Fixed bed residual oil hydrogenation method and system

Abstract

The invention provides a fixed bed residual oil hydrogenation method and system. The method comprises the following steps: enabling a residual oil raw material and hydrogen to sequentially pass through a first hydrogenation reactor, a second hydrogenation reactor and a third hydrogenation reactor which are connected in series in a down-flow manner for hydrogenation reaction to obtain a mixture of desulfurized residual oil and hydrogen; separating the mixture of the desulfurized residual oil and the hydrogen to obtain the desulfurized residual oil and the hydrogen; and heating the separated desulfurized residual oil to 420-480 DEG C, introducing the heated 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 carrying out a hydrocracking reaction to obtain a residual oil hydrogenation product. According to the method and the system, the yield of distillate oil rich in 3-4 ring aromatic hydrocarbons in the residual oil hydrogenation product is increased, the yield of light distillate oil is increased, and the carbon residue value of the hydrogenated residual oil is reduced, so that the economic benefits of the whole fixed bed residual oil hydrogenation process and system are increased.

Description

Technical Field

[0001] The invention belongs to the technical field of residual oil hydrogenation process, and in particular relates to a fixed-bed residual oil hydrogenation method and system. Background Art

[0002] In the petroleum refining industry, as crude oil becomes heavier and inferior, and environmental protection requirements become increasingly stringent, the fixed-bed residue oil hydrogenation process has gradually become a crucial process. Due to the increasing overcapacity of refining capacity, fierce market competition, and meager profits in the crude oil processing process, it is increasingly important to improve the operating level and economic benefits of refining units. More and more refining companies are beginning to consider improving existing fixed-bed residue oil hydrogenation units and processes to produce aromatic-rich distillates suitable for the preparation of carbon materials. Studies have shown that the coking rate of 3-4-ring aromatics is moderate, which is conducive to the growth of carbon material grains and is suitable for the production of high-end carbon materials. Therefore, various refining companies have studied and improved residue oil hydrogenation units and processes to increase the yield of 3-4-ring aromatics.

[0003] CN102816597A discloses a residual oil hydroprocessing process. In this process, a feed port is added before the demetallizing agent bed of the residual oil hydroprocessing device. The residual oil and hydrogen enter the device through the original feed port of the residual oil hydroprocessing device for reaction, and the catalytic cracking recycled oil enters the device through the added feed port for reaction. The residual oil hydroprocessing device adopts catalyst grading filling, which includes three or more hydrogenation catalysts including protective agent, demetallizing agent and desulfurizing agent in sequence. Each catalyst is divided into a bed layer for filling, and the protective agent bed layer adopts an upflow reactor or a fixed bed reactor. The method can improve the impurity removal rate of residual oil hydroprocessing, not only inhibits the coking of the bed layer, prolongs the operation cycle of the residual oil hydroprocessing device, but also greatly increases the yield of high value-added light fractions.

[0004] CN102816599A discloses a combined process for residual oil hydroprocessing. In this process, a feed port is added before the desulfurizer bed of the residual oil hydroprocessing unit, and the residual oil and hydrogen enter the unit through the original feed port of the residual oil hydroprocessing unit for reaction, the hydrogenated residual oil enters the catalytic cracking unit for further reaction, and the catalytic cracking recycled oil returns to the residual oil hydroprocessing unit through the added feed port for hydroprocessing. This process can effectively reduce the carbon deposition of the desulfurizer and the catalyst behind it, extend the operation cycle of the residual oil hydroprocessing unit, increase the yield of high value-added light oil, reduce the use of cold hydrogen, prevent the recycled oil from being over-hydrogenated, maintain high solubility in asphaltene, and achieve the effect of preventing asphaltene from precipitating coke.

[0005] CN102816594A discloses a combined process of residue oil hydroprocessing-catalytic cracking-solvent refining. In this process, the catalytic cracking heavy cycle oil and oil slurry obtained from the catalytic cracking unit are subjected to solvent refining, the solvent refining extracted oil is returned to the residue oil hydroprocessing unit after solid impurities are removed, and enters the unit together with the residue oil for hydroprocessing, the solvent refining raffinate oil is returned to the catalytic cracking unit, and enters the catalytic cracking unit together with the hydrogenated residue oil for further reaction. In this process, the residue oil is converted into high value-added light oil products as much as possible, and the operating condition of the residue oil hydroprocessing unit is improved, and the operating time of the residue oil hydroprocessing unit is extended.

