CN116064124A

CN116064124A - Coal tar hydrotreatment device and method

Info

Publication number: CN116064124A
Application number: CN202111267788.9A
Authority: CN
Inventors: 王晶晶; 宣根海; 徐彤; 郭兵兵; 赵玉琢
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-05-05

Abstract

The invention discloses a coal tar hydrotreatment device and a method, wherein the device comprises the following steps: a prefractionator for fractionating the pretreated coal tar and obtaining light components; a hydrogenation reactor which receives the prefractionated light component as a liquid phase feed which flows through each catalyst bed in turn from top to bottom; hydrogen uniformly enters from the bottom of each catalyst bed layer from bottom to top; the gas-phase product after hydrogenation reaction is discharged from the top of the reactor from an independent gas-phase channel; a fractionation column that receives the hydroconverted cold low pressure oil and fractionates it into a clean fuel oil product. The coal tar hydrotreatment device and the method can effectively solve the problem that gas phase reaction products of a hydrogenation reactor are timely separated from a reaction zone.

Description

Coal tar hydrotreatment device and method

Technical Field

The invention relates to the field of hydrogenation reaction, in particular to a coal tar hydrotreating device and method.

Background

Coal tar is one of liquid products obtained in carbonization and gasification processes, is black or black brown viscous liquid with pungent odor at normal temperature, mainly comprises polycyclic aromatic compounds, has extremely complex composition, and can be divided into low-temperature coal tar, medium-temperature coal tar, high-temperature coal tar and other different products according to different cracking temperatures. The coal tar is processed by a hydrogenation method, so that low-sulfur naphtha and clean fuel oil with high added values can be obtained. The coal tar is clean and light, the shortage of petroleum resources can be effectively supplemented, the coal resources can be efficiently utilized, and the problems of low comprehensive utilization of resources, environmental pollution and the like which plague the coking industry in China for a long time are solved.

However, coal tar itself contains a large amount of polar substances containing oxygen and a certain amount of unsaturated hydrocarbons and impurities such as sulfur, nitrogen and metals. Meanwhile, the coal tar contains a large amount of fine inorganic impurities, organic impurities and other special substances, and the conventional fixed bed, boiling bed and suspension bed are adopted to process coal tar distillate oil or whole distillate, so that certain difficulties exist, such as the problem that the fixed bed is easy to block the bed by solid substances; a large amount of heat is released in the hydrotreating process, which causes bed temperature runaway and causes bed hot spots to appear. After hydrogenation reaction, hydrodeoxygenation and other reactions are carried out on polar substances containing oxygen and the like, tiny impurities are released and are easily deposited in a reactor bed. Meanwhile, the conventional loading scheme of the heavy oil fixed bed catalyst is that the catalyst pore diameter is smaller and smaller along the flowing direction of the reactants, so that the reactor bed is easy to be blocked, and particularly the position of the reaction bed layer released by impurities after deoxidation is easier to be blocked, and the long-period stable operation of the whole reaction device is influenced.

More importantly, the gas phase product (H) generated by the hydrofining reaction in the hydrogenation reactor in the prior art ₂ O、H ₂ S、NH ₄ Etc.) and unreacted hydrogen feed may remain in the catalyst bed and contact the catalyst, adversely affecting catalyst activity; meanwhile, as the hydrogenation reaction is an exothermic reaction, the retention of gas phase products cannot take away most of reaction heat in time, so that the consumption of hydrogen is increased.

Therefore, a coal tar hydrotreater is needed to effectively solve the problem that the gas phase reaction product of the hydrogenation reactor is timely separated from the reaction zone.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a coal tar hydrotreatment device and a coal tar hydrotreatment method, which can effectively solve the problem that gas phase reaction products of a hydrogenation reactor are timely separated from a reaction zone.

To achieve the above object, according to a first aspect of the present invention, there is provided a coal tar hydrotreater comprising: a prefractionator for fractionating the pretreated coal tar and obtaining light components; a hydrogenation reactor which receives the prefractionated light component as a liquid phase feed which flows through each catalyst bed in turn from top to bottom; hydrogen uniformly enters from the bottom of each catalyst bed layer from bottom to top; the gas-phase product after hydrogenation reaction is discharged from the top of the reactor from an independent gas-phase channel; a fractionation column that receives the hydroconverted cold low pressure oil and fractionates it into a clean fuel oil product.

Further, in the above technical solution, the hydrogenation reactor may include: a catalyst bed for filling solid catalyst, the solid catalyst filled in each catalyst bed having an inclined surface at an upper portion thereof; a liquid phase feed subunit disposed above the sloped surface of the topmost catalyst bed through which liquid phase feed is directed to the catalyst bed; a hydrogen feed subunit disposed between the upper catalyst bed and the inclined surface of the lower catalyst bed, the hydrogen feed of each layer being directed upwardly into the catalyst bed; and the independent gas phase channel is in a relative isolation state with the hydrogen feeding subunit, and gas phase products generated after the hydrogen and the liquid phase feeding react in the catalyst bed layer directly enter the gas phase channel.

Further, in the above technical solution, the whole of the inclined surface may be an umbrella-shaped partition plate structure.

Further, in the above technical solution, the end of the umbrella-shaped partition plate may be provided with an annular downcomer, and the bottom of the downcomer is spaced from the bottom of the catalyst bed by a distance so that the liquid phase feed enters the catalyst bed in the radial direction.

