Gradient separation and graded polycondensation process and system for oil slurry

Abstract

The invention provides an oil slurry gradient separation and fractional polycondensation process and system, and the process comprises the steps: cutting the oil slurry into four streams with different distillation ranges according to the order of final boiling points from low to high according to different hydrocarbon distribution conditions in the oil slurry, and enabling a heated second stream to enter a reactor to carry out a first-stage thermal polycondensation reaction; enabling the heated third stream to enter the reactor to be subjected to a second-stage thermal polycondensation reaction together with a reaction product of the first-stage thermal polycondensation reaction; enabling the heated first stream to enter the reactor in a gas form and pass through a reaction product of the second-stage thermal polycondensation reaction from bottom to top, discharging unreacted materials out of the reactor from the top, ending the reaction after the pressure in the reactor reaches normal pressure, and discharging the thermal polycondensation product out of the reactor from the bottom. According to the process, the thermal polycondensation product with more uniform product property and morphology structure can be obtained, the yield of the thermal polycondensation product is high, and the comprehensive utilization rate of the oil slurry can be improved.

Description

Technical Field

[0001] This invention relates to a gradient separation and graded polycondensation process and system for oil slurry, belonging to the field of oil slurry thermal polycondensation technology. Background Technology

[0002] The properties of the raw materials are crucial to the development of the carbonaceous mesophase. Aromatic hydrocarbons with different degrees of ring condensation exhibit different thermal polycondensation properties. Lighter raw materials have lower ring condensation and slower carbonaceous mesophase development under the same reaction conditions; heavier raw materials contain higher degrees of condensation and higher molecular weight compounds, resulting in a higher viscosity of the reaction system and faster formation of large-molecule aromatic compounds. Therefore, aromatic hydrocarbons with different ring condensation require different times to form optimally morphological mesophase microspheres, each possessing its own "reaction window." Mixed raw materials inevitably experience asynchronous reactions in thermal polycondensation, leading to difficulty in controlling the reaction process and poor product quality uniformity.

[0003] Mesophase molecules are formed by the condensation of fused-ring aromatic molecules, and high aromatic hydrocarbon content accelerates mesophase development. However, as an early product in mesophase development, rapid reaction shortens the residence time of mesophase spheres, leading to rapid coalescence. Under specific reaction conditions, the growth and coalescence of mesophase spheres are mainly controlled by the mass transfer capacity of the reaction system, i.e., by the viscosity of the reaction system. Excessively high viscosity hinders further sphere growth, while excessively low viscosity accelerates coalescence. During the mesophase development stage, the system viscosity has a significant impact on the microcrystalline morphology of the mesophase spheres and subsequent coke. Therefore, in addition to the content and structure of fused-ring aromatic hydrocarbons, the content of cycloalkanes is also important. For example, arylcycloalkanes play a role in hydrogen transfer during carbonization, increasing the reactivity of the raw materials and reducing the viscosity of the system.

[0004] The oil slurry fractions exhibit a wide distribution. The light fractions contain higher levels of saturated hydrocarbons and low-ring aromatics, while the heavy fractions have higher condensation rates, a greater tendency to coke, and are rich in sulfur-, nitrogen-, and oxygen-containing heterocyclic aromatics. The middle fractions mainly contain moderately ring-numbered condensed aromatics and some sulfur-containing heterocyclic aromatics, showing high reaction consistency. During the co-carbonization of the mixed feedstock, the light fraction exhibits low condensation polymerization reactivity, while the middle fraction shows high thermal condensation polymerization reactivity and good reaction consistency. The heavy fractions condense first to form coking precursors, which then drive the condensation of more light aromatics, ultimately resulting in disordered accumulation and a product dominated by poorly structured mosaic-type mesophase.

[0005] In existing technologies, to ensure the uniformity of polycondensation products, the oil slurry is typically distilled to separate the middle fraction as the effective component for thermal polycondensation. This process has two drawbacks: Firstly, the low viscosity of the light fraction effectively reduces the viscosity of the reaction system during thermal polycondensation, which is beneficial for the development of mesophase microspheres. However, in existing technologies, this light fraction is not fully utilized. Secondly, due to the continuity of the aromatic structure in the oil slurry, aromatics with similar ring numbers and heterocyclic aromatics exhibit good molecular miscibility and similar boiling points. The distillation process suffers from poor separation clarity, making it difficult to fully separate the effective aromatic components from the heavy fraction, resulting in low yields of the effective components and poor overall utilization of the oil slurry resources.

[0006] To further illustrate the existing technology, the applicant will continue to explain using the following existing technologies as examples.

[0007] CN113773870A discloses a method for preparing mesophase asphalt, which includes mixing medium-temperature coal tar with FCC slurry and then extracting with furfural to obtain a pure aromatic mixture; the aromatic mixture is then subjected to vacuum distillation to separate a light component at 350-450℃ and a heavy component at 450-530℃; the heavy component is reacted at 390-450℃ and 3-5 MPa for 2-5 hours to generate soft asphalt; the soft asphalt is mixed with the light component at 350-450℃ to obtain blended soft asphalt; the blended soft asphalt is polycondensed at 390-410℃ and 3-5 MPa for 3-10 hours, and the light component is removed from the reactants using vacuum to obtain mesophase asphalt. In this method, the heavy component undergoes the first reaction first, and the reaction product of the first reaction is mixed with the light component to complete the second reaction.

