Vacuum system and method for a fixed bed propane dehydrogenation unit

Abstract

The present application relates to the technical field of chemical engineering device, disclose a kind of fixed bed propane dehydrogenation device's vacuum system and method, when the first vacuum device operates, the current exhaust temperature of the exhaust port of the first vacuum device is acquired in real time;Current exhaust temperature is compared with preset temperature, when current exhaust temperature exceeds preset temperature, control switching component enters second working mode, the first vacuum device stops running and the second vacuum device operates.The fixed bed propane dehydrogenation device's vacuum method provided in the present application, when temperature exceeds preset temperature, immediately control the first vacuum device stops running, so that effectively avoid the thermal damage of high-temperature gas to the core components of the first vacuum device, prolongs the service life of equipment.Therefore, the technical scheme can guarantee the safety of propane dehydrogenation device vacuum process under the premise, effectively reduces energy consumption, improves the reliability of system.

Description

Technical Field

[0001] This invention relates to the field of chemical plant technology, and in particular to a vacuum system and method for a fixed-bed propane dehydrogenation unit. Background Technology

[0002] Fixed-bed propane dehydrogenation units typically employ multiple reactors controlled sequentially to achieve continuous material production. In the operation cycle of a single reactor, the process involves a series of steps, including dehydrogenation reaction, steam purging, catalyst regeneration (coke burning), vacuuming, hydrogen injection reduction, and return to dehydrogenation. The vacuuming process plays a crucial role, its main task being to rapidly remove residual high-temperature gases (typically 580–600°C and approximately 120–130 kPaA) after catalyst regeneration, reducing the internal pressure to below 50 kPaA (absolute pressure). This creates an oxygen-free, low-pressure safe environment for subsequent injection of reducing hydrogen, preventing explosions.

[0003] Currently, the mainstream technical solution for achieving this vacuuming process in the industry is to use a steam ejector system. This system uses high-pressure steam of approximately 4.0 MPaG as the driving fluid, forming a supersonic jet through nozzles. This creates negative pressure in the mixing chamber to extract the process gas from the reactor. Once the steam pressure falls below a set value, the system determines that the vacuuming capacity is insufficient and immediately triggers an interlock to stop subsequent hydrogen injection operations, preventing an explosion caused by the mixing of oxygen and hydrogen. However, this traditional method is extremely energy-intensive; a typical single PDH unit consumes 25–35 t / h of steam, significantly increasing the operating costs of the unit.

[0004] In recent years, in order to reduce energy consumption, the industry has begun to try using liquid ring (water ring) vacuum pump units to replace steam ejectors. However, when switching to electric vacuum pump units, if the pumping capacity suddenly decreases due to overload tripping, frequency converter failure, or pipeline leakage during operation, and hydrogen is injected according to the original procedure, it is very easy to form an explosive gas mixture under high temperature and high pressure, causing serious safety accidents. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a vacuum system and method for a fixed-bed propane dehydrogenation device, which can effectively reduce the risk of explosion and improve system safety.

[0006] In a first aspect, the present invention provides a vacuuming method for a fixed-bed propane dehydrogenation device, applied to a controller of a vacuuming system. The fixed-bed propane dehydrogenation device includes a reactor, and the vacuuming system includes a controller, a switching assembly, a first vacuuming device, and a second vacuuming device. The second vacuuming device is a steam vacuum ejector. The switching assembly is disposed between the reactor, the first vacuuming device, and the second vacuuming device, and is electrically connected to the controller to have a first operating mode and a second operating mode. In the first operating mode, the switching assembly connects the gas outlet of the reactor with the gas inlet of the first vacuuming device to form a first flow path, and disconnects the gas outlet of the reactor from the gas inlet of the second vacuuming device. In the second operating mode, the switching assembly connects the gas outlet of the reactor with the gas inlet of the second vacuuming device to form a second flow path, and disconnects the gas outlet of the reactor from the gas inlet of the first vacuuming device. The method includes: When the first vacuum device is running, the current outlet temperature of the first vacuum device is obtained in real time. The current outlet temperature is compared with the preset temperature. When the current outlet temperature exceeds the preset temperature, the control switching component enters the second working mode, the first vacuum device stops running, and the second vacuum device starts running.

[0007] The vacuuming method for a fixed-bed propane dehydrogenation unit provided by this invention has the following advantages compared to the prior art: This invention monitors the outlet gas temperature of the first vacuuming device to determine the system status and automatically switches to the second vacuuming device in case of an anomaly. When the temperature exceeds a preset temperature (i.e., a potential critical point of danger), this method immediately controls the first vacuuming device to stop operating, thereby effectively avoiding thermal damage to the core components of the first vacuuming device from high-temperature gas and extending the equipment's service life. Simultaneously with cutting off the first path, the switching component is immediately controlled to enter the second working mode and the second vacuuming device (steam vacuum ejector) is started. Furthermore, under normal operating conditions where the outlet gas temperature does not exceed the preset temperature, the system defaults to using the first vacuuming device. Since the operating energy consumption of the mechanical vacuum pump is lower than that of the steam ejector, this ensures low-energy operation of the unit for most of the time. This method, through automated control logic, can complete flow path switching and equipment start-up and shutdown instantly when the temperature exceeds the limit, eliminating the time lag and risk of misoperation associated with manual judgment and operation. Therefore, this technical solution can effectively reduce energy consumption and improve system reliability while ensuring the safety of the vacuuming process in the propane dehydrogenation unit.

[0008] Furthermore, the method also includes: After the vacuum system is started, obtain the current status of the first vacuum device; If the current state is a fault state, the control switching component will enter the second working mode and the second vacuum pumping device will operate. If the current state is normal, the control switching component enters the first working mode and the first vacuum pumping device starts operating.

[0009] Further, the first vacuum pumping device includes a cooling structure, an outlet separating tank, and a liquefaction vacuum pump. The inlet of the cooling structure is connected to the outlet of the reactor via a switching component. The inlet of the liquefaction vacuum pump is connected to the outlet of the cooling structure. The outlet of the liquefaction vacuum pump is connected to the inlet of the outlet separating tank. The outlet of the outlet separating tank is located above the inlet of the outlet separating tank and is used to discharge the cooled gas. The method also includes: When the first vacuum pump is running, the operation of the liquefied vacuum pump is controlled, and the current operating current of the liquefied vacuum pump is acquired in real time. When the current operating current is zero, the current state of the first vacuum pumping device is changed from normal state to fault state.

