A hydrocracking method

Abstract

This invention discloses a hydrocracking method. The hydrocracking method includes the following steps: mixing feedstock oil with hydrogen and then feeding the mixture into a hydrocracking pretreatment reactor for a pre-reaction; the pre-reaction effluent then enters a catalytic reactive distillation column for hydrocracking and distillation to obtain the corresponding product. This method effectively solves the problem of reaction products not being separated from the reaction zone in a timely manner, while simultaneously improving the yield of the target product and reducing the energy consumption of the equipment.

Description

Technical Field

[0001] The invention relates to the field of petrochemical industry, and in particular to a hydrocracking method. Background Art

[0002] In modern oil refining technology, the hydrocracking process is one of the most important means of lightening heavy oil. It has the characteristics of strong raw material adaptability, variable operation mode, good product quality, flexible scheme and high liquid yield. In the 1920s, Germany used lignite to produce aviation gasoline using a three-stage hydrogenation process under high temperature and high pressure; in the 1960s, the raw materials for hydrocracking were mainly light vacuum distillate oil (LVGO), light cycle oil (LCO) of catalytic cracking unit and atmospheric distillate oil (AGO), which were used to produce light and heavy naphtha and liquefied petroleum gas; in the early 1970s, vacuum distillate oil (VGO) had become the main raw material for hydrocracking, and coker gas oil (CGO) was also used as a feed component; after the 1980s, the raw materials for hydrocracking have been extended to deasphalted oil (DAO). The process flow of hydrocracking mainly includes two-stage hydrocracking with two reactors, single-stage hydrocracking with a single reactor and one-stage hydrocracking with two reactors in series. The operation modes include one-time passing of raw materials, partial circulation of tail oil, full circulation of tail oil and circulation of intermediate fractions. In 2001, UOP launched the HyCyele ​​Unicracking process, which is a leap forward compared to conventional hydrocracking. The typical characteristics of this process are that the refining and cracking reactors are connected in reverse series, and a HyCyele ​​separator / post-processor is added. The process saves investment due to the reduced design pressure. The biggest feature is that the diesel yield is significantly increased and the hydrogen consumption is reduced. The main products of the hydrocracking process are light naphtha, heavy naphtha, aviation kerosene, diesel and tail oil. Light naphtha has a high content of isomerized hydrocarbons and a high octane number. It is a high-quality clean gasoline blending component and can also be used as a raw material for hydrocarbon steam reforming to produce hydrogen or steam cracking to produce ethylene. Heavy naphtha is one of the main products of hydrocracking. It has a high potential content of aromatics and is a high-quality catalytic reforming feed component. The aviation kerosene fraction is a high-quality jet fuel, and the diesel fraction is a clean high-cetane diesel component. The tail oil fraction can be used as steam cracking raw material, and can also be isomerized and dewaxed to produce high-quality lubricant base oil.

[0003] The two-stage hydrocracking technology disclosed in US10144884B2 is a two-stage full conversion process. Its main feature is the invention of a device called a hydrocracking reactor container. This device can be divided into two parts as a whole, the upper part uses a special component to achieve gas-liquid separation, and the lower part is an ordinary trickle bed hydrogenation reactor. The equipment has two upper and lower feeds. The logistics from the front hydrocracking reactor enters the upper part for gas-liquid separation, the gas phase is separated at the top, and the liquid phase descends to the hydrocracking reactor part; the lower feed is a mixed flow of unconverted oil and circulating hydrogen, which is mixed with the liquid phase descending from the upper separation part on the catalyst bed of the hydrocracking reactor, and descends through the catalyst bed for hydrocracking reaction. The effluents at the top and bottom of the reactor container are separated by hot high separation and cold high separation, and the hydrogen is recycled; the liquid phase separated by the separator enters the fractionation tower, the top and side lines produce products, and the tail oil at the bottom of the tower is circulated.

[0004] From the development history of hydrocracking, it can be seen that the technological progress is mainly concentrated in the changes of raw materials, process flow and catalyst performance. However, the hydrocracking reactor is still a traditional and classic trickle bed reactor. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a hydrocracking method, which can effectively solve the problem that the reaction products cannot be separated from the reaction zone in time, improve the yield of the target product, and at the same time improve the hydrocracking reaction efficiency and reduce the energy consumption of the device.

[0006] The invention provides a hydrocracking method, comprising the following steps: mixing raw oil with hydrogen and then entering a hydrocracking pretreatment reactor for pre-reaction; and the pre-reaction effluent enters a catalytic reaction distillation tower for hydrocracking reaction and distillation to obtain corresponding products.

[0007] Further, in the above technical solution, the hydrocracking method comprises the following steps:

[0008] (1) The feedstock oil is mixed with hydrogen and then enters a hydrocracking pretreatment reactor to undergo a pre-reaction under hydrogenation conditions;

[0009] (2) the pre-reaction effluent of step (1) enters a catalytic reaction distillation tower; a rectification unit is disposed in the upper part of the catalytic reaction distillation tower; a catalytic reaction unit is disposed in the lower part of the catalytic reaction distillation tower;

[0010] The gas phase in the pre-reaction effluent enters the distillation unit of the catalytic reaction distillation tower for distillation; the liquid phase in the pre-reaction effluent enters the catalytic reaction unit of the catalytic reaction distillation tower for hydrocracking reaction;

[0011] (3) The gas phase in the logistics after the hydrocracking reaction in step (2) enters the distillation unit, and the liquid phase in the logistics flows out from the bottom of the catalytic reaction distillation tower to obtain the corresponding product.

