Residue hydrotreating system and method

Abstract

This invention discloses a residue hydrotreating system and method. The system includes a first series of devices and a second series of devices arranged in parallel. The first series of devices includes a first hydrotreating protection reaction zone, a first product gas-liquid separation zone, a first hydrotreating reaction zone, and a first gas-liquid separation zone. The second series of devices includes a second hydrotreating protection reaction zone, a second hydrotreating reaction zone, and a second gas-liquid separation zone. The liquid phase outlet of the first product gas-liquid separation zone is connected to the inlet of the second hydrotreating reaction zone, and the outlet of the second hydrotreating protection reaction zone is connected to the inlet of the first hydrotreating reaction zone. The liquid phase outlet of the second gas-liquid separation zone is connected to the inlet of a second atmospheric distillation tower. The bottom outlet of the second atmospheric distillation tower is connected to the inlet of a vacuum distillation tower. The residue removal outlet of the vacuum distillation tower is connected to the inlet of the second hydrotreating protection reaction zone. The method of this invention enables the combined operation of two sets of residue hydrotreating devices, simultaneously producing low-sulfur marine fuel and catalytic cracking feedstock, maximizing the utilization rate of the devices and catalysts.

Description

Technical Field

[0001] This invention belongs to the field of oil refining and chemical engineering, and in particular relates to a system and method for treating residual oil hydrotreating. Background Technology

[0002] Currently, the main technologies for residue hydrotreating include fixed-bed, fluidized-bed, slurry-bed, and moving-bed hydrotreating. Compared to other residue hydrotreating technologies, fixed-bed residue hydrotreating technology has the advantages of mature technology, easy operation, and low investment, enabling efficient conversion and utilization of residue. Fixed-bed residue hydrotreating technology primarily removes impurities such as sulfur, nitrogen, and metals from the residue feedstock through hydrotreating, reducing the residual carbon value and providing feedstock for downstream catalytic cracking units. However, with the increasing market demand for low-sulfur marine fuel oil in recent years, fixed-bed residue hydrotreating units often simultaneously undertake the task of producing both catalytic cracking feedstock and low-sulfur marine fuel oil. According to the International Maritime Organization (IMO), starting from January 1, 2020, the sulfur content of marine fuel oil for ships navigating in all global sea areas must be less than 0.5%, and for ships navigating in International Emission Control Areas (ECAs), the sulfur content of marine fuel oil must not exceed 0.1%. Stricter sulfur content standards and stricter emission controls have had a significant impact on the fuel oil market, which is dominated by high-sulfur fuel oil, presenting both significant challenges and opportunities for suppliers. Meeting the demand for low-sulfur marine fuel oil products that are low-cost, efficient, flexible, and produced on a large scale has become a pressing issue for refineries and suppliers.

[0003] Because the feedstock properties of catalytic cracking units have relatively stringent requirements, the production of low-sulfur marine fuel oil using existing fixed-bed residue oil units and catalyst grading systems suffers from problems such as insufficient selectivity in hydrodesulfurization and excessive properties of hydrotreated residue oil products. Even with adjustments to operating conditions and optimization of catalyst grading, existing units still face issues such as insufficient selective desulfurization and the inability to simultaneously produce low-sulfur marine fuel oil and catalytic cracking feedstock.

[0004] CN113122332A discloses a method for producing low-sulfur marine fuel oil. The method includes: low-quality heavy oil feedstock first enters a pretreatment reactor, reacting with a treatment agent packed within the reactor; after hydrotreating and fractionation, 180# and 380# low-sulfur marine fuel oil can be produced. This method has low production costs and readily available feedstock, but the reaction effluent suffers from high product loss rates after atmospheric and vacuum distillation, and the processing capacity of the equipment is insufficient to meet the huge demand in the marine fuel oil market.

[0005] CN116478724A discloses a heavy oil processing method and system. The method includes two sets of residue hydrotreating units. First, heavy oil feedstock is mixed with hydrogen and enters a first reaction zone for reaction. The reaction product enters a first separation zone. The liquid phase products obtained from the first hot low-pressure separator and the first cold low-pressure separator are both fed into a flash distillation tower for fractionation to obtain light and heavy components. Second, heavy oil feedstock is mixed with hydrogen and enters a second reaction zone for reaction. The reaction product enters a second separation zone. The liquid phase products obtained from the second hot low-pressure separator, the second cold low-pressure separator, and the light components obtained from the flash distillation tower are all fed into an atmospheric distillation tower for fractionation to obtain hydrotreated naphtha, hydrotreated diesel, and hydrotreated heavy oil. This method can maximize the low-cost production of low-sulfur marine fuel, but the two sets of units use the same feedstock and cannot work synergistically, resulting in insufficient operational flexibility.

[0006] CN114644939A discloses a method for producing low-sulfur marine fuel oil through hydrotreating. The method includes mixing the effluent from an upflow hydrotreating reactor with hydrogen and then feeding it into a fixed-bed hydrotreating unit for a first hydrorefining reaction to obtain hydrotreated product oil. This product oil is then subjected to atmospheric and vacuum fractionation to obtain hydrotreated vacuum residue and hydrotreated vacuum wax oil. A portion of the hydrotreated vacuum residue is mixed with relatively inferior residue feedstock and hydrogen and fed into an upflow hydrotreating reactor for a second hydrorefining reaction to obtain the effluent from the upflow hydrotreating reactor. A portion of the hydrotreated vacuum residue is then mixed with the hydrotreated vacuum wax oil to obtain the marine fuel oil product. This method can process inferior residue feedstock and meet the requirements for low-sulfur marine fuel. However, this reaction process requires a portion of the product to be recycled back to the reactor as the main reactant to continue, which is not conducive to maximizing the economic benefits of the unit. Furthermore, the product is only recycled back to the unit in the same phase, failing to maximize the combined effect of the two phases. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a residue hydrotreating system and method. The method of this invention enables the combined operation of two residue hydrotreating units, not only processing the original residue feedstock while also producing low-sulfur marine fuel and catalytic cracking feedstock, but also improving the operability of the unit, maximizing the utilization rate of the unit and catalyst, and significantly enhancing economic benefits.

[0008] The inventors discovered that for low-sulfur paraffinic residue feedstock, the lower sulfur content results in relatively lower exothermic reactions in the hydrotreating reaction zone. While increasing the temperature to compensate for the heat required for hydrodesulfurization and denitrification, the limited operating space of the catalyst bed leads to faster coking and charring of the catalyst during harsher reaction conditions and rapid temperature increases, affecting catalyst lifespan. Therefore, this feedstock becomes more difficult to process in the later stages of operation. Furthermore, during the processing of low-sulfur paraffinic residue feedstock, asphaltenes are more likely to precipitate and deposit in the hydrotreating reaction zone bed, leading to catalyst coking and deactivation, while the catalyst in the hydrotreating protection reaction zone remains active. For high-sulfur intermediate residue feedstock, its high sulfur content, high aromatic content, and short side chains provide sufficient heat for the hydrotreating reaction bed, achieving a high impurity removal rate and meeting the requirements for catalytic cracking feedstock. However, when adjusting the production plan to increase the production of low-sulfur marine fuel blending components, the high sulfur content makes it difficult to meet the requirements at lower reaction severity levels, necessitating measures such as pressurization and space velocity reduction. This increases operating costs and impacts unit operation. Further research by the inventors revealed that by combining two sets of residue hydrotreating units in a specific manner, not only can the original residue feedstock be processed while simultaneously producing low-sulfur marine fuel and catalytic cracking feedstock, but the operability of the unit can also be improved, maximizing the utilization rate of the unit and catalyst, resulting in significant economic benefits.

