RU2848091C2 - Method of producing high-melting electrode pitch of grade "b" from coal or pyrolysis resin or fractions thereof (medium-temperature pitch) and apparatus for this technological process using said method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to coke chemistry and is involved in supplying many branches of the national economy with carbonaceous material. Method of producing high-melting electrode pitch of grade "B" consists of steps of receiving coal or pyrolysis resin, preparation of raw material for processing – removal of water and desalination, heating of raw material, primary rectification of raw material, vacuum rectification of stripped resin, converting medium-temperature coal tar in column-type thermal oxidation and polymerisation reactors to coal tar of the required quality. Also includes steps of receiving electrode pitch of "B" grade and feeding it to belt cooler-granulator, Peck cooling at belt-type cooler-granulator, peck distillate absorption from oxidation gas vapours produced in reactors of thermal oxidation and polymerization of production of B-type electrode peck. Block of polymerisation reactors R-101 and thermal oxidation reactors R-102 employs isothermal reactors with built-in heat exchange and mixing devices. Both reactors R-101 and R-102 can be used as oxidation reactors with air supply as oxidizing agent to each of them with possibility of obtaining specified properties of produced high-melting electrode pitch. There is a unit for washing coal or pyrolysis resin and filtration thereof before feeding for primary rectification. There is a rectification unit intended for separation of resin stream into commercial products, consisting of two columns with heaters, circulation and flushing irrigation systems, air coolers with rotation controllers and factory cover louvers. Hydro-ejector system is used to create vacuum, which consists of hydro-ejector and separator-divider into lines of vapours and liquid after rectification column. Nitrogen breathing system is used, consisting of nitrogen supply system to polymerisation and thermal oxidation reactors and nitrogen removal to maintain pressure in process apparatus with output of excess nitrogen-hydrocarbon medium for recycling in afterburner. Absorption fraction 230–270 °C is used as absorbent for absorption of pitch distillate and its separation from oxidation gases is one of commercial products of the plant. Hydro-circulation system is used for evacuation and nitrogen respiration to rule out hydrocarbon emissions. An apparatus for realizing the method is also disclosed.

EFFECT: group of inventions provides optimal conditions for producing high-temperature petroleum pitch binder, provides additional high-quality dehydration and removal of salts and acids from resin, which considerably reduces corrosion of process equipment and pipelines, and also prevents the ingress of corrosion products into the commercial product, which ensures prolonged trouble-free operation of the process equipment and commercial quality of the obtained product.

7 cl, 3 dwg, 11 tbl, 4 ex

Description

The significant amount of coal tar produced and processed determines the leading role of coke chemistry in providing many sectors of the national economy with carbon raw materials.

It should be taken into account that in such important branches of industry as ferrous metallurgy (steelmaking and blast furnace production), non-ferrous metallurgy (aluminum production), and the chemical industry, not only is the demand for carbon materials increasing, but the requirements for their quality and properties are also increasing.

Coke is a solid combustible residue formed when organic matter is heated in the absence of air. Coke's properties depend on the feedstock and coking conditions.

Pitch coke is used mainly in the production of electrodes, graphite-carbon mixtures, etc.

The feedstock for the production of pitch coke is high-temperature pitch.

The starting materials for the production of high-temperature pitch and pitch distillates are medium-temperature pitch and coke resin formed during the coking of high-temperature pitch.

The yield of high-temperature pitch reaches 87-89 wt.%. The product quality is characterized by the following data: softening point of 140-150°C, yield of substances insoluble in toluene of 45-50 wt.%, yield of volatile substances of 49-52 wt.%.

The yield of pitch distillates is 10-13% by weight. High-temperature pitch is the feedstock for producing pitch coke.

To obtain high-temperature pitch by the air method, reactor cubes with a diameter of 3000 mm and a working capacity of 27 ^m3 are used.

The still is heated by blast furnace or coke oven gas. To capture droplets of pitch fractions carried away from the still reactor by the exhaust air, an 800 mm diameter, insulated steel baffle plate is used.

Below are listed industrial schemes and technological modes for the production of high-melting (high-temperature) pitch.

In industrial practice, continuous, periodic and semi-continuous installations have found application.

The principle of obtaining high-melting pitch according to the first type of scheme is based on the continuous distillation of medium-temperature pitch by continuously feeding it and superheated steam into the still and continuously delivering high-melting pitch (p. 68 in the book by Stepanenko M.A., Bron Ya.A., Kulakov N.K. Production of pitch coke. X., 1964, 310 p.).

The operation of the plant proceeds according to the following scheme: from the evaporator of the tar distillation shop, the pitch is continuously sent by gravity or by a pump from an intermediate collector to the still to obtain high-melting pitch.

At the same time, superheated steam is fed into the still through a bubbler. The steam is superheated in a coil placed in the tubular furnace of the tar distillation unit or in a separate superheater.

High-melting pitch from the cube enters the pitch receiver under pressure maintained in the cube, and from there - into the pitch receivers of the pitch coke ovens or onto a granulation conveyor for dispatch in solid form to the consumer.

Pitch oil vapors and water vapor from the still enter the condenser - refrigerator, where they condense and cool.

From the refrigerator, the distillates flow into a separator, where they are separated from the water. The water is sent to the sewer, and the distillates to a receiver.

The main indicators of the technological regime are the consumption of superheated steam and the heating temperature of the pitch in the cube.

By increasing the specific steam consumption, high-melting pitch can be obtained at a lower heating temperature of the pitch in the cube.

A column can also be used as the main apparatus in the pitch distillation process.

When working in batch-type plants, a certain amount of medium-temperature pitch is loaded into the cube, which is gradually treated with superheated water steam until the softening temperature rises to 150°C.

The pitch from the tar distillation still with a softening temperature of 70-75°C flows by gravity into the pitch receiver.

The pitch is squeezed out of the pitch receiver using steam under a pressure of 1.5-2.0 atm or pumped into a vertical cube.

After the pitch is loaded into the cube, steam superheated to 350°C is immediately introduced. The steam is superheated in a superheater.

Steam is fed into the still through a bubbler located at the bottom of the still. The still is heated with coke oven gas.

Superheated steam is fed into the still until the pitch reaches the desired softening temperature (135-150°C). Water vapor and pitch distillates from the still enter the condenser-cooler, where they condense and cool to 50°C. The liquid obtained in the condenser-cooler enters the pitch distillate receiver.

The entire system (still, condenser, refrigerator, and pitch distillate receiver) is under vacuum, created by a vacuum pump. Uncondensed gases from the pitch distillate receiver enter the vacuum tank, and from there are released into the atmosphere via the vacuum pump.

The pitch from the cube is squeezed into the pitch receiver using superheated steam.

Technological mode: steam superheat temperature - 340-360°C; flue gas temperature at the superheater pass - 680-750°C; pitch temperature in the cube, °C: at the beginning of the operation - 250-280; maximum (at the end of the operation) - 380; water temperature in the refrigerator, °C - 50; vacuum value on the lantern, mm Hg - 330; steam consumption, % of the loaded pitch - 20.

Intensive distillation of pitch occurs starting at a heating temperature of 350-360°C. During this period, the pitch's softening temperature rises significantly.

The total duration of one operation for obtaining high-melting pitch consists of the following durations of individual operations:

Loading medium pitch into the still - 0.5 hour; heating the pitch to a temperature of 350-360°C - 9 hours; intensive distillation period - 5 hours; dispensing high-melting pitch from the still - 0.5 hour; total duration - 15 hours.

Pitch produced in a batch plant differs significantly in terms of the yield of insoluble and volatile substances from pitch produced by air treatment. The yield of insoluble substances in high-melting pitch produced by steam distillation is higher than in pitch produced by air treatment.

One of the plants operating on a semi-continuous basis is described below. Pitch with a softening point of 60°C is produced continuously in a still.

From the still, the pitch is continuously pumped into a second still, where a temperature of 390°C is maintained. The stills operate under a vacuum of 250 mmHg. The stills are heated by burning pulverized pitch, which has a softening point of 150°C.

At the bottom of the cubes there are two perforated pipes through which superheated steam is supplied.

The steam is superheated in coils installed in the cubes' flues. Additional coolers are installed to condense the water vapor.

Part of the pitch with a softening temperature of 150°C is periodically lowered from the cube so that the level of the pitch remaining in the cube is above the fire tubes (the cube heating is not turned off).

Stills for producing high-melting pitch have been in operation for approximately five years. A method for producing high-melting pitch using flue gases was implemented at the Espenhain plant in Germany for lignite pitch.

Pitch with a softening temperature of 60°C, obtained in a tubular installation, is pumped into batch-type stills.

The cubes, each with a capacity of 30 tons, are heated by coke oven gas. They are fed with inert gases obtained by burning coke oven gas in a special apparatus.

To burn the gas, flue gases from the flue gas duct are fed in instead of air; thus, the inert gases contain almost no oxygen or carbon monoxide.

The coke oven gas combustion apparatus is a cylinder with a refractory lining that acts as a contact mass.

The distillation process in a stream of inert gases is carried out under a vacuum reaching an absolute pressure of 110 mm Hg.

Pitch distillate vapors from the still enter a coil condenser, where they condense at 60°C. Uncondensed inert gases enter the washer and then exit into the atmosphere.

After the distillation process is complete, the pitch is pressed out of the still by gas through a pitch pipeline with a steam jacket into special stills, in which the pitch is maintained in a liquid state at a temperature of 320°C.

The cubes serve as storage facilities for high-melting pitch; from them, the pitch is pumped into pitch-coke furnaces (p. 34 in the book by M.S. Litvinenko, “Chemical Products of Coking.” K., Tekhnika, 1974. 265 p.).

The essence of the method developed at UKHIN (Ukrainian State Research Coal Chemical Institute) lies in the additional heat treatment of pitch with a softening temperature of about 60°C, obtained directly in a continuous tar distillation unit or by diluting medium-temperature pitch with heavy fractions of resin.

During the heat treatment process, as a result of condensation and polymerization reactions, as well as partial pyrolysis followed by condensation, polycondensation products accumulate in the pitch, which affects its group composition and physicochemical properties.

At the same time, during the long-term heating process, the volatile components of the resin are removed.

To intensify the process and obtain pitch with a given softening temperature, heat treatment is combined with the dehydrating effect of atmospheric oxygen.

Due to the exothermic nature of the polycondensation reaction, the temperature of the liquid phase is maintained at the required level.

In addition, the supply of air promotes mixing of the contents in the reactor cube, maintaining possible oxidation products in a suspended state, and therefore, their better removal.

The feedstock pitch is continuously fed from the second stage evaporator of the Shubchaty resin processing unit into the first of two series-connected reactor cubes:

- The pitch is transferred from the second cube to the finished product warehouse, where it is stored, loaded as a liquid into thermal tanks, or cooled to produce solid anhydrous pitch. Air is supplied to the second cube by a compressor;

- exhaust air from reactor cubes and emissions from pitch collectors enter the scrubber;

- exhaust air, distillates and reaction products are cooled in condenser-refrigerators for preliminary cleaning by washing with absorption oil, and then sent to a catalytic cleaning unit for organic matter.

As the absorption oil becomes saturated and its absorption capacity decreases, it is pumped to an oil storage facility or to the unit’s collection tank.

Obtaining electrode pitch.

The raw materials used to produce electrode pitch are pitch resins, medium-temperature pitch obtained through rectification, and pitch distillates.

The above products are subjected to oxidation with atmospheric oxygen or an oxygen-air mixture with an oxygen content in the mixture higher than 21% by volume (usually up to 35%).

Thermal oxidation takes place in reactors with a volume of 50 ^m3 at a temperature of 280-360°C, into which the raw material flow (pitch) is fed counter-currently - fed to the top of the reactor, and air is fed through a mother liquor - distributor to the bottom of the reactor.

All domestic installations for producing electrode pitch are built according to the standard Giprokoks design.

Improvement of the technology of the units put into operation was carried out as a result of experience gained during operation.

