A process for producing high-end isotropic coke

Abstract

The present invention provides a process for producing high-end isotropic coke, which relates to the field of carbon materials. Wax oil raw materials are put into a wax oil raw material heating furnace for thermal cracking, and the gas phase products of the pyrolysis reactor enter a fractionation tower, and the liquid phase products enter a mixed raw material heating furnace; polymerization initiator and circulating oil also enter the furnace, and after mixing with the liquid phase products, they enter a coking reactor to generate coke, and the gas phase products enter a fractionation tower, and the solid phase products flow out as isotropic coke. The fractionation tower separates the feed oil and gas into cracking gas, light fraction oil, and heavy fraction oil, and the bottom liquid phase is the circulating oil that returns to the entrance of the mixed raw material heating furnace. The method solves the problem that the existing isotropic coke raw materials contain high coking precursors, ash, and sulfur and nitrogen elements, and the resulting coke has poor uniformity, which causes coking and blockage of the heating furnace and high-temperature pipelines, affecting the long-term safe operation of the device and the stability of product quality, and effectively improves production efficiency and product quality.

Description

Technical Field

[0001] The invention relates to the technical field of carbon materials, and in particular to a process for producing high-end isotropic coke. Background Art

[0002] Isotropic coke refers to coke whose mechanical, electrical and thermal properties, such as coefficient of thermal expansion (CTE), resistivity and other indicators, are roughly the same in all directions; the microscopic optical structure in all directions is a fine mosaic structure, and there is no single orientation. High-end isotropic coke is widely used in cutting-edge fields such as semiconductors, military industry, aerospace, and graphite for the nuclear industry. At present, domestic high-end isotropic coke mainly relies on imported products.

[0003] For example, in the application number: CN201410211421.9, asphalt-like substances containing high quinoline insolubles and high toluene insolubles in coal tar are mixed, heat-treated, carbonized and coked to obtain isotropic coke. However, because the asphalt contains solid impurities, the obtained isotropic coke has a coarse mosaic structure with extremely uneven tissue, and the coking rate of the heating furnace equipment is too fast, making it difficult to produce continuously.

[0004] However, the current mainstream preparation method of isotropic coke is to use coal tar, residual oil or ethylene tar with high aromatic content as raw materials, and prepare isotropic coke through air oxidation or catalytic polycondensation, and then high-temperature carbonization. However, since the above raw materials contain relatively high coking precursors, ash, sulfur, nitrogen and other impurities, the coke formed is a coarse mosaic structure coke with poor uniformity, which belongs to the low-end isotropic coke product. This type of low-end isotropic coke can only be used as a cheap raw material in the fields of lithium battery negative electrode materials, isotropic graphite preparation, etc. In addition, the above raw materials have high coking reaction activity. During the high-temperature carbonization process, it is very easy to cause coking and blockage of the heating furnace and high-temperature pipelines, which seriously affects the long-term safe operation of the device and is not conducive to the stability of product quality. Summary of the invention

[0005] In view of this, the present invention provides a process for producing high-end isotropic coke. The unique structure and properties of high-end isotropic coke require that its production raw materials must have the characteristics of high aromatics, high reactivity and low impurity content. Its production process can flexibly control the coke structure and operate safely and stably for a long period of time. Therefore, how to solve the above technical problems is the key issue in developing independent high-end isotropic coke production technology and ensuring the supply of key carbon materials.

[0006] The present invention provides a process for producing high-end isotropic coke, which has the following purposes and effects:

[0007] Step 1: The wax oil raw material enters the wax oil raw material heating furnace through the wax oil raw material pipe, is heated to 400°C-450°C, and enters the pyrolysis reactor to complete the thermal cracking reaction.

[0008] Step 2: The gas phase product of the pyrolysis reactor flows out from the first gas phase product pipe at the top and enters the distillation tower, and the liquid phase product flows from the liquid phase product pipe to the mixed raw material heating furnace.

