Needle coke and preparation method thereof

Abstract

The present application discloses a needle coke and a preparation method thereof. The method comprises the steps of dehydrating medium-temperature coal tar, cutting the first fraction, and extracting the first solvent to obtain a first component; extracting high-temperature coal tar pitch with a second solvent to obtain a second component; delaying coking the dehydrated medium-temperature coal tar and cutting the second fraction to obtain a third component; filtering, hydrogenating, and cutting the third fraction of petroleum-based aromatic-rich heavy oil to obtain a fourth component; mixing the first component, the second component, the third component, and the fourth component to obtain a refined coking raw material; delaying coking the refined coking raw material to obtain needle coke green coke; and calcining the needle coke green coke to obtain needle coke. The preparation method of needle coke processes the four components and mixes them according to a ratio, adjusts the refined coking raw material to a reasonable composition and a suitable molecular weight distribution, improves thermal reaction performance, makes the intermediate phase of the carbonization process grow and develop smoothly, and improves the crystallinity of the product.

Description

Technical Field

[0001] The present application belongs to the technical field of coal chemical industry, and in particular relates to a needle coke and a preparation method thereof. Background Art

[0002] Needle coke is a high-quality carbon material with a silver-grey metallic luster. It has the advantages of low ash, low thermal expansion, high conductivity, and high anisotropy. It is widely used in many fields such as high-power / ultra-high-power graphite electrodes, lithium-ion battery negative electrode materials, and special graphite materials. High-power graphite electrodes and ultra-high-power graphite electrodes made of needle coke have the advantages of low resistivity, strong heat shock resistance, and high mechanical strength, and are widely used in electric arc steelmaking. Lithium-ion battery negative electrode materials made of needle coke have the advantages of low resistivity and good charge and discharge performance. It is one of the main raw materials for lithium-ion battery negative electrode materials. With the rapid development of the electric furnace steelmaking industry and the new energy industry, the demand for needle coke is also increasing day by day.

[0003] The specific performance of needle coke is determined by the properties of the raw materials and the control of parameters during the coking process. The raw materials for producing needle coke are mainly heavy components in petroleum and high-temperature coal tar, such as heavy petroleum oil, high-temperature coal tar pitch, catalytic cracking (FCC) slurry, etc. The process for producing needle coke mainly includes three parts: raw material pretreatment, coking, and calcination. The existing needle coke preparation process is complex, costly, and difficult to industrialize. Summary of the invention

[0004] The embodiment of the present application provides a method for preparing needle coke, which can prepare the components of the raw materials through a combination of operations such as impurity removal, delayed coking, hydrogenation, and fraction cutting, so that the composition of the coking raw materials is reasonable and the molecular weight distribution is appropriate, and its thermal reaction performance is improved, so that the mesophase growth and development of the carbonization process is stable, and the crystallinity of the product is improved, so as to obtain high-quality needle coke with high crystallinity, good crystal structure and excellent performance.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing needle coke, the method comprising:

[0006] Using medium-temperature coal tar as a first raw material, subjecting it to dehydration, first fraction cutting, and first solvent extraction treatment to obtain a first component;

[0007] Using high temperature coal tar pitch as a second raw material and extracting it with a second solvent to obtain a second component;

[0008] The dehydrated medium-temperature coal tar is used as the third raw material, and subjected to delayed coking and second fraction cutting treatment to obtain a third component;

[0009] Using petroleum aromatic-rich heavy oil as the fourth raw material, filtering, hydrogenating, and cutting the third fraction to obtain a fourth component;

[0010] The first component, the second component, the third component and the fourth component are mixed in a weight ratio of 0 to 3:0 to 9:0 to 4:0 to 9 to obtain a refined coking raw material;

[0011] Delaying coking of the refined coking raw material to obtain needle coke green coke;

[0012] The needle coke green coke is calcined to obtain needle coke.

[0013] The preparation method of needle coke in the embodiment of the present application is as follows: a first component is obtained by dehydrating a first raw material, cutting a first fraction, and extracting a first solvent, a second component is obtained by extracting a second raw material with a second solvent, a third component is obtained by delaying coking and cutting the second fraction of the dehydrated medium-temperature coal tar as a third raw material, and finally a fourth component is obtained by filtering, hydrogenating, and cutting the third fraction of the fourth raw material; then, the four components are blended according to a weight ratio, and the composition of the refined coking raw material is adjusted to make the composition of the coking raw material reasonable and the molecular weight distribution appropriate, improve its thermal reaction performance, make the intermediate phase of the carbonization process grow and develop smoothly, and improve the crystallinity of the product; finally, needle coke green coke is obtained by delaying coking the refined coking raw material, and high-quality needle coke with high crystallinity, good crystal structure and excellent performance is obtained after calcining the needle coke green coke. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is a process flow chart of the method for preparing needle coke of the present application;

[0016] Figure 2 Schematic diagram of the process flow of an embodiment of the present application.

