RU2752174C1 - Method and device for producing binding electrode pitch - Google Patents

Abstract

FIELD: binder electrode pitch production.SUBSTANCE: invention relates to a method for producing a binder electrode pitch, including mixing crushed coal with a solvent, dissolving the resulting mixture to obtain a coal extract, distilling the coal extract to obtain the final product - a binder pitch. The method is characterized by the fact that the dissolution of coal is carried out for 45-90 minutes at a temperature of 380-450°C, while a mixture of coal tar and heavy gas oil of catalytic cracking is used as a solvent, and distillation is carried out for 20-40 minutes at a temperature of 270-300°C with condensation and removal of light fractions. To implement the proposed method, a device is proposed, consisting of a heat-insulated housing equipped with heating elements, inside which a tubular coil (flow reactor) and a distiller are sequentially located. Coil diameter is 30-50 mm, coil length is 20-40 m.EFFECT: obtaining a more environmentally friendly and more affordable binder electrode pitch for anodes with characteristics close to those of coal tar pitch, as well as increasing productivity during its production.6 cl, 1 dwg, 2 tbl

Description

Technology area

The invention relates to the field of coal chemistry, to technologies for extracting hydrocarbons from coal, namely, to obtain a mixture of heavy aromatic hydrocarbons, which is an analogue of coal tar pitch obtained by the traditional technology of coking coal, and can be used in the production of anode mass and baked anodes for aluminum electrolysers. The invention also includes a device for implementing a method for producing a binder pitch for anodes by the method of coal dissolution.

State of the art

There are known methods for producing electric coal products - electrode coke, a binder for the anode mass of carbon electrodes ("New binder for heat-resistant materials for metallurgical purposes", Bazegsky A. E., Shkoller MB, Ferrous metallurgy, 2014, No. 6 (1374) , S. 6-11, patent GB1472810 (A), IPC C10B55 / 00, C10B57 / 04, C10C3 / 00, C10G1 / 04, C10L5 / 00; C10L9 / 02, published 11.05.1977, patent GB1474100 (A), IPC C10G01 / 00, C10G01 / 04, published on 05/18/1977, patent DE2944689 (A1), IPC C10G1 / 04, published on 05/07/1981).

The methods are mixing finely ground coal or coal, subject to special activation methods (mechanical activation), with hydrocarbon, mainly condensed aromatic solvents, for example, anthracene oil, in a ratio of 1: 1-1: 3, followed by dissolution (thermal dissolution, liquefaction, extraction) when heated in the range from 300 to 500 ° C and at elevated pressure, further separation from the resulting product of the utilized ash fraction and the isolation of the target product - coal pitch - by filtration or distillation.

The disadvantage of the known methods is that they are aimed at obtaining products that are fundamentally different in their functional purpose, namely, liquid hydrocarbon products of various compositions used as various fuels, taphole mass for blast furnaces, raw materials for electrode coke, coking additives, and others.

It is known that the organic mass of coal is an irregular polymer, which depolymerizes under conditions of high temperatures and pressures with the formation of a large number of fragments of various structures and properties. The role of hydrogen used in hydrogenation processes is to stabilize the fragments obtained during the thermal destruction of the original coal matter and to reduce the content of oxygen, nitrogen and sulfur [Lipovich V.G., Kalabin G.A., Kalechits I.V. and other Chemistry and coal processing. M., Chemistry, 1988 - 336 S.] Stabilization of fragments is necessary to increase the yield of liquefaction products and reduce the formation of solid residues. Molecular hydrogen and solvents with high donor activity can be used as stabilizers.

Closest to the claimed invention is a method for dissolving coal using a rubber material (application US 2012/0091043 A1, IPC C10G1 / 04, published on April 19, 2012). The method is the dissolution of coal in solvents containing hydrogenated vegetable oil and a solvent derived from coal. Hydrogenated vegetable oil is a hydrogen donor in the decomposition reactions of large coal molecules. A crushed rubber material is also added to the slurry of coal and solvent, which can act as a hydrogen donor and form pitch substances insoluble in quinoline.

The disadvantage of the prototype is the use of hydrogenated vegetable oil, which requires a hydrogenation unit and large volumes of vegetable oil, which is economically unprofitable on the scale of large-scale industrial production.

Because in the published printed literature close sources to the claimed device were not found, the applicant below provides links from the Internet to the closest analogs and the prototype of the device.

Known devices, for example tubular furnaces such as GN, GN2 for high-temperature heating of oil products in the process of their processing (http://www.splyse.ru/offer/offer_55598.html). If necessary, hydrocarbon gases, water, inert gas can be heated. The disadvantage of tubular furnaces is the risk of uneven heating of the surface of the pipes and their coking during operation, as a result of long-term equipment repair in case of failure. (MA Berlin. "Wear of the main elements of tubular furnaces." P. 6, items 3 and 4. Publishing house "Nedra", Moscow, 1964).