[0009] Step three, the polymerization initiator and circulating oil enter the mixed raw material heating furnace through the polymerization initiator pipe and the circulating oil pipe, are mixed with the liquid phase product of the pyrolysis reactor, are heated to 430°C-520°C in the mixed raw material heating furnace, and then enter the coking reactor to complete the coking reaction.

[0010] In step 4, the gas phase product of the coking reactor flows out from the second gas phase product pipe at the top and enters the fractionation tower, and the solid phase product at the bottom of the coking reactor flows out as isotropic coke through the isotropic coke pipe.

[0011] Step 5: The distillation tower separates the feed oil and gas into cracked gas, light fraction oil and heavy fraction oil, which are respectively led out through the cracked gas pipe, light fraction oil pipe and heavy fraction oil pipe. The liquid phase at the bottom of the distillation tower is circulating oil, and the circulating oil returns to the inlet of the mixed raw material heating furnace through the circulating oil pipe.

[0012] Furthermore, the reaction pressure of the pyrolysis reactor in step 2 is 0.1Mpa-2.0Mpa, the reaction temperature is 390-450°C, and the reaction time is 0.5h-3.0h.

[0013] Furthermore, in step three, the polymerization initiator accounts for 5w%-30w% of the total feed of the mixed raw material heating furnace; the circulating oil accounts for 0-50w% of the total feed of the mixed raw material heating furnace.

[0014] Furthermore, in step 4, the reaction pressure of the coke reactor is 0.1Mpa-1.0Mpa, the reaction temperature is 400-500°C, and the reaction time is 18h-48h.

[0015] Furthermore, the heating furnace used in step three is a cylindrical spiral coil heating furnace, the flow velocity in the heating furnace tube is 2-20m / s, and the average thermal intensity of the furnace tube is 20-35kW / m2.

[0016] Furthermore, the wax oil raw material in step 1 is one or more of straight-run wax oil, hydrogenated wax oil, and coker wax oil with high aromatic content.

[0017] Furthermore, the total aromatic content of the wax oil raw material in step 1 is not less than 50w%, the ash content does not exceed 0.05w%, the sulfur content does not exceed 0.3w%, and the distillation range is 300°C-550°C.

[0018] Furthermore, the polymerization initiator in step three is low-sulfur ethylene tar.

[0019] Beneficial effects:

[0020] The use of high aromatic wax oil raw materials with low heteroatom content can overcome the problem of uneven isotropic coke structure and coarse mosaic structure caused by high coking precursors in the raw materials in the prior art. Through the thermal cracking reaction of wax oil, the easily cracked saturated hydrocarbon groups in the raw materials are reduced, and the aromatic content in the raw materials after the reaction is further increased, which is conducive to the preparation of isotropic coke with high graphitization degree.

[0021] In addition, during the research process, the applicant of this patent discovered that the coking rate of wax oil raw materials is relatively low, but by introducing polymerization initiators, the coking carbonization rate of the mixed raw materials can be regulated, which provides key conditions for the production of high-end isotropic coke with a fine mosaic structure and uniform tissue distribution, and the polymerization rate can be flexibly regulated by the proportion of polymerization initiators.

[0022] In addition, the present invention mixes wax oil raw materials with lower coking rate, circulating oil and polymerization initiator, which can flexibly adjust the coking rate and solve the blockage problem of heating furnace and high-temperature pipeline in the prior art, and can realize long-term safe operation of the device, which can further reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings of the embodiment are briefly introduced below.

[0024] The drawings described below are only related to some embodiments of the present invention, but are not intended to limit the present invention.

[0025] In the attached picture:

[0026] Figure 1 It is a schematic diagram of the process of the present invention.

