A method for starting up an ebullated bed hydroprocessing unit

Abstract

The present invention discloses a method for starting up an ebullated bed hydroprocessing unit. The ebullated bed hydroprocessing unit uses at least one ebullated bed hydrogenation reactor. The method includes catalyst loading and screen installation, airtightness, catalyst presulfurization, and feedstock switching. The catalyst loading and screen installation includes: installing a first screen made of a material with a melting point of 50 to 100°C at the bottom of the reactor; loading the hydrogenation catalyst into the reactor from the top of the reactor; installing a second screen made of a material with a melting point of 150 to 200°C close to the catalyst loading surface; and then installing a third screen made of a material with a melting point 2 to 15°C lower than the initial temperature of the reactor under normal operating conditions at a distance of 100 to 500 mm from the catalyst loading surface. The method of the present invention solves the effects of bed fluctuations caused by distributor blockage during the catalyst loading stage, catalyst loss during the airtightness stage, and changes in the sulfiding medium during the presulfidation stage. As the start-up temperature rises, the screens melt in sequence and are carried out with the liquid phase, significantly shortening the start-up time of the unit.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogenation, and in particular relates to a method for starting up a fluidized bed hydroprocessing device. Background Art

[0002] The increasing severity of heavy and inferior oil resources, coupled with evolving environmental regulations, has compelled the petrochemical industry to pursue advanced heavy oil processing and cleaner products. Among the numerous heavy oil processing technologies, ebullated-bed residue hydrotreating is attracting increasing attention from researchers, particularly due to its wide adaptability to feedstocks, excellent mass and heat transfer, long operating cycles, and high catalyst utilization.

[0003] Very few facilities have applied ebullated-bed technology to residue hydrotreating, and most industrial operations are still in the exploratory stage. The catalyst particles used in ebullated-bed hydrotreating typically range in size from 0.01 to 1.0 mm. However, there are still challenges with catalyst loading methods during plant startup. Currently, two common catalyst loading methods are used: First, the catalyst is mixed with oil and introduced into the reactor via an oil pump. However, this subsequently results in poor airtightness, requiring the entire oil product to be removed from the reactor before hot work can be performed. This is complex and poses safety risks. Second, the catalyst is poured directly into the reactor, followed by gas exchange and sealing. However, due to the small catalyst particle size in the ebullated-bed reactor, the catalyst can easily fall into the gas-liquid distributor before the sulfiding oil enters the reactor, causing blockage or being carried out of the reactor, resulting in loss. This limits gas flow rate and slows the airtight pressurization process. Furthermore, the catalyst presulfidation process involves the replacement of the sulfiding medium and the switching of feedstocks. Changes in the physical and chemical properties of the liquid phase inevitably disrupt the catalyst flow, hindering the sulfidation reaction.

[0004] CN102211044A discloses a method of using wax substances to bond catalysts to form spherical, hemispherical, cylindrical, flaky or irregularly shaped particles. Although this method can prevent catalyst particles from clogging pipelines and nozzles, and at the same time avoid collision losses of catalysts during loading and the harm of dust to the environment, the method is complicated to operate, and the catalyst located at the edge of the wax balls is easily damaged during the preparation process.

[0005] CN102211004A discloses a method in which large-sized wax balls are respectively loaded at the bottom and top of the catalyst, which to a certain extent avoids the loss and blockage caused by tiny catalysts falling into the gas-liquid distributor or being carried out of the reactor during the hydrogen replacement and airtightness processes when the device is started. However, there are still gaps between the large-sized wax balls, and there is a problem that some catalysts escape through the gaps.

[0006] CN102211044A and CN102211004A solve the problems of catalyst loss and distributor blockage during catalyst loading and nitrogen sealing before the start of the fluidized bed, but problems such as catalyst loss still exist during the catalyst start-up stage. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention provides a method for starting up an ebullated-bed hydroprocessing unit. This method can address issues such as catalyst loss and pipeline blockage throughout the unit's startup process, eliminate limitations on feed properties and air intake, and significantly shorten startup time.

[0008] The present invention provides a method for starting up an ebullated bed hydroprocessing unit, wherein the ebullated bed hydroprocessing unit uses at least one ebullated bed hydrogenation reactor. The method includes catalyst loading and spacer installation, nitrogen gas sealing, hydrogen gas sealing, catalyst presulfurization, and feedstock switching processes, wherein the catalyst loading and spacer installation process includes:

[0009] (1) Install the first screen made of a material with a melting point of 50-100°C at the bottom of the reactor.

