Fixed bed residue hydroprocessing method and system

Abstract

The application provides a fixed bed residual oil hydrogenation method and system. The method comprises the following steps: sequentially passing a residual oil raw material and hydrogen through a first hydrogenation reactor, a second hydrogenation reactor and a third hydrogenation reactor in series in a downflow mode for hydrogenation reaction to obtain a mixture of desulfurized residual oil and hydrogen; separating the mixture of desulfurized residual oil and hydrogen to obtain desulfurized residual oil and hydrogen; heating the separated desulfurized residual oil to 420-480 DEG C, then introducing the desulfurized residual oil into a fourth hydrogenation reactor from the top of the fourth hydrogenation reactor, introducing the separated hydrogen into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor, and performing a hydrocracking reaction to obtain a residual oil hydrogenation product. The method and system improve the yield of 3-4 ring aromatic hydrocarbon fraction oil in the residual oil hydrogenation product, improve the yield of light distillate oil, and reduce the carbon residue value of the hydrogenated residual oil, thus improving the economic benefits of the overall fixed bed residual oil hydrogenation process and system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of residual oil hydrogenation process, and particularly relates to a fixed bed residual oil hydrogenation method and system. BACKGROUND

[0002] In the petroleum refining industry, with the continuous increase of the heavy and poor quality of crude oil, and the increasingly stringent environmental protection requirements, the fixed bed residual oil hydrogenation process has gradually become a crucial process. Due to the increasingly surplus refining capacity, fierce market competition, and the meager profit of crude oil processing, it is more and more important to improve the operation level and economic benefit of the refining device. More and more refining and chemical enterprises begin to consider improving the existing fixed bed residual oil hydrogenation device and process to produce aromatic-rich distillate oil suitable for preparing carbon materials. Studies have shown that 3-4 ring aromatics have moderate coking speed, which is conducive to the growth of carbon material grains, and are suitable for producing high-end carbon materials. Therefore, various refining and chemical enterprises have researched and improved the residual oil hydrogenation device and process to improve the yield of 3-4 ring aromatics.

[0003] CN102816597A discloses a residual oil hydroprocessing process. The process adds a feed inlet before the demetallization agent bed layer of the residual oil hydroprocessing device. Residual oil and hydrogen enter the device through the original feed inlet of the residual oil hydrogenation device for reaction, and catalytic cracking back-fried oil enters the device through the added feed inlet for reaction. The residual oil hydrogenation device adopts catalyst grading loading, which includes three or more than three kinds of hydrogenation catalysts such as protective agent, demetallization agent, and desulfurization agent. Each catalyst is divided into one bed layer for loading, and the protective agent bed layer adopts an upflow reactor or a fixed bed reactor. This method can improve the impurity removal rate of residual oil hydroprocessing, not only inhibits bed coking, but also prolongs the operation period of the residual oil hydroprocessing device, and greatly increases the yield of high-value light fraction.

[0004] CN102816599A discloses a residual oil hydroprocessing combined process. The process adds a feed inlet before the desulfurization agent bed layer of the residual oil hydrogenation device. Residual oil and hydrogen enter the device through the original feed inlet of the residual oil hydrogenation device for reaction, and hydrogenated residual oil enters the catalytic cracking device for further reaction. Catalytic cracking back-fried oil returns to the residual oil hydrogenation device through the added feed inlet for hydrogenation treatment. This process can effectively reduce the carbon deposition of the desulfurization agent and the catalysts behind it, prolong the operation period of the residual oil hydroprocessing device, improve the yield of high-value light oil, reduce the use of cold hydrogen, prevent excessive hydrogenation of back-fried oil, maintain high solubility of asphaltene, and prevent asphaltene coking.

[0005] CN102816594A discloses a residue hydro-treating-catalytic cracking-solvent refining combined process. The process performs solvent refining on catalytic cracking heavy cycle oil and oil slurry obtained from a catalytic cracking unit, and the solvent refined extract oil is returned to a residue hydro-treating unit after removal of solid impurities, and is fed into the unit together with residue oil for hydro-treating. The solvent refined raffinate oil is returned to the catalytic cracking unit together with the hydro-treated residue oil for further reaction. The process converts as much residue oil as possible into high value-added light oil products, improves the operating conditions of the residue hydro-treating unit, and prolongs the operating time of the residue hydro-treating unit.

[0006] CN102816598B discloses a method for reducing coke deposition on a de-residual carbon catalyst in a residue hydro-treating unit. The method adds a feed inlet before the de-residual carbon catalyst bed in the residue hydro-treating unit, and introduces 1-30% of catalytic cracking recycled oil with high aromaticity into the feedstock residue oil through the feed inlet, to increase the solubility of gradually precipitated asphaltene in the feedstock oil, thereby reducing the amount of coke deposited on the catalyst. The method can effectively reduce coke deposition on the de-residual carbon catalyst and the catalysts behind it, prolong the operating period of the residue hydro-treating unit, and reduce the amount of cold hydrogen used.

[0007] The above method improves the proportion of light components in the hydro-treated residue oil, but the content of 3-4 ring aromatic components in the produced hydro-treated residue oil is low, which is not suitable for producing high-end carbon materials. Moreover, the operating temperature of the fixed-bed residue hydro-treating unit in the above method is generally low, usually at 350-430°C, which also makes the content of 3-4 ring aromatic components in the hydro-treated residue oil low.

[0008] Therefore, it is still one of the urgent problems in the field to develop a new type of fixed-bed residue hydro-treating method and system to improve the yield of 3-4 ring aromatic fraction oil suitable for producing high-end carbon materials. SUMMARY

[0009] To solve the above technical problems, the purpose of the present application is to provide a fixed-bed residue hydro-treating method and system. The method and system can improve the yield of 3-4 ring aromatic fraction oil in the residue hydro-treating product.

