RU2698833C1 - Method of processing fuel oil - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil refining, in particular, to a method of processing fuel oil to obtain light oil products and petroleum pitches, which can be used in various fields of science and engineering. Proposed method comprises thermolysis of fuel oil in flow mode. First, in the coil of the furnace at pressure of 2.0 MPa, temperature of 450 °C in the presence of an additive - a mixture of phenol and urotropin, steam in a mode of recirculation of the obtained mixture through heating in a heat exchanger. Then, light and medium-temperature light oil products are distilled in the reactor, passing through the entire height of the reactor through three layers of catalysts for hydrocracking, hydrofining and reforming. Exiting the reactor, they enter the rectification column, where light oil products and medium-temperature light oil products are divided into light oil products, and heavy oil products - thermolysis resin from the reactor cube - are supplied to the oxidation reactor, where they are oxidised with air oxygen to obtain light hydrocarbon fractions and water vapour, which are cooled in a heat exchanger, enter the separator, and oil from the bottom of the oxidation reactor is fed for granulation.

EFFECT: technical result consists in increase of oil processing depth with production of qualitative light oil products and oil pitch with absence of content of benz(a)pyrene in it.

1 cl, 3 dwg, 2 tbl, 7 ex

Description

The invention relates to the field of oil refining, in particular, to a method for the processing of fuel oil M-100 (GOST 10585-2013) to produce light oil products and oil pitch, which can be used in various fields of science and technology as a replacement for coal oil pitch and can be applied for the production of anode paste, coal and graphite products, structural carbon graphite materials. For many years, attempts have been made in the aluminum and electrode industries to introduce pitches obtained on the basis of petroleum products (heavy oil cracking residues - tars), pyrolysis resins obtained in the production of polyethylene, etc.

Important indicative qualities of the resulting oil pitch is its low ash content, especially the concentration of heavy metals, and the main advantage of oil pitch is that it does not contain carcinogens harmful to human health (3,4-benz (a) pyrenes, etc.). In addition, there are practically unlimited raw materials for the production of oil pitch, however, to date, oil pitch has not been widely distributed due to the low concentration of polycondensed aromatic hydrocarbons, α ₁ and α ₂ fractions, the content of which causes a low C / H ratio, at this results in a lower yield of coke residue. In this case, the softening temperature of isotropic fiber-forming pitch obtained from almost all of the oil residues mentioned above is in the range of 180-220 ° C with a high content of α-fraction, at lower softening temperatures (180 ° C) the content of volatile (γ- fraction) up to 10%, while a low content of the most structured part of the pitch (α-fraction ≈ 20%) is observed, which leads to a decrease in its strength.

Thus, despite the best environmental characteristics of oil pitch, due to the significantly lower content of carcinogenic polycyclic aromatic hydrocarbons, all the above disadvantages do not allow to obtain the anode mass of the required quality in the production of electrode products. In industrial practice, the main consumers of electrode pitch are aluminum plants, which use the practice of mixing coal and oil pitch. So, in US patent No. 5746906 a method for producing a hybrid oil-tar pitch with a softening temperature in the temperature range 107-114 ° C and a low content of surface active hydrocarbons by mixing coal tar pitch with a high softening temperature and oil pitch with a reduced softening temperature in the ratio of 60: 40.

In the patent RU No. 2080418 in the production of the anode mass, a homogeneous mixture obtained by mixing coal tar pitch with oil pitch at a ratio of 19: 1 - 2: 1 is used as a carbon-containing binder.

It should be noted that the correct approach to the selection of starting materials is a complex task of preparing the production to obtain the anode mass. The basic properties of pitch are largely dependent on what oil products they are derived from, many structural and chemical features of the starting products are fundamentally preserved along the entire transformation chain from the primary layer of heavy residues of oil products, etc. The starting material for the production of coal tar pitch is coal tar obtained as a by-product of coal coking. To obtain oil pitch, fiber-forming pitch, pyrolysis resins for the production of ethylene or propylene are mainly used (patents RU No. 2478685, 2415972, 2586135, etc.).

Thus, the output of electrode products depends mainly on the quality of the raw materials. At present, there is practically no scientific substantiation of the requirements for the quality of binders based on refined products. The reason is that they can significantly vary in composition and properties, both from coal tar pitch and among themselves, depending on the raw materials and manufacturing technology. Together, these factors raise the problem of developing the production of oil pitch using alternative raw materials in relation to the used oil residues from the processes of pyrolysis, cracking and visbreaking.