[0010] (2) loading the hydrogenation catalyst into the reactor from the top of the reactor,

[0011] (3) A second screen made of a material with a melting point of 150-200°C is installed close to the catalyst loading surface, and a third screen made of a material with a melting point 2-15°C lower than the initial temperature of the reactor under normal operating conditions is installed at a distance of 100-500 mm, preferably 200-300 mm, from the catalyst loading surface.

[0012] In the above-mentioned start-up method, in step (1), the first screen is made of a material with a melting point of 50-100°C, preferably a screen with a melting point of 80-100°C. The mesh size of the first screen is preferably 0.025-0.050 mm, and the porosity is 85%-95%. The mesh size of the first screen is required to prevent the hydrogenation catalyst particles from passing through. The material used is selected from polymers, alloys or wax-based materials, preferably polymers. The alloy can be a low-melting-point alloy (with at least two elements such as bismuth, cadmium, tin, lead, dysprosium, indium as the main components), preferably a bismuth-tin-based alloy, and the polymer can be EnvisionTEC RC30 high-temperature resistant resin (commonly known as red wax). The wax-based material can be paraffin. The size of the first screen matches the inner diameter of the reactor, and the installation method can be inorganic bonding chemical assembly fixation. The thickness of the first screen is 2-5 mm. The first screen can be made by casting, forging, stamping, injection molding, or 3D printing.

[0013] In the above-mentioned start-up method, in step (3), the second screen is made of a material with a melting point of 150-200°C, preferably a screen with a melting point of 170-200°C. The mesh size of the second screen is preferably 0.05-0.50 mm, and the porosity is 85%-95%, preferably 85%-90%. The mesh size of the second screen is required to prevent the hydrogenation catalyst particles from passing through. The material used is selected from alloys or polymers, preferably polymers. The alloy can be a low-melting-point alloy (with at least two elements such as bismuth, cadmium, tin, lead, dysprosium, and indium as the main components), and the polymer can be polylactic acid (PLA) or ABS plastic (ABS plastic is a terpolymer of three monomers: acrylonitrile (A), butadiene (B), and styrene (S)). The size of the second screen matches the inner diameter of the reactor, and the installation method can be inorganic bonding chemical assembly fixation. The thickness of the second screen is 2-5 mm. The second screen can be made by casting, forging, stamping, injection molding, or 3D printing.

[0014] In the above-mentioned start-up method, in step (3), the third screen is made of a material with a melting point 2 to 15°C lower than the initial temperature of the reactor under normal operating conditions, preferably 2 to 8°C lower than the initial temperature of the reactor under normal operating conditions. The initial temperature of the reactor under normal operating conditions is 370°C to 380°C. The mesh size of the third screen is preferably 0.05 to 0.50 mm, and the porosity is 85% to 95%, preferably 85% to 90%. The mesh size of the third screen is required to prevent hydrogenation catalyst particles from passing through. The material used is selected from alloys or polymers, preferably alloys. The alloy can be a tin-based alloy or a zinc-based alloy, preferably a magnesium-zinc alloy, and the polymer can be polyacrylonitrile. The size of the third screen matches the inner diameter of the reactor, and the installation method can be welding or inorganic bonding chemical assembly fixation. The thickness of the third screen is 2 to 5 mm. The third screen can be made by casting or forging.

[0015] In the above-mentioned start-up method, the catalyst filling process adopts bag filling, and the nitrogen airtightness, hydrogen airtightness, catalyst presulfurization, and raw material switching processes solve the limitation of the device's air inlet speed of 8 to 15 mm / s. All of them can be carried out using a start-up method similar to that of a fixed-bed hydrogenation device, and the hydrogen linear velocity is controlled at 15 to 30 mm / s, preferably 20 to 25 mm / s.

[0016] In the above-mentioned start-up method, preferably, the specific process of nitrogen airtightness is as follows: it is carried out at room temperature, and the pressure under the nitrogen atmosphere is detected in turn, and the device is airtightly operated at at least low pressure (2-3MPa), medium pressure (4-8MPa) and high pressure (9-10MPa), and the air intake volume is 1.5-2.5 times that under normal operating conditions.

[0017] In the above-mentioned start-up method, preferably, the specific process of hydrogen airtightness is as follows: the outlet temperature of the heating furnace is controlled at 150-170°C, and the wall temperature of the reaction system equipment is at least higher than the lowest pressure increase point (about 93°C) by heating with nitrogen. Subsequently, the pressure under the hydrogen atmosphere is detected in sequence, and the device is airtightly operated at at least low pressure (4-5MPa), medium pressure (6-12MPa) and high pressure (14-18MPa), and the air intake volume is 1.5-2.5 times that under normal operating conditions.