[0012] Furthermore, in the above technical solution, the raw oil in step (1) includes at least one of a diesel fraction, a vacuum distillate oil (VGO) and a mixed oil thereof (including the corresponding fraction of the secondary processing product). The distillation range of the raw oil is generally within the range of 140 to 600°C. The raw oil has a sulfur content of 0.05 wt% or more, preferably 0.10 wt% to 3.00 wt%; and / or a nitrogen content of 50 μg / g or more, preferably 200 to 2000 μg / g; and / or an aromatics content of 30 wt% or more, preferably 60 wt% to 80 wt%.

[0013] Furthermore, in the above technical solution, in step (1), the raw oil is mixed with hydrogen after heat exchange; the temperature of the raw oil after heat exchange is 260-350°C.

[0014] Furthermore, in the above technical solution, at least one catalyst bed is provided in the hydrocracking pretreatment reactor in step (1); preferably, the number of catalyst beds is 1 to 4; more preferably, a quench hydrogen inlet is provided between the catalyst beds.

[0015] Furthermore, in the above technical solution, the pre-reaction in step (1) includes at least one of hydrodesulfurization, hydrodenitrogenation and hydrogenation saturation reaction.

[0016] Further, in the above technical scheme, the hydrogenation conditions of the pre-reaction in step (1) are: total pressure 2.0-20.0 MPa, average reaction temperature 330-400°C, liquid hourly volume space velocity 0.5-3.0 h -1 , hydrogen-oil volume ratio 200:1~2000:1.

[0017] Furthermore, in the above technical solution, the catalyst used in the hydrocracking pretreatment reactor in step (1) is a hydrocracking pretreatment catalyst; the catalyst can be a commercial hydrocracking pretreatment catalyst, or can be prepared according to a method known in the art. The commercial hydrocracking pretreatment catalyst is preferably an FF series hydrocracking pretreatment catalyst developed by Fushun Petrochemical Research Institute, such as FF-36.

[0018] Furthermore, in the above technical solution, the nitrogen content in the liquid phase of the pre-reaction effluent in step (1) is generally 20 to 50 μg / g.

[0019] Furthermore, in the above technical solution, the catalytic reaction distillation tower in step (2) comprises: a catalytic reaction unit and a distillation unit; the distillation unit is arranged on the upper part of the catalytic reaction unit and distills the gas phase generated by the catalytic reaction unit and the gas phase of the pre-reaction effluent in step (1).

[0020] After a lot of research, it was found that for the gas-liquid-solid three-phase reaction process in which the amount of liquid phase decreases rapidly and the amount of gas phase increases rapidly during the reaction, the rapid increase in the amount of gas phase occupies a large amount of bed space, which greatly increases the liquid phase flow rate. According to the traditional design, although the gas-liquid-solid three-phase contact can be guaranteed, the effective reaction time of the liquid phase that needs further conversion is reduced, and the probability of the gas phase that does not need to react again (such as the gas phase obtained by liquid phase conversion under reaction conditions) contacting 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. are difficult to further improve.

[0021] Through research, it is found that when the overall space velocity is similar, for the gas-liquid-solid three-phase hydrogenation reaction in which the amount of liquid phase decreases rapidly and the amount of gas phase increases rapidly during the reaction process, when hydrogen is contacted with the raw oil in a gas-liquid countercurrent manner, the generated gas phase quickly leaves the catalyst bed, the adverse effects of the generated gas phase accumulate to a small extent, and the liquid phase has a more sufficient chance to react on the catalyst, thereby overcoming the traditional understanding of the adverse effects of traditional reactors such as poor contact effect at a large aspect ratio, and achieving the effect of significantly improving the yield of the target product. At the same time, the problems of easy flooding of the countercurrent reactor and limited hydrogen-to-oil ratio are solved.

[0022] Furthermore, in the above technical solution, the catalytic reaction unit further comprises: a plurality of catalyst beds, preferably catalyst beds with a large diameter-to-height ratio, with a diameter-to-height ratio of 2 to 800, preferably 5 to 500. The diameter-to-height ratio is the ratio of the equivalent diameter of the cross-sectional area of ​​the catalyst bed to the height of the catalyst bed. The catalyst bed is used to fill the hydrocracking catalyst, and starting from the second layer, the upper part of the hydrocracking catalyst filled in each catalyst bed has an inclined surface; a liquid-phase feed subunit, which is arranged above the top first catalyst bed, and the liquid-phase feed is guided downward to the first catalyst bed; a gas-phase feed subunit, which is arranged between the catalyst bed of the upper layer and the inclined surface of the next layer, and the gas-phase feed of each layer enters the catalyst bed upward; a gas-phase channel, which is in a relatively isolated state from the gas-phase feed subunit, and the gas-phase product generated after the gas-phase feed and the liquid-phase feed react in the catalyst bed directly enters the gas-phase channel.

[0023] Furthermore, in the above technical solution, the gas phase channel can be located outside the catalytic reaction unit and be annular and penetrate all catalyst beds from bottom to top. In addition, the gas phase channel can also be arranged in the middle of the catalytic reaction unit.

[0024] Furthermore, in the above technical solution, the inclined surface as a whole can be designed as an inverted umbrella-shaped partition structure. The end of the inverted umbrella-shaped partition can be provided with an inner downcomer, the bottom of which is spaced a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed in a radial direction.

