A sequential control method and control system for one-key starting of a chemical fiber raw material device

Abstract

The application belongs to the technical field of chemical fiber raw material device control, and discloses a sequence control method for one-key starting of a chemical fiber raw material device and a sequence control system for one-key starting of the chemical fiber raw material device, realizes successful application of a chemical fiber raw material main device control system on a large-scale chemical fiber raw material integrated device, improves a reactor feeding rate to a specific load by controlling various parameters of an oxidation reactor and related equipment and through a sequence control program written in advance, monitors progress of a key starting stage in real time, prevents safety hazards, reduces use and connection of function blocks, makes the program simple and readable, improves sequence control performance, and reduces a control system load.

Description

Technical Field

[0001] This invention relates to the field of chemical fiber raw material equipment control technology, and in particular to a sequential control method and control system for one-button start-up of a chemical fiber raw material equipment. Background Technology

[0002] Because the production process of chemical fiber raw materials involves high temperature, high pressure, flammability, explosiveness, toxicity, corrosion, and radioactivity, it is the most typical and dangerous production environment. This places high demands on the reliability of the control system manufacturer's products, its understanding of the chemical fiber raw material process, and its engineering implementation capabilities. Previously, foreign import manufacturers had a monopoly in the field of control systems for the main equipment of chemical fiber raw materials, so they are committed to breaking this awkward situation.

[0003] Currently, no domestically produced control systems or central control systems have been applied to chemical fiber raw material plants, and therefore no one-button start-up solution has been implemented. For similar processes, existing technologies typically use FBD combined with ST programming language.

[0004] Previously, understanding of the equipment characteristics, process flow, and control scheme was limited to paper documents and simulation platforms. Furthermore, existing technologies using FBD programming consume significant resources such as program and function blocks, resulting in poor readability and inconvenient debugging. Simply using ST language for programming offers very limited program monitoring, requiring manual intervention with numerous variables to monitor program status. Employing ultra-large-scale sequential control using traditional FBD and ST languages ​​demands substantial time and effort from designers to design program interfaces and complex structures, hindering template creation and program reuse. Existing technologies lack practical experience and application records in specific chemical fiber raw material plants, making it difficult to gain acceptance from users and other stakeholders. The absence of a one-button start / stop system increases the risk of operational errors during start-up, impacting safe production, and results in lengthy start-up cycles. Summary of the Invention

[0005] The purpose of this invention is to enable the successful application of the main control system for chemical fiber raw materials in large-scale integrated chemical fiber raw material equipment. To solve the above problems, this invention provides the following technical solution: a sequential control method for one-button start-up of a chemical fiber raw material equipment, comprising the following steps:

[0006] S1. The operator presets and checks the parameters required for system operation, then runs the start-up sequence control, detects the flow rate of raw material feed, and releases operating permissions to the operator in stages according to the start-up phase;

[0007] S2. After the flow rate detection is passed, an air test is performed to monitor the air flow rate and ensure it reaches the preset value;

[0008] S3. After the air flow rate reaches the preset value, the liquid raw material is fed in, and the flow rate of the liquid raw material begins to increase. 30 seconds after the liquid raw material reaches the preset value, the air is fed in, and the air flow rate begins to increase.

[0009] S4. Monitor the pressure inside the reactor and start the agitator, distillation column and high-pressure absorption column in sequence according to different stages of reactor load; S5. After the load reaches the preset value, the distillation column no longer self-circulates and directly returns to the reactor to control the reactor temperature and water content. The whole system operates automatically.

[0010] To achieve one-click start-up of the oxidation unit of the chemical fiber raw material plant, this invention requires controlling various parameters of the oxidation reactor and related equipment, and increasing the reactor feed rate to a specific load through a pre-written sequential control program. To ensure the safety of the entire process, close and timely interaction between the safety system's ESD logic and the DCS control system is required to monitor the progress of critical startup stages. DCS, short for Distributed Control System, is a new generation of instrument control system based on microprocessors. It employs a design principle that distributes control functions while centralizing display and operation, balancing autonomy and comprehensive coordination. By detecting the flow rates of raw materials and reactants before the reaction, the safety system monitors each stage of system operation in real time. If an error occurs in any stage or a problem arises with the raw materials, the reaction can be stopped immediately to prevent accidents. By monitoring the pressure inside the reactor, devices at each stage of the system are started sequentially according to different reactor load stages, replacing manual intervention. This method automates the operation of the chemical fiber raw material unit. All steps before the reactor load reaches a preset value can be manually interrupted to prevent operational errors. After the reactor load reaches the preset value, the reaction stabilizes, and the system automatically adjusts the temperature and water content inside the reactor based on the reaction conditions. The entire system then begins automatic and stable operation. Operators can also adjust the load by adjusting the air feed.

