Refinery hydrocracking unit. Recycling (continued). Technological scheme of single-stage hydrocracking with the production of predominantly diesel fuel from vacuum gas oil in a stationary catalyst bed

Hydrocracking is intended for the production of low-sulfur fuel distillates from various raw materials.

Hydrocracking is a later generation process than catalytic cracking and catalytic reforming, so it more efficiently accomplishes the same tasks as these 2 processes.

The raw materials used in hydrocracking plants are vacuum and atmospheric gas oils, thermal and catalytic cracking gas oils, deasphalted oils, fuel oils, and tars.

A hydrocracking technological unit usually consists of 2 blocks:

Reaction unit, including 1 or 2 reactors,

A fractionation unit consisting of a different number of distillation columns.

Hydrocracking products are motor gasoline, jet and diesel fuel, raw materials for petrochemical synthesis and LPG (from gasoline fractions).

Hydrocracking can increase the yield of gasoline components, usually by converting feedstocks such as gas oil.

The quality of gasoline components that is achieved in this way is unattainable by re-passing gas oil through the cracking process in which it was obtained.

Hydrocracking also allows the conversion of heavy gas oil into light distillates (jet and diesel fuel). Hydrocracking does not produce any heavy non-distillable residue (coke, pitch or bottoms), but only light boiling fractions.

Advantages of Hydrocracking

The presence of a hydrocracking unit allows the refinery to switch its capacity from producing large quantities of gasoline (when the hydrocracking unit is running) to producing large quantities of diesel fuel (when it is off).

Hydrocracking improves the quality of gasoline and distillate components.

The hydrocracking process uses the worst components of the distillate and produces a higher than average quality gasoline component.

The hydrocracking process produces significant amounts of isobutane, which is useful for controlling the amount of feedstock in the alkylation process.

The use of hydrocracking units increases the volume of products by 25%.

There are about 10 different types of hydrocrackers in common use today, but they are all very similar to a typical design.

Hydrocracking catalysts are less expensive than catalytic cracking catalysts.

Process

The word hydrocracking is explained very simply. This is catalytic cracking in the presence of hydrogen.

The introduction of cold hydrogen-containing gas into the zones between the layers of the catalyst makes it possible to equalize the temperature of the raw material mixture along the height of the reactor.

The movement of the raw material mixture in the reactors is downward.

The combination of hydrogen, a catalyst and the appropriate process mode allows the cracking of low-quality light gas oil, which is formed in other cracking plants and is sometimes used as a component of diesel fuel.
The hydrocracking unit produces high-quality gasoline.

Hydrocracking catalysts are usually sulfur compounds with cobalt, molybdenum or nickel (CoS, MoS 2, NiS) and aluminum oxide.
Unlike catalytic cracking, but similar to catalytic reforming, the catalyst is located in a fixed bed. Like catalytic reforming, hydrocracking is most often carried out in 2 reactors.

The raw material supplied by the pump is mixed with fresh hydrogen-containing gas and circulating gas, which are pumped by the compressor.

The gas mixture, having passed through the heat exchanger and furnace coils, is heated to a reaction temperature of 290-400°C (550-750°F) and, under a pressure of 1200-2000 psi (84-140 atm), is introduced into the reactor from above. Taking into account the large heat release during the hydrocracking process, cold hydrogen-containing (circulation) gas is introduced into the reactor into the zones between the catalyst layers in order to equalize the temperatures along the height of the reactor. During passage through the catalyst bed, approximately 40-50% of the feedstock is cracked to form products with boiling points similar to gasoline (boiling point up to 200°C (400°F).

The catalyst and hydrogen complement each other in several ways. Firstly, cracking occurs on the catalyst. In order for cracking to continue, a heat supply is required, that is, it is an endothermic process. At the same time, hydrogen reacts with the molecules that are formed during cracking, saturating them, and heat is released. In other words, this reaction, called hydrogenation, is exothermic. Thus, hydrogen provides the heat necessary for cracking to occur.

Secondly, this is the formation of isoparaffins. Cracking produces olefins that can combine with each other, leading to normal paraffins. Due to hydrogenation, the double bonds are quickly saturated, often creating isoparaffins, and thus preventing the re-production of unwanted molecules (the octane numbers of isoparaffins are higher than in the case of normal paraffins).

The mixture of reaction products and circulating gas leaving the reactor is cooled in a heat exchanger, refrigerator and enters the high-pressure separator. Here, the hydrogen-containing gas, for return to the process and mixing with the raw material, is separated from the liquid, which from the bottom of the separator, through a pressure reducing valve, then enters the low-pressure separator. A portion of the hydrocarbon gases is released in the separator, and the liquid stream is sent to a heat exchanger located in front of the intermediate distillation column for further distillation. In the column, at slight excess pressure, hydrocarbon gases and light gasoline are released. The kerosene fraction can be separated as a side stream or left together with gas oil as a distillation residue.

Gasoline is partially returned to the intermediate distillation column in the form of acute irrigation, and its balance amount is pumped out of the installation through the “alkalinization” system. The residue from the intermediate distillation column is separated in an atmospheric column into heavy gasoline, diesel fuel and the >360°C fraction. Since the raw materials in this operation have already been subjected to hydrogenation, cracking and reforming in the 1st reactor, the process in the 2nd reactor proceeds in a more severe mode (higher temperatures and pressures). Like the products of the 1st stage, the mixture leaving the 2nd reactor is separated from hydrogen and sent for fractionation.

The thickness of the walls of the steel reactor for the process taking place at 2000 psi (140 atm) and 400 ° C sometimes reaches 1 cm.