[0025] 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 the gas phase feed from the gas phase product.

[0026] 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.

[0027] Furthermore, in the above technical solution, the liquid-phase feed subunit further includes: a liquid-phase feed pipe, which extends along the radial direction of the catalytic reaction unit; a liquid-phase distribution pipe, which is annular and intersects orthogonally or tangentially with the liquid-phase feed pipe, and the tube wall of the liquid-phase distribution pipe is provided with a plurality of channels for evenly distributing the liquid-phase feed to various positions above the first catalyst bed layer.

[0028] Furthermore, in the above technical solution, the gas-phase feed subunit may further include: a gas-phase feed pipe, which extends along the radial direction of the catalytic reaction unit; a gas-phase distribution pipe, which is annular or has multiple layers of concentric rings, and the gas-phase distribution pipe intersects the gas-phase feed pipe orthogonally or tangentially, and a plurality of holes are provided on the wall of the gas-phase distribution pipe for evenly distributing the gas-phase feed to all directions at the bottom of the catalyst bed.

[0029] Furthermore, in the above technical solution, the gas phase feeding subunit may also include: a gas phase 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 gas phase distribution plate.

[0030] Furthermore, in the above technical solution, the gas phase distribution pipe can be arranged below the catalyst bed or inside the catalyst bed.

[0031] Furthermore, in the above technical solution, the distillation unit may be provided with an inert packing layer, and the rising gas phase product from the gas phase channel is distilled in the inert packing layer.

[0032] Furthermore, in the above technical solution, the inert filler layer is filled with an inert filler; the inert filler can be conventionally selected according to needs, and is preferably at least one of Raschig rings and ceramic balls.

[0033] Furthermore, in the above technical solution, a guide unit is provided between the inert filler layer and the first catalyst bed layer, and the guide unit as a whole is an inverted umbrella-shaped partition structure; the partition is a hollow structure at a position corresponding to the gas phase channel on one side close to the distillation tower wall, and an opening is provided on the side close to the middle of the distillation tower for the liquid phase heavy components descending after distillation to enter the catalytic reaction unit.

[0034] Furthermore, in the above technical solution, the catalytic reaction distillation tower can be a multi-layer plate tower structure. The number of catalyst beds in the catalytic reaction distillation tower is more than 2 layers, preferably 2 to 20 layers.

[0035] Furthermore, in the above technical solution, the catalytic reaction distillation tower is suitable for a reaction system in which at least one liquid feed and at least one gas feed undergo a chemical reaction on a hydrocracking catalyst, and at least one gas product is produced as a reaction product.

[0036] Furthermore, in the above technical solution, the hydrocracking reaction conditions of the catalytic reaction unit are: an average reaction temperature of 300-450°C, a liquid hourly volume space velocity of 0.5-3.0h -1 , hydrogen-oil volume ratio 500:1~10000:1.

[0037] Further, in the above technical solution, the catalyst for the hydrocracking reaction used in the catalytic reaction unit is a hydrocracking catalyst. The catalyst can be a commercial hydrocracking catalyst, or it can be prepared according to a method known in the art. The commercial hydrocracking catalyst is preferably a FC series hydrocracking catalyst developed by Fushun Petrochemical Research Institute, such as FC-24.

[0038] Furthermore, in the above technical solution, the distillation reaction conditions of the distillation unit are: the tower top pressure is 2.0-20.0 MPa, and the tower top temperature is 200-400°C.

[0039] Furthermore, in the above technical solution, in step (3), the reaction effluent of the distillation unit is separated into gas and liquid after heat exchange cooling, and a part of the obtained liquid phase flow is refluxed into the top of the distillation tower distillation unit, and the other part flows out of the pipeline, which is the obtained light product, such as naphtha. The weight ratio of the part refluxed into the distillation tower to the product part flowing out of the pipeline, referred to as the tower top reflux ratio, can be determined according to the product quality requirements. The tower top reflux ratio is 1:1 to 3:1.

[0040] Furthermore, in the above technical solution, the product flowing out from the bottom of the catalytic reaction distillation tower in step (3) is a heavy product, such as a diesel fraction, hydrocracking tail oil, etc.

[0041] In the hydrocracking method of the present invention, the raw oil is mixed with hydrogen after heat exchange and then enters the hydrocracking pretreatment reactor for hydrodesulfurization, hydrodenitrogenation and hydrogenation saturation reactions; the reaction effluent directly enters the catalytic reaction distillation tower, which is divided into an upper section and a lower section, the upper section is a rectification section, and the lower section is a reaction section. The gas phase in the effluent of the hydrocracking pretreatment reactor enters the fractionation section upward, and the liquid phase enters the reaction section downward to undergo hydrocracking reaction through the catalyst bed. The reaction section is provided with multiple catalyst beds, each of which is connected to a gas phase channel, and the gas phase enters the rectification section through the gas phase channel; the oil products that have not reacted or are still in the liquid phase after the reaction pass through the catalyst bed layer by layer, and the oil products that are still in the liquid phase at the bottom of the catalytic reaction distillation tower flow out of the distillation tower.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) In the present invention, a catalytic reaction distillation tower is used. After the reactants undergo a hydrocracking reaction in the catalyst bed, the gaseous products generated will leave the reaction zone in a timely manner and will not re-enter the upper catalyst bed, thereby avoiding secondary reactions of the target gaseous products and improving the selectivity of the target products.

