Continuous production process of coal pitch product with high added value

Abstract

The invention belongs to the technical field of coal pitch processing, and discloses a continuous production process of a high value-added coal pitch product. Comprising the following steps: mixing medium-temperature soft asphalt and an organic solvent, pressurizing, heating, feeding into a supercritical extraction kettle for supercritical extraction, discharging the extracted mixed fluid from the upper part of the supercritical extraction kettle, and discharging hard asphalt from the lower part of the supercritical extraction kettle; the mixed fluid enters a separator for separation after pressure relief, the separated high-quality asphalt is discharged from the lower part of the separator, and the organic solvent is discharged from the upper part of the separator and recycled for extractive distillation; the heated high-quality asphalt is subjected to a thermal polycondensation reaction in a reaction kettle, and after the reaction, the high-quality asphalt enters an asphalt flash tower to be subjected to flash evaporation to prepare high-quality bonded asphalt; and carrying out thermal polycondensation reaction on the heated high-quality asphalt in a reaction kettle, and carrying out delayed coking reaction in a delayed coking tower after the reaction to obtain the needle coke. According to the process disclosed by the invention, the problems of high ash content and wide-domain molecular weight distribution of the coal pitch are solved by adopting a unit operation combined process.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal tar processing, and in particular relates to a continuous production process for high value-added coal tar products. Background Art

[0002] China's high-temperature coking produces nearly 20 million tons of high-temperature coal tar (coal tar in this invention refers to high-temperature coal tar) every year. The resource is very rich, but the production of asphalt, which accounts for nearly 60% of the coal tar components, has been declining year by year. In 2023, the national coal tar production was less than 5.5 million tons. The main reason for the decline in asphalt production is that in addition to the country's increasingly stringent requirements for environmental protection issues in industrial production, my country's coal tar industry is still mainly concentrated in the low-end medium-temperature asphalt and modified asphalt product fields, resulting in a serious surplus of low-end asphalt products, greatly limiting the development of my country's coal tar industry, and thus affecting the development of the coal tar processing industry. In the tar distillation process, only the light components are separated by distillation, and the remaining asphalt and a large amount of inorganic ash are left at the tail end, resulting in a large amount of ash coal mixed with the coal tar product, which has become a fatal defect in increasing the added value of coal tar products. At the same time, the molecular weight distribution of the coal tar currently used is too broad, with obvious non-concentration and non-uniformity, which is not conducive to the production of high-performance carbon material raw materials in the later stage, such as high-quality impregnating asphalt / adhesive asphalt, needle coke, etc. Therefore, fundamentally developing a new asphalt production process to match the existing main tar processing process and solving the problem of new outlets for asphalt products is the key to the stable development of the tar processing industry. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the aforementioned prior art by providing a continuous production process for high-value-added coal tar pitch products. The present invention's continuous production process for high-value-added coal tar pitch products enables the continuous production of high-quality bonding pitch with uniform molecular weight and low ash content, as well as the stable production of high-quality needle coke products. This solves the problems of high ash content and wide molecular weight distribution in prior art coal tar pitch products.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A continuous production process for high value-added coal tar pitch products comprises the following steps:

[0006] Supercritical extraction separation: Mix the medium-temperature soft asphalt and the organic solvent, then pressurize and heat them before entering the supercritical extraction kettle for supercritical extraction. The organic solvent is a mixture of toluene and n-hexane. After extraction, the mixed fluid is discharged from the upper part of the supercritical extraction kettle, and the hard asphalt is discharged from the lower part of the supercritical extraction kettle. The discharged mixed fluid is depressurized and enters the separator for separation. The separated high-quality asphalt is discharged from the lower part of the separator, and the organic solvent is discharged from the upper part of the separator.

[0007] Heating: Feed high-quality asphalt into a tubular furnace for heating;

[0008] Preparation of high-quality binder pitch or needle coke: Carry out thermal polycondensation reaction on the heated high-quality asphalt in a reaction kettle. There are two stop valves with different heights on the reaction kettle. The stop valve a of the reaction kettle is arranged above the stop valve b of the reaction kettle. The reaction product is discharged through the stop valve b of the reaction kettle and enters an asphalt flash tower for flash evaporation to obtain high-quality binder pitch; or it is discharged through the stop valve a of the reaction kettle and enters a delayed coking tower for delayed coking reaction to obtain needle coke;

[0009] In the above supercritical extraction and separation process, there are at least 3 sets of identical extraction and separation equipment. When continuously producing in the continuous production process of high-value-added coal tar pitch products, at least one set of extraction and separation equipment is feeding raw materials for extraction and separation, and at least one set of extraction and separation equipment is discharging high-quality asphalt. Each extraction and separation equipment is cleaned after being used for extraction and separation 3 - 4 times.