Further, in the above technical solution, the catalyst bed may be provided with: an overflow weir provided on one side close to the gas phase passage; and the liquid sealing baffle is arranged at the upper part of the overflow weir and is used for isolating the hydrogen from the gas-phase product.

Further, in the above technical solution, the liquid seal baffle may include: a horizontal part which is in an annular flat plate shape and is positioned above the overflow weir; and the vertical part is cylindrical, the vertical part and the horizontal part are integrally formed, and the lower end of the vertical part is spaced from the bottom of the catalyst bed by a certain distance.

Further, in the above technical solution, the liquid phase feeding subunit may further include: a liquid phase feed tube extending in a radial direction of the hydrogenation reactor; and the liquid phase distributing pipe is annular and is orthogonal or tangentially intersected with the liquid phase feeding pipe, and the pipe wall of the liquid phase distributing pipe is provided with a plurality of pore channels for uniformly distributing liquid phase feeding materials to all directions of the annular downcomer.

Further, in the above technical solution, the hydrogen feeding subunit may further include: a hydrogen feed tube extending in a radial direction of the hydrogenation reactor; the hydrogen distribution pipe is annular or multi-layer concentric annular, the hydrogen distribution pipe is orthogonal or tangentially intersected with the hydrogen feeding pipe, and a plurality of pore channels are arranged on the wall surface of the hydrogen distribution pipe and are used for uniformly distributing hydrogen feeding materials to all directions at the bottom of the catalyst bed.

Further, in the above technical solution, the hydrogen feeding subunit may further include: the hydrogen distribution plate is positioned at the bottom of the catalyst bed and is in a disc shape as a whole, and a plurality of holes are uniformly distributed on the hydrogen distribution plate.

Further, in the above technical solution, the gas phase channel may be located in the middle of the hydrogenation reactor and penetrates all the catalyst beds from bottom to top.

Further, in the above technical solution, the hydrogen distribution pipe may be disposed below the catalyst bed or within the catalyst bed.

Further, in the above technical solution, the number of catalyst beds may be two or more than two; each catalyst bed layer is filled with a hydrofining catalyst, or the upper layer is filled with a hydrofining catalyst, and the lower layer is filled with a hydrocracking catalyst; the void fraction of the catalyst bed is 0.5% to 85%, preferably 1% to 20%.

Further, in the above technical scheme, the liquid phase product after hydrogenation flows to the bottom of the hydrogenation reactor, a liquid level monitoring unit is arranged at the bottom, and the discharge is stopped when the liquid level is lower than a set value.

Further, in the above technical scheme, the coal tar hydrotreater of the present invention may further include: the cold high-pressure separator is used for receiving the gas-phase product discharged from the top of the hydrogenation reactor and the hydrogen which is not reacted, separating cold high-pressure gas and cold high-pressure oil, and returning the purified cold high-pressure gas to the hydrogenation reactor for recycling; a cold low pressure separator that receives the liquid phase product from the bottom of the hydrogenation reactor and cold high pressure oil from the cold high pressure separator and separates cold low pressure gas and cold low pressure oil.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a coal tar hydrotreating method comprising the steps of: fractionating the pretreated coal tar to obtain light components; light components are used as liquid phase feed and sequentially flow through each catalyst bed layer of the hydrogenation reactor from top to bottom; hydrogen uniformly enters from the bottom of each catalyst bed layer from bottom to top; the gas-phase product after hydrogenation reaction is discharged from the top of the reactor from an independent gas-phase channel; separating the gas phase product at a cold high pressure, obtaining cold high pressure oil and cold high pressure gas, purifying the cold high pressure gas and recycling the purified cold high pressure gas; carrying out cold low-pressure separation on the liquid phase product and cold high-pressure oil after hydrogenation reaction to obtain cold low-pressure oil; and fractionating the cold low-pressure oil to prepare a clean fuel oil product.

Further, in the above technical solution, the clean fuel oil product may include naphtha and diesel.

Further, in the above technical scheme, the operation conditions of the hydrogenation reaction may be: the reaction temperature of the hydrogenation reactor is 300-450 ℃; the reaction pressure is 3MPa to 20MPa; the volume ratio of the hydrogen to the oil is 200:1-1500:1, preferably 500-1000; volume space velocity of 0.2h ^-1 ～2.0h ^-1 。

Further, in the above technical scheme, the coal tar may be at least one of low-temperature coal tar, medium-temperature coal tar and medium-low-temperature coal tar. The purity of the hydrogen gas may be 99.9%.

Compared with the prior art, the invention has the following beneficial effects:

1) H generated after chemical reaction of reactants in the hydrogenation reactor of the invention in the catalyst bed layer ₂ O、H ₂ S、NH ₄ The gas-phase product can timely leave the reaction zone and cannot enter the upper catalyst bed again, namely, the gas-phase product is not contacted with the hydrofining/cracking catalyst bed, so that the adverse effect on the catalyst activity is reduced, the catalyst poisoning caused by the gas-phase product is effectively avoided, and the service life of the catalyst is prolonged; the secondary reaction of the target product is effectively avoided, and the selectivity of the reaction is improved; meanwhile, as the gas phase products in the reaction zone leave, the reaction driving force is increased, and the equilibrium conversion rate is improved; in addition, the timely separation of the gas phase product can take away most of reaction heat, so that the consumption of hydrogen is reduced; the reaction is promoted to right, and the removal rate of sulfur and nitrogen in the raw oil and the yield of target products are improved;

