CN114763490B

CN114763490B - Catalytic diesel oil treatment process

Info

Publication number: CN114763490B
Application number: CN202110029100.7A
Authority: CN
Inventors: 仝玉军; 杨涛; 葛海龙; 孟兆会; 刘玲; 张文芳
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: 2021-01-11
Filing date: 2021-01-11
Publication date: 2023-04-07
Anticipated expiration: 2041-01-11
Also published as: CN114763490A

Abstract

The invention provides a catalytic diesel oil treatment process, which is characterized in that catalytic diesel oil is pretreated to obtain an aromatic hydrocarbon-rich material and an alkane-rich material, and the aromatic hydrocarbon-rich material is subjected to pretreatment agent recovery to obtain aromatic hydrocarbon fraction; the aromatic hydrocarbon fraction enters a fractionation unit and is separated to obtain a light fraction, a middle fraction and a heavy fraction; the heavy fraction enters a fixed bed hydrogenation reaction zone for reaction, liquid phase effluent, middle fraction and hydrogen obtained by the reaction enter a boiling bed hydrogenation reaction zone for reaction, the reaction effluent is separated to obtain a gas phase and a liquid phase, and the obtained liquid phase enters a fractionation unit for treatment. The treatment process realizes reasonable and efficient conversion of each component of the catalytic diesel oil, greatly reduces hydrogen consumption, remarkably improves the quality and yield of high value-added aromatic hydrocarbon products, and greatly improves the operation period of the device.

Description

Catalytic diesel oil treatment process

Technical Field

The invention belongs to the technical field of petrochemical industry, and particularly relates to a high-efficiency conversion process for catalyzing diesel oil.

Background

At present, the annual total processing capacity of a catalytic cracking device in China already exceeds 1.7 hundred million tons, the annual yield of the catalytic diesel reaches 3500 ten thousand tons. In recent years, on one hand, as the quality of crude oil becomes worse, the raw material processed by catalytic cracking also becomes heavier and poorer, so that the operation severity of a catalytic cracking unit is increased, and the quality of catalytic diesel oil is reduced; on the other hand, in order to reduce the content of gasoline olefin and simultaneously produce more propylene, MIP-CGP or FDFCC technologies are selected for a plurality of catalytic devices, but the technologies can further degrade the quality of catalytic diesel oil while producing more propylene and effectively reducing the gasoline olefin. Although the catalytic diesel oil of different enterprises has different properties, the catalytic diesel oil has common characteristics, namely high density, low cetane number and high aromatic hydrocarbon content, and the catalytic diesel oil becomes the most main bottleneck for realizing diesel oil quality upgrading with high efficiency and low consumption of the current oil refining enterprises. The hydrogenation technology of poor quality and high aromatic hydrocarbon catalytic diesel oil can be divided into hydrogenation refining technology, hydrogenation modification technology, hydrocracking technology and hydrogenation conversion technology according to different production purposes. For example, MQD (Maximum quality distillation) combined refining technology, MAK-LCO hydro-upgrading technology, hyCycle Unicracking technology and FD2G technology of petrochemical FRIPP of UOP company, different processing technologies are all used for converting poor-quality diesel oil into clean diesel oil products or gasoline and chemical products; at present, several processing technologies have certain market applications, but all have problems, mainly the problems that the product index is not required to be loaded, the hydrogen consumption is high and the economical efficiency is poor due to the fact that the content of the naphthenic hydrocarbon in the product is too high. Therefore, finding a high-efficiency, low-consumption and economic processing route for upgrading the quality of catalytic diesel as soon as possible is a technical problem which needs to be solved at present, and can greatly promote the physique of enterprises to be enhanced.

CN107286987A provides a combined process for treating poor diesel oil. Mixing the poor diesel oil raw material with hydrogen, then entering a fixed bed hydrogenation reaction zone, and carrying out hydrogenation reaction under the action of a hydrofining catalyst; and mixing the obtained reaction product oil with hydrogen, then feeding the mixture into a fluidized bed hydrocracking reaction zone, carrying out hydrocracking reaction in the presence of a fluidized bed hydrogenation conversion catalyst, and separating to obtain a product.

