Pressure control method, device and equipment based on VAC device ethylene unloading working condition, medium and program product

Abstract

The invention relates to a pressure control method, device and equipment based on an ethylene unloading working condition of a VAC device, a medium and a program product. The method comprises the following steps: determining a current working condition according to process characteristics; automatically switching a pressure control target according to the working condition and the pressure parameter; according to different working conditions, the pressure control points of the storage tank are dynamically adjusted in stages; reading an actual measurement value of a pressure variable, setting algorithm detection interval time, and obtaining a pressure change rate through differential calculation; the pressure control point serves as a target value, the actual pressure measurement value serves as a feedback value, the deviation between the target value and the feedback value is calculated, the deviation is processed through a PID algorithm, and an opening instruction of the ethylene backflow flow valve is output. Therefore, the operation condition of the device can be automatically identified, and a corresponding control strategy is matched. Automatic control over the pressure of the ethylene buffer tank in the whole ethylene unloading process is achieved; ethylene backflow is used as a core pressure control means, and the adjusting amplitude of the pressure control valve of the ethylene buffer tank is reduced.

Description

Technical Field

[0001] This application relates to the field of automatic control technology, and in particular to a pressure control method, apparatus, computer equipment, computer-readable storage medium, and computer program product based on the ethylene unloading condition of a VAC device. Background Technology

[0002] During the ethylene unloading phase of a vinyl acetate (VAC) plant, the pressure control of existing ethylene buffer tanks generally relies on manual adjustment of the reflux valves in the ethylene storage tanks. This method suffers from poor operational consistency and untimely response. When the compressor is started at the initial stage of unloading or stopped at the end stage, the pressure change rate of the ethylene storage tank and the ethylene buffer tank fluctuates significantly, making it difficult to achieve precise control of the pressure change rate in the tank area through manual adjustment.

[0003] If the pressure in the ethylene buffer tank exceeds the safety threshold (too high or too low), the control system will trigger a cascading alarm mechanism. Under high pressure, this can easily lead to overpressure in the equipment, causing damage to the tank and pipelines; under low pressure, it may cause air backflow, forming an explosive mixture, posing a significant safety hazard. Simultaneously, if the pressure regulating reflux valve operates with excessive amplitude or rate, it will cause drastic fluctuations in the ethylene mass flow rate entering the synthesis unit reactor, severely reducing the stability of the unit's operation. Summary of the Invention

[0004] Therefore, it is necessary to provide a pressure control method, device, computer equipment, computer-readable storage medium, and computer program product based on the ethylene unloading operation of the VAC unit, which can perform real-time and efficient pressure regulation when pressure fluctuates during ethylene unloading, ensure the stability of pressure parameters and reflux valve regulation rate, and thus guarantee the stable operation of the ethylene tank area system pressure.

[0005] In a first aspect, this application provides a pressure control method based on the ethylene unloading condition of a VAC unit, the method comprising: Determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; Based on the operating conditions and pressure parameters, the pressure control target is automatically switched, including: ethylene storage tank pressure and / or ethylene buffer tank pressure. The pressure control points of the storage tank are dynamically adjusted in stages according to different operating conditions. Read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation; Using the pressure control point as the target value and the actual pressure measurement value as the feedback value, the deviation between the two is calculated, and the deviation is processed by the PID algorithm to output the opening command of the ethylene reflux flow valve.

[0006] In one embodiment, determining the current operating condition based on the process characteristics of the ethylene unloading compressor includes: By analyzing the process characteristics of the ethylene unloading compressor, the lubricating oil temperature, lubricating oil pressure, and exhaust gas temperature of the unloading compressor were selected as the discrimination parameters. If the temperature of the unloading compressor lubricating oil, the pressure of the lubricating oil, and the exhaust gas temperature are all greater than their respective preset judgment values, the compressor is determined to be in unloading condition. If any one of the unloading compressor's lubricating oil temperature, lubricating oil pressure, or exhaust gas temperature does not exceed its respective preset judgment value, the compressor is determined to be in a non-unloading operating condition.

[0007] In one embodiment, the automatic switching of the pressure control target based on operating conditions and pressure parameters includes: When the unit is not in unloading condition, the pressure of the ethylene buffer tank is used as the control target; When the unit is in the unloading condition and the pressure of the ethylene buffer tank exceeds the set control range, the pressure of the ethylene buffer tank will be used as the control target. When the unit is in unloading mode and simultaneously meets the conditions that the pressure change rate of the buffer tank is greater than the preset empirical multiple of the pressure change rate of the storage tank, and the pressure change rate of the buffer tank is greater than the set fixed empirical value, the pressure of the ethylene buffer tank is taken as the control target.

