A method for starting a hydrocracking unit

Abstract

The present invention provides a method for starting up a hydrocracking unit, the method comprising the following steps: the hydrocracking unit comprises a refining reaction zone and a cracking reaction zone arranged in series, wherein the refining reaction zone is loaded with at least one hydrorefining catalyst and the cracking reaction zone is loaded with at least one hydrocracking catalyst; (1) when the temperature reaches 170-190°C, a sulfiding agent is introduced into the refining reaction zone; (2) the refining reaction zone is heated to perform a staged sulfiding treatment, and then the feedstock oil is switched; (3) the cracking reaction zone is heated to perform a staged constant temperature sulfiding treatment. The provided method can significantly shorten the start-up time by matching specific start-up temperature increase paths for the hydrorefining catalyst and the hydrocracking catalyst, and can be combined with the optimization of the process flow of the hydrocracking unit, thereby improving the catalyst sulfiding effect and solving the problems of nitrogen poisoning of the hydrocracking catalyst in the initial start-up period.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, relates to a hydrocracking process, and in particular to a method for starting a hydrocracking unit. Background Art

[0002] With increasingly stringent environmental protection requirements for fuel products, hydrogenation units have become an indispensable and important production unit for major refining and chemical companies. In particular, hydrocracking units, as the main unit for producing chemical raw materials, have received special attention from companies for their safe and stable operation.

[0003] The current startup methods for hydrocracking units can meet the requirements for safe and stable startup, but there are still some problems such as long startup time, and there is room for further improvement. Currently, sulfur and ammonia injection operations are required during the startup process of hydrocracking units. It is generally recognized that when the hydrogen sulfide content in the circulating hydrogen reaches 1000-2000 mg / kg and the ammonia content in the high-molecular acid water reaches 500-1500 mg / kg, sulfur breakthrough and ammonia breakthrough are considered to have occurred. However, the sulfur breakthrough and ammonia breakthrough times in existing startup methods are generally long. Generally, the sulfur breakthrough time is 10-16 hours, sometimes even longer, and the ammonia breakthrough time is also more than 6-10 hours. The startup time generally exceeds 50 hours, affecting the overall economic benefits of the unit.

[0004] Chinese patent CN102311792A discloses a hydrocracking process sulfurization method. This method incorporates a gas-liquid separator between the hydrotreating reactor and the hydrocracking reactor. During the initial sulfurization process, the hydrotreating effluent enters the gas-liquid separator, the liquid phase is recycled back to the hydrotreating reactor, and the gas phase is first passed through the hydrocracking reactor and then recycled back to the hydrotreating reactor. This method can improve the sulfurization effect of the catalyst, but it still faces the problem of nitrogen poisoning of the catalyst at the top of the hydrocracking reactor during the initial startup.

[0005] Chinese patent CN109777475A discloses a method for rapidly starting a hydrocracking catalyst. This method eliminates the ammonia injection passivation step and reduces start-up time by introducing feedstock oil in advance. However, introducing feedstock oil in advance at low temperatures can cause more severe nitrogen poisoning of the hydrocracking catalyst, negatively impacting the cracking activity and long-term operation of the hydrocracking unit.

[0006] Chinese patent CN107446616A discloses a hydrocracking startup method that, by loading a low-molecular-weight nitrogen compound onto the hydrocracking catalyst, eliminates the need for ammonia injection during startup, thus reducing time. However, this method still poses the problem of nitrogen poisoning of the hydrocracking catalyst during the initial startup phase. Summary of the Invention

[0007] After research, the applicant found that in the current start-up plan for the hydrocracking unit, the same start-up temperature increase path is used for the hydrorefining catalyst and the hydrocracking catalyst in the hydrocracking unit. However, after research, the applicant found that due to the different interaction forces between the metal and the carrier, the hydrorefining catalyst and the hydrocracking catalyst exhibit different sulfurization and reduction abilities. Based on the above findings, the applicant proposed a start-up method for differentially controlling the temperature increase paths of the hydrorefining catalyst and the hydrocracking catalyst.