Changes and refinements to the oxidation process affected reactor layout, distillate and pitch resin processing modes, and exhaust air cooling and purification. Some plants began using air with added oxygen as an oxidizer.

Thus, at an oxygen concentration of 35% vol., air consumption is reduced by half and the efficiency of the process for producing high-quality pitch is doubled.

In fact, the process of obtaining oxidized pitch consists of distillation of the lightest components of the raw materials, polycondensation and polymerization of the products included in the medium-temperature pitch, the formation of new compaction products based on individual compounds, and the destruction of thermally unstable compounds and structures.

The primary process in producing thermally oxidized pitch is dehydropolycondensation, with copolycondensation and copolymerization occurring in parallel. The individual compounds undergo polycondensation and polymerization.

Hydrocarbons are oxidized simultaneously in two directions:

Based on the experience of industrial installations and the analysis of their operation, the most acceptable technology is the use of a vertical column apparatus equipped with a quenching section that organizes the direction of movement of liquid and gas flows.

The above industrial installations for producing pitch, including electrode pitch, are continuously being improved, which is reflected in the patent literature.

A known method for producing petroleum pitch is by thermal polycondensation of petroleum feedstock (Belgian Patent No. 893465, class C10C 3/02, C10C 3/04, published on September 12, 1982), in particular pyrolysis resin, under pressure of up to 15 atm at 290-420°C (preferably 300-410°C) for 10 min. to 6 hours, followed by distillation of low-molecular products, wherein the temperature difference between the hot lower part of the reactor and the colder upper part is from 20 to 200°C and holding in the second reactor at a temperature of 290-420°C in the presence of water vapor for 5 min. to 2 hours. Steam is consumed in an amount of 0.3 to 3.0 ^m3 /hour per 1 ^m3 of the reaction mass.

The disadvantages of the known method are the complexity of the process, in particular maintaining the temperature difference, the relatively low yield of fiber-forming pitch and its low quality.

A known method for producing pitch involves mixing coal tar pitch with an anthracene fraction and heat treating the mixture. The anthracene fraction is first heat treated at 250-300°C for 10-13 hours in the presence of air. The resulting fraction is mixed with pitch in a pitch:fraction ratio of 2:1 to 9:1, and the mixture is heat treated in the presence of air (USSR A.S. No. 679615, C10C 3/04. Bulletin No. 30, 1979).

The disadvantage of the known method is the discrepancy between the softening temperature of the resulting pitch, as well as the duration and complexity of the process.

A method is known for producing petroleum fiber-forming pitch (RU Patent No. 2062285, cl. C10C 1/16, published on 20.06.1996, Bulletin No. 17, 1996) by thermal polycondensation of heavy pyrolysis resin in a flow reactor of a coil type at elevated pressure and a temperature of 330-400 ° C, distillation of low-molecular reaction products and holding the resulting product at a temperature of 300-330 ° C in the presence of superheated water vapor as a non-oxidizing agent, wherein thermal polycondensation is carried out at a pressure of 30-50 atm and a feed volumetric feed rate of 0.5-2.0 l / h, and distillation is carried out using two separators with continuous supply of a non-oxidizing agent at a rate of 375-1000 l / h for 10-25 hours. Thermal polycondensation of heavy pyrolysis resin is carried out in a continuous unit. Feedstock is continuously pumped from a heated vessel through a pipeline into a coil-type reactor with an ascending product flow, where thermal polycondensation occurs under pressure. After passing through the reaction zone, the reaction products enter two alternately operating separators, where low-molecular-weight products are distilled off in the presence of superheated water vapor or nitrogen. From the top of the separator, the distillate with gaseous products passes through a condenser-cooler into a gas separator, where, after separation, the gases are released into the atmosphere, and the liquid products are collected in a special container. After a certain portion of the first separator is filled, the reaction products from the reactor are sent to the second separator. In the first separator, an additional holding time occurs to remove low-molecular-weight and volatile products and bring the pitch to the required parameters, after which the pitch is discharged through the bottom of the separator into a pitch receiver. Considering that the density of heavy pyrolysis resin is 1.01-1.10 kg/l, and that of superheated steam is 0.1 kg/l, the flow rate of superheated steam into the separator is 200-500 liters per 1 kg of feedstock or 20-50 kg per 1 kg of feedstock. This method increases productivity due to the continuous process and ease of implementation; the yield of fiber-forming pitch is 22.8-26.3 wt%.

The disadvantages of this method include high consumption of superheated steam, low yield of fiber-forming pitch due to insufficient passage of the reaction mixture through the coil reactor at elevated pressure and temperature, and the complexity of the process due to the need to maintain high pressure. Reducing the pressure in the flow reactor below 30 atm leads to coking of the equipment.

A method for producing petroleum isotropic fiber-forming pitch is known (RU Patent No. 2065470, class C10C 1/16, published on August 20, 1996, Bulletin No. 3), which includes thermal polycondensation of petroleum feedstock at elevated pressure in a flow reactor, distillation of low-molecular reaction products in the presence of a non-oxidizing agent. Moreover, the initial pyrolysis resin is first subjected to ultrasonic treatment in the presence of surface-active substances (SAS), then thermal polycondensation in a flow-type reactor at 20-50 atm and further distillation of low-molecular reaction products in a separator with the supply of a non-oxidizing agent at a rate of 375-10,000 l/hour at 300-360°C. A mixture of polyethylene glycol with an average molecular weight of 400 and polyethylene glycol adipate in a weight ratio of 60:40-80:20 is used as a surfactant, used at a rate of 0.1-0.5% of the feedstock weight. Ultrasonic treatment ensures optimal dispersion of the surfactant in the initial pyrolysis resin. This method improves pitch quality and productivity due to the continuous nature of the process.

The disadvantages of the known method are the use of surfactants, an insufficiently high yield of fiber-forming pitch due to the insufficient residence time of the reaction mass in the reaction zone due to the fact that the thermal polycondensation stage is carried out at elevated pressure only in a flow-through coil reactor.

A known method for producing pitch—a binder for electrode materials—involves treating medium-temperature pitch and a coal tar fraction with air at elevated temperatures. The pitch and coal tar fraction are mixed in a pitch:fraction ratio of (9.9:0.1) to (9.1:0.9) and, after mixing, treated with air at a temperature of 280-350°C. Anthracene and/or absorbent fraction are used as the coal tar fraction (RU Patent No. 2119522, C10C 3/04, published 1998).

The disadvantages of this method are that the process is carried out in several stages (mixing, melting, heat treatment and oxidation), i.e. the duration and complexity of the process, as well as its applicability to resins with a significant degree of pyrolysis.

The invention (Patent of the Russian Federation No. 2269565, 2004, class C10C 3/04, published on 10.02.2006, Bulletin No. 4) relates to the field of metallurgical and coke-chemical industries, in particular to a method for producing coal tar pitch used for the preparation of graphitized products and anode mass.

The essence: a method for producing pitch involves treating medium-temperature pitch with air at elevated temperature and simultaneously supplying heated air to a temperature of 120-250°C in an amount of 1-10 ^m3 /ton of pitch with the addition of a coal tar fraction in an amount of 5-30% by weight of the pitch. The technical result: improving the quality of the pitch by reducing its volatile content and increasing the α-fraction content under operating process equipment conditions.

A method similar to the proposed method in terms of technical result is the method for producing low-melting petroleum binder and fiber-forming pitch (RU Patent No. 2477744, 2011, class C10C 1/16, published on March 20, 2013, Bulletin No. 8) by thermal polycondensation of heavy pyrolysis resin purified from low-boiling and non-melting components at elevated pressure and a temperature of 330-400°C, distilling off low-molecular reaction products and holding the resulting product at an elevated temperature in the presence of superheated water vapor as a non-oxidizing agent.

The reaction mass is in the reaction zone for a specified time by recirculating it at a pressure of 10-25 atm, then part of the reaction mass is sent to the reaction separator for distillation of low-molecular reaction products at a flow rate of superheated water vapor in the amount of 0.02-0.04 kg/h per kg of TSP and holding at a temperature of 340-380 °C for 3-10 hours to obtain a low-melting binder pitch, then the low-melting binder pitch is sent to a vacuum column for distillation of low-molecular reaction products and holding at 300-320 °C and a pressure of 20-50 mm Hg. For 2-5 hours, using a superheated steam flow rate of 0.02-0.04 kg/h per kg of raw material, producing a high-melting pitch melt. The resulting melt is treated with ultrasound at a frequency of 15-22 kHz and a power of 50-100 W/ ^cm² to produce a high-melting fiber-forming pitch. The low-molecular-weight reaction product distillates are sent to an atmospheric column for water separation and separation to produce hydrocarbon gases, gasoline, and light and heavy gas oils. The heavy gas oil, after heating to a temperature of 480-540°C, is then sent to a mixer. The low-melting binder pitch can be recovered as a separate commercial product.

Technical result: increased yield of petroleum pitch, simplification of the technological process.

The disadvantages of this method are:

- the use of large quantities of superheated water vapor as a non-oxidizing agent at all stages of the process flow, leading to high energy costs, the problem of wastewater disposal and the need to introduce additional process equipment for separating water and drying by-products of distillation;

- low yield and unsatisfactory quality of the target product - high-temperature pitch binder, due to the use of a fraction of heavy pyrolysis resin with an i.c. of 250°C as raw material and insufficient duration of isothermal holding of the reaction mass in the separator.

The invention (Patent of the Russian Federation No. 2645524, 2017, cl. C10C 3/00, C10C 1/16, published on 21.02.2018, Bulletin No. 6) relates to the field of oil refining, in particular to a method for producing medium-temperature petroleum binders/impregnation and high-temperature binder pitches, and can be used in the petrochemical and oil refining industries. The method includes thermal polycondensation of a heavy pyrolysis resin purified from low-boiling components with an initial boiling point of n.k. 230°C in a flow reactor at a pressure of 1.0-2.5 MPa and a temperature of 360-390°C, isothermal holding of the reaction mass in a reactor-separator at a temperature of 320-380°C and a pressure of 0.1-0.2 MPa in the presence of natural gas as a bubbling agent with distillation of low-molecular reaction products. In this case, the reaction mass is in the reaction zone of the flow reactor for 6-10 hours to obtain petroleum medium-temperature binder/impregnation pitches or 18-20 hours to obtain petroleum high-temperature binder pitch at a natural gas flow rate of 0.015-0.025 kg/h per 1 kg of feedstock with recirculation of the reaction mixture. Distillates of low-molecular reaction products are sent to a separation column to obtain hydrocarbon gases, gasoline, light and heavy gas oils. The technical result is the production of petroleum medium-temperature binder/impregnation or high-temperature binder pitches; an increase in the yield of petroleum medium-temperature binder/impregnation or high-temperature binder pitches; an improvement in the economic and environmental performance of the process; and a simplification of the process.

The invention (Patent of the Russian Federation No. 2647735, 2017, class C10C 3/00, C10C 1/16, published on 19.03.2018, Bulletin No. 8, 2018) relates to the field of oil refining, in particular to a method for producing high-temperature petroleum binder pitches, and can be used in the petrochemical and oil refining industries. The method includes thermal polycondensation of heavy pyrolysis resin purified from low-boiling components in a flow reactor at a pressure of 1.0-2.5 MPa and a temperature of 360-390 °C, isothermal holding of the reaction mass in a reactor-separator at a temperature of 320-380 °C and a pressure of 0.1-0.2 MPa in the presence of dry hydrocarbon gas as a bubbling agent with distillation of low-molecular reaction products. The reaction mixture is held in the flow reactor reaction zone for a specified time at a pressure of 1.0-2.5 MPa. The reaction mixture is then sent to a reactor-separator for isothermal holding at a temperature of 320-380°C and a pressure of 0.1-0.2 MPa for 18-20 hours. Low-molecular-weight reaction products are distilled off at a dry hydrocarbon gas flow rate of 0.01-0.02 kg/h per kg of feedstock, producing a high-temperature petroleum binder (pitch). The low-molecular-weight reaction product distillates are sent to a separation column to produce hydrocarbon gases, gasoline, and light and heavy gas oils.

