A method for stopping a liquid phase hydrogenation device of aviation kerosene

Abstract

The application discloses a kind of aviation coal liquid phase hydrogenation device shutdown method, comprising the following contents: (1) first, reduce aviation coal raw material feed temperature, when temperature reduces, stop into aviation coal raw material, stop supplement hydrogen, nitrogen is introduced before heating furnace, and after heating, nitrogen enters catalyst bed by reactor top, carries out first purging, after purging, stop introducing nitrogen;(2) maximum supplement hydrogen is introduced before heating furnace, and hydrogen is heated after passing through heating furnace, enters catalyst bed by reactor top, carries out second purging;(3) open heating furnace fuel gas bypass valve, so that part of fuel gas and hydrogen are mixed, after heating by heating furnace, introduce reactor catalyst bed, carry out third purging, and oil in catalyst bed is flowed out from reactor bottom.The method effectively improves the oil-carrying effect of catalyst during shutdown, shortens the purging time, and can quickly complete the shutdown process of liquid phase hydrogenation device.

Description

Technical Field

[0001] This invention belongs to the field of petroleum refining, and specifically relates to a shutdown method for a liquid-phase hydrogenation unit for aviation kerosene. Background Technology

[0002] With the continuous development of the global air transport industry, the demand for aviation kerosene has been increasing in recent years. Hydrogenation technology is currently the most mature and reliable technology for producing high-quality aviation kerosene products and has received widespread attention from the refining industry. At the same time, due to increasing market competition in the refining industry, the investment cost and operating expenses of hydrogenation units are relatively high. How to achieve the production of clean aviation kerosene products while reducing investment and operating costs is an important problem that urgently needs to be solved.

[0003] Against this backdrop, several patent holders of hydrogenation technology have developed low-cost liquid-phase hydrogenation technology for jet kerosene. This technology eliminates the need for a hydrogen recirculation system in the reaction section, relying instead on hydrogen dissolved in the kerosene feedstock to provide the chemically required hydrogen for the hydrogenation reaction. It boasts advantages such as a simple process flow, low investment costs, small footprint, and low operating costs. However, the elimination of the circulating hydrogen compressor results in lower hydrogen supply during downtime, significantly increasing the time required for hydrogen purging of the catalyst and removing residual oil. This frequently leads to high levels of residual oil after catalyst removal, severely impacting catalyst removal efficiency and regeneration effectiveness. Consequently, jet kerosene liquid-phase hydrogenation units experience relatively long downtimes, negatively impacting the profitability of refineries and hindering the further promotion and application of jet kerosene liquid-phase hydrogenation technology.

[0004] CN102527448B discloses a method and apparatus for deoiling a catalyst. This method and apparatus are specifically designed for removing oil from catalysts, employing a hot nitrogen circulation method. It can complete catalyst deoiling in a short time, achieving a deoiling rate as high as 98.7%, meeting the needs of continuous production in chemical plants.

[0005] CN112725026B discloses a shutdown method for a hydrocracking unit. This method controls the reaction temperature in the cracking section by increasing the nitrogen content in the feedstock and the reaction temperature in the refining section, while simultaneously injecting ammonia into the feedstock in the cracking section. The feedstock is then shut off for cooling and depressurization. This method effectively reduces the damage to the hydrocracking catalyst activity caused by the shutdown process, mitigating the problem of shortened service life of the hydrocracking unit after restarting.

[0006] However, none of the above are shutdown methods specifically for the liquid phase hydrogenation process of aviation kerosene. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a shutdown method for a liquid-phase hydrogenation unit for aviation kerosene. This method effectively improves the oil carryover effect of the hydrogenation catalyst during shutdown, shortens the purging time, and can quickly complete the shutdown process of the liquid-phase hydrogenation unit, effectively solving the problem of prolonged shutdown time caused by the small amount of hydrogen purging in the liquid-phase hydrogenation unit.

[0008] The shutdown method for the liquid-phase hydrogenation unit of aviation kerosene of the present invention includes the following:

[0009] (1) First, reduce the feed temperature of aviation kerosene. When the temperature is reduced, stop feeding aviation kerosene and stop adding hydrogen. Introduce nitrogen in front of the heater. The heated nitrogen enters the catalyst bed from the top of the reactor for the first purging. After the purging is completed, stop introducing nitrogen.