[0010] In the above solution, the average molecular weight of the asphalt in the reaction kettle is adjusted to 800 - 1500, the temperature of the reaction kettle is controlled at 370 - 390 °C, and the residence time is controlled at 8 - 12 hours to synthesize high-quality binder pitch.

[0011] In the above solution, the average molecular weight of the asphalt in the reaction kettle is adjusted to above 3000, the temperature of the reaction kettle is controlled at 390 - 430 °C, and the residence time is controlled at 13 - 17 hours to synthesize needle coke.

[0012] In the above solution, the softening point of the obtained high-quality binder pitch is 90 - 120 °C, the ash content is < 0.001%, and the resin content is ≥ 35%. The high-quality binder pitch is also used as high-quality impregnating pitch.

[0013] In the above solution, the true density of the obtained needle coke is 2.00 - 2.20 g / cm 3 , the ash content is 0.0005% - 0.001%, the thermal expansion coefficient is (8.0 - 15.0) × 10 -7 / °C, and the volatile content is 0.2% - 0.5%.

[0014] In the above solution, there are three sets of identical extraction and separation equipment in the extraction and separation process: the extraction and separation equipment of Line 1, the extraction and separation equipment of Line 2, and the extraction and separation equipment of Line 3. The continuous production operation is as follows: After the feeding of the extraction and separation equipment of Line 1 is completed, extraction starts, and the feeding of the extraction and separation equipment of Line 2 begins; after the extraction of the extraction and separation equipment of Line 1 is completed, high-quality asphalt is discharged, and after the feeding of the extraction and separation equipment of Line 2 is completed, extraction starts, and the feeding of the extraction and separation equipment of Line 1 restarts; after the discharging of the extraction and separation equipment of Line 1 is completed, after the extraction of the extraction and separation equipment of Line 2 is completed, high-quality asphalt is discharged. After circulating extraction 1 - 2 times between the extraction and separation equipment of Line 1 and the extraction and separation equipment of Line 2, the extraction and separation equipment of Line 1 is stopped for equipment cleaning, and the extraction and separation equipment of Line 2 and the extraction and separation equipment of Line 3 start the extraction work. After circulating extraction 1 - 2 times between the extraction and separation equipment of Line 2 and the extraction and separation equipment of Line 3, the extraction and separation equipment of Line 2 stops production for equipment cleaning, and the extraction and separation equipment of Line 3 and the extraction and separation equipment of Line 1 carry out the extraction work. After that, the extraction and separation equipment of Line 3 takes turns to carry out continuous production in sequence.

[0015] In the above solution, the softening point of the hard asphalt discharged from the lower part of the supercritical extraction kettle is 100 - 150 °C, and the ash content ≥ 1%.

[0016] In the above solution, the organic solvent discharged from the upper part of the separator is mixed with the supplemented organic solvent and reused.

[0017] In the above solution, the mass ratio of toluene to n-hexane in the organic solvent is 5:1 - 10:1.

[0018] In the above solution, in the supercritical extraction and separation step, the pressurization pressure is 3.9 - 4.5 MPa.

[0019] In the above solution, in the supercritical extraction and separation step, the heating temperature is 300 - 350 °C.

[0020] In the above solution, in the heating step, the temperature of the high-quality asphalt at the outlet of the tubular furnace is controlled at 360 - 430 °C.

[0021] In the above solution, the softening point of the medium-temperature soft asphalt is 60 - 80 °C.

[0022] In the above solution, in the preparation step of the high-quality binder asphalt, after flash evaporation, the flash evaporation oil is discharged from the upper part of the asphalt flash evaporation tower, and the high-quality binder asphalt is discharged from the lower part of the asphalt flash evaporation tower.

[0023] In the above solution, in the preparation step of the needle coke, after the delayed coking reaction, the light flash evaporation oil is discharged from the upper part of the delayed coking tower. The bottom of the delayed coking tower is cooled with nitrogen, and then deionized water is used for coke cutting and discharging to obtain needle coke.

