Coal tar hydroprocessing system and method

Abstract

The application discloses a coal tar hydrogenation treatment system and method, which adopts coal tar as raw material to carry out two-stage reactions of hydrogenation refining and hydrocracking, and can produce naphtha, and at least comprises a hydrogenation refining reactor, which is internally provided with a catalyst bed filled with hydrogenation refining catalyst, and is externally provided with a liquid phase circulation channel; the refined and fractionated raw oil is radially introduced from the bottom of the catalyst bed, and is driven by hydrogen gas from below the catalyst bed and upwardly into the catalyst bed, so that a gas-liquid two-phase countercurrent upflow is formed in the catalyst bed, and hydrogenation refining reactions of gas, liquid and solid are carried out in the upflow process; after the reaction, the gaseous phase product is rapidly separated from the catalyst bed under the driving of hydrogen gas, and is directly discharged from the reactor in a relatively independent gaseous phase space above the catalyst bed; and part of the liquid phase material after the reaction enters the liquid phase circulation channel, is combined with new liquid phase feed and is returned to the catalyst bed, so that local liquid phase circulation is realized. The internal structure and gas-liquid flow direction of the hydrocracking reactor are the same as those of the hydrogenation refining reactor.

Description

Technical Field

[0001] This invention relates to the field of hydrogenation reaction technology, and in particular to a two-stage hydrogenation treatment system and method for coal tar. Background Technology

[0002] Coal tar is a liquid product obtained during the dry distillation and gasification of coal. At room temperature, it is a black or dark brown viscous liquid with a pungent odor, primarily composed of polycyclic aromatic compounds. The composition of coal tar is extremely complex, and it can be classified into several different products based on its pyrolysis temperature, including low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar. The industry processes coal tar through hydrogenation to lighten it, obtaining high-value-added low-sulfur naphtha and clean fuel oil, significantly improving the graded utilization of coal tar. This method not only benefits environmental protection and efficient energy utilization but also plays a crucial role in alleviating the shortage of petroleum resources.

[0003] Coal tar hydrogenation technology primarily involves first separating the light components of coal tar through fractionation, then reacting them with hydrogen in a hydrogenation reactor under high temperature and pressure. This process alters and transforms substances such as nitrogen and heavy metals in the coal tar, thereby changing the properties of the coal tar itself. This results in changes to the odor and color of the hydrogenation products. Generally, the resulting clean fuel oil consists mostly of diesel, with naphtha production being relatively low. Because of the complex composition of coal tar, its hydrogenation reaction process is also very complex. Therefore, to solve different engineering problems, many unique coal tar hydrogenation processes have been developed, including process adjustments and catalyst improvements.

[0004] The fixed-bed hydrorefining-hydrocracking two-stage process involves coal tar undergoing hydrorefining and hydrocracking before entering a fractionation tower to obtain clean fuel oil. Because coal tar contains a significant amount of heteroatoms such as sulfur, nitrogen, and oxygen, the ammonia generated during hydrorefining can affect the activity of the hydrocracking catalyst, and the generated water can cause permanent deactivation of the catalyst in the hydrocracking stage. In traditional two-stage processes, multiple separation devices are added, resulting in a complex process flow to protect catalyst activity.

[0005] Even so, most traditional hydrogenation reactors still have some prominent problems in the hydrogenation process. For example, with the long-term operation of fixed-bed hydrogenation equipment, the operating efficiency gradually decreases, which not only reduces product quality but also increases energy consumption. Therefore, it is necessary to find various methods to perform numerical calculations on the reactor and simulate the operating status of the unit in real time to ensure the stable and efficient operation of the unit. At the same time, in conventional heavy oil fixed-bed catalyst loading schemes, the catalyst pore size decreases along the reactant flow direction, which can easily cause reactor bed blockage, especially in the reaction bed where impurities are released after deoxygenation, affecting the long-term stable operation of the entire reaction unit. Since the hydrogenation reaction is an exothermic reaction, excessive cold hydrogen needs to be introduced to avoid local overheating, which greatly increases hydrogen consumption.

[0006] Chinese patent CN116064120B discloses a two-stage hydrotreating apparatus and method for coal tar. The apparatus includes: a hydrorefining reactor, which receives pretreated coal tar as a first liquid phase feed, which flows sequentially from top to bottom through each catalyst bed; hydrogen gas enters uniformly from bottom to top through the bottom of each catalyst bed; the first gaseous product after hydrorefining is discharged from the top of the reactor through an independent gaseous channel, while the first liquid phase product flows to the bottom; and a hydrocracking reactor, which has the same internal structure as the hydrorefining reactor and receives a portion of the first liquid phase product from the hydrorefining reactor as a second liquid phase feed, generating a second gaseous product discharged from the top and a second liquid phase product flowing to the bottom after hydrorefining. This solution effectively solves the problem of timely separation of gaseous reaction products from the reaction zone in the hydrorefining / cracking reactor, improves the properties of the hydrorefining feed, reduces the reaction temperature rise in hydrorefining, lowers the reaction difficulty, and can adapt to more demanding feedstock conditions under the same conditions.

[0007] Although this scheme allows the gaseous products from each catalyst bed in the hydrogenation reaction to converge into a relatively independent gaseous channel and exit the reactor from the top, thus ensuring that the gaseous products from each bed can leave the reaction system relatively quickly, the forward reaction rate and reaction depth still need to be improved, the conversion rate of heavy oil to light oil needs to be increased, and more naphtha cannot be obtained. In addition, the liquid phase after each reaction flows directly into the next catalyst bed, which cannot effectively guarantee the completeness of the reaction in each catalyst bed, and the utilization rate of the catalyst is not high enough.

[0008] Therefore, there is an urgent need for a coal tar hydrogenation treatment system and method that can not only effectively improve the forward reaction rate and reaction depth of the hydrogenation reaction and effectively increase the conversion rate of heavy oil to light oil, thereby obtaining more naphtha, but also make the reaction of each catalyst bed more complete and thorough.

[0009] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0010] The purpose of this invention is to provide a coal tar hydrotreating system and method. By using a co-current upward flow of gas and liquid phases in each catalyst bed of hydrorefining / cracking, and achieving backmixing with some liquid phases outside the catalyst bed without contacting the gas phase, this not only effectively avoids flooding and increased pressure drop, but also effectively improves the forward reaction rate and reaction depth of the hydrotreating reaction, effectively increases the conversion rate of heavy oil to light oil, and ensures that the reaction in each bed is sufficient and complete.