[0018] In the above-mentioned start-up method, preferably, the specific process of catalyst pre-sulfurization is as follows: the reaction pressure is maintained at 15 to 18 MPa, including the first vulcanization stage and the second vulcanization stage, wherein the first vulcanization stage uses diesel as the medium oil, the vulcanization temperature is 230 to 260°C, and the constant temperature vulcanization time is 2 to 8 hours, and the second vulcanization stage uses straight-run wax oil as the medium oil, the vulcanization temperature is 280 to 320°C, and the constant temperature vulcanization time is 2 to 8 hours. A fully open circuit is adopted during the vulcanization process, and the medium oil is directly thrown out to the waste oil tank after passing through the reactor. The switching between diesel and straight-run wax oil is after the constant temperature vulcanization in the first vulcanization stage. The vulcanizing agent used in the vulcanization process can be at least one of carbon disulfide, di-tert-butyl polysulfide, and dimethyl disulfide; the initial injection temperature of the vulcanizing agent is 160 to 200°C, preferably 180 to 200°C.

[0019] In the above-mentioned start-up method, the hydrogenation catalyst can be a conventional ebullated-bed hydrogenation catalyst, generally comprising a support and an active metal component. The support can be an inorganic refractory oxide, preferably alumina. The active metal component includes at least one of a Group VIB or Group VIII metal, with Group VIB preferably being molybdenum and / or tungsten, and a Group VIII metal preferably being cobalt and / or nickel. The hydrogenation active metal content, calculated as oxide, is 10% to 14% based on the mass of the catalyst. The particle size of the hydrogenation catalyst is 0.4 to 0.7 mm. Commonly used ebullated-bed hydrogenation catalysts include the FEM series of ebullated-bed hydrogenation catalysts developed by Sinopec (Dalian) Research Institute of Petrochemicals Co., Ltd.

[0020] In the above-mentioned start-up method, the ebullated bed hydrogenation reactor can be a conventional ebullated bed hydrogenation reactor.

[0021] In the above method, preferably, the specific process of raw material switching after catalyst presulfurization is as follows: the residual oil feed cutting rate is increased by 5% to 30% of the total feed amount every 24 hours, preferably 15% to 25%, and the reactor temperature is gradually increased accordingly, and the heating rate is controlled at 5°C / 24h to 10°C / 24h, preferably 8°C / 24h to 10°C / 24h.

[0022] In the above method, the raw oil during normal production is atmospheric residue and / or vacuum residue, and diluent oil may be added, wherein the diluent oil mainly includes at least one of straight-run wax oil, coker wax oil, catalytic cracking diesel, catalytic cracking slurry oil, etc. The impurity content of the raw oil, calculated by mass fraction, is as follows: sulfur is 1.5% to 8.20%, carbon residue is 8% to 25%, nitrogen is 0.15% to 0.48%, and metal (nickel + vanadium) is 50 to 200 mg kg -1 .

[0023] In the above method, the operating conditions for normal production are as follows: hydrogen partial pressure 15-20 MPa, liquid hourly volume space velocity 0.4-1.0h -1 , Hydrogen to oil volume ratio 200~800Nm 3 / m 3 , reaction temperature 370~412℃.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] 1. The inventors have discovered that during the startup process of an ebullated-bed hydroprocessing unit, in addition to catalyst loss and distributor blockage during catalyst loading and nitrogen sealing, serious catalyst loss still occurs during the subsequent hydrogen sealing stage and catalyst presulfiding stage, when the properties of the sulfiding medium change. Currently, methods such as limiting feed properties and air intake are used to reduce catalyst loss, but this increases startup time. Further research has revealed that by using screens with different melting points placed at specific locations in the reactor to coordinate the catalyst startup process, catalyst loss can be controlled throughout the process and significantly shorten startup time.

[0026] 2. The method of the present invention is simple and easy to operate. For example, the catalyst can be loaded in a cloth bag. The materials for preparing the separator are widely available and inexpensive. Separators with different melting points can be synthesized by simple casting or 3D printing, and the separators with different melting points can be installed in corresponding positions.