[0009] The first aspect of this invention provides a residue hydrotreating system, comprising two series of residue hydrotreating units arranged in parallel, namely a first series unit and a second series unit. The first series unit includes a first hydrotreating protection reaction zone, a first product gas-liquid separation zone, a first hydrotreating reaction zone, and a first gas-liquid separation zone. The second series unit includes a second hydrotreating protection reaction zone, a second hydrotreating reaction zone, and a second gas-liquid separation zone. The liquid phase outlet of the first product gas-liquid separation zone is connected to the inlet of the second hydrotreating reaction zone, and the outlet of the second hydrotreating protection reaction zone is connected to the inlet of the first hydrotreating reaction zone. The liquid phase outlet of the first gas-liquid separation zone is connected to the inlet of a first atmospheric distillation tower, and the liquid phase outlet of the second gas-liquid separation zone is connected to the inlet of a second atmospheric distillation tower. The bottom outlet of the second atmospheric distillation tower is connected to the inlet of a vacuum distillation tower. The residue removal outlet of the vacuum distillation tower is connected to the inlet of the second hydrotreating protection reaction zone.

[0010] Furthermore, preferably, the vacuum wax oil outlet of the vacuum fractionation tower is connected to the inlet of the first hydrogenation reaction zone.

[0011] Furthermore, the first hydrogenation protection reaction zone is used to protect the main catalyst in the first hydrogenation reaction zone, mainly to remove mechanical impurities and metallic impurities such as iron, calcium, nickel, and vanadium. Generally, the first hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst.

[0012] Furthermore, the first product gas-liquid separation zone is used for gas-liquid separation of the effluent obtained from the first hydrogenation protection reaction zone, removing C1-C4 light components and gases such as H2S from the reaction products.

[0013] Furthermore, the first hydrogenation reaction zone is used as the main reaction zone for residue oil treatment, removing impurities such as sulfur and nitrogen from the residue oil feedstock. Generally, the first hydrogenation reaction zone is filled with a hydrodesulfurization catalyst and a hydrodenitrification catalyst in sequence according to the flow direction. Preferably, a hydrodemetallization catalyst is filled upstream of the hydrodesulfurization catalyst.

[0014] Furthermore, the first gas-liquid separation zone is used for gas-liquid separation of the effluent from the first hydrogenation reaction zone to remove C1-C4 light components and gases such as H2S from the reaction products.

[0015] Furthermore, the first atmospheric distillation column is used for the fractionation of the liquid phase obtained from the first gas-liquid separator to obtain hydrotreated naphtha, hydrotreated diesel oil, and hydrotreated heavy oil.

[0016] Furthermore, the second hydrogenation protection reaction zone is used to protect the main catalyst in the second hydrogenation reaction zone, mainly to remove mechanical impurities and metallic impurities such as iron, calcium, nickel, and vanadium. Generally, the second hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst.

[0017] Furthermore, the second hydrogenation reaction zone is used as the main reaction zone for residue oil treatment, removing impurities such as sulfur and nitrogen from the residue oil feedstock. Generally, the second hydrogenation reaction zone is filled with hydrodesulfurization catalyst and hydrodenitrification catalyst in sequence according to the flow direction.

[0018] Furthermore, the second gas-liquid separation zone is used for gas-liquid separation of the effluent from the second hydrogenation reaction zone to remove C1-C4 light components and gases such as H2S from the reaction products.

[0019] Furthermore, the second atmospheric distillation tower is used for the fractionation of the liquid phase obtained from the second gas-liquid separator to obtain hydrotreated naphtha, hydrotreated diesel oil, and hydrotreated heavy oil; the hydrotreated heavy oil obtained from the fractionation enters the vacuum distillation tower to obtain vacuum wax oil and vacuum residue.

[0020] Furthermore, both the first and second series units are fixed-bed residue hydrotreating units. The reactors in the first series units are all top-down co-current fixed-bed reactors. In the second series units, the reactor in the second hydrotreating protection reaction zone can be either a co-current fixed-bed reactor or an upflow fixed-bed reactor; the reactors in the second hydrotreating reaction zone are all top-down co-current fixed-bed reactors.

[0021] Furthermore, the first hydrogenation protection reaction zone employs at least one fixed-bed hydrogenation reactor, preferably 1 to 3 reactors; the first product gas-liquid separation zone includes at least one high-pressure separator, preferably 1 to 2 separators. Generally, the first product gas-liquid separation zone and the first gas-liquid separation zone may include a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, and a cold low-pressure separator for gas-liquid separation.

[0022] Furthermore, the second hydrogenation protection reaction zone employs at least one fixed-bed hydrogenation reactor, preferably one to three; the second hydrogenation reaction zone employs at least one fixed-bed hydrogenation reactor, preferably one to three, more preferably two to three. The second gas-liquid separation zone includes at least one high-pressure separator, preferably one to two. Generally, the second gas-liquid separation zone may include a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, and a cold low-pressure separator for gas-liquid separation.

[0023] The second aspect of the present invention provides a method for treating residual oil hydrotreating, wherein the residual oil hydrotreating system provided in the first aspect is used, and the method includes a first operation process I and a first operation process II operating simultaneously, as well as a second operation process and a third operation process.

[0024] The first operation process I includes: the first series of units using low-sulfur paraffin-based residue oil as raw material to produce low-sulfur marine fuel oil products;

[0025] The first operation process II includes: the second series of units uses high-sulfur intermediate base residue oil as raw material to produce catalytic cracking feed or low-sulfur marine fuel oil blending components;

[0026] When the pressure drop of the catalyst bed in the first hydrogenation reaction zone of the first series unit reaches 50% to 90% of the maximum design pressure drop, preferably 60% to 80%, the operation is switched from the first operation to the second operation. That is, the product stream from the first hydrogenation protection reaction zone of the first series unit is introduced into the second hydrogenation reaction zone of the second series unit and mixed with the product stream from the second hydrogenation protection reaction zone of the second series unit as feed for the second hydrogenation reaction zone, which is used to produce low-sulfur marine fuel blending components. Preferably, at the same time, a portion of the vacuum wax oil obtained from the vacuum fractionation tower of the second series unit is recycled back to the first hydrogenation reaction zone of the first series unit as feed for the first hydrogenation reaction zone.

[0027] When the catalyst bed pressure drop in the second hydrogenation reaction zone of the second series unit reaches 65% to 90% of the maximum design pressure drop, preferably 70% to 85%, the operation transitions from the second to the third process. Specifically, the first hydrogenation protection reaction stream from the first series unit is redirected back to the first hydrogenation reaction zone of the first series unit. Simultaneously, a portion of the product stream from the second hydrogenation protection reaction zone of the second series unit (preferably, the introduction flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 10% to 20% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume) is introduced into the first hydrogenation reaction zone of the first series unit. The first series unit is used to produce low-sulfur marine fuel blending components, while the second series unit is used to produce low-sulfur marine fuel blending components or catalytic cracking feedstock, until both units are shut down.

[0028] Further, the low-sulfur paraffinic residue feedstock can be selected from at least one of atmospheric residue and vacuum residue, and may also contain one or more of catalytic diesel, deasphalted oil, coking wax oil, or heavy distillate oil. In the low-sulfur paraffinic residue feedstock, the mass content of saturated components is above 18%, which can be 18%–24%, and the mass content of aromatic components is below 30%, which can be 25%–30%. By mass fraction, the sulfur content in the low-sulfur paraffinic residue feedstock is not higher than 4.0%, which can be 1.0%–4.0%, and further 0.8%–2.0%; the total content of heavy metals nickel and vanadium is not higher than 200 μg / g, and further 40–100 μg / g; the nitrogen content is not higher than 0.80%, which can be 0.20%–0.65%; and the KORP residue is not higher than 17%, which can be 5.0%–15.0%.

[0029] Furthermore, the high-sulfur intermediate residue feedstock can be selected from at least one of atmospheric residue and vacuum residue, and may also contain one or more of catalytic diesel, deasphalted oil, coking wax oil, or heavy distillate oil. In the high-sulfur intermediate residue feedstock, the mass content of saturated components is below 15%, which can be 13%–15%, and the mass content of aromatic components is above 45%, which can be 45%–48%. By mass fraction, the sulfur content in the high-sulfur intermediate residue feedstock is not higher than 5.0%, which can be 1.5%–4.5%, further 2.5%–4.0%; the total content of heavy metals nickel and vanadium is not higher than 200 μg / g, which can be 50–120 μg / g; the nitrogen content is not higher than 0.80%, which can be 0.20%–0.50%; and the KORP residue is not higher than 17%, which can be 7.0%–15.0%.