2) The liquid phase feed of the hydrogenation reactor can sequentially flow through each catalyst bed layer from top to bottom, hydrogen uniformly enters from bottom to top to form a hydrogenation catalyst bed layer, and the hydrogenation catalyst bed layer is in countercurrent contact with the hydrogen flowing upwards from the bottom of the catalyst bed layer, so that the catalyst stacking density is not increased, and the pressure drop of the hydrogenation reactor bed layer can be effectively reduced;

3) The umbrella-shaped baffle plate in the hydrogenation reactor can separate hydrogen feeding and gas phase products between adjacent bed layers on one hand, and plays a role in guiding liquid phase and gas phase on the other hand; the liquid sealing baffle can effectively isolate the hydrogen feeding material from the gas-phase product; the arrangement of the multi-layer concentric annular hydrogen distribution pipes can keep the distribution of hydrogen feeding materials uniform to the greatest extent;

4) The catalyst bed layer of the hydrogenation reactor can be filled with the hydrofining catalyst at the upper layer and the hydrocracking catalyst at the lower layer, so that the double purposes of refining and cracking can be realized, the investment cost is reduced, the process flow is simplified, and clean fuel oil with high added value can be produced due to the fact that the hydrofining/cracking catalyst is filled at the same time.

The foregoing description is only an overview of the present invention, and it is to be understood that it is intended to provide a more clear understanding of the technical means of the present invention and to enable the technical means to be carried out in accordance with the contents of the specification, while at the same time providing a more complete understanding of the above and other objects, features and advantages of the present invention, and one or more preferred embodiments thereof are set forth below, together with the detailed description given below, along with the accompanying drawings.

Drawings

FIG. 1 is a process flow diagram of a coal tar hydroprocessing apparatus of the present invention;

FIG. 2 is a schematic diagram of the internal structure of the hydrogenation reactor of the present invention.

FIG. 3 is a top view of a liquid distribution tube in a hydrogenation reactor according to the invention.

Fig. 4 is a top view of the hydrogen feed pipe and the hydrogen distribution pipe in the hydrogenation reactor of the present invention (showing the case where the hydrogen feed pipe is disposed orthogonally to the annular hydrogen distribution pipe).

FIG. 5 is another top view of the hydrogen feed line and the hydrogen distribution line in the hydrogenation reactor of this invention (showing the tangential intersection of the hydrogen feed line and the annular hydrogen distribution line).

Fig. 6 is a top view of a hydrogen distribution tube of the present invention employing concentric dual ring distribution tubes.

FIG. 7 is a top view of a hydrogen distribution tray in a hydrogenation reactor according to the invention.

FIG. 8 is a top view of a catalyst support disc in a hydrogenation reactor according to the invention.

The main reference numerals illustrate:

1-hydrogenation reactor, 10-solid catalyst, 11-umbrella-shaped partition plate, 12-outer downcomer, 13-gas phase channel, 14-overflow weir, 15-liquid falling folded plate, 16-liquid receiving disc, 17-liquid sealing baffle, 18-inner downcomer, 19-catalyst supporting disc and 191-grille;

21-a liquid phase feeding pipe, 22-a liquid phase distributing pipe, 220-a liquid phase distributing pipe body and 221-a liquid phase pore canal;

31-hydrogen feeding pipe, 32-hydrogen distributing pipe, 320-hydrogen distributing pipe body, 321-hydrogen pore canal, 33-hydrogen distributing disk, 331-pore and 34-liquid phase product;

100-prefractionator, 200-high pressure separator, 201-heat exchanger, 202-sulfur nitrogen purifier, 300-low pressure separator, 400-fractionating tower; l1-coal tar raw material, L2-reactor feed, L3-hydroconversion high-fraction oil, L4-hydroconversion low-fraction oil, L5-naphtha, L6-diesel oil, L7-unconverted oil, L8-high-fraction sewage, L9-low-fraction sewage, L10-heavy oil fraction, Q1-hydrogen, Q2-reactor gas phase product, Q3-high-fraction gas, Q4-low-fraction gas.

Detailed Description

The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or other components.

Spatially relative terms, such as "below," "beneath," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element's or feature's in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the article in use or operation in addition to the orientation depicted in the figures. For example, if the article in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" may encompass both a direction of below and a direction of above. The article may have other orientations (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terms "first," "second," and the like herein are used for distinguishing between two different elements or regions and are not intended to limit a particular position or relative relationship. In other words, in some embodiments, the terms "first," "second," etc. may also be interchanged with one another.

