Sulfation method for fixed-bed residue hydrotreating catalyst

Abstract

This invention discloses a sulfidation method for a fixed-bed residue hydrotreating catalyst. The method includes: after completing catalyst loading, airtightness checks, and catalyst pre-sulfidation preparation steps in the fixed-bed residue hydrotreating unit, initiating a reverse sulfidation process: first, establishing a reverse full-cycle flow for start-up diesel, then performing full-cycle pre-sulfidation of diesel; when the reactor temperature is 230–260°C, switching the start-up diesel to wax oil, then performing full-cycle pre-sulfidation of wax oil; finally, using fresh sulfur-containing wax oil for non-full-cycle pre-sulfidation. The catalysts loaded are a protective agent, a demetallization catalyst, a desulfurization catalyst, and a decarbonization catalyst, respectively. The sulfidation degree of the desulfurization catalyst and the decarbonization catalyst is controlled to be complete sulfidation, while the sulfidation degree of the protective agent and the demetallization catalyst is controlled to be incomplete sulfidation. This invention is beneficial for controlling the initial bed temperature rise, reducing initial carbon buildup, improving the catalyst's demetallization capacity, and ensuring stable operation of the unit.

Description

Technical Field

[0001] This invention relates to the field of residue hydrotreating technology, and more specifically, to a sulfidation method for a fixed-bed residue hydrotreating catalyst. Background Technology

[0002] Heavy oil refers to oil products with heavier fractions, generally referring to residue oil fractions. It is the remainder after crude oil has undergone atmospheric and vacuum distillation to remove gasoline, diesel, and vacuum distillate fractions. Residue oil is characterized by high viscosity, numerous heteroatoms, and a low hydrogen-to-carbon ratio, making it one of the most difficult feedstocks to process in the refining industry. Residue oil processing not only involves cracking it into low-boiling-point products such as naphtha, middle distillate oil, and vacuum gas oil, but also increasing its hydrogen-to-carbon ratio. Currently, the main developed residue oil processing methods are hydrotreating and decarbonization. Compared to coking in decarbonization, hydrotreating can increase the yield of liquid products and remove heteroatoms, providing high-quality feedstock for downstream units. Therefore, hydrotreating units have become a core unit for most refining companies.

[0003] Hydrotreating processes are classified into four types based on the catalyst state in the reactor: fixed bed, moving bed, fluidized bed, and suspended bed. Fixed bed residue hydrotreating technology offers advantages such as high liquid product yield, good product quality, strong production flexibility, low waste and feedstock production, environmental friendliness, and high return on investment, leading to its increasingly widespread application. Currently, the mainstream technology in China's residue hydrotreating process is the combination of fixed bed hydrotreating and catalytic cracking.

[0004] The fixed-bed residue hydrotreating catalyst series includes protective agents / demetallizers and desulfurization / residual carbon removal conversion catalysts. Protective agents and demetallizers are located at the front end of the residue hydrotreating process, effectively removing most metallic impurities from the residue feed while suppressing rapid increases in bed pressure drop. The residue hydrodesulfurization and residual carbon removal catalysts are located in the middle and later stages of the catalyst system, primarily used for deep desulfurization, denitrification, and moderate hydroconversion.

[0005] Residue oil contains a large amount of complex colloids, asphaltenes, and metal compounds (nickel and vanadium). During hydrotreating, the metals are deposited on the catalyst surface in the form of sulfides, while the macromolecular colloids and asphaltenes produce highly polymerized hydrocarbon compounds that are deposited on the catalyst. The catalyst deactivation process can be divided into three stages: (1) the initial rapid deactivation stage, where coke or multiple layers of metal deposits are deposited on the catalyst surface, causing rapid catalyst deactivation; (2) the slow deactivation stage, where metal impurities gradually cover the catalyst surface, causing slow catalyst deactivation; and (3) the final rapid deactivation stage, where metals and coke simultaneously block or restrict the entry of reactants into the catalyst channels. Metal deposition and coking cause catalyst deactivation, resulting in catalyst bed caking, increased pressure drop in the unit, and ultimately forcing the unit to shut down and replace the catalyst.

[0006] The operational life of a catalyst system depends on the metal capacity of the protective agent and demetallizer systems and the pressure drop in their respective beds. Therefore, maintaining the activity and stability of the protective agent and demetallizer systems throughout the entire operating cycle is crucial. However, in the initial operating phase, due to the high catalyst activity, the protective agent and demetallizer reactors experience significant temperature rises, and even localized radial temperature differences. The vigorous reactions in the initial operating phase are detrimental to catalyst performance, and may even exacerbate the initial coking rate, block catalyst pores, affect the diffusion and mass transfer of macromolecules into the catalyst channels, reduce the metal capacity of the catalyst, and severely impact the pressure drop and hot spots in the catalyst bed, significantly affecting the catalyst's lifespan.

[0007] Fixed-bed residue hydrotreating technology is characterized by complex feedstock composition, multiple reactors, and various catalyst grades, which directly impacts the unit's operational performance, product quality, and operating cycle during startup. The catalyst sulfidation step during startup is particularly crucial. Currently, during production, transportation, and storage, the active metal components of residue hydrotreating catalysts exist in an oxidized state. Research and industrial practice have demonstrated that only through sulfidation, converting the active metal components from the oxidized state to a correspondingly stable sulfidized state, can hydrotreating catalysts exhibit higher hydrotreating activity, stability, and selectivity, stronger resistance to toxicity, and longer lifespan, thus maximizing their effectiveness. Therefore, residue hydrotreating catalysts must be sulfidated before use to improve their activity and stability.

[0008] Catalytic sulfidation can be divided into two types: wet sulfidation and dry sulfidation. Dry sulfidation is carried out in the presence of hydrogen by directly using hydrogen sulfide containing a certain concentration or by directly injecting organic sulfides into the circulating hydrogen. Wet sulfidation is carried out in the presence of hydrogen by pre-sulfidation of distillate oil containing sulfides in the liquid and semi-liquid phases.

[0009] The existing fixed-bed residue hydrotreating catalyst sulfidation process has many problems. For example, to ensure complete catalyst sulfidation, excessive sulfiding agent is injected into the reaction system, causing problems with sulfiding agent storage and safety. Furthermore, the excessive hydrogen sulfide produced by the decomposition of the sulfiding agent corrodes equipment, especially high-pressure air-cooled areas, and increases the load on subsequent desulfurization processes, directly affecting operational complexity and economic efficiency. In the initial stage of the reaction, the over-activated catalyst has high hydrogenation activity, causing rapid coking on the catalyst surface and saturating a large amount of aromatics in the residue with hydrogen. However, due to the low reaction temperature, the difficult-to-react large-molecule asphaltenes cannot be converted into smaller molecules, disrupting the colloidal system with aromatics as solvent and asphaltenes as solute, leading to asphaltenes precipitation and foam entrainment at the hot high-pressure separator, severely affecting separation efficiency and system stability. Limited heat sources in the unit make reactor heating difficult, and the isothermal period during high-temperature sulfidation is too long, resulting in excessively long sulfidation time.

[0010] CN103059939A discloses a catalyst sulfidation method for a residue hydrotreating process. The method includes: 1) a residue hydrotreating unit comprising two rows of residue hydrotreating reactors; 2) one row of reactors in the residue hydrotreating unit operating normally, while the other row is prepared for sulfidation; 3) adjusting the desulfurization rate of the circulating hydrogen desulfurization unit in the stably operating residue hydrotreating unit; 4) introducing hydrogen sulfide-containing gas discharged from the circulating hydrogen desulfurization unit of the stably operating residue hydrotreating unit into the reactor of the prepared residue hydrotreating unit, and performing sulfidation operation on this row of reactors; 5) performing sulfidation under normal dry / wet sulfidation conditions for a residue hydrotreating unit until completion. This method has limited application scenarios. Firstly, the unit requires a dual-series setup, and the two rows need to be staggered in their start-up and shutdown operations, making it unsuitable for single-series units and simultaneous start-up / shutdown operation modes.

