Coal tar two-stage hydrotreating device and method

Abstract

The present invention discloses a coal tar two-stage hydroprocessing device and method, the device comprises: a hydrofining reactor, which receives pretreated coal tar as a first liquid phase feed, the first liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top; the first gas phase product after the hydrogenation reaction is discharged from the top of the reactor from an independent gas phase channel, and the first liquid phase product of the reactor flows to the bottom; a hydrocracking reactor, which has the same internal structure as the hydrofining reactor, and receives part of the first liquid phase product of the hydrofining reactor as the second liquid phase feed of the hydrocracking reactor, and generates a second gas phase product discharged from the top and a second liquid phase product flowing to the bottom after the hydrogenation reaction. The present invention can effectively solve the problem of timely separation of the gas phase reaction product of the hydrofining / cracking reactor from the reaction zone, and can improve the properties of the hydrofining feed, reduce the reaction temperature rise of the hydrofining, reduce the difficulty of the reaction, and can also adapt to feedstock oil with worse conditions under the same conditions.

Description

Technical Field

[0001] The invention relates to the field of hydrogenation reaction, and in particular to a coal tar two-stage hydrogenation processing device and method. Background Art

[0002] Coal tar is one of the liquid products obtained during the distillation and gasification of coal. It is a black or dark brown viscous liquid with a pungent odor at room temperature. It is mainly composed of polycyclic aromatic compounds. The composition of coal tar is extremely complex. According to the different cracking temperatures, it can be divided into several different products such as low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar. By processing coal tar by hydrogenation, high-value-added low-sulfur naphtha and clean fuel oil can be obtained. The cleanliness and lightness of coal tar can not only effectively supplement the shortage of petroleum resources, but also efficiently utilize coal resources, solving the problems of low comprehensive utilization of resources and environmental pollution that have long plagued my country's coking industry.

[0003] However, since coal tar itself contains a large amount of oxygen-containing polar substances and a certain amount of unsaturated hydrocarbons and impurities such as sulfur, nitrogen and metals. At the same time, coal tar contains a large number of special substances such as fine inorganic impurities and organic impurities. It is difficult to process coal tar fractions or whole fractions using conventional fixed beds, fluidized beds and suspended beds. For example, fixed beds are prone to solid matter blocking the bed layer; a large amount of heat is released during the hydrogenation process, causing the bed layer to overheat and causing "hot spots" to appear in the bed layer. During the hydrogenation reaction, after polar substances such as oxygen are subjected to hydrogenation and deoxygenation reactions, fine impurities are released and are easily deposited in the reactor bed. At the same time, the conventional heavy oil fixed bed catalyst loading scheme follows the flow direction of the reactants, and the catalyst pore size becomes smaller and smaller, which can easily cause the reactor bed to be blocked, especially the reaction bed position where impurities are released after deoxygenation is more likely to be blocked, affecting the long-term stable operation of the entire reaction device.

[0004] More importantly, the gaseous products (H2O, H2S, NH4, etc.) and unreacted hydrogen feed generated by the hydrofining reaction in the hydrofining / cracking reactor in the prior art will still be retained in the catalyst bed and in contact with the catalyst, which will have an adverse effect on the catalyst activity; at the same time, since the hydrogenation reaction is an exothermic reaction, the retention of the gaseous products cannot take away most of the reaction heat in time, which will increase the consumption of hydrogen. In addition, the existing single hydrofining / cracking reactor is difficult to adapt to crude oil with harsh conditions.

[0005] Therefore, there is an urgent need for a two-stage coal tar hydroprocessing device, which can effectively solve the problem of timely separation of the gas phase reaction products of the hydrotreating / cracking reactor from the reaction zone, while improving the properties of the hydrotreating feed, reducing the reaction temperature rise of the hydrotreating, reducing the difficulty of the reaction, and adapting to feedstocks with more severe conditions under the same conditions.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a coal tar two-stage hydroprocessing device and method, which can effectively solve the problem of timely separation of the gas phase reaction products of the hydrotreating / cracking reactor from the reaction zone, and can also improve the properties of the hydrotreating feed, reduce the reaction temperature rise of the hydrotreating, reduce the difficulty of the reaction, and can adapt to feedstock oil with more severe conditions under the same conditions.

[0008] To achieve the above-mentioned purpose, according to the first aspect of the present invention, there is provided a two-stage coal tar hydroprocessing device, comprising: a hydrofining reactor, which receives pretreated coal tar as a first liquid feed, and the first liquid feed flows through each catalyst bed layer in sequence from top to bottom; hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top; the first gas phase product after the hydrogenation reaction is discharged from the top of the reactor from an independent gas phase channel, and the first liquid phase product of the reactor flows to the bottom; a hydrocracking reactor, which has the same internal structure as the hydrofining reactor, and receives part of the first liquid phase product of the hydrofining reactor as the second liquid phase feed of the hydrocracking reactor, and generates a second gas phase product discharged from the top and a second liquid phase product flowing to the bottom after the hydrogenation reaction.

[0009] Furthermore, in the above technical scheme, both the hydrotreating reactor and the hydrocracking reactor may include: a catalyst bed, which is used to fill a solid catalyst, and each catalyst bed has an inclined surface on the upper part of the solid catalyst filled; a liquid feed subunit, which is arranged above the inclined surface of the topmost catalyst bed, and the liquid feed is guided to the catalyst bed through the inclined surface; a hydrogen feed subunit, which is arranged between the inclined surface of the catalyst bed of the upper layer and the lower layer, and the hydrogen feed of each layer enters the catalyst bed upward; an independent gas phase channel, which is in a relatively isolated state from the hydrogen feed subunit, and the gas phase product generated after the hydrogen and liquid phase feed react in the catalyst bed directly enters the gas phase channel.

[0010] Furthermore, in the above technical solution, the entire inclined surface can be an umbrella-shaped partition structure.

[0011] Furthermore, in the above technical solution, an annular downcomer may be provided at the end of the umbrella-shaped partition, and the bottom of the downcomer is spaced a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed in a radial direction.

[0012] Furthermore, in the above technical solution, the catalyst bed may be provided with: an overflow weir, which is arranged on the side close to the gas phase channel; and a liquid sealing baffle, which is arranged on the upper part of the overflow weir to isolate hydrogen from the gas phase product.

[0013] Furthermore, in the above technical solution, the liquid seal baffle may include: a horizontal portion, which is an annular flat plate and is located above the overflow weir; a vertical portion, which is cylindrical and is integrally formed with the horizontal portion, and the lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed.