[0044] (2) Due to the timely departure of the gas phase products in the reaction zone, the driving force of the reaction is increased and the equilibrium conversion rate is improved; the yield of the target product is high, the yield of components below C4 is low, and the hydrogen consumption is effectively reduced; the aromatic content of the top product of the catalytic reaction distillation tower used for the hydrocracking reaction is significantly increased.

[0045] (3) Compared with the conventional hydrocracking process, the present invention eliminates the need for a separate hydrocracking product fractionation system because the catalytic reaction distillation tower directly produces the product, thus significantly reducing the energy consumption of the device.

[0046] (4) The present invention conducts in-depth research on the hydrogenation reaction with rapid reduction of liquid phase and rapid increase of gas phase under reaction conditions, breaks through the long-standing design scheme in this field, proposes technical means with design parameters completely different from the prior art, proposes appropriate process flow, catalyst bed structure and other technical schemes, and achieves outstanding technical effects. When catalytic diesel is used as raw material, the naphtha yield can be increased by 50.3% and the diesel yield can be increased by 48.3%, which exceeds the expectations of those skilled in the art and breaks through the conventional cognition of solidification in this field.

[0047] The present invention arranges multiple fixed beds (especially large-diameter-to-height ratio beds) in the catalytic reaction unit of the catalytic reaction distillation tower, so that the lighter part can be directly taken out and no longer enters the hydrocracking reaction zone to participate in the hydrocracking reaction. At the same time, the design of the liquid phase distribution pipe allows the heavy components entering the hydrocracking reaction zone to be distributed more evenly, solving the problem of poor contact of reactants on the catalyst bed at a large height-to-diameter ratio in traditional reactors. By using the reactor of the present invention, under the same process conditions and product index requirements, the void ratio of the reactor of the present invention can be smaller.

[0048] In addition, the present invention reasonably arranges the reaction process and controls the catalyst bed structure, so that the light components of the distillate oil after secondary hydrogenation can quickly leave the system and no longer excessively participate in the cracking reaction. Since the product can quickly leave the reaction system, the forward reaction rate is increased, and the hidden danger of by-product clogging the catalyst is eliminated, thereby improving the yield of the target product and extending the service life of the catalyst.

[0049] The present invention can realize the timely extraction of light intermediate products through flash evaporation and stripping by setting the distillation unit of the catalytic reaction distillation tower, so as to effectively control the reaction degree, retain the aromatic components to the maximum extent, and become a good chemical raw material. At the same time, since the product partial pressure is always kept at a low state, the reaction speed is accelerated, which is beneficial to improve the reaction efficiency and can take away the unsaturated components that are easy to coke. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of the catalytic reaction distillation tower of the present invention.

[0051] Figure 2 It is a top view of the liquid phase distribution pipe in the catalytic reaction unit of the present invention.

[0052] Figure 3 It is a top view of the gas-phase feed pipe and the gas-phase distribution pipe in the catalytic reaction unit of the present invention (showing the situation where the gas-phase feed pipe and the annular gas-phase distribution pipe are arranged orthogonally).

[0053] Figure 4 It is another top view of the gas-phase feed pipe and the gas-phase distribution pipe in the catalytic reaction unit of the present invention (showing the situation where the gas-phase feed pipe and the annular gas-phase distribution pipe are arranged to intersect tangentially).

[0054] Figure 5 It is a top view of the gas phase distribution pipe of the present invention which adopts a concentric double-ring distribution pipe.

[0055] Figure 6 It is a top view of the gas phase distribution plate in the catalytic reaction unit of the present invention.

[0056] Figure 7 It is a top view of the catalyst support plate in the catalytic reaction unit of the present invention.

[0057] Figure 8 It is a top view of the inert filler support plate in the distillation unit of the present invention.

[0058] Fig. 9 It is a top view of the guide unit in the distillation unit of the present invention.

[0059] Fig.10 It is a process flow chart of the hydrocracking method of the present invention.

[0060] Description of main reference numerals:

[0061] 1- catalytic reaction distillation tower, 5- hydrocracking pretreatment reactor, 6- heat exchange cooler, 7- reflux tank, 8- circulating hydrogen heating furnace;

[0062] 10-hydrocracking catalyst, 11-first umbrella-shaped partition, 12-inner downcomer, 13-gas phase channel, 14-overflow weir, 15-downcomer folding plate, 16-liquid receiving tray, 17-liquid sealing baffle, 18-outer downcomer, 19-catalyst support plate, 191-grid;

[0063] 21-liquid phase feed pipe, 22-liquid phase distribution pipe, 220-liquid phase distribution pipe body, 221-liquid phase channel;

[0064] 31-gas phase feed pipe, 32-gas phase distribution pipe, 320-gas phase distribution pipe body, 321-gas phase channel, 33-gas phase distribution plate, 331-hole;

[0065] 41-second umbrella-shaped partition, 411-hollow portion, 42-liquid phase heavy component collection port, 43-filler support plate, 44-inert filler;

[0066] 1001-raw oil, 1002-mixture of raw oil and hydrogen, 1003-pre-reaction effluent, 1004-catalytic reaction distillation tower top effluent, 1005-reflux tank feed, 1006-reflux tank top gas, 1007-hydrogenation treatment circulating gas, 1008-catalytic distillation circulating gas, 1009-catalytic reaction distillation tower hydrogen feed, 1010-reflux tank bottom effluent, 1011-catalytic reaction distillation tower top reflux, 1012-catalytic reaction distillation tower top product (light product), 1013-catalytic reaction distillation tower bottom product (heavy product), 1014-supplemental hydrogen. DETAILED DESCRIPTION