The technical result is the production of a high-temperature petroleum binder pitch, an increase in the yield of the high-temperature petroleum binder pitch, an improvement in the economic and environmental performance of the process, and a simplification of the process.

The formula of the present invention is as follows: a method for producing a high-temperature petroleum binder pitch, consisting of the stages of thermal polycondensation of a pyrolysis resin fraction at a temperature of 360-390°C and a pressure of 1.0-2.5 MPa in a flow reactor and subsequent isothermal holding of the reaction mass with distillation of low-molecular components in a reactor-separator, characterized in that a fraction with an initial boiling point of n.k. is used as the pyrolysis resin fraction. 230°C, during the thermal polycondensation of raw materials in a flow reactor, a non-oxidizing agent is excluded - superheated water vapor, the process of isothermal holding of the reaction mass, accompanied by thermal polycondensation and distillation of low-molecular components, is carried out in a reactor-separator at a temperature of 320-380°C and a pressure of 0.1-0.2 MPa for 18-20 hours and bubbling of dry hydrocarbon gas at a gas flow rate of 0.01-0.02 kg / h per kg of soft pitch.

The closest to our invention is Russian Federation patent No. 2659262, 2017, Class C10C 3/00, C10C 1/16, published June 29, 2018, Bulletin No. 19, 2018 (prototype).

The aim of this invention is to obtain a high-temperature petroleum binder pitch with specified physical and chemical characteristics (Table 1) with a high yield and to simplify the process.

The stated objective is achieved by the proposed method for producing a high-temperature petroleum binder pitch, consisting of the stages of thermal polycondensation of the pyrolysis resin fraction at a temperature of 360-390°C and a pressure of 1.0-2.5 MPa in a flow reactor and subsequent isothermal holding of the reaction mass with distillation of low-molecular components in a reactor-separator, wherein:

- the fraction with n.k. 230°C is used as the pyrolysis resin fraction;

- when undergoing thermal polycondensation of raw materials in a flow reactor, the non-oxidizing agent - superheated water vapor - is excluded;

- the process of isothermal holding of the reaction mass, accompanied by thermal polycondensation and distillation of low-molecular components, is carried out in a reactor-separator at a temperature of 320-380°C and a pressure of 0.1-0.2 MPa for 18-20 hours with bubbling of natural gas, at a gas flow rate of 0.015-0.025 kg/h per 1 kg of raw material. Natural gas has the following composition: CH ₄ - 98%, C ₂ H ₆ - 2%.

The essence of the proposed method is as follows. Heavy pyrolysis tar (Table 2), a by-product of ethylene production, with an initial boiling point of approximately 200°C, is fractionated in a distillation column. Low-boiling fractions of the pyrolysis tar are withdrawn from the top, and a heavy fraction with an initial boiling point of 230°C, or soft pitch with a softening point according to KIS of 30-80°C, is withdrawn from the bottom.

Removing low-boiling components of the TSP (up to 230°C) reduces gas evolution during thermal polycondensation and improves the quality of the target high-temperature petroleum pitch by reducing porosity. Using a pyrolysis resin fraction with an OC temperature of 250°C as feedstock in the prototype eliminates approximately 25% of the reactive polycycloaromatic components of the original pyrolysis resin from the thermal polycondensation reaction zone (see Table 2). In the proposed method, using a pyrolysis resin fraction with an OC temperature of 230°C as feedstock corrects this, thereby increasing the yield of high-temperature petroleum binder pitch.

Keeping the carbonizing mass, heated in a flow reactor, in a reactor-separator at a temperature of 320-380°C, a pressure of 0.1-0.2 MPa for 18-20 hours with bubbling of natural gas (at a gas consumption of 0.015-0.025 kg/h per 1 kg of raw material) and simultaneous distillation of low-molecular products of the process provides optimal conditions for obtaining high-temperature petroleum binder pitch.

Reducing the isothermal holding temperature to 320°C compared to the prototype (340°C) makes it possible to control the rate of the thermolysis reaction and the quality of the target product.

Carrying out the process at temperatures below 320°C for less than 18 hours results in a reduced yield of the target product due to incomplete thermopolycondensation reaction. Increasing the temperature above 380°C and holding for 20 hours or more results in a pitch whose group composition does not meet the requirements for high-temperature petroleum binder pitch (Table 1). Increasing the isothermal holding time of the reaction mixture to more than 10 hours results in a pitch whose physicochemical characteristics meet the requirements for high-temperature petroleum binder pitch (Table 1). Natural gas bubbling in the reactor-separator ensures uniform mixing of the mixture components, reduces stagnation of the carbonizing mass and coking of the reactor walls, and improves the quality of the finished product. Eliminating the supply of superheated steam at the stage of soft pitch heat treatment in a flow reactor reduces energy consumption for generating steam, the cost of installing equipment for obtaining, storing and supplying it, as well as additional equipment for drying the distillate products of the process, and eliminates the wastewater treatment stage.

Using natural gas as a bubbling agent instead of superheated steam during isothermal holding in a reactor-separator reduces energy consumption for steam generation, the cost of installing additional equipment for drying distillate products, and wastewater treatment. A natural gas flow rate of less than 0.015 kg/h per 1 kg of feedstock does not ensure the reaction mixture temperature remains within 320-380°C and its intensive, uniform mixing. Increasing the natural gas flow rate above 0.025 kg/h per 1 kg of feedstock does not affect the pitch group composition or softening point and is not economically feasible.

The basic process flow diagram for obtaining high-temperature petroleum binder pitch is shown in Fig. 1, where:

1 - pyrolysis resin preparation unit, 2 - tubular furnace, 3 - mixer, 4 - flow reactor, 5 - separator, 6 - reactor-separator, 7 - system for cooling, condensation and separation of low-molecular heat treatment products.

Streams: I - heavy pyrolysis resin into the preparation unit, II - light fraction of pyrolysis resin, III - soft petroleum pitch (heavy fraction of pyrolysis resin with a temperature of about 230°C), IV - soft pitch heated in the furnace, V - reaction mass from the mixer into the flow reactor, VI - reaction mass from the flow reactor into the separator; VII - distillation of low-molecular products of heat treatment of the flow reactor; VIII - reaction mixture from the separator; IX - reaction mixture from the separator for circulation, X - reaction mixture from the separator to the reactor-separator, XI - natural gas, XII - target petroleum high-temperature binder pitch, XIII - gas-steam mixture of low-molecular heat treatment products, XIV - hydrocarbon gases, XV - gasoline, XVI - light distillate with a boiling point below 350°C, XVII - heavy distillate with a boiling point of 350-450°C.

Heavy pyrolysis tar I enters preparation unit 1, where it is separated into light fractions II and heavy fractions III with a base temperature of 230°C (hereinafter referred to as soft pitch). Soft pitch is fed via stream III to tubular furnace 2, where it is heated to 280-390°C under a pressure of 1.9 MPa. Heated soft pitch IV then enters mixer 3, where it is mixed with the recirculating reaction mass, and stream V feeds the mixture to flow reactor 4, where the feedstock is heat-treated at a temperature of 360-390°C and a pressure of 1.0-2.5 MPa. From flow reactor 4, the reaction mass enters separator 5 via stream VI for distillation of low-molecular heat-treatment products VII. The resulting liquid reaction mass VIII is separated, a portion of the reaction mass is returned from separator 5 to mixer 3 via stream IX, the balance amount of reaction mass X is discharged into one of three reactor-separators 6, which operate periodically; the entire circuit operates continuously. In reactor-separator 6, low-molecular-weight reaction products are distilled off by reducing the pressure to 0.1-0.2 MPa. After filling one reactor-separator, it is disconnected from the reaction mass feed line, which is directed to the next reactor-separator. In reactor-separator 6, an isothermal holding process is carried out at a temperature of 320-380°C, a pressure of 0.1-0.2 MPa, and bubbling of natural gas XI with a mass flow rate of 0.015-0.025 kg/h per 1 kg of feedstock. This process involves thermal destructive condensation of the liquid reaction mass and distillation of low-molecular-weight components.

Isothermal holding of the reaction mass in reactor-separator 6 continues until high-temperature petroleum binder pitch XIV with the required quality parameters is obtained. The physicochemical properties of the pitch are adjusted to the required values by regulating the temperature, holding time, natural gas injection rate, and liquid mass circulation rate. After achieving the desired degree of conversion, the reaction mass is withdrawn from reactor-separator 6 as target product XII. Low-molecular-weight thermal polycondensation product distillates from reactor-separators 6 as stream XIII and are fed to column 7, where they are fractionated under reduced pressure to produce hydrocarbon gases XIV, gasoline XV, light gas oil XVI, and heavy gas oil XVII.

The obtained petroleum pitches are analyzed according to the following quality indicators:

- softening temperature using the ring and rod method, GOST 9950-83;

- content of α ₁ -fraction insoluble in quinoline, GOST 12000-83;

- content of α-fraction insoluble in toluene, GOST 7847-73;

- ash content, GOST 7846-73;

- volatile matter yield, GOST 9951-73;

- sulfur content, GOST 1437-75.

The proposed method is illustrated with examples. Heavy pyrolysis resin was used as a raw material for producing high-temperature petroleum binder pitches (Table 2).

The resulting pitch's physicochemical properties are comparable to those of petroleum-based high-temperature binder pitch. Examples show that the method allows for:

- to obtain high-temperature petroleum binder pitches;

- increase the yield of high-temperature petroleum binder pitch by using a fraction of heavy pyrolysis resin with an initial temperature of 230°C as raw material and using natural gas as a bubbling agent;

- improve the economic and environmental performance of the process by eliminating the use of superheated water vapor during the heat treatment of soft pitch in a flow reactor and replacing it with natural gas for bubbling in the reactor-separator.

The formula of the present invention is as follows: a method for producing a high-temperature petroleum binder pitch, consisting of the stages of thermal polycondensation of a pyrolysis resin fraction at a temperature of 360-390°C and a pressure of 1.0-2.5 MPa in a flow reactor and subsequent isothermal holding of the reaction mass with distillation of low-molecular components in a reactor-separator, characterized in that a fraction with an initial boiling point of n.k. is used as the pyrolysis resin fraction. 230°C, during the thermal polycondensation of raw materials in a flow reactor, a non-oxidizing agent is excluded - superheated water vapor, the process of isothermal holding of the reaction mass, accompanied by thermal polycondensation and distillation of low-molecular components, is carried out in a reactor-separator at a temperature of 320-380°C and a pressure of 0.1-0.2 MPa for 18-20 hours and bubbling with natural gas at a gas flow rate of 0.015-0.025 kg/h per 1 kg of raw materials.

The disadvantages of this method are:

- use of additional large quantities of natural gas;

- low yield and unsatisfactory quality of the target product - high-temperature pitch binder, due to the use of a fraction of heavy pyrolysis resin with an initial temperature of 230°C as raw material.

The theoretical basis for our proposed technological process for processing coal tar or pyrolysis tar. The coal tar or pyrolysis tar processing process according to our proposed invention includes the following steps:

Stage 1. Preparation of raw materials in the raw materials park.

Stage 2. Resin processing at the process plant.

Stage 2.1. Preparing resin for rectification.

Stage 2.2. Primary rectification – dehydration of the resin before feeding it to the main stage of rectification.

Stage 2.3. Rectification of resin to obtain narrow fractions and medium-temperature pitch.

Stage 2.4. Obtaining grade "B" electrode pitch.

Stage 2.5. Cooling, granulation and packaging.

Stage 1. Preparation of raw materials in the raw materials park.

Due to the planned procurement of raw materials from third-party suppliers (various manufacturers), preparation of raw materials for processing begins directly with the acceptance stage, with an average laboratory analysis of the received coal tar or pyrolysis tar before discharge into the raw material storage tanks.

In the future, all technological operations in the raw material park must ensure that the resin composition is constant before being fed for processing (its physical and chemical homogeneity).