[0027] 3. In the method of the present invention, a first screen is installed at the bottom of the reactor to prevent the catalyst from clogging the gas-liquid distributor during catalyst loading. A second screen is installed just above the catalyst feed surface to prevent catalyst loss and pore blockage during nitrogen and hydrogen sealing. It also prevents mechanical collisions between catalyst particles during the sealing process, which could damage the catalyst's physical structure. A third screen is installed 100 to 500 mm from the catalyst feed surface to secure the catalyst particles in a specific area. This prevents disturbance of the catalyst bed, as the start-up medium oil requires switching during the device startup process. By installing the screens, the problems of feed property fluctuations and air intake restrictions are resolved throughout the device startup process, significantly shortening startup time.

[0028] 4. The installation of the screen in the method of the present invention has no effect on the physical and chemical properties of the catalyst and the operation of the device. After the screen plays its own role, it will melt as the temperature of the reactor gradually rises during the start-up of the device and be carried out of the reaction system by the liquid phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the internal structure of the ebullated bed hydroprocessing device of the present invention;

[0030] Attachment Figure 1 The markings are explained as follows:

[0031] Reactor inlet 1; gas-liquid distributor 2; first spacer 3; hydrogenation catalyst 4; second spacer 5; third spacer 6; circulation cup 7; separator 8; gas phase outlet 9; liquid phase hydrogenation tail oil outlet 10; circulation oil outlet 11; catalyst online addition and discharge inlet 12; waste catalyst discharge outlet 13. DETAILED DESCRIPTION

[0032] The following is a further description of the startup method provided by the present invention and its functions and effects with reference to the accompanying drawings and examples, but the present invention is not limited thereto. Many devices, such as pumps, heat exchangers, and heating furnaces, are omitted from the drawings, but are well known to those skilled in the art.

[0033] The following combination Figure 1 The method of the present invention is described in detail. An ebullating bed hydrogenation reactor is used. A reactor inlet 1, a gas-liquid distributor 2, and a waste catalyst discharge port 13 are provided at the bottom. A circulation cup 7 is provided at the top. A catalyst online addition and discharge inlet 12 is provided at the top. The reactor outlet is connected to a separator 8. The separator 8 is provided with a gas phase outlet 9, a liquid phase hydrogenation tail oil outlet 10, and a circulating oil outlet 11. The start-up method includes catalyst loading and spacer installation, nitrogen gas tightness, hydrogen gas tightness, catalyst presulfurization, and raw material switching processes. The catalyst loading and spacer installation process includes:

[0034] (1) Install the first screen 3 made of a material with a melting point of 50-100°C, preferably 80-100°C, at the bottom of the reactor.

[0035] (2) The hydrogenation catalyst 4 is loaded into the reactor from the top of the reactor,

[0036] (3) A second spacer 5 made of a material with a melting point of 150-200°C, preferably 170-200°C, is installed close to the catalyst loading surface, and then a third spacer 6 made of a material with a melting point 2-15°C, preferably 2-8°C lower than the initial temperature of the reactor under normal operating conditions is installed at a distance of 100-500 mm, preferably 200-300 mm, from the catalyst loading surface.

[0037] The same pilot plant was used for both the embodiment and comparative example ebullated bed reactors, with an effective height of 1800 mm, a diameter of 520 mm, and a catalyst loading of 165 kg. Initially, the reactor was filled with air at room temperature and pressure.

[0038] The gas flow rate in the present invention refers to the actual gas volume flow rate inside the reactor divided by the cross-sectional area of ​​the reactor.

[0039] The ebullated bed reactors in the examples and comparative examples of the present invention both use the ebullated bed hydrogenation catalyst FEM-10 (see Table 1).

[0040] Table 1 Main properties of fluidized bed hydrogenation catalyst FEM-10

[0041] Appearance and shape spherical Particle diameter / mm 0.4～0.5 <![CDATA[Pore volume / (mL·g -1 )]]> 0.60 <![CDATA[Specific surface area / (m 2 ·g -1 )]]> 180 Chemical composition <![CDATA[Mo-Ni-Al2O3]]> Wear / % 0.1

[0042] The same sulfiding medium oil (properties shown in Table 2) and raw material atmospheric residue oil (main properties shown in Table 3) were used during the start-up process of the examples and comparative examples of the present invention.

[0043] The process conditions of the normal operation stage of the raw materials in the examples of the present invention and the comparative examples are consistent, and the main operating conditions are shown in Table 4.