[0008] In response to the problems existing in the existing hydrocracking unit start-up method, the present invention aims to provide a hydrocracking unit start-up method. The provided start-up method can significantly shorten the start-up time, improve the catalyst sulfurization effect, and solve the problem of nitrogen poisoning of the hydrocracking catalyst in the initial stage of start-up by matching specific start-up temperature increase paths for the hydrorefining catalyst and the hydrocracking catalyst respectively, and combining it with the optimization of the hydrocracking unit process flow.

[0009] The present invention provides a method for starting a hydrocracking unit, comprising the following steps: the hydrocracking unit comprises a refining reaction zone and a cracking reaction zone arranged in series, wherein the refining reaction zone is filled with at least one hydrorefining catalyst, and the cracking reaction zone is filled with at least one hydrocracking catalyst;

[0010] (1) When the temperature reaches 170-190°C, introduce the sulfiding agent into the refining reaction zone;

[0011] (2) The refining reaction zone is heated to the first refining vulcanization temperature for the first constant temperature vulcanization treatment; then the temperature is heated to the second refining vulcanization temperature for the second constant temperature vulcanization treatment; further heated to the third refining vulcanization temperature for the third constant temperature vulcanization treatment, and then the feed of crude oil is switched;

[0012] (3) The temperature of the cracking reaction zone is raised to the first cracking sulfurization temperature for the first constant temperature sulfurization treatment, and a passivating agent is introduced into the cracking reaction zone at the same time; then the temperature is raised to the second cracking sulfurization temperature for the second constant temperature sulfurization treatment; and further the temperature is raised to the third cracking sulfurization temperature for the third constant temperature sulfurization treatment.

[0013] Furthermore, in the hydrocracking unit startup method, the first refining sulfiding temperature is 200-225°C, preferably 205-220°C; the heating rate to the first refining sulfiding temperature is preferably controlled to be 10-30°C / h, preferably 15-25°C / h.

[0014] Furthermore, in the hydrocracking unit startup method, the refining second sulfiding temperature is 280-300°C, preferably 285-295°C; the heating rate to the refining second sulfiding temperature is preferably controlled to be 8-25°C / h, preferably 10-20°C / h.

[0015] Furthermore, in the hydrocracking unit startup method, the refining third sulfiding temperature is 330-360°C, preferably 340-350°C; the heating rate to the refining third sulfiding temperature is preferably controlled to be 5-20°C / h, preferably 8-12°C / h.

[0016] Furthermore, in the hydrocracking unit start-up method, in step (2), the first constant temperature sulfurization treatment time is 6 to 10 hours; the second constant temperature sulfurization treatment time is 4 to 8 hours; and the third constant temperature sulfurization treatment time is 1 to 3 hours.

[0017] Furthermore, in the hydrocracking unit startup method, the first cracking sulfidation temperature is 240-280°C, preferably 250-260°C; the heating rate to the first cracking sulfidation temperature is preferably controlled to be 8-25°C / h, preferably 10-20°C / h.

[0018] Furthermore, in the hydrocracking unit startup method, the second sulfidation temperature for cracking is 290-310°C, preferably 295-305°C; the heating rate for heating to the second sulfidation temperature for cracking is preferably controlled to be 8-20°C / h, preferably 8-15°C / h.

[0019] Furthermore, in the hydrocracking unit startup method, the cracking third sulfidation temperature is 310-330°C, preferably 315-320°C; the heating rate to the cracking third sulfidation temperature is preferably controlled to be 5-15°C / h, preferably 6-10°C / h.

[0020] Furthermore, in the hydrocracking unit start-up method, in step (3), the first constant temperature sulfurization treatment time is 3 to 8 hours; the second constant temperature sulfurization treatment time is 2 to 6 hours; and the third constant temperature sulfurization treatment time is 1 to 3 hours.

[0021] Furthermore, in the hydrocracking unit startup method, after the sulfiding agent is introduced into the reaction system, the sulfiding agent and the startup oil enter the refining reaction zone, and the effluent of the refining reaction zone obtained after the reaction enters the cracking reaction zone.