[0010] Furthermore, the cooling structure includes a desuperheater and a cooling tower; wherein, the air inlet of the desuperheater is connected to the air outlet of the reactor via a switching component, the air inlet of the cooling tower is connected to the air outlet of the desuperheater, and the air outlet of the cooling tower is connected to the air inlet of the liquefied vacuum pump; controlling the operation of the second vacuum pumping device includes: Control the operation of the desuperheater to reduce the temperature of the incoming gas to 80-200℃; Control the operation of the cooling tower to reduce the temperature of the incoming gas to 45-70°C.

[0011] Furthermore, the current outlet temperature of the first vacuum pumping device is acquired in real time, including: The current first outlet temperature of the desuperheater is obtained in real time; The current outlet temperature is compared with the preset temperature. When the current outlet temperature exceeds the preset temperature, the control switching component enters the second working mode, the first vacuum pump stops operating, and the second vacuum pump starts operating, including: The current first outlet temperature is compared with the first preset temperature. When the current first outlet temperature exceeds the first preset temperature, the control switching component enters the second working mode, the first vacuum device stops running and the second vacuum device starts running, wherein the first preset temperature is between 200℃ and 205℃.

[0012] Furthermore, the current outlet temperature of the first vacuum pumping device is acquired in real time, including: Real-time acquisition of the current second outlet air temperature at the outlet of the cooling tower; The current outlet temperature is compared with the preset temperature. When the current outlet temperature exceeds the preset temperature, the control switching component enters the second working mode, the first vacuum pump stops operating, and the second vacuum pump starts operating, including: The current second outlet temperature is compared with the second preset temperature. When the current second outlet temperature exceeds the second preset temperature, the control switching component enters the second working mode, the first vacuum device stops running and the second vacuum device starts running, wherein the second preset temperature is between 70℃ and 75℃.

[0013] Furthermore, the desuperheater is equipped with atomizing nozzles; controlling the operation of the desuperheater includes: Control the atomizing nozzle to spray atomized water with droplet size of 50μm to 150μm and temperature not higher than 50℃.

[0014] Furthermore, the cooling tower also includes spray nozzles for spraying quenching water and a cooling tower outlet. The air inlet of the contact water spray cooling tower is located vertically between the nozzles and the cooling tower outlet, and the air outlet of the contact water spray cooling tower is located vertically above the nozzles. Controlling the operation of the cooling tower includes: Control the spray nozzles to spray cooling water at a temperature not exceeding 50°C.

[0015] Furthermore, the air inlet of the first vacuum device is connected to the air outlet of the reactor through the first pipeline, and the air inlet of the second vacuum device is connected to the air outlet of the reactor through the second pipeline; the switching component includes a first solenoid valve and a second solenoid valve electrically connected to the controller, the first solenoid valve being located on the first pipeline and the second solenoid valve being located on the second pipeline. The control switching component enters the first working mode, including: controlling the first solenoid valve to open and the second solenoid valve to close; The control switching component enters the second working mode, including: controlling the first solenoid valve to close and the second solenoid valve to open.

[0016] Secondly, the present invention also provides a vacuum system for a fixed-bed propane dehydrogenation apparatus, including a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the control method of the vacuum system for the fixed-bed propane dehydrogenation apparatus of any of the above embodiments.

[0017] The vacuum system for a fixed-bed propane dehydrogenation unit provided by this invention offers several advantages over prior art: This invention monitors the outlet gas temperature of the first vacuum device to determine the system status and automatically switches to the second vacuum device in case of an anomaly. When the temperature exceeds a preset temperature (i.e., a potential critical point), this method immediately stops the first vacuum device, effectively preventing thermal damage to the core components of the first vacuum device from high-temperature gas and extending the equipment's service life. Simultaneously with cutting off the first path, the switching component immediately enters the second operating mode and starts the second vacuum device (steam vacuum ejector). Furthermore, under normal operating conditions where the outlet gas temperature does not exceed the preset temperature, the system defaults to using the first vacuum device. Since the mechanical vacuum pump consumes less energy than the steam ejector, this ensures low-energy operation of the unit for most of the time. This method, through automated control logic, can instantly switch flow paths and start / stop the equipment when the temperature exceeds the limit, eliminating the time lag and risk of misoperation associated with manual judgment and operation. Therefore, this technical solution effectively reduces energy consumption and improves system reliability while ensuring the safety of the vacuuming process in the propane dehydrogenation unit. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below only show some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the vacuum system of a fixed-bed propane dehydrogenation apparatus according to an embodiment of the present invention is shown. Figure 2 A schematic flowchart of a vacuuming method for a fixed-bed propane dehydrogenation apparatus according to an embodiment of the present invention is shown. Figure 3 An internal structural diagram of the computer equipment of the vacuum system of a fixed-bed propane dehydrogenation apparatus according to an embodiment of the present invention is shown. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments only show a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are shown only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they may indicate a fixed connection, a detachable connection, or an integral connection; they may indicate a mechanical connection or an electrical connection; they may indicate a direct connection or an indirect connection through an intermediate medium; and they may indicate communication between the internal components of two elements. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] This embodiment provides a vacuum system and method for a fixed-bed propane dehydrogenation device, aiming to solve the problems of high energy consumption of a single steam ejector or insufficient safety of a single electric vacuum pump in the prior art.

[0025] This embodiment provides a vacuuming method for a fixed-bed propane dehydrogenation unit, applied to the controller of the vacuuming system, such as... Figure 1As shown, the fixed-bed propane dehydrogenation unit includes a reactor 100, and the vacuum system includes a controller, a switching component 10, a first vacuum device 20, and a second vacuum device 30. The second vacuum device 30 is a steam vacuum ejector. The switching component 10 is located between the reactor 100, the first vacuum device 20, and the second vacuum device 30. The switching component 10 is electrically connected to the controller to have a first operating mode and a second operating mode. In the first operating mode, the switching component 10 connects the outlet of the reactor 100 with the inlet of the first vacuum device 20 to form a first flow path, and disconnects the outlet of the reactor 100 from the inlet of the second vacuum device 30. In the second operating mode, the switching component 10 connects the outlet of the reactor 100 with the inlet of the second vacuum device 30 to form a second flow path, and disconnects the outlet of the reactor 100 from the inlet of the first vacuum device 20. Figure 2 This is a flowchart of a vacuuming method for a fixed-bed propane dehydrogenation apparatus according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps: S100: When the first vacuum device 20 is running, the current outlet temperature of the outlet of the first vacuum device 20 is obtained in real time.