[0067] The present invention will be further described below by way of examples, but the protection scope of the present invention is not limited by the examples.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] like Figure 1 As shown, the catalytic reaction distillation tower 1 of the present invention is an upper and lower structure, wherein a catalytic reaction unit is arranged in the lower part of the tower, and a distillation unit is arranged in the upper part of the tower. The catalytic reaction unit is an internal component of the reaction distillation tower 1, and includes a plurality of catalyst beds, a liquid-phase feed subunit, a gas-phase feed subunit, and a gas-phase channel. The catalyst bed is used to fill the hydrocracking catalyst 10. Starting from the second layer at the top, the upper part of the hydrocracking catalyst 10 filled in each catalyst bed has an inclined surface. The overall shape formed by the inclined surface can be an inverted umbrella shape, which acts as a partition. On the one hand, it can separate the gas-phase feed and the product gas between adjacent beds, and on the other hand, it plays a guiding role for the liquid phase and the gas phase. Preferably, but not restrictively, the inverted umbrella surface can be an arc shape or a folding umbrella shape. The liquid-phase feed subunit is arranged above the top first catalyst bed layer, and the liquid-phase feed is guided downward to the first catalyst bed layer to contact the hydrocracking catalyst 10. Specifically, an inner downcomer 12 (i.e., Figure 1The bottom of the inner downcomer 12 is spaced a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed along the radial direction of the reaction distillation tower 1. The gas-phase feed subunit is arranged in each catalyst bed, specifically between the catalyst bed of the upper layer and the inverted first umbrella-shaped partition 11 of the lower layer, and the gas-phase feed of each layer enters the catalyst bed upward. After the gas-liquid phase feed and the hydrocracking 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 inverted first umbrella-shaped partition 11. The gas-phase channel 13 is in a relatively isolated state from the gas-phase feed subunit, that is, the gas-phase product generated after the gas-phase feed and the liquid-phase feed react in the catalyst bed directly enters the gas-phase channel 13. Preferably, but not restrictively, the gas-phase channel is located on the outside of the reaction distillation tower 1, is annular and passes through all catalyst beds from bottom to top.

[0072] Further Figure 1 , 2 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 catalytic reaction unit, 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 various positions above the first catalyst bed. The openings of the channels 221 can be in various directions on the upper, lower and side surfaces of the pipe body. The liquid-phase feed enters the reaction distillation tower 1 through the liquid-phase feed pipe 21, enters the tower through the annular liquid-phase distribution pipe 22, and is distributed to the first catalyst bed. The annular diameter of the annular liquid-phase distribution pipe 22 is larger than the outer diameter of the inner downcomer 12, and smaller than the inner diameter of the reaction distillation tower 1. The height of the downcomer fold 15 is generally smaller than the height of the catalyst loading in this layer, and the size of the space enclosed by the downcomer fold 15 is determined according to the flow rate of the liquid phase reactant in this layer.

[0073] Further Figure 1As shown, the height of each catalyst bed in the reaction distillation tower 1 can be the same or different, depending on the different chemical reaction systems. 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 seal baffle 17, and the overflow weir 14 is arranged on the side close to the gas phase channel 13. The liquid seal baffle 17 is arranged on the upper part of the overflow weir 14 to isolate the gas phase feed from the gas phase product. Further, the liquid seal baffle 17 includes a horizontal part and a vertical part, the horizontal part is an annular flat plate and is located above the overflow weir 14; the vertical part is cylindrical, and the vertical part is integrally formed with the horizontal part, and other seamless connection methods can also be used. The lower end of the vertical part 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 material in the catalyst bed pass through the overflow weir 14, through the outer downcomer 18 (i.e., the annular space between the overflow weir 14 and the inner wall of the gas phase channel 13), along the inverted first umbrella-shaped partition 11, and through the inner 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 this bed, preferably 10 to 100 mm higher. The annular outer downcomer 18 formed between the overflow weir 14 and the inner 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 downcomer of each bed can be the same or different.

