Catalytic diesel oil hydro-conversion method

Abstract

The invention provides a catalytic diesel oil hydro-conversion method which comprises the following steps: (1) catalytic diesel oil and hydrogen enter a hydrofining reaction unit to react, and a hydrofining material flow is obtained after the reaction; (2) separating the hydrofined material flow obtained in the step (1) in a separator to obtain a light material flow and a heavy material flow; (3) the heavy material flow obtained in the step (2) enters a hydrocracking reaction unit to react, and a hydrocracking material flow is obtained after the reaction; and (4) separating the hydrocracking material flow obtained in the step (3) to obtain gas, gasoline and diesel oil. According to the conversion method, a high-octane gasoline product can be obtained at the initial stage of start-up by optimizing the technological process, and meanwhile, the cetane number of the diesel fraction is remarkably increased.

Description

Technical Field

[0001] This invention relates to a catalytic diesel hydroconversion method, and particularly to a catalytic diesel hydroconversion method that can produce high-octane gasoline products, belonging to the field of petroleum refining technology. Background Technology

[0002] The high-value utilization of catalytic diesel is challenging and has become a key area of ​​research for petrochemical companies and research institutions. Exploring the intrinsic properties of catalytic diesel under the concept of molecular refining has become a desirable approach. Currently, converting catalytic diesel into high-octane gasoline is the mainstream route, which helps companies reduce the diesel-to-gasoline ratio and contribute to achieving quality and efficiency improvement goals.

[0003] The existing process for producing gasoline from catalytic diesel still faces several pressing challenges in industrial production. The first problem is the low octane number of the gasoline fraction during the initial operation phase. Within the first month of operation, the octane number typically only reaches 80-85, significantly lower than the desired octane number of 90 or above. The second problem is the inability to precisely control the aromatics saturation performance and hydrodenitrogenation performance of the hydrorefining catalyst. While the hydrodenitrogenation reaction aims to maintain a high saturation level to maximize the activity of the hydrocracking catalyst, the aromatics saturation reaction requires precise control. The gasoline fraction needs minimal saturation to efficiently retain high-octane components, while the diesel fraction needs maximum saturation. The third problem is that the high aromatics content in the catalytic diesel causes a violent aromatics saturation reaction in the hydrorefining section, releasing a large amount of heat. Improper control can lead to abnormally high temperatures, potentially carrying these heat into the hydrocracking reactor and causing a series of uncontrollable cracking reactions, resulting in safety accidents and affecting the safe, stable, long-term, full-capacity, and high-efficiency operation of the unit. The fourth problem is that although the cetane number of the produced diesel is 10 units higher than that of the feedstock, it is still relatively low (cetane number ~40), requiring blending to produce qualified diesel products (cetane number >51). Therefore, there is an urgent need to upgrade the existing process to solve the above bottlenecks, thereby achieving the goals of shortening the adjustment time of gasoline product octane number, increasing the yield of gasoline fractions, providing cetane number for diesel fractions, and ensuring long-term stable operation of the unit.

[0004] Patent CN114763489A discloses a combined catalytic diesel processing technology and system that organically combines a hydrotreating pretreatment unit with a fluidized bed unit to produce gasoline fractions with high monocyclic aromatic hydrocarbon content. This solves the technical problems caused by the high aromatic hydrocarbon content and complex composition of catalytic diesel, which lead to significant differences in hydroconversion patterns, resulting in strong exothermic reactions, easy generation of hot spots, difficulty in controlling the reaction process, poor product quality, low yield, and short equipment operation cycle. However, it requires the construction of a new fluidized bed reactor, resulting in a large investment.

[0005] Patent CN112625742A discloses a method for hydrotreating inferior diesel fuel, which divides the hydrorefining reactor into four reaction zones and loads different types of hydrorefining catalysts in a graded manner. This method can process high-sulfur, high-nitrogen inferior diesel fuel fractions, thereby increasing the yield of gasoline fractions. Summary of the Invention

[0006] To address the problems existing in the current catalytic diesel hydroconversion process, the core objective of this invention is to provide a catalytic diesel hydroconversion method. This method, by optimizing the process flow, can reduce the operational difficulty of the refining section while shortening the initial setup time of the unit. It can obtain high-octane gasoline products at the beginning of operation and significantly improve the cetane number of the diesel fraction, thereby improving the overall economic efficiency of the unit.