[0010] To achieve the above purpose, the first aspect of the present application provides a fixed-bed residue hydro-treating method, which comprises the following steps:

[0011] (1) passing a residue feedstock and hydrogen through a first hydro-treating reactor, a second hydro-treating reactor and a third hydro-treating reactor in series in a downflow manner for hydro-treating reaction, to obtain a mixture of desulfurized residue oil and hydrogen;

[0012] (2) separating the mixture of desulfurized residue oil and hydrogen obtained in step (1) to obtain desulfurized residue oil and hydrogen;

[0013] (3) heating the desulfurized residue oil obtained in step (2) to 420-480℃, then introducing the heated desulfurized residue oil from the top of the fourth hydrogenation reactor into the fourth hydrogenation reactor, introducing the hydrogen obtained in step (2) from the bottom of the fourth hydrogenation reactor into the fourth hydrogenation reactor, and performing a hydrocracking reaction with the heated desulfurized residue oil to obtain a residue hydrogenation product.

[0014] In the fixed bed residue hydrogenation method described above, preferably, the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor each comprise a catalyst loading zone, and the four catalyst loading zones constitute a total reaction zone; in the total reaction zone, four or more kinds of hydrogenation catalysts comprising a hydrogenation guard catalyst, a hydrodemetallization catalyst, a hydrodesulfurization catalyst and a hydrodecarbon catalyst are sequentially loaded along the flow direction of the residue.

[0015] It should be noted that the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor used in the present application are all downflow fixed bed hydrogenation reactors.

[0016] In the fixed bed residue hydrogenation method described above, preferably, the loading amount of the hydrogenation guard catalyst is 2%-10% of the volume of the total reaction zone, the loading amount of the hydrodemetallization catalyst is 35%-70% of the volume of the total reaction zone, the loading amount of the hydrodesulfurization catalyst is 10%-40% of the volume of the total reaction zone, and the loading amount of the hydrodecarbon catalyst is 10%-40% of the volume of the total reaction zone.

[0017] In the fixed bed residue hydrogenation method described above, preferably, the catalyst loading zone of the fourth hydrogenation reactor is only loaded with the hydrodecarbon catalyst (i.e. the loading amount of the hydrodecarbon catalyst is 25% of the volume of the total reaction zone), which can avoid catalyst backmixing when hydrogen lifts the catalyst bed of the fourth hydrogenation reactor.

[0018] In the present application, the hydrogenation guard catalyst, the hydrodemetallization catalyst, the hydrodesulfurization catalyst and the hydrodecarbon catalyst can use the corresponding catalysts in the field of residue hydrogenation disclosed in the prior art. Preferably, the hydrogenation guard catalyst, the hydrodemetallization catalyst, the hydrodesulfurization catalyst and the hydrodecarbon catalyst can use the PHR series of residue hydrogenation catalysts developed by China Petroleum Group Petrochemical Research Institute.

[0019] In the fixed bed residue hydrogenation method described above, preferably, the residue raw material comprises atmospheric residue and / or vacuum residue, etc. More preferably, the S content in the residue raw material is 4.5% by weight or less, the MCR is 15% by weight or less, and the total metal content is 150 μg / g or less.

[0020] In the fixed bed residual oil hydrogenation method described above, preferably, in step (1), the conditions of the hydrogenation reactions in the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor respectively include: hydrogen partial pressure of 10-30 MPa, reaction temperature of 320-420℃, volume space velocity of 0.1-6.5 h -1 -1 calculated based on residual oil, and volume ratio of hydrogen to residual oil of 500-2000. More preferably, the conditions of the hydrogenation reactions in the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor respectively include: hydrogen partial pressure of 15-20 MPa, reaction temperature of 350-390℃, volume space velocity of 0.1-1.0 h -1 -1 calculated based on residual oil, and volume ratio of hydrogen to residual oil of 500-1000. It should be noted that the hydrogenation reaction conditions of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor can be the same or different, as long as they are within the above ranges.

[0021] In the fixed bed residual oil hydrogenation method described above, preferably, in step (2), the separation of the mixture of desulfurized residual oil and hydrogen obtained in step (1) is achieved by a hot high-pressure separator.

[0022] In the fixed bed residual oil hydrogenation method described above, preferably, in step (2), the S content in the desulfurized residual oil is ≤0.45 wt%. If the sulfur content in the desulfurized residual oil does not reach 0.45 wt% or less, the reaction temperature in one or more of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor can be appropriately increased within the above range until the sulfur content in the desulfurized residual oil meets the requirements.

[0023] In the fixed bed residual oil hydrogenation method described above, preferably, in step (3), the heating of the desulfurized residual oil obtained in step (2) to 420-480℃ is achieved by a heating furnace.

[0024] In the fixed bed residual oil hydrogenation method described above, preferably, in step (3), the desulfurized residual oil obtained in step (2) is heated to 430-450℃.

[0025] In the fixed bed residual oil hydrogenation method described above, preferably, in step (3), after the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor, it is uniformly distributed through the gas distributor provided in the fourth hydrogenation reactor, and then reacts with the heated desulfurized residual oil for hydrocracking.