[0017] Description of reference numerals:

[0018] 1. The first fractionation tower; 2. The second fractionation tower; 3. The third fractionation tower;

[0019] 4. The first coke tower; 5. The second coke tower. DETAILED DESCRIPTION

[0020] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0021] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0022] Medium temperature coal tar generally refers to coal tar obtained by dry distillation (pyrolysis) of coal at 600°C to 1000°C. Based on the prior art pointed out in the background technology, the inventor found that the heavy component of medium temperature coal tar is rich in polycyclic aromatic hydrocarbons, and the molecular weight is suitable, and the quinoline insoluble matter is extremely low. It is a high-quality raw material for preparing needle coke. The colloid and asphaltene content in the heavy component of medium temperature coal tar are high, and the reaction activity is high. The S, N, and O heteroatoms in the raw materials have a great influence on the formation of the mesophase and the quality of the needle coke product. It is generally believed that nitrogen and sulfur will overflow during the graphitization process, resulting in cracks or gaps in the product, significantly reducing the density and strength of the product. Suitable raw material composition can improve the crystallinity of needle coke and reduce the formation of defects. Therefore, raw material pretreatment is extremely important and is the key to the preparation of needle coke. The main purpose of raw material pretreatment is to remove quinoline insoluble matter, ash and sulfur, nitrogen, oxygen heteroatoms, adjust the components, and achieve suitable polycyclic aromatic hydrocarbon content, softening point, density, coking value, etc. The main pretreatment processes include solvent method, thermal polycondensation method, hydrogenation method, etc. The coking processes include kettle coking and delayed coking, and the calcining processes include pot calcining and rotary kiln calcining.

[0023] Although the above-mentioned method for preparing needle coke can prepare needle coke, it still has some shortcomings, such as:

[0024] (1) The main components of medium-temperature coal tar and high-temperature coal tar are different, and their proportions are different. There are certain differences in their thermal reactions, which will eventually affect the fusion and growth of the intermediate phase spheres.

[0025] (2) Catalysts, co-carbonizing agents and inhibitors need to be added during the coking and calcining process, which will introduce impurities and affect the quality of the final product.

[0026] (3) Intermittent process, limited production capacity.

[0027] (4) The preparation process of needle coke is complex and involves ultrasonic extraction, which is costly and difficult to industrialize.

[0028] In order to solve the deficiencies of the prior art in raw material pretreatment process and coking, and to obtain high-quality raw materials with suitable components to ensure the quality of needle coke, the applicant proposed the technical solution of the present application.

[0029] like Figure 1 As shown, an embodiment of the present application provides a method for preparing needle coke, comprising:

[0030] Using medium-temperature coal tar as a first raw material, subjecting it to dehydration, first fraction cutting, and first solvent extraction treatment to obtain a first component;

[0031] Using high temperature coal tar pitch as a second raw material and extracting it with a second solvent to obtain a second component;

[0032] The dehydrated medium-temperature coal tar is used as the third raw material, and subjected to delayed coking and second fraction cutting treatment to obtain a third component;

[0033] Using petroleum aromatic-rich heavy oil as the fourth raw material, filtering, hydrogenating, and cutting the third fraction to obtain a fourth component;

[0034] Mixing the first component, the second component, the third component and the fourth component in a weight ratio of 0 to 3:0 to 9:0 to 4:0 to 9 to obtain a refined coking raw material;

[0035] Delaying coking of the refined coking raw material to obtain needle coke green coke;

[0036] The needle coke green coke is calcined to obtain needle coke.

[0037] The preparation method of needle coke in the embodiment of the present application is as follows: a first component is obtained by dehydrating a first raw material, cutting a first fraction, and solvent extracting, a second component is obtained by extracting a second raw material with a second solvent, a third component is obtained by delaying coking and cutting the second fraction of the dehydrated medium-temperature coal tar as a third raw material, and finally a fourth component is obtained by filtering, hydrogenating, and cutting the third fraction of the fourth raw material; then, the four components are blended according to a weight ratio, and the composition of the refined coking raw material is adjusted to make the composition of the coking raw material reasonable and the molecular weight distribution appropriate, improve its thermal reaction performance, make the intermediate phase of the carbonization process grow and develop smoothly, and improve the crystallinity of the product; finally, needle coke green coke is obtained by delaying coking the refined coking raw material, and high-quality needle coke with high crystallinity, good crystal structure and excellent performance is obtained after calcining the needle coke green coke.

[0038] According to the method for preparing needle coke in the embodiment of the present application, high-temperature coal tar refers to a liquid product obtained by dry distillation of coal at a temperature greater than 1000°C, and high-temperature coal tar pitch is the bottom fraction obtained by distilling high-temperature coal tar at 300°C to 400°C.

[0039] According to the method for preparing needle coke in the embodiment of the present application, the steps of using medium-temperature coal tar as the first raw material, dehydrating, cutting the first fraction, and extracting the first solvent to obtain the first component include:

[0040] Dehydration treatment, dehydrating the first raw material to obtain anhydrous coal tar;

[0041] The first fraction cutting process is to distill the anhydrous coal tar under normal pressure or reduced pressure to obtain a fraction of the anhydrous coal tar having a temperature greater than 350° C.

[0042] The first solvent extraction treatment is to perform a first solvent extraction on the fraction of the anhydrous coal tar with a temperature greater than 350° C., and remove the extraction solvent by vacuum distillation to obtain a first component.