[0022] Furthermore, in the hydrocracking unit startup method, the refining reaction zone is provided with two catalyst beds, preferably three to five catalyst beds, and more preferably, feed ports are provided between the catalyst beds. The sulfiding agent and the startup oil can enter the refining reaction zone through the refining reaction zone inlet and the feed ports provided between the catalyst beds.

[0023] Furthermore, in the hydrocracking unit startup method, the cracking reaction zone is provided with two catalyst beds, preferably three to five catalyst beds, and more preferably, feed ports are provided between the catalyst beds. The passivating agent and the effluent from the refining reactor enter the cracking reaction zone through the inlet of the cracking reaction zone and the feed ports provided between the catalyst beds.

[0024] Furthermore, in the hydrocracking unit start-up method, the operating conditions of the refining reaction zone are as follows: hydrogen partial pressure 2-20 MPa, preferably 6-18 MPa; hydrogen-to-oil volume ratio 200-4000, preferably 500-2000; volume space velocity 0.1-8 h -1 , preferably 0.6~2.0h -1 ; The average reaction temperature is 290-415°C, preferably 320-400°C.

[0025] Furthermore, in the hydrocracking unit start-up method, the operating conditions of the cracking reaction zone are as follows: hydrogen partial pressure 5-20 MPa, preferably 6-18 MPa; hydrogen-to-oil volume ratio 300-4000, preferably 600-2000; volume space velocity 0.1-10 h -1 , preferably 0.5 to 2.0 hours -1 ; The average reaction temperature is 270-460°C, preferably 330-420°C.

[0026] Furthermore, in the hydrocracking unit start-up method, the sulfiding agent can be any one or more of the commonly used sulfiding agents in the existing industry, specifically one or more of dimethyl disulfide (DMDS), carbon disulfide, and FSA-55 sulfiding agent (developed by Dalian (Fushun) Petrochemical Research Institute of Sinopec).

[0027] Furthermore, in the hydrocracking unit start-up method, the passivating agent can be any one of the existing conventional industrial passivating agents, and the specific passivating agent can be selected from one or more of anhydrous liquid ammonia, cyclohexylamine, and n-butylamine.

[0028] Furthermore, in the method for starting up the hydrocracking unit, the effluent from the refined reaction zone obtained after the reaction enters the cracking reaction zone after heat exchange, and the heat exchange temperature is adjusted according to the temperature requirement of the cracking reaction zone. Heat exchange is generally performed through a heat exchanger, and the heat exchanger can be a conventional industrial type heat exchanger, specifically any one of a shell and tube heat exchanger, a plate heat exchanger, a fin-tube heat exchanger, and a plate-fin heat exchanger.

[0029] Furthermore, in the hydrocracking unit startup method, the feedstock oil generally has an initial boiling point of 150-330°C and a final boiling point of 360-550°C. There are generally no restrictions on sulfur and nitrogen content. Specifically, the feedstock oil can be selected from one or more of straight-run diesel, catalytic diesel, pressure-reduced wax oil, and shale oil.

[0030] Furthermore, in the hydrocracking unit startup method, at least one hydrorefining catalyst is loaded into the refining reaction zone. Typically, the hydrorefining catalyst comprises a hydrogenation-active metal component and a support. The hydrogenation-active metal component may be one or more metals from Group VIB, Group VIIB, or Group VIII, specifically two or more selected from Co, Mo, Ni, and W. The support may generally be an inorganic refractory oxide such as alumina or silica. The hydrorefining catalyst may be a commercially available product or prepared as needed according to common knowledge in the art. Specifically, commercial hydrogenation catalysts such as FHUDS-8, FF-66, FF-36, and FF-56 developed by Dalian (Fushun) Research Institute of Petrochemicals (FRIPP) of Sinopec Corporation may be used.

