Preparation method of needle coke raw material, needle coke and graphitized substance
By combining and treating coal tar asphalt with petroleum-based heavy oil or petroleum-based cracked oil, the problems of complex purification process and high cost in coal-based needle coke production are solved, and high-quality and low-cost needle coke raw materials are obtained , and improves its graphite properties.
Patent Information
- Application Number
- CN202310694827.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-13
- Publication Date
- 2024-12-20
AI Technical Summary
The purification process of coal asphalt in the production of coal needle coke in the prior art is complex, the reactive space of adjusting asphalt components is small, the flash condensation method is high and the yield is low, and it is difficult to effectively remove quinoline insoluble substances and high boiling components. .
Different sources of asphalt species are used to mix with petroleum-based heavy oil or petroleum-based cracked oil. As solvents, the reactivity and continuity of components are adjusted by heating, stirring and standing cooling, and the quinoline insoluble substances and high boiling point groups are removed. To obtain high-quality needle-shaped coke raw materials.
The preparation of needle-shaped coke raw materials with high quality and low cost is achieved, and the structural advantages of needle-shaped coke and the thermal expansion coefficient performance of graphite are improved.
Smart Images
Figure CN119161890A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of asphalt deep processing, and relates to a method for preparing a needle coke raw material, and the needle coke and graphitized product. Background Art
[0002] Needle coke is a high-quality variety of carbon materials that was vigorously developed in the 1970s. It is one of the artificial graphites and has a series of advantages such as low thermal expansion coefficient, low porosity, low sulfur, low ash content, low metal content, high conductivity and easy graphitization. Its graphitized products have good chemical stability, corrosion resistance, high thermal conductivity, and good mechanical strength at low and high temperatures. They are mainly used to produce high-power (HP) and ultra-high-power (UHP) graphite electrodes and special carbon products for electric furnace steelmaking. They are also new materials for brushes, batteries, steelmaking carburizers, and high-temperature high-quality refractory furnace materials. The metallurgical industry is the largest user of graphite electrodes. In addition, yellow phosphorus production also consumes a certain amount of graphite electrodes. The use of high-power or ultra-high-power electric furnaces for steelmaking can shorten the smelting time by 30-50%, save more than 10-20% of electricity, and have obvious economic benefits.
[0003] According to the different raw material routes, needle coke is divided into oil-based and coal-based, and their production methods are somewhat different. The production method of oil-based needle coke uses heavy distillate oil from petroleum processing plants such as thermal cracking residue oil and catalytic cracking clarified oil as raw materials, and produces finished oil-based needle coke through delayed coking and calcination processes. The production method of coal-based needle coke uses coal tar pitch, a by-product of coal coking, as raw material, and produces finished coal-based needle coke through three processes of raw material pretreatment, delayed coking and calcination.
[0004] The difference between the production process of coal-based needle coke and oil-based needle coke lies mainly in the raw material pretreatment. The main component of coal tar pitch is aromatic hydrocarbons, but it contains a certain amount of quinoline insolubles (QI), which is not only amorphous carbon generated by the thermal polymerization of certain high-molecular resinous substances during coal tar distillation, but also coal powder and coke powder brought from the carbonization chamber of the coke oven with coal gas. They adhere to the surrounding of the mesophase, hindering the growth and fusion of spherical crystals, and after coking, needle coke tissue with good fiber structure cannot be obtained. Therefore, it is necessary to pretreat the coal tar raw material, first remove the quinoline insolubles that hinder the growth of small spheres, and then modulate the components to obtain raw materials that meet the needs of needle coke production. This is a necessary condition for producing needle coke with coal tar.
[0005] In the prior art, the purification of coal tar pitch is basically carried out by solvent method, and the asphalt purification process is complicated, with little room for adjusting the asphalt components and no room for adjusting the reactivity of the asphalt. The flash polycondensation method uses thermal modification and distillation to adjust the components, and the reactivity is adjusted, but the yield is extremely low and the cost is high. Summary of the invention
[0006] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a method for preparing a needle coke raw material, needle coke and graphitized product, by using asphalt types from different sources to match each other and serve as solvents for each other, thereby adjusting the reactivity and continuity of the components, being able to remove primary quinoline insolubles and high-boiling components, and allowing coal tar pitch to develop in a direction that is beneficial to various anisotropic components, thereby obtaining a needle coke raw material with high quality and low cost.