[0011] CN103100446A discloses a start-up sulfidation method for a hydrotreating unit. The method includes: firstly, a portion of the recycle gas is heated in a furnace and then a sulfiding agent is introduced. The sulfiding agent decomposes to produce hydrogen sulfide. Then, the hydrogen sulfide-rich recycle gas is mixed with a second portion of the recycle gas. After reaching the desired temperature, the mixture passes through a catalyst bed. Once a large amount of hydrogen sulfide has penetrated the catalyst bed, the temperature continues to rise. The injection rate of the sulfiding agent is adjusted according to the required hydrogen sulfide content, and the ratio of the two portions of recycle gas is adjusted according to the required temperature. Sulfidation is completed simultaneously under heating rate and isothermal conditions. After sulfidation, the temperature is lowered, start-up oil is introduced to wet the catalyst bed, and then the temperature is raised again and feedstock oil is introduced. This method uses gas preheating, resulting in low gas heating efficiency, a slow reactor heating rate, and a long sulfidation time. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention provides a sulfidation method for a fixed-bed residue hydrotreating catalyst. Using this method, the sulfidation time can be shortened, the amount of sulfiding agent required can be reduced, equipment corrosion can be decreased, and the increase in catalyst bed pressure drop and deterioration of hydrotreating product properties caused by excessive initial activation and coking of the catalyst can be prevented. This method is beneficial for controlling the initial bed temperature rise, reducing initial carbon buildup, improving the catalyst's demetallization ability and ensuring stable operation of the unit, extending catalyst lifespan, and extending the unit's operating cycle.

[0013] This invention provides a sulfidation method for a fixed-bed residue hydrotreating catalyst. The method includes: after completing catalyst loading, airtightness inspection, and catalyst pre-sulfidation preparation steps for the fixed-bed residue hydrotreating unit, starting the reverse sulfidation process of the catalyst: first, establishing a reverse full-cycle process for start-up diesel, then performing full-cycle pre-sulfidation of diesel, switching the start-up diesel to wax oil when the reactor temperature is 230-260℃, then performing full-cycle pre-sulfidation of wax oil, and finally using fresh sulfur-containing wax oil for non-full-cycle pre-sulfidation. The catalysts loaded are a protective agent, a demetallization catalyst, a desulfurization catalyst, and a decarbonization catalyst, and the sulfidation degree of the desulfurization catalyst and the decarbonization catalyst is controlled to be complete sulfidation, while the sulfidation degree of the protective agent and the demetallization catalyst is controlled to be incomplete sulfidation.

[0014] In the above-mentioned start-up method, the degree of vulcanization of the protective agent is 40% to 70%, preferably 50% to 65%.

[0015] In the above start-up method, the degree of sulfidation of the demetallization catalyst is 40% to 70%, preferably 50% to 65%.

[0016] In the above-mentioned start-up method, the degree of sulfidation of the desulfurization catalyst is 75% to 100%, preferably 80% to 95%.

[0017] In the above-mentioned start-up method, the degree of sulfidation of the decarbonization catalyst is 75% to 100%, preferably 80% to 95%.

[0018] In the above-mentioned start-up method, the system pressure is maintained at 13-20 MPa throughout the entire vulcanization process. The system pressure refers to the top outlet pressure of the cold high-pressure separator.

[0019] In the above-mentioned start-up methods, the catalyst reverse sulfidation process refers to the flow direction of the material through the catalyst during the sulfidation process being opposite to the flow direction of the liquid raw material material through the catalyst during normal production.

[0020] In the above start-up method, during the catalyst reverse sulfidation process, all feeds (including diesel, wax oil, hydrogen and sulfiding agent) enter the reactor from the bottom of the last reactor and flow in reverse until they are discharged from the top of the first reactor.

[0021] In the above-described start-up method, the establishment of a reverse full-cycle diesel fuel flow process includes the following steps: the start-up diesel fuel enters the reactor from the bottom of the last reactor, flows counter-currently until it exits from the top of the first reactor, and the stream exiting from the top of the first reactor enters a hot high-pressure separator (i.e., hot high-pressure separator), where it is separated into hot high-pressure liquid and hot high-pressure gas. The obtained hot high-pressure liquid enters a hot low-pressure separator (i.e., hot low-pressure separator), where the separated hot low-pressure liquid is used as circulating oil, and the obtained hot high-pressure gas enters a cold high-pressure separator (i.e., cold high-pressure separator), where the separated cold high-pressure gas is used as circulating hydrogen. The circulating oil and circulating hydrogen are then used as feed to the last reactor. During the establishment of the reverse full-cycle diesel fuel flow process, the reactor temperature is controlled to not exceed 230°C, preferably not exceeding the decomposition temperature of the sulfurizing agent.

[0022] In the above-mentioned start-up method, diesel full-cycle pre-sulfurization is carried out after the diesel reverse full-cycle is established. Under the condition of diesel reverse full-cycle, a sulfurizing agent is added to the feed and the feed passes through the decarbonization catalyst, desulfurization catalyst, demetallization catalyst and protective agent in sequence. After hydrogen sulfide penetrates the catalyst bed, isothermal sulfurization is carried out.

[0023] In the above start-up method, the temperature is controlled at 210–230°C before hydrogen sulfide penetrates the catalyst bed. Preferably, the reactor is heated at a rate of 5–20°C / h. The conditions for hydrogen sulfide penetration of the catalyst bed are that hydrogen sulfide is first detected in the circulating hydrogen, and the concentration is 0.1 vol.%–0.5 vol.%, preferably 0.1 vol.%–0.2 vol.%.

[0024] In the above-mentioned start-up method, the isothermal sulfidation is carried out at a constant temperature of 220-230°C for 4-8 hours. After hydrogen sulfide penetrates the catalyst bed, the hydrogen sulfide content in the circulating hydrogen is controlled to be no less than 0.2 vol.%, preferably 0.2 vol.% to 1.0 vol.%.

[0025] In the above-mentioned start-up method, after isothermal vulcanization, the temperature is further increased to carry out the first non-isothermal vulcanization.

[0026] In the above-mentioned start-up method, the first non-isothermal sulfidation involves controlling the sulfidation reaction temperature of the demetallization catalyst and protective agent to be lower than the sulfidation reaction temperature of the desulfurization and decarbonization catalysts. Further, the sulfidation reaction temperature of the demetallization catalyst and protective agent is controlled to be 20–50°C lower than the sulfidation reaction temperature of the desulfurization and decarbonization catalysts, preferably 25–35°C. Specifically, this can be achieved by injecting cold hydrogen into the inlet of the reactor containing the desulfurization catalyst unit to control the sulfidation reaction temperature of the demetallization catalyst and protective agent to be lower than the reaction temperature of the desulfurization and decarbonization catalysts.

[0027] In the above-mentioned start-up method, the bed sulfidation temperature of the decarbonization catalyst and the desulfurization catalyst in the first non-isothermal sulfidation is 280-290℃, the bed sulfidation temperature of the demetallization catalyst and the protective agent is 230-265℃, preferably 240-260℃, and the sulfidation time is 4-8h.

[0028] In the above start-up methods, the sulfidation temperature of the decarbonization catalyst and desulfurization catalyst bed can be adjusted by the furnace outlet temperature, and the sulfidation temperature of the demetallization catalyst and protective agent bed can be controlled by the bed cold hydrogen medium.

[0029] In the above start-up method, after isothermal sulfidation, when the bed sulfidation temperature of the decarbonization catalyst and desulfurization catalyst is 230–260°C, the start-up diesel is switched to wax oil, and then wax oil full-cycle pre-sulfidation, i.e., the first non-isothermal sulfidation, is performed. During the process of rising from the isothermal sulfidation temperature to the first non-isothermal sulfidation temperature and during the first non-isothermal sulfidation stage, the hydrogen sulfide content in the circulating hydrogen is controlled to be not less than 0.5 vol.%, preferably 0.5 vol.% to 1.0 vol.%. In the above start-up method, during the full-cycle pre-sulfidation process, before the reactor temperature reaches 260°C, the method for controlling the concentration of hydrogen sulfide in the circulating hydrogen can be adjusted according to the amount of sulfiding agent injected. After the reactor temperature reaches 260°C, the method for controlling the concentration of hydrogen sulfide in the circulating hydrogen can be adjusted according to the amount of sulfiding agent injected and / or the circulating oil feed load.

[0030] In the above start-up method, water is injected into the system when the temperature of the reactor containing the desulfurization and residual carbon removal catalyst rises to 260-280°C. The water injection points are before the inlet of the heat exchanger at the top of the hot high-pressure separator and before the inlet of the high-pressure air cooler. To prevent ammonium salt crystallization from clogging the pipes, water can be injected into the pipes to dissolve the ammonium salts. Hydrogen sulfide and ammonia will form ammonium hydrosulfide crystals below 120°C, and hydrogen chloride and ammonia will form ammonium chloride crystals below 200°C.