[0026] In the fixed bed residual oil hydrogenation method described above, preferably, in step (3), the conditions of the hydrocracking reaction in the fourth hydrogenation reactor include: hydrogen partial pressure of 10-30 MPa, reaction temperature of 420-480℃, volume space velocity of 0.2-10.0 h-1 calculated based on residual oil, and volume ratio of hydrogen to residual oil of 200-1500. More preferably, the conditions of the hydrocracking reaction in the fourth hydrogenation reactor include: hydrogen partial pressure of 15-20 MPa, reaction temperature of 430-450℃, volume space velocity of 0.2-2.0 h-1 calculated based on residual oil, and volume ratio of hydrogen to residual oil of 500-1000. -1 -1

[0027] According to the specific embodiment of the present application, preferably, the fixed bed residual oil hydrogenation method further comprises step (4): subjecting the residual oil hydrogenation product obtained in step (3) to fractionation in a fractionation device to obtain light distillate oil, 3-4 ring aromatic hydrocarbon-rich distillate oil, and hydrogenated residual oil. The light distillate oil is distillate oil with a boiling point below 350℃, the 3-4 ring aromatic hydrocarbon-rich distillate oil is distillate oil with a boiling point of 350-460℃, and the hydrogenated residual oil is distillate oil with a boiling point above 460℃. More preferably, the weight content of 3-4 ring aromatic hydrocarbons in the 3-4 ring aromatic hydrocarbon-rich distillate oil is 50-90%.

[0028] The second aspect of the present application provides a fixed bed residual oil hydrogenation system for implementing the fixed bed residual oil hydrogenation method described above, which comprises: a first hydrogenation reactor, a second hydrogenation reactor, a third hydrogenation reactor, a hot high-pressure separator, a heating furnace, and a fourth hydrogenation reactor.

[0029] The top of the first hydrogenation reactor, the top of the second hydrogenation reactor, and the top of the third hydrogenation reactor are respectively provided with inlets, and the bottoms are respectively provided with outlets, and the first hydrogenation reactor, the second hydrogenation reactor, and the third hydrogenation reactor are connected in series.

[0030] The hot high-pressure separator is provided with an inlet, a desulfurized residual oil outlet, and a hydrogen outlet.

[0031] The heating furnace is provided with an inlet and an outlet.

[0032] The top of the fourth hydrogenation reactor is provided with a heated desulfurized residual oil inlet, and the bottom is provided with a hydrogen inlet and a residual oil hydrogenation product outlet.

[0033] ​​The outlet at the bottom of the third hydrogenation reactor is connected to the inlet of the hot high-pressure separator by a pipeline, the desulfurized residue oil outlet of the hot high-pressure separator is connected to the inlet of the heating furnace by a pipeline, the outlet of the heating furnace is connected to the heated desulfurized residue oil inlet at the top of the fourth hydrogenation reactor by a pipeline, the hydrogen outlet of the hot high-pressure separator is connected to the hydrogen inlet at the bottom of the fourth hydrogenation reactor by a pipeline, and the product obtained by hydrogenation of the residue oil raw material flows out from the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor.

[0034] In the fixed-bed residue oil hydrogenation system described above, preferably, a gas distributor is arranged inside the fourth hydrogenation reactor, and the gas distributor is arranged above the hydrogen inlet. The gas distributor can be a gas distributor in the prior art, and the structure thereof is not specially limited in the present application.

[0035] In the fixed-bed residue oil hydrogenation system described above, preferably, the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor are all down-flow fixed-bed hydrogenation reactors. The structures of the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor are not specially limited in the present application, and down-flow fixed-bed hydrogenation reactors in the prior art can be used. The structure of the fourth hydrogenation reactor is basically the same as that of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor, and the difference is that a hydrogen inlet is additionally arranged at the bottom of the fourth hydrogenation reactor and a gas distributor for uniformly distributing hydrogen is additionally arranged inside the fourth hydrogenation reactor.

[0036] According to the specific embodiment of the present application, preferably, the fixed-bed residue oil hydrogenation system further comprises a fractionation device, and the fractionation device is provided with an inlet, a light distillate oil outlet, an aromatic-rich distillate oil outlet and a hydrogenated residue oil outlet, and the inlet of the fractionation device is connected to the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor by a pipeline.

[0037] A conventional fixed-bed residue oil hydrogenation treatment device usually adopts four hydrogenation reactors. The first reactor is a hydrogenation protection reactor, which mainly functions to filter mechanical impurities and remove Fe and Ca in the residue oil; the second reactor is a hydrogenation demetallization reactor, which mainly functions to make the residue oil undergo a demetallization reaction to remove Ni and V in the residue oil, and also to deposit a small amount of Fe and Ca; the third reactor is a hydrogenation desulfurization reactor, which mainly functions to make the residue oil undergo a desulfurization reaction to remove sulfur in the residue oil; and the fourth reactor is a hydrogenation de-residual carbon reactor, which mainly functions to make the residue oil undergo a de-residual carbon reaction to reduce the content of residual carbon in the residue oil. The working temperature of the four hydrogenation reactors is usually 350-430°C, but the running temperature is usually not higher than 390°C, because when the hydrogenation reaction temperature of the residue oil is higher than 390°C, the coking rate of the reactor increases exponentially, which leads to rapid reaching of the upper limit of the pressure drop of the residue oil hydrogenation treatment device and shutdown.

[0038] Residue hydrocracking process can produce more high-quality light distillate oil than residue hydrotreating process, and has better economic benefits, but it is difficult to realize high-temperature residue hydrocracking process in fixed-bed residue hydrogenation device, because residue hydrocracking process is more prone to coking than hydrocarbon residue removal process, so that residue hydrocracking cokes in a short time and cannot be stably operated.

