A fluidized bed-fixed bed combined hydroprocessing process and processing system

Abstract

The present invention discloses a combined ebullated bed-fixed bed hydroprocessing process and a processing system, wherein the heated hydrocarbon-containing raw material enters an ebullated bed hydrogenation reaction unit, reacts under the action of hydrogen and an ebullated bed hydrogenation catalyst, and obtains a gas phase first stream and a liquid phase second stream after reaction and separation; the obtained liquid phase second stream enters a stabilization unit, and the 22nd stream obtained by stabilization treatment and separation and hydrogen enter a fixed bed hydrogenation reaction unit, reacts under the action of a fixed bed hydroprocessing catalyst, and the reaction effluent is separated to obtain a target product. The present invention also provides an ebullated bed-fixed bed combined hydroprocessing system including an ebullated bed hydrogenation reaction unit, a stabilization unit, a fixed bed hydrogenation reaction unit, and a separation unit. The combined process greatly improves the operating stability of the fixed bed hydrogenation reaction unit, solves the problem of mismatching the operating cycle of the fixed bed hydrogenation reaction unit and the ebullated bed hydrogenation reaction unit, greatly improves the operating cycle of the entire hydrogenation unit, reduces the number of shutdowns during the overhaul cycle, and realizes the upgrading of hydrogenation technology.

Description

Technical Field

[0001] The invention belongs to the field of oil refining and chemical industry, and relates to a combined hydrogenation method, in particular to a combined hydrogenation method of a boiling bed and a fixed bed. Background Art

[0002] Fixed-bed residue oil hydrogenation technology is an important means of heavy oil processing. It is favored by refineries due to its good treatment effect and high technical maturity. With the increasing trend of inferior and heavy raw materials, the shortcomings of fixed-bed residue oil hydrogenation technology have gradually emerged, mainly in the following aspects: (1) The limitations of processing inferior raw materials. Due to factors such as catalyst activity and catalyst bed pressure drop, in order to ensure the operation cycle of the device, it is usually necessary to control the total metal content of the fixed-bed raw oil to less than 150μg / g, the carbon residue to less than 15wt%, and the asphaltene content to less than 5wt%. When the fixed-bed hydrogenation process is used to treat inferior raw materials with high metal and carbon residue content, the catalyst coking and deactivation rate is relatively fast; at the same time, the catalyst bed is easily blocked by coke and metal organic matter, causing a rapid increase in pressure drop. In addition, at the end of operation, due to uneven distribution of bed logistics, bed hot spots and radial temperature differences will also occur, which will eventually shorten the operation cycle of the fixed-bed device. (2) The short operation cycle of the device has become an important factor restricting the further development of fixed-bed residue oil hydrogenation technology. On the one hand, the fixed-bed residue oil hydrotreating unit has a low air velocity and a short catalyst life, and the catalyst cannot be replaced online; on the other hand, during operation, as the operating temperature increases and the amount of coke deposits on the catalyst bed increases, the pressure difference and radial temperature difference in the catalyst bed protecting the reactor will increase, affecting the continued temperature increase of the unit, which in turn leads to the catalyst activity of other reactors or beds not being fully utilized, ultimately causing unplanned shutdown of the unit and wasting the corresponding catalyst activity in subsequent fixed-bed reactors.

[0003] Prolonging the stable operation cycle of the unit is an important development direction of fixed-bed residue oil hydrotreating technology. For this purpose, domestic and foreign researchers have carried out a lot of research work on new process development, catalyst preparation and grading system research and development. A typical example is the UFR protection reactor technology developed by CLG. The catalyst in the UFR protection reactor is in a micro-expansion state, but there are still problems such as radial temperature difference at the end of operation that cannot be solved.

[0004] The ebullated bed hydrogenation technology is also one of the hydrogenation processes successfully used in the industry to treat heavy oil. The ebullated bed reactor used in it is a fluidized bed reactor. The interior of the reactor is in an approximately full backmixing state and the temperature distribution is uniform, which is conducive to better mass and heat transfer between the materials inside the reactor. With the effective regulation of the key physical properties of the ebullated bed catalyst, such as the pore size and pore volume, the depolymerization of asphaltene macromolecules in the residual oil raw material can be well achieved, and metals such as Ni and V can be efficiently removed, solving the two major problems of asphaltene conversion and metal removal faced by traditional residual oil hydrogenation technology. At the same time, the ebullated bed reactor helps to solve problems such as bed pressure drop and hot spots. The setting of the online addition and discharge system can timely replace part of the catalyst according to the changes in the catalyst activity in the ebullated bed reactor. By adjusting the addition and discharge amount and the addition and discharge frequency of the catalyst, the overall activity of the catalyst in the reactor can be artificially adjusted, thereby adjusting the product properties.

[0005] Patent CN101591563A discloses a combined process of ebullating bed hydrogenation and fixed bed hydrogenation, the combined process includes at least one three-phase ebullating bed reactor and at least one fixed bed reactor, the feedstock oil is mixed with hydrogen and then enters the three-phase ebullating bed reactor, where it contacts with a hydrogenation catalyst for hydrogenation reaction, the gas phase and liquid phase products from the three-phase ebullating bed reactor are treated separately, the gas phase product produced by the ebullating bed hydrogenation reaction is heat exchanged and cooled to 40-60°C, and then enters a cold high-pressure separator for gas-liquid separation, and the cold high-pressure separation obtains After the gas phase is desulfurized, heat is exchanged again, one way enters the light oil fixed bed hydrogenation reactor together with the cold high-fraction liquid phase, and the other way is mixed with the liquid phase produced by the ebullating bed reaction to enter the heavy oil fixed bed reactor for hydrogenation reaction, or the desulfurized gas phase enters the heavy oil fixed bed reactor together with the cold high-fraction liquid phase and the liquid phase produced by the ebullating bed reaction for hydrogenation reaction, and finally enters the fractionation tower for fractionation to obtain light products and gas phase, which are recycled after gas phase desulfurization; in this patented technology, filtering facilities need to be set at the outlet of the ebullating bed reactor to intercept possible solid particles. The problem with this process is that the outlet of the ebullating bed reactor is under harsh conditions of high temperature and high pressure, and the ebullating bed reactor is in full back-mixing mode, and there is a "short circuit" of materials. Filtering facilities are set at the outlet of the reactor. When the device fluctuates, it is easy to cause the filter facilities to be blocked due to the loss of solid catalyst particles; in addition, the current ebullating bed reactor adopts a high conversion rate operation mode when processing inferior raw materials. The coke produced during the deep conversion of inferior residual oil is also very easy to cause filter blockage, which will seriously affect the safe operation of the device and long-term stable operation. Summary of the invention