[0007] This invention provides a method for catalytic diesel hydroconversion, comprising the following steps:

[0008] (1) Under hydrorefining reaction conditions, catalytic diesel and hydrogen enter the hydrorefining reaction unit to react, and the hydrorefined feed stream is obtained after the reaction.

[0009] (2) The hydrorefined feed stream obtained in step (1) is separated into light feed stream and heavy feed stream after entering the separator. The operating temperature of the separator is 160-340℃, and more preferably 200-280℃.

[0010] (3) Under hydrocracking reaction conditions, the heavy feed stream obtained in step (2) enters the hydrocracking reaction unit for reaction, and after the reaction, a hydrocracking feed stream is obtained.

[0011] (4) The hydrocracking feedstock obtained in step (3) is separated to obtain gas, gasoline and diesel.

[0012] In a further preferred embodiment, the catalytic diesel in step (1) is an intermediate fraction obtained from fractionation after catalytic cracking reaction at 150°C to 375°C, with a total aromatic content of more than 70 wt%, preferably 75 wt% to 90 wt%.

[0013] In a further preferred embodiment, the hydrorefining reaction unit in step (1) is generally provided with at least one catalyst bed, preferably two to five catalyst beds. When two or more catalyst beds are provided, they can be provided in one hydrorefining reactor or in separate hydrorefining reactors. The hydrorefining reactor is preferably a fixed-bed hydrorefining reactor.

[0014] In a further preferred embodiment, the hydrorefining reaction unit in step (1) is filled with a hydrorefining catalyst. Those skilled in the art, based on their knowledge, can select from commercially available hydrorefining catalysts according to the properties of the raw materials and product specifications, or prepare the catalyst according to methods disclosed in the art as needed. Specifically, commercially available hydrorefining catalysts such as FHUDS-8, FF-66, FF-36, and FF-56 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. (FRIPP) can be used. The hydrorefining catalyst generally includes a hydrorefining active metal component and a support. The hydrorefining active metal can be one or more of Group VIB, Group VIIB, and Group VIII metal elements, specifically selected from at least one of Co, Mo, Ni, and W. The support can generally be an inorganic refractory oxide such as alumina or silicon dioxide.

[0015] In a further preferred embodiment, the separator in step (2) is generally a high-pressure separator. After separation, a light material flow is generally obtained in the upper part (including the top) of the separator, and a heavy material flow is obtained in the lower part (including the bottom) of the separator.

[0016] In a further preferred embodiment, the heavy feed stream obtained in step (2) can be divided into two streams. The first stream of heavy feed stream enters the hydrocracking reaction unit for reaction, and the second stream of heavy feed stream is recycled back to the hydrorefining reaction unit to be mixed with catalytic diesel for processing.

[0017] In a further preferred embodiment, as a specific implementation, the proportion of the first heavy feed stream to the total heavy feed stream is dynamically adjusted during the initial stage of unit operation. Starting from the moment the unit switches from operating oil to catalytic diesel feedstock, the proportion of the first heavy feed stream to the total heavy feed stream is continuously and dynamically adjusted in real time. Specifically, the corresponding proportion (M) can be determined using a preset function based on the time elapsed since the switch to catalytic diesel feedstock (duration (h)). h );

[0018] Same as representing the proportion of the first heavy mass flow to the total heavy mass flow (M) h The preset function relating the duration (h) to the time (h) is as follows:

[0019] M h =0.01×(0.0276h) 2 -2.05h+66);

[0020] Wherein, the duration (h) is the time elapsed since the current moment when switching to catalytic diesel feedstock, and the duration is an integer value in days; in this embodiment of the invention, the time point at which the proportion of the first heavy feedstock stream to the total heavy feedstock stream is stopped can be determined by setting the maximum value of the duration (h).

[0021] In practical applications, the maximum value of the duration (h) is no greater than 35;

[0022] Furthermore, the preferred maximum value of the duration (h) is any value between 28 and 34; after h reaches its maximum value, the adjustment of the proportion of the first heavy material flow to the total heavy material flow is stopped and maintained at a constant value.

[0023] In a further preferred embodiment, the light feed stream obtained after separation in step (2) enters the hydrocracking reaction unit for processing, preferably through the second feed inlet (the second feed inlet is located on the reactor shell); wherein, the catalyst loading volume between the second feed inlet and the first feed inlet (the first feed inlet is located at the top or bottom of the reactor (when using an upflow reactor with bottom feeding)) is 25% to 80% of the total catalyst loading volume of the reactor, more preferably 35% to 65%. The heavy feed stream (the first heavy feed stream) entering the hydrocracking reaction unit enters through the first feed inlet.