As shown in fig. 1, the coal tar hydrotreater of the present invention includes a prefractionator 100, a hydrogenation reactor 1, a high pressure separator 200, a low pressure separator 300, and a fractionating tower 400. The process comprises the following steps: the coal tar is dehydrated, purified and pretreated, enters a prefractionator 100 for fractionation, light components obtained by prefractionation enter a hydrogenation reactor 1, and liquid phase feeding is uniformly distributed to all directions of an annular downcomer through liquid phase distribution in the reactor. Meanwhile, hydrogen Q1 enters the lower parts of catalyst beds in the reactor from the side wall of the hydrogenation reactor 1 respectively, and hydrogen feeding is uniformly distributed to all directions of the bottom of the catalyst beds through gas phase distribution. The catalyst beds of the hydrogenation reactor 1 can be sequentially filled with a hydrofining catalyst/a hydrocracking catalyst from top to bottom, and the liquid-phase feed L2 and the hydrogen feed Q1 respectively enter the catalyst beds from the upper part and the lower part of the catalyst beds and are in countercurrent contact for hydrofining/cracking reaction. The liquid phase feed L2 sequentially passes through all catalyst beds to obtain hydrogenated distillate oil (namely liquid phase product 34), and the liquid phase product 34 enters a cold low-pressure separator 300 from a bottom pipeline of the hydrogenation reactor 1; the gas phase product generated after the hydrogenation reaction of the catalyst bed and the unreacted hydrogen (mixed gas Q2) directly enter an independent gas phase channel in the hydrogenation reactor 1, are discharged from the top end of the hydrogenation reactor 1, enter a cold high pressure separator 200 (cooled by a heat exchanger 201 before entering) through a pipeline; the gas phase product of the hydrogenation reactor 1 is subjected to cold high-pressure separator 200 to obtain cold high-pressure gas Q3, cold high-pressure oil L3 and sulfur-containing sewage L8, the cold high-pressure gas Q3 is purified by a sulfur-nitrogen purifier 202 and then returned to the hydrogenation reactor 1 for recycling, and the cold high-pressure oil L3 enters a cold low-pressure separator 300 through a pipeline; the liquid-phase product 34 and the cold high-pressure oil L3 of the hydrogenation reactor 1 are separated in the cold low-pressure separator 300 to obtain cold low-pressure gas Q4, cold low-pressure oil L4 and sulfur-containing sewage L9, the cold low-pressure oil L4 continuously enters the fractionating tower 400 for further separation to obtain clean fuel oil products such as naphtha L5 and diesel oil L6, and unconverted oil L7 returns to the inlet of the hydrogenation reactor 1.

As further shown in fig. 2, the hydrogenation reactor 1 of the present invention comprises a catalyst bed, a liquid phase feed subunit, a hydrogen feed subunit, and a separate gas phase channel in the middle of the reactor. The catalyst beds are used for filling the solid catalyst 10, an inclined surface is arranged at the upper part of the solid catalyst 10 filled in each catalyst bed, the inclined surface can form an umbrella shape, the inclined surface can act as a partition plate, on one hand, the hydrogen feeding and the product gas between adjacent beds can be separated, on the other hand, the diversion effect of liquid phase and gas phase can be realized, and the umbrella cover can be an arc shape or a folded umbrella shape, preferably but not limited to. The liquid-phase feed sub-unit is disposed above the inclined surface of the topmost catalyst bed (i.e., umbrella-shaped partition 11) through which the liquid-phase feed is directed to contact the catalyst bed with the solid catalyst 10, and in particular, the umbrella-shaped partition 11 is terminated with an annular outer downcomer 12 (i.e., an annular space between the liquid-lowering flap 15 in fig. 2 and the inner wall surface of the hydrogenation reactor 1), the bottom of which outer downcomer 12 is spaced from the bottom of the catalyst bed by a distance such that the liquid-phase feed enters the catalyst bed in the radial direction of the hydrogenation reactor 1. The hydrogen feeding subunit is arranged on each catalyst bed layer, specifically arranged between the catalyst bed layer on the upper layer and the umbrella-shaped baffle plate 11 on the lower layer (namely, the bottom of each catalyst bed layer), and the hydrogen feeding of each layer enters the catalyst bed layer 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 baffle 11. The gas phase channel 13 and the hydrogen feeding subunit are in a relatively isolated state, namely, gas phase products generated after the hydrogen feeding and the liquid phase feeding react in the catalyst bed directly and timely enter the gas phase channel 13, so that the gas phase products can also be timely separated from the catalyst bed. Preferably, and without limitation, the gas phase channels 13 are located in the middle of the hydrogenation reactor 1 and run through all catalyst beds from bottom to top.

As further shown in fig. 2 and 3, the liquid phase feed subunit further comprises a liquid phase feed pipe 21 and a liquid phase distribution pipe 22. The liquid phase feeding pipe 21 extends along the radial direction of the hydrogenation reactor, the liquid phase distributing pipe 22 is annular, the liquid phase feeding pipe 21 is orthogonal or tangential intersected with the pipe body 220 of the liquid phase distributing pipe 22, and the pipe wall of the liquid phase distributing pipe 22 is provided with a plurality of pore channels 221 for uniformly distributing the liquid phase feeding material to all directions of the annular outer side downcomer 12. The openings of the tunnel 221 may be in all directions above, below, and to the side faces of the tube. The liquid phase feed enters the hydrogenation reactor 1 through a liquid phase feed pipe 21, is distributed into the reactor through an annular liquid phase distribution pipe 22, flows into an outer downcomer 12 from the periphery through an umbrella-shaped baffle plate 11, and transversely enters a catalyst bed layer to be contacted with the solid catalyst 10 after passing through the outer downcomer 12. The feeding direction of the liquid phase feeding pipe 21 is the radial direction of the hydrogenation reactor, and is intersected with the radial orthogonal or tangential direction of the annular liquid phase distributing pipe 22, the annular diameter of the annular liquid phase distributing pipe 22 is larger than the outer diameter of the gas phase channel 13 and smaller than the inner diameter of the hydrogenation reactor 1, and a plurality of pore canals on the pipe wall of the annular liquid phase distributing pipe 22 are convenient for the liquid phase feeding to be uniformly distributed in all directions of the outer side downcomer 12. The height of the liquid-lowering folded plate 15 is generally smaller than the filling height of the catalyst of the layer, and the distance between the liquid-lowering folded plate 15 and the inner wall of the hydrogenation reactor 1 is determined according to the flow rate of the liquid-phase reactant of the layer.