[0011] Another objective of this invention is to provide a coal tar hydrogenation treatment system and method. By setting up relatively independent gas phase spaces above each catalyst bed in the hydrorefining / cracking reactor and separating gas phase products in a timely manner, not only is over-hydrogenation avoided and the selectivity of the reaction improved, but also adverse factors such as water, hydrogen sulfide and ammonia generated in the hydrogenation reaction that easily lead to catalyst deactivation can leave the catalyst bed in a timely manner, which is beneficial to extending the catalyst's operating cycle.

[0012] To achieve the above objectives, according to a first aspect of the present invention, a coal tar hydrotreating system is provided, which uses coal tar as feedstock for a two-stage reaction of hydrorefining and hydrocracking, and produces naphtha. The system includes at least: a hydrorefining reactor containing a bed for filling a hydrorefining catalyst, with liquid-phase circulation channels inside and outside the bed; the feedstock oil, after refining and fractionation, enters radially from the bottom of the catalyst bed, and under the influence of hydrogen gas entering the catalyst bed from below, forms a gas-liquid two-phase upward flow within the catalyst bed. The process involves gaseous, liquid, and solid hydrorefining reactions. After the reaction, the gaseous products are rapidly removed from the catalyst bed by hydrogen and discharged directly from the reactor in a relatively independent gaseous space above the catalyst bed. A portion of the liquid material after the reaction enters the liquid circulation channel and merges with the newly fed liquid material, returning to the catalyst bed to achieve localized liquid circulation. The hydrocracking reactor receives the liquid effluent from the hydrorefining reactor after complete reaction and performs hydrocracking. The internal structure and gas-liquid flow of the hydrocracking reactor are the same as those of the hydrorefining reactor.

[0013] Furthermore, in the above technical solutions, both the hydrorefining reactor and the hydrocracking reactor may be equipped with: a liquid phase feed subunit, which is connected to the liquid phase circulation channel and provides radial feed to the bottom of the hydrorefining / cracking catalyst bed; and a gas phase feed subunit, which is located below the hydrorefining / cracking catalyst bed, with the gas phase feed entering the catalyst bed upwards.

[0014] Furthermore, in the above technical solution, the bed of the hydrorefining / cracking catalyst can be a single layer or multiple layers.

[0015] Furthermore, in the above technical solution, the hydrorefining / cracking catalyst bed can be provided with concentric annular inner and outer guide weirs; the lower edge of the guide weirs is higher than the bottom surface of the catalyst bed to form a radial feed channel; the upper edge of the guide weirs is flush with or 1-10 mm higher than the upper surface of the catalyst bed. Concentric annular inner and outer baffles can be respectively provided at the lower edge of the inner and outer guide weirs and at corresponding positions in the radial feed channel to deflect the radially entering liquid phase feed upwards and prevent gas phase feed from entering the liquid phase circulation channel. The inner and outer baffles can be vertically arranged or inclined towards the center of the catalyst bed; when inclined, the inclination angle is preferably less than or equal to 45°.

[0016] Furthermore, in the above technical solution, an outer overflow weir can be provided on the outer side of the outer guide weir, and an inner overflow weir can be provided on the inner side of the inner guide weir; the inner and outer overflow weirs are in a concentric ring shape; the upper edge of the overflow weir is flush with or higher than the upper edge of the guide weir by 1 to 10 mm; a liquid seal baffle is provided on the lower edge of the overflow weir, and the liquid seal baffle is flush with the lower surface of the catalyst bed.

[0017] Furthermore, in the above technical solution, the space between the guide weir and the overflow weir at the corresponding position constitutes a liquid phase circulation channel; the space outside the outer overflow weir and inside the inner overflow weir constitutes a liquid drop channel, which is used to guide the liquid phase to the next catalyst bed or liquid phase outlet.

[0018] Furthermore, in the above technical solution, the gas phase feed subunit may include: a gas phase feed pipe extending radially along the hydrorefining / cracking reactor; a gas phase distribution pipe located below the hydrorefining / cracking catalyst bed and arranged in a ring or multiple concentric rings, the gas phase distribution pipe intersecting the gas phase feed pipe orthogonally or tangentially, the upper wall of the gas phase distribution pipe having multiple channels for uniformly distributing the gas phase feed to the bottom of the catalyst bed; and a gas phase distribution cavity surrounding the gas phase distribution pipe, allowing only the gas phase feed to enter the catalyst bed upwards. The gas phase distribution cavity can be a cavity structure with a hollow top surface and closed side walls and bottom surface; the hollow area is the area between the inner and outer baffles.

[0019] Furthermore, in the above technical solution, the liquid phase feed subunit may include: a liquid phase feed pipe that extends radially along the hydrorefining / cracking reactor; and a liquid phase distribution pipe that is annular and intersects the liquid phase feed pipe orthogonally or tangentially. The liquid phase distribution pipe extends within the liquid phase circulation channel and has multiple channels in its wall for uniformly distributing the liquid phase feed to the catalyst bed.

[0020] Furthermore, in the above technical solution, when the hydrorefining / cracking catalyst bed is a single layer, downcomers are opened at the bottom of the downcomer channel and at the corresponding positions of the tray to guide the reacted liquid phase to the liquid phase outlet; when the hydrorefining / cracking catalyst bed is multi-layered, downcomers are installed at the bottom of the downcomer channel and at the corresponding positions of the tray to guide a portion of the liquid phase material to the liquid phase circulation channel of the next catalyst bed, so that the liquid phase entering the next layer does not come into contact with the gas phase reaction products of the next layer.

[0021] Furthermore, in the above technical solution, each layer of hydrorefining / cracking catalyst bed is equipped with a gas phase feed sub-unit; the liquid phase feed sub-unit is only set in the uppermost layer of hydrorefining / cracking catalyst bed, or it is set in each layer of hydrorefining / cracking catalyst bed.

[0022] Furthermore, in the above technical solution, when the hydrorefining / cracking catalyst bed is multi-layered, the gaseous products containing water, hydrogen sulfide and ammonia in each layer leave the reaction system without obstruction above the corresponding catalyst bed in a timely manner.

[0023] Furthermore, in the above technical solution, the system of the present invention may further include: a refining distillation tower, which uses preheated, dehydrated and mechanically impurity-free medium-low temperature coal tar and hydrogen as raw materials for distillation. The refining distillation tower is equipped with: a catalyst bed located above the raw material inlet of the refining distillation tower, used to desulfurize and denitrify part of the heated and gasified coal tar components and saturate olefins and aromatics; a heavy oil tank, which receives the liquid phase from the gas-liquid distribution component and diffuses the falling liquid phase from the central region to the outer region; the liquid phase at the top of the heavy oil tank serves as the feed oil for the hydrorefining reactor.