[0043] In one embodiment, the dehydration step includes:

[0044] The first raw material is dehydrated by a distillation tower to obtain anhydrous coal tar; wherein the dehydration treatment meets the following process conditions: the feed temperature of the first raw material is 110°C to 190°C, the bottom temperature of the fractionation tower is 120°C to 200°C, the top temperature of the tower is 90°C to 150°C, and the top pressure is 2KPa to 25KPa, so as to remove moisture from the first raw material. The feed temperature of the first raw material is the temperature when it enters the fractionation tower after heat exchange with the fractionation tower or other heating source.

[0045] In the process of obtaining the first component and the third component by using medium-temperature coal tar as the first raw material, dehydrating the first raw material can reduce the moisture in the feed of the distillation tower, that is, reduce the moisture in the coal tar entering the distillation tower. Because coal tar contains a lot of water, on the one hand, it will increase the heat load of the distillation device and reduce production capacity; on the other hand, it will also significantly increase the system pressure, increase resistance, and cause unstable operation; on the other hand, the corrosive medium brought in with the water will cause corrosion of pipelines and equipment. Therefore, considering the negative impact of the high water content in coal tar on equipment, energy consumption, and product quality, the water contained should be removed before preparing needle coke.

[0046] In one embodiment, the first fraction cutting process comprises:

[0047] The anhydrous coal tar is subjected to the first fraction cutting treatment by using a distillation tower, and the first fraction cutting meets the following process conditions: the feed temperature of the anhydrous coal tar is 250°C to 300°C, the tower bottom temperature is 230°C to 280°C, the tower top temperature is 90°C to 150°C, the tower top pressure is -50KPa to -80KPa, and the bottom of the first distillation tower is the fraction of anhydrous coal tar with a temperature greater than 350°C.

[0048] In one embodiment, the first solvent extraction process comprises:

[0049] The fraction of anhydrous coal tar having a temperature greater than 350° C. is subjected to a first solvent extraction treatment to settle quinoline insoluble matter and ash impurities in the fraction of anhydrous coal tar having a temperature greater than 350° C., thereby obtaining an extraction solvent mixture free of quinoline insoluble matter and ash impurities;

[0050] The extraction solvent mixture is subjected to reduced pressure distillation to remove the extraction solvent and obtain a first component.

[0051] In one embodiment, the fraction of anhydrous coal tar greater than 350°C is mixed online with an extraction solvent and then enters an extraction tower, and the fraction of anhydrous coal tar greater than 350°C is subjected to solvent extraction treatment, the weight ratio of the fraction of anhydrous coal tar greater than 350°C and the extraction solvent is 1:1-2, and the mixing temperature is 80°C-200°C, so as to remove impurities in the fraction of anhydrous coal tar greater than 350°C and obtain an extraction solvent mixture free of impurities.

[0052] In one embodiment, the step of distilling the extraction solvent mixture under reduced pressure comprises:

[0053] Under the conditions of vacuum degree of -50KPa to -80KPa and feed temperature of 200℃ to 300℃, the impurity-free extraction mixture of the fraction of medium-temperature coal tar greater than 350℃ and the extraction solvent is subjected to reduced pressure distillation to remove the extraction solvent and obtain the impurity-free fraction of anhydrous coal tar greater than 350℃ as the first component.

[0054] According to the method for preparing needle coke in the embodiment of the present application, the steps of using high-temperature coal tar pitch as the second raw material and extracting it with a second solvent to obtain the second component include:

[0055] Performing a second solvent extraction treatment on the high-temperature coal tar pitch to settle quinoline insoluble matter and ash impurities in the high-temperature coal tar pitch, thereby obtaining an extraction solvent mixture free of quinoline insoluble matter and ash impurities;

[0056] The extraction solvent mixture is subjected to reduced pressure distillation to remove the extraction solvent and obtain a second component.

[0057] In one embodiment, the step of performing a second solvent extraction on the high temperature coal tar pitch comprises:

[0058] The high-temperature coal tar pitch and the extraction solvent are mixed online and then enter the extraction tower to perform solvent extraction on the high-temperature coal tar pitch. The weight ratio of the high-temperature coal tar pitch and the extraction solvent is 1:1-2, and the mixing temperature is 80°C-200°C, so as to remove impurities in the high-temperature coal tar pitch and obtain an extraction solvent mixture without impurities.

[0059] According to the method for preparing needle coke in the embodiment of the present application, the process parameters for the reduced pressure distillation treatment of the extraction solvent mixture of anhydrous coal tar free of quinoline insolubles and ash impurities or the extraction mixture of high-temperature coal tar pitch and extraction solvent are: vacuum degree of -50KPa to -80KPa, and feed temperature of 200℃ to 300℃.

[0060] According to the method for preparing needle coke in the embodiment of the present application, both the first solvent extraction treatment and the second solvent extraction treatment use an extraction solvent for solvent extraction treatment, the extraction solvent is compounded by an aromatic solvent and an aliphatic solvent, the distillation range of the aromatic solvent is 220°C to 300°C, and the distillation range of the aliphatic solvent is 140°C to 300°C.

[0061] In one embodiment, the aromatic solvent is selected from one or a combination of fractions of distillation tower top circulating oil, distillation tower phenol oil fraction, coking wash oil fraction, coal tar light diesel 220°C to 300°C, and the aliphatic solvent is selected from one or a combination of fractions of kerosene, aviation kerosene, light white oil, industrial white oil at 140°C to 300°C.