[0024] In a further preferred embodiment, the hydrocracking reaction unit is loaded with a hydrocracking catalyst having cracking function. Those skilled in the art, based on their knowledge, can select from existing commercially available hydrocracking catalysts according to the properties of the raw materials and product specifications, or prepare them according to methods disclosed in the art as needed. Specifically, commercial hydrocracking catalysts such as FC-32, FC-46, FC-90, and FC-52 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. (FRIPP) can be used. The hydrocracking catalyst includes a hydrocracking active metal component and a support. The hydrocracking active metal can be one or more metal elements from Group VIB, Group VIIB, and Group VIII, specifically selected from at least one of Co, Mo, Ni, and W as the hydrocracking active metal component. The support typically includes amorphous silica-alumina and molecular sieves. Furthermore, based on the weight of the hydrocracking catalyst, the content of the hydrocracking component, calculated as oxides, is generally 20wt%–25wt%, and the specific surface area is 350–420 m². 2 ·g -1 The pore volume is 0.32–0.36 g·cm³. -3 .

[0025] In a further preferred embodiment, the hydrocracking reaction unit in step (3) is provided with at least one catalyst bed, preferably two or three catalyst beds.

[0026] In a further preferred embodiment, the hydrocracking reaction unit is provided with two catalyst beds, which are arranged sequentially according to the direction of liquid phase material flow as a first catalyst bed and a second catalyst bed. The first catalyst bed is located between the first feed inlet and the second feed inlet, and the second catalyst bed is located between the second feed inlet and the discharge outlet. Compared with the hydrocracking catalyst B loaded in the second catalyst bed, the hydrocracking catalyst B, based on the weight of the hydrocracking catalyst, has a lower content of hydrogenation metal components (calculated as oxides) of 0-5 wt% than that of hydrocracking catalyst A.

[0027] In a further preferred embodiment, the hydrorefining reaction conditions in step (1) are generally as follows: reaction temperature is 320–430°C, preferably 330–420°C; reaction pressure is 5–20 MPa, preferably 6–15 MPa; and volume hourly space velocity (for fresh catalytic diesel feed) is 0.2–3.0 h⁻¹. -1 Preferably, it is 0.6 to 1.2 hours. -1 .

[0028] In a further preferred embodiment, the hydrocracking reaction conditions in step (3) are generally as follows: reaction temperature is 330–430°C, preferably 350–420°C; reaction pressure is 5–20 MPa, preferably 6–15 MPa; and volume hourly space velocity (for fresh catalytic diesel feed) is 0.2–3.0 h⁻¹. -1 Preferably, it is 0.6 to 1.8 hours. -1 .

[0029] In a further preferred embodiment, the hydrorefining reaction pressure is 0.5 to 5.0 MPa higher than the hydrocracking reaction pressure, and more preferably 1.0 to 2.0 MPa.

[0030] In a further preferred embodiment, as a specific implementation, the hydrogen-to-oil volume ratio in the operating conditions of the hydrorefining reaction unit is dynamically adjusted during the initial stage of unit operation. Starting from the moment the unit switches from operating oil to catalytic diesel feedstock, the hydrogen-to-oil volume ratio is continuously and dynamically adjusted in real time. Specifically, the corresponding hydrogen-to-oil volume ratio (V0) can be determined using a preset function based on the time elapsed since the switch to catalytic diesel feedstock (duration (h)). h );

[0031] Same as expressing the hydrogen-to-oil volume ratio (V h The preset function relating the duration (h) to the time (h) is as follows:

[0032] V h =0.46h 2 -10h+930;

[0033] Wherein, the duration (h) is the time elapsed since the current moment when switching to catalytic diesel feedstock, and the duration is rounded to the nearest integer in days; in this embodiment of the invention, the time point at which to stop adjusting the hydrogen-oil volume ratio can be determined by setting the maximum value of the duration (h).

[0034] In practical applications, the maximum value of the duration (h) is no greater than 35;

[0035] Furthermore, the preferred maximum value of the duration (h) is any value between 28 and 34; after h reaches its maximum value, the adjustment of the hydrogen-oil volume ratio is stopped and maintained at a constant value.

[0036] In a further preferred embodiment, the hydrogen-to-oil volume ratio of the hydrocracking reaction unit changes with the hydrogen-to-oil volume ratio of the hydrorefining reaction unit, without the need for separate adjustment.