[0006] CN102816598B discloses a method for reducing carbon deposition on a carbon removal catalyst in a residual oil hydroprocessing unit. The method is to add a feed port before the carbon removal agent bed of the residual oil hydroprocessing unit, and introduce 1 to 30% of the weight of the raw material residual oil through the feed port. High aromaticity catalytic cracking recycled oil increases the solubility of the asphaltene gradually precipitated in the raw material oil, thereby reducing the amount of carbon deposition on the catalyst. The method can effectively reduce the carbon deposition on the carbon removal agent and the catalyst behind it, extend the operating cycle of the residual oil hydroprocessing unit, and reduce the amount of cold hydrogen used.

[0007] Although the above method increases the proportion of light components in the hydrotreated residue, the content of 3-4 ring aromatic components in the produced hydrotreated residue is low, which is not suitable for the production of high-end carbon materials. Moreover, the operating temperature of the fixed bed residue hydrotreating unit in the above method is usually low, generally at 350-430°C, which also makes the content of 3-4 ring aromatic components in the hydrotreated residue low.

[0008] Therefore, developing a novel fixed-bed residue oil hydrogenation method and system to increase the yield of 3-4-ring aromatic fraction oil suitable for the production of high-end carbon materials remains one of the urgent problems to be solved in this field. Summary of the invention

[0009] In order to solve the above technical problems, the purpose of the present invention is to provide a fixed-bed residue oil hydrogenation method and system. The method and system can increase the yield of 3-4 ring aromatic hydrocarbon fraction oil in the residue oil hydrogenation product.

[0010] In order to achieve the above object, the first aspect of the present invention provides a fixed bed residue oil hydrogenation method, which comprises the following steps:

[0011] (1) allowing the residual oil feedstock and hydrogen to pass through a first hydrogenation reactor, a second hydrogenation reactor, and a third hydrogenation reactor connected in series in a downflow manner to perform a hydrogenation reaction to obtain a mixture of desulfurized residual oil and hydrogen;

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

[0013] (3) The desulfurized residue obtained in step (2) is heated to 420-480° C., and then the heated desulfurized residue is introduced into the fourth hydrogenation reactor from the top of the fourth hydrogenation reactor, and the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor to perform a hydrocracking reaction with the heated desulfurized residue to obtain a residue hydrogenation product.

[0014] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor respectively include catalyst loading areas, and the four catalyst loading areas constitute a total reaction area; in the total reaction area, four or more hydrogenation catalysts including a hydrogenation protection catalyst, a hydrodemetallization catalyst, a hydrodesulfurization catalyst and a hydrodecarbonization catalyst are sequentially loaded along the flow direction of the residue oil.

[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 invention are all downflow fixed bed hydrogenation reactors.

[0016] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, the loading amount of the hydrogenation protection catalyst is 2% to 10% of the volume of the total reaction zone, the loading amount of the hydrodemetallization catalyst is 35% to 70% of the volume of the total reaction zone, the loading amount of the hydrodesulfurization catalyst is 10% to 40% of the volume of the total reaction zone, and the loading amount of the hydroremoval of carbon residue catalyst is 10% to 40% of the volume of the total reaction zone.

[0017] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, the catalyst loading zone of the fourth hydrogenation reactor is only loaded with the hydrogenation carbon removal catalyst (that is, the loading amount of the hydrogenation carbon removal catalyst is 25% of the volume of the total reaction zone), which can avoid catalyst backmixing when hydrogen supports the catalyst bed of the fourth hydrogenation reactor.

[0018] In the present invention, the hydrogenation protection catalyst, the hydrodemetallization catalyst, the hydrodesulfurization catalyst and the hydroremoval of carbon residue catalyst can adopt the corresponding catalysts in the field of residual oil hydrogenation disclosed in the prior art. Preferably, the hydrogenation protection catalyst, the hydrodemetallization catalyst, the hydrodesulfurization catalyst and the hydroremoval of carbon residue catalyst can adopt the PHR series residual oil hydrogenation catalyst developed by the Petrochemical Research Institute of China Petroleum Group.

[0019] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, the residue oil feedstock includes atmospheric residue oil and / or vacuum residue oil, etc. More preferably, the S content in the residue oil feedstock is 4.5 wt% or less, the MCR is 15 wt% or less, and the total metal content is 150 μg / g or less.

