A method for producing raw materials for high-grade needle coke

Abstract

A method for producing high-grade needle coke raw materials, the invention provides a method for introducing hydrogenated diesel from a residue oil hydrogenation unit and catalytic diesel from a catalytic cracking unit into a thermal polycondensation unit for thermal polycondensation reaction to obtain a thermal polycondensation product, and the heavy component of the thermal polycondensation product obtained by cutting is mixed with filtered catalytic cracking oil slurry, and the mixture is used to produce high-grade needle coke raw materials. The invention provides a method for moderately thermally polycondensing hydrogenated diesel and catalytic diesel to obtain low-sulfur condensed aromatic hydrocarbons, which not only solves the diesel outlet problem, but also provides a higher-quality needle coke raw material.

Description

Technical Field

[0001] The present invention relates to the field of residue raw material treatment, and particularly relates to a method for producing high-grade needle coke raw materials from residue raw materials. Background Art

[0002] Needle coke 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, good mechanical strength at low and high temperatures, and good comprehensive electrochemical performance. Needle coke is mainly used for ultra-high power graphite electrodes and anode materials of lithium-ion batteries. With the proposal of the strategic goals of "carbon peak" and "carbon neutrality", the country has continuously promoted the industrial structure adjustment and transformation and upgrading of the steel and automobile industries, vigorously promoted the application of energy-saving, low-carbon and green environmental protection technologies, promoted the rapid development of electric arc furnace steelmaking and new energy vehicles, and the demand for raw material needle coke has also increased rapidly.

[0003] According to the properties and formation mechanism of needle coke, raw materials with a high content of polycyclic aromatic hydrocarbons should be selected. Catalytic cracking slurry is a low-value-added product of a catalytic cracking unit, which has a high content of polycyclic aromatic hydrocarbons and is suitable as a raw material for producing needle coke. The sulfur and nitrogen impurity contents of the slurry produced by catalytic cracking units in China are relatively high. The presence of sulfur and nitrogen heteroatoms in the needle coke coking reaction will cause unnecessary cross-linking reactions, resulting in the loss of planarity of molecules and the formation of a cross-linked structure, thus destroying the flatness of the intermediate product and being unfavorable for the formation of a wide-area mesophase. Moreover, sulfur and nitrogen are released under the action of high temperature during the graphitization of needle coke and the use of electrodes, which will cause crystal swelling, not only affecting the performance of graphite electrodes, but also leading to the fracture of graphite electrodes, thus causing production accidents. Therefore, whether used as a raw material for graphite electrodes or anode materials of lithium batteries, there are clear requirements for the sulfur and nitrogen heteroatom contents of needle coke. The China Carbon Industry Association Standard (T / ZGTS 002—2019) stipulates that the sulfur content of super-grade needle coke ≯0.35%, and the nitrogen content ≯0.10%. Therefore, raw materials with low sulfur, low nitrogen and high aromatics are suitable for producing high-grade needle coke.

[0004] CN1872963A discloses a pretreatment method for producing needle coke raw materials. In this method, the raw material oil first removes heavy non-ideal components such as asphaltenes, resins and part of ash and light non-ideal components such as diesel fractions through filtration and vacuum distillation in sequence. Among them, the light non-ideal components are drawn out from the top of the vacuum tower and the first side stream of the vacuum tower, the heavy non-ideal components are drawn out from the bottom of the tower, and the remaining ideal components are drawn out from the middle of the tower and contacted with hydrogen and a hydrogenation catalyst. The hydrogenation reaction product stream is separated to obtain the raw material for producing needle coke.

[0005] CN103666556A discloses a method for preparing petroleum coke. It includes: (1) subjecting catalytic cracking slurry oil to vacuum distillation, where the sulfur content of the catalytic cracking slurry oil is 0.50 wt% to 2.5 wt%, the ash content is 0.01 wt% to 1 wt%, and the asphaltene content is 1 wt% to 20 wt%; (2) after mixing the fraction oil obtained in step (1) with hydrogen, successively contacting it with a hydrogenation protective agent and a hydrogenation refining agent; (3) inputting the hydrogenated liquid product obtained in step (2) into a delayed coking unit for thermal cracking reaction to obtain petroleum coke.