[0024] In the prior art, wash oil and anthracene oil components are mostly used as extractants for asphalt. The yield of high-quality asphalt extracted by conventional extraction methods is as low as 10-20%, the ash content is usually higher than 0.5%, the extraction time is long, and the extraction effect is poor. When supercritical extraction is carried out using CO2 as an extractant, the extraction rate of some components in asphalt is lower than 10%, and the extraction selectivity is poor.

[0025] In the present invention, a mixture of toluene and n-hexane is selected as an extractant, and supercritical extraction is carried out by controlling the temperature and pressure. The extraction efficiency is high, the extraction selectivity is good, the ash content in asphalt can be quickly removed, and at the same time, ultra-large molecular substances (QI) can be removed, and a better ratio of aromatic hydrocarbons and alkanes can be obtained. The average molecular weight of asphalt can be further homogenized, and the width of the molecular weight distribution can be reduced, providing pure high-quality asphalt and uniform molecular condensation nuclei for subsequent polycondensation reactions; and multiple sets of extraction and separation devices are combined to adopt a rotation production method. Each extraction and separation device operates intermittently. After each extraction and separation device is extracted and separated 3-4 times, the equipment is cleaned to avoid problems such as coking of the equipment after the extraction and separation steps in the supercritical extraction kettle and separator, resulting in an increase in the ash content of the product, ensuring the stability of the product during continuous production. At the same time, the extraction and separation equipment in the present invention is refined and indirectly operated, and can adjust the amount of asphalt raw material fed and the ratio of the extractant, and make the raw material and the supercritical extractant fully contact and extract, so that the extraction is more sufficient, the extraction effect is excellent, the extraction quality and extraction rate of asphalt are improved, and the ash content of the product after extraction is reduced. The ash content of the product after extraction and separation by the process of the present invention can be reduced by 20-30% compared with that of the continuous tower type, so that the ash content of the high-quality asphalt product after supercritical extraction and separation is stably controlled at a low level.

[0026] Specifically, after a large amount of exploration in the present invention, based on the analysis and research of the main components of asphalt (about 60-80% of the components in asphalt are aromatic hydrocarbons with a benzene ring structure of 3-6, and about 5-10% of the components are alkanes between C20 and C40 and other components, etc.), a mixture of toluene and n-hexane (the mass ratio of toluene to n-hexane is 5:1-10:1) is screened and provided as a supercritical extraction solvent, which is pressurized and heated to the supercritical state for asphalt extraction. The extraction yield is high, the extraction selectivity is good, the yield of high-quality asphalt extracted is as high as over 80%, and the extraction operation is faster and smoother, and the ash content index of the high-quality asphalt product is more stable and reliable. By selecting an appropriate ratio of toluene and n-hexane in the present invention, the extraction rate of different components of asphalt by the mixed organic solvent can be regulated, ensuring the ratio of aromatic hydrocarbons and alkanes in the final high-quality asphalt (in the polycondensation reaction, a certain amount of alkane ratio is required, generally the alkane ratio is not less than 10%, which is beneficial to the formation of mesophase in asphalt), and the extraction rates of aromatic hydrocarbons and alkanes in the asphalt components can be ensured. A good aromatic hydrocarbon ratio directly affects the regulation of the molecular weight in the asphalt polymerization reaction, and further affects the quality of the obtained asphalt product.

[0027] By setting reaction kettle stop valves with different heights in the reaction kettle, and through the opening and closing of two reaction kettle stop valves with different heights, the control of the reaction residence time of asphalt in the reaction kettle in the continuous production process can be achieved. Thus, the control of the average molecular weight of the asphalt after the reaction can be realized by controlling the reaction residence time according to the production requirements, so as to be used for the subsequent separate preparation of high-quality binder asphalt and needle coke in the continuous production process.

[0028] The present invention has the following main advantages compared with the prior art:

[0029] 1. The present invention provides a continuous production process for high-value-added coal tar pitch products, which can realize the continuous production of high-quality binder asphalt or needle coke products. The high-quality binder asphalt produced has a uniform and concentrated molecular weight and low ash content, solving the problems of high ash content and wide molecular weight distribution of coal tar pitch.

[0030] 2. The continuous production process for high-value-added coal tar pitch products provided by the present invention can effectively promote the development of the tar processing industry and the development of the high-quality high-power electrode industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of a continuous production process for high-value-added coal tar pitch products according to Embodiment 1 of the present invention.