Disclosure of Invention

In order to solve the problems existing in the prior art, the invention mainly aims to provide a catalytic diesel oil treatment process, which is based on the concept of molecular oil refining, separates catalytic diesel oil according to different hydrocarbon components, and combines a pretreatment, fractionation and fixed bed-boiling bed hydrogenation combined process to treat different aromatic hydrocarbons in a catalytic diesel oil raw material by matching appropriate reaction paths, so that the technical problems of strong heat release, easy generation of hot spots, difficult control of reaction process, poor product quality and low yield and short device operation period in the hydrogenation conversion process caused by high aromatic hydrocarbon content and complex composition in the existing catalytic diesel oil treatment process are solved, reasonable and efficient conversion of each component of the catalytic diesel oil is realized, hydrogen consumption is greatly reduced, the quality and the yield of aromatic hydrocarbon products with high added values are remarkably improved, and the device operation period is greatly improved.

The invention provides a catalytic diesel oil treatment process, which comprises the following steps:

(1) Under the contact condition, catalytic diesel oil and a pretreating agent enter a pretreatment unit, and after full contact, the catalytic diesel oil and the pretreating agent are separated to obtain an aromatic hydrocarbon-rich material and an alkane-rich material;

(2) Under the separation condition, processing the aromatic hydrocarbon-rich material from the step (1), and separating to obtain an aromatic hydrocarbon fraction and a regeneration pretreating agent;

(3) Under the separation condition, the aromatic hydrocarbon fraction obtained in the step (2) enters a fractionation unit for separation, and a first gas, a light fraction, a middle fraction and a heavy fraction are obtained after separation;

(4) The heavy fraction obtained in the step (3) and hydrogen enter a fixed bed hydrogenation reaction zone for reaction, and a second gas and a liquid phase effluent are obtained after the reaction effluent is separated;

(5) And (3) feeding the liquid phase effluent obtained in the step (4), the middle distillate obtained in the step (3) and hydrogen into a fluidized bed hydrogenation reaction zone for reaction, separating the reaction effluent to obtain a gas phase and a liquid phase, and feeding the obtained liquid phase into the fractionating unit in the step (3) for treatment.

Further, in the above technical scheme, in the catalytic diesel oil in the step (1), the content of aromatic hydrocarbon is higher than 50wt%, and preferably, the content of aromatic hydrocarbon is 55wt% to 80wt%.

Further, in the above technical scheme, the pretreating agent in step (1) may be at least one selected from a sulfone compound, an aldehyde compound, an alkanone compound, an amide compound, and an ionic liquid, and is preferably a sulfone compound; the pretreating agent can be sulfolane, N-methylpyrrolidone, N-dimethylacetamide, caprolactam, [ emim]N(CN)2、[3-mebupy]N(CN) ₂ At least one of (1).

Further, in the above technical solution, the operation conditions of the pretreatment unit in step (1) are as follows: the temperature is 30-200 ℃, preferably 30-180 ℃, and the mass ratio of the pretreating agent to the catalytic diesel oil is 0.5-15.0, preferably 1.0-10.0.

Further, in the technical scheme, the cutting temperature of the light fraction and the middle fraction in the step (1) is 150-250 ℃, preferably 180-220 ℃; the cutting temperature of the middle fraction and the heavy fraction is 260-320 ℃, and preferably 290-310 ℃.

Further, in the above technical scheme, the light fraction in step (1) may be directly discharged from the apparatus as a product, and mainly comprises a monocyclic aromatic hydrocarbon component having a carbon number of C5 to C9, and specifically may include light aromatic hydrocarbons such as benzene, toluene, xylene, methyl ethyl benzene, mesitylene, and the like.

Further, in the above technical scheme, the fixed bed hydrogenation reaction zone may be provided with more than one fixed bed hydrogenation reactor, preferably 1 or 2 fixed bed hydrogenation reactors; n catalyst beds (n is an integer between 1 and 5 (such as 1, 2, 3, 4 and 5), preferably n is an integer between 2 and 4) are arranged in the fixed bed hydrogenation reactor, and specifically, the 1 st catalyst bed, the 2 nd catalyst bed, … …, the n-1 st catalyst bed and the n th catalyst bed are sequentially arranged according to the material flowing direction; preferably, each catalyst bed layer comprises a hydrofining catalyst and a hydrocracking catalyst, the hydrofining catalyst is arranged above the hydrocracking catalyst according to the material flowing direction, the loading amount of the hydrofining catalyst is gradually reduced according to the material flowing direction, and the loading amount of the hydrocracking catalyst is gradually increased.