[0037] In a further preferred embodiment, the separation of the hydrocracking feedstock in step (4) generally includes gas-liquid separation and fractionation. The specific process is as follows: the hydrocracking feedstock first enters the gas-liquid separator and is separated into a gas phase feedstock and a liquid phase feedstock; the separated liquid phase feedstock enters the fractionation tower and is separated to obtain gas, gasoline, and diesel; the separated gas phase feedstock preferably undergoes purification treatment (generally desulfurization treatment) and is then processed by a circulating hydrogen compressor before it can be used as circulating hydrogen.

[0038] Compared with existing catalytic diesel hydroconversion processes, the catalytic diesel hydroconversion method provided by this invention can bring one or more of the following technical effects:

[0039] (1) In the initial stage of traditional catalytic diesel hydroconversion process, the activity of the hydrorefining catalyst is high, resulting in a saturation depth greater than expected, which leads to a low octane number of gasoline products (80-85) in the early stage. It takes a long time to adjust the operation and adjust the process. After the activity of the hydrorefining catalyst stabilizes, the octane number of gasoline products can reach above 90. The adjustment period usually takes close to 30 days.

[0040] (2) If the activity of the hydrorefining catalyst is actively reduced, the operating cycle of the unit will be limited, and the cetane number of the diesel fraction will be further reduced. In the method provided by the present invention, the hydrorefining product is separated, and a portion of the separated heavy feed stream is recycled to the hydrorefining reactor. This can increase the volume hourly space velocity of the hydrorefining reactor. At the same time, a program is set to dynamically adjust the recycling rate of the heavy feed stream, which is coupled with the activity temperature stage of the hydrorefining catalyst. This allows the gasoline octane number to reach above 90 at the beginning of the unit's operation, while also improving the saturation capacity of aromatics in the diesel fraction, thereby significantly increasing the cetane number of the diesel fraction.

[0041] (2) In the catalytic diesel hydroconversion method provided by the present invention, the separated heavy feed stream is partially recycled to the hydrorefining reactor. After the heavy feed stream has been hydrotreated, the aromatic content has been greatly reduced. When mixed with fresh catalytic diesel, it can play a harmonizing role, which can reduce the temperature rise of the hydrorefining reactor and help the operation stability and safety of the device. In particular, it solves the problem that the temperature rise of the reactor is not easy to control when the hydrorefining catalyst activity is high in the early stage of operation.

[0042] (3) In the catalytic diesel hydroconversion method provided by this invention, the hydrogen-to-oil volume ratio and the circulation ratio of the heavy feedstock in the reaction conditions can be precisely controlled by program to adjust the hydrodenitrogenation performance and aromatic saturation performance of the catalyst. This allows the denitrogenation activity to be fully utilized while the aromatic saturation is precisely controlled. At the same time, the reaction pressures of the refining and cracking reaction units can be controlled separately. This avoids the loss of large aromatic potential in gasoline due to excessive aromatic saturation in the gasoline fraction, while simultaneously saturating the aromatics in the diesel fraction.

[0043] (4) In the catalytic diesel hydrocracking method provided by the present invention, the feeding method of the hydrocracking reactor is optimized. The light feed stream and the heavy feed stream obtained after separation of the hydrorefining feed stream enter the hydrocracking reactor through different feed inlets. The upper part of the reactor provides a favorable reaction zone with low space velocity for aromatic conversion. At the same time, the residence time of monocyclic aromatics and cycloalkanes in the light feed stream is shortened in the hydrocracking reactor, so that monocyclic aromatics are effectively retained and the yield of low carbon hydrocarbons is reduced. Ultimately, higher liquid product yield, higher gasoline octane number and diesel cetane number are achieved, which improves the economic benefits for enterprises. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a catalytic diesel hydroconversion process in an embodiment of the present invention.

[0045] Among them, 1-catalytic diesel feedstock; 2-hydrorefining reactor; 3-hydrorefining feed stream; 4-separator; 5-light feed stream; 6-second heavy feed stream; 7-first heavy feed stream; 8-hydrocracking reactor; 9-hydrocracking feed stream; 10-gas-liquid separator; 11-liquid feed stream; 12-fractionation tower; 13-gaseous product; 14-gasoline; 15-diesel; 16-gas feed stream; 17-recycle hydrogen compressor; 18-recycle hydrogen; 19-new hydrogen. Detailed Implementation

[0046] The technical solution and technical effects of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0048] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0049] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0050] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0051] In the context of this invention, all numerical values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numerical value.