[0074] Further Figure 1 , 3 As shown in FIG. 5 , the gas phase feed subunit includes a gas phase feed pipe 31 and a gas phase distribution pipe 32. The gas phase feed pipe 31 extends in the radial direction of the reaction distillation tower 1. The gas phase distribution pipe 32 is annular (see FIG. Figure 3 , 4 ) or multiple layers of concentric rings (see Figure 5 The gas phase feed pipe 31 is orthogonal to the pipe body 320 of the gas phase distribution pipe 32 (see Figure 3 ) or tangential intersection (see Figure 4 ), a plurality of holes 321 are provided on the wall of the gas phase distribution pipe 32, which are used to evenly distribute the gas phase feed to all directions at the bottom of the catalyst bed. Preferably, but not limiting, the gas phase distribution pipe 32 can be arranged below the catalyst bed, or can be arranged inside the catalyst bed. Figure 6As shown, the gas-phase feed subunit further includes a gas-phase distribution plate 33, which is located at the bottom of the catalyst bed and is in the shape of a plate as a whole. The gas-phase distribution plate is evenly and densely distributed with a plurality of holes 331. The gas-phase feed enters the reaction distillation tower 1 through the gas-phase feed pipes 31 of each layer, is distributed into the reaction distillation tower 1 through the annular gas-phase distribution pipe 32, and enters the catalyst bed upward through the gas-phase distribution plate 33 at the lower part of the catalyst support plate 19. The gas-phase feed pipe 31 enters the reaction distillation tower 1 in a radial direction, and intersects orthogonally or tangentially with the annular gas-phase distribution pipe 32. The annular gas-phase distribution pipe 32 is located below the catalyst bed. The annular diameter of the annular gas-phase 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 gas-phase distribution pipe 32 facilitate the uniform distribution of gas at various positions of the gas-phase 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 reaction distillation tower. The function of the gas phase distribution plate 33 is to ensure uniform distribution of the gas phase feed, while trying to avoid direct leakage of the liquid phase feed on the catalyst bed (using the gas phase distribution plate 33 of the present invention, the liquid leakage is less than 15%). When more than one concentric annular gas phase distribution pipe 32 of different diameters is arranged on the same plane, the distribution of the gas phase feed can be made more uniform. Figure 1 In the embodiment of the present invention, the annular gas phase distribution pipe 32 is arranged below the catalyst bed layer. When the annular gas phase distribution pipe 32 is installed in the catalyst bed layer, the catalyst support plate 19 can Figure 7 The grid 191 is changed into a support plate, and the gas phase distribution plate 33 is cancelled.

[0075] Further Figure 1 As shown, after the liquid feed and the gas feed react in the catalyst bed layers of each layer, the generated gas phase product directly enters the annular gas phase channel 13 on the side of the tower wall, and the gas phase product passes through the gas phase channel 13 and rises to the inert packing layer 44 of the distillation unit. The lower part of the inert packing layer 44 is provided with a grid-type packing support plate 43 (see Figure 8 ), the gas phase product from the catalytic reaction unit is distilled here. The feed is converted into the target product (i.e., the gas phase product) through the catalytic reaction unit of the present invention and is promptly separated from the reaction system (the gas phase feed will not be mixed with the gas phase product for secondary reaction). The gas phase product obtained by the catalytic reaction unit rises to the distillation unit through the gas phase channel 13. One or two or more target products can be obtained through the distillation unit. During the distillation process of the inert filler layer 44, some liquid phase heavy components will be generated. Therefore, the present invention is provided with a guide unit between the inert filler layer 44 and the first catalyst bed layer. The guide unit is a connection device between the distillation unit and the catalytic reaction unit. While collecting the liquid, it can play a role in evenly distributing the gas phase product rising from the catalytic reaction unit. The guide unit is an inverted umbrella-shaped partition structure as a whole (i.e. Figure 1The second umbrella-shaped partition 41 is a hollow structure at a position corresponding to the gas phase channel 13 and close to the side of the distillation tower wall of the second umbrella-shaped partition 41 (see Fig. 9 The hollow portion 411 is arranged near the tower wall so that the rising gas phase product from the gas phase channel 13 can smoothly enter the inert seasoning layer 44. The second umbrella-shaped partition 41 is provided with an opening (i.e., a hollow portion 411) near the middle of the distillation tower for the descending liquid phase heavy components after distillation to enter the catalytic reaction unit. Figure 1 and Fig. 9 The liquid phase heavy component collecting port 42 in the distillation unit can re-enter the catalytic reaction unit through the liquid phase heavy component descending through the distillation unit.

[0076] The catalytic reaction unit of the present invention is in the catalyst bed, and the liquid phase feed and the gas phase feed are catalytically reacted. The gas phase product and the unreacted gas phase feed rise through the gas phase channel 13 and leave the reaction system. The gas phase product generated after the reactants undergo chemical reaction in the catalyst bed will leave the reaction zone in time and will not enter the upper catalyst bed again (isolated by the inverted umbrella-shaped partition), thereby 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 product in the reaction zone, the driving force of the reaction is increased and the equilibrium conversion rate is improved.

[0077] The reaction distillation tower of the present invention uses the above catalytic reaction unit, and the reaction distillation tower 1 can be a multi-layer plate tower structure. The number of catalyst beds in the reaction distillation tower is two or more. The reaction distillation tower 1 of the present invention is suitable for a reaction system in which at least one liquid feed and at least one gas feed undergo a chemical reaction on a hydrocracking catalyst, and at least one gas product is included in the reaction product. For example, hydrocracking of petroleum fractions and chemical synthetic oils, hydrodewaxing of diesel and lubricating oil fractions, and hydrotreatment processes of various petroleum fractions.

[0078] In addition to the downcomers, overflow weirs and liquid receiving trays 16, each tray of the reaction distillation tower 1 of the present invention is also provided with a liquid sealing baffle on the tray, which is connected to the gas phase channel. Adjacent trays are separated by inverted umbrella-shaped partitions. Each tray is an annular structure, and the outer edge of the annular structure is connected to the gas phase channel. The gas phase channel is a common channel for removing the gas phase products generated by the chemical reaction on each tray. In the embodiment of the present invention, the liquid feed positions are all on the upper part of the first tray, and liquid feed can also be provided on some trays or each tray, and the gas phase feed has feed at the lower part of each tray. Above each tray is a catalyst loading area, and the liquid phase feed flows radially through the catalyst bed. The gas phase 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 on the outside. After the liquid phase leaves the current bed, it enters the next bed through the downcomer. Since the reaction and separation are carried out simultaneously, the reaction equilibrium can be destroyed, and the conversion rate of the reactants and the selectivity of the target product can be effectively improved.