Furthermore, in the above technical scheme, the i-th catalyst bed (i is not less than 1 and not more than n) is taken as an example for explanation, and the weight of the hydrofining catalyst in the i-th catalyst bed is expressed by M _i Expressed as weight of hydrocracking catalyst in the i-th catalyst bed N _i Shows that the filling weight ratio M of the hydrofining catalyst to the hydrocracking catalyst in the ith catalyst bed layer _i /N _i Is 5: 1 to 1: 5, preferably 3: 1 to 1: 3.

Further, in the above technical scheme, the hydrorefining catalyst may be a commercially available product, or may be prepared according to conventional knowledge in the art. The hydrofining catalyst takes alumina or silicon-containing alumina as a carrier, and the active component selects VIB group of Mo and/or W and/or VIII group metal of Co and/or Ni. Based on the weight of the catalyst, the content of the VIB group metal and the VIII group metal is respectively 7wt% -30 wt% and 3wt% -18 wt% calculated by oxides.

Further, in the above technical scheme, the hydrocracking catalyst may be a commercially available product, or may be prepared according to conventional knowledge in the art. The hydrocracking catalyst comprises a carrier and an active component, wherein the carrier comprises a molecular sieve and an optional inorganic oxide, and the molecular sieve is selected from one or more of a Y-type molecular sieve, a beta molecular sieve, an SBA-15 molecular sieve and an SAPO molecular sieve; the inorganic oxide can be one or more of aluminum oxide, silicon oxide and the like. The active metal is selected from one or more of VIII group metals and/or VIB group metals, and the VIII group metals are preferably Ni and/or Co; the group VIB metal is preferably W and/or Mo.

Further, in the above technical scheme, the ebullated-bed hydrogenation reaction zone may be provided with more than one ebullated-bed reactor, preferably with a three-phase separator disposed inside the reactor, and specifically may be an ebullated-bed reactor with a three-phase separator developed by the institute of petrochemical engineering, france, of the petrochemical industry, ltd.

In the catalytic diesel oil combined treatment process, the fluidized bed hydrogenation catalyst can be the existing diesel oil hydrogenation catalyst in the field, or can be prepared by the method disclosed by the prior art. Specifically, in the preferred fluidized bed hydrogenation catalyst, high-silicon aluminum oxide and a molecular sieve are used as carriers, a VIII group metal and a VIB group metal are used as active metal components, and the weight of the catalyst is taken as a reference, the content of the high-silicon aluminum oxide is 30-70%, the content of the molecular sieve is 10-50%, the content of the VIII group metal is 1-9% calculated by oxides, and the content of the VIB group metal is 10-30% calculated by oxides. The group VIII metal is preferably Ni and/or Co; the group VIB metal is preferably W and/or Mo; the molecular sieve is selected from one or more of Y-type molecular sieve, beta molecular sieve, ZSM-5 molecular sieve, SAPO molecular sieve and MCM-41 mesoporous molecular sieve.

Further, in the above technical scheme, the alkane-rich material fraction obtained in step (1) may be processed in a catalytic cracking unit, or may be used as a raw material for preparing olefins in steam cracking, catalytic cracking, or other units.

Further, in the above technical scheme, the process conditions of the fixed bed hydrogenation reaction zone in the step (4) are as follows: the reaction temperature is 330-440 ℃, the optimized temperature is 380-420 ℃, the reaction pressure is 5.0-20.0 MPa, the optimized pressure is 8.0-15.0 MPa, the volume ratio of hydrogen to oil is 500-2000, the optimized pressure is 600-1500, and the liquid hourly space velocity is 0.1-5.0 h ^-1 Preferably 0.2 to 2.0h ^-1 。

Further, in the above technical scheme, the middle distillate obtained in step (3) may enter a fixed bed hydrogenation reaction zone, preferably enter different catalyst beds through different inlets, and the mass flow rate of the middle distillate accounts for 0 to 20%, preferably 0 to 10%, of the mass flow rate of the corresponding catalyst bed.