[0044] Table 2 Main properties of sulfiding medium oil

[0045]

[0046]

[0047] Table 3 Main properties of residue oil (raw material)

[0048] crude oil atmospheric residue <![CDATA[Density (20 °C) / (kg·m -3 )]]> 985.0 <![CDATA[Viscosity (100 °C) / (mm 2 ·s -1 )]]> 126 CCR / wt% 13.15 S / wt% 4.52 <![CDATA[N / (mg·kg -1 )]]> 3000 <![CDATA[Ni / (mg·kg -1 )]]> 27.47 <![CDATA[V / (mg·kg -1 )]]> 81.58 Asphaltene / wt% 6.60

[0049] Table 4 Main operating conditions of residue oil hydrotreating unit

[0050] project data Reactor inlet pressure / MPa 17.0 <![CDATA[Liquid hourly space velocity / h -1 > 0.61 <![CDATA[Hydrogen-oil volume ratio / (Nm 3 ·m -3 )]]> 300 Reaction temperature / ℃ 390

[0051] Note: *Definition of hydrogen-oil volume ratio: [Total flow rate of mixed hydrogen at the reactor inlet (Nm 3 / h) × volume purity of hydrogen in mixed hydrogen] / feed oil flow rate (m 3 / h).

[0052] Example 1

[0053] First, 3D printing technology was used to select EnvisionTEC RC30 high-temperature resistant resin (commonly known as red wax) with a melting point of 70°C as the raw material to prepare a first separator with a grid side length of 0.04mm, a porosity of 86% and a thickness of 3mm. 3D printing technology was used to select ABS plastic with a melting point of 170°C (ABS plastic is a terpolymer of three monomers: acrylonitrile (A), butadiene (B) and styrene (S)) as the raw material to prepare a second separator with a grid side length of 0.05mm, a porosity of 90% and a thickness of 3mm. Molding was used to select magnesium-zinc alloy with a melting point of 375°C as the raw material to prepare a third separator with a grid side length of 0.10mm, a porosity of 90% and a thickness of 3mm.

[0054] After the first partition is assembled and fixed to the upper part of the distributor with inorganic adhesive, the catalyst is loaded into the reactor from the top of the reactor by bag filling, and the second partition is assembled and fixed with inorganic adhesive at a position close to the catalyst loading surface. Finally, the third partition is fixed by welding at a distance of 200 mm from the upper part of the catalyst loading surface.

[0055] During the gas replacement and airtightness process of the reactor, the gas flow rate was controlled at about 25 mm / s. The nitrogen airtightness process and the hydrogen airtightness process took a total of 75 hours. After the airtightness was qualified, the start-up medium diesel oil was introduced to raise the temperature of the device to 200°C at 15°C / h.

[0056] The catalyst was then vulcanized. The gas flow rate was controlled at approximately 20 mm / s throughout the vulcanization process, and the furnace outlet temperature was raised at a rate of 15°C / h to 230°C. Once the reaction temperature reached 230°C, the temperature was stopped to allow for hydrogen sulfide penetration. After hydrogen sulfide penetration and the concentration of hydrogen sulfide in the circulating hydrogen reached 0.2-1.0 vol.%, the first constant-temperature vulcanization period lasted 4 hours. The reactor temperature was then raised at a rate of 5°C / h to 260°C, and wax oil was introduced for displacement. Once displacement was complete, the reactor temperature was raised at a rate of 10°C / h to 320°C, where it was maintained at this temperature for 4 hours before the vulcanization process concluded. During this period, the hydrogen sulfide content in the circulating hydrogen was controlled at 1.5-2.0 vol.% by adjusting the sulfiding agent injection rate. The entire vulcanization process took a total of 26 hours.

[0057] During the feedstock switching process, the residual oil feedstock was cut in at a rate of 20% of the total feed amount every 24 hours. At the same time, the reactor temperature was gradually increased to 380°C, and the heating rate was controlled at 10°C / 24h, which took 144h.

[0058] When the raw material switching was completed and the reactor temperature rose to 380°C, the operation test was started.

[0059] The entire process was simple and smooth, with no catalyst particle loss or blockage during the gas replacement and airtightness stages. The bed temperature distribution was uniform during the catalyst sulfidation and feedstock switching phases, with a radial temperature difference of less than 2°C. The catalyst performed well during the test phase, and the main properties of the full range of hydrogenated oil fractions are shown in Table 5. After the unit was shut down, inspection of the reactor outlet gas line and bottom nozzle revealed that they were very clean.