[0011] Preferably, in step S4, the reactor load is increased. When the reactor load reaches 10%, the stirrer is started to ensure that the reaction mixture crystallizes into a slurry. When the air load reaches a specific set value, the device has a certain atmospheric pressure. The high-pressure absorber is started to increase the reactor pressure and raise the reactor temperature. When the reactor load reaches 15%, the liquid level in the reactor container increases further. The liquid level control module of the high-pressure absorber is started to control the liquid level in the high-pressure absorber. When the reactor load reaches 25%, the reflux control module is started to control the liquid level in the high-pressure absorber and recover the solvent at the same time.

[0012] The reactor agitator of this invention is crucial for the safe and efficient production of products in each reactor. Its function is to ensure that the reaction mixture crystallizes into a slurry and breaks up airflow into small bubbles, thereby increasing the rate at which oxygen dissolves into the solvent. The agitator speed needs to be automatically adjusted at each stage of the reaction. The high-pressure absorber can increase the reactor pressure, which can raise the reactor temperature. Even small changes in reactor temperature can have a significant impact on the reaction rate. To avoid an excessively fast reaction rate, the reactor pressure cannot be too low; however, low-pressure operation will increase the load on the condenser at the top of the reactor. Therefore, the pressure must be controlled within a reasonable range.

[0013] Preferably, in step S5, the preset value is 30%. When the reactor load reaches 30%, the first distillation column connected to the reactor stops self-circulation, the reflux control module controls the reflux of the first distillation column and the reactor, and starts the second distillation column connected to the first distillation column. The reflux control module controls the second distillation column to perform reflux. At this point, the start-up sequence is completed, all operating permissions are released, and the system switches to fully automatic operation.

[0014] The reflux control module of this invention is used to control the water concentration. Water concentration affects the reaction rate, catalyst consumption, etc., and the target water concentration in the reactor should be controlled within a reasonable range. The water concentration inside the reactor cannot be directly measured; however, the actual water concentration can be estimated by inferring it from the reactor temperature.

[0015] Preferably, in step S1, if no liquid raw material feed flow is detected within a short period of time, an alarm is issued to remind the operator to handle the situation. If no liquid raw material feed flow is detected after a short delay, the reaction is stopped through the safety system, and the shutdown procedure is run. In step S2, if the air test is performed, after receiving the command to start the air feed, the air valve is opened, a short delay is set, and the air flow is monitored after the delay. If the preset value is reached, the next stage is entered; otherwise, a shutdown command is issued, and the shutdown procedure is run.

[0016] The total air volume in this invention determines the production rate of the device, reflecting the reactor load. The reactor has multiple air nozzles, each with an independent flow control loop. Operators or start-up controllers set the total air volume via a handheld device. The program then calculates the flow rate setpoints for each air nozzle and automatically adjusts the inlet valves to maintain symmetrical airflow around the reactor. Therefore, the reactor's airflow needs to be tested to ensure it meets reaction requirements. Only when the reaction requirements are met will the reactor accept liquid feedstock for reaction. The liquid feedstock, as the main reactant, is supplied from an external storage tank. Its temperature is raised from ambient temperature to a specific temperature via a heat exchanger before entering the reactor, where oxygen is added. The feedstock flow rate setpoint is calculated by the program based on the reaction principle. The flow valves are set to automatic, ensuring the actual feed flow rate equals the setpoint. If the actual feed flow rate differs from the setpoint, the reactor will not operate and will not accept liquid feedstock.

[0017] Preferably, the specific operation process of the parking procedure is as follows:

[0018] T1. When the shutdown condition is triggered, all pumps and motors stop, and the shut-off valves return to the fail-safe position.

[0019] T2. When the program receives a stop signal, it first stops the main program, and the corresponding control loop will remain in the current state;

[0020] T3. Then monitor the running status of the subroutine. If the subroutine is detected to be running, stop the subroutine immediately, and the corresponding climbing action will also stop.

[0021] T4. Once all procedures have stopped, each control loop will receive a corresponding signal from the system to return the device to its initial state.