Further, in the above technical solution, the process conditions of the ebullated bed hydrogenation reaction zone in the step (5) are as follows: the reaction temperature is 350-450 ℃, the preferential temperature is 380-440 ℃, the reaction pressure is 5.0-15.0 MPa, the preferential pressure is 8.0-18.0 MPa, the volume ratio of hydrogen to oil is 500-2000, the preferential pressure is 600-1500, and the liquid hourly space velocity is 0.1-5.0 h ^-1 Preferably 0.2 to 2.0h ^-1 。

Further, in the above technical solution, the pretreatment unit may be implemented by a solvent refining device or an aromatic hydrocarbon extraction device.

Further, in the above technical solution, the separation unit comprises a gas-liquid separator and optionally a fractionation column; the gas-liquid separator can comprise a high-pressure separator and a low-pressure separator, and the fractionating tower can be a fractionating tower existing in the field, and can be a plate tower or a packed tower.

Further, in the above technical scheme, the obtained first gas, second gas, and gas phase may enter a membrane separation unit and/or a pressure swing adsorption unit for hydrogen purification, and the purified hydrogen may be used in a fixed bed hydrogenation reaction zone and/or a boiling bed hydrogenation reaction zone.

Compared with the prior art, the catalytic diesel oil treatment process has the following advantages:

1. the catalytic diesel oil treatment process provided by the invention is based on the concept of molecular oil refining, and organically combines physical separation (pretreatment and distillation) and chemical conversion (fixed bed-boiling bed combined hydrogenation) to realize that different types of molecules are subjected to zone reaction according to ideal controllable reaction paths, so that the aim of' alkene is suitable and arene is suitable is achieved, alkane and arene in catalytic diesel oil are respectively converted, alkane-rich components, cycloalkane-rich components and the like are used as raw materials of a catalytic cracking device for converting to generate alkene, and bicyclic and polycyclic arene directional hydrogenation is carried out to convert monocyclic arene components with high added value and with BTX as the main component to the maximum extent.

2. The catalytic diesel oil treatment process provided by the invention adopts a fixed bed-boiling bed combined hydrogenation process, a fixed bed hydrogenation reaction zone adopts a catalyst grading scheme, and the refining and cracking processes of catalyst bed layers are alternately arranged on the basis of polycyclic aromatic hydrocarbon ring-by-ring hydrogenation characteristics and a cracking process carbonium ion theory to realize gradual cracking reaction of aromatic hydrocarbon molecules; the cascade catalyst grading can be well carried out at a beta position in the polycyclic aromatic hydrocarbon bond breaking process, and the dry gas yield can be effectively reduced.

3. In the catalytic diesel oil treatment process provided by the invention, the boiling bed hydrogenation technology is adopted, the full back-mixing characteristic can be utilized, the temperature and the pressure in a reaction space are the same, and the state difference of gas-liquid-solid three phases in a reactor exists (hydrogen exists in a dispersed phase, and the hydrogen bubbles are required to contact with a catalyst in the hydrogenation reaction process), so that the control of a reaction path is facilitated; for a high aromatic hydrocarbon heat release system such as catalytic diesel oil, the generation of hot spots can be effectively avoided.

4. In the catalytic diesel oil treatment process provided by the invention, the middle fraction obtained by the fractionation unit enters the fixed bed hydrogenation reaction zone, so that the reaction temperature can be favorably controlled, the cold hydrogen dosage can be effectively reduced, the hydrogenation supersaturation caused by the increase of the hydrogen-oil ratio after the cold hydrogen is added can be neutralized to a certain extent, and the hydrogenation depth can be effectively controlled.

5. In the catalytic diesel oil treatment process provided by the invention, through a pretreatment, fractionation and fixed bed-boiling bed hydrogenation combined process, the fractionation unit not only plays a role in separating the subsequent feeding materials of a fixed bed hydrogenation reaction zone and a boiling bed hydrogenation reaction zone, but also can reduce the liquid phase separation obtained in the boiling bed hydrogenation reaction zone to obtain a target product, and seems to be obtained only by changing the position of a fractionation tower, but a good technical effect is brought, one fractionation tower can be omitted, and the investment and operation cost of the device is greatly reduced.