[0026] A temperature sensor is installed at the outlet of the first vacuum device 20 (e.g., on the exhaust pipe of the outlet separator 27). The temperature sensor is connected to the control module of the vacuum system. During the vacuuming operation in the first working mode of the first vacuum device 20, the temperature sensor monitors the temperature of the gas flowing through the outlet in real time and converts the collected temperature signal into an electrical signal, which is then transmitted to the control module. The control module receives and records the current outlet temperature value. Monitoring the current outlet temperature effectively reflects the state of the gas discharged from the reactor 100 and the operating load of the first vacuum device 20 itself.

[0027] S200: Compare the current outlet temperature with the preset temperature. When the current outlet temperature exceeds the preset temperature, control the switching component 10 to enter the second working mode, the first vacuum device 20 to stop running, and the second vacuum device 30 to start running.

[0028] Specifically, the control module has a pre-stored safe temperature threshold (i.e., a preset temperature). The preset temperature is set according to the tolerance limit temperature of the first vacuum pumping device 20 and process safety requirements, for example, it can be set to 60℃~80℃.

[0029] The control module compares the current outlet air temperature, which is acquired in real time, with the preset temperature. Scenario 1: If the current outlet temperature does not exceed the preset temperature, it indicates that the first vacuum device 20 is operating normally and the temperature of the gas discharged from the reactor 100 is within the safe range. The control module controls the switching component 10 to maintain the first working mode and continue to perform vacuuming by the first vacuum device 20.

[0030] Scenario 2: If the current outlet gas temperature exceeds the preset temperature, it indicates that reactor 100 may be experiencing overheating (e.g., excessive combustion during regeneration) or that the cooling effect of the first vacuum pump 20 has decreased. Continued operation may damage the first vacuum pump 20 (e.g., mechanical seal failure, pump deformation). In this case, the control module executes the following interlock protection logic: 1. Sending a shutdown command: The control module sends a shutdown signal to the first vacuum pumping device 20 (such as the motor of a water ring vacuum pump) to stop the operation of the first vacuum pumping device 20 and prevent high temperature damage to the equipment.

[0031] 2. Switching the flow path: The control module controls the switching component 10 to operate. Specifically, the first solenoid valve on the first pipeline is closed, disconnecting the reactor 100 from the first vacuum device 20; simultaneously, the second solenoid valve on the second pipeline is opened, connecting the reactor 100 to the second vacuum device 30. At this time, the switching component 10 switches from the first operating mode to the second operating mode.

[0032] 3. Start the standby device: The control module sends an opening signal to the steam inlet valve of the second vacuum device 30 (steam vacuum ejector) to introduce high-pressure steam and start the steam vacuum ejector.

[0033] The vacuuming method provided in this embodiment determines the system status by monitoring the outlet gas temperature of the first vacuuming device 20 and automatically switches to the second vacuuming device 30 in case of an anomaly. When the temperature exceeds a preset temperature (i.e., a potential critical point of danger), this method immediately controls the first vacuuming device 20 to stop operating, effectively preventing thermal damage to the core components of the first vacuuming device 20 from high-temperature gas and extending the equipment's service life. Simultaneously with cutting off the first path, the switching component 10 is immediately controlled to enter the second operating mode and the second vacuuming device 30 (steam vacuum ejector) is activated. Furthermore, under normal operating conditions where the outlet gas temperature does not exceed the preset temperature, the system defaults to using the first vacuuming device 20. Since the operating energy consumption of the mechanical vacuum pump is lower than that of the steam ejector, this ensures low-energy operation of the device for most of the time. This method, through automated control logic, can complete flow path switching and equipment start-up and shutdown instantly when the temperature exceeds the limit, eliminating the time lag and risk of misoperation associated with manual judgment and operation. Therefore, this embodiment effectively reduces energy consumption and improves system reliability while ensuring the safety of the vacuuming process in the propane dehydrogenation unit.

[0034] In one embodiment, the method further includes the following steps: S300. After the vacuum system is started, obtain the current status of the first vacuum device 20.

[0035] Upon receiving the system start signal from the operator, the main equipment is not immediately started; instead, a self-test procedure is executed first. The control module reads the status feedback signal of the first vacuum pumping device 20 (e.g., a liquefied vacuum pump) in real time via a communication bus or hardwired signal. The current status includes, but is not limited to: motor run / stop signal, inverter fault alarm signal, circuit breaker closing status, or current feedback value. If the feedback signal indicates that the equipment is in a "fault" or "trip" state, the current state is determined to be a fault state; otherwise, it is a normal state.

[0036] S400 If the current state is a fault state, the control switching component 10 enters the second working mode and the second vacuuming device 30 runs.

[0037] When the system detects a fault in the primary vacuum pumping device 20 (such as failure to reset after the last shutdown, motor overload, etc.), the system automatically triggers redundant protection logic to avoid production delays caused by starting with a faulty device. The control module first outputs a control signal to drive the switching component 10, establishing a gas path connection between the reactor 100 and the secondary vacuum pumping device 30; then, it outputs a start signal to activate the secondary vacuum pumping device 30 (such as a steam ejector), directly utilizing the backup system for vacuuming operations.

[0038] S500 If the current state is normal, the control switching component 10 enters the first working mode and the first vacuum device 20 runs.

[0039] When the system confirms that all indicators of the first vacuum pumping device 20 are normal, the standard startup procedure is executed. The control module controls the switching component 10 to be in the first working mode, establishing a gas path connection between the reactor 100 and the first vacuum pumping device 20; subsequently, the first vacuum pumping device 20 is started. At this time, the system operates in a low-energy-consumption, high-efficiency mechanical pump pumping mode.

[0040] This embodiment introduces self-testing logic (S300) during the startup phase, enabling the system to automatically identify the health status of the main equipment (first vacuum pumping device 20). This avoids forced startup due to equipment failure caused by human oversight, which could lead to secondary damage or safety accidents. When the main equipment fails, the system automatically executes step S400, immediately switching to the backup path (second vacuum pumping device 30). This "fault bypass" mechanism ensures that even in the event of a main pump failure, the device can still maintain a vacuum environment through a backup system (such as a steam ejector), greatly reducing unplanned downtime and ensuring the continuity of the propane dehydrogenation process.