The main task is to prevent cracking from getting out of control. Since the overall process is endothermic, a rapid rise in temperature and a dangerous increase in the cracking rate are possible. To avoid this, most hydrocrackers contain built-in devices to quickly stop the reaction.

Gasoline from the atmospheric column is mixed with gasoline from the intermediate column and removed from the installation. Diesel fuel after the stripping column is cooled, “alkalinized” and pumped out of the installation. The >360°C fraction is used as a hot stream at the bottom of the atmospheric column, and the rest (residue) is removed from the installation. In the case of the production of oil fractions, the fractionation unit also has a vacuum column.

Regeneration of the catalyst is carried out with a mixture of air and inert gas; catalyst service life is 4-7 months.

Products and outputs.

The combination of cracking and hydrogenation produces products whose relative density is significantly lower than the density of the raw material.

Below is a typical distribution of yields of hydrocracking products when gas oil from a coking unit and light fractions from a catalytic cracking unit are used as feedstock.

Hydrocracking products are 2 main fractions that are used as gasoline components.

Volume fractions

Coking gasoil 0.60

Light fractions from catalytic cracking unit 0.40

Products:

Isobutane 0.02

N-Butane 0.08

Light hydrocracking product 0.21

Heavy hydrocracking product 0.73

Kerosene fractions 0.17

Let us remember that from 1 unit of raw materials about 1.25 units of products are obtained.

It does not indicate the required amount of hydrogen, which is measured in standard ft 3 /bbl of feed.

The usual consumption is 2500 st.

The heavy product of hydrocracking is naphtha, which contains many aromatic precursors (that is, compounds that are easily converted into aromatics).

This product is often sent to a reformer for upgrading.

Kerosene fractions are a good jet fuel or feedstock for distillate (diesel) fuel because they contain little aromatics (as a result of saturation of double bonds with hydrogen).

Hydrocracking of the residue.

There are several models of hydrocrackers that have been designed specifically to process residue or vacuum distillation residue.

The output is more than 90% residual (boiler) fuel.

The objective of this process is to remove sulfur as a result of the catalytic reaction of sulfur-containing compounds with hydrogen to form hydrogen sulfide.

Thus, a residue containing no more than 4% sulfur can be converted into heavy fuel oil containing less than 0.3% sulfur.
It is necessary to use hydrocracking units in the overall oil refining scheme.

On the one hand, the hydrocracker is the central point as it helps to establish a balance between the amount of gasoline, diesel fuel and jet fuel.
On the other hand, feed rates and operating modes of catalytic cracking and coking units are no less important.
In addition, alkylation and reforming should also be considered when planning the distribution of hydrocracking products.

In 2012, within the framework of the contract concluded by Izhora Plants OJSC with RN-Tuapse Refinery LLC (part of the Rosneft Oil Company) in 2010, the OMZ Group completed the manufacture and delivered six heavy-duty tank units intended for deep oil refining and obtaining high-quality fuel of Euro-5 standard. The total weight of the equipment was more than 5 thousand tons, while two vessels have unique weight and dimensional characteristics: height - more than 40 meters, diameter - more than 5 meters, weight - about 1,400 tons. Such petrochemical reactors were produced in Russian Federation for the first time.

The vessels were manufactured in accordance with the requirements of the ASME Code and Russian regulatory documents for petrochemical production equipment. The licensor of the project was Chevron Lummus Global (USA), one of the world's largest companies developing the latest technologies for deep processing of hydrocarbons.

Shipment of hydrocracking reactors to Tuapse Refinery became a unique transport operation, since for the first time in the history of Izhora plants, products were shipped to the customer in batches of three petrochemical vessels with a total weight of more than 2,600 tons. All vessels were shipped to the customer by water from the cargo pier of Izhora Plants on the Neva River in the village of Ust-Slavyanka.”

Customer

Rosneft is the leader of the Russian oil industry and one of the largest public oil and gas companies in the world. The main activities of Rosneft are exploration and production of oil and gas, production of petroleum products and petrochemical products, as well as marketing of manufactured products. The company is included in the list of strategic enterprises in Russia.

The geography of Rosneft's activities in the exploration and production sector covers all the main oil and gas provinces of Russia: Western Siberia, Southern and Central Russia, Timan-Pechora, Eastern Siberia, Far East, shelf of the Arctic seas. The company also implements projects in Kazakhstan, Algeria, Venezuela and the UAE.

Rosneft's main competitive advantage is the size and quality of its resource base. The company has 22.8 billion barrels. n. e. proven reserves, which is one of the best indicators among public oil and gas companies in the world.

The total volume of oil refining at the Company's refineries amounted to a record 50.5 million tons (369 million barrels) at the end of 2010 for the Russian refining sector. Rosneft refineries have an advantageous geographical location, which makes it possible to significantly increase the efficiency of supplies of produced petroleum products. Rosneft is currently implementing projects to expand and modernize its refineries in order to improve the balance between production and refining, as well as to increase the output of high-quality products with high added value that meet the most modern environmental standards.

A special place in the development program of the Company’s refining sector is occupied by the project to expand the capacity of the Tuapse Refinery from 5 to 12 million tons (from 37 to 88 million barrels) per year. In fact, we are talking about the construction of a new modern plant on the territory of an existing refinery with a Nelson complexity index of about 8 and a yield of light oil products of 90%. At the same time, automobile fuel produced at the refinery will correspond to classes 4 and 5 (equivalent to Euro-4 and Euro-5). The Tuapse plant has the most advantageous geographical location among Rosneft's refining assets, which determines the high economic efficiency of the project to expand its capacity.