[0024] Furthermore, in the above technical solution, the system of the present invention may also include: a high-pressure separator, which is used to receive the mixed gas phase products from the refining distillation tower, the hydrorefining reactor and the hydrocracking reactor, and to separate out hydrogen for recycling; and a low-pressure separator, which is used to receive the liquid phase from the high-pressure separator and to separate out water and low-grade oil.

[0025] Furthermore, in the above technical solution, the system of the present invention may also include: a fractionation tower, which receives low-grade oil from a low-pressure separator and extracts naphtha components and diesel components from 2 to 4 side streams respectively.

[0026] To achieve the above objectives, according to a second aspect of the present invention, the present invention provides a method for treating coal tar hydrogenation, employing the aforementioned system.

[0027] Furthermore, in the above technical solution, the hydrorefining catalyst is preferably a hydrorefining catalyst with high desulfurization and denitrogenation activity and low aromatic saturation; the hydrorefining catalyst includes a support and an active component, the active component being a metal from Group VIB and Group VIII; the operating conditions of the hydrorefining reactor can be: reaction temperature of 200℃~400℃, reaction pressure of 8MPa~20MPa, hydrogen-to-oil volume ratio of 600:1~1200:1, and volume hourly space velocity of 0.2h⁻¹. -1 ~3.0h -1 .

[0028] Furthermore, in the above technical solution, the hydrocracking catalyst preferably contains Y-type zeolite, alumina, and at least one metal component selected from Group VIII and at least one metal component selected from Group VIB; the operating conditions of the hydrocracking reactor can be: reaction temperature of 300℃~400℃, reaction pressure of 10MPa~20MPa, hydrogen-to-oil volume ratio of 200:1~800:1, and volume hourly space velocity of 0.2h⁻¹. -1 ~2.0h -1 .

[0029] Furthermore, in the above technical solution, the operating conditions of the refining distillation tower can be: reaction temperature of 200℃~400℃, reaction pressure of 8MPa~20MPa, hydrogen-to-oil volume ratio of 600:1~1200:1, and volume hourly space velocity of 0.2h. -1 ~3.0h -1 .

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) In the hydrorefining reactor / hydrocracking reactor, the present invention not only effectively avoids flooding and small particle accumulation by simultaneously upward flow of gas and liquid (i.e., liquid feedstock oil and hydrogen) in the hydrorefining / cracking catalyst bed, but also enables the liquid phase material to repeatedly enter the same catalyst bed for catalytic reaction without external power by driving the liquid phase and local liquid phase circulation through gas phase. This can improve the completeness of hydrorefining / cracking reaction and reduce dependence on external kinetic energy. In other words, the gas phase feed participates in the chemical reaction on the one hand, and makes full use of the kinetic energy carried by the gas phase feed on the other hand, so that the liquid phase material can self-circulate into the catalyst bed.

[0032] 2) In the hydrorefining reactor / hydrocracking reactor of the present invention, the liquid feed can pass through the hydrorefining / cracking catalyst bed rapidly under the impetus of the gas feed, and at the same time the liquid material after the reaction is recycled into the catalyst bed, thereby increasing the cumulative residence time of the reactants in the catalyst bed;

[0033] 3) The present invention has a relatively independent gas phase space above each catalyst bed in the hydrorefining reactor / hydrocracking reactor. Through this space, the gas phase products can leave each catalyst bed quickly and timely (the heat of reaction can be removed quickly). On the one hand, it avoids over-hydrogenation and improves the selectivity of the reaction. On the other hand, the water (in the form of water vapor), hydrogen sulfide and ammonia generated in the hydrogenation reaction can leave the catalyst bed in time, which is conducive to extending the operating cycle of the catalyst.

[0034] 4) In the hydrocracking process of the hydrocracking reactor of the present invention, some long-chain molecules of coal tar break down into short-chain molecules, and some polycyclic aromatic hydrocarbons also undergo ring breaking. The smaller hydrocarbon molecules, together with hydrogen, can be rapidly discharged from the hydrocracking reactor as gaseous products in each layer. That is, the light components of the distillate oil products after hydrocracking can be quickly removed from the catalyst system, thereby improving the forward reaction rate and reaction depth, effectively increasing the conversion rate of heavy oil to light oil, thus creating conditions for obtaining more naphtha in the end.

[0035] 5) In the hydrocracking reactor of the present invention, the rapid departure of each layer of gaseous products during the hydrocracking process can also avoid the over-cracking caused by the light components being retained in the catalyst bed; while hydrogen carries the gaseous products away from the catalyst system, it can also carry the heat of reaction away from the reaction system, which can effectively avoid local overheating caused by the heat of reaction and reduce the hidden danger of catalyst blockage caused by polycyclic aromatic hydrocarbon condensation.

[0036] 6) In the hydrorefining / hydrocracking reactor of this invention, the arrangement of a guide weir and an overflow weir creates a liquid phase circulation channel in the space between the guide weir and the overflow weir. The space outside the outer overflow weir and inside the inner overflow weir creates a downcomer channel. This allows a portion of the reacted liquid phase material to enter the liquid phase circulation channel and return to the catalyst bed of this layer, while the other portion overflows into the downcomer channel and flows into the liquid phase circulation channel of the next bed through a designated path in the downcomer. With this arrangement, neither the liquid phase material flowing downwards in the liquid phase circulation channel nor in the downcomer channel / downcomer will come into contact with the upward-flowing gas phase feed. Therefore, except for the gas-liquid contact reaction inside the catalyst bed, the gas phase feed will not come into reverse contact with the liquid phase material in any other space, completely avoiding flooding problems caused by gas-liquid entrainment.

[0037] 7) This invention uses a refining fractionation tower upstream of the hydrorefining reactor. A hydrorefining catalyst bed is set in the upper part of the refining fractionation tower. After the material enters the tower, gas-liquid phase separation is achieved. The hydrorefining reaction zone only receives the lighter gas phase components in the feed, thus improving the hydrorefining feed conditions, reducing the reaction temperature rise in hydrorefining, and effectively reducing the reaction difficulty of hydrorefining. After the material enters the refining fractionation tower, gas-liquid phase separation is achieved. The heavy components enter the heavy oil tank for precipitation and discharge of solid impurities, while most of the heavier components in better condition enter the hydrorefining / cracking reactor for further light-weight conversion. Compared with the traditional pre-distillation technology, this improves the overall light-weight conversion rate of the feedstock, creating more favorable conditions for subsequent naphtha production.

[0038] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the connection of the coal tar hydrogenation treatment system of the present invention.

[0040] Figure 2 This is a schematic diagram of the first internal structure of the hydrorefining / cracking reactor in the system of the present invention (the reactor is configured as a single bed).

[0041] Figure 3 This is a schematic diagram of the second internal structure of the hydrorefining / cracking reactor in the system of the present invention (the reactor is configured with multiple beds).