[0008] CN106544758A discloses a method for preparing high-modulus pitch-based carbon fiber, comprising: (1) using catalytic oil slurry as raw material; (2) performing high-pressure hydrogenation pretreatment, with a reaction pressure of 12-18 MPa, a reaction temperature of 420-450℃, and a reaction time of 1-3 h, to obtain a hydrogenated product; (3) obtaining a fraction of ≥400℃ from the hydrogenated product by vacuum distillation, which is carried out in an inert gas or nitrogen atmosphere, with a reaction pressure of 1-6 MPa, a reaction temperature of 460-500℃, and a reaction time of 6-8 h, to obtain a primary condensation product; (4) subsequently performing a nitrogen reaction at atmospheric pressure, with a nitrogen flow rate of 5-8 L / (s·kg), a reaction temperature of 450-500℃, and a reaction time of 4-6 h, to obtain high-quality mesophase pitch; (5) performing melt spinning on the obtained mesophase pitch to obtain high-modulus carbon fiber. In this method, a fraction of ≥400℃ is selected for a continuous two-stage reaction.

[0009] CN111363578A discloses a method for refining mesophase asphalt through hydrogenation and chain transfer modification. The method includes cutting precursor asphalt into light and heavy components; hydrogenating the light component and then copolymerizing it with the precursor asphalt under pressure to obtain pressure-modified asphalt, which is then cut into light, medium, and heavy fractions. The medium fraction is directly further thermally polycondensed to prepare mesophase asphalt; the light component is hydrogenated again and then repolymerized with the precursor asphalt in a mixed hydrogenation process to obtain pressure-modified asphalt; the hydrogenated modified asphalt is cut again, and the above steps are repeated to cyclically prepare mesophase asphalt. In this method, the light and heavy fractions react separately, the light component is used for modification after mixing with the raw material, and the medium fraction is used as a raw material for a one-step reaction to prepare mesophase asphalt.

[0010] Therefore, providing a novel process and system for gradient separation and graded polycondensation of oil slurry has become a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0011] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a gradient separation and staged polycondensation process and system for oil slurry. This invention controls the overall progress of thermal polycondensation of aromatics with different compositions and structures to be consistent by setting the feeding timing of different fractions with varying reactivity, thereby improving the uniformity of the properties of the polycondensation products and increasing the utilization rate of effective components in the oil slurry.

[0012] To achieve the above objectives, on the one hand, the present invention provides an oil slurry gradient separation and staged polycondensation process, wherein the oil slurry gradient separation and staged polycondensation process includes:

[0013] Step (1): According to the different distribution of hydrocarbons in the slurry, the slurry is cut into four streams with different boiling ranges in order of increasing final boiling point; wherein the final boiling points of the first stream, the second stream, and the third stream are 300-380℃, preferably 300-350℃, 400-450℃, and 500-530℃, respectively, and the rest are the fourth stream;

[0014] Step (2): The heated second stream enters the reactor to undergo the first stage of thermal polycondensation reaction;

[0015] Step (3): The heated third stream enters the reactor and undergoes a second-stage thermal polycondensation reaction together with the reaction products of the first-stage thermal polycondensation reaction;

[0016] Step (4): The heated first stream enters the reactor in gas form and passes through the reaction products of the second stage thermal polycondensation reaction from bottom to top. Unreacted materials exit the reactor from the top. The reaction ends when the pressure inside the reactor reaches atmospheric pressure. The thermal polycondensation products exit the reactor from the bottom.

[0017] In the process described above in this invention, the second stream is lighter than the third stream, and the reaction time required for it to reach the same degree of reaction is longer than that of the third stream. Therefore, it is first subjected to a first-stage thermal polycondensation reaction. After reaching a certain degree, the third stream and the reaction products of the first-stage thermal polycondensation reaction undergo a second-stage thermal polycondensation reaction together, finally reaching a synchronous state. Step (4) is the cooling and depressurization stage. In the environment of this stage, the first stream basically does not react. The addition of the first stream reduces the viscosity of the original reaction system. Furthermore, because the fraction of the first stream is light and has a low density, it vaporizes under the reaction conditions and passes through the reaction products of the second-stage thermal polycondensation reaction from the bottom of the reactor upwards. This can make the microcrystalline structure of the intermediate phase of the product uniformly oriented, increasing the more ideal fiber structure.

[0018] In one specific embodiment of the process described above, when the yield of the residual fraction with an initial boiling point of 500-530℃ is ≤10wt%, the residual fraction is incorporated into the third stream, i.e., the slurry is split into three streams with different boiling ranges. When the yield of the residual fraction with an initial boiling point of 500-530℃ is >10wt%, four streams with different boiling ranges are separated as shown above, wherein the fourth stream, i.e., the bottom stream, can be used for other purposes as needed.

[0019] In a specific embodiment of the process described above in this invention, when the yield of the residual distillate with an initial boiling point of 450-500℃ is ≤10wt%, the residual distillate is incorporated into the second stream, that is, the slurry is split into two streams with different distillation ranges. In this case, the process includes:

[0020] The heated second stream enters the reactor to undergo the first stage of thermal polycondensation reaction;

[0021] The heated first stream enters the reactor in gaseous form and passes through the reaction products of the first stage of thermal polycondensation from bottom to top. Unreacted materials exit the reactor from the top. The reaction ends when the pressure inside the reactor reaches atmospheric pressure, and the thermal polycondensation products exit the reactor from the bottom.

[0022] As a specific embodiment of the process described above in this invention, the temperature of the second stream entering the reactor is 420-480°C, and the reaction is carried out for 3-6 hours under the conditions of a reaction temperature of 420-480°C, preferably 440-460°C, and a reaction pressure of 0.1-3 MPa, preferably 0.5-2.5 MPa.

[0023] In one specific embodiment of the process described above in this invention, the temperature of the third stream entering the reactor is 380-460°C. Under the conditions of a reaction temperature of 380-460°C, preferably 420-440°C, and a reaction pressure of 0.1-3 MPa, preferably 0.5-2.5 MPa, the reaction product of the first stage thermal polycondensation reaction reacts together for 2-20 hours, preferably 3-6 hours.