The project is being implemented in two stages. The first stage, which is planned to be completed in 2012, includes the construction of an ELOU-AVT-12 primary oil refining unit with a naphtha hydrotreating section, as well as general plant facilities. The second stage, which is planned to be completed in 2014, includes the construction of a vacuum gas oil hydrocracking and diesel fuel hydrotreating unit, a hydrogen production unit, naphtha isomerization and hydrotreating unit, a catalytic reforming unit, sulfur production unit, and a flexicocking unit.

For more than ten years, JSC Izhora Plants has been the largest machine-building enterprise in Russia producing unique reactor equipment for installations: hydrocracking, hydrotreating, catalytic cracking, etc. In recent years, more than 150 vessels have been designed and manufactured, including those with unique weight and dimensional characteristics.

Technological capabilities

At the Izhora industrial site, a comprehensive (end-to-end) technology for the production of heavy petrochemical reactors from large-sized forged shells made of chromiolybdenum vanadium steel has been developed and implemented - the main material for the manufacture of similar equipment by world leaders.

Izhora plants have the technological capabilities to manufacture petrochemical equipment in accordance with ASME codes and Russian standards with the following parameters:

• Outer diameter, mm: from 500 to 9000
• Length, mm: from 300 to 80000
• Wall thickness, mm: from 4 to 450
• Weight, t: from 0.05 to 1450
• Working pressure, MPa: up to 250
• Operating temperature, 0C: from minus 70 to plus 600

An important competitive advantage of Izhora Plants is the presence of its own high-quality metallurgy at one production site (OMZ-Spetsstal LLC); research center (enterprise TK "OMZ-Izhora"), providing metallurgical support at all stages of production; and a design bureau capable of designing equipment using modern software systems in accordance with the requirements of global licensors.

To ensure high strength of reactors for oil refining, Izhora plants have developed and successfully used a large number of unique welding and surfacing technologies. Only a few enterprises in the world have the technology for welding chrome-molybdenum-vanadium steels of large thickness (more than 200 mm); in Russia, only the Izhora plants. Another unique technology that has been developed and implemented in the production of reactors for oil refining is homogeneous single-layer corrosion-resistant surfacing with a 90 mm wide tape, performed using the electroslag method.

PJSC Orsknefteorgsintez, or Orsky Oil Refinery, is part of the industrial and financial SAFMAR Group of Mikhail Gutseriev. The plant operates in the Orenburg region, supplies its region and surrounding areas with petroleum products - motor fuel, fuel oil and bitumen. For several years now, the company has been undergoing large-scale modernization, as a result of which the plant will remain among the leaders in the oil refining industry for many years.

Currently, the Orsk Refinery has begun a test launch of the most significant of the newly built facilities, the Hydrocracking Complex. By June, construction, installation and commissioning work “idle” and debugging and adjustment of equipment “under load” were completed at this facility. The total investment in the construction of this Complex will amount to more than 43 billion rubles; both own and borrowed funds are used to finance the project.

In the near future, raw materials will be accepted for the installation and debugging of all processes to obtain products will begin. The test mode is necessary to debug the technological regime at all facilities of the Hydrocracking complex, obtain products of appropriate quality, and also, among other things, to confirm the warranty indicators laid down by the licensor Shell Global Solutions International B.V. (Shell)

The adjustment of the regime is carried out by ONOS units with the assistance of contractors during commissioning and in the presence of a representative of the licensor Shell. The main shareholder of ONOS, ForteInvest, plans to complete operation in test mode and bring the facility into commercial operation in July of this year. Thus, despite the difficult economic situation in the country, the Hydrocracking Complex is planned to be built in an extremely short time frame - the first work on the project began in mid-2015, and hydrocracking will reach its design capacity approximately 33 months after the start of the project.

The commissioning of modernization facilities will bring the Orsk Refinery to a new level of refining, allowing it to increase its depth to 87%. The selection of light petroleum products will increase to 74%. As a result of this stage of the Modernization Program, the product line of the enterprise will change: vacuum gas oil will cease to be a commercial product, as it will become a raw material for a hydrocracking unit; The production of aviation kerosene and Euro 5 diesel fuel will significantly increase.

The shareholders of the Orsk Oil Refinery pay great attention to the development of the enterprise for the long term. The global modernization of production, which has been underway since 2012, is of great importance not only for the enterprise, but also for the region, because the plant is one of the city-forming enterprises of Orsk. Currently, about 2.3 thousand people work at the refinery - residents of the city and nearby villages. Production update has great value for the social sphere of the city is the creation of new jobs, an increase in the number of qualified personnel involved in production, and, consequently, increasing the overall standard of living of the workers of the plant and the city.

PJSC "Orsknefteorgsintez"‒ an oil refinery with a capacity of 6 million tons per year. Kit technological processes The plant allows the production of about 30 types of different products. These include class 4 and 5 motor gasoline; RT jet fuel; diesel fuel of summer and winter types of classes 4 and 5; road and construction bitumen; fuel oils. In 2017, the volume of oil refining amounted to 4 million 744 thousand tons.

The Hydrocracking Complex includes a hydrocracking unit, a sulfur production unit with a granulation and loading unit, a chemical water treatment unit, a water recycling unit and nitrogen station No. 2. Construction of the vacuum gas oil hydrocracking complex began in 2015, its launch is scheduled for the summer of 2018.

The processes of processing petroleum fractions in the presence of hydrogen are called hydrogenation. They occur on the surface of hydrogenation catalysts in the presence of hydrogen at high temperatures (250-420 °C) and pressure (from 2.5-3.0 up to 32 MPa). Such processes are used to regulate the hydrocarbon and fractional composition of processed petroleum fractions, purify them from sulfur-, nitrogen- and oxygen-containing compounds, metals and other undesirable impurities, improve the operational (consumer) characteristics of petroleum fuels, oils and petrochemical raw materials. Hydrocracking allows the production of a wide range of petroleum products from virtually any petroleum feedstock by selecting appropriate catalysts and operating conditions, making it the most versatile, efficient and flexible petroleum refining process. The division of hydrogenation processes into hydrocracking and hydrotreating is quite arbitrary based on the properties of the catalysts used, the amount of hydrogen used and the technological parameters of the process (pressure, temperature, etc.).