[0062] In one embodiment, the aromatic solvent is one selected from the group consisting of fractionation tower top circulating oil, fractionation tower phenol oil fraction, coking oil fraction, and coal tar light diesel fraction at 220°C to 300°C. The fractionation tower top circulating oil refers to the fraction at 180°C to 260°C in the upper part of the third fractionation tower, and the fractionation tower phenol oil fraction refers to the fraction at 180°C to 260°C in the upper part of the second fractionation tower. Coal tar light diesel is a diesel fraction obtained by hydrogenating and splitting the fraction of medium and low temperature coal tar less than 400°C.

[0063] In one embodiment, the coking wash oil fraction is a 220°C to 300°C fraction of high-temperature coal tar, which is a product obtained by distilling high-temperature coal tar.

[0064] Kerosene is the 180℃~300℃ fraction obtained by petroleum distillation.

[0065] Aviation kerosene is the 180℃~300℃ fraction obtained by hydrogenating and fractionating petroleum or coal tar fractions.

[0066] Light white oil is a 140℃~300℃ fraction obtained by hydrogenating and fractionating petroleum or coal tar fractions.

[0067] Industrial white oil is the 140℃~300℃ fraction obtained by hydrogenation and fractionation of petroleum or coal tar fractions.

[0068] According to the method for preparing needle coke in the embodiment of the present application, dehydrated medium-temperature coal tar is used as the third raw material, and is subjected to delayed coking and second fraction cutting treatment to obtain a third component.

[0069] According to the method for preparing needle coke in the embodiment of the present application, the steps of using dehydrated medium-temperature coal tar as the third raw material, and subjecting the third component to delayed coking and second fraction cutting treatment include:

[0070] Delayed coking treatment, in which the dehydrated medium-temperature coal tar as the third raw material is subjected to delayed coking to produce coking oil gas;

[0071] The second fraction is cut and the coking oil gas is distilled to obtain a 300°C to 500°C fraction to obtain a third component.

[0072] In one embodiment, the step of delaying coking the dehydrated medium-temperature coal tar comprises:

[0073] The dehydrated medium-temperature coal tar is heated in a heating furnace and then sent to a coke tower for delayed coking. The process conditions for delayed coking are: the outlet temperature of the heating furnace is 420°C to 460°C, the pressure of the coke tower is a slightly positive pressure of 0KPa to 200KPa, and the coking oil gas is obtained.

[0074] In one embodiment, a distillation tower is used to perform a second fraction cutting process on the coking oil gas, and the second fraction cutting process meets the following process conditions: the feed temperature of the coking oil gas is 380°C to 440°C, the tower bottom temperature is 340°C to 400°C, the tower top temperature is 90°C to 150°C, and the tower top pressure is 20KPa to 80KPa.

[0075] The method for preparing needle coke in the embodiment of the present application is to carry out delayed coking by using the dehydrated medium-temperature coal tar of the first raw material as the third raw material, the main purpose of which is to lighten the medium-temperature coal tar. The medium-temperature coal tar is subjected to delayed coking, and the heavy components therein undergo a thermal condensation reaction to generate asphalt coke and produce coking oil gas. The coking oil gas is cut and fractionated through the second fraction to obtain a fraction of 300°C to 500°C, i.e., the third component, to provide raw materials for subsequent stages.

[0076] According to the method for preparing needle coke in the embodiment of the present application, petroleum-based aromatic-rich heavy oil is used as the fourth raw material, and the fourth component is obtained after filtering, hydrogenation, and cutting of the third fraction.

[0077] According to the method for preparing needle coke in the embodiment of the present application, the steps of using petroleum-based aromatic-rich heavy oil as the fourth raw material, filtering, hydrogenating, and cutting the third fraction to obtain the fourth component include:

[0078] Filtering the petroleum-based aromatic-rich heavy oil to remove ash and obtain low-ash petroleum-based aromatic-rich heavy oil;

[0079] The low-ash petroleum aromatic-rich heavy oil is hydrotreated to remove the S element, and the third fraction is cut to obtain a fraction greater than 350° C. as the fourth component.

[0080] The method for preparing needle coke in the embodiment of the present application reduces the influence of S heteroatoms in the raw materials on the formation of the mesophase and the quality of the needle coke product by hydrogenating the petroleum-based aromatic-rich heavy oil.

[0081] In one embodiment, the steps of filtering the petroleum-based aromatic-rich heavy oil to remove ash to obtain low-ash petroleum aromatic-rich heavy oil include:

[0082] The filter is used to filter the heavy oil rich in aromatics of petroleum. The process conditions and parameters of the filtering treatment are as follows: the filtering temperature of the heavy oil rich in aromatics of petroleum is 180℃~260℃, the filtering accuracy of the filtering component of the filter is 0.05 micron~10 micron, and the filtering component is a filter element or a filter membrane. The filter has a backwashing function to prevent the impurities and high-viscosity substances in the heavy oil rich in aromatics of petroleum from clogging the filter and prolonging the service life of the filter element. The solvent for backwashing is a mixture of coking diesel and coking wax oil.