[0042] Figure 4 This is a top view schematic diagram of the gas phase distribution pipe of the hydrorefining / cracking reactor of the present invention, which adopts a concentric double-ring distribution pipe.

[0043] Figure 5 This is a schematic diagram of the liquid phase material flow direction inside the hydrorefining / cracking reactor of the present invention.

[0044] Explanation of key figure labels:

[0045] 1-Catalyst bed, 2-Guiding weir, 21-Outer guiding weir, 22-Inner guiding weir, 3-Overflow weir, 30-Liquid seal baffle, 31-Outer overflow weir, 32-Inner overflow weir, 4-Baffle, 41-Outer baffle, 42-Inner baffle, 5-Gas phase distribution cavity, 6-Downcomer, 7-Gas phase feed subunit, 71-Gas phase feed pipe, 72-Gas phase distribution pipe, 72A-Inner ring distribution pipe, 721A-Inner ring channel, 72B-Outer ring distribution pipe, 721B-Outer ring channel, 8-Train tray; A1-Outer liquid phase circulation channel, A2-Inner liquid phase circulation channel, B1-Outer downcomer channel, B2-Inner downcomer channel;

[0046] 100-Hydrorefining reactor, 200-Hydrocracking reactor, 300-Refining fractionation tower, 301-Catalyst bed inside the tower, 302-Gas-liquid distribution assembly, 303-Heavy oil tank, 304-Level gauge, 400-High-pressure separator, 500-Low-pressure separator, 600-Fraction tower, 601-Separating tank, 602-Condenser. Detailed Implementation

[0047] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0048] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0049] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0050] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0051] This invention utilizes medium- and low-temperature coal tar for a two-stage reaction of hydrorefining and hydrocracking. Through the same special internal structure and gas-liquid flow design of the hydrorefining reactor and the hydrocracking reactor, better conditions can be created for the preparation of naphtha and diesel, especially effectively increasing the yield of naphtha.

[0052] like Figure 1 As shown, this invention provides a coal tar hydrotreating system that uses coal tar as feedstock for a two-stage reaction involving hydrorefining and hydrocracking, producing naphtha in large quantities. The system includes at least a hydrorefining reactor 100 and a hydrocracking reactor 200. The hydrorefining reactor 100 contains a bed 1 for filling with a hydrorefining catalyst (which can be configured as follows). Figure 2 single layer or Figure 3 The catalyst bed 1 has liquid phase circulation channels on both the inner and outer sides (i.e., outer liquid phase circulation channel A1 and inner liquid phase circulation channel A2). The refined and fractionated feed oil enters radially from the bottom of the catalyst bed 1 and, driven by hydrogen from below and upward into the catalyst bed, forms a gas-liquid two-phase upward flow within the catalyst bed 1. During the upward flow, a gas, liquid, and solid hydrogenation refining reaction takes place. After the reaction, the gaseous products (including water vapor, hydrogen sulfide, and ammonia) are rapidly removed from the catalyst bed by the hydrogen and discharged directly from the reactor in a relatively independent gas phase space above the catalyst bed (for multi-layered beds, i.e., the space between the catalyst bed 1 and the upper tray 8). A portion of the liquid phase material after the reaction enters the liquid phase circulation channels (i.e., A1 and A2) and merges with the newly introduced liquid phase feed, returning to the catalyst bed 1 to achieve local liquid phase circulation. The hydrocracking reactor 200 receives the liquid phase feed from the bottom of the hydrorefining reactor 100 after complete reaction and performs hydrocracking reaction. The internal structure and gas-liquid flow of the hydrocracking reactor 200 are the same as those of the hydrorefining reactor 100. That is, the hydrocracking reactor 200 is equipped with a hydrocracking catalyst bed, a liquid phase circulation channel, and relatively independent gas phase product spaces in each layer. In the catalyst bed, the gas and liquid flow is upward. The gas phase products are quickly separated from the catalyst bed by hydrogen and directly discharged from the reactor in the relatively independent gas phase space above the catalyst bed.

[0053] By employing the above-mentioned technical solution of the present invention, in the hydrorefining reactor 100 / hydrocracking reactor 200, not only are the simultaneous upward flow of gas and liquid (i.e., liquid feedstock and hydrogen) within the hydrorefining / cracking catalyst bed effectively avoiding flooding and small particle accumulation, but also, through gas-phase-driven liquid-phase and localized liquid-phase circulation, the liquid-phase material can repeatedly enter the same catalyst bed for catalytic reaction without external power. This improves the completeness of the hydrorefining / cracking reaction and reduces dependence on external kinetic energy. In other words, the gas-phase feed participates in the chemical reaction while fully utilizing the kinetic energy carried by the gas-phase feed, enabling the liquid-phase material to self-circulate into the catalyst bed. Driven by the gas-phase feed, the liquid-phase feed can quickly pass through the hydrorefining / cracking catalyst bed, while the reacted liquid-phase material circulates back into the catalyst bed, thereby increasing the cumulative residence time of the reactants in the catalyst bed. In addition, the present invention has a relatively independent gas phase space above each catalyst bed in the hydrorefining reactor 100 / hydrocracking reactor 200. Through this space, the gas phase products can leave each catalyst bed quickly and timely (the heat of reaction can be removed quickly). On the one hand, this avoids over-hydrogenation and improves the selectivity of the reaction. On the other hand, adverse factors such as water, hydrogen sulfide and ammonia generated in the hydrogenation reaction that can easily lead to catalyst deactivation can leave the catalyst bed in time, which is beneficial to extending the operating cycle of the catalyst. Furthermore, regarding the hydrocracking reactor 200, during the hydrocracking process, some long-chain molecules of coal tar break down into short-chain molecules, and some polycyclic aromatic hydrocarbons also undergo ring breaking. The smaller hydrocarbon molecules, along with hydrogen, can be rapidly discharged from the hydrocracking reactor 200 as gaseous products from each layer. In other words, the light components of the distillate products after hydrocracking can quickly leave the catalyst system, thereby increasing the forward reaction rate and reaction depth. This can effectively improve the conversion rate of heavy oil to light oil, thus creating conditions for obtaining more naphtha. At the same time, the rapid departure of gaseous products from each layer can also avoid over-cracking caused by light components remaining in the catalyst bed. While hydrogen carries the gaseous products away from the catalyst system, it can also carry the heat of reaction away from the reaction system. This can effectively avoid local overheating caused by the heat of reaction and reduce the risk of catalyst blockage caused by the condensation of polycyclic aromatic hydrocarbons.