[0032] In the figure: 1 - supercritical extraction kettle; 2 - heater; 3 - pressure pump; 4 - expansion valve; 5 - separator; 6 - separator extraction pump; 7 - reaction kettle circulation pump; 8 - tubular heating furnace; 9 - reaction kettle; 10 - stop valve a; 11 - stop valve b; 12 - three-way stop valve; 13 - flash distillation tower; 14 - delayed coking tower; 15 - raw material asphalt valve of system 1; 16 - raw material asphalt valve of system 2; 17 - raw material asphalt valve of system 3. DETAILED DESCRIPTION OF THE INVENTION

[0033] The technical method of the present invention will be further described and explained below in conjunction with the drawings and specific embodiments. All the embodiments here are only used to illustrate the present invention and do not limit the protection scope of the present invention.

[0034] Therefore, the detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0035] A continuous production process for high-value-added coal tar pitch products includes the following steps:

[0036] (1) Supercritical extraction and separation: Mix medium-temperature soft pitch and organic solvent, then pressurize through a pressure pump and heat through a heater and enter the supercritical extraction kettle for supercritical extraction. After extraction, the mixed fluid is discharged from the upper part of the supercritical extraction kettle, and the hard pitch is discharged from the lower part of the supercritical extraction kettle; the discharged mixed fluid is depressurized through an expansion valve and then enters a separator for separation. After separation, high-quality pitch is discharged from the lower part of the separator, and the organic solvent is discharged from the upper part of the separator and recycled for extractive distillation; among them, the softening point of the hard pitch discharged from the lower part of the supercritical extraction kettle is 100 - 150 °C, and the ash content ≥ 1%; the high-temperature organic solvent discharged from the upper part of the separator is mixed with the supplemented organic solvent and then returned for reuse. Among them, the extraction and separation process includes at least 3 sets of the same extraction and separation equipment. When continuously producing high-value-added coal tar pitch products, at least one set of extraction and separation equipment is kept for feeding raw materials for extraction and separation, and at least one set of extraction and separation equipment is for discharging high-quality pitch. Each extraction and separation equipment is cleaned after 3 - 4 times of extraction and separation. Among them, the organic solvent is a mixture of toluene and n-hexane, and the mass ratio of toluene to n-hexane in the organic solvent is 5:1 - 10:1. The pressure pressurized by the pressure pump is 3.9 - 4.5 MPa. The temperature heated by the heater is 300 - 350 °C. The softening point of the medium-temperature soft pitch is 60 - 80 °C.

[0037] (2) Heating: Feed the high-quality pitch into a tubular furnace for heating; among them, the temperature of the high-quality pitch at the outlet of the tubular furnace is controlled at 360 - 430 °C.

[0038] (3) Preparation of high-quality binder pitch (which can also be used as high-quality impregnating pitch): Carry out thermal polycondensation reaction on the heated high-quality pitch in a reaction kettle. There are two plug valves with different heights on the reaction kettle. The reaction kettle plug valve a is arranged above the reaction kettle plug valve b. After the reaction, it is discharged through the reaction kettle plug valve b and enters an asphalt flash tower for flash evaporation to obtain high-quality binder pitch; among them, the softening point of the obtained high-quality binder pitch is 90 - 120 °C, the ash content < 0.001%, and the resin content ≥ 35%; among them, the average molecular weight of the pitch in the reaction kettle is adjusted to 800 - 1500, the temperature of the reaction kettle is controlled at 370 - 390 °C, and the residence time is controlled at 8 - 12 hours. After flash evaporation, the flash evaporation oil is discharged from the upper part of the asphalt flash tower, and the high-quality binder pitch is discharged from the lower part of the asphalt flash tower.

[0039] (4) Preparation of needle coke: Carry out thermal polycondensation reaction on the heated high-quality pitch in a reaction kettle. After the reaction, it is discharged through the reaction kettle plug valve a and enters a delayed coking tower for delayed coking reaction to obtain needle coke; among them, the true density of the obtained needle coke is 2.00 - 2.20 g / cm 3 ³, the ash content is 0.0005% - 0.001%, and the thermal expansion coefficient is (8.0 - 15.0) × 10 -7 / °C, with a volatile content of 0.2% - 0.5%. Among them, the average molecular weight of the pitch in the reaction kettle is regulated to more than 3000, the temperature of the reaction kettle is controlled at 390 - 430 °C, and the residence time is controlled to be 13 - 17 hours. After the delayed coking reaction, the light flashed oil is discharged from the upper part of the delayed coking tower. The bottom of the delayed coking tower is cooled with nitrogen, and then deionized water is used for cutting coke and discharging coke to obtain needle coke.

