Plug flow asphalt continuous polymerization method and device

Abstract

The invention provides a plug flow asphalt continuous polymerization method and device, and the method comprises the following steps: carrying out segmented temperature control on a first plug flow reactor, conveying a heavy aromatic hydrocarbon raw material from the middle upper part of the first plug flow reactor to the first plug flow reactor, and carrying out pressurized thermal polycondensation to obtain a compressed polycondensation product; and carrying out segmented temperature control on the second plug flow reactor, discharging the compressed polycondensation product from the bottom of the first plug flow reactor, conveying the compressed polycondensation product to the second plug flow reactor from the bottom of the second plug flow reactor, and carrying out reduced pressure thermal polycondensation to obtain the mesophase pitch product. The continuous preparation of the mesophase pitch product can be realized, so that the problem of difficulty in continuous refining in the existing mesophase pitch preparation process can be solved; and the mesophase pitch product obtained by the method is uniform in quality and excellent in performance.

Description

A method and apparatus for continuous polymerization of plug flow bitumen Technical Field

[0001] This invention relates to a method and apparatus for continuous polymerization of plug flow asphalt, belonging to the field of materials technology, particularly the field of novel carbon materials technology. Background Technology

[0002] Existing technologies for the separation of mesophase asphalt mainly use settling tanks for intermittent operation, resulting in low production efficiency.

[0003] The applicant will briefly introduce some prior art that is closely related to this invention, so that those skilled in the art can better understand the situation of the prior art and the drawbacks of the prior art.

[0004] CN113680301A discloses a method and apparatus for preparing spinnable mesophase pitch. The core method for improving the composition of mesophase pitch is to achieve dynamic separation of components during the polymerization process. That is, the heavy components enter the low temperature zone and polymerize under relatively mild conditions, while the light components enter the high temperature zone to accelerate polymerization. This can both accelerate the reaction of the light components and inhibit the excessive polymerization of the heavy components. By employing a gradient non-isothermal thermal field corresponding to the molecular weight gradient, dynamic separation of components and gradient non-isothermal polymerization are achieved. Heavy components polymerize under milder conditions in the lower low-temperature zone, while lighter components polymerize more rapidly in the upper high-temperature zone. This accelerates the reaction of lighter components while suppressing excessive polymerization of heavy components, resulting in a narrower relative molecular weight distribution. The lower asphalt components with similar and moderate molecular weights can form an intermediate phase under mild conditions, reducing QI and BS, increasing BI-QS, and improving spinnability. By separately controlling the heating temperature of each section of the heating resistance wire, gradient heating at equal heights can be achieved to meet the temperature requirements of different locations. This eliminates the need for back-mixing, reducing energy consumption and allowing for continuous feeding at suitable locations and continuous discharge from the bottom, achieving a plug-flow continuous polymerization reaction. This system can operate continuously for at least 3000 hours, enabling continuous production of spinnable mesophase asphalt, and has significant potential for industrial applications.

[0005] However, in this existing technology, because the light components rise and the heavy components descend, the heptane-soluble substances (HS), which have a lower relative density and higher hydrogen content, cannot enter the heavy components for discharge. This results in an excessively high C / H ratio in the mesophase asphalt product, making it prone to exceeding the softening point standard, and the softening point cannot be directly adjusted. Furthermore, due to the downward movement of the material, continuous depressurization thermal polycondensation would cause a large amount of gas to escape (approximately 50% of the total material volume) and move upward, causing severe turbulence and a decline in product properties.