[0014] Furthermore, in the above technical scheme, the liquid-phase feed subunit may further include: a liquid-phase feed pipe, which extends along the radial direction of the hydrotreating reactor or the hydrocracking reactor; a liquid-phase distribution pipe, which is annular and intersects orthogonally or tangentially with the liquid-phase feed pipe, and the pipe wall of the liquid-phase distribution pipe is provided with a plurality of channels for evenly distributing the liquid-phase feed to all directions of the annular downcomer.

[0015] Furthermore, in the above technical solution, the hydrogen feed subunit may further include: a hydrogen feed pipe, which extends along the radial direction of the hydrotreating reactor or the hydrocracking reactor; a hydrogen distribution pipe, which is in the form of a ring or a plurality of concentric rings, and the hydrogen distribution pipe intersects the hydrogen feed pipe orthogonally or tangentially, and a plurality of holes are provided on the wall of the hydrogen distribution pipe for evenly distributing the hydrogen feed to all directions at the bottom of the catalyst bed.

[0016] Furthermore, in the above technical solution, the hydrogen feeding subunit may also include: a hydrogen distribution plate, which is located at the bottom of the catalyst bed and is disk-shaped as a whole, and a plurality of holes are evenly and densely distributed on the hydrogen distribution plate.

[0017] Furthermore, in the above technical solution, the gas phase channel may be located in the middle of the hydrotreating reactor or the hydrocracking reactor, and penetrate all catalyst beds from bottom to top.

[0018] Furthermore, in the above technical solution, the hydrogen distribution pipe can be arranged below the catalyst bed or inside the catalyst bed.

[0019] Furthermore, in the above technical solution, the number of catalyst beds in the hydrotreating reactor is two or more; each catalyst bed is filled with a hydrotreating catalyst, or the upper layer is filled with a hydrotreating catalyst and the lower layer is filled with a hydrocracking catalyst.

[0020] Furthermore, in the above technical solution, the number of catalyst beds in the hydrocracking reactor is two or more; each catalyst bed is filled with hydrocracking catalyst, or the upper or middle layer is filled with hydrorefining catalyst, and the other beds are filled with hydrocracking catalyst.

[0021] Furthermore, in the above technical solution, the liquid product after the reaction in the hydrotreating reactor or the hydrocracking reactor flows to the bottom of the reactor, and a liquid level monitoring unit is provided at the bottom, and the discharge is stopped when the liquid level is lower than the set value.

[0022] Furthermore, in the above technical scheme, the coal tar two-stage hydroprocessing device of the present invention may also include: a pre-fractionation tower, which fractionates the pretreated coal tar and obtains light components, and uses the light components as the first liquid phase feed; a high-pressure separator, which receives the first gas phase product, the second gas phase product and the hydrogen that has not completed the reaction, and separates high-fraction gas and high-fraction oil, and the high-fraction gas is returned to the hydrotreating reactor and / or the hydrocracking reactor for reuse after purification; a low-pressure separator, which receives the second liquid phase product from the bottom of the hydrocracking reactor and the high-fraction oil from the high-pressure separator, and separates low-fraction gas and low-fraction oil; a fractionation tower, which fractionates the low-fraction oil into a clean fuel oil product.

[0023] To achieve the above-mentioned purpose, according to the second aspect of the present invention, there is provided a two-stage coal tar hydrogenation treatment method, comprising the following steps: using the pretreated coal tar as the first liquid phase feed for hydrogenation refining, the first liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; hydrogen enters uniformly from the bottom to top from the bottom of each catalyst bed layer; the first gas phase product after the hydrogenation reaction is discharged from the top of the reactor through an independent gas phase channel, and the first liquid phase product of the reactor flows to the bottom; using part of the first liquid phase product as the second liquid phase feed for hydrocracking, the second liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top; the second gas phase product after the hydrogenation reaction is discharged from the top of the reactor through an independent gas phase channel, and the second liquid phase product of the reactor flows to the bottom.

[0024] Furthermore, in the above technical solution, the method of the present invention may also include the following steps: fractionating the pretreated coal tar and obtaining light components before hydrofining.

[0025] Furthermore, in the above technical scheme, the method of the present invention may also include the following steps: after hydrofining and hydrocracking, separating the first gas phase product, the second gas phase product and the hydrogen that has not completed the reaction into high-fraction gas and high-fraction oil, and returning the high-fraction gas to the hydrofining and / or hydrocracking process for reuse after purification; separating the second liquid phase product and the high-fraction oil into low-fraction gas and low-fraction oil; and distilling the low-fraction oil into a clean fuel oil product.

[0026] Furthermore, in the above technical solution, the clean fuel oil product may include naphtha and diesel.

[0027] Furthermore, in the above technical solution, the operating conditions of the hydrofining reaction can be: reaction temperature of 300°C to 430°C, reaction pressure of 3MPa to 15MPa, hydrogen-oil volume ratio of 200:1 to 1500:1, volume space velocity of 0.2h -1 ~2.0h -1 .

[0028] Furthermore, in the above technical solution, the operating conditions of the hydrocracking reaction can be: reaction temperature of 330°C to 450°C, reaction pressure of 3MPa to 15MPa, hydrogen-oil volume ratio of 400:1 to 1500:1, volume space velocity of 0.2h -1 ~2.0h -1 .

[0029] Furthermore, in the above technical solution, the coal tar can be at least one of low temperature coal tar, medium temperature coal tar, and medium and low temperature coal tar. The purity of hydrogen can be 99.9%.

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

[0031] 1) The present invention adopts two-stage reactors in series, and adds hydrofining / cracking liquid product reflux, which can improve the properties of hydrofining feed, reduce the reaction temperature rise of hydrofining, and reduce its reaction difficulty. Under the same conditions, it can adapt to crude oil with more severe conditions, and adopt the two-stage hydrotreatment of the present invention, and no pre-fractionation process can be performed before hydrofining. At the same time, the loading combination of the catalyst can be more flexible. When one of the reactors fails or needs to be shut down for maintenance, the other reactor can also work independently to avoid shutdowns caused by emergencies and improve the adaptability of long-term operation.