[0007] To achieve the above object, the present invention adopts the following technical solution:
[0008] A first aspect of the present invention provides a method for preparing a needle coke raw material, comprising the following steps:
[0009] S1, mixing coal tar pitch with petroleum-based heavy oil or petroleum-based cracking oil, and obtaining a mixture after heating and stirring;
[0010] S2, after the mixture is allowed to stand and cool, insoluble precipitates are removed by a tilting method to obtain a needle coke raw material.
[0011] Preferably, in step S1:
[0012] In the total amount of coal tar pitch and petroleum-based heavy oil or petroleum-based cracking oil, the petroleum-based heavy oil or petroleum-based cracking oil accounts for 10 to 70 wt % of the total amount; and / or
[0013] The petroleum cracking oil is selected from catalytic cracking residual oil and hydrocracking residual oil produced by the petrochemical industry.
[0014] Preferably, in the total amount of coal tar pitch and petroleum-based heavy oil or petroleum-based cracking oil, the petroleum-based heavy oil or petroleum-based cracking oil accounts for 25 to 50 wt % of the total amount.
[0015] Preferably, in step S1:
[0016] During the heating process, the heating temperature is 200-320° C. and the heating time is 1-4 hours; and / or
[0017] During the heating process, the light oil is refluxed while stirring.
[0018] Preferably, in step S1, the heating temperature is 250-310°C.
[0019] Preferably, in step S2, the cooling method is natural cooling, and the temperature of the mixture when removing insoluble precipitates after standing and cooling is 60-200°C.
[0020] Preferably, in step S2, the temperature of the mixture when removing insoluble precipitates after standing and cooling is 150-200°C.
[0021] Preferably, in step S2, the quinoline insoluble matter content of the needle coke raw material is ≤0.2wt%.
[0022] The second aspect of the present invention provides a needle coke obtained by coking a needle coke raw material obtained by the method for preparing a needle coke raw material as described in the first aspect of the present invention.
[0023] The third aspect of the present invention provides a graphitized material obtained by graphitizing the needle coke as described in the second aspect of the present invention.
[0024] The preparation method of needle coke raw material, needle coke and graphitized product provided by the present invention have the following beneficial effects:
[0025] The present invention adopts asphalt types from different sources to match each other and serve as solvents for each other, thereby adjusting the reactivity and continuity of the components and adopting the method of removing primary quinoline insolubles and high-boiling point components at the lowest cost; thus, the coal tar pitch is developed in a direction that is beneficial to various anisotropic components, and high-quality and low-cost needle coke is obtained. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:
[0027] Figure 1 The figure is a schematic diagram of the process of preparing needle coke raw material of the present invention. DETAILED DESCRIPTION
[0028] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.
[0029] The existing technology basically adopts the solvent method, the asphalt purification process is complicated, there is little room for adjusting the asphalt components, and there is no room for adjusting the reactivity of the asphalt; the flash polycondensation method adopts thermal modification and distillation methods to adjust the components, and the reactivity is adjusted, but the yield is extremely low and the cost is high. In view of the above situation, the present invention uses asphalt of different sources and types to match with petroleum-based heavy oil or petroleum-based cracking oil, which are solvents for each other, adjust the reactivity of the components and the continuity of the components, and at the same time adopt the lowest cost technical means to remove the primary quinoline insolubles in the simplest way, so that the asphalt develops in a direction that is more conducive to anisotropic components, and obtains high-quality and low-cost needle coke.
[0030] The present invention studies the influence of the difference in aromaticity and oil fractions between coal tar pitch and petroleum residue on the coke grade, and recognizes that by mixing a certain petroleum fraction with coal tar pitch within a specific range, removing insoluble matter and then coking, pitch coke with an excellent needle coke structure can be produced.
[0031] Combination Figure 1 As shown, a method for preparing a needle coke raw material of the present invention comprises the following steps:
[0032] S1, mixing coal tar pitch with petroleum-based heavy oil or petroleum-based cracking oil, and obtaining a mixture after heating and stirring;
[0033] Coal tar pitch is a soft pitch obtained by distilling coal tar produced during coal dry distillation and removing light oil. There are no major restrictions on the petroleum-based heavy oil used, and generally, A heavy oil, B heavy oil, C heavy oil, etc. sold on the market can be used. The petroleum-based cracking oil used is selected from one of the catalytic cracking residual oil and the hydrocracking residual oil produced by the petrochemical industry, among which the catalytic cracking residual oil is preferred.