[0006] The applicant has conducted long-term and extensive research in the field of ebullating bed-fixed bed combined hydrogenation technology, and some of the results have been applied in industry, such as the 500,000 tons / year coal tar ebullating bed hydrogenation and upgrading device of a chemical company in Shaanxi. During the research and development and application process, it was found that some phenomena occurring in actual operation were not completely consistent with the common understanding. The general understanding of those skilled in the art is that when the inferior raw materials are first pretreated with an ebullating bed and then enter the fixed bed for deep treatment, the fixed bed reactor should be more stable in operation, and the problem of frequent hot spots in the first reactor of the fixed bed when directly treating inferior raw materials, which in turn causes the bed layer pressure drop to increase rapidly and the stability is insufficient, should not occur. However, it was found in the study that the practical results were not completely consistent with the above understanding. After the gas phase and liquid phase materials after the ebullating bed reaction were directly introduced into the fixed bed reactor, the hot spots and pressure drop problems of the first reactor of the fixed bed reactor system were weakened to a certain extent, but they were not completely eliminated, and the expected goals were not achieved. In response to the hot spots and pressure drop problems of the fixed bed reactor that occurred during the research of the ebullated bed-fixed bed combined hydrogenation process, as well as the long-term stable operation of the entire device affected by the mismatch between the operating cycles of the fixed bed and the ebullated bed, the applicant proposed a new ebullated bed-fixed bed combined hydrogenation treatment process in which a stabilization unit is arranged between the ebullated bed hydrogenation reaction unit and the fixed bed hydrogenation reaction unit. On the one hand, this process route solves the problem of poor operating stability of the fixed bed hydrogenation reaction unit caused by the occurrence of bed hot spots and pressure drop, and greatly improves the operating stability of the fixed bed hydrogenation reaction unit; on the other hand, it solves the problem of mismatch between the operating cycles of the fixed bed hydrogenation reaction unit and the ebullated bed hydrogenation reaction unit, and greatly improves the operating cycle of the entire hydrogenation device, reduces the number of shutdowns during the maintenance cycle, and realizes the upgrading of hydrogenation technology.

[0007] The first aspect of the present invention aims to provide a fluidized bed-fixed bed combined hydroprocessing process, comprising the following steps:

[0008] (1) The heated hydrocarbon-containing feedstock enters an ebullated bed hydrogenation reaction unit, reacts under the action of hydrogen and an ebullated bed hydrogenation catalyst, and after the reaction, is separated by a three-phase separator inside an ebullated bed reactor to obtain a first gaseous stream from the top of the reactor and a second liquid stream discharged from a liquid phase overflow outlet on the side wall of the reactor cylinder at an upper part of the reactor and lower than the outlet position of the first gaseous stream;

[0009] (2) The second material stream obtained in step (1) enters a stabilization unit, is stabilized and separated to obtain a gas phase 21 material stream and a liquid phase 22 material stream;

[0010] (3) The gas phase No. 21 material stream obtained in step (2), the supplemental hydrogen and the liquid phase No. 22 material stream are mixed and then enter the fixed bed hydrogenation reaction unit to react under the action of the fixed bed hydrogenation catalyst. The reaction effluent is separated to obtain the target product.

[0011] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the ebullated bed hydrogenation reaction unit is provided with at least one ebullated bed reactor, and the ebullated bed reactor is an ebullated bed reactor with a built-in three-phase separator, and the ebullated bed reactor can specifically be one or more of ZL 200710012680.9, ZL 200810012191.8, etc. The ebullated bed reactor with a three-phase separator can achieve the preliminary separation of the gas, liquid and solid three phases in the material flow obtained after the reaction through the three-phase separator inside the reactor, the gas phase is generally discharged through the gas phase outlet at the top of the reactor for treatment, and the liquid phase is generally discharged through the liquid phase outlet provided on the side wall of the reactor for subsequent treatment, and the solid phase catalyst obtained after separation is circulated and used inside the ebullated bed reactor.

[0012] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the conversion rate of the ebullated bed hydrogenation reaction unit is generally not higher than 40% (such as 40%, 35%, 30%, etc.), preferably not higher than 24% (such as 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, etc.), and further preferably not higher than 15% (such as 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, etc.). The purpose of setting up the ebullated bed hydrogenation reaction unit is not to pursue a high conversion rate of the raw material and to convert the maximum amount into the target product (such as clean fuel oil (gasoline, diesel, kerosene, etc.) or aromatics, etc.), but the core goal is to pre-treat the raw material by hydrogenation to remove various metal impurities, with the goal of producing a fixed bed feed that meets the requirements. Different from the prior art which uses an ebullated bed for hydroprocessing, in the existing ebullated bed hydroprocessing process, the ebullated bed reactor generally needs to be operated at a high conversion rate (generally higher than 55%, preferably higher than 60%, more preferably higher than 70% (such as 70%, 75%, 80%, 85%, 90%, etc.) to ensure the maximum amount of various target products.

[0013] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the ebullated bed hydroprocessing reaction unit controls the conversion depth to be no higher than 15%. Due to the different sizes and structures of different components in the residual oil system, their hydrogenation reaction rates are also different. In the traditional ebullated bed hydrogenation technology route, the ebullated bed reactor usually adopts a high conversion rate operation mode (the conversion rate is generally higher than 55%). The different reaction rates of different components will cause the content and structure of different components in the system to change, which will destroy the original stable system state, cause the precipitation of macromolecules such as asphaltene, and then cause coking, etc., which is very likely to cause the hydrogenation device in the subsequent fixed bed hydrogenation reaction unit to have problems such as bed coking and increased pressure drop. In the technical solution provided in this application, the ebullated bed hydrogenation reaction unit only needs to remove metals and asphaltene that have a greater impact on the fixed bed reaction. It does not pursue deep conversion, but needs to strictly control the conversion depth of the ebullated bed hydrogenation reaction unit to ensure that the ebullated bed hydrogenation reaction product will not show a decrease in stability during the subsequent fixed bed hydrogenation deep treatment process, and avoid the problem of increased bed pressure drop in the subsequent fixed bed reactor when the subsequent fixed bed hydrogenation reaction unit performs hydrogenation reaction due to poor stability of the ebullated bed reaction product. This is also one of the important differences between this technical route and the conventional ebullated bed-fixed bed combination technology.

[0014] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the stabilization unit is provided with at least one stabilization tank, the design operating conditions of the stabilization tank are the same as the operating conditions of the ebullated bed reactor (same pressure and temperature), the stabilization tank can be a vertical tank and / or a horizontal tank, preferably a horizontal tank; further preferably, the lower part of the stabilization tank adopts a conical design. It is further preferred that an internal component is provided inside the stabilization tank, and the internal component can be a baffle, which can be used to effectively intercept scale and prevent the scale from being brought into the subsequent fixed bed reactor.

[0015] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the design operating conditions of the stabilization tank are the same as the operating conditions of the ebullating bed reactor (same pressure and temperature), and the gas phase separated by the stabilization tank is mixed with the liquid phase and supplementary hydrogen as the feed of the subsequent fixed bed reactor. The gas phase separated by the stabilization tank (mainly light hydrocarbons corresponding to naphtha and light diesel) is mixed with the separated liquid phase, and the whole fraction is used as the feed of the fixed bed hydrogenation reaction unit. On the one hand, the gas phase and the liquid phase are mixed at the inlet of the fixed bed reactor instead of mixing in the front pipeline, which helps to avoid the fluctuation of the fixed bed feed caused by the compressibility of the gas phase, and helps to improve the feed stability of the fixed bed reactor and improve the operation stability of the device; on the other hand, it helps to reduce the feed viscosity of the fixed bed hydrogenation reaction unit, and helps to increase the diffusion rate of the reaction raw materials, especially the diffusion rate in the catalyst pores, thereby improving the fixed bed hydrogenation reaction effect.