[0032] 2) In the hydrofining / cracking reactor of the present invention, the gaseous products such as H2O, H2S, NH4, etc. generated after the reactants undergo chemical reactions in the catalyst bed will leave the reaction zone in time and will not re-enter the upper catalyst bed, that is, they will not contact the hydrofining / cracking catalyst bed, thereby reducing their adverse effects on the catalyst activity, effectively avoiding catalyst poisoning caused by them, and extending the service life of the catalyst; effectively avoiding the secondary reaction of the target product and improving the selectivity of the reaction; at the same time, due to the departure of the gaseous products in the reaction zone, the driving force of the reaction is increased and the equilibrium conversion rate is improved; in addition, the timely separation of the gaseous products can take away most of the reaction heat, reducing the consumption of hydrogen; and it is beneficial to promote the reaction to the right, thereby improving the removal rate of sulfur and nitrogen in the feed oil and the yield of the target product;

[0033] 3) The liquid feed of the hydrofining / cracking reactor of the present invention can flow through each catalyst bed layer from top to bottom in sequence, and hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top, forming a countercurrent contact between the hydrogenation catalyst bed layer and the hydrogen flowing upward from the bottom of the catalyst bed layer, which will not cause the catalyst stacking density to increase, and can effectively reduce the pressure drop of the hydrofining / cracking reactor bed layer;

[0034] 4) The umbrella-shaped baffles in the hydrotreating / cracking reactor can separate the hydrogen feed and gaseous products between adjacent beds on the one hand, and play a guiding role for the liquid and gas phases on the other hand; the liquid seal baffle can effectively isolate the hydrogen feed and gaseous products; the setting of multiple concentric annular hydrogen distribution pipes can keep the distribution of hydrogen feed uniform to the maximum extent;

[0035] 5) The catalyst bed of the hydrorefining / cracking reactor of the present invention can be filled with a hydrorefining catalyst in the upper layer and a hydrocracking catalyst in the lower layer. Since the hydrorefining / cracking catalyst is loaded at the same time, the dual purposes of refining and cracking can be achieved, the investment cost can be reduced, the process flow can be simplified, and high value-added clean fuel oil can be produced.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a process flow chart of a coal tar two-stage hydrotreating device according to the present invention;

[0038] Figure 2 It is a schematic diagram of the internal structure of the hydrotreating / cracking reactor of the present invention.

[0039] Figure 3 It is a top view of the liquid phase distribution pipe in the hydrotreating / cracking reactor of the present invention.

[0040] Figure 4 It is a top view of the hydrogen feed pipe and the hydrogen distribution pipe in the hydrotreating / cracking reactor of the present invention (showing the situation where the hydrogen feed pipe and the annular hydrogen distribution pipe are arranged orthogonally).

[0041] Figure 5 It is another top view of the hydrogen feed pipe and the hydrogen distribution pipe in the hydrotreating / cracking reactor of the present invention (showing the situation where the hydrogen feed pipe and the annular hydrogen distribution pipe are arranged to intersect tangentially).

[0042] Figure 6 It is a top view of the hydrogen distribution pipe of the present invention which adopts a concentric double-ring distribution pipe.

[0043] Figure 7 It is a top view of the hydrogen distribution plate in the hydrotreating / cracking reactor of the present invention.

[0044] Figure 8 It is a top view of the catalyst support plate in the hydrotreating / cracking reactor of the present invention.

[0045] Description of main reference numerals:

[0046] 1-hydrofining / cracking reactor, 1A-hydrofining reactor, 1B-hydrocracking reactor, 10-solid catalyst, 11-umbrella-shaped baffle, 12-outer downcomer, 13-gas phase channel, 14-overflow weir, 15-downcomer folding plate, 16-liquid receiving tray, 17-liquid sealing baffle, 18-inner downcomer, 19-catalyst support plate, 191-grid;

[0047] 21-liquid phase feed pipe, 22-liquid phase distribution pipe, 220-liquid phase distribution pipe body, 221-liquid phase channel;

[0048] 31-hydrogen feed pipe, 32-hydrogen distribution pipe, 320-hydrogen distribution pipe body, 321-hydrogen channel, 33-hydrogen distribution plate, 331-hole, 34-liquid product;

[0049] 100-pre-fractionation tower, 200-high-pressure separator, 201-heat exchanger, 202-sulfur and nitrogen purifier, 300-low-pressure separator, 400-fractionation tower; L1-coal tar feedstock, L2-hydrogenation refining reactor feed, L3-hydrocracking reactor feed, L4-hydrogenation conversion high-fraction oil, L41-second liquid phase product, L5-hydrogenation conversion low-fraction oil, L6-naphtha, L7-diesel, L31-unconverted oil, L8-high-fraction wastewater, L9-low-fraction wastewater, L10-heavy oil fraction, Q1-hydrogen, Q21-first gas phase product, Q22-second gas phase product, Q3-high-fraction gas, Q4-low-fraction gas. DETAILED DESCRIPTION

