An automatic valve switching control method and system for a pyrolysis furnace

Abstract

This application discloses an automatic valve switching control method and system for a cracking furnace, relating to the field of petrochemical automatic control. The method includes: determining a first valve to be closed and a second valve to be opened based on current control commands obtained from a distributed control system; determining the current switching stage based on the opening degrees of the transmission valve and the coking valve in the cracking furnace; real-time execution of a monitoring program: detecting whether the cracking furnace meets safety process requirements; if the safety process requirements are met, triggering the closure of the first valve; triggering the opening of the second valve when the first valve closes to an associated first preset opening degree, and updating the current switching stage; monitoring the current differential pressure value of the transmission valve; generating a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value; and controlling the switching of the first valve or the second valve according to the first control command. The above technical solution improves the safety and reliability of the valve switching process.

Description

Technical Field

[0001] This application relates to the field of industrial control technology, and more particularly to the field of petrochemical automatic control, specifically to a method and system for automatic switching control of cracking furnace valves. Background Technology

[0002] During the operation of a cracking furnace, it is usually necessary to coordinate and control multiple pairs of transfer valves and coke removal valves installed in multiple cracking furnaces.

[0003] Current technology typically employs manual operation. During the switch from pyrolysis mode to decoking mode, one on-site operator sets the transfer valve to the "close" command, gradually switching it from fully open to fully closed. Simultaneously, another operator precisely coordinates to set the decoking valve to the "open" command, switching it from fully closed to fully open, thus introducing material from the pyrolysis furnace pipeline into the decoking tank. When switching to hot standby mode after decoking, the valve switching operation is reversed, and material from the pyrolysis furnace pipeline is introduced into the quench oil tower, provided the hot standby conditions are met. This current operating mode has significant drawbacks: First, it heavily relies on the operator's experience and immediate reaction time. Precise synchronization of valve actions is difficult, and misalignment can easily lead to high-temperature material (around 200°C) flowing back from the quench oil tower into the decoking tank, posing a fire and personnel safety risk. Second, manual switching results in large pressure fluctuations in the pyrolysis furnace tubes, affecting their lifespan. Finally, manual operation is slow to respond, has a long switching cycle, and the results vary from person to person, resulting in poor process stability and low operating efficiency.

[0004] Therefore, existing technologies lack a reliable and automatic collaborative control mechanism, making it difficult to achieve safe, accurate, and efficient automatic control of multiple valves during the pyrolysis furnace mode switching process. Summary of the Invention

[0005] This application provides an automatic switching control method and system for pyrolysis furnace valves, which can realize safe, automatic, and precise coordinated control of the transmission valve and the coking valve during the mode switching process.

[0006] According to one aspect of this application, an automatic switching control method for a pyrolysis furnace valve is provided, executed by a switching program, the method comprising:

[0007] The first valve to be closed and the second valve to be opened are determined based on the current control commands obtained from the distributed control system.

[0008] The current switching stage of the pyrolysis furnace valves is determined based on the opening degree of the transfer valve and the coke removal valve in the pyrolysis furnace;

[0009] The monitoring program is invoked in real time to execute the following: Detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage. Also, monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter, and generate a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value.

[0010] The first control command controls the switching of the first valve or the second valve.

[0011] According to another aspect of this application, an automatic switching control system for a pyrolysis furnace valve is provided. The system includes a differential pressure transmitter disposed on a transmission valve, the differential pressure transmitter being connected to the inlet and outlet of the transmission valve respectively; an interlocking protection system connected to the transmission valve, the differential pressure transmitter, and the coke removal valve; and a distributed control system connected to the interlocking protection system. The interlocking protection system includes a switching control unit and a monitoring unit, which are respectively used to execute a switching program and a monitoring program.

[0012] The switching control unit is used to determine the first valve to be closed and the second valve to be opened according to the current control command obtained from the distributed control system; and to determine the current switching stage of the pyrolysis furnace valves according to the opening degree of the transmission valve and the coking valve in the pyrolysis furnace.

[0013] The switching control unit is used to call the monitoring unit in real time. The monitoring unit is used to perform the following: detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage. Also, monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter, and generate a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value.

[0014] The switching control unit is used to control the switching of the first valve or the second valve according to the first control command.

[0015] According to another aspect of this application, an electronic device is provided, the electronic device comprising:

[0016] At least one processor; and

[0017] A memory communicatively connected to the at least one processor; wherein,

[0018] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the automatic switching control method for pyrolysis furnace valves according to any embodiment of this application.

[0019] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the automatic switching control method for pyrolysis furnace valves according to any embodiment of this application.

[0020] According to another aspect of this application, a computer program product is provided, comprising a computer program that, when executed by a processor, implements any of the automatic switching control methods for pyrolysis furnace valves provided in the embodiments of this application.

[0021] The technical solution of this embodiment, by introducing a phased automatic switching control mechanism, brings at least the following beneficial effects: Fundamentally improving operational safety and eliminating the risk of human error: By automatically identifying the switching stage based on valve opening and coordinating the adjustment of the dual valves according to real-time differential pressure monitoring data, the precise timing and interlocking of the transmission valve and the coking valve are ensured. This fundamentally avoids safety risks such as material cross-contamination and drastic system pressure fluctuations that may occur due to misalignment during manual operation, stabilizing the valve switching process within the predetermined safety parameter range; Achieving full-process automation and improving operational efficiency and stability: The entire switching process proceeds automatically and orderly without human intervention, eliminating reliance on the operator's personal experience and immediate reaction. This not only significantly shortens the mode switching time and improves production efficiency but also ensures consistency and repeatability between different switching operations, greatly enhancing the stability of process operation; Achieving precise and reliable closed-loop control: By selecting corresponding control strategies at each switching stage and combining them with real-time monitoring, targeted closed-loop control is formed, solving the problem of limited control precision in manual operation. This ensures that the valve switching process strictly meets safety process requirements, with control quality far exceeding manual levels.