[0083] Fourth, the raw material continuously passes through the filter component of the filter at a certain temperature, and the ash impurities will be intercepted by the filter component. After running for a period of time, an ash impurity filter cake will be formed on the material inlet side of the filter component, and the filtration flux will be greatly reduced. At this time, stop feeding the filter, start the backwash process, backwash the filter component, and remove the ash impurity filter cake formed on the filter component.

[0084] The method for preparing needle coke in the embodiment of the present application is to filter the petroleum-based aromatic-rich heavy oil for the purpose of removing ash from the petroleum-based aromatic-rich heavy oil after hydrogenation, mainly to filter out the catalyst powder in the ash to protect the hydrogenation catalyst and prevent the catalyst powder from causing the hydrogenation catalyst to lose its catalytic hydrogenation activity.

[0085] In one embodiment, the steps of hydrotreating petroleum-based aromatic-rich heavy oil to remove the S element and performing a third fraction cutting process to obtain a fraction greater than 350° C. as the fourth component include:

[0086] Under the conditions of a feed temperature of 30°C to 380°C and a pressure of 3.0MPa to 10.0MPa, and a Ni, Mo, Co, W active component supported alumina carrier catalyst, a fixed bed reactor is used to perform a hydrogenation operation on an ash-free petroleum-based aromatic heavy oil, and the hydrogenated petroleum-based aromatic heavy oil is filtered to obtain a petroleum-based aromatic heavy oil from which the S element and ash are removed;

[0087] The petroleum-based aromatic heavy oil from which the S element has been removed is subjected to a third fraction cutting treatment using a fractionating tower to obtain a fraction greater than 350° C. as the fourth component. The feed temperature refers to the feed temperature of the petroleum-based aromatic heavy oil.

[0088] In one embodiment, the third fraction cutting process needs to meet the following process conditions: the feed temperature of the petroleum-based aromatic-rich heavy oil from which the S element has been removed is 340°C to 380°C, the tower bottom temperature is 330°C to 370°C, the tower top temperature is 105°C to 145°C, and the tower top pressure is 50KPa to 200KPa.

[0089] According to the embodiments of the present application, the petroleum-based aromatic-rich heavy oil is one of catalytic cracking oil slurry and ethylene tar or a combination thereof. Catalytic cracking oil slurry is the bottom fraction obtained after the petroleum heavy oil is processed by catalytic cracking; ethylene tar is the product of high-temperature condensation of raw materials and products during the steam cracking process of ethylene cracking raw materials. The petroleum-based aromatic-rich heavy oil contains catalyst powder and more than 50wt% of polycyclic aromatic hydrocarbons, and most of the polycyclic aromatic hydrocarbons have few and short side chains and low hydrogen-carbon atom ratios; the petroleum heavy oil is selected from one of vacuum distillate oil, coker wax oil, and deasphalted oil or a combination thereof.

[0090] Both petroleum-based aromatic-rich heavy oil and high-temperature coal tar pitch have high polycyclic aromatic hydrocarbon content and good thermal reaction performance. Adding a certain proportion of the second component and the fourth component to the needle coke raw material can significantly improve the composition and thermal reaction performance of the needle coke raw material, thereby preparing high-quality needle coke.

[0091] Compared with the prior art, the method for preparing needle coke in the embodiment of the present application increases the content of tricyclic aromatic hydrocarbons and tetracyclic aromatic hydrocarbons in the refined coking raw material from 38.2%wt to 49.1%wt by adding the second component and the fourth component, and adjusts the composition of the refined coking raw material to obtain a refined coking raw material with a suitable molecular weight distribution.

[0092] According to the method for preparing needle coke in the embodiment of the present application, the step of obtaining the refined coking raw material comprises:

[0093] The first component, the second component, the third component and the fourth component are mixed in a weight ratio of 1:3:3:3 to obtain a refined coking raw material.

[0094] In one embodiment, in the step of obtaining a refined coking feedstock, the weight ratio of the first component, the second component, the third component and the fourth component is preferably 1:4:2:3 or 1:4:1:4 or 1:3:2:4.

[0095] According to the method for preparing needle coke in the embodiment of the present application, the steps of delaying coking the refined coking raw material to obtain needle coke raw coke include:

[0096] The refined coking raw materials are heated in a heating furnace and then sent to a coke tower for delayed coking. The process conditions for delayed coking are: the outlet temperature of the heating furnace is 440°C to 520°C, the pressure of the coke tower is 0.5MPa to 1.0MPa, and needle coke is obtained. The delayed coking time is 24 to 48 hours.

[0097] According to the method for preparing needle coke in the embodiment of the present application, delayed coking is carried out by variable temperature and variable pressure delayed coking. Variable temperature and variable pressure delayed coking is relative to constant temperature and constant pressure operation. Variable temperature operation is in the delayed coking process of producing needle coke, and the outlet temperature of the delayed coking heating furnace will change as the coking proceeds.

[0098] Specifically, temperature change means that during the delayed coking process of refined coking raw materials, the outlet temperature of the heating furnace in the initial stage of feeding the refined coking raw materials is 400℃~480℃, and after a period of feeding, the temperature is increased to 500℃~520℃ at a heating rate of 1~5℃ / h and kept constant for a period of time.