For example, the following terminology is accepted: “Hydro-treating”, “Hydrorefining” and “Hydrocracking”. Hydrotreating includes processes in which there is no significant change in the molecular structure of the raw material (for example, desulfurization at a pressure of 3-5 MPa). Hydrofining involves processes in which up to 10% of the raw material is subject to change molecular structure(desulfurization - dearomatization - denitrogenization at a pressure of 6-12 MPa). Hydrocracking is a process (high pressure - more than 10 MPa and medium pressure - less than 10 MPa) in which more than 50% of the raw material is subjected to destruction with a decrease in molecular size. In the 80s of the XX century. Hydrofining processes with a conversion of less than 50% were called soft or light hydrocracking, which began to include intermediate processes with hydrodestruction of raw materials from 10 to 50% at pressures both less and more than 10 MPa. The capacity of hydrocracking installations (million tons/year) in the world is approximately 230, and of hydrotreating and hydrofining - 1380, of which in North America - 90 and 420, respectively; in Western Europe - 50 and 320; in Russia and the CIS - 3 and 100.

The history of the development of industrial hydrogenation processes began with the hydrogenation of coal liquefaction products. Even before the Second World War, Germany achieved great success in the production of synthetic gasoline (syntin) through the hydrogenation processing of coal (based on the use of Fischer-Tropsch synthesis), and during the Second World War Germany produced more than 600 thousand tons/year of synthetic liquid fuels, which covered most of the country's consumption. Currently, global production of coal-based artificial liquid fuels is about 4.5 million tons/year. After the widespread industrial introduction of catalytic reforming, which produces excess cheap hydrogen as a by-product, a period of mass distribution of various hydrotreating processes of raw oil fractions (by the way, necessary for reforming processes) and commercial refinery products (gasoline, kerosene, diesel and oil fractions) begins.

Hydrocracking (HC) makes it possible to obtain light petroleum products (gasoline, kerosene, diesel fractions and liquefied gases C3-C4) from almost any petroleum feedstock by selecting appropriate catalysts and technological process conditions. Sometimes the term "hydroconversion" is used as a synonym for the term hydrocracking. The first GK installation was launched in 1959 in the USA. Most GC processes involve the processing of distillate feedstock: heavy atmospheric and vacuum gas oils, catalytic cracking and coking gas oils, as well as deasphalting agents. The resulting products are saturated (saturated) hydrocarbon gases, high-octane gasoline fraction, low-solidification fractions of diesel and jet fuels.

Hydrocracking of raw materials containing significant amounts of compounds based on sulfur, nitrogen, oxygen and other elements is usually carried out in two stages (Fig. 2.22). At the first stage, shallow soft hydrocracking is carried out in the hydrotreating mode to remove unwanted impurities, which are usually catalyst poisons or reduce their activity. The catalysts of this stage are identical to conventional hydrotreating catalysts and contain oxides and sulfides of nickel, cobalt, molybdenum and tungsten on different carriers - active alumina, aluminosilicate or special zeolites. At the second stage, the prepared, purified raw material, containing no more than 0.01% sulfur and no more than 0.0001% nitrogen, undergoes basic hard hydrocracking on catalysts based on palladium or platinum on a carrier - type Y zeolites.

Hydrocracking of heavy gas oil fractions is used to produce gasoline, jet and diesel fuel, as well as to improve the quality of oils, boiler fuel and pyrolysis and catalytic cracking raw materials. Hydrocracking of low-sulfur vacuum distillates into gasoline is carried out in one stage on sulfide catalysts that are resistant to poisoning by heteroorganic compounds at a temperature of 340-420 ° C and a pressure of 10-20 MPa with a gasoline yield of 30-40% and up to 80-90 vol. %. If the raw material contains more than 1.5% sulfur and 0.003-0.015% nitrogen, then a two-stage process is used with hydrotreating of the raw material at the first stage. Hydrocracking in the second stage occurs at a temperature of 290-380 °C and a pressure of 7-10 MPa. The gasoline output reaches 70-120 vol. % for raw materials, the resulting light gasoline up to 190 °C is used as a high-octane component of commercial gasoline, heavy gasoline can be sent for reforming. Hydrocracking of heavy gas oils into middle fractions (jet and diesel fuel) is also carried out in one or two stages.

In the course of gasoline, obtain up to 85% of jet or diesel fuel. For example, the domestic one-stage vacuum gas oil hydrocracking process on a zeolite-containing catalyst of the GK-8 type can produce up to 52% of jet fuel or up to 70% of winter diesel fuel with an aromatic hydrocarbon content of 5-7%. Hydrocracking of vacuum distillates of sulfur oils is carried out in two stages. By including hydrocracking in the technological scheme of a refinery, high flexibility is achieved in the production of its commercial products.

At the same hydrocracking installation, different options for producing gasoline, jet or diesel fuel are possible by changing the technological regime of hydrocracking and the unit for rectifying fractionation of reaction products. For example, the gasoline version produces a gasoline fraction with a yield of up to 51% of raw materials and a diesel fuel fraction of 180-350 °C with a yield of 25% of raw materials. The gasoline fraction is divided into light gasoline C5-C6 with RON = 82 and heavy gasoline Su-Syu with RON = 66 with a sulfur content of up to 0.01%. The Cy-C^ fraction can be sent to catalytic reforming to increase its octane number. The diesel fraction has a cetane number of 50-55, no more than 0.01% sulfur and a pour point of no higher than minus 10 ° C (component of summer diesel fuel).