[0022] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0023] Figure 1 This is a flowchart of an automatic switching control method for a pyrolysis furnace valve provided in Embodiment 1 of this application;

[0024] Figure 2a This is a flowchart of another automatic switching control method for pyrolysis furnace valves provided according to Embodiment 2 of this application;

[0025] Figure 2b This is a schematic diagram illustrating the division of the automatic switching control process of the pyrolysis furnace valve into switching stages according to Embodiment 2 of this application;

[0026] Figure 2c This is a schematic diagram of the differential pressure graded control strategy for the transmission valve provided in Embodiment 2 of this application;

[0027] Figure 2d This is a schematic diagram of the display interface for alarm information of the distributed control system provided in Embodiment 2 of this application;

[0028] Figure 3 This is a schematic diagram of an automatic switching control system for a pyrolysis furnace valve provided according to Embodiment 3 of this application. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] Example 1

[0032] Figure 1 This is a flowchart of an automatic switching control method for pyrolysis furnace valves according to Embodiment 1 of this application. This embodiment is applicable to achieving automatic switching control of pyrolysis furnace valves without manual intervention. This method can be executed by a switching program in the automatic switching control system for pyrolysis furnace valves. Figure 1 As shown, the method includes:

[0033] S101. Determine the first valve to be closed and the second valve to be opened based on the current control command obtained from the distributed control system.

[0034] In this embodiment, the distributed control system (DCS) is used to monitor the operating status of the cracking furnace in real time and issue control commands during the automatic valve switching process. The current control command refers to the valve switching control command issued by the operator from the human-machine interface of the DCS, used to control the opening or closing of the transmission valve and the coking valve. Specifically, the current control command is a control command to switch the cracking furnace to the coking tank, which requires closing the transmission valve and opening the coking valve; the control command is a control command to switch the cracking furnace to the quench oil tower, which requires closing the coking valve and opening the transmission valve.

[0035] Specifically, based on the current control command obtained from the distributed control system, the valve that needs to be closed during the pyrolysis furnace valve switching process is identified as the first valve, and the valve that needs to be opened is identified as the second valve. If the current control command is to switch the pyrolysis furnace to the coke removal tank, the corresponding first valve is the transfer valve, and the corresponding second valve is the coke removal valve; if the current control command is to switch the pyrolysis furnace to the quench oil tower, the corresponding first valve is the coke removal valve, and the corresponding second valve is the transfer valve. By determining the first and second valves based on the current control command, automatic valve identification is achieved, enabling the valve actions corresponding to different control commands to be processed uniformly. This ensures that the subsequent valve opening and closing logic can be executed uniformly and accurately, reducing reliance on manual operation.

[0036] S102. Determine the current switching stage of the pyrolysis furnace valves based on the opening degree of the transmission valve and the coke removal valve in the pyrolysis furnace.

[0037] In this embodiment, the current switching stage is determined based on the opening degree of the transmission valve and the coking valve during the process of switching the pyrolysis furnace valve from the transmission valve to the coking removal valve or vice versa. This stage is used to identify the specific stage of the current valve adjustment operation. Specifically, multiple switching stages are pre-defined based on the valve opening degrees of the transmission valve and the coking removal valve. The current switching stage of the pyrolysis furnace valve is determined from these multiple switching stages based on the current opening degrees of the transmission valve and the coking removal valve in the pyrolysis furnace. By dividing the automatic switching process into multiple switching stages, it is convenient to set corresponding control strategies according to the pyrolysis furnace equipment conditions at different stages. Furthermore, by determining the current switching stage of the pyrolysis furnace valve in real time based on the opening degrees of the transmission valve and the coking removal valve in the pyrolysis furnace, precise staged control of the pyrolysis furnace valves is achieved, thereby improving the accuracy and reliability of valve switching.

[0038] S103. Real-time call to the monitoring program to execute: detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage; and monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter. Based on the current control strategy associated with the current switching stage, generate a first control command according to the current differential pressure value.

[0039] S104. Control the switching of the first valve or the second valve according to the first control command.

[0040] In this embodiment, safety process requirements refer to the constraints imposed on the operating parameters, valve status, material flow direction, and interlocking conditions of the pyrolysis furnace during operation and valve switching to ensure equipment safety, personnel safety, and process stability. For example, safety process requirements include, but are not limited to, the correct closure of the pyrolysis feedstock valve, the failure of dilution steam to trigger the low-flow interlock, the failure of the pyrolysis furnace tube outlet temperature to trigger the over-temperature interlock, the failure of the boiler liquid level to trigger the low-level interlock, and the failure of the furnace pressure to trigger the corresponding safety protection conditions. These safety protection conditions include, but are not limited to, high-high interlock (HH) or low-low interlock (LL); in addition, they include the failure of the pyrolysis furnace fire alarm button to be triggered, the pyrolysis furnace mode and feed meeting requirements, the quench oil isolation valve and coke air isolation valve being in the correct closed position, and the failure of the emergency stop switches in the pyrolysis furnace field and control room to be triggered. The first preset opening degree refers to the first valve closing opening threshold preset to ensure the safety of the valve switching process. The current differential pressure value refers to the pressure difference between the inlet and outlet of the transmission valve, measured and output in real time by a differential pressure transmitter installed at the transmission valve. The current control strategy refers to a preset, automated control strategy corresponding to the current switching stage, set according to the current switching stage of the pyrolysis furnace and the current differential pressure range, to regulate the opening or closing process of the first and second valves. The first control command refers to a control constraint generated based on the current differential pressure value and the current control strategy, used to regulate the first and second valves to perform corresponding control actions.

[0041] Specifically, during the automatic valve switching process of the pyrolysis furnace, the monitoring program is invoked in real time and the following steps are executed: The pyrolysis furnace continuously monitors whether it meets safety process requirements. If it does, the first valve is triggered to close, and when the first valve closes to the associated first preset opening degree, the second valve is triggered to open, and the current switching stage is updated. During this process, the current differential pressure value of the transmission valve is monitored in real time, and combined with the current control strategy associated with the current switching stage, a first control command is generated based on the current differential pressure value to control the switching operation of the first or second valve. By constructing the monitoring program and the switching program, the functions of monitoring and control are decoupled, and the division of labor is clearer. Based on the real-time detection of the pyrolysis furnace's safety process requirements, combined with the dynamic monitoring of the differential pressure status of the transmission valve and the dynamic generation of the first control command, safety constraints and coordinated control of the valve switching process are achieved. This ensures that the differential pressure of the pyrolysis furnace remains within a safe range during valve switching, thereby effectively improving the safety and overall reliability of the switching operation.