[0099] Pressure change means that during the delayed coking process of refined coking raw materials, the top pressure of the second coke tower will change as the coking progresses; wherein, in the early stage of delayed coking, the second coke tower maintains a relatively stable pressure, that is, within the pressure range of 0.5MPa to 1.0MPa; in the later stage of delayed coking, the top pressure of the second coke tower will be reduced to normal pressure at a pressure reduction rate of 0.05MPa / h to 0.2MPa / h.

[0100] In some embodiments, the aforementioned distillation tower can be used to preheat the refined coking raw materials, while reducing the heat load of the heating furnace, thereby achieving the effect of energy saving and consumption reduction.

[0101] According to the method for preparing needle coke in the embodiment of the present application, the step of calcining green needle coke to obtain needle coke includes:

[0102] The needle coke is calcined in a rotary kiln at 1100°C to 1500°C to obtain the needle coke.

[0103] In one embodiment, the calcination time of the needle coke green coke in the rotary kiln is 2 hours to 5 hours.

[0104] It should be noted that the distillation tower in the above method refers to components or devices with the same function, rather than the same component or device.

[0105] In a second aspect, an embodiment of the present application further provides a needle coke, which is prepared according to the above-mentioned preparation method of needle coke.

[0106] The method for preparing needle coke of the present application is described in detail below with reference to specific embodiments and drawings.

[0107] Embodiment: This embodiment provides a needle coke, which is prepared from medium-temperature coal tar, petroleum-based aromatic-rich heavy oil slurry and high-temperature coal tar pitch according to the needle coke preparation method of the present application. In this embodiment, the first raw material is medium-temperature coal tar, the second raw material is high-temperature coal tar pitch, and the third raw material is dehydrated medium-temperature coal tar, that is, anhydrous coal tar; the fourth raw material is petroleum-based aromatic-rich heavy oil.

[0108] like Figure 2 As shown, the preparation method of this embodiment specifically includes the following steps:

[0109] S1. Using medium-temperature coal tar as a first raw material, subjecting it to dehydration, first fraction cutting, and first volume extraction treatment to obtain a first component A; wherein step S1 specifically comprises:

[0110] Dehydration treatment: the first raw material is subjected to dehydration treatment using the first fractionation tower 1 to remove water from the first raw material; the dehydration treatment meets the following process conditions: the feed temperature of the first raw material is 110°C to 130°C, the tower bottom temperature is 120°C to 130°C, the tower top temperature is 90°C to 110°C, and the tower top pressure is 5KPa to 10KPa, to obtain anhydrous coal tar;

[0111] The first fraction cutting treatment, the anhydrous coal tar is subjected to the first fraction cutting treatment by using a distillation tower, and the first fraction cutting treatment meets the following process conditions: the feed temperature of the anhydrous coal tar is 270℃~290℃, the tower bottom temperature is 240℃~260℃, the tower top temperature is 90℃~110℃, the tower top pressure is -50KPa~-80KPa, and the bottom output of the first distillation tower is the fraction of anhydrous coal tar with a temperature greater than 350℃.

[0112] The first solvent extraction treatment is to use an extraction solvent prepared by compounding an aromatic solvent and an aliphatic solvent to perform the first solvent extraction treatment on the fraction of the anhydrous coal tar with a temperature greater than 350°C, and under the reduced pressure conditions of a vacuum degree of -50KPa to -80KPa and a feed temperature of 280°C to 300°C, a reduced pressure distillation is performed on an extraction mixture of the fraction of the anhydrous coal tar with a temperature greater than 350°C and the extraction solvent in a volume ratio of 1:1.5 to remove the extraction solvent and obtain a first component A, i.e., the fraction of the anhydrous coal tar with a temperature greater than 350°C without impurities.

[0113] The extraction solvent includes an aromatic solvent and an aliphatic solvent in a volume ratio of 3:1, the aromatic solvent is the circulating oil at the top of the distillation tower, and the aliphatic solvent is kerosene.

[0114] S2, using high temperature coal tar pitch as a second raw material, and extracting it with a second solvent to obtain a second component B; wherein step S2 specifically includes:

[0115] A second solvent extraction treatment is performed on the high-temperature coal tar pitch using an extraction solvent in an extraction tower to cause quinoline insolubles and ash impurities in the high-temperature coal tar pitch to settle, thereby obtaining an extraction solvent mixture free of quinoline insolubles and ash impurities;

[0116] The weight ratio of high-temperature coal tar pitch to the extraction solvent is 1:1.8, the mixing temperature is 110°C to 130°C, the extraction solvent includes an aromatic solvent and an aliphatic solvent in a volume ratio of 3:1, the aromatic solvent is a fraction of the tower phenol oil, and the aliphatic solvent is a light white oil;

[0117] The extraction solvent mixture of high-temperature coal tar pitch and extraction solvent is subjected to reduced pressure distillation treatment under the conditions of a vacuum degree of -50KPa to -80KPa and a feed temperature of 280°C to 300°C to remove the extraction solvent and obtain a second component B.