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

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

[0022] In the above-mentioned fixed bed residue oil hydrogenation method, preferably, in step (2), the sulfur content in the desulfurized residue oil is ≤0.45 wt %. If the sulfur content in the desulfurized residue oil is less than or equal to 0.45 wt %, the reaction temperature in one or more of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor may be appropriately increased within the above-mentioned range until the sulfur content in the desulfurized residue oil meets the requirement.

[0023] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, in step (3), heating the desulfurized residue oil obtained in step (2) to 420-480° C. is achieved by using a heating furnace.

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

[0025] In the above-mentioned fixed-bed residue oil hydrogenation method, preferably, in step (3), the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor, and then evenly distributed by a gas distributor provided in the fourth hydrogenation reactor, and then subjected to a hydrocracking reaction with the heated desulfurized residue oil.

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

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

[0028] The second aspect of the present invention provides a fixed bed residue oil hydrogenation system, the system is used to implement the above-mentioned fixed bed residue oil hydrogenation method, the system 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 first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor are respectively provided with an inlet at the top and an outlet at the bottom, 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 fourth hydrogenation reactor is provided with a heated desulfurized residual oil inlet at the top, and a hydrogen inlet and a residual oil hydrogenation product outlet at the bottom;

[0033] The outlet at the bottom of the third hydrogenation reactor is connected to the inlet of the hot high-pressure separator through a pipeline, the desulfurized residue oil outlet of the hot high-pressure separator is connected to the inlet of the heating furnace through a pipeline, the outlet of the heating furnace is connected to the inlet of the heated desulfurized residue oil at the top of the fourth hydrogenation reactor through 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 through a pipeline, and 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.

[0034] In the above-mentioned fixed bed residue oil hydrogenation system, preferably, a gas distributor is provided inside the fourth hydrogenation reactor, and the gas distributor is provided above the hydrogen inlet. The gas distributor can adopt a gas distributor in the prior art, and the present invention does not impose any special restrictions on its structure.

[0035] In the above-mentioned fixed-bed residue oil hydrogenation system, preferably, the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor are all downflow fixed-bed hydrogenation reactors. The present invention does not impose any special restrictions on their structures, and a downflow fixed-bed hydrogenation reactor in the prior art can be used. The structure of the fourth hydrogenation reactor is substantially the same as that of the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor, except that a hydrogen inlet is added at the bottom of the fourth hydrogenation reactor and a gas distributor is added inside the fourth hydrogenation reactor for uniformly distributing hydrogen.

[0036] According to a specific embodiment of the present invention, preferably, the fixed-bed residue oil hydrogenation system further comprises: a fractionation device, the fractionation device is provided with an inlet, a light distillate oil outlet, an aromatics-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 through a pipeline.

[0037] Traditional fixed bed residue oil hydroprocessing units usually use four hydrogenation reactors. The first reactor is a hydrogenation protection reactor, which is mainly used to filter mechanical impurities and remove metal Fe and Ca from the residue oil; the second reactor is a hydrodemetallization reactor, which is mainly used to demetallize the residue oil, remove metal Ni and V from the residue oil, and also deposit a small amount of Fe and Ca; the third reactor is a hydrodesulfurization reactor, which is mainly used to desulfurize the residue oil and remove sulfur from the residue oil; the fourth reactor is a hydrodecarbonization reactor, which is mainly used to decarbonize the residue oil and reduce the residual carbon content in the residue oil. The operating temperature of these four hydrogenation reactors is usually 350-430℃, but the operating temperature usually does not exceed 390℃. The reason is that when the hydrogenation reaction temperature of the residue oil exceeds 390℃, the coking rate of the reactor increases exponentially, causing the pressure drop of the residue oil hydroprocessing unit to quickly reach the upper limit and shut down.

[0038] Compared with the residue hydrotreating process, the residue hydrocracking process can produce more high-quality light distillate oil and has better economic benefits. However, it is difficult to achieve the residue high-temperature hydrocracking process in a fixed-bed residue hydrotreating unit because the residue hydrocracking process is more prone to coking than the hydrodecarbonization process, so that the residue hydrocracking process cokes in a short period of time and cannot operate stably.