[0006] CN103013567A discloses a method for producing raw materials for needle coke from catalytic cracking slurry oil. This method sets up a hydrogenation protective reaction zone in front of the hydrogenation reaction zone. The catalytic cracking slurry oil first enters the protection zone to adsorb most of the catalytic cracking catalyst powder, and then is mixed with hydrogen and enters a heating furnace. After heating, it enters the hydrogenation reaction zone for hydrogenation treatment reaction. Through the hydrorefining of catalytic cracking slurry oil, most of the sulfur in the catalytic cracking slurry oil is removed to produce qualified raw materials for needle coke. Summary of the Invention

[0007] The present invention aims to solve the technical problem of how to effectively utilize residue oil raw materials to produce high-grade raw materials for needle coke in the largest quantity.

[0008] A method for producing high-grade raw materials for needle coke provided by the present invention includes:

[0009] (1) Hydrotreated diesel from a residue hydrotreating unit and catalytic diesel from a catalytic cracking unit enter a thermal polycondensation unit for thermal polycondensation reaction to obtain a thermal polycondensation product;

[0010] (2) Distilling and cutting the thermal polycondensation product into a heavy fraction and a light fraction, and returning the light fraction to the inlet of the thermal polycondensation unit;

[0011] (3) Mixing the heavy fraction obtained in step (2) with the filtered catalytic cracking slurry oil, and using this mixture as a raw material for producing high-grade needle coke to enter a delayed coking unit.

[0012] In an embodiment of the present invention, the distillation range of the hydrotreated diesel is 160 - 350 °C, by weight, the sulfur content is 0.001% - 0.050%, the nitrogen content is 0.001% - 0.050%, the distillation range of the catalytic diesel is 160 - 350 °C, by weight, the sulfur content is 0.0105 - 0.200%, the nitrogen content is 0.010% - 0.200%, and the mixing mass ratio of the hydrotreated diesel and the catalytic diesel is 1:1 - 1:4.

[0013] In the present invention, hydrotreated diesel and catalytic diesel are sent to a thermal polycondensation unit for thermal polycondensation reaction, aiming to reasonably utilize the aromatic components in diesel. Through thermal polycondensation to a certain extent of polycyclic aromatic hydrocarbons, they can become high-quality raw materials for needle coke. Moreover, since the sulfur content and nitrogen content in hydrotreated diesel and catalytic diesel are both lower than those in catalytic slurry oil, the heavy components obtained after their thermal polycondensation are also components with lower sulfur content and nitrogen content. Mixing them with catalytic slurry oil can effectively reduce the sulfur content and nitrogen content of the final mixture. Therefore, the present invention not only solves the problem of the outlet of diesel but also obtains high-quality raw materials for producing high-grade needle coke.

[0014] In one embodiment of the present invention, the thermal polycondensation unit in step (1) is a tubular reactor to precisely control the temperature and time of thermal polycondensation.

[0015] In one embodiment of the present invention, the temperature of the thermal polycondensation reaction in step (1) is 400°C to 480°C, and the reaction time is 0.1 h to 2 h. Preferably, the temperature of the thermal polycondensation reaction is 440°C to 470°C, and the reaction time is 0.2 h to 1 h.

[0016] In one embodiment of the present invention, the cut-off point between the light components and heavy components of the thermal polycondensation product in step (2) is 370°C to 470°C, preferably 420°C to 460°C.

[0017] In one embodiment of the present invention, the composition of the heavy components obtained in step (2) is polycyclic aromatic hydrocarbons with three to six rings.

[0018] In one embodiment of the present invention, the initial boiling point of the filtered catalytic cracking slurry oil is greater than or equal to 350°C. By weight, the sulfur content is not greater than 0.50%, the nitrogen content is not greater than 0.10%, and the content of three-ring and four-ring aromatic hydrocarbons is not less than 30%.

[0019] In one embodiment of the present invention, the mixing mass ratio of the filtered catalytic cracking slurry oil to the heavy components is 1:1 to 1:4.

[0020] In one embodiment of the present invention, the residue oil raw material and hydrogen enter a fixed-bed residue oil hydrotreating unit together, and successively pass through a hydrotreating protective agent, a hydrodemetallization agent, a hydrodesulfurization agent, and a hydrodenitrogenation agent. The obtained hydrotreated product oil is separated to obtain dry gas, hydrotreated gasoline, hydrotreated diesel, and hydrotreated residue oil. The obtained hydrotreated residue oil enters a catalytic cracking unit and undergoes a catalytic cracking reaction under the action of a catalytic cracking catalyst to obtain dry gas, catalytic gasoline, catalytic diesel, and catalytic slurry oil.

