A continuous control system for intermittent polypropylene units

Abstract

The present invention relates to the technical field of intermittent liquid-phase bulk polymerization processes, and in particular to a continuous control system for an intermittent polypropylene device. The system comprises a signal control module, a CPU module and a signal processing unit installed in an SDT-4000 system, a numerical control instrument and a process operation module connected to process equipment, and an acquisition control module connected to the process operation module and the numerical control instrument, respectively; the signal control module is connected to the CPU module, the CPU module is connected to the signal processing unit, and the signal processing unit is connected to the acquisition control module. The intermittent polypropylene device continuous control system proposed in the present invention realizes automated operation of the entire process of the process flow through the CPU unit, and by installing the CPU module and the signal processing unit in the SDT-4000 system, the various parts of the system are relatively independent, thereby ensuring the stability of the system. A set of control systems is provided for each polymerization kettle and a flash kettle, respectively, so that the two parts are independent of each other, and when one device fails, the operation of the other device is not affected.

Description

Technical Field

[0001] The invention relates to the technical field of intermittent liquid phase bulk polymerization technology, in particular to a continuous control system of an intermittent polypropylene device. Background Art

[0002] The batch liquid-phase bulk polymerization process is a unique polypropylene production technology independently developed in my country in the 1970s. Due to the limited development time of the technology, the original technology itself has many shortcomings, such as high operator labor intensity, multiple human factors, unstable product quality, and non-standard production operations. During the operation process, many steps require manual operation, which is prone to errors and accidents. In particular, the manual addition process can cause flammable gas emissions and even activator to penetrate the venting system, causing smoke and fire accidents. This requires high operator quality and sense of responsibility, and is highly dangerous. With technological advancement, the existing technology can implement segmented automatic control of operations such as hydrogenation, feeding, three-dose, heating and temperature rise, cold water pressure increase, constant temperature and pressure, and high-pressure recovery in production. However, each step requires manual operation and is complex, and the process remains cumbersome. At the same time, existing operating systems perform and control each step within the same CPU. When the CPU fails, it can easily lead to serious system failures, posing a safety hazard. Summary of the Invention

[0003] (1) Technical issues to be resolved

[0004] In view of the shortcomings of the existing technology, the present invention provides a continuous control system for an intermittent polypropylene device, which solves the problems of discontinuous automatic control, high dependence on personnel, and high system safety risks.

[0005] (2) Technical solution

[0006] To solve the above problems, the present invention provides a batch polypropylene device continuity control system, comprising: a signal control module, a control mechanism and process equipment, each process equipment is provided with a separate set of control mechanisms, a process equipment and a set of control mechanisms are combined into a control group, and the control system includes a plurality of control groups;

[0007] The control mechanism includes: a CPU module, a signal processing unit, an acquisition control module and a process operation module; a control signal is input through the signal control module and sent to the CPU module of the corresponding control group, the CPU module performs calculations based on the received control signal and sends the result to the signal processing unit, the signal processing unit sends the received signal to the acquisition control module, the acquisition control module transmits the signal to the process operation module, the process operation module is installed on the process equipment and is divided into several process units according to different process operations, and the process equipment is adjusted according to the received signal; the CPU module and the signal processing unit are installed in the SDT-4000 system controller; a number of numerical control instruments are provided on the process equipment, and the numerical control instruments are connected to the acquisition control module to transmit the state parameters in the process equipment to the acquisition control module.

[0008] Preferably, the signal control module is controlled simultaneously by two control networks A and B, and the two networks A and B are independent of each other.

[0009] Preferably, the process equipment is a polymerization kettle or a flash kettle.

[0010] Preferably, the outlet of the polymerization kettle is connected to the flash kettle via a feed pipeline, and the feed pipeline is provided with an electric discharge door and an electric feed door in sequence.