[0054] For the hydrorefining reactor 100 / hydrocracking reactor 200, further as... Figure 2 , 3As shown, to construct the outer liquid phase circulation channel A1 and the inner liquid phase circulation channel A2, the catalyst bed 1 is provided with concentric annular inner and outer guide weirs (i.e., outer guide weir 21 and inner guide weir 22). The lower edge of the guide weir is higher than the bottom surface of the catalyst bed 1, forming a radial feed channel; the upper edge of the guide weir is flush with or slightly higher than the upper surface of the catalyst bed 1 by 1-10 mm. With this arrangement, the radially entering liquid phase material, driven by the rising gas phase, rises in the catalyst bed and undergoes a catalytic reaction. When the liquid phase material rises to the upper surface of the catalyst bed, a portion of the material passes over the outer guide weir 21 and the inner guide weir 22 and descends. Since this descending channel is outside the catalyst bed, the descending liquid phase will not come into contact with the rising gas phase inside the catalyst bed. To minimize the reverse contact between the liquid and gas phases at this location, concentric annular outer baffles 41 and inner baffles 42 are respectively installed at the lower edges of the outer guide weir 21 and the inner guide weir 22, and at corresponding positions in the radial feed channel. These baffles not only deflect the radially entering liquid feed upwards but also prevent the gas feed from entering the liquid circulation channel A. Furthermore, both the outer baffles 41 and the inner baffles 42 can be vertically arranged or inclined towards the center of the catalyst bed. When inclined, the inclination angle is preferably less than or equal to 45°.

[0055] Further as Figure 2 , 3 As shown, an outer overflow weir 31 may be provided on the outer side of the outer guide weir 21, and an inner overflow weir 32 may be provided on the inner side of the inner guide weir 22. The inner and outer overflow weirs are concentric rings. The upper edge of the overflow weir 3 is preferably flush with or 1-10 mm higher than the upper edge of the guide weir 2; a liquid seal baffle 30 may be provided on the lower edge of the overflow weir 3, and the liquid seal baffle 30 is flush with the lower surface of the catalyst bed. With this arrangement, the space between the guide weir and the overflow weir constructs the liquid phase circulation channel of the present invention (i.e., the outer liquid phase circulation channel A1 and the inner liquid phase circulation channel A2), and the space outside the outer overflow weir 31 (i.e., the space between the outer overflow weir 31 and the inner wall of the hydrorefining reactor 100 / hydrocracking reactor 200) and the space inside the inner overflow weir 32 construct the downcomer channel of the present invention (i.e., the outer downcomer channel B1 and the inner downcomer channel B2). The function of the descending channel is to guide another portion of the reacted liquid phase material to the next catalyst bed 1. Figure 3 (Multi-layer configuration) or liquid phase outlet ( Figure 2 (Single-layer configuration in the text). Figure 5 The diagram shows the overall flow direction of the liquid phase in each catalyst bed of the present invention.

[0056] Further as Figure 4 As shown, the gas phase feed subunit 7 of the present invention may further include a gas phase feed pipe 71, a gas phase distribution pipe 72, and a gas phase distribution cavity 5 (see reference). Figure 2 , 3The gas phase feed pipe 71 extends radially along the hydrorefining / cracking reactor. The gas phase distribution pipe 72 is located below the catalyst bed and is annular or multi-layered concentric annular. The gas phase distribution pipe 72 intersects the gas phase feed pipe 71 orthogonally or tangentially. The upper wall of the gas phase distribution pipe 72 is provided with multiple channels to uniformly distribute the gas phase feed to the bottom of the catalyst bed. Figure 4 The diagram illustrates a "double-layer concentric ring" configuration. The gas phase distribution pipe includes an inner ring distribution pipe 72A and an outer ring distribution pipe 72B. The upper walls of the inner and outer ring distribution pipes are respectively provided with inner ring channels 721A and outer ring channels 721B. Further details are provided below. Figure 2 , 3 As shown, the gas phase distribution cavity 5 surrounds the gas phase distribution pipe, allowing only the gas phase feed to enter the catalyst bed 1 upwards. Preferably, but not limitingly, the gas phase distribution cavity 5 is a cavity structure with a hollow top surface and closed side walls and bottom surface. The hollow area is the area between the outer baffle 41 and the inner baffle 42. This arrangement effectively prevents the upward-flowing gas phase feed from entering the liquid phase circulation channel A. When the catalyst bed has multiple layers, each catalyst bed layer is provided with a gas phase feed subunit 7.

[0057] Furthermore, the liquid phase feed subunit (not shown in the figure) of the present invention is arranged similarly to the gas phase feed subunit 7, and the opening direction of the channels can be adjusted as needed. It includes a liquid phase feed pipe and a liquid phase distribution pipe. The liquid phase feed pipe extends radially along the hydrorefining / cracking reactor; the liquid phase distribution pipe is annular and intersects the liquid phase feed pipe orthogonally or tangentially. This liquid phase distribution pipe extends within the liquid phase circulation channel and its wall is provided with multiple channels for uniformly distributing the liquid phase feed to the catalyst bed 1. When the catalyst bed has multiple layers, the liquid phase feed subunit is only arranged in the uppermost catalyst bed, or it can be arranged in each catalyst bed layer.

[0058] Further as Figure 2 As shown, when the catalyst bed 1 of the hydrorefining reactor 100 / hydrocracking reactor 200 of the present invention is a single layer, downcomers are opened at the bottom of the downcomer channel B and at the corresponding positions of the tray 101 (i.e., Figure 2 (at the location of the dashed arrow), used to guide the reacted liquid phase from the descending liquid channel to the liquid phase outlet; such as... Figure 3As shown, when the catalyst bed 1 is multi-layered, a downcomer 6 is preferably installed at the bottom of the downcomer channel B of each layer and at the corresponding position of the tray 101 of each layer. This is used to guide a portion of the liquid phase material to the liquid phase circulation channel A of the next catalyst bed, so that the liquid phase entering the next layer does not come into contact with the gas phase reaction products of the next layer. With this arrangement, substances in the gas phase products that are prone to catalyst deactivation, such as water, hydrogen sulfide, and ammonia, can leave the reaction system without obstruction above the corresponding catalyst bed and in a timely manner. In addition, the gas phase products containing light components of hydrocracking distillate oil products can quickly leave the catalyst system, which can effectively improve the conversion rate of heavy oil to light oil, thereby creating conditions for obtaining more naphtha in the end.