[0031] In the above-mentioned start-up method, the non-full-circulation pre-sulfurization of fresh sulfur-containing wax oil is carried out after the full-circulation pre-sulfurization of wax oil. Without adding a sulfurizing agent (i.e., without additional sulfurizing agent), fresh sulfur-containing wax oil is used as the feed to the last reactor, and the circulating oil undergoes a multi-part circulation (i.e., non-circulation or partial circulation) sulfurization process. Specifically, in the non-circulation pre-sulfurization process, without adding a sulfurizing agent, fresh sulfur-containing wax oil, or fresh sulfur-containing wax oil and a portion of the circulating oil, enters the last reactor from the bottom and flows counter-currently until it exits from the top of the first reactor. The stream exiting from the top of the first reactor enters the hot high-pressure separator (i.e., hot high-pressure separator), where it is separated into hot high-pressure liquid and hot high-pressure gas. The obtained hot high-pressure liquid enters the hot low-pressure separator (i.e., hot low-pressure separator), where the separated hot low-pressure liquid is used as circulating oil (this circulating oil undergoes multi-part circulation). The obtained hot high-pressure gas enters the cold high-pressure separator (i.e., cold high-pressure separator), where the separated cold high-pressure gas is used as circulating hydrogen. The circulating hydrogen and the circulating oil used for circulation continue to be used as the feed to the last reactor.

[0032] In the above-mentioned start-up method, the non-full-cycle pre-sulfurization of fresh sulfur-containing wax oil involves controlling the sulfurization reaction temperature of the demetallization catalyst and the protective agent to be lower than the sulfurization reaction temperature of the decarbonization catalyst and the desulfurization catalyst. Further, the sulfurization reaction temperature of the demetallization catalyst and the protective agent is controlled to be 20-50°C lower than the sulfurization reaction temperature of the desulfurization and decarbonization catalysts, preferably 30-50°C.

[0033] In the above-mentioned start-up method, the sulfidation reaction temperature of the decarbonization catalyst and the desulfurization catalyst in the non-full-cycle pre-sulfurization of fresh sulfur-containing wax oil is 310-330℃, and the sulfidation reaction temperature of the demetallization catalyst and the protective agent is 260-290℃, preferably 270-280℃. The constant-temperature sulfidation is carried out for 2-8 hours. During the non-full-cycle pre-sulfurization stage of fresh sulfur-containing wax oil, the hydrogen sulfide content in the circulating hydrogen is controlled to be not less than 0.7 vol.%, preferably 0.7-1.0 vol.%.

[0034] In the above-mentioned start-up method, during the non-full-cycle pre-sulfurization process of the fresh sulfur-containing wax oil, the concentration of hydrogen sulfide in the circulating hydrogen can be adjusted based on the wax oil feed load, the sulfur content of the wax oil, the amount of circulating oil used for circulation, and the hydrogen sulfide content in the circulating hydrogen used for circulation. Specifically, the method for adjusting the hydrogen sulfide content in the circulating hydrogen used for circulation is to start the circulating hydrogen desulfurization system to treat the gas separated by the cold high-pressure separator to remove hydrogen sulfide before using it as circulating hydrogen. The circulating hydrogen desulfurization system can use a circulating hydrogen desulfurization tower that removes hydrogen sulfide from the circulating hydrogen using lean amine solution.

[0035] In the above-mentioned start-up method, preferably, during the vulcanization process, the feed rate of diesel or wax oil is controlled to be above 60 wt.% of the design processing load. Preferably, the feed rate of diesel or wax oil is 60 wt.% to 90 wt.% of the design processing load.

[0036] In the above-described start-up method, the vulcanizing agent is preferably at least one of carbon disulfide and dimethyl disulfide. Preferably, the preferred injection temperature for carbon disulfide is 180–190°C, and the preferred injection temperature for dimethyl disulfide is 190–200°C.

[0037] In the above-mentioned start-up method, during the non-full-cycle pre-sulfurization process of fresh sulfur-containing wax oil, the sulfur-containing wax oil is preferably straight-run wax oil with a sulfur content ranging from 1.5 wt.% to 3.5 wt.%, preferably from 2.0 wt.% to 3.5 wt.%.

[0038] In the above-mentioned start-up method, before the fresh sulfur-containing wax oil undergoes non-full-cycle pre-sulfurization, straight-run wax oil is preferred. There are no particular restrictions on the sulfur content of the wax oil used.

[0039] In the above-mentioned start-up method, preferably, the initial hourly injection amount of the sulfiding agent is 3wt% to 6wt% of the theoretical sulfur required for complete sulfidation of all catalysts.

[0040] In the above start-up methods, quench hydrogen can be used to cool the reactor. A portion of the recycled hydrogen can be used as quench hydrogen to cool the reactor that needs cooling, while another portion can be reused as reactor feed.

[0041] In the above-mentioned start-up method, after sulfidation is completed, the reverse operation process is switched to the normal forward operation process, that is, the residue oil feedstock and hydrogen are fed from the first reactor and discharged from the last reactor.

[0042] In the above-described start-up method, the catalyst loading, airtightness check, and catalyst pre-sulfurization preparation steps for the fixed-bed residue hydrotreating unit can be performed using conventional methods in the art, and there are no particular limitations in this invention. The fixed-bed residue hydrotreating unit is based on a conventional fixed-bed residue hydrotreating unit in the art, with two additional pipelines added between the first and last reactors. These pipelines are used for feeding the last reactor and discharging the first reactor into the subsequent separation process during the reverse sulfurization process, respectively, to achieve the reverse sulfurization operation of this invention. The catalyst pre-sulfurization preparation step includes conventional steps such as wetting the catalyst and removing sludge oil, the purpose of which is to wet the catalyst and remove powder carried in by the catalyst. The start-up oil used for wetting the catalyst can be selected from at least one of straight-run diesel and / or straight-run wax oil, preferably wax oil. During the catalyst pre-sulfurization preparation step, the reactor temperature should not exceed 230°C, preferably not exceeding the decomposition temperature of the sulfiding agent. During the catalyst pre-sulfurization preparation step, the feed rate of the start-up oil should be at least 60 wt.% of the design load, preferably 60 wt.% to 90 wt.%.

[0043] In the above-described start-up method, the fixed-bed residue hydrotreating unit employs at least one hydrotreating reactor. More preferably, multiple hydrotreating reactors are arranged in series, and even more preferably, three to five hydrotreating reactors are arranged.

[0044] In the above-mentioned start-up method, the catalyst generally includes a residue hydrotreating protection catalyst, a residue hydrodemetallization catalyst, a residue hydrodesulfurization catalyst, and a residue hydrodecarbonization catalyst. Specifically, based on the total loading volume of the fixed-bed residue hydrotreating catalyst, the residue hydrotreating protection catalyst accounts for 3%–10% of the total loading volume, the residue hydrodemetallization catalyst accounts for 30%–60%, and the sum of the loading volumes of the residue hydrodesulfurization catalyst and the residue hydrodecarbonization catalyst accounts for 37%–67% of the total loading volume. The catalyst loading sequence can adopt a conventional gradation sequence, generally ensuring that the feedstock sequentially contacts the residue hydrotreating protection catalyst, the residue hydrodemetallization catalyst, the residue hydrodesulfurization catalyst, and the residue hydrodecarbonization conversion catalyst during normal production. The catalysts for protecting residual oil hydrotreating, demetallizing residual oil hydrotreating, desulfurizing residual oil hydrotreating, and carbon removal conversion of residual oil can be catalysts with corresponding functions commonly used in this field, such as the CEN, FZC, ZTN, and ZTS series of residual oil hydrotreating catalysts produced by the Catalyst Branch of China Petroleum & Chemical Corporation.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. The inventors discovered through research that in a fixed-bed residue hydrotreating unit, the catalyst in the tail reactor has high activity, while the catalyst in the head reactor has low activity. The catalyst in the tail reactor requires more hydrogen sulfide for sulfidation than that in the head reactor. Existing methods require the injection of excess sulfiding agent to ensure complete sulfidation of the catalyst in the tail reactor. Further research by the inventors revealed that, using the reverse sulfidation method of this invention, the sulfiding agent first enters the tail reactor and reacts with the highly active catalyst requiring more hydrogen sulfide, and then reacts with the less active catalyst requiring less hydrogen sulfide, eliminating the need for excessive sulfiding agent injection. Furthermore, after switching wax oil, the reverse-introduced wax oil, under the action of the highly active catalyst in the tail reactor, easily removes organic sulfur from the starting wax oil at a lower temperature to generate hydrogen sulfide, which participates in the catalyst's sulfidation reaction. This fully utilizes the organic sulfur contained in the wax oil, thereby reducing the amount of sulfiding agent injected. Therefore, the sulfidation method of this invention can significantly save on the amount of sulfiding agent used.

