A hydrocracking method and system for processing high-drying point wax oil

Abstract

The present invention provides a hydrocracking method and system for processing high-drying point wax oil. The system includes a feedstock separation unit, a hydropretreatment unit, a first hydrocracking unit, a separation unit, a second hydrocracking unit, and a product separation unit. The method comprises the following steps: first, the high-drying point wax oil feedstock is cut to obtain a light wax oil feedstock and a heavy wax oil feedstock; the light wax oil feedstock sequentially enters the hydropretreatment unit and the first hydrocracking unit for reaction, and the first hydrocracking stream obtained after the reaction enters the separation unit for separation to obtain gas, light naphtha, heavy naphtha, and tail oil; the heavy wax oil feedstock and tail oil enter the second hydrocracking unit for reaction, and the second hydrocracking stream obtained after the reaction is cut into light and heavy components. The heavy second hydrocracking stream obtained is circulated to the hydropretreatment unit, and the light second hydrocracking stream is circulated back to the separation unit. The hydrocracking method provided by the present invention can improve the long-term operation stability of the high-drying point wax oil hydrocracking unit and the product yield of high-quality reforming feedstock represented by heavy naphtha.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry and relates to a hydrocracking method, in particular to a hydrocracking method using high-drying point wax oil as raw material. Background Art

[0002] The hydrocracking process can handle a wide range of feedstocks, but each has specific limitations. For example, when processing wax oil feedstocks, the dry point is limited, often to no higher than 530°C. However, due to the increasing heaviness of petrochemical feedstocks and the competitive nature of companies striving for economic returns, deep drawing technology is being used to expand the processing capacity of wax oil feedstocks. Wax oils that have undergone deep drawing are known as high-dry-point wax oils, and their processing is significantly more difficult than conventional wax oils. The dry point of feedstocks processed by traditional hydrocracking processes is generally less than 530°C. Deep drawing significantly increases the dry point of the feedstock, leading to significant increases in nitrogen, sulfur, asphaltenes, residual carbon, and trace metal impurities.

[0003] The key to developing hydrocracking technology for deep-drawn wax oil with high drying point is to solve the problem of difficulty in processing due to the significant deterioration of the properties of deep-drawn wax oil in the atmospheric and vacuum unit. After deep-drawing of wax oil, a series of requirements are put forward for hydrocracking catalysts and hydrocracking technology. For catalysts, the denitrification performance of refined catalysts must be better, and the cracking catalysts must have larger pore sizes to accommodate large molecules and have better selectivity. The processing of high-drying point wax oil raw materials has always troubled workers in the petrochemical industry. The hydrocracking process can produce high-value-added chemical raw materials such as heavy naphtha fractions through a series of reactions such as ring opening and chain scission. However, the high nitrogen content and aromatic content of high-drying point wax oil raw materials have become a technical bottleneck to a certain extent that limits the long-term stable operation of the unit. In particular, the processing severity of the hydrocracking pretreatment section is high, and the reaction temperature needs to be continuously increased to supplement the activity.

[0004] CN104611010A discloses a hydrocracking method for high-drying-point feedstocks. This method employs three reaction zones: the first zone performs hydrofining, the second zone employs both gas-liquid cocurrent and countercurrent flow for deep refining, and the third zone performs hydrocracking. This method improves the overall denitrification capacity of the device, but primarily achieves this through the addition of reactors, leaving room for further improvement in its technical and economical efficiency.

[0005] CN107345156A discloses a hydrocracking method suitable for processing high-drying point wax oil raw materials. The method is characterized in that the hydrocracking catalyst used uses a modified Y-type molecular sieve, amorphous silica-alumina and alumina as a carrier, wherein the modified Y-type molecular sieve is a Y-type molecular sieve rich in mesopores and with a concentrated effective pore distribution, and the mesopore volume accounts for more than 70% of the total volume.

[0006] CN101987967A discloses a method for hydrogenating vacuum deep-pulled wax oil. The deep-pulled wax oil is mixed with hydrogen and passes through two hydrogenation reaction zones in succession. The first hydrogenation reaction zone is loaded with a hydrogenation protective agent and a hydrodemetallization and deasphalting catalyst, and the second hydrogenation reaction zone is loaded with a hydrodesulfurization catalyst and a denitrification catalyst. Summary of the Invention

[0007] High-drying-point wax oil feedstocks have high nitrogen content and are difficult to process, requiring the hydrorefining stage to operate under highly severe conditions, resulting in short plant operating cycles. The primary objective of the present invention is to provide a hydrocracking method and system for processing high-drying-point wax oils. The hydrocracking method provided by the present invention can improve the long-term operating stability of high-drying-point wax oil hydrocracking units and the product yield of high-quality reforming feedstocks, such as heavy naphtha.

[0008] In order to address the deficiencies of the prior art, the present invention provides a hydrocracking method for processing high-drying point wax oil, comprising the following steps:

[0009] (1) Cutting the high-drying point wax oil raw material into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material;

[0010] (2) The light wax oil feedstock enters the hydrogenation pretreatment unit and the first hydrocracking unit in sequence, reacts in the presence of hydrogen and a catalyst, and obtains a first hydrocracking stream after the reaction;

[0011] (3) The first hydrocracking stream enters the separation unit and is separated to obtain gas, light naphtha, heavy naphtha and tail oil;

[0012] (4) The heavy wax oil feedstock and tail oil enter the second hydrocracking unit and react in the presence of hydrogen and a hydrocracking catalyst to obtain a second hydrocracking stream;

[0013] (5) The second hydrocracking stream is cut into light and heavy components, and the obtained heavy second hydrocracking stream is circulated to the hydrogenation pretreatment unit, and the light second hydrocracking stream is circulated back to the separation unit.