[0052] In the context of this invention, "substantially" means that deviations that are acceptable or considered reasonable to those skilled in the art are permitted, such as deviations within ±5%, ±2%, ±1%, ±0.5%, or ±0.1%.

[0053] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0054] In the context of this invention, any two or more embodiments or aspects of this invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0055] The process flow of the catalytic diesel hydroconversion method provided by this invention is as follows: Figure 1As shown, in the presence of hydrogen (including new hydrogen 19 and recycled hydrogen 18), catalytic diesel feedstock 1 enters the hydrorefining reactor 2 and reacts with the hydrorefining catalyst packed inside the reactor. The resulting hydrorefined feed stream 3 enters the separator 4 for light and heavy component separation. The top of the separator yields a light feed stream 5, and the bottom of the separator yields a heavy feed stream. The heavy feed stream can be divided into two paths: a first heavy feed stream 7 and a second heavy feed stream 6. The second heavy feed stream 6 can be recycled back to the hydrorefining reactor for further processing. The first heavy feed stream 7 enters from the first inlet at the top of the reactor. The light feed stream 5, obtained after separation by separator 4, enters hydrocracking reactor 8 through the second feed port in the middle of the reactor and reacts with the hydrocracking catalyst packed in the reactor. The resulting hydrocracking feed stream 9 enters gas-liquid separator 10 for gas-liquid separation, resulting in gas phase feed stream 16 and liquid phase feed stream 11. Liquid feed stream 11 enters fractionation tower 12 and is separated to obtain gaseous products 13, gasoline 14, and diesel 15. Gas phase feed stream 16 is processed by circulating hydrogen compressor 17 and can be recycled as circulating hydrogen 18 to hydrorefining reactor and / or hydrocracking reactor.

[0056] The properties of the catalytic diesel feedstock used in this paper are shown in Table 1.

[0057] Table 1 Properties of Catalytic Diesel Feedstock

[0058] Item Catalytic diesel Density (20°C), kg / m 3 ]] 928.6 Nitrogen content, mg / kg 506 Sulfur content, mg / kg 5266 Distillation range, °C 198～356 Total aromatics content, wt% 75.5 Cetane number 20.6

[0059] Example 1

[0060] This embodiment adopts Figure 1 The catalytic diesel hydroconversion process flow shown is illustrated in Table 1. The properties of the catalytic diesel feedstock are listed below. Catalytic diesel is mixed with hydrogen and fed into a hydrorefining reactor for hydrorefining. The resulting hydrorefined feed stream is then separated into light and heavy feed streams (cutting temperature 200℃). The light feed stream does not enter the hydrocracking reactor. The hydrorefining reactor is loaded with FF-66 hydrorefining catalyst, while the hydrocracking reactor is loaded with FC-32 catalyst. The hydrogen-to-oil volume ratio at the hydrorefining reactor inlet is 1050:1. The reaction pressure in both the hydrorefining and hydrocracking reactors is 10.0 MPa, and the volume hourly space velocity (VHSV) is 0.8 h⁻¹ in each reactor. -1 and 1.8h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is to control the nitrogen content of the hydrorefining feed stream to 8 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 46%. The reaction results are shown in Table 1.

[0061] Example 2

[0062] This embodiment adopts Figure 1 The catalytic diesel hydroconversion process flow shown is illustrated in Table 1, and the properties of the catalytic diesel feedstock are listed below. Catalytic diesel is mixed with hydrogen and fed into a hydrorefining reactor for hydrorefining. The resulting hydrorefined feed stream enters a separator to obtain light and heavy feed streams at a cutting temperature of 280℃. The first heavy feed stream enters the hydrocracking reactor through the first inlet at the top, while the second heavy feed stream is recycled back to the hydrorefining reactor for further processing. The proportion of the first heavy feed stream to the total heavy feed stream (M...) is... h The hydrogen-to-oil volume ratio (V) in the hydrorefining reactor h In the initial stage of construction, adjustments are made dynamically, according to M. h =0.01×(0.0276h) 2 -2.05h+66), V h =0.46h 2 The process is controlled at -10h + 930, with each h being 30 days. Light feedstock enters the hydrocracking reactor through the second inlet for hydroconversion. The catalyst volume between the first and second inlets accounts for 65% of the total catalyst loading volume of the reactor. The hydrorefining reactor is loaded with hydrorefining catalyst FHUDS-8. The hydrocracking reactor is loaded with FC-46 catalyst in the region between the first and second inlets according to the liquid phase material flow direction, and with FC-90 catalyst in the region between the second inlet and outlet. The reaction pressures in the hydrorefining and hydrocracking reactors are 12.0 MPa and 10.0 MPa, respectively, and their volume hourly space velocities are 0.9 h⁻¹ and 0.9 h⁻¹, respectively. -1 1.2h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is to control the nitrogen content of the hydrorefining feed stream to 10 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 50%. The reaction results are shown in Table 1.