[0042] In one optional embodiment, when the first valve is a transfer valve, the first preset opening degree is 35%; when the first valve is a coking removal valve, the first preset opening degree is 10%. The specific value of the first preset opening degree is not limited to 35% or 10%, and can be adjusted according to process parameters, equipment specifications, and operational requirements in practical applications. Specifically, when the first valve is a transfer valve and the first preset opening degree is 35%, it checks whether the pyrolysis furnace meets the safety process requirements. If it does, it triggers the closure of the first valve, i.e., the closure of the transfer valve. When the first valve is closed to 35%, it triggers the opening of the second valve, i.e., the opening of the coking removal valve, and updates the current switching stage. When the first valve is a coking removal valve and the first preset opening degree is 10%, it checks whether the pyrolysis furnace meets the safety process requirements. If it does, it triggers the closure of the first valve, i.e., the closure of the coking removal valve. When the first valve is closed to 35%, it triggers the opening of the second valve, i.e., the opening of the transfer valve, and updates the current switching stage.

[0043] The technical solution of this embodiment automatically determines the current switching stage of the pyrolysis furnace valves based on the opening degree of the transmission valve and the coking valve in the pyrolysis furnace. A phased switching control mechanism is introduced during the automatic switching process of the pyrolysis furnace valves, and a corresponding control strategy is selected for each switching stage. Under the condition that the pyrolysis furnace meets the safety process requirements, combined with the real-time monitoring of the valve differential pressure status, the valve opening and closing process is coordinated and adjusted, so that the valve switching process proceeds in an orderly manner according to the predetermined stage control instructions, and the differential pressure value of the transmission valve is stably controlled within a safe range during the switching process. Thus, the controllability and safety of the pyrolysis furnace valve switching process are effectively guaranteed without manual intervention.

[0044] Example 2

[0045] Figure 2a This is a flowchart of another automatic switching control method for pyrolysis furnace valves provided in Embodiment 2 of this application. The technical solution of this embodiment further refines the determination method of the switching stage and control commands based on the technical solution of the above embodiments. For example... Figure 2a As shown, the method includes:

[0046] S210. Determine the first valve to be closed and the second valve to be opened based on the current control command obtained from the distributed control system.

[0047] S220. If the opening degree of the transmission valve in the pyrolysis furnace is greater than zero and the opening degree of the coking valve is equal to zero, then the current switching stage is the first switching stage; if the opening degrees of both the transmission valve and the coking valve in the pyrolysis furnace are greater than zero, then the current switching stage is the second switching stage; if the opening degree of the transmission valve in the pyrolysis furnace is equal to zero and the opening degree of the coking valve is greater than zero, then the current switching stage is the third switching stage.

[0048] In this embodiment, the first switching stage is when the transmission valve in the cracking furnace is open and the coking valve is closed, i.e., the transmission valve opening is greater than zero and the coking valve opening is equal to zero. The second switching stage is when both the transmission valve and the coking valve are open, i.e., both openings are greater than zero. The third switching stage is when the transmission valve is closed and the coking valve is open, i.e., the transmission valve opening is equal to zero and the coking valve opening is greater than zero. This method, combined with the characteristics of process switching, divides the switching of the transmission valve and the coking valve into three stages: First stage: the transmission valve is fully open or partially open, and the coking valve is completely closed. Second stage: the transmission valve is in the stage of partially open and just fully closed; at the same time, the coking valve is in the stage of just fully closed to partially open. Third stage: the transmission valve is completely closed; the coking valve is in the stage of partially open to fully open. Based on the above three stages, targeted control strategies are designed to realize the automatic switching of the transmission valve and the coking valve.

[0049] For example, during the automatic valve switching control process of the pyrolysis furnace, the corresponding control commands include a control command to switch the pyrolysis furnace to the coking tank, which requires closing the transmission valve and opening the coking valve; and a control command to switch the pyrolysis furnace to the quench oil tower, which requires closing the coking valve and opening the transmission valve. The switching process is divided into three stages based on the opening relationship between the transmission valve and the coking valve: in the first switching stage, the transmission valve performs an opening or closing operation; in the second switching stage, both the transmission valve and the coking valve perform opening or closing operations; and in the third switching stage, the coking valve performs an opening or closing operation.

[0050] Figure 2b This is a schematic diagram illustrating the division of the automatic switching control process of the pyrolysis furnace valve into switching stages, based on Embodiment 2 of this application. Figure 2bAs shown, Stage 1 indicates that only the transfer valve is opening or closing, while the coking valve is completely closed and not operating; Stage 2 indicates that both the transfer valve and the coking valve are opening or closing simultaneously; Stage 3 indicates that the transfer valve is completely closed, and only the coking valve is opening or closing. Stages 1 and 3 do not pose a risk of backflow, while Stage 2 carries the risk of cracked gas flowing back from the quench oil tower to the coking tank.

[0051] S230, Real-time call to the monitoring program to execute: Detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage; and monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter.

[0052] S241. If the current switching stage is the first switching stage and the current differential pressure value is less than or equal to the first differential pressure threshold, the transmission valve is allowed to open or close, and the coking valve is prohibited from opening; if the current switching stage is the first switching stage and the current differential pressure value is equal to or greater than the second differential pressure threshold, the transmission valve is prohibited from closing, and the transmission valve and the coking valve are allowed to open.

[0053] S242. If the current switching stage is the second switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the transmission valve and the coking valve are prohibited from opening, and the transmission valve and the coking valve are allowed to close; if the current switching stage is the second switching stage, and the current differential pressure value is between the third differential pressure threshold and the fourth differential pressure threshold, then the transmission valve and the coking valve are allowed to open or close; if the current switching stage is the second switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve and the coking valve are prohibited from closing, and the transmission valve and the coking valve are allowed to open.

[0054] S243. If the current switching stage is the third switching stage and the current differential pressure value is less than or equal to the first differential pressure threshold, the coking valve is allowed to open or close, and the transmission valve is prohibited from opening; if the current switching stage is the third switching stage and the current differential pressure value is equal to or greater than the second differential pressure threshold, the transmission valve and the coking valve are prohibited from closing, and the transmission valve and the coking valve are allowed to open.