[0014] Another aspect of the present invention provides a hydrocracking system for processing high-drying point wax oil, comprising a feed separation unit, a hydrogenation pretreatment unit, a first hydrocracking unit, a separation unit, a second hydrocracking unit, and a product separation unit, wherein

[0015] A raw material separation unit is used to receive and separate the high-drying point wax oil raw material into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material;

[0016] A hydrogenation pretreatment unit is used to receive the light wax oil feedstock and hydrogen from the feedstock separation unit and obtain a hydrogenation pretreatment stream after reaction;

[0017] A first hydrocracking unit is configured to receive the hydropretreatment stream and hydrogen obtained after the reaction in the hydropretreatment unit, and obtain a first hydrocracking stream after the reaction;

[0018] A separation unit is used to receive the first hydrocracking stream obtained after the reaction in the first hydrocracking unit, and obtain gas, light naphtha, heavy naphtha and tail oil after separation;

[0019] a second hydrocracking unit, which is used to receive the tail oil from the separation unit, the heavy wax oil feedstock from the feedstock separation unit, and optionally the light naphtha from the separation unit, and obtain a second hydrocracking stream after reaction;

[0020] The product separation unit is used to receive and cut the second hydrocracking stream from the second hydrocracking unit into light and heavy components to obtain a light second hydrocracking stream and a heavy second hydrocracking stream; the obtained heavy second hydrocracking stream is circulated to the hydrogenation pretreatment unit through a pipeline, and the light second hydrocracking stream is circulated to the separation unit through a pipeline.

[0021] Compared with the prior art, the hydrocracking method and system for processing high-drying point wax oil provided by the present invention have the following technical effects:

[0022] In the hydrocracking method and system for processing high-drying point wax oil provided by the present invention, the dry high-drying point wax oil raw material is first cut into light and heavy components, and the light wax oil raw material is processed in sequence through the hydropretreatment, the first hydrocracking unit and the second hydrocracking unit, while the heavy wax oil raw material preferably first enters the middle and lower part of the second hydrocracking unit, is processed by the provided hydrorefining catalyst bed and the hydrocracking catalyst bed B, and is again cut into light and heavy components through the product separation unit, and the heavy second hydrocracking material flow is circulated through the pipeline to the hydropretreatment unit, which greatly alleviates the processing difficulty of the hydropretreatment unit and helps to extend the operation cycle of the device. It solves the problem that the conventional process method solves the problem that the high-drying point wax oil raw material has a high nitrogen content and is difficult to remove, and the hydropretreatment process must be operated under more severe operating conditions, and the reaction temperature needs to be continuously increased for temperature compensation, thereby shortening the operation cycle of the device, and the temperature of the material at the outlet of the hydropretreatment reactor is too high and does not match the operating temperature required by the hydrocracking reactor.

[0023] In the hydrocracking method and system for processing high-drying point wax oil provided by the present invention, a hydrorefining catalyst bed is provided in the second hydrocracking unit, which can partially saturate the polycyclic aromatic hydrocarbons in the second-stage reactor with aromatic hydrocarbons, thereby solving the problem of polycyclic aromatic hydrocarbon accumulation in the traditional two-stage full-circulation hydrocracking process. At the same time, it can also improve the selectivity of heavy naphtha, achieving two major positive improvements: preventing the accumulation of polycyclic aromatic hydrocarbons and improving the selectivity of heavy naphtha.

[0024] The applicant discovered that the hydrocracking reaction exhibits a dynamic inhibition-directed phenomenon within the cracking reaction zone. Specifically, during the hydrocracking process of a full-fraction reactant, the introduction of materials with a distillation range of A to B°C promotes the reaction of materials with a distillation range of <B°C, while inhibiting the reaction of materials with a distillation range of >B°C. Based on these experiments, the applicant discovered that by optimizing the functional regions and hydrocracking reaction pathways of the second hydrocracking unit, the selectivity of the target product was significantly improved while extending the unit's operating cycle. Light naphtha was introduced into the second hydrocracking unit through the third feed port below the hydrorefining catalyst bed, allowing the light cycle oil to bypass the hydrorefining catalyst bed. Heavy wax oil feedstock was introduced through the first feed port at the top, creating a high concentration zone of light naphtha and heavy fraction reactants within the reactor region below the hydrorefining catalyst bed. This promoted the reaction of heavy fraction reactants toward heavy naphtha, reduced the tendency of the heavy naphtha fraction to react toward the light naphtha fraction, and further increased the selectivity of the heavy naphtha product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the hydrocracking method for processing high drying point wax oil in an embodiment of the present invention.

[0026] Among them, 1-high drying point wax oil feedstock; 2-light wax oil feedstock; 3-heavy wax oil feedstock; 4-hydrogenation pretreatment unit; 5-hydrogenation pretreatment stream; 6-first hydrocracking unit; 7-first hydrocracking stream; 8-gas-liquid separator; 9-gas phase stream; 10-liquid phase stream; 11-fractionation unit; 12-gas; 13-light naphtha; 14-heavy naphtha; 15-tail oil; 16-second hydrocracking unit; 17-second hydrocracking stream; 18-product separation unit; 19-heavy second hydrocracking stream; 20-light second hydrocracking stream; 21-circulating hydrogen compressor; 22-circulating hydrogen; 23-new hydrogen; 24-feedstock separation unit; 25-hydrocracking catalyst bed A; 26-hydrorefining catalyst bed; 27-hydrocracking catalyst bed B.

[0027] Figure 2 Schematic diagram of the hydrocracking method for processing high drying point wax oil in a comparative example of the present invention.

[0028] Among them, 1-high drying point wax oil feedstock; 2-hydrogenation pretreatment unit; 3-hydrogenation pretreatment stream; 4-first hydrocracking unit; 5-gas-liquid separator; 6-liquid phase stream; 7-fractionation unit; 8-gas; 9-light naphtha; 10-heavy naphtha; 11-tail oil; 12-second hydrocracking unit; 13-second hydrocracking stream; 14-gas phase stream; 15-circulating hydrogen compressor; 16-first hydrocracking stream; 17-circulating hydrogen; 18-new hydrogen. DETAILED DESCRIPTION

[0029] The technical solutions and technical effects of the present invention are further described below with reference to the accompanying drawings and specific implementations.