In this case, the main indicator of homogeneity is the naphthalene content, since it most fully characterizes the quality of the resin.

Fluctuations in the naphthalene content in the resin fed to the plant should not exceed 1% by weight.

Consistency of quality is achieved by pumping incoming batches of raw materials into separate tanks or into tanks containing residues similar in chemical composition (naphthalene content).

It is possible to average the quality of the raw resin by mixing naphthalene-containing oils.

The recommended amount of resin in the raw material park when processing raw materials purchased from various suppliers, based on storage for 15 days.

The technological scheme for feeding raw materials to the plant must be equipped with self-cleaning filters.

Stage 2. Resin processing at the process plant.

Stage 2.1. Resin preparation unit for processing – water removal and desalination.

The coal tar or pyrolysis tar supplied to the process plant contains emulsified water in which various salts are dissolved, including ammonium chloride, complexes of tar components with Lewis salts and acids, as well as mechanical impurities.

To obtain high-quality pitch suitable for use as a binder in the graphite materials industry, etc., high-quality dehydration of the resin and removal of mechanical impurities from coarse particles is carried out.

Additional high-quality dehydration and removal of salts and acids from the resin significantly reduces corrosion of process equipment and pipelines, and also prevents corrosion products from entering the finished product, thereby ensuring long-term trouble-free operation of the process equipment and the commercial quality of the resulting product.

To prepare coal tar or pyrolysis tar for processing, the process flow diagram includes a tar washing unit and its filtration before feeding it to primary rectification (a second stage of self-cleaning filters is installed).

Washing is carried out in a horizontal tank (thermal settling tank) equipped with washing devices, at a pressure of 0.7-1.4 MPa, a temperature of 90-120 (140)°C, with internal recirculation of the aqueous solution and fresh water replenishment up to 3-5 wt.% of the resin supplied as raw material.

As an additional measure for deep resin dewatering, the addition of a demulsifier is recommended. The demulsifier is injected directly into the fresh water stream before the water/resin mixer.

In addition to filtering the raw coal tar or pyrolysis tar before feeding it to the plant, the tar ash concentrated in its solid dispersed phase is removed by washing the tar in the tar preparation unit for rectification.

Stage 2.2. Dehydration of coal tar or pyrolysis tar before feeding it to rectification.

After the resin has been washed, desalted and heated, it is sent to a primary atmospheric distillation column to separate it from residual moisture and light oil.

Stage 2.3. Rectification of coal tar or pyrolysis tar to produce narrow fractions and medium-temperature pitch.

Significant difficulties in resin rectification are associated with the high boiling points of its main components and, in particular, the high-boiling residue - medium-temperature pitch.

Therefore, the main solution for processing resin is to preheat it in a tubular furnace and separate it into fractions in a complex distillation column.

When separating a heated resin stream in a distillation column operating under excess pressure, the temperature in the feed zone is taken to be 370-390°C, which corresponds to a temperature at the outlet of the heating furnace coil of 395-405°C.

The increase in the efficiency of the rectification process is limited by the conditions of the heat balance of the rectification column and is partially compensated by feeding superheated water vapor into the still section and optimizing the temperatures and flow rates of intermediate circulation irrigations.

In the absence of stripping sections on the side streams removed from the main distillation column, the removed fractions contain low-boiling components in quantities determined by the equilibrium conditions on the plates from which the selection is made.

All this, taking into account the complexity and imperfection of the system that the resin represents, reduces the clarity of separation and leads to a significant “smearing” of the components across the resin fractions.

The above-mentioned disadvantages of resin separation in a complex distillation column can be reduced if stripping sections are installed on the side streams removed from the column, with stripping of low-boiling fractions, supply of superheated steam, or by heating the bottom part of the stripping column.

When rectifying coal tar or pyrolysis tar, the goal is to obtain a large number of narrow fractions.

Difficulties in resin separation cannot be eliminated by installing stripping sections, increasing the number of columns and fractions collected.

It is very important to simplify the resin composition, eliminating the harmful effects of the formation of numerous azeotropic mixtures, since the latter make the separation of the resin difficult.

The presence of phenols leads to the formation of positive, that is, low-boiling, azeotropic mixtures with naphthalene, and the content of naphthalene in the latter increases significantly with a decrease in the total pressure of the components of this system.

Phenols form positive azeotropic mixtures with high-boiling unsaturated compounds and indole, contributing to an increase in their concentration in the naphthalene fraction.

At the same time, quinoline forms negative azeotropic mixtures with low-boiling phenols, which explains the presence of the latter in high-boiling fractions.

In the process flow diagram we have proposed, the main distillation column is divided into two sections: the first section is designed for the exhaustive separation of light components from the medium-temperature pitch and the removal of the second anthracene fraction as a side stream; in the second section, separation into narrow fractions occurs.

The main distillation column operates under vacuum, which reduces heat consumption for the process, increases the yield of high-boiling fractions, reduces the degree of thermal impact on the pitch and, as a result, reduces coking of the furnace equipment, the main distillation column and the equipment associated with them.

Stage 2.4. Obtaining grade "B" electrode pitch.

The starting material for the production of grade "B" electrode pitch is medium-temperature pitch obtained by rectification of coal tar or pyrolysis resin.

The yield of grade "B" electrode pitch (EP) reaches 87-89 wt.% of the initial medium-temperature pitch.

The quality of the product is characterized by the following data:

• softening temperature - 85-92°C (using the Ring and Rod method);

• yield of substances insoluble in toluene - not less than 31 wt.%;

• yield of volatile substances – no more than 57 wt.%.

The oxidation process of medium-temperature pitch is accompanied by the release of heat; however, its rate is insignificant at the beginning of oxidation, especially when the temperature of the initial pitch does not exceed 280-300°C. The optimal temperature at which the processes of pitch condensation and polymerization begin to proceed intensively is 340-365°C.

The technological process for obtaining EP is continuous and consists of thermal-oxidative treatment of raw materials with air in sequentially connected reactors.

As a result of thermal-oxidative treatment, EP, pitch distillates, reaction water and exhaust air are produced.

For the polymerization and oxidation of raw materials, two reactor cubes, each with a volume of 50 ^m3 , connected by overflows, are provided.

The reactor cube is a vertically positioned cylindrical apparatus with a diameter of 3 meters and a height of 7.6 meters. The bottom of each reactor contains a bubbler for supplying compressed air.

The specific air consumption is 160-270 ^m3 per 1 ton of mixture and is adjusted taking into account the actual quality of the pitch and the content of unreacted oxygen in the exhaust air, which should not exceed 3%.

An equally important technological factor of the process is the air consumption per unit of pitch per hour; as it increases, the processing time also decreases.

The process of obtaining grade "B" electrode pitch consists of distillation of the lightest components of the raw materials, polycondensation and polymerization of the products included in the medium-temperature pitch, the formation of new compaction products, and the destruction of thermally unstable compounds or structures.

The role of oxygen in the process of obtaining grade "B" electrode pitch is reduced to the intensification of the dehydrogenation process and the removal of hydrogen in the form of reaction water, part of the hydrogen is consumed in the formation of methane.

In parallel with the copolycondensation and copolymerization of more active compaction products, polycondensation and polymerization of individual compounds and the formation of acetylene and carbon dioxide occur.

The balance of oxygen used in the reaction, without taking into account its content in medium-temperature and high-temperature pitches, is: reaction water - 93.5 wt.%, CO+ _CO2 - 5 wt.%, distillate - 1.5 wt.%.

Oxygen intensifies the processes of dehydrogenation and removal of hydrogen in the form of water, as indicated by the fact that the vapor-gas phase during thermal-oxidative treatment of pitch consists of 93.5% water by weight.

As the softening temperature of pitch increases, the oxygen content in it does not increase.

The significance of the destruction of the compounds that make up the pitch can be judged by the insignificant content of methane in the exhaust gases leaving the reactor cubes.

As the softening temperature of the pitch increases as a result of dehydropolycondensation reactions, the content of substances insoluble in toluene increases sharply.

Part of the relative increase in the content of these products occurs due to the removal of pitch distillates, as well as as a result of thermal polymerization.

The group composition of the electrode pitch grade "B", obtained by air treatment with a weight yield equal to 87 wt.%, changes in comparison with the medium-temperature pitch as follows: the content of the α-fraction increases from 25.8 to 52.5%; the content of the P-fraction decreases from 40.9 to 26.2%, and the γ-fraction from 33.3 to 21.3%.

The yield of the a-fraction increases due to the polycondensation of compounds included in the P-fraction; in turn, the y-fraction replenishes the loss of the P-fraction and partially forms the a-fraction according to the scheme: →p-fraction→a-fraction.

Great importance is attached to the chemical composition of the original coal tar pitch and the first stage of coke production - obtaining pitch with an elevated softening temperature by oxidizing it with oxygen or air.

It is believed that during the oxidation of such a complex aromatic system as coal tar pitch, a sufficiently substantiated and unambiguous mechanism for the interaction of this system with oxygen cannot be proposed.

Numerous literary sources indicate a general scheme for the direction of the oxidation process of aromatic hydrocarbons only for petroleum products:

When small (10 µm) pitch particles were oxidized in an air stream at 150-350°C, samples were obtained that did not melt at 250°C, and the formation of oxygen-containing functional groups was noted.

Since low-molecular hydrocarbons, which evaporate during thermostatting, participate in the compaction during thermal oxidation, the yield of oxidized pitch is significantly higher.

Thus, when oxidizing even soft pitch, a yield of 98-99 wt.% was recorded.

During thermal oxidation in thermolysis reactions, for the compaction of hydrocarbons in the liquid phase, a necessary condition for interaction is their planarity.

In vapor-phase compaction, this condition is not met, and therefore the compaction products are non-coplanar and easily form cross-links.

Understanding thermochemical transformations during pitch oxidation allows one to select the technology, processing mode, and quality of the raw material depending on the goal.

Differences in the hydrocarbon compaction mechanism explain the reasons for the structural discrepancy between the same fractions of oxidized and thermostatted pitches, as well as the influence of oxidation on the graphitization process.

The increased viscosity of oxidized pitch is explained, firstly, by a decrease in the amount of low-molecular plasticizing hydrocarbons, and secondly, by the formation of non-planar oligomers.

It is obvious that , formed during thermal oxidation, differs in composition from , formed as a result of thermal transformations, and differently affects the growth and coalescence of the mesophase during carbonization.

By linking the known information about the influence of raw material oxidation on graphitization with the concepts of the compaction mechanism, it can be concluded that the “negative” influence of oxidation manifests itself at a temperature close to the temperature of the formation of mesophase nuclei.

Under these conditions, oxidation leads to the formation of hydrocarbon agglomerates of a three-dimensional structure with cross-links, which, as a dispersed phase, prevent the development of mesophase formations, which leads to the production of poorly graphitizing coke of an isotropic or fine-mosaic structure.

When pitch is oxidized under moderate conditions (<300°C), compaction occurs with minimal formation of a three-dimensional structure, which promotes coalescence of the mesophase and the production of well-graphitizing coke.

It is believed that in light of the obtained ideas about the features of thermal and oxidative transformations, the technology of thermal-oxidative treatment of pitch in cubes for the purpose of selective build-up, which exists at some coke-chemical plants, appears to be suboptimal.

The air flow rate used during bubbling mixing in stills does not provide the required degree of oxidation of pitch distillates.

This demonstrates the great potential of using oxygen-enriched air to intensify the pitch preparation process in pitch and coke shops.

When using oxygen-enriched air, the qualitative composition of the high-temperature pitch also changes.

During oxidative dehydropolycondensation reactions, oxygen is consumed primarily (92-95%) by dehydrogenation and hydrogen binding. The oxygen consumption per unit of feedstock is constant and independent of its concentration in the enriched air. As oxygen concentration increases, the amount of low-molecular-weight hydrocarbons involved in the oxidation process increases, and polycondensation reactions intensify. In high-temperature pitch, the content of highly condensed fractions (a and aa) increases at the same softening point.