Unlike catalytic cracking, C3-C4 gases and liquid fractions of hydrocracking contain only saturated stable hydrocarbons and practically do not contain heteroorganic compounds; they are less aromatized than catalytic cracking gas oils. With the jet-fuel option, it is possible to obtain up to 41% of the 120-240 °C fraction, which meets the standard requirements for jet fuel. With the diesel-fuel option, it is possible to produce 47 or 67% of the diesel fuel fraction with a cetane number of about 50.

A promising area of ​​hydrocracking is the processing of oil fractions (vacuum distillates and deasphalted oils). Deep hydrogenation of oil fractions increases their viscosity index from 36 to 85-140 while reducing the sulfur content from 2 to 0.04-0.10%, coking is reduced by almost an order of magnitude and the pour point is reduced. By selecting the technological mode of hydrocracking, it is possible to obtain base oil fractions with a high viscosity index from almost any oil. During hydrocracking of oil fractions, hydroisomerization reactions of normal alkanes (solidifying at higher temperatures) occur, so hydroisomerization lowers the pour point (due to an increase in isoparaffins in oils) and eliminates the need for dewaxing of oils with solvents. Hydroisomerization of kerosene-gas oil fractions on bifunctional aluminum-platinum catalysts or nickel and tungsten sulfides on aluminum oxide makes it possible to obtain diesel fuel with a pour point of up to minus 35 ° C.

Hydrocracking, combining reforming and selective hydrocracking, called selectoforming, increases the octane number of reformates or raffinate (after separation of aromatic hydrocarbons) by 10-15 points at a temperature of about 360 ° C, a pressure of 3 MPa and a hydrogen-containing gas flow rate of 1000 nm3/m3 of raw material on a zeolite-containing catalyst with an input window size of 0.50-0.55 nm with active metals of the platinum group, nickel or with oxides or sulfides of molybdenum and tungsten. By selectively removing normal alkanes from kerosene and diesel fractions, the pour point of jet and diesel fuels is reduced to minus 50-60 °C, and the pour point of oils can be lowered from 6 to minus 40-50 °C.

Hydrodearomatization is the main process for producing high-quality jet fuels from straight-run (with an arene content of 14-35%) and secondary (with an arene content of up to 70%) raw materials. Jet fuel for supersonic aviation, for example T-6, should not contain more than 10 May. % aromatic hydrocarbons. Therefore, upgrading of jet fuel fractions is carried out by hydrotreating in the hydrodearomatization mode. If the raw material has less than 0.2% sulfur and less than 0.001% nitrogen, then hydrocracking is carried out in one stage on a platinum zeolite catalyst at a temperature of 280-340 °C and a pressure of 4 MPa with the degree of removal (conversion) of arenes up to 75-90%.

At higher sulfur and nitrogen contents in the raw material, hydrocracking is carried out in two stages. Recycled raw materials are processed under more stringent conditions at a temperature of 350-400 °C and a pressure of 25-35 MPa. Hydrocracking is a very expensive process (high hydrogen consumption, expensive high-pressure equipment), but it has long been widely used industrially. Its main advantages are the technological flexibility of the process (the ability to produce different target products on one equipment: gasoline, kerosene and diesel fractions from a wide variety of raw materials: from heavy gasoline to residual oil fractions); the yield of jet fuel increases from 2-3 to 15% for oil, and the yield of winter diesel fuel - from 10-15 to 100%; high quality of the resulting products in accordance with modern requirements.

Hydrotreating processes are widely used in oil refining and petrochemical industries. They are used to produce high-octane gasoline, to improve the quality of diesel, jet and boiler fuels and petroleum oils. Hydrotreating removes sulfur, nitrogen, oxygen compounds and metals from oil fractions, reduces the content of aromatic compounds, and removes unsaturated hydrocarbons by converting them into other substances and hydrocarbons. In this case, sulfur, nitrogen and oxygen are hydrogenated almost completely and converted in a hydrogen environment into hydrogen sulfide H2S, ammonia NH3 and water H20, organometallic compounds decompose by 75-95% with the release of free metal, which is sometimes a catalyst poison. For hydrotreating, a variety of catalysts are used that are resistant to poisoning by various poisons. These are oxides and sulfides of expensive metals: nickel Ni, cobalt Co, molybdenum Mo and tungsten W, on aluminum oxide A1203 with other additives. Most hydrotreating processes use aluminum-cobalt-molybdenum (ACM) or aluminum-nickel-molybdenum (ANM) catalysts. ANM catalysts may have a zeolite additive (type G-35). These catalysts are usually manufactured in the form of irregular cylindrical granules with a size of 4 mm and a bulk density of 640-740 kg/m3. When starting up the reactors, the catalysts are sulfided (sulfurization process) with a gas mixture of hydrogen sulfide and hydrogen. ANM and aluminum-cobalt-tungsten (AKV) catalysts are designed for deep hydrotreating of heavy, highly aromatic raw materials, paraffins and oils. Regeneration of catalysts for burning coke from its surface is carried out at a temperature of 530 °C. Hydrotreating processes are usually limited to a temperature of 320-420 °C and a pressure of 2.5-4.0, less often 7-8 MPa. The consumption of hydrogen-containing gas (HCG) varies from 100-600 to 1000 nm3/m3 of raw material depending on the type of raw material, the perfection of the catalyst and process parameters.