[0030] Unless expressly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising” will be understood to include the stated elements or components but not to exclude other elements or components.

[0031] In this document, for ease of description, spatially relative terms such as "below," "beneath," "below," "above," "above," etc. may be used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that the spatially relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the drawings. For example, if the object in the drawings is turned over, the element described as being "below" or "beneath" other elements or features will be oriented "above" the elements or features. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatially relative terms used herein should be interpreted accordingly.

[0032] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit specific positions or relative relationships. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable with each other.

[0033]

[0046] All numerical values ​​for parameters (eg, amounts or conditions) herein are to be understood as being modified in all instances by the term "about," whether or not "about" actually precedes the numerical value.

[0034] In order to address the deficiencies of the prior art, the present invention provides a hydrocracking method for processing high-drying point wax oil, comprising the following steps:

[0035] (1) Cutting the high-drying point wax oil raw material into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material;

[0036] (2) The light wax oil feedstock enters the hydrogenation pretreatment unit and the first hydrocracking unit in sequence, reacts in the presence of hydrogen and a catalyst, and obtains a first hydrocracking stream after the reaction;

[0037] (3) The first hydrocracking stream enters the separation unit and is separated to obtain gas, light naphtha, heavy naphtha and tail oil;

[0038] (4) The heavy wax oil feedstock and tail oil enter the second hydrocracking unit and react in the presence of hydrogen and a hydrocracking catalyst to obtain a second hydrocracking stream;

[0039] (5) The second hydrocracking stream is cut into light and heavy components, and the obtained heavy second hydrocracking stream is circulated to the hydrogenation pretreatment unit, and the light second hydrocracking stream is circulated back to the separation unit.

[0040] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the distillation range of the high-drying point wax oil raw material is generally 280°C to 600°C, and the final distillation point is preferably 550°C to 600°C. There is no special restriction on the sulfur and nitrogen content. Under normal circumstances, the sulfur content is not more than 3.0wt% and the nitrogen content is greater than 3000ppm.

[0041] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the splitting temperature for cutting the high-drying point wax oil raw material into light and heavy components in step (1) is 520-590°C, preferably 540-580°C.

[0042] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the reactor of the second hydrocracking unit includes, in the direction of liquid material flow, a hydrocracking catalyst bed A, a hydrocracking catalyst bed B, and a hydrorefining catalyst bed disposed between the hydrocracking catalyst bed A and the hydrocracking catalyst bed B; wherein the volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 5% to 30%, preferably 8% to 18%; and the bottom position of the hydrorefining catalyst bed is located at 20% to 90%, more preferably 35% to 75%, of the height (from top to bottom) of the reactor in the second hydrocracking unit.

[0043] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the tail oil enters the second hydrocracking unit through the first feed port at the top of the reactor in the second hydrocracking unit.

[0044] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the heavy wax oil feedstock enters the second hydrocracking unit through a second feed port provided on the side wall of the reactor shell between the hydrocracking catalyst bed A and the hydrorefining catalyst bed.

[0045] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the light naphtha may partially or entirely enter the second hydrocracking unit for processing. When entering the second hydrocracking unit, it preferably enters the second hydrocracking unit through a third feed port on the sidewall of the reactor shell between the hydrorefining catalyst bed and the hydrocracking catalyst bed B. Furthermore, when the light naphtha partially enters the second hydrocracking unit, the amount of light naphtha entering the second hydrocracking unit is 10% to 85% (wt), preferably 15% to 75% (wt), of the light naphtha product.

[0046] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the splitting temperature for cutting the light and heavy components of the second hydrocracking material stream is 510-580°C, and the splitting temperature for cutting the light and heavy components of the second hydrocracking material stream is 0-30°C lower than the splitting temperature for cutting the light and heavy components of the high-drying point wax oil feedstock, preferably 5-20°C.

[0047] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the specific process of the first hydrocracking stream entering the separation unit in step (3) to obtain gas, light naphtha, heavy naphtha and tail oil after separation is as follows: the first hydrocracking stream is first subjected to gas-liquid separation to obtain a gas phase stream and a liquid phase stream after separation; the obtained gas phase stream is further purified (purification generally refers to the removal of sulfur-containing compounds (hydrogen sulfide) in the gas phase stream, and the purification can adopt any of the existing hydrogen sulfide removal processes) and compressed by a circulating hydrogen compressor to obtain hydrogen, which can be circulated back to the hydrogenation pretreatment unit, the first hydrocracking unit, and the second hydrocracking unit for use as circulating hydrogen.

[0048] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the operating conditions of the hydrotreating pretreatment unit include:

[0049] The reaction pressure is 8.0-20.0 MPa, the reaction temperature is 340-430°C, and the volume space velocity is 0.2-10.0 h -1 , hydrogen to oil volume ratio is 100 to 3000;

[0050] Preferably, the reaction pressure is 15.0-18.0 MPa, the reaction temperature is 370-425°C, and the volume space velocity is 0.8-2.0 h -1 , the hydrogen-to-oil volume ratio is 800-2000.

[0051] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the operating conditions of the first hydrocracking unit include:

[0052] The reaction pressure is 8.0-20.0 MPa, the reaction temperature is 330-425°C, and the volume space velocity is 0.6-8.0h -1 , hydrogen to oil volume ratio is 100 to 2500;

[0053] Preferably, the reaction pressure is 15.0-18.0 MPa, the reaction temperature is 360-410°C, and the volume space velocity is 0.8-2.0 h -1 , the hydrogen-to-oil volume ratio is 600-2200.