[0059] The hydrorefining reactor 100 / hydrocracking reactor 200 of the present invention, through the arrangement of a guide weir and an overflow weir, constructs a liquid phase circulation channel A in the space between the guide weir and the overflow weir, and a downcomer channel B in the space outside the outer overflow weir and inside the inner overflow weir. This allows a portion of the reacted liquid phase material to enter the liquid phase circulation channel and return to the catalyst bed of this layer, while another portion of the liquid phase material overflows into the downcomer channel and then flows into the liquid phase circulation channel of the next bed through the designated path of the downcomer 6. In this way, neither the liquid phase material flowing downwards in the liquid phase circulation channel A nor the liquid phase material flowing downwards in the downcomer channel B or downcomer 6 will come into contact with the upward-flowing gas phase material. Therefore, except for the gas-liquid contact reaction inside the catalyst bed, the gas phase feed in any other space will not come into reverse contact with the liquid phase material, completely avoiding the flooding problem caused by gas-liquid entrainment. In addition, the downcomer in each layer ensures that the liquid material flowing down into the next bed will not come into contact with the gaseous products above the next bed. This avoids secondary reactions and allows the gaseous products to be separated directly and promptly in each layer without any obstruction, quickly leaving the reaction system.

[0060] Further as Figure 1As shown, the system of the present invention may further include a refining distillation tower 300. This refining distillation tower 300 uses preheated, dehydrated, and mechanically impurity-free medium-low temperature coal tar and hydrogen as raw materials for distillation. Specifically, preferably but not limitingly, the refining distillation tower 300 may be equipped with an internal catalyst bed 301, a gas-liquid distribution assembly 302, and a heavy oil tank 303. The internal catalyst bed 301 is located above the feed inlet of the refining distillation tower 300 and is used to desulfurize, denitrify, and saturate olefins and aromatics in part of the heated and gasified coal tar components. The heavy oil tank 303 receives the liquid phase from the gas-liquid distribution assembly 302 and diffuses the liquid phase falling into the tank from the central region to the outer region. The liquid phase at the top of the heavy oil tank 303 serves as the feed oil for the hydrorefining reactor 100 of the present invention. The heavy oil tank 303 is equipped with a level gauge 304, which controls the liquid level of the heavy oil tank 303 through automated control. When the liquid level is between the highest and lowest levels, the liquid phase material in the upper part of the heavy oil tank 303 (i.e., Figure 1 The feedstock oil from the hydrorefining reaction enters the hydrorefining reactor 100, while a small amount of excessively heavy sludge impurities (i.e., oil from the heavy oil tank 303) are present at the bottom. Figure 1 The heavy oil precipitates in the system are then discharged from the system of this invention.

[0061] Further as Figure 1 As shown, the system of the present invention may further include a high-pressure separator 400 and a low-pressure separator 500. The high-pressure separator 400 receives the mixed gaseous products from the refining fractionation tower 300, the hydrorefining reactor 100, and the hydrocracking reactor 200, and separates hydrogen for recycling. The low-pressure separator 500 receives the liquid phase from the high-pressure separator 400 and separates water and low-grade oil. Additionally, the system of the present invention may further include a fractionation tower 600, which receives the low-grade oil from the low-pressure separator 500 and extracts naphtha components and diesel components (including...) from 2 to 4 side streams. Figure 1 (Light diesel and heavy diesel in the mixture). It should be noted that since the mixed gaseous products entering the high-pressure separator 400 are all light components that have undergone hydrorefining and / or hydrocracking, especially the rapid removal of the gaseous products from the catalyst system after hydrocracking, the conversion rate of heavy oil to light oil can be effectively improved, thus creating conditions for the fractionation tower 600 to finally obtain more naphtha.

[0062] This invention also provides a method for treating coal tar hydrogenation, using the aforementioned system. See below for reference. Figures 1 to 5 Detailed explanation of the process flow of the method of the present invention:

[0063] 1) After being dehydrated and removed from mechanical impurities, the medium- and low-temperature coal tar is preheated and fed together with hydrogen into the refining and fractionating tower 300, below the catalyst bed 301. Dispersed by the gas-liquid distribution component 302, it separates into a gas phase and a liquid phase within the refining and fractionating tower 300. The gas phase contains hydrogen and some heated and vaporized coal tar components. This gas phase component rises through the catalyst bed 301, achieving the purpose of improving the properties of the oil. The improved gas phase component then sequentially enters the high / low pressure separators 400 / 500, where hydrogen and water are separated. The hydrogen undergoes purification treatment and is recycled. The low-grade oil generated by the low-pressure separator 500 continues to enter the fractionation tower 600. Two to four side streams can be opened in the fractionation tower 600 to extract light and heavy diesel oil components and naphtha components, respectively. The liquid phase feed in the material entering the refining fractionation tower 300 flows downward into the heavy oil tank 303. The liquid level in the heavy oil tank is controlled by the level gauge 304. When the liquid level is between the highest and lowest levels, part of the liquid phase material in the upper part of the heavy oil tank 303 enters the hydrorefining reactor 100, while a small amount of excessively heavy sludge impurities (i.e., heavy oil sediment) at the bottom of the heavy oil tank 303 is discharged from the system.

[0064] 2) After heating, a portion of the liquid material from the heavy oil tank 303 is fed into the uppermost catalyst bed of the hydrorefining reactor 100 as liquid feed. It is radially and uniformly distributed within catalyst bed 1, contacting hydrogen gas from the bottom of catalyst bed 1 and moving upwards together. The reaction temperature is 200℃~400℃, the reaction pressure is 8MPa~20MPa, the hydrogen-to-oil volume ratio is 600:1~1200:1, and the volume hourly space velocity is 0.2h⁻¹. -1 ~3.0h -1 The feedstock oil and hydrogen undergo a hydrogenation reaction in the catalyst bed of the reactor. The gaseous products after the reaction leave the reactor 100 directly from each layer, while the liquid phase after the reaction completes local circulation in each catalyst bed. Under the action of the catalyst in the reactor 100, desulfurization, denitrification, and saturation of olefins and aromatics are completed, thereby improving the properties of the oil.

[0065] 3) The improved liquid-phase product after hydrorefining continues to enter the uppermost catalyst bed of the hydrocracking reactor 200, where it is radially and uniformly distributed. It moves upwards in contact with hydrogen gas from the bottom of the catalyst bed. The reaction temperature is 300℃~400℃, the reaction pressure is 10MPa~20MPa, the hydrogen-to-oil volume ratio is 200:1~800:1, and the volume hourly space velocity is 0.2h⁻¹. -1 ~2.0h -1In coal tar, some long-chain molecules break down into short-chain molecules, and some polycyclic aromatic hydrocarbons also undergo ring breaking. The smaller hydrocarbon molecules, along with hydrogen, are discharged from the reactor as gaseous products. They then mix with gaseous products from the refining fractionation tower 300 and the hydrorefining reactor 100, and sequentially enter the high / low pressure separators 400 / 500. The low-pressure oil continues into the fractionation tower 600, where diesel and naphtha components are extracted via side streams. The hydrogenated heavy components generated in the hydrocracking reactor 200 flow downwards into the next catalyst bed, repeating the hydrocracking reaction. Finally, they flow into the bottom heavy oil tank. The bottom liquid phase can be used as feedstock, entering the top layer of the hydrocracking reactor 200 along with the liquid products from the hydrorefining reactor 100.