[0041] In one embodiment, the first vacuum pumping device 20 includes a cooling structure, an outlet separating tank 27, and a liquefaction vacuum pump 28. The air inlet of the cooling structure is connected to the air outlet of the reactor 100 via a switching component 10. The air inlet of the liquefaction vacuum pump 28 is connected to the air outlet of the cooling structure, and the air outlet of the liquefaction vacuum pump 28 is connected to the air inlet of the outlet separating tank 27. The air outlet of the outlet separating tank 27 is located above the air inlet of the outlet separating tank 27 and is used to discharge the cooled gas. The method further includes the following steps: S600: When the first vacuum pumping device 20 is running, the liquefied vacuum pump 28 is controlled to run, and the current running current of the liquefied vacuum pump 28 is obtained in real time.

[0042] Specifically, after confirming that the first vacuum pumping device 20 has been started, the control module reads the three-phase current value or average operating current of the motor in real time at a preset sampling frequency (such as once per second) through a current transformer or intelligent circuit breaker installed in the power supply circuit of the liquefied vacuum pump 28 motor. This step aims to indirectly characterize the mechanical operating state of the pump body through the key physical quantity of current.

[0043] S700 When the current operating current is zero, change the current state of the first vacuum pumping device 20 from normal state to fault state.

[0044] The control module compares the real-time current value with zero (or an extremely low leakage current threshold). If the current is zero, it indicates that the motor may have experienced a serious fault such as power failure, tripping, contactor disconnection, or burnt-out motor windings, causing the pump to lose power. At this time, the control module immediately generates a fault flag and triggers the state change logic.

[0045] This embodiment monitors the operating current of the liquefied vacuum pump 28 in real time through step S600, directly reflecting the core power status of the equipment. Current is the most sensitive parameter reflecting motor load and operating status; compared to monitoring only the outlet pressure, current monitoring can detect equipment shutdown faults more quickly. Step S700 uses "zero current" as a criterion, with clear logic and strong anti-interference capabilities. If the motor unexpectedly loses power or trips, the system can identify "abnormal shutdown" within milliseconds or seconds, avoiding misjudgments caused by pressure gauge response lag. Changing the device status from "normal" to "fault" is a key prerequisite for triggering the startup of the backup system (second vacuum pumping device 30) in the aforementioned embodiment (step S400). This embodiment ensures that switching is only triggered when the main pump actually shuts down, preventing erroneous switching due to secondary factors such as pressure fluctuations, and guaranteeing the stability of the propane dehydrogenation unit's vacuum system.

[0046] In one embodiment, the cooling structure includes a desuperheater 21 and a cooling tower 22; wherein the air inlet of the desuperheater 21 is connected to the air outlet of the reactor 100 via a switching component 10, the air inlet of the cooling tower 22 is connected to the air outlet of the desuperheater 21, and the air outlet of the cooling tower 22 is connected to the air inlet of the liquefied vacuum pump 28; controlling the operation of the second vacuum pumping device 30 includes: 1. Control the operation of the desuperheater 21 to reduce the temperature of the incoming gas to 80-200℃.

[0047] Specifically, when the system switches to the second operating mode, the control module sends an activation command to the desuperheater 21. Based on feedback from the inlet temperature sensor, the desuperheater 21 adjusts the atomization rate of the cooling medium (such as atomized demineralized water or condensate). The temperature detected by the inlet temperature sensor is positively correlated with the atomization rate of the cooling medium. Using direct mixing heat exchange or indirect heat exchange, the extremely high temperature gas discharged from the reactor 100 (e.g., 500°C) is rapidly reduced to 80–200°C. This temperature range is chosen to avoid the dew point corrosion zone of the gas while preventing excessively high temperatures from damaging the internal components of the subsequent cooling tower 22.

[0048] 2. Control the operation of cooling tower 22 to reduce the temperature of the incoming gas to 45-70℃.

[0049] The gas, after being processed by the desuperheater 21, enters the cooling tower 22. The control module activates the circulating cooling system of the cooling tower 22 (e.g., by turning on the cooling fan or circulating water pump) to further exchange sensible heat with the gas. The goal is to precisely control the gas temperature between 45 and 70°C. This temperature range is typically slightly higher than the dew point temperature of the heavy components in the gas to prevent excessive condensation and liquid slugging before the inlet of the liquefied vacuum pump 28, while being low enough to meet the optimal operating temperature requirements of the liquefied vacuum pump 28, ensuring the pumping efficiency and sealing performance of the pump body.

[0050] This embodiment achieves a combination of rapid cooling and precise cooling by setting up a two-stage cooling system: a desuperheater 21 and a cooling tower 22. The desuperheater 21 has a fast response speed and strong heat load handling capacity, making it suitable for handling large temperature differences in the high-temperature range; the cooling tower 22 has high temperature control accuracy and stable operation, making it suitable for handling precise temperature control in the low-temperature range. This division of labor avoids the contradiction of a single device needing to simultaneously meet the requirements of large temperature differences and a wide adjustment range, reducing equipment costs and maintenance difficulty.

[0051] In one embodiment, step S100 includes: S101, real-time acquisition of the current first outlet temperature of the desuperheater 21.

[0052] Specifically, a first temperature sensor (e.g., thermocouple or resistance temperature detector) is installed at the outlet pipe or outlet flange of the desuperheater 21. The control module reads the signal from this temperature sensor at a preset sampling period (e.g., every 500 milliseconds), and obtains the current first outlet temperature after filtering. This temperature directly reflects the initial cooling effect of the desuperheater 21 on the high-temperature gas discharged from the reactor 100.

[0053] Step S200 includes: S102, compare the current first outlet temperature with the first preset temperature. When the current first outlet temperature exceeds the first preset temperature, control the switching component 10 to enter the second working mode, stop the first vacuum device 20 and start the second vacuum device 30, wherein the first preset temperature is between 200℃ and 205℃.

[0054] The control module stores a first preset temperature threshold, which is set between 200°C and 205°C (preferably 200°C). When the current first outlet gas temperature monitored in real time exceeds this threshold, it indicates that the desuperheater 21 is unable to cool the gas to the safe operating range of subsequent equipment (such as cooling tower 22 or liquefied vacuum pump 28). At this time, in order to prevent the high-temperature gas from damaging the seals of liquefied vacuum pump 28 or causing the cooling tower 22 to overheat, the control module immediately executes the protection logic: first, it outputs a shutdown signal to shut down the first vacuum pumping device 20; second, it drives the switching component 10 to cut off the gas path of the first vacuum pumping device 20 and connect the gas path of the second vacuum pumping device 30; finally, it starts the second vacuum pumping device 30 (such as a steam ejector, whose temperature resistance is usually better than that of a mechanical pump) to maintain the vacuum pumping function of the system.