[0006] CN114405433A discloses a multi-stage reaction apparatus and preparation method for high-purity mesophase pitch used in spinning. The multi-stage reaction apparatus includes a primary reactor, a primary separator, a secondary reactor, a secondary separator, a tertiary reactor, and multiple feed pumps, all connected in series via pipelines. The primary separator has a by-product outlet at the bottom and a refined pitch outlet on the side, which is connected to the secondary reactor via a pipeline. The secondary separator has a mesophase pitch outlet at the bottom and a circulating pitch outlet on the side, which is connected to the tertiary reactor via a pipeline, and the circulating pitch outlet is connected to the secondary reactor via a pipeline. Furthermore, heat exchangers are installed between the primary reactor and the primary separator, and between the secondary reactor and the secondary separator, to cool the pitch. The preparation method of high-purity spinning mesophase pitch using a multi-stage reaction device includes the following steps: S1, the melted raw material pitch is pumped to the primary reactor, then cooled to 250-350℃, and then placed in a 200-360℃ separator for settling. The upper layer is first pumped into the secondary reactor through the refined pitch outlet, and then the lower layer is pumped out through the by-product outlet; S2, after the reaction in the secondary reactor, it is sent to a 300-360℃ secondary separator for settling. The upper layer is first pumped into the secondary reactor through the circulating pitch outlet, and then the lower layer is pumped into the tertiary reactor through the mesophase pitch outlet; S3, degassing is carried out in the tertiary reactor, and the light components are removed under negative pressure. The resulting product is the spinning mesophase pitch.

[0007] Although the multi-stage reaction device and preparation method are highly efficient and stable, and can be used for industrial production of mesophase asphalt, producing high-quality mesophase asphalt, the existing technology requires intermittent operation because both the primary and secondary separators use sedimentation separation, which prevents continuous production and significantly limits production efficiency.

[0008] CN113773871A discloses a continuous cyclic polymerization distillation reaction system for preparing mesophase asphalt, comprising: a counter-rotating twin-screw extruder, a magnetically driven constant-pressure stirrer, a static mixer, a static density separator, a first-stage counter-rotating twin-screw devouring extruder, a second-stage counter-rotating twin-screw devouring extruder, and a vacuum filter buffer tank; the main structure of the static density separator is arranged on a loss-in-weight weighing scale, the top of the main structure of the static density separator is the separator feed pipe, and the bottom outlet of the main structure of the static density separator is connected to the inlet of a volumetric metering pump; the outlet of the volumetric metering pump is connected to a third three-way solenoid valve; the third three-way solenoid valve has two passages, and by controlling the third three-way solenoid valve, the outlet of the volumetric metering pump can be connected to a heavy component conveying pipe and a light component conveying pipe separately; the heavy component conveying pipe is connected to the first-stage counter-rotating twin-screw devouring extruder; the light component conveying pipe is connected to the counter-rotating twin-screw extruder through a first three-way solenoid valve and the feed pipe of the conveying extruder. Although this system can solve the problems of low production efficiency, impurity of mesophase asphalt composition, and low quality in the preparation of mesophase asphalt in the prior art, the system disclosed in the prior art uses a static density separator to separate and purify asphalt, which also requires intermittent operation and cannot achieve continuous production, thus greatly limiting the production efficiency.

[0009] Therefore, providing a novel method and apparatus for continuous polymerization of plug flow bitumen has become a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0010] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a method and apparatus for continuous polymerization of plug flow asphalt. The method and apparatus provided by the present invention can solve the problem of continuous refining during the preparation of mesophase asphalt and ensure the uniformity of the quality of the obtained mesophase asphalt product.

[0011] To achieve the above objectives, on the one hand, the present invention provides a method for continuous polymerization of plug flow asphalt, wherein the method includes:

[0012] Step (1): The first plug flow reactor is subjected to segmented temperature control. The heavy aromatic raw material is sent from the middle and upper part of the first plug flow reactor to the first plug flow reactor for pressurized thermal polycondensation (gradient non-isothermal pressurized thermal polycondensation) to obtain the pressurized polycondensation product.

[0013] Step (2): The second plug flow reactor is subjected to segmented temperature control so that the compressed polycondensation product is discharged from the bottom of the first plug flow reactor and sent from the bottom of the second plug flow reactor to the second plug flow reactor for depressurized thermal polycondensation (gradient non-isothermal depressurized thermal polycondensation) to obtain the mesophase asphalt product.

[0014] As a specific embodiment of the method described above in this invention, the heavy aromatics feedstock includes one or a combination of several of the following: catalytic slurry, ethylene tar, vacuum residue, coal tar, and coal pitch.