Differences in the properties of pitches are most noticeably manifested in the dynamics of gas evolution during heating.

Pitch obtained from medium-temperature coal, during thermal destruction, releases less heat-resistant hydrocarbons, which, when decomposed in the gas phase, produce an increased yield of pitch-coke gas.

A brief description of the principles of forming the process flow diagram and a list of blocks and units of the installation we are proposing are presented in Table 3.

We offer the following method for producing high-melting electrode pitch grade "B":

A method for producing high-melting grade "B" electrode pitch, consisting of the stages of receiving coal tar or pyrolysis resin, preparing raw materials for processing - removing water and desalting, heating the raw materials, primary rectification of the raw materials, vacuum rectification of the stripped resin, converting medium-temperature pitch in column-type thermal oxidation and polymerization reactors into pitch of the required quality, receiving grade "B" electrode pitch and feeding it to a belt cooler-granulator, cooling the pitch on the belt cooler-granulator, absorbing pitch distillate from the vapors of oxidation gases obtained in the thermal oxidation and polymerization reactors for producing grade "B" electrode pitch, characterized in that isothermal reactors with built-in heat exchange and mixing devices are used in the block of R-101 polymerization and R-102 thermal oxidation reactors, wherein both R-101 and R-102 reactors can be used as reactors oxidation with the supply of air as an oxidizing agent to each of them with the possibility of obtaining the specified qualities of the resulting high-melting electrode pitch, has a unit for washing coal tar or pyrolysis resin and filtering it before feeding it to the primary rectification, has a rectification unit designed to separate the resin flow into marketable products, consisting of two columns with heaters, circulation and washing irrigation, air coolers with rotation regulators and louvers of factory shelters, a hydro-ejector vacuum creation system is used, consisting of a hydro-ejector and a separator - a divider on the vapor and liquid line after the rectification column, a nitrogen breathing system is used, consisting of a system for supplying nitrogen to the polymerization and thermal oxidation reactor and removing nitrogen to maintain pressure in the process equipment and removing excess nitrogen-hydrocarbon medium for disposal in the afterburner, as an absorbent for absorbing pitch distillate and separating An absorption fraction of 230-270°C is used to remove oxidation gases - one of the plant's commercial products; due to the use of a hydrocirculation system for creating a vacuum and nitrogen breathing, hydrocarbon emissions into the atmosphere are excluded.

This method also differs in that:

- the process of polymerization and thermal oxidation of raw materials in the R-101 reactor is carried out at a temperature of 280-380°C, excess pressure in the reactors depending on the quality of the raw material flow and the required commercial qualities of the finished product in the range of 0.1-2.5 MPa, the total residence time in the reaction zone in both reactors R-101 and R-102 is 6-20 hours in total with regulation of the temperature profile along the height of the reactors, for which purpose circulation circuits of the coolant/coolant are provided to remove excess heat of reaction and supply the missing one, which allows to exclude uncontrollability of the process, specific air consumption of 160-270 m3 per 1 ton of raw material mixture;

- the design of thermal oxidation and polymerization reactors allows the feedstock flow to be directed both from the bottom up and from the top down, while feeding the flow from the top down and removing the thermally oxidized product from the bottom of the reactors eliminates internal recirculation of the reaction flow and its uncontrolled overoxidation;

- to obtain high-quality pitch suitable for use as a binder in the graphite materials industry, a unit is provided for washing coal tar or pyrolysis resin or their fractions and filtering them before feeding them to primary rectification; a second stage of self-cleaning filters is installed, high-quality dehydration of the resin and removal of mechanical impurities from coarse particles is carried out, additional high-quality dehydration and removal of salts and acids from the resin significantly reduces corrosion of process equipment and pipelines, and also prevents the ingress of corrosion products into the commercial product, which ensures long-term trouble-free operation of the process equipment and commercial quality of the resulting products;

- stripped coal tar or pyrolysis resin after the heat exchange unit, where it is heated to a temperature of 380-405°C, enters the resin rectification unit to obtain narrow fractions, including two vacuum rectification columns with heaters, circulating and washing refluxes, refrigerators and heat exchangers for cooling the fraction vapors, a vacuum rectification column K-102 for obtaining the II anthracene fraction of fr. 320-420°C and medium-temperature pitch of fr. 420°C+ at a pressure in the column of 250-350 mm Hg, a temperature in the upper and bottom parts of the column of 250-270°C and 290-340°C, respectively, and a vacuum rectification column K-103 for obtaining a phenol fraction of fr. 170-210°C, naphthalene fraction fr. 210-230°C, absorption fraction fr. 230-270°C and 1st anthracene fraction fr. 280-360°C at a pressure in the column of 100-250 mm Hg, a temperature in the upper and bottom parts of the column of 125-130°C and 250-280°C, respectively, the use of vacuum in the main process columns reduces the heating temperature, eliminates the loss of quality of fractions due to coking and improves the energy characteristics of the process;

- to maintain constant pressure in the distillation process of stripped resin, a hydro-ejector vacuum creation system is used, consisting of a hydro-ejector EZh-101 and a separator S-103 - a separator on the vapor and liquid line after the distillation column K-103, after cooling in X-101, the uncondensed gases of the separator S-102 with a temperature of 20-40°C and a pressure of 100-250 mm Hg. are fed to the input of the low-pressure chamber of the hydroejector EZh-101, where they are captured by the flow of active liquid, which is steam condensate from the separator S-102 and desalinated water supplied by the circulation pump, and then the gas-liquid mixture is fed for separation to the separator S-103, from which the degassed steam condensate as a working flow, fed for cooling to the water cooler X-102, and then from the discharge of the active liquid pumps is fed to the input of the high-pressure chamber of the hydroejector EZh-101.

consisting of a unit for receiving coal tar or pyrolysis tar or their fractions, a heat exchange unit, a unit for preparing the tar for processing 8 - removing water and desalting, a unit 10 for heating the raw material and maintaining the temperature in the distillation columns, apparatuses and pipelines, a unit for primary rectification of raw materials 9, a unit for vacuum rectification of stripped tar 11, a unit for polymerization and thermal oxidation of raw materials 12, consisting of reactors R-101 and R-102, units for supplying and removing heat, mixing, a unit for maintaining a constant temperature and heating the process pipelines and pumps pumping tar and pitch, a vacuum creation system, a unit for receiving grade "B" electrode pitch and feeding it to a belt cooler-granulator, a belt cooler-granulator, a nitrogen breathing system and the capture of vapors of a nitrogen-hydrocarbon environment, a system for cooling and absorption of pitch distillate from vapors of oxidation gases from polymerization and thermal oxidation reactors for obtaining grade "B" electrode pitch, a high-temperature oil coolant circuit, a circuit for providing heating for process apparatuses, pipelines and pumping equipment, a process furnace for heating stripped resin, air cooling devices for cooling process flows, characterized in that isothermal reactors are used in the distillation column in the block of reactors for polymerization and oxidation of raw materials, there is a unit for washing coal or pyrolysis resin and filtering them before feeding them to primary distillation, there is a distillation unit designed to separate the reaction stream into intermediate and commercial products, consisting of two vacuum columns with heaters, circulation and washing irrigation, air coolers with rotation regulators and louvers for plant shelters, contains a hydro-ejector vacuum creation system consisting of a hydro-ejector and a separator-divider on the vapor and liquid line after the distillation column, a nitrogen breathing system, which consists of a system for supplying nitrogen to the polymerization and thermal oxidation reactors and removing nitrogen to maintain pressure in the process equipment and removing excess nitrogen-hydrocarbon medium for disposal in block 15 of the PD-104 afterburner, additionally equipped with a convection chamber for heating, using excess heat from the flue gases in it, the air supplied to it through coil heaters for pitch oxidation in the R-101 and R-102 reactors, an absorption fraction of 230-270?C is used as an absorbent for absorbing pitch distillate and separating it from oxidation gases - one of the commercial products of the plant, contains an absorption column K-104 and a separator C-104 for capturing residual liquid - a mixture of pitch distillate and absorption fraction, a unit for receiving and granulating high-melting electrode pitch of grade "B" 13, while the heat exchange unit for heating the stripped coal tar or pyrolysis tar vacuum rectification unit 11 is located in front of the stripped coal tar or pyrolysis tar vacuum rectification unit 11, wherein the resin preparation unit 8 is configured to feed raw coal tar or pyrolysis tar or their fractions into it by stream A and fresh water by stream B, and to remove corrosive components and water from the coal tar or pyrolysis tar or their fractions to treatment facilities by stream B; the resin primary rectification unit 9 is configured to feed heated prepared tar or its fractions into it by stream G and to separate the light fraction of 80-170°C by stream D; the heat exchange unit 10 is configured to feed stripped coal tar or pyrolysis tar into it by stream E and to heat it to a temperature of 380-405°C; the coal tar or pyrolysis resin rectification unit 11 is configured to produce narrow fractions - the 1st anthracene fraction fr. 280-360°C stream K, the 2nd anthracene fraction fr. 320-420°C stream L, the phenol fraction fr. 170-210°C stream Z, the naphthalene fraction fr. 210-230°C stream I, the absorption fraction fr. 230-270°C stream M and the medium-temperature pitch fr. 420°C stream O; the thermal-oxidative reactor R-101 of the polymerization and thermal-oxidation reactor unit 12 is configured to receive medium-temperature pitch from the vacuum rectification unit 11 via stream O and then feed it to thermal-oxidative polymerization in the temperature range of 280-380°C; The R-101 reactor is designed to allow movement of a medium-temperature pitch flow. 420?C from top to bottom, the PD-104 15 afterburner unit is configured to supply air with a temperature of more than 300?C by flow U, pumped by air compressors, countercurrently into the R-101 reactor, the R-101 reactor is configured to oxidize medium-temperature pitch with air in the temperature range of 280?C - start, 340-365?C - optimal temperatures for oxidation and thermal polymerization of pitch, the R-101 reactor is also configured to maintain excess pressure in the range from 0.1 to 2.5 MPa in the reaction zone depending on the quality of the raw material stream and the required commercial qualities of the finished product, the second-stage thermal-oxidative polymerization reactor R-102 is configured to receive a stream of thermally oxidized polymerizate with a temperature of 310-395?C from the R-101 reactor and subsequent oxidation of medium-temperature pitch with air at an average temperature in the R-102 reactor 340-370?C, the R-102 reactor is configured to maintain excess pressure in the range from 0.1 to 2.5 MPa depending on the quality of the feedstock stream and the required commercial qualities of the finished product; the absorption column of the unit for cooling and absorbing oxidation gas vapors from the reactors for producing grade "B" electrode pitch 14 is configured to receive a vapor-gas mixture with pitch distillate vapors by stream C from the reactors of the polymerization and thermal oxidation reactor unit 12, unit 14 is configured to receive the absorption fraction of fr. 230-270?C by stream H to refresh the absorbent composition; the bottom of the absorption column K-104 of unit 14 is configured to remove pitch distillate of fr. 260-420?C together with the absorption oil by the F stream by the pump without separation gradually after cooling, with a partial return to the K-104 absorption column, and the removal of the excess into the park, the top of the K-104 absorption column is designed with the possibility of removing oxidation gases with a temperature of up to 130?C into the S-104 separator for capturing the remaining liquid - a mixture of pitch distillate and absorption fraction, the PD-104 afterburner of block 15 is designed with the possibility of burning a mixture of pitch distillate and absorption fraction; The unit for receiving and granulating high-melting electrode pitch of grade "B" 13 is designed with the possibility of feeding the obtained electrode pitch of grade "B" by flow P from the bottom of the reactor R-102 of the polymerization and thermal oxidation reactor unit 12 through the holding tank E-103 in a liquid state with a temperature of 180-200°C, for cooling to the ambient temperature, as well as granulation and feeding for packaging into containers with subsequent weighing by flow P.