[0027] List of reference numerals;

[0028] 1. Wax oil raw material pipe; 101. Wax oil raw material heating furnace; 102. Pyrolysis reactor; 2. First gas phase product pipe; 201. Mixed raw material heating furnace; 202. Coke reactor; 203. Distillation tower; 3. Liquid phase product pipe; 4. Polymerization initiator pipe; 5. Circulating oil pipe; 6. Second gas phase product pipe; 7. Isotropic coke pipe; 8. Cracking gas pipe; 9. Light fraction oil pipe; 10. Heavy fraction oil pipe. DETAILED DESCRIPTION

[0029] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" are generally understood in combination with the directions shown in the drawings and the directions in actual applications, and "inside and outside" refer to the inside and outside of the outline of the component.

[0030] As attached Figure 1As shown, the detailed process of the high-end isotropic coke production method of the present invention is described as follows:

[0031] Step 1: The wax oil raw material enters the wax oil raw material heating furnace 101 through the wax oil raw material pipe 1, is heated to 400°C-450°C, and enters the pyrolysis reactor 102 to complete the thermal cracking reaction; Step 2: The gas phase product of the pyrolysis reactor 102 flows out from the first gas phase product pipe 2 at the top and enters the fractionation tower 203, and the liquid phase product flows from the liquid phase product pipe 3 to the mixed raw material heating furnace 201; Step 3: The polymerization initiator and the circulating oil enter the mixed raw material heating furnace 201 through the polymerization initiator pipe 4 and the circulating oil pipe 5, and after being mixed with the liquid phase product of the pyrolysis reactor 102, the mixed raw material heating furnace 201 heats the mixture. After being heated to 430℃-520℃, it enters the coking reactor 202 to complete the coking reaction; Step 4, the gaseous product of the coking reactor 202 flows out from the second gaseous product pipe 6 at the top and enters the fractionation tower 203, and the solid phase product at the bottom of the coking reactor 202 flows out as isotropic coke through the isotropic coke pipe 7; Step 5, the fractionation tower 203 separates the feed oil and gas into cracking gas, light fraction oil and heavy fraction oil, which are respectively led out through the cracking gas pipe 8, the light fraction oil pipe 9 and the heavy fraction oil pipe 10, and the liquid phase at the bottom of the fractionation tower 203 is circulating oil, and the circulating oil returns to the entrance of the mixed raw material heating furnace 201 through the circulating oil pipe 5.

[0032] Embodiment 1;

[0033] Table-1 Wax oil raw material composition in the embodiment;

[0034]

[0035]

[0036] The coking wax oil and hydrogenated wax oil (mass ratio 1:1) in Table 1 are used as raw materials. First, the reaction pressure in the pyrolysis reactor (102) is 0.1Mpa-2.0Mpa, the reaction temperature is 390-450℃, and the reaction time is 0.5h-3.0h; then, the liquid product is mixed with 10w% ethylene tar and 30w% circulating oil, heated to 500℃ in the mixed raw material heating furnace 201, and reacted in the coking reactor 202 at a temperature of 480℃, a pressure of 0.5Mpa, and a reaction time of 24h to obtain isotropic coke, and its organizational structure is characterized. The results are shown in Table 2; the results show that the isotropic coke prepared in Example 1 of the present invention has a uniform organizational structure and a typical fine mosaic structure. The prepared isotropic true density is 2.05g·cm -3 , ash content 0.03w%, isotropy 1.05.

[0037] Table-2 Characterization data of isotropic coke structure prepared in Example 1;

[0038]

[0039]

[0040] Embodiment 2;

[0041] The coking wax oil and hydrogenated wax oil (mass ratio 1:3) in Table 1 were used as raw materials. First, the reaction temperature was 420°C, the pressure was 0.8 MPa, and the reaction time was 3 h in the pyrolysis reactor 102; then, the liquid product 103 was mixed with 15w% ethylene tar and 40w% circulating oil, heated to 510°C in the mixed raw material heating furnace 201, and the reaction temperature was 490°C, the pressure was 0.5 MPa, and the reaction time was 18 h in the coking reactor 202 to obtain isotropic coke; the results show that the isotropic coke prepared in Example 2 of the present invention has a uniform microstructure and a typical fine mosaic structure; the prepared isotropic coke has a true density of 2.07 g·cm -3 , graphitization degree 90%, ash content 0.03w%, and isotropy degree 1.03.