The development of technology for the production of oil electrode pitch in Russia began in the 60s of the last century. These studies were carried out by the Ural Polytechnic and Ufa Petroleum Institutes together with research institutes (BashNII NP, VAMI, GosNIIEP, NIIgrafit, VNIIEI) and industrial enterprises (Omsk, Novoufimsky, Volgograd oil refineries and Ural aluminum plants).

The main task of turning petroleum feedstocks into pitch is a directed controlled change in the group composition of heavy petroleum feedstocks, which should provide the pitch with the necessary physico-chemical, operational properties, taking into account the optimal technology for its processing with carbon fillers.

Currently, the oil refining industry has a relatively wide range of residual heavy crude oil: pyrolysis resin, cracking residue, heavy visbreaking tar residue, heavy gas oil fractions.

It is known that the process of thermolysis of heavy oil residues is a complex physicochemical system having a dual deterministic stochastic nature. The participating substance flows in the process of its thermolysis are, as a rule, multiphase and multicomponent. The resulting system is extremely characterized by the complex effects of their phases and components, however, heavy oil residues are a promising raw material for the production of oil pitch, as they contain condensed aromatic compounds, as well as naphthenic and naphthenoaromatic structures.

According to the flowchart (Fig. 1), methods for producing oil pitch were developed for possible options for producing oil pitch, which are presented in RU patents Nos. 2062285, 2186824, 2085571, 2075496.

In all the methods described in the above patents, the thermolysis of heavy petroleum feedstocks is associated with decomposition and compaction reactions, with the corresponding phase transitions: gas distillate and pitch (bottoms). In this regard, almost all the methods for obtaining pitch in the above patents have the same drawback: excessive energy consumption, a lot of heat is spent on evaporation of the distillates formed in the reactor, which complicates the hardware design of the process. Since in all methods for the production of pitch there is a combination of thermal cracking with vacuum distillation, thermal cracking with thermolysis.

The main disadvantage of oil pitch obtained by the methods described in the above patents is the lack of the required ratio of α and α ₁ fractions. The value of the α-fraction should be at least 27, and the α ₁ fraction should be at least 7. At these values of the α and α ₂ fractions, the resulting peaks have the required sintering ability, mechanical strength, and reduced porosity.

The closest in technical essence is the method of producing oil pitch using averaged fuel oil grade M-40 (GOST 10585-2013), presented in an article by M.O. Andropov, V.V. Beetle, A.N. Tretyakov, R.A. Churkin, V.A. Yanovsky “RESEARCH OF THERMOLYSIS OF THE SIBERIAN AVERAGE FUEL OIL OF BRAND M-40” (Bulletin of Tomsk State University. 2014. No. 382. S. 225-229).

This method presents the thermolysis of fuel oil M-40 to produce gaseous and distillate products and oil pitch. The main disadvantage of this method is that in the information presented there are no basic indicators by which it would be possible to determine the suitability of the resulting oil pitch as a binder in the production of graphite electrodes. For the production of graphite electrodes, binders of strictly regulated quality are required, with a high yield of coke residue, characterized by a certain ratio of α and α ₁ fractions.

Determination of the content of α-fractions (carbenes), as well as β-fractions (resinous-asphaltene part) and γ-fraction (oil-resinous part), provides oil pitch fluidity, plasticity and gives it a binder sintering ability. The content of α ₁ fraction (carboids) plays the role of a coke formation center and affects the formation of a material with isotropic properties under certain technological conditions.

In this work, two quality parameters of the resulting pitch are presented: the softening temperature, which is in the range from 68 to 135 ° C and the coking ability in the range of 54.2-69.6%.

According to the above indicators, it is impossible to judge pitch as a binding component in graphite production, since the above quality indicators of the resulting pitch do not characterize its binding and sintering capabilities. The main component of the binder component is the soluble part of the pitch (α, β, γ-fraction) containing maltens and asphaltenes, which determine the sintering properties of the binder component.

The objective of this work is to develop a technology for the processing of M-100 fuel oil (GOST 10585-2013) with the aim of increasing the depth of oil refining to obtain high-quality light oil products and oil pitch with no benz (a) pyrene content in it.

One of the main methods for the deep processing of fuel oil is the processes of thermal and thermocatalytic cracking. New approaches to the role and purpose of thermal processes make it possible to effectively use each of them. By rationally combining these processes with the selection of technological conditions and selective additives that are most preferable for a particular task, it is possible to obtain specific petroleum products, for example, oil pitch and light petroleum products.