[0010] (2) The maximum amount of supplementary hydrogen is introduced to the front of the heater. After being heated by the heater, the hydrogen enters the catalyst bed from the top of the reactor for a second purging.

[0011] (3) Open the fuel gas bypass valve of the heater to mix some fuel gas and hydrogen. After being heated by the heater, the mixture is introduced into the catalyst bed of the reactor for the third purging. The oil stored in the catalyst bed flows out from the bottom of the reactor.

[0012] In the method of the present invention, step (1) involves reducing the feed temperature to 210-280°C or 10-30°C below the final reaction temperature.

[0013] In the method of this invention, the nitrogen gas mentioned in step (1) is the nitrogen gas commonly used in the nitrogen pipeline network of oil refining enterprises, mainly used for system replacement, drying and other processes. The conditions for the first purging operation are as follows: pressure 0.3-4.0 MPa, temperature 200-350℃, gas-to-agent volume ratio 50-200, and purging time 2-4 hours.

[0014] In the method of this invention, the liquid-phase hydrogenation reactor in step (1) generally includes functional units such as a feed oil buffer tank, a feed pump, a feed heater, a gas-liquid mixer, a liquid-phase hydrogenation reactor, a low-pressure separator, a fractionation tower, and corresponding pipelines and valves. The liquid-phase hydrogenation reactor is a single-bed or multi-bed fixed-bed hydrogenation reactor. The liquid-phase hydrogenation reactor can be a single reactor or multiple reactors connected in series, used to load aviation kerosene hydrogenation catalysts, which may include hydrogenation protection catalysts and hydrogenation refining catalysts, etc. Specific catalysts can be catalysts with the same function in existing technologies. The hydrogenation catalyst generally includes a support component and a hydrogenation active metal component, wherein the hydrogenation active metal component includes Group VIB metal elements and / or Group VIII metal elements, wherein the Group VIB loading metal element is Mo and / or W, and the Group VIII metal element is Ni and / or Co. The catalyst gradation method can be carried out according to conventional methods, and is not particularly limited in this invention.

[0015] In the method of this invention, the hydrogen used for purging in step (2) is the hydrogen used in the normal production process of the liquid phase hydrogenation unit for aviation kerosene, mainly used for hydrogenation to remove impurities from aviation kerosene raw materials. The operating conditions for the second purging are as follows: pressure 0.3~4.0MPa, temperature 250~400℃, hydrogen quantity is the maximum designed amount to be fed into the unit, and purging time is 3~5 hours.

[0016] In the method of this invention, the purging fuel gas in step (3) is the mixed gas used in the normal production process of the feed heating furnace of the aviation kerosene liquid phase hydrogenation unit. The operating conditions for the third purging are as follows: pressure 0.3-4.0 MPa, temperature 250-400℃, hydrogen quantity is the maximum designed amount to be fed into the unit, fuel gas introduction accounts for 30%-80% of the total fuel gas, and purging time is 7-9 hours.

[0017] In the method of this invention, the fuel gas mentioned in step (3) is a mixed gas supplied to the heating furnace of this device, and its main components include hydrogen, methane, ethane, and small amounts of propane, butane, etc. The fuel gas introduced into the liquid phase hydrogenation reactor accounts for 30% to 80% of the total fuel gas in the feed heating furnace. The injection point is in the pipeline before the feed heating furnace. The remaining small amount of fuel gas is still used as fuel for the heating furnace to heat the mixture of supplementary hydrogen and fuel gas.

[0018] In the method of the present invention, the bottom effluent of the reactor described in step (3) enters the low-pressure separator for separation, and the hydrogen and fuel gas are recycled and reused at the top of the gas-liquid separator.