[0030] Furthermore, the first series of units are conventional residue hydrotreating units that directly produce low-sulfur marine fuel oil products from low-sulfur paraffin-based residue oil.

[0031] Furthermore, the first series of devices includes a first hydrogenation protection reaction zone, a first product gas-liquid separation zone, a first hydrogenation reaction zone, and a first gas-liquid separation zone. The first hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst. The first hydrogenation reaction zone is filled with a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst in sequence according to the flow direction. Preferably, the hydrogenation demetallization catalyst is filled upstream of the hydrogenation desulfurization catalyst.

[0032] Furthermore, the first operation process I of the first series of units includes: low-sulfur paraffin-based residue oil feedstock and hydrogen are mixed and fed into the first hydrogenation protection reaction zone for reaction. The product obtained in the first hydrogenation protection zone is not subjected to gas-liquid separation and is directly fed into the first hydrogenation reaction zone for reaction. The product stream obtained in the first hydrogenation reaction zone is fed into the first gas-liquid separation zone for gas-liquid separation. The separated liquid phase is fed into the first atmospheric distillation tower for fractionation. The atmospheric hydrogenated heavy oil obtained is the marine fuel oil product.

[0033] Furthermore, the second series of units are conventional residue hydrotreating units that use high-sulfur intermediate residue oil as feedstock to produce catalytic cracking feedstock or marine fuel oil blending components.

[0034] Furthermore, the second series of units includes a second hydrogenation protection reaction zone, a second hydrogenation reaction zone, and a second gas-liquid separation zone. The second hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst, while the second hydrogenation reaction zone is filled with a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst in sequence according to the flow direction.

[0035] Furthermore, the first operation process II of the second series unit includes: high-sulfur intermediate base residue feedstock, recycled reduced-pressure residue, and hydrogen are mixed and fed into the second hydrotreating protected reaction zone for reaction; the product stream from the second hydrotreating protected zone is fed into the second hydrotreating reaction zone for reaction; the product stream from the second hydrotreating reaction zone is fed into the second gas-liquid separation zone for gas-liquid separation; the separated liquid phase is fed into the second atmospheric distillation tower for fractionation; and the obtained atmospheric residue is fed into the vacuum distillation tower for vacuum fractionation to obtain vacuum wax oil and reduced-pressure residue. The reduced-pressure residue is used as a catalytic cracking feedstock or a blending component for low-sulfur marine fuel oil, preferably as a catalytic cracking feedstock.

[0036] Furthermore, the second series of units is used to produce catalytic cracking feedstock or low-sulfur marine fuel oil blending components, preferably catalytic cracking feedstock.

[0037] Furthermore, the reduced residue obtained from the vacuum distillation tower of the second series unit is recycled to the second hydrotreating protection reaction zone to improve the properties of the high-sulfur feedstock. Furthermore, the recycled amount of reduced residue accounts for 10% to 15% of the high-sulfur intermediate base residue feedstock, measured by volumetric flow rate.

[0038] Furthermore, when the pressure drop of the catalyst bed in the first hydrogenation reaction zone of the first series unit reaches 50% to 90%, preferably 60% to 80%, of the maximum design pressure drop, the operation transitions from the first to the second process. Specifically, the product stream from the first hydrogenation protection reaction zone of the first series unit enters the first product gas-liquid separation zone, and the resulting liquid stream is introduced into the second hydrogenation reaction zone of the second series unit, mixing with the product stream from the second hydrogenation protection reaction zone. Compared to the second series unit operating alone, the introduction of reactants with lower sulfur and metal content optimizes the feed to the second hydrogenation reaction zone, making it suitable for producing low-sulfur marine fuel blending components. Simultaneously, a portion of the vacuum wax oil obtained from the vacuum fractionation tower of the second series unit is recycled back to the first hydrogenation reaction zone of the first series unit as feed to alleviate coking of the catalyst bed in the first hydrogenation reaction zone.

[0039] Furthermore, when the catalyst bed pressure drop in the second hydrotreating zone of the second series unit reaches 65%–90% of the maximum design pressure drop, preferably 70%–85%, the operation transitions from the second to the third process. In this third process, the first hydrotreating protection reaction stream from the first series unit is directly returned to the first hydrotreating zone of the first series unit without gas-liquid separation. Simultaneously, a portion of the product stream from the second hydrotreating protection reaction zone of the second series unit (preferably, the introduction flow rate of the product stream from the second hydrotreating protection reaction zone accounts for 10%–20% of the product stream flow rate from the first hydrotreating protection reaction zone, by volume) is introduced into the first hydrotreating zone of the first series unit. This addresses the problem of insufficient heat of reaction in the hydrotreating zone during the later stages of operation of low-sulfur paraffinic residue feedstock, ensuring impurity removal rates. This operation allows continued use of the catalyst in the first hydrotreating zone of the first series unit. Although the activity is reduced compared to fresh catalyst, it can still be used to produce low-sulfur marine fuel blending components, thus maximizing the utilization of the catalyst in the first hydrotreating zone of the first series unit. The second series unit is used to produce low-sulfur marine fuel blending components or catalytic cracking feedstock until both units are shut down.

[0040] Furthermore, in the first series of units, catalysts are loaded and production conditions for the first operation process I are controlled to produce marine fuel oil products using low-sulfur paraffin-based residue oil as raw material.

[0041] Furthermore, in the first operation process I, the operating conditions of the first hydrogenation protected reaction zone are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 410°C, and liquid hourly space velocity of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 200–2000; preferably, the hydrogen partial pressure is 12 MPa–18 MPa, the reaction temperature is 315°C–400°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1500.

[0042] Furthermore, in the first operation process I, the operating conditions of the first hydrogenation reaction zone are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 420°C, and liquid hourly space velocity of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 250–2000; preferably, the hydrogen partial pressure is 14 MPa–18 MPa, the reaction temperature is 320°C–410°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1800.

[0043] Furthermore, in the second series of units, marine fuel oil blending components or catalytic cracking feedstock are produced using high-sulfur intermediate base residue as raw material, and catalysts are loaded and production conditions of the first operation process II are controlled.

[0044] Furthermore, in the first operation process II, the operating conditions of the second hydrogenation protected reaction zone are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 410°C, and liquid hourly space velocity of fresh feedstock of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 200–2000; preferably, the hydrogen partial pressure is 13 MPa–19 MPa, the reaction temperature is 320°C–400°C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 420–1600.

[0045] Furthermore, the operating conditions of the second hydrogenation reaction zone in the first operation process II are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 420°C, and liquid hourly space velocity of fresh feedstock of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 280–2000; preferably, the hydrogen partial pressure is 14 MPa–19 MPa, the reaction temperature is 330°C–410°C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 450–1800.

[0046] Furthermore, in the first series of devices, the first hydroprotection reaction zone is filled with a hydroprotection catalyst and a hydrodemetallization catalyst, while the first hydrotreating reaction zone is filled with an optional hydrodemetallization catalyst, a hydrodesulfurization catalyst, and a hydrodenitrogenation catalyst. Specifically, based on the total catalyst loading volume, the hydroprotection catalyst accounts for 6%–30% of the total loading volume, preferably 8%–25%; the hydrodemetallization catalyst accounts for 10%–50% of the total loading volume, preferably 20%–40%; the hydrodesulfurization catalyst accounts for 20%–80% of the total loading volume, preferably 25%–55%; and the hydrodenitrogenation catalyst accounts for 20%–80% of the total loading volume, preferably 20%–50%. The catalyst loading sequence can adopt a conventional gradation sequence, generally involving the feedstock oil contacting the hydroprotection catalyst, hydrodemetallization catalyst, hydrodesulfurization catalyst, and hydrodenitrogenation catalyst in sequence. Hydrogenation protection catalysts, hydrodemetallization catalysts, hydrodesulfurization catalysts, and hydrodenitrogenation catalysts can be catalysts with corresponding functions commonly used in this field, such as the FZC series residue hydrotreating catalysts produced by the Catalyst Branch of China Petroleum & Chemical Corporation.