[0011] Preferably, the loading electric door and the unloading electric door are respectively controlled by two independent AND logics, and the two signal sources of each AND logic are respectively from the collection control module corresponding to the flash kettle and the collection control module corresponding to the polymerization kettle.

[0012] Preferably, the process units in the process operation module are independent of each other.

[0013] Preferably, the CPU module includes a plurality of independent CPU units, and each process unit in the process operation module corresponds to an independent CPU unit in the CPU module.

[0014] Preferably, the numerical control instrument continuously monitors the production parameters in the process equipment in real time and transmits the transmitted signals to the CPU module.

[0015] (3) Beneficial effects

[0016] The intermittent polypropylene device continuity control system provided by the present invention is provided with a process operation module installed on the process equipment and a corresponding CPU unit for each process unit, so as to realize the automatic operation of the whole process of the process flow, improve the automation level of the system, reduce the dependence of the system operation on the quality of personnel, and reduce the accident rate. At the same time, the various parts are independent of each other, and the failure of one unit will not affect the normal operation and adjustment of other parts. By installing the CPU module and the signal processing unit in the SDT-4000 system, the various parts in the system are relatively independently controlled, and sufficient system redundancy is provided to ensure the stability of the system. By providing a set of control systems for the polymerization kettle and the flash kettle respectively, the two parts are independent of each other, and when one device fails, the operation of the other device is not affected, thereby improving the stability of the device and reducing the failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural diagram of the continuity control system of the intermittent polypropylene device of the present invention;

[0018] Figure 2 The figure is a flow chart of the continuity control system of the intermittent polypropylene device of the present invention.

[0019] Among them, 1. Signal control module; 2. CPU module; 3. Signal processing unit; 4. Acquisition control module; 5. Polymerization kettle; 6. Flash kettle; 7. Unloading door; 8. Loading door. Implementation Method

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by “upper”, “lower”, “inside”, “outside”, “top”, “bottom”, etc. are all based on the orientations or positional relationships shown in the accompanying drawings. The purpose is only to facilitate the description of the present invention and simplify the description. It does not indicate or imply that the referred parts must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. Example 1:

[0022] like Figure 1-2 As shown, the present invention provides a continuous control system for an intermittent polypropylene device, specifically comprising: a signal control module 1, a control mechanism and process equipment, each process equipment and a set of control mechanisms cooperate to form a control group, and each system of the present invention includes several control groups;

[0023] The control system includes: a CPU module 2, a signal processing unit 3, an acquisition control module 4 and a process operation module;

[0024] During the working process, the operation of the device is controlled by inputting preset working parameters and start and stop signals into the signal control module 1. The signal control module 1 is connected to several control mechanisms at the same time and is connected to the CPU module 2 in each control mechanism. The signal control module 1 transmits the input preset working parameters and start and stop signals to the CPU module 2 for processing; the CPU module 2 is connected to the signal processing unit 3, and the results processed by the CPU module 2 are sent to the signal processing unit 3, and the signal processing unit 3 integrates the data and transmits it to the next module; the signal processing unit 3 is connected to the acquisition control module 4, and the signal processing unit 3 transmits the received calculation result signal to the corresponding part of the acquisition control module 4; the acquisition control module 4 is connected to the process operation module, and the process operation module is installed on the process equipment. After the acquisition control module 4 transmits the signal to the process operation module, the process operation module adjusts the process according to the received signal.

[0025] The signal control module 1 is connected to each control group via two control networks, A and B. These two control networks simultaneously control the system. If one network fails, the other network can continue to operate normally, ensuring normal system operation and improving system stability. In this embodiment, the signal control module's two control networks, A and B, are formed by parallel switches A and B. Several parallel operating stations are used to input control signals, and each operating station is simultaneously connected to switches A and B.

[0026] Furthermore, the A control network and the B control network are connected to the CPU module 2 in the control group, and the signal input by the signal control module 1 is input into the CPU module 2 through the A and B operation networks. The CPU module 2 processes the signals input by the two control networks and then performs calculations to prevent the signals of the two control networks from acting at the same time, resulting in repeated operations, thereby improving the accuracy of the system.