[0040] Example 1

[0041] This example provides a continuous production process for high-value-added coal tar pitch products.

[0042] Specifically, please refer to Figure 1 , the reaction device in this example includes: a supercritical extraction kettle 1, a heater 2, a pressure pump 3, an expansion valve 4, a separator 5, a separator extraction pump 6, a reaction kettle circulation pump 7, a tubular heating furnace 8, a reaction kettle 9, a reaction kettle cock valve a (10), a reaction kettle cock valve b (11), a three-way cock valve 12, a flash tower 13, a delayed coking tower 14, a raw material pitch valve 15 of system 1; a raw material pitch valve 16 of system 2; a raw material pitch valve 17 of system 3. As Figure 1 shown, among them, the extraction and separation related equipment includes a supercritical extraction kettle 1, a heater 2, a pressure pump 3, an expansion valve 4, a separator 5, and raw material pitch valves (15, 16, 17). In this example, three sets of the same extraction and separation equipment are set. When continuously producing high-value-added coal tar pitch products, at least one set of extraction and separation equipment is feeding raw materials for extraction and separation, at least one set of extraction and separation equipment is discharging high-quality pitch, and each set of extraction and separation equipment needs to be cleaned after 3 - 4 times of extraction and separation. The specific connection and continuous production operations of the three sets of the same extraction and separation equipment are as follows:

[0043] The raw asphalt first enters the supercritical extraction kettle 1 of the first system through the asphalt raw material valve 15 of the first system for supercritical extraction. After the feeding is completed, the operation is switched. The asphalt raw material valve 15 of the first system is closed, and the asphalt raw material valve 16 of the second system is opened. The extraction and separation equipment of the second system starts to feed, and the extraction and separation equipment of the first system starts to perform extraction. After the extraction operation, the hard asphalt is discharged from the bottom of the supercritical extraction kettle 1 of the first system, and the hard asphalt is immediately discharged completely by controlling the speed. The separator 5 discharges the high-quality asphalt after extraction; the extraction and separation equipment of the second system completes the feeding and starts to perform extraction. The asphalt raw material valve 16 of the second system is closed and the asphalt raw material valve 15 of the first system is opened to feed the supercritical extraction kettle 1 of the first system. The separator 5 of the first system completes the discharging, the supercritical extraction kettle of the second system completes the extraction operation, the discharging of the separator 5 of the first system stops, and the separator of the second system starts to discharge. Such a cycle ensures the continuity of product generation and raw asphalt replenishment. After the first system extraction and separation equipment and the second system extraction and separation equipment perform cyclic extraction 1 to 2 times, the asphalt raw material valve 15 of the first system is closed, and the first system extraction and separation equipment starts to be cleaned. The asphalt raw material valve 17 of the third system is opened, and the third system extraction and separation equipment starts to perform cyclic extraction work with the second system extraction and separation equipment. After the first system extraction and separation equipment is cleaned, the second system extraction and separation equipment and the third system extraction and separation equipment also perform cyclic extraction 1 to 2 times. Then the second system extraction and separation equipment stops production for equipment cleaning as a standby, and the third system extraction and separation equipment and the first system extraction and separation equipment perform cyclic production. After that, the third system extraction and separation equipment takes turns to perform continuous production in sequence.

[0044] Specifically, in this embodiment, taking the extraction and separation equipment of the first system as an example: the raw asphalt is medium-temperature soft asphalt (softening point 75 °C, directly produced by distillation of high-temperature coal tar). The asphalt raw material valve 15 of the first system is opened, and the medium-temperature soft asphalt is sent to the inlet of the pressure pump 3, and is fully mixed with the organic solvent (a mixture of toluene and n-hexane, and the mass ratio of toluene to n-hexane is 6:1) at the inlet of the pressure pump 3. Through the pressurization of the pressure pump 3 and the heating of the heater 2, the temperature of the mixed material is heated to 330 °C, and the pressure (gauge pressure) is controlled at 4.0 MPa. Then it enters the supercritical extraction kettle 1. After sufficient mixing and extraction, the hard asphalt product (softening point at 130 °C, ash content ≥ 1%) is discharged from the bottom of the supercritical extraction kettle 1, and the mixed fluid is discharged from the upper part of the supercritical extraction kettle 1. The mixed fluid is depressurized through the expansion valve 4 and then enters the separator 5 for separation. After separation, the high-quality asphalt is discharged from the lower part of the separator 5. The yield of the high-quality asphalt is 70% to 85% (the discharge amount of the hard asphalt discharged from the bottom of the supercritical extraction kettle 1 has a certain impact on the yield of the high-quality asphalt. Relatively speaking, the larger the discharge amount of the hard asphalt, the lower the yield of the high-quality asphalt). The high-temperature organic solvent discharged from the upper part of the separator 5 is mixed with the supplemented organic solvent and then returned for reuse. The high-quality asphalt discharged from the separator 5 is sent to the inlet of the reaction kettle circulation pump 7 through the separator extraction pump 6 and mixed with the asphalt pumped out from the bottom of the reaction kettle 9 and then sent to the tubular heating furnace 8 for heating.