[0016] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the stabilization tank in the stabilization unit is provided with at least one feed port and two discharge ports; the two discharge ports are respectively recorded as the first discharge port and the second discharge port; wherein, the feed port is used to receive the liquid phase second material flow from the ebullated bed hydrogenation reaction unit; the first discharge port is used to discharge the 21st material flow, and the second discharge port is used to discharge the 22nd material flow. Furthermore, the feed port is arranged on the tank body of the stabilization tank, the first discharge port is arranged at the top of the stabilization tank or the upper part of the tank body on the other side of the stabilization tank relative to the direction of the feed port, and the second discharge port is arranged at the lower middle part of the tank body on the other side of the stabilization tank relative to the direction of the feed port. When the first discharge port is arranged at the upper part of the stabilization tank, the height difference between the first discharge port and the second discharge port is 60% to 90% of the height of the tank body of the stabilization tank; the relative height difference between the feed port and the second discharge port is 40% to 70% of the height of the tank body of the stabilization tank, preferably 50% to 65%. This arrangement is to ensure the separation stabilization effect of the liquid phase second material flow in the stabilization tank.

[0017] Furthermore, in the above-mentioned fluidized bed-fixed bed combined hydroprocessing process, the stabilization unit is provided with a liquid level control system, and the second discharge port of the stabilization tank in the stabilization unit is provided with a control valve, and the opening of the second discharge port control valve can be adjusted accordingly according to the liquid level in the stabilization tank.

[0018] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the ebullating bed hydrogenation catalyst adopts a micro-spherical catalyst, and the particle size of the catalyst is generally 0.3-1.0 mm, preferably 0.4-0.7 mm; the catalyst has good fluidization performance, and only a relatively low hydrogen-oil volume ratio (generally 200:1-500:1, preferably 250:1-400:1) is required to achieve good fluidization. Compared with the existing strip catalyst (generally 0.8-1.2 mm in particle size and 3-5 mm in length), the micro-spherical catalyst has a small particle size, a short diffusion path, and a small mass transfer resistance, which is conducive to promoting heat and mass transfer, and at the same time helps asphaltene macromolecules diffuse into the catalyst pores to contact active sites, thereby improving the utilization rate of the catalyst.

[0019] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the ebullated bed hydrogenation catalyst comprises an active metal component and a carrier, the carrier is an inorganic refractory metal oxide such as alumina, silicon-containing alumina, silicon oxide, preferably alumina; the active metal component generally comprises a VIB group element and / or a VIII group element, preferably one or more of W, Mo, Ni, Co, preferably Mo and Ni. The ebullated bed hydrogenation catalyst can be a commercially available product, such as the FEM series ebullated bed hydrogenation catalyst developed by Dalian Petrochemical Research Institute of Sinopec, or prepared according to an existing public method.

[0020] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the ebullating bed reactor in the ebullating bed hydrogenation reaction unit can be optionally provided with or without a high-pressure online catalyst addition and discharge system according to actual needs. Furthermore, when a high-pressure online catalyst addition and discharge system is provided, the ebullating bed reactor adopts variable temperature operation. In the initial operation (generally not exceeding 20% ​​of the entire operation cycle, usually 5% to 15% of the entire operation cycle), the catalyst activity is high, and the reactor temperature is operated at 10 to 15°C lower than the normal operating temperature. At this stage, there is no need to perform catalyst addition and discharge operation; when the operation is in the middle stage, it is operated at the normal operating temperature and the catalyst addition and discharge operation is started at the same time; at the end of the operation (generally not exceeding 15% of the entire operation cycle, usually 5% to 10% of the entire operation cycle), the catalyst online addition and discharge is stopped, and the temperature increase operation (15 to 20°C higher than the normal operating temperature) is adopted to give full play to the activity of the catalyst. Minimize the consumption of catalysts during the entire operation process. When a high-pressure online catalyst addition and discharge system is not set up, the activity loss of the catalyst can be compensated by adjusting the reaction temperature (generally increasing the reaction temperature in the final stage) according to the change in catalyst activity during operation, thereby ensuring the stability of product properties.

[0021] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the operating conditions of the ebullated bed hydrogenation reaction unit are generally as follows: hydrogen partial pressure is 12-20 MPa, preferably 15-18 MPa, reaction temperature is 380-420°C, preferably 385-415°C, hydrogen-to-oil volume ratio is 150-500, preferably 200-450, more preferably 200-350, and more preferably 200-300; volume space velocity is 0.5-2.0 h -1 , preferably 0.6 to 1.5h -1 .

[0022] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the hydrocarbon-containing raw material is a compound containing at least carbon and hydrogen, and the specific hydrocarbon-containing raw material can be at least one of atmospheric residue, vacuum residue, heavy crude oil, low-temperature coal tar, medium-temperature coal tar, high-temperature coal tar, catalytic slurry, deasphalted oil, catalytic recycling oil, hot tar (from coking and / or visbreaking), ethylene tar, etc. In general, the total content of metal nickel, vanadium and iron in the hydrocarbon-containing raw material is not less than 100 μg / g, and can be 120-300 μg / g, preferably 140-260 μg / g; the sulfur content is generally 1.5-6.0wt%, preferably 3.5-5.5wt%; the nitrogen content is generally 3000-8000μg / g, preferably 3500-6000μg / g.

[0023] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the first stream obtained in step (1) can also enter a fixed bed hydrogenation reaction unit to react under the action of a fixed bed hydroprocessing catalyst.

[0024] Further, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the fixed bed hydrogenation reaction unit adopts the fixed bed heavy oil hydroprocessing technology, and the fixed bed hydrogenation reaction unit is provided with at least one fixed bed hydrogenation reactor, preferably multiple fixed bed hydrogenation reactors are arranged in series, and further preferably 3 to 5 fixed bed hydrogenation reactors are arranged. Taking the fixed bed heavy oil hydroprocessing technology that has been maturely applied in industry as an example, the fixed bed hydroprocessing catalyst used generally refers to a single catalyst or a combination catalyst with functions such as hydrodemetallization, hydrodesulfurization, and hydrodenitrogenation. These catalysts are generally based on porous refractory inorganic oxides such as alumina as carriers, oxides of group VIB and / or group VIII metals such as W, Mo, Co, Ni, etc. as active components, and various other additives such as catalysts of elements such as P, Si, F, B, etc. are selectively added, such as CEN, FZC, ZTN, and ZTS series hydrogenation catalysts produced by the Catalyst Branch of China Petrochemical Corporation, and ZTN and ZTS series catalysts produced by Qilu Petrochemical Company. At present, in the fixed bed heavy oil hydrogenation technology, multiple catalysts are often used in combination, including protective agent, hydrodemetallization catalyst, hydrodesulfurization catalyst, hydrodenitrogenation catalyst, etc. The loading order is generally to make the raw oil contact with protective agent, hydrodemetallization, hydrodesulfurization, and hydrodenitrogenation catalyst in turn. Of course, there is also a technology of mixing these catalysts.