[0024] When the slurry is divided into four streams with different distillation ranges, in step (3) of the process described above, the timing of adding the third stream can be determined based on the degree of reaction or reaction time of the first-stage thermal polycondensation reaction. For example, the heated third stream can be introduced into the reactor 3-6 hours after the first-stage thermal polycondensation reaction to undergo the second-stage thermal polycondensation reaction together with the reaction products of the first-stage thermal polycondensation reaction; alternatively, the heated third stream can be introduced into the reactor to undergo the second-stage thermal polycondensation reaction together with the reaction products of the first-stage thermal polycondensation reaction after characterization analysis of the products of the first-stage thermal polycondensation reaction and before the mesophase microspheres begin to grow but have not fully developed to the point of fusion.

[0025] In step (4) of the process described above in this invention, the timing of adding the first stream can be determined based on the degree of reaction or reaction time of the second-stage thermal polycondensation reaction. For example, the first stream after heating can be introduced into the reactor in gaseous form after the second-stage thermal polycondensation reaction has been carried out for 2-20 hours, preferably 3-6 hours; alternatively, the first stream after heating can be introduced into the reactor in gaseous form before the products of the second-stage thermal polycondensation reaction are characterized and analyzed and it is found that the mesophase microspheres are fully developed, fused, and have not solidified to form quinoline insolubles.

[0026] As a specific embodiment of the process described above in this invention, when the oil slurry is cut into two streams with different distillation ranges, the temperature of the second stream entering the reactor is 420-480°C, and it reacts for 5-26 hours under the conditions of a reaction temperature of 420-480°C and a reaction pressure of 0.1-3MPa.

[0027] When the slurry is split into two streams with different distillation ranges, the timing of adding the first stream in the process described above can be determined based on the degree of reaction or reaction time of the first-stage thermal polycondensation reaction. For example, the heated first stream can be introduced into the reactor in gaseous form 5-26 hours after the first-stage thermal polycondensation reaction has proceeded; alternatively, the heated first stream can be introduced into the reactor in gaseous form before the products of the first-stage thermal polycondensation reaction have been characterized and analyzed, and before the mesophase microspheres have fully developed, merged, and solidified to form quinoline insolubles.

[0028] In one specific embodiment of the process described above in this invention, the temperature of the first stream entering the reactor is 380-460°C.

[0029] In one specific embodiment of the process described above in this invention, after the first stream of feed is completed, the system begins to depressurize at a rate of 0.05-0.1 atm / min. During the depressurization process, unreacted materials in the system exit the reactor from the top, while the residual materials in the reactor, namely the thermopolymerization product / thermopolymerization product mesophase pitch, are discharged from the bottom of the reactor.

[0030] The location where the second stream enters the reactor depends on the feedstock's distillation range. In one specific embodiment of the process described above, the height of the second stream entering the reactor from the bottom of the reactor is not less than the height of the reactor occupied by the first-stage thermal polycondensation reaction zone.

[0031] The location where the third stream enters the reactor depends on the feedstock's distillation range. In one specific embodiment of the process described above, the height of the third stream entering the reactor from the bottom of the reactor is not less than the height of the reactor occupied by the second-stage thermal polycondensation reaction zone.

[0032] In one specific embodiment of the process described above in this invention, when the slurry is cut into three or more streams with different boiling ranges in order of increasing final boiling point, the heated second stream enters the reactor from the lower middle or upper middle part of the reactor, and the heated third stream enters the reactor from the upper middle or lower middle part of the reactor; when the slurry is cut into two streams with different boiling ranges in order of increasing final boiling point, the heated second stream enters the reactor from the lower middle part of the reactor.

[0033] For the first stream, regardless of whether the slurry is cut into several streams with different distillation ranges, it is used to purge the material in the reactor. Therefore, the closer the first stream enters the reactor (i.e., the first inlet position) is to the bottom of the reactor, the better. The best position is the bottom outlet of the reactor. However, in order to distinguish the first inlet from the discharge port of the thermal polycondensation product, in some embodiments of the present invention, the first stream can be placed at the junction of the reactor side wall and the bottom head of the reactor tower.

[0034] In a specific embodiment of the process described above in this invention, when the slurry is cut into three or more streams with different distillation ranges in order of increasing final boiling point, the feed rate of the first stream is 1 / 10 to 1 / 2 of the feed rate of the third stream; when the slurry is cut into two streams with different distillation ranges in order of increasing final boiling point, the feed rate of the first stream is 1 / 10 to 1 / 2 of the feed rate of the second stream.

[0035] As a specific embodiment of the process described above in this invention, the process further includes a reflux operation at the top of the reactor, with a reflux temperature of 350-450°C, preferably 380-440°C. By performing this reflux operation at the top of the reactor, some heavier components obtained after the reaction, such as thermal polycondensation products, can be prevented from exiting the reactor from the top of the tower.

[0036] As a specific embodiment of the process described above in this invention, the process further includes mixing unreacted material coming out from the top of the reactor with oil slurry and then cutting it.

[0037] In step (4) of the process described above in this invention, the unreacted materials include the first stream that did not participate in the reaction and other unreacted materials, but the composition and content of the other unreacted materials are uncertain and are related to the composition of the raw materials and the reaction conditions.

[0038] As a specific embodiment of the process described above in this invention, the oil slurry includes one or a combination of several of the following: clarified oil slurry after desolidification, ethylene tar, coking wax oil, catalytic circulating oil, and furfural extract oil.