[0022] During system startup, the safety system continuously monitors the status of the process and equipment. If any interlocking conditions are not met, a shutdown procedure will be triggered. Operators can also manually stop the system by pressing a button to ensure the safety of system operation.

[0023] Preferably, the reactor has multiple air nozzles, each with an independent flow control loop.

[0024] The purpose of this invention is to provide each air nozzle with an independent flow control loop so that the flow rate of air entering each reactor can be strictly controlled. This is because the reaction of chemical fiber raw materials is very dangerous, and even a slight error in the proportion may cause a safety accident. Therefore, the input of raw materials must be strictly controlled to prevent potential safety hazards.

[0025] Preferably, the liquid raw material is output from a storage tank outside the boundary area, and its temperature is raised from the ambient temperature to a specific temperature through a heat exchanger before entering the reactor and adding oxygen to carry out the reaction.

[0026] This invention replaces manual control by employing an automated control device for chemical fiber raw material reactions. Since the reaction of chemical fiber raw materials is extremely dangerous, the control must be precise, and each step must be strictly executed according to the preset data to ensure the safe conduct of the reaction.

[0027] Preferably, the reactor outlet is equipped with an oxygen concentration detection device, which automatically controls the oxygen flow rate by detecting the oxygen content at the outlet, ensuring that the oxidation reaction proceeds fully.

[0028] The oxygen content at the reactor outlet is crucial in this invention; its concentration must be maintained within a safe range to ensure sufficient oxygen is present in the reactor to provide favorable oxidation conditions. By monitoring the outlet oxygen content, the oxygen flow rate is automatically controlled to ensure the oxidation reaction proceeds fully.

[0029] A sequential control system for one-button start-up of a chemical fiber raw material plant includes a reactor connected to a high-pressure absorber, a stirrer, and a distillation column. The high-pressure absorber is connected to a liquid level control module. The distillation column includes a first distillation column and a second distillation column. The first distillation column is positioned above the reactor, and the second distillation column is positioned above the first distillation column. The first distillation column, the second distillation column, and the reactor are all connected to a reflux control module.

[0030] This invention involves introducing liquid raw materials and air into a reactor for reaction. A stirrer agitates the materials within the reactor to ensure thorough reaction and crystallization of the reaction mixture into a slurry. A high-pressure absorber increases the reactor pressure, raising the reactor temperature and accelerating the reaction rate. Simultaneously, the reactor temperature is controlled to maintain a reasonable level, preventing overload due to excessively low temperatures. A liquid level control module regulates the liquid level within the reactor, controlling the reaction state, solvent flow, and mother liquor flow to maintain a constant consistency of the slurry leaving the reactor, achieving the target net solvent ratio. A reflux control module controls the water concentration within the reactor; the target water concentration should be maintained within a reasonable range, as water concentration affects the reaction rate and catalyst consumption. Maintaining a reasonable water concentration allows for a faster reaction rate.

[0031] Preferably, the reactor is equipped with valves around its perimeter, through which air and liquid raw materials enter the reactor. An oxygen concentration detection device is installed at the reactor outlet to detect the oxygen concentration of the product after the reaction. The reactor is also connected to a safety system that protects the safe operation of the entire control system and is equipped with a shutdown procedure.

[0032] This invention's safety system controls various devices and modules in the reaction process. If the air flow and liquid feed flow deviate from preset values, the control valves close, the shutdown procedure is executed to stop the entire system, and an alarm signal is issued along with the cause of the problem. The operator then performs maintenance based on the feedback report. The start-up procedure runs 30 seconds after the operator clicks the start button. This 30-second delay is part of the safety system interlock, allowing time for the reactor analyzer sample routing valves to change, confirming the sample gas flow to the analyzer. If the valves do not activate, and the sampling route and flow are not established, the safety system terminates the start-up and executes the shutdown procedure. This action is achieved through a branch structure. When the start-up procedure begins, the first action is to set various controllers and valves to their initial states, including initiating the liquid feed for a "test reaction" phase. If no feed flow is detected within a short time, an alarm is issued to alert the operator. If no feed flow is detected after a short delay, the reaction start-up is stopped through the emergency shutdown system, and the shutdown procedure is executed. This action is also achieved through a branch structure. After the liquid feed passes the "test," the "air test" begins. Upon receiving the instruction to start air feeding, the air valve is opened, a short delay is set, and the airflow is monitored after the delay. If the preset value is reached, the process proceeds to the next stage; otherwise, the shutdown procedure is initiated. If the "test response" stage is entered, a 5-minute timer will begin. In the last minute of the test stage, the "Accept" button is available for the operator to click, allowing them to decide whether to continue operation; otherwise, the shutdown procedure will be executed. The safety system monitors each stage in real time to prevent problems. If a problem occurs, the start-up procedure is immediately interrupted, and the cause and location of the problem are sent to the operator for timely repair.