[0025] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing process, the specific conditions of the hydroprocessing process of the fixed bed hydroprocessing reaction unit can be specifically determined by ordinary technicians in the field according to the properties of the raw materials, process form, catalyst performance and quality requirements of the target product. In general, the hydroprocessing conditions of the fixed bed hydroprocessing reaction unit are as follows: the reaction pressure is 5MPa~25MPa, preferably 15MPa~18MPa; the reaction temperature is 300℃~450℃, preferably 380℃~420℃; the liquid hourly volumetric space velocity and hydrogen partial pressure are selected according to the characteristics of the material to be treated and the required depth of hydroprocessing. The liquid hourly volumetric space velocity is generally 0.1h -1 ~1.0h -1 , preferably 0.15h -1 ~0.8h -1 , the volume ratio of hydrogen to oil is 300-5000, preferably 500-3000.

[0026] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is smaller than that of the fixed bed hydrogenation reaction unit. Specifically, the hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is 100 to 4500 lower than that of the fixed bed hydrogenation reaction unit, and preferably 300 to 2000 lower.

[0027] Furthermore, in the above-mentioned fluidized bed-fixed bed combined hydroprocessing process, the separation in step (3) generally includes a gas-liquid separation unit and a fractionation unit, and the gas-liquid separation unit generally includes a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator and a cold low-pressure separator; the fractionation unit includes a fractionation tower, and the target products may include gasoline, diesel and hydrogenated heavy oil, and the hydrogenated heavy oil can be used as a raw material for catalytic cracking.

[0028] The second aspect of the present invention provides a fluidized bed-fixed bed combined hydroprocessing system, comprising:

[0029] An ebullated bed hydrogenation reaction unit is used to receive hydrocarbon-containing feedstock, react under the action of hydrogen and an ebullated bed hydrogenation catalyst, and obtain a gas phase first stream from the top of the reactor after separation by a three-phase separator inside the ebullated bed reactor, and a second stream discharged from a liquid phase overflow outlet on the side wall of the reactor cylinder at the upper part of the reactor below the outlet position of the gas phase first stream;

[0030] A stabilization unit, which is used to receive the second material stream from the ebullated bed hydrogenation reaction unit, stabilize and separate it to obtain a gas phase 21 material stream and a liquid phase 22 material stream;

[0031] The fixed bed hydrogenation reaction unit is used to receive the 22nd material flow from the stabilization unit, the 21st material flow from the stabilization unit, and optionally the gas phase 1st material flow from the ebullating bed hydrogenation reaction unit, and react under the action of hydrogen and a fixed bed hydroprocessing catalyst. The reaction effluent enters a separation unit for separation to obtain a target product.

[0032] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing system, the ebullated bed hydrogenation reaction unit is provided with at least one ebullated bed reactor, and the ebullated bed reactor is an ebullated bed reactor with a built-in three-phase separator independently developed by the applicant, and the ebullated bed reactor can specifically be one or more of ZL200710012680.9 and ZL 200810012191.8. The ebullated bed reactor with a three-phase separator developed by the applicant can achieve the preliminary separation of the gas, liquid and solid three phases in the material flow obtained after the reaction through the three-phase separator inside the reactor, the gas phase is generally discharged through the gas phase outlet at the top of the reactor for treatment, and the liquid phase is generally discharged through the liquid phase outlet provided on the side wall of the reactor for subsequent treatment, and the solid phase catalyst obtained after separation is circulated and used inside the ebullated bed reactor.

[0033] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing system, the conversion rate of the ebullated bed hydrogenation reaction unit is generally not higher than 40% (such as 40%, 35%, 30%, etc.), preferably not higher than 24% (such as 24%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, etc.), and further preferably not higher than 15% (such as 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, etc.). The purpose of setting up the ebullated bed hydrogenation reaction unit is not to pursue a high conversion rate of the raw material and to convert the maximum amount into the target product (such as clean fuel oil (gasoline, diesel, kerosene, etc.) or aromatics, etc.), but the core is to pre-treat the raw material for hydrodemetallization, with the goal of producing a fixed bed feed that meets the requirements. This is completely different from the goal of using an ebullated bed for hydroprocessing in the prior art. In the existing ebullated bed hydroprocessing process, the ebullated bed reactor needs to operate at a high conversion rate (generally higher than 55%, preferably higher than 60%, and more preferably higher than 70% (such as 70%, 75%, 80%, 85%, 90%, etc.) to ensure the maximum amount of various target products.

[0034] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the stabilization unit is provided with at least one stabilization tank, the design operating conditions of the stabilization tank are the same as those of the ebullated bed reactor, the stabilization tank can be a vertical tank and / or a horizontal tank, preferably a horizontal tank; further preferably, the lower part of the stabilization tank adopts a conical design. It is further preferred that an internal component is provided inside the stabilization tank, and the internal component can be a baffle, which can be used to effectively intercept scale and prevent the scale from being brought into the subsequent fixed bed reactor.

[0035] Furthermore, in the above-mentioned ebullated bed-fixed bed combined hydroprocessing process, the stabilization tank in the stabilization unit is provided with at least one feed port and two discharge ports; the two discharge ports are respectively recorded as the first discharge port and the second discharge port; wherein, the feed port is used to receive the liquid phase second material flow from the ebullated bed hydrogenation reaction unit; the first discharge port is used to discharge the 21st material flow, and the second discharge port is used to discharge the 22nd material flow. Furthermore, the feed port is arranged on the tank body of the stabilization tank, the first discharge port is arranged at the top of the stabilization tank or the upper part of the tank body on the other side of the stabilization tank relative to the direction of the feed port, and the second discharge port is arranged at the lower middle part of the tank body on the other side of the stabilization tank relative to the direction of the feed port. When the first discharge port is arranged at the upper part of the stabilization tank, the height difference between the first discharge port and the second discharge port is 60% to 90% of the height of the tank body of the stabilization tank; the relative height difference between the feed port and the second discharge port is 40% to 70% of the height of the tank body of the stabilization tank, preferably 50% to 65%. This arrangement is to ensure the separation stabilization effect of the liquid phase second material flow in the stabilization tank.

[0036] Furthermore, in the above-mentioned fluidized bed-fixed bed combined hydroprocessing process, the stabilization unit is provided with a liquid level control system, and the second discharge port of the stabilization tank in the stabilization unit is provided with a control valve, and the opening of the second discharge port control valve can be adjusted accordingly according to the liquid level in the stabilization tank.

