CN113755206A

CN113755206A - Temperature and pressure changing operation method in oil system needle coke production process

Info

Publication number: CN113755206A
Application number: CN202111174140.7A
Authority: CN
Inventors: 牛永峰; 唐克; 田振宝; 李雪; 刘芷君
Original assignee: Liaoning Baolai Bio Energy Co Ltd
Current assignee: Liaoning Baolai Bio Energy Co Ltd
Priority date: 2021-10-08
Filing date: 2021-10-08
Publication date: 2021-12-07
Anticipated expiration: 2041-10-08
Also published as: CN113755206B

Abstract

The invention discloses a temperature and pressure changing operation method in the production process of oil-based needle coke, which is characterized by comprising the following steps: s1: the raw material slurry oil is subjected to heat exchange treatment and then enters a pretreatment heating furnace for heating; s2: entering a vacuum tower for vacuum fractionation to obtain top dirty oil, first-line oil, middle-section oil and asphalt oil; s3: the middle oil enters a pressure reduction stripping tower for secondary fractionation, the upper section of the middle oil obtains second-line oil, and the lower section of the middle oil obtains third-line oil; s4: respectively feeding the first-line oil, the second-line oil and the third-line oil into a coking heating furnace and a coking tower for coking reaction to obtain needle coke green coke; s5: and (4) the needle coke is calcined in a calcining rotary furnace to obtain the needle coke. The temperature and pressure changing operation method in the production process of the oil-based needle coke provided by the invention reduces the defects caused by uneven chemical reaction of components with different molecular weights in the slurry oil, and the prepared needle coke has a good length-width ratio and a low thermal expansion coefficient.

Description

Temperature and pressure changing operation method in oil system needle coke production process

Technical Field

The invention belongs to the field of needle coke manufacturing, and particularly relates to a temperature and pressure changing operation method in an oil-based needle coke production process.

Background

The needle coke is a silver gray porous solid, has obvious fiber texture trend, has the characteristics of high crystallinity, high strength, high graphitization, low thermal expansion, low ablation and the like, and is a high-quality raw material for manufacturing graphite electrodes, battery cathode materials and high-end carbon products.

The needle coke can be divided into two types of coal-based needle coke and petroleum needle coke according to different production raw materials, generally, the petroleum needle coke has better performance than the coal-based needle coke, the thermal expansion coefficient is smaller, and the produced electrode material has stronger electric conductivity. At present, the production of domestic oil-based needle coke is mostly carried out on the basis of a delayed coking process, and the production process mainly comprises three stages of raw material pretreatment, delayed coking and calcination. The raw material of the petroleum needle coke is required to be high in short-side chain polycyclic aromatic hydrocarbon content and low in colloidal asphalt content, and the catalytic oil slurry is rich in short-side chain polycyclic aromatic hydrocarbon and is one of excellent raw materials of the oil-system needle coke. However, the catalytic slurry oil has complex components and wide distillation range, and not only has lighter micromolecule substances, but also has heavy-molecular-weight fused aromatic hydrocarbons, in the carbonization process, the micromolecules or overflow systems or liquid phase mobile phases are generated, the alkane content in the micromolecule substances is high, the reaction intensity is accelerated, the expansion of intermediate phases is not facilitated, the fused ring macromolecules need to react at higher temperature and are easily aggregated into large coking particles, so that the catalytic slurry oil needs to be pretreated to reduce light components and macromolecular substances which are not conducive to coking reaction in the slurry oil, and the residual components of the slurry oil are more conducive to the generation of needle coke.

Chinese patent CN201810504927.7 discloses a process for producing needle coke raw oil by filtering catalytic slurry oil and a system thereof, wherein the catalytic slurry oil is pretreated by a filtering-reduced pressure distillation method, and separated to obtain upper-stage oil mainly containing saturated hydrocarbon, middle-stage oil mainly containing polycyclic aromatic hydrocarbon and a small amount of polycyclic aromatic hydrocarbon, and lower-stage oil mainly containing colloid and asphaltene, and the middle-stage oil mainly containing polycyclic aromatic hydrocarbon and a small amount of polycyclic aromatic hydrocarbon enters the next coking stage.