[0039] The present invention improves the traditional fixed-bed residue oil hydroprocessing process and provides a novel fixed-bed residue oil hydrogenation method and system. The present invention 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 the fourth hydrogenation reactor for evenly distributing the 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) enters the heating furnace and is raised to a suitable temperature, and is introduced into the fourth hydrogenation reactor from the top, and the separated hydrogen (i.e., gas phase material) is introduced into the fourth hydrogenation reactor from the bottom, and after being evenly distributed by the gas distributor, it undergoes a hydrocracking reaction with the desulfurized residue oil to generate more 3-4-ring aromatics, and at the same time, the catalyst bed is lifted and expanded, the bed porosity is increased, and the probability of catalyst coking is reduced. The inventor of this case has found through research that the content of 3-4-ring aromatic hydrocarbons in the residue hydrogenation product can be greatly increased under the high-temperature hydrocracking reaction conditions of 420-480°C (especially 430-450°C) of desulfurized residue. However, as mentioned above, when the hydrogenation reaction temperature of the residue exceeds 390°C, the coking rate of the reactor increases exponentially, causing the pressure drop of the residue hydrogenation unit to quickly reach the upper limit and shut down. While the present invention raises the fourth hydrogenation reactor to a temperature suitable for the generation of 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 bed porosity, preventing the catalyst from coking, and allowing the fixed bed residue hydrocracking process to operate stably.

[0040] The fixed-bed residue oil hydrogenation method and system of the present invention effectively improves the yield of 3-4-ring aromatic hydrocarbon-rich fraction oil in the residue oil hydrogenation product, greatly improves the yield of light distillate oil, increases the depth of residue oil hydrocracking and reduces the carbon residue value of hydrogenated residue oil. After the fractionation device, the obtained 3-4-ring aromatic hydrocarbon-rich fraction oil can be used to produce high-end carbon materials, the light distillate oil can be used to produce gasoline and diesel, and the hydrogenated residue oil with a low carbon residue value 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 oil hydrogenation process and system.

[0041] The technical solution of the present invention has at least the following beneficial effects:

[0042] First, the present invention separates hydrogen from the material and introduces it from the bottom of the fourth hydrogenation reactor, i.e., the hydrogenation decarbonization reactor, so that the catalyst bed can be slightly lifted, the bed can be slightly expanded, and the porosity of the bed can be increased, thereby effectively avoiding coking and hardening of the catalyst bed and avoiding a rapid increase in pressure drop, thereby allowing the residual oil hydrocracking process to operate stably.

[0043] Second, the present invention determines the appropriate residue hydrocracking reaction temperature, which can hydrocracking polycyclic aromatic hydrocarbons in the residue to generate 3-4-ring aromatic hydrocarbons, effectively increasing the yield of 3-4-ring aromatic fraction oil in the residue hydrogenation product, which can be used as a raw material to produce carbon materials and effectively improve the quality of carbon materials. However, too high or too low reaction temperature will cause the residue to generate different target products.

[0044] Third, the present invention can also simultaneously increase the yield of light distillate oil and significantly 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 THE DRAWINGS

[0045] Figure 1 Schematic diagram of the process of the fixed-bed residue oil hydrogenation method and the structure of the fixed-bed residue oil hydrogenation system provided in Examples 1 to 5.

[0046] Description of Figure Numbers:

[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, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0049] In the following Examples 1 to 5 and Comparative Examples 1 to 3, the residual oil raw materials used are the same, all of which are Kuwait atmospheric residual oil, and their specific properties are shown in Table 1.

[0050] Table 1 Properties of residual oil feedstock

[0051] project Atmospheric residue <![CDATA[Density (20 °C), g / cm 3 > 0.978 Sulfur, wt% 4.50 Nitrogen, wt% 0.42 Carbon residue (MCR), wt% 12.5 Metal (Ni+V), ppm 78.8 Asphaltene, wt% 4.0 Aromatic content, wt% 40.7

[0052] In the following Examples 1 to 5 and Comparative Examples 1 to 3, the method for carbonizing the obtained aromatic distillate oil to produce a needle coke sample is the same. The method comprises: placing 100 g of the aromatic distillate oil sample in a numbered quartz test tube, the test tube having a diameter of 20 mm and a depth of 180 mm; then placing the quartz test tube in a 50 mL microreactor and tightening the reactor body, replacing the air in the reactor with nitrogen, and filling the reactor with nitrogen to reach 3 MPa; then heating the microreactor to 420° C. for 8 hours; then raising the temperature of the microreactor to 480° C., reducing the pressure to 0.75 MPa, and carbonizing for 4 hours to prepare semi-coke; then removing the heating jacket of the microreactor, and passing circulating cooling water for rapid cooling to terminate the reaction, and preparing needle coke.