[0031] Furthermore, in the hydrocracking unit startup method, at least one hydrocracking catalyst is loaded into the cracking reaction zone. The catalyst used in the hydrocracking reaction includes a cracking component and a hydrogenation component; the cracking component typically comprises amorphous silica-alumina and a molecular sieve. The hydrogenation component is one or more non-precious metal elements from Group VI, Group VII, or Group VIII, preferably two or more of Co, Mo, Ni, and W as active components. The hydrogenation component, calculated as oxide, comprises 10% to 40% of the catalyst weight. Any commercially available hydrocracking catalyst can be used, and different types of hydrocracking catalysts can be selected depending on the target product. For naphtha production, a light oil-type hydrocracking catalyst can be used; for middle distillates, a medium oil-type hydrocracking catalyst can be used; and for flexible production of both naphtha and middle distillates, a flexible hydrocracking catalyst can be used. For example, commercial hydrocracking catalysts such as FC-34, FC-50, FC-52, and FC-76 developed by Fushun Research Institute of Petrochemical Industry (FRIPP) can also be prepared according to common knowledge in this field as needed.

[0032] Compared with the existing hydrocracking unit startup method, the hydrocracking unit startup method provided in the technical solution of the present invention has the following advantages:

[0033] The startup plan for existing hydrocracking units usually involves unified control of the inlet temperatures of the refining reactor and the cracking reactor. To ensure stable hydrocracking reaction temperatures during feedstock switching and avoid "temperature fluctuations," feedstock switching is generally performed when the inlet temperatures of the refining reactor and the cracking reactor are between 310 and 320°C. At these temperatures, the hydrorefining catalyst is unable to remove nitrogen impurities from the feedstock to the ideal level (generally required to be less than 10 mg / kg), inevitably causing nitrogen poisoning of the catalyst at the top of the hydrocracking reactor, affecting the hydrocracking activity and long-term stability of the unit.

[0034] During the research process to solve the above-mentioned problems, the applicant discovered that there are significant differences in the reduction, sulfidation, and passivation performance of hydrotreating catalysts and hydrocracking catalysts. To fully utilize the optimal performance of each catalyst, based on this discovery, the applicant has originally proposed a specific start-up temperature path for hydrotreating catalysts and hydrocracking catalysts. The hydrocracking catalyst can be raised to a higher temperature for sulfidation without waiting for sulfur breakthrough, while the hydrotreating catalyst does not need to wait for ammonia breakthrough to inhibit activity, which can effectively improve the catalyst sulfidation effect and further enhance the catalyst's reaction performance. Based on the hydrotreating catalyst's easy reduction property, the first constant temperature sulfidation temperature is controlled within a relatively low temperature range to prevent the hydrotreating catalyst from being reduced by H2 before the hydrogen sulfide content in the reaction system reaches 1000 mg / kg, thus avoiding the problem of increased difficulty in sulfiding the reduced hydrotreating catalyst. At the same time, based on the discovery that the hydrocracking catalyst does not undergo significant reduction even at a higher temperature (260°C) in a hydrogen atmosphere before hydrogen sulfide breakthrough, the first constant temperature sulfidation treatment of the hydrocracking catalyst is carried out at a higher temperature to achieve a better sulfidation effect. This solves the existing startup method's inability to simultaneously address the sulfurization and catalytic activity of both the hydrotreating and hydrocracking catalysts. It enables feedstock switching at higher hydrotreating reaction temperatures, fundamentally resolving the undesirable nitrogen poisoning of the initial hydrocracking catalysts encountered in conventional startup methods.

[0035] In the hydrocracking unit startup method provided in this application, during the startup process, the sulfiding agent and passivating agent are uniformly introduced into the corresponding hydrorefining reactor and hydrocracking reactor through multiple feed ports (feed ports between catalyst beds). Combined with the proposed dedicated startup temperature paths for the hydrorefining catalyst and hydrocracking catalyst, the startup time can be significantly reduced, saving manpower and material resources, allowing the unit to quickly enter the normal production stage and improving the unit's economic benefits. During the feedstock switching stage, the hydrorefining reaction effluent enters the hydrocracking reactor from different feed positions, making it easier to control the temperature of each bed in the hydrocracking reactor, greatly reducing the risk of "temperature runaway" during the hydrocracking unit startup phase and improving the safety margin of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The figure is a process flow diagram of a method for starting a hydrocracking unit in an embodiment of the present invention.