Chinese patent CN201310499281.5 discloses a coking method, raw oil is fractionated by a thermal cracking reactor to obtain upper layer gasoline/diesel oil fraction, middle distillate oil and lower layer heavy distillate oil, the middle distillate oil is put into a delayed coking heating furnace to be heated to reaction temperature, and then is put into a coke tower to be subjected to deep polymerization and cracking reaction to obtain needle coke deposition.

However, the middle-stage oil is still a mixture of aromatic hydrocarbons with various molecular weights, and under the same coking and carbonization process parameters, the chemical reaction is not uniform, the growth and fusion of mesophase spherule are influenced, and the prepared needle coke has the defects of low length-width ratio and high thermal expansion coefficient.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provide the temperature and pressure changing operation method for the production process of the oil-based needle coke, which has uniform coking reaction and good length-width ratio and thermal expansion coefficient of the prepared needle coke.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention provides a temperature and pressure changing operation method in an oil-based needle coke production process, which comprises the following steps:

s1: the raw material slurry oil is subjected to heat exchange treatment and then enters a pretreatment heating furnace to be heated to 400 ℃, so that the heat of each fraction in the production process is fully recovered, and the energy consumption is reduced;

s2: the heated raw material slurry oil enters a vacuum tower for vacuum fractionation, and is sequentially fractionated from top to bottom to obtain top dirty oil, first-line oil, middle-section oil and asphalt oil, wherein the top dirty oil and the asphalt oil are recovered after treatment, and the first-line oil enters a subsequent coking reaction section;

s3: feeding the middle oil obtained in the step S2 into a pressure reduction stripping tower for secondary fractionation, obtaining two-line oil at the upper section and three-line oil at the lower section;

s4: respectively feeding the first-line oil obtained in the step S2, the second-line oil obtained in the step S3 and the third-line oil into a coking heating furnace and a coking tower for coking reaction to obtain needle coke green coke;

s5: and (4) putting the needle coke green coke obtained in the S4 into a calcining rotary furnace for calcining treatment to obtain the needle coke.

Preferably, in S1, the heat exchange process includes the following steps:

s11: exchanging heat between the raw material slurry oil and the line oil to enable the raw material slurry oil to reach 150-160 ℃;

s12: after the raw material slurry oil exchanges heat with the first-line oil, exchanging heat with the second-line oil to enable the raw material slurry oil to reach 260-280 ℃;

s13: and exchanging heat between the raw material oil slurry and the second-line oil, and then exchanging heat between the raw material oil slurry and the third-line oil to enable the raw material oil slurry to reach 290-320 ℃.

Because the temperatures of the first-line oil, the second-line oil and the third-line oil are sequentially increased, the gradual heat exchange and temperature rise of the raw material slurry oil are realized, and the heat recovery is fully realized.

Preferably, in S2, the one-line oil has a boiling point ranging from 160 to 240 ℃ and a pressure ranging from 0.9 to 1.0 MPa.

Preferably, in S2, the distillation point of the middle section oil ranges from 270 ℃ to 340 ℃, and the pressure ranges from 1.0MPa to 1.1 MPa.

Preferably, in S3, the two-line oil has a boiling point in the range of 290-320 ℃ and a pressure in the range of 0.9-1.05 MPa.

Preferably, in S3, the distillation point of the tri-line oil is within the range of 320-340 ℃, and the pressure is within the range of 1.05-1.1 MPa.

Preferably, in S4, the first line oil coking reaction process parameters are: the temperature of the coking heating furnace is 420-450 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.15-1.5MPa, the coking circulation ratio is 0.7-0.8, and the coke charging time is 36-48 h. Before 340 deg.C, the oil is not cracked, and the temp. can be quickly raised to raise its efficiency.