[0054] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the operating conditions of the second hydrocracking unit include:

[0055] The reaction pressure is 8.0-18.0 MPa, the reaction temperature is 320-410°C, and the volume space velocity is 0.6-8.0 h -1 , hydrogen to oil volume ratio is 500~2500;

[0056] Preferably, the reaction pressure is 12.0-18.0 MPa, the reaction temperature is 340-390°C, and the volume space velocity is 1.0-2.5 h -1 , the hydrogen-to-oil volume ratio is 600-2200.

[0057] Furthermore, in the hydrocracking method for processing high-drying point wax oil, unless otherwise specified, the pressures described herein all represent gauge pressures.

[0058] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the hydrocracking pretreatment unit is loaded with at least one hydrocracking pretreatment catalyst, preferably comprising one to three hydrocracking pretreatment catalysts. The hydrocracking pretreatment catalyst can be a commercially available catalyst or prepared according to existing methods. When a commercially available hydrocracking catalyst is selected, specifically, commercial hydrocracking catalysts such as FF-12, FF-56, FF-66, and FHUDS-8 developed by the Dalian (Fushun) Petrochemical Research Institute of Sinopec can be selected.

[0059] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the first hydrocracking unit is loaded with at least one hydrocracking catalyst. The hydrocracking catalyst can be a commercially available hydrocracking catalyst or prepared according to existing methods. When a commercially available hydrocracking catalyst is selected, specific examples include commercial hydrocracking catalysts such as FC-52 and FC-32 (developed by Dalian (Fushun) Research Institute of Petrochemicals (FRIPP) of Sinopec).

[0060] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the hydrocracking catalyst bed A in the second hydrocracking unit is loaded with at least one hydrocracking catalyst. The hydrocracking catalyst can be a commercially available hydrocracking catalyst or prepared according to existing methods. When a commercially available hydrocracking catalyst is selected, specific examples include commercial hydrocracking catalysts such as FC-76 and FC-50 (developed by Dalian (Fushun) Research Institute of Petrochemicals (FRIPP) of Sinopec).

[0061] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the hydrocracking catalyst bed B in the second hydrocracking unit is loaded with at least one hydrocracking catalyst. The hydrocracking catalyst can be a commercially available hydrocracking catalyst or prepared according to existing methods. When a commercially available hydrocracking catalyst is selected, commercial hydrocracking catalysts such as FC-38 and FC-14 (developed by Dalian (Fushun) Research Institute of Petrochemicals (FRIPP) of Sinopec Corporation) can be specifically selected.

[0062] Furthermore, in the hydrocracking method for processing high-drying point wax oil, the hydrorefining catalyst bed in the second hydrocracking unit is loaded with at least one hydrorefining catalyst. This hydrorefining catalyst may be the same as or different from the hydrocracking pretreatment catalyst used in the hydropretreatment unit. It may be a commercially available catalyst or prepared according to existing methods. Specifically, commercial hydrorefining catalysts such as FF-56, FF-66, FHUDS-7, FHUDS-8, and FTX developed by Dalian (Fushun) Research Institute of Petrochemicals (FRIPP) of Sinopec Corporation may be used.

[0063] Another aspect of the present invention provides a hydrocracking system for processing high-drying point wax oil, comprising a feed separation unit, a hydrogenation pretreatment unit, a first hydrocracking unit, a separation unit, a second hydrocracking unit, and a product separation unit, wherein

[0064] A raw material separation unit is used to receive and separate the high-drying point wax oil raw material into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material;

[0065] A hydrogenation pretreatment unit is used to receive the light wax oil feedstock and hydrogen from the feedstock separation unit and obtain a hydrogenation pretreatment stream after reaction;

[0066] A first hydrocracking unit is configured to receive the hydropretreatment stream and hydrogen obtained after the reaction in the hydropretreatment unit, and obtain a first hydrocracking stream after the reaction;

[0067] A separation unit is used to receive the first hydrocracking stream obtained after the reaction in the first hydrocracking unit, and obtain gas, light naphtha, heavy naphtha and tail oil after separation;

[0068] a second hydrocracking unit, which is used to receive the tail oil from the separation unit, the heavy wax oil feedstock from the feedstock separation unit, and optionally the light naphtha from the separation unit, and obtain a second hydrocracking stream after reaction;

[0069] The product separation unit is used to receive and cut the second hydrocracking stream from the second hydrocracking unit into light and heavy components to obtain a light second hydrocracking stream and a heavy second hydrocracking stream; the obtained heavy second hydrocracking stream is circulated to the hydrogenation pretreatment unit through a pipeline, and the light second hydrocracking stream is circulated to the separation unit through a pipeline.

[0070] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the reactor in the second hydrocracking unit includes, in the direction of liquid material flow, a hydrocracking catalyst bed A, a hydrocracking catalyst bed B, and a hydrorefining catalyst bed disposed between the hydrocracking catalyst bed A and the hydrocracking catalyst bed B; wherein the volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 5% to 30%, preferably 8% to 18%; and the bottom position of the hydrorefining catalyst bed is located at 20% to 90%, more preferably 35% to 75%, of the height (from top to bottom) of the reactor in the second hydrocracking unit.

[0071] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the reactor in the second hydrocracking unit includes a first feed port, a second feed port, and a discharge port; wherein the first feed port is located at the top of the reactor, and the tail oil enters the second hydrocracking unit through the first feed port; the second feed port is arranged on the side wall of the reactor shell between the hydrocracking catalyst bed A and the hydrorefining catalyst bed, and the heavy wax oil feedstock enters the second hydrocracking unit through the second feed port.

[0072] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the reactor in the second hydrocracking unit also includes a third feed port, which is arranged on the side wall of the reactor shell between the hydrorefining catalyst bed and the hydrocracking catalyst bed B. When the light naphtha is circulated to the second hydrocracking unit for processing, it enters the second hydrocracking unit through the third feed port.