[0079] like Fig.10 As shown, the feedstock oil 1001 of the hydrocracking unit is mixed with the hydroprocessing circulating gas 1007 through heat exchange heating, and the feedstock oil and hydrogen mixture 1002 enters the hydrocracking pretreatment reactor 5. The reactor is equipped with a hydrocracking pretreatment catalyst, and there may be one or more beds. Cold hydrogen may be injected between the beds. The feedstock undergoes chemical reactions such as hydrodenitrogenation, hydrodesulfurization and hydrogenation saturation in the hydrocracking pretreatment reactor 5. The pre-reaction effluent 1003 enters the middle part of the catalytic reaction distillation tower. The catalytic reaction distillation tower is divided into an upper section and a lower section. The upper section is a distillation section, and the product is distilled and separated. The effluent 1004 from the top of the catalytic reaction distillation tower passes through a heat exchange cooler 6, and the cooled mixture 1005 enters a reflux tank 7 for gas-liquid separation. The top gas of the reflux tank 1006 is divided into two circulations. One circulation is to the hydrocracking pretreatment reactor 5 through the hydroprocessing circulating hydrogen pipeline 1007; the other circulation is to the circulating hydrogen heating furnace 8 through the catalytic distillation circulating hydrogen pipeline 1008, mixed with the supplementary hydrogen 1014, and then enters the catalytic reaction distillation tower 1 through the catalytic distillation hydrogen inlet pipeline 1009 (multiple pipelines, at least one for each catalyst bed). The bottom outflow 1010 of the reflux tank 7 is divided into two parts, one part is returned to the top of the distillation section tower as reflux through the reflux pipeline 1011, and the other part is discharged from the device as a light product through the light product pipeline 1012. The lower section of the catalytic reaction distillation tower is the reaction section, which is the place where the heavy fraction undergoes hydrocracking reaction. Here, the light components generated by the hydrocracking reaction of the heavy fraction rise to the distillation section through the gas phase channel, and the uncracked heavy fraction passes through the catalyst bed layer step by step. The heavy components that have not cracked after passing through the lowest bed layer are discharged from the bottom pipeline 1013 of the catalytic reaction distillation tower as the heavy product of the device.

[0080] Examples 1-5

[0081] The following device process flow charts and Fig.10 The process conditions of each embodiment are shown in Table 2, and the properties of the main products obtained are shown in Table 3. In each example, the hydroprocessing reactor is loaded with FF-36 catalyst, the catalyst bed of the catalytic reaction unit of the catalytic reaction distillation tower is loaded with FC-24 catalyst, and the raw oil uses catalytic diesel. The properties are shown in Table 1. In each example, one catalyst bed is set in the hydrocracking pretreatment reactor. The number of catalyst beds in the catalytic reaction distillation tower is 6. The diameter-to-height ratio of each catalyst bed is: 5:1 in Example 1, 20:1 in Example 2, 40:1 in Example 3, 100:1 in Example 4, and 500:1 in Example 5. The inert filler in the catalytic reaction distillation tower is Raschig ring.

[0082] Table 1 Raw oil properties

[0083] Crude oil FCC Diesel A FCC Diesel B <![CDATA[Density / g·cm -3 > 0.9440 0.9213 Distillation range / ℃ 148～370 151～344 Sulfur content, wt% 1.10 1.05 <![CDATA[Nitrogen content / μg·g -1 > 910 860 Aromatics, wt% 78.0 75.3 Cetane number 15.1 17.0

[0084] Comparative Example 1

[0085] A conventional one-stage serial hydrocracking method, i.e., hydrogenation pretreatment + hydrocracking process, is adopted. The cracking reactor adopts raw oil and hydrogen to enter from the upper part of the reactor. The cracked distillate oil is separated by a separation tower and then sent out as a product. The diameter-to-height ratio of the catalyst bed in the cracking reactor is 1:3. The other conditions are the same as those in Example 1. The properties of the main products obtained are shown in Table 3.

[0086] Table 2 Example process conditions

[0087]

[0088]

[0089] Table 3 Properties of main products

[0090]

[0091]