[0053] Example 1

[0054] This embodiment provides a fixed bed residue oil hydrogenation method, such as Figure 1 As shown, it includes the following steps:

[0055] (1) allowing the residual oil feedstock and hydrogen to pass through a first hydrogenation reactor 1, a second hydrogenation reactor 2, and a third hydrogenation reactor 3 connected in series in a downflow manner to perform a hydrogenation reaction to obtain 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) the desulfurized residual oil obtained in step (2) is heated to 440° C. by a heating furnace 5, and then the heated desulfurized residual oil is introduced into the fourth hydrogenation reactor 6 from the top of the fourth hydrogenation reactor 6, and the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor 6 from the bottom of the fourth hydrogenation reactor 6, and after being evenly distributed by a gas distributor provided in the fourth hydrogenation reactor 6, the hydrogen is subjected to a hydrocracking reaction with the heated desulfurized residual oil to obtain a residual oil hydrogenation product;

[0058] (4) subjecting the residue oil hydrogenation product obtained in step (3) to fractionation through a fractionation device 7 to obtain a light distillate oil A1, a distillate oil rich in aromatics (3-4 rings) B1, and a hydrogenated residue oil C1; the light distillate oil is a distillate oil with a boiling point below 350° C., the distillate oil rich in aromatics (3-4 rings) is a distillate oil with a boiling point of 350° C. to 460° C., and the hydrogenated residue oil is a distillate oil with a boiling point above 460° C.;

[0059] Among them, the first hydrogenation reactor 1, the second hydrogenation reactor 2, the third hydrogenation reactor 3 and the fourth hydrogenation reactor 6 respectively include catalyst loading areas, and the four catalyst loading areas constitute a total reaction area; in the total reaction area, a hydrogenation protection catalyst, a hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst and a hydrogenation decarbonization 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 a hydrogenation decarbonization catalyst.

[0060] The first hydrogenation reactor 1, the second hydrogenation reactor 2, the third hydrogenation reactor 3 and the fourth hydrogenation reactor 6 used in this embodiment are all downflow fixed bed hydrogenation reactors. The structure of the fourth hydrogenation reactor 6 is basically the same as the first three reactor structures, except that a hydrogen inlet is added at the bottom of the fourth hydrogenation reactor 6 and a gas distributor is added inside it for making the hydrogen evenly distributed. 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 Xytel Company of the United States is used in this embodiment, and the device includes four hydrogenation reactors. The residual oil raw material is mixed with hydrogen after being boosted to the reaction pressure by a booster device, and then heated by a heating device, and then enters the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 in sequence for hydrogenation reaction, and then enters the hot high-pressure separator 4 to separate hydrogen and residual oil, and hydrogen enters from the bottom of the fourth reactor 6, and the residual oil is heated to a suitable high temperature through a heating furnace 5, and enters the fourth reactor 6 from the top, thereby realizing a gas-liquid two-phase countercurrent contact reaction.

[0061] In this embodiment, the loading amount of the hydrogenation protection catalyst is 5% of the volume of the total reaction zone, the loading amount of the hydrodemetallization catalyst is 40% of the volume of the total reaction zone, the loading amount of the hydrodesulfurization catalyst is 30% of the volume of the total reaction zone, and the loading amount of the hydrodecarbonization catalyst is 25% of the volume of the total reaction zone.

[0062] The hydrogenation protection catalyst, hydrogenation demetallization catalyst, hydrogenation desulfurization catalyst and hydrogenation decarbonization catalyst used in this embodiment are all PHR series residue oil hydrogenation catalysts developed by China National Petroleum Corporation Petrochemical Research Institute Co., Ltd.

[0063] In this 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, that is, the hydrogen partial pressure is 16.0 MPa, the volume space velocity calculated based on the residual oil is 0.27 hr -1, the volume ratio of hydrogen to residual 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 residual oil ≤ 0.45% as the control index. 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 residual oil meets the requirements. 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°C.

[0064] In this embodiment, the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e., the hydrodecarbonization reactor) are as follows: the hydrogen partial pressure is 16.0 MPa, the reaction temperature is 440° C., and the volume space velocity calculated based on the residual oil is 0.27 h -1 , the volume ratio of hydrogen to residual oil is 1000.