[0047] 2. The vulcanization method of this invention is simple to operate. It shortens the switching time of the vulcanization medium by adopting a mode in which wax oil replaces diesel oil while the reactor is heated.

[0048] 3. Existing methods require the injection of excessive sulfiding agent, generating excessive hydrogen sulfide. A large amount of hydrogen sulfide present in the circulating hydrogen does not participate in the reaction, which will cause corrosion to equipment such as high-pressure air coolers. The sulfidation method of this invention utilizes the characteristics of the catalyst and reaction, ensuring complete sulfidation of the catalyst without the need for excessive hydrogen sulfide. The hydrogen sulfide concentration in the circulating hydrogen is already low by the time it reaches the high-pressure air cooler and other equipment. Furthermore, the circulating hydrogen desulfurization system can be started earlier, further effectively reducing the hydrogen sulfide content in the circulating hydrogen. Therefore, this invention can effectively reduce equipment corrosion and lower the risk of equipment corrosion.

[0049] 4. In the sulfidation method of the present invention, the material flows counterclockwise from the bottom to the top of the reactor, which increases the porosity between the catalyst beds and prevents carbon buildup and coking between catalyst particles during the sulfidation process.

[0050] 5. The vulcanization method of this invention has a fast heating rate and low furnace load. During the vulcanization heating process, the heat source for raising the temperature is mainly provided by the heat source device. In addition, the heat released by the vulcanization reaction can also appropriately raise the temperature. Due to the high catalytic activity of the downstream reactor, the heat release of the reaction is greater than that of the first reactor. Compared with the existing technology where a large amount of heat released by the tail reactor cannot be utilized, the vulcanization method of this invention uses the material to drive the greater amount of heat released by the tail reactor to the first reactor, which is conducive to the rapid increase of the overall reactor temperature. Because the reverse heating rate is fast, the target temperature can be reached in a specified time by appropriately reducing the reactor inlet temperature. There is no need to heat the reactor feed to a high temperature through the furnace, thus reducing the furnace load. This advantage is more obvious as the reactor temperature increases. Reverse vulcanization can make full use of the reaction heat released during the vulcanization process, reduce heat exchange steps, and avoid heat loss caused by frequent heat exchange processes.

[0051] 6. The vulcanization method of the present invention can significantly shorten the vulcanization time.

[0052] 7. The sulfidation method of the present invention performs sulfidation of the catalyst in reverse, without the need for excessive hydrogen sulfide, and avoids the situation in the first reactor of the prior art where the low-activity catalyst is overactivated, thereby avoiding the problem of easy coking of the catalyst in the early stage of the residue oil reaction.

[0053] 8. In the sulfidation method of the present invention, the appropriate sulfidation of the protective agent and the demetallizing agent helps to reduce the initial reaction activity, reduce the pore blockage caused by the initial coking and deactivation of the catalyst, improve the overall metal-holding capacity, and extend the operating cycle of the device. The desulfurization and decarbonization catalyst can complete high-temperature complete sulfidation in a short time, which is beneficial for controlling the sulfidation steps and saving sulfidation time.

[0054] 9. In the sulfidation method of the present invention, controlling the degree of sulfidation of the protective agent and the demetallizing agent is beneficial to reducing the heat of the pre-reactor and reducing the temperature rise, thereby reducing the risk of radial temperature difference and hot spot generation. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0056] Appendix Figure 1 The markings are explained below:

[0057] 1. Fresh raw materials; 2, 4, 6, 16, 18, 23. Three-way valves; 5. Forward flow from the heater outlet; 7. Top flow line of the first reactor; 8. Fixed-bed first reactor; 9. Top flow line of the second reactor; 10. Fixed-bed second reactor; 11. Top flow line of the third reactor; 12. Fixed-bed third reactor; 13. Top flow line of the fourth reactor; 14. Fixed-bed fourth reactor; 15, 17. Bottom flow lines of the fourth reactor; 19. High-temperature fraction; 20. High-temperature liquid fraction; 21. Low-temperature fraction; 2 2. Hot low-temperature liquid separator; 24. Circulating line; 25. Circulating feed pump; 26. Reverse flow line from the heater outlet; 27. Reverse flow line from the top of the first reverse reactor; 28. Hot high-temperature gas separator; 29. ​​Air cooling; 30. Cold high-temperature gas separator; 31. Cold high-temperature gas separator; 33. Circulating hydrogen compressor; 34. Quenched hydrogen; 35. Circulating hydrogen; 36. Fresh hydrogen; 37. Fresh hydrogen compressor; 38. Mixed hydrogen; 39. Cold high-temperature liquid separator; 40. Hot low-temperature gas separator; 41. Hydrogenated slag line; 42. Sulfating agent; 43. Circulating hydrogen desulfurization tower; 44. Lean amine solution; 45. Rich amine solution. Detailed Implementation

[0058] The starting method, its function, and its effects provided by the present invention will be further described below with reference to the accompanying drawings and embodiments, but this does not limit the present invention. Many devices, such as pumps, heat exchangers, heating furnaces, air coolers, and stripping towers, are omitted in the figures, but these are well known to those skilled in the art.

[0059] In this invention, circulating hydrogen refers to the cold high-pressure gas obtained by the cold high-pressure separator (i.e., cold high-pressure separator) as circulating hydrogen, and the concentration of hydrogen sulfide in the circulating hydrogen refers to the concentration of hydrogen sulfide in the cold high-pressure gas.

[0060] In this invention, the reactor temperature is a weighted temperature calculated based on the weight of the catalyst loading volume in each reactor.

[0061] In this invention, the sulfidation degree of the catalyst metal element was determined by X-ray photoelectron spectroscopy (XPS). Specific processing methods are detailed in the literature Hanet et al., Journal of Materials Chemistry 2012, 22:25340. Through energy spectrum curve fitting analysis, the ratio of oxidized and sulfided metals was obtained separately, and the percentage of sulfided metal content to the total metal content is the sulfidation degree.

[0062] The initiation vulcanization process (reverse vulcanization process) of this invention, such as... Figure 1As shown, the system includes four reactors, namely reactor 8 (first reactor), reactor 10 (second reactor), reactor 12 (third reactor), and reactor 14 (fourth reactor). The process includes: the vulcanizing medium is heated by furnace 3, and then flows through the reverse flow line 26 at the furnace outlet controlled by three-way valve 4. The flow then flows through the bottom flow line 15 of reactor 14 into the fixed-bed reactor 14 via three-way valve 16. Subsequently, the flow enters from the bottom of reactor 12 via top flow line 13, reactor 20 via top flow line 11, reactor 11 via top flow line 9, and reactor 18 via bottom flow line 9. The flow then flows from the top of reactor 1. After flowing out of logistics line 7, it is controlled by three-way valve 6 to flow into the reverse top logistics line 27 of the tower, and then enters the hot high-temperature fraction 19 through three-way valve 18. The hot high-temperature liquid 20 enters the hot low-temperature fraction 21. The hot low-temperature liquid 22 flows through three-way valve 23 to the circulation line 24, mixes with the sulfurizing agent 42, and then mixes with mixed hydrogen 38 after passing through the circulation feed pump and returns to the heating furnace inlet. The hot high-temperature gas 28 enters the cold high-temperature fraction 30 after passing through heat exchange equipment such as air cooler 31. The cold high-temperature gas 31 is pressurized and divided into quench hydrogen 34 and circulating hydrogen 35. The fresh hydrogen 36 is pressurized by the fresh hydrogen compressor 37 and mixed with the circulating hydrogen to form mixed hydrogen 38. When the circulating hydrogen desulfurization system is activated, the circulating hydrogen is separated by the cold high-pressure separator and enters from the bottom of the circulating hydrogen desulfurization tower 43. The lean amine liquid 44 enters from the top of the desulfurization tower. After the two phases come into countercurrent contact, the desulfurized circulating hydrogen flows out from the top of the desulfurization tower and enters the circulating hydrogen compressor. The lean amine liquid absorbs hydrogen sulfide and generates rich amine liquid 45, which flows out from the bottom of the desulfurization tower for regeneration.