[0037] Furthermore, in the above-mentioned ebullating bed-fixed bed combined hydroprocessing system, the fixed bed hydroprocessing reaction unit adopts the fixed bed heavy oil hydroprocessing technology, and the fixed bed hydroprocessing reaction unit is provided with at least one fixed bed hydroprocessing reactor, preferably multiple fixed bed hydroprocessing reactors are arranged in series, and further preferably 3 to 5 fixed bed hydroprocessing reactors are arranged. Taking the fixed bed heavy oil hydroprocessing technology that has been maturely applied in industry as an example, the fixed bed hydroprocessing catalyst used generally refers to a single catalyst or a combination catalyst having the functions of hydrodemetallization, hydrodesulfurization, hydrodenitrogenation, etc.

[0038] Furthermore, in the above-mentioned fluidized bed-fixed bed combined hydroprocessing system, the separation unit includes a gas-liquid separation unit and a fractionation unit. The gas-liquid separation unit generally includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator and a cold low-pressure separator; the fractionation unit includes a fractionation tower.

[0039] Furthermore, the above-mentioned ebullated bed-fixed bed combined hydroprocessing system further includes a circulating hydrogen desulfurization tower, which is used to receive and process the gas phase separated by the hot high-pressure separator in the separation unit, and the gas phase obtained after the treatment is pressurized and passed into the fixed bed hydrogenation reaction unit and / or the ebullated bed hydrogenation reaction unit for use as circulating hydrogen. Furthermore, the volume ratio of the circulating hydrogen amount of the fixed bed hydrogenation reaction unit to the circulating hydrogen amount of the ebullated bed hydrogenation reaction unit can be 6:1 to 2:1, preferably 5:1 to 3:1.

[0040] Compared with the prior art, the ebullating bed-fixed bed combined hydroprocessing process and processing system provided by the present invention has the following advantages:

[0041] The inventor of this application found in the process of independent research that in the process of treating heavy hydrocarbon-containing materials with a combined process of an ebullating bed and a fixed bed, compared with the treatment with a fixed bed alone, the fixed bed reactor in the combined process still has abnormal problems such as bed hot spots. This phenomenon is contrary to the understanding of the technical personnel of the field of hydrocarbon material hydrogenation reaction law and does not meet the expectations of the technical personnel of the field ...

[0042] After in-depth research, it was found that in the ebullated bed-fixed bed combination process, especially when an ebullated bed reactor with a built-in three-phase separator is used, the material flow discharged from the liquid phase outlet of the ebullated bed reactor is, in principle, a stable liquid phase flow. According to the conventional practice in the art, it is believed that the liquid phase material flow that has been separated by the three-phase separator inside the ebullated bed reactor can be directly sent as the feed of the subsequent processing unit for processing. As long as the feed of the ebullated bed reactor is stable, the liquid phase material discharged in principle is also stable. However, after in-depth research, it was found that the liquid phase material flow discharged from the liquid phase outlet belongs to a gas-liquid mixed phase flow, especially in the industrial device of the direct combination of ebullated bed and fixed bed, the gas-liquid mixed phase of the ebullated bed outlet is easy to cause fluctuations in the operation of the device. Since the liquid phase discharged from the ebullated bed is an overflow discharge method on the liquid level surface, there is no liquid level control system in the ebullated bed reactor, and the liquid level is inevitably fluctuated during operation due to the influence of pressure, etc., so it is difficult to ensure that the material flow is a pure liquid phase. The microscopic essence is a gas-liquid mixed phase flow, and sometimes there will be a situation where there is no liquid phase discharge for a short time or the liquid phase discharge amount is significantly higher than the normal amount. Moreover, due to the compressibility of the gas, coupled with the fluctuations of the reaction conditions of the ebullating bed reactor itself and the liquid level of the ebullating bed, the amount of liquid phase material entering the subsequent fixed bed reactor is relatively unstable, and sometimes even a short-term material shortage occurs. During production, the fixed bed reactor is easily deviated from the normal operating conditions, which in turn causes problems such as device fluctuations and bed hot spots. In the process of direct combination of ebullating bed and fixed bed, due to: (i) the connection between the two systems, especially the connection of the hydrogen system, the mutual influence between the two is more obvious. For example, the pressure change of the fixed bed system will also affect the ebullating bed reaction system; (ii) due to the needs of reaction and temperature control, the fixed bed reaction system requires a larger amount of circulating hydrogen. When a large amount of gas phase and the gas-liquid mixed phase material discharged from the ebullating bed are mixed in the logistics, the instability of the liquid phase material discharged from the ebullating bed is aggravated. Therefore, the stability of the direct combination process of ebullating bed and fixed bed has become one of the important issues for industrial implementation. This application proposes a solution based on the above research and findings.

[0043] In the existing ebullated bed hydroprocessing process, the ebullated bed reactor is generally operated at a high conversion rate (generally higher than 55%, preferably higher than 60%, and more preferably higher than 70%) to pursue a high conversion rate. Under high conversion rate operating conditions, more cracking reactions will occur, resulting in the production of more small molecular reaction products. In particular, when an ebullated bed reactor without a built-in three-phase separator is used, all reaction products are discharged through the upper outlet of the reactor. Moreover, under high conversion rate operating conditions, a large amount of small molecular light hydrocarbons will inevitably be produced. At the same time, as impurities such as sulfur and nitrogen are removed, hydrogen sulfide, ammonia, etc. are produced in the form of gas phase in the circulating hydrogen. In order to avoid excessive hydrogenation to produce more small molecular hydrocarbons that affect the yield of liquid phase products and reduce the concentrations of H2S and NH3 in the circulating hydrogen, it is necessary to separate the reaction products into gas-liquid products and liquid phase products through a gas-liquid separator and then treat them separately.

[0044] Unlike the existing ebullated bed hydroprocessing process described above, which pursues a high conversion rate, the conversion rate of the ebullated bed reactor in the ebullated bed-fixed bed combined treatment process of the present application is controlled at a relatively low level. The ebullated bed reactor is mainly aimed at demetallization pretreatment of the raw materials. The conversion rate of the ebullated bed reactor is generally controlled to be no higher than 40%, preferably no higher than 24%, and further no higher than 15%. Under such low conversion rate operating conditions, the proportion of hydrocarbon-containing raw materials undergoing cracking reactions is also relatively low, and the gas phase product yield is generally no higher than 2.0%. Moreover, in combination with the fluidized bed reactor with a built-in three-phase separator used in the present application, when faced with the above situation, it is generally believed that the gas phase has been discharged through the gas phase outlet at the top of the fluidized bed reactor. Moreover, since the fluidized bed reactor is mainly used for hydrogenation and demetallization reactions, the contents of sulfur, nitrogen and other indicators in the obtained liquid phase feed stream still do not meet the requirements, and the entire liquid phase fraction is required for subsequent hydrogenation treatment. Therefore, when faced with the above situation, technicians have no motivation to separate the liquid phase feed stream discharged from the liquid phase outlet again. The general idea is to directly carry out subsequent hydrogenation treatment for all of them, and then separate the hydrogenated products as needed.

[0045] In the combined ebullated bed-fixed bed hydroprocessing process of the present application, unlike the traditional technical route in which the ebullated bed reactor adopts the concept of high conversion rate, the ebullated bed in the present technical route adopts low conversion rate operation, which can greatly reduce the system instability, asphaltene coking and other problems caused by the high conversion rate of the ebullated bed hydrogenation reaction products in the subsequent fixed bed reactor, which helps to avoid the rapid increase of the pressure drop of the fixed bed reactor and improve the operating stability of the device.