[0039] The present application improves the traditional fixed-bed residue hydrotreating process, and provides a new type of fixed-bed residue hydrogenation method and system. The present application adds a hot high-pressure separator and a heating furnace at the front end of the fourth hydrogenation reactor, adds a hydrogen inlet at the bottom of the fourth hydrogenation reactor and adds a gas distributor inside for uniform distribution of hydrogen; the mixture of desulfurized residue oil and hydrogen flowing out of the third hydrogenation reactor is separated in the hot high-pressure separator, the separated desulfurized residue oil (i.e. liquid phase material) is introduced into the heating furnace to be raised to a suitable temperature, and is introduced into the fourth hydrogenation reactor from the top, the separated hydrogen (i.e. gas phase material) is introduced into the fourth hydrogenation reactor from the bottom, and is uniformly distributed after passing through the gas distributor, and is reacted with the desulfurized residue oil for hydrocracking to generate more 3-4 ring aromatic hydrocarbons, at the same time, the catalyst bed is lifted and the bed is expanded, the porosity of the bed is increased, and the probability of catalyst coking is reduced. The present inventors have found that under the high-temperature hydrocracking reaction conditions of 420-480℃ (especially 430-450℃) of the desulfurized residue oil, the content of 3-4 ring aromatic hydrocarbons in the residue hydrogenation product can be greatly increased. However, as mentioned above, when the hydrogenation reaction temperature of the residue oil exceeds 390℃, the coking rate of the reactor increases exponentially, resulting in rapid pressure drop of the residue hydrogenation device to reach the upper limit and shutdown. While the fourth hydrogenation reactor is raised to a temperature suitable for generating 3-4 ring aromatic hydrocarbons, hydrogen is introduced from the bottom of the fourth hydrogenation reactor to slightly expand the catalyst bed, thereby increasing the porosity of the bed, preventing catalyst coking, and stably operating the fixed-bed residue hydrocracking process.

[0040] The fixed-bed residue hydrogenation method and system of the present application effectively increase the yield of 3-4 ring aromatic hydrocarbon-rich distillate oil in the residue hydrogenation product, greatly increase the yield of light distillate oil, increase the depth of residue hydrocracking and reduce the carbon residue value of the hydrogenated residue oil. After the fractionation device, the 3-4 ring aromatic hydrocarbon-rich distillate oil obtained can be used to produce high-end carbon materials, the light distillate oil can be used to produce gasoline and diesel, and the low carbon residue value of the hydrogenated residue oil can effectively improve the light oil yield of the subsequent catalytic cracking process, thereby greatly improving the economic benefits of the overall fixed-bed residue hydrogenation process and system.

[0041] The technical scheme of the present application has at least the following beneficial effects:

[0042] Firstly, the present application can effectively avoid the coking and hardening of the catalyst bed, avoid the rapid rise of pressure drop, and make the residue oil hydrocracking process run stably by separating hydrogen from the material and introducing it from the bottom of the fourth hydrogenation reactor, i.e. the hydrogenation residual carbon removal reactor, to slightly lift the catalyst bed and increase the porosity of the bed.

[0043] Secondly, the present application determines the appropriate residue oil hydrocracking reaction temperature, which can make the polycyclic aromatic hydrocarbons in the residue oil hydrocracking to generate 3-4 ring aromatic hydrocarbons, effectively improve the yield of 3-4 ring aromatic hydrocarbon distillate oil in the residue oil hydrogenation product, and effectively improve the quality of carbon materials as raw materials to produce carbon materials, and too high or too low reaction temperature will lead to different target products of the residue oil.

[0044] Thirdly, the present application can also increase the yield of light distillate oil and greatly reduce the carbon residue value of hydrogenated residue oil, thereby improving the economic benefits of the fixed bed residue oil hydrogenation process and system. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The flow chart of the fixed bed residue oil hydrogenation method and the structure of the fixed bed residue oil hydrogenation system provided for Examples 1-5 are shown in the schematic diagram.

[0046] Explanation of reference numerals:

[0047] 1-First hydrogenation reactor; 2-Second hydrogenation reactor; 3-Third hydrogenation reactor; 4-Hot high-pressure separator; 5-Heating furnace; 6-Fourth hydrogenation reactor; 7-Fractionation device. DETAILED DESCRIPTION

[0048] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail below, but it cannot be understood as limiting the scope of the present application.

[0049] In Examples 1-5 and Comparative Examples 1-3 below, the same residue oil raw material was used, which was Kuwait atmospheric residue, and its specific properties are shown in Table 1.

[0050] Table 1 Properties of residue oil raw material

[0051] Item Atmospheric residue Density (20°C), g / cm 3 ]] 0.978 Sulfur, wt% 4.50 Nitrogen, wt% 0.42 Metal content (Ni+V), ppm 12.5 Asphaltene, wt% 78.8 Aromatics, wt% 4.0 Figure 1 40.7

[0052] The method for producing the needle coke sample from the obtained aromatic distillate oil is the same in the following Examples 1-5 and Comparative Examples 1-3. The method comprises: placing 100 g of the sample of the aromatic distillate oil in a labeled quartz test tube, the test tube having a diameter of 20 mm and a depth of 180 mm; then placing the quartz test tube into a 50 mL micro-reactor, tightening the reactor body, replacing the air in the reactor with nitrogen, and filling the nitrogen to 3 MPa; then heating the micro-reactor to 420 ℃, and reacting for 8 h; then increasing the temperature of the micro-reactor to 480 ℃, reducing the pressure to 0.75 MPa, and carbonizing for 4 h to prepare the semicoke; then removing the heating jacket of the micro-reactor, and circulating cooling water to rapidly cool to terminate the reaction, thereby preparing the needle coke.