The advantages of the claimed installation scheme for producing grade "B" electrode pitch are as follows:

a) additional high-quality dehydration and removal of salts and acids from the resin significantly reduces corrosion of process equipment and pipelines, and also prevents corrosion products from entering the finished product, thereby ensuring long-term trouble-free operation of the process equipment and the commercial quality of the resulting product;

b) the main distillation column is divided into two sections; the first section is designed for the exhaustive separation of light components from the medium-temperature pitch and the removal of the second anthracene fraction as a side stream; in the second section, separation into narrow fractions occurs.

The main distillation column operates using a vacuum, which reduces heat consumption for the process, increases the yield of high-boiling fractions, reduces the degree of thermal impact on the pitch and, as a consequence, the coking of the furnace equipment, the main distillation column and the equipment associated with them;

c) concentration of the maximum amount of resources in naphthalene resin in the naphthalene fraction by supplying additional heat by circulating part of the absorption fraction through a separate tube in the furnace;

d) regeneration of heat from products removed from the columns, which increases the efficiency of the furnaces and reduces gas consumption for heating the resin;

d) maintaining the required vacuum allows obtaining pitch with the specified properties.

The basic flow chart of the plant for producing high-melting electrode pitch grade "B" according to our invention is shown in Fig. 2, where the blocks and flows are designated as indicated above.

The installation works as follows:

raw coal tar or pyrolysis resin or their fractions in stream A and fresh water in stream B enter the resin preparation unit 8, where water and corrosive components are removed from the coal tar or pyrolysis resin or their fractions (stream B). The heated prepared resin is fed by stream G to the primary rectification block 9, where the light fraction (fraction 80-70°C) D is separated. Then the stripped resin is sent by stream E to the heat exchange block 10, where it is heated to a temperature of 380-405°C and fed to the coal tar rectification block 11 to obtain narrow fractions (the 1st anthracene fraction (fraction 280-360°C - stream K), the 2nd anthracene fraction (fraction 320-420°C - stream L), the phenol fraction (fraction 170-210°C - stream 3), the naphthalene fraction (fraction 210-230°C - stream I), the absorption fraction (fraction 230-270°C - streams M, H) and medium-temperature pitch (stream O).

From the vacuum rectification unit 11, the medium-temperature pitch is fed by the O flow for thermal-oxidative polymerization in the temperature range of 280-380°C into the thermal-oxidative reactor R-101 of the polymerization and thermal-oxidation reactor block 12. In the R-101 reactor, the medium-temperature pitch O flow moves from top to bottom, and towards it (counter-current) from the PD-104 afterburner block 15, air is fed by the U flow with a temperature of more than 300°C, pumped by air compressors.

Oxidation of medium-temperature pitch with air in the R-101 reactor occurs within a temperature range of 280°C (initially), with 340-365°C being the optimal temperature for pitch oxidation and thermal polymerization. The excess pressure in the reaction zone ranges from 0.1 to 2.5 MPa, depending on the quality of the feedstock and the desired commercial qualities of the finished product.

From reactor R-101, the stream of thermally oxidized polymerizate with a temperature of 310-395°C (depending on the initial temperature of the feedstock stream) flows into the second-stage thermal-oxidative polymerization reactor R-102.

Oxidation of medium-temperature pitch with air occurs at an average temperature of 340-370°C in the R-102 reactor. The excess pressure in the reactor ranges from 0.1 to 2.5 MPa, depending on the quality of the feedstock and the required commercial qualities of the finished product.

The steam-gas mixture with pitch distillate vapors by stream C from the reactors of the polymerization and thermal oxidation reactor block 12 enters the absorption column of the cooling and absorption unit for oxidation gas vapors of block 15 from the reactors for obtaining grade "B" electrode pitch of block 12. To renew the composition of the absorbent, an absorption fraction (absorption oil - fraction 230-270°C) is fed into the absorption column K-104 of block 14 by stream H.

When pitch distillate and absorbent oil are mixed, a single fraction of pitch distillate is obtained, as pitch distillate mixes well with coal and pyrolysis oils. Thus, the absorbent is a mixed fraction of pitch distillate and absorbent oil.

From block 14, from the bottom of the absorption column K-104, the pitch distillate (fraction 260-420°C) together with the absorption oil in flow F are gradually and partially returned to the first plate of the absorption column K-104 by the pump without separation after cooling, the excess is discharged into the park, oxidation gases with a temperature of up to 130°C from the top of the absorption column K-104 are fed to the separator S-104 to capture the remaining liquid (a mixture of pitch distillate and absorption oil), then they are fed for combustion in the afterburner PD-104 of block 15.

The obtained high-melting electrode pitch of grade "B" is fed by flow P from the bottom of reactor R-102 of block 12 of polymerization and thermal oxidation reactors through holding tank E-103 in a liquid state with a temperature of 180-200°C to block 13 for receiving and granulating high-melting electrode pitch of grade "B", where it is cooled to ambient temperature, granulated and fed for packaging into containers with subsequent weighing.

The technological scheme of the atmospheric-vacuum installation ensures:

• Heating of raw coal tar or pyrolysis tar in heat exchangers using the heat of fractions and pitch.

• Separation of the light fraction and water at the first stage.

Heating of dehydrated resin in a furnace and subsequent feeding to the main vacuum distillation column for fractionation.

In the main distillation column, divided into two sections, in the first section, the light components are completely separated from the medium-temperature pitch and the second anthracene fraction is removed as a side stream; in the second section, separation into narrow fractions occurs.

This organization of the technological process allows:

a) regenerate the heat of the products removed from the columns, which increases the efficiency of the furnaces and reduces gas consumption for heating the resin;

b) obtain higher quality fractions and pitch;

c) concentrate in the resin the maximum amount of naphthalene resources in the naphthalene fraction by supplying additional heat by circulating part of the absorption fraction through a separate tube in the furnace;

d) maintaining the required vacuum allows obtaining pitch with specified properties;

d) resin preparation unit - a unit for washing coal tar or pyrolysis resin or their fractions - provides additional high-quality dehydration and removal of salts and acids from the resin, which significantly reduces corrosion of process equipment and pipelines, and also prevents the penetration of corrosion products into the commercial product, thereby ensuring long-term trouble-free operation of the process equipment and the commercial quality of the resulting product.

Our proposed technology for producing high-melting grade "B" electrode pitch from coal tar or pyrolysis resin or their fractions (medium-temperature pitch) allows for significant improvements in the environmental performance of this process and reduces emissions of harmful substances into the atmosphere to virtually zero values due to the following operations used in the process:

- due to the use of a hydrocirculation system for creating a vacuum in distillation columns, instead of steam ejectors traditionally used in similar cases, and nitrogen breathing, emissions of water vapor and hydrocarbons into the atmosphere are practically eliminated;

- the use of air coolers with rotation regulators and factory-made shutters to prevent the freezing of products in the cooler pipes instead of water ones eliminates the use of large quantities of recycled water;

- all gaseous hydrocarbons formed during the process are sent to the afterburner and undergo complete combustion;

- the process proposes to use dry packaging of electrode pitch using a belt cooler, which eliminates the use of "wet" operations and the formation of liquid effluents at this stage.

Our proposed technology for producing high-melting grade "B" electrode pitch from coal tar or pyrolysis resin or their fractions (medium-temperature pitch) allows for significant improvements in the environmental performance of this process and reduces emissions of harmful substances into the atmosphere to virtually zero values due to the following operations used in the process:

- due to the use of a hydrocirculation system for creating a vacuum in distillation columns, instead of steam ejectors traditionally used in similar cases, and nitrogen breathing, emissions of water vapor and hydrocarbons into the atmosphere are practically eliminated;

- the use of air coolers with rotation regulators and shutters of factory covers to prevent the solidification of products in the cooler pipes instead of water ones eliminates the use of a large amount of recycled water;

- all gaseous hydrocarbons formed during the process are sent to the afterburner and undergo complete combustion;

- the process proposes to use dry packaging of electrode pitch using a belt cooler, which eliminates the use of "wet" operations and the formation of liquid effluents at this stage.

Three technological experiments were carried out to characterize the declared technological parameters of the process of thermal-oxidative polymerization of medium-temperature pitch (fraction 420°C+).

Experiments on the conversion of the feedstock (medium-temperature coal tar pitch) were carried out on a laboratory setup, the diagram of which is shown in Fig. 3.

Description and operating principle of the laboratory setup.

The feedstock (medium-temperature coal tar or pyrolysis pitch, fraction 420°C+) from the feedstock tank E1 with a stirrer and heater (position (pos. 1 in Fig. 3) is fed by a metering plunger pump NDP (pos. 8) into the feedstock heating furnace Ш (pos. 1/1). The temperature in tank E1 (pos. 1) is maintained in the range of 120-150°C by means of electric heating. The feedstock level in tank E1 (pos. 1) is determined by the position of the float. The feedstock is stirred by a screw stirrer using an electric motor Ed1 (pos. 21) for uniform temperature distribution.

The working section of the NDP pump (item 8) and connecting pipelines are also heated to prevent raw material solidification in this section of the process flow. The KShT1 three-way ball valve (item 19) is designed to shut off the raw material supply to the NDP pump (item 8) and drain it from the unit. The VT8 needle valve (item 15) is designed to relieve pressure in the discharge line of the metering pump. The pressure in this section is determined by a pressure sensor. If the pressure in the discharge line of the NDP pump (item 8) increases, it is shut off.

In the feed furnace P1 (item 1/1), the feedstock (medium-temperature coal tar or pyrolysis pitch) is heated to the process temperature (280-380°C). To prevent coke formation on the furnace walls and to ensure uniform temperature distribution, the feedstock is stirred by a stirrer using an electric motor Ed2 (item 22). The heated feedstock then enters the reactor R (item 2), where the processes of pitch polymerization and thermal oxidation occur. The reactor is equipped with electric heating to maintain the process temperature at 280-380°C. The liquid phase level in the reactor is regulated by the position of the float using the needle valve Vt2 (item 12).

The bottom of the reactor is equipped with a gas bubbling device, a ring with 0.5 mm diameter holes. During the unit's warm-up and ramp-up to operating mode, nitrogen is supplied from cylinder B1 (item 18) through the gas supply line. After the reactor reaches operating mode, air may or may not be supplied from cylinder B2 (item 18) instead of nitrogen.

The amount of metered air and nitrogen is determined by rotameters and regulated by valves Vt4 (item 17) and Vt5 (item 17) (only Vt4 and Vt5 are indicated in the diagram). Three-way ball valve KShT2 (item 20) is used to switch the supply of nitrogen and air from cylinders B1 (item 18) and B2 (item 18) to the reactor. The gas is supplied through the line to the furnace for heating gases P2 (item 1/2). The temperature in furnace P2 (item 1/2) is maintained by electric heating to the required temperature (the maximum required temperature of air supplied to the reactor is 400°C), the pressure in the furnace is controlled by a pressure gauge. The temperature in all devices of the process flow diagram is determined by thermocouples.

To regulate the pressure in reactor P (item 2), valve Kl1 (item 13) and a pressure sensor (not shown in the diagram) are used. At the valve outlet is condenser K2 (item 7), where the incoming light fraction vapors (pitch distillate) are condensed. After condensation, the pitch distillate enters heat exchanger T2 (item 6), where it is cooled with running water. Oxidation gases and nitrogen enter separator C (item 3), where they are separated from the portion of the pitch distillate that entered the separator along with the gases.

Next, the oxidation gases and nitrogen pass through a gas clock to determine their quantity, are analyzed on a gas chromatograph and are released into the atmosphere.

The liquid portion of the light fractions (pitch distillate) enters receiver Pr2 (item 10). A safety valve, Vt1 (item 11), is also located at the top of the reactor. If the reactor pressure rises sharply, valve Vt1 (item 11) opens, and product vapors from the reactor enter the pipeline downstream of valve Kl1 (item 13).