[0015] As a specific embodiment of the method described above in this invention, in step (1), the segmented temperature control is to form a temperature distribution of 5-10 segments from the top to the bottom of the cavity of the first plug flow reactor, with the temperature difference between adjacent temperature segments being 1-18℃, the temperature of the segment closest to the top of the cavity being 400-470℃, the temperature of the segment closest to the bottom of the cavity being 380-420℃, the pressure inside the first plug flow reactor being 0.11-6MPa, and the residence time of the material inside the first plug flow reactor being 1-10h.

[0016] As a specific embodiment of the method described above in this invention, in step (2), the segmented temperature control is to form a temperature distribution of 5-10 segments from the bottom to the top of the cavity of the second plug flow reactor, with the temperature difference between adjacent temperature segments being 1-16℃, the temperature of the segment closest to the bottom of the cavity being 400-440℃, the temperature of the segment closest to the top of the cavity being 360-390℃, the pressure inside the second plug flow reactor being 0.001-0.095MPa, and the residence time of the material inside the second plug flow reactor being 1-10h.

[0017] In this invention, the cavity of the first and second plug flow reactors refers to the cavity inside the reactor used for the reaction. In some embodiments of this invention, both the first and second plug flow reactors are cylindrical, and the cavity is a hollow cylinder.

[0018] As a specific embodiment of the method described above in this invention, the method further includes discharging the light components generated by pressurized thermal polycondensation through an oil and gas outlet provided at the top of the first plug flow reactor.

[0019] As a specific embodiment of the method described above in this invention, the method further includes discharging the light components generated by depressurized thermal polycondensation through an oil and gas outlet provided at the top of the second plug flow reactor.

[0020] In one specific embodiment of the method described above, when the liquid level in the second plug flow reactor is not lower than the outlet located at the upper part of the second plug flow reactor, the outlet is opened and the mesophase asphalt product is discharged through it. This operation allows the mesophase asphalt product to be discharged from the second plug flow reactor through the outlet located at the upper part of the second plug flow reactor, and prevents gaseous products from being discharged from the outlet.

[0021] On the other hand, the present invention also provides a plug flow asphalt continuous polymerization apparatus for implementing the above-described plug flow asphalt continuous polymerization method, wherein the apparatus includes a first plug flow reactor and a second plug flow reactor, wherein the upper middle part and the bottom of the first plug flow reactor are respectively provided with an inlet and an outlet, and the bottom and the upper middle part of the second plug flow reactor are respectively provided with an inlet and an outlet.

[0022] The heavy aromatics feedstock storage tank is connected to the inlet of the first plug flow reactor via a pipeline, and the outlet of the first plug flow reactor is connected to the inlet of the second plug flow reactor via a pipeline.

[0023] In one specific embodiment of the device described above in this invention, the top of the first plug flow reactor is provided with an oil and gas outlet.

[0024] In one specific embodiment of the device described above in this invention, an oil and gas outlet is provided at the top of the second plug flow reactor.

[0025] In this invention, heavy aromatic raw materials are first fed from the upper middle part of the first plug flow reactor to the first plug flow reactor for pressurized thermal polycondensation. During this process, the material gradually moves downwards due to gravity, while the light components generated by pressurized thermal polycondensation escape in gaseous form and move upwards, opposite to the direction of material movement. However, since the reaction taking place in the first plug flow reactor is a pressurized thermal reaction, i.e., pressurized thermal polycondensation, the amount of light components escaping can be controlled to <10% (calculated with the total weight of the feed to the first plug flow reactor as 100%), thus preventing violent mixing in the first plug flow reactor. The material produced at the bottom of the first plug flow reactor, namely the compressed polymerized product, is then fed from the bottom of the second plug flow reactor to the second plug flow reactor. This material passes through the second plug flow reactor from bottom to top and undergoes depressurized thermal polycondensation. Because this process is a depressurized thermal reaction, a large amount of reaction products escape in gaseous form and move towards the top of the second plug flow reactor, consistent with the direction of material movement within the reactor. This process allows for the escape of light components to be >30% (calculated with the total weight of the feed to the second plug flow reactor as 100%), without causing severe backmixing within the reactor. If the second plug flow reactor uses a top-in, bottom-out feeding method, severe backmixing will occur, and the residence time of the material cannot be strictly controlled. Finally, the material, namely the mesophase asphalt product, is produced in the upper part of the second plug flow reactor.