[0053] Example 1

[0054] This example provides a fixed bed residual oil hydrogenation method, as shown in FIG. 1, which comprises the following steps: Figure 1

[0055] (1) passing the residual oil raw material and hydrogen through the first hydrogenation reactor 1, the second hydrogenation reactor 2, and the third hydrogenation reactor 3 in series in a downflow manner to carry out hydrogenation reaction, thereby obtaining a mixture of desulfurized residual oil and hydrogen;

[0056] (2) separating the mixture of desulfurized residual oil and hydrogen obtained in step (1) through a hot high-pressure separator 4 to obtain desulfurized residual oil and hydrogen;

[0057] (3) heating the desulfurized residual oil obtained in step (2) through a heating furnace 5 to 440 ℃, then introducing the heated desulfurized residual oil into the fourth hydrogenation reactor 6 from the top of the fourth hydrogenation reactor 6, and introducing the hydrogen obtained in step (2) into the fourth hydrogenation reactor 6 from the bottom of the fourth hydrogenation reactor 6, and after being uniformly distributed through the gas distributor provided in the fourth hydrogenation reactor 6, carrying out hydrocracking reaction with the heated desulfurized residual oil, thereby obtaining a residual oil hydrogenation product;

[0058] (4) fractionating the residual oil hydrogenation product obtained in step (3) through a fractionating device 7 to obtain a light distillate oil A1, an aromatic hydrocarbon (3-4 ring)-rich distillate oil B1, and a hydrogenated residual oil C1; the light distillate oil is a distillate oil having a boiling point below 350 ℃, the aromatic hydrocarbon (3-4 ring)-rich distillate oil is a distillate oil having a boiling point of 350 ℃-460 ℃, and the hydrogenated residual oil is a distillate oil having a boiling point above 460 ℃;

[0059] ​The first hydrogenation reactor 1, the second hydrogenation reactor 2, the third hydrogenation reactor 3 and the fourth hydrogenation reactor 6 each comprise a catalyst loading area, and the four catalyst loading areas form a total reaction area; in the total reaction area, a hydrogenation protective catalyst, a hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst and a hydrogenation decarburization catalyst are sequentially loaded along the flow direction of the residual oil; and the catalyst loading area of the fourth hydrogenation reactor 6 is only loaded with the hydrogenation decarburization catalyst.

[0060] The first hydrogenation reactor 1, the second hydrogenation reactor 2, the third hydrogenation reactor 3 and the fourth hydrogenation reactor 6 in the embodiment are all down-flow fixed-bed hydrogenation reactors, the structure of the fourth hydrogenation reactor 6 is basically the same as that of the first three reactors, and the difference lies in that a hydrogen inlet is additionally arranged at the bottom of the fourth hydrogenation reactor 6 and a gas distributor for uniformly distributing hydrogen is additionally arranged inside the fourth hydrogenation reactor 6. The four reactors can be residual oil hydrogenation reactors in the prior art. Specifically, the fixed-bed residual oil hydrogenation 1000ml pilot plant produced by the American Xytel Company is adopted in the embodiment, and the pilot plant comprises four hydrogenation reactors. After being pressurized to the reaction pressure by a pressure booster and mixed with hydrogen, the residual oil raw material is heated by a heating device and then sequentially enters the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 for hydrogenation reaction, and then enters a hot high-pressure separator 4 to separate hydrogen from the residual oil. The hydrogen enters from the bottom of the fourth reactor 6, and the residual oil is heated to a suitable high temperature by a heating furnace 5 and then enters the fourth reactor 6 from the top, so that the gas-liquid countercurrent contact reaction is realized.

[0061] In the embodiment, the loading amount of the hydrogenation protective catalyst is 5% of the volume of the total reaction area, the loading amount of the hydrogenation demetallization catalyst is 40% of the volume of the total reaction area, the loading amount of the hydrogenation desulfurization catalyst is 30% of the volume of the total reaction area, and the loading amount of the hydrogenation decarburization catalyst is 25% of the volume of the total reaction area.

[0062] The hydrogenation protective catalyst, the hydrogenation demetallization catalyst, the hydrogenation desulfurization catalyst and the hydrogenation decarburization catalyst adopted in the embodiment are all PHR series residual oil hydrogenation catalysts developed by the Petrochemical Research Institute of China Petroleum Group.

[0063] In the embodiment, the hydrogenation reaction conditions in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 are the same, and are as follows: the hydrogen partial pressure is 16.0MPa, the volume space velocity calculated according to the residual oil is 0.27hr -1, the volume ratio of hydrogen and residue oil is 1000. The reaction temperature of the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 is controlled by taking the sulfur content in the desulfurized residue oil ≤0.45% as a control index, and if the sulfur content exceeds the standard, the reaction temperature in one or more of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor can be increased until the sulfur content in the desulfurized residue oil meets the requirement. In this embodiment, the reaction temperature of the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 is 350-390℃.

[0064] In this embodiment, the hydrogenation cracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation desulfurization reactor) are as follows: the hydrogen partial pressure is 16.0 MPa, the reaction temperature is 440℃, the volume space velocity calculated according to the residue oil is 0.27h -1 , and the volume ratio of hydrogen and residue oil is 1000.