[0037] Among them, 1-start-up oil; 2-sulfurizing agent; 3-top feed port of hydrorefining reactor; 4-feed port I between catalyst beds of hydrorefining reactor; 5-feed port II between catalyst beds of hydrorefining reactor; 6-hydrorefining reactor; 7-hydrorefining reaction product; 8-heat exchanger; 9-feed to hydrocracking reactor after heat exchange; 10-passivating agent; 11-top feed port of hydrocracking reactor; 12-feed port I between catalyst beds of hydrocracking reactor; 13-feed port II between catalyst beds of hydrocracking reactor; 14-hydrocracking reactor; 15-hydrocracking reaction product; 16-gas-liquid separator; 17-liquid phase product; 18-fractionation tower; 19-gas phase product; 20-circulating hydrogen compressor; 21-circulating hydrogen; 22-new hydrogen.

[0038] Figure 2 This is the vulcanization temperature curve of Example 1.

[0039] Figure 3 This is the vulcanization temperature curve of Comparative Example 1. DETAILED DESCRIPTION

[0040] The technical solutions and technical effects provided by the present invention are discussed in detail below with reference to the accompanying drawings and specific implementation examples.

[0041] Unless otherwise explicitly stated, throughout the specification and claims of the present invention, the term "comprise" or its variations such as "include" or "comprising", etc. will be understood to include the stated elements or components but not to exclude other elements or other components.

[0042] In the context of this specification, for convenience 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.

[0043] In the context of this specification, 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.

[0044] Throughout this specification, all numerical values ​​for parameters (eg, amounts or conditions) are to be understood as being modified in all instances by the term "about," regardless of whether "about" actually appears before the numerical value.

[0045] Combine Figure 1 The method for starting up a hydrocracking unit provided by the present invention is further described.

[0046] Example 1

[0047] Use attached Figure 1 The hydrocracking unit startup method flow chart shows how the hydrotreating reactor inlet temperature and the hydrocracking reactor inlet temperature are adjusted according to the dedicated startup paths for the hydrotreating catalyst and hydrocracking catalyst, respectively. When the hydrotreating reactor inlet temperature is 180°C, a sulfiding agent (DMDS) is introduced into the reaction system. The sulfiding agent enters the hydrotreating reactor through the top feed port, the hydrotreating reactor catalyst bed interlayer feed port I, and the hydrotreating reactor catalyst bed interlayer feed port II. The hydrotreating reaction products enter the hydrocracking reactor through the top feed port, the hydrotreating reactor catalyst bed interlayer feed port I, and the hydrotreating reactor catalyst bed interlayer feed port II.

[0048] The special start-up path for the hydrotreating catalyst is: increase the inlet temperature of the hydrotreating reactor to 210°C at a heating rate of 15°C / h. When the inlet temperature of the hydrotreating reactor reaches 210°C, the hydrogen sulfide content in the circulating hydrogen reaches 1600 mg / kg, and a constant-temperature sulfidation treatment at 210°C for 6 hours is started; after the constant-temperature sulfidation is completed, increase the inlet temperature of the hydrotreating reactor to 290°C at a heating rate of 10°C / h, and a constant-temperature sulfidation treatment at 290°C for 6 hours is started; after the constant-temperature sulfidation is completed, increase the inlet temperature of the hydrotreating reactor to 340°C at a heating rate of 10°C / h, and a constant-temperature sulfidation treatment at 340°C for 2 hours is started.

[0049] Dedicated hydrocracking catalyst startup procedure: Raise the hydrocracking reactor inlet temperature to 260°C at a heating rate of 10°C / h. At 260°C, activate the ammonia injection system to allow passivation to enter the hydrocracking reactor through the top feed port, catalyst bed interlayer feed port I, and catalyst bed interlayer feed port II. A 4-hour constant-temperature sulfiding treatment at 260°C is initiated. At the end of the sulfiding treatment, the ammonia content in the high-fraction, neutralized acidic water is 1800 mg / kg, indicating ammonia breakthrough. Following the completion of the constant-temperature sulfiding treatment, raise the hydrocracking reactor inlet temperature to 295°C at a heating rate of 8°C / h, and commence a 4-hour constant-temperature sulfiding treatment at 295°C. Following the completion of the constant-temperature sulfiding treatment, raise the hydrocracking reactor inlet temperature to 320°C at a heating rate of 6°C / h, and commence a 2-hour constant-temperature sulfiding treatment at 320°C. After the sulfiding treatment is complete, the feedstock is switched.