[0021] In one embodiment of the present invention, the process conditions for fixed-bed residue hydrotreating are as follows: the reaction temperature is between 300°C and 430°C, preferably between 350°C and 390°C; the reaction pressure is between 13.0 MPa and 19.0 MPa, preferably between 15.0 MPa and 18.0 MPa; the volumetric space velocity is between 0.10 h -1 ~0.50 h -1 preferably between 0.15 h -1 ~0.40 h -1 ; the hydrogen-to-oil volume ratio is between 500 and 1500, preferably between 800 and 1200.

[0022] The hydrotreating protective agent and hydrodemetallization agent filled in the fixed-bed residue hydrotreating reactor can be commercially available residue hydrotreating protective agent and hydrodemetallization agent. The purpose of filling the hydrodemetallization agent is to remove metal impurities in the raw material to protect the downstream hydrodesulfurization agent and hydrodenitrogenation agent.

[0023] The hydrodesulfurization agent can adopt a commercially available fixed-bed residue hydrodesulfurization catalyst. Preferably, the active metal of the hydrodesulfurization agent is cobalt-molybdenum, that is, the hydrodesulfurization agent is a cobalt-molybdenum type catalyst. The hydrodenitrogenation agent can adopt a commercially available fixed-bed residue hydrodenitrogenation catalyst. Preferably, the active metal of the hydrodenitrogenation agent is nickel-tungsten, that is, the hydrodenitrogenation agent is a nickel-tungsten type catalyst. In the present invention, the filling ratio of the hydrodesulfurization agent and the hydrodenitrogenation agent is comprehensively determined according to the sulfur content, nitrogen content in the raw material and the reaction conditions.

[0024] In one embodiment of the present invention, based on the overall fixed-bed residue hydrotreating catalyst, by volume, the filling ratio of the hydrotreating protective agent is between 1% and 10%, the filling ratio of the hydrodemetallization agent is between 5% and 50%, the filling ratio of the hydrodesulfurization agent is between 5% and 50%, and the filling ratio of the hydrodenitrogenation agent is between 5% and 50%.

[0025] In the present invention, there is no limitation on the catalytic cracking unit, and a catalytic cracking unit that produces more light olefins is preferred.

[0026] The characteristics of the present invention: moderately thermally condensing hydrotreated diesel and catalytic diesel to obtain low-sulfur polycyclic aromatic hydrocarbons, which not only solves the problem of diesel outlet, but also provides a higher-quality needle coke raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of one embodiment of the method for producing high-grade needle coke raw material provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below with reference to the drawings, but the present invention is not limited thereby.

[0029] Figure 1 It is a schematic diagram of one of the embodiments of the method for producing raw materials for high-grade needle coke provided by the present invention. As Figure 1 shown, the residue oil raw material from pipeline 1 and hydrogen enter the fixed-bed residue oil hydrogenation unit 2 together, and hydrogenation reaction is carried out under the action of hydrogenation catalyst to remove most of the impurities such as sulfur and nitrogen in the residue oil. The hydrogenated product oil enters the separation system 4 through pipeline 3. The separated gas and hydrogenated gasoline leave the unit through pipelines 5 and 6 respectively, and the hydrogenated diesel oil enters the thermal polycondensation unit 19 through pipeline 7. The hydrogenated residue oil enters the fluid catalytic cracking unit 9 through pipeline 8, and cracking reaction is carried out under the action of fluid catalytic cracking catalyst. The cracked product oil enters the separation system 11 through pipeline 10. The dry gas, liquefied gas and catalytic gasoline obtained by separation leave the unit through pipelines 12, 13 and 14 respectively, and the catalytic slurry oil enters the filtration unit 17 through pipeline 16. The catalytic diesel oil enters the thermal polycondensation unit 19 after being mixed with the hydrogenated diesel oil from pipeline 7 through pipeline 15 for thermal polycondensation reaction. The thermal polycondensation product is fractionated to obtain light and heavy components, and the light components return to the thermal polycondensation unit 19 through pipeline 20. After the heavy components are mixed with the catalytic slurry oil filtered by the filtration unit 17, they leave the unit through pipeline 18 and enter the delayed coking unit as raw materials for producing high-grade needle coke.

[0030] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereby.

[0031] The properties of the residue oil raw materials A and B used in the examples and comparative examples are shown in Table 1. The commercial brand numbers of the hydrogenation protective agent, hydrogenation demetallization agent, hydrogenation desulfurization agent and hydrogenation denitrogenation agent used in the fixed-bed residue oil hydrogenation unit are RG-30B, RDM-202, RMS-30 and RSN-1 respectively. The commercial brand number of the hydrogenation desulfurization and denitrogenation agent used in the comparative example is RCS-31, all of which are produced by Changling Catalyst Plant, Sinopec Catalyst Company. The main properties of the hydrogenation catalyst are shown in Table 2. The commercial brand number of the fluid catalytic cracking catalyst used is MLC500, which is produced by Sinopec Catalyst Changling Company.