[0065] This embodiment also provides a fixed bed residue oil hydrogenation system, which is used to implement the above-mentioned fixed bed residue oil hydrogenation method, such as Figure 1 As shown, it includes:

[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 first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3 are respectively provided with an inlet at the top and an outlet at the bottom, 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 fourth hydrogenation reactor 6 is provided with an inlet for heated desulfurized residual oil at the top, and a hydrogen inlet and an outlet for residual oil hydrogenation products at the bottom; a gas distributor is provided inside the fourth hydrogenation reactor 6, and the gas distributor is provided above the hydrogen inlet;

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

[0072] The outlet at the bottom of the third hydrogenation reactor 3 is connected to the inlet of the hot high-pressure separator 4 through a pipeline, the desulfurized residue oil outlet of the hot high-pressure separator 4 is connected to the inlet of the heating furnace 5 through a pipeline, the outlet of the heating furnace 5 is connected to the heated desulfurized residue oil inlet at the top of the fourth hydrogenation reactor 6 through a pipeline, the hydrogen outlet of the hot high-pressure separator 4 is connected to the hydrogen inlet at the bottom of the fourth hydrogenation reactor 6 through 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 6, the residue oil hydrogenation product outlet at the bottom of the fourth hydrogenation reactor 6 is connected to the inlet of the fractionation device 7 through a pipeline, and the light distillate oil A1, the aromatics-rich distillate oil B1 and the hydrogenated residue oil C1 flow out from the light distillate oil outlet, the aromatics-rich distillate oil outlet and the hydrogenated residue oil outlet respectively.

[0073] The initial pressure drop of the fourth hydrogenation reactor 6 was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 8500 hours. In addition, the aromatics-rich fraction B1 was carbonized according to the above method to produce needle coke, and needle coke D1 was obtained, and its properties are shown in Table 2.

[0074] Example 2

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

[0076] The initial pressure drop of the fourth hydrogenation reactor 6 was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 8100 hours. In addition, the aromatics-rich fraction B2 was carbonized according to the above method to produce needle coke, and needle coke D2 was obtained, and its properties are shown in Table 2.

[0077] Example 3

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

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

[0080] Example 4

[0081] This embodiment provides a fixed bed residue oil hydrogenation method, and the fixed bed residue oil hydrogenation system used in the method is the same as that in Example 1. The difference between this method and Example 1 is that the hydrocracking reaction conditions in the fourth hydrogenation reactor 6 (i.e., the hydrogenation carbon removal reactor) are: the hydrogen partial pressure is 10.0 MPa, the reaction temperature is 420°C, and the volume space velocity calculated based on the residue oil is 0.2 h -1 , the volume ratio of hydrogen to residue oil is 200. The catalysts and their loading amounts in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3, as well as the reaction conditions in the three hydrogenation reactors are the same as those in Example 1. Finally, light distillate oil A4, aromatics-rich distillate oil B4 and hydrogenated residue oil C4 are obtained.

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

[0083] Example 5

[0084] This embodiment provides a fixed bed residue oil hydrogenation method, and the fixed bed residue oil hydrogenation system used in the method is the same as that in 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 carbon removal reactor) are: the hydrogen partial pressure is 30.0 MPa, the reaction temperature is 480°C, and the volume space velocity calculated based on the residue oil is 10.0 h -1 , the volume ratio of hydrogen to residue oil is 1500. The catalysts and their loading amounts in the first hydrogenation reactor 1, the second hydrogenation reactor 2 and the third hydrogenation reactor 3, as well as the reaction conditions in the three hydrogenation reactors are the same as those in Example 1. Finally, light distillate oil A5, aromatics-rich distillate oil B5 and hydrogenated residue oil C5 are obtained.

[0085] The initial pressure drop of the fourth hydrogenation reactor 6 was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 5900 hours. In addition, the aromatics-rich fraction B5 was carbonized according to the above method to produce needle coke, and needle coke D5 was obtained, and its properties are shown in Table 2.

[0086] Comparative Example 1

[0087] This comparative example provides a fixed bed residue oil hydrogenation method, which is basically the same as Example 1, except that: after the mixture of desulfurized residue oil and hydrogen is separated by a hot high-pressure separator to obtain desulfurized residue oil and hydrogen, the desulfurized residue oil is heated to 440°C by a heating furnace, and then the heated desulfurized residue oil and the separated hydrogen are introduced into the fourth hydrogenation reactor from the top of the fourth hydrogenation reactor to carry out a hydrocracking reaction to obtain a residue oil hydrogenation product, and the residue oil hydrogenation product is fractionated by a fractionation device to obtain a light distillate oil a1, an aromatics-rich distillate oil b1 and a hydrogenated residue oil c1. The catalysts and the loading amounts thereof loaded in the first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor, as well as the reaction conditions in the four hydrogenation reactors are the same as those in Example 1.