[0039] On the other hand, the present invention also provides an oil slurry gradient separation and graded polycondensation system, wherein the oil slurry gradient separation and graded polycondensation system includes: a distillation device, a heating device, and a reactor. The distillation device is provided with a first stream outlet, a second stream outlet, a third stream outlet, and a fourth stream outlet from top to bottom. The reactor is provided with a third inlet, a second inlet, and a first inlet from top to bottom. The first stream outlet, the second stream outlet, and the third stream outlet are respectively connected to the first inlet, the second inlet, and the third inlet of the reactor via pipelines through the heating device, or the first stream outlet, the second stream outlet, and the third stream outlet are respectively connected to the first inlet, the third inlet, and the second inlet of the reactor via pipelines through the heating device.

[0040] As a specific embodiment of the system described above in this invention, the distillation apparatus is provided with a first stream outlet, a second stream outlet and a third stream outlet from top to bottom.

[0041] In a specific embodiment of the system described above in this invention, the distillation apparatus is provided with a first stream outlet and a second stream outlet at its top and bottom, respectively, and the reactor is provided with a second inlet and a first inlet from top to bottom, respectively. The first stream outlet and the second stream outlet are respectively connected to the first inlet and the second inlet of the reactor via pipelines through the heating device.

[0042] In one specific embodiment of the system described above in this invention, a reflux device is further provided at the top of the reactor.

[0043] In one specific embodiment of the system described above in this invention, the top outlet of the reactor is connected to the raw material inlet of the distillation apparatus via a pipeline.

[0044] In the system described above in this invention, one or more heating devices may be provided. When only one heating device is provided, the heating device provides a gradient temperature increase from top to bottom. Each stream is heated by an independent furnace tube, and each stream reaches the temperature required to enter the reactor by exiting the heating device from a different location. In some embodiments of this invention, the heating device may be, for example, a heating furnace.

[0045] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0046] The oil slurry gradient separation and staged polycondensation process provided by this invention first uses distillation to cut the oil slurry into narrow fractions with different hydrocarbon distribution characteristics. Then, utilizing the different "reaction windows" of compounds with different compositions, the aromatic-rich components, namely the second and third streams, undergo staged thermal polycondensation to obtain an intermediate phase with uniform optical structure size. Finally, the light fraction with low aromatic content, namely the first stream, is slowly introduced into the reactor in the middle and late stages of the reaction, and the escape rate of unreacted materials is controlled. On the one hand, this can reduce the viscosity of the reaction system and promote the further growth of the mesophase microspheres. On the other hand, as the reaction proceeds, the fully developed mesophase microspheres merge in a certain orientation, promoting the formation of a broad-area mesophase structure.

[0047] In summary, the beneficial technical effects of the oil slurry gradient separation and staged polycondensation process provided by this invention are as follows: First, it can obtain thermal polycondensation products with more uniform product properties and morphology; second, it enables precise reaction of aromatics with different structures, resulting in a high yield of thermal polycondensation products; and third, compared with existing technologies that "cut off the head and tail" and take the middle fraction for reaction, except for particularly heavy components, other components participate in the thermal polycondensation reaction to the greatest extent, thereby improving the comprehensive utilization rate of oil slurry. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the oil slurry gradient separation and graded polycondensation system provided in Embodiment 1 of the present invention.

[0050] Figure 2This is a schematic diagram of the oil slurry gradient separation and graded polycondensation system provided in Embodiment 2 of the present invention.

[0051] Figure 3 This is a schematic diagram of the oil slurry gradient separation and graded polycondensation system provided in Embodiment 3 of the present invention.

[0052] Figure 4 The image shown is a polarized light microscope image of the thermal polycondensation product provided in Embodiment 1-1 of the present invention.

[0053] Figure 5 The images shown are polarized light microscope images of the thermal condensation products provided in Examples 1-2 of this invention.

[0054] Figure 6 The images shown are polarized light microscope images of the thermal condensation products provided in Examples 1-3 of this invention.

[0055] Figure 7 This is a polarized light microscope image of the thermal condensation product provided in Embodiment 2-1 of the present invention.

[0056] Figure 8 The image shown is a polarized light microscope image of the thermal polycondensation product provided in Embodiment 2-2 of the present invention.

[0057] Figure 9 This is a polarized light microscope image of the thermal polycondensation product provided in Example 3-1 of the present invention.

[0058] Figure 10 A polarized microscope image of the thermal condensation product provided for Comparative Example 1.

[0059] Figure 11 A polarized microscope image of the thermal condensation product provided for Comparative Example 2.

[0060] Figure 12 A polarized microscope image of the thermopolymerization product provided for Comparative Example 3.

[0061] Explanation of main icon numbers:

[0062] 1. Distillation column;

[0063] 2. Reactor. Detailed Implementation

[0064] It should be noted that the term "comprising" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0065] The "range" disclosed in this invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this way are composable, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is also expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if the listed minimum range values ​​are 1 and 2, and the listed maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0066] In this invention, unless otherwise specified, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this invention, and "0-5" is simply a shortened representation of these numerical combinations.

[0067] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in this invention can be combined with each other to form new technical solutions.

[0068] In this invention, unless otherwise specified, all technical features and preferred features mentioned in this invention can be combined with each other to form new technical solutions.

[0069] In this invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0070] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying tables, drawings, and embodiments. The embodiments described below are some, but not all, embodiments of this invention, and are only used to illustrate the invention, and should not be considered as limiting the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0071] Example 1

[0072] This embodiment provides an oil slurry gradient separation and staged polycondensation system, the structural schematic of which is shown below. Figure 1 As shown, from Figure 1 As can be seen from the figure, the system includes a distillation column 1, a heating furnace (not shown in the figure) and a reactor 2. The distillation column 1 is provided with a raw material inlet and a first stream outlet, a second stream outlet, a third stream outlet and a fourth stream outlet from top to bottom. The reactor is provided with a third inlet, a second inlet and a first inlet, a top outlet and a bottom outlet from top to bottom. The distance between the third inlet and the top of the reactor is 1 / 4 of the reactor height. The second inlet is located in the middle of the reactor and the first inlet is located at the junction of the side wall of the reactor and the bottom head of the reactor column.