[0032] Example 1

[0033] Residual oil feedstock A enters the residue hydrotreating unit together with hydrogen, and successively passes through the hydrotreating protective agent RG-30B, the hydrodemetallization agent RDM-202, the hydrodesulfurization agent RMS-30, and the hydrodenitrogenation catalyst RSN-1 to remove most of the sulfur and nitrogen heteroatoms in the residual oil. The hydrogenated product oil is separated to obtain dry gas, hydrogenated gasoline, hydrogenated diesel, and hydrogenated residue. The hydrogenated residue enters the fluid catalytic cracking unit and undergoes a fluid catalytic cracking reaction under the action of a fluid catalytic cracking catalyst to obtain dry gas, catalytic gasoline, catalytic diesel, and catalytic slurry. The hydrogenated diesel and catalytic diesel enter the thermal polycondensation unit for a thermal polycondensation reaction to obtain a thermal polycondensation product. The thermal polycondensation product is distilled and cut into a heavy fraction and a light fraction, and the light fraction is returned to the thermal polycondensation unit. The heavy fraction is mixed with the filtered catalytic slurry and enters the delayed coking unit as a raw material for producing high-grade needle coke.

[0034] The main operating conditions, main product properties, and yields of the residue hydrotreating unit and the fluid catalytic cracking unit are shown in Tables 3 and 4.

[0035] Example 2

[0036] Residual oil feedstock B enters the residue hydrotreating unit together with hydrogen, and successively passes through the hydrogen protective agent RG-30B, the hydrodemetallization agent RDM-202, the hydrodesulfurization agent RMS-30, and the hydrodenitrogenation catalyst RSN-1 to remove most of the sulfur and nitrogen heteroatoms in the residual oil. The hydrogenated product oil is separated to obtain dry gas, hydrogenated gasoline, hydrogenated diesel, and hydrogenated residue. The hydrogenated residue enters the fluid catalytic cracking unit and undergoes a fluid catalytic cracking reaction under the action of a fluid catalytic cracking catalyst to obtain dry gas, catalytic gasoline, catalytic diesel, and catalytic slurry. The hydrogenated diesel and catalytic diesel enter the thermal polycondensation unit for a thermal polycondensation reaction to obtain a thermal polycondensation product. The thermal polycondensation product is distilled and cut into a heavy fraction and a light fraction, and the light fraction is returned to the thermal polycondensation unit. The heavy fraction is mixed with the filtered catalytic slurry and enters the delayed coking unit as a raw material for producing high-grade needle coke.

[0037] The main operating conditions, main product properties, and yields of the residue hydrotreating unit and the fluid catalytic cracking unit are shown in Tables 3 and 4.

[0038] As can be seen from Table 4, the sulfur content of the high-grade needle coke raw materials obtained from Example 1 and Example 2 is both < 0.10 wt%, and the nitrogen content is both < 0.05 wt%, and they can be used as raw materials for producing high-grade needle coke. This raw material enters the delayed coking unit, and after coking treatment, the properties of the obtained needle coke are listed in Table 4, and the carbon industry association standard (T / ZGTS 002—2019) is listed in Table 6. It can be seen from Table 4 that the properties of the obtained needle coke meet the index requirements of super-grade coke.

[0039] The total yields of Example 1 and Example 2 are listed in Table 5. Among them, dry gas, liquefied gas, and gasoline refer to the sum of the related products of the residue hydrotreating unit and the fluid catalytic cracking unit, and the needle coke raw material refers to the mixture of the heavy components obtained from the thermal condensation unit and the filtered catalytic slurry.

[0040] Comparative Example 1

[0041] The residue feedstock A enters the residue hydrotreating unit together with hydrogen and passes successively through the hydrotreating protective agent RG-30B, the hydrodemetallization agent RDM-202, and the hydrodesulfurization and denitrification agent RCS-31 to remove most of the sulfur and nitrogen heteroatoms in the residue. The hydrogenated product oil is separated to obtain dry gas, hydrogenated gasoline, hydrogenated diesel, and hydrogenated residue. The hydrogenated residue enters the fluid catalytic cracking unit and undergoes a fluid catalytic cracking reaction under the action of a fluid catalytic cracking catalyst to obtain dry gas, catalytic gasoline, catalytic diesel, and catalytic slurry. The hydrogenated diesel and catalytic diesel enter the thermal condensation unit for a thermal condensation reaction to obtain a thermal condensation product. The thermal condensation product is distilled and cut into heavy components and light components, and the light components are returned to the thermal condensation unit. The heavy components are mixed with the filtered catalytic slurry and enter the delayed coking unit as a raw material for producing high-grade needle coke.