[0088] The initial pressure drop of the fourth hydrogenation reactor was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 2500 hours. In addition, the aromatics-rich fraction b1 was carbonized according to the above method to produce needle coke, and needle coke d1 was obtained, and its properties are shown in Table 2.

[0089] Comparative Example 2

[0090] This comparative example provides a fixed bed residue oil hydrogenation method, which is basically the same as Example 1, except that the desulfurized residue oil is heated to 410°C by a heating furnace, and the hydrocracking reaction conditions in the fourth hydrogenation reactor (i.e., the hydrogenation decarbonization reactor) are: the hydrogen partial pressure is 16.0 MPa, the reaction temperature is 410°C, and the volume space velocity calculated based on the residue oil is 0.27 h -1 , the volume ratio of hydrogen to residue oil is 1000, and finally a light distillate oil a2, an aromatics-rich distillate oil b2 and a hydrogenated residue oil c2 are obtained. The catalysts loaded in the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor and the reaction conditions in the three hydrogenation reactors are the same as those in Example 1.

[0091] The initial pressure drop of the fourth hydrogenation reactor was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 10500 hours. In addition, the aromatics-rich fraction b2 was carbonized according to the above method to produce needle coke, and needle coke d2 was obtained, and its properties are shown in Table 2.

[0092] Comparative Example 3

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

[0094] The initial pressure drop of the fourth hydrogenation reactor was 0.15 MPa, and the operation was stopped when the pressure drop rose to 0.50 MPa, and the overall operation time was recorded as 3500 hours. In addition, the aromatics-rich fraction b3 was carbonized according to the above method to produce needle coke, and needle coke d3 was obtained, and its properties are shown in Table 2.

[0095] Table 2 Product properties of hydrotreated residue oil and needle coke

[0096]

[0097]

[0098] As can be seen from the results of Example 1, the fixed-bed residue oil hydrogenation method and system provided by the embodiment of the present invention effectively improves the yield of 3-4-ring aromatic hydrocarbon-rich fraction oil in the residue oil hydrogenation product, greatly improves the yield of light distillate oil, increases the depth of residue oil hydrocracking and reduces the carbon residue value of hydrogenated residue oil, and makes the fixed-bed residue oil hydrocracking process run stably. As can be seen from the results of Example 2 and Example 3, operating at the upper and lower limits of the optimal operating conditions given by the present invention has no effect on the product properties, and the operating time does not change much. As can be seen from Examples 4 and 5, operating at the upper and lower limits of the range given by the present invention has no effect on the product properties, but the operating time is shortened. As can be seen from the results of Example 1 and Comparative Example 1, feeding both desulfurized residue oil and hydrogen from the top of the fourth hydrogenation reactor will greatly shorten the operating cycle of the residue oil hydrogenation system. It can be seen from the results of Example 1, Comparative Example 2 and Comparative Example 3 that a reaction temperature lower than or higher than the hydrocracking reaction temperature range in the fourth hydrogenation reactor given in the present invention will lead to a decrease in the content of 3-4-ring aromatics in the product, thereby affecting the interlayer distance, layer height and grain size of the needle coke grains, making it difficult to achieve the quality of the needle coke of Example 1.

Claims

1. A fixed bed residue oil hydrogenation method, comprising the following steps: (1) allowing the residual oil feedstock and hydrogen to pass through a first hydrogenation reactor, a second hydrogenation reactor, and a third hydrogenation reactor connected in series in a downflow manner to perform a hydrogenation reaction to obtain a mixture of desulfurized residual oil and hydrogen; (2) separating the mixture of desulfurized residual oil and hydrogen obtained in step (1) to obtain desulfurized residual oil and hydrogen; (3) The desulfurized residue obtained in step (2) is heated to 420-480° C., and then the heated desulfurized residue is introduced into the fourth hydrogenation reactor from the top of the fourth hydrogenation reactor, and the hydrogen obtained in step (2) is introduced into the fourth hydrogenation reactor from the bottom of the fourth hydrogenation reactor to perform a hydrocracking reaction with the heated desulfurized residue to obtain a residue hydrogenation product.