[0055] Among them, the first differential pressure threshold, the third differential pressure threshold, the fourth differential pressure threshold, and the second differential pressure threshold increase sequentially.

[0056] In this embodiment, the first differential pressure threshold refers to the lower limit of the differential pressure value of the transmission valve of the pyrolysis furnace under safe operating conditions. The second differential pressure threshold refers to the upper limit of the differential pressure value of the transmission valve of the pyrolysis furnace under safe operating conditions. The third differential pressure threshold refers to the lowest differential pressure boundary that allows the transmission valve and the coking valve of the pyrolysis furnace to freely open and close during the second switching phase. The fourth differential pressure threshold refers to the highest differential pressure boundary that allows the transmission valve and the coking valve of the pyrolysis furnace to freely open and close during the second switching phase. Optionally, the first, second, third, and fourth differential pressure thresholds can be set according to actual operating conditions and safety process requirements. As an optional scheme, the first differential pressure threshold is 0.4 bar (gauge pressure), the second differential pressure threshold is 1.9 bar (gauge pressure), the third differential pressure threshold is 0.8 bar (gauge pressure), and the fourth differential pressure threshold is 1.6 bar (gauge pressure).

[0057] It should be noted that, in this application, allowing the transfer valve (or coke removal valve) to open or close means that the valve opening or closing operation is allowed to continue during the current switching phase, that is, the opening degree of the transfer valve (or coke removal valve) is allowed to increase or decrease. Prohibiting the transfer valve (or coke removal valve) from opening or closing means that the valve opening or closing operation is prohibited during the current switching phase, that is, the current valve opening degree of the transfer valve (or coke removal valve) remains unchanged.

[0058] Specifically, for each switching stage, multiple differential pressure ranges are pre-defined based on a set differential pressure threshold. Within each switching stage, control strategies that match different differential pressure ranges and meet process safety requirements are configured. During the automatic switching control of the pyrolysis furnace valve, the current switching stage of the pyrolysis furnace valve is identified in real time, and the current differential pressure value is obtained synchronously. Under the control strategy corresponding to the switching stage, the appropriate control command is selected based on the threshold range into which the current differential pressure value falls, and the transmission valve and the coking valve are coordinated and adjusted to achieve stable and controllable operation of the switching process while ensuring process safety.

[0059] For example, if the current switching stage is the first switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, it indicates that the current cracking furnace may be at risk of low-pressure operation. In this case, the transmission valves that are in the open state are allowed to continue to open or close, while the coking valves that are in the closed state are prohibited from opening. By adjusting only the transmission valves that are already open in the current switching stage and avoiding the introduction of new valve flow paths, the differential pressure of the cracking furnace can be gradually increased and tend to the safe differential pressure range. If the current switching stage is the first switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, it indicates that the current cracking furnace may be at risk of high-pressure operation. In this case, the transmission valves that are in the open state are prohibited from continuing to close, while the transmission valves and coking valves are allowed to continue to open. By keeping the valves open to release pressure, the system differential pressure can be alleviated, local pressure buildup or pressure shock can be prevented, thereby ensuring the safe and stable operation of the cracking furnace and related equipment during the switching process.

[0060] For example, if the current switching stage is the second switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, it indicates that the current cracking furnace may be at risk of low-pressure operation. In this case, the transmission valve and the coking valve are prohibited from continuing to open, while the transmission valve and the coking valve are allowed to continue to close. By adjusting only the transmission valves that are already open in the current switching stage and avoiding the introduction of new valve flow paths, the differential pressure of the cracking furnace is gradually increased and tends to the safe differential pressure range. If the current switching stage is the second switching stage, and the current differential pressure value is between the third and fourth differential pressure thresholds, it indicates that the current cracking furnace is in a controllable and safe range, and it is allowed to remain open. The transmission valve and coke removal valve can continue to be opened or closed. Under the premise of ensuring process safety, the valve operation can be freely performed according to process requirements to achieve normal operation of the switching stage. If the current switching stage is the second switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, it indicates that there may be a high pressure risk in the current cracking furnace. At this time, the transmission valve and coke removal valve that are in the open state must not be closed, and the transmission valve and coke removal valve are allowed to continue to be open. By keeping the valves open, pressure is released, the system differential pressure is relieved, and local pressure buildup or pressure shock is prevented, thereby ensuring the safe and stable operation of the cracking furnace and related equipment during the switching process.

[0061] For example, if the current switching stage is the third switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, it indicates that the current cracking furnace may be at risk of low-pressure operation. In this case, the coking valve that is in the open state is allowed to continue to open or close, and the transmission valve that is in the closed state is prohibited from opening. By adjusting only the transmission valve that is already open in the current switching stage and avoiding the introduction of new valve flow paths, the differential pressure of the cracking furnace can be gradually increased and tend to the safe differential pressure range. If the current switching stage is the third switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, it indicates that the current cracking furnace may be at risk of high-pressure operation. In this case, the transmission valve and coking valve are prohibited from continuing to close, and the transmission valve and coking valve are allowed to continue to open. By keeping the valves open to release pressure, the system differential pressure is relieved, local pressure buildup or pressure shock is prevented, thereby ensuring the safe and stable operation of the cracking furnace and related equipment during the switching process.

[0062] S250: Control the switching of the first valve or the second valve according to the first control command.

[0063] The technical solution in this embodiment further refines the determination method of switching stages and control commands. Based on the switching process of the transmission valve and the coking valve, the entire automatic valve switching process of the pyrolysis furnace is divided into three switching stages. For each switching stage, different control strategies and valve operation control commands are determined according to the current differential pressure value. By setting the differential pressure range and corresponding control commands for each switching stage, the differential pressure of the pyrolysis furnace is controlled within a safe range, ensuring that it is always in a feasible and safe working state during the automatic switching process of the transmission valve and the coking valve. This avoids process risks and equipment damage risks caused by excessively low or high current differential pressure values ​​of the pyrolysis furnace transmission valve, effectively achieving stable switching of the pyrolysis furnace valves and improving the overall safety and reliability of operation.

[0064] In one optional implementation, the method further includes: when the current switching stage is in the second switching stage, a monitoring program is invoked to monitor whether the current differential pressure value is lower than a preset differential pressure lower limit; if it is lower than the differential pressure lower limit, a second control command is generated; and the switching of the first valve or the second valve is controlled according to the second control command.