Drawings

FIG. 1 is a schematic view of a catalytic diesel fuel treatment process provided by the present invention.

FIG. 2 is a schematic view of the catalyst gradation in the fixed-bed hydrogenation reaction zone according to the present invention.

Detailed Description

The technical features of the present invention will be further described by way of examples with reference to the accompanying drawings, but the present invention is not limited to these examples. In the present invention,% is generally a weight percentage.

As shown in figure 1, the invention provides a catalytic diesel oil treatment process, wherein catalytic diesel oil 1 and a pretreating agent 2 enter a pretreatment unit 3, are fully contacted and separated to obtain a material 5 rich in aromatic hydrocarbon and a material 4 rich in alkane; the obtained material rich in aromatic hydrocarbon enters a pretreatment agent recovery unit 6, an aromatic hydrocarbon fraction 8 and a regeneration pretreatment agent 7 are obtained after separation, and the regeneration pretreatment agent 7 can be recycled by the pretreatment unit 3; the obtained aromatic hydrocarbon fraction 8 enters a fractionation unit 9, and a first gas 10, a light fraction 11, a middle fraction 12 and a heavy fraction 13 are obtained after separation; wherein, the heavy fraction 13 and hydrogen 19 enter a fixed bed hydrogenation reaction zone 14, and carry out hydrogenation reaction under the action of a fixed bed hydrogenation catalyst and hydrogen to generate a fixed bed hydrogenation reaction effluent 15; separating the obtained fixed bed hydrogenation reaction effluent 15 by a gas-liquid separator 16 to obtain a second gas 17 and a liquid phase effluent 18; the liquid phase effluent 18, the middle distillate 12 and the hydrogen 19 enter a fluidized bed hydrogenation reaction zone 20, react under the action of a fluidized bed hydrogenation catalyst and the hydrogen to generate a fluidized bed hydrogenation reaction effluent 21, the fluidized bed hydrogenation reaction effluent 21 enters a separation unit, the separation unit comprises a high-pressure separator 22 and a low-pressure separator 23 which are connected in series, gas 24 and a liquid phase material 25 are obtained after separation by the high-pressure separator 22, the liquid phase material 25 further enters the low-pressure separator 23 to be separated to obtain a dry gas 26 and a liquid phase 27, and the obtained liquid phase 27 enters a fractionation unit 9 for circulation treatment.

The basic properties of the catalyzed diesel fuels used in the inventive and comparative examples are shown in Table 1.

TABLE 1 basic Properties of catalytic Diesel

Example 1

The embodiment is carried out by adopting the process flow chart shown in fig. 1, catalytic diesel oil enters a pretreatment unit, wherein the pretreatment unit is set as an aromatic hydrocarbon extraction device, an extracting agent is sulfolane, the extraction temperature is 160 ℃, and the mass ratio of the agent to the oil is 13.0; and (3) introducing the extracted aromatic-rich component into a fractionation unit, wherein the dry point temperatures of the light fraction and the middle fraction are 200 ℃ and 300 ℃ respectively. The hydrogenation refined catalyst and the cracking catalyst in the fixed bed respectively adopt FFT-1B and FC-70 catalysts developed by the institute of petrochemical industry, dalian, petrochemical industry, inc. of China, the fixed bed is provided with 4 beds (as shown in figure 2, the same below), the weight ratio of the FFT-1B and the FC-70 catalysts from the 1 st bed to the 4 th bed is respectively 3: 1, 2: 1, 1: 1 and 1: 2, the average temperature of a hydrogenation reaction zone of the fixed bed is 390 ℃, the reaction pressure is 10.0MPa, the hydrogen-oil ratio is 600, and the liquid hourly volume space velocity is 1.0 h ^-1 (ii) a The fluidized bed catalyst is selected from FC-70 catalyst which is subjected to crushing treatment (crushed into short strips of 0.5-1.0 mm) and developed by the institute of petrochemical engineering, dalian of the China petrochemical industry, inc., the temperature of a hydrogenation reaction zone of the fluidized bed is 415 ℃, the reaction pressure is 10.0MPa, the hydrogen-oil ratio is 600, and the liquid hourly volume space velocity is 0.8 h ^-1 (ii) a The specific test results are shown in Table 2.