[0060] Example 2

[0061] First, a bismuth-tin-based alloy with a melting point of 90°C was selected as the raw material by a casting method to prepare a first separator with a grid side length of 0.05 mm, a porosity of 87% and a thickness of 5 mm. A second separator with a grid side length of 0.30 mm, a porosity of 86% and a thickness of 4 mm was prepared by a 3D printing technology. A magnesium-zinc alloy with a melting point of 365°C was selected as the raw material by a casting method to prepare a third separator with a grid side length of 0.30 mm, a porosity of 87% and a thickness of 2 mm.

[0062] After the first partition is assembled and fixed to the upper part of the distributor at the bottom of the reactor with inorganic adhesive, the catalyst is loaded into the reactor from the top of the reactor by bag filling, and the second partition is assembled and fixed with inorganic adhesive at a position close to the catalyst loading surface. Finally, the third partition is fixed by welding at a distance of 300 mm from the catalyst loading surface.

[0063] The gas flow rate during the reactor gas replacement and airtightness process was controlled at approximately 20 mm / s. The nitrogen and hydrogen airtightness processes took a total of 95 hours. After the airtightness was qualified, diesel fuel was introduced as the start-up medium, raising the temperature to 185°C at a rate of 15°C / h.

[0064] The catalyst was then vulcanized. The gas flow rate was controlled at approximately 20 mm / s throughout the vulcanization process, and the furnace outlet temperature was raised at a rate of 15°C / h to 230°C. Once the reaction temperature reached 230°C, the temperature was stopped to allow for hydrogen sulfide penetration. After hydrogen sulfide penetration and the concentration of hydrogen sulfide in the circulating hydrogen reached 0.2-1.0 vol.%, the first constant-temperature vulcanization period lasted 4 hours. The reactor temperature was then raised at a rate of 5°C / h to 260°C, and wax oil was introduced for displacement. Once displacement was complete, the reactor temperature was raised at a rate of 10°C / h to 320°C, where it was maintained at this temperature for 4 hours before vulcanization concluded. During this period, the hydrogen sulfide content in the circulating hydrogen was controlled at 1.5-2.0 vol.% by adjusting the sulfiding agent injection rate. The entire vulcanization process took a total of 28 hours.

[0065] During the feedstock switching process, the residual oil feedstock was cut in at a rate of 20% of the total feed amount every 24 hours. At the same time, the reactor temperature was gradually increased to 370°C, and the heating rate was controlled at 8°C / 24h, which took 150h.

[0066] When the raw material switching was completed and the reactor temperature rose to 370°C, the operation test was started.

[0067] The entire process was simple and smooth, with no catalyst particle loss or blockage during the gas replacement and airtightness stages. The bed temperature distribution was uniform during the catalyst sulfidation and feedstock switching phases, with a radial temperature difference of less than 2°C. The catalyst performed well during the test phase, and the main properties of the full range of hydrogenated oil fractions are shown in Table 5. After the unit was shut down, inspection of the reactor outlet gas line and bottom nozzle revealed that they were very clean.

[0068] Comparative Example 1

[0069] Compared to Example 1, this comparative example did not use a screen. The catalyst was loaded into bags. The gas flow rate during the reactor gas replacement and airtightness process was 10 mm / s. The nitrogen and hydrogen airtightness processes took a total of 190 hours. After the airtightness was achieved, diesel fuel (a start-up medium) was introduced to raise the temperature to 200°C at a rate of 15°C / h.

[0070] The catalyst was then vulcanized. The gas flow rate was controlled at approximately 10 mm / s throughout the vulcanization process, and the furnace outlet temperature was raised at 15°C / h to 230°C. Once the reaction temperature reached 230°C, the temperature was stopped to allow for hydrogen sulfide penetration. After hydrogen sulfide penetration and the concentration of hydrogen sulfide in the circulating hydrogen reached 0.2-1.0 vol.%, the first constant-temperature vulcanization period lasted 4 hours. The reactor temperature was then raised at 5°C / h to 260°C, and wax oil was introduced for displacement. Once displacement was complete, the reactor temperature was raised at 10°C / h to 320°C, where it was held constant for 4 hours before vulcanization concluded. During this period, the hydrogen sulfide content in the circulating hydrogen was controlled at 1.5-2.0 vol.% by adjusting the sulfiding agent injection rate. The entire vulcanization process took a total of 36 hours.

[0071] During the feedstock switching process, the residual oil feedstock was cut in at a rate of 10% of the total feed amount every 24 hours. At the same time, the reactor temperature was gradually increased to 380°C, and the heating rate was controlled at 5°C / 24h, which took 288h.