By adopting the hydrogenation reactor, liquid-phase feed can sequentially flow through each catalyst bed layer from top to bottom, hydrogen uniformly enters from bottom to top, and the hydrogenation catalyst beds are formed to be in countercurrent contact with the hydrogen flowing upwards from the bottoms of the catalyst beds, so that the pressure drop of the hydrogenation reactor beds can be effectively reduced.

As further shown in fig. 2, the upper part of the catalyst bed is fixed by a screen, the bed is kept relatively stable, and the height of the bed is set to be 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 at one side close to the gas phase channel 13. A liquid seal 17 is provided above weir 14 to isolate the hydrogen feed from the gas phase product. Further, the liquid seal baffle 17 includes a horizontal portion and a vertical portion, the horizontal portion is in the shape of an annular flat plate and is located above the overflow weir 14; the vertical part is cylindrical, the vertical part and the horizontal part are integrally formed, other seamless connection modes can be adopted, the lower end of the vertical part is separated from the bottom of the catalyst bed by a certain distance, and outflow of liquid phase products can be ensured. Unreacted liquid feed and reacted but liquid-phase-maintaining material within the catalyst bed passes over weir 14, through inner downcomer 18 (i.e., the annular space between weir 14 and the outer wall of gas phase channel 13), along umbrella baffle 11, through outer downcomer 12 of the next layer into the next catalyst bed. The height of weir 14 is above the upper level of the catalyst in the bed, preferably 10 to 100mm. The size of the space between the overflow weir 14 and the annular inner downcomer 18 formed by the outer wall of the gas phase channel 13 depends on the size of the liquid phase load, and the size of each bed downcomer can be the same or different.

As further shown in fig. 2, 4 to 6, the hydrogen feed subunit comprises a hydrogen feed pipe 31 and a hydrogen distribution pipe 32, the hydrogen feed pipe 31 extending in the radial direction of the hydrogenation reactor 1. The hydrogen distribution pipe 32 is annular (see fig. 4 and 5) or multi-layer concentric annular (see two-layer concentric rings of fig. 6), the hydrogen inlet pipe 31 is orthogonal to the pipe body 320 of the hydrogen distribution pipe 32 (see fig. 4) or tangentially intersects the pipe body (see fig. 5), and a plurality of holes 321 are formed in the wall surface of the hydrogen distribution pipe 32 and are used for uniformly distributing the hydrogen feed to all directions at the bottom of the catalyst bed. Preferably, and without limitation, the hydrogen distribution tube 32 may be disposed below the catalyst bed or within the catalyst bed. As further shown in fig. 7, the hydrogen feed subunit further comprises a hydrogen distribution plate 33, wherein the hydrogen distribution plate 33 is located at the bottom of the catalyst bed and is in a shape of a plate as a whole, and a plurality of holes 331 are uniformly distributed on the hydrogen distribution plate. The hydrogen feed enters the hydrogenation reactor 1 through the hydrogen feed pipes 31 of each layer, is distributed into the hydrogenation 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 feeding pipe 31 enters the hydrogenation reactor 1 in a radial direction and is orthogonal or tangentially intersected with the annular hydrogen distributing pipe 32, the annular hydrogen distributing pipe 32 is positioned below the catalyst bed layer, the annular diameter of the annular hydrogen distributing pipe 32 is smaller than the outer annular diameter of the catalyst bed layer, the inner diameter of the annular hydrogen distributing pipe 32 is larger than the inner annular diameter of the catalyst bed layer, and a plurality of pore channels 321 on the pipe wall of the annular hydrogen distributing pipe 32 are convenient for gas to be uniformly distributed at all positions of the hydrogen distributing plate 33. The function of the catalyst support disc 19 is mainly to support the catalyst bed, ensuring that the catalyst bed remains stable in the axial direction of the hydrogenation reactor. The purpose of the hydrogen distribution tray 33 is to ensure uniform distribution of the hydrogen feed while avoiding direct leakage of the liquid feed over the catalyst bed as much as possible (with the hydrogen distribution tray 33 of the present invention, liquid leakage is < 15%). When more than one concentric annular hydrogen distribution tube 32 of different diameters are provided on the same plane, the distribution of the hydrogen feed may be more uniform. The embodiment of fig. 2 provides for the annular hydrogen distribution tube 32 to be positioned below the catalyst bed, and when the annular hydrogen distribution tube 32 is installed within the catalyst bed, the catalyst support plate 19 may be modified from the grid 191 of fig. 8 to a support plate, while eliminating the hydrogen distribution plate 33.

In the hydrogenation reactor, each layer of tray comprises a downcomer, an overflow weir and a liquid receiving tray, a liquid sealing baffle plate is arranged on the tray, the liquid sealing baffle plate is connected with a gas phase channel, adjacent trays are separated by an umbrella-shaped baffle plate, each layer of tray is of an annular structure, the annular inner edge is connected with the gas phase channel, and the outer edge is connected with the inner wall of the hydrogenation reactor. The gas phase channels are common channels for removing gas phase products generated by chemical reaction on each tray layer. The liquid feeding positions of the embodiment of the invention are all at the upper part of one layer of trays, and liquid feeding can also be carried out on part of trays or each layer of trays, and hydrogen feeding is carried out at the lower part of each layer of trays. The catalyst filling area is arranged above each layer of tray, the liquid phase feed radially flows through the catalyst bed, the hydrogen feed enters from below the tray and reacts under the action of the catalyst, the gas phase material generated after the reaction directly breaks away from the reaction system and enters the gas phase channel in the middle part, and the liquid phase leaves the bed and enters the next bed through the downcomer. Because the reaction and the separation are carried out simultaneously, the reaction balance can be destroyed, and the conversion rate of reactants and the selectivity of target products can be effectively improved.

