A method for co-production of mesophase pitch and high-quality needle coke
The method of preparing high-quality needle coke through a three-step process of thermal polymerization-sedimentation-coking solves the problem of unstable needle coke quality in existing technologies, realizes the co-production of mesophase pitch and needle coke, and improves product quality and production flexibility.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN CHANGLING PETROCHEM SCI & TECH DEV CO LTD
- Filing Date
- 2023-11-03
- Publication Date
- 2026-07-14
AI Technical Summary
Existing needle coke production equipment suffers from quality instability, including inconsistent quality between the upper, middle, and lower parts of a single tower and unstable quality control between multiple towers. Furthermore, the existing two-step method for preparing mesophase pitch has a low anisotropic structure content, leading to unstable needle coke quality.
A three-step method of thermal polymerization-sedimentation-coking was adopted to prepare low softening point mesophase pitch with an anisotropic structure content of more than 90% through thermal polymerization and sedimentation separation technology. During the coking process, a heated medium was used for coking and reheating to ensure the quality stability of needle coke.
This technology enables the co-production of mesophase pitch and needle coke, improving product quality stability and flexibility, solving the problems of uniformity in needle coke pulling and heating, and ensuring the production of high-quality needle coke.
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Figure CN117264646B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for the co-production of mesophase pitch and high-quality needle coke. Specifically, it involves using heavy oil as raw material and preparing mesophase pitch with an anisotropic structure content greater than 90% and high-quality needle coke through a three-step process of thermal polymerization-sedimentation-coking. This belongs to the field of novel high-quality carbon material preparation technology. Background Technology
[0002] Mesophase pitch is a mixture of various polycyclic aromatic hydrocarbons with relative molecular masses ranging from 370 to 2000. Its excellent properties have established it as a superior precursor for carbon materials, from which many high-performance carbon materials can be manufactured, such as carbon fibers, thermally conductive materials, carbon composites, and advanced battery electrodes. These advanced carbon materials play a significant role in numerous fields, including defense, aerospace, and daily life.
[0003] Needle coke is a special type of coke produced during the thermal conversion of coal-based or oil-based raw materials. It is a raw material for producing carbon products such as graphite electrodes, lithium-ion battery anode materials, and carbon composite materials. Carbon products made from needle coke are characterized by high purity, low ablation, and low coefficient of thermal expansion, and are therefore widely used in metallurgy, new energy, and other fields. Existing needle coke production equipment suffers from quality instability, including inconsistent quality of needle coke in the upper, middle, and lower parts of a single tower, and unstable quality control in multi-tower production. The main reason for this is that the delayed coking process currently used in needle coke production completes the entire process from heavy oil to needle coke. Due to the inconsistency in the composition of heavy oil, the coking process is difficult to control, making it difficult to guarantee the quality of needle coke. Furthermore, uneven temperature distribution in the upper, middle, and lower parts of the coking tower and insufficient control of the needle coke pulling process result in needle coke that is not of stable quality and has a consistent morphology and structure.
[0004] Patents CN106635142, CN106544045, CN106147835, and CN104650938 disclose a two-step process for preparing needle coke. Although pre-coking increases the anisotropic structural component content of the heavy pitch entering the coking tower, all of these methods suffer from the problem of low anisotropic structural content in the heavy pitch, leading to unstable needle coke quality. CN106544045 uses mesophase pitch with an anisotropic content of 25-80% as raw material and employs a two-step carbonization method to prepare needle coke. This process requires a solvation reaction, which is complex and energy-intensive.