As the closest analogue (prototype) of the proposed device, it is possible to consider a technological furnace ANU-0.8 (NPP NOUprom LLC nouprom-npz.ru, (http://nouprom-npz.ru/katalog-produktsii/pechi-nagreva-nefti -nefteproduktov-masla / anu-0-8 /) for heating liquid hydrocarbons, consisting of a casing with a radiant chamber, single-flame heating, a tubular coil located in the chamber and a casing cooling fan. pressure in the coil up to 18 atm The main disadvantage, like all tube furnaces with flare heating, is the uneven heating of pipes and their coking, with failure and long-term repair.

Disclosure of invention

The objective of the invention is to expand the raw material base and expand the technological capabilities for obtaining a binder electrode pitch for anodes and reducing the cost of its production.

The technical result is to obtain a more environmentally friendly and economical binder electrode pitch for anodes with characteristics close to the characteristics of coal electrode pitch, as well as to increase productivity during its production. Obtained by the described method, the binder electrode pitch for anodes can replace coal tar pitch obtained by the traditional technology of coking coal, in the production of anode mass for aluminum electrolyzers.

The characteristics of the binder for coal tar pitch include:

- softening temperature according to Mettler 110-130 ° С,

- the content of substances insoluble in toluene 25-45%, substances insoluble in quinoline 3-15%,

- coke residue at 550 ° С not less than 45%.

The technical result is achieved in that the method for producing a binder electrode pitch includes mixing crushed coal with a solvent, dissolving the resulting mixture with the release of coal extract, subsequent distillation of the coal extract to obtain the final product - a binder pitch, according to the claimed invention, the dissolution of coal is carried out for 45-90 minutes at a temperature of 380-450 ° C, and a mixture of coal tar and heavy gas oil of catalytic cracking is used as a solvent, while distillation is carried out for 20-40 minutes at a temperature of 270-300 ° C.

The achievement of the claimed technical result is facilitated by the following features:

- heavy catalytic cracking gas oil can be subjected to preliminary heat treatment for 15-30 minutes at a temperature of 360-420 ° C, and distillation at 270-300 ° C for 15-30 minutes.

- can use coal grade "GZh" or "Zh", crushed to a particle size of no more than 0.25 mm, and its share in the mixture with the solvent can be 30-35% of the mass.

- the proportion of coal tar in the solvent can be 50-100% of the mass, the rest is heavy catalytic cracking gas oil.

The technical result is also achieved by the fact that in a device for producing a binder electrode pitch, containing a housing, in the lower part of which there are heating elements, and in the middle part of which a tubular coil and a distiller are sequentially located, according to the claimed invention, the heating elements are made of electric heating coils, and the diameter the coil is 30-50 mm, while the length of the coil is 20-40 m.

Brief Description of Drawings

FIG. presents the inventive device for producing a binder pitch.

Implementation of the invention

Dissolution of coal is carried out for 45-90 minutes at a temperature of 380-450 ° C, and a mixture of coal tar and catalytic cracking heavy gas oil is used as a solvent, while distillation is carried out for 20-40 minutes at a temperature of 270-300 ° C.

The use of a mixture of coal tar and catalytically cracked heavy gas oil dissolves the organic matter of the coal. Coal tar contains a large amount of hydrogen-donating organic compounds. The coal radicals from thermal cracking are stabilized by mobile hydrogen from the coal tar, preventing the radicals from recombining with each other. Heavy catalytic cracking gas oil acts as a diluent and dispersion medium for coal and its solvolysis products.

Preliminary heat treatment of heavy catalytic cracking gas oil for 15-30 minutes at a temperature of 360-420 ° C promotes the processes of enlargement of hydrocarbon molecules in the gas oil, and distillation at 270-300 ° C for 15-30 minutes helps to remove the lightest hydrocarbons. The gas oil heat treatment process can be carried out using the apparatus described in this application.

Coal of grades "GZh" and "Zh" has an optimal level of volatile substances, which contributes to the achievement of the required qualities of the binder pitch. Grinding coal to a particle size of no more than 0.25 mm contributes to a more complete course of coal depolymerization reactions with the participation of a solvent due to the formation of a large specific surface area of coal. The use of 30-35% coal in the mixture contributes to the production of a binder pitch with the required softening temperature and viscosity.

The use of a share of coal tar 50-100% in a mixture with heavy catalytic gas oil contributes to the production of a binder pitch with the required softening temperature and viscosity.

A device for producing a binder pitch by the claimed method is proposed, consisting of a housing 1 with thermal insulation 2, in the middle part of which a tubular coil 3 and a distiller 4 are sequentially located, in the lower part of the housing 1 there are heating elements 5.