[0027] The CPU module 2 and the signal processing unit 3 are installed in a controller based on the SDT-4000 system. According to the characteristics of the SDT-4000 system, 1:1 redundancy can be provided for the CPU module 2. When the CPU fails during operation, the redundant CPU can be switched to for calculation and control, which does not affect the normal operation of the device. At the same time, the system has sufficient time to wait for the staff to repair and restore the faulty CPU, thereby reducing the system failure rate, improving the system maintenance efficiency and work efficiency, and improving the stability of the system.

[0028] The CPU module 2 includes several CPU units, each of which independently handles the calculations and data processing corresponding to different process operations, and then uniformly transmits the calculated data to the signal processing unit 3. The relatively independent information processing of each process can reduce the CPU load, reduce the occurrence of CPU overload accidents, and improve the stability of the device. At the same time, when a CPU unit fails, the CPU units corresponding to the remaining processes can still operate normally and make timely adaptive adjustments to the impact of the failure, ensuring the stability and safety of the environment within the process equipment and improving the safety of the system.

[0029] In the present invention, the signal processing unit 3 is connected to the CPU module and the acquisition control module 4. After the calculation is completed, each unit in the CPU module 2 sends the calculation results and signals to the signal processing unit 3. The signal processing unit 3 integrates all received signals and then sends the integrated signal to the acquisition control module 4. The acquisition control module 4 is connected to the process operation module, which is installed on the process equipment and adjusts the process equipment according to the received signals so that the production parameters during production reach the set values ​​of the signal control module 1.

[0030] Among them, the process control module includes a hydrogenation unit, a feeding unit, a three-dose feeding unit, a hot water control unit, a cold water control unit and a reaction automatic control unit. The units are independent of each other. When one of the units fails, the other units can still work freely, and targeted accident handling and adjustments can be made to the process equipment under failure, providing protection for the production safety of the system.

[0031] Furthermore, each unit in the process control module is responsible for adjusting the corresponding process. Each process unit in the process control module in the CPU module 2 has a corresponding CPU unit, so that each process can be independently operated and controlled, and will not affect each other when a fault occurs, thereby improving the stability of the system.

[0032] The process equipment is provided with a number of numerical control instruments, which are connected to the acquisition control module 4. During the operation of the device, the numerical control instruments continuously collect and transmit various real-time data of the device to the acquisition control module 4, and then the acquisition control module 4 continues to pass the collected real-time data upward to the signal processing unit 3 and the CPU module 2 in sequence. After the CPU module 2 performs simple processing on the data, the data is transmitted to the signal control module 1 for display to the operator. At the same time, during the production process, if the target process parameters have been set and the data transmitted back does not match the set values, the CPU module 2 will calculate the process and adjustment that need to be adjusted based on the difference between the two, and then transmit the adjustment signal downward again.

[0033] The data transmitted by the digital control instrument include kettle temperature, kettle pressure, kettle current, cold water flow, hot water flow and additive flow, etc.

[0034] In the present invention, the process equipment includes a polymerization kettle 5 and a flash kettle 6. The polymerization kettle 5 and the flash kettle 6 are independent of each other and each equipped with a control system. The product of the polymerization kettle 5 serves as the raw material for the production of the flash kettle 6. The two are independent of each other. In traditional batch propylene plants, both are controlled by a centralized CPU unit. If a CPU unit fails, all polymerization kettles 5 or flash kettles 6 must be treated simultaneously, which can have serious consequences if not handled in a timely manner. The connection control method of the present invention ensures that when the CPU unit fails during operation, it will only affect the corresponding polymerization kettle 5 or flash kettle 6. Workers only need to repair and treat the affected equipment, reducing staff workload and minimizing safety hazards.