[0005] CN1132895C and CN1172147A employ a two-stage coking method to produce needle coke. In a delayed coking unit, needle coke is prepared by heating in two stages using light oil. However, the heated light oil inevitably polymerizes at high temperatures to form coke, which affects the quality of the needle coke product. Summary of the Invention
[0006] This invention overcomes the shortcomings of existing technologies and provides a co-production process for mesophase pitch and needle coke. Using heavy oil as raw material, it employs a three-step process of thermal polymerization-sedimentation-coking to co-produce low-softening-point mesophase pitch with an anisotropic structure content greater than 90% and high-quality needle coke. To achieve the above objectives, this invention adopts the following technical solutions:
[0007] Using heavy oil as raw material, a three-step process of thermal polymerization-sedimentation-coking is adopted to co-produce mesophase pitch and needle coke. The mesophase pitch with low softening point and an anisotropic structure content of more than 90% is obtained by using thermal polymerization and sedimentation separation technology. The mesophase pitch is heated in a heating furnace and then enters the coking tower. High-quality needle coke is prepared by using the coking and reheating effects of the heated medium.
[0008] The specific process includes the following steps:
[0009] S1: Heavy oil is heated to a certain temperature in a heating furnace and then enters a thermal polymerization reactor to obtain mesophase pitch with an anisotropic structure of 20-50%.
[0010] S2: 20-50% anisotropic mesophase asphalt enters the settling tank to obtain low softening point mesophase asphalt with anisotropic structure content greater than 90%. The upper layer asphalt is mixed with heavy oil and then used as feed for the thermal polymerization reactor.
[0011] S3: A portion of the mesophase pitch is directly extracted from the bottom of the settling tank as the mesophase pitch product; another portion of the mesophase pitch is heated to a certain temperature in a heating furnace and then enters the coking tower; at the same time, a high-temperature heated medium of 500-550℃ is introduced into the bottom of the coking tower to pull out the mesophase pitch and reheat it, thereby obtaining high-quality needle coke. The needle coke is discharged from the discharge port at the bottom of the coking tower after hydraulic decoking.
[0012] S4: Oil and gas and coke pulling media generated during the coking process are discharged from the top of the reactor.
[0013] The aforementioned process for preparing mesophase pitch and needle coke employs a three-step method: thermal polymerization, sedimentation, and coking.
[0014] The mesophase pitch is prepared using thermal polymerization and sedimentation separation techniques.
[0015] The heavy oil is heated to 350-450℃ in a heating furnace.
[0016] A portion of the mesophase pitch is heated to 490-530°C in a heating furnace before entering the coking tower.
[0017] The needle coke preparation process involves heating low-softening-point mesophase pitch with an anisotropic structure content greater than 90% before feeding it into a coking tower, where a heated medium is used for coke pulling and reheating.
[0018] The heating medium is at least one of water, N2, methane, ethane, propane, butane, liquefied petroleum gas, natural gas, dry gas, coking gas, gasoline, jet fuel, kerosene, and diesel.
[0019] The heavy oil is selected from at least one of medium- and low-temperature coal tar, high-temperature coal tar and its fractions, ethylene cracking tar, and petroleum heavy fractions.
[0020] The heavy oil described herein meets the following requirements: asphaltene content less than 10%, sulfur content less than 0.5%, aromatic hydrocarbon content greater than 50%, and ash content less than 0.05%.
[0021] The thermal polymerization reaction temperature is 350-450℃, the reaction pressure is 0.5-5.5MPa, and the reaction time is 10-50h.
[0022] The material temperature inside the settling tank is 300-400℃, the pressure is atmospheric pressure, and the settling time is 2-5 hours.
[0023] The coking tower has a temperature of 490-530℃, a pressure of 0-1 MPa, and a coking time of 2-8 hours.
[0024] In the thermal polymerization reactor, heavy oil undergoes a rapid reaction at high temperature (350-450℃) and high pressure (0.5-5.5Mpa) to obtain mesophase microspheres and fused mesophase asphalt. In order to avoid further condensation of the mesophase asphalt at high temperature, forming products with high softening points and carbon powder, when the anisotropic structure in the mesophase asphalt is 20-50%, the mesophase asphalt is pumped into a low-temperature settling tank for settling.