[0073] The first, second, and third stream outlets are respectively connected to the first, second, and third inlets of the reactor via pipelines through the heating furnace.

[0074] In this embodiment, a heating furnace is set up. The heating furnace heats the material gradually from top to bottom. The three streams of material are heated by independent furnace tubes and exit the heating furnace from different positions to meet the reactor inlet temperature requirements.

[0075] In this embodiment, a reflux device is provided at the top of the reactor 2, and the top outlet of the reactor 1 is also connected to the raw material inlet of the distillation column 1 through a pipeline.

[0076] Example 2

[0077] This embodiment provides an oil slurry gradient separation and staged polycondensation system, the structural schematic of which is shown below. Figure 2 As shown, from Figure 2As can be seen from the figure, the system includes a distillation column 1, a heating furnace (not shown in the figure) and a reactor 2. The distillation column 1 is provided with a raw material inlet and a first stream outlet, a second stream outlet and a third stream outlet from top to bottom. The reactor is provided with a third inlet, a second inlet and a first inlet, a top outlet and a bottom outlet from top to bottom. The distance between the third inlet and the top of the reactor is 1 / 4 of the reactor height. The second inlet is located in the middle of the reactor and the first inlet is located at the junction of the side wall of the reactor and the bottom head of the reactor column.

[0078] The first, second, and third stream outlets are respectively connected to the first, second, and third inlets of the reactor via pipelines through the heating furnace.

[0079] In this embodiment, a heating furnace is set up. The heating furnace heats the material gradually from top to bottom. The three streams of material are heated by independent furnace tubes and exit the heating furnace from different positions to meet the reactor inlet temperature requirements.

[0080] In this embodiment, a reflux device is provided at the top of the reactor 2, and the top outlet of the reactor 1 is also connected to the raw material inlet of the distillation column 1 through a pipeline.

[0081] Example 3

[0082] This embodiment provides an oil slurry gradient separation and staged polycondensation system, the structural schematic of which is shown below. Figure 3 As shown, from Figure 3 As can be seen from the figure, the system includes a distillation column 1, a heating furnace (not shown in the figure) and a reactor 2. The distillation column 1 is provided with a raw material inlet and a first stream outlet and a second stream outlet located at the top and bottom of the distillation column 1, respectively. The reactor is provided with a second inlet, a first inlet, a top outlet and a bottom outlet from top to bottom. The second inlet is located in the middle of the reactor and the first inlet is located at the junction of the side wall of the reactor and the bottom end cap of the reactor column.

[0083] The first and second stream outlets are respectively connected to the first and second inlets of the reactor via pipelines through the heating furnace.

[0084] In this embodiment, a heating furnace is set up. The heating furnace heats the material gradually from top to bottom. The two streams of material are heated by independent furnace tubes and exit the heating furnace from different positions to meet the reactor inlet temperature requirements.

[0085] In this embodiment, a reflux device is provided at the top of the reactor 2, and the top outlet of the reactor 1 is also connected to the raw material inlet of the distillation column 1 through a pipeline.

[0086] Example 4

[0087] This embodiment provides an oil slurry gradient separation and staged polycondensation system, which differs from Embodiment 1 only in that:

[0088] The distance between the third inlet and the top of the reactor is 1 / 10 of the reactor height. The first, second, and third stream outlets are respectively connected to the first, third, and second inlets of the reactor via pipelines through the heating furnace.

[0089] Example 1-1

[0090] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 1. The process includes the following steps:

[0091] Step (1): Using a domestic ethylene tar as raw material, its distillation range data is shown in Table 1. The ethylene tar is divided into a first stream, a second stream, a third stream, and a fourth stream by a distillation column. The final boiling point of the first stream is 320℃, the final boiling point of the second stream is 450℃, the final boiling point of the third stream is 530℃, and the remainder is the fourth stream, which is discharged from the system for other uses.

[0092] Table 1 Ethylene tar distillation range data

[0093] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 202 203 228 270 321 373 433 490 544 610

[0094] Step (2): After the second stream is heated in the heating furnace, it enters the reactor from the middle, i.e. the second inlet, to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 450℃. Under the conditions of temperature of 450℃ and pressure of 2.0MPa, the reaction lasts for 4 hours.

[0095] Step (3): After being heated in the furnace, the third stream enters the reactor from 1 / 4 of the height from the top, i.e., the third inlet, and undergoes the second stage of thermal polycondensation reaction together with the reaction products of the first stage thermal polycondensation reaction. The inlet temperature of the third stream is 430℃. Under the conditions of 430℃ and 2.0MPa, it reacts with the reaction products of the first stage thermal polycondensation reaction for 4 hours.

[0096] Step (4): After the first stream is heated in the furnace, it enters the reactor through the first inlet. The temperature of the reactor is 420℃. After the feeding is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0097] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0098] Examples 1-2

[0099] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 4. The process includes the following steps:

[0100] Step (1): Using a certain oil slurry (denoted as the first oil slurry) as raw material, its distillation range data is shown in Table 2. The first oil slurry is split into a first stream, a second stream, a third stream, and a fourth stream by a distillation column. The final boiling point of the first stream is 380℃, the final boiling point of the second stream is 445℃, the final boiling point of the third stream is 530℃, and the remainder is the fourth stream, which is discharged from the system for other uses.

[0101] Table 2. Distillation range data for the first oil slurry.

[0102] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 327 373 405 425 445 464 483 505 532 577

[0103] Step (2): After being heated in the furnace, the second stream enters the reactor from the third inlet at a height of 1 / 10 from the top of the reactor to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 420℃. Under the conditions of temperature of 420℃ and pressure of 3.0MPa, the reaction lasts for 6 hours.