Example 2

This example was carried out using the process flow diagram shown in FIG. 1, with the catalyzed diesel entering the pretreatment unit, which was set as an aromatics extraction unit, and the extractant was N-methylPyrrolidone, the extraction temperature is 160 ℃, and the mass ratio of solvent to oil is 10.0; the extracted aromatic-rich component enters a fractionation unit, and the dry point temperatures of the light fraction and the middle fraction are 180 ℃ and 290 ℃ respectively. The hydrogenation refined catalyst and the cracking catalyst in the fixed bed respectively adopt FFT-1B and FC-70 developed by the institute of petrochemical engineering of Dalian, petrochemical engineering, inc. of China, the fixed bed is provided with 4 beds (as shown in figure 2), the weight ratio of the FFT-1B and the FC-70 catalyst from the 1 st bed to the 4 th bed is respectively 3: 1, 2: 1, 1: 1 and 1: 2, the average temperature of the hydrogenation reaction zone of the fixed bed is 400 ℃, the reaction pressure is 10.0MPa, the hydrogen-oil ratio is 800, and the liquid hourly volume space velocity is 1.2 h ^-1 (ii) a The fluidized bed catalyst is selected from FC-70 catalyst which is subjected to crushing treatment (crushing into short strips of 0.5-1.0 mm) and developed by the institute of petrochemical engineering, large-connecting petrochemical research of China petrochemical industry, inc., the temperature of a hydrogenation reaction zone of the fluidized bed is 420 ℃, the reaction pressure is 10.0MPa, the hydrogen-oil ratio is 600, and the liquid hourly space velocity is 0.5 h ^-1 (ii) a The specific test results are shown in Table 2.

Comparative example 1

The main difference between the comparative example and the invention is that the fixed bed hydrogenation unit catalyst is not graded and filled, only the refined catalyst FFT-1B is filled, the total height of the catalyst bed is the same as that of the example 1, the other flow is the same as that of the example 1, the catalytic diesel oil 1 and the pretreating agent 2 enter the pretreatment unit 3, and the materials are fully contacted and separated to obtain the material 5 rich in aromatic hydrocarbon and the material 4 rich in alkane; the obtained material rich in aromatic hydrocarbon enters a pretreatment agent recovery unit 6, and is separated to obtain an aromatic hydrocarbon fraction 8 and a regeneration pretreatment agent 7, and the regeneration pretreatment agent 7 can be recycled by the pretreatment unit 3; the obtained aromatic hydrocarbon fraction 8 enters a fractionation unit 9, and a first gas 10, a light fraction 11, a middle fraction 12 and a heavy fraction 13 are obtained after separation; wherein, the heavy fraction 13 and hydrogen 19 enter a fixed bed hydrogenation reaction zone 14, and carry out hydrogenation reaction under the action of a fixed bed hydrogenation catalyst and hydrogen to generate a fixed bed hydrogenation reaction effluent 15; separating the obtained fixed bed hydrogenation reaction effluent 15 by a gas-liquid separator 16 to obtain a second gas 17 and a liquid phase effluent 18; the liquid phase effluent 18, the middle distillate 12 and the hydrogen 19 enter a fluidized bed hydrogenation reaction zone 20, react under the action of a fluidized bed hydrogenation catalyst and the hydrogen to generate a fluidized bed hydrogenation reaction effluent 21, the fluidized bed hydrogenation reaction effluent 21 enters a separation unit, the separation unit comprises a high-pressure separator 22 and a low-pressure separator 23 which are connected in series, the high-pressure separator 22 separates the effluent to obtain a gas 24 and a liquid phase material 25, the liquid phase material 25 further enters the low-pressure separator 23 to separate the liquid phase material to obtain a dry gas 26 and a liquid phase 27, and the obtained liquid phase 27 enters a fractionation unit 9 for circular treatment. The specific data are shown in Table 2.