Further, the hydrogenation reactor of the invention can be provided with a plurality of catalyst beds, the catalyst beds can be filled with the hydrofining catalyst from top to bottom, or the hydrofining catalyst can be filled in the upper layer, and the hydrocracking catalyst can be filled in the lower layer. Preferably, but not by way of limitation, the volume ratio of hydrofinishing catalyst to hydrocracking catalyst is from 1:1 to 7:1. Two different types of catalysts are filled in the same reactor, so that the raw oil can be desulfurized and denitrified, and the raw oil is changed into clean fraction oil with medium molecular size after proper cracking. Aromatic hydrocarbon and long-chain macromolecular hydrocarbon are respectively saturated or cracked in the hydrogenation reactor to generate naphthenic hydrocarbon and short-chain micromolecular hydrocarbon, so as to achieve the purpose of modification. The void ratio of the catalyst bed layer in the hydrogenation reactor is 0.5-85%, preferably 1-20%.

Further, the hydrofining catalyst can be a hydrofining catalyst with high desulfurization and denitrification activity and less aromatic hydrocarbon saturation. The hydrofining catalyst includes carrier and active component, the hydrogenation active component is one, two or more of metal in VIB group and VIII group, such as W, mo, co, ni, and the total content of metal oxide is 2wt% -12 wt%, and the content of metal in VIB group is 5wt% -25 wt% based on oxide. Hydrofining catalysts can be prepared according to the prior art, or commercial hydrofining catalysts can be selected. The refined catalyst may contain adjuvants such as one or more of K, P, mg, zr and Ca, and the group VIII metal content is 3wt% to 10wt% in terms of oxide, and the group VIB metal content is 6wt% to 30wt% in terms of oxide.

Further, the hydrocracking catalyst comprises Y-type zeolite, alumina, at least one metal component selected from the VIII groups and at least one metal component selected from the VIB groups, wherein the VIB groups of the two catalysts are selected from molybdenum and/or tungsten, and the VIII groups of the two catalysts are selected from cobalt and/or nickel. The metal composition is as follows by weight percent: 10-30% of tungsten oxide, 5-15% of nickel oxide, and a certain amount of molecular sieves, such as one or two of a Y-type molecular sieve and a beta-type molecular sieve, can be contained, generally, 1-30% of molecular sieves, and the balance of refractory tungsten oxide carriers such as amorphous silica alumina, silicon-containing alumina, alumina and the like. The pore volume of the catalyst is 0.10-0.50 ml/g, and the specific surface is 120-350 m ² And/g. The hydrocracking catalyst is preferably a porous catalyst, a heterogeneous catalyst and/or a honeycomb catalyst. The pore diameter of the porous catalyst is 1-50 mm, preferably 4-20 mm; the average particle diameter of the shaped catalyst is 2-50 mm, preferably 4-30 mm; honeycomb body catalysisThe diameter of the agent hole or the side length of the hole is 1-50 mm, preferably 3-15 mm.

Further, the operating conditions of the coal tar hydrogenation process are as follows: the reaction temperature of the hydrogenation reactor is 300-450 ℃, the reaction pressure is 3-20 MPa, the volume ratio of hydrogen to oil is 200:1-1500:1, and the volume airspeed is 0.2h ^-1 ～2.0h ^-1 . The operation temperature of the high-pressure separator is 30-260 ℃ and the reaction pressure is 3-20 MPa.

The inventor finds that for the gas-liquid-solid three-phase reaction process of the conventional hydrogenation process with the rapid decrease of the liquid phase amount and the rapid increase of the gas phase amount in the reaction, the gas phase amount is rapidly increased to occupy a large amount of bed gaps, so that the flow rate of the liquid phase is greatly increased. In the prior art, although the sufficient contact of gas phase, liquid phase and solid phase can be ensured, the effective reaction time of the liquid phase which needs to be further converted is reduced, the contact probability of the gas phase which does not need to be reacted again (such as the gas phase obtained by liquid phase conversion under the reaction condition) and the catalyst is increased, and for a system which needs more liquid phase conversion and gas phase control secondary reaction, the overall reaction effect is limited to a certain extent, and the general manifestation is that the reaction conversion rate, the selectivity and the like are difficult to be further improved. In the hydrogenation reactor, liquid-phase feeding and hydrogen feeding are subjected to catalytic reaction in a catalyst bed, gas-phase products and lighter reaction products (namely naphtha fraction) are carried away upwards under the action of hydrogen stripping and are separated from a reaction system through a gas-phase channel 13, and heavier reaction products (namely diesel fraction) enter a next catalyst bed reaction zone downwards under the action of gravity.

The gas-phase product generated after the reactant in the hydrogenation reactor carries out chemical reaction in the catalyst bed layer can timely leave the reaction zone, and can not enter the upper catalyst bed layer again (isolated by the umbrella-shaped baffle plate), so that the secondary reaction of the target product is avoided, and the selectivity of the reaction is improved. Meanwhile, as the gas phase products in the reaction zone leave, the reaction driving force is increased, and the equilibrium conversion rate is improved. In addition, the gas phase product (H) produced by the hydrofining reaction ₂ O、H ₂ S、NH ₄ Etc.) and unreacted gas phase feed is separated from the catalyst bed reaction system and directly leaves the reactor through the gas phase channel withoutContact with the hydrofining/cracking catalyst bed layer, the adverse effect on the catalyst activity is reduced, and meanwhile, most of reaction heat can be taken away by timely separation of gas-phase products, so that the consumption of hydrogen is reduced.