[0072] When the raw material switching was completed and the reactor temperature rose to 380°C, the operation test was started.

[0073] In this comparative example, by controlling the gas flow rate, no catalyst particle loss occurred during the gas replacement and airtightness stages. However, during the catalyst sulfidation and feedstock switching stages, the bed temperature distribution was uneven, with a radial bed temperature difference exceeding 8°C during the feedstock switching stage, which presented operational difficulties. The catalyst hydrogenation performance was slightly poor during the test phase. The main properties of the full fraction of the hydrogenated oil are shown in Table 5. After the unit was shut down, inspection revealed a small amount of catalyst in the reactor outlet gas line and catalyst particles in the bottom nozzle.

[0074] Table 5 Main properties of the full fraction of hydrogenated oil

[0075] project Example 1 Example 2 Comparative Example 1 S / wt% 2.48 2.50 2.63 <![CDATA[N / (mg·kg -1 )]]> 2550 2620 2730 CCR / wt% 8.7 8.9 9.6 <![CDATA[Ni+V / (mg·kg -1 )]]> 35 40 54

[0076] Comparative Example 2

[0077] Compared with Example 1, this comparative example does not use a partition screen, and the catalyst is loaded in a dense phase manner. The gas flow rate during the gas replacement and airtightness of the reactor is 25 mm / s. During the gas replacement and airtightness pressurization stages, surging is prone to occur, resulting in a large amount of catalyst being carried out. The device is forced to end the startup process. Inspection revealed that there were catalyst particles in the nozzle at the bottom of the reactor and a large amount of catalyst deposits in the outlet gas pipe.

Claims

1. A method for starting up an ebullated bed hydroprocessing unit, wherein the ebullated bed hydroprocessing unit uses at least one ebullated bed hydrogenation reactor, and the method includes the steps of loading a hydrogenation catalyst and installing a spacer, nitrogen gas sealing, hydrogen gas sealing, presulfiding the hydrogenation catalyst, and switching feedstocks, wherein: The process of loading the hydrogenation catalyst and installing the spacer includes: (1) Install the first screen of the material with a melting point of 50~100℃ at the bottom of the reactor, (2) Load the hydrogenation catalyst into the reactor from the top of the reactor, (3) A second screen made of a material with a melting point of 150-200°C is installed close to the hydrogenation catalyst feeding surface, and a third screen made of a material with a melting point 2-15°C lower than the initial temperature of the ebullated bed hydrogenation reactor under normal production conditions is installed 100-500 mm away from the hydrogenation catalyst feeding surface; the sizes of the first screen, the second screen, and the third screen are all matched with the inner diameter of the ebullated bed hydrogenation reactor, and the mesh size of the first screen, the second screen, and the third screen is required to be such that no hydrogenation catalyst particles can pass through; The reaction temperature of the normal production is 370~412℃.

2. The method for starting a work according to claim 1, characterized in that: In step (1), a first screen made of a material with a melting point of 80-100° C. is installed at the bottom of the reactor.

3. The start-up method according to claim 1, characterized in that: In step (3), a second screen made of a material having a melting point of 170-200°C is installed close to the hydrogenation catalyst loading surface, and then a third screen made of a material having a melting point 2-8°C lower than the initial temperature of the fluidized bed hydrogenation reactor under normal production conditions is installed 200-300 mm away from the hydrogenation catalyst loading surface.

4. The start-up method according to claim 1, characterized in that: The mesh size of the first spacer is 0.025-0.050 mm, the porosity is 85%-95%, and the thickness of the first spacer is 2-5 mm.

5. The start-up method according to claim 1, characterized in that: The material used for the first separator is selected from polymer, alloy or wax-based material.

6. The method for starting work according to claim 5, characterized in that: The material used for the first separator is polymer.

7. The start-up method according to claim 5, characterized in that: The material used for the first separator is bismuth-tin based alloy or EnvisionTECRC30 high temperature resistant resin.

8. The method for starting a work according to claim 1, characterized in that: The hydrogenation catalyst is an ebullating bed hydrogenation catalyst, which includes a carrier and an active metal component. The carrier is an inorganic refractory oxide. The active metal component includes at least one of Group VIB and Group VIII metals. Based on the mass of the hydrogenation catalyst, the hydrogenation active metal is calculated as oxide at 10% to 14%. The particle size of the hydrogenation catalyst is 0.4 to 0.7 mm.

9. The method for starting a work according to claim 8, characterized in that: In the hydrogenation catalyst, the carrier is alumina.