[0073] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the raw material separation unit may be a device that can separate the materials according to their different distillation ranges, such as a fractionating tower.

[0074] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the product separation unit may be a device that can separate materials according to their different distillation ranges, such as a fractionating tower.

[0075] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the separation unit includes a gas-liquid separator and a distillation tower. Depending on actual needs, the gas-liquid separator generally includes but is not limited to a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, and a cold low-pressure separator; the connection method between the separators and between the separator and the distillation tower can adopt the existing connection method in the field, and those skilled in the art can freely choose according to actual needs.

[0076] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the hydrotreating pretreatment unit is provided with at least one reactor. When two or more reactors are provided, the reactors can be connected in parallel and / or in series; preferably, they are connected in series. The reactor can be at least one of a fixed bed hydrogenation reactor, a suspended bed hydrogenation reactor, and a fluidized bed hydrogenation reactor.

[0077] Furthermore, in the hydrocracking system for processing high-drying point wax oil, the first hydrocracking unit and the second hydrocracking unit are each equipped with at least one reactor. When two or more reactors are provided, the reactors may be connected in parallel and / or in series; preferably, they are connected in series. The reactor may be at least one of a fixed-bed hydrogenation reactor, a suspended-bed hydrogenation reactor, and a fluidized-bed hydrogenation reactor, preferably a fixed-bed reactor.

[0078] the following Figure 1 The specific implementation methods of the process and system provided by the present invention are further described as follows. Figure 1As shown, the hydrocracking method for processing high-drying point wax oil provided by the present invention proceeds as follows: a high-drying point wax oil feedstock 1 enters a feedstock separation unit 24 for separation of light and heavy components, producing a light wax oil feedstock 2 and a heavy wax oil feedstock 3. In the presence of fresh hydrogen 23, the light wax oil feedstock 2 is mixed with recycled hydrogen 22 and then enters a hydropretreatment unit 4 for reaction. The resulting hydropretreated stream 5 enters a first hydrocracking unit 6 for reaction in the presence of hydrogen and a catalyst, yielding a first hydrocracked stream 7. This stream enters a gas-liquid separator 8 for gas-liquid separation, yielding a gas stream 9 and a liquid stream 10. The gas stream 9 is compressed by a circulating hydrogen compressor 21 and recycled as circulating hydrogen 22 back into the reaction system (which can be the hydropretreatment unit, the first hydrocracking unit, or the second hydrocracking unit). The liquid stream 10 enters a fractionation unit 11 for separation, yielding gas 12, light naphtha 13, heavy naphtha 14, and tail oil 15. The heavy wax oil feedstock 3 and the tail oil 15 enter the second hydrocracking unit 16 through different feed ports. According to the flow direction of the liquid phase material, the reactor in the second hydrocracking unit 16 includes a hydrocracking catalyst bed A25, a hydrocracking catalyst bed B27, and a hydrorefining catalyst bed 26 arranged between the hydrocracking catalyst bed A25 and the hydrocracking catalyst bed B27; the reactor in the second hydrocracking unit 16 includes a first feed port, a second feed port, a third feed port and a discharge port; wherein the first feed port is located at the top of the reactor, and the tail oil 15 enters the second hydrocracking unit 16 through the first feed port, and the second feed port is arranged on the side wall of the reactor shell between the hydrocracking catalyst bed A25 and the hydrorefining catalyst bed 26. The light wax oil feedstock 3 enters the second hydrocracking unit 16 through the second feed port, and the third feed port is arranged on the side wall of the reactor shell between the hydrorefining catalyst bed 26 and the hydrocracking catalyst bed B27. When the light naphtha 13 is circulated to the second hydrocracking unit 16 for treatment, it enters the second hydrocracking unit 16 through the third feed port; the second hydrocracking stream 17 obtained after the reaction in the second hydrocracking unit enters the product separation unit 18 for cutting light and heavy components to obtain a light second hydrocracking stream 20 and a heavy second hydrocracking stream 19; the obtained heavy second hydrocracking stream 19 is circulated to the hydrogenation pretreatment unit 4 through a pipeline for treatment, and the light second hydrocracking stream 20 is circulated to the gas-liquid separator 8 in the separation unit through a pipeline for treatment.

[0079] Detailed properties of the high-drying point wax oil feedstock used in the Examples and Comparative Examples of the present invention are shown in Table 1. In the Examples and Comparative Examples of the present invention, the hydropretreatment unit includes one hydropretreatment reactor, and the first hydrocracking unit and the second hydrocracking unit each include one hydrocracking reactor, which are respectively designated as the first hydrocracking reactor and the second hydrocracking reactor.

[0080] Table 1 Properties of high drying point wax oil raw materials

[0081]

[0082] Example 1

[0083] use Figure 1 The hydrocracking method for processing high-drying point wax oil is shown in Table 1. The hydropretreatment reactor is loaded with FF-66 catalyst, the first hydrocracking reactor is loaded with FC-52 catalyst, and the upper hydrocracking catalyst A in the second hydrocracking reactor is FC-32, the hydrofining catalyst is FF-66, and the lower hydrocracking catalyst B is FC-28. The hydrofining catalyst in the second hydrocracking reactor accounts for 18% of the volume, and the bottom of the hydrofining catalyst bed is located at 70% of the height of the second hydrocracking reactor (from top to bottom). The light-heavy split temperature of the high-drying point wax oil feedstock is 560°C, and the light-heavy split temperature of the second hydrocracking stream is 550°C. The amount of light naphtha recycled is 30% by weight of the light naphtha product. The operating conditions of the hydropretreatment reactor are as follows: reaction pressure of 18.0 MPa, reaction temperature of 380°C, and volumetric space velocity of 1.0 h / min. -1 The hydrogen-to-oil volume ratio is 1800. The reaction conditions of the first hydrocracking reactor are as follows: reaction pressure 18.0 MPa, reaction temperature 380 ° C, volume space velocity 1.5h -1 The reaction conditions of the second hydrocracking reactor are as follows: reaction pressure of 18.0 MPa, reaction temperature of 360 ° C, volume space velocity of 2.0 h -1 , the volume ratio of hydrogen to oil was 1500. The reaction results are shown in Table 2.

