RU2075496C1 - Method of producing petroleum pitch - Google Patents

Abstract

FIELD: petroleum processing. SUBSTANCE: invention concerns methods of producing petroleum pitch applicable as binding agent or impregnating material when preparing various carbon objects. Method of invention consists in mixing thermocracking products with 5-40% (based on raw material for thermocracking) of pyrolysis heavy pitch from monoolefin production with subsequent vacuum distillation of mixture obtained. EFFECT: increased yield and improved quality of pitch. 2 tbl

Description

 The invention relates to methods for producing oil pitch, used as a binder or impregnating material in the manufacture of various carbon products, and can be used in the oil refining industry.

A known method of producing oil pitch by thermal cracking of distillate fractions of secondary origin, followed by vacuum distillation of the distillate cracked residue [1]
The disadvantage of this method is the low density of the pitch, insufficient sintering ability and high sulfur content due to the use of distillates of sulphurous oils. All these factors make it difficult to use cracking pitch in the technology of carbon-graphite materials.

Closest to the proposed method is a method for producing oil pitch, including thermocracking of gas oil fractions of secondary origin, followed by mixing the cracked products with the remainder of the vacuum distillation in a ratio of 1: 100 to 20: 100 [2]
The known method allows to increase the degree of aromatization and sintering properties of oil pitch. However, this method does not allow to obtain oil pitch with satisfactory characteristics and a sufficiently high yield.

 The present invention is aimed at increasing the yield and improving the quality of oil pitch.

 This is achieved by the fact that in the method for producing oil pitch, which includes thermocracking of heavy gas oil fractions or mixtures thereof, followed by mixing cracked products with highly aromatized hydrocarbons and vacuum distillation of the resulting mixture, heavy pyrolysis resin from the production of monoolefins in the amount of 5 to 40% by weight is used as highly aromatized hydrocarbons . from thermal cracking raw materials.

 A heavy pyrolysis resin with a light fractional composition has a high degree of aromatization and at the same time an extremely high reactivity, manifested, for example, in intense coke formation during high temperature heating. Mixing it with cracking products will create optimal conditions for the occurrence of thermopolycondensation reactions, as a result of which the reaction products are enriched in aromatic hydrocarbons, and coking ability increases. Possible coke formation of the highly reactive pyrolysis resin is prevented by the fact that its heat treatment is carried out in the environment of products that have already passed the cracking stage, which for this reason have low reactivity.

 The proposed method is as follows.

Raw materials heavy gas oil fractions of secondary origin or mixtures thereof with extracts of oil origin after heating in heat exchangers are sent to a furnace where, at a temperature of 495 505 ^o C and a pressure of ≈ 2.0 MPa, thermal cracking of the feedstock is carried out. Next, the reaction products are fed into the reaction chamber, where at a temperature of 440 460 ^o C and a pressure of 1.5 to 2.0 MPa carry out additional cracking of the vapor phase. Exiting the reaction chamber, the cracking products are mixed with a heavy pyrolysis resin from the production of monoolefins, added in an amount of 5 to 40% wt. from thermal cracking raw materials. The mixture is fed to evaporators for stripping low boiling fractions. The distillate cracking residue is sent to a vacuum column, where due to the additional stripping of low-boiling fractions, an oil pitch product with the required softening temperature and volatile matter content is obtained.

 To verify the proposed method for producing oil pitch and compare it with the prototype method, experiments were conducted, the results of which are presented by examples and tables.

 Example 1 (prototype).

Raw mix of gas oil catalytic cracking, coking and extracts of selective oil purification, the characteristics of which are given in table. 1, after heating in heat exchangers, they are sent to a furnace, where it is thermally cracked at a temperature of 495-505 ^° C and a pressure of 2.0 MPa. The reaction products are fed into the reaction chamber, where an additional vapor phase cracking is carried out at a temperature of 440,460 ^° C and a pressure of 1.6 MPa. The cracking products leaving the reaction chamber are mixed with the remainder of the vacuum distillation (oil pitch), the characteristics of which are given in Table. 1, in a ratio of 20: 100.

The mixture is fed to evaporators for stripping low boiling fractions. The distillate cracking residue is sent to a vacuum column, where due to the additional stripping of low-boiling fractions, oil pitch of the following quality is obtained:
density, kg / m ³ 1190
coking ability, wt. 48,4
softening temperature, ^o C 86
sulfur content, wt. 2.15
volatile matter content, wt. 69.7
content of α fraction, wt. 3.9
The pitch output was 28% wt.

 Example 2 (the proposed method).

The raw material, similar to example 1, after heating in heat exchangers is sent to the furnace, where at a temperature of 495 505 ^o C and a pressure of 2.0 MPa carry out its thermal cracking. The reaction products are fed into the reaction chamber, where an additional vapor phase cracking is carried out at a temperature of 440,460 ^° C and a pressure of 1.6 MPa. The cracking products leaving the reaction chamber are mixed with the heavy pyrolysis resin from the production of monoolefins (the quality is shown in Table 1). The pyrolysis resin is added in an amount of 5% wt. from thermal cracking raw materials. The mixture is fed to evaporators for stripping low boiling fractions. The distillate cracking residue is sent to a vacuum column, where due to the additional stripping of low-boiling fractions, oil pitch of the following quality is obtained:
density, kg / m ³ 1,2114
coking property, 48.6
sulfur content, wt. 1.9
the yield of volatiles, wt. 70.0
the content of fractions, wt. 5,0
the content of a ₁ fractions, wt. 0.2
softening temperature, ^o C 86.0
The output of the pitch was 30.0 wt.

 Analogously to example 2, experiments were carried out on the implementation of the method within the claimed limits of the amount of added heavy pyrolysis resin. The experimental results are summarized in table. 2.

As can be seen from the table, the proposed method in comparison with the prototype method will increase the yield of oil pitch to 30 -0 34.0% wt. (prototype 28% wt.), as well as improve its quality: the density of the pitch increases, the sulfur content decreases to 1.5 1.9% wt. (prototype 2.15 wt.%), the content of α fractions is increased by 1.3 to 5.4 times compared with the prototype. In addition, the resulting pitch contains a ₁ fraction, while in the pitch obtained by the prototype method, they are absent.

 The use of pyrolysis resin in an amount of less than 5% wt. does not have a significant impact on improving the quality and yield of pitch. The increase in the amount of resin more than 40% wt. can lead to intense coking of the equipment and the production of such a high-temperature pitch that it will be difficult to use.

 Thus, the proposed method will increase the yield and improve the quality of the oil pitch used as a binder or impregnating material in the manufacture of various carbon materials by mixing cracking products with a heavy pyrolysis resin.

Claims (1)

 A method for producing oil pitch, including thermocracking of heavy gas oil fractions or mixtures thereof, followed by mixing cracked products with highly aromatized hydrocarbons and vacuum distillation of the resulting mixture, characterized in that heavy pyrolysis resin is used as highly aromatized hydrocarbons from the production of monoolefins in an amount of 5-40% by weight of raw materials thermocracking.

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