After the experiment is completed—the polymerization and thermal oxidation of the raw materials—the liquid phase (electrode pitch) discharged from the reactor enters heat exchanger T1 (pos. 4), where it is cooled to a temperature of 150-200°C due to water evaporation, and then enters receiver Pr1 (pos. 9). Water vapor from the intertube space of heat exchanger T1 (pos. 4) enters condenser K1 (pos. 5), where it condenses. The vapor pressure is maintained at P = 5 atm by valve Kl1 (pos. 14). At this pressure, the water temperature in heat exchanger T1 (pos. 4) is 150°C, which prevents solidification of the electrode pitch in the heat exchanger tubes.

The specification of the laboratory setup equipment is given in Table 4.

The experimental conditions are presented in Table 5.

Algorithm for calculating the primary material balance of the experiments performed.

1. The flow rate of the raw material stream is determined by the stroke of the plunger of the raw material pump.

2. Nitrogen and air consumption is determined by rotameters Vt6-7.

3. The amount of gas leaving the receiver is determined by the counter, its composition is determined chromatographically.

4. The amount of electrode pitch fraction obtained is determined by weighing the receiver on electronic scales.

5. The amount of pitch distillate obtained is determined by weighing the receiver on electronic scales.

6. The electrode pitch is determined by:

- softening temperature according to the Ring and Rod method, GOST 9950;

- content of α ₁ -fraction insoluble in quinoline, GOST 28572;

- content of α-fraction insoluble in toluene, GOST 7847;

- ash content, GOST 7846;

- volatile emissions, GOST 9951.

Below are examples of the transformation of the feedstock at this plant (medium-temperature coal tar pitch, corresponding in its properties to medium-temperature coal tar pitch grade B according to GOST R 59045 - 2020).

Example 1.

1.0 kg of medium-temperature pitch (fr. 420°C+) was placed in reactor P and kept there at a temperature of 340°C and an excess pressure of 0.5 MPa without air access for 5 hours.

After this, air heated to 340°C in the amount of 240 liters was uniformly supplied to reactor R through valve Vtb (pos. 17) from cylinder B2 (pos. 18) over the course of 5.5 hours. After this, the pitch remained in the reactor at the same temperature and an excess pressure of 0.5 MPa for another thirty minutes.

The oxidation exhaust gases were continuously analyzed, and the pitch distillate was collected in receiver PR2.

After this, the temperature in reactor P is sharply lowered to 220-230°C and the reactor is unloaded and the material balance is calculated as described above in the section on the description and operating principle of the laboratory setup.

Amount of oxidation gases formed: 0.25 kg.

The amount of pitch distillate formed: 0.15 kg.

The amount of electrode pitch formed: 0.60 kg.

The pitch was analyzed for the following parameters:

- softening temperature according to the Ring and Rod method, GOST 9950;

- content of α ₁ -fraction insoluble in quinoline, GOST 28572;

- content of α-fraction insoluble in toluene, GOST 7847;

- ash content, GOST 7846;

- volatile emissions, GOST 9951.

The obtained results of the analyses are presented below:

- softening temperature according to the Ring and Rod method - 91°C (according to GOST 10200 - 2017: 85-92°C);

- content of α ₁ -fraction insoluble in quinoline - 12 wt.% (according to GOST 10200 - 2017: no more than 14 wt.%);

- content of the α-fraction insoluble in toluene - 33 wt.% (according to GOST 10200-2017: not less than 31 wt.%);

- ash content - 0.26% (according to GOST 10200 - 2017: no more than 0.3%);

- volatile content - 52% (according to GOST 10200 - 2017: no more than 57%).

Example 2.

1.0 kg of medium-temperature pitch (fr. 420°C+) was placed in reactor P and kept there at a temperature of 280°C and an excess pressure of 0.1 MPa without air access for 10 hours.

After this, air heated to 280°C in the amount of 270 liters was uniformly supplied to reactor R through valve B6 (pos. 17) from cylinder B2 (pos. 18) over the course of 9.5 hours. After this, the pitch remained in the reactor at the same temperature and an excess pressure of 0.1 MPa for another 30 minutes.

The oxidation exhaust gases were continuously analyzed, and the pitch distillate was collected in receiver PR2.

After this, the temperature in reactor P is sharply lowered to 220-230°C and the reactor is unloaded and the material balance is calculated as described above in the section on the description and operating principle of the laboratory setup.

Amount of oxidation gases formed: 0.20 kg.

The amount of pitch distillate formed: 0.25 kg.

The amount of electrode pitch formed: 0.55 kg.

The pitch was analyzed for the following parameters:

- softening temperature according to the Ring and Rod method, GOST 9950;

- content of α ₁ -fraction insoluble in quinoline, GOST 28572;

- content of α-fraction insoluble in toluene, GOST 7847;

- ash content, GOST 7846;

- volatile emissions, GOST 9951.

The obtained results of the analyses are presented below:

- softening temperature according to the Ring and Rod method - 92°C (according to GOST 10200 - 2017: 85-92°C);

- content of α ₁ -fraction insoluble in quinoline - 11 wt.% (according to GOST 10200 - 2017: no more than 14 wt.%);

- content of the α-fraction insoluble in toluene - 32 wt.% (according to GOST 10200-2017: not less than 31 wt.%);

- ash content - 0.29% (according to GOST 10200 - 2017: no more than 0.3%);

- volatile content - 54% (according to GOST 10200 - 2017: no more than 57%).

Example 3.

1.0 kg of medium-temperature pitch (fr. 420°C+) was placed in reactor P and kept there at a temperature of 380°C and an excess pressure of 2.5 MPa without air access for 3 hours.

After this, air heated to 380°C in the amount of 160 liters was uniformly supplied to reactor R through valve B6 (pos. 17) from cylinder B2 (pos. 18) over the course of 2.5 hours. After this, the pitch remained in the reactor at the same temperature and an excess pressure of 2.5 MPa for another 30 minutes.

The oxidation exhaust gases were continuously analyzed, and the pitch distillate was collected in receiver PR2.

After this, the temperature in reactor P is sharply lowered to 220-230°C and the reactor is unloaded and the material balance is calculated as described above in the section on the description and operating principle of the laboratory setup.

Amount of oxidation gases formed: 0.25 kg.

The amount of pitch distillate formed: 0.22 kg.

The amount of electrode pitch formed: 0.53 kg.

The pitch was analyzed for the following parameters

- softening temperature according to the Ring and Rod method, GOST 9950;

- content of α ₁ -fraction insoluble in quinoline, GOST 28572;

- content of α-fraction insoluble in toluene, GOST 7847;

- ash content, GOST 7846;

- volatile emissions, GOST 9951.

The obtained results of the analyses are presented below:

- softening temperature according to the Ring and Rod method - 89°C (according to GOST 10200 - 2017: 85-92°C);

- content of α ₁ -fraction insoluble in quinoline - 13 wt.% (according to GOST 10200 - 2017: no more than 14 wt.%);

- content of the α-fraction insoluble in toluene - 31 wt.% (according to GOST 10200-2017: not less than 31 wt.%);

- ash content - 0.28 wt.% (according to GOST 10200 - 2017: no more than 0.3%);

- volatile content - 55% (according to GOST 10200 - 2017: no more than 57%).

From the obtained results (examples 1-3), it is evident that the obtained required product (electrode pitch) fully complies with the electrode pitch parameters according to the Interstate Standard GOST 10200-2017 "Electrode Coal Pitch. Technical Conditions".

Example 4.

Using the computer software "Petro - Sim 6.0", a complete process flow diagram for the operation of a plant for producing grade "B" electrode pitch from coal tar was calculated, including the following process stages:

Stage 1. Preparation of coal tar for rectification.

Stage 2. Primary rectification of coal tar before feeding it to the main stage of rectification.

Stage 3. Rectification of coal tar to obtain narrow fractions and

medium-temperature pitch.

Stage 4. Obtaining grade "B" electrode pitch.

Stage 5. Cooling, granulation and packaging.

The production of grade "B" electrode pitch from medium-temperature pitch obtained by rectification of coal tar is characterized by the following data:

• softening temperature 85 - 92°C (using the Ring and Rod method);

• yield of substances insoluble in toluene, not less than 31 wt.%;

• yield of volatile substances no more than 57 wt.%.

The yield of grade "B" electrode pitch reaches 87-89 wt.% of the initial medium-temperature pitch.

The characteristics of the original coal tar are given in Table 6.

In terms of physicochemical properties, high-melting electrode pitch grade "B" - a product of processing the above-mentioned resins - must comply with the requirements and standards specified in Table 7.

The material balances of the process are given in Tables 8-10.

To compare the yield of electrode pitch according to our invention and the prior art (Examples 1 and 2 of Russian Federation Patent No. 2659262, which specifies a yield of 33.6-33.8 wt.% for high-temperature binder pitch from soft petroleum pitch—a heavy fraction of pyrolysis resin with a base temperature of 230°C—we calculated the yield of petroleum electrode pitch from similar raw materials according to our invention using the Petro-Sim 6.0 computer software. The calculation results are presented in Table 11.

From Table 11 it can be seen that according to our invention the yield of electrode pitch significantly exceeds the similar yield of the prototype: 53.8 wt.% according to our invention instead of 33.6-33.8 wt.% for the prototype.

Brief description of the drawings.

Fig. 1-3 show drawings for the present invention application.

Fig. 1 shows a diagram of the prototype (Patent of the Russian Federation No. 2659262, 2017) - a basic technological diagram for obtaining a high-temperature petroleum binder pitch.

The following designations of equipment (blocks) and process flows are used: 1 - pyrolysis resin preparation block, 2 - tubular furnace, 3 - mixer, 4 - flow reactor, 5 - separator, 6 - reactor-separator, 7 - cooling, condensation and separation system for low-molecular heat treatment products.

Streams: I - heavy pyrolysis resin into the preparation unit, II - light fraction of pyrolysis resin, III - soft petroleum pitch (heavy fraction of pyrolysis resin with a temperature of about 230°C), IV - soft pitch heated in the furnace, V - reaction mass from the mixer into the flow reactor, VI - reaction mass from the flow reactor into the separator; VII - distillation of low-molecular products of heat treatment of the flow reactor; VIII - reaction mixture from the separator; IX - reaction mixture from the separator for circulation, X - reaction mixture from the separator to the reactor-separator, XI - natural gas, XII - target petroleum high-temperature binder pitch, XIII - gas-steam mixture of low-molecular heat treatment products, XIV - hydrocarbon gases, XV - gasoline, XVI - light distillate with a boiling point below 350°C, XVII - heavy distillate with a boiling point of 350-450°C.

Fig. 2 shows a basic flow chart of the installation for producing high-melting electrode pitch grade "B" according to the present invention application.

The following designations of equipment (blocks) and process flows are used:

Blocks: 8 - Block for preparing resin or its fractions for processing, 9 - Block for primary resin rectification, 10 - Block for heat exchange for heating stripped resin before the vacuum block, 11 - Block for vacuum rectification of stripped coal tar or pyrolysis resin, 12 - Block for polymerization and thermal oxidation reactors; 13 - Block for receiving and granulating high-melting electrode pitch of grade "B", 14 - Block for cooling and absorption of oxidation gas vapors from reactors for producing high-melting electrode pitch of grade "B", 15 - Block for afterburner PD-104.

Streams: A - stream of raw coal tar or pyrolysis tar to the preparation unit, B - stream of fresh water, V - stream to treatment facilities, G - stream of tar prepared for primary distillation, D - stream of light fraction fr. 80-170°C, E - stream of stripped tar to the heat exchange unit, Zh - stream of stripped tar heated in P-102 to the vacuum distillation unit, Z - stream of phenol fraction fr. 170-210°C, I - stream of naphthalene fraction fr. 210 - 230°C, K - stream of 1-st anthracene fraction fr. 280-360°C, L - stream of 2-nd anthracene fraction fr. 320-420°C, M, N - streams of absorption fraction fr. 230-270°C, O - flow of medium-temperature pitch fr. 420°C+ for thermal-oxidative polymerization, P - flow of high-melting electrode pitch grade "B" into the receiving and granulation unit, R - flow of target granulated high-melting electrode pitch grade "B", S - flow of steam-gas mixture with pitch distillate vapors, T - flow of oxidation gases into the PD-104 afterburner, U - air flow, F - flow of pitch distillate.