[0050] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0051] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0052] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0053] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0054] like Figure 1As shown, the coal tar two-stage hydroprocessing device of the present invention includes a pre-fractionation tower 100, a hydrofining / cracking reactor 1 (including a hydrofining reactor 1A and a hydrocracking reactor 1B), a high-pressure separator 200, a low-pressure separator 300 and a fractionation tower 400. The present invention connects the hydrofining reactor 1A and the hydrocracking reactor 1B in series, and the two reactors have the same internal structure, and can perform two-stage hydroprocessing. The process is as follows: after the coal tar is pre-treated by dehydration and impurity removal, it enters the pre-fractionation tower 100 for fractionation to obtain the light component, and the light component enters the hydrofining reactor 1A. Through the liquid phase distribution, the first liquid phase feed L2 can be evenly distributed to all directions of the annular downcomer, and at the same time, the hydrogen Q1 enters the bottom of each catalyst bed in the reactor from the side wall of the reactor. Under the action of the hydrogen distributor in the reactor, the hydrogen feed is evenly distributed to all directions at the bottom of the catalyst bed. Each bed of the hydrotreating reactor 1A is filled with a hydrotreating catalyst, and the first liquid feed L2 and the hydrogen feed Q1 enter the catalyst bed from the top and bottom of the catalyst bed respectively, and countercurrently contact to carry out a hydrotreating reaction. The first liquid feed L2 passes through all the catalyst beds in sequence to obtain a hydrogenated distillate oil (i.e., a first liquid product), a part of which is returned to the inlet of the hydrotreating reactor 1A, and the other part is sent to the hydrocracking reactor 1B through a pipeline as the feed L3 (i.e., the second liquid feed) of the hydrocracking reactor. The second liquid feed L3 can be evenly distributed to all directions of the annular downcomer through liquid phase distribution. At the same time, hydrogen Q1 enters the bottom of the catalyst bed in the reactor from the side wall of the reactor, and under the action of the reactor hydrogen distributor, the hydrogen feed is evenly distributed to all directions at the bottom of the catalyst bed. Each bed in the hydrocracking reactor 1B is filled with a hydrocracking catalyst, and the second liquid phase feed L3 and the hydrogen feed Q1 enter the catalyst bed from the top and bottom of the catalyst bed respectively, and perform a hydrocracking reaction in countercurrent contact.The second liquid phase feed L3 passes through all the catalyst beds in sequence to obtain the hydrogenated distillate oil (i.e., the second liquid phase product), a part of which is returned to the inlet of the hydrofining reactor 1A, and the other part is sent to the low-pressure separator 300 via a pipeline; and the first gas phase product Q21, the second gas phase product Q22 and the unreacted hydrogen generated after the hydrogenation reaction of the catalyst beds in the hydrofining reactor 1A and the hydrocracking reactor 1B directly enter the independent gas phase channel of the present invention, and are discharged at the top of the hydrofining reactor 1A / hydrocracking reactor 1B, and enter the high-pressure separator 200 via a pipeline; the first gas phase product Q21, the second gas phase product Q22 and the unreacted hydrogen generated after the hydrogenation reaction of the catalyst beds in the hydrofining reactor 1A and the hydrocracking reactor 1B directly enter the independent gas phase channel of the present invention, and are discharged at the top of the hydrofining reactor 1A / hydrocracking reactor 1B, and enter the high-pressure separator 200 via a pipeline; the first gas phase product Q21, the second gas phase product Q22 and the unreacted hydrogen Product Q22 is passed through the high-pressure separator 200 to obtain high-fraction gas Q3, high-fraction oil L4, and sulfur-containing wastewater L8. The high-fraction gas Q3 is purified by the sulfur-nitrogen purifier 202 and returned to the hydrotreating / cracking reactor for reuse. The high-fraction oil L4 enters the low-pressure separator 300 through a pipeline. The liquid phase product of the hydrocracking reactor 1B (i.e., the second liquid phase product L41) and the high-fraction oil L4 are separated in the low-pressure separator 300 to obtain low-fraction gas Q4, low-fraction oil L5, and sulfur-containing wastewater L9. The low-fraction oil L5 continues to enter the distillation tower 400 for further separation to obtain clean fuel oil products such as naphtha L6 and diesel L7. The unconverted oil L31 is returned to the inlet of the hydrocracking reactor 1B.

[0055] The present invention adopts two-stage reactors in series, and adds hydrofining / cracking liquid product reflux, which can improve the properties of hydrofining feed, reduce the reaction temperature rise of hydrofining, and reduce its reaction difficulty. Under the same conditions, it can adapt to crude oil with more severe conditions, and adopt the two-stage method of the present invention for hydrofining, and no pre-fractionation process can be performed before hydrofining. At the same time, the loading combination of the catalyst can be more flexible. When one of the reactors fails or needs to be shut down for maintenance, the other reactor can also work independently to avoid shutdowns caused by emergencies and improve the adaptability of long-term operation.

[0056] Further Figure 2 As shown, the hydrotreating / cracking reactor 1 of the present invention includes a catalyst bed, a liquid-phase feed subunit, a hydrogen feed subunit, and an independent gas-phase channel located in the middle of the reactor. The catalyst bed is used to fill the solid catalyst 10, and an inclined surface is provided on the upper part of the solid catalyst 10 filled in each catalyst bed. The overall shape formed by the inclined surface can be umbrella-shaped, which acts as a partition. On the one hand, it can separate the hydrogen feed and the product gas between adjacent beds, and on the other hand, it plays a role in guiding the liquid phase and the gas phase. Preferably, but not restrictively, the umbrella surface can be arc-shaped or folding umbrella-shaped. The liquid-phase feed subunit is arranged on the inclined surface of the topmost catalyst bed (i.e., the umbrella-shaped partition 11). The liquid-phase feed is guided to the catalyst bed through the inclined surface of the umbrella-shaped partition 11 to contact with the solid catalyst 10. Specifically, an annular outer downcomer 12 (i.e., Figure 2The outer downcomer 12 is provided with a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed along the radial direction of the hydrorefining / cracking reactor 1. The hydrogen feed subunit is provided in each catalyst bed, specifically between the catalyst bed of the upper layer and the umbrella-shaped partition 11 of the lower layer (i.e., the bottom of each catalyst bed), and the hydrogen feed of each layer enters the catalyst bed from bottom to top. After the gas-liquid phase feed and the solid catalyst 10 are fully reacted in the catalyst bed, the gas phase product of each layer is guided to the gas phase channel 13 along the lower part of the umbrella-shaped partition 11. The gas phase channel 13 is in a relatively isolated state from the hydrogen feed subunit, that is, the gas phase product generated after the hydrogen feed and the liquid phase feed react in the catalyst bed directly and timely enters the gas phase channel 13, so that the gas phase product can also leave the catalyst bed in time. Preferably, but not limiting, the gas phase channel 13 is located in the middle of the hydrotreating / cracking reactor 1 and passes through all catalyst beds from bottom to top.

[0057] Further Figure 2 , 3 As shown, the liquid-phase feed subunit further includes a liquid-phase feed pipe 21 and a liquid-phase distribution pipe 22. The liquid-phase feed pipe 21 extends in the radial direction of the hydrofining / cracking reactor, and the liquid-phase distribution pipe 22 is annular. The liquid-phase feed pipe 21 intersects orthogonally or tangentially with the pipe body 220 of the liquid-phase distribution pipe 22. The pipe wall of the liquid-phase distribution pipe 22 is provided with a plurality of channels 221 for evenly distributing the liquid-phase feed to all directions of the annular outer downcomer 12. The openings of the channels 221 can be in all directions on the upper, lower and side surfaces of the pipe body. The liquid-phase feed enters the hydrofining / cracking reactor 1 through the liquid-phase feed pipe 21, is distributed into the reactor through the annular liquid-phase distribution pipe 22, flows into the outer downcomer 12 toward the periphery through the umbrella-shaped partition 11, and enters the catalyst bed laterally after passing through the outer downcomer 12 to contact the solid catalyst 10. The feeding direction of the liquid phase feed pipe 21 is the radial direction of the hydrofining / cracking reactor, and is orthogonal or tangential to the radial direction of the annular liquid phase distribution pipe 22. The annular diameter of the annular liquid phase distribution pipe 22 is larger than the outer diameter of the gas phase channel 13, and smaller than the inner diameter of the hydrofining / cracking reactor 1. The several holes on the wall of the annular liquid phase distribution pipe 22 facilitate the uniform distribution of the liquid phase feed in all directions of the outer downcomer 12. The height of the downcomer fold 15 is generally smaller than the catalyst loading height of this layer, and the distance between the downcomer fold 15 and the inner wall of the hydrofining / cracking reactor 1 is determined according to the flow rate of the liquid phase reactants in this layer.