Hydrotreating of gasoline fractions is used mainly in their preparation for catalytic reforming. Hydrotreating temperature 320-360 °C, pressure 3-5 MPa, VSG consumption 200-500 nm3/m3 of raw material. When purifying gasoline fractions of catalytic and thermal cracking, the consumption of VSG is more than 400-600 nm3/m3 of raw materials.

Hydrotreating of kerosene fractions is carried out on a more active catalyst at a pressure of up to 7 MPa to reduce the sulfur content to less than 0.1% and aromatic hydrocarbons to 10-18 May. %.

More than 80-90% of fractions are subjected to hydrotreating of diesel fractions at a temperature of 350-400 °C and a pressure of 3-4 MPa with a VSG consumption of 300-600 nm3/m3 of raw materials on AKM catalysts, the degree of desulfurization reaches 85-95% or more. To increase the cetane number of diesel fractions originating from the reaction products of catalytic and thermal cracking, part of the aromatic hydrocarbons is removed on active catalysts at a temperature of about 400 °C and a pressure of up to 10 MPa.

Hydrotreating of vacuum distillates (gas oils) for use as raw materials for catalytic cracking, hydrocracking and coking (to produce low-sulfur coke) is carried out at a temperature of 360-410 °C and a pressure of 4-5 MPa. In this case, 90-94% desulfurization is achieved, nitrogen content is reduced by 20-25%, metals - by 75-85, arenes - by 10-12, coking ability - by 65-70%.

Hydrotreating of oils and paraffins. Hydrotreating of base oils is more advanced than classical sulfuric acid cleaning with contact post-treatment of oils. Hydrotreating of oils is carried out on AKM and ANM catalysts at a temperature of 300-325 ° C and a pressure of 4 MPa. Hydrotreating of oils on an aluminum-molybdenum catalyst with promoters makes it possible to reduce the temperature to 225-250 °C and the pressure to 2.7-3.0 MPa. Hydrotreating of paraffins, ceresins and petrolatums is carried out to reduce the content of sulfur, resinous compounds, unsaturated hydrocarbons, to improve color and stability (as for oils). The process using AKM and ANM catalysts is similar to the hydrotreating of oils. Aluminum-chromium-molybdenum and nickel-tungsten-iron sulfided catalysts have also been used.

Hydrotreating of oil residues. It is usually obtained from oil on May 45-55. % of residues (fuel oils and tars) containing large quantities of sulfur-, nitrogen- and organometallic compounds, resins, asphaltenes and ash. To involve these residues in catalytic processing, purification of oil residues is necessary. Hydrotreating oil residues is sometimes called hydrodesulfurization, although not only sulfur is removed, but also metals and other undesirable compounds. Hydrodesulfurization of fuel oil is carried out at a temperature of 370-430 °C and a pressure of 10-15 MPa on AKM catalysts. The yield of fuel oil with a sulfur content of up to 0.3% is 97-98%. At the same time, nitrogen, resins, asphaltenes are removed and partial upgrading of the raw materials occurs. Hydrotreating of tars is a more complex task than hydrotreating of fuel oils, since significant demetallization and deasphalting of tars must be achieved either preliminary or directly during the hydrodesulfurization process. Special requirements are placed on catalysts, since conventional catalysts quickly lose activity due to large deposits of coke and metals. If coke is burned out during regeneration, then some metals (nickel, vanadium, etc.) poison the catalysts and their activity is usually not restored during oxidative regeneration. Therefore, hydrodemetallization of residues should precede hydrotreating, which makes it possible to reduce the consumption of hydrotreating catalysts by 3-5 times.

Fixed-bed hydrocracking and hydrotreating reactors are widely used and are largely similar in design to catalytic reforming reactors. The reactor is a cylindrical vertical apparatus with spherical bottoms with a diameter of 2-3 to 5 m and a height of 10-24 and even 40 m. At high process pressures, the wall thickness reaches 120-250 mm. Typically a single fixed bed of catalyst is used. But sometimes due to the allocation large quantity heat during exothermic hydrocracking reactions, it becomes necessary to cool the internal reactor space by introducing a coolant into each zone. To do this, the reactor volume is sectioned into 2-5 zones (sections), each of which has a supporting grate for pouring the catalyst, side fittings for loading and unloading the catalyst, distribution devices for the vapor-gas mixture, as well as fittings and distributors for introducing the coolant - cold circulating gas to remove the heat of reaction and regulate the required temperature along the height of the reactor. The catalyst layer of a single-section reactor has a height of up to 3-5 m or more, and in multi-section reactors - up to 5-7 m or more. The raw material enters the apparatus through the upper fitting, and the reaction products leave the reactor through the lower fitting, passing through special packages of mesh and porcelain balls to retain the catalyst. Filtering devices (a system of perforated nozzles and metal meshes) are installed at the top of the reactor to capture corrosion products from the steam-gas feedstock. For high-pressure devices (10-32 MPa), special requirements are imposed on the design of the housing and internal devices.

Regeneration of catalysts is carried out by oxidative burning of coke. Regeneration is in many ways similar to the regeneration of catalytic reforming catalysts, but it also has its own characteristics. After disconnecting the reactor from the raw material, reduce the pressure and switch to circulation using VSG. For heavy types of raw materials, wash the catalyst with solvents, gasoline or diesel fuel at a temperature of 200-300 °C. Then the VSG is replaced with an inert gas (water vapor). In the case of gas-air regeneration, the process is similar to the regeneration of reforming catalysts. During steam-air regeneration, the system is first purged with inert gas until the residual hydrogen content is not higher than 0.2 vol. %, then the inert gas is replaced with water vapor and discharged into the chimney of a tube furnace under conditions that exclude condensation of water vapor (temperature at the furnace outlet 300-350 °C, pressure in the reactor about 0.3 MPa). Next, the catalyst is heated to a temperature of 370-420 °C by burning coke at an oxygen concentration in the mixture of no more than 0.1 vol. % Increasing air flow at an oxygen concentration of up to 1.0-1.5 vol. % the catalyst temperature rises to 500-520 °C (but not higher than 550 °C). By monitoring the decrease in CO2 concentration in the flue gases, a decision is made to stop regeneration, which is completed when the oxygen content in the flue gases becomes close to the oxygen content in the mixture at the inlet to the reactor. Steam-air regeneration is simpler and occurs at low pressures no higher than 0.3 MPa using water steam from the plant network. Water vapor is mixed with air and fed into the reactor through a tube furnace; flue gases are discharged into the chimney of the tube furnace.