[0019] Compared with the prior art, the method of the present invention has the following advantages:

[0020] 1. Compared to the shutdown process of conventional jet kerosene hydrogenation, this invention only requires the installation of some pipelines and valves to complete the catalyst oil carry-over process during the shutdown of the liquid-phase hydrogenation unit within 12-18 hours, slightly longer than the time required for conventional jet kerosene hydrogenation units. Existing jet kerosene liquid-phase hydrogenation units require at least 24-36 hours to achieve the same effect during normal shutdown oil carry-over. This invention, by introducing nitrogen and some fuel gas used in the heating furnace, fully utilizes the differences in the molecular structure and flow properties of different gases. Through a synergistic effect, it simultaneously increases the purging gas volume of the catalyst bed, achieving a better catalyst oil carry-over effect. Therefore, this invention, by adding some pipelines and corresponding valves, does not require an additional hydrogen supply from outside the unit.

[0021] 2. In the method of this invention, the fuel gas used is the mixed gas used in the heater of this device, which does not require changes to the process flow of the device and has low modification costs. Most of the fuel gas used is used for purging the oil in the catalyst bed of the liquid-phase hydrogenation reactor, and a small portion still enters the heater to heat and supplement the hydrogen and fuel gas entering the reactor. This method solves the problem of low gas volume in the catalyst bed and ensures that hydrogen and fuel gas can enter the catalyst bed at a relatively high temperature. In addition, since the main components of the fuel gas include hydrogen, methane, ethane and a small amount of propane, butane, etc., the smaller molecular weight hydrogen and methane can effectively purge the oil in the micropores of the catalyst, while the relatively larger molecular weight ethane, propane and butane can effectively carry the oil between the catalyst particles out of the hydrogenation reactor. Through the synergistic effect of gases with different molecular weights, the effect of removing oil in and between the catalyst pores is effectively guaranteed.

[0022] 3. The method of this invention fully utilizes the synergistic effect of nitrogen, hydrogen, and fuel gas. In the first purging process, the heated nitrogen primarily purges the oil remaining between catalyst particles in the upper bed of the reactor, while the oil in the upper bed flows downwards into the lower bed due to its own weight. In the second purging process, the heated hydrogen primarily purges the oil remaining in the micropores of the catalyst in the upper bed of the reactor, and also purges some of the oil remaining in the micropores and between particles of the catalyst in the lower bed. In the third purging process, the heated fuel gas and hydrogen primarily purge the remaining oil remaining in the micropores and between particles of the catalyst in the lower bed of the reactor, while also carrying the oil out of the hydrogenation reactor. The mixed gas used in the final purging, due to its different molecular structure, can effectively carry away the oil remaining in the micropores and between particles of the catalyst, and its relatively high temperature and larger flow rate allow for faster and more effective removal of the oil remaining in the lower catalyst bed.

[0023] 4. In the method of the present invention, the fuel gas used in the heating furnace of the device is fully utilized, so that it can not only play the role of heating gas, but also fully play the role of purging the oil in the catalyst bed. At the same time, it plays a good synergistic purging role with hydrogen, which effectively solves the problem of long downtime of aviation kerosene liquid phase hydrogenation device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a specific process of the method of the present invention.

[0025] Among them: 1-jet fuel, 2-fuel oil buffer tank, 3-feed pump, 4-fuel heater, 5-gas-liquid mixer, 6-liquid phase hydrogenation reactor, 7-low pressure separator, 8-fractionation tower, 9-refined kerosene, 10-nitrogen, 11-supplementary hydrogen, 12-fuel gas, 13-valve a, 14-valve b, 15-valve c, 16-valve d, 17-valve e. Detailed Implementation

[0026] The method of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, one implementation of the shutdown method for the liquid-phase hydrogenation unit of aviation kerosene according to the present invention is as follows: First, appropriately reduce the temperature of the raw material heater 4, cut off the aviation kerosene raw material 1, close valves a13 and e17, open valve b14, and introduce nitrogen gas 10 from before the heater, which, after being heated, passes through the gas-liquid mixer 5 and enters from the top of the liquid-phase hydrogenation reactor 6. After 2 to 4 hours, slowly open valve a13. 13. Close valve b14. Add hydrogen 11 enters the heating furnace 4 through valve a13. Heat the added hydrogen to the required temperature and ensure that all the hot hydrogen enters from the top of the liquid phase hydrogenation reactor 6. After 3-5 hours, slowly open valve d16 to mix some fuel gas with the added hydrogen 11 and then enter the heating furnace 4. Heat the mixed gas to the required temperature and then enter from the top of the liquid phase hydrogenation reactor 6 to purge the residual oil remaining in the pores and between particles of the lower bed of the reactor catalyst. After 7-9 hours, the purged residual oil enters the low-pressure separator 7 for separation. The hydrogen and fuel gas used for purging are discharged from the top of the low-pressure separator 7 and can be returned to the gas pipeline for continued use or purified for reuse.