[0026] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0027] 1) The method and apparatus provided by the present invention can realize the continuous preparation of mesophase asphalt products, thereby solving the problem of continuous refining in the existing mesophase asphalt preparation process.

[0028] 2) The mesophase pitch product obtained by this invention has uniform quality and excellent performance. Attached Figure Description

[0029] 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.

[0030] Figure 1 is a schematic diagram of the structure of the continuous polymerization device for push flow asphalt provided in Embodiment 1 of the present invention.

[0031] Explanation of main icon numbers:

[0032] 1. Heavy aromatics feedstock storage tank;

[0033] 2. First plug flow reactor;

[0034] 3. Second plug flow reactor. Detailed Implementation

[0035] 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 / apparatus, 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Example 1

[0043] This embodiment provides a continuous plug flow asphalt polymerization device, the structural schematic of which is shown in Figure 1. As can be seen from Figure 1, the device includes a heavy aromatics raw material storage tank 1, a first plug flow reactor 2, and a second plug flow reactor 3. The first plug flow reactor 2 is provided with a first feed inlet, a first discharge outlet, and a first oil and gas discharge outlet at its upper middle part, bottom, and top, respectively. The second plug flow reactor 3 is provided with a second feed inlet, a second discharge outlet, and a second oil and gas discharge outlet at its bottom, upper middle part, and top, respectively.

[0044] The heavy aromatics feedstock storage tank 1 is connected to the first feed inlet of the first plug flow reactor 2 via a pipeline, and the first discharge outlet of the first plug flow reactor 2 is connected to the second feed inlet of the second plug flow reactor 3 via a pipeline.

[0045] Examples 2-19

[0046] This series of embodiments provides a method for continuous polymerization of plug flow asphalt, which is implemented using the continuous polymerization apparatus for plug flow asphalt provided in Embodiment 1. The method includes the following steps:

[0047] Step (1): The first plug flow reactor is subjected to segmented temperature control. The segmented temperature control is a temperature distribution that is formed from the top to the bottom of the cavity of the first plug flow reactor and gradually decreases. The heavy aromatic raw material is sent from the middle and upper part of the first plug flow reactor to the first plug flow reactor for pressurized thermal polycondensation. During this process, the material gradually moves downward by gravity. The light components generated by pressurized thermal polycondensation escape in gaseous form and move upward and finally exit the first plug flow reactor through the first oil and gas outlet, which is opposite to the direction of material movement. However, since the first plug flow reactor is subjected to pressurized thermal reaction, i.e. pressurized thermal polycondensation, the amount of light components that escape can be controlled to <10% (calculated with the total weight of the feed to the first plug flow reactor as 100%), so that violent mixing will not occur in the first plug flow reactor.

[0048] Step (2): The second plug flow reactor is subjected to segmented temperature control. The segmented temperature control is to form several segments of temperature distribution from the bottom to the top of the cavity of the second plug flow reactor, and the temperature decreases segment by segment. Then, the material produced at the bottom of the first plug flow reactor is compressed and polymerized. The product is discharged from the bottom of the first plug flow reactor and sent from the bottom of the second plug flow reactor to the second plug flow reactor. The material passes through the second plug flow reactor from bottom to top and undergoes depressurized thermal polycondensation to obtain mesophase asphalt product. Since the process is a depressurized thermal reaction, a large amount of reaction products escape in gaseous form and move to the upper part of the second plug flow reactor, which is consistent with the movement direction of the material in the second plug flow reactor. This process can make the escape amount of light components >30% (calculated with the total weight of the feed to the second plug flow reactor as 100%). This part of light components is discharged from the second plug flow reactor through the second oil and gas outlet, and will not cause serious back mixing in the second plug flow reactor.

