed to put the boiler in a heated furnace, from where a pipe went through a barrel with cold water into an empty container. In the furnace boiler, the oil was heated, passed through the “refrigerator” and settled.

Modern methods of preparing raw materials

Today, at oil refineries, oil refining technology begins with additional purification, during which the product is dehydrated using ELOU devices (electric desalting units), freed from mechanical impurities and light carbohydrates (C1 - C4). Then the raw material can be sent for atmospheric distillation or vacuum distillation. In the first case, the operating principle of the factory equipment resembles that which was used back in 1823.

Only the oil refining plant itself looks different. The company has furnaces the size of windowless houses, made of the best refractory bricks. Inside them there are many kilometers of pipes in which oil moves at high speed (2 meters per second) and is heated to 300-325 C with a flame from a large nozzle (at higher temperatures, hydrocarbons simply decompose). The pipe for condensation and cooling of vapors is nowadays replaced by distillation columns (can be up to 40 meters in height), where the vapors are separated and condensed, and entire towns from different tanks are built to receive the resulting products.

What is material balance?

Oil refining in Russia gives different material balances during atmospheric distillation of raw materials from one or another deposit. This means that the output can be different proportions for different fractions - gasoline, kerosene, diesel, fuel oil, associated gas.

For example, for West Siberian oil, gas yield and losses are one percent each, respectively, gasoline fractions (released at temperatures from about 62 to 180 C) occupy a share of about 19%, kerosene - about 9.5%, diesel fraction - 19% , fuel oil - almost 50 percent (released at temperatures from 240 to 350 degrees). The resulting materials are almost always subject to additional processing, since they do not meet the operational requirements for the same machine engines.

Production with less waste

Vacuum oil refining is based on the principle of substances boiling at a lower temperature when pressure decreases. For example, some hydrocarbons in oil boil only at 450 C (atmospheric pressure), but they can be made to boil at 325 C if the pressure is lowered. Vacuum processing of raw materials is carried out in rotary vacuum evaporators, which increase the distillation speed and make it possible to obtain ceresins, paraffins, fuel, oils from fuel oil, and then use the heavy residue (tar) for the production of bitumen. Vacuum distillation, compared to atmospheric processing, produces less waste.

Recycling allows us to obtain high-quality gasoline

The secondary oil refining process was invented in order to obtain more motor fuel from the same feedstock by influencing the molecules of petroleum hydrocarbons, which acquire formulas more suitable for oxidation. Recycling includes different types so-called “cracking”, including hydrocracking, thermal and catalytic options. This process was also originally invented in Russia, in 1891, by engineer V. Shukhov. It involves the breakdown of hydrocarbons into forms with fewer carbon atoms per molecule.

Oil and gas processing at 600 degrees Celsius

The operating principle of cracking plants is approximately the same as that of installations atmospheric pressure vacuum production. But here the processing of raw materials, which is most often represented by fuel oil, is carried out at temperatures close to 600 C. Under this influence, the hydrocarbons that make up the fuel oil mass break down into smaller ones, which make up the same kerosene or gasoline. Thermal cracking is based on processing high temperatures and produces gasoline with a large number of impurities, catalytic - also through heat treatment, but with the addition of catalysts (for example, special clay dust), which allows you to get more gasoline of good quality.

Hydrocracking: main types

Oil production and refining today may include different kinds hydrocracking, which is a combination of hydrotreating processes, splitting large hydrocarbon molecules into smaller ones and saturating unsaturated hydrocarbons with hydrogen. Hydrocracking can be light (pressure 5 MPa, temperature about 400 C, one reactor is used, mainly diesel fuel and material for catalytic cracking are obtained) and hard (pressure 10 MPa, temperature about 400 C, several reactors, diesel, gasoline and kerosene are obtained factions). Catalytic hydrocracking makes it possible to produce a number of oils with high viscosity coefficients and low content of aromatic and sulfur hydrocarbons.

Recycling of oil, in addition, can use the following technological processes:

Visbreaking. In this case, at temperatures up to 500 C and pressures ranging from half to three MPa, secondary asphaltenes, hydrocarbon gases, and gasoline are obtained from the raw material by splitting paraffins and naphthenes.

Coking of heavy oil residues is a deep oil refining, when the raw material is processed at temperatures close to 500 C under a pressure of 0.65 MPa to produce gas oil components and petroleum coke. The stages of the process end with the production of a “coke cake”, which is preceded (in reverse order) densification, polycondensation, aromatization, cyclization, dehydrogenation and cracking. In addition, the product must also be dried and calcined.

Reforming. This method processing of petroleum products was invented in Russia in 1911 by engineer N. Zelinsky. Today, catalytic reforming is used to obtain high-quality aromatic hydrocarbons and gasolines, as well as hydrogen-containing gas from naphtha and gasoline fractions, for subsequent processing in hydrocracking.

Isomerization. Oil and gas refining in this case involves obtaining an isomer from a chemical compound due to changes in the carbon skeleton of the substance. Thus, high-octane components are isolated from low-octane components of oil to produce commercial gasoline.