Example 1

By adopting the flow chart shown in fig. 1, the raw oil is medium-low temperature coal tar, and the properties are shown in table 1. The coal tar raw material subjected to dehydration and impurity removal treatment firstly enters a prefractionator, is distilled and cut into coal tar light fraction and coal tar heavy fraction under normal pressure, the cutting point is 500 ℃, the cut light fraction is sent to a hydrogenation reactor 1 through a pipeline, the distillate oil quality of the light fraction is shown in table 2, the specific operation conditions of the hydrogenation reactor are shown in table 3, the hydrogenation reactor 1 is provided with 10 beds in total, wherein the upper 7 beds are filled with hydrofining catalyst, and the lower 3 beds are filled with hydrocracking catalyst. The hydrofining catalyst comprises 17wt% of molybdenum oxide, 5wt% of nickel oxide, the balance of silicon oxide carrier or aluminum oxide carrier, the pore volume of the hydrofining catalyst is 0.4mL/g, and the specific surface area is 185m ² /g; the hydrocracking catalyst comprises 8wt% of nickel oxide, 22wt% of tungsten oxide and the balance of a silica carrier or an alumina carrier; raw materials are in countercurrent contact with hydrogen in a hydrogenation reactor 1 to carry out hydrofining reaction at first, H generated by the reaction ₂ O,H ₂ S,NH ₄ The isogas phase products are separated from the catalyst bed layer and directly enter the independent gas phase channel of the invention, and the rest liquid phase products sequentially pass through all the refining beds and then enter the hydrocracking bed layer for hydrocracking reaction. The single-layer catalyst bed layer in the hydrogenation reactor is 200mm high. All gas phase products generated by the hydrogenation reactor are discharged from the top through a gas phase channel and enter a cold high pressure separator 200 after heat exchange, the operation temperature of the cold high pressure separator is 85 ℃, cold high pressure gas is purified by a desulfurization nitrogen purification device and then is mixed with new hydrogen to return to the hydrogenation reactor 1, cold high pressure oil and hydrogenation reactor liquid phase hydrogenation products are sent to a cold low pressure separator 300 together, the separated cold low pressure gas is discharged upwards, cold low pressure oil continues to enter a fractionating tower 400 for further separation, naphtha and diesel oil products are obtained, and unconverted oil at the bottom is returned to the hydrogenation reactor for further conversion. Operating conditions are shown in Table3：

Example 2

This example differs from example 1 in that the reaction zone in the hydrogenation reactor is charged with hydrofining catalyst at the upper 8 layers and hydrocracking catalyst at the lower 2 layers, and the operating conditions are shown in Table 3.

Example 3

This example differs from example 1 in that the system hydrogen partial pressure is 12MPa. The operating conditions are shown in Table 3.

Comparative example 1

Conventional fixed bed hydrofining is used to produce clean fuel oil.

TABLE 1 Properties of raw oil

Project	Data	Group composition, percent	Data
				Density, g/cm ³	1.0881	Saturation fraction	17.1
Viscosity/mm ² /s	26.8	Aromatic components	22.17
				Sulfur content, vol%	0.19	Colloid	46.01
Nitrogen content%	0.35	Asphaltenes	1.2
				Carbon residue value,%	6.12	Total metal, μg/g	115.44

TABLE 2 Pre-distillation light fraction oil Properties

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Table 3 operating conditions for examples and comparative examples

Table 4 product properties of examples and comparative examples

According to experimental results of the embodiment, by adopting the coal tar hydrotreatment device and the coal tar hydrotreatment method, water generated by the reaction can be effectively discharged from a gas phase channel and further separated in high-low fractions, so that the service life of the catalyst is ensured; can obtain clean fuel oil with higher quality, and improves the yield of naphtha compared with the traditional fixed bed hydrofining process.

The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. Any simple modifications, equivalent variations and modifications of the above-described exemplary embodiments should fall within the scope of the present invention.

Claims

1. A coal tar hydrotreater, comprising:

a prefractionator for fractionating the pretreated coal tar and obtaining light components;

a hydrogenation reactor which receives the prefractionated light component as a liquid phase feed which flows through each catalyst bed in turn from top to bottom; hydrogen uniformly enters from the bottom of each catalyst bed layer from bottom to top; the gas-phase product after hydrogenation reaction is discharged from the top of the reactor from an independent gas-phase channel;

a fractionation column that receives the hydroconverted cold low pressure oil and fractionates it into a clean fuel oil product.

2. The coal tar hydroprocessing apparatus according to claim 1, wherein said hydrogenation reactor comprises:

the catalyst beds are used for filling solid catalyst, and the upper part of the solid catalyst filled in each catalyst bed is provided with an inclined surface;

a liquid phase feed subunit disposed above the sloped surface of the topmost catalyst bed through which liquid phase feed is directed to the catalyst bed;

a hydrogen feed subunit disposed between the catalyst bed of a previous layer and the sloped surface of a next layer, the hydrogen feed of each layer being directed upwardly into the catalyst bed;

the independent gas phase channel is in a relative isolation state with the hydrogen feeding subunit, and the gas phase product generated after the reaction of the hydrogen and the liquid phase feeding in the catalyst bed layer directly enters the gas phase channel.