[0046] In the combined ebullating bed-fixed bed hydroprocessing process of the present application, a thermal coupling method is adopted between the ebullating bed and the fixed bed reactor, and there is no need to set up an artificial cooling link and a circulating hydrogen desulfurization step. While fully utilizing the heat of the ebullating bed reaction, fuel consumption is saved and energy consumption is reduced. At the same time, the thermally combined process simplifies the process and reduces the complexity of the device.

[0047] In the present application of the combined hydroprocessing process of the ebullated bed and the fixed bed, based on the characteristics of the ebullated bed reactor with a built-in three-phase separator and the easy fluidization of the micro-spherical ebullated bed hydrogenation catalyst, and controlling the low conversion depth of the ebullated bed hydrogenation reaction unit, by adjusting the circulating hydrogen distribution and dosage of the ebullated bed reactor and the fixed bed reactor, the load of the circulating hydrogen compressor can be minimized and the equipment investment can be reduced; the ebullated bed reactor only needs to maintain a relatively low hydrogen-to-oil volume ratio to meet the reaction and fluidization requirements; while the fixed bed hydrogenation reaction unit needs to maintain a higher hydrogen-to-oil volume ratio to ensure the reaction and heat carrying requirements in the fixed bed reactor. The regulation of the hydrogen-to-oil volume ratio of the ebullated bed and the fixed bed in the combined process has a great influence on the reaction results. If the hydrogen-to-oil volume ratio of the ebullated bed reactor is too large, the liquid phase stays in the reactor for a short time, and the reaction does not achieve the expected effect; if the hydrogen-to-oil volume ratio of the fixed bed reactor is too small, it cannot meet the reaction requirements or the heat in the fixed bed hydrogenation reaction unit cannot be effectively carried, and abnormal conditions such as bed temperature rise occur.

[0048] In the ebullated bed-fixed bed combined hydroprocessing process of the present application, in order to address the objective problem that the fixed bed feed fluctuation leads to hot spots and poor operating stability in the device in the ebullated bed-fixed bed combined process technology, the above-mentioned problem is solved by setting a stabilization tank between the ebullated bed and the fixed bed reactor. The setting of the stabilization tank solves the influence of the gas-liquid mixed phase flow on the fixed bed reactor feed, and greatly improves the operating stability of the device.

[0049] In the combined ebullating bed-fixed bed hydroprocessing process of the present application, an ebullating bed reactor is used as a protective reactor. The unique reactor form and the matching high-activity catalyst are used to remove most of the metals and asphaltene macromolecules in the feed, optimize the subsequent fixed bed feed properties, and significantly extend the operation cycle of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the ebullating bed-fixed bed combined hydroprocessing process and processing system of the present invention.

[0051] Figure 2 This is a schematic diagram of the ebullating bed-fixed bed combined hydroprocessing process in Comparative Example 1.

[0052] Figure 3 It is a schematic diagram of the structure of the fluidized bed reactor of the present invention. DETAILED DESCRIPTION

[0053] The specific embodiments of the present invention are described in detail below, but it should be pointed out that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims.

[0054] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definitions in this specification shall prevail.

[0055] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0056] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight and pressure is gauge pressure.

[0057] In the context of this specification, any two or more embodiments of the present invention may be arbitrarily combined, and the technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0058] In the context of this specification, the conversion rate = (the content of heavy components greater than 540°C in the feed oil - the content of heavy components greater than 540°C in the hydrogenated oil) / the content of heavy components greater than 540°C in the feed oil × 100%. The conversion rate described herein is a mass percentage.

[0059] like Figure 1As shown, the process flow of the combined hydroprocessing of an ebullated bed and a fixed bed of the present invention is as follows: a raw material 1 is mixed with the heated hydrogen 2 and enters an ebullated bed hydrogenation reaction unit 3 (the ebullated bed hydrogenation reaction unit is provided with at least one ebullated bed hydrogenation reactor), and contacts with an ebullated bed hydrogenation catalyst loaded in the reactor to carry out a shallow hydrogenation reaction, so as to remove metals and convert asphaltene into a main phase. A three-phase separator is provided in the ebullated bed reactor. The reaction product is separated to obtain a gas phase first stream 4 and a liquid phase second stream 6. The second stream 6 enters a stabilization unit 5. The stabilization unit 5 is provided with at least one stabilization tank. The second stream 6 enters the stabilization tank for stabilization treatment and is separated to obtain a second stream 6. 1 stream 7 and the 22nd stream 8; wherein, the gas phase 1st stream 4 separated by the ebullating bed reactor and the 21st stream 7 separated by the stabilization unit are preferably entered into the fixed bed hydrogenation reaction unit for treatment, and the 22nd stream 8 separated by the stabilization tank is entered into the fixed bed hydrogenation reaction unit as the liquid phase feed of the fixed bed hydrogenation reaction unit. The fixed bed hydrogenation reaction unit is provided with more than one fixed bed reactor, such as a first fixed bed reactor 9, a second fixed bed reactor 11, a third fixed bed reactor 13 and a fourth fixed bed hydrogenation reactor 1 5. In the presence of hydrogen, the 22nd stream 8 enters the first fixed bed reactor 9, the second fixed bed reactor 11, the third fixed bed reactor 13 and the fourth fixed bed hydrogenation reactor 15 in sequence for hydrodesulfurization, hydrodenitrogenation and hydrodecarbonization. The specific process is that the 22nd stream 8 first enters the first fixed bed reactor 9 for reaction, the reaction product 10 of the first fixed bed reactor obtained by the reaction enters the second fixed bed reactor 11 for reaction, the reaction product 12 of the second fixed bed reactor obtained by the reaction enters the third fixed bed reactor 13 for reaction, the reaction product 14 of the third fixed bed reactor obtained by the reaction enters the fourth fixed bed reactor 15 for reaction, the reaction product 16 of the fourth fixed bed reactor obtained by the reaction enters the gas-liquid separation unit 17 for gas-liquid separation, the separated gas 19 is cooled and desulfurized in a desulfurization tower (not shown) and then used as circulating hydrogen 20, the separated liquid phase 18 can enter a fractionation tower (not shown) for further separation according to product requirements, such as fractionation to obtain dry gas, liquefied gas, naphtha, diesel and hydrogenated heavy oil.

[0060] The properties of the raw materials used in the examples of the present invention are shown in Table 1. The ebullated bed hydrogenation reaction unit is provided with an ebullated bed hydrogenation reactor, and the ebullated bed reactor can adopt the structure in ZL200810012191.8. The fixed bed hydrogenation reaction unit is provided with 4 fixed bed hydrogenation reactors. The reaction conditions of the ebullated bed hydrogenation reaction unit and the fixed bed hydrogenation reaction unit are shown in Table 2. The reaction results of the examples and comparative examples are shown in Table 3.