[0047] Furthermore, in the second series of units, the second hydroprotection reaction zone is filled with a hydroprotection catalyst and a hydrodemetallization catalyst, and the second hydrotreating reaction zone is filled with a hydrodesulfurization catalyst and a hydrodenitrification catalyst. Specifically, based on the total catalyst loading volume, the hydroprotection catalyst accounts for 6%–30% of the total loading volume, preferably 8%–25%; the hydrodemetallization catalyst accounts for 10%–55% of the total loading volume, preferably 20%–45%; the hydrodesulfurization catalyst accounts for 25%–80% of the total loading volume, preferably 25%–60%; and the hydrodenitrification catalyst accounts for 20%–75% of the total loading volume, preferably 20%–45%. The catalyst loading sequence can adopt a conventional gradation sequence, generally involving the feedstock oil contacting the hydroprotection catalyst, hydrodemetallization catalyst, hydrodesulfurization catalyst, and hydrodenitrification catalyst in sequence. Hydrogenation protection catalysts, hydrodemetallization catalysts, hydrodesulfurization catalysts, and hydrodenitrogenation catalysts can be catalysts with corresponding functions commonly used in this field, such as the FZC series residue hydrotreating catalysts produced by the Catalyst Branch of China Petroleum & Chemical Corporation.

[0048] Furthermore, in the first series of devices, the catalysts of the fixed-bed reactors in the first hydrogenation protection reaction zone and the first hydrogenation reaction zone are graded and loaded according to conventional gradation principles, that is, the catalyst particle size gradually decreases, the porosity gradually decreases, and the content of hydrogenation active metals on the catalyst gradually increases in the direction of material flow.

[0049] Furthermore, taking the first series of devices using four reactors as an example, the first reactor in the first hydrogenation protection reaction zone is at least filled with a hydrogenation protection agent, and may also be filled with a hydrogenation protection agent and a hydrogenation demetallization catalyst. The second reactor is at least filled with a hydrogenation demetallization catalyst, and may also be filled with a hydrogenation protection agent upstream of the hydrogenation demetallization catalyst. The third reactor in the first hydrogenation reaction zone is at least filled with a hydrogenation desulfurization catalyst, and may also be filled with a hydrogenation demetallization catalyst upstream of the hydrogenation desulfurization catalyst. The fourth reactor is at least filled with a hydrogenation denitrogenation catalyst, and may also be filled with a hydrogenation desulfurization catalyst upstream of the hydrogenation denitrogenation catalyst. Preferably, the volume ratio of hydrogenation protective agent to hydrogenation demetallization catalyst in the first reactor is (0.5-5):1, more preferably (0.8-3):1; the volume ratio of hydrogenation demetallization catalyst to hydrogenation protective agent in the second reactor is (0.5-20):1, more preferably (1-10):1; the volume ratio of hydrogenation desulfurization catalyst to hydrogenation demetallization catalyst in the third reactor is (0.5-20):1, more preferably (5-10):1; and the volume ratio of hydrogenation denitrogenation catalyst to hydrogenation desulfurization catalyst in the fourth reactor is (0.5-20):1, more preferably (5-10):1.

[0050] Furthermore, in the second series of devices, the catalysts in the fixed-bed reactors of the second hydrogenation protection reaction zone and the second hydrogenation reaction zone are graded and loaded according to conventional gradation principles, that is, the catalyst particle size gradually decreases, the porosity gradually decreases, and the content of hydrogenation active metals on the catalyst gradually increases in the direction of material flow.

[0051] Furthermore, taking the second series of units using four reactors as an example, the first reactor in the second hydrogenation protection reaction zone is at least filled with a hydrogenation protection agent, and a hydrogenation demetallization catalyst may also be filled downstream of the hydrogenation protection agent. The second reactor is at least filled with a hydrogenation demetallization catalyst, and a hydrogenation protection agent may also be filled upstream of the hydrogenation demetallization catalyst. The third reactor in the second hydrogenation reaction zone is at least filled with a hydrogenation desulfurization catalyst, and the fourth reactor is filled upstream with a hydrogenation desulfurization catalyst and downstream with at least one or more of the hydrogenation desulfurization catalyst or hydrogenation denitrification catalyst. Preferably, the volume ratio of hydrogenation protective agent to hydrogenation demetallization catalyst in the first reactor is (0.5-5):1, more preferably (1-3):1; the volume ratio of hydrogenation demetallization catalyst to hydrogenation protective agent in the second reactor is (0.5-20):1, more preferably (3-10):1; a hydrogenation desulfurization catalyst is loaded in the third reactor; and the volume ratio of hydrogenation desulfurization catalyst loaded in the fourth reactor accounts for 1%-40% of the total catalyst loading volume in the fourth reactor, preferably 5%-30%, and the volume of hydrogenation denitrification catalyst accounts for 60%-99% of the total catalyst loading volume in the fourth reactor, preferably 70%-95%.

[0052] Furthermore, in the second operation, the operating conditions of the second hydrogenation reaction zone of the second series unit are adjusted as follows: compared with the operating conditions of the second hydrogenation reaction zone in the first operation II, the hydrogen partial pressure is increased (at least by 0.1 MPa, preferably by 0.2 to 2.0 MPa), the reaction temperature is decreased (at least by 4°C, preferably by 4°C to 7°C), and the volume hourly space velocity is increased (at least by 0.01 h⁻¹). -1 The preferred improvement is 0.01 to 0.5 h. -1 Increase the hydrogen-to-oil volume ratio (at least 5, preferably 5-200), further increase the hydrogen partial pressure to 15-25 MPa, and increase the liquid hourly space velocity of the fresh feedstock to 0.24 h⁻¹. -1 ~2.2h -1 The total hydrogen-to-oil volume ratio is increased to 300–2200; preferably, compared with the operating conditions of the second hydrogenation reaction zone in the first operation process II, the hydrogen partial pressure is increased to 16 MPa–20 MPa, the reaction temperature is decreased by 5–6 °C, and the liquid hourly space velocity of the fresh feedstock is increased to 0.27 h⁻¹. -1 ~1.95h -1 This will increase the total hydrogen-to-oil volume ratio to 500–1800.

[0053] Furthermore, in the second operation, the operating conditions of the first hydrogenation reaction zone of the first series of devices are adjusted as follows: compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is reduced (by at least 1 MPa), the reaction temperature is reduced (by at least 10 °C), and the liquid hourly space velocity is increased (by at least 0.1 h⁻¹). -1 This reduces the total hydrogen-to-oil volume ratio (by at least 50%). Specifically, compared to the operating conditions in the first hydrogenation reaction zone of the first operation process I, the hydrogen partial pressure is reduced to 8 MPa–18 MPa, the reaction temperature is reduced to 300°C–370°C, and the liquid hourly space velocity is increased to 0.22 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is reduced to 100–400; preferably, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is reduced to 10 MPa–16 MPa, the reaction temperature is reduced to 310°C–365°C, and the liquid hourly space velocity is increased to 0.3 h⁻¹. -1 ~2.5h -1 The total hydrogen-to-oil volume ratio is reduced to 100-350.

[0054] Furthermore, in the third operation, the operating conditions of the first hydrogenation reaction zone of the first series of devices are as follows: compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the reaction temperature is increased (at least by 10°C, preferably by 10–40°C); specifically, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is 10 MPa–20 MPa, the reaction temperature is increased to 350°C–425°C, and the liquid hourly space velocity is 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 300–2000; preferably, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is 14 MPa–18 MPa, the reaction temperature is increased to 360°C–420°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1800.

[0055] Furthermore, in the third operation, the operating conditions of the second hydrogenation reaction zone of the second series unit are as follows: compared with the operating conditions of the second hydrogenation reaction zone in the second operation, the hydrogen partial pressure is 15 MPa to 25 MPa, the reaction temperature is increased by 8 to 40 °C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 300–2200; preferably, the hydrogen partial pressure is 16 MPa–20 MPa, the reaction temperature is increased by 10–30 °C, and the liquid hourly space velocity of the fresh feedstock is 0.16 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 500–1800.