[0008] In one embodiment, the automatic switching of the pressure control target based on operating conditions and pressure parameters includes: When the unit is in the unloading condition, and simultaneously meets the following conditions: the buffer tank pressure is within the set control range, the buffer tank pressure change rate is less than the preset empirical multiple of the storage tank pressure change rate, and the buffer tank pressure change rate is less than the set fixed empirical value, the ethylene storage tank pressure is taken as the control target.

[0009] In one embodiment, the step of dynamically adjusting the tank pressure control point in stages for different operating conditions includes: For non-unloading conditions, the tank pressure control point is set to the same value as the setting on the operation screen; For transitional operating conditions, a proportional function between tank pressure and lubricating oil temperature is established, and the actual control point of tank pressure is output in real time according to the change of lubricating oil temperature. For unloading operations, the tank pressure control point is equal to the set value on the operation screen plus a specified value.

[0010] Secondly, this application also provides a pressure control device based on the ethylene unloading conditions of a VAC unit, the device comprising: The determination module is used to determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; The switching module is used to automatically switch the pressure control target according to the operating conditions and pressure parameters. The pressure control target includes: ethylene storage tank pressure and / or ethylene buffer tank pressure. The adjustment module is used to dynamically adjust the pressure control point of the storage tank in stages for different operating conditions; The calculation module is used to read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation. The processing module is used to calculate the deviation between the pressure control point as the target value and the actual measured pressure value as the feedback value, and then process the deviation through a PID algorithm to output the opening command of the ethylene reflux flow valve.

[0011] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps: Determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; Based on the operating conditions and pressure parameters, the pressure control target is automatically switched, including: ethylene storage tank pressure and / or ethylene buffer tank pressure. The pressure control points of the storage tank are dynamically adjusted in stages according to different operating conditions. Read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation; Using the pressure control point as the target value and the actual pressure measurement value as the feedback value, the deviation between the two is calculated, and the deviation is processed by the PID algorithm to output the opening command of the ethylene reflux flow valve.

[0012] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps: Determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; Based on the operating conditions and pressure parameters, the pressure control target is automatically switched, including: ethylene storage tank pressure and / or ethylene buffer tank pressure. The pressure control points of the storage tank are dynamically adjusted in stages according to different operating conditions. Read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation; Using the pressure control point as the target value and the actual pressure measurement value as the feedback value, the deviation between the two is calculated, and the deviation is processed by the PID algorithm to output the opening command of the ethylene reflux flow valve.

[0013] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps: Determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; Based on the operating conditions and pressure parameters, the pressure control target is automatically switched, including: ethylene storage tank pressure and / or ethylene buffer tank pressure. The pressure control points of the storage tank are dynamically adjusted in stages according to different operating conditions. Read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation; Using the pressure control point as the target value and the actual pressure measurement value as the feedback value, the deviation between the two is calculated, and the deviation is processed by the PID algorithm to output the opening command of the ethylene reflux flow valve.

[0014] The aforementioned pressure control method, apparatus, computer equipment, computer-readable storage medium, and computer program product based on the ethylene unloading operation of a VAC unit determine the current operating condition according to the process characteristics of the ethylene unloading compressor; automatically switch the pressure control target based on the operating condition and pressure parameters, wherein the pressure control target includes: ethylene storage tank pressure and / or ethylene buffer tank pressure; dynamically adjust the storage tank pressure control point in stages for different operating conditions; read the actual measured value of the pressure variable, set the algorithm detection interval time, and calculate the pressure change rate through differential calculation; use the pressure control point as the target value and the actual measured pressure value as the feedback value, calculate the deviation between the two, process the deviation through a PID algorithm, and output the opening command of the ethylene reflux flow valve. This allows for automatic identification of the unit's operating condition (unloading / non-unloading) and matching of the corresponding control strategy; achieving automated control of the ethylene buffer tank pressure throughout the ethylene unloading process; and using ethylene reflux as the core pressure control means to reduce the adjustment amplitude of the ethylene buffer tank pressure control valve and smooth the fluctuation of the synthesis reaction feed flow. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 Control diagram for the cascade temperature of the ethylene storage tank outlet pipe of the VAC unit; Figure 2 This is a schematic diagram of the process flow of the ethylene tank area of ​​a VAC unit in one embodiment; Figure 3 A flowchart of a pressure control method based on the ethylene unloading condition of a VAC unit, provided as an embodiment of this application; Figure 4 This is a flowchart illustrating the process of determining the unloading condition of the VAC unit in one embodiment; Figure 5 This is a schematic diagram of the VAC unit unloading pressure control point switching process in one embodiment; Figure 6 This is a schematic diagram of the output process of the VAC unit unloading pressure control point in one embodiment; Figure 7 This is a schematic diagram of the overall process for controlling the ethylene unloading pressure of a VAC unit in one embodiment. Figure 8 This is a graph showing the pressure variation trend under normal manual operation control. Figure 9 This is a graph showing the pressure change trend under the control of the method described in the embodiments of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] To facilitate understanding of the technical solutions in the various embodiments of this application, a brief explanation of the technical terms that may appear in the various embodiments of this application will be given first.