[0058] By using the two-stage hydrotreating / cracking reactor of the present invention, the liquid feed can flow through each catalyst bed layer from top to bottom in sequence, and hydrogen can enter uniformly from bottom to top from the bottom of each catalyst bed layer, forming a countercurrent contact between the hydrogenation catalyst bed layer and the hydrogen flowing upward from the bottom of the catalyst bed layer, which can effectively reduce the pressure drop of the hydrotreating / cracking reactor bed layer.

[0059] Further Figure 2 As shown, the catalyst bed is fixed with a screen to keep the bed relatively stable, and the bed height is set to 10mm to 1000mm. The catalyst bed is provided with an overflow weir 14 and a liquid-sealed baffle 17, and the overflow weir 14 is arranged on the side close to the gas phase channel 13. The liquid-sealed baffle 17 is arranged on the upper part of the overflow weir 14 to isolate the hydrogen feed from the gas phase product. Furthermore, the liquid-sealed baffle 17 includes a horizontal portion and a vertical portion, the horizontal portion is an annular flat plate and is located above the overflow weir 14; the vertical portion is cylindrical, and the vertical portion is integrally formed with the horizontal portion, and other seamless connection methods can also be used. The lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed to ensure the outflow of the liquid phase product. The unreacted liquid feed and the reacted but liquid-phase materials in the catalyst bed pass through the overflow weir 14, through the inner downcomer 18 (i.e., the annular space between the overflow weir 14 and the outer wall of the gas phase channel 13), along the umbrella-shaped partition 11, and through the outer downcomer 12 of the next layer into the next catalyst bed. The height of the overflow weir 14 is higher than the upper plane of the catalyst in the current bed, preferably 10 to 100 mm higher. The annular inner downcomer 18 formed between the overflow weir 14 and the outer wall of the gas phase channel 13 has a spacing size determined by the size of the liquid phase load, and the size of the downcomers of each bed can be the same or different.

[0060] Further Figure 2 , 4 As shown in Figures 6 to 7, the hydrogen feed subunit includes a hydrogen feed pipe 31 and a hydrogen distribution pipe 32. The hydrogen feed pipe 31 extends in the radial direction of the hydrofining / cracking reactor 1. The hydrogen distribution pipe 32 is annular (see Figure 4 , 5 ) or multiple layers of concentric rings (see Figure 6 The hydrogen feed pipe 31 is orthogonal to the pipe body 320 of the hydrogen distribution pipe 32 (see Figure 4 ) or tangential intersection (see Figure 5 ), a plurality of holes 321 are provided on the wall of the hydrogen distribution pipe 32, which are used to evenly distribute the hydrogen feed to all directions at the bottom of the catalyst bed. Preferably, but not limiting, the hydrogen distribution pipe 32 can be arranged below the catalyst bed, or can be arranged inside the catalyst bed. Figure 7As shown, the hydrogen feed subunit further includes a hydrogen distribution plate 33, which is located at the bottom of the catalyst bed and is in the shape of a plate as a whole, and the hydrogen distribution plate is evenly and densely distributed with a plurality of holes 331. The hydrogen feed enters the hydrofining / cracking reactor 1 through the hydrogen feed pipes 31 of each layer, is distributed into the hydrofining / cracking reactor 1 through the annular hydrogen distribution pipe 32, and enters the catalyst bed upward through the hydrogen distribution plate 33 at the lower part of the catalyst support plate 19. The hydrogen feed pipe 31 enters the hydrofining / cracking reactor 1 in a radial direction, and intersects orthogonally or tangentially with the annular hydrogen distribution pipe 32. The annular hydrogen distribution pipe 32 is located below the catalyst bed, and the annular diameter of the annular hydrogen distribution pipe 32 is smaller than the outer ring diameter of the catalyst bed, and the inner diameter is larger than the inner ring diameter of the catalyst bed. The plurality of channels 321 on the wall of the annular hydrogen distribution pipe 32 facilitate the uniform distribution of the gas at various positions of the hydrogen distribution plate 33. The function of the catalyst support plate 19 is mainly to support the catalyst bed and ensure that the catalyst bed remains stable in the axial direction of the hydrofining / cracking reactor. The function of the hydrogen distribution plate 33 is to ensure the uniform distribution of the hydrogen feed and to avoid the direct leakage of the liquid feed on the catalyst bed as much as possible (using the hydrogen distribution plate 33 of the present invention, the liquid leakage is <15%). On the same plane, when more than one concentric annular hydrogen distribution pipe 32 of different diameters is set, the distribution of the hydrogen feed can be more uniform. Figure 2 In the embodiment of the present invention, the annular hydrogen distribution pipe 32 is arranged below the catalyst bed. When the annular hydrogen distribution pipe 32 is installed in the catalyst bed, the catalyst support plate 19 can Figure 8 The grid 191 is changed into a support plate, and the hydrogen distribution plate 33 is cancelled.

[0061] In addition to the downcomers, overflow weirs and liquid receiving trays on each tray of the hydrofining / cracking reactor of the present invention, a liquid seal baffle is also provided on the tray, which is connected to the gas phase channel. Adjacent trays are separated by umbrella-shaped partitions. Each tray is an annular structure, the inner edge of the annular ring is connected to the gas phase channel, and the outer edge is connected to the inner wall of the hydrofining / cracking reactor. The gas phase channel is a common channel for removing gas phase products generated by chemical reactions on each tray. In the embodiment of the present invention, the liquid feed positions are all on the upper part of a tray, and liquid feed can also be provided on some trays or each tray, and hydrogen feed is provided at the lower part of each tray. Above each tray is a catalyst loading area, and the liquid feed flows radially through the catalyst bed. The hydrogen feed enters from the bottom of the tray and reacts under the action of the catalyst. The gas phase material generated after the reaction directly leaves the reaction system and enters the gas phase channel in the middle. After the liquid phase leaves the bed, it enters the next bed through the downcomer. Since the reaction and separation are carried out simultaneously, the reaction equilibrium can be destroyed, effectively improving the conversion rate of the reactants and the selectivity of the target products.