[0065] This embodiment also provides a fixed bed residue oil hydrogenation system for realizing the fixed bed residue oil hydrogenation method described above, as shown in FIG. 1, which comprises: ​

[0066] a first hydrogenation reactor 1, a second hydrogenation reactor 2, a third hydrogenation reactor 3, a hot high-pressure separator 4, a heating furnace 5, a fourth hydrogenation reactor 6 and a fractionation device 7;

[0067] The top of the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 is respectively provided with an inlet, and the bottom is respectively provided with an outlet, and the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 are connected in series;

[0068] The hot high-pressure separator 4 is provided with an inlet, a desulfurized residue oil outlet and a hydrogen outlet;

[0069] The heating furnace 5 is provided with an inlet and an outlet;

[0070] The top of the fourth hydrogenation reactor 6 is provided with a desulfurized residue oil inlet after heating, and the bottom is provided with a hydrogen inlet and a residue oil hydrogenation product outlet; the inside of the fourth hydrogenation reactor 6 is provided with a gas distributor, which is arranged above the hydrogen inlet;

[0071] The fractionation device 7 is provided with an inlet, a light distillate oil outlet, an aromatic-rich distillate oil outlet and a hydrogenated residue oil outlet;

[0072] ​The outlet at the bottom of the third hydrogenation reactor 3 is connected by a pipeline to the inlet of a hot high-pressure separator 4, the desulfurized residue oil outlet of the hot high-pressure separator 4 is connected by a pipeline to the inlet of a heating furnace 5, the outlet of the heating furnace 5 is connected by a pipeline to the heated desulfurized residue oil inlet at the top of a fourth hydrogenation reactor 6, the hydrogen gas outlet of the hot high-pressure separator 4 is connected by a pipeline to the hydrogen gas inlet at the bottom of the fourth hydrogenation reactor 6, the product obtained after hydrogenation of the residue oil feedstock flows out from the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor 6, the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor 6 is connected by a pipeline to the inlet of a fractionation device 7, the light distillate oil Al, the distillate oil Bl rich in aromatic hydrocarbons and the hydrogenated residue oil Cl flow out from the light distillate oil outlet, the distillate oil outlet rich in aromatic hydrocarbons and the hydrogenated residue oil outlet respectively.

[0073] The initial pressure drop of the fourth hydrogenation reactor 6 is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 8500 hours. Moreover, the distillate oil Bl rich in aromatic hydrocarbons is carbonized according to the above method to produce needle coke, and needle coke Dl is obtained, and its properties are shown in Table 2.

[0074] Example 2

[0075] This example provides a fixed bed residue oil hydrogenation method, and the fixed bed residue oil hydrogenation system used in this method is the same as that in Example 1. The difference between this method and Example 1 is that the hydrogenation cracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation desulfurization reactor) are as follows: the hydrogen gas partial pressure is 20.0 MPa, the reaction temperature is 450°C, the volume space velocity calculated according to the residue oil is 2.0 h -1 -1, and the volume ratio of hydrogen gas to residue oil is 1000. The catalysts filled in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 and their filling amounts, and the reaction conditions in the three hydrogenation reactors are the same as those in Example 1. Finally, the light distillate oil A2, the distillate oil B2 rich in aromatic hydrocarbons and the hydrogenated residue oil C2 are obtained.

[0076] The initial pressure drop of the fourth hydrogenation reactor 6 is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 8100 hours. Moreover, the distillate oil Bl rich in aromatic hydrocarbons is carbonized according to the above method to produce needle coke, and needle coke Dl is obtained, and its properties are shown in Table 2.

[0077] Example 3

[0078] The present example provides a fixed bed residual oil hydrogenation method, which uses the same fixed bed residual oil hydrogenation system as that of Example 1. The difference between the method and Example 1 is that the desulfurized residual oil is heated to 460°C by the heating furnace 5, and the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation residual carbon removal reactor) are that the hydrogen partial pressure is 15.0 MPa, the reaction temperature is 430°C, the volume space velocity calculated according to the residual oil is 0.2 h -1 , and the volume ratio of hydrogen to residual oil is 500. The catalysts filled in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 and their filling amounts, and the reaction conditions in the three hydrogenation reactors are the same as those of Example 1. Finally, the light distillate oil A3, the aromatic-rich distillate oil B3 and the hydrogenated residual oil C3 are obtained.

[0079] The initial pressure drop of the fourth hydrogenation reactor 6 is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 7600 hours. In addition, the aromatic-rich distillate oil B3 is carbonized according to the above method to produce needle coke, and the needle coke D3 is obtained, and its properties are shown in Table 2.

[0080] Example 4

[0081] The present example provides a fixed bed residual oil hydrogenation method, which uses the same fixed bed residual oil hydrogenation system as that of Example 1. The difference between the method and Example 1 is that the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation residual carbon removal reactor) are that the hydrogen partial pressure is 10.0 MPa, the reaction temperature is 420°C, the volume space velocity calculated according to the residual oil is 0.2 h -1 , and the volume ratio of hydrogen to residual oil is 200. The catalysts filled in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 and their filling amounts, and the reaction conditions in the three hydrogenation reactors are the same as those of Example 1. Finally, the light distillate oil A4, the aromatic-rich distillate oil B4 and the hydrogenated residual oil C4 are obtained.

[0082] The initial pressure drop of the fourth hydrogenation reactor 6 is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 5200 hours. In addition, the aromatic-rich distillate oil B4 is carbonized according to the above method to produce needle coke, and the needle coke D4 is obtained, and its properties are shown in Table 2.

[0083] Example 5

[0084] The present example provides a fixed bed residual oil hydrogenation method, which uses the same fixed bed residual oil hydrogenation system as that of Example 1. The difference between the method and Example 1 is that the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation de-residue carbon reactor) are as follows: hydrogen partial pressure is 30.0 MPa, reaction temperature is 480°C, volume space velocity calculated according to residual oil is 10.0 h -1 -1, volume ratio of hydrogen and residual oil is 1500. The catalysts filled in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 and their filling amounts, and the reaction conditions in the three hydrogenation reactors are all the same as those of Example 1. Finally, light distillate oil A5, aromatic-rich distillate oil B5 and hydrogenated residual oil C5 are obtained.