[0019] Vinyl acetate (VAC): a key monomer in polymerization reactions, widely used in the field of chemical synthesis.

[0020] Proportional-Integral-Derivative (PID) control is a method that calculates the deviation between the target setpoint and the actual measured value, and outputs a control signal to achieve precise control of the controlled object.

[0021] The relevant technologies for pressure control in ethylene tank farms within VAC units are mainly divided into two categories: the first is cascade control of the outlet pipe temperature, and the second is single-loop automatic control of the ethylene reflux flow rate. Among these, cascade control of the outlet pipe temperature is a commonly used solution in the industry. Its control logic is as follows: using the ethylene storage tank outlet pipe temperature as the main control loop and the ethylene reflux flow rate as the secondary control loop, the pressure of the ethylene buffer tank is controlled by indirectly regulating the outlet pipe temperature. Under non-unloading conditions, this solution can achieve stable pressure through real-time temperature adjustment and has the advantage of fast response speed.

[0022] However, under ethylene unloading conditions, the cascade control scheme for the outlet pipe temperature has significant limitations, specifically: 1) Temperature lag leads to control inaccuracy: The temperature signal of the liquid outlet pipe has a transmission lag characteristic. If the temperature adjustment rate is accelerated in order to pursue pressure stability, it is easy to cause large temperature fluctuations. If the adjustment rate is reduced, the temperature will continue to rise or fall, and the pressure control requirements cannot be met.

[0023] 2) Manual intervention is required when switching operating conditions: During the transition phase of starting or stopping the unloading compressor, the temperature parameters will change drastically. Operators need to manually adjust the temperature setpoint to avoid the reflux valve's action amplitude and rate exceeding the standard. This makes it impossible to achieve full-condition automated control and is difficult to match the dynamic control requirements of ethylene unloading conditions.

[0024] For example, Figure 1 This is a control diagram for the cascade temperature control of the ethylene storage tank outlet pipe of the VAC unit. In the diagram, TIC_72101 is the ethylene storage tank outlet pipe temperature controller, and FIC_72101 is the ethylene return flow controller.

[0025] To address the problems existing in related technologies, this application aims to provide a pressure control method based on the ethylene unloading operation of a VAC unit. By designing a condition judgment program, the method achieves automatic switching of the reflux valve control target. The method uses the pressure of the ethylene buffer tank and the ethylene storage tank during the ethylene unloading process as controlled variables, and the opening degree of the reflux valve at the outlet of the ethylene storage tank pump as the actuator. Simultaneously, the lubricating oil temperature and exhaust gas temperature of the unloading compressor are introduced as indicator variables for condition judgment, thus constructing a "one-to-two" controller with automatic control logic switching functionality.

[0026] It should be understood that the embodiments of this application are a method for automatically controlling the pressure of ethylene buffer tanks during the unloading stage of ethylene tank farms through multivariate intelligent control. The method in the embodiments of this application can solve the problem of automatic control of ethylene buffer tank pressure during the unloading process of ethylene tank farms in the process industry, and achieve the control purpose of balancing the pressure of ethylene buffer tanks and reducing the fluctuation of feed to downstream units.