[0033] The beneficial effects of this invention are as follows: 1. By combining SFC with ST language, this invention greatly reduces the use and connection of function blocks, making the program simple and readable, improving sequential control performance while reducing the load on the control system; 2. Using the SFC sequential control diagram structure, this invention can clearly decompose the program, and the mutual calling between various programs is simple and convenient, greatly reducing the difficulty and workload of program writing, and allowing for flexible responses to program modifications caused by process changes in the later stages; 3. The SFC of this invention comes with a monitoring panel, allowing operators to clearly monitor the program status down to each step and each action; 4. Using the solution of this invention, the program portability is greatly improved; 5. Through the successful application of the solution of this invention in a large-scale integrated chemical fiber raw material plant, the new technology has achieved performance and experience in large-scale plants, gaining recognition from all parties; 6. This invention improves the safety of the plant start-up process and shortens the start-up cycle through one-button start-up. Attached Figure Description

[0034] Figure 1 This is a flowchart of the present invention;

[0035] Figure 2 This is a flowchart of the parking exploration procedure of the present invention;

[0036] Figure 3 This is a system block diagram of the sequential control system for one-button start-up of the fiber raw material device in Embodiment 2 of the present invention; Detailed Implementation

[0037] The specific implementation of the technical solution of the present invention will be further described below through examples and in conjunction with the accompanying drawings.

[0038] Example 1:

[0039] Please see Figure 1 This invention provides a sequential control method for one-button start-up of a chemical fiber raw material device, comprising the following steps:

[0040] Step 1: The operator presets and checks the parameters required for system operation. Before starting the start-up sequence, the operator needs to preset and check the parameters required for program operation to determine the start-up rate and target, etc. When the unit is ready to start, the operator uses the start button on the DCS operation screen to run the start-up program. The "Start-up Response" button is only allowed to be operated by the operator when all interlock signals are normal. Then, the start-up program is run. Once the start-up program is started, the operation mode of the relevant valves, motors, and other operation panels is switched to automatic, and manual control is not allowed to prevent human error. Operation permissions will be gradually released to the operator according to the start-up stage.

[0041] The start-up procedure runs 30 seconds after the operator clicks the start button. This 30-second delay is part of the safety system interlock, allowing time for the reactor analyzer sample routing valves to change and confirm sample gas flow to the analyzer. If the valves do not actuate, and a sampling route and flow are not established, the safety system terminates the start-up and runs the shutdown procedure, which is implemented through a branching structure.

[0042] When the start-up procedure begins, the first action is to set all controllers and valves to their initial states, including initiating the liquid feed for a "test reaction" phase. If no feed flow is detected within a short period, an alarm is triggered to alert the operator. If no feed flow is detected after a short delay, the reaction start-up is aborted via the emergency stop system, and the shutdown procedure is executed. This action is achieved through a branching structure.

[0043] Step Two: After the liquid feed passes the "test", the "air test" begins. Upon receiving the command to start air feed, the air valve is opened, a small setting is set, and the air flow is monitored after a delay. If the preset value is reached, the process proceeds to the next stage; otherwise, the shutdown procedure is initiated.

[0044] If the "Test Response" phase is entered, a 5-minute timer will start. In the last minute of the test phase, the "Accept" button can be clicked by the operator, who can then decide whether to continue driving or execute the stop procedure.

[0045] Step 3: After the operator issues an "accept" command and the program receives "accept" confirmation from the system, the device will begin automatic and stable feeding. First, the mother liquor feed is started at a preset rate. Then, through liquid feed flow control, the liquid feed flow is increased from the "test phase" flow rate.

[0046] After the liquid feed begins, the safety system monitors its real-time values ​​to determine if air feeding is permitted. Once a specific set value is reached, there is a 30-second delay before the air feed rate begins to ramp up from the "test phase" level. The 30-second delay is to allow the liquid feed to enter the reactor before the air. After normal feeding begins, the system automatically controls the pressure inside the reactor.