[0049] Example 20

[0050] This embodiment provides a method for continuous polymerization of plug flow asphalt, which differs from Embodiment 7 only in that the segmented temperature control in the second plug flow reactor is a temperature distribution that forms 5 segments from the top to the bottom of the cavity of the second plug flow reactor and decreases segment by segment.

[0051] Comparative Example 1

[0052] This comparative example provides a method for continuous polymerization of plug flow asphalt, which differs from Example 7 in that:

[0053] This comparative example only performed step (1), but not steps (2) and (3), and the heavy aromatic raw materials and process parameters used in step (1) were the same as those in Example 7.

[0054] Comparative Example 2

[0055] This comparative example provides a plug flow asphalt polymerization method, which differs from Example 7 in that: although the method in this comparative example involves two-stage reactions, step (2) uses a conventional batch reactor or tubular reactor, and the method includes the following steps:

[0056] Step (1): Same as in Example 7;

[0057] Step (2): Then, the material produced at the bottom of the first plug flow reactor is compressed and discharged from the bottom of the first plug flow reactor and sent to a conventional batch reactor or tubular reactor. After the material enters, the reactor is closed, and then the reactor is heated to 400°C and the pressure is 0.02MPa. After holding the temperature for 6 hours, the reaction is completed. The bottom or top of the reactor is opened to discharge the product.

[0058] Comparative Example 3

[0059] This comparative example provides a method for continuous polymerization of plug flow asphalt, which differs from Example 7 only in that: the second plug flow reactor is not subjected to segmented temperature control, that is, the second plug flow reactor has no temperature gradient, and the material is produced at the bottom of the first plug flow reactor, that is, the compressed polymer product is discharged from the bottom of the first plug flow reactor and sent from the middle and upper part of the second plug flow reactor to the second plug flow reactor, and discharged from the bottom of the second plug flow reactor.

[0060] Comparative Example 4

[0061] This comparative example provides a method for continuous polymerization of plug flow asphalt, which differs from Example 7 only in that: the material is produced at the bottom of the first plug flow reactor, that is, the compressed polymer product is discharged from the bottom of the first plug flow reactor and sent from the middle and upper part of the second plug flow reactor to the second plug flow reactor, and discharged from the bottom of the second plug flow reactor; and the segmented temperature control in the second plug flow reactor is a temperature distribution that forms 5 segments from the top to the bottom of the cavity of the second plug flow reactor and decreases segment by segment.

[0062] The specific substances and composition information of the heavy aromatic feedstocks used in this series of embodiments and Comparative Examples 1-4 are shown in Table 1. The various process parameters involved in the first plug flow reactor in step (1), such as the number of temperature segments or temperature ranges formed from the top to the bottom of the cavity of the first plug flow reactor (denoted as N1), the temperature difference between adjacent temperature segments (denoted as ΔT1), and the temperature of the segment closest to the top of the cavity (denoted as T). 顶1 The temperature of the section closest to the bottom of the cavity (denoted as T) 底1The pressure (denoted as P1) in the first plug flow reactor and the residence time of the material in the first plug flow reactor (denoted as t1) are shown in Table 2. The various process parameters involved in the second plug flow reactor or conventional batch reactor or tubular reactor in step (2) include the number of temperature segments or temperature ranges formed from the bottom to the top of the cavity of the second plug flow reactor (denoted as N2), the temperature difference between adjacent temperature segments (denoted as ΔT2), and the temperature of the segment closest to the top of the cavity (denoted as T). 顶2 The temperature of the section closest to the bottom of the cavity (denoted as T) 底2 The pressure (denoted as P) in the second plug flow reactor and the residence time of the material in the second plug flow reactor (denoted as t2) are shown in Table 2. The properties and yield data of the obtained mesophase asphalt products are also shown in Table 2.