[0045] Producing high-quality binder pitch: The temperature of the pitch at the outlet of the tubular heating furnace 8 is controlled at 388 °C. The pitch undergoes a condensation reaction in the reaction kettle 9 to further modulate the molecular weight distribution of the pitch. The average molecular weight of the pitch in the reaction kettle 9 is regulated to 1280, and the temperature of the reaction kettle 9 is controlled at 386 °C. It is discharged by operating the stopcock valve b (11) of the reaction kettle, and the residence time (reaction time) of the materials in the reaction kettle 9 is controlled at 10 hours. Then, it enters the flash distillation column 13 through the three-way stopcock valve c (12) for flash distillation to adjust its softening point. The flash distillate is discharged from the top of the flash distillation column 13, and high-quality binder pitch (softening point around 95 °C, ash content < 0.001%, resin content ≥ 35%) is discharged from the lower part of the flash distillation column 13.

[0046] Producing needle coke: The temperature of the pitch at the outlet of the tubular heating furnace 8 is controlled at about 390 °C. The pitch undergoes a condensation reaction in the reaction kettle 9 to further modulate the molecular weight distribution of the pitch. The average molecular weight of the pitch in the reaction kettle 9 is regulated to above 3000, and the temperature of the reaction kettle 9 is controlled at about 395 °C. By opening the stopcock valve a (10), the reaction residence time of the pitch in the reaction kettle 9 is extended, and the residence time (reaction time) of the materials in the reaction kettle 9 is controlled at 15 hours to enable sufficient polymerization. Then, the pitch is introduced into the delayed coking tower 14 through the three-way stopcock valve c (12) for delayed coking reaction. The light flash distillate is discharged from the top of the delayed coking tower 14. After coking at the bottom of the delayed coking tower 14, nitrogen is used for heat recovery by cooling, and then industrial water (deionized water after treatment to prevent metal ion contamination of the coke) is used for coke cutting and discharging to obtain needle coke products (true density 2.10 g / cm 3 、ash content 0.0008%, thermal expansion coefficient 10.0×10 -7 / °C, volatile matter 0.3%).

[0047] Example 2

[0048] This example provides a continuous production process for high-value-added coal tar pitch products.

[0049] In this embodiment, the 1-series extraction and separation equipment is taken as an example: the raw material asphalt is medium-temperature soft asphalt (softening point 80 °C, directly produced by distilling high-temperature coal tar). The 1-series asphalt raw material valve 15 is opened, and the medium-temperature soft asphalt is fed into the inlet of the pressure pump 3, where it is fully mixed with an organic solvent (a mixture of toluene and n-hexane, with a mass ratio of toluene to n-hexane of 9:1) at the inlet of the pressure pump 3. Through the pressurization of the pressure pump 3 and the heating of the heater 2, the temperature of the mixed material is heated to 320 °C, and the pressure (gauge pressure) is controlled at 4.2 MPa. Then it enters the supercritical extraction kettle 1. After sufficient mixing and extraction, a hard asphalt product (softening point at 130 °C, ash content ≥ 1%) is discharged from the bottom of the supercritical extraction kettle 1, and a mixed fluid is discharged from the upper part of the supercritical extraction kettle 1. The mixed fluid is depressurized through the expansion valve 4 and then enters the separator 5 for separation. After separation, high-quality asphalt is discharged from the lower part of the separator 5, with the yield of high-quality asphalt being 70% - 85%. The high-temperature organic solvent discharged from the upper part of the separator 5 is mixed with the supplementary organic solvent and then returned for reuse. The high-quality asphalt discharged from the separator 5 is sent into the inlet of the reaction kettle circulation pump 7 through the separator extraction pump 6 and mixed with the asphalt drawn from the bottom of the reaction kettle 9, and then sent into the tubular heating furnace 8 for heating.