[0055] In this embodiment, a temperature warning mechanism is set at the outlet of the desuperheater 21 through steps S101 and S102. Once a cooling failure is detected that causes the temperature to exceed the first preset temperature (200℃-205℃), the system can immediately cut off the path of high-temperature gas into the first vacuum pumping device 20. This effectively avoids high-temperature gas directly impacting the liquefied vacuum pump 28, preventing serious equipment accidents such as pump jamming, seal failure, or lubricating oil carbonization caused by excessive temperature.

[0056] In one embodiment, step S100 includes: Step S102: Obtain the current second outlet temperature of the outlet of the cooling tower 22 in real time.

[0057] Specifically, a second temperature sensor (such as a Pt100 resistance temperature detector) is installed on the gas outlet pipe of cooling tower 22, specifically on the section of pipe before it connects to the inlet of liquefied vacuum pump 28. The control module continuously acquires the signal from this sensor via an analog input module, monitoring in real time the temperature of the gas that finally enters the vacuum pump after two stages of cooling. This temperature is the direct basis for determining whether the inlet conditions of liquefied vacuum pump 28 meet the standards.

[0058] Step S200 includes: Step S202: Compare the current second outlet temperature with the second preset temperature. When the current second outlet temperature exceeds the second preset temperature, control the switching component 10 to enter the second working mode, stop the first vacuum device 20 and start the second vacuum device 30, wherein the second preset temperature is between 70℃ and 75℃.

[0059] The control module has a second preset temperature threshold set between 70°C and 75°C (preferably 70°C). When the current second outlet gas temperature monitored in real time is higher than this threshold, it indicates that although the desuperheater 21 is working normally, the cooling tower 22 may have reduced heat exchange capacity due to excessively high cooling water temperature, scaling of heat exchange tubes, or fan failure, and thus cannot cool the gas to the ideal temperature required by the liquefied vacuum pump 28 (usually required to be below 70°C to ensure the performance of the sealing fluid and the pumping efficiency). At this time, in order to protect the liquefied vacuum pump 28, the control module executes protection logic: immediately stops the temperature-sensitive first vacuum pumping device 20, switches the gas path to the second vacuum pumping device 30 (such as a steam ejector) with better temperature resistance, and starts the second vacuum pumping device 30 to maintain the system vacuum.

[0060] Because liquefied vacuum pumps (such as liquid ring pumps) are highly sensitive to inlet gas temperature, excessively high inlet gas temperatures can lead to an increase in the saturated vapor pressure of the working fluid (sealing fluid) inside the pump, significantly reducing the pump's ultimate vacuum and pumping efficiency, and even causing cavitation or mechanical seal damage. This embodiment uses step S202 to intercept the gas at 70℃-75℃, ensuring that the gas temperature entering the pump body remains within a safe and efficient range. Furthermore, by ensuring that the first vacuum pumping device 20 operates only in the efficient range with a suitable inlet gas temperature, energy waste and inefficiency caused by operating in the inefficient high-temperature range are avoided. When operating conditions worsen, the system automatically switches to the second device, which is more suitable for high-temperature conditions, thus optimizing the overall system energy efficiency.

[0061] In one embodiment, the desuperheater 21 is provided with an atomizing nozzle; controlling the operation of the desuperheater 21 includes: Control the atomizing nozzle to spray atomized water with droplet size of 50μm to 150μm and temperature not higher than 50℃.

[0062] Specifically, the desuperheater 21 is equipped with a high-pressure atomizing nozzle. The control module adjusts the water supply pressure and flow rate so that the nozzle atomizes the cooling water with a temperature ≤50℃ into tiny droplets with a particle size of 50μm to 150μm.

[0063] Droplets with a diameter range of 50μm to 150μm have an extremely large specific surface area. When injected into a high-temperature gas flow, they can evaporate and absorb heat instantly, achieving rapid cooling (quenching). At the same time, the droplet size of 50μm to 150μm can effectively prevent droplets that are too large from settling and wetting the wall, or droplets that are too small (<10μm) from being directly carried away by the gas flow without evaporation, thus ensuring both cooling efficiency and the dryness of the gas flow.

[0064] In one embodiment, the cooling tower 22 further includes a spray nozzle for spraying quench water and a cooling tower outlet. The air inlet of the contact water spray cooling tower 22 is located between the nozzle and the cooling tower outlet in the vertical direction, and the air outlet of the contact water spray cooling tower 22 is located above the nozzle in the vertical direction. Controlling the operation of the cooling tower 22 includes: Control the spray nozzles to spray cooling water at a temperature not exceeding 50°C.

[0065] Cooling tower 22 adopts a contact water spray structure. Cooling water (≤50℃) is sprayed downwards from the upper spray nozzles, coming into countercurrent contact with the gas entering from the lower air inlet. As the gas rises, it fully contacts the water droplets for heat exchange, further reducing its temperature to 45℃~70℃. The condensate and spray water converge at the bottom outlet and are discharged, while the cooled gas is discharged from the top air outlet.

[0066] This countercurrent contact design maximizes the temperature difference for gas-liquid mass and heat transfer, ensuring that the gas can be deeply cooled to the optimal operating temperature range required by the liquefied vacuum pump 28, while also achieving gas-liquid separation.

[0067] In one embodiment, the air inlet of the first vacuum device 20 is connected to the air outlet of the reactor 100 through a first pipeline, and the air inlet of the second vacuum device 30 is connected to the air outlet of the reactor 100 through a second pipeline; the switching component includes a first solenoid valve and a second solenoid valve electrically connected to the controller, the first solenoid valve being disposed on the first pipeline, and the second solenoid valve being disposed on the second pipeline.

[0068] The control switching component 10 enters the first operating mode, including: controlling the first solenoid valve to open and the second solenoid valve to close. Entering the first operating mode: the control module outputs a signal to energize and open the first solenoid valve, while simultaneously de-energizing and closing the second solenoid valve. At this time, the gas outlet of the reactor 100 is only connected to the first vacuum device 20.

[0069] The control switching component 10 enters the second operating mode, including: controlling the first solenoid valve to close and the second solenoid valve to open. Entering the second operating mode: the control module outputs a signal to de-energize and close the first solenoid valve, while simultaneously energizing and opening the second solenoid valve. At this time, the first pipeline is cut off, and the gas outlet of the reactor 100 is switched to be connected to the second vacuum device 30.