10. The start-up method according to claim 8, characterized in that: In the hydrogenation catalyst, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

11. The method for starting a work according to claim 1, characterized in that: The mesh size of the second spacer is 0.05-0.50 mm, the porosity is 85%-95%, and the thickness of the second spacer is 2-5 mm.

12. The start-up method according to claim 11, characterized in that: The porosity of the second separator is 85%~90%.

13. The method for starting a work according to claim 1, characterized in that: The material of the second separator is selected from alloy or polymer.

14. The start-up method according to claim 13, characterized in that: The second separator is made of polymer.

15. The start-up method according to claim 13, characterized in that: The second partition is made of polylactic acid or ABS plastic.

16. The method for starting a work according to claim 1, characterized in that: The mesh size of the third spacer is 0.05-0.50 mm, the porosity is 85%-95%, and the thickness of the third spacer is 2-5 mm.

17. The start-up method according to claim 16, characterized in that: The porosity of the third separator is 85%~90%.

18. The start-up method according to claim 1, characterized in that: The material of the third separator is selected from alloy or polymer.

19. The method for starting a work according to claim 18, characterized in that: The material of the third separator is alloy.

20. The start-up method according to claim 18, characterized in that: The material of the third separator is tin-based alloy, zinc-based alloy or polyacrylonitrile.

21. The method for starting a work according to claim 1, characterized in that: The hydrogenation catalyst is filled in a cloth bag, and during the nitrogen airtightness, hydrogen airtightness, hydrogenation catalyst presulfurization, and raw material switching processes, the hydrogen linear velocity is controlled at 15-30 mm / s.

22. The method for starting a work according to claim 1, characterized in that: The hydrogenation catalyst is filled in a cloth bag, and during the nitrogen airtightness, hydrogen airtightness, hydrogenation catalyst presulfurization, and raw material switching processes, the hydrogen linear velocity is controlled at 20-25 mm / s.

23. The start-up method according to claim 21, characterized in that: The pre-sulfurization process of the hydrogenation catalyst is as follows: the reaction pressure is maintained at 15~18MPa, including the first vulcanization stage and the second vulcanization stage, wherein the first vulcanization stage uses diesel as the medium oil, the vulcanization temperature is 230~260℃, and the constant temperature vulcanization time is 2~8 hours; the second vulcanization stage uses straight-run wax oil as the medium oil, the vulcanization temperature is 280~320℃, and the constant temperature vulcanization time is 2~8 hours; a fully open circuit is adopted during the vulcanization process, wherein the switching between diesel and straight-run wax oil is after the constant temperature vulcanization in the first vulcanization stage; the vulcanizing agent used in the vulcanization process is at least one of carbon disulfide, di-tert-butyl polysulfide, and dimethyl disulfide; the initial injection temperature of the vulcanizing agent is 160~200℃.

24. The start-up method according to claim 23, characterized in that: The initial injection temperature of the vulcanizing agent is 180~200℃.

25. The method for starting a work according to claim 1, characterized in that: The feed switching process after pre-sulfurization of the hydrogenation catalyst is as follows: the residual oil feed cutting rate increases by 5% to 30% of the total feed amount every 24 hours, and the reactor temperature increases accordingly, and the heating rate is controlled at 5℃ / 24h~10℃ / 24h.

26. The method for starting a work according to claim 1, characterized in that: The feed switching process after pre-sulfurization of the hydrogenation catalyst is as follows: the residual oil feed cutting rate increases by 15%~25% of the total feed amount every 24 hours, and the reactor temperature increases accordingly, and the heating rate is controlled at 8℃ / 24h~10℃ / 24h.

27. The method for starting a work according to claim 1, characterized in that: The raw oil in normal production is atmospheric residue and / or vacuum residue. The impurity content of the raw oil, calculated by mass fraction, is as follows: sulfur 1.5% to 8.20%, carbon residue 8% to 25%, nitrogen 0.15% to 0.48%, and metals (calculated as nickel and vanadium) 50 to 200 mg kg -1 .

28. The start-up method according to claim 27, characterized in that: During normal production, diluent oil is added to the raw oil, wherein the diluent oil includes at least one of straight-run wax oil, coker wax oil, catalytic cracking diesel oil, and catalytic cracking slurry oil.

29. The method for starting a work according to claim 1, characterized in that: The operating conditions for normal production are as follows: hydrogen partial pressure 15~20MPa, liquid hourly volume space velocity 0.4~1.0h -1 , Hydrogen to oil volume ratio 200~800Nm 3 / m.

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