[0084] Example 2

[0085] use Figure 1The hydrocracking method for processing high-drying point wax oil is shown in Table 1. The hydropretreatment reactor is loaded with graded FF-36 / FF-66 catalysts, the first hydrocracking reactor is loaded with FC-24 catalyst, and the upper hydrocracking catalyst A in the second hydrocracking reactor is FC-76, the hydrofining catalyst is FUDS-8, and the lower hydrocracking catalyst B is FC-14. The hydrofining catalyst in the second hydrocracking reactor accounts for 12% of the volume, and the bottom of the hydrofining catalyst bed is located at 50% of the height of the second hydrocracking reactor (from top to bottom). The light / heavy split temperature of the high-drying point wax oil feedstock is 540°C, and the light / heavy split temperature of the second hydrocracking stream is 535°C. The light naphtha recycles 50% of the light naphtha product. The operating conditions of the hydrogenation pretreatment reactor are as follows: reaction pressure of 15.0 MPa, reaction temperature of 420 °C, volume space velocity of 1.8 h -1 The hydrogen-to-oil volume ratio is 1600. The operating conditions of the first hydrocracking reactor are as follows: reaction pressure is 15.0 MPa, reaction temperature is 400 ° C, volume space velocity is 1.0 h -1 The operating conditions of the second hydrocracking reactor are as follows: reaction pressure 15.0 MPa, reaction temperature 380 ° C, volume space velocity 1.5 h -1 , the volume ratio of hydrogen to oil was 2000. The reaction results are shown in Table 2.

[0086] Example 3

[0087] use Figure 1 The hydrocracking method for processing high-drying point wax oil is shown in Table 1. The hydropretreatment reactor is loaded with FF-56 catalyst, the first hydrocracking reactor is loaded with FC-70 catalyst, and the upper hydrocracking catalyst A in the second hydrocracking reactor is FC-80, the hydrofining catalyst is FTX, and the lower hydrocracking catalyst B is FC-28. The hydrofining catalyst in the second hydrocracking reactor accounts for 16% of the volume, and the bottom of the hydrofining catalyst bed is located at 75% of the height of the second hydrocracking reactor (from top to bottom). The light-heavy split temperature of the high-drying point wax oil feedstock is 575°C, and the light-heavy split temperature of the second hydrocracking stream is 555°C. The light naphtha recycle amount is 70% by weight of the light naphtha product. The operating conditions of the hydropretreatment reactor are as follows: reaction pressure of 17.0 MPa, reaction temperature of 400°C, and volumetric space velocity of 1.2 h / min. -1 The operating conditions of the first hydrocracking reactor are as follows: reaction pressure 17.0 MPa, reaction temperature 360 ​​° C, volume space velocity 2.0 h -1The operating conditions of the second hydrocracking reactor are as follows: reaction pressure 17.0 MPa, reaction temperature 350 °C, volume space velocity 1.0 h -1 , the volume ratio of hydrogen to oil was 2000. The reaction results are shown in Table 2.

[0088] Comparative Example 1

[0089] use Figure 2 The illustrated two-stage hydrocracking method for wax oil has the following specific process: a high-drying point wax oil feedstock 1 is mixed and introduced into a hydropretreatment unit 2 in the presence of fresh hydrogen 18 for reaction. The resulting hydropretreatment stream 3 enters a first hydrocracking unit 4 for reaction in the presence of hydrogen and a catalyst. The resulting hydrocracked stream 16 enters a gas-liquid separator 5 for gas-liquid separation, yielding a gas stream 14 and a liquid stream 6. The gas stream 14 is compressed by a circulating hydrogen compressor 15 and recycled as circulating hydrogen 17 back to the reaction system (which may be the hydropretreatment unit, the first hydrocracking unit, or the second hydrocracking unit). The liquid stream 6 enters a fractionation unit 7 for separation, yielding gas 8, light naphtha 9, heavy naphtha 10, and tail oil 11. The tail oil 11 enters a second hydrocracking unit through the reactor's top feed port. The second hydrocracking stream 13 obtained after the reaction in the second hydrocracking unit is circulated via a pipeline to the gas-liquid separator 5 in the separation unit for further processing.

[0090] The properties of the processed wax oil feedstock are shown in Table 1. The hydrotreating pretreatment reactor was loaded with FF-66 catalyst, the first hydrocracking reactor was loaded with FC-52 catalyst, and the hydrocracking catalyst in the second hydrocracking reactor was FC-52 catalyst. The operating conditions of the hydrotreating pretreatment reactor were as follows: reaction pressure of 18.0 MPa, reaction temperature of 380°C, volume space velocity of 1.0 h -1 The hydrogen-to-oil volume ratio is 1800. The operating conditions of the first hydrocracking reactor are as follows: reaction pressure 18.0 MPa, reaction temperature 380 ° C, volume space velocity 1.5 h -1 The operating conditions of the second hydrocracking reactor are as follows: reaction pressure of 18.0 MPa, reaction temperature of 360 °C, volume space velocity of 2.0 h -1 , the volume ratio of hydrogen to oil was 1500. The reaction results are shown in Table 2.