[0070] This embodiment uses a solenoid valve as the switching actuator, which has the advantages of fast response speed (millisecond level), good sealing performance, and simple control logic. Through interlock control (one open and one closed), it is ensured that gas can only enter one set of vacuum devices at any time, avoiding gas flow short circuit or mutual interference between the two systems, and realizing reliable and seamless switching of the vacuum system.

[0071] Example 2: The present invention also provides a vacuum system for a fixed-bed propane dehydrogenation device, such as... Figure 3 As shown, Figure 3 This is an internal structural diagram of the computer equipment of the vacuum system of a fixed-bed propane dehydrogenation device provided in an optional embodiment of the present invention, as shown below. Figure 3 As shown, the computer equipment of the vacuum system of the fixed-bed propane dehydrogenation unit includes a control module. In this embodiment, the control module is used to execute the control method of the vacuum system of the fixed-bed propane dehydrogenation unit in any of the above embodiments. The control module includes one or more processors 10, a memory 20, and interfaces for connecting the various components, including high-speed interfaces and low-speed interfaces. The various components are interconnected via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processor can process instructions executed within the vacuum system of the fixed-bed propane dehydrogenation unit, including instructions stored in or on memory to display graphical information of a GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, multiple processors and / or multiple buses can be used with multiple memories and multiple memory sets, if desired. Similarly, multiple vacuum systems of fixed-bed propane dehydrogenation units can be connected, each device providing some of the necessary operations (e.g., as a server array, a set of blade servers, or a multiprocessor system). Figure 3 Take a processor 10 as an example.

[0072] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0073] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0074] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the vacuum system of the fixed-bed propane dehydrogenation unit. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transient memory, such as at least one disk storage device, flash memory device, or other non-transient solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the vacuum system of the fixed-bed propane dehydrogenation unit via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0075] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0076] The vacuum system of the fixed-bed propane dehydrogenation unit also includes a communication interface 30 for communicating with other equipment or communication networks.

[0077] The vacuum system of the fixed-bed propane dehydrogenation unit provided in this embodiment judges the system status by monitoring the outlet gas temperature of the first vacuum device 20 and automatically switches to the second vacuum device 30 in case of an anomaly. When the temperature exceeds a preset temperature (i.e., a potential critical point of danger), this method immediately controls the first vacuum device 20 to stop operating, thereby effectively avoiding thermal damage to the core components of the first vacuum device 20 by high-temperature gas and extending the equipment's service life. Simultaneously with cutting off the first path, the switching component 10 is immediately controlled to enter the second working mode and the second vacuum device 30 (steam vacuum ejector) is started. Furthermore, under normal operating conditions where the outlet gas temperature does not exceed the preset temperature, the system defaults to using the first vacuum device 20. Since the operating energy consumption of the mechanical vacuum pump is lower than that of the steam ejector, this ensures low-energy operation of the unit for most of the time. This method, through automated control logic, can complete flow path switching and equipment start-up and shutdown instantly when the temperature exceeds the limit, eliminating the time lag and risk of misoperation associated with manual judgment and operation. Therefore, this technical solution can effectively reduce energy consumption and improve system reliability while ensuring the safety of the vacuuming process in the propane dehydrogenation unit.

[0078] In one embodiment, the vacuum system includes a controller, a switching component 10, a first vacuum device 20, and a second vacuum device 30, wherein the second vacuum device 30 is a steam vacuum ejector. The switching component 10 is located between the reactor 100, the first vacuum device 20, and the second vacuum device 30. The switching component 10 is electrically connected to the controller so as to have a first working mode and a second working mode. In the first working mode, the switching component 10 connects the outlet of the reactor 100 with the inlet of the first vacuum device 20 to form a first flow path, and disconnects the outlet of the reactor 100 from the inlet of the second vacuum device 30. In the second operating mode, the switching component 10 connects the outlet of the reactor 100 with the inlet of the second vacuum device 30 to form a second flow path, and disconnects the outlet of the reactor 100 from the inlet of the first vacuum device 20.

[0079] The vacuum system provided in this embodiment, by setting up a switching component 10, a first vacuum device 20, and a second vacuum device 30, and utilizing the switching component 10 to switch between a first operating mode and a second operating mode, achieves flexible selection and redundancy backup of the reactor 100 between two different vacuuming methods. Firstly, the second vacuum device 30 is a steam vacuum ejector, whose operation does not rely on electric drive and can still operate normally in the event of a power grid failure or failure of the electric drive equipment. When the first vacuum device 20, such as an electrically driven liquid ring vacuum pump, experiences a decrease in pumping capacity due to overload tripping, inverter failure, or pipeline leakage, the switching component 10 can quickly switch to the second operating mode, activating the second vacuum device 30 to continue the vacuuming process. This effectively avoids the mixing of residual oxygen in the reactor 100 with subsequently injected hydrogen due to insufficient vacuuming capacity, thereby significantly reducing the risk of explosion and ensuring the inherent safety of the device. Furthermore, the first vacuum pumping device 20 can employ a low-energy-consumption mechanical vacuum pump, such as a liquid ring vacuum pump, which is prioritized under normal operating conditions to significantly reduce steam consumption and operating costs. In special conditions such as abnormal steam supply, malfunction of the first vacuum pumping device 20, or the need for rapid establishment of a high vacuum, it can switch to the second vacuum pumping device 30 (steam ejector) to ensure the continuity and stability of the vacuuming process. This dual-mode redundancy design achieves energy-saving goals while retaining the high reliability advantages of traditional steam ejectors. Finally, by controlling the on / off state of the first and second flow paths through the switching component 10, the system can automatically or manually select the optimal vacuuming path based on real-time operating parameters such as steam pressure, motor current, and vacuum level. This avoids interruption of the entire reaction cycle due to the failure of a single vacuuming method, improving the operational resilience and flexibility of the fixed-bed propane dehydrogenation unit under complex conditions.

[0080] In summary, this vacuum system, through the coordinated operation of the dual vacuum devices and the switching component 10, helps to ensure the safety of the vacuuming process in the propane dehydrogenation unit while effectively reducing energy consumption and improving the system's reliability, flexibility, and adaptability.

[0081] In one embodiment, the air inlet of the first vacuum device 20 is connected to the air outlet of the reactor 100 through a first pipeline, and the air inlet of the second vacuum device 30 is connected to the air outlet of the reactor 100 through a second pipeline; the switching component includes a first solenoid valve and a second solenoid valve, the first solenoid valve being disposed on the first pipeline and the second solenoid valve being disposed on the second pipeline.