[0025] Inside the settling tank, mesophase pitch settles at low temperature (300-400℃) and normal pressure. The low temperature helps slow down the polymerization rate and extent of the mesophase pitch, resulting in a lower softening point. It also prevents excessive carbonization that could lead to carbon powder clogging the pipes. Normal pressure allows the lighter components in the system to escape from the reaction system, thereby reducing the distance between the mesophase microspheres and promoting their fusion and growth. Through settling, a low-softening-point mesophase pitch with an anisotropic structure content greater than 90% can be obtained. This mesophase pitch can be sold as a product for downstream applications in mesophase pitch-based carbon fibers, mesophase pitch and foamed carbon, mesophase pitch-based electrode materials, and other mesophase pitch-based carbon / carbon composites.
[0026] Inside the coking tower, mesophase pitch with a low softening point and an anisotropic structure content greater than 90% undergoes deep carbonization at high temperature (490-530℃) and low pressure (0-1Mpa). The mesophase pitch with an anisotropic structure content greater than 90% is further carbonized to prepare needle coke, ensuring the consistency of the feed to the coking tower, thereby significantly improving the quality stability of needle coke. At the same time, a heated medium is injected for coke pulling and reheating. The injection of the heated medium can effectively solve the problems of uniformity of needle coke pulling and uniformity of heating, which is conducive to the release of volatiles and obtaining needle coke with a consistent morphology and structure. The reheating of the heated medium can make the temperature distribution in the upper, middle and lower parts of the coking tower relatively uniform, improving the uniformity of the quality of needle coke products in the upper, middle and lower parts of the coking tower.
[0027] The advantages of this invention compared to existing preparation methods are:
[0028] (1) This invention is a three-step method for co-producing mesophase pitch and high-quality needle coke. Currently, the carbon material market fluctuates greatly. This invention can adjust the products in a timely manner according to the market and improve the ability of the equipment to resist risks.
[0029] (2) The preparation of mesophase asphalt involves separating thermal polymerization and sedimentation into two steps. By combining thermal polymerization and sedimentation separation, and independently controlling the thermal polymerization reactor and sedimentation tank, low softening point mesophase asphalt with an anisotropic structure content of more than 90% can be prepared. At the same time, the present invention can adjust the reaction conditions in real time according to the changes in the composition of heavy oil, making the operation flexible and the raw material adaptability strong.
[0030] (3) Preparation of needle coke: Using low softening point mesophase pitch with an anisotropic structure content of more than 90% as feed to the coking tower can ensure the consistency of the feed, which is beneficial to improve the quality of needle coke and ensure the stability of needle coke quality.
[0031] (4) At present, domestic industrial needle coke production equipment basically does not inject heated medium. The injection of heated medium can effectively solve the problems of uniformity of needle coke pulling and uniformity of heating. Under the action of airflow shear force, the intermediate phase molecules are arranged in an orderly manner and solidified to generate needle coke products with higher crystallinity. Attached Figure Description
[0032] Figure 1 This is a process flow diagram of the co-production of mesophase pitch and high-quality needle coke according to the present invention.
[0033] In the diagram: 1-thermal polymerization reactor; 2-sedimentation tank; 3-coking tower; P-1, P-2, P-3-pumps; E-1, E-2, E-3-heat exchanger. Detailed Implementation
[0034] The following describes, in conjunction with embodiments, the method provided by the present invention for the three-step co-production of mesophase pitch and high-quality needle coke using heavy oil as raw material.
[0035] Example 1:
[0036] Low-temperature coal tar with a bituminous content of 4%, sulfur content of 0.32%, aromatic content of 65%, and ash content of 0.02% was heated and then fed into a thermal polymerization reactor. The reaction temperature of the thermal polymerization reactor was controlled at 350℃ and the reaction pressure at 0.5 MPa. After 50 hours of reaction, the mixture was fed into a settling tank. The temperature of the settling tank was controlled at 300℃ and the settling pressure at atmospheric pressure. After 5 hours of settling, the isotropic bitumen in the upper part of the settling tank was mixed with the raw material, heated, and then fed into the thermal polymerization reactor. Low-softening-point mesophase bitumen was obtained at the bottom. According to market demand, part of the mesophase bitumen product was sold directly as a product, and part of the mesophase bitumen was fed into a coking tower for coking. The mesophase bitumen was heated and coked by superheated steam. The temperature in the coking tower was controlled at 530℃ and the pressure at 1 MPa. After 2 hours of coking, needle coke was obtained. The properties of the needle coke product were analyzed after calcination. The properties of the mesophase bitumen and needle coke (after calcination) are shown in Table 1.
