RU2085571C1 - Method of producing petroleum electrode pitch - Google Patents

Abstract

FIELD: petroleum processing. SUBSTANCE: method includes gradual heating of heavy petroleum residues and holding them at thermopolycondensation temperature. Light fractions formed in the course of heating are withdrawn from process, Distinguishing feature of invention is that material is aged by way of heating it from temperature 340-350 C with rate 5-9 C/h to yield pitch with required quality. EFFECT: increased yield of coke, reduced power consumption, and increased reliability of equipment.

Description

 The invention relates to the refining industry and can be used to obtain a petroleum electrode pitch used as a binder or impregnating material.

A known method of producing pitch from oil cracking residues by heat treatment at a temperature of 320-470 ^o C and a pressure of 1-20 atm followed by distillation of light fractions [1]
The resulting pitch is used as a binder and for impregnation in the manufacture of electrodes.

 However, the resulting pitch is not of high enough quality, as it contains many components that are insoluble in quinoline (3-20 wt.).

Closest to the claimed invention is a method for producing oil electrode foam in cubes of periodic action by heating heavy oil cracking residues at a speed of 10-150 ^o C / h, followed by exposure at 350-430 ^o C for 10-600 min [2]
The disadvantage of this method is that when the oil residue is heated at a stated speed to the holding temperature, a layer of coke deposits forms on the cube walls, which reduces heat transfer from the wall and load. This requires additional energy costs to ensure exposure conditions upon receipt of the pitch. In addition, the formation of coke deposits leads to overheating and destruction of the metal of the cube body, an increase in operating costs for cleaning and repairing the cube, and also a decrease in the yield of the target product.

 The invention is aimed at increasing the yield of the pitch, reducing energy consumption, improving the reliability of equipment and reducing operating costs.

This is achieved by the fact that in the method for producing oil electrode pitch in batch cubes by gradually heating heavy oil cracked residues with subsequent exposure to them at a temperature of thermopolycondensation, the exposure is carried out by heating the feedstock from 340-350 ^o C at a rate of 5-9 ^o C / h to obtain a pitch of a given quality.

 Holding the shutter in the claimed mode of heating of the raw material provides equalization of the rates of heat transfer through the cube wall, heat removal from the heating surface and heat distribution throughout the entire volume of the liquid phase of the cube loading.

 Compliance with the mentioned conditions for the preparation of electrode pitch eliminates the risk of overheating of the boundary layer of the product and its excessive decomposition with the accumulation of heavy coke-forming components to a value exceeding the threshold concentration when intense coking of the heat transfer surface is observed. In the latter case, the process is accompanied by a sharp increase in the temperature of the cube wall metal, a drop in pitch output, loss of pitch, loss of raw materials, and an increase in operating costs for cleaning and repairing the cube.

 Under the optimal conditions for the preparation of electrode pitch, the temperature and concentration of group chemical components are equalized over the entire volume of the liquid phase due to mass transfer and the occurrence of thermopolycondensation reactions under isothermal conditions.

 The method is as follows.

The feedstock is heated to 150-170 ^o C, loaded into a cube of periodic action with external heating and heated to 340-350 ^o C at a speed of 30-40 ^o C / h Then hold by heating the raw materials from 340-350 ^o C at a speed of 5-9 ^o C / h to obtain a pitch of a given quality. Light fractions formed during the heating process are removed from the process.

 The proposed method was tested on an industrial coke-cube plant. As raw materials, heavy pyrolysis resin and distillate cracking residue were used (their characteristics are given in the table).

Example 1. The feedstock is heated heavy pyrolysis resin is heated to 170 ^o C and loaded into a cube of periodic action, equipped with gas heating, a capacity of 50 m ³ , up to 340 ^o C the raw material is heated at a speed of 30 ^o C / h Then an exposure is carried out by heating the raw material from 340 ^o C at a speed of 9 ^o C / h for 7 hours. The light fractions formed during the heating process are removed from the process. Get the electrode pitch, the quality indicators of which meet the requirements of the standard: TU 38.301-29-76-95
Softening point, ^o C (KiSh) 78.0
Volatiles yield, 57.8
The content of α-fractions (insoluble in benzene), 29.0
The content of a ₁ fractions (insoluble in quinoline), 2.5
Sulfur content, 0.35
Ash content, 0.08
The output of the pitch was 50 wt. the amount of coke deposition 0.1 wt. The temperature difference between the metal walls of the cube and the load did not exceed 35 ^o C.

Example 2. The feedstock the distillate cracked residue is heated to 350 ^o C as in example 1. The exposure is carried out by heating the raw material from 350 ^o C at a speed of 5 ^o C / h for 11 hours. The resulting light fractions are removed from the process. The quality indicators of the resulting pitch meet the requirements of TU, namely:
Softening point, ^o C (KiSh) 80.0
Volatiles yield, 65
The content of α-fraction, 20
The content of a ₁ fractions, 2.0
Sulfur content, 1.24
Ash content, 0.1
The output of the pitch was 50% wt. the amount of coke deposition 0.13% wt. The temperature difference between the cube wall metal and the load did not exceed 50 ^o C.

 Example 3 (prototype).

The feedstock, similar to example 2, is heated to 170 ^o C and loaded into a cube of periodic action with a capacity of 50 m ³ .

The temperature of the feed is increased to 400 ^° C. with a heating rate of 30 ^° C./h and is maintained at 400 ^° C. for 2 hours. Light fractions formed during the heating process are removed from the process.

The resulting pitch meets the requirements of TU:
Softening point, ^o C (KiSh) 77.0
Volatiles yield, 65.0
The content of α-fraction, 15.7
The content of a ₁ fraction, 6.8
Sulfur content, 1.28
Ash content, 0.12
The output of the pitch was 45 wt. the number of coco deposits 5.0 wt. The maximum temperature difference between the cube wall metal and the load was 150 ^o C.

As can be seen from the examples, the proposed method will increase the yield of pitch by 5 wt. in comparison with the prototype method. The experimental results show a decrease in the number of coke deposits on the walls of the cube to 0.1 0.13 wt. compared with 5 wt. by the prototype method. The onset of intense coke deposition is also evidenced by the increased amount in the pitch of fractions insoluble in the quinoline of α ₁ fractions. In pitch, according to the prototype method, there are 6.8 wt. while the proposed method is 2.0 to 2.5 wt. Reducing coke deposition will allow for better heat transfer from the cube wall to the load, which reduces energy consumption for the pitch production process and increases its yield. In addition, the reduction of coke deposition reduces the temperature difference between the cube wall metal and the load (in the prototype method, the maximum difference reaches 150 ^o C, while in the proposed method only 35-50 ^o C). This will improve the reliability of the cube and reduce operating costs for its cleaning and repair.

Holding at a heating rate of less than 5 ^° C./h will significantly increase the duration of the pitch production process. An increase in the heating rate of more than 9 ^o C / h leads to an increase in the number of coke deposits on the walls of the cube.

 Thus, the proposed method will increase the output of the pitch, reduce energy costs for the process, increase the reliability of equipment and reduce operating costs for repairs.

Claims (1)

A method of producing oil electrode pitch in batch cubes by gradually heating heavy oil cracking residues with subsequent exposure to them at a temperature of thermopolycondensation, characterized in that the exposure is carried out by heating the feedstock from 340 350 ^o С at a speed of 5 9 ^o С / h to obtain pitch given quality.

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