[0050] Example 2

[0051] Use attached Figure 1 The hydrocracking startup process flow diagram shows the hydrotreating reactor inlet temperature and the hydrocracking reactor inlet temperature being adjusted according to the dedicated startup paths for the hydrotreating catalyst and hydrocracking catalyst, respectively. A sulfiding agent (FSA-55, developed by the Fushun Petrochemical Research Institute of Sinopec) was introduced into the reaction system at a hydrotreating reactor inlet temperature of 170°C. The sulfiding agent entered the hydrotreating reactor through the top feed port, the hydrotreating reactor catalyst bed interlayer feed port I, and the hydrotreating reactor catalyst bed interlayer feed port II. The hydrotreating reaction products entered the hydrocracking reactor through the top feed port, the hydrotreating reactor catalyst bed interlayer feed port I, and the hydrotreating reactor catalyst bed interlayer feed port II.

[0052] Special start-up path for hydrotreating catalyst: increase the inlet temperature of the hydrotreating reactor to 220°C at a heating rate of 20°C / h. When the inlet temperature of the hydrotreating reactor reaches 220°C, the hydrogen sulfide content in the circulating hydrogen reaches 1200 mg / kg, and start constant-temperature sulfidation treatment at 220°C for 8 hours; after the constant-temperature sulfidation is completed, increase the inlet temperature of the hydrotreating reactor to 285°C at a heating rate of 15°C / h, and start constant-temperature sulfidation treatment at 285°C for 4 hours; after the constant-temperature sulfidation is completed, increase the inlet temperature of the hydrotreating reactor to 350°C at a heating rate of 10°C / h, and start constant-temperature sulfidation at 350°C for 1 hour.

[0053] Dedicated hydrocracking catalyst startup procedure: Raise the hydrocracking reactor inlet temperature to 250°C at a heating rate of 20°C / h. At 250°C, activate the ammonia injection system to allow passivation to enter the hydrocracking reactor through the top feed port, catalyst bed interlayer feed port I, and catalyst bed interlayer feed port II. A 6-hour constant-temperature sulfiding treatment at 250°C is initiated. At the end of the constant-temperature sulfiding treatment, the ammonia content in the high-fraction, neutralized acidic water is 2000 mg / kg, indicating ammonia breakthrough. Following the completion of the constant-temperature sulfiding treatment, increase the hydrocracking reactor inlet temperature to 300°C at a heating rate of 10°C / h, and commence constant-temperature sulfiding at 300°C for 2 hours. Following the completion of the constant-temperature sulfiding treatment, increase the hydrocracking reactor inlet temperature to 315°C at a heating rate of 8°C / h, and commence constant-temperature sulfiding at 315°C for 1 hour. After the sulfiding treatment is complete, the feedstock is switched.

[0054] Comparative Example 1

[0055] The conventional hydrocracking process (e.g. Figure 1 ) Unified control of the inlet temperature of the hydrotreating reactor and the hydrocracking reactor, introducing a sulfiding agent (DMDS) into the reaction system when the inlet temperature is 180°C, and raising the inlet temperature to 230°C at a rate of 10°C / h. After 5 hours of operation, the inlet temperature is raised to 230°C to wait for sulfur penetration. After waiting for 4 hours, the hydrogen sulfide content in the circulating hydrogen reaches 1500 mg / kg, and constant temperature sulfidation at 230°C for 8 hours is started; after constant temperature sulfidation at 230°C for 2 hours, the ammonia injection equipment is turned on to inject sulfur into the reaction system. After introducing a passivator and 8 hours of constant-temperature vulcanization at 230°C, the acidic ammonia content in the high-grade water did not meet the breakthrough standard. After waiting for 2 hours, the ammonia content in the acidic water in the high-grade water reached 1200 mg / kg, at which point ammonia breakthrough was considered. The inlet temperature was increased to 290°C at a rate of 8°C / h. After reaching 290°C, a 6-hour constant-temperature vulcanization process began. After the constant-temperature vulcanization process ended, the inlet temperature was increased to 320°C at a rate of 6°C / h. After reaching 320°C, a 2-hour constant-temperature vulcanization process began. After the vulcanization process ended, the feedstock was switched.