[0050] Production of high-quality binder asphalt: The temperature of the asphalt at the outlet of the tubular heating furnace 8 is controlled at 400 °C, and the asphalt undergoes a condensation reaction in the reaction kettle 9 to further modulate the molecular weight distribution of the asphalt. The average molecular weight of the asphalt in the reaction kettle 9 is adjusted to 1100, the temperature of the reaction kettle 9 is controlled at 380 °C, and the discharge is controlled by operating the reaction kettle stopcock valve b (11). The residence time (reaction time) of the material in the reaction kettle 9 is controlled at 10 hours, and then it enters the flash distillation tower 13 through the three-way stopcock valve c (12) for flash distillation to adjust its softening point. The flash distillation oil is discharged from the top of the flash distillation tower 13, and high-quality binder asphalt (softening point around 100 °C, ash content < 0.001%, resin content ≥ 35%) is discharged from the lower part of the flash distillation tower 13.

[0051] Production of needle coke: The temperature of the asphalt at the outlet of the tubular heating furnace 8 is controlled at about 410 °C, and the asphalt undergoes a condensation reaction in the reaction kettle 9 to further modulate the molecular weight distribution of the asphalt. The average molecular weight of the asphalt in the reaction kettle 9 is adjusted to over 3000, the temperature of the reaction kettle 9 is controlled at about 407 °C, and the reaction residence time of the asphalt in the reaction kettle 9 is extended by opening the stopcock valve a (10). The residence time (reaction time) of the material in the reaction kettle 9 is controlled at 15 hours to allow it to polymerize sufficiently. Then, the asphalt is introduced into the delayed coking tower 14 through the three-way stopcock valve c (12) for delayed coking reaction. The light flash distillation oil is discharged from the top of the delayed coking tower 14, and after coking at the bottom of the delayed coking tower 14, nitrogen is used for heat recovery by cooling, and then industrial water (treated deionized water to prevent metal ion pollution of coke) is used for cutting coke and discharging to obtain a needle coke product (true density 2.1 g / cm 3, ash content 0.0007%, coefficient of thermal expansion 8.5×10 -7 / °C, volatile matter 0.36%).

[0052] In summary, the present invention provides a continuous production process for high-value-added coal tar pitch products. This process solves the problems of high ash content and wide-range molecular weight distribution of coal tar pitch by adopting a combined unit operation process; this process can realize the continuous production of high-quality binder pitch or needle coke products, and the produced high-quality binder pitch has a uniform and concentrated molecular weight and a low ash content.

[0053] The above embodiments are only used to illustrate the design concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made according to the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A continuous production process for high-value-added coal tar pitch products, characterized in that, It includes the following steps: Supercritical extraction and separation: Mix medium-temperature soft pitch with an organic solvent, then enter a supercritical extraction kettle after pressurization and heating for supercritical extraction. The organic solvent is a mixture of toluene and n-hexane. After extraction, the mixed fluid is discharged from the upper part of the supercritical extraction kettle, and the hard pitch is discharged from the lower part of the supercritical extraction kettle; the discharged mixed fluid enters a separator for separation after depressurization. The high-quality pitch after separation is discharged from the lower part of the separator, and the organic solvent is discharged from the upper part of the separator; Heating: Feed the high-quality pitch into a tubular furnace for heating; Preparation of high-quality binder pitch or needle coke: Carry out thermal polycondensation reaction on the heated high-quality pitch in a reaction kettle. There are two stop valves with different heights on the reaction kettle. Stop valve a of the reaction kettle is arranged above stop valve b of the reaction kettle. The reaction product is discharged through stop valve b of the reaction kettle and enters an asphalt flash tower for flash evaporation to obtain high-quality binder pitch; or is discharged through stop valve a of the reaction kettle and enters a delayed coking tower for delayed coking reaction to obtain needle coke; During the supercritical extraction and separation process, at least 3 sets of the same extraction and separation equipment are included. When continuously producing the high-value-added coal pitch product, at least one set of extraction and separation equipment is feeding raw materials for extraction and separation, and at least one set of extraction and separation equipment is discharging high-quality pitch. Each extraction and separation equipment is cleaned after 3 to 4 times of extraction and separation.