[0035] Each polymerization kettle 5 corresponds to a flash kettle 6, and the two are connected by a feed pipe. During normal operation, the reaction product in the polymerization kettle 5 enters the flash kettle 6 through the feed pipe and is used as a production raw material for further processing.

[0036] It should be noted that the feeding pipeline is provided with a feeding electric door 8 and a discharging electric door 7, which are respectively controlled by an independent AND logic. The two signal sources of each AND logic come from the collection control module 4 corresponding to the flash kettle 6 and the collection control module 4 corresponding to the polymerization kettle 5. When one of the process equipment fails, its corresponding collection control module 4 sends a closing signal to the feeding electric door (8) and the discharging electric door (7) are closed at the same time, isolating the two, ensuring that the raw materials in the process equipment in normal operation are not contaminated, and improving the working efficiency and safety of the system.

[0037] In the present invention, the process equipment and the control system are combined into a control group. The intermittent polypropylene device continuity control system of the present invention is composed of several control groups. Example 2:

[0038] Taking the device startup process as an example, the working principle of the continuity control system of the intermittent polypropylene device of the present invention is explained.

[0039] First, set the initial parameters and send a start signal. Predetermined process parameters are input to the system through the workstation, and a start signal is sent. Each unit in the CPU module issues a control signal according to the pre-set program. The signal is transmitted step by step downward to the process operation module, and the device begins to start. Simultaneously, the CNC instrument transmits the detected data step by step upward to the CPU module as adjustment feedback, and also sends a signal to the signal control module.

[0040] Among them, the initial parameters that need to be set include: the hot and cold water switching pressure setting value when the polymerization kettle is heated, the constant temperature setting value, the recovery endpoint pressure setting value after the reaction is completed, the return water switching temperature of the polymerization kettle jacket outlet, the stirring current setting value at the polymerization reaction endpoint, the automatic hydrogenation amount setting value, the propylene feed bottom material addition amount setting value (first stage setting value), the propylene feed amount setting value when the activator is added (second stage setting value), the propylene feed amount setting value when the third component is added (third stage setting value) and the total propylene amount setting value.

[0041] Then, the hydrogenation start signal is sent through the signal control module. Before the hydrogenation start signal is issued, it is necessary to first determine whether the "hydrogenation set value" is correct, and then determine whether the pressure of the polymerization kettle allows hydrogenation operation, whether the hydrogen pressure is greater than 1.2MPa, and whether the valve of the hydrogenation system is in the automatic position; after everything is normal, the hydrogenation signal is calculated by the CPU module and transmitted step by step to the process control module, which controls the opening of the hydrogenation valve on the polymerization kettle, the opening of the hydrogenation system outlet switch valve, and the start of adjustment of the hydrogenation system outlet regulating valve in turn. During the control process, the flow rate is kept within the range of 2-6kg / h and the pressure is kept within the range of 1.2-2.0MPa. At this time, the "hydrogenation batch accumulation" begins to accumulate; when the feedback "hydrogenation batch accumulation" reaches the "hydrogenation set value", the CPU module determines that the hydrogenation is completed. Each CPU unit sends a control signal to the process control module step by step, closes the hydrogenation system switch valve, and then closes the hydrogen valve above the polymerization kettle to end the hydrogenation process.

[0042] Among them, the "hydrogenation" start button is interlocked with the closed status of the upper and lower spray valves of the polymerization kettle, the upper and lower valves of the catalyst feed pipeline, and the activator pipeline valve. If any valve is not closed in place, the "hydrogenation" button will be gray and cannot be clicked to start, that is, the hydrogenation start signal cannot be sent.