High molecular weight organic compounds predominate in fuel oil, therefore, first of all, high molecular weight hydrocarbons and their derivatives will undergo thermal decomposition. In thermal cracking, decomposition reactions are more likely than dehydrogenation reactions. In this case, coke formation does not take place in the primary cracking reaction.

Of particular importance for unsaturated hydrocarbons are cracking conditions at moderate temperatures and elevated pressures; reactions of their polymerization occur; at elevated temperatures, low pressure contributes to the decomposition of unsaturated into simpler molecules. Under severe process conditions, aromatic hydrocarbons may form from olefins.

The formation of products during the cracking of fuel oil occurs according to a radical chain mechanism through alkyl and benzene radicals according to the following scheme (Fig. 2).

The problem is solved by the proposed method of processing fuel oil M-100 to obtain light petroleum products and oil pitch (Fig. 3), including thermolysis of fuel oil in flow mode, while first in the furnace coil at a pressure of 2.0 MPa, temperature 450 ° C the presence of additives - a mixture of phenol and urotropine in a ratio of 1: 1, in an amount of 0.1-0.25% by weight, taken from the feedstock, water vapor in an amount of 1.5% by weight. in the recirculation mode of the mixture for 30 minutes through heating in a heat exchanger, then in the R-1 reactor at a pressure of 0.6 MPa and a temperature of 430 ° C for 20 minutes, light and medium-temperature light oil products are distilled through the entire height of the reactor through three layer catalysts for hydrocracking, hydrotreating and reforming, leaving the reactor R-1 enter the distillation column, where they are divided into light Nafta-I light oil products (TU 19.20.23-001-15666578-2017) and Nafta-II light-temperature light oil products "(TU 19.20.23-002-156 66578-2017), and heavy petroleum products - thermolysis resin from the cube of the R-1 reactor, enter the P-2 oxidation reactor, where they are oxidized with atmospheric oxygen in an amount of 2.5% vol. at a temperature of 385 ° C, atmospheric pressure for 30-40 minutes, to obtain light hydrocarbon fractions and water vapor, which, when cooled in a heat exchanger, enter the separator, and the oil pitch from the bottom of the R-2 reactor is fed to granulation.

Three layers of heterogeneous catalysts are used as metal complex catalysts: hydrocracking (sulfur-nickel catalyst NiS / Al ₂ O ₃ ), hydrotreating (cobalt-molybdenum catalyst CoMo ₃ / Al ₂ O ₃ ), reforming (bimetal nickel-cobalt-copper NiCoCu / Al ₂ O ₃ ).

The technical result is to obtain light petroleum products and oil pitch with characteristics similar to a coal-tar electrode pitch, but with no benz (a) pyrene and low ash content by thermolysis of M-100 fuel oil.

Thus, the organization of the production of oil pitch based on thermo-destructive processes of new oil residues in the form of M-100 fuel oil will expand the possibilities of increasing the raw material base for producing electrode pitch and at the same time give an additional impetus to solving the problem of deepening oil refining, since along with the sintering additive significant volumes of secondary distillate fractions, the catalytic refinement of which will increase the production of motor fuels.

The proposed technical solution, as a new set of existing features exhibiting a new technical property, meets the criteria of the invention "inventive step"

In the proposed method, thermal condensation, dehydrogenation, cyclization and oxidation of the reaction mixture are carried out in flow-type reactors in a downward flow, which uniformly washes the walls of the reactors, preventing their coking.

Thermolysis of M-100 fuel oil leads to splitting of the structure of paraffin chains, dehydrogenation and cyclization and the formation of flat structures of polycyclic condensed aromatic compounds. Thermolysis at elevated pressure leads to the involvement of most components of the reaction mixture, as well as to a decrease in coke formation due to the steam distillation stage, which allows to bring the oil pitch to a predetermined group composition and softening temperature.

Example 1

Fuel oil M-100 (GOST 10585-2013) according to the technological scheme (Fig. 3), was placed in E-1, from where it was pumped with an N-1 pump into an E-1 ejector, and the complexing additive was urotropine and phenol in an amount of 0, 1% of the mass was fed separately to the E-1 ejector with an N-2 pump, where fuel oil and complexing additive were mixed, then water vapor in the amount of 1.5% of the mass was fed through the E-2 ejector, then the whole reaction mixture was preheated in a heat exchanger T-1 and sent to the furnace P-1, where a temperature of 450 ° C and a pressure of 2 MPa were maintained for 30 minutes. After that, the reaction mixture entered the reactor R-1, where the temperature was maintained at 430 ° C and a pressure of 0.6 MPa when water vapor was supplied in an amount of 5% vol. The residence time of the reaction mixture in the P-1 cube was 20 minutes, during which the reaction medium was divided into gas-vapor, which passed through the entire height of the reactor through three layers of hydrocracking, hydrotreating and reforming catalysts. Then the gas-vapor mixture of hydrocarbons was sent to the distillation column RK-1, where it was divided into the light hydrocarbon fraction "Nafta-I" and the average hydrocarbon fraction "Nafta-II" (Table 1).