2. The continuous production process of a high-value-added coal tar pitch product according to claim 1, characterized in that: Regulate the average molecular weight of the pitch in the reaction kettle to 800 - 1500, control the reaction kettle temperature at 370 - 390 °C, and control the residence time at 8 - 12 hours to synthesize high-quality binder pitch.

3. A continuous production process for a high-value-added coal tar pitch product according to claim 1, characterized in that: Regulate the average molecular weight of the pitch in the reaction kettle to above 3000, control the reaction kettle temperature at 390 - 430 °C, and control the residence time at 13 - 17 hours to synthesize needle coke.

4. A continuous production process for a high-value-added coal tar pitch product according to claim 1, characterized in that: The softening point of the hard pitch discharged from the lower part of the supercritical extraction kettle is 100 - 150 °C, and the ash content ≥ 1%; the organic solvent discharged from the upper part of the separator is mixed with the supplemented organic solvent and reused.

5. A continuous production process for a high-value-added coal tar pitch product according to claim 1, characterized in that: The softening point of the obtained high-quality binder pitch is 90 - 120 °C, the ash content < 0.001%, and the resin content ≥ 35%; The true density of needle coke is 2.00 - 2.20 g / cm 3 , the ash content is 0.0005% - 0.001%, and the coefficient of thermal expansion is (8.0 - 15.0) × 10 -7 / ℃, and the volatile matter is 0.2% - 0.5%.

6. The continuous production process of a high-value-added coal tar pitch product according to claim 1, characterized in that: There are three sets of identical extraction and separation equipment in the extraction and separation process: the extraction and separation equipment of Line 1, the extraction and separation equipment of Line 2, and the extraction and separation equipment of Line 3. The continuous production operation is as follows: After the feeding of the extraction and separation equipment of Line 1 is completed, extraction starts, and the feeding of the extraction and separation equipment of Line 2 starts; after the extraction of the extraction and separation equipment of Line 1 is completed, high-quality asphalt is discharged, and after the feeding of the extraction and separation equipment of Line 2 is completed, extraction starts, and the feeding of the extraction and separation equipment of Line 1 restarts; after the discharging of the extraction and separation equipment of Line 1 is completed, after the extraction of the extraction and separation equipment of Line 2 is completed, high-quality asphalt is discharged. After 1-2 cycles of extraction between the extraction and separation equipment of Line 1 and the extraction and separation equipment of Line 2, the extraction and separation equipment of Line 1 is stopped for equipment cleaning, and the extraction and separation equipment of Line 2 and the extraction and separation equipment of Line 3 start the extraction work. After 1-2 cycles of extraction are also carried out between the extraction and separation equipment of Line 2 and the extraction and separation equipment of Line 3, the extraction and separation equipment of Line 2 stops production for equipment cleaning, and the extraction and separation equipment of Line 3 and the extraction and separation equipment of Line 1 carry out the extraction work. After that, the extraction and separation equipment of Line 3 takes turns in sequence for continuous production.

7. A continuous production process for a high-value-added coal tar pitch product according to claim 1, characterized in that: In the supercritical extraction and separation step, the mass ratio of toluene to n-hexane in the organic solvent is 5:1 to 10:

1.

8. A continuous production process for a high - value - added coal tar pitch product according to claim 1, characterized in that: In the supercritical extraction and separation step, the pressure for pressurization is 3.9 - 4.5 MPa; the temperature for heating is 300 - 350 °C.

9. The continuous production process of a high value-added coal tar pitch product according to claim 1, characterized in that: The softening point of the medium-temperature soft asphalt is 60 - 80 °C; the temperature of the high-quality asphalt at the outlet of the tubular furnace in the heating step is controlled at 360 - 430 °C.

10. A continuous production process for a high-value-added coal tar pitch product according to claim 1, characterized in that: In the preparation step of the high-quality binder asphalt, after flash evaporation, the flash evaporation oil is discharged from the upper part of the asphalt flash evaporation tower, and the high-quality binder asphalt is discharged from the lower part of the asphalt flash evaporation tower; In the preparation step of the needle coke, after the delayed coking reaction, the light flash evaporation oil is discharged from the upper part of the delayed coking tower. The bottom of the delayed coking tower is cooled with nitrogen, and then deionized water is used for coke cutting and discharging to obtain needle coke.

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