[0085] The initial pressure drop of the fourth hydrogenation reactor 6 is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 5900 hours. Moreover, the aromatic-rich distillate oil B5 is carbonized according to the above method to produce needle coke, and needle coke D5 is obtained, the properties of which are shown in Table 2.

[0086] Comparative Example 1

[0087] The present example provides a fixed bed residual oil hydrogenation method, which uses the same fixed bed residual oil hydrogenation system as that of Example 1. The difference between the method and Example 1 is that the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e. the hydrogenation de-residue carbon reactor) are as follows: hydrogen partial pressure is 30.0 MPa, reaction temperature is 480°C, volume space velocity calculated according to residual oil is 10.0 h -1 -1, volume ratio of hydrogen and residual oil is 1500. The catalysts filled in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 and their filling amounts, and the reaction conditions in the three hydrogenation reactors are all the same as those of Example 1. Finally, light distillate oil A5, aromatic-rich distillate oil B5 and hydrogenated residual oil C5 are obtained.

[0088] The initial pressure drop of the fourth hydrogenation reactor is 0.15 MPa, and the operation is stopped when the pressure drop rises to 0.50 MPa, and the overall running time is recorded as 2500 hours. Moreover, the aromatic-rich distillate oil b1 is carbonized according to the above method to produce needle coke, and needle coke d1 is obtained, the properties of which are shown in Table 2.

[0089] Comparative Example 2

[0090] This comparative example provides a fixed-bed residue hydrotreating method, which is basically the same as that in Example 1, except that: the desulfurized residue is heated to 410°C in a heater, and the hydrocracking reaction conditions in the fourth hydrotreating reactor (i.e., the hydrocracking and decarbonization reactor) are: hydrogen partial pressure of 16.0 MPa, reaction temperature of 410°C, and volume hourly space velocity (VHSV) calculated based on the residue is 0.27 h⁻¹. -1 The volume ratio of hydrogen to residue oil was 1000, ultimately yielding light distillate oil a2, aromatic-rich distillate oil b2, and hydrogenated residue oil c2. The catalysts and their loading amounts in the first, second, and third hydrogenation reactors, as well as the reaction conditions in the three hydrogenation reactors, were the same as in Example 1.

[0091] The initial pressure drop of the fourth hydrogenation reactor was 0.15 MPa. Operation was stopped when the pressure drop rose to 0.50 MPa, and the total operating time was recorded as 10,500 hours. Furthermore, the aromatic-rich distillate oil b2 was carbonized using the method described above to produce needle coke, yielding needle coke d2, the properties of which are shown in Table 2.

[0092] Comparative Example 3

[0093] This comparative example provides a fixed-bed residue hydrotreating method, which is basically the same as that in Example 1, except that: the desulfurized residue is heated to 490°C in a heater, and the hydrocracking reaction conditions in the fourth hydrotreating reactor (i.e., the hydrocracking and decarbonization reactor) are: hydrogen partial pressure of 16.0 MPa, reaction temperature of 490°C, and volume hourly space velocity (VHSV) calculated based on the residue is 0.27 h⁻¹. -1 The volume ratio of hydrogen to residual oil was 1000, ultimately yielding light distillate oil a3, aromatic-rich distillate oil b3, and hydrogenated residual oil c3. The catalysts and their loading amounts in the first, second, and third hydrogenation reactors, as well as the reaction conditions in the three hydrogenation reactors, were the same as in Example 1.

[0094] The initial pressure drop of the fourth hydrogenation reactor was 0.15 MPa. Operation was stopped when the pressure drop rose to 0.50 MPa, and the total operating time was recorded as 3500 hours. Furthermore, the aromatic-rich distillate oil b3 was carbonized using the method described above to produce needle coke, yielding needle coke d3, the properties of which are shown in Table 2.

[0095] Table 2. Product Properties of Hydrogenated Residue Oil and Needle Coke

[0096]

[0097]

[0098] As can be seen from the results of Example 1, the fixed bed residual oil hydrogenation method and system provided by the embodiment of the present application effectively improves the yield of the 3-4 ring aromatic hydrocarbon fraction oil in the residual oil hydrogenation product, greatly improves the yield of the light fraction oil, increases the depth of residual oil hydrocracking and reduces the carbon residue value of the hydrogenated residual oil, and enables the fixed bed residual oil hydrocracking process to be stably operated. As can be seen from the results of Example 2 and Example 3, operating within the upper limit and lower limit of the optimal operating conditions given by the present application has no effect on the product properties, and the operating time changes little. As can be seen from Example 4 and Example 5, operating within the upper limit and lower limit of the range given by the present application has no effect on the product properties, but the operating time is shorter. As can be seen from the results of Example 1 and Comparative Example 1, feeding the desulfurized residual oil and hydrogen from the top of the fourth hydrogenation reactor will greatly shorten the operating cycle of the residual oil hydrogenation system. As can be seen from the results of Example 1, Comparative Example 2 and Comparative Example 3, lower or higher than the reaction temperature range of the hydrocracking in the fourth hydrogenation reactor given by the present application will result in a decrease in the content of 3-4 ring aromatic hydrocarbons in the product, thereby affecting the interlayer distance, layer height and grain size of the needle coke crystalline grains, and it is difficult to achieve the quality of the needle coke of Example 1.