[0034] In the total amount of coal tar pitch and petroleum-based heavy oil or petroleum-based cracking oil, the petroleum-based heavy oil or petroleum-based cracking oil accounts for 10-70wt% of the total amount. When the petroleum-based heavy oil or petroleum-based cracking oil is less than 10wt%, it is difficult to overcome the insoluble precipitate, and no good product can be obtained during coking. When the petroleum-based heavy oil or petroleum-based cracking oil is greater than 70wt%, although needle coke can be generated during coking, the effect is not good because the yield is low and the distillation and metal vanadium contained in the petroleum-based residual oil can mix into the needle coke. In a further preferred embodiment, when the petroleum-based heavy oil or petroleum-based cracking oil accounts for 25-50wt% of the total amount, needle coke with a needle-like structure can be obtained.
[0035] When the two raw materials are mixed, the heating temperature is 200-320℃, preferably 250-310℃. When the heating temperature is lower than 200℃, the insoluble matter contains some semi-solid matter of the mixture, which is not economical. When the heating temperature exceeds 320℃, the difference in specific gravity between the insoluble matter and the mixture is small, which makes it difficult to separate and the heat loss is large. The heating time is preferably 1-4h. A general mixer can usually be used for stirring during the heating process. Since light oil evaporates during heating and stirring, it is necessary to reflux the light oil while stirring.
[0036] S2, after the mixture is allowed to stand and cool, an insoluble precipitate is removed by a tilting method to obtain a needle coke raw material.
[0037] After the mixture is cooled by standing, the temperature for separating the insoluble precipitate is 60-200°C, preferably 150-200°C. When the temperature of the mixture is lower than 60°C, the mixture and the insoluble precipitate are difficult to separate and are mixed, so it is not economical; when the temperature of the mixture exceeds 200°C, the insoluble precipitate cannot be completely precipitated, and a good product cannot be obtained after coking. Forced cooling is not suitable during standing cooling, and natural cooling can be used; then the mixture after standing cooling is separated into light and heavy phases by a tilting method to remove the insoluble precipitate, and the light phase is obtained as the needle coke raw material; the quinoline insoluble matter (QI) content in the needle coke raw material is ≤0.2wt%, and the yield of the needle coke raw material is ≥85wt%.
[0038] Through the above treatment, the reactivity of the needle coke raw material components and the continuity of the components are adjusted, wherein the reactivity and continuity of the components are an overall concept and can be characterized by the aromaticity index fa. The aromaticity index fa of the needle coke raw material of the present invention is in the range of 0.75 to 0.92, and in a further preferred embodiment, the aromaticity index fa is in the range of 0.80 to 0.90.
[0039] The present invention also provides a needle coke, which is obtained by coking the needle coke raw material obtained by the method for preparing the needle coke raw material.
[0040] The present invention also provides a graphite, wherein the graphite obtained by graphitizing needle coke in a graphite furnace has a graphite lattice constant Graphite crystal thickness in the C-axis direction The thermal expansion coefficient of the graphite in the direction parallel to the needle structure is ≤1.35×10 -6 / ℃(e.g. 1.20×10 -6 / ℃~1.35×10 -6 / ℃).
[0041] The preparation method of the needle coke raw material, the needle coke and the graphitized product of the present invention are further introduced below with reference to specific examples.
[0042] Example 1
[0043] The method for preparing a needle coke raw material in this embodiment has the following specific process:
[0044] Soft asphalt with a softening point of 24.5°C (ring and ball method), 31.26% Conradson carbon residue, and 0.54% sulfur is mixed with petroleum-based heavy oil with a viscosity of 93.6 centistokes (50°C), 6.39% Conradson carbon residue, and 2.75% sulfur at a total amount of 50%, and heated and stirred at about 310°C while refluxing the light oil, and then left to cool at room temperature. When the mixture is reduced to 180°C, the insoluble precipitate is removed by the tilting method to obtain a needle coke raw material. The yield of the needle coke raw material after removing the insoluble precipitate is about 93%, the QI of the needle coke raw material is 0.18wt%, and the aromaticity index fa is 0.89.
[0045] After the needle coke raw material was kept at about 400°C for 24 hours, the temperature was raised to 650°C at a heating rate of 1°C / min. After being kept at 650°C for 30 minutes, the temperature was raised to 950°C at a heating rate of 3°C / min and kept at this temperature for 30 minutes for coking to obtain needle coke with excellent needle structure.
[0046] The needle coke was graphitized in a graphitization furnace at 2000°C in an argon-helium atmosphere to obtain a graphitized product. The graphite lattice constant Co(002) and the graphite crystal thickness Lc(002) in the C-axis direction of the graphite were determined by X-ray analysis. The thermal expansion coefficient of graphite between 0℃ and 7600℃ was measured to be 1.29×10 -6 / ℃.