[0063] Example 3

[0064] This embodiment adopts Figure 1 The catalytic diesel hydroconversion process flow shown is illustrated in Table 1, and the properties of the processed catalytic diesel feedstock are listed below. Catalytic diesel, the second heavy feed stream, and hydrogen are mixed and fed into the hydrorefining reactor for hydrorefining. The resulting hydrorefined feed stream is then separated into light and heavy feed streams at a cutting temperature of 260°C. The first heavy feed stream enters the hydrocracking reactor through the first inlet at the top, while the second heavy feed stream is recycled back to the hydrorefining reactor for further processing. The proportion of the first heavy feed stream to the total heavy feed stream (M...) is... h The hydrogen-to-oil volume ratio (V) in the hydrorefining reactor hIn the initial stage of construction, adjustments are made dynamically, according to M. h =0.01×(0.0276h) 2 -2.05h+66), V h =0.46h 2 The reaction time was adjusted to -10h +930, with h being 28 and 34 days respectively. Light feedstock entered the hydrocracking reactor through the feed inlet at the top. The hydrorefining reactor was loaded with hydrorefining catalyst FF-76, and the hydrocracking reactor was loaded with catalyst FC-70A. The reaction pressure in both the hydrorefining and hydrocracking reactors was 12.0 MPa, and the volume hourly space velocity (VHSV) in both reactors was 1.0 h⁻¹. -1 1.5h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is to control the nitrogen content of the hydrorefining feed stream to 5 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 46%. The reaction results are shown in Table 1.

[0065] Example 4

[0066] This embodiment adopts Figure 1 The catalytic diesel hydroconversion process flow shown is illustrated in Table 1, and the properties of the catalytic diesel feedstock are listed below. Catalytic diesel is mixed with hydrogen and fed into a hydrorefining reactor for hydrorefining. The resulting hydrorefined feed stream is then separated into light and heavy feed streams at a cutting temperature of 220°C. The first heavy feed stream enters the hydrocracking reactor through the first inlet at the top, while the second heavy feed stream is recycled back to the hydrorefining reactor for further processing. The proportion of the first heavy feed stream to the total heavy feed stream (M...) is... h The hydrogen-to-oil volume ratio (V) in the hydrorefining reactor h In the initial stage of construction, adjustments are made dynamically, according to M. h =0.01×(0.0276h) 2 -2.05h+66), V h =0.46h 2The process was controlled at -10h + 930, with h being 33 and 29 days respectively. Light feedstock entered the hydrocracking reactor through the second inlet for hydroconversion. The catalyst volume between the first and second inlets accounted for 35% of the total catalyst loading volume of the reactor. The hydrorefining reactor was loaded with hydrorefining catalyst FF-56. The hydrocracking reactor was loaded with catalyst FC-90 in the region between the first and second inlets according to the liquid phase material flow direction, and catalyst FC-46 was loaded in the region between the second inlet and outlet. The reaction pressures of the hydrorefining reactor and the hydrocracking reactor were 9.5 MPa and 9.0 MPa, respectively, and the volume hourly space velocity (VHSV) of the hydrorefining reactor and the hydrocracking reactor were 1.1 h⁻¹. -1 1.0h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is to control the nitrogen content of the hydrorefining feed stream to 5 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 40%. The reaction results are shown in Table 1.