[0043] Secondly, the feed start signal is sent through the signal control module. Before sending the feed start signal, it is necessary to first determine whether the "hydrogenation set value" is correct, and then determine the propylene pump start status, The propylene feed valve and reflux valve are in automatic state, the valves of the polymerization kettle are all in closed and automatic state (because feeding is the starting signal of the polymerization kettle control), the propylene bottom material set value, the activator propylene cumulative amount set value, the third component propylene cumulative amount set value, and the total propylene set value are correct, the activator metering tube liquid level and the three-component metering tube liquid level are normal, whether the catalyst has been added to the hopper, and whether the three-dose control system are all in automatic state. After everything is normal, the feed signal is calculated by the CPU module and transmitted step by step to the process control module, which controls the opening of the activator valve above the polymerization kettle, the opening of the regulating valve of the feed system, and the closing of the reflux valve (if the propylene pressure is too high, it will automatically adjust to a certain opening). At this time, the "propylene batch accumulation" begins to accumulate. During the control process, the CNC instrument transmits the detected data to the CPU module step by step. Each unit in the CPU module calculates according to the feedback value and transmits the adjustment signal to the process control module step by step to keep the flow and pressure within the set value range. During the entire feeding process, the propylene pressure should be greater than 1.2MPa in winter and greater than 1.5MPa in summer; if the propylene pressure is too high (1.9MPa), the CPU module sends a control signal based on feedback to control the reflux valve to release the pressure.

[0044] The "feed" start button is interlocked with the closed status of the upper and lower spray valves of the polymerization kettle and the hydrogenation valve on the polymerization kettle. If any valve is not closed properly, the "feed" button will be gray and cannot be clicked to start, that is, the feed start signal cannot be sent.

[0045] Next, the signal control module sends a heating start signal. Before this is done, it must ensure that the hot water tank temperature has reached the required temperature (80°C or above in winter, 70°C or above in summer), that the hot water pump has started, that the return valve at the polymerization reactor jacket outlet is in the automatic state, that the hot water, cold water, and recovery control valves are in the automatic state, and that all other valves are closed. After the hot water control valve opens, the reactor jacket inlet temperature begins to rise. The CPU module continuously receives operating parameters transmitted by the CNC instrument. When the jacket outlet temperature reaches the "return water switchover setpoint" (generally set between 45-50°C), the CPU module issues a control signal to close the jacket outlet cold water valve and open the hot water valve. When the reactor pressure rises to the "cold / hot water switchover setpoint," the CPU module issues a control signal to close the hot water valve and open the hot water tank return valve (if no other reactors are heating up), ending the heating process. At this point, the CPU module sends another signal to open the jacket cold water control valve, signaling the polymerization reaction to enter the heating and constant temperature phase.

[0046] When the hot water regulating valve is closed and the cold water regulating valve is opened, the control system uses cold water to control the temperature rise rate. At this point, the CPU module calculates and determines the initial constant temperature process based on the feedback of factors such as the temperature rise rate, cold water flow rate, and reaction time. Based on the reaction parameters of the polymerization kettle, the CPU module automatically sends a signal to control the end of the initial constant temperature process and continue to heat up to the "constant temperature set point."

[0047] Among them, a secondary overpressure protection program is set in the SDT-4000 system where the CPU module and signal processing unit are located. If the polymerization kettle is overpressured, the CPU module will judge based on the feedback signal that the high-pressure recovery valve is in manual state. When the polymerization kettle pressure reaches the secondary alarm value, the CPU module will automatically send a control signal to control the high-pressure recovery valve to open and release pressure to protect production safety.

[0048] Finally, the recovery start operation is performed. When the production status meets the pre-set production state, the CPU module automatically controls the recovery valve to gradually open. When the parameter change received by feedback matches the set value, the recovery valve is controlled to stop and remain open until all liquid propylene has evaporated. At this point, the recovery valve continues to open to accelerate the recovery process. When the pressure of the polymerization kettle falls below the "recovery end pressure value," the recovery process ends, and the interlock protection for injection is released. The operator at the polymerization station can directly authorize the operator at the flash steam station and supply power to the injection operation, allowing the flash steam operator to proceed with the injection operation. The polymerization kettle enters the "injection allowed" state, authorizing the flash steam injection operation and supplying power (operator operation required) to wait for injection. This completes the "one-button start" polymerization process.