[0027] For example, Figure 2 This is a schematic diagram of the process flow of the ethylene tank area of ​​a VAC unit in one embodiment, such as... Figure 2 As shown, 1-T-7201 is an ethylene storage tank; 2-PT_72104 is an ethylene storage tank pressure transmitter; 3-FIC_72101 is a pump outlet reflux controller; 4-TIC_72101 is an outlet pipe temperature controller; 5-T-7203 is an ethylene buffer tank; 6-PIC_72003 is an ethylene buffer tank pressure controller.

[0028] See Figure 2First, after being unloaded, the ethylene feedstock enters the T-7201 ethylene storage tank. The ethylene storage tank pump then transports the ethylene from the tank to the T-7203 ethylene buffer tank as feed for the VAC synthesis unit. A reflux pipeline is installed at the outlet of the ethylene storage tank pump, and the refluxed ethylene returns to the ethylene storage tank to balance the tank pressure. An automatic pressure control loop is installed at the outlet of the ethylene buffer tank, through which the material is transported to the VAC synthesis unit reactor.

[0029] For example, Figure 3 A flowchart of a pressure control method based on the ethylene unloading condition of a VAC unit, provided as an embodiment of this application, is shown below. Figure 3 As shown, the method in this embodiment may include the following steps: Step S301: Determine the current operating conditions based on the process characteristics of the ethylene unloading compressor.

[0030] In this embodiment, by analyzing the process characteristics of the ethylene unloading compressor, three key parameters are selected as the basis for judging the operating condition. For example, the unloading compressor lubricating oil temperature, lubricating oil pressure, and exhaust gas temperature are selected. When all three parameters are greater than the preset judgment value, the compressor is determined to be in normal start-up state, that is, the unit enters the unloading condition; otherwise, it is determined to be in a non-unloading condition.

[0031] For example, Figure 4 This is a flowchart illustrating the unloading condition determination process of the VAC unit in one embodiment. The compressor parameter tag number is read by running the ADVPLANT.FINDTAG function in the unloading condition determination program, and the condition status flag ST.VALUE is output through a conditional judgment statement, where 1 represents the unloading condition and 0 represents the non-unloading condition.

[0032] Step S302: Automatically switch the pressure control target according to the operating conditions and pressure parameters. The pressure control target includes: ethylene storage tank pressure and / or ethylene buffer tank pressure.

[0033] For example, using the pressure of the ethylene buffer tank as a control target requires that any of the following conditions be met: Situation 1: The equipment is in a non-unloading condition.

[0034] Situation 2: The unit is in unloading mode and the pressure of the ethylene buffer tank exceeds the set control range.

[0035] Situation 3: The device is in the unloading condition and simultaneously meets the conditions of "the pressure change rate of the buffer tank is greater than the preset experience multiple of the pressure change rate of the storage tank" and "the pressure change rate of the buffer tank is greater than the set fixed experience value".

[0036] For example, if the pressure of an ethylene storage tank is used as a control target, the following conditions must be met: The device is in unloading mode and simultaneously meets the following conditions: "the pressure of the buffer tank is within the set control range", "the pressure change rate of the buffer tank is less than the preset experience multiple of the pressure change rate of the storage tank", and "the pressure change rate of the buffer tank is less than the set fixed experience value".

[0037] For example, Figure 5 This is a schematic diagram of the VAC unit unloading pressure control point switching process in one embodiment, as shown below. Figure 5 As shown, the control point switching control program is first started, the unloading status tag number is read, and it is confirmed whether the unloading condition is met; then, the pressure control target is further determined, and finally the program judgment result is read, the status judgment tag number is written, and one output is completed.

[0038] Step S303: Adjust the tank pressure control point dynamically in stages according to different operating conditions.

[0039] In this embodiment, to address the issue of large pressure fluctuations in the storage tank during unloading, the pressure control point of the storage tank is dynamically adjusted in stages to avoid excessive output amplitude of the reflux valve leading to fluctuations in downstream feed.

[0040] For example, Figure 6 This is a schematic diagram of the unloading pressure control point output process of the VAC device in one embodiment. First, the compressor status is detected. For example: non-unloading condition (compressor stopped and fully cooled): the tank pressure control point is equal to the setting value on the operation screen; transition condition (compressor start-up preheating stage, stop cooling stage): a proportional function between tank pressure and lubricating oil temperature is established, and the actual tank pressure control point is output in real time according to the change of lubricating oil temperature; unloading condition (compressor running normally): the tank pressure control point is equal to the setting value on the operation screen plus 1.5 kPa.