[0042] The main operating conditions, main product properties, and yields of the residue hydrotreating unit and the fluid catalytic cracking unit are shown in Tables 3 and 4, and the total yields are listed in Table 5.

[0043] The needle coke raw material obtained from Comparative Example 1 enters the delayed coking unit. After coking treatment, the properties of the obtained needle coke are listed in Table 4. It can be seen from Table 4 that the properties of the obtained needle coke meet the index requirements of Grade I coke.

[0044] Table 1

[0045] Feedstock oil number Residuum A Residuum B <![CDATA[Density (20 °C), kg / m 3 > 955 960 <![CDATA[Kinematic viscosity (100 °C), mm 2 / s]]> 32 40 Carbon residue, wt% 6.3 8.5 Nitrogen, wt% 0.15 0.23 Sulfur, wt% 1.7 2.0 <![CDATA[Asphaltene (C 7 insoluble matter)]]> 1.5 2.1 Metal (nickel + vanadium) content, ppm 20 43

[0046] Table 2

[0047]

[0048]

[0049] Table 3

[0050]

[0051]

[0052] Table 4

[0053]

[0054]

[0055] Table 5

[0056]

[0057]

[0058] Table 6

[0059]

Claims

1. A method for producing raw materials for super needle coke, comprising: (1) Hydrotreated diesel from a residue hydrotreating unit and catalytic diesel from a fluid catalytic cracking unit enter a thermal polycondensation unit for thermal polycondensation reaction to obtain a thermal polycondensation product. The thermal polycondensation unit is a tubular reactor, the thermal polycondensation reaction temperature is 400°C to 480°C, and the reaction time is 0.1 h to 2 h; (2) The thermal polycondensation product is distilled and cut into a heavy fraction and a light fraction. The light fraction is returned to the inlet of the thermal polycondensation unit, and the cutting point of the light and heavy fractions of the thermal polycondensation product is 370°C to 470°C; (3) The heavy fraction obtained in step (2) is mixed with filtered fluid catalytic cracking slurry oil, and the mixture enters a delayed coking unit as raw materials for producing super needle coke. The initial boiling point of the filtered fluid catalytic cracking slurry oil is greater than or equal to 350°C, and by weight, the sulfur content is not more than 0.50%, the nitrogen content is not more than 0.10%, and the content of three-ring and four-ring aromatic hydrocarbons is not less than 30%; The residue raw material and hydrogen enter a fixed-bed residue hydrotreating unit, and successively pass through a hydrotreating protective agent, a hydrodemetallization agent, a hydrodesulfurization agent, and a hydrodenitrogenation agent. The obtained hydrotreated product oil is separated to obtain dry gas, hydrotreated gasoline, hydrotreated diesel, and hydrotreated residue. The obtained hydrotreated residue enters a fluid catalytic cracking unit and undergoes a fluid catalytic cracking reaction under the action of a fluid catalytic cracking catalyst to obtain dry gas, catalytic gasoline, catalytic diesel, and catalytic slurry oil.

2. The method according to claim 1, characterized in that, in step (1), the thermal polycondensation reaction temperature is 440°C to 470°C, and the reaction time is 0.2 h to 1 h.

3. The method according to claim 1, characterized in that, in step (2), the cutting point of the light and heavy fractions of the thermal polycondensation product is 420°C to 460°C.

4. The method according to claim 1, characterized in that, the composition of the heavy fraction obtained in step (2) is polycyclic aromatic hydrocarbons with three to six rings.

5. The method according to claim 1, characterized in that, the mixing mass ratio of the filtered fluid catalytic cracking slurry oil and the heavy fraction is 1:1 to 1:

4.

6. The method according to claim 1, characterized in that, based on the overall residue hydrotreating catalyst, by volume, the loading ratio of the hydrotreating protective agent is between 1% and 10%, the loading ratio of the hydrodemetallization agent is between 5% and 50%, the loading ratio of the hydrodesulfurization agent is between 5% and 50%, and the loading ratio of the hydrodenitrogenation agent is between 5% and 50%.

7. The method according to claim 1 or 6, characterized in that, the active metal of the hydrodesulfurization agent is cobalt-molybdenum; the active metal of the hydrodenitrogenation agent is nickel-tungsten.

Images