[0066] Since the coal tar hydrogenation treatment method of the present invention uses the aforementioned system, it can achieve all the aforementioned technical effects of the system, which will not be repeated here.

[0067] Example 1

[0068] In this embodiment, the feedstock is medium-low temperature coal tar, the properties of which are shown in Table 1. After dehydration and impurity removal, the coal tar is heated to 300°C and then fed into a refining fractionation tower 300 along with hydrogen. The light components rise with the hydrogen into the refining catalyst bed, while the heavy components descend into the heavy oil tank. The settled heavy oil is then sent to a hydrorefining reactor 100. The specific operating conditions of the hydrorefining reactor 100 are shown in Table 3. The hydrorefining reactor has six beds, each 200 mm high, completely filled with hydrorefining catalyst. The hydrorefining catalyst contains 17 wt% molybdenum oxide, 5 wt% nickel oxide, and the remainder is a silica or alumina support. The pore volume of the hydrorefining catalyst is 0.4 mL / g, and the specific surface area is 185 m². 2 / g; The raw material is in contact with hydrogen in the co-current upward flow in the hydrotreating reactor 100, and first undergoes a hydrorefining reaction. The gaseous products such as H2O, H2S, and NH4 generated by the reaction leave the catalyst bed directly and exit the reactor. The liquid products circulate locally in each layer, and then pass through all the refining beds in sequence before exiting the reactor and being sent to the hydrocracking reactor 200. The specific operating conditions of the hydrocracking reactor are shown in Table 3. The hydrocracking reactor has a total of 6 beds, all of which are filled with hydrocracking catalyst. The height of a single catalyst bed is 220 mm. The hydrocracking catalyst contains 8 wt% nickel oxide, 22 wt% tungsten oxide, and the balance is a silica or alumina support. All gaseous products generated in the hydrorefining / cracking reactor leave the catalyst bed and enter the high-pressure separator 400 directly. The high-pressure separator 400 operates at a temperature of 85°C. After desulfurization and nitrogen purification, the high-pressure gas is mixed with fresh hydrogen and returned to the hydrorefining reactor. The high-pressure oil is sent to the low-pressure separator 500. The separated low-pressure gas is discharged upwards, while the low-pressure oil continues to enter the fractionation tower 600 for further separation to obtain naphtha and light and heavy diesel oil (product properties are shown in Table 4).

[0069] Example 2

[0070] This embodiment is the same as Embodiment 1, except that the system operating temperature is 330℃. Product properties are shown in Table 4.

[0071] Example 3

[0072] This embodiment is the same as Embodiment 1, except that the system operating temperature is 350℃. Product properties are shown in Table 4.

[0073] Comparative Example 1

[0074] A conventional pre-distillation-hydrorefining process was employed. Both the pre-distillation and hydrorefining reactors used conventional equipment. The feedstock, after being cut into lighter components (properties shown in Table 2) by the pre-distillation column, entered the hydrorefining reactor along with hydrogen, in a top-to-bottom flow reaction. In the comparative example, the separation temperature from the distillation column was 370°C. The catalyst packed in the refining reactor was the same as that in Example 1, with a volume ratio of 1:1. A full tail oil recirculation process was used, with the tail oil intermittently discharged. All other process conditions were the same as in Example 1.

[0075] Table 1 Properties of the Crude Oil

[0076] project data Family composition, % data <![CDATA[Density, g / cm 3 > 1.089 Saturated fraction 17.1 <![CDATA[Viscosity / mm 2 / s]]> 26.4 Aromatic components 22.07 Sulfur content, vol% 0.19 gelatinous 46.01 Nitrogen content, % 0.27 Asphalt 1.2 Carbon residue value, % 6.12 Total metal content, μg / g 115.44

[0077] Table 2 Properties of Pre-distilled Light Component Distillate Oils

[0078]

[0079] Table 3 Operating conditions for the examples and comparative examples

[0080]

[0081] Table 4. Product Properties of Examples and Comparative Examples

[0082]

[0083] The experimental results from the examples show that the water generated in the reaction can be effectively discharged and then separated in the high and low fractions, ensuring the service life of the catalyst; higher quality clean fuel oil can be obtained, and the naphtha yield is improved compared with the traditional two-stage hydrogenation process.

[0084] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A coal tar hydrogenation treatment system, characterized in that, Using coal tar as feedstock, a two-stage reaction involving hydrorefining and hydrocracking is carried out, producing a large amount of naphtha, including: The hydrorefining reactor contains a bed filled with a hydrorefining catalyst, with liquid phase circulation channels inside and outside the bed. The refined and fractionated feedstock enters radially from the bottom of the catalyst bed and, driven by hydrogen gas entering upwards from below, forms a gas-liquid two-phase upward flow within the catalyst bed, during which a gas-liquid-solid hydrorefining reaction occurs. After the reaction, the gaseous product rapidly detaches from the catalyst bed under the influence of hydrogen gas and is directly discharged from the reactor in a relatively independent gas phase space above the catalyst bed. A portion of the liquid material after the reaction enters the liquid phase circulation channel, merges with the newly introduced liquid feedstock, and returns to the catalyst bed, achieving localized liquid phase circulation. The hydrocracking reactor receives the liquid phase feed from the hydrorefining reactor after the reaction is complete, and performs the hydrocracking reaction; the internal structure and gas-liquid flow of the hydrocracking reactor are the same as those of the hydrorefining reactor.

2. The coal tar hydrogenation treatment system according to claim 1, characterized in that, Both the hydrorefining reactor and the hydrocracking reactor are equipped with: A liquid phase feed subunit is connected to the liquid phase circulation channel and provides radial feed to the bottom of the hydrorefining / cracking catalyst bed; The gas-phase feed subunit is located below the hydrorefining / cracking catalyst bed, with the gas-phase feed entering the catalyst bed upwards.

3. The coal tar hydrogenation treatment system according to claim 1, characterized in that, The bed of the hydrorefining / cracking catalyst is configured as a single layer or multiple layers.

4. The coal tar hydrogenation treatment system according to claim 1, characterized in that, The bed of the hydrorefining / cracking catalyst is provided with concentric annular inner and outer guide weirs; the lower edge of the guide weir is higher than the bottom surface of the catalyst bed to form a radial feed channel; the upper edge of the guide weir is flush with or 1-10 mm higher than the upper surface of the catalyst bed.