[0082] This embodiment achieves automated control of flow path switching by setting up a first pipeline, a second pipeline, and a first solenoid valve and a second solenoid valve respectively located on them. The solenoid valves can act quickly according to system signals, achieving seamless connection between the first and second working modes, reducing the time of manual operation and the risk of misoperation, and ensuring the stability of the vacuuming process.

[0083] In one embodiment, the fixed-bed propane dehydrogenation device includes multiple reactors 100. The vacuum system also includes an outlet pipe connected to the outlet of each reactor 100. The outlet pipe includes a main outlet pipe and multiple branch outlet pipes. Each branch outlet pipe corresponds to one reactor 100. The inlet of the branch outlet pipe is connected to the outlet of the corresponding reactor 100. The outlet of the branch outlet pipe is connected to the main outlet pipe. The side of the main outlet pipe away from the branch outlet pipe is connected to a first pipeline and a second pipeline. The switching assembly also includes a solenoid valve disposed on each branch outlet pipe.

[0084] In this embodiment, the above structure allows each reactor 100 to perform vacuuming independently. When a reactor 100 completes the regeneration process and needs vacuuming, only the solenoid valve of the corresponding outlet branch pipe needs to be opened, while other reactors 100 in reaction or standby states remain unaffected. This not only optimizes the pipeline layout and reduces the equipment footprint, but also improves the overall operating efficiency of the multi-reactor system.

[0085] In one embodiment, the first vacuum device 20 includes a desuperheater 21, a cooling tower 22, and a water ring vacuum pump assembly; wherein the air inlet of the desuperheater 21 is connected to the air outlet of the reactor 100 through a switching component 10, the air inlet of the cooling tower 22 is connected to the air outlet of the desuperheater 21, and the suction port of the water ring vacuum pump assembly is connected to the air outlet of the cooling tower 22, so as to compress and discharge the cooled gas.

[0086] Understandably, the gas discharged from the propane dehydrogenation reactor 100 is extremely hot (typically containing oxygen), and directly entering the mechanical pump would damage the equipment. In this embodiment, the gas is initially cooled by a desuperheater 21, then further cooled by a cooling tower 22, and finally drawn in by a water ring vacuum pump unit. This staged treatment method effectively protects the downstream mechanical equipment, while the water ring vacuum pump unit has a natural safety advantage in handling flammable, explosive, dusty, or water-containing gases.

[0087] In one embodiment, the cooling tower 22 further includes a spray nozzle for spraying quench water and a cooling tower outlet. The air inlet of the contact water spray cooling tower 22 is located between the nozzle and the cooling tower outlet in the vertical direction, and the air outlet of the contact water spray cooling tower 22 is located above the nozzle in the vertical direction.

[0088] The spatial layout of this embodiment creates a counter-current or cross-flow effect between the incoming high-temperature gas and the sprayed cooling water, increasing the gas-liquid contact time and contact area. This allows the high-temperature gas to be rapidly cooled by the quenching water, while the sprayed water also washes away impurities in the gas, preventing them from entering the subsequent vacuum pump unit and extending the equipment's service life.

[0089] In one embodiment, the spray nozzle includes a first spray nozzle 221 and a second spray nozzle 222, with the first spray nozzle 221 located below the second spray nozzle 222.

[0090] In this embodiment, the double-layer nozzle design forms a multi-stage spray zone, ensuring that the gas is fully covered and cooled during its ascent, eliminating cooling dead zones, and further improving cooling efficiency and the ultimate vacuum degree of the vacuum system.

[0091] In one embodiment, the first vacuum device 20 further includes a water circulation pump 23 and a first water circulation cooler 24. The inlet of the water circulation pump 23 is connected to the outlet of the cooling tower, the outlet of the water circulation pump 23 is connected to the inlet of the first water circulation cooler 24, and the outlet of the first water circulation cooler 24 is connected to the inlet of the spray nozzle.

[0092] Understandably, the above-mentioned circulation system enables the reuse of cooling water, saving water resources; at the same time, the first water circulation cooler 24 can continuously reduce the temperature of the circulating water, ensuring the cooling capacity of the spray water, thereby maintaining the stability of the vacuum degree of the vacuum system and avoiding a decrease in vacuum degree due to the increase in water temperature.

[0093] In one embodiment, the desuperheater 21 is provided with an atomizing nozzle to spray atomized cold water to cool the incoming high-temperature gas.

[0094] In this implementation, the atomizing nozzle sprays cooling water in an extremely fine mist, greatly increasing the specific surface area of ​​the water, allowing it to instantly absorb heat and vaporize after mixing with the high-temperature gas. This rapidly reduces the high-temperature gas at the outlet of reactor 100 to a temperature range that downstream equipment can withstand, preventing high-temperature damage to pipes and the lining of cooling tower 22.

[0095] In one embodiment, the water ring vacuum pump assembly includes an outlet separator 27 and a liquefaction vacuum pump 28; the inlet of the liquefaction vacuum pump 28 is connected to the outlet of the cooling tower 22, and the outlet of the liquefaction vacuum pump 28 is connected to the inlet of the outlet separator 27. The outlet of the outlet separator 27 is located above the inlet of the outlet separator 27 and is used to discharge the cooled gas.

[0096] The above structure utilizes the principle of gravity settling to effectively separate the gas-liquid mixture discharged from the liquefied vacuum pump 28. The gas is discharged from the top, while the liquid remains at the bottom, preventing the working fluid or condensate from being carried out of the system into the downstream pipeline network, and also reducing the loss of working fluid.

[0097] In one embodiment, the water ring vacuum pump assembly further includes a drain pump 25 and / or a second water circulation cooler 26; the inlet of the drain pump 25 is connected to the outlet at the bottom of the outlet separator 27, and the outlet of the drain pump 25 is connected to the cooling tower 22; the inlet of the second water circulation cooler 26 is connected to the outlet at the bottom of the outlet separator 27, and the outlet of the second water circulation cooler 26 is connected to the inlet of the liquefied vacuum pump 28.

[0098] In this embodiment, the drain pump 25 sends the separated liquid back to the cooling tower 22 for recycling, reducing wastewater discharge; the second water circulation cooler 26 further cools and recovers the separated gas or liquid, which helps to recover valuable process components and further increases the gas density or reduces the temperature entering the liquefied vacuum pump 28, thereby improving the pumping efficiency and operational stability of the vacuum pump group.