Comparative example 2

The main difference between the comparative example and the invention is that the fractionation unit 9 is arranged behind the boiling bed hydrogenation unit, and the pretreated aromatic-rich component of the catalytic diesel oil directly enters the fixed bed hydrogenation unit. The main process flow of the comparative example 2 is that the catalytic diesel oil 1 enters a pretreatment unit 3, contacts with a pretreatment agent 2 and is separated to obtain an aromatic hydrocarbon-rich component 5 and an alkane-rich component 6; the obtained aromatic hydrocarbon-rich component enters a pretreatment agent recovery unit 6, and is separated to obtain a regeneration pretreatment agent 7 and an aromatic hydrocarbon fraction 8, wherein the regeneration pretreatment agent 7 is recycled to be used by the pretreatment unit; the obtained aromatic hydrocarbon fraction 8 and hydrogen enter a fixed bed hydrogenation reaction zone 14 to react to generate a first reaction effluent 15; separating the effluent 15 by a gas-liquid separator 16 to obtain a second gas 17 and a liquid phase effluent 18; the liquid phase effluent 18 and hydrogen enter a fluidized bed hydrogenation reaction zone 20, and react under the action of a fluidized bed hydrogenation catalyst and hydrogen to generate a fluidized bed hydrogenation reaction effluent 21, the fluidized bed hydrogenation reaction effluent 21 enters a separation unit, the separation unit comprises a high-pressure separator 22 and a low-pressure separator 23 which are connected in series, the high-pressure separator 22 separates the fluidized bed hydrogenation reaction effluent 21 to obtain a gas 24 and a liquid phase material 25, the liquid phase material 25 further enters the low-pressure separator 23 to separate the liquid phase material 25 to obtain a dry gas 26 and a liquid phase 27, and the obtained liquid phase 27 enters a fractionation unit 9 for treatment and separation to obtain a first gas 10, a light fraction 11 and a heavy fraction 28.

The pretreatment unit conditions, fixed bed reaction zone and ebullated bed reaction zone catalysts and process conditions were the same as in example 1. The specific test results are shown in Table 2.

TABLE 2 Hydrocarbon composition of catalytic Diesel hydroconversion product (stream 10)

Claims

1. A catalytic diesel treatment process, comprising:

(3) Under the separation condition, the aromatic hydrocarbon fraction obtained in the step (2) enters a fractionation unit for separation, and a first gas, a light fraction, a middle fraction and a heavy fraction are obtained after separation; the middle fraction enters a fixed bed hydrogenation reaction zone, and the mass flow of the middle fraction accounts for 0-20% of the mass flow of the corresponding catalyst bed layer;

(4) The heavy fraction obtained in the step (3) and hydrogen enter a fixed bed hydrogenation reaction zone for reaction, and a second gas and a liquid phase effluent are obtained after the reaction effluent is separated; the technological conditions of the fixed bed hydrogenation reaction zone are as follows: the reaction temperature is 330-440 ℃, the reaction pressure is 5.0-20.0 MPa, the volume ratio of hydrogen to oil is 500-2000, and the liquid hourly space velocity is 0.1-5.0 h ^-1 ；

(5) The liquid phase effluent obtained in the step (4), the middle distillate obtained in the step (3) and hydrogen enter a fluidized bed hydrogenation reaction zone for reaction, the reaction effluent is separated to obtain a gas phase and a liquid phase, and the obtained liquid phase enters the fractionating unit in the step (3) for treatment; the process conditions of the fluidized bed hydrogenation reaction zone are as follows: the reaction temperature is 350-450 ℃, the reaction pressure is 5.0-15.0 MPa, the volume ratio of hydrogen to oil is 500-2000, and the liquid hourly space velocity is 0.1-5.0 h ^-1 ；