[0118] S3, using the dehydrated medium-temperature coal tar as the third raw material, i.e., anhydrous coal tar, and subjecting it to delayed coking and second fraction cutting to obtain a third component C; wherein step S3 specifically comprises:

[0119] Delayed coking treatment, using a heating furnace to heat the third raw material and then feeding it into the first coke drum 4 for delayed coking, the delayed coking meets the following process conditions: the outlet temperature of the heating furnace is 420°C to 460°C, the pressure of the first coke drum 4 is a slightly positive pressure of 0KPa to 50KPa, and asphalt coke and coking oil gas are obtained;

[0120] The second fraction cutting treatment is to distill the obtained coking oil gas in the third distillation tower 3 to obtain a fraction of 300°C to 500°C by distillation, that is, to obtain the third component C; wherein, the second fraction cutting meets the following process parameters: the feed temperature of the coking oil gas is 400°C to 420°C, the tower bottom temperature is 360°C to 380°C, the tower top temperature is 100°C to 120°C, and the tower top pressure is 20KPa to 50KPa.

[0121] S4, using petroleum-based aromatics-rich heavy oil as the fourth raw material, filtering, hydrogenating, and cutting the third fraction to obtain a fourth component D; wherein step S4 specifically includes:

[0122] The filter is used to filter the petroleum-based aromatic-rich heavy oil. The process conditions and parameters satisfied by the filtering treatment are as follows: the filtering temperature of the petroleum-based aromatic-rich heavy oil is 200°C to 220°C, and the filter uses a filter element with a filtering accuracy of 0.05 microns to 5 microns as a filtering component to remove ash and obtain low-ash petroleum-based aromatic-rich heavy oil;

[0123] A fixed bed reactor is used to hydrogenate low-ash petroleum-based aromatic heavy oil at a feed temperature of 300°C to 360°C, a pressure of 3.0MPa to 10.0MPa, and an alumina-supported catalyst with Ni, Mo, Co, and W active components to obtain a petroleum-based aromatic heavy oil from which the S element has been removed.

[0124] The petroleum-based aromatic heavy oil from which the S element has been removed is subjected to a third fraction cutting process, and the third fraction cutting process must meet the following process conditions: the feed temperature of the petroleum-based aromatic heavy oil from which the S element has been removed is 340°C to 380°C, the tower bottom temperature is 330°C to 370°C, the tower top temperature is 105°C to 145°C, the tower top pressure is 50KPa to 200KPa, and a fraction greater than 350°C is obtained as the fourth component D.

[0125] S5, mixing the first component, the second component, the third component and the fourth component in a weight ratio of 1:3:3:3 to obtain a refined coking raw material;

[0126] S6, heating the refined coking raw material in a heating furnace and then sending it to the second coking tower 5 for delayed coking, the process conditions of delayed coking are: the outlet temperature of the heating furnace is 480°C to 520°C, the top pressure of the second coking tower 5 is 0.5MPa to 1.0MPa, and the delayed coking is performed for 24 hours to obtain needle coke green coke;

[0127] S7. Place the green needle coke in a rotary kiln and calcine it for 2.5 hours at 1300° C. to 1500° C. to obtain needle coke.

[0128] The microstructures of the needle coke prepared in the embodiment of the present application are compared with those of the existing needle coke, as shown in Table 1:

[0129] Table 1 Comparison of microstructures of samples at different parts of the coking tower before and after process improvement

[0130]

[0131] It can be concluded from Table 1 that the fiber structure of the needle coke prepared by the method for preparing needle coke of the present application has increased after the fiber structure is improved in the upper, middle and lower parts of the coking tower, and the increase in the upper, middle and lower parts is 60.71%, 20.31% and 23.53% respectively. The above comparative data show that the preparation method of the present application makes the mesophase of the coking raw material grow and develop smoothly during the carbonization process, and is easy to form a fiber structure.

[0132] It should be clear that the present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0133] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A method for preparing needle coke, characterized in that: include: Using medium-temperature coal tar as a first raw material, and performing a dehydration treatment on the first raw material to obtain anhydrous coal tar; The first fraction cutting process is to perform atmospheric or reduced pressure distillation on the anhydrous coal tar to obtain a fraction of the anhydrous coal tar having a temperature greater than 350° C. The fraction of the anhydrous coal tar having a temperature greater than 350° C. is subjected to a first solvent extraction treatment, comprising: the fraction of the anhydrous coal tar having a temperature greater than 350° C. is subjected to a first solvent extraction treatment, so as to settle quinoline insoluble matter and ash impurities in the fraction of the anhydrous coal tar having a temperature greater than 350° C., thereby obtaining an extraction solvent mixture free of quinoline insoluble matter and ash impurities; the extraction solvent mixture is subjected to a reduced pressure distillation treatment, so as to remove the extraction solvent, thereby obtaining a first component; Using high-temperature coal tar pitch as a second raw material, subjecting the high-temperature coal tar pitch to a second solvent extraction treatment to settle quinoline insolubles and ash impurities in the high-temperature coal tar pitch, thereby obtaining an extraction solvent mixture free of quinoline insolubles and ash impurities; subjecting the extraction solvent mixture to a reduced pressure distillation treatment to remove the extraction solvent, thereby obtaining a second component; Dehydrating the dehydrated medium-temperature coal tar as the third raw material to obtain coking oil gas; performing a second fraction cutting process, distilling the coking oil gas to obtain a 300°C to 500°C fraction, and obtaining a third component; A petroleum-based aromatic-rich heavy oil is used as the fourth raw material, wherein the petroleum-based aromatic-rich heavy oil is selected from one of catalytic cracking oil slurry and ethylene tar or a combination thereof; the petroleum-based aromatic-rich heavy oil is filtered to remove ash to obtain a low-ash petroleum-based aromatic-rich heavy oil; under the conditions of a feed temperature of 300° C. to 380° C., a pressure of 3.0 MPa to 10.0 MPa, and a Ni, Mo, Co, W active component-loaded alumina carrier catalyst, the low-ash petroleum-based aromatic-rich heavy oil is hydrogenated to remove the S element, and a third fraction cutting process is performed to obtain a fraction greater than 350° C. as the fourth component; The first component, the second component, the third component and the fourth component are mixed in a weight ratio of 1 to 3:3 to 9:1 to 4:3 to 9 to obtain a refined coking raw material; The refined coking raw material is subjected to delayed coking, comprising: heating the refined coking raw material in a heating furnace and then feeding the heated raw material into a coke drum for delayed coking, wherein the process conditions of the delayed coking are: the outlet temperature of the heating furnace is 440° C. to 520° C., the pressure of the coke drum is 0.5 to 1.0 MPa, and needle coke is obtained; The needle coke green coke is calcined to obtain needle coke.