[0099] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered as showing the scope of this specification.

[0100] The specific embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A vacuuming method for a fixed-bed propane dehydrogenation unit, applied to the controller of a vacuuming system, wherein the fixed-bed propane dehydrogenation unit includes a reactor (100), characterized in that, The vacuum system includes a controller, a switching component (10), a first vacuum device (20), and a second vacuum device (30), wherein the second vacuum device (30) is a steam vacuum ejector; the switching component (10) is located between the reactor (100), the first vacuum device (20), and the second vacuum device (30), and the switching component (10) is electrically connected to the controller to have a first working mode and a second working mode; in the first working mode, the switching component (10) connects the outlet of the reactor (100) with the inlet of the first vacuum device (20) to form a first flow path, and disconnects the outlet of the reactor (100) from the inlet of the second vacuum device (30); in the second working mode, the switching component (10) connects the outlet of the reactor (100) with the inlet of the second vacuum device (30) to form a second flow path, and disconnects the outlet of the reactor (100) from the inlet of the first vacuum device (20); the method includes: When the first vacuum device (20) is running, the current outlet temperature of the outlet of the first vacuum device (20) is obtained in real time. The current outlet temperature is compared with the preset temperature. When the current outlet temperature exceeds the preset temperature, the switching component (10) is controlled to enter the second working mode, the first vacuum device (20) stops running and the second vacuum device (30) starts running.

2. The vacuuming method according to claim 1, characterized in that, The method further includes: After the vacuum system is started, the current state of the first vacuum device (20) is obtained; If the current state is a fault state, then control the switching component (10) to enter the second working mode and the second vacuum device (30) to operate; If the current state is normal, then control the switching component (10) to enter the first working mode and the first vacuum device (20) to operate.

3. The vacuuming method according to claim 2, characterized in that, The first vacuum pumping device (20) includes a cooling structure, an outlet liquid separator (27), and a liquefaction vacuum pump (28). The air inlet of the cooling structure is connected to the air outlet of the reactor (100) through the switching component (10). The air inlet of the liquefaction vacuum pump (28) is connected to the air outlet of the cooling structure. The air outlet of the liquefaction vacuum pump (28) is connected to the air inlet of the outlet liquid separator (27). The air outlet of the outlet liquid separator (27) is located above the air inlet of the outlet liquid separator (27) and is used to discharge the cooled gas. The method further includes: When the first vacuum pumping device (20) is running, the liquefied vacuum pump (28) is controlled to run, and the current operating current of the liquefied vacuum pump (28) is obtained in real time; When the current operating current is zero, the current state of the first vacuum pumping device (20) is changed from normal state to fault state.

4. The vacuuming method according to claim 3, characterized in that, The cooling structure includes a desuperheater (21) and a cooling tower (22); wherein the air inlet of the desuperheater (21) is connected to the air outlet of the reactor (100) through the switching assembly (10), the air inlet of the cooling tower (22) is connected to the air outlet of the desuperheater (21), and the air outlet of the cooling tower (22) is connected to the air inlet of the liquefied vacuum pump (28); controlling the operation of the second vacuum pumping device (30) includes: Control the operation of the desuperheater (21) to reduce the temperature of the incoming gas to 80-200°C; Control the operation of the cooling tower (22) to reduce the temperature of the incoming gas to 45-70°C.

5. The vacuuming method according to claim 4, characterized in that, The real-time acquisition of the current outlet temperature of the first vacuum pumping device (20) includes: The current first outlet temperature of the desuperheater (21) is obtained in real time; The step of comparing the current outlet temperature with a preset temperature, and controlling the switching component (10) to enter a second working mode, the first vacuum device (20) to stop operating, and the second vacuum device (30) to operate when the current outlet temperature exceeds the preset temperature, includes: The current first outlet temperature is compared with the first preset temperature. When the current first outlet temperature exceeds the first preset temperature, the switching component (10) is controlled to enter the second working mode, the first vacuum device (20) stops running and the second vacuum device (30) starts running, wherein the first preset temperature is between 200℃ and 205℃.

6. The vacuuming method according to claim 4, characterized in that, The real-time acquisition of the current outlet temperature of the first vacuum pumping device (20) includes: The current second outlet temperature of the cooling tower (22) is obtained in real time; The step of comparing the current outlet temperature with a preset temperature, and controlling the switching component (10) to enter a second working mode, the first vacuum device (20) to stop operating, and the second vacuum device (30) to operate when the current outlet temperature exceeds the preset temperature, includes: The current second outlet temperature is compared with the second preset temperature. When the current second outlet temperature exceeds the second preset temperature, the switching component (10) is controlled to enter the second working mode, the first vacuum device (20) stops running and the second vacuum device (30) starts running, wherein the second preset temperature is between 70°C and 75°C.

7. The vacuuming method according to claim 4, characterized in that, The desuperheater (21) is equipped with an atomizing nozzle; the control of the operation of the desuperheater (21) includes: The atomizing nozzle is controlled to spray atomized water with a droplet size of 50μm to 150μm and a temperature not higher than 50℃.

8. The vacuuming method according to claim 4, characterized in that, The cooling tower (22) also includes a spray nozzle for spraying quench water and a cooling tower outlet. The air inlet of the contact water spray cooling tower (22) is located between the nozzle and the cooling tower outlet in the vertical direction, and the air outlet of the contact water spray cooling tower (22) is located above the nozzle in the vertical direction. The control of the operation of the cooling tower (22) includes: The spray nozzles are controlled to spray cooling water with a temperature not exceeding 50°C.

9. The vacuuming method according to any one of claims 2-8, characterized in that, The air inlet of the first vacuum device (20) is connected to the air outlet of the reactor (100) through a first pipeline, and the air inlet of the second vacuum device (30) is connected to the air outlet of the reactor (100) through a second pipeline; the switching component includes a first solenoid valve and a second solenoid valve electrically connected to the controller, the first solenoid valve being located on the first pipeline, and the second solenoid valve being located on the second pipeline. The control of the switching component (10) to enter the first working mode includes: controlling the first solenoid valve to open and the second solenoid valve to close; The control of the switching component (10) to enter the second working mode includes: controlling the first solenoid valve to close and the second solenoid valve to open.

10. A vacuum system for a fixed-bed propane dehydrogenation unit, characterized in that, It includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the vacuuming method of the fixed-bed propane dehydrogenation apparatus according to any one of claims 1 to 9.

Images