[0037] Example 2
[0038] High-temperature coal tar with a bituminous content of 6%, sulfur content of 0.37%, aromatic content of 75%, and ash content of 0.04% was heated and then fed into a thermal polymerization reactor. The reaction temperature in the thermal polymerization reactor was controlled at 400℃ and the reaction pressure at 2.5 MPa. After 20 hours of reaction, the mixture was fed into a settling tank. The temperature in the settling tank was controlled at 350℃ and the settling pressure at atmospheric pressure. After 3 hours of settling, the isotropic bitumen in the upper part of the settling tank was mixed with the raw material, heated, and then fed into the thermal polymerization reactor. Low-softening-point mesophase bitumen was obtained at the bottom. According to market demand, part of the mesophase bitumen product was sold directly as a product, and part of the mesophase bitumen was fed into a coking tower for coking. The mesophase bitumen was heated and coked by superheated N2 with a heated medium. The temperature in the coking tower was controlled at 500℃ and the pressure at 0.5 MPa. After 6 hours of coking, needle coke was obtained. The properties of the needle coke product were analyzed after calcination. The properties of the mesophase bitumen and needle coke (after calcination) are shown in Table 1.
[0039] Example 3
[0040] Ethylene tar with a bituminous content of 5%, sulfur content of 0.35%, aromatic content of 65%, and ash content of 0.01% was heated and fed into a thermal polymerization reactor. The reaction temperature of the thermal polymerization reactor was controlled at 450℃ and the reaction pressure at 5.5 MPa. After 10 hours of reaction, the mixture was fed into a settling tank. The temperature of the settling tank was controlled at 400℃ and the settling pressure at atmospheric pressure. After 2 hours of settling, the isotropic bitumen in the upper part of the settling tank was mixed with the raw material, heated, and then fed into the thermal polymerization reactor. Low-softening-point mesophase bitumen was obtained at the bottom. According to market demand, part of the mesophase bitumen product was sold directly as a product, and part of the mesophase bitumen was fed into a coking tower for coking. The mesophase bitumen was heated and coked by superheated gasoline, a heated medium. The temperature in the coking tower was controlled at 490℃ and the pressure at 0 MPa. After 8 hours of coking, needle coke was obtained. The properties of the needle coke product were analyzed after calcination. The properties of the mesophase bitumen and needle coke (after calcination) are shown in Table 1.
[0041] Example 4
[0042] Petroleum heavy distillate with a bituminous content of 3%, sulfur content of 0.35%, aromatic content of 72%, and ash content of 0.01% was heated and fed into a thermal polymerization reactor. The reaction temperature of the thermal polymerization reactor was controlled at 450℃ and the reaction pressure at 1.0 MPa. After 30 hours of reaction, the product was fed into a settling tank. The temperature of the settling tank was controlled at 420℃ and the settling pressure at atmospheric pressure. After 3 hours of settling, the isotropic bitumen in the upper part of the settling tank was mixed with the raw material, heated, and then fed into the thermal polymerization reactor. Low-softening-point mesophase bitumen was obtained at the bottom. According to market demand, part of the mesophase bitumen product was sold directly as a product, and part of the mesophase bitumen was fed into a coking tower for coking. The mesophase bitumen was heated and coked by superheated methane, a heated medium. The temperature in the coking tower was controlled at 520℃ and the pressure at 0.2 MPa. Coking was carried out for 4 hours to obtain needle coke. The properties of the needle coke product were analyzed after calcination. The properties of the mesophase bitumen and needle coke (after calcination) are shown in Table 1.
[0043] Comparative Example 1
[0044] A heavy petroleum fraction with a bituminous content of 3%, sulfur content of 0.35%, aromatic content of 72%, and ash content of 0.01% was heated in a furnace and fed into a coking tower. The temperature inside the coking tower was controlled at 520℃ and the pressure at 0.2MPa. Coking was carried out for 4 hours to obtain needle coke. The properties of the needle coke (after calcination) were analyzed. The properties of the needle coke (after calcination) are shown in Table 1.