Fig. 3 shows a diagram of a laboratory setup for conducting experiments on the conversion of feedstock (medium-temperature coal tar or pyrolysis pitch) - examples 1-3.

The specification of the equipment used in this installation is given in Table 4.

Claims (7)

1. A method for producing high-melting grade "B" electrode pitch, consisting of the stages of receiving coal tar or pyrolysis resin, preparing raw materials for processing - removing water and desalting, heating the raw materials, primary rectification of the raw materials, vacuum rectification of the stripped resin, converting medium-temperature pitch in column-type thermal oxidation and polymerization reactors into pitch of the required quality, receiving grade "B" electrode pitch and feeding it to a belt cooler-granulator, cooling the pitch in the belt cooler-granulator, absorbing pitch distillate from the vapors of oxidation gases obtained in the thermal oxidation and polymerization reactors for producing grade "B" electrode pitch, characterized in that isothermal reactors with built-in heat exchange and mixing devices are used in the block of polymerization reactors R-101 and thermal oxidation reactors R-102, wherein both reactors R-101 and R-102 can be used as oxidation reactors with air supply as an oxidizing agent in each of them with the possibility of obtaining the specified qualities of the resulting high-melting electrode pitch, there is a unit for washing coal tar or pyrolysis resin and filtering it before feeding it to primary rectification, there is a rectification unit designed to separate the resin flow into marketable products, consisting of two columns with heaters, circulation and washing irrigation, air coolers with rotation regulators and louvers of factory shelters, a hydro-ejector vacuum creation system is used, consisting of a hydro-ejector and a separator - a separator on the vapor and liquid line after the rectification column, a nitrogen breathing system is used, consisting of a system for supplying nitrogen to the polymerization and thermal oxidation reactors and removing nitrogen to maintain pressure in the process equipment with the removal of excess nitrogen-hydrocarbon medium for disposal in the afterburner, as an absorbent for absorbing pitch distillate and To separate it from oxidation gases, an absorption fraction of 230-270°C is used - one of the commercial products of the plant; due to the use of a hydrocirculation system for creating a vacuum and nitrogen breathing, hydrocarbon emissions into the atmosphere are excluded. 2. The method according to paragraph 1, characterized in that the process of polymerization and thermal oxidation of raw materials in the R-101 reactor is carried out at a temperature of 280-380°C, excess pressure in the reactors depending on the quality of the raw material flow and the required commercial qualities of the finished product in the range of 0.1-2.5 MPa, a total residence time in the reaction zone in both reactors R-101 and R-102 of 6-20 hours in total with regulation of the temperature profile along the height of the reactors, for which purpose circulation circuits of the coolant/coolant are provided to remove excess heat of reaction and supply the missing one, which makes it possible to eliminate the uncontrollability of the process, with a specific air consumption of 160-270 ^m3 per 1 ton of raw material mixture. 3. The method according to paragraphs 1 and 2, characterized in that the design of the thermal oxidation and polymerization reactors allows the feedstock flow to be directed both from the bottom up and from the top down, while feeding the flow from the top down and removing the thermally oxidized product from the bottom of the reactors allows for the elimination of internal recirculation of the reaction flow and its uncontrolled overoxidation. 4. The method according to paragraph 1, characterized in that in order to obtain high-quality pitch suitable for use as a binder in the graphite materials industry, a unit is provided for washing coal tar or pyrolysis resin or their fractions and filtering them before feeding them to primary rectification, a second stage of self-cleaning filters is installed, high-quality dehydration of the resin and removal of mechanical impurities from coarse particles is carried out, additional high-quality dehydration and removal of salts and acids from the resin significantly reduces corrosion of process equipment and pipelines, and also prevents the ingress of corrosion products into the commercial product, which ensures long-term trouble-free operation of the process equipment and the commercial quality of the resulting product. 5. The method according to paragraph 1, characterized in that the stripped coal tar or pyrolysis resin after the heat exchange unit, where it is heated to a temperature of 380-405°C, enters the resin rectification unit for obtaining narrow fractions, including two vacuum rectification columns with heaters, circulation and washing refluxes, refrigerators and heat exchangers for cooling the vapors of the fractions, a vacuum rectification column K-102 for obtaining the II anthracene fraction of fr. 320-420°C and medium-temperature pitch of fr. 420°C+ at a column pressure of 250-350 mmHg, a temperature in the upper and lower parts of the column of 250-270°C and 290-340°C, respectively, and a vacuum distillation column K-103 to obtain a phenol fraction of 170-210°C, a naphthalene fraction of 210-230°C, an absorption fraction of 230-270°C and the 1-st anthracene fraction of 280-360°C at a column pressure of 100-250 mmHg, a temperature in the upper and lower parts of the column of 125-130°C and 250-280°C, respectively, the use of vacuum in the main process columns reduces the heating temperature, eliminates the loss of fraction quality due to coking and improves the energy characteristics of the process. 6. The method according to paragraph 1, characterized in that in order to maintain the constancy of the pressure of the distillation process of the stripped resin, a hydro-ejector vacuum creation system is used, consisting of a hydro-ejector EZh-101 and a separator S-103 - a separator on the line of vapors and liquids after the distillation column K-103, after cooling in X-101 the uncondensed gases of the separator S-102 with a temperature of 20-40°C and a pressure of 100-250 mm Hg. are fed to the input of the low-pressure chamber of the hydroejector EZh-101, where they are captured by the flow of active liquid, which is steam condensate from the separator S-102 and desalinated water supplied by the circulation pump, and then the gas-liquid mixture is fed for separation to the separator S-103, from which the degassed steam condensate as a working flow, fed for cooling to the water cooler X-102, and then from the discharge of the active liquid pumps is fed to the input of the high-pressure chamber of the hydroejector EZh-101. 7. An installation for implementing the method for producing high-melting electrode pitch of grade "B" according to paragraph 1, consisting of a unit for receiving coal tar or pyrolysis resin or their fractions, a heat exchange unit, a unit for preparing resin for processing (8) - removing water and desalting, a unit (10) for heating raw materials and maintaining the temperature in distillation columns, apparatuses and pipelines, a unit for primary rectification of raw materials (9), a unit for vacuum rectification of stripped resin (11), a unit for polymerization and thermal oxidation of raw materials (12), consisting of reactors R-101 and R-102, units for supplying and removing heat, mixing, a unit for maintaining a constant temperature and heating process pipelines and pumps pumping resin and pitches, a vacuum creation system, a unit for receiving electrode pitch of grade "B" and feeding it to a belt cooler-granulator, a belt cooler-granulator, a nitrogen breathing system and capturing vapors of a nitrogen-hydrocarbon medium, a system for cooling and absorbing pitch distillate from vapors of oxidation gases from polymerization and thermal oxidation reactors for obtaining grade "B" electrode pitch, a high-temperature oil coolant circuit, a circuit for providing heating for process equipment, pipelines and pumping equipment, a process furnace for heating stripped resin, air cooling devices for cooling process flows, characterized in that isothermal reactors are used in the distillation column in the block of reactors for polymerization and oxidation of raw materials, there is a block for washing coal or pyrolysis resin and filtering them before feeding them to primary distillation, there is a distillation unit designed to separate the reaction stream into intermediate and commercial products, consisting of two vacuum columns with heaters, circulation and washing irrigation, air coolers with rotation regulators and louvers of plant shelters, contains a hydro-ejector system for creating a vacuum, consisting of a hydroejector and a separator-separator on the line of vapors and liquid after the distillation column, a nitrogen breathing system, which consists of a system for supplying nitrogen to the polymerization and thermal oxidation reactors and removing nitrogen to maintain pressure in the process equipment with the removal of excess nitrogen-hydrocarbon medium for disposal in the block (15) of the afterburner PD-104, an additionally equipped convection chamber for heating, using the excess heat of the flue gases in it, the air supplied to it through heating coils for the oxidation of pitch in the reactors R-101 and R-102, an absorption fraction of 230-270 ° C is used as an absorbent for absorbing pitch distillate and separating it from oxidation gases - one of the commercial products of the plant, contains an absorption column K-104 and a separator S-104 for capturing the remaining liquid - a mixture of pitch distillate and the absorption fraction, a unit for receiving and granulating high-melting electrode pitch of brand "B" (13), wherein the heat exchange unit for heating the stripped resin (10) is located in front of the vacuum rectification unit (11) of the stripped coal tar or pyrolysis resin, wherein the resin preparation unit (8) is configured to feed raw coal tar or pyrolysis resin or their fractions into it by stream A and fresh water by stream B and to remove corrosive components and water from the coal tar or pyrolysis resin or their fractions to treatment facilities by stream V; the primary resin rectification unit (9) is configured to feed heated prepared resin or its fractions into it by stream G and to separate the light fraction of fr. 80-170°C by stream D; the heat exchange unit (10) is configured to feed stripped coal tar or pyrolysis resin into it by stream E and to heat it to a temperature of 380-405°C; the coal tar or pyrolysis resin rectification unit (11) is configured to obtain narrow fractions - the 1st anthracene fraction fr. 280-360°C stream K, the 2nd anthracene fraction fr. 320-420°C stream L, the phenol fraction fr. 170-210°C stream Z, the naphthalene fraction fr. 210-230°C stream I, the absorption fraction fr. 230-270°C stream M and the medium-temperature pitch fr. 420°C stream O; the thermal-oxidative reactor R-101 of the polymerization and thermal-oxidation reactor unit (12) is configured to receive medium-temperature pitch from the vacuum rectification unit (11) via stream O and then feed it to thermal-oxidative polymerization in the temperature range of 280-380°C; The R-101 reactor is designed to allow movement of a medium-temperature pitch flow. 420°C from top to bottom, the PD-104 afterburner unit (15) is configured to supply air with a temperature of more than 300°C by flow U, pumped by air compressors, countercurrently into the R-101 reactor, the R-101 reactor is configured to oxidize medium-temperature pitch with air in the temperature range of 280°C - start, 340-365°C - optimal temperatures for oxidation and thermal polymerization of pitch, the R-101 reactor is also configured to maintain excess pressure in the range from 0.1 to 2.5 MPa in the reaction zone depending on the quality of the raw material flow and the required commercial qualities of the finished product, the second-stage thermal-oxidative polymerization reactor R-102 is configured to receive a stream of thermally oxidized polymerizate with a temperature of 310-395°C from the R-101 reactor and subsequent oxidation of medium-temperature pitch with air at an average temperature in the R-102 reactor 340-370°C, the R-102 reactor is configured to maintain excess pressure in the range from 0.1 to 2.5 MPa depending on the quality of the feedstock stream and the required commercial qualities of the finished product; the absorption column of the unit for cooling and absorbing oxidation gas vapors from the reactors for producing grade "B" electrode pitch (14) is configured to receive a vapor-gas mixture with pitch distillate vapors by stream C from the reactors of the polymerization and thermal oxidation reactor unit (12), the unit (14) is configured to receive the absorption fraction of fr. 230-270°C by stream H to renew the absorbent composition; the bottom of the absorption column K-104 of the unit (14) is configured to remove pitch distillate of fr. 260-420°C together with the absorption oil by the F stream, by a pump without separation gradually after cooling, with a partial return to the K-104 absorption column and the removal of the excess into the park, the top of the K-104 absorption column is designed with the possibility of removing oxidation gases with a temperature of up to 130°C into the S-104 separator for capturing the remaining liquid - a mixture of pitch distillate and absorption fraction, the PD-104 afterburner of the block (15) is designed with the possibility of burning a mixture of pitch distillate and absorption fraction; the unit for receiving and granulating high-melting electrode pitch of grade "B" (13) is designed with the possibility of feeding the obtained electrode pitch of grade "B" by flow P from the bottom of the reactor R-102 of the polymerization and thermal oxidation reactor unit (12) through the holding tank E-103 in a liquid state with a temperature of 180-200°C for cooling to ambient temperature, as well as granulation and feeding for packaging into containers with subsequent weighing by flow P.