[0041] In this embodiment, the tank pressure control point PT_72104_APC.VALUE is calculated and output based on the compressor lubricating oil temperature T1.VALUE and the operating status flag YXXC_ST.VALUE using the multi-condition judgment statement in the tank pressure control point calculation program.

[0042] Step S304: Read the actual measured value of the pressure variable, set the algorithm detection interval time, and calculate the pressure change rate through differential calculation.

[0043] In this embodiment, a common module for variable change rate algorithm is designed to realize real-time calculation of pressure change rate.

[0044] In step S305, the pressure control point is used as the target value and the actual measured pressure value is used as the feedback value. The deviation between the two is calculated and processed by the PID algorithm to output the opening command of the ethylene reflux flow valve.

[0045] In this embodiment, a common module for the pressure control PID algorithm is designed to output the reflux valve opening adjustment signal.

[0046] For example, the functions of steps S301 to S305 above can be realized through the intelligent control software of ZKTeco. The VBScript language is used for integrated development to form an intelligent controller that automatically switches control points and control parameters according to the working conditions.

[0047] For example, Figure 7 This is a schematic diagram of the overall process for controlling the ethylene unloading pressure of a VAC unit in one embodiment, as shown below. Figure 7 As shown, it may include steps S1 to S7.

[0048] Step S1: Start the ethylene reflux valve control program.

[0049] Step S2: Read the unloading status tag number to determine whether the device is in the unloading condition.

[0050] Step S3: If it is a non-unloading condition, execute the non-unloading condition control program with the buffer tank pressure as the control point; if it is an unloading condition, further determine whether the buffer tank pressure exceeds the control limit and whether the pressure change rate is too large. If the above conditions are met, execute the unloading condition control program with the buffer tank pressure as the control point. If the conditions are not met, execute the unloading condition control program with the tank pressure as the control point. Step S4: Read the pressure control points and corresponding actual measured values ​​of the ethylene storage tank and buffer tank, and calculate the control deviation.

[0051] Step S5: Call the PID program to calculate based on the control deviation.

[0052] Step S6: Read the PID calculation results, adjust the opening of the return valve to the calculated value, and complete one control output.

[0053] Step S7: Repeat steps S2 to S6 to achieve loop control.

[0054] As an optional example, the pressure control during ethylene unloading at a certain VAC unit is used as an application case to verify the actual effect of the control method of the present invention, as follows: 1) Variable structure design According to the VAC unit ethylene tank farm process flow (see [reference]), Figure 2 The control loop variable structure is designed as shown in Table 1. In Table 1, the input variables include the operating variables and the operating condition judgment variables, and the output variable is the controlled pressure parameter; "+ / -" indicates the direction of the input variable's effect on the output variable ("+" for positive action, "-" for negative action), and " / " indicates no control relationship.

[0055] Table 1. Pressure control loop structure of the VAC unit's ethylene tank area 2) Program control parameter settings Based on the intelligent control program for input and output variables, the PID control parameters of the ethylene reflux valve circuit are set as shown in Table 2 to ensure control accuracy and stability.

[0056] Table 2 Control parameters for ethylene reflux valve circuit 3) Comparison of control effects By collecting operational data for 15 consecutive days, the pressure control effect of the ethylene buffer tank before and after the commissioning of this invention was compared. The results are shown in Table 3; the pressure change trends are shown in the attached figures. Figure 8 (Routine manual operation), as shown in Figure 9 (the method used in the embodiment of this application). Figure 8 , Figure 9 In the table, PIC_72003_PV represents the pressure measurement value of the ethylene buffer tank, PT_72104 represents the pressure measurement value of the ethylene storage tank, and FIC_72101_OUT represents the opening degree of the ethylene reflux valve.

[0057] Table 3 Comparison of performance parameters of ethylene buffer tank before and after pressure commissioning (data for 15 consecutive days) As shown in Table 3, before commissioning (routine manual operation): the pressure fluctuation of the ethylene buffer tank was significant, with a standard deviation of 0.03195 kPa, requiring frequent manual adjustment of the pressure control valve PIC_72003, which disturbed the stability of the system.

[0058] As shown in Table 3, after commissioning (using the method of this invention): the pressure fluctuation of the ethylene buffer tank was significantly reduced, the standard deviation was reduced to 0.01530 kPa, the standard deviation was reduced by 52.11%, the pressure control valve PIC_72003 achieved minimal fluctuation operation, effectively suppressing the feed flow of the VAC synthesis unit, laying the foundation for improving the performance of subsequent synthesis reactions and product quality.