[0065] In this embodiment, the lower limit of differential pressure refers to the minimum safe differential pressure value at which, during the second switching phase, the current differential pressure value of the transmission valve is lower than the set value, potentially causing material from the quench oil tower to flow back into the coking tank, thus posing a risk of fire and personal injury. The second control command is a control command automatically triggered during the second switching phase when the current differential pressure value of the transmission valve is lower than the lower limit of differential pressure. Its function is to adjust the opening state of the first or second valve to prevent safety problems caused by excessively low differential pressure, ensuring that the pyrolysis furnace operates stably within a safe differential pressure range.

[0066] Specifically, during the second switching phase, both the transfer valve and the decoking valve in the pyrolysis furnace are open. If the differential pressure is too low, material may flow in the wrong direction. The monitoring program checks if the current differential pressure is below a preset lower limit. If it is, a second control command is generated in real time to adjust the opening of the first and second valves, ensuring the differential pressure remains within a safe range. This method, by generating corresponding control commands to adjust valve openings, prevents backflow, avoids the risk of fire and personnel injury caused by material flowing back from the quench oil tower to the decoking tank, and ensures the normal operation and process safety of the pyrolysis furnace.

[0067] In one optional implementation, if the pressure difference is below the lower limit, a second control command is generated, including: if the pressure difference is below the lower limit, the first valve to be closed is paused from closing, and the second valve to be opened continues to open, until the current pressure difference is above the lower limit and the first valve to be closed is reopened.

[0068] Specifically, when the differential pressure falls below the lower limit, the generated second control command suspends the closure of the first valve to be closed to prevent further reduction in differential pressure and the risk of backflow. Simultaneously, the second valve to be opened continues to open to increase the flow rate and promote a recovery in differential pressure until the current differential pressure exceeds the lower limit, at which point the first valve to be closed is closed again. By generating the second control command, when the differential pressure falls below the lower limit, the closure of the first valve to be closed is suspended while the second valve to be opened continues to open, effectively preventing backflow problems caused by excessively low differential pressure and ensuring the stability of the cracking furnace operation.

[0069] In one alternative implementation, two differential pressure transmitters are installed on the transmission valve, each connected to the inlet and outlet of the transmission valve, respectively. A two-to-two voting logic is used to monitor the current differential pressure between the inlet and outlet of the transmission valve.

[0070] Specifically, two differential pressure transmitters are installed on each of the transmission valves. Each transmitter is connected to both the inlet and outlet of the transmission valve to measure the current differential pressure between them. Based on the differential pressure values ​​collected by the two transmitters, subsequent control logic is used for judgment. Only when the control commands corresponding to the current differential pressure values ​​collected by the two transmitters are consistent is the control command considered valid, and the switching operation of the pyrolysis furnace valve is controlled. This method ensures the accuracy of the control results, avoids unnecessary erroneous or ineffective adjustments during the control process, and improves system stability and safety.

[0071] In one optional implementation, the method further includes: obtaining the stroke values ​​of the transmission valve and the coke removal valve through an interlocking protection system, predicting the predicted valve opening of the transmission valve and the coke removal valve based on the stroke values; comparing the predicted valve opening with the detected actual valve opening, and determining whether there is valve jamming based on the comparison result; if valve jamming is present, pausing the switching procedure.

[0072] In this embodiment, the interlocking protection system monitors the status of valves and equipment and provides coordinated protection by controlling the interrelationships and protection mechanisms between multiple devices and sensors in the system. The stroke value refers to the theoretical displacement of the drive motor corresponding to the valve under control commands, used to predict the theoretical valve opening at any given time. The predicted valve opening refers to the theoretical valve position predicted based on the valve stroke value, used to determine the valve opening that should be achieved under the current operating state. The actual valve opening refers to the true valve opening measured by sensors on the valve, used to reflect the actual operating state of the valve.

[0073] Specifically, during valve switching, the interlocking protection system acquires the stroke values ​​of the transmission valve and the coking valve, and predicts their opening degrees based on this. Simultaneously, it monitors the actual valve openings of the transmission valve and the coking valve in real time, comparing the predicted and actual openings. When the deviation reaches a preset threshold, valve jamming is detected, the switching process is paused, and an alarm is automatically issued awaiting operator inspection and handling. This method proactively predicts valve jamming, ensuring safe switching. Specifically, by comparing the predicted and actual valve openings, abnormal valve movement can be promptly identified and subsequent actions interrupted, preventing equipment damage or process risks caused by valve jamming and improving the safety and reliability of the valve switching process.

[0074] For example, during the valve switching process in the pyrolysis furnace, the stroke detection module acquires the stroke values ​​of the drive motors corresponding to the transmission valve and the coking valve in real time. Based on the mechanical correspondence between the motor stroke value and the valve movement, the theoretically expected valve opening is calculated. Simultaneously, the actual valve opening is acquired by a sensor. If the actual valve opening deviates from the predicted valve opening calculated based on the stroke, and the deviation exceeds a preset deviation threshold, it indicates that the drive motor has been idling while the valve has failed to move synchronously. This indicates a risk of valve jamming and triggers a pause switching procedure to take corresponding protective measures. Optionally, the preset deviation threshold can be set based on experience or actual engineering requirements. One possible solution is to set it to fluctuate by 3.5% above or below the predicted valve opening.

[0075] In one optional embodiment, detecting whether the pyrolysis furnace meets the safety process requirements further includes: if the safety process requirements are not met, pausing the switching procedure and keeping the opening of the first valve and the second valve unchanged.

[0076] Specifically, if the current operating conditions are determined not to meet safety process requirements, the switching procedure is immediately suspended, and the current opening degrees of the first and second valves remain unchanged. This method automatically performs periodic fault checks to ensure safe switching and prevent potential safety risks. Specifically, by suspending the switching procedure and maintaining the valve opening degree when safety process requirements are not met, it effectively avoids valves from continuing to operate under unstable conditions and ensures that all valve switching operations are performed under the premise of meeting safety process requirements, thereby improving the stability and safety of automatic valve switching in the pyrolysis furnace.