[0104] Step (3): After being heated in the furnace, the third stream enters the reactor from the middle of the reactor, i.e. the second inlet, and undergoes the second stage of thermal polycondensation reaction together with the reaction products of the first stage thermal polycondensation reaction. The inlet temperature of the third stream is 380℃. Under the conditions of temperature of 380℃ and pressure of 3.0MPa, it reacts with the reaction products of the first stage thermal polycondensation reaction for 20h.

[0105] Step (4): After the first stream is heated in the furnace, it enters the reactor through the first inlet. The temperature of the reactor is 460℃. After the feeding is completed, the system begins to depressurize at a rate of 0.1 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0106] A reflux operation is performed at the top of the reactor at a reflux temperature of 420°C.

[0107] Examples 1-3

[0108] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 4. The process includes the following steps:

[0109] Step (1): Using a certain oil slurry (denoted as the second oil slurry) as raw material, its distillation range data is shown in Table 3. The second oil slurry is split into a first stream, a second stream, a third stream, and a fourth stream by a distillation column. The final boiling point of the first stream is 370℃, the final boiling point of the second stream is 420℃, the final boiling point of the third stream is 500℃, and the remainder is the fourth stream, which is discharged from the system for other uses.

[0110] Table 3. Distillation range data for the second oil slurry.

[0111] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 347 370 388 402 413 426 441 459 483 536

[0112] Step (2): After being heated in the furnace, the second stream enters the reactor from the third inlet at a height of 1 / 10 from the top of the reactor to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 480℃. Under the conditions of temperature of 480℃ and pressure of 0.1MPa, the reaction lasts for 3 hours.

[0113] Step (3): After being heated in the furnace, the third stream enters the reactor from the middle of the reactor, i.e. the second inlet, and undergoes the second stage of thermal polycondensation reaction together with the reaction products of the first stage thermal polycondensation reaction. The inlet temperature of the third stream is 380℃. Under the conditions of temperature of 380℃ and pressure of 0.1MPa, it reacts with the reaction products of the first stage thermal polycondensation reaction for 10h.

[0114] Step (4): After the first stream is heated in the heating furnace, it enters the reactor through the first inlet. The temperature of the reactor is 380℃. After the feeding is completed, the system begins to depressurize at a rate of 0.05 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0115] A reflux operation is performed at the top of the reactor, with a reflux temperature of 400°C.

[0116] Example 2-1

[0117] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 2. The process includes the following steps:

[0118] Step (1): Using a certain refinery slurry (referred to as the third slurry) as raw material, its distillation range data is shown in Table 4. The third slurry is cut into the first stream, the second stream and the third stream by a distillation column. The final boiling point of the first stream is 340℃, the final boiling point of the second stream is 450℃, and the rest are the third stream.

[0119] Table 4. Distillation range data for the third oil slurry

[0120] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 331 342 357 371 385 399 413 430 454 493

[0121] Step (2): After the second stream is heated in the heating furnace, it enters the reactor from the middle, i.e. the second inlet, to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 460℃. Under the conditions of temperature of 460℃ and pressure of 2.4MPa, the reaction lasts for 5 hours.

[0122] Step (3): After being heated in the heating furnace, the third stream enters the reactor from 1 / 4 of the height from the top, i.e., the third inlet, and undergoes the second stage of thermal polycondensation reaction together with the reaction products of the first stage thermal polycondensation reaction. The inlet temperature of the third stream is 440℃. Under the conditions of 440℃ and 2.4MPa, it reacts with the reaction products of the first stage thermal polycondensation reaction for 5 hours.

[0123] Step (3): After the first stream is heated in the furnace, it enters the reactor through the first inlet. The temperature of the reactor is 420℃. After the feeding is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0124] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0125] Example 2-2

[0126] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 2. The process includes the following steps:

[0127] Step (1): Using oil slurry (referred to as fourth oil slurry) from a certain refinery as raw material, its distillation range data is shown in Table 5. The fourth oil slurry is cut into first stream, second stream and third stream by a distillation column. The final boiling point of the first stream is 370℃, the final boiling point of the second stream is 450℃, and the rest are the third stream.

[0128] Table 5. Distillation range data for the fourth oil slurry.

[0129] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 336 374 398 413 425 439 455 474 499 550

[0130] Step (2): After the second stream is heated in the heating furnace, it enters the reactor from the middle, i.e. the second inlet, to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 460℃. Under the conditions of temperature of 460℃ and pressure of 2.0MPa, the reaction is carried out for 5 hours.

[0131] Step (3): After being heated in the heating furnace, the third stream enters the reactor from 1 / 4 of the height from the top, i.e., the third inlet, and undergoes a second-stage thermal polycondensation reaction with the reaction products of the first-stage thermal polycondensation reaction. The inlet temperature of the third stream is 430℃. Under the conditions of 430℃ and 2.0MPa, it reacts with the reaction products of the first-stage thermal polycondensation reaction for 4 hours.

[0132] Step (4): After the first stream is heated in the furnace, it enters the reactor through the first inlet. The temperature of the reactor is 420℃. After the feeding is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0133] A reflux operation is performed at the top of the reactor at a reflux temperature of 420°C.

[0134] Example 3-1

[0135] This embodiment provides an oil slurry gradient separation and graded polycondensation process, which is implemented using the oil slurry gradient separation and graded polycondensation system provided in Embodiment 3. The process includes the following steps:

[0136] Step (1): Using catalytic cycle oil as raw material, its distillation range data is shown in Table 6. The catalytic cycle oil is split into a first stream and a second stream 2 by a distillation column. The final boiling point of the first stream is 350℃, and the rest is the second stream.