[0045] Comparative Example 2
[0046] Petroleum heavy distillate with a bituminous content of 3%, sulfur content of 0.35%, aromatic content of 72%, and ash content of 0.01% was heated and fed into a thermal polymerization reactor. The reaction temperature of the thermal polymerization reactor was controlled at 450℃ and the reaction pressure at 1.0 MPa. After 30 hours of reaction, the product was fed into a settling tank. The temperature of the settling tank was controlled at 420℃ and the settling pressure at atmospheric pressure. After 3 hours of settling, the isotropic bitumen in the upper part of the settling tank was mixed with the raw material, heated, and then fed into the thermal polymerization reactor. Low-softening-point mesophase bitumen was obtained at the bottom. According to market demand, part of the mesophase bitumen product was sold directly as a product, and part of the mesophase bitumen was fed into a coking tower for coking. The mesophase bitumen was heated to 520℃ and the pressure was 0.2 MPa in a heating furnace and coked for 4 hours to obtain needle coke product. The properties of the needle coke product were analyzed after calcination. The properties of the mesophase bitumen and needle coke (after calcination) are shown in Table 1.
[0047] Table 1 Properties of interphase pitch and needle coke (after calcination) in the examples
[0048]
Claims
1. A method for co-producing mesophase pitch and high-quality needle coke, using heavy oil as raw material, adopting a three-step method of thermal polymerization-sedimentation-coking to co-produce mesophase pitch and needle coke, using thermal polymerization and sedimentation separation technology to obtain low softening point mesophase pitch with an anisotropic structure content greater than 90%, the mesophase pitch is heated in a heating furnace and then enters a coking tower, using the coking and reheating effects of the heated medium to prepare high-quality needle coke; Its features Includes the following steps: S1: Heavy oil is heated to 350-450℃ in a heating furnace and then enters a thermal polymerization reactor to obtain mesophase pitch with an anisotropic structure content of 20-50%. S2: Mesophase asphalt with an anisotropic structure content of 20-50% enters the settling tank to obtain low softening point mesophase asphalt with an anisotropic structure content of more than 90%. The upper layer asphalt is mixed with heavy oil and then used as feed for the thermal polymerization reactor. S3: A portion of the mesophase pitch is directly extracted from the bottom of the settling tank as the mesophase pitch product; another portion of the mesophase pitch is heated to 490-530℃ in a heating furnace and then enters the coking tower; at the same time, a high-temperature heated medium of 500-550℃ is introduced into the bottom of the coking tower to pull out the mesophase pitch and reheat it, thereby obtaining high-quality needle coke. The needle coke is discharged from the discharge port at the bottom of the coking tower after hydraulic decoking. S4: Oil and gas and coke pulling media generated during the coking process are discharged from the top of the reactor.
2. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The heating medium is at least one of water, N2, methane, ethane, propane, butane, liquefied petroleum gas, natural gas, dry gas, coking gas, gasoline, jet fuel, kerosene, and diesel.
3. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The heavy oil is selected from at least one of medium- and low-temperature coal tar, high-temperature coal tar and its fractions, naphthalene compounds, ethylene cracking tar, and petroleum heavy fractions.
4. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The heavy oil described herein meets the following requirements: asphaltene content less than 10%, sulfur content less than 0.5%, aromatic hydrocarbon content greater than 50%, and ash content less than 0.05%.
5. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The thermal polymerization reaction temperature is 350-450℃, the reaction pressure is 0.5-5.5MPa, and the reaction time is 10-50h.
6. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The material temperature inside the settling tank is 300-400℃, the pressure is atmospheric pressure, and the settling time is 2-5 hours.
7. The method for co-producing mesophase pitch and high-quality needle coke according to claim 1, characterized in that... The coking tower has a temperature of 490-530℃, a pressure of 0-1 MPa, and a coking time of 2-8 hours.