[0063] The existing conventional start-up vulcanization process follows the normal production process, such as... Figure 1 As shown, the system includes four reactors, namely reactor 8 (first reactor), reactor 10 (second reactor), reactor 12 (third reactor), and reactor 14 (fourth reactor). The process includes: the vulcanizing medium is heated by the heating furnace 3, and then controlled by the three-way valve 4 to flow through the positive flow line 5 at the outlet of the heating furnace. The flow is then controlled by the three-way valve 6 to flow sequentially from the top flow 7 of reactor 1 into fixed bed reactor 8, the top flow 9 of reactor 2 into fixed bed reactor 2 into reactor 10, the top flow 11 of reactor 3 into fixed bed reactor 3 into reactor 12, the top flow 13 of reactor 4 into fixed bed reactor 4 into reactor 14, and the bottom flow 15 of reactor 4 into reactor 16. Controlled by three-way valves 16 and 18, the hot high-temperature fraction 20 enters the hot low-temperature fraction 21. The hot low-temperature fraction 22 flows through three-way valve 23 to the circulation line 24, mixes with the sulfurizing agent 44, and then mixes with the mixed hydrogen 38 after passing through the circulating feed pump and returns to the heating furnace inlet. The hot high-temperature fraction gas 28 enters the cold high-temperature fraction 30 after passing through heat exchange equipment such as air cooling 29. The cold high-temperature fraction gas 31 is pressurized and divided into quenched hydrogen 34 and circulating hydrogen 35. The fresh hydrogen 36 is pressurized by the fresh hydrogen compressor 37 and mixed with the circulating hydrogen to form mixed hydrogen 38.

[0064] The embodiments and comparative examples of the present invention adopt the following methods: Figure 1The fixed-bed residue hydrotreating unit comprises four reactors, namely, reactor 1, reactor 2, reactor 3, and reactor 4, in sequence. The catalysts used are hydroprotection catalysts (FZC-103D, FZC-103E), hydrodemetallization catalysts (FZC-28A, FZC-204A), hydrodesulfurization catalysts (FZC-33BT), and hydrodenitrogenation catalysts (FZC-41BT). Reactor 1 is loaded with equal volumes of FZC-103D and FZC-103E catalysts, reactor 2 is loaded with equal volumes of FZC-28A and FZC-204A catalysts, reactor 3 is loaded with FZC-33BT catalysts, and reactor 4 is loaded with FZC-41BT catalysts. The loading volume ratio of reactor 1:2:3:4 is 15:45:25:15, and the total catalyst loading is 1000 ml. The catalyst gradation and sulfiding agent used in the embodiments and comparative examples of this invention are the same. The start-up diesel oil used in the embodiments and comparative examples is straight-run diesel oil. Except for the start-up wax oil used in Example 2, which is high-sulfur straight-run wax oil, the other embodiments and comparative examples use low-sulfur straight-run wax oil, the properties of which are shown in Table 1. The sulfiding agent used is dimethyl disulfide. A comparison of the main conditions of the catalyst sulfidation process in the embodiments and comparative examples of this invention is shown in Table 2. The properties of the feedstock oil are shown in Table 3. The main evaluation conditions are shown in Table 4. The evaluation results of the embodiments and comparative examples are shown in Table 5.

[0065] In the embodiments and comparative examples of this invention, hydrogen sulfide penetration of the catalyst bed refers to the detection of a hydrogen sulfide concentration in the circulating hydrogen that is higher than 0.1 vol.% after the sulfiding agent is first injected.

[0066] Table 1. Properties of the starting oil used in each example.

[0067] project Straight-run diesel Low-sulfur straight-run wax oil High-sulfur straight-run wax oil S, wt.% 0.76 1.64 3.28 N, μg / g 32 420 730 Distillation range, °C ASTM D-86 ASTM D-1160 ASTM D-1160 Initial boiling point 210 352 360 Final boiling point 358 522 538

[0068] Example 1

[0069] In this embodiment, the sulfidation method of the present invention is used. After the catalyst is loaded and the airtightness is checked in the fixed bed residue oil hydrogenation unit, hydrogen is introduced and the pressure of the reaction system is controlled at 17.5 MPa. The temperature is gradually increased and start-up diesel is introduced into the reaction system from the first reactor to wet the catalyst. The waste oil is thrown out to clean the catalyst. When the throwing out is completed, the reactor temperature is controlled to reach 160°C.

[0070] Initiate the catalyst reverse sulfidation process:

[0071] First, a diesel reverse full circulation process is established. Diesel and hydrogen are introduced from the bottom of the last reactor and flow in reverse until they are discharged from the top of the first reactor, thus establishing the diesel reverse full circulation process. During the establishment of the diesel reverse full circulation process, the reactor temperature is controlled to not exceed 170℃.

[0072] Then, a full-cycle pre-sulfurization process is carried out. At the inlet temperature of the fourth reactor (185℃), a sulfurizing agent is injected at a flow rate of 1.0 g / h. The diesel feed rate is controlled at 85 wt.% of the design load, i.e., 146 g / h. Simultaneously, the heater outlet temperature is increased to 225℃ at a rate of 10℃ / h. After ensuring a stable injection of the sulfurizing agent into the reaction system, the injection rate is increased to 2.8 g / h and maintained until hydrogen sulfide penetration occurs. Once the reaction temperatures of reactors one through four reach 225℃, the heating is stopped to allow hydrogen sulfide penetration. After hydrogen sulfide penetration, the hydrogen sulfide concentration in the circulating hydrogen is controlled at 0.2–1.0 vol.%, and sulfurization is carried out for 4 hours. Subsequently, the temperatures of reactors three and four are increased to 290℃ at a rate of 10℃ / h, and the temperatures of reactors one and two are increased to 260℃ at a rate of 5℃ / h. When the temperature of reactors three and four reaches 250°C, the system is switched to open circuit with fresh wax oil to replace the diesel fuel in the unit. After the wax oil is switched, the system is switched to full wax oil circulation. During the heating process, the amount of sulfiding agent injected is gradually reduced until the injection of sulfiding agent is stopped, while ensuring that the hydrogen sulfide content in the circulating hydrogen is 0.5-1.0 vol.%. When the temperature of reactors three and four reaches 260°C, water injection begins. When the temperature of reactors three and four reaches 290°C and the temperature of reactors one and two reaches 260°C, the first non-isothermal sulfidation is carried out for 4 hours, during which the hydrogen sulfide content in the circulating hydrogen is controlled to be 0.5-1.0 vol.%.

[0073] Next, a non-full-circulation pre-sulfurization process for the wax oil is carried out. After the first non-isothermal sulfurization is completed, lean amine solution is added, and the circulating hydrogen desulfurization tower is turned on, changing the full circulation process to a fully open circuit (i.e., the circulating oil is not circulated). Fresh wax oil is injected at 85 wt.%, or 146 g / h, of the design load. At the same time, the temperature of the third and fourth reactors is increased to 320℃ at 5℃ / h, and the temperature of the first and second reactors is increased to 280℃ at 2.5℃ / h. After the third and fourth reactors reach 320℃ and the first and second reactors reach 280℃, the temperature is kept constant for 4 hours to end the sulfurization. During this period, the hydrogen sulfide content in the circulating hydrogen is controlled at 0.7~1.0 vol.%.

[0074] After sulfidation, the sulfidation degrees of the protective agent, demetallization catalyst, desulfurization catalyst, and decarbonization catalyst were 62%, 62%, 94%, and 94%, respectively. During the initial operation, the temperature rise of the reactor from reactor one to reactor four was 12.2℃, 23.1℃, 25.5℃, and 18.3℃, respectively.

[0075] Example 2

[0076] In this embodiment, the sulfidation method of the present invention is used. After the catalyst is loaded and the airtightness is checked in the fixed bed residue oil hydrogenation unit, hydrogen is introduced and the pressure of the reaction system is controlled at 18.3 MPa. The temperature is gradually increased and start-up diesel is introduced into the reaction system from the first reactor to wet the catalyst. The waste oil is thrown out to clean the catalyst. When the throwing is completed, the reactor temperature is controlled to reach 160°C.