[0047] Step 4: Monitor the pressure inside the reactor and start the agitator, distillation column, and high-pressure absorption column in sequence according to the different stages of reactor load;

[0048] Step 5: Once the load reaches the preset value, the distillation column no longer self-circulates and directly returns to the reactor, controlling the reactor temperature and water content. The entire system operates fully automatically.

[0049] The starting process of this invention can be monitored via a screen, which includes device status, device parameters, running time, operation buttons, temperature rise curve, and the interlock status of the safety system. Operators can intuitively and accurately monitor the entire automatic starting process through the screen. During program operation, the status of the sequential control program and the specific actions executed by the program can be monitored via the screen.

[0050] This invention utilizes the built-in timer in each step of the SFC to meet numerous timing requirements and delay condition judgments in the program.

[0051] The program is designed with a main program and subroutines. Subroutines are designed for specific devices and sub-units, while the main program is designed for the entire device. The main program and subroutines are linked through nested calls.

[0052] This invention uses a specially developed ramping module, which can smoothly increase the device load to the target value according to a preset rate and a one-click start-up program.

[0053] During the operation of this invention program, any abnormalities in the process or equipment are continuously monitored, and corresponding actions are executed according to the fault level, such as alarms and interlocks.

[0054] This invention includes an alarm information display window in the program monitoring screen. During operation, if any alarm or shutdown interlock is triggered, the corresponding information will be displayed in the window.

[0055] During the one-button start-up process, the present invention monitors the status of the device in real time. If any interlocking condition occurs, the program will be triggered to stop. The stopping program will safely stop the device according to the start-up stage.

[0056] Regardless of whether the start-up is successful, this invention will generate a start-up report, recording information such as start-up time / trip time, valve stroke time, and key process parameters, providing it to the process for start-up analysis.

[0057] To achieve one-click start-up of the oxidation unit of the chemical fiber raw material plant, this invention requires controlling various parameters of the oxidation reactor and related equipment, and increasing the reactor feed rate to a specific load through a pre-written sequential control program. To ensure the safety of the entire process, close and timely interaction between the safety system's ESD logic and the DCS control system is required to monitor the progress of critical startup stages. DCS, short for Distributed Control System, is a new generation of instrument control system based on microprocessors. It employs a design principle that distributes control functions while centralizing display and operation, balancing autonomy and comprehensive coordination. By detecting the flow rates of raw materials and reactants before the reaction, the safety system monitors each stage of system operation in real time. If an error occurs in any stage or a problem arises with the raw materials, the reaction can be stopped immediately to prevent accidents. By monitoring the pressure inside the reactor, devices at each stage of the system are started sequentially according to different reactor load stages, replacing manual intervention. This method automates the operation of the chemical fiber raw material unit. All steps before the reactor load reaches a preset value can be manually interrupted to prevent operational errors. After the reactor load reaches the preset value, the reaction stabilizes, and the system automatically adjusts the temperature and water content inside the reactor based on the reaction conditions. The entire system then begins automatic and stable operation. Operators can also adjust the load by adjusting the air feed.

[0058] In step four, the reactor load is increased. When the reactor load reaches 10%, the agitator is started to ensure that the reaction mixture crystallizes into a slurry. When the air load reaches a specific set value, the device has a certain atmospheric pressure. The high-pressure absorber is started to increase the reactor pressure and raise the reactor temperature. Since the high-pressure absorber is shared by the reactors, the status of other reactors needs to be checked before starting. When the reactor load reaches 15%, the liquid level in the reactor container increases further. The liquid level control module of the high-pressure absorber is started to control the liquid level in the high-pressure absorber. When the reactor load reaches 25%, the reflux control module is started to control the liquid level in the high-pressure absorber and recover the solvent at the same time.

[0059] The reactor agitator of this invention is crucial for the safe and efficient production of products in each reactor. Its function is to ensure that the reaction mixture crystallizes into a slurry and breaks up airflow into small bubbles, thereby increasing the rate at which oxygen dissolves into the solvent. The agitator speed needs to be automatically adjusted at each stage of the reaction. The high-pressure absorber can increase the reactor pressure, which can raise the reactor temperature. Even small changes in reactor temperature can have a significant impact on the reaction rate. To avoid an excessively fast reaction rate, the reactor pressure cannot be too low; however, low-pressure operation will increase the load on the condenser at the top of the reactor. Therefore, the pressure must be controlled within a reasonable range.