[0042] Table-3 Statistical results of isotropic focal optical organization prepared in Example 2;

[0043] Optical structure name Data Remarks M (Mosaic) / % 62.3 Md (Microdomain) / % 27.4 Sad (Short acicular domain) / % 4.4 Mid (Middle domain) / % 3.3 Ad (Middle acicular domain) / % 1.2 D (Wide domain) / % 1.4 Bd (Long acicular domain) / % 0 Optical structure index OTI 1009

[0044] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A process for producing high-end isotropic coke, characterized in that: The following steps are involved: Step 1: the wax oil raw material passes through the wax oil raw material pipe (1) into the wax oil raw material heating furnace (101), is heated to 400° C.-450° C., and enters the pyrolysis reactor (102) to complete the thermal cracking reaction; Step 2: The gas phase product of the pyrolysis reactor (102) flows out from the first gas phase product pipe (2) at the top and enters the fractionation tower (203); the liquid phase product of the pyrolysis reactor (102) flows from the liquid phase product pipe (3) to the mixed raw material heating furnace (201); Step 3: The polymerization initiator and the circulating oil enter the mixed raw material heating furnace (201) through the polymerization initiator pipe (4) and the circulating oil pipe (5), are mixed with the liquid phase product of the pyrolysis reactor (102), are heated to 430° C.-520° C. in the mixed raw material heating furnace (201), and then enter the coking reactor (202) to complete the coking reaction; the polymerization initiator is low-sulfur ethylene tar; Step 4: the gas phase product of the coke production reactor (202) flows out from the second gas phase product pipe (6) at the top and enters the fractionation tower (203); the solid phase product at the bottom of the coke production reactor (202) flows out as isotropic coke through the isotropic coke pipe (7); Step 5: The fractionation tower (203) separates the feed oil gas into cracked gas, light fraction oil and heavy fraction oil, which are respectively led out through the cracked gas pipe (8), the light fraction oil pipe (9) and the heavy fraction oil pipe (10); the liquid phase at the bottom of the fractionation tower (203) is circulating oil, and the circulating oil is returned to the inlet of the mixed raw material heating furnace (201) through the circulating oil pipe (5); The total aromatic content of the wax oil raw material is not less than 50w%, the ash content does not exceed 0.05w%, the sulfur content does not exceed 0.3w%, and the distillation range of the wax oil raw material is 300°C-550°C.

2. The process for producing high-end isotropic coke according to claim 1, characterized in that: The reaction pressure of the pyrolysis reactor (102) in step 1 is 0.1Mpa-2.0Mpa, the reaction temperature is 390-450°C, and the reaction time is 0.5h-3.0h.

3. The process for producing high-end isotropic coke according to claim 1, characterized in that: In step 3, the polymerization initiator accounts for 5w%-30w% of the total feed of the mixed raw material heating furnace (201); and the circulating oil accounts for 0-50w% of the total feed of the mixed raw material heating furnace (201).

4. The process for producing high-end isotropic coke according to claim 1, characterized in that: In the step 3, the reaction pressure of the coke reactor (202) is 0.1Mpa-1.0Mpa, the reaction temperature is 400-500°C, and the reaction time is 18h-48h.

5. The process for producing high-end isotropic coke according to claim 1, characterized in that: The mixed raw material heating furnace (201) is a cylindrical spiral coil heating furnace. The flow rate in the mixed raw material heating furnace tube in step 3 is 2-20 m / s, and the average heat intensity of the furnace tube is 20-35 kW / m 2 .

6. The process for producing high-end isotropic coke according to claim 1, characterized in that: The wax oil raw material in the step 1 is one or more of straight-run wax oil, hydrogenated wax oil, and coker wax oil with a high aromatic content.

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