[0059] This embodiment can automatically identify the operating conditions of the device (unloading / non-unloading) and match the corresponding control strategy; realize the automated control of the pressure of the ethylene buffer tank throughout the ethylene unloading process; use ethylene reflux as the core pressure control means to reduce the adjustment range of the ethylene buffer tank pressure control valve and smooth the fluctuation of the feed flow of the synthesis reaction.

[0060] This embodiment enables intelligent control of tank area pressure during the ethylene unloading process of the VAC unit; it introduces unloading compressor parameters (lubricating oil temperature, exhaust gas temperature, and lubricating oil pressure) into the tank pressure control point for regulation, achieving automatic tracking and adaptive adjustment of the control point; it adopts an architecture of "centralized processing by host computer + execution by DCS", integrating data acquisition, auxiliary calculation, program compilation, and control algorithms into the host computer, and only writing the control output signal back to the distributed control system (DCS), simplifying the control process and ensuring system response efficiency.

[0061] It should be understood that the method in this embodiment has the following four advantages: 1) Improved control robustness: Targeting the dynamic characteristics of ethylene unloading conditions in VAC units, precise control of pressure parameters is achieved to ensure stable unit operation and accurate parameter tracking. 2) Optimized feed stability: Significantly reduces fluctuations in the feed flow rate of the VAC synthesis unit, maintaining stable feed even under strong interference scenarios such as operating condition switching and compressor start-up and shutdown; 3) Convenient and reliable switching between operating conditions: The operation of the control loop is simple and can achieve seamless switching between unloading and non-unloading conditions, with high operational reliability. 4) Reduced system load: All computing tasks are completed on the host computer, avoiding additional computing pressure on the DCS and improving the DCS's response speed to core process parameters.

[0062] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0063] Based on the same inventive concept, this application also provides a pressure control device for implementing the pressure control method based on the ethylene unloading condition of a VAC unit as described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more pressure control device embodiments based on the ethylene unloading condition of a VAC unit provided below can be found in the limitations of the pressure control method based on the ethylene unloading condition of a VAC unit described above, and will not be repeated here.

[0064] This application embodiment also provides a pressure control device based on the ethylene unloading condition of a VAC unit, the device may include: The determination module is used to determine the current operating conditions based on the process characteristics of the ethylene unloading compressor; The switching module is used to automatically switch the pressure control target according to the operating conditions and pressure parameters. The pressure control target includes: ethylene storage tank pressure and / or ethylene buffer tank pressure. The adjustment module is used to dynamically adjust the pressure control point of the storage tank in stages for different operating conditions; The calculation module is used to read the actual measured value of the pressure variable, set the algorithm detection interval, and calculate the pressure change rate through differential calculation. The processing module is used to calculate the deviation between the pressure control point as the target value and the actual measured pressure value as the feedback value, and then process the deviation through a PID algorithm to output the opening command of the ethylene reflux flow valve.

[0065] For example, the determining module is specifically used for: By analyzing the process characteristics of the ethylene unloading compressor, the lubricating oil temperature, lubricating oil pressure, and exhaust gas temperature of the unloading compressor are selected as the discrimination parameters. When the lubricating oil temperature, lubricating oil pressure, and exhaust gas temperature of the unloading compressor are all greater than their respective preset judgment values, the compressor is determined to be in the unloading condition. When any one of the lubricating oil temperature, lubricating oil pressure, and exhaust gas temperature of the unloading compressor is not greater than its respective preset judgment value, the compressor is determined to be in the non-unloading condition.

[0066] For example, the switching module is specifically used for: When the unit is not in unloading condition, the pressure of the ethylene buffer tank is used as the control target; When the unit is in the unloading condition and the pressure of the ethylene buffer tank exceeds the set control range, the pressure of the ethylene buffer tank will be used as the control target. When the unit is in unloading mode and simultaneously meets the conditions that the pressure change rate of the buffer tank is greater than the preset empirical multiple of the pressure change rate of the storage tank, and the pressure change rate of the buffer tank is greater than the set fixed empirical value, the pressure of the ethylene buffer tank is taken as the control target.