[0060] In step five, the preset value is 30%. When the reactor load reaches 30%, the first distillation column connected to the reactor stops self-circulation. The reflux control module controls the reflux of the first distillation column and the reactor, and starts the second distillation column connected to the first distillation column. The reflux control module controls the second distillation column to reflux. At this point, the start-up is completed, all operating permissions are released, and the system switches to fully automatic operation.

[0061] The reflux control module of this invention is used to control the water concentration. Water concentration affects the reaction rate, catalyst consumption, etc., and the target water concentration in the reactor should be controlled within a reasonable range. The water concentration inside the reactor cannot be directly measured; however, the actual water concentration can be estimated by inferring it from the reactor temperature.

[0062] In step S1, if no liquid feed flow is detected within a short period of time, an alarm is issued to remind the operator to handle the situation. If no liquid feed flow is detected after a short delay, the reaction is stopped through the safety system, and the shutdown procedure is run. In step S2, if the air test is performed, after receiving the command to start the air feed, the air valve is opened, a short delay is set, and the air flow is monitored after the delay. If the preset value is reached, the next stage is entered; otherwise, a shutdown command is issued, and the shutdown procedure is run.

[0063] The total air volume in this invention determines the production rate of the device, reflecting the reactor load. The reactor has multiple air nozzles, each with an independent flow control loop. Operators or start-up controllers set the total air volume via a handheld device. The program then calculates the flow rate setpoints for each air nozzle and automatically adjusts the inlet valves to maintain symmetrical airflow around the reactor. Therefore, the reactor's airflow needs to be tested to ensure it meets reaction requirements. Only when the reaction requirements are met will the reactor accept liquid feedstock for reaction. The liquid feedstock, as the main reactant, is supplied from an external storage tank. Its temperature is raised from ambient temperature to a specific temperature via a heat exchanger before entering the reactor, where oxygen is added. The feedstock flow rate setpoint is calculated by the program based on the reaction principle. The flow valves are set to automatic, ensuring the actual feed flow rate equals the setpoint. If the actual feed flow rate differs from the setpoint, the reactor will not operate and will not accept liquid feedstock.

[0064] like Figure 2 As shown, the specific operation process of the parking procedure is as follows:

[0065] T1. When the shutdown condition is triggered, all pumps and motors stop, and the shut-off valve returns to the fail-safe position.

[0066] T2. When the program receives a stop signal, it first stops the main program, and the corresponding control loop will remain in the current state;

[0067] T3. Then monitor the running status of the subroutine. If it is running, stop the subroutine immediately, and the corresponding climbing action will also stop.

[0068] T4. Once all procedures have stopped, each control loop will receive a corresponding signal from the system to return the device to its initial state.

[0069] During system startup, the safety system continuously monitors the status of the process and equipment. If any interlocking conditions are not met, a shutdown procedure will be triggered. Operators can also manually stop the system by pressing a button to ensure the safety of system operation.

[0070] The reactor has multiple air nozzles, each with an independent flow control loop.

[0071] The purpose of this invention is to provide each air nozzle with an independent flow control loop so that the flow rate of air entering each reactor can be strictly controlled. This is because the reaction of chemical fiber raw materials is very dangerous, and even a slight error in the proportion may cause a safety accident. Therefore, the input of raw materials must be strictly controlled to prevent potential safety hazards.

[0072] Liquid raw materials are output from storage tanks outside the boundary area, and their temperature is raised from ambient temperature to a specific temperature through a heat exchanger. After entering the reactor, oxygen is added to carry out the reaction.

[0073] This invention replaces manual control by employing an automated control device for chemical fiber raw material reactions. Since the reaction of chemical fiber raw materials is extremely dangerous, the control must be precise, and each step must be strictly executed according to the preset data to ensure the safe conduct of the reaction.

[0074] An oxygen concentration detection device is installed at the reactor outlet. By detecting the oxygen content at the outlet, the oxygen flow rate is automatically controlled to ensure that the oxidation reaction proceeds fully.

[0075] The oxygen content at the reactor outlet is crucial in this invention; its concentration must be maintained within a safe range to ensure sufficient oxygen is present in the reactor to provide favorable oxidation conditions. By monitoring the outlet oxygen content, the oxygen flow rate is automatically controlled to ensure the oxidation reaction proceeds fully.

[0076] Example 2:

[0077] like Figure 3 As shown, Embodiment 2 of the present invention provides a sequential control system for one-button start-up of a chemical fiber raw material device, including a reactor. The reactor is connected to a high-pressure absorber, a stirrer, and a distillation column. The high-pressure absorber is connected to a liquid level control module. The distillation column includes a first distillation column and a second distillation column. The first distillation column is located above the reactor, and the second distillation column is located above the first distillation column. The first distillation column, the second distillation column, and the reactor are all connected to a reflux control module.