2. The preparation method according to claim 1, characterized in that: The dehydration process comprises: The first raw material is dehydrated by using a distillation tower, and the dehydration meets the following process conditions: feed temperature 110℃~190℃, tower bottom temperature 120℃~200℃, tower top temperature 90℃~150℃, tower top pressure 2KPa~25KPa.

3. The preparation method according to claim 1, characterized in that: The first fraction cutting process meets the following process conditions: feed temperature 250°C to 300°C, tower bottom temperature 230°C to 280°C, tower top temperature 90°C to 150°C, tower top pressure -50KPa to -80KPa.

4. The preparation method according to claim 1, characterized in that: The process conditions for the reduced pressure distillation treatment of the extraction solvent mixture are: vacuum degree of -50KPa to -80KPa, and feed temperature of 200°C to 300°C.

5. The preparation method according to claim 1, characterized in that: The first solvent extraction treatment and the second solvent extraction treatment are both performed using an extraction solvent, wherein the extraction solvent is compounded from an aromatic solvent and an aliphatic solvent, wherein the distillation range of the aromatic solvent is 220°C to 300°C, and the distillation range of the aliphatic solvent is 140°C to 300°C.

6. The preparation method according to claim 1, characterized in that: The steps of the delayed coking process include: The dehydrated medium-temperature coal tar is heated in a heating furnace and then sent to a coke tower for delayed coking. The process conditions for delayed coking are: the outlet temperature of the heating furnace is 420°C to 460°C, the pressure of the coke tower is a slightly positive pressure of 0KPa to 200KPa, and the coking oil gas is obtained.

7. The preparation method according to claim 1, characterized in that: The second fraction cutting process needs to meet the following process conditions: The feed temperature is 380℃~440℃, the tower bottom temperature is 340℃~400℃, the tower top temperature is 90℃~150℃, and the tower top pressure is 20KPa~80KPa.

8. The preparation method according to claim 1, characterized in that: The step of filtering the petroleum-based aromatic-rich heavy oil to remove ash to obtain low-ash petroleum aromatic-rich heavy oil comprises: The petroleum-based aromatic-rich heavy oil is filtered using a filter, and the filtering treatment meets the following process conditions and parameters: the filtering temperature is 180°C to 260°C, the filtering accuracy of the filtering component of the filter is 0.05 microns to 10 microns, and the filtering component is a filter element or a filter membrane.

9. The preparation method according to claim 1, characterized in that: The step of hydrotreating the petroleum-based aromatic-rich heavy oil to remove the S element and performing a third fraction cutting process to obtain a fraction greater than 350° C. as the fourth component comprises: The petroleum-based aromatics-rich heavy oil is subjected to hydrogenation treatment by using a fixed bed reactor to obtain the petroleum-based aromatics-rich heavy oil from which the S element has been removed; The petroleum-based aromatics-rich heavy oil from which the S element has been removed is subjected to a third fraction cutting treatment using a fractionating tower to obtain a fraction having a temperature greater than 350° C. as the fourth component.

10. The preparation method according to claim 1, characterized in that: The step of obtaining the refined coking raw material comprises: The first component, the second component, the third component and the fourth component are mixed in a weight ratio of 1:3:3:3 to obtain the refined coking raw material.

11. The preparation method according to claim 1, characterized in that: The step of obtaining the refined coking raw material, wherein the weight ratio of the first component, the second component, the third component and the fourth component is 1:4:2:3 or 1:4:1:4 or 1:3:2:

4.

12. The preparation method according to claim 1, characterized in that: The step of calcining the green needle coke to obtain the needle coke comprises: The green needle coke is placed in a rotary kiln for calcination at 1100° C. to 1500° C. to obtain needle coke.

13. A needle coke, characterized in that: The needle coke is prepared according to the method for preparing the needle coke according to any one of claims 1 to 12.

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