[0056] Furthermore, when the first and second series of units were shut down, the utilization rate of the catalyst in each reactor exceeded 95%.

[0057] Compared with the prior art, the present invention has the following advantages:

[0058] 1. Through further research, the inventors discovered that by combining a low-sulfur paraffin-based residue oil hydrotreating unit (first series unit) with a high-sulfur intermediate-based residue oil hydrotreating unit (second series unit), specifically when the catalyst in the first hydrotreating reaction zone of the first series unit is about to reach its lifespan limit, the first hydrotreating reaction zone is disconnected, and the liquid phase stream obtained from the product stream of the first hydrotreating protection reaction zone is introduced into the second hydrotreating reaction zone of the second series unit via gas-liquid separation. Simultaneously, a portion of the vacuum-pressed paraffin oil from the second series unit is recycled back to the first series hydrotreating reaction zone as feed. Then, when the catalyst in the second hydrotreating reaction zone of the second series unit is about to reach its lifespan limit, the product from the first hydrotreating protection reaction zone of the first series unit is returned to the first hydrotreating reaction zone, and a portion of the product from the second hydrotreating protection reaction zone is introduced again, continuing operation until both series units are shut down. This invention not only allows for the processing of different raw materials but also enables flexible adjustment of the production plan according to the actual production needs of the unit, producing the most efficient product, maximizing the flexibility of raw material procurement and utilization, as well as the utilization rate of the unit and catalyst, resulting in significant economic benefits.

[0059] 2. The two series of residue hydrotreating units used in the method of the present invention can be operated independently or in synergy, thereby improving the operability of the unit;

[0060] 3. In the method of the present invention, the two series of devices perform synergistic operation during the middle and later stages of operation. During the middle stage of operation, the first series of devices can improve the feed properties of the second series of devices and improve product distribution. At the same time, the second series of devices can alleviate the coking degree of the first series of catalyst beds.

[0061] 4. In the method of the present invention, in the later stage of operation, the second series of devices can provide the first series with high-heat hydrogenation reaction exothermic feedstock, optimize the temperature rise space of the first series, and realize long-term efficient and stable operation of the devices.

[0062] 5. Compared with processing the same raw materials simultaneously with two sets of equipment, this method can increase the proportion of slag added to high-sulfur intermediate base raw materials. While increasing the processing capacity of inferior raw materials, it can also adjust the product types according to the production situation, improve product properties, and reduce energy consumption. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the system of the present invention;

[0064] The reference numerals in the attached figures are explained as follows:

[0065] 11-12 are the first series of first hydrogenation protection reactors; 13 is the first product gas-liquid separator; 14-15 are the first hydrogenation reactors; 16 is the first gas-liquid separator; 17 is the first atmospheric distillation tower; 111 is the first series of raw materials; 112-113 are the effluent from the first hydrogenation protection reactors; 114-115 are the effluents that do not pass through the first product gas-liquid separator; L1 is a pipeline used to transport the liquid phase effluent after separation by the first product gas-liquid separator; 116-117 are the effluent from the first hydrogenation reactors; 118 is the liquid phase effluent after separation by the first gas-liquid separator; 119 is the hydrogenated heavy oil after separation by the first atmospheric distillation tower.

[0066] 21-22 are the second series of second hydrogenation protection reactors; 23-24 are the second hydrogenation reactors; 25 is the second gas-liquid separator; 26 is the second atmospheric distillation tower; 27 is the second vacuum distillation tower; 211 is the second series of feedstocks; 212-213 are the effluent streams from the second hydrogenation protection reactor; 214-215 are the effluent streams from the second hydrogenation reactor; L2 is a pipeline used to transport a branch of the effluent stream from the second hydrogenation protection reactor to the inlet of the first hydrogenation reactor; 216 is the liquid phase stream after separation by the second gas-liquid separator; 217 is the hydrogenated heavy oil after separation by the second atmospheric distillation tower; 219 and 220 are the vacuum residue and vacuum wax oil obtained by fractionation of the hydrogenated heavy oil by the second vacuum distillation tower; 218 is the vacuum residue oil recycled back to the second hydrogenation protection reactor; 221 is the vacuum wax oil recycled to the first hydrogenation reactor; a, b, c, d, and e are valves on the control pipelines. Detailed Implementation

[0067] The method of the present invention will be described in detail below with reference to the embodiments.

[0068] The method provided by this invention employs Figure 1 The system shown includes:

[0069] First operation process I: The first series of raw materials 111 enter the first hydrogenation protection reactor 11 for reaction, and the resulting effluent 112 enters the first hydrogenation protection reactor 12 for reaction. Valves a, d, and e are closed, and valves b and c are opened. The resulting effluent 113 enters the first hydrogenation reactor 14 through pathways 114 and 115 for reaction, and the resulting effluent 116 enters the first hydrogenation reactor 15 for reaction. The resulting effluent 117 enters the first gas-liquid separator 16, and the separated liquid phase effluent 118 enters the first atmospheric distillation tower 17 to obtain hydrogenated heavy oil 119.

[0070] First Operation Process II: The second series of raw materials 211 enter the second hydrogenation protection reactor 21 for reaction, the resulting effluent 212 enters the second hydrogenation protection reactor 22 for reaction, the resulting effluent 213 enters the second hydrogenation reactor 23 for reaction, the resulting effluent 214 enters the second hydrogenation reactor 24 for reaction, the effluent 215 enters the second gas-liquid separator 25 for gas-liquid separation, the liquid phase effluent 216 enters the second atmospheric distillation tower 26 for fractionation to obtain hydrogenated heavy oil 217, the hydrogenated heavy oil 217 then enters the second vacuum distillation tower 27 for vacuum fractionation to obtain vacuum wax oil 220 and vacuum residue oil 219, of which a portion of the vacuum residue oil 218 is recycled to the inlet of the second hydrogenation protection reactor 21;

[0071] Second operation process: When the pressure drop of the catalyst bed in the first hydrogenation reaction zone of the first series unit reaches 60% to 80% of the maximum design pressure drop, the operation process switches from the first operation process to the second operation process. Valves b, c, and e are closed, and valves a and d are opened. The effluent 113 obtained from the first hydrogenation protection reaction of the first series is introduced into the first product gas-liquid separator 13. The liquid phase stream separated by the gas-liquid separator 13 and the hydrogenation reaction stream 214 of the second series are introduced into the second hydrogenation reactor 24 through pipeline L1. The subsequent operation of the second series unit is the same as the first operation process II, and will not be described again here. At the same time, part of the vacuum wax oil 221 obtained by the second vacuum fractionation tower 27 of the second series is recycled to the first hydrogenation reactor 14 and flows through the unit in the direction of the stream to alleviate the coking of the bed of the first hydrogenation reactors 14 and 15.

[0072] Third operating procedure: When the pressure drop of the catalyst bed in the second hydrogenation reaction zone of the second series unit reaches 70% to 85% of the maximum design pressure drop, the operation transitions from the second operating procedure to the third operating procedure. Valves a and d are closed, and valves b, c, and e are opened. The flow direction of the first hydrogenation protection reaction stream L1 of the first series unit is changed to 115, returning to the first hydrogenation reactor 14. The subsequent operation of the first series is the same as the first operating procedure I, and will not be repeated here. A portion of the hydrogenation protection reaction stream 213 of the second series flows into the second hydrogenation reactor 23, and the branch stream is connected to the first hydrogenation reactor 14 through the L2 pipeline. The subsequent operation of the second series unit is the same as the first operating procedure II, and will not be repeated here.

[0073] In the examples and comparative examples, the first series of units used four co-current fixed-bed hydrotreating reactors of equal volume, and the second series of units used four co-current fixed-bed hydrotreating reactors of equal volume. The catalysts used were all FZC series residue hydrotreating catalysts developed by the Dalian Petrochemical Research Institute of Sinopec and produced by the Catalyst Branch of Sinopec Corporation. The catalyst loading by volume in the reactors of both units is shown in Table 1. Specifically, two grades of hydroprotective agents were used: FZC-12B and FZC-103D, with a volume ratio of 1:3; two grades of hydrodemetallizing catalysts were used: FZC-28 and FZC-204, with a volume ratio of 2:3; the hydrodesulfurization catalyst was FZC-33BT; and the hydrodenitrogenation catalyst was FZC-41A.