[0077] Initiate the catalyst reverse sulfidation process:

[0078] First, a diesel reverse full circulation process is established. Diesel and hydrogen are introduced from the bottom of the last reactor and flow in reverse until they are discharged from the top of the first reactor, thus establishing the diesel reverse full circulation process. During the establishment of the diesel reverse full circulation process, the reactor temperature is controlled to not exceed 185℃.

[0079] Then, a full-cycle pre-sulfurization process is carried out. At a reactor temperature of 185℃, a sulfurizing agent is injected at a flow rate of 2.0 g / h. The diesel feed rate is controlled at 90 wt.% of the design load, i.e., 155 g / h. Simultaneously, the furnace outlet temperature is increased to 230℃ at a rate of 10℃ / h. After ensuring a stable injection of the sulfurizing agent into the reaction system, the injection rate is increased to 3.0 g / h and maintained until hydrogen sulfide penetration occurs. Once the reaction temperatures of reactors one through four reach 230℃, the heating is stopped to allow hydrogen sulfide penetration. After hydrogen sulfide penetration, the hydrogen sulfide concentration in the circulating hydrogen is controlled at 0.2–1.0 vol.%, and sulfurization is carried out for 4 hours. Subsequently, the temperatures of reactors three and four are increased to 290℃ at a rate of 15℃ / h, and the temperatures of reactors one and two are increased to 255℃ at a rate of 5℃ / h. When the temperature of reactors three and four reaches 260°C, the system is switched to open circuit with fresh wax oil to replace the diesel fuel in the unit. After the wax oil is switched, the system is switched to full wax oil circulation. During the heating process, the amount of sulfiding agent injected is gradually reduced until the injection of sulfiding agent is stopped, while ensuring that the hydrogen sulfide content in the circulating hydrogen is 0.5-1.0 vol.%. When the temperature of reactors three and four reaches 260°C, water injection begins. When the temperature of reactors three and four reaches 290°C and the temperature of reactors one and two reaches 255°C, the first non-isothermal sulfidation is carried out for 4 hours, during which the hydrogen sulfide content in the circulating hydrogen is controlled to be 0.5-1.0 vol.%.

[0080] The wax oil undergoes a non-full-cycle pre-sulfurization process. After the first non-isothermal sulfurization, lean amine solution is introduced, and the circulating hydrogen desulfurization tower is started, changing the full-cycle process to a partial-cycle process. The total feed rate at the reactor inlet is adjusted to 155 g / h, which is 90 wt.% of the design load, with a fresh wax oil to circulating oil mass ratio of 1:1. Simultaneously, the temperatures of the third and fourth reactors are increased at 5℃ / h towards 310℃, and the temperatures of the first and second reactors are increased at 5℃ / h towards 270℃. After the third and fourth reactors reach 310℃ and the first and second reactors reach 270℃, the sulfurization is stopped after 4 hours of constant temperature maintenance, during which the hydrogen sulfide content in the circulating hydrogen is controlled at 0.7–1.0 vol.%.

[0081] After sulfidation, the sulfidation degrees of the protective agent, demetallization catalyst, desulfurization catalyst, and decarbonization catalyst were 53%, 53%, 86%, and 86%, respectively. During the initial operation, the temperature rise of the reactor from reactor one to reactor four was 11.3℃, 22.0℃, 24.4℃, and 18.6℃, respectively.

[0082] Example 3

[0083] In this embodiment, the sulfidation method of the present invention is used. After the catalyst is loaded and the airtightness is checked in the fixed bed residue oil hydrogenation unit, hydrogen is introduced and the pressure of the reaction system is controlled at 17.9 MPa. The temperature is gradually increased and start-up diesel is introduced into the reaction system from the first reactor to wet the catalyst. The waste oil is thrown out to clean the catalyst. When the throwing is completed, the reactor temperature is controlled to reach 170°C.

[0084] Initiate the catalyst reverse sulfidation process:

[0085] First, a diesel reverse full circulation process is established. Diesel and hydrogen are introduced from the bottom of the last reactor and flow in reverse until they are discharged from the top of the first reactor, thus establishing the diesel reverse full circulation process. During the establishment of the diesel reverse full circulation process, the reactor temperature is controlled to not exceed 190℃.

[0086] Then, a full-cycle pre-sulfurization process is carried out. At a reactor temperature of 190℃, a sulfurizing agent is injected at a flow rate of 2.0 g / h. The diesel feed rate is controlled at 80 wt.% of the design load, i.e., 138 g / h. Simultaneously, the furnace outlet temperature is increased to 230℃ at a rate of 10℃ / h. After ensuring a stable injection of the sulfurizing agent into the reaction system, the injection rate is increased to 3.5 g / h and maintained until hydrogen sulfide penetration occurs. Once the reaction temperature reaches 230℃ from the first to the fourth reactor stage, the heating is stopped to allow hydrogen sulfide penetration. After hydrogen sulfide penetration, the hydrogen sulfide concentration in the circulating hydrogen is controlled at 0.2–1.0 vol.%, and sulfurization is carried out for 4 hours. Subsequently, the temperatures of the third and fourth reactor stages are increased to 290℃ at a rate of 10℃ / h, and the temperatures of the first and second reactor stages are increased to 260℃ at a rate of 5℃ / h. When the temperature of the third and fourth reactors reaches 240°C, the system is switched to open circuit with fresh wax oil to replace the diesel fuel in the unit. After the wax oil switching is completed, the system is switched to full wax oil circulation. During the heating process, the amount of sulfiding agent injected is gradually reduced until the injection of sulfiding agent is stopped, while ensuring that the hydrogen sulfide content in the circulating hydrogen is 0.5-1.0 vol.%. When the temperature of the third and fourth reactors reaches 260°C, water injection begins. When the temperature of the third and fourth reactors reaches 290°C, the temperature of the first and second reactors is raised to 260°C for the first non-isothermal sulfidation, which lasts for 4 hours. During this period, the hydrogen sulfide content in the circulating hydrogen is controlled to be 0.5-1.0 vol.%.

[0087] Next, a non-full-circulation pre-sulfurization process for the wax oil is carried out. After the first non-isothermal sulfurization is completed, lean amine solution is added, and the circulating hydrogen desulfurization tower is turned on, changing the full circulation process to a fully open circuit (i.e., the circulating oil is not circulated). Fresh wax oil is injected at 80 wt.% / h of the design load, which is 138 g / h. At the same time, the temperature of the third and fourth reactors is increased to 320℃ at 10℃ / h, and the temperature of the first and second reactors is increased to 270℃ at 5℃ / h. When the temperature of the third and fourth reactors reaches 320℃ and the temperature of the first and second reactors reaches 270℃, the sulfurization is completed after 8 hours of constant temperature. During this period, the hydrogen sulfide content in the circulating hydrogen is controlled to be 0.7-1.0 vol.%.

[0088] After sulfidation, the sulfidation degrees of the protective agent, demetallization catalyst, desulfurization catalyst, and decarbonization catalyst were 53%, 53%, 94%, and 94%, respectively. During the initial operation, the temperature rise of the reactor from reactor one to reactor four was 11.0℃, 22.1℃, 28.2℃, and 20.7℃, respectively.

[0089] Comparative Example 1

[0090] This comparative example uses a conventional sulfidation method (operating according to the normal production process). After the catalyst is loaded and the airtightness is checked in the fixed-bed residue hydrotreating unit, hydrogen is introduced and the pressure of the reaction system is controlled at 17.5 MPa. The temperature is gradually increased, and start-up diesel is introduced into the reaction system from the first reactor to wet the catalyst. Waste oil is thrown out to clean the catalyst. After the waste oil is thrown out, start-up diesel and hydrogen are introduced from the top of the first reactor and passed through the second and third reactors in a forward direction until they are discharged from the bottom of the fourth reactor, establishing a full circulation of start-up diesel. The reactor temperature is controlled to reach 170°C.

[0091] Start the catalyst sulfidation process:

[0092] The sulfurizing agent was initially injected at a flow rate of 1.5 g / h, while the furnace outlet temperature was increased to 225°C at a rate of 5°C / h. After ensuring a stable injection of the sulfurizing agent into the reaction system, the injection rate was increased to 3.0 g / h and maintained until hydrogen sulfide permeated. When the reaction temperature reached 225°C, the heating was stopped to allow hydrogen sulfide to permeate. After hydrogen sulfide permeation, and the hydrogen sulfide concentration in the circulating hydrogen was 0.2–1.0 vol.%, the first isothermal sulfurization was carried out for 8 hours. Subsequently, the reactor temperature was increased to 290°C at a rate of 5°C / h. When the temperature reached 250°C, the system was switched to a fully open circuit, injecting fresh wax oil to displace the diesel fuel in the unit. After the wax oil was switched, the system was switched to full circulation, during which sulfurizing agent was continuously injected. When the reactor temperature reached 290°C, the system was kept at a second isothermal temperature for 4 hours, during which the hydrogen sulfide content in the circulating hydrogen was controlled to be 1.0–1.5 vol.%.