[0077] Optionally, the conditions that can trigger the pause switching procedure include, in addition to safety process requirements, equipment requirements and fire condition requirements. Equipment requirements include, but are not limited to, the transmission valve not triggering a hardware alarm and the descaling valve not triggering a hardware alarm. Fire condition requirements refer to a safe and stable on-site environment, ensuring that no fire or related safety accidents will occur under these conditions. Upon the occurrence of a fire condition, the high-temperature interlock is triggered, the switching procedure is paused, the transmission valve is switched to the closed state, the descaling valve remains open, and the alarm signal is displayed on the distributed control system's visual operation page, notifying the operator to handle the situation according to fire conditions.

[0078] Optionally, after pausing the switching procedure and waiting for the current problem to be resolved, the latest control commands can be retrieved from the distributed control system, along with the opening degrees of the transmission valves and coke removal valves in the pyrolysis furnace. Based on this, the current switching stage of the pyrolysis furnace valves can be reassessed, and subsequent valve control commands can be regenerated by combining the latest control commands with the current switching stage, thereby achieving the orderly resumption of valve operation while meeting safety process requirements.

[0079] Figure 2c This is a schematic diagram of the differential pressure graded control strategy for the transmission valve provided in Embodiment 2 of this application, as shown below. Figure 2c The left vertical axis represents differential pressure (unit: bar), with a range of 0.00 bar to 5.00 bar. The vertical axis is set from bottom to top as follows: LL = 0.10 bar (low-low interlock value, low danger limit), LO = 0.20 bar (low alarm or lower operating limit), the middle is the normal operating range, H = 3.80 bar (high alarm value), and HH = 4.00 bar (high-high interlock value, high danger limit). The curve in the figure shows the dynamic change trend of differential pressure over time during the operation of the transmission valve. A curve fluctuation range between 0.20 bar and 3.80 bar indicates that the current equipment is in the normal operating range and no alarm or interlock action has been triggered.

[0080] In one optional embodiment, the automatic valve switching method for the cracking furnace described in this application can be applied to the C2 section cracking furnace process system of an ethylene plant, such as the C2 Low Pressure Protection (LOP) system. Table 1 shows the differential pressure control setting range for the cracking furnace process system. The control setting range for the differential pressure values ​​of the transmission valves of the nine cracking furnaces in this system under different unit (A, B) and different flow directions is given. Specifically, the upper and lower limits of the differential pressure are given according to the two transmission directions: "from the coke cleaning tank to the quench oil tower" and "from the quench oil tower to the coke cleaning tank," respectively, in bar. Each cracking furnace has different allowable differential pressure operating ranges in different flow directions based on its structure, pipeline layout, and process resistance differences. This range is jointly defined by the upper and lower limits of the differential pressure, serving as the control boundary conditions for the automatic valve switching control method of the cracking furnace. When the real-time monitored differential pressure of the transmission valve is between the upper and lower limits, it is considered to meet the safe operating conditions; if it approaches the boundary value, it enters the warning zone; if it exceeds the range, an alarm or interlock logic is triggered. By setting differentiated differential pressure ranges for each cracking furnace and each transmission direction, the automatic switching control has clear safety criteria in different operating modes, thereby ensuring that the differential pressure is always controlled during the switching process between the transmission valve and the coking valve. Through refined safety control, the risk of stress imbalance or even rupture in the cracking furnace due to abnormal differential pressure in the transmission valve is avoided.

[0081]

[0082] For example, an alarm message indicating a pause is generated in the interlocking protection system and transmitted from the interlocking protection system to the distributed control system, where it is displayed to the operator. Figure 2d This is a schematic diagram of the display interface for alarm information of the distributed control system provided in Embodiment 2 of this application, as shown below. Figure 2dAs shown, during the operation and mode switching of the pyrolysis furnace, various operating status signals and safety status signals are centrally monitored and visualized through system linkage to form alarm, permission, start, and switching status displays. Taking a pyrolysis furnace as an example, the interlock protection system executes from top to bottom according to the logical program. Within one execution cycle, it scans all states that may cause the switching program to pause, including: whether each process safety parameter is consistent with the required state; whether the transfer valve and decoking valve themselves have fault alarms; whether the pyrolysis furnace is in a fire condition; whether there are valve jams in the pyrolysis furnace; whether the pyrolysis furnace has been manually paused by the on-site operator; if a state change that may cause the switching program to pause is detected, the alarm signal is immediately recorded and displayed on the visualization interface of the distributed control system; after the alarm is reset, the alarm information detection resumes; at the same time, the operator can automatically operate and monitor the switching operation of the transfer valve and decoking valve in the distributed control system; when the program pauses, the operator can see the alarm signal that caused the switching program to pause from the distributed control system, and then quickly handle the fault according to the signal indication to ensure that the switching continues, thus realizing process safety assurance for the entire automatic switching process. Meanwhile, the operator's operations are carried out in the distributed control system. The switching program and monitoring program that realize the automatic switching method logic function are deployed in the interlocking protection system. This ensures that the interlocking protection system can still be executed normally even if the distributed control system fails, thus ensuring the process safety during the automatic switching of the pyrolysis furnace valve.

[0083] The technical solution of this embodiment, by introducing a phased automatic switching control mechanism, brings at least the following beneficial effects:

[0084] (1) Based on the characteristics of process switching, the switching of the transmission valve and the coking valve is divided into three stages: the first stage: the transmission valve is fully open or partially open, and the coking valve is completely closed; the second stage: the transmission valve is in the stage of being partially open and just completely closed, and the coking valve is in the stage of being just completely closed to being partially open; the third stage: the transmission valve is completely closed, and the coking valve is in the stage of being partially open to being fully open. Based on the above three stages, targeted control strategies were designed to realize the automatic switching of the transmission valve and the coking valve.

[0085] (2) Fundamentally improve operational safety and eliminate the risk of human error: By automatically identifying the switching stage based on the valve opening and coordinating the adjustment of the two valves according to the real-time differential pressure monitoring data, and actively predicting valve jamming and automatic fault checking, safe switching is ensured and any possible safety risks are prevented. The precise timing coordination and interlocking of the operation of the transmission valve and the coking valve are ensured, fundamentally avoiding safety risks such as material cross-contamination and severe fluctuations in system pressure that may be caused by coordination deviations during manual operation, and stabilizing the valve switching process within the predetermined safety parameter range.