[0074] Table 1 Catalyst loading details

[0075]

[0076] Example 1

[0077] Adopting such Figure 1 The process flow is as follows. The first operation process I includes: the first series of units uses low-sulfur paraffin-based residue oil as raw material to produce low-sulfur marine fuel oil products. The operating conditions are shown in Table 3 and the product properties are shown in Table 4. The products in the first hydrogenation protection zone do not undergo gas-liquid separation and directly enter the first hydrogenation reaction zone for reaction.

[0078] The first operation process II includes: the second series of units uses high-sulfur intermediate base residue oil as feedstock to produce catalytic cracking feedstock, the operating conditions are shown in Table 3, and the product properties are shown in Table 4; wherein, the reduced residue obtained from the vacuum distillation tower of the second series of units is recycled to the second hydrotreating protection reaction zone; the recycling volume of the reduced residue accounts for 12% of the high-sulfur intermediate base residue oil feedstock, measured by volumetric flow rate;

[0079] When the pressure drop of the catalyst bed in the first hydrogenation reaction zone of the first series unit reaches 70% of the maximum design pressure drop, the operation process is switched from the first operation to the second operation process. That is, the product stream from the first hydrogenation protection reaction zone of the first series unit is first separated in the first product gas-liquid separation zone, and the resulting liquid stream is introduced into the second hydrogenation reaction zone of the second series unit. It is mixed with the product stream from the second hydrogenation protection reaction zone of the second series unit and used as the feed for the second hydrogenation reaction zone to produce low-sulfur marine fuel blending components. The operating conditions are shown in Table 3, and the properties of the obtained products are shown in Table 4. At the same time, part of the vacuum wax oil obtained from the vacuum fractionation tower of the second series unit is recycled to the first hydrogenation reaction zone of the first series unit and used as the feed for the first hydrogenation reaction zone. The operating conditions are shown in Table 3.

[0080] When the catalyst bed pressure drop in the second hydrogenation reaction zone of the second series unit reaches 80% of the maximum design pressure drop, the operation process is switched from the second to the third. Specifically, the first hydrogenation protection reaction stream from the first series unit is redirected back to the first hydrogenation reaction zone of the first series unit. Simultaneously, a portion of the product stream from the second hydrogenation protection reaction zone of the second series unit (wherein, the introduction flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 15% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume) is introduced into the first hydrogenation reaction zone of the first series unit. The first series unit is used to produce low-sulfur marine fuel blending components; its operating conditions are shown in Table 3, and the properties of the resulting products are shown in Table 4. Meanwhile, the second series unit is used to produce catalytic cracking feedstock; its operating conditions are shown in Table 3, and the properties of the resulting products are shown in Table 4. This process continues until both units are shut down.

[0081] Example 2

[0082] and Figure 1 Compared to the previous process, the vacuum wax oil from the vacuum fractionation tower is not recycled to the inlet of the first hydrogenation reaction zone. Other operating procedures are the same as in Example 1, the operating conditions are shown in Table 3, and the properties of the obtained products are shown in Table 4.

[0083] Example 3

[0084] Compared to Example 1, when the catalyst bed pressure drop in the first hydrogenation reaction zone of the first series of units reaches 80% of the maximum design pressure drop, the process switches from the first operation to the second operation. When the catalyst bed pressure drop in the second hydrogenation reaction zone of the second series of units reaches 85% of the maximum design pressure drop, the process switches from the second operation to the third operation. In the third operation, a portion of the product stream from the second hydrogenation protection reaction zone of the second series of units (wherein, the introduction flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 10% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume) is introduced into the first hydrogenation reaction zone of the first series of units. Other operations are the same as in Example 1, the operating conditions are shown in Table 3, and the properties of the obtained products are shown in Table 4.

[0085] Example 4

[0086] Compared to Example 2, when the catalyst bed pressure drop in the first hydrogenation reaction zone of the first series of units reaches 60% of the maximum design pressure drop, the process switches from the first operation to the second operation. When the catalyst bed pressure drop in the second hydrogenation reaction zone of the second series of units reaches 75% of the maximum design pressure drop, the process switches from the second operation to the third operation. In the third operation, a portion of the product stream from the second hydrogenation protection reaction zone of the second series of units (wherein, the introduction flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 10% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume) is introduced into the first hydrogenation reaction zone of the first series of units. Other operations are the same as in Example 2, the operating conditions are shown in Table 3, and the properties of the obtained products are shown in Table 4.

[0087] Comparative Example 1

[0088] The difference from Example 1 is that the two series of units operate independently, with no synergistic effect between the first and second series until shutdown. Throughout the entire operating cycle, the first series of units produces low-sulfur marine fuel oil. The operating conditions of the first series of units are shown in Table 3, and the properties of the resulting products are shown in Table 4.

[0089] Comparative Example 2

[0090] The difference from Example 1 is that the two series of units operate independently. The first and second series have no synergistic effect until shutdown. Throughout the entire operation cycle, the second series unit produces catalytic cracking feedstock. The operating conditions of the second series unit are shown in Table 3, and the properties of the resulting products are shown in Table 4.

[0091] Comparative Example 3

[0092] Compared to Example 1, the difference lies in that the two series of units operate independently. The first and second series have no synergistic effect until shutdown. Throughout the entire operating cycle, the second series of units produces low-sulfur marine fuel blending components. The operating conditions of the second series of units are shown in Table 3, and the properties of the resulting products are shown in Table 4.

[0093] Comparative Example 4

[0094] Compared with Example 2, the difference is that in the third operation, the hydrogen protection reaction stream of the second series second hydrogenation protection reaction zone is not introduced into the first hydrogenation reaction zone of the first series device. Other operating conditions are shown in Table 3, and the properties of the obtained products are shown in Table 4.

[0095] Table 2 Properties of Residue Oil Feedstock

[0096]

[0097]

[0098] Table 3 Operating conditions for each example

[0099]

[0100]

[0101] Continued from Table 3: Operating conditions for each example

[0102]

[0103]

[0104] Table 4 shows the properties of the products obtained in each example.

[0105]

[0106]

[0107] Continued in Table 4: Properties of the products obtained in each example

[0108]

[0109]

[0110] Table 5 shows the utilization rate of catalysts used during shutdowns in each case.

[0111] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 First Series One 96％ 95％ 96％ 96％ 90％ — — 93％ Two 96％ 95％ 96％ 96％ 90％ — — 93％ Three 98％ 96％ 97％ 96％ 87％ — — 92％ Four 98％ 96％ 97％ 96％ 87％ — — 92％ Second Series One 95％ 95％ 95％ 95％ — 91％ 90％ 94％ Two 95％ 95％ 95％ 96％ — 91％ 90％ 94％ Three 97％ 97％ 96％ 97％ — 93％ 91％ 95％ Four 97％ 97％ 97％ 97％ — 93％ 91％ 95％

Claims

1. A residue hydrotreating system, comprising two series of residue hydrotreating units arranged in parallel, namely a first series unit and a second series unit, wherein, The first series of units includes a first hydrogenation protection reaction zone, a first product gas-liquid separation zone, a first hydrogenation reaction zone, and a first gas-liquid separation zone. The second series of units includes a second hydrogenation protection reaction zone, a second hydrogenation reaction zone, and a second gas-liquid separation zone. The liquid phase outlet of the first product gas-liquid separation zone is connected to the inlet of the second hydrogenation reaction zone, and the outlet of the second hydrogenation protection reaction zone is connected to the inlet of the first hydrogenation reaction zone. The liquid phase outlet of the first gas-liquid separation zone is connected to the inlet of the first atmospheric distillation tower, and the liquid phase outlet of the second gas-liquid separation zone is connected to the inlet of the second atmospheric distillation tower. The bottom outlet of the second atmospheric distillation tower is connected to the inlet of the vacuum distillation tower. The slag outlet of the vacuum distillation tower is connected to the inlet of the second hydrogenation protection reaction zone.