[0078] This invention involves introducing liquid raw materials and air into a reactor for reaction. A stirrer agitates the materials within the reactor to ensure thorough reaction and crystallization of the reaction mixture into a slurry. A high-pressure absorber increases the reactor pressure, raising the reactor temperature and accelerating the reaction rate. Simultaneously, the reactor temperature is controlled to maintain a reasonable level, preventing overload due to excessively low temperatures. A liquid level control module regulates the liquid level within the reactor, controlling the reaction state, solvent flow, and mother liquor flow to maintain a constant consistency of the slurry leaving the reactor, achieving the target net solvent ratio. A reflux control module controls the water concentration within the reactor; the target water concentration should be maintained within a reasonable range, as water concentration affects the reaction rate and catalyst consumption. Maintaining a reasonable water concentration allows for a faster reaction rate.

[0079] The reactor is equipped with valves around its perimeter, through which air and liquid raw materials enter the reactor. An oxygen concentration detection device is installed at the reactor outlet to detect the oxygen concentration of the product after the reaction. The reactor is also connected to a safety system that protects the safe operation of the entire control system. The safety system is equipped with a shutdown procedure.

[0080] This invention's safety system controls various devices and modules in the reaction process. If the air flow and liquid feed flow deviate from preset values, the control valves close, the shutdown procedure is executed to stop the entire system, and an alarm signal is issued along with the cause of the problem. The operator then performs maintenance based on the feedback report. The start-up procedure runs 30 seconds after the operator clicks the start button. This 30-second delay is part of the safety system interlock, allowing time for the reactor analyzer sample routing valves to change, confirming the sample gas flow to the analyzer. If the valves do not activate, and the sampling route and flow are not established, the safety system terminates the start-up and executes the shutdown procedure. This action is achieved through a branch structure. When the start-up procedure begins, the first action is to set various controllers and valves to their initial states, including initiating the liquid feed for a "test reaction" phase. If no feed flow is detected within a short time, an alarm is issued to alert the operator. If no feed flow is detected after a short delay, the reaction start-up is stopped through the emergency shutdown system, and the shutdown procedure is executed. This action is also achieved through a branch structure. After the liquid feed passes the "test," the "air test" begins. Upon receiving the instruction to start air feeding, the air valve is opened, a short delay is set, and the airflow is monitored after the delay. If the preset value is reached, the process proceeds to the next stage; otherwise, the shutdown procedure is initiated. If the "test response" stage is entered, a 5-minute timer will begin. In the last minute of the test stage, the "Accept" button is available for the operator to click, allowing them to decide whether to continue operation; otherwise, the shutdown procedure will be executed. The safety system monitors each stage in real time to prevent problems. If a problem occurs, the start-up procedure is immediately interrupted, and the cause and location of the problem are sent to the operator for timely repair.

[0081] This invention, through the combination of SFC and ST language, significantly reduces the use and connection of function blocks, making the program simple and readable, improving sequential control performance while reducing the load on the control system. The SFC sequential control diagram structure allows for clear program decomposition, facilitating easy and convenient inter-program calls, greatly reducing programming difficulty and workload, and enabling flexible adaptation to program changes caused by process variations. The SFC of this invention includes a built-in monitoring panel, allowing operators to clearly monitor the program status down to each step and action. Using this invention, program portability is greatly improved. The successful application of this invention in a large-scale integrated chemical fiber raw material plant has provided the new technology with achievements and experience in large-scale installations, gaining recognition from all parties. 6. This invention improves the safety of the plant start-up process and shortens the start-up cycle through one-button start-up.

[0082] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. 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 all fall within the protection scope of the present invention.

Claims

1. A sequential control method for one-button start-up of a chemical fiber raw material device, characterized in that, Includes the following steps: S1. The operator presets and checks the parameters required for system operation, then runs the start-up procedure, detects the flow rate of raw material feed, and gradually releases operating permissions to the operator according to the start-up stage; S2. After the flow rate detection is passed, an air test is performed to monitor the air flow rate and ensure it reaches the preset value; S3. After the air flow rate reaches the preset value, the liquid raw material is fed in, and the flow rate of the liquid raw material begins to increase. 30 seconds after the liquid raw material reaches the preset value, the air is fed in, and the air flow rate begins to increase. S4. Monitor the pressure inside the reactor and start the agitator, distillation column and high-pressure absorption column in sequence according to the different stages of reactor load; S5. Once the load reaches the preset value, the distillation column no longer self-circulates and directly returns to the reactor to control the reactor temperature and water content. The entire system operates automatically.