[0067] Example 5

[0068] This embodiment adopts Figure 1 The catalytic diesel hydroconversion process flow shown is illustrated in Table 1, and the properties of the catalytic diesel feedstock are listed below. Catalytic diesel and hydrogen are mixed and fed into a hydrorefining reactor for hydrorefining. The resulting hydrorefined feed stream is separated into light and heavy feed streams at a cutting temperature of 250°C. The first heavy feed stream enters the hydrocracking reactor through the first inlet at the top, while the second heavy feed stream is recycled back to the hydrorefining reactor for further processing. The first heavy feed stream accounts for 29% of the total heavy feed stream. The light feed stream enters the hydrocracking reactor through the second inlet for hydrogenation. The catalyst volume between the first and second inlets accounts for 50% of the total catalyst loading volume in the reactor. The hydrorefining reactor is loaded with FF-66 hydrorefining catalyst. The hydrocracking reactor is loaded with FC-90 catalyst in the region between the first and second inlets according to the liquid phase material flow direction, and with FC-46 catalyst in the region between the second inlet and the outlet. The hydrogen-to-oil volume ratio at the inlet of the hydrorefining reactor is 1100:1. The reaction pressures of the hydrorefining reactor and the hydrocracking reactor are 9.5 MPa and 9.0 MPa, respectively, and the volume hourly space velocity (VHSV) of the hydrorefining reactor and the hydrocracking reactor is 1.1 h⁻¹. -1 1.0h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is to control the nitrogen content of the hydrorefining feed stream to 5 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 40%. The reaction results are shown in Table 1.

[0069] Comparative Example 1

[0070] Comparative Example 1 uses the existing process flow, compared with Figure 1 Compared to the previous process flow, this method does not include a separator; the hydrorefined feedstock enters the hydrocracking reactor directly without separation. The properties of the catalytic diesel feedstock are shown in Table 1. The catalytic diesel is mixed with hydrogen and enters the hydrorefining reactor for the hydrorefining reaction. The resulting hydrorefined feedstock then enters the hydrocracking reactor for further reaction. The hydrogen-to-oil volume ratio (V / L) in the hydrorefining reactor is... h The adjustments are dynamic at the initial stage of construction, according to V. h =0.46h 2 The reaction time was controlled at -10h + 930, where h represents 30 days. The hydrorefining reactor was loaded with hydrorefining catalyst FF-66, and the hydrocracking reactor was FC-32. The reaction pressure in both the hydrorefining and hydrocracking reactors was 10.0 MPa, and the volume hourly space velocity (VHSV) was 0.8 h⁻¹. -1 1.8h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 8 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to regulate it according to a gasoline yield of 46%. The reaction results are shown in Table 1.

[0071] Comparative Example 2

[0072] Comparative Example 2 uses the existing process flow, and... Figure 1 Compared to the conventional process, this method eliminates the need for a separator, allowing the hydrorefined feedstock to directly enter the hydrocracking reactor for processing without separation. The properties of the catalytic diesel feedstock are shown in Table 1. The catalytic diesel is mixed with hydrogen and fed into the hydrorefining reactor for the hydrorefining reaction. The resulting hydrorefined feedstock then enters the hydrocracking reactor for further reaction. The hydrorefining reactor is loaded with the hydrorefining catalyst FHUDS-8, while the hydrocracking reactor is loaded with FC-46 and FC-90 catalysts sequentially according to the liquid phase flow direction, at a volume ratio of 65:35. The hydrogen-to-oil ratio at the inlet of the hydrorefining reactor is 1000:1. The reaction pressures in the hydrorefining and hydrocracking reactors are 12.0 MPa and 10.0 MPa, respectively, and their volume hourly space velocities are 0.9 h⁻¹. -1 1.2h -1 The principle for adjusting the reaction temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 10 ppm. The principle for adjusting the reaction temperature of the hydrocracking reactor is to adjust it according to a gasoline yield of 50%. The reaction results are shown in Table 1.

[0073] Table 2 Results of Examples and Comparative Examples

[0074]

[0075]

[0076] Comparative data shows that the method provided by this invention results in a higher gasoline octane rating at the initial stage of the process, while conventional processes typically require 30 days to adjust the gasoline octane rating to around 90. The scheme, combined with the catalyst activity temperature rule and process optimization, ensures that the gasoline octane rating is consistently higher than in conventional processes, while also improving the diesel cetane rating. Coupled with a reduction in the total temperature rise during refining, this provides enterprises with a safe, reliable, and economically efficient high-value-added catalytic diesel utilization technology solution.

Claims

1. A catalytic diesel hydroconversion method, comprising the following steps: (1) catalytic diesel and hydrogen gas are reacted under hydrofining reaction conditions in a hydrofining reaction unit, and a hydrofining stream is obtained after the reaction; (2) the hydrofining stream obtained in step (1) is separated in a separator to obtain a light stream and a heavy stream, wherein the operating temperature of the separator is 160-340°C, and is further preferably 200-280°C; (3) the heavy stream obtained in step (2) is reacted under hydrocracking reaction conditions in a hydrocracking reaction unit, and a hydrocracking stream is obtained after the reaction; (4) the hydrocracking stream obtained in step (3) is separated to obtain gas, gasoline and diesel.