Claims

1. A method for hydrogenating fixed-bed residue oil, comprising the following steps: (1) The residual oil feedstock and hydrogen are sequentially passed through a first hydrogenation reactor, a second hydrogenation reactor, and a third hydrogenation reactor in a downflow manner to carry out hydrogenation reactions, thereby obtaining a mixture of desulfurized residual oil and hydrogen; the conditions for the hydrogenation reactions in the first hydrogenation reactor, the second hydrogenation reactor, and the third hydrogenation reactor are respectively: hydrogen partial pressure of 10~30MPa, reaction temperature of 320~420℃, and volume hourly space velocity calculated based on residual oil of 0.1~6.5h. -1 The volume ratio of hydrogen to residual oil is 500~2000; (2) Separate the mixture of desulfurized residue oil and hydrogen obtained in step (1) to obtain desulfurized residue oil and hydrogen; (3) The desulfurized residue obtained in step (2) is heated to 420~480℃, and then the heated desulfurized residue is introduced into the fourth hydrogenation reactor from the top. The hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom, and the hydrogen is subjected to a hydrocracking reaction with the heated desulfurized residue to obtain the residue hydrogenation product. The conditions for the hydrocracking reaction in the fourth hydrogenation reactor include: hydrogen partial pressure of 10~30MPa, reaction temperature of 420~480℃, and volume hourly space velocity calculated based on residue of 0.2~10.0h. -1 The volume ratio of hydrogen to residual oil is 200~1500.

2. The fixed-bed residue hydrotreating method according to claim 1, wherein, The first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor, and the fourth hydrogenation reactor each include a catalyst loading zone, and the four catalyst loading zones constitute a total reaction zone. In the total reaction zone, four or more hydrogenation catalysts, including a hydrogenation protection catalyst, a hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst, and a hydrogenation decarbonization catalyst, are sequentially loaded along the direction of residue oil flow.

3. The fixed-bed residue hydrotreating method according to claim 2, wherein, The catalyst loading zone of the fourth hydrogenation reactor is filled only with the hydrogenation decarbonization catalyst.

4. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (1), the conditions for the hydrogenation reactions in the first, second, and third hydrogenation reactors respectively include: a hydrogen partial pressure of 15-20 MPa, a reaction temperature of 350-390 °C, and a volume hourly space velocity (VHSV) calculated based on the residue oil of 0.1-1.0 h⁻¹. -1 The volume ratio of hydrogen to residual oil is 500~1000.

5. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (2), the mixture of desulfurized residue oil and hydrogen obtained in step (1) is separated by a hot high-pressure separator.

6. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (3), the desulfurized residue oil obtained in step (2) is heated to 420~480℃ by a heating furnace.

7. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (3), the desulfurized residue oil obtained in step (2) is heated to 430~450℃.

8. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (3), the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor. After being evenly distributed by the gas distributor set in the fourth hydrogenation reactor, it is then subjected to a hydrocracking reaction with the heated desulfurized residue oil.

9. The fixed-bed residue hydrotreating method according to claim 1, wherein, In step (3), the conditions for the hydrocracking reaction in the fourth hydroreactor include: a hydrogen partial pressure of 15-20 MPa, a reaction temperature of 430-450 °C, and a volume hourly space velocity (VHSV) calculated based on the residue oil of 0.2-2.0 h⁻¹. -1 The volume ratio of hydrogen to residual oil is 500~1000.

10. The fixed-bed residue hydrotreating method according to claim 1, wherein, The fixed-bed residue hydrotreating method further includes step (4): the residue hydrotreating product obtained in step (3) is fractionated by a fractionating device to obtain light distillate oil, distillate oil rich in 3-4 ring aromatics and hydrotreating residue oil.

11. A fixed-bed residue hydrotreating system, said system being used to implement the fixed-bed residue hydrotreating method according to any one of claims 1-10, said system comprising: The reactor consists of a first hydrogenation reactor, a second hydrogenation reactor, a third hydrogenation reactor, a hot high-pressure separator, a heater, and a fourth hydrogenation reactor. The first hydrogenation reactor, the second hydrogenation reactor, and the third hydrogenation reactor are respectively provided with inlets at the top and outlets at the bottom, and are connected in series. The hot high-pressure separator is equipped with an inlet, a desulfurized residue oil outlet, and a hydrogen outlet. The heating furnace is equipped with an inlet and an outlet; The fourth hydrogenation reactor is equipped with a heated desulfurized residue oil inlet at the top and a hydrogen inlet and a residue oil hydrogenation product outlet at the bottom. The outlet at the bottom of the third hydrogenation reactor is connected to the inlet of the thermal high-pressure separator via a pipeline. The desulfurized residue oil outlet of the thermal high-pressure separator is connected to the inlet of the heater via a pipeline. The outlet of the heater is connected to the heated desulfurized residue oil inlet at the top of the fourth hydrogenation reactor via a pipeline. The hydrogen outlet of the thermal high-pressure separator is connected to the hydrogen inlet at the bottom of the fourth hydrogenation reactor via a pipeline. The product obtained after hydrogenation of the residue oil feedstock flows out from the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor.

12. The fixed-bed residue hydrotreating system according to claim 11, wherein, The fourth hydrogenation reactor is equipped with a gas distributor located above the hydrogen inlet.

13. The fixed-bed residue hydrotreating system according to claim 11, wherein, The fixed-bed residue hydrotreating system further includes a fractionation unit, which is provided with an inlet, a light distillate oil outlet, an aromatics-rich distillate oil outlet, and a hydrotreating residue oil outlet. The inlet of the fractionation unit is connected to the residue hydrotreating product outlet at the bottom of the fourth hydrotreating reactor via a pipeline.

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