[0056] Comparative Example 2

[0057] The inlet temperatures of the hydrotreating reactor and the hydrocracking reactor were uniformly controlled using the conventional hydrocracking start-up route. When the inlet temperature was 170°C, a sulfiding agent (FSA-55) was introduced into the reaction system. The inlet temperature was raised to 230°C at a rate of 8°C / h. After 6 hours of operation, the inlet temperature was raised to 230°C to wait for sulfur penetration. After 6 hours of waiting, the hydrogen sulfide content in the circulating hydrogen reached 1800 mg / kg, and constant-temperature sulfurization at 230°C was started for 8 hours. At constant-temperature sulfurization at 230°C, the inlet temperature was raised to 230°C to wait for sulfur penetration. After 2 hours of curing, the ammonia injection equipment was turned on to introduce a passivating agent into the reaction system. After 8 hours of constant-temperature curing at 230°C, the acidic ammonia content in the high-precipitation solution reached 1600 mg / kg, indicating ammonia breakthrough into the reactor. The inlet temperature was raised to 290°C at a rate of 6°C / h. After reaching 290°C, a 6-hour constant-temperature curing process was initiated. After the constant-temperature curing process was completed, the inlet temperature was raised to 310°C at a rate of 5°C / h. After reaching 310°C, a 2-hour constant-temperature curing process was initiated. After the curing process was completed, the feedstock was switched.

[0058] Table 1 Reaction results of Examples and Comparative Examples

[0059]

[0060] The above examples and comparative examples show that the hydrocracking start-up method of the present invention can effectively shorten the time required for start-up, while improving the sulfurization effect of the hydrorefining catalyst and the hydrocracking catalyst, and can achieve efficient hydrocracking at a lower reaction temperature and is conducive to the long-term operation of the device, providing significant efficiency improvement for the enterprise.

Claims

1. A method for starting a hydrocracking unit, comprising: a hydrocracking unit comprising a refining reaction zone and a cracking reaction zone arranged in series, wherein the refining reaction zone is filled with at least one hydrorefining catalyst, and the cracking reaction zone is filled with at least one hydrocracking catalyst; (1) When the temperature reaches 170-190°C, introduce the sulfiding agent into the refining reaction zone; (2) The refining reaction zone is heated to the first refining vulcanization temperature for the first constant temperature vulcanization treatment; then the temperature is heated to the second refining vulcanization temperature for the second constant temperature vulcanization treatment; further heated to the third refining vulcanization temperature for the third constant temperature vulcanization treatment, and then the feedstock oil is switched; the first refining vulcanization temperature is 200-225°C, the second refining vulcanization temperature is 280-300°C, and the third refining vulcanization temperature is 330-360°C; (3) The temperature of the cracking reaction zone is raised to the first cracking sulfurization temperature for the first constant temperature sulfurization treatment, and a passivating agent is introduced into the cracking reaction zone at the same time; then the temperature is raised to the second cracking sulfurization temperature for the second constant temperature sulfurization treatment; further the temperature is raised to the third cracking sulfurization temperature for the third constant temperature sulfurization treatment; the first cracking sulfurization temperature is 240-280°C, the second cracking sulfurization temperature is 290-310°C, and the third cracking sulfurization temperature is 310-330°C; The refining reaction zone is provided with 2-5 catalyst beds, and feed ports are provided between the catalyst beds. The sulfiding agent and the start-up oil enter the refining reaction zone through the inlet of the refining reaction zone and the feed port provided between the catalyst beds; the cracking reaction zone is provided with 2-5 catalyst beds, and feed ports are provided between the catalyst beds; the passivating agent and the effluent of the refining reactor enter the cracking reaction zone through the inlet of the cracking reaction zone and the feed port provided between the catalyst beds.