Alkylation. This process is based on the incorporation of alkyl substituents into an organic molecule. In this way, components for high-octane gasoline are obtained from unsaturated hydrocarbon gases.

Striving for European standards

Oil and gas processing technology at refineries is constantly being improved. Thus, at domestic enterprises there has been an increase in the efficiency of processing raw materials in terms of parameters: depth of processing, increased selection of light petroleum products, reduction of irreversible losses, etc. Plant plans for the 10-20s of the twenty-first century include a further increase in the depth of processing (up to 88 percent) , improving the quality of manufactured products to European standards, reducing the technogenic impact on the environment.

Currently, various types of fuel, petroleum oils, paraffins, bitumens, kerosenes, solvents, soot, lubricants and other petroleum products obtained by processing raw materials can be obtained from crude oil.

Extracted hydrocarbon raw materials ( oil, passing petroleum gas And natural gas) The field goes through a long stage before important and valuable components are isolated from this mixture, from which usable petroleum products will subsequently be obtained.

Oil refining a very complex technological process that begins with the transportation of petroleum products to oil refineries. Here, oil goes through several stages before becoming a ready-to-use product:

1. preparation of oil for primary processing
2. primary oil refining (direct distillation)
3. oil recycling
4. petroleum products purification

Preparing oil for primary processing

Extracted but not processed oil contains various impurities, for example, salt, water, sand, clay, soil particles, associated gas PNG. The life of the field increases the water content of the oil reservoir and, accordingly, the content of water and other impurities in the produced oil. The presence of mechanical impurities and water interferes with the transportation of oil through oil product pipelines for further processing, causes the formation of deposits in heat exchangers and others, and complicates the process of oil refining.

All extracted oil undergoes a comprehensive purification process, first mechanical, then fine purification.

At this stage, the separation of the extracted raw materials into oil and gas into oil and gas also occurs.

Settling in sealed containers, either cold or heated, removes large amounts of water and solids. To obtain high performance of installations for further oil processing, the latter is subjected to additional dehydration and desalting in special electric desalting plants.

Often, water and oil form a poorly soluble emulsion in which tiny droplets of one liquid are suspended in the other.

There are two types of emulsions:

• hydrophilic emulsion, i.e. oil in water
• hydrophobic emulsion, i.e. water in oil

There are several ways to break emulsions:

• mechanical
• chemical
• electric

Mechanical method in turn is divided into:

• upholding
• centrifugation

The difference in the densities of the emulsion components makes it possible to easily separate water and oil by settling by heating the liquid to 120-160°C under a pressure of 8-15 atmospheres for 2-3 hours. In this case, evaporation of water is not allowed.

The emulsion can also be separated under the action of centrifugal forces in centrifuges when reaching 3500-50000 rpm.

At chemical method the emulsion is broken by the use of demulsifiers, i.e. surfactants. Demulsifiers have greater activity compared to the active emulsifier, form an emulsion of the opposite type, and dissolve the adsorption film. This method is used together with the electric one.

In electric dehydrator installations with electrical influence On an oil emulsion, water particles combine, and faster separation with oil occurs.

Primary oil refining

Extracted oil is a mixture of naphthenic, paraffinic, aromatic carbohydrates, which have different molecular weights and boiling points, and sulfur, oxygen and nitrogenous organic compounds. Primary oil refining consists of separating prepared oil and gases into fractions and groups of hydrocarbons. During distillation, a wide range of petroleum products and intermediates are obtained.

The essence of the process is based on the principle of the difference in boiling temperatures of the components of extracted oil. As a result, the raw material decomposes into fractions - to fuel oil (light oil products) and to tar (oil).

Primary distillation of oil can be carried out with:

• single evaporation
• multiple evaporation
• gradual evaporation

During a single evaporation, the oil is heated in the heater to a predetermined temperature. As it heats up, vapors are formed. When the set temperature is reached, the vapor-liquid mixture enters the evaporator (a cylinder in which steam is separated from the liquid phase).

Process multiple evaporation represents a sequence of single evaporations with a gradual increase in heating temperature.

Distillation gradual evaporation represents a small change in the state of oil with each single evaporation.

The main devices in which oil distillation, or distillation, takes place are tube furnaces, distillation columns and heat exchangers.

Depending on the type of distillation, tube furnaces are divided into atmospheric furnaces AT, vacuum furnaces VT and atmospheric-vacuum tube furnaces AVT. AT installations carry out shallow processing and obtain gasoline, kerosene, diesel fractions and fuel oil. In VT installations, in-depth processing of raw materials is carried out and gas oil and oil fractions, tar are obtained, which are subsequently used for the production of lubricating oils, coke, bitumen, etc. In AVT furnaces, two methods of oil distillation are combined.

The process of oil refining by the principle of evaporation occurs in distillation columns. There, the source oil is supplied to a heat exchanger using a pump, heated, and then enters a tubular furnace (fire heater), where it is heated to a given temperature. Next, oil in the form of a vapor-liquid mixture enters the evaporation part of the distillation column. Here the division of the vapor phase and the liquid phase occurs: the steam rises up the column, the liquid flows down.