[0137] Table 6 Catalytic cycle oil distillation range data

[0138] Yield, wt% 5 10 20 30 40 50 60 70 80 90 Boiling point, °C 309 332 353 366 376 386 395 405 417 433

[0139] Step (2): After being heated in the furnace, the second stream enters the reactor from the middle, i.e. the second inlet, to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the second stream is 460°C. Under the conditions of 460°C and 2.4MPa, the reaction lasts for 10 hours.

[0140] Step (3): After the first stream is heated in the heating furnace, it enters the reactor through the first inlet. The temperature of the reactor is 440℃. After the feeding is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0141] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0142] Comparative Example 1

[0143] This comparative example uses the fourth slurry from Example 2-2 as raw material. After being heated in a heating furnace, the fourth slurry enters the reactor from the junction of the side wall of the reactor and the bottom head of the reactor tower. Its temperature at the reactor entrance is 460°C. The reaction is carried out at a temperature of 460°C and a pressure of 2.4 MPa for 10 hours. After the reaction is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, unreacted materials in the system exit the reactor from the top. The reaction ends when the pressure inside the reactor reaches atmospheric pressure. The residual materials in the reactor are discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0144] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0145] Comparative Example 2

[0146] This comparative example uses the fourth oil slurry from Example 2-2 as raw material to provide an oil slurry gradient separation and polycondensation process, including:

[0147] Step (1): The fourth oil slurry is cut into the first stream, the second stream and the third stream by the distillation tower. The final boiling point of the first stream is 370℃, the final boiling point of the second stream is 450℃, and the rest are the third stream.

[0148] Step (2): After the second stream is heated in the heating furnace, it enters the reactor from the middle, i.e. the second inlet, to undergo a thermal polycondensation reaction. The inlet temperature of the second stream is 460℃, and the reaction is carried out for 10 hours under the conditions of 460℃ and 2.0MPa.

[0149] Step (3): After the reaction is completed, the reaction system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits from the top of the reactor and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0150] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0151] Comparative Example 3

[0152] This comparative example uses the third oil slurry used in Example 2-1 as raw material to provide an oil slurry gradient separation and graded polycondensation process, which includes the following steps:

[0153] Step (1): The third oil slurry (distillation range data as shown in Table 4) is cut into the first stream, the second stream and the third stream by the distillation column. The final boiling point of the first stream is 340℃, the final boiling point of the second stream is 450℃, and the rest are the third stream.

[0154] Step (2): After the third stream is heated in the heating furnace, it enters the reactor from the middle, i.e. the second inlet, to carry out the first stage of thermal polycondensation reaction. The inlet temperature of the third stream is 460℃. Under the conditions of temperature of 460℃ and pressure of 2.4MPa, the reaction lasts for 5 hours.

[0155] Step (3): After being heated in the furnace, the second stream enters the reactor through the third inlet located at a distance of 1 / 4 of the reactor height from the top of the reactor and undergoes a second-stage thermal polycondensation reaction together with the reaction products of the first-stage thermal polycondensation reaction. The inlet temperature of the second stream is 440℃. Under the conditions of 440℃ and 2.4MPa, it reacts with the reaction products of the first-stage thermal polycondensation reaction for 5 hours.

[0156] Step (3): After the first stream is heated in the furnace, it enters the reactor through the first inlet. The temperature of the reactor is 420℃. After the feeding is completed, the system begins to depressurize at a rate of 0.08 atm / min. During the depressurization process, the unreacted material in the system exits the reactor from the top and mixes with the raw material into the distillation tower. After the pressure in the reactor reaches atmospheric pressure, the reaction ends. The residual material in the reactor is discharged from the bottom of the reactor to obtain the thermal polycondensation product.

[0157] A reflux operation is performed at the top of the reactor, with a reflux temperature of 380°C.

[0158] Test Example 1

[0159] In this test example, the thermopolymerization products provided in Examples 1-1 to 1-3, Examples 2-1 to 2-2, Example 3-1, and Comparative Examples 1 to 3 were analyzed by polarized light microscopy. The obtained polarized light micrographs are shown below. Figures 4-12 As shown.

[0160] from Figures 4-9 As can be seen from the mesophase microcrystalline morphology shown, all of the present invention, including Examples 1-1 to 1-3, Examples 2-1 to 2-2, and Example 3-1, have obtained mesophase pitch with a wide-area streamlined structure.

[0161] In Comparative Example 1, the fourth oil slurry whole fraction was used as raw material to obtain the thermal polycondensation product through thermal polycondensation. Figure 10 As shown in the mesophase microcrystalline morphology, the technical solution provided in Comparative Example 1 yielded mesophase pitch with both wide-area and mosaic structures. This is because molecules with different reactivity coexist in the raw material slurry and react under the same conditions. Polycyclic aromatic hydrocarbon molecules have higher reactivity and react faster, leading to a rapid increase in the viscosity of the reaction system. The mesophase microspheres do not have time to grow before coalescing. Furthermore, no light components enter the system in the later stages of the reaction, so they cannot play a gas-stretching role, resulting in the formation of some small plate-like optical microstructures.

[0162] In Comparative Example 2, the fourth oil slurry middle fraction, i.e., the second stream, was used to obtain the thermopolymerization product through thermopolymerization. Figure 11 As can be seen from the mesophase microcrystalline morphology shown, the technical solution provided in Comparative Example 2 also yielded mesophase pitch with a wide-area structure. However, since no light components entered the system in the later stage of the reaction, they could not play a gas flow stretching role, resulting in a slightly poor streamline structure and the formation of a large area of ​​wide-area structure.