2. The sequential control method for one-button start-up of a chemical fiber raw material device according to claim 1, characterized in that, In step S4, the reactor load is increased. When the reactor load reaches 10%, the stirrer is started to ensure that the reaction mixture crystallizes into a slurry. When the air load reaches a specific set value, the device has a certain atmospheric pressure. The high-pressure absorber is started to increase the reactor pressure and raise the reactor temperature. When the reactor load reaches 15%, the liquid level in the reactor container increases further. The liquid level control module of the high-pressure absorber is started to control the liquid level in the high-pressure absorber. When the reactor load reaches 25%, the reflux control module is started to control the liquid level in the high-pressure absorber and recover the solvent at the same time.

3. The sequential control method for one-button start-up of a chemical fiber raw material device according to claim 1, characterized in that, In step S5, the preset value is 30%. When the reactor load reaches 30%, the first distillation column connected to the reactor stops self-circulation. The reflux control module controls the reflux of the first distillation column and the reactor, and starts the second distillation column connected to the first distillation column. The reflux control module controls the second distillation column to reflux. At this point, the start-up is completed, all operating permissions are released, and the system switches to fully automatic operation.

4. The sequential control method for one-button start-up of a chemical fiber raw material device according to claim 1, characterized in that, In step S1, if no liquid raw material feed flow is detected within a short period of time, an alarm is issued to remind the operator to handle the situation. If no liquid raw material feed flow is detected after a short delay, the reaction is stopped through the safety system, and the shutdown procedure is run. In step S2, if the air test is performed, after receiving the command to start air feeding, the air valve is opened, a short delay is set, and the air flow is monitored after the delay. If the preset value is reached, the next stage is entered; otherwise, a shutdown command is issued, and the shutdown procedure is run.

5. The sequential control method for one-button start-up of a chemical fiber raw material device according to claim 4, characterized in that, The specific operation process of the parking procedure is as follows: T1. When the shutdown condition is triggered, all pumps and motors stop, and the shut-off valves return to the fail-safe position. T2. When the program receives a stop signal, it first stops the main program, and the corresponding control loop will remain in the current state; T3. Then monitor the running status of the subroutine. If the subroutine is detected to be running, stop the subroutine immediately, and the corresponding climbing action will also stop. T4. Once all procedures have stopped, each control loop will receive a corresponding signal from the system to return the device to its initial state.

6. A sequential control method for one-button start-up of a chemical fiber raw material device according to claim 1, 2, or 3, characterized in that, The reactor has multiple air nozzles, each with an independent flow control loop.

7. A sequential control method for one-button start-up of a chemical fiber raw material device according to claim 1 or 4, characterized in that, The liquid raw material is output from a storage tank outside the boundary area, and its temperature is raised from the ambient temperature to a specific temperature through a heat exchanger. After entering the reactor, oxygen is added to carry out the reaction.

8. The sequential control method for one-button start-up of a chemical fiber raw material device according to claim 6, characterized in that, The reactor outlet is equipped with an oxygen concentration detection device. By detecting the oxygen content at the outlet, the oxygen flow rate is automatically controlled to ensure that the oxidation reaction proceeds fully.

9. A sequential control system for one-button start-up of a chemical fiber raw material device, applicable to the sequential control method for one-button start-up of a chemical fiber raw material device according to any one of claims 1-8, characterized in that, The system includes a reactor connected to a high-pressure absorber, a stirrer, and a distillation column. The high-pressure absorber is connected to a level control module. The distillation column includes a first distillation column and a second distillation column. The first distillation column is positioned above the reactor, and the second distillation column is positioned above the first distillation column. The first distillation column, the second distillation column, and the reactor are all connected to a reflux control module.

10. The sequential control system for one-button start-up of a chemical fiber raw material device according to claim 9, characterized in that, The reactor is equipped with valves around its perimeter, through which air and liquid raw materials enter the reactor. An oxygen concentration detection device is installed at the reactor outlet to detect the oxygen concentration of the product after the reaction. The reactor is also connected to a safety system that protects the safe operation of the entire control system. The safety system is equipped with a shutdown procedure.

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