2. Catalytic diesel hydroconversion process according to claim 1, characterized in that: The total aromatic content of the catalytic diesel in step (1) is higher than 70wt%, and is preferably 80wt%-90wt%.

3. Catalytic diesel hydroconversion process according to claim 1, characterized in that: The heavy stream obtained in step (2) is divided into two streams, wherein the first heavy stream is reacted in the hydrocracking reaction unit, and the second heavy stream is recycled to the hydrofining reaction unit and mixed with the catalytic diesel for treatment.

4. Catalytic diesel hydroconversion process according to claim 3, characterized in that: The proportion of the first heavy stream to the heavy stream is dynamically adjusted at the initial stage of the operation of the device, and the proportion of the first heavy stream to the heavy stream is dynamically adjusted according to a preset function with the time length (h) as the input parameter, starting from the time when the device is switched from the start-up oil to the catalytic diesel feedstock, wherein the preset function comprises: M h = 0.01 x (0.0276h 2 - 2.05h + 66); wherein the time length (h) is the time length from the current time to the time when the catalytic diesel feedstock is switched in, and the time length is taken as an integer value in days; the maximum value of the time length (h) is not greater than 35; and preferably, the value is any value between 28 and 34; and the proportion of the first heavy stream to the heavy stream is stopped adjusting when h reaches the maximum value.

5. The catalytic diesel hydroconversion process according to claim 1, characterized in that: The light stream obtained after separation in step (2) is treated in the hydrocracking reaction unit and enters the reactor through a second feed inlet, and the second feed inlet is arranged on the reactor shell; wherein the catalyst loading volume between the second feed inlet and the first feed inlet is 25%-80% of the total catalyst loading volume of the reactor, and is further preferably 35%-65%; the first feed inlet is arranged at the top or bottom of the reactor; and the heavy stream entering the hydrocracking reaction unit enters through the first feed inlet.

6. The catalytic diesel hydroconversion process according to claim 1, characterized in that: The hydrocracking reaction unit is loaded with a hydrocracking catalyst having a cracking function.

7. Catalytic diesel hydroconversion process according to claim 5, characterized in that: The hydrocracking reaction unit is provided with two catalyst beds, which are sequentially arranged in the liquid phase material flow direction as a first catalyst bed and a second catalyst bed; the first catalyst bed is arranged between the first feed inlet and the second feed inlet, and the second catalyst bed is arranged between the second feed inlet and the discharge outlet; and the hydrocracking catalyst A loaded in the first catalyst bed has a lower content of hydrogen metal components than the hydrocracking catalyst B loaded in the second catalyst bed, and the content of the hydrogen metal components in the hydrocracking catalyst B is 0-5wt% lower than that in the hydrocracking catalyst A based on the weight of the hydrocracking catalyst.

8. Catalytic diesel hydroconversion process according to claim 1, characterized in that: The hydrofining reaction conditions in step (1) are as follows: reaction temperature is 320-430°C, preferably 330-420°C; reaction pressure is 5-20 MPa, preferably 6-15 MPa; volume space velocity is 0.2-3.0 h -1 , preferably 0.6-1.2 h -1 .

9. The catalytic diesel hydroconversion process according to claim 1, characterized in that: The hydrocracking reaction conditions in step (3) are as follows: the reaction temperature is 330-430°C, preferably 350-420°C; the reaction pressure is 5-20 MPa, preferably 6-15 MPa; the volume space velocity is 0.2-3.0 h -1 , preferably 0.6-1.8 h -1 .

10. The catalytic diesel hydroconversion process according to claim 1, characterized in that: The hydrofining reaction pressure is 0.5-5.0 MPa higher than the hydrocracking reaction pressure, and is further preferably 1.0-2.0 MPa.

11. The catalytic diesel hydroconversion process according to claim 1, characterized in that: Taking the moment when the device is switched into catalytic diesel raw material from start-up oil as the starting point, taking the time length (h) as the input parameter, the hydrogen oil volume ratio of the hydrogenation refining reaction zone is dynamically adjusted according to a preset function, and the preset function includes: V h = 0.46h 2 -10h + 930; Wherein, the time length (h) is the time length from the current moment to the moment when the catalytic diesel raw material is switched in, and the time length is rounded to an integer value in days; the maximum value of the time length (h) is not greater than 35; preferably, the value is any value between 28 and 34; when h reaches the maximum value, the adjustment of the hydrogen oil volume ratio is stopped.

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