[0093] Subsequently, the temperature of the reactor was increased from the first to the fourth reactor at a rate of 5°C / h towards 320°C. After reaching 320°C, the temperature was maintained at this level for 8 hours to complete the sulfidation process. During this period, the hydrogen sulfide content in the circulating hydrogen was controlled to be 1.5–2.0 vol.% by adjusting the amount of sulfiding agent injected.

[0094] After sulfidation, the sulfidation degrees of the protective agent, demetallization catalyst, desulfurization catalyst, and decarbonization catalyst were measured to be 85%, 85%, 85%, and 85%, respectively. During the initial operation, the temperature rise of the reactor from reactor one to reactor four was 13.5℃, 24.2℃, 23.0℃, and 17.1℃, respectively.

[0095] Comparative Example 2

[0096] After the catalyst loading and airtightness check are completed for the fixed bed residue hydrotreating unit, hydrogen is introduced and the pressure of the reaction system is controlled at 17.5 MPa. The temperature is gradually increased, and start-up diesel is introduced into the reaction system from the first reactor to wet the catalyst. The waste oil is then thrown out to clean the catalyst. When the throwing out is completed, the reactor temperature is controlled to reach 160℃.

[0097] Initiate the catalyst reverse sulfidation process:

[0098] First, a diesel reverse full circulation process is established. Diesel and hydrogen are introduced from the bottom of the last reactor and flow in reverse until they are discharged from the top of the first reactor, thus establishing the diesel reverse full circulation process. During the establishment of the diesel reverse full circulation process, the reactor temperature is controlled to not exceed 170℃.

[0099] Then, a full-cycle pre-sulfurization process is carried out. The temperature of each reactor (from the first to the fourth reactor) is 185℃, and the sulfurizing agent is injected at a flow rate of 1.0 g / h. The diesel feed rate is controlled at 85 wt.% of the design load, which is 146 g / h. Simultaneously, the furnace outlet temperature is increased to 225℃ at a rate of 10℃ / h. After ensuring a stable injection of the sulfurizing agent into the reaction system, the injection rate is increased to 2.8 g / h and maintained until hydrogen sulfide penetration occurs. Once the reaction temperature of each reactor (from the first to the fourth reactor) reaches 225℃, the heating is stopped, and hydrogen sulfide penetration is allowed. After hydrogen sulfide penetration, the hydrogen sulfide concentration in the circulating hydrogen is controlled at 0.2–1.0 vol.%, and sulfurization is carried out at 225℃ for 4 hours. The reactor temperature was then increased to 290℃ at a rate of 10℃ / h. When the temperature reached 250℃, the system was switched to a fully open circuit to inject fresh wax oil to replace the diesel fuel in the unit. After the wax oil was switched, the system was switched to full wax oil circulation. During the heating process, the amount of sulfiding agent injected was gradually reduced until the injection of sulfiding agent was stopped, while ensuring that the hydrogen sulfide content in the circulating hydrogen was 0.5-1.0 vol.%. When the reactor temperature reached 260℃, water injection was started. When the reactor temperature reached 290℃, the system was kept at this temperature for 4 hours for constant temperature sulfidation, during which the hydrogen sulfide content in the circulating hydrogen was controlled to be 0.5-1.0 vol.%.

[0100] The wax oil undergoes a non-full-circulation pre-sulfurization process. After sulfurization at a constant temperature of 290℃ for 4 hours, lean amine solution is added, and the circulating hydrogen desulfurization tower is turned on, changing the full-circulation process to a fully open circuit (i.e., the circulating oil is not circulated). Fresh wax oil is injected at 85 wt.%, or 146 g / h, of the design load. At the same time, the reactor temperature is increased to 320℃ at a rate of 5℃ / h. After reaching 320℃, the temperature is maintained for 4 hours to end the sulfurization. During this period, the hydrogen sulfide content in the circulating hydrogen is controlled to be 0.7–1.0 vol.% by adjusting the amount of sulfiding agent injected.

[0101] After sulfidation, the sulfidation degrees of the protective agent, demetallization catalyst, desulfurization catalyst, and decarbonization catalyst were 94%, 94%, 94%, and 94%, respectively. During the initial operation, the temperature rise of the reactor from reactor one to reactor four was 15.0℃, 25.2℃, 26.1℃, and 19.3℃, respectively.

[0102] Table 2 Comparison of main conditions in the sulfidation process of each catalyst example.

[0103]

[0104] *Note: Reactor temperature

[0105] As shown in Table 2, firstly, the sulfidation method of the present invention requires less time for catalyst sulfidation than the comparative example, which helps improve refinery efficiency; secondly, the sulfidation method of the present invention greatly saves the amount of sulfiding agent used; and thirdly, the hydrogen sulfide content in the circulating hydrogen during catalyst sulfidation is significantly lower than that in the comparative example, thereby reducing the corrosion of equipment by hydrogen sulfide.

[0106] In addition, after sulfidation, the feedstock oil (properties shown in Table 3) was switched into the units of each embodiment and comparative example. The catalyst after sulfidation was tested and evaluated, and samples were taken for analysis after the units had stabilized for 50 days. The overall reactor pressure drop of the embodiment units was lower than that of the comparative example. Notably, the pressure drop of the front reactor in the embodiment units was significantly lower than that in the comparative example, which is beneficial for long-term operation of the unit. The properties of the hydrogenated products are shown in Table 5. The hydrogenated residue oil of the embodiment units showed better performance than that of the comparative example in all indicators.

[0107] Table 3 Properties of Feed Oil

[0108]

[0109] Table 4 Main Operating Conditions

[0110]

[0111] Table 5. Properties of the hydrogenated products obtained in each example.

[0112]

[0113]

[0114] As shown in Tables 3 to 5, the devices using the above-mentioned catalyst sulfidation method all meet the technical requirements during actual operation. Furthermore, the impurity content of the hydrogenated residue oil and the reactor pressure drop in the examples are significantly lower than those in the comparative example. The sulfidation method of this invention is superior to traditional methods in terms of catalyst sulfidation effect, and there is still room for optimization within the proposed operating conditions. In addition, it has unique advantages such as simple operation, short operation time, and low sulfiding agent dosage.

Claims

1. A method for sulfiding a fixed bed residual hydroprocessing catalyst comprising: After the fixed-bed residual oil hydrogenation device completes catalyst loading, gas tightness inspection, and catalyst pre-sulfurization preparation steps, the catalyst reverse sulfuration process is started: first, an open operation diesel reverse full circulation process is established, then diesel full circulation pre-sulfurization is carried out, when the reactor temperature is 230-260℃, the open operation diesel is switched to wax oil, then wax oil full circulation pre-sulfurization is carried out, and finally, fresh sulfur-containing wax oil is used for non-full circulation pre-sulfurization, wherein the loaded catalysts are protective agent, metal removal catalyst, desulfurization catalyst, and residual carbon removal catalyst, and the sulfuration degrees of the desulfurization catalyst and the residual carbon removal catalyst are controlled to be complete sulfuration, and the sulfuration degrees of the protective agent and the metal removal catalyst are controlled to be incomplete sulfuration. In the process of establishing the open operation diesel reverse full circulation process, the open operation diesel enters the reactor from the bottom of the last reactor, flows reversely until the top of the first reactor, and is discharged from the top of the first reactor, the stream discharged from the top of the first reactor enters a hot high-pressure separator, i.e., a hot high separator, is separated to obtain hot high separator liquid and hot high separator gas, the obtained hot high separator liquid enters a hot low-pressure separator, i.e., a hot low separator, and is separated to obtain hot low separator liquid as circulating oil, the obtained hot high separator gas enters a cold high-pressure separator, i.e., a cold high separator, and is separated to obtain cold high separator gas as circulating hydrogen, and the circulating oil and the circulating hydrogen continue to be used as the feed of the last reactor, wherein, in the process of establishing the open operation diesel reverse full circulation process, the reactor temperature is controlled to be not more than 230℃. The diesel full circulation pre-sulfurization is carried out after the open operation diesel reverse full circulation is established, in the case of the open operation diesel reverse full circulation, a sulfuration agent is added to the feed, and the feed sequentially passes through the residual carbon removal catalyst, the desulfurization catalyst, the metal removal catalyst, and the protective agent, and after hydrogen sulfide penetrates the catalyst bed, isothermal sulfuration is carried out; the isothermal sulfuration is constant-temperature sulfuration for 4-8 h under the condition of 220-230℃, and the hydrogen sulfide content in the circulating hydrogen is controlled to be not less than 0.2 vol.% after the hydrogen sulfide penetrates the catalyst bed and before the isothermal sulfuration stage. The fresh sulfur-containing wax oil non-full circulation pre-sulfurization is carried out after the wax oil full circulation pre-sulfurization, in the case of not adding a sulfuration agent, fresh sulfur-containing wax oil is used as the feed of the last reactor, and the circulating oil is at most partially circulated in the sulfuration process.