[0028] The following examples will further illustrate the present invention.

[0029] In the embodiments and comparative examples of this invention, the liquid-phase hydrogenation technology for aviation kerosene developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., and the FH-40A hydrogenation catalyst and FBN series hydrogenation protectant were used to conduct shutdown tests on the liquid-phase hydrogenation unit for aviation kerosene.

[0030] The hydrorefining catalyst used in the embodiments and comparative examples of this invention is the FH-40A hydrorefining catalyst developed and produced by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., and its physicochemical properties are shown in Table 1. The residual oil content of the catalyst was determined using an RPA-03 catalyst volatiles simulation analyzer.

[0031] Example 1

[0032] according to Figure 1 The process employs a liquid-phase hydrogenation process for aviation kerosene. First, the feed temperature to the liquid-phase hydrogenation reactor is reduced to 230°C, then the reaction pressure is slowly reduced to 2.0 MPa, and the feedstock is stopped. Valves 13 and 17 are closed, and nitrogen gas 10 is introduced from before the heater. After heating, it enters from the top of the liquid-phase hydrogenation reactor 6. After 3 hours, valve 13 is slowly opened, and valve 14 is closed. Supplementary hydrogen 11 enters the heater 4 through valve 13. After heating, all of it enters from the top of the liquid-phase hydrogenation reactor 6. After 4 hours, valve 16 is slowly opened, allowing some fuel gas to mix with the supplementary hydrogen 11 before entering the heater 4. The heated mixed gas then enters from the top of the liquid-phase hydrogenation reactor 6 to purge the remaining residual oil in the pores and between particles of the lower catalyst bed. After 8 hours, the purged residual oil enters the low-pressure separator 7 for separation. The hydrogen and fuel gas used for purging are discharged from the top of the low-pressure separator 7, ending the purging process. The relevant valves are closed, the reaction temperature is reduced, and the reaction system is purged with nitrogen, ending the entire shutdown process. The effects after the work stoppage are listed in Table 3.

[0033] Example 2

[0034] according to Figure 1 The process employs a liquid-phase hydrogenation flow for aviation kerosene. First, the feed temperature to the liquid-phase hydrogenation reactor is reduced to 230°C, then the reaction pressure is slowly reduced to 2.5 MPa, and the feedstock is stopped. Valves 13 and 17 are closed, and nitrogen gas 10 is introduced from before the heater. After heating, it enters from the top of the liquid-phase hydrogenation reactor 6. After 3 hours, valve 13 is slowly opened, and valve 14 is closed. Supplementary hydrogen 11 enters the heater 4 through valve 13. After heating, all of it enters from the top of the liquid-phase hydrogenation reactor 6. After 5 hours, valve 16 is slowly opened, allowing some fuel gas to mix with the supplementary hydrogen 11 before entering the heater 4. The heated mixed gas then enters from the top of the liquid-phase hydrogenation reactor 6 to purge the remaining residual oil in the pores and between particles of the lower catalyst bed. After 9 hours, the purged residual oil enters the low-pressure separator 7 for separation. The hydrogen and fuel gas used for purging are discharged from the top of the low-pressure separator 7, ending the purging process. The relevant valves are closed, the reaction temperature is reduced, and the reaction system is purged with nitrogen, ending the entire shutdown process. The effects after the work stoppage are listed in Table 3.

[0035] Comparative Example 1

[0036] Compared with Example 1, the only difference is that only supplemental hydrogen is used to purge the catalyst bed in the liquid phase hydrogenation reactor.