[0092] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A hydrocracking method, comprising the following steps: The raw oil is mixed with hydrogen and then enters the hydrocracking pretreatment reactor for pre-reaction; The pre-reaction effluent enters the catalytic reaction distillation tower for hydrocracking reaction and distillation to obtain corresponding products; The method comprises the following steps: (1) The crude oil is mixed with hydrogen and then enters the hydrocracking pretreatment reactor to undergo a pre-reaction under hydrogenation conditions; (2) The pre-reaction effluent of step (1) enters a catalytic reaction distillation tower; the catalytic reaction distillation tower is provided with a rectification unit at the upper part, and the catalytic reaction unit is provided at the lower part of the catalytic reaction distillation tower; The gas phase in the pre-reaction effluent enters the distillation unit of the catalytic reaction distillation tower for distillation; the liquid phase in the pre-reaction effluent enters the catalytic reaction unit of the catalytic reaction distillation tower for hydrocracking reaction; (3) The gas phase in the logistics after the hydrocracking reaction in step (2) enters the distillation unit, and the liquid phase in the logistics after the hydrocracking reaction flows out from the bottom of the catalytic reaction distillation tower to obtain the corresponding product; The distillation unit in step (2) is arranged on the upper part of the catalytic reaction unit and distills the gas phase generated by the catalytic reaction unit and the gas phase of the pre-reaction effluent in step (1); The catalytic reaction unit comprises: A plurality of catalyst beds, which are used to fill the hydrocracking catalyst, starting from the second layer, the upper part of the hydrocracking catalyst filled in each catalyst bed has an inclined surface; A liquid phase feed subunit is arranged above the first catalyst bed layer at the top of the catalytic reaction unit, and the liquid phase feed is guided downward to the first catalyst bed layer; A gas-phase feed subunit, which is arranged between the catalyst bed layer of the upper layer and the inclined surface of the lower layer, and the gas-phase feed of each layer enters the catalyst bed layer upward; A gas phase channel, which is relatively isolated from the gas phase feed subunit, and a gas phase product generated after the gas phase feed and the liquid phase feed react in the catalyst bed directly enters the gas phase channel; The gas phase channel is located outside the catalytic reaction unit and is annular and passes through all the catalyst beds from bottom to top; And / or, the inclined surface as a whole is an inverted umbrella-shaped partition structure; An inner downcomer is disposed at the end of the inverted umbrella-shaped partition, and the bottom of the inner 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; The catalyst bed of the catalytic reaction unit is provided with: An overflow weir, which is arranged on a 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 gas phase feed from the gas phase product; The liquid sealing baffle comprises: a horizontal portion, which is in the shape of an annular flat plate and is located above the overflow weir; The vertical part is cylindrical and is formed integrally with the horizontal part. The lower end of the vertical part is spaced a distance from the bottom of the catalyst bed.

2. The hydrocracking method according to claim 1, characterized in that: The hydrogenation conditions of the pre-reaction in step (1) are: total pressure 2.0-20.0 MPa, average reaction temperature 330-400°C, liquid hourly volume space velocity 0.5-3.0 h -1 , hydrogen-oil volume ratio 200:1~2000:1; and / or, at least one catalyst bed is provided in the hydrocracking pretreatment reactor in step (1); And / or, the pre-reaction in step (1) includes at least one of hydrodesulfurization, hydrodenitrogenation and hydrosaturation reaction; And / or, the catalyst used in the hydrocracking pretreatment reactor in step (1) is a hydrocracking pretreatment catalyst.

3. The hydrocracking method according to claim 2, characterized in that: The number of catalyst beds in the hydrocracking pretreatment reactor in step (1) is 1 to 4.

4. The hydrocracking method according to claim 2 or 3, characterized in that: In step (1), a quench hydrogen inlet is provided between the catalyst beds of the hydrocracking pretreatment reactor.

5. The hydrocracking method according to claim 1, characterized in that: The liquid phase feeding subunit comprises: a liquid-phase feed pipe extending in a radial direction of the catalytic reaction unit; A liquid phase distribution pipe, which is annular and intersects the liquid phase feed pipe orthogonally or tangentially, and the wall of the liquid phase distribution pipe is provided with a plurality of holes for evenly distributing the liquid phase feed to various positions above the first catalyst bed layer; And / or, the gas phase feeding subunit comprises: a gas-phase feed pipe extending in a radial direction of the catalytic reaction unit; A gas phase distribution pipe, which is annular or multi-layered concentric annular, and intersects the gas phase feed pipe orthogonally or tangentially. The wall of the gas phase distribution pipe is provided with a plurality of holes for evenly distributing the gas phase feed to all directions at the bottom of the catalyst bed; the gas phase distribution pipe is arranged below the catalyst bed or in the catalyst bed; The gas phase 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 gas phase distribution plate.

6. The hydrocracking method according to claim 1, characterized in that: The distillation unit is provided with an inert packing layer, and the rising gas phase product from the gas phase channel is distilled in the inert packing layer; A guide unit is provided between the inert filler layer and the first catalyst bed layer. The guide unit is an inverted umbrella-shaped partition structure as a whole. The umbrella-shaped partition is close to the distillation tower wall and is a hollow structure at the position corresponding to the gas phase channel. The umbrella-shaped partition is close to the middle of the distillation tower and is provided with an opening for the liquid phase heavy components descending after distillation to enter the catalytic reaction unit.

7. The hydrocracking method according to claim 1, characterized in that: The catalytic reaction distillation tower is a multi-layer plate tower structure; The number of catalyst beds in the catalytic reaction distillation tower is 2 to 20.

8. The hydrocracking method according to claim 1, characterized in that: The hydrocracking reaction conditions of the catalytic reaction unit in step (2) are: an average reaction temperature of 300-450°C, a liquid hourly volume space velocity of 0.5-3.0h -1 , hydrogen-oil volume ratio 500:1~10000:

1.

9. The hydrocracking method according to claim 1, characterized in that: The distillation reaction conditions of the distillation unit in step (2) are: the tower top pressure is 2.0-20.0 MPa, and the tower top temperature is 200-400°C.

10. The hydrocracking method according to claim 1, characterized in that: In step (3), the reaction effluent of the distillation unit is subjected to heat exchange cooling and then gas-liquid separation, and a portion of the resulting liquid phase flow is refluxed into the top of the catalytic reaction distillation tower distillation unit, and the other portion flows out of the pipeline as the obtained light product; the top reflux ratio of the catalytic reaction distillation tower distillation unit is 1:1 to 3:1.

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