[0062] Furthermore, the hydrotreating reactor 1A may be provided with a plurality of catalyst beds, and the hydrotreating catalyst beds may be filled with hydrotreating catalysts from top to bottom, or may be filled with hydrotreating catalysts in the upper layer and hydrocracking catalysts in the lower layer. Preferably, but not restrictively, the volume ratio of the hydrotreating catalyst to the hydrocracking catalyst is 1:1 to 10:1. The porosity of the catalyst bed of the hydrotreating reactor 1A is 0.5% to 85%, preferably 1% to 20%. By loading two different types of catalysts in the hydrotreating reactor, the feedstock oil can be desulfurized and denitrogenated, and after appropriate cracking, the feedstock oil can be converted into a clean medium molecular distillate oil. In the hydrogenation reactor, aromatic hydrocarbons and long-chain macromolecular hydrocarbons are saturated or cracked to generate cycloalkanes and short-chain small molecular hydrocarbons, respectively, to achieve the purpose of upgrading.

[0063] Furthermore, the hydrocracking reactor 1B may also be provided with a plurality of catalyst beds, and the hydrocracking catalyst beds may be filled with hydrocracking catalysts from top to bottom, or may be filled with hydrorefining catalysts in the upper layer or the middle layer, and hydrocracking catalysts in the lower layer. Preferably, but not restrictively, the volume ratio of the hydrorefining catalyst to the hydrocracking catalyst is 1:5 to 1:50. The porosity of the catalyst bed of the hydrocracking reactor 1B is 0.5% to 85%, preferably 1% to 20%. By loading two different types of catalysts in the hydrocracking reactor, the liquid phase raw material can also be further desulfurized and denitrogenated, and after moderate cracking, the raw material oil can be converted into a clean medium molecular distillate oil. In the hydrogenation reactor, aromatic hydrocarbons and long-chain macromolecular hydrocarbons are saturated or cracked to generate cycloalkanes and short-chain small molecular hydrocarbons, respectively, to achieve the purpose of upgrading.

[0064] Furthermore, the hydrorefining catalyst can be a hydrorefining catalyst with high desulfurization and denitrogenation activity and less aromatic saturation. The hydrorefining catalyst includes a carrier and an active component, and the hydrogenation active component is a metal in Group VIB and Group VIII, such as one, two or more of W, Mo, Co, and Ni, measured by the weight of the metal oxide, the total content of the metal oxide is 2wt% to 12wt%, and the content of Group VIB metal is 5wt% to 25wt% in terms of oxide. The hydrorefining catalyst can be prepared according to the existing technology, or a commercial hydrorefining catalyst can be selected. The refining catalyst can contain an additive, such as one or more of K, P, Mg, Zr and Ca, the content of Group VIII metal is 3wt% to 10wt% in terms of oxide, and the content of Group VIB metal is 6wt% to 30wt% in terms of oxide.

[0065] Furthermore, 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. In the above two catalysts, the metals of Group VIB are selected from molybdenum and / or tungsten, and the metals of Group VIII are selected from cobalt and / or nickel. The metal composition is calculated by weight percentage: 10% to 30% tungsten oxide, 5% to 15% nickel oxide, and may contain a certain amount of molecular sieves, such as one or two of Y-type molecular sieves and β molecular sieves, generally containing 1% to 30% molecular sieves, and the rest are refractory tungsten oxide carriers such as amorphous silicon aluminum, silicon-containing aluminum oxide, and aluminum oxide. The catalyst pore volume is 0.10 to 0.50 ml / g, and the specific surface area is 120 to 350 m 2 / g. The hydrocracking catalyst is preferably a porous catalyst, a shaped catalyst and / or a honeycomb catalyst. The porous catalyst has a pore diameter of 1 to 50 mm, preferably 4 to 20 mm; the average particle diameter of the shaped catalyst is 2 to 50 mm, preferably 4 to 30 mm; the pore diameter or pore side length of the honeycomb catalyst is 1 to 50 mm, preferably 3 to 15 mm.

[0066] Furthermore, the reaction temperature of the hydrotreating reactor is 300°C to 430°C, the reaction pressure is 3MPa to 20MPa, the hydrogen-oil volume ratio is 200:1 to 1500:1, and the volume space velocity is 0.2h -1 ~2.0h -1 The proportion of the first liquid phase product after hydrotreating returning to the inlet of the hydrotreating reactor is no more than 60%. The reaction temperature of the hydrocracking reactor is 330℃~450℃, the reaction pressure is 3MPa~20MPa, the hydrogen-oil volume ratio is 400:1~1500:1, and the volume space velocity is 0.2h -1 ~2.0h -1 The proportion of the second liquid phase product after hydrocracking returning to the inlet of the hydrotreating reactor is no more than 50%. The operating temperature of the high-pressure separator is 30°C to 260°C, and the reaction pressure is 3MPa to 20MPa.

[0067] After a lot of research, the inventor found that for the conventional hydrogenation process, the liquid phase amount is rapidly reduced and the gas phase amount is rapidly increased in the gas-liquid-solid three-phase reaction process, because the gas phase amount is rapidly increased, it occupies a large amount of bed gaps, so that the liquid phase flow rate is greatly increased. Although the prior art can ensure that the gas-liquid-solid three-phase contact is sufficient, the effective reaction time of the liquid phase that needs to be further converted is reduced, and the probability of contact between the gas phase that does not need to react again (such as the gas phase obtained by liquid phase conversion under reaction conditions) and the catalyst increases. For the system that requires more liquid phase conversion and gas phase control of secondary reaction, the overall reaction effect is subject to certain limitations, which is generally manifested as the reaction conversion rate, selectivity, etc. It is difficult to further improve. In the hydrofining / cracking reactor of the present invention, the liquid phase feed and hydrogen feed are catalytically reacted in the catalyst bed, and the gas phase product and the lighter reaction product (i.e., the naphtha fraction) are taken away from the reaction system upward through the gas phase channel 13 under the action of hydrogen stripping, and the heavier reaction product (i.e., the diesel fraction) enters the next catalyst bed reaction zone downward under the action of gravity.