2. The fixed bed residue hydrogenation method according to claim 1, wherein: The first hydrogenation reactor, the second hydrogenation reactor, the third hydrogenation reactor and the fourth hydrogenation reactor respectively include catalyst loading areas, and the four catalyst loading areas constitute a total reaction area; in the total reaction area, four or more hydrogenation catalysts including a hydrogenation protection catalyst, a hydrodemetallization catalyst, a hydrodesulfurization catalyst and a hydrodecarbonization catalyst are sequentially loaded along the flow direction of the residual oil; Preferably, the catalyst loading zone of the fourth hydrogenation reactor is only loaded with the hydrogenation carbon removal catalyst.

3. The fixed bed residue hydrogenation method according to claim 1, wherein: In step (1), the conditions of the hydrogenation reaction in the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor respectively include: a hydrogen partial pressure of 10 to 30 MPa, a reaction temperature of 320 to 420°C, a volume space velocity calculated based on the residual oil of 0.1 to 6.5 h -1 , the volume ratio of hydrogen to residual oil is 500-2000; Preferably, the conditions of the hydrogenation reaction in the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor include: a hydrogen partial pressure of 15-20 MPa, a reaction temperature of 350-390°C, a volume space velocity calculated based on the residual oil of 0.1-1.0 h -1 , the volume ratio of hydrogen to residual oil is 500-1000.

4. The fixed bed residue oil hydrogenation method according to claim 1, wherein: In step (2), separation of the mixture of desulfurized residual oil and hydrogen obtained in step (1) is achieved by a hot high-pressure separator.

5. The fixed bed residue oil hydrogenation method according to claim 1, wherein: In step (3), heating the desulfurized residual oil obtained in step (2) to 420-480° C. is achieved by using a heating furnace; Preferably, in step (3), the desulfurized residual oil obtained in step (2) is heated to 430-450°C.

6. The fixed bed residue hydrogenation 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, evenly distributed by a gas distributor provided in the fourth hydrogenation reactor, and then subjected to a hydrocracking reaction with the heated desulfurized residue oil.

7. The fixed bed residue oil hydrogenation method according to claim 1, wherein: In step (3), the conditions of the hydrocracking reaction in the fourth hydrogenation reactor include: a hydrogen partial pressure of 10 to 30 MPa, a reaction temperature of 420 to 480°C, a volume space velocity calculated based on the residual oil of 0.2 to 10.0 h -1 , the volume ratio of hydrogen to residual oil is 200 to 1500; Preferably, the conditions of the hydrocracking reaction in the fourth hydrogenation reactor include: a hydrogen partial pressure of 15 to 20 MPa, a reaction temperature of 430 to 450°C, a volume space velocity calculated based on the residual oil of 0.2 to 2.0 h -1 , the volume ratio of hydrogen to residual oil is 500-1000.

8. The fixed bed residue oil hydrogenation method according to claim 1, wherein: The fixed bed residue oil hydrogenation method further comprises step (4): fractionating the residue oil hydrogenation product obtained in step (3) through a fractionation device to obtain light distillate oil, distillate oil rich in 3-4 ring aromatics and hydrogenated residue oil.

9. A fixed-bed residue oil hydrogenation system, the system being used to implement the fixed-bed residue oil hydrogenation method according to any one of claims 1 to 8, the system comprising: 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; The first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor are respectively provided with an inlet at the top and an outlet at the bottom, and the first hydrogenation reactor, the second hydrogenation reactor and the third hydrogenation reactor are connected in series; The hot high-pressure separator is provided with an inlet, a desulfurized residual oil outlet and a hydrogen outlet; The heating furnace is provided with an inlet and an outlet; The fourth hydrogenation reactor is provided with a heated desulfurized residual oil inlet at the top, and a hydrogen inlet and a residual oil hydrogenation product outlet at the bottom; The outlet at the bottom of the third hydrogenation reactor is connected to the inlet of the hot high-pressure separator through a pipeline, the desulfurized residue oil outlet of the hot high-pressure separator is connected to the inlet of the heating furnace through a pipeline, the outlet of the heating furnace is connected to the inlet of the heated desulfurized residue oil at the top of the fourth hydrogenation reactor through 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 through a pipeline, and 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.

10. The fixed bed residue oil hydrogenation system according to claim 9, wherein: A gas distributor is disposed inside the fourth hydrogenation reactor, and the gas distributor is disposed above the hydrogen inlet.

11. The fixed bed residue oil hydrogenation system according to claim 9, wherein: The fixed-bed residue oil hydrogenation system further comprises: a fractionation device, which is provided with an inlet, a light distillate oil outlet, an aromatics-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 through a pipeline.

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