Preferably, in S4, the second-line oil coking reaction process parameters are: the temperature of the coking heating furnace is 435-465 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25-2.5MPa, the coking circulation ratio is 0.8-0.9, and the coke charging time is 30-42 h.

Preferably, in S4, the three-line oil coking reaction process parameters are: the temperature of the coking heating furnace is 450-480 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25-3MPa, the coking circulation ratio is 0.9-0.95, and the coke charging time is 24-36 h.

Preferably, in S5, the calcination process parameters of the needle coke green coke are: the calcination temperature is 1250-1450 ℃, the temperature rising method is to rapidly rise the temperature before 0-480 ℃, the temperature rises at the speed of 2 ℃/min after 480 ℃, and the calcination time is 36-48 h.

Compared with the prior art, the temperature and pressure changing operation method for the production process of the oil-based needle coke provided by the invention has the advantages that the raw material oil slurry is deeply decompressed and separated into the first-line oil, the second-line oil and the third-line oil by using the decompression tower and the decompression stripping tower, compared with the method that the raw material oil slurry can only be separated into the middle-line oil in the prior art, the multi-stage separation of the oil slurry is realized, different temperature and pressure changing operation methods are pertinently adopted in respective coking reactions, the defects caused by uneven coking reactions of components with different molecular weights in the oil slurry are reduced, and the prepared needle coke has a good length-width ratio and a low thermal expansion coefficient.

Drawings

Fig. 1 is a process flow diagram of a temperature and pressure changing operation method in an oil-based needle coke production process, fig. 2 is a schematic flow diagram of pretreatment of S1-S4 raw material slurry oil in an embodiment of the present invention, and fig. 3 is a schematic flow diagram of pretreatment of S4-S5 raw material slurry oil in an embodiment of the present invention.

Wherein, 1, a heating furnace; 2-a vacuum tower; 3-decompression stripping tower; 4-a coking heating furnace; 5-a coking tower; 6-calcining rotary furnace.

Detailed Description

For a better understanding of the present invention, specific embodiments thereof are described in further detail below with reference to the accompanying drawings.

Example 1

As shown in the attached

drawings

1, 2 and 3, the temperature and pressure changing operation method in the production process of the oil-based needle coke comprises the following steps:

s1: the raw material slurry oil is subjected to heat exchange treatment and then enters a pretreatment heating furnace 1 to be heated to 400 ℃, wherein the heat exchange treatment comprises the following steps: s11: exchanging heat between the raw material slurry oil and the first-line oil to enable the raw material slurry oil to reach 150-160 ℃; s12: after the raw material slurry oil exchanges heat with the first-line oil, exchanging heat with the second-line oil to enable the raw material slurry oil to reach 260-280 ℃; s13: after the raw material oil slurry exchanges heat with the second-line oil, the raw material oil slurry exchanges heat with the third-line oil, so that the raw material oil slurry reaches 290-320 ℃;

s2: the heated raw material slurry oil enters a decompression tower 2 for decompression fractionation, and fractionation is carried out from top to bottom in sequence to obtain top dirty oil, first-line oil, middle-section oil and asphalt oil; wherein the range of the distillation point of the first line oil is 160-240 ℃, and the pressure range is 0.9-1.0 MPa; the distillation point range of the middle oil is 270-340 ℃, and the pressure range is 1.0-1.1 MPa;

s3: feeding the middle oil obtained in the step S2 into a reduced pressure stripping tower 3 for secondary fractionation, wherein the upper section of the middle oil is two-line oil, and the lower section of the middle oil is three-line oil; wherein the range of the distillation point of the two-line oil is 290-320 ℃, and the pressure range is 0.9-1.05 MPa; the distillation point range of the three-line oil is 320-340 ℃, and the pressure range is 1.05-1.1 MPa;

s4: respectively feeding the first-line oil obtained in the step S2, the second-line oil obtained in the step S3 and the third-line oil into a coking heating furnace 4 and a coking tower 5 for coking reaction to obtain needle coke green coke; wherein, the first-line oil coking reaction process parameters are as follows: the temperature of the coking heating furnace is 420 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.15MPa, the coking circulation ratio is 0.7, and the coke charging time is 36 h; the technological parameters of the second-line oil coking reaction are as follows: the temperature of the coking heating furnace is 435 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25MPa, the coking circulation ratio is 0.8, and the coke charging time is 30 h; the technological parameters of the three-line oil coking reaction are as follows: the temperature of the coking heating furnace is 450 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25MPa, the coking cycle ratio is 0.9, and the coke charging time is 24 h.