[0163] Comparative Example 3 used the third slurry used in Example 2-1 as raw material, and subjected it to gradient separation and graded polycondensation. The cutting and depressurization schemes were the same as in Example 2-1, but the reaction order of the streams (i.e., the second and third streams) was different. Figure 12 As shown in the mesophase microcrystalline morphology, the technical solution provided in Comparative Example 3 yielded mesophase pitch with a small-plate structure. This is because: the polycyclic aromatic hydrocarbons in the third stream are highly reactive and react quickly. After reacting at 460℃ for 5 hours, the mesophase microspheres have grown sufficiently, resulting in a high viscosity of the reaction system. Subsequently, the second stream, which is lighter and less reactive, is introduced. The molecular reactions in the two streams are completely different, and the two streams react independently, thus failing to form a large-plate, wide-area structure.

[0164] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A gradient separation and staged polycondensation process for oil slurry, characterized in that, The oil slurry gradient separation and staged polycondensation process includes: Step (1): According to the different distribution of hydrocarbons in the slurry, the slurry is cut into four streams with different boiling ranges in order of increasing final boiling point; the final boiling points of the first stream, the second stream, and the third stream are 300-380℃, 400-450℃, and 500-530℃, respectively, and the rest are the fourth stream; Step (2): The heated second stream enters the reactor to undergo the first stage of thermal polycondensation reaction; Step (3): The heated third stream enters the reactor and undergoes a second-stage thermal polycondensation reaction together with the reaction products of the first-stage thermal polycondensation reaction; Step (4): The heated first stream enters the reactor in gas form and passes through the reaction products of the second stage thermal polycondensation reaction from bottom to top. Unreacted materials exit the reactor from the top. The reaction ends when the pressure inside the reactor reaches atmospheric pressure. The thermal polycondensation products exit the reactor from the bottom.

2. The process according to claim 1, characterized in that, When the yield of the residual fraction with an initial boiling point of 500-530℃ is ≤10wt%, the residual fraction is incorporated into the third stream, that is, the oil slurry is split into three streams with different boiling ranges.

3. The process according to claim 1, characterized in that, When the yield of the residual fraction with an initial boiling point of 450-500℃ is ≤10wt%, the residual fraction is incorporated into the second stream, that is, the slurry is split into two streams with different boiling ranges. The process then includes: The heated second stream enters the reactor to undergo the first stage of thermal polycondensation reaction; The heated first stream enters the reactor in gaseous form and passes through the reaction products of the first stage of thermal polycondensation from bottom to top. Unreacted materials exit the reactor from the top. The reaction ends when the pressure inside the reactor reaches atmospheric pressure, and the thermal polycondensation products exit the reactor from the bottom.

4. The process according to claim 1 or 2, characterized in that, The temperature of the second stream entering the reactor is 420-480℃, and it reacts for 3-6 hours under the conditions of reaction temperature of 420-480℃ and reaction pressure of 0.1-3MPa.

5. The process according to claim 1 or 2, characterized in that, The temperature of the third stream entering the reactor is 380-460℃. Under the conditions of reaction temperature of 380-460℃ and reaction pressure of 0.1-3MPa, it reacts with the reaction products of the first stage thermal polycondensation reaction for 2-20 hours.

6. The process according to claim 3, characterized in that, When the oil slurry is split into two streams with different distillation ranges, the temperature of the second stream entering the reactor is 420-480℃, and it reacts for 5-26 hours under the conditions of reaction temperature of 420-480℃ and reaction pressure of 0.1-3MPa.

7. The process according to any one of claims 1-3, characterized in that, The temperature of the first stream entering the reactor is 380-460℃.

8. The process according to any one of claims 1-3, characterized in that, After the first stream of feed is completed, the system begins to depressurize at a rate of 0.05-0.1 atm / min.

9. The process according to any one of claims 1-3, characterized in that, The position where the second stream enters the reactor is at a height from the bottom of the reactor that is no less than the height of the reactor occupied by the first-stage thermal polycondensation reaction zone.

10. The process according to claim 1 or 2, characterized in that, The position where the third stream enters the reactor is at a height from the bottom of the reactor that is no less than the height of the reactor occupied by the second-stage thermal polycondensation reaction zone.

11. The process according to any one of claims 1-3, characterized in that, The process also includes a reflux operation at the top of the reactor, with a reflux temperature of 350-450°C.

12. The process according to any one of claims 1-3, characterized in that, The process also includes mixing unreacted material exiting from the top of the reactor with slurry before cutting.

13. The process according to any one of claims 1-3, characterized in that, The oil slurry includes one or a combination of several of the following: clarified oil slurry after desolidification, ethylene tar, coking wax oil, catalytic cycle oil, and furfural extract oil.

14. An oil slurry gradient separation and staged polycondensation system, characterized in that, The oil slurry gradient separation and staged polycondensation system includes a distillation unit, a heating unit, and a reactor. The distillation unit is provided with a first stream outlet, a second stream outlet, a third stream outlet, and a fourth stream outlet from top to bottom. The reactor is provided with a third inlet, a second inlet, and a first inlet from top to bottom. The first stream outlet, the second stream outlet, and the third stream outlet are respectively connected to the first inlet, the second inlet, and the third inlet of the reactor via pipelines through the heating unit, or the first stream outlet, the second stream outlet, and the third stream outlet are respectively connected to the first inlet, the third inlet, and the second inlet of the reactor via pipelines through the heating unit.

15. The system according to claim 14, characterized in that, The distillation apparatus is provided with a first stream outlet, a second stream outlet, and a third stream outlet from top to bottom.

16. The system according to claim 15, characterized in that, The distillation apparatus is provided with a first stream outlet and a second stream outlet at the top and bottom, respectively. The reactor is provided with a second inlet and a first inlet from top to bottom. The first stream outlet and the second stream outlet are respectively connected to the first inlet and the second inlet of the reactor through pipelines via the heating device.

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