The fixed bed hydrogenation reaction zone is provided with more than one fixed bed hydrogenation reactor, n catalyst beds are arranged in the fixed bed hydrogenation reactor, n is an integer between 1 and 5, and the 1 st catalyst bed, the 2 nd catalyst bed, … …, the n-1 st catalyst bed and the n th catalyst bed are sequentially arranged according to the material flowing direction; each catalyst bed layer comprises a hydrofining catalyst and a hydrocracking catalyst, the hydrofining catalyst is arranged above the hydrocracking catalyst according to the material flowing direction, the loading amount of the hydrofining catalyst is gradually reduced according to the material flowing direction, and the loading amount of the hydrocracking catalyst is gradually increased; the hydrocracking catalyst comprises a carrier and an active component, wherein the carrier comprises a molecular sieve and an optional inorganic oxide, and the molecular sieve is selected from one or more of a Y-type molecular sieve, a beta molecular sieve, an SBA-15 molecular sieve and an SAPO molecular sieve; the inorganic oxide is one or more of aluminum oxide and silicon oxide; the active metal is selected from one or more of VIII group metals and/or VIB group metals.

2. The process of claim 1, wherein: in the step (1), the content of aromatic hydrocarbon in the catalytic diesel oil is higher than 50wt%.

3. The process of claim 1, wherein: in the step (1), the content of aromatic hydrocarbon in the catalytic diesel oil is 55-80 wt%.

4. The process of claim 1, wherein: in the step (1), the pretreating agent is selected from at least one of sulfone compounds, aldehyde compounds, alkanone compounds, amide compounds and ionic liquid.

5. The process of claim 1, wherein: the pretreatment agent in the step (1) is selected from sulfones compounds.

6. The process according to claim 1 or 4, wherein: the pretreating agent in the step (1) is sulfolane, N-methyl pyrrolidone, N-dimethyl acetamide, caprolactam and [ emim]N(CN) ₂ 、[3-mebupy]N(CN) ₂ At least one of (1).

7. The process of claim 1, wherein: the operation conditions of the pretreatment unit in the step (1) are as follows: the temperature is 30-200 ℃, and the mass ratio of the pretreating agent to the catalytic diesel oil is 0.5-15.0.

8. The process of claim 1, wherein: the operation conditions of the pretreatment unit in the step (1) are as follows: the temperature is 30-180 ℃, and the mass ratio of the pretreating agent to the catalytic diesel oil is 1.0-10.0.

9. The process of claim 1, wherein: in the step (1), the cutting temperature of the light fraction and the middle fraction is 150-250 ℃, and the cutting temperature of the middle fraction and the heavy fraction is 260-320 ℃.

10. The process of claim 1, wherein: the cutting temperature of the light fraction and the middle fraction in the step (1) is 180-220 ℃; the cutting temperature of the middle fraction and the heavy fraction is 290-310 ℃.

11. The process of claim 1, wherein: the fixed bed hydrogenation reaction zone is provided with 1 or 2 fixed bed hydrogenation reactors; and n catalyst beds are arranged in the fixed bed hydrogenation reactor, wherein n is an integer between 2 and 4.

12. The process of claim 1, wherein: the VIII group metal is Ni and/or Co; the group VIB metal is W and/or Mo.

13. The process of claim 1, wherein: and (2) the alkane-rich material obtained in the step (1) enters a catalytic cracking device for treatment, or is used as a raw material for preparing olefin by a steam cracking device and a catalytic cracking device.

14. The process of claim 1, wherein: the process conditions of the fixed bed hydrogenation reaction zone in the step (4) are as follows: the reaction temperature is 380-420 ℃, the reaction pressure is 8.0-15.0 MPa, the volume ratio of hydrogen to oil is 600-1500, and the liquid hourly space velocity is 0.2-2.0 h ^-1 。

15. The process of claim 1, wherein: and (4) allowing the middle distillate obtained in the step (3) to enter different catalyst beds in a fixed bed hydrogenation reaction zone through different inlets, wherein the mass flow of the middle distillate accounts for 0-10% of the mass flow of the corresponding catalyst beds.

16. The process of claim 1, wherein: the process conditions of the boiling bed hydrogenation reaction zone in the step (5) are as follows: the reaction temperature is 380-440 ℃, the reaction pressure is 8.0-18.0 MPa, the volume ratio of hydrogen to oil is 600-1500, and the liquid hourly space velocity is 0.2-2.0 h ^-1 。

17. The process of claim 1, wherein: the pretreatment unit adopts a solvent refining device or an aromatic hydrocarbon extraction device.