3. The coal tar hydroprocessing apparatus according to claim 2, wherein said inclined surface is integrally formed as an umbrella-shaped partition structure.

4. The coal tar hydroprocessing apparatus according to claim 3, wherein said umbrella-shaped partition ends with an annular downcomer having a bottom spaced from the bottom of said catalyst bed by a distance such that said liquid phase feed enters said catalyst bed in a radial direction.

5. The coal tar hydroprocessing apparatus according to claim 1, wherein said catalyst bed is provided with:

an overflow weir provided on a side close to the gas phase passage;

and the liquid sealing baffle is arranged at the upper part of the overflow weir and is used for isolating the hydrogen from the gas-phase product.

6. The coal tar hydroprocessing apparatus according to claim 5, wherein said liquid seal baffle comprises:

a horizontal portion having an annular flat plate shape and located above the overflow weir;

and the vertical part is cylindrical, the vertical part and the horizontal part are integrally formed, and the lower end of the vertical part is spaced from the bottom of the catalyst bed by a certain distance.

7. The coal tar hydroprocessing apparatus according to claim 4, wherein said liquid phase feed subunit further comprises:

a liquid phase feed tube extending in a radial direction of the hydrogenation reactor;

and the liquid phase distributing pipe is annular and is orthogonal or tangentially intersected with the liquid phase feeding pipe, and the pipe wall of the liquid phase distributing pipe is provided with a plurality of pore channels for uniformly distributing the liquid phase feeding materials to all directions of the annular downcomer.

8. The coal tar hydroprocessing apparatus according to claim 2, wherein said hydrogen feed subunit further comprises:

a hydrogen feed tube extending in a radial direction of the hydrogenation reactor;

and the hydrogen distribution pipe is annular or multi-layer concentric annular, is orthogonal or tangentially intersected with the hydrogen feeding pipe, and is provided with a plurality of pore channels on the wall surface for uniformly distributing the hydrogen feeding to all directions at the bottom of the catalyst bed.

9. The coal tar hydroprocessing device according to claim 8, wherein said hydrogen feed subunit further comprises:

the hydrogen distribution plate is positioned at the bottom of the catalyst bed and is in a disc shape as a whole, and a plurality of holes are uniformly distributed on the hydrogen distribution plate.

10. The coal tar hydroprocessing apparatus according to claim 1, wherein said gas phase channel is located in the middle of said hydrogenation reactor and runs through all catalyst beds from bottom to top.

11. The coal tar hydroprocessing apparatus according to claim 8, wherein the hydrogen distribution pipe is disposed below or within the catalyst bed.

12. The coal tar hydroprocessing apparatus according to claim 1, wherein the number of catalyst beds is two or more; each catalyst bed layer is filled with a hydrofining catalyst, or an upper layer is filled with a hydrofining catalyst, and a lower layer is filled with a hydrocracking catalyst; the void fraction of the catalyst bed is 0.5-85%, preferably 1-20%.

13. The coal tar hydrotreatment device according to claim 1, wherein the liquid phase product after hydrogenation flows to the bottom of the hydrogenation reactor, a liquid level monitoring unit is arranged at the bottom, and the discharge is stopped when the liquid level is lower than a set value.

14. The coal tar hydroprocessing apparatus according to claim 13, characterized in that said apparatus further comprises:

the cold high-pressure separator is used for receiving the gas-phase product discharged from the top of the hydrogenation reactor and hydrogen which is not reacted, separating cold high-pressure gas and cold high-pressure oil, and returning the Leng Gao gas after being purified to the hydrogenation reactor for recycling;

a cold low pressure separator that receives the liquid phase product from the bottom of the hydrogenation reactor and the Leng Gao pressure oil from the cold high pressure separator and separates cold low pressure gas and cold low pressure oil.

15. The coal tar hydrotreating process includes the following steps:

fractionating the pretreated coal tar to obtain light components;

the light component is used as liquid phase feed and flows through each catalyst bed layer of the hydrogenation reactor from top to bottom in sequence; hydrogen uniformly enters from the bottom of each catalyst bed layer from bottom to top; the gas-phase product after hydrogenation reaction is discharged from the top of the reactor from an independent gas-phase channel;

separating the gas phase product at a cold high pressure, obtaining cold high pressure oil and cold high pressure gas, purifying the Leng Gao gas and recycling;

carrying out cold low-pressure separation on the liquid phase product after hydrogenation reaction and Leng Gao pressure oil to obtain cold low-pressure oil;

fractionating the cold low pressure oil to produce a clean fuel oil product.

16. The coal tar hydroprocessing method according to claim 15, wherein said clean fuel oil products comprise naphtha and diesel.

17. The coal tar hydroprocessing method according to claim 15, characterized in that the operating conditions of the hydrogenation reaction are: the reaction temperature of the hydrogenation reactor is 300-450 ℃; the reaction pressure is 3MPa to 20MPa; the volume ratio of the hydrogen to the oil is 200:1-1500:1, preferably 500-1000; volume space velocity of 0.2h ^-1 ～2.0h ^-1 。

18. The coal tar hydroprocessing method according to claim 15, wherein the coal tar is at least one of low-temperature coal tar, medium-temperature coal tar, and medium-low-temperature coal tar.

19. The coal tar hydroprocessing method according to claim 15, characterized in that the hydrogen purity is 99.9%.