[0086] (3) Achieve full-process automation and improve operational efficiency and stability: The entire switching process proceeds automatically and orderly without human intervention, eliminating the reliance on the operator's personal experience and immediate response. This not only significantly shortens the mode switching time and improves production efficiency, but also ensures consistency and repeatability between different switching operations, greatly improving the stability of process operation.

[0087] (4) Achieve precise and reliable closed-loop control: By selecting the corresponding control strategy at each switching stage and combining it with real-time monitoring, a targeted closed-loop control is formed, which solves the problem of limited control accuracy of manual operation, so that the valve switching process can strictly meet the safety process requirements and the control quality far exceeds the level of manual operation.

[0088] Example 3

[0089] Figure 3 This is a schematic diagram of an automatic switching control system for a pyrolysis furnace valve according to Embodiment 3 of this application, as shown below. Figure 3 As shown, the specific structure of the automatic valve switching control system for the pyrolysis furnace is as follows:

[0090] The system includes a differential pressure transmitter 320 installed on the transmission valve 310, the differential pressure transmitter 320 being connected to the inlet and outlet of the transmission valve 310 respectively; an interlocking protection system 340 connected to the transmission valve 310, the differential pressure transmitter 320, and the coke removal valve 330; and a distributed control system 350 connected to the interlocking protection system 340. The interlocking protection system 340 includes a switching control unit 341 and a monitoring unit 342, which are used to execute switching procedures and monitoring procedures respectively. The system also includes a cracking furnace 360 ​​connected to the transmission valve 310 and the coke removal valve 330, a quench oil tower 370 connected to the transmission valve 310, and a coke removal tank 380 connected to the coke removal valve 330.

[0091] The switching control unit 341 is used to determine the first valve to be closed and the second valve to be opened according to the current control command obtained from the distributed control system; and to determine the current switching stage of the valves in the pyrolysis furnace 360 ​​according to the opening degree of the transmission valve 310 and the coke removal valve 330 in the pyrolysis furnace 360.

[0092] The switching control unit 341 is used to call the monitoring unit 342 in real time. The monitoring unit 342 is used to perform the following: detect whether the pyrolysis furnace 360 ​​meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage. Also, monitor the current differential pressure value between the inlet and outlet of the transmission valve 310 obtained from the differential pressure transmitter 320, and generate a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value.

[0093] The switching control unit 341 is used to control the switching of the first valve or the second valve according to the first control command.

[0094] In one alternative embodiment, the switching control unit 341 is specifically used for:

[0095] If the opening degree of the transmission valve 310 in the pyrolysis furnace 360 ​​is greater than zero, and the opening degree of the coke removal valve 330 is equal to zero, then the current switching stage is the first switching stage.

[0096] If the opening degree of both the transmission valve 310 and the coke removal valve 330 in the pyrolysis furnace 360 ​​is greater than zero, then the current switching stage is the second switching stage.

[0097] If the opening degree of the transmission valve 310 in the pyrolysis furnace 360 ​​is equal to zero, and the opening degree of the coke removal valve 330 is greater than zero, then the current switching stage is the third switching stage.

[0098] In one alternative embodiment, the switching control unit 341 is specifically used for:

[0099] If the current switching stage is the first switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the transmission valve 310 is allowed to open or close, and the coking valve 330 is prohibited from opening; if the current switching stage is the first switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve 310 is prohibited from closing, and the transmission valve 310 and the coking valve 330 are allowed to open.

[0100] If the current switching stage is the second switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the transmission valve 310 and the coke removal valve 330 are prohibited from opening, and the transmission valve 310 and the coke removal valve 330 are allowed to close; if the current switching stage is the second switching stage, and the current differential pressure value is between the third differential pressure threshold and the fourth differential pressure threshold, then the transmission valve 310 and the coke removal valve 330 are allowed to open or close; if the current switching stage is the second switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve 310 and the coke removal valve 330 are prohibited from closing, and the transmission valve 310 and the coke removal valve 330 are allowed to open.

[0101] If the current switching stage is the third switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the coking valve 330 is allowed to open or close, and the transmission valve 310 is prohibited from opening; if the current switching stage is the third switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve 310 and the coking valve 330 are prohibited from closing, and the transmission valve 310 and the coking valve 330 are allowed to open.

[0102] The first differential pressure threshold, the third differential pressure threshold, the fourth differential pressure threshold, and the second differential pressure threshold increase sequentially.

[0103] In one alternative embodiment, the switching control unit 341 is specifically used for:

[0104] When the current switching phase is in the second switching phase, the monitoring program is also invoked to monitor whether the current differential pressure value is lower than the preset differential pressure lower limit. If it is lower than the differential pressure lower limit, a second control command is generated.

[0105] The switching of the first valve or the second valve is controlled according to the second control command.

[0106] In one alternative embodiment, the switching control unit 341 is specifically used for:

[0107] If the pressure difference is lower than the lower limit, the first valve to be closed will be temporarily closed, and the second valve to be opened will continue to be opened until the current pressure difference is higher than the lower limit, at which point the first valve to be closed will be closed again.

[0108] In one optional embodiment, the automatic switching control system for the pyrolysis furnace valve is specifically used for:

[0109] When the first valve is a transmission valve 310, the first preset opening degree is 35%; when the first valve is a coke removal valve 330, the first preset opening degree is 10%.

[0110] In one optional embodiment, the automatic switching control system for the pyrolysis furnace valve is specifically used for:

[0111] Two differential pressure transmitters 320 are installed on the transmission valve 310. Each differential pressure transmitter 320 is connected to the inlet and outlet of the transmission valve 310, respectively. A two-to-two voting logic is used to monitor the current differential pressure between the inlet and outlet of the transmission valve 310.

[0112] In one optional embodiment, the automatic switching control system for the pyrolysis furnace valve is specifically used for:

[0113] The interlock protection system 340 obtains the stroke values ​​of the transmission valve 310 and the coke removal valve 330, and predicts the valve opening of the transmission valve 310 and the coke removal valve 330 based on the stroke values.

[0114] Compare the predicted valve opening with the detected actual valve opening, and determine whether valve jamming exists based on the comparison result;

[0115] If valve jamming occurs, the switching procedure should be paused.