The above methods of oil refining cannot be used to isolate individual high-purity hydrocarbons from oil fractions, which will subsequently become raw materials for the petrochemical industry to produce benzene, toluene, xylene, etc. To obtain high-purity hydrocarbons, an additional substance is introduced into oil distillation units to increase the difference in the volatility of separated hydrocarbons.

The resulting components after primary oil refining are usually not used as a finished product. At the primary distillation stage, the properties and characteristics of the oil are determined, on which the choice of further processing process to obtain the final product depends.

As a result of primary oil processing, the following main petroleum products are obtained:

• hydrocarbon gas (propane, butane)
• gasoline fraction (boiling point up to 200 degrees)
• kerosene (boiling point 220-275 degrees)
• gas oil or diesel fuel (boiling point 200-400 degrees)
• lubricating oils (boiling point above 300 degrees) residue (fuel oil)

Oil recycling

Depending on the physical and chemical properties of oil and the need for the final product, a further method of destructive processing of raw materials is selected. Petroleum recycling consists of thermal and catalytic effects on petroleum products obtained by direct distillation. The impact on raw materials, that is, the hydrocarbons contained in oil, changes their nature.

There are options for oil refining:

• fuel
• fuel and oil
• petrochemical

Fuel method processing is used to produce high-quality motor gasoline, winter and summer diesel fuels, fuels for jet engines, boiler fuels. This method uses fewer technological installations. The fuel method is a process that produces motor fuels from heavy petroleum fractions and residues. This type of processing includes catalytic cracking, catalytic reforming, hydrocracking, hydrotreating and other thermal processes.

During fuel and oil processing Along with fuels, lubricating oils and asphalt are produced. This type includes extraction and deasphalting processes.

The greatest variety of petroleum products is obtained as a result petrochemical refining. In this regard, a large number of technological installations are used. As a result of petrochemical processing of raw materials, not only fuels and oils are produced, but also nitrogen fertilizers, synthetic rubber, plastics, synthetic fibers, detergents, fatty acids, phenol, acetone, alcohol, ethers and other chemicals.

Catalytic cracking

Catalytic cracking uses a catalyst to speed up chemical processes without changing the nature of those chemical reactions. The essence of the cracking process, i.e. The splitting reaction consists of passing oils heated to a vapor state through a catalyst.

Reforming

The reforming process is used primarily to produce high-octane gasoline. Only paraffin fractions boiling in the range of 95-205°C can be subjected to this processing.

Types of reforming:

• thermal reforming
• catalytic reforming

During thermal reforming Fractions of primary oil refining are exposed only to high temperatures.

During catalytic reforming the impact on the initial fractions occurs both with temperature and with the help of catalysts.

Hydrocracking and hydrotreating

This processing method consists of obtaining gasoline fractions, jet and diesel fuel, lubricating oils and liquefied gases through the action of hydrogen on high-boiling oil fractions under the influence of a catalyst. As a result of hydrocracking, the original oil fractions also undergo hydrotreating.

Hydrotreating involves removing sulfur and other impurities from raw materials. Typically, hydrotreating units are combined with catalytic reforming units, since the latter produces a large amount of hydrogen. As a result of purification, the quality of petroleum products increases and equipment corrosion decreases.

Extraction and deasphalting

Extraction process consists of separating a mixture of solid or liquid substances using solvents. The extracted components dissolve well in the solvent used. Next, dewaxing is carried out to reduce the pour point of the oil. The final product is obtained through hydrotreating. This processing method is used to produce diesel fuel and extract aromatic hydrocarbons.

As a result of deasphalting, resinous asphaltene substances are obtained from residual oil distillation products. Subsequently, the deasphalted oil is used to produce bitumen and is used as a raw material for catalytic cracking and hydrocracking.

Coking

To obtain petroleum coke and gas oil fractions from heavy fractions of oil distillation, deasphalting residues, thermal and catalytic cracking, and pyrolysis of gasoline, the coking process is used. This type of petroleum product refining consists of the sequential reactions of cracking, dehydrogenation (release of hydrogen from raw materials), cyclization (formation of a cyclic structure), aromatization (increase in aromatic hydrocarbons in oil), polycondensation (release of by-products such as water, alcohol) and compaction to form a continuous “coke cake”. Volatile products released during the coking process are subjected to a rectification process to obtain the target fractions and stabilize them.

Isomerization

The isomerization process consists of converting its isomers from the feedstock. Such transformations lead to the production of gasoline with a high octane number.

Alkyning

By introducing alkyne groups into compounds, high-octane gasoline is obtained from hydrocarbon gases.

It should be noted that in the process of oil refining and to obtain the final product, the entire complex of oil, gas and petrochemical technologies is used. The complexity and variety of finished products that can be obtained from the extracted raw materials also determine the diversity of oil refining processes.