According to the claimed invention, the heating elements 5 are made of electric heating coils, and the diameter of the coil 3 is 30-50 mm, while the length of the coil 3 is 20-40 m.

The indicated dimensions of the coil 3 make it possible to ensure the constant pressure and temperature of the mixture of coal and solvent along the entire length and along the radial section. The use of mathematical modeling methods showed that with a coil diameter of less than 30 mm and a coil length of more than 40 m, the total residence time of the mixture in the coil will be more than 90 minutes, coking of the mixture at the walls and on the coil bends will occur, which will lead to the device stopping. If the diameter of the coil is more than 50 mm and the length of the coil is less than 20 m, the temperature difference between the mixture, which is located at the walls of the coil, and the mixture, which is located in the center, will increase. In this case, it will be 25 ° C. This uneven temperature distribution can significantly affect the stability of thermal dissolution and the quality of the binder pitch, since the permissible deviation from the required temperature for the reaction of thermal dissolution of coal is 5 ° C. If the coil length is less than 20 m, the total residence time of the mixture in the tubular coil will be less than 45 minutes, the conversion of coal to liquid products will be incomplete and the quality of the binder pitch will be low.

Smooth, in comparison with flare, electric heating by means of heating elements 5, made in the form of electric heating coils, reduces the risks of coking of the coil during operation, and provides increased heating up to 380-450 ° C. Distiller 4, located at the outlet of the tubular coil 3 and associated with it, allows you to obtain a binder pitch of the required quality. The design of the claimed device provides a "soft" mode of heating the working mixture in the coil, excluding local overheating and coking, followed by a stable in time and volume flow of coal extract from the coil for subsequent distillation.

A device for producing a binder electrode pitch by the claimed method operates as follows.

A mixture consisting of 30-35% coal, crushed to a fineness class of less than 0.25 mm, and 65-70% of the solvent is continuously fed by means of a pump into coil 3 and dissolved by the action of heating elements 5. The dissolution of coal is carried out at a temperature of 380 to 450 ° C, pressure from 12 to 20 atmospheres, created by the vapors of the reaction mass. After leaving coil 3, the reacted mixture goes directly to distiller 4, where, due to a sharp release of pressure, distillates are separated with a boiling point of 270-300 ° C and a binder pitch is released in the form of a high-boiling fraction, the light components of the mixture evaporate, and at the bottom of the distiller 4 binder electrode pitch accumulates, which is discharged periodically through the bottom valve. Light distillation products enter a cooled receiver and condense.

Distillation is carried out continuously, and the binding electrode pitch accumulated at the bottom is discharged every 20-40 minutes.

Using the proposed method, a binder electrode pitch is obtained, which has a softening temperature according to Mettler of 110-130 ° C, containing substances insoluble in toluene 25-38%, substances insoluble in quinoline 3-12%, coke residue at 550 ° C not less 45%, and which can be used in the production of anode paste for aluminum electrolyzers.

The invention is illustrated by the examples given in tables 1 and 2.

Examples 1-9 were performed experimentally using the described device, including a tubular coil with a diameter of 40 mm and a length of 30 m.

Examples 10-17 are made on the basis of the created mathematical model of the described device, including a tubular coil, the model allows you to change the section and length of the coil.

Table 1*

Example No. The composition of the mixture, wt% Conditions in the tubular coil Distiller conditions Binder pitch quality indicators Coal / grade KUS THCK T _reac , ° С t _reaction , min T _dist , ° С t _dist , min T _mett , ° С NS., % N / T,% Н / Х,% one 33 / GZH 37 thirty 450 45 280 thirty 115 47 37 10 2 30 / GZH 40 thirty 450 60 280 thirty 118 46 35 nine 3 35 / GZH 40 25 430 90 290 thirty 122 45 36 10 4 35 / GZH 65 0 420 45 270 thirty 112 51 36 12 five 33 / GZH 37 thirty 450 60 250 thirty 108 41 33 7 6 33 / GZH 37 thirty 450 60 280 fifteen 113 42 37 eleven 7 33 / GZH 37 thirty 450 60 280 45 165 53 37 10 eight 33 / GZH 37 thirty 460 60 310 thirty 162 54 36 10 nine 33 / F 37 thirty 450 60 280 thirty 112 46 35 nine

Table 2*

Example No. The composition of the mixture, wt% Parameters / devices Binder pitch quality indicators Coal / grade KUS THCK Coil length, m Coil diameter, mm T _mett , ° С NS., % N / T,% Н / Х,% 10 30 / GZH 40 thirty 24 34 120 48 32 10 eleven 30 / GZH 40 thirty 24 46 121 47 34 nine 12 30 / GZH 40 thirty 36 34 115 48 33 eight 13 30 / GZH 40 thirty 36 46 119 49 35 10 fourteen 30 / GZH 40 thirty 24 25 - - - - fifteen 30 / GZH 40 thirty 24 54 - - - - sixteen 30 / GZH 40 thirty 44 34 110 42 23 6 17 30 / GZH 40 thirty sixteen 34 113 39 21 7