[0063] Table 1

[0064] Catalytic oil slurry, ethylene tar, vacuum residue, coal tar, coal tar pitch (saturated content / wt%): 18.4, 14.3, 27.3, 16.6, 10.1; Aromatic content / wt%): 68.6, 58.2, 38.7, 52.1, 61.3; Resin / wt%): 12.2, 17.4, 27.4, 24.1, 14.4; Asphaltenes / wt%): 0.8, 10.1, 6.6, 7.2, 14.2 surface

[0065] Table 2

[0066]

[0067]

[0068] Note 1: t1 and t2 were calculated as the ratios of the volume of the cavity between the inlet and outlet of the first and second plug flow reactors to the material outflow rate at the outlet, respectively. The softening point was measured using the Mettler cup method, and the optical structure was measured using a polarizing microscope.

[0069] Note 2: The heavy aromatic feedstock used in Example 3 was 50 wt% vacuum residue and 50 wt% ethylene tar; the heavy aromatic feedstock used in Example 5 was 10 wt% coal tar pitch and 90 wt% coal tar; and the heavy aromatic feedstock used in Example 12 was 30 wt% catalytic slurry and 70 wt% ethylene tar.

[0070] As can be seen from the experimental data in Table 2 above, Examples 2-20 of the present invention can obtain mesophase pitch products with both high optical anisotropy content and low softening point, and the yield is relatively high. Compared with Example 7 of the present invention, Example 20 carried out a two-stage reaction, and both stages of the reaction used a plug flow reactor, which can also achieve continuous production. However, in the second plug flow reactor used in Example 20, as the material becomes heavier due to thermal polycondensation, the temperature gradually increases, causing the initial thermal polycondensation reaction to be too slow and unable to fully polymerize. At the same time, the heavy components undergo excessive polycondensation, resulting in a slight deterioration in the optical structure and a slight increase in the softening point of the obtained mesophase pitch product.

[0071] Compared with Example 7 of the present invention, since Comparative Example 1 did not undergo two-stage refining and only completed the prepolymerization reaction, only a small amount of asphalt product with an intermediate phase structure was formed in Comparative Example 1.

[0072] Compared to Example 7 of the present invention, although Comparative Example 2 involved a two-stage reaction, step (2) used a conventional batch reactor or tubular reactor, which could not achieve continuous production. In addition, since the temperature inside a conventional batch reactor or tubular reactor is constant, the temperature inside the reactor cannot be gradually adjusted and lowered according to the gradual polymerization and increasing weight of the material. This results in excessive polymerization of the heavy components in the later stage. Although the optical structure of the resulting mesophase asphalt product is better, its softening point is significantly exceeded.

[0073] Compared to Example 7 of the present invention, Comparative Example 3 involved a two-stage reaction, both of which used plug flow reactors, enabling continuous production. However, because the temperature inside the second plug flow reactor was constant, it was impossible to gradually adjust and lower the reactor temperature according to the gradual polymerization and increasing weight of the material. This resulted in excessive polymerization of the heavy components in the later stages. Furthermore, because the second plug flow reactor used a top-in, bottom-out feeding and discharging method, the material inside the reactor cracked under reduced pressure to produce light components (which accounted for 50% of the total weight of the feed to the second plug flow reactor). These light components were largely vaporized and moved upwards in the second plug flow reactor, opposite to the direction of material movement, causing extensive mixing of the material inside the reactor. This resulted in the mixing of light and heavy components, which were then discharged from the bottom. Although this significantly reduced the softening point of the resulting mesophase asphalt product compared to Comparative Example 2, this was due to the entry of non-mesophase substances into the product caused by the mixing. It also significantly deteriorated the optical structure of the resulting product.