[0091] Comparative Example 2

[0092] use Figure 1The wax oil two-stage hydrocracking method shown in Table 1 has the properties of the processed wax oil feedstock. Unlike the embodiment, no hydrorefining catalyst bed is set in the second hydrocracking reactor, and no hydrorefining catalyst is loaded. The hydropretreatment reactor is loaded with FF-36 / FF-66 catalysts in a graded manner, the first hydrocracking reactor is loaded with FC-24 catalyst, and the second hydrocracking reactor is loaded with FC-76 catalyst. The light-heavy component splitting temperature of the high-drying point wax oil feedstock is 540°C, and the light-heavy component splitting temperature of the second hydrocracking stream is 535°C. The amount of light naphtha recycled is 50wt% of the light naphtha product. The operating conditions of the hydropretreatment reactor are as follows: reaction pressure of 15.0MPa, reaction temperature of 420°C, volume space velocity of 1.8h -1 The hydrogen-to-oil volume ratio is 1600. The operating conditions of the first hydrocracking reactor are as follows: reaction pressure of 15.0 MPa, reaction temperature of 400 °C, volume space velocity of 1.0 h -1 The operating conditions of the second hydrocracking reactor are as follows: reaction pressure of 15.0 MPa, reaction temperature of 380 ° C, volume space velocity of 1.5 h -1 , the volume ratio of hydrogen to oil was 2000. The reaction results are shown in Table 2.

[0093] Comparative Example 3

[0094] use Figure 2 The two-stage hydrocracking method for wax oil shown in the figure uses FF-56 catalyst in the hydropretreatment reactor and FC-70 catalyst in the first hydrocracking reactor. In the second hydrocracking reactor, the upper hydrocracking catalyst A is FC-80, the hydrofining catalyst is FTX, and the lower hydrocracking catalyst B is FC-28. The hydrofining catalyst in the second hydrocracking reactor accounts for 16% of the volume, and the bottom of the hydrofining catalyst bed is located at 75% of the height of the second hydrocracking reactor (from top to bottom). The operating conditions of the hydropretreatment reactor are as follows: reaction pressure of 17.0 MPa, reaction temperature of 400°C, and volume space velocity of 1.2 h / min. -1 The operating conditions of the first hydrocracking reactor are as follows: reaction pressure 17.0 MPa, reaction temperature 360 ​​° C, volume space velocity 2.0 h -1 The operating conditions of the second hydrocracking reactor are as follows: reaction pressure 17.0 MPa, reaction temperature 350 °C, volume space velocity 1.0 h -1 , the volume ratio of hydrogen to oil was 2000. The reaction results are shown in Table 2.

[0095] Table 2 Results of Examples and Comparative Examples

[0096]

[0097] The experimental results of the above examples and comparative examples demonstrate that the hydrocracking method for processing high-drying-point wax oils significantly increases the yield of heavy naphtha and improves the octane rating of light naphtha. It also addresses the issues of aromatics accumulation in the circulating oil and insufficient hydrodenitrogenation capacity during long-term operation of two-stage hydrocracking. Under the general trend of "oil conversion," this method will help refineries improve quality and efficiency, bringing significant economic benefits to refineries.

Claims

1. A hydrocracking method for processing high-drying point wax oil, comprising the following steps: (1) The high-drying point wax oil raw material is cut into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material, and the cutting temperature of the light and heavy components is 520-590°C; the distillation range of the high-drying point wax oil raw material is 280-600°C, and the final distillation point is 550-600°C; (2) The light wax oil feedstock enters the hydrogenation pretreatment unit and the first hydrocracking unit in sequence, reacts in the presence of hydrogen and a catalyst, and obtains a first hydrocracking stream after the reaction; (3) The first hydrocracking stream enters the separation unit and is separated to obtain gas, light naphtha, heavy naphtha and tail oil; (4) The heavy wax oil feedstock and tail oil enter the second hydrocracking unit and react in the presence of hydrogen and a hydrocracking catalyst to obtain a second hydrocracking stream. According to the flow direction of the liquid phase material, the reactor of the second hydrocracking unit includes a hydrocracking catalyst bed A, a hydrocracking catalyst bed B, and a hydrorefining catalyst bed disposed between the hydrocracking catalyst bed A and the hydrocracking catalyst bed B; the volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 5% to 30%, and the bottom position of the hydrorefining catalyst bed is located at 20% to 90% of the height of the reactor from the top to the bottom in the second hydrocracking unit; (5) The second hydrocracked stream is split into light and heavy components to obtain a heavy second hydrocracked stream and a light second hydrocracked stream. The heavy second hydrocracked stream is circulated to the hydrogenation pretreatment unit, and the light second hydrocracked stream is circulated back to the separation unit. The splitting temperature for the light and heavy component splitting of the second hydrocracked stream is 510-580°C. Among them, the tail oil enters the second hydrocracking unit through the first feed port on the top of the reactor in the second hydrocracking unit; the heavy wax oil feedstock enters the second hydrocracking unit through the second feed port on the side wall of the reactor shell between the hydrocracking catalyst bed A and the hydrorefining catalyst bed; the light naphtha enters the second hydrocracking unit through the third feed port on the side wall of the reactor shell between the hydrorefining catalyst bed and the hydrocracking catalyst bed B; the amount of light naphtha entering the second hydrocracking unit is 10wt% to 85wt% of the light naphtha product.

2. The hydrocracking method for processing high-drying point wax oil according to claim 1, wherein In step (1), the cutting temperature for cutting the high-drying point wax oil raw material into light and heavy components is 540-580°C.

3. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 8% to 18%, and the bottom of the hydrorefining catalyst bed is located at 35% to 75% of the reactor height from top to bottom in the second hydrocracking unit.

4. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The amount of light naphtha entering the second hydrocracking unit is 15 wt% to 75 wt% of the light naphtha product.

5. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The cutting temperature for cutting the light and heavy components of the second hydrocracking stream is 0 to 30° C. lower than the cutting temperature for cutting the light and heavy components of the high drying point wax oil feedstock.

6. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The cutting temperature for cutting the light and heavy components of the second hydrocracking stream is 5 to 20° C. lower than the cutting temperature for cutting the light and heavy components of the high drying point wax oil feedstock.

7. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the hydrogenation pretreatment unit include: reaction pressure of 8.0-20.0 MPa, reaction temperature of 340-430°C, volume space velocity of 0.2-10.0 h -1 , the hydrogen-to-oil volume ratio is 100-3000.

8. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the hydrogenation pretreatment unit include: reaction pressure of 15.0-18.0 MPa, reaction temperature of 370-425°C, volume space velocity of 0.8-2.0 h -1 , the hydrogen-to-oil volume ratio is 800-2000.

9. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the first hydrocracking unit include: reaction pressure of 8.0-20.0 MPa, reaction temperature of 330-425°C, volume space velocity of 0.6-8.0 h -1 , the hydrogen-to-oil volume ratio is 100-2500.

10. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the first hydrocracking unit include: reaction pressure of 15.0-18.0 MPa, reaction temperature of 360-410°C, volume space velocity of 0.8-2.0 h -1 , the hydrogen-to-oil volume ratio is 600-2200.

11. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the second hydrocracking unit include: reaction pressure of 8.0-18.0 MPa, reaction temperature of 320-410°C, volume space velocity of 0.6-8.0 h -1 , the hydrogen-to-oil volume ratio is 500-2500.

12. The hydrocracking method for processing high-drying point wax oil according to claim 1, characterized in that: The operating conditions of the second hydrocracking unit include: reaction pressure of 12.0-18.0 MPa, reaction temperature of 340-390°C, volume space velocity of 1.0-2.5 h -1 , the hydrogen-to-oil volume ratio is 600-2200.

13. A hydrocracking system for processing high-drying point wax oil, comprising a feed separation unit, a hydrogenation pretreatment unit, a first hydrocracking unit, a separation unit, a second hydrocracking unit, and a product separation unit, wherein A raw material separation unit is used to receive and separate the high-drying point wax oil raw material into light and heavy components to obtain light wax oil raw material and heavy wax oil raw material; A hydrogenation pretreatment unit is used to receive the light wax oil feedstock and hydrogen from the feedstock separation unit and obtain a hydrogenation pretreatment stream after reaction; a first hydrocracking unit, which is used to receive the hydropretreatment stream and hydrogen obtained after the reaction in the hydropretreatment unit, and obtain a first hydrocracking stream after the reaction; A separation unit, which is used to receive the first hydrocracking stream obtained after the reaction in the first hydrocracking unit, and obtain gas, light naphtha, heavy naphtha and tail oil after separation; The second hydrocracking unit is used to receive the tail oil from the separation unit, the heavy wax oil feedstock from the feedstock separation unit, and the light naphtha from the separation unit, and obtain a second hydrocracking stream after reaction; according to the flow direction of the liquid phase materials, the reactor in the second hydrocracking unit includes a hydrocracking catalyst bed A, a hydrocracking catalyst bed B, and a hydrorefining catalyst bed disposed between the hydrocracking catalyst bed A and the hydrocracking catalyst bed B; a product separation unit for receiving and splitting the second hydrocracked stream from the second hydrocracking unit into light and heavy components to obtain a light second hydrocracked stream and a heavy second hydrocracked stream; the obtained heavy second hydrocracked stream is circulated to the hydropretreatment unit via a pipeline, and the light second hydrocracked stream is circulated to the separation unit via a pipeline; Among them, the volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 5% to 30%; the bottom position of the hydrorefining catalyst bed is located at 20% to 90% of the height of the reactor from top to bottom in the second hydrocracking unit; the reactor in the second hydrocracking unit includes a first feed port, a second feed port, and a discharge port; wherein, the first feed port is located at the top of the reactor, and the tail oil enters the second hydrocracking unit through the first feed port, and the second feed port is arranged on the side wall of the reactor shell between the hydrocracking catalyst bed A and the hydrorefining catalyst bed, and the heavy wax oil feedstock enters the second hydrocracking unit through the second feed port; the reactor in the second hydrocracking unit also includes a third feed port, which is arranged on the side wall of the reactor shell between the hydrorefining catalyst bed and the hydrocracking catalyst bed B, and the light naphtha enters the second hydrocracking unit through the third feed port.

14. The hydrocracking system for processing high-drying point wax oil according to claim 13, characterized in that: The volume ratio of the hydrorefining catalyst bed to the total catalyst bed of the second hydrocracking unit is 8% to 18%; the bottom position of the hydrorefining catalyst bed is located at 35% to 75% of the reactor height from top to bottom in the second hydrocracking unit.

15. The hydrocracking system for processing high-drying point wax oil according to claim 13, characterized in that: The separation unit includes a gas-liquid separator and a distillation tower.

16. The hydrocracking system for processing high-drying point wax oil according to claim 13, characterized in that: The hydrogenation pretreatment unit is provided with at least one reactor; when the hydrogenation pretreatment unit is provided with two or more reactors, the reactors are connected in parallel and / or in series, and the reactor is at least one of a fixed bed hydrogenation reactor, a suspended bed hydrogenation reactor, and a fluidized bed hydrogenation reactor.

17. The hydrocracking system for processing high-drying point wax oil according to claim 16, characterized in that: When the hydrogenation pretreatment unit is provided with two or more reactors, the reactors are connected in series.

18. The hydrocracking system for processing high-drying point wax oil according to claim 13, characterized in that: The first hydrocracking unit and the second hydrocracking unit are each provided with at least one reactor; when the first hydrocracking unit and the second hydrocracking unit are each provided with two or more reactors, the reactors are connected in parallel and / or in series, and the reactor is at least one of a fixed bed hydrogenation reactor, a suspended bed hydrogenation reactor, and a fluidized bed hydrogenation reactor.

19. The hydrocracking system for processing high-drying point wax oil according to claim 18, characterized in that: When the first hydrocracking unit and the second hydrocracking unit are each provided with two or more reactors, the reactors are connected in series and are fixed bed reactors.

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