[0068] In the hydrofining / cracking reactor of the present invention, the gaseous products generated after the reactants undergo chemical reactions in the catalyst bed will leave the reaction zone in time and will not re-enter the upper catalyst bed (isolated by the umbrella-shaped partition), thereby avoiding secondary reactions of the target products and improving the selectivity of the reaction. At the same time, due to the departure of the gaseous products in the reaction zone, the driving force of the reaction is increased and the equilibrium conversion rate is improved. In addition, the gaseous products (H2O, H2S, NH4, etc.) and unreacted gaseous feed generated by the hydrofining reaction are separated from the catalyst bed reaction system and directly leave the reactor through the gas phase channel without contacting the hydrofining / cracking catalyst bed, thereby reducing its adverse effects on the catalyst activity. At the same time, the timely departure of the gaseous products can take away most of the reaction heat and reduce the consumption of hydrogen.

[0069] Example 1

[0070] Using the present invention Figure 1 As shown in the flow chart, the raw oil is medium-low temperature coal tar, and its properties are shown in Table 1. The coal tar raw material that has been dehydrated and decontaminated first enters the pre-fractionation tower, and is often vacuum distilled and cut into coal tar light fraction and coal tar heavy fraction. The cutting point is 500°C. The light fraction after cutting is sent to the hydrotreating reactor 1A through a pipeline. The specific operating conditions of the hydrotreating reactor are shown in Table 3. The hydrotreating reactor is equipped with 10 beds in total, and the single-layer catalyst bed is 200mm high, all of which are filled with hydrotreating catalyst. The hydrotreating catalyst contains 17wt% molybdenum oxide, 5wt% nickel oxide, and the remainder is a silicon oxide carrier or an aluminum oxide carrier. The pore volume of the hydrotreating catalyst is 0.4mL / g, and the specific surface area is 185m 2 / g; the raw material is countercurrently contacted with hydrogen in the hydrogenation reactor 1A to first undergo a hydrorefining reaction, and the gaseous products (i.e., the first gaseous products) such as H2O, H2S, and NH4 generated by the reaction are separated from the catalyst bed and directly enter the gas phase channel, and the remaining liquid products (i.e., the first liquid products) pass through all the refining beds in sequence and then exit the reactor, of which 20% of the first liquid products are returned to the inlet of the hydrorefining reactor, and 80% are sent to the hydrocracking reactor 1B. The specific operating conditions of the hydrocracking reactor are shown in Table 3. The hydrocracking reactor is provided with a total of 6 beds, all of which are filled with hydrocracking catalysts, and the height of the single-layer catalyst bed is 220 mm. The hydrocracking catalyst contains 8wt% nickel oxide, 22wt% tungsten oxide, and the remainder is a silicon oxide carrier or an aluminum oxide carrier; all gas phase products (including the first gas phase product and the second gas phase product) generated by the hydrorefining / cracking reactor are discharged from the top through the gas phase channel of each reactor and enter the high-pressure separator 200 after heat exchange. The operating temperature of the high-pressure separator 200 is 85°C. The high-fraction gas Q3 is purified by the desulfurization and nitrogen purification device 202 and then mixed with new hydrogen and returned to the hydrogenation reactor. The high-fraction oil L4 is sent to the low-pressure separator 300 together with 85% of the second liquid phase product generated by the hydrocracking reactor 1B. The separated low-fraction gas Q4 is discharged upward, and the low-fraction oil L5 continues to enter the distillation tower 400 for further separation to obtain product naphtha L6 and diesel L7, and the unconverted oil at the bottom is returned to the hydrocracking reactor 1B for further conversion.

[0071] Example 2

[0072] The difference between this embodiment and embodiment 1 is that the upper 9 layers of the reaction zone in the hydrotreating reactor are filled with hydrotreating catalyst, and the lower layer is filled with hydrocracking catalyst; the operating conditions are shown in Table 3.

[0073] Example 3

[0074] The difference between this embodiment and embodiment 1 is that 40% of the first liquid phase product of hydrofining is returned to the inlet of the hydrofining reactor, 60% of the first liquid phase product is sent to the hydrocracking reactor, and 100% of the second liquid phase product of hydrocracking is sent to the low-pressure separator. The operating conditions are shown in Table 3

[0075] Comparative Example 1

[0076] The conventional fixed-bed two-stage hydrofining method is used to produce clean fuel oil;

[0077] Table 1 Properties of crude oil

[0078] project data Family composition, % data <![CDATA[Density, g / cm 3 > 1.0881 Saturation 17.1 <![CDATA[Viscosity / mm 2 / s]]> 26.8 Aroma 22.17 Sulfur content, vol% 0.19 Gel 46.01 Nitrogen content, % 0.35 Asphaltene 1.2 Carbon residue value, % 6.12 Total metal content, μg / g 115.44

[0079] Table 2 Properties of pre-distilled light fraction oil

[0080]

[0081]

[0082] Table 3 Operating conditions of embodiments and comparative examples

[0083]

[0084] Table 4 Properties of Examples and Comparative Examples

[0085]

[0086]

[0087] From the experimental results of the embodiment, it can be seen that the water generated by the reaction can be effectively discharged from the gas phase channel and then separated out in the high and low fractions, ensuring the service life of the catalyst; higher quality clean fuel oil can be obtained, and the yield of naphtha is improved compared with the traditional two-stage hydrogenation process.

[0088] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A coal tar two-stage hydroprocessing device, characterized in that: include: A hydrofining reactor receives the pretreated coal tar as a first liquid phase feed, and the first liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; Hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top; the first gas phase product after the hydrofining reaction is discharged from the top of the hydrofining reactor through an independent gas phase channel, and the first liquid phase product of the hydrofining reactor flows to the bottom; A hydrocracking reactor, which has the same internal structure as the hydrofining reactor, receives part of the first liquid phase product of the hydrofining reactor as the second liquid phase feed of the hydrocracking reactor, and generates a second gas phase product discharged from the top and a second liquid phase product flowing to the bottom after the hydrocracking reaction; The hydrofining reactor and the hydrocracking reactor both comprise: the catalyst bed, which is used to fill the solid catalyst, and has an inclined surface on the top of the solid catalyst filled in each catalyst bed; a liquid-phase feed subunit, which is arranged above the inclined surface of the topmost catalyst bed, and the liquid-phase feed is guided to the catalyst bed through the inclined surface; a hydrogen feed subunit, which is arranged between the catalyst bed of the upper layer and the inclined surface of the lower layer, and the hydrogen feed of each layer enters the catalyst bed upward; the independent gas phase channel, which is in a relatively isolated state from the hydrogen feed subunit, and the gas phase product generated after the hydrogen and liquid-phase feed react in the catalyst bed directly enters the gas phase channel; The catalyst bed is provided with: an overflow weir, which is arranged on one side close to the gas phase channel; a liquid sealing baffle, which is arranged on the upper part of the overflow weir and is used to isolate the hydrogen from the gas phase product; the liquid sealing baffle comprises: a horizontal part, which is in the shape of an annular flat plate and is located above the overflow weir; a vertical part, which is in the shape of a cylinder, the vertical part is integrally formed with the horizontal part, and the lower end of the vertical part is spaced a distance from the bottom of the catalyst bed; The gas phase channel is located in the middle of the hydrotreating reactor or the hydrocracking reactor and passes through all catalyst beds from bottom to top; The number of catalyst beds in the hydrotreating reactor and the hydrocracking reactor are both two or more.

2. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: The inclined surface is an umbrella-shaped partition structure as a whole.

3. The coal tar two-stage hydroprocessing device according to claim 2, characterized in that: An annular downcomer is disposed at the end of the umbrella-shaped partition, and the bottom of the downcomer is spaced a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed in a radial direction.

4. The coal tar two-stage hydroprocessing device according to claim 3, characterized in that: The liquid phase feeding subunit further comprises: a liquid phase feed pipe extending in the radial direction of the hydrotreating reactor or the hydrocracking reactor; The liquid phase distribution pipe is annular and intersects the liquid phase feed pipe orthogonally or tangentially. The pipe wall of the liquid phase distribution pipe is provided with multiple channels for evenly distributing the liquid phase feed to all directions of the annular downcomer.

5. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: The hydrogen feed subunit further comprises: a hydrogen feed pipe extending in the radial direction of the hydrotreating reactor or the hydrocracking reactor; The hydrogen distribution pipe is annular or multi-layered concentric annular. The hydrogen distribution pipe intersects the hydrogen feed pipe orthogonally or tangentially. A plurality of holes are arranged on the wall of the hydrogen distribution pipe for uniformly distributing the hydrogen feed to all directions at the bottom of the catalyst bed.

6. The coal tar two-stage hydroprocessing device according to claim 5, characterized in that: The hydrogen feed subunit further comprises: The hydrogen distribution plate is located at the bottom of the catalyst bed and is in the shape of a plate as a whole. A plurality of holes are evenly and densely distributed on the hydrogen distribution plate.

7. The coal tar two-stage hydroprocessing device according to claim 5, characterized in that: The hydrogen distribution pipe is arranged below the catalyst bed or in the catalyst bed.

8. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: Each catalyst bed of the hydrotreating reactor is filled with a hydrotreating catalyst, or, when the number of catalyst beds of the hydrotreating reactor is two, the upper bed is filled with a hydrotreating catalyst and the lower bed is filled with a hydrocracking catalyst.

9. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: Each catalyst bed of the hydrocracking reactor is filled with a hydrocracking catalyst, or the upper layer or the middle layer is filled with a hydrorefining catalyst and the other beds are filled with a hydrocracking catalyst.

10. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: The liquid phase product after the reaction in the hydrotreating reactor or hydrocracking reactor flows to the bottom of the reactor, and a liquid level monitoring unit is provided at the bottom. When the liquid level is lower than a set value, the discharge is stopped.

11. The coal tar two-stage hydroprocessing device according to claim 1, characterized in that: The device also includes: A pre-fractionation tower, which fractionates the pretreated coal tar to obtain light components, and uses the light components as the first liquid phase feed; A high-pressure separator receives the first gas-phase product, the second gas-phase product and the unreacted hydrogen, and separates high-fraction gas and high-fraction oil. The high-fraction gas is purified and returned to the hydrotreating reactor and / or the hydrocracking reactor; a low-pressure separator, which receives the second liquid phase product from the bottom of the hydrocracking reactor and the high-fraction oil from the high-pressure separator, and separates low-fraction gas and low-fraction oil; A fractionation tower is used to fractionate the low-fraction oil into a clean fuel oil product.

12. A two-stage coal tar hydrotreating method, characterized in that: The device as claimed in claim 1 comprises the following steps: The pretreated coal tar is used as the first liquid phase feed for hydrogenation refining, and the first liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; hydrogen gas enters uniformly from the bottom to top from the bottom of each catalyst bed layer; The first gas phase product after the hydrofining reaction is discharged from the top of the hydrofining reactor through an independent gas phase channel, and the first liquid phase product of the hydrofining reactor flows to the bottom; Using part of the first liquid phase product as the second liquid phase feed for hydrocracking, the second liquid phase feed flows through each catalyst bed layer from top to bottom in sequence; hydrogen enters uniformly from the bottom of each catalyst bed layer from bottom to top; The second gas phase product after the hydrocracking reaction is discharged from the top of the hydrocracking reactor through an independent gas phase channel, and the second liquid phase product of the hydrocracking reactor flows to the bottom.

13. The two-stage coal tar hydrotreating method according to claim 12, characterized in that: The method further comprises the following steps: before the hydrofining, the pretreated coal tar is fractionated to obtain light components.

14. The two-stage coal tar hydrotreating method according to claim 12, characterized in that: The following steps are also included: After the hydrofining and hydrocracking, the first gas phase product, the second gas phase product and the unreacted hydrogen are separated into high-fraction gas and high-fraction oil, and the high-fraction gas is returned to the hydrofining and / or hydrocracking process after being purified; Separating the second liquid phase product and the high-content oil into low-content gas and low-content oil; The low-fraction oil is fractionated to produce clean fuel oil products.

15. The two-stage coal tar hydrotreating method according to claim 14, characterized in that: The clean fuel oil products include naphtha and diesel.

16. The two-stage coal tar hydrotreating method according to claim 12, characterized in that: The operating conditions of the hydrofining reaction are: reaction temperature of 300°C to 430°C, reaction pressure of 3MPa to 15MPa, hydrogen-oil volume ratio of 200:1 to 1500:1, volume space velocity of 0.2h -1 ~2.0h -1 .

17. The two-stage coal tar hydrotreating method according to claim 12, characterized in that: The operating conditions of the hydrocracking reaction are: reaction temperature of 330°C to 450°C, reaction pressure of 3MPa to 15MPa, hydrogen-oil volume ratio of 400:1 to 1500:1, volume space velocity of 0.2h -1 ~2.0h -1 .

18. The two-stage coal tar hydrotreating method according to claim 12, characterized in that: The coal tar is low-temperature coal tar or medium-temperature coal tar.

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