[0074] Compared to Example 7 of the present invention, Comparative Example 4 involved a two-stage reaction, both of which used plug flow reactors, enabling continuous production. Although the feeding method (top in, bottom out) of the second plug flow reactor in Comparative Example 4 was consistent with the temperature gradient change (the segmented temperature control in the second plug flow reactor was a five-segment temperature distribution that decreased progressively from the top to the bottom of the reactor cavity), i.e., as the material thermally condensed and became heavier, the temperature gradually decreased, preventing excessive condensation of heavy components, the top in, bottom out feeding method of the second plug flow reactor caused the material inside to crack under reduced pressure, producing light components (which accounted for 50% of the total weight of the feed to the second plug flow reactor). These light components were vaporized in large quantities and moved upwards in the second plug flow reactor, opposite to the direction of material movement, resulting in extensive mixing of the material inside the reactor. This caused the light and heavy components to mix and be discharged from the bottom. Although the softening point of the product obtained in Comparative Example 4 was lower than that of the mesophase asphalt product obtained in Example 7, the mesophase content in the product was significantly reduced, resulting in a substandard product.

[0075] 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 method for continuous polymerization of plug flow asphalt, characterized in that, The method for continuous polymerization of plug flow asphalt includes: step (1): segmented temperature control of the first plug flow reactor, sending heavy aromatic raw material from the upper middle part of the first plug flow reactor to the first plug flow reactor for pressurized thermal polycondensation to obtain pressurized polycondensation product; step (2): segmented temperature control of the second plug flow reactor, causing the pressurized polycondensation product to be discharged from the bottom of the first plug flow reactor and sent from the bottom of the second plug flow reactor to the second plug flow reactor for depressurized thermal polycondensation to obtain mesophase asphalt product.

2. The method according to claim 1, characterized in that, The heavy aromatic feedstock includes one or a combination of several of the following: catalytic slurry, ethylene tar, vacuum residue, coal tar, and coal pitch.

3. The method according to claim 1 or 2, characterized in that, In step (1), the segmented temperature control is to form a temperature distribution of 5-10 segments from the top to the bottom of the cavity of the first plug flow reactor, with the temperature difference between adjacent temperature segments being 1-18℃. The temperature of the segment closest to the top of the cavity is 400-470℃, and the temperature of the segment closest to the bottom of the cavity is 380-420℃. The pressure inside the first plug flow reactor is 0.11-6MPa, and the residence time of the material inside the first plug flow reactor is 1-10h.

4. The method according to claim 1 or 2, characterized in that, In step (2), the segmented temperature control is to form a temperature distribution of 5-10 segments from the bottom to the top of the cavity of the second plug flow reactor, with the temperature difference between adjacent temperature segments being 1-16℃. The temperature of the segment closest to the bottom of the cavity is 400-440℃, and the temperature of the segment closest to the top of the cavity is 360-390℃. The pressure inside the second plug flow reactor is 0.001-0.095MPa, and the residence time of the material inside the second plug flow reactor is 1-10h.

5. The method according to claim 1 or 2, characterized in that, The method further includes discharging the light components generated by pressurized thermal polycondensation through an oil and gas outlet located at the top of the first plug flow reactor.

6. The method according to claim 1 or 2, characterized in that, The method further includes discharging the light components generated by depressurized thermal polycondensation through an oil and gas outlet provided at the top of the second plug flow reactor.

7. The method according to claim 1 or 2, characterized in that, When the liquid level in the second plug flow reactor is not lower than the discharge port located at the upper part of the second plug flow reactor, the mesophase asphalt product is discharged through the discharge port.

8. A continuous plug flow asphalt polymerization apparatus for implementing the continuous plug flow asphalt polymerization method according to any one of claims 1-7, characterized in that, The apparatus includes a first plug flow reactor and a second plug flow reactor. The first plug flow reactor has an inlet and an outlet at its upper middle and bottom, respectively, and the second plug flow reactor has an inlet and an outlet at its bottom and upper middle, respectively. A heavy aromatics feedstock storage tank is connected to the inlet of the first plug flow reactor via a pipeline, and the outlet of the first plug flow reactor is connected to the inlet of the second plug flow reactor via a pipeline.

9. The apparatus according to claim 8, characterized in that, The first plug flow reactor is provided with an oil and gas outlet at the top.

10. The apparatus according to claim 8 or 9, characterized in that, The top of the second plug flow reactor is provided with an oil and gas outlet.

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