[0061] like Figure 3As described in the specification, the fluidized bed reactor includes a reactor shell and a three-phase separator 11. The reactor shell includes an expansion section 4 and a straight section 3 from top to bottom. The three-phase separator 11 is arranged in the expansion section 4. The diameter of the expansion section 4 is 1.2 to 2 times the diameter of the straight section, and the ratio of the diameter to the height of the expansion section is 0.3 to 2.0:1. The lower end of the expansion section 4 can be an inverted open truncated cone, or other suitable geometric shapes. The expansion angle formed by the tangent at the intersection of the expansion section and the straight section and the axis of the reactor is an acute angle, preferably 45 to 60 degrees. The three-phase separator 11 is composed of an inner tube 5, an outer tube 6, and the inner wall of the shell of the reactor expansion section 4. The straight section of the inner tube 5 constitutes the central tube of the three-phase separator, the annular space between the inner tube 5 and the outer tube 6 constitutes the baffle tube of the three-phase separator, the annular space between the outer tube 6 and the inner wall of the shell of the reactor expansion section 4 is the clarified liquid product collection area, the opening of the diffusion section at the lower end of the central tube is the logistics inlet, and the annular opening formed by the opening of the diffusion section and the inner wall of the shell of the reactor expansion section 4 is the catalyst discharge port. The specific working process is as follows: the raw material enters the fluidized bed reactor from the feed port 1, passes through the gas-liquid distributor 2, and evenly passes through the catalyst bed 7, and contacts with the catalyst for hydrogenation reaction. Under the action of the gas-liquid phase material flowing in parallel, the catalyst bed will expand to a certain extent, and its volume after expansion is usually 20% to 70% larger than its static volume. After the hydrogenation reaction, the oil and gas carrying part of the catalyst particles enter the three-phase separator 11 through the expanded area 8 surrounded by the expanded section 4, and the gas-liquid-solid three-phase separation is carried out: the gas is separated first and discharged from the reactor through the gas outlet 10, the separated catalyst returns to the reaction zone through the feed outlet 13, and the clarified flow that basically does not contain catalyst particles is discharged from the reactor through the liquid outlet 12. In order to replenish fresh catalyst and discharge the deactivated catalyst from the reactor in time, fresh catalyst can be added to the reaction system through the catalyst addition pipe 9 at the upper part of the reactor, and part of the deactivated catalyst can be discharged from the reaction system through the discharge pipe 14 at the lower part of the reactor.

[0062] Example 1

[0063] Example 1 uses Figure 1 In the process flow shown, a stabilization tank is set between the fluidized bed reactor and the first fixed bed reactor. The specific reaction process conditions and reaction results are shown in Table 2 and Table 3 respectively.

[0064] Example 2

[0065] Example 2 uses the same process flow as Example 1, and a stabilization tank is set between the ebullating bed reactor and the first fixed bed reactor. The difference is that the process conditions are different. The specific reaction process conditions and reaction results are shown in Table 2 and Table 3, respectively.

[0066] Example 3

[0067] Example 3 uses the same process flow as Example 1, and a stabilization tank is set between the fluidized bed reactor and the first fixed bed reactor. The difference is that the process conditions are different. The specific reaction process conditions and reaction results are shown in Table 2 and Table 3, respectively.

[0068] Example 4

[0069] Example 4 uses the same process flow as Example 1, and a stabilization tank is set between the ebullating bed reactor and the first fixed bed reactor. The difference is that the process conditions are different. The specific reaction process conditions and reaction results are shown in Table 2 and Table 3, respectively.

[0070] Comparative Example 1

[0071] It is basically the same as Example 1, except that no stabilization unit is set, and the second stream obtained from the ebullated bed reactor directly enters the first fixed bed reactor in the fixed bed hydrogenation reaction unit. The specific reaction process conditions and reaction results are shown in Tables 2 and 3, respectively.

[0072] Comparative Example 2

[0073] It is basically the same as Example 1, using the same process flow, and a stabilization tank is set between the ebullated bed reactor and the first fixed bed reactor. The difference is that the ebullated bed reactor in Comparative Example 2 adopts a high conversion rate operation mode, that is, the corresponding process conditions are different. The specific reaction process conditions and reaction results are shown in Tables 2 and 3, respectively.

[0074] Comparative Example 3

[0075] It is basically the same as Example 1, using the same process flow, and a stabilization tank is set between the ebullating bed reactor and the first fixed bed reactor. The difference is that the gas phase stream separated by the stabilization tank is successively returned to the inlet of the circulating hydrogen compressor for pressurization and recycling after heat exchange and air cooling, and is not used as feed for the fixed bed hydrogenation reaction unit. The specific reaction process conditions and reaction results are shown in Tables 2 and 3, respectively.

[0076] Table 1 Raw material properties

[0077]

[0078] Table 2 Reaction process conditions

[0079]

[0080] Table 3 Reaction results

[0081]

[0082] In Table 3, HDS represents the hydrodesulfurization rate, and HDM represents the hydrodemetallization removal rate.

[0083] The above embodiments and comparative examples illustrate that the use of the patented fluidized bed-fixed bed combined process technology with a stabilization tank can significantly reduce pipeline fluid flow fluctuations caused by liquid phase gas, thereby reducing fixed bed feed fluctuations, and completely eliminating problems such as hot spots in the fixed bed layer caused by frequent feed fluctuations, thereby significantly improving the operating stability and safety of the device, and helping the company's devices to achieve stable, long-term, full and optimal operation.

Claims

1. A fluidized bed-fixed bed combined hydrotreating process, comprising the following steps: (1) The heated hydrocarbon-containing feedstock enters an ebullated bed hydrogenation reaction unit, reacts under the action of hydrogen and an ebullated bed hydrogenation catalyst, and after the reaction, is separated by a three-phase separator inside the ebullated bed reactor to obtain a gas phase first stream from the top of the reactor, and a liquid phase overflow outlet on the side wall of the reactor cylinder at the upper part of the reactor below the outlet position of the gas phase first stream is discharged to obtain a second stream. The conversion rate of the ebullated bed hydrogenation reaction unit is not higher than 40%; conversion rate = (heavy component content greater than 540°C in the feedstock oil - heavy component content greater than 540°C in the ebullated bed hydrogenation product oil) / heavy component content greater than 540°C in the feedstock oil × 100%, and the conversion rate is a mass percentage; (2) The second material stream obtained in step (1) enters a stabilization unit, is stabilized and separated to obtain a gas phase 21 material stream and a liquid phase 22 material stream; the stabilization unit is provided with at least one stabilization tank; (3) The gas phase No. 21 material stream obtained in step (2), the supplemental hydrogen and the liquid phase No. 22 material stream are mixed and then enter the fixed bed hydrogenation reaction unit to react under the action of the fixed bed hydrogenation catalyst. The reaction effluent is separated to obtain the target product.

2. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The conversion rate of the ebullated bed hydrogenation reaction unit is not higher than 24%.

3. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The conversion rate of the ebullated bed hydrogenation reaction unit is not higher than 15%.

4. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The design operating conditions of the stabilization tank are the same as those of the fluidized bed reactor, and the stabilization tank is a vertical tank and / or a horizontal tank.

5. The ebullating bed-fixed bed combined hydrotreating process according to claim 4, characterized in that: The stabilization tank is a horizontal tank.

6. The ebullating bed-fixed bed combined hydrotreating process according to claim 4 or 5, characterized in that: The lower part of the stabilization tank adopts a conical design.

7. The ebullating bed-fixed bed combined hydrotreating process according to claim 4 or 5, characterized in that: An internal component is arranged inside the stabilization tank, and the internal component is a baffle.

8. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The stabilization tank in the stabilization unit is provided with at least one feed port and two discharge ports; the two discharge ports are respectively recorded as the first discharge port and the second discharge port; wherein, the feed port is used to receive the liquid phase second material flow from the fluidized bed hydrogenation reaction unit; the first discharge port is used to discharge the 21st material flow, and the second discharge port is used to discharge the 22nd material flow; the feed port is arranged on the tank body of the stabilization tank, the first discharge port is arranged at the top of the stabilization tank or the upper part of the tank body on the other side of the stabilization tank relative to the feed port direction, and the second discharge port is arranged at the middle and lower part of the tank body on the other side of the stabilization tank relative to the feed port direction. When the first discharge port is arranged at the upper part of the stabilization tank, the height difference between the first discharge port and the second discharge port is 60% to 90% of the height of the tank body of the stabilization tank; the relative height difference between the feed port and the second discharge port is 40% to 70% of the height of the tank body of the stabilization tank.

9. The ebullating bed-fixed bed combined hydrotreating process according to claim 8, characterized in that: The relative height difference between the feed port and the second discharge port is 50% to 65% of the height of the stabilizing tank body.

10. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The stabilization unit is provided with a liquid level control system. The second discharge port of the stabilization tank in the stabilization unit is provided with a control valve. The opening of the second discharge port control valve is adjusted accordingly according to the liquid level in the stabilization tank.

11. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The ebullating bed hydrogenation catalyst adopts a microspherical catalyst, and the particle size of the catalyst is 0.3 to 1.0 mm.

12. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The ebullating bed hydrogenation catalyst adopts a micro-spherical catalyst, and the particle size of the catalyst is 0.4 to 0.7 mm.

13. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The ebullated bed reactor in the ebullated bed hydrogenation reaction unit is equipped with a high-pressure online catalyst addition and discharge system according to actual needs.

14. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The operating conditions of the ebullated bed hydrogenation reaction unit are: hydrogen partial pressure of 12-20 MPa, reaction temperature of 380-420°C, hydrogen-oil volume ratio of 150-500, and volume space velocity of 0.5-2.0 h -1 .

15. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The operating conditions of the ebullated bed hydrogenation reaction unit are: hydrogen partial pressure of 15-18 MPa, reaction temperature of 385-415°C, hydrogen-oil volume ratio of 200-450, and volume space velocity of 0.6-1.5 h -1 .

16. The ebullating bed-fixed bed combined hydrotreating process according to claim 14 or 15, characterized in that: The volume ratio of hydrogen to oil is 200-350.

17. The ebullating bed-fixed bed combined hydrotreating process according to claim 14 or 15, characterized in that: The volume ratio of hydrogen to oil is 200-300.

18. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The total content of metal nickel, vanadium and iron in the hydrocarbon-containing raw material is not less than 100 μg / g, the sulfur content is 1.5-6.0wt%, and the nitrogen content is 3000-8000 μg / g.

19. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 18, characterized in that: The total content of metal nickel, vanadium and iron in the hydrocarbon-containing raw material is 120-300 μg / g, the sulfur content is 3.5-5.5 wt%, and the nitrogen content is 3500-6000 μg / g.

20. The ebullating bed-fixed bed combined hydroprocessing process according to claim 1, characterized in that: The total content of metal nickel, vanadium and iron in the hydrocarbon-containing raw material is 140-260 μg / g.

21. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 18, characterized in that: The hydrocarbon-containing raw material is at least one of atmospheric residue oil, vacuum residue oil, heavy crude oil, low-temperature coal tar, medium-temperature coal tar, high-temperature coal tar, catalytic oil slurry, deasphalted oil, catalytic recycling oil, and ethylene tar.

22. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 18, characterized in that: The hydrocarbon-containing feedstock is thermal tar.

23. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The fixed bed hydrogenation reaction unit is provided with a plurality of fixed bed hydrogenation reactors connected in series.

24. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 23, characterized in that: The fixed bed hydrogenation reaction unit is provided with 3 to 5 fixed bed hydrogenation reactors in series.

25. The ebullating bed-fixed bed combined hydrotreating process according to claim 1, characterized in that: The hydroprocessing conditions of the fixed bed hydroprocessing unit are as follows: reaction pressure is 5MPa-25MPa, reaction temperature is 300℃-450℃, liquid hourly volume space velocity is 0.1h -1 ~1.0h -1 , the volume ratio of hydrogen to oil is 300-5000.

26. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 25, characterized in that: The hydroprocessing conditions of the fixed bed hydroprocessing unit are as follows: reaction pressure is 15MPa-18MPa, reaction temperature is 380℃-420℃, liquid hourly volume space velocity is 0.15h -1 ~0.8h -1 , the volume ratio of hydrogen to oil is 500-3000.

27. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 25, characterized in that: The hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is lower than that of the fixed bed hydrogenation reaction unit, and the hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is 100 to 4500 lower than that of the fixed bed hydrogenation reaction unit.

28. The ebullating bed-fixed bed combined hydrotreating process according to claim 1 or 25, characterized in that: The hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is smaller than that of the fixed bed hydrogenation reaction unit, and the hydrogen-to-oil volume ratio of the ebullated bed hydrogenation reaction unit is 300 to 2000 lower than that of the fixed bed hydrogenation reaction unit.

29. An ebullated bed-fixed bed combined hydroprocessing system for implementing the ebullated bed-fixed bed combined hydroprocessing process according to any one of claims 1 to 28, comprising: An ebullated bed hydrogenation reaction unit is used to receive hydrocarbon-containing feedstock, react under the action of hydrogen and an ebullated bed hydrogenation catalyst, and obtain a gas phase first stream from the top of the reactor after separation by a three-phase separator inside the ebullated bed reactor, and a second stream discharged from a liquid phase overflow outlet on the side wall of the reactor cylinder at the upper part of the reactor below the outlet position of the gas phase first stream; A stabilization unit, which is used to receive the second material stream from the ebullated bed hydrogenation reaction unit, stabilize and separate it to obtain a gas phase 21 material stream and a liquid phase 22 material stream; the stabilization unit is provided with at least one stabilization tank; The fixed bed hydrogenation reaction unit is used to receive the 22nd material flow from the stabilization unit, the 21st material flow from the stabilization unit, and optionally the gas phase 1st material flow from the ebullating bed hydrogenation reaction unit, and react under the action of hydrogen and a fixed bed hydroprocessing catalyst. The reaction effluent enters a separation unit for separation to obtain a target product.

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