2. The vulcanization method according to claim 1, characterized by, The sulfuration degree of the protective agent is 40%-70%, and / or, the sulfuration degree of the metal removal catalyst is 40%-70%, and / or, the sulfuration degree of the desulfurization catalyst is 75%-100%, and / or, the sulfuration degree of the residual carbon removal catalyst is 75%-100%.

3. The vulcanization method according to claim 2, characterized in that, The sulfuration degree of the protective agent is 50%-65%, and / or, the sulfuration degree of the metal removal catalyst is 50%-65%, and / or, the sulfuration degree of the desulfurization catalyst is 80%-95%, and / or, the sulfuration degree of the residual carbon removal catalyst is 80%-95%.

4. The vulcanization method according to claim 1, characterized by, The system pressure is maintained at 13-20 MPa in the whole process of the sulfuration method.

5. The vulcanization method according to claim 1, characterized by, In the process of establishing the open operation diesel reverse full circulation, the reactor temperature is controlled to be not more than the decomposition temperature of the sulfuration agent.

6. The vulcanization method according to claim 1, characterized by, The hydrogen sulfide content in the circulating hydrogen is controlled to be 0.2 vol.%-1.0 vol.% after the hydrogen sulfide penetrates the catalyst bed and before the isothermal sulfuration stage.

7. The vulcanization method according to claim 1, characterized by, After the isothermal sulfuration, the temperature is continuously increased to perform the first non-isothermal sulfuration, and the first non-isothermal sulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be lower than the sulfuration reaction temperature of the desulfurization and decarbon catalyst.

8. The vulcanization method according to claim 7, characterized in that, The first non-isothermal sulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be 20-50℃ lower than the sulfuration reaction temperature of the desulfurization and decarbon catalyst.

9. The vulcanization method according to claim 8, characterized in that, The first non-isothermal sulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be 25-35℃ lower than the sulfuration reaction temperature of the desulfurization and decarbon catalyst.

10. The vulcanization method according to claim 7, characterized by, In the first non-isothermal sulfuration, the bed sulfuration temperature of the decarbon catalyst and the desulfurization catalyst is 280-290℃, and the bed sulfuration temperature of the demetallization catalyst and the guard catalyst is 230-265℃, and the sulfuration time is 4-8h.

11. The vulcanization method according to claim 10, characterized in that, In the first non-isothermal sulfuration, the bed sulfuration temperature of the demetallization catalyst and the guard catalyst is 240-260℃.

12. The vulcanization method according to claim 1, characterized by, After the isothermal sulfuration, the feedstock is switched to the waxy oil when the bed sulfuration temperature of the decarbon catalyst and the desulfurization catalyst is 230-260℃, and then the waxy oil full circulation presulfuration, i.e. the first non-isothermal sulfuration, is performed; and the hydrogen sulfide content in the circulation hydrogen is controlled to be not less than 0.5vol.% during the process of increasing the temperature from the isothermal sulfuration temperature to the first non-isothermal sulfuration temperature and the first non-isothermal sulfuration stage.

13. The vulcanization method according to claim 12, characterized in that, The hydrogen sulfide content in the circulation hydrogen is controlled to be 0.5vol.%-1.0vol.% during the process of increasing the temperature from the isothermal sulfuration temperature to the first non-isothermal sulfuration temperature and the first non-isothermal sulfuration stage.

14. The vulcanization method according to claim 1, characterized by, The temperature is controlled to be 210-230℃ before the hydrogen sulfide penetrates the catalyst bed.

15. The vulcanization method according to claim 14, characterized in that, The reactor is heated at a rate of 5-20℃ / h before the hydrogen sulfide penetrates the catalyst bed.

16. The vulcanization method according to claim 1, characterized by, The hydrogen sulfide penetrates the catalyst bed when the hydrogen sulfide is first detected in the circulation hydrogen, and the concentration is 0.1vol.%-0.5vol.%.

17. The vulcanization method according to claim 1, characterized by, The hydrogen sulfide penetrates the catalyst bed when the hydrogen sulfide is first detected in the circulation hydrogen, and the concentration is 0.1vol.%-0.2vol.%.

18. The vulcanization method according to claim 1, characterized by, The fresh sulfur-containing waxy oil non-full circulation presulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be lower than the sulfuration reaction temperature of the decarbon catalyst and the desulfurization catalyst.

19. The vulcanization method according to claim 18, characterized in that, The fresh sulfur-containing waxy oil non-full circulation presulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be 20-50℃ lower than the sulfuration reaction temperature of the desulfurization and decarbon catalyst.

20. The vulcanization method according to claim 19, characterized by, The fresh sulfur-containing waxy oil non-full circulation presulfuration is to control the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst to be 30-50℃ lower than the sulfuration reaction temperature of the desulfurization and decarbon catalyst.

21. The vulcanization method according to claim 18, characterized in that, The hydrogen sulfide content in the circulation hydrogen is controlled to be not less than 0.7vol.% in the non-full circulation presulfuration stage.

22. The vulcanization method according to claim 21, characterized by, The hydrogen sulfide content in the circulation hydrogen is controlled to be 0.7-1.0vol.% in the non-full circulation presulfuration stage.

23. The vulcanization method according to claim 18, characterized by, The heating rate for increasing the temperature to the constant temperature of the non-full circulation presulfuration is 5-15℃ / h.

24. The vulcanization method according to claim 18, characterized by, In the fresh sulfur-containing waxy oil non-full circulation presulfuration, the sulfuration reaction temperature of the decarbon catalyst and the desulfurization catalyst is 310-330℃, and the sulfuration reaction temperature of the demetallization catalyst and the guard catalyst is 260-290℃, and the constant temperature sulfuration time is 2-8h.

25. The vulcanization method according to claim 24, characterized in that, In the non-full cycle pre-sulfurization of fresh sulfur-containing wax oil, the sulfurization reaction temperature of the demetallization catalyst and the guard catalyst is 270-280℃.

26. The vulcanization method according to claim 1, characterized by, In the sulfurization process, the feed amount of diesel or wax oil is controlled to be more than 60wt.% of the design processing load.

27. The vulcanization method according to claim 26, characterized in that, In the sulfurization process, the feed amount of diesel or wax oil is 60wt.%-90wt% of the design processing load.

28. The vulcanization method according to claim 1, characterized by, The sulfurization agent is at least one of carbon disulfide and dimethyl disulfide; the injection temperature of carbon disulfide is 180-190℃, and the injection temperature of dimethyl disulfide is 190-200℃.

29. The vulcanization method according to claim 1, characterized by, In the non-full cycle pre-sulfurization of fresh sulfur-containing wax oil, the sulfur-containing wax oil is straight-run wax oil, and the sulfur content is 1.5wt.%-3.5wt.%.

30. The vulcanization method according to claim 29, characterized by, In the non-full cycle pre-sulfurization of fresh sulfur-containing wax oil, the sulfur content in the straight-run wax oil is 2.0wt.%-3.5wt.%.

31. The vulcanization method according to claim 1, characterized in that, Before the non-full cycle pre-sulfurization of fresh sulfur-containing wax oil, the used wax oil is straight-run wax oil.

32. The vulcanization method according to claim 1, characterized by, Based on the total loading volume of the fixed bed residual oil hydroprocessing catalyst, the guard catalyst accounts for 3%-10% of the total loading volume, the demetallization catalyst accounts for 30%-60% of the total loading volume, and the sum of the loading volume of the desulfurization catalyst and the de-carbon residue catalyst accounts for 37%-67% of the total loading volume.

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