[0067] For example, the switching module is specifically used to: when the device is in the unloading condition, and simultaneously meets the conditions that the buffer tank pressure is within the set control range, the buffer tank pressure change rate is less than the preset empirical multiple of the storage tank pressure change rate, and the buffer tank pressure change rate is less than the set fixed empirical value, the ethylene storage tank pressure is used as the control target.

[0068] For example, the adjustment module is specifically used for: For non-unloading conditions, the tank pressure control point is set to the same value as the setting on the operation screen; For transitional operating conditions, a proportional function between tank pressure and lubricating oil temperature is established, and the actual control point of tank pressure is output in real time according to the change of lubricating oil temperature. For unloading operations, the tank pressure control point is equal to the set value on the operation screen plus a specified value.

[0069] The various modules in the pressure control device based on the ethylene unloading operation of the VAC unit described above can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0070] In an exemplary embodiment, a computer device is provided, which may be a server. The computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is connected to the system bus via the I / O interfaces. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database of the computer device stores data. The I / O interfaces of the computer device are used for exchanging information between the processor and external devices. The communication interface of the computer device is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a pressure control method based on the ethylene unloading conditions of a VAC unit.

[0071] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0072] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0073] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0074] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0075] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A pressure control method based on the VAC device ethylene unloading working condition, characterized in that, The method comprises: determining the current working condition according to the process characteristics of the ethylene unloading compressor; automatically switching the pressure control target according to the working condition and the pressure parameter, the pressure control target comprising: the ethylene storage tank pressure and / or the ethylene buffer tank pressure; dynamically adjusting the storage tank pressure control point in stages for different working conditions; reading the actual measurement value of the pressure variable, setting the algorithm detection interval time, and obtaining the pressure change rate through differential calculation; taking the pressure control point as the target value and the actual measurement value of the pressure as the feedback value, calculating the deviation between the two, and outputting the opening instruction of the ethylene backflow flow valve through the PID algorithm.

2. The method of claim 1, wherein, The determination of the current working condition according to the process characteristics of the ethylene unloading compressor comprises: selecting the unloading compressor lubricating oil temperature, lubricating oil pressure and exhaust gas temperature as the discriminant parameters by analyzing the process characteristics of the ethylene unloading compressor; determining that the compressor is in the unloading working condition when the unloading compressor lubricating oil temperature, lubricating oil pressure and exhaust gas temperature are all greater than the respective preset determination values; determining that the compressor is in the non-unloading working condition when any one of the unloading compressor lubricating oil temperature, lubricating oil pressure and exhaust gas temperature is not greater than the respective preset determination value.

3. The method of claim 1, wherein, The automatic switching of the pressure control target according to the working condition and the pressure parameter comprises: taking the ethylene buffer tank pressure as the control target when the device is in the non-unloading working condition; taking the ethylene buffer tank pressure as the control target when the device is in the unloading working condition and the ethylene buffer tank pressure exceeds the set control range; taking the ethylene buffer tank pressure as the control target when the device is in the unloading working condition and simultaneously satisfies the conditions that the buffer tank pressure change rate is greater than the preset empirical multiple of the storage tank pressure change rate and the buffer tank pressure change rate is greater than the set fixed empirical value.

4. The method of claim 1, wherein, The automatic switching of the pressure control target according to the working condition and the pressure parameter comprises: taking the ethylene storage tank pressure as the control target when the device is in the unloading working condition and simultaneously satisfies the conditions that the buffer tank pressure is within the set control range, the buffer tank pressure change rate is less than the preset empirical multiple of the storage tank pressure change rate, and the buffer tank pressure change rate is less than the set fixed empirical value.

5. The method according to any one of claims 1 to 4, characterized in that, The dynamic adjustment of the storage tank pressure control point in stages for different working conditions comprises: setting the storage tank pressure control point equal to the operating picture set value for the non-unloading working condition; establishing a proportional function of the storage tank pressure and the lubricating oil temperature for the transition working condition, and outputting the storage tank pressure actual control point in real time according to the lubricating oil temperature change; setting the storage tank pressure control point equal to the operating picture set value plus a specified value for the unloading working condition.

6. A pressure control device based on the unloading condition of ethylene in a VAC device, characterized by, The device comprises: a determination module for determining the current working condition according to the process characteristics of the ethylene unloading compressor; a switching module for automatically switching the pressure control target according to the working condition and the pressure parameter, the pressure control target comprising: the ethylene storage tank pressure and / or the ethylene buffer tank pressure; an adjustment module for dynamically adjusting the storage tank pressure