Industrial hydrotreating and hydrocracking plants. Typical installations of the period 1956-1965. for the hydrotreating of diesel fuels were two-stage units with a capacity of 0.9 million tons of raw materials/year, type L-24-6; the hydrotreating of gasoline fractions was carried out in separate units with a capacity of 0.3 million tons of raw materials/year. In 1965-1970 Hydrotreating units for various distillate fractions with a capacity of 1.2 million tons/year, type L-24-7, LG-24-7, LCh-24-7, were introduced. Gasoline fractions were purified in blocks of combined reforming units with a capacity of 0.3 and 0.6 million tons/year. Kerosene fractions were purified in diesel fuel hydrotreating units, previously retrofitted for these purposes. Since 1970, enlarged installations have been widely introduced various types and purposes - both stand-alone type J1-24-9 and J14-24-2000, and as part of combined JlK-bu plants (section 300) with a capacity of 1 to 2 million tons/year. The technological schemes for hydrotreating jet and diesel fuels are in many ways similar to the scheme for the hydrotreating unit for gasoline fractions - the raw material of catalytic reforming units.

Hydrodesulfurization plants for boiler fuels, fuel oils and tars of type 68-6 are operated in three-phase fluidized bed reactors. The installation capacity, depending on the raw material, can vary from 1.25 million tons/year of sulfurous tar to 2.5 million tons/year of sulfur fuel oil. The process pressure is 15 MPa, temperature is 360-390 °C, VSG consumption is 1000 nm3/m3 of raw material. The AKM catalyst is used in the form of extruded particles with a diameter of 0.8 mm and a height of 3-4 mm. The catalyst in the reactor is not regenerated, but is removed in small quantities and replaced with a fresh portion once every 2 days. The reactor vessel is multilayer with a wall thickness of 250 mm, the reactor weight is about 800 tons.

Here are the names of the hydrocracking and hydrotreating processes of foreign companies:

Modern hydrogenation processes of the Union Oil company: the Unicracking/DP process, which includes two sequentially operating hydrotreating and selective hydrodewaxing reactors for processing raw materials - diesel fractions and vacuum gas oils to produce low-solidifying diesel fuel (pour point sometimes down to minus 80 ° C ) containing 0.002% sulfur, less than 10% aromatics on NS-K and NS-80 catalysts with a feed conversion of 20%; Unicracking process with partial conversion of 80% of raw materials - vacuum gas oils to produce diesel fuel containing 0.02% sulfur, less than 10% aromatics on the NS-K pre-hydrotreating catalyst and an improved zeolite catalyst DHC-32, the process can also be used in work Refinery with a gasoline option in the scheme of preparing raw materials for catalytic cracking; Unicracking process with a complete 100% conversion of raw materials - vacuum gas oils with an end boiling point of 550 °C to produce environmentally friendly jet and diesel fuels containing 0.02% sulfur, 4 and 9% aromatics on an amorphous spherical catalyst DHC-8 (catalyst operating cycle 2-3 years), ensuring maximum yield of high-quality distillates, especially diesel fuels; the “Unisar” process with a conversion of 10% on the new AS-250 catalyst for effectively reducing the aromatic content up to 15% in jet and diesel fuels (hydrodearomatization), especially recommended for the production of diesel fuels from difficult to refine raw materials, such as light gas oils from catalytic cracking and coking; AN-Unibon process from the UOP company for hydrotreating and hydrofining of diesel fuels of the AR-10 and AR-10/2 type (two stages) to a sulfur content of 0.01 wt. % and aromatics up to 10 vol. % with a cetane number of 53 at process pressures of 12.7 and 8.5 MPa (two stages).

For reformulation (controlled hydroprocessing) of oil residues in world practice, in particular, the following processes are used: hydrotreating - the RCD Unionfining process of the Union Oil company to reduce the content of sulfur, nitrogen, asphaltenes, metals and reduce the coking properties of residual raw materials (vacuum residues and asphalts in deasphalting processes) in order to obtain high-quality low-sulfur boiler fuel or for further processing during hydrocracking, coking, catalytic cracking of residual raw materials; hydrotreating - the Chevron RDS/VRDS process is similar in purpose to the previous process, while raw materials are processed with a viscosity at 100 ° C of up to 6000 mm2/s with a metal content of up to 0.5 g/kg (for deep hydrodemetallization of raw materials), On-the-fly catalyst replacement technology is used, which makes it possible to unload the catalyst from the reactor and replace it with a fresh one while maintaining normal operation in parallel reactors, which makes it possible to process very heavy raw materials with an installation run of more than a year; hydrovisbreaking - the “Aqvaconversion” process from the companies “Intevep SA”, “UOP”, “Foster Wheeler” provides a significant reduction in the viscosity (more compared to visbreaking) of heavy boiler fuels with a higher conversion of raw materials, and also allows you to obtain hydrogen from water under basic conditions process by introducing into the raw material, together with water (steam), a composition of two catalysts based on base metals; hydrocracking - the “LC-Fining” process from the companies “ABB Lummus”, “Oxy Research”, “British Petroleum” for desulfurization, demetallization, reduction of coking and conversion of atmospheric and vacuum residues with a conversion of raw materials of 40-77%, degree of desulfurization of 60-90% , complete demetallization of 50-98% and a reduction in coking by 35-80%, while in the reactor the catalyst is maintained in suspension by an ascending flow of raw material liquid (for example, tar) mixed with hydrogen; hydrocracking - the “H-Oil” process (Fig. 2.23) for the hydroprocessing of residual and heavy raw materials, such as tar, in two or three reactors with a suspended catalyst bed; during the process, the catalyst can be added and removed from the reactor, maintaining its activity and degree of conversion tar from 30 to 80%; hydrorefining of residual raw materials - Shell's Nusop process uses all bunker reactors (one or more depending on the metal content of the raw material) with a moving catalyst bed to constantly update the catalyst in the reactors (0.5-2.0% of the total catalyst per day. ), in this case, two reactors with a fixed bed of catalyst can also be used after bunker reactors; if necessary, a hydrocracking reactor is included in the scheme to increase the conversion of raw materials for process pressures of 10-20 MPa and temperatures of 370-420 ° C (Fig. 2.24).