2. The system according to claim 1, characterized in that, The vacuum oil outlet of the vacuum distillation tower is connected to the inlet of the first hydrogenation reaction zone.

3. The system according to claim 1, characterized in that, The first hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst; the first hydrogenation reaction zone is filled with a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst in sequence according to the material flow direction, preferably, the hydrogenation demetallization catalyst is filled upstream of the hydrogenation desulfurization catalyst; And / or, the second hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst; the second hydrogenation reaction zone is filled with a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst in sequence according to the flow direction.

4. The system according to claim 1, characterized in that, Both the first and second series units are fixed-bed residue hydrotreating units. The reactors in the first series units are all top-down co-current fixed-bed reactors. In the second series units, the reactors in the second hydrotreating protection reaction zone are either co-current fixed-bed reactors or upflow fixed-bed reactors. The reactors in the second hydrotreating reaction zone are all top-down co-current fixed-bed reactors.

5. A method for hydrotreating residual oil, characterized in that, The residual oil hydrotreating system according to any one of claims 1-4 is used, the method comprising a first operation process I and a first operation process II operating simultaneously, as well as a second operation process and a third operation process; The first operation process I includes: the first series of units using low-sulfur paraffin-based residue oil as raw material to produce low-sulfur marine fuel oil products; The first operation process II includes: the second series of units uses high-sulfur intermediate base residue oil as raw material to produce catalytic cracking feed or low-sulfur marine fuel oil blending components; When the pressure drop of the catalyst bed in the first hydrogenation reaction zone of the first series unit reaches 50% to 90% of the maximum design pressure drop, preferably 60% to 80%, the operation is switched from the first operation to the second operation. That is, the product stream from the first hydrogenation protection reaction zone of the first series unit is introduced into the second hydrogenation reaction zone of the second series unit and mixed with the product stream from the second hydrogenation protection reaction zone of the second series unit as feed for the second hydrogenation reaction zone, which is used to produce low-sulfur marine fuel blending components. Preferably, at the same time, a portion of the vacuum wax oil obtained from the vacuum fractionation tower of the second series unit is recycled back to the first hydrogenation reaction zone of the first series unit as feed for the first hydrogenation reaction zone. When the catalyst bed pressure drop in the second hydrogenation reaction zone of the second series unit reaches 65% to 90% of the maximum design pressure drop, preferably 70% to 85%, the operation transitions from the second to the third process. Specifically, the first hydrogenation protection reaction stream from the first series unit is redirected back to the first hydrogenation reaction zone of the first series unit. Simultaneously, a portion of the product stream from the second hydrogenation protection reaction zone of the second series unit (preferably, the introduction flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 10% to 20% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume) is introduced into the first hydrogenation reaction zone of the first series unit. The first series unit is used to produce low-sulfur marine fuel blending components, while the second series unit is used to produce low-sulfur marine fuel blending components or catalytic cracking feedstock, until both units are shut down.

6. The method according to claim 5, characterized in that, The low-sulfur paraffinic residue feedstock has a saturated content of 18% or more, further 18% to 24% by mass, and an aromatic content of 30% or less, further 25% to 30% by mass. By mass fraction, the sulfur content in the low-sulfur paraffinic residue feedstock is not higher than 4.0%, further 1.0% to 4.0%, and even further 0.8% to 2.0%; the total content of heavy metals nickel and vanadium is not higher than 200 μg / g, further 40 to 100 μg / g; the nitrogen content is not higher than 0.80%, further 0.20% to 0.65%; and the saturated carbon residue is not higher than 17%, further 5.0% to 15.0%. And / or, in the high-sulfur intermediate base residue feedstock, the mass content of saturated components is less than 15%, further 13% to 15%, and the mass content of aromatic components is more than 45%, further 45% to 48%; by mass fraction, the sulfur content in the high-sulfur intermediate base residue feedstock is not higher than 5.0%, further 1.5% to 4.5%, and even further 2.5% to 4.0%; the total content of heavy metals nickel and vanadium is not higher than 200 μg / g, further 50 to 120 μg / g; the nitrogen content is not higher than 0.80%, further 0.20% to 0.50%; and the KORP residue is not higher than 17%, further 7.0% to 15.0%.

7. The method according to claim 5, characterized in that, The first series of units are residue hydrotreating units that directly produce low-sulfur marine fuel oil products from low-sulfur paraffin-based residue oil; the second series of units are residue hydrotreating units that produce catalytic cracking feedstock or marine fuel oil blending components from high-sulfur intermediate-based residue oil.

8. The method according to claim 5 or 6, characterized in that, The first operation process I of the first series of units includes: low-sulfur paraffin-based residue oil feedstock and hydrogen are mixed and fed into the first hydrogenation protection reaction zone for reaction. The product obtained in the first hydrogenation protection zone is not subjected to gas-liquid separation and is directly fed into the first hydrogenation reaction zone for reaction. The product stream obtained in the first hydrogenation reaction zone is fed into the first gas-liquid separation zone for gas-liquid separation. The separated liquid phase is fed into the first atmospheric distillation tower for fractionation. The atmospheric hydrogenated heavy oil obtained is the marine fuel oil product. And / or, the first operation process II of the second series unit includes: high-sulfur intermediate base residue feedstock, recycled reduced residue and hydrogen are mixed and fed into the second hydrotreating protected reaction zone for reaction; the product stream from the second hydrotreating protected zone is fed into the second hydrotreating reaction zone for reaction; the product stream from the second hydrotreating reaction zone is fed into the second gas-liquid separation zone for gas-liquid separation; the separated liquid phase is fed into the second atmospheric distillation tower for fractionation; the obtained atmospheric residue is fed into the vacuum distillation tower for vacuum fractionation to obtain vacuum wax oil and reduced residue; wherein, the reduced residue is used as catalytic cracking feedstock or low-sulfur marine fuel oil blending component, preferably catalytic cracking feedstock.

9. The method according to claim 8, characterized in that, The reduced residue obtained from the vacuum distillation tower of the second series unit is recycled to the second hydrogenation protection reaction zone; furthermore, the recycling volume of the reduced residue accounts for 10% to 15% of the high-sulfur intermediate base residue feedstock, measured by volumetric flow rate.

10. The method according to claim 5, characterized in that, The process transitions from the first operation to the second operation, whereby the product stream from the first hydrogenation protection reaction zone of the first series of units enters the first product gas-liquid separation zone, and the resulting liquid stream is introduced into the second hydrogenation reaction zone of the second series of units. The liquid stream is then mixed with the product stream from the second hydrogenation protection reaction zone of the second series of units and enters the second hydrogenation reaction zone to produce low-sulfur marine fuel blending components.

11. The method according to claim 5, characterized in that, The process transitions from the second to the third operation, whereby the effluent from the first hydrogenation protection reaction zone of the first series of units is not subjected to gas-liquid separation and is directly returned to the first hydrogenation reaction zone of the first series of units. Simultaneously, a portion of the product stream from the second hydrogenation protection reaction zone of the second series of units is introduced into the first hydrogenation reaction zone of the first series of units (preferably, the introduced flow rate of the product stream from the second hydrogenation protection reaction zone accounts for 10% to 20% of the product stream flow rate from the first hydrogenation protection reaction zone, by volume), to produce low-sulfur marine fuel blending components. The second series of units is used to produce low-sulfur marine fuel blending components or catalytic cracking feedstock until both units are shut down.