[0047] Example 2
[0048] The method for preparing a needle coke raw material in this embodiment has the following specific process:
[0049] The soft asphalt used in Example 1 was mixed with 25% of the total amount of petroleum catalytic cracking residual oil with a viscosity of 146CP (50°C), a residual carbon of 9.40%, and a sulfur of 0.37%. After heating and stirring for 3 hours while refluxing the light oil fraction at about 210°C, the mixture was allowed to stand and cool at room temperature. When the temperature of the mixture was reduced to 140°C, the insoluble precipitate was separated by the tilting method to obtain a needle coke raw material. The yield of the needle coke raw material after removing the insoluble precipitate was about 87%, the QI of the needle coke raw material was 0.15wt%, and the aromaticity index fa was 0.83.
[0050] The needle coke raw material was coked in the same manner as in Example 1 to obtain needle coke. Then, the graphitization was performed in the same manner as in Example 1 to obtain a graphitized product. The graphite lattice constant Co(002) and the graphite crystal thickness Lc(002) in the C-axis direction were determined by X-ray analysis. The thermal expansion coefficient of graphite was measured by dilatometer between 0 and 600 °C. The coefficient of thermal expansion in the direction parallel to the needle structure was 1.34×10 -6 / ℃.
[0051] Example 3
[0052] The preparation method of needle coke in this embodiment is the same as that in Example 1.
[0053] The needle coke raw material same as that in Example 1 was heated to about 490°C and loaded from the bottom of the coking tower to maintain the pressure in the tower at about 4 kg / cm 2 The coking temperature is about 440-480°C, and the delayed coking method is used. After 24 hours of coking, needle coke with a needle-like structure is obtained. The yield of the needle coke is about 42.5%. After the needle coke is heat-treated at 1200°C for 30 minutes, it is graphitized in the same way as in Example 1 to obtain a graphitized product, and the same measurement is performed. The results are The thermal expansion coefficient of graphite was measured by dilatometer between 0 and 600 °C. The coefficient of thermal expansion in the direction parallel to the needle structure was 1.25×10 -6 / ℃.
[0054] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.
Claims
1. A method for preparing needle coke raw material, characterized in that: The following steps are involved: S1, mixing coal tar pitch with petroleum-based heavy oil or petroleum-based cracking oil, and obtaining a mixture after heating and stirring; S2, after the mixture is allowed to stand and cool, insoluble precipitates are removed by a tilting method to obtain a needle coke raw material.
2. The method for preparing needle coke raw material according to claim 1, characterized in that: In step S1: In the total amount of coal tar pitch and petroleum-based heavy oil or petroleum-based cracking oil, the petroleum-based heavy oil or petroleum-based cracking oil accounts for 10 to 70 wt % of the total amount; and / or The petroleum cracking oil is selected from catalytic cracking residual oil and hydrocracking residual oil produced by the petrochemical industry.
3. The method for preparing needle coke raw material according to claim 2, characterized in that: In the total amount of coal tar pitch and petroleum-based heavy oil or petroleum-based cracking oil, the petroleum-based heavy oil or petroleum-based cracking oil accounts for 25-50wt% of the total amount.
4. The method for preparing needle coke raw material according to claim 1, characterized in that: In step S1: During the heating process, the heating temperature is 200-320° C. and the heating time is 1-4 hours; and / or During the heating process, the light oil is refluxed while stirring.
5. The method for preparing needle coke raw material according to claim 4, characterized in that: In the step S1, the heating temperature is 250-310°C.
6. The method for preparing needle coke raw material according to claim 1, characterized in that: In the step S2, the cooling method is natural cooling; the temperature of the mixture when removing insoluble precipitates after standing and cooling is 60-200°C.
7. The method for preparing needle coke raw material according to claim 6, characterized in that: In the step S2, the temperature of the mixture when removing the insoluble precipitate after standing and cooling is 150-200°C.
8. The method for preparing needle coke raw material according to claim 1, characterized in that: In the step S2, the quinoline insoluble matter content of the needle coke raw material is ≤0.2wt%, and the aromaticity index fa is 0.75-0.
92.
9. Needle coke obtained by coking a needle coke raw material obtained by the method for preparing a needle coke raw material according to any one of claims 1 to 8.
10. A graphite, characterized in that: The needle coke according to claim 9 is graphitized to obtain the product.