Major achievement recent years in the technology for the production of sulfur-free low-solidifying jet and diesel fuels and high-index base oils is the creation of hydrogenation processes called “Isocracking” by Chevron companies together with ABB.

Lummus”, which carry out hydrocracking with a conversion of 40-60% (oil), 50-60, 70-80 or 100% (diesel) of vacuum gas oils 360-550 °C or heavy vacuum gas oils 420-570 °C, reduce the sulfur content to 0.01-0.001% (diesel fuel) or up to 0.005% (oil), bring the aromatic content to 1-10% depending on the brand of catalyst (amorphous-zeolite or zeolite) ICR-117, 120, 139, 209 and etc., the number of reaction stages (one or two), pressure in the reactors (less than 10 or more than 10 MPa), the use of recycle systems, and also carries out selective hydroisomerization of n-paraffins. This process, in a mode with hydroisodewaxing, makes it possible to process heavy vacuum gas oils with maximum yields of high-index lubricating oils (IV = 110-130) while simultaneously producing low-solidifying diesel fuels. Unlike hydrodewaxing, in which n-paraffins are removed, in this process they are hydroisomerized. A distinctive modification in recent years of hydrocracking (with a high level of conversion) is the use of additional technological solutions for the removal of heavy polynuclear aromatics (HMA) from the recycle liquid (hot separation, selective adsorption of TMA, etc.) in hydrocracking systems with recycle. TMA (aromatics with 11 or more rings) formed during operation is undesirable in commercial products; it reduces the efficiency of the catalyst, precipitates on the colder surfaces of equipment and pipelines, and disrupts the functioning of the installation.

Oil. A new complex for deep oil refining using hydrocracking technology has appeared in Russia. But it is too early to say that oil companies are moving from primary to deep refining.

The new complex includes a hydrocracking unit, which is a fairly modern, but expensive technology. "F" told us more about it. Alexander Yakovlev, director of the EPN-Consulting company: “Previously, in Russia, a hydrocracking unit operated only in Ufa at Ufaneftekhim. But it worked poorly - it was constantly reconstructed. Now a second unit has begun operating in Perm using a new, more modern technology, which allows you to increase the production of light petroleum products. However, this process is very expensive, so now catalytic cracking is mainly used. The construction of a plant for processing 2 million tons of oil per year costs about $1.5-2 billion, the same as the cost of an oil refinery for 5-6 million tons. “The decision about what to build depends on the company’s starting capabilities. If it has little refining capacity, then it builds a new refinery, but if it has enough, it can afford modernization.”

Dmitry Lukashov, an analyst at Aton Investment Group, told F. that hydrocracking is not considered a super technology abroad, but for Russia it is quite progressive. When using it, the yield of light petroleum products increases, but on the scale of Lukoil the changes will not be serious. And the complex is expensive. With this money it was possible to build a new processing plant. However, Lukoil is not the only company that has decided to use hydrocracking. Rosneft plans to use this technology at the Komsomolsk Refinery since 2005, and Surgutneftegaz plans to install it at the Kirishi Refinery by 2008.

According to Lukoil's calculations, the new complex will increase the production of motor fuel by more than 1 million tons per year, while the quality of petroleum products will meet European standards. “However, low-processed products are in great demand abroad,” Anastasia Andronova, an analyst at CenterInvest Securities, told F. short term it would be more profitable to build a primary oil processing facility. In this case, Lukoil is focusing on the future, but in 3-4 years this technology will be cheaper. It is unlikely that hydrocracking will begin to become very popular now, since there is a lack of refining capacity in Russia."

According to Lukoil, investments in the complex amounted to 10.8 billion rubles. “According to our calculations, additional revenues from the project will amount to more than 4 billion rubles per year,” Dmitry Mangilev, an analyst at Prospekt Investment Company, told F. “Thus, we can talk about a fairly quick payback for the project for the company. On the other hand, the construction of a new refinery, designed to process 2 million tons of oil per year, could cost Lukoil about $300-350 million, which is approximately the same level as a new installation. Therefore, it is doubtful whether other domestic companies will invest in it. similar projects or will prefer the construction of new capacities, especially since large companies besides Lukoil are more focused on the export of crude oil.”

Thus, new oil refining technologies are taking hold in Russia, but now it is difficult to say how widely oil companies will use them. Large companies for now they prefer to export primary oil. Moreover, for some, the problem of lack of refining capacity is acute and, first of all, they will try to solve it by building refineries. And only then will they think about modernizing and improving product quality. l