12. The method according to claim 5, characterized in that, In the first series of units, marine fuel oil products are produced using low-sulfur paraffinic residue oil as feedstock. This involves catalyst loading and controlling the production conditions of the first operation process I. Preferably, the operating conditions in the first hydrotreating protected reaction zone of the first operation process I are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 410°C, and liquid hourly space velocity of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 200–2000; preferably, the hydrogen partial pressure is 12 MPa–18 MPa, the reaction temperature is 315°C–400°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1500. In the first operation process I, the operating conditions of the first hydrogenation reaction zone are as follows: hydrogen partial pressure of 10 MPa–20 MPa, reaction temperature of 310°C–420°C, and liquid hourly space velocity of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 250–2000; preferably, the hydrogen partial pressure is 14 MPa–18 MPa, the reaction temperature is 320°C–410°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1800. And / or, in the second series of units, marine fuel oil blending components are produced using high-sulfur intermediate base residue as feedstock, or catalytic cracking feedstock is loaded with catalyst and the production conditions of the first operation process II are controlled; preferably, in the first operation process II, the operating conditions of the second hydrotreating protected reaction zone are as follows: hydrogen partial pressure of 10 MPa to 20 MPa, reaction temperature of 310°C to 410°C, and liquid hourly space velocity of fresh feedstock of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 200–2000; preferably, the hydrogen partial pressure is 13 MPa–19 MPa, the reaction temperature is 320°C–400°C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 420–1600; the operating conditions of the second hydrogenation reaction zone in the first operation process II are as follows: hydrogen partial pressure of 10 MPa–20 MPa, reaction temperature of 310°C–420°C, and liquid hourly space velocity of fresh feedstock of 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 280–2000; preferably, the hydrogen partial pressure is 14 MPa–19 MPa, the reaction temperature is 330°C–410°C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 450–1800.

13. The method according to claim 5 or 12, characterized in that, In the first series of devices, the first hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst, and the first hydrogenation reaction zone is filled with an optional hydrogenation demetallization catalyst, a hydrogenation desulfurization catalyst, and a hydrogenation denitrification catalyst; wherein, based on the total loading volume of the catalysts, the hydrogenation protection catalyst accounts for 6% to 30% of the total loading volume, preferably 8% to 25%; the hydrogenation demetallization catalyst accounts for 10% to 50% of the total loading volume, preferably 20% to 40%; the hydrogenation desulfurization catalyst accounts for 20% to 80% of the total loading volume, preferably 25% to 55%; and the hydrogenation denitrification catalyst accounts for 20% to 80% of the total loading volume, preferably 20% to 50%. And / or, in the second series of devices, the second hydrogenation protection reaction zone is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst, and the second hydrogenation reaction zone is filled with a hydrogenation desulfurization catalyst and a hydrogenation denitrification catalyst. Specifically, based on the total catalyst loading volume, the hydrogenation protection catalyst accounts for 6% to 30% of the total loading volume, preferably 8% to 25%; the hydrogenation demetallization catalyst accounts for 10% to 55% of the total loading volume, preferably 20% to 45%; the hydrogenation desulfurization catalyst accounts for 25% to 80% of the total loading volume, preferably 25% to 60%; and the hydrogenation denitrification catalyst accounts for 20% to 75% of the total loading volume, preferably 20% to 45%.

14. The method according to claim 5, characterized in that, The first series of devices uses four reactors. In the first reactor, the volume ratio of hydrogenation protective agent to hydrogenation demetallization catalyst is (0.5-5):1, more preferably (0.8-3):1; in the second reactor, the volume ratio of hydrogenation demetallization catalyst to hydrogenation protective agent is (0.5-20):1, more preferably (1-10):1; in the third reactor, the volume ratio of hydrogenation desulfurization catalyst to hydrogenation demetallization catalyst is (0.5-20):1, more preferably (5-10):1; and in the fourth reactor, the volume ratio of hydrogenation denitrogenation catalyst to hydrogenation desulfurization catalyst is (0.5-20):1, more preferably (5-10):

1. And / or, the second series of devices employs four reactors. In the first reactor, the volume ratio of hydrogenation protective agent to hydrogenation demetallization catalyst is (0.5-5):1, more preferably (1-3):1; in the second reactor, the volume ratio of hydrogenation demetallization catalyst to hydrogenation protective agent is (0.5-20):1, more preferably (3-10):1; a hydrogenation desulfurization catalyst is loaded in the third reactor; and in the fourth reactor, the volume ratio of hydrogenation desulfurization catalyst is 1%-40% of the total catalyst loading volume in the fourth reactor, preferably 5%-30%, and the volume of hydrogenation denitrification catalyst is 60%-99% of the total catalyst loading volume in the fourth reactor, preferably 70%-95%.

15. The method according to claim 5, characterized in that, In the second operation, the operating conditions of the second hydrogenation reaction zone of the second series unit are adjusted as follows: compared with the operating conditions of the second hydrogenation reaction zone in the first operation process II, the hydrogen partial pressure is increased (at least by 0.1 MPa, preferably by 0.2 to 2.0 MPa), the reaction temperature is decreased (at least by 4°C, preferably by 4°C to 7°C), and the volume hourly space velocity is increased (at least by 0.01 h⁻¹). -1 The preferred improvement is 0.01 to 0.5 h. -1 Increase the hydrogen-to-oil volume ratio (at least 5, preferably 5-200), further increase the hydrogen partial pressure to 15-25 MPa, and increase the liquid hourly space velocity of the fresh feedstock to 0.24 h⁻¹. -1 ~2.2h -1 The total hydrogen-to-oil volume ratio is increased to 300–2200; preferably, compared with the operating conditions of the second hydrogenation reaction zone in the first operation process II, the hydrogen partial pressure is increased to 16 MPa–20 MPa, the reaction temperature is decreased by 5–6 °C, and the liquid hourly space velocity of the fresh feedstock is increased to 0.27 h⁻¹. -1 ~1.95h -1 This will increase the total hydrogen-to-oil volume ratio to 500–1800. And / or, in the second operation, the operating conditions of the first hydrogenation reaction zone of the first series of devices are adjusted as follows: compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is reduced (at least 1 MPa), the reaction temperature is reduced (at least 10 °C), and the liquid hourly space velocity is increased (at least 0.1 h⁻¹). -1 This reduces the total hydrogen-to-oil volume ratio (by at least 50%). Specifically, compared to the operating conditions in the first hydrogenation reaction zone of the first operation process I, the hydrogen partial pressure is reduced to 8 MPa–18 MPa, the reaction temperature is reduced to 300°C–370°C, and the liquid hourly space velocity is increased to 0.22 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is reduced to 100–400; preferably, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is reduced to 10 MPa–16 MPa, the reaction temperature is reduced to 310°C–365°C, and the liquid hourly space velocity is increased to 0.3 h⁻¹. -1 ~2.5h -1 The total hydrogen-to-oil volume ratio is reduced to 100-350.

16. The method according to claim 5, characterized in that, In the third operation, the operating conditions of the first hydrogenation reaction zone of the first series of devices are as follows: compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the reaction temperature is increased (at least by 10°C, preferably by 10–40°C); specifically, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is 10 MPa–20 MPa, the reaction temperature is increased to 350°C–425°C, and the liquid hourly space velocity is 0.1 h⁻¹. -1 ~3.0h -1 The total hydrogen-to-oil volume ratio is 300–2000; preferably, compared with the operating conditions of the first hydrogenation reaction zone in the first operation process I, the hydrogen partial pressure is 14 MPa–18 MPa, the reaction temperature is increased to 360°C–420°C, and the liquid hourly space velocity is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 400–1800. And / or, in the third operation, the operating conditions of the second hydrogenation reaction zone of the second series unit are as follows: compared with the operating conditions of the second hydrogenation reaction zone in the second operation, the hydrogen partial pressure is 15 MPa to 25 MPa, the reaction temperature is increased by 8 to 40 °C, and the liquid hourly space velocity of the fresh feedstock is 0.15 h⁻¹. -1 ~2.0h -1 The total hydrogen-to-oil volume ratio is 300–2200; preferably, the hydrogen partial pressure is 16 MPa–20 MPa, the reaction temperature is increased by 10–30 °C, and the liquid hourly space velocity of the fresh feedstock is 0.16 h⁻¹. -1 ~1.8h -1 The total hydrogen-to-oil volume ratio is 500–1800.

17. The method according to claim 5, characterized in that, When the first and second series of units were shut down, the utilization rate of the catalyst in each reactor exceeded 95%.

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