2. The method for starting up a hydrocracking unit according to claim 1, wherein: The first refined vulcanization temperature is 205-220° C.; the heating rate to the first refined vulcanization temperature is controlled to be 10-30° C. / h.

3. The method for starting up a hydrocracking unit according to claim 2, wherein: The heating rate to the refined first vulcanization temperature is controlled to be 15-25°C / h.

4. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The refined second vulcanization temperature is 285-295° C.; the heating rate to the refined second vulcanization temperature is controlled to be 8-25° C. / h.

5. The method for starting up a hydrocracking unit according to claim 4, characterized in that: The heating rate to the refined second vulcanization temperature is controlled to be 10-20°C / h.

6. The method for starting up a hydrocracking unit according to claim 1, wherein: The refined third vulcanization temperature is 340-350° C.; the heating rate to the refined third vulcanization temperature is controlled to be 5-20° C. / h.

7. The method for starting up a hydrocracking unit according to claim 6, characterized in that: The heating rate to the refined third vulcanization temperature is controlled to be 8-12°C / h.

8. The method for starting up a hydrocracking unit according to claim 1, characterized in that: In step (2), the first constant temperature vulcanization treatment time is 6 to 10 hours; the second constant temperature vulcanization treatment time is 4 to 8 hours; and the third constant temperature vulcanization treatment time is 1 to 3 hours.

9. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The first cracking sulfidation temperature is 250-260° C.; the heating rate to the first cracking sulfidation temperature is controlled to be 8-25° C. / h.

10. The method for starting up a hydrocracking unit according to claim 9, characterized in that: The heating rate to the first sulfidation temperature of cracking is controlled to be 10-20°C / h.

11. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The second cracking sulfide temperature is 295-305° C.; the heating rate to the second cracking sulfide temperature is controlled to be 8-20° C. / h.

12. The method for starting up a hydrocracking unit according to claim 11, characterized in that: The heating rate to the cracking second sulfidation temperature is controlled to be 8-15°C / h.

13. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The third cracking sulfurization temperature is 315-320°C; the heating rate to the third cracking sulfurization temperature is controlled to be 5-15°C / h.

14. The method for starting up a hydrocracking unit according to claim 13, characterized in that: The heating rate to the cracking third sulfurization temperature is controlled to be 6-10°C / h.

15. The method for starting up a hydrocracking unit according to claim 1, characterized in that: In step (3), the first constant temperature vulcanization treatment time is 3 to 8 hours; the second constant temperature vulcanization treatment time is 2 to 6 hours; and the third constant temperature vulcanization treatment time is 1 to 3 hours.

16. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The refining reaction zone is provided with 3 to 5 catalyst beds.

17. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The cracking reaction zone is provided with 3 to 5 catalyst beds.

18. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The operating conditions of the refining reaction zone are as follows: hydrogen partial pressure of 2-20 MPa; hydrogen to oil volume ratio of 200-4000; volume space velocity of 0.1-8 h -1 ; The reaction temperature is 290~415℃.

19. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The operating conditions of the refining reaction zone are as follows: hydrogen partial pressure of 6-18 MPa; hydrogen-oil volume ratio of 500-2000; volume space velocity of 0.6-2.0 h -1 ; The reaction temperature is 320-400℃.

20. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The operating conditions of the cracking reaction zone are as follows: hydrogen partial pressure of 5-20 MPa; hydrogen-oil volume ratio of 600-2000; volume space velocity of 0.5-2.0 h -1 ; The reaction temperature is 330~420℃.

21. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The operating conditions of the cracking reaction zone are as follows: hydrogen partial pressure of 6-18 MPa; hydrogen-oil volume ratio of 600-2000; volume space velocity of 0.5-2.0 h -1 ; The reaction temperature is 330~420℃.

22. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The vulcanizing agent is selected from one or more of dimethyl disulfide, carbon disulfide, and FSA-55 vulcanizing agent.

23. The method for starting up a hydrocracking unit according to claim 1, characterized in that: The passivating agent is selected from one or more of anhydrous liquid ammonia, cyclohexylamine and n-butylamine.

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