The thermolysis resin of M-100 fuel oil from the P-1 cube was supplied to P-2, cooled in a T-1 heat exchanger to a temperature of 385 ° C, where it was oxidized with atmospheric pressure in the amount of 2.5% vol. within 30 minutes. The light hydrocarbon fraction and the resulting water vapor were cooled in a T-2 heat exchanger and entered the C-1 separator. The resulting pitch from the R-2 reactor was poured and analyzed, according to GOST 10200-83 "Coal electrode pitch."

Example 2

The method of processing fuel oil was carried out according to example 1, with the exception of the amount of complexing additives, which is 0.1% of the mass. at the time of oxidation in P-2 for 40 minutes.

Example 3

The method of processing fuel oil was carried out according to example 1, with the exception of the amount of complexing additives, which is 0.175% of the mass. and oxidation time in P-2 30 minutes.

Example 4

The method of processing fuel oil was carried out according to example 1, except for the amount of additive component 0.175% of the mass. and oxidation time in P-2 40 minutes.

Example 5

The method of processing fuel oil was carried out according to example 1, with the exception of the amount of additive component 0.25% of the mass. and oxidation time in P-2 30 minutes.

Example 6

The method of processing fuel oil was carried out according to example 1, with the exception of the amount of additive component 0.25% of the mass. and oxidation time in P-2 40 minutes.

Example 7

The method of processing fuel oil was carried out according to example 1, except for the amount of additive component 0.35% of the mass. and oxidation time in P-2 40 minutes.

The process under all the above technological conditions in example 1, but with the addition of an additive in an amount of 0.35 wt%, leads to the fact that the content of undesirable α ₁ fraction increases in the thermolysis product, and the depth of conversion of the raw material in it leads to the necessary degree conversions of fuel oil. The number of light oil products remains at the same level, with a redistribution: the number of light light oil products "Nafta-I" increases, and the amount of medium-temperature oil products "Nafta-II" decreases, since a high concentration of the additive during the polycondensation leads to an increase in coke formation.

Thus, the proposed method allows to obtain from oil fuel oil pitch, which does not contain benz (a) pyrenes (Fig. 1) and allows you to increase the depth of oil refining up to 80-90% of the mass. (tab. 2). Taking into account the obtained light oil products at the stage of primary oil refining by the method of catalytic liquid-phase oxidative cracking, the yield of which is 59-62% of the mass.

Claims (2)

1. A method of processing fuel oil to obtain light petroleum products and oil pitch, including thermolysis of fuel oil in flowing mode, characterized in that it is first in the furnace coil at a pressure of 2.0 MPa, a temperature of 450 ° C in the presence of an additive - a mixture of phenol and urotropine in a mass ratio 1: 1, in an amount of 0.1-0.25 wt.%, Taken from the feedstock, water vapor in an amount of 1.5 wt.% In the recirculation mode of the mixture for 30 minutes through heating in a heat exchanger, then in the reactor at a pressure of 0.6 MPa and a temperature of 430 ° C for 20 min distillation of light and medium temperature light oil products passing through the entire height of the reactor through three layers of hydrocracking, hydrotreating and reforming catalysts, leaving the reactor, enter a distillation column, where they are divided into light light oil products and medium temperature light oil products, and heavy oil products - thermolysis resin from a cube reactor - enter the oxidation reactor, where they are oxidized with atmospheric oxygen in an amount of 2.5 vol.% at a temperature of 385 ° C, atmospheric pressure for 30-40 minutes, to obtain m light hydrocarbon fractions and water vapor, which are cooled in a heat exchanger, fed to the separator, and petroleum pitch from the bottom of the oxidation reactor is fed to granulation. 2. The method according to claim 1, characterized in that three layers of heterogeneous metal-complex catalysts are used: hydrocracking (nickel-sulfur catalyst NiS / Al ₂ O ₃ ), hydrotreating (co-molybdenum catalyst Co-Mo ₃ / A1 ₂ O ₃ ), reforming (bimetallic nickel-cobalt copper NiCoCu / Al ₂ O ₃ ).

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