[0049] During the recovery start-up operation, the operator can, based on his or her own experience, start the recovery process in advance by sending a recovery start signal through the "Recovery" start button when the constant temperature control program has not determined the conditions for ending the polymerization reaction.

[0050] The intermittent polypropylene unit continuity control system provided by the present invention can achieve full automation of the process flow, improve system stability, and reduce the system accident rate. The specific working process of the system is as follows:

[0051] Step 1: Input the starting process parameters and the starting signal through the signal control module 1, and the signal control module 1 transmits the process parameters, the signal and the starting signal to the CPU module 2;

[0052] Step 2: The CPU module 2 calculates the process unit that should be adjusted based on the received signal, and the CPU unit corresponding to the process unit performs the calculation and sends the calculation result to the signal processing unit 3;

[0053] Step 3: The signal processing unit 3 integrates the received signal and sends it to the acquisition control module 4, which then sends the signal to the corresponding units in the process operation module.

[0054] Step 4: Each unit of the process operation module operates the process equipment according to the received signal to make adjustments;

[0055] Step 5: The numerical control instrument in the process equipment feeds back the parameters in the equipment to the CPU module 2 in real time through the acquisition module and the signal processing unit 3;

[0056] Step 6. Repeat steps 2 to 5 until the feedback signal is the same as the input set value.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A batch polypropylene device continuity control system, characterized in that: include: A signal control module (1), a control mechanism and process equipment, wherein each process equipment is provided with a separate control mechanism, a process equipment and a control mechanism are combined into a control group, and the control system includes a plurality of control groups; The control mechanism comprises: a CPU module (2), a signal processing unit (3), an acquisition control module (4) and a process operation module; A control signal is input through the signal control module (1) and sent to the CPU module (2) of the corresponding control group. The CPU module (2) performs calculations based on the received control signal and sends the result to the signal processing unit (3). The signal processing unit (3) sends the received signal to the acquisition control module (4). The acquisition control module (4) transmits the signal to the process operation module. The process operation module is installed on the process equipment and is divided into a plurality of process units according to different process operations, and adjusts the process equipment according to the received signal. The CPU module (2) and the signal processing unit (3) are installed in the SDT-4000 system controller. The process equipment is provided with a plurality of numerical control instruments, which are connected to the acquisition control module (4) to transmit the state parameters in the process equipment to the acquisition control module (4).

2. A batch polypropylene device continuity control system according to claim 1, characterized in that: The signal control module (1) is controlled simultaneously by two control networks A and B, and the two networks A and B are independent of each other.

3. A batch polypropylene device continuity control system according to claim 1, characterized in that: The process equipment includes a polymerization kettle (5) and a flash kettle (6).

4. A batch polypropylene device continuity control system according to claim 3, characterized in that: The outlet of the polymerization kettle (5) is connected to the flash kettle (6) through a feeding pipeline, and a discharge electric door (7) and a feed electric door (8) are sequentially provided on the feeding pipeline.

5. A batch polypropylene device continuity control system according to claim 4, characterized in that: The loading electric door (8) and the unloading electric door (7) are respectively controlled by two independent AND logics, and the two signal sources of each AND logic are respectively from the acquisition control module (4) corresponding to the flash kettle (6) and the acquisition control module (4) corresponding to the polymerization kettle (5).

6. A batch polypropylene device continuity control system according to claim 1, characterized in that: The process units in the process operation module are independent of each other.

7. A batch polypropylene device continuity control system according to claim 6, characterized in that: The CPU module (2) includes a plurality of mutually independent CPU units, and each process unit in the process operation module corresponds to an independent CPU unit in the CPU module (2).

8. A batch polypropylene device continuity control system according to claim 1, characterized in that: The numerical control instrument continuously monitors the production parameters in the process equipment in real time and transmits the transmitted signals to the CPU module (2).

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