[0037] Comparative Example 2

[0038] Compared with Example 2, the only difference is that only supplemental hydrogen is used to purge the catalyst bed in the liquid phase hydrogenation reactor, and the purging time is basically the same as that of this technical solution.

[0039] Table 1 Physicochemical properties of hydrorefining catalysts

[0040]

[0041]

[0042] Table 2 Fuel Gas Group Composition

[0043] name,% Fuel gas A Fuel gas B hydrogen 2.4 5.1 methane 18.8 25.2 Ethane 20.1 23.3 ethylene 0.4 0.2 propane 23.6 21.1 propylene 0.5 0.8 butane 34.1 24.0 Butene 0.1 0.3 total 100.0 100.0

[0044] Table 3. Effects of shutdown in the examples and comparative examples

[0045]

[0046]

Claims

1. A method for shutting down a liquid-phase hydrogenation unit for aviation kerosene, characterized in that... The following are included: (1) First, reduce the feed temperature of aviation kerosene. When the temperature is reduced, stop feeding aviation kerosene and stop supplementing hydrogen. Introduce nitrogen in front of the heater. The heated nitrogen enters the catalyst bed from the top of the reactor for the first purging. After the purging is completed, stop introducing nitrogen. (2) Introduce the maximum amount of supplementary hydrogen in front of the heater. After the hydrogen is heated by the heater, it enters the catalyst bed from the top of the reactor for the second purging. (3) Open the fuel gas bypass valve of the heater to mix some fuel gas and hydrogen. After being heated by the heater, it is introduced into the catalyst bed of the reactor for the third purging. The oil stored in the catalyst bed flows out from the bottom of the reactor.

2. The shutdown method according to claim 1, characterized in that: Step (1) involves lowering the feed temperature to 210-280°C or 10-30°C below the final reaction temperature.

3. The shutdown method according to claim 1, characterized in that: The liquid-phase hydrogenation reactor described in step (1) includes a feed oil buffer tank, a feed pump, a feed heater, a gas-liquid mixer, a liquid-phase hydrogenation reactor, a low-pressure separator, a fractionation tower, and corresponding pipelines and valves; wherein, the liquid-phase hydrogenation reactor is a single-bed or multi-bed fixed-bed hydrogenation reactor.

4. The shutdown method according to claim 1, characterized in that: The liquid-phase hydrogenation reactor can be a single reactor or multiple reactors connected in series, used to pack aviation kerosene hydrogenation catalysts, including hydrogenation protection catalysts and hydrogenation refining catalysts.

5. The shutdown method according to claim 1, characterized in that: The conditions for the first purging operation in step (1) are as follows: reaction pressure 0.3~4.0MPa, reaction temperature 200~350℃, gas-agent volume ratio 50~200, and time 2~4 hours.

6. The shutdown method according to claim 1, characterized in that: The conditions for the second purging operation in step (2) are as follows: reaction pressure 0.3~4.0MPa, reaction temperature 250~400℃, gas-agent volume ratio 30~200, and time 3~5 hours.

7. The shutdown method according to claim 1, characterized in that: The conditions for the third purging operation in step (3) are as follows: reaction pressure 0.3~4.0MPa, reaction temperature 250~400℃, gas-agent volume ratio 50~300, and time 7~9 hours.

8. The shutdown method according to claim 1, characterized in that: The amount of hydrogen introduced in step (3) is the maximum amount designed to be introduced into the device, and the amount of fuel gas introduced accounts for 30% to 80% of the total fuel gas.

9. The shutdown method according to claim 1, characterized in that: The fuel gas mentioned in step (3) is a mixed gas supplied to the heating furnace of this device. The fuel gas introduced into the liquid phase hydrogenation reactor accounts for 30% to 80% of the total fuel gas; the remaining small amount of fuel gas is still used as fuel for the heating furnace to heat the mixed gas of supplementary hydrogen and fuel gas.

10. The shutdown method according to claim 1, characterized in that: The bottom effluent from the reactor described in step (2) enters a low-pressure separator for separation, while hydrogen and fuel gas are recycled and reused at the top of the gas-liquid separator.

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