* decoding:

KUS - coal tar; TGKK - Catalytic Cracked Heavy Gas Oil; without TO - TGCC was used without heat treatment; T _reaction , is the temperature in the coil; P is the pressure in the coil; t _reaction , is the residence time of the reaction mixture in the coil; T _dist , is the temperature in the distiller; t _dist , is the residence time in the distiller; T _mett , is the Mettler softening point; NS. - coke residue at 550 ° C; Н / Т - mass fraction of substances insoluble in toluene; Н / Х - mass fraction of substances insoluble in quinoline.

For all examples used coal tar with a density of 1.18 g / cm ³ at 20 ° C, the content of substances insoluble in toluene 7.5%, the content of substances insoluble in quinoline 4%. The original heavy catalytic cracking gas oil had a density of 1.031 g / cm ³ . It was heat treated sequentially in a tubular coil for 15-60 minutes at a temperature of 360-420 ° C, and in a distiller at 270-300 ° C for 15-30 minutes. After heat treatment, the density of the gas oil became equal to 1.07 g / cm ³ at 20 ° C. Coal of grades "GZh", "Zh" was crushed in a crusher and a mill and a fraction of -0.25 mm was isolated by the sieve method. The crushed coal was mixed with the solvent components in the ratios as shown for examples 1-9 in table 1. The prepared mixture of coal and solvent was fed by means of a pump into the coil, preheated to the temperatures indicated for examples 1-9 in the table. reactor with a diameter of 30-50 mm and a length of 20-40 m was 45-90 minutes. After the reactor, the mixture entered the distiller, where, under the action of a sharp drop in pressure, light hydrocarbons evaporated, at the bottom of the distiller, a binding electrode pitch was accumulated, which was discharged after 20-40 minutes.

Tables 1 and 2 show the quality characteristics of the obtained binder electrode pitches for each example 1-17.

An analysis of the results obtained for examples 1-4 and 9, in table 1 and examples 10-13 in table 2, indicates that the binder pitch obtained by the claimed method and using the inventive device has qualitative characteristics that allow it to be used as a binder pitch for anode mass of aluminum electrolyzers.

Example 5 shows that distillation at temperatures below 270 ° C produces a binder pitch with a low softening point and low coke residue.

Example 6 shows that distillation of less than 20 minutes results in a low coke binder pitch.

Example 7 shows that a binder pitch with a high softening point is formed upon distillation for more than 40 minutes.

Example 8 shows that when coal is thermally dissolved in a reactor with a temperature of more than 450 ° C, a binder pitch with a high softening point is formed.

Examples 10-13 indicate that the binder pitch obtained by the inventive method and using the inventive device has quality characteristics that allow it to be used as a binder pitch for the anode mass of aluminum electrolyzers.

Examples 14 and 15 show that when the diameter of the coil is less than 30 mm and the length is more than 40 m, coking of the mixture occurs at the walls and on the bends of the coil, which leads to the device stopping.

Examples 16 and 17 show that with a coil diameter greater than 50 mm and a length less than 20 meters, a binder pitch with a low coke residue is formed.

Claims (6)

1. A method of obtaining a binder electrode pitch, including mixing crushed coal with a solvent, dissolving the resulting mixture to obtain a coal extract, distilling the coal extract to obtain the final product - a binder pitch, characterized in that the dissolution of coal is carried out for 45-90 minutes at a temperature of 380 -450 ° C, while a mixture of coal tar and heavy gas oil of catalytic cracking is used as a solvent, and distillation is carried out for 20-40 minutes at a temperature of 270-300 ° C with condensation and removal of light fractions. 2. A method according to claim 1, characterized in that the catalytically cracked heavy gas oil is subjected to preliminary heat treatment for 15-30 minutes at a temperature of 360-420 ° C, and distillation at 270-300 ° C for 15-30 minutes. 3. A method according to claim 1, characterized in that coal of the “GZh” or “Zh” grade is used, crushed to a particle size of no more than 0.25 mm. 4. The method according to p. 1, characterized in that the proportion of crushed coal in the mixture with the solvent is 30-35% of the mass. 5. The method according to p. 1, characterized in that the proportion of coal tar in the solvent is 50-100% of the mass. 6. Device for producing a binder electrode pitch by the method according to any one of paragraphs. 1-5, containing a housing, in the lower part of which heating elements are located, and in the middle part of which a tubular coil and a distiller are located in series, characterized in that the heating elements are made of electric heating coils, and the diameter of the tubular coil is 30-50 mm, while coil length is 20-40 m.

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