S5: and (3) putting the needle coke green coke obtained in the S4 into a calcination rotary furnace 6 for calcination treatment, wherein the calcination technological parameters are as follows: the calcination temperature is 1250 ℃, the temperature rising method is to rapidly rise the temperature before 0-480 ℃, the temperature rises at the speed of 2 ℃/min after 480 ℃, the calcination time is 36h, and the needle coke is obtained.

Example 2

The difference from the example 1 is that the temperature of the coking heating furnace of the one-line oil in the S4 is 435 ℃, the pressure range of a coke tower is 0.6MPa, and the coke charging time is 42 h; the temperature of a coking heating furnace of the two-line oil is 450 ℃, the pressure range of a coke tower is 1.5MPa, and the coke charging time is 36 h; the coking heating furnace temperature of the three-line oil is 465 ℃, the pressure range of the coke tower is 1.5MPa, and the coke charging time is 30 h.

Example 3

The difference from the example 1 is that the temperature of the coking heating furnace of the one-line oil in the S4 is 450 ℃, the pressure range of a coke tower is 1.5MPa, and the coke charging time is 48 h; the temperature of a coking heating furnace of the two-line oil is 465 ℃, the pressure range of a coke tower is 2.5MPa, and the coke charging time is 42 h; the coking heating furnace temperature of the three-line oil is 480 ℃, the pressure range of the coke tower is 3.0MPa, and the coke charging time is 36 h.

Comparative example 1

The difference from example 1 is that the coking heaters of the first line oil, the second line oil and the third line oil in S4 are respectively 420 ℃, the pressure range of the coke tower is respectively 0.15MPa, and the coke charging time is respectively 36 h.

Comparative example 2

The difference from example 2 is that the coking heaters of the first line oil, the second line oil and the third line oil in S4 are 435 ℃, the pressure range of the coke tower is 0.6MPa, and the coke charging time is 42 h.

Comparative example 3

The difference from example 3 is that in S4, the coking heaters for the first line oil, the second line oil and the third line oil are all 450 ℃, the pressure range of the coke tower is all 1.5MPa, and the coke charging time is all 45 hours.

Comparative example 4

A production method of oil-based needle coke comprises the following steps:

s2: the heated raw material slurry oil enters a decompression tower 2 for decompression fractionation, and fractionation is carried out from top to bottom in sequence to obtain top dirty oil, first-line oil, middle-section oil and asphalt oil; wherein the distillation point range of the middle section oil is 160-340 ℃, and the pressure range is 0.9-1.1 MPa;

s3: directly feeding the middle-stage oil obtained in the S2 into a coking heating furnace 4 and a coking tower 5 for coking reaction without multistage fractionation to obtain needle coke green coke; wherein, the coking reaction process parameters are as follows: the temperature of the coking heating furnace is 435 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25MPa, the coking circulation ratio is 0.8, and the coke charging time is 30 h.

S4: and (3) putting the needle coke green coke obtained in the S3 into a calcination rotary furnace 6 for calcination treatment, wherein the calcination technological parameters are as follows: the calcination temperature is 1250 ℃, the temperature rising method is to rapidly rise the temperature before 0-480 ℃, the temperature rises at the speed of 2 ℃/min after 480 ℃, the calcination time is 36h, and the needle coke is obtained.

The needle coke obtained in examples 1 to 3 and comparative examples 1 to 4 were subjected to the tests of the true density, the aspect ratio and the thermal expansion coefficient, and the results are shown in Table 1.