5. The coal tar hydrogenation treatment system according to claim 4, characterized in that, The lower edges of the inner and outer guide weirs and the corresponding positions of the radial feed channel are respectively provided with concentric ring-shaped inner baffles and outer baffles, which are used to deflect the radially entering liquid phase feed upward and block the gas phase feed from entering the liquid phase circulation channel.

6. The coal tar hydrogenation treatment system according to claim 5, characterized in that, The inner and outer baffles are set vertically or inclined toward the center of the catalyst bed; when inclined, the inclination angle is less than or equal to 45°.

7. The coal tar hydrogenation treatment system according to claim 4, characterized in that, An outer overflow weir is provided on the outer side of the outer guide weir, and an inner overflow weir is provided on the inner side of the inner guide weir; the inner and outer overflow weirs are concentric rings in shape; the upper edge of the overflow weir is flush with or 1-10 mm higher than the upper edge of the guide weir; a liquid seal baffle is provided on the lower edge of the overflow weir, and the liquid seal baffle is flush with the lower surface of the catalyst bed.

8. The coal tar hydrogenation treatment system according to claim 7, characterized in that, The space between the guide weir and the corresponding overflow weir constitutes the liquid phase circulation channel; the space outside the outer overflow weir and inside the inner overflow weir constitutes the liquid drop channel, which is used to guide the liquid phase to the next catalyst bed or the liquid phase outlet.

9. The coal tar hydrogenation treatment system according to claim 2, characterized in that, The gas phase feed subunit includes: A gas-phase feed pipe extends radially along the hydrorefining / cracking reactor; A gas phase distribution pipe is located below the hydrorefining / cracking catalyst bed and is in the form of a ring or multiple concentric rings. The gas phase distribution pipe intersects the gas phase feed pipe orthogonally or tangentially. The upper wall of the gas phase distribution pipe is provided with multiple channels for uniformly distributing the gas phase feed to the bottom of the catalyst bed. The gas phase distribution cavity surrounds the gas phase distribution pipe, allowing only the gas phase feed to enter the catalyst bed upwards.

10. The coal tar hydrogenation treatment system according to claim 9, characterized in that, The gas phase distribution cavity is a cavity structure with a hollow top surface and closed side walls and bottom surface; the hollow area is the area between the inner and outer baffles.

11. The coal tar hydrogenation treatment system according to claim 2, characterized in that, The liquid phase feed subunit includes: The liquid feed pipe extends radially along the hydrorefining / cracking reactor; The liquid phase distribution pipe is annular and intersects the liquid phase feed pipe orthogonally or tangentially. The liquid phase distribution pipe extends within the liquid phase circulation channel and has multiple channels in its wall to uniformly distribute the liquid phase feed to the catalyst bed.

12. The coal tar hydrogenation treatment system according to claim 8, characterized in that, When the hydrorefining / cracking catalyst bed is a single layer, downcomers are provided at the bottom of the downcomer channel and at the corresponding positions of the tray to guide the reacted liquid phase to the liquid phase outlet. When the hydrorefining / cracking catalyst bed is multi-layered, downcomers are provided at the bottom of the downcomer channel and at the corresponding positions of the tray to guide a portion of the liquid phase material to the liquid phase circulation channel of the next catalyst bed, so that the liquid phase entering the next layer does not come into contact with the gas phase reaction products of the next layer.

13. The coal tar hydrogenation treatment system according to claim 2, characterized in that, Each hydrorefining / cracking catalyst bed is equipped with the gas phase feed sub-unit; the liquid phase feed sub-unit is only provided in the uppermost hydrorefining / cracking catalyst bed, or it is provided in each hydrorefining / cracking catalyst bed.

14. The coal tar hydrogenation treatment system according to claim 3, characterized in that, When the hydrorefining / cracking catalyst bed is multi-layered, the gaseous products containing water, hydrogen sulfide and ammonia in each layer leave the reaction system without obstruction above the corresponding catalyst bed.

15. The coal tar hydrogenation treatment system according to claim 1, characterized in that, The system also includes: The refining distillation tower uses preheated, dehydrated, and mechanically impurity-free medium- and low-temperature coal tar and hydrogen as raw materials for distillation.

16. The coal tar hydrogenation treatment system according to claim 15, characterized in that, The refining and fractionation column is equipped with: The catalyst bed, located above the feed inlet of the refining distillation tower, is used to desulfurize and denitrify the partially heated and gasified coal tar components and saturate olefins and aromatics. The heavy oil tank receives the liquid phase from the gas-liquid distribution component and diffuses the falling liquid phase from the central region to the outer region; the liquid phase at the top of the heavy oil tank serves as the feedstock oil for the hydrorefining reactor.

17. The coal tar hydrogenation treatment system according to claim 16, characterized in that, The system also includes: A high-pressure separator is used to receive the mixed gaseous products from the refining distillation column, the hydrorefining reactor and the hydrocracking reactor, and to separate out hydrogen for recycling. A low-pressure separator is used to receive the liquid phase from the high-pressure separator and separate water and low-grade oil.

18. The coal tar hydrogenation treatment system according to claim 17, characterized in that, The system also includes: The fractionation tower receives the low-pressure oil from the low-pressure separator and extracts naphtha and diesel components from 2 to 4 side streams.

19. A method for hydrogenating coal tar, characterized in that, The system described in any one of claims 1 to 18 is used.

20. The coal tar hydrogenation treatment method according to claim 19, characterized in that, The hydrorefining catalyst employs high desulfurization and denitrogenation activity with low aromatic saturation. The catalyst comprises a support and active components, the active components being metals from Group VIB and Group VIII. The operating conditions of the hydrorefining reactor are: reaction temperature 200℃~400℃, reaction pressure 8MPa~20MPa, hydrogen-to-oil volume ratio 600:1~1200:1, and volume hourly space velocity 0.2h⁻¹. -1 ~3.0h -1 .

21. The coal tar hydrogenation treatment method according to claim 19, characterized in that, The hydrocracking catalyst contains Y-type zeolite, alumina, and at least one metal component selected from Group VIII and at least one metal component selected from Group VIB. The operating conditions of the hydrocracking reactor are: reaction temperature of 300℃~400℃, reaction pressure of 10MPa~20MPa, hydrogen-to-oil volume ratio of 200:1~800:1, and volume hourly space velocity of 0.2h⁻¹. -1 ~2.0h -1 .

22. The coal tar hydrogenation treatment method according to claim 19, characterized in that, Operating conditions for the refining fractionation column: reaction temperature 200℃~400℃, reaction pressure 8MPa~20MPa, hydrogen-to-oil volume ratio 600:1~1200:1, volume hourly space velocity 0.2h⁻¹ -1 ~3.0h -1 .

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