[0116] In one alternative embodiment, the automatic switching control system for the pyrolysis furnace valve can also be used for:

[0117] If the safety process requirements are not met, the switching procedure will be paused, and the opening degrees of the first valve and the second valve will remain unchanged.

[0118] The automatic switching control system for pyrolysis furnace valves provided in this application can execute the automatic switching control method for pyrolysis furnace valves provided in any embodiment of this application, and has the corresponding functional modules and beneficial effects of the method.

[0119] This application also provides an electronic device, a readable storage medium, and a computer program product. The computer-readable storage medium stores a computer program that, when executed by a processor, implements the automatic switching control method for arbitrary pyrolysis furnace valves of this application.

Claims

1. A method for automatic switching control of pyrolysis furnace valves, characterized in that, Executed by the switching procedure, the method includes: The first valve to be closed and the second valve to be opened are determined based on the current control commands obtained from the distributed control system. The current switching stage of the pyrolysis furnace valves is determined based on the opening degree of the transfer valve and the coke removal valve in the pyrolysis furnace; The monitoring program is invoked in real time to execute the following: Detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage. Also, monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter, and generate a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value. The first control command controls the switching of the first valve or the second valve.

2. The method according to claim 1, characterized in that, The process of determining the current switching stage of the pyrolysis furnace valves based on the opening degree of the transfer valve and the coke removal valve in the pyrolysis furnace includes: If the opening degree of the transfer valve in the pyrolysis furnace is greater than zero and the opening degree of the coke removal valve is equal to zero, then the current switching stage is the first switching stage. If the opening degree of both the transfer valve and the coke removal valve in the pyrolysis furnace is greater than zero, then the current switching stage is the second switching stage. If the opening degree of the transfer valve in the pyrolysis furnace is zero and the opening degree of the coke removal valve is greater than zero, then the current switching stage is the third switching stage.

3. The method according to claim 2, characterized in that, The first control command, generated based on the current control strategy associated with the current switching phase and according to the current differential pressure value, includes: If the current switching stage is the first switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the transmission valve is allowed to open or close, and the coking valve is prohibited from opening; if the current switching stage is the first switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve is prohibited from closing, and the transmission valve and the coking valve are allowed to open. If the current switching phase is the second switching phase, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the transmission valve and the coking valve are prohibited from opening, and the transmission valve and the coking valve are allowed to close; if the current switching phase is the second switching phase, and the current differential pressure value is between the third differential pressure threshold and the fourth differential pressure threshold, then the transmission valve and the coking valve are allowed to open or close; if the current switching phase is the second switching phase, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve and the coking valve are prohibited from closing, and the transmission valve and the coking valve are allowed to open. If the current switching stage is the third switching stage, and the current differential pressure value is less than or equal to the first differential pressure threshold, then the coking valve is allowed to open or close, and the transmission valve is prohibited from opening; if the current switching stage is the third switching stage, and the current differential pressure value is equal to or greater than the second differential pressure threshold, then the transmission valve and the coking valve are prohibited from closing, and the transmission valve and the coking valve are allowed to open. The first differential pressure threshold, the third differential pressure threshold, the fourth differential pressure threshold, and the second differential pressure threshold increase sequentially.

4. The method according to claim 1, characterized in that, The method further includes: When the current switching phase is in the second switching phase, the monitoring program is also invoked to monitor whether the current differential pressure value is lower than the preset differential pressure lower limit. If it is lower than the differential pressure lower limit, a second control command is generated. The switching of the first valve or the second valve is controlled according to the second control command.

5. The method according to claim 4, characterized in that, If the pressure difference is lower than the lower limit, a second control command is generated, including: If the pressure difference is lower than the lower limit, the first valve to be closed will be temporarily closed, and the second valve to be opened will continue to be opened until the current pressure difference is higher than the lower limit, at which point the first valve to be closed will be closed again.

6. The method according to claim 1, characterized in that, When the first valve is a transmission valve, the first preset opening degree is 35%; when the first valve is a descaling valve, the first preset opening degree is 10%.

7. The method according to claim 1, characterized in that, Two differential pressure transmitters are installed on each of the transmission valves. Each differential pressure transmitter is connected to the inlet and outlet of the transmission valve, respectively. A two-to-two voting logic is used to monitor the current differential pressure between the inlet and outlet of the transmission valve.

8. The method according to claim 1, characterized in that, The method further includes: The stroke values ​​of the transmission valve and the coke removal valve are obtained through the interlocking protection system, and the predicted valve opening of the transmission valve and the coke removal valve is predicted based on the stroke values. Compare the predicted valve opening with the detected actual valve opening, and determine whether valve jamming exists based on the comparison result; If valve jamming occurs, the switching procedure should be paused.

9. The method according to claim 1, characterized in that, The method for detecting whether the pyrolysis furnace meets the safety process requirements also includes: If the safety process requirements are not met, the switching procedure will be paused, and the opening degrees of the first valve and the second valve will remain unchanged.

10. An automatic switching control system for pyrolysis furnace valves, characterized in that, The system includes a differential pressure transmitter installed on the transmission valve, the differential pressure transmitter being connected to the inlet and outlet of the transmission valve respectively; an interlocking protection system connected to the transmission valve, the differential pressure transmitter and the coke removal valve; and a distributed control system connected to the interlocking protection system; the interlocking protection system includes a switching control unit and a monitoring unit, which are used to execute switching procedures and monitoring procedures respectively. The switching control unit is used to determine the first valve to be closed and the second valve to be opened according to the current control command obtained from the distributed control system; and to determine the current switching stage of the pyrolysis furnace valves according to the opening degree of the transmission valve and the coking valve in the pyrolysis furnace. The switching control unit is used to call the monitoring unit in real time. The monitoring unit is used to perform the following: detect whether the pyrolysis furnace meets the safety process requirements. If the safety process requirements are met, trigger the closure of the first valve. When the first valve is closed to the associated first preset opening degree, trigger the opening of the second valve and update the current switching stage. Also, monitor the current differential pressure value between the inlet and outlet of the transmission valve obtained from the differential pressure transmitter, and generate a first control command based on the current control strategy associated with the current switching stage and the current differential pressure value. The switching control unit is used to control the switching of the first valve or the second valve according to the first control command.

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