TABLE 1 needle coke true density, aspect ratio and coefficient of thermal expansion data

As can be seen from the data in Table 1, the needle coke prepared in examples 1 to 3 all had good aspect ratios and thermal expansion coefficients of less than 0.88; in comparative examples 1 to 3, due to the adoption of the coking process parameters of the first-line oil, the length-width ratio of the needle coke prepared from the second-line oil and the third-line oil is reduced, and the thermal expansion coefficient is remarkably higher than that of the needle coke prepared from the first-line oil; in comparative example 4, the length-width ratio and the thermal expansion coefficient of the needle coke prepared by directly coking and calcining the middle oil are the worst results because the middle oil is not further fractionated, which shows that the defects caused by nonuniform coking reaction can be reduced by adopting a targeted temperature and pressure change operation method in the coking process for components with different molecular weights after the oil slurry is subjected to vacuum fractionation, so that the needle coke product with good length-width ratio and lower thermal expansion coefficient can be prepared.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims

1. The temperature and pressure changing operation method in the production process of the oil-based needle coke is characterized by comprising the following steps of:

s1: the raw material slurry oil is subjected to heat exchange treatment and then enters a pretreatment heating furnace to be heated to 400 ℃;

s2: the heated raw material slurry oil enters a vacuum tower for vacuum fractionation, and overhead oil, first-line oil, middle-section oil and asphalt oil are obtained by fractionation from top to bottom in sequence;

2. The temperature-changing and pressure-changing operation method for producing the oil-based needle coke according to claim 1, wherein in S1, the heat exchange treatment comprises the following steps:

3. The temperature-and-pressure changing operation method for producing oil-based needle coke according to claim 1, wherein in S2, the one-line oil has a boiling point ranging from 160 to 240 ℃ and a pressure ranging from 0.9 to 1.0 MPa.

4. The temperature and pressure changing operation method for producing the oil-based needle coke according to claim 1, wherein in S2, the distillation point of the middle oil ranges from 270 ℃ to 340 ℃, and the pressure ranges from 1.0MPa to 1.1 MPa.

5. The temperature-and-pressure changing operation method for producing the oil-based needle coke according to claim 1, wherein in S3, the two-line oil has a boiling point in the range of 290-320 ℃ and a pressure in the range of 0.9-1.05 MPa.

6. The temperature and pressure changing operation method for producing the oil-based needle coke according to claim 1, wherein in S3, the distillation point of the three-line oil is in the range of 320-340 ℃, and the pressure is in the range of 1.05-1.1 MPa.

7. The temperature-changing and pressure-changing operation method for producing the oil-based needle coke according to claim 1, wherein in S4, the first-line oil coking reaction process parameters are as follows: the temperature of the coking heating furnace is 420-450 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.15-1.5MPa, the coking circulation ratio is 0.7-0.8, and the coke charging time is 36-48 h.

8. The temperature-changing and pressure-changing operation method for producing the oil-based needle coke according to claim 1, wherein in S4, the second-line oil coking reaction process parameters are as follows: the temperature of the coking heating furnace is 435-465 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25-2.5MPa, the coking circulation ratio is 0.8-0.9, and the coke charging time is 30-42 h.

9. The temperature-changing and pressure-changing operation method for the production process of the oil-based needle coke according to claim 1, wherein in S4, the three-line oil coking reaction process parameters are as follows: the temperature of the coking heating furnace is 450-480 ℃, the temperature is quickly raised before 0-340 ℃, and the temperature is raised at a speed of 5 ℃/min after 340 ℃; the pressure range of the coke tower is 0.25-3MPa, the coking circulation ratio is 0.9-0.95, and the coke charging time is 24-36 h.

10. The temperature-changing and pressure-changing operation method for producing the oil-based needle coke as claimed in claim 1, wherein in S5, the calcination process parameters of the needle coke green coke are as follows: the calcination temperature is 1250-1450 ℃, the temperature rising method is to rapidly rise the temperature before 0-480 ℃, the temperature rises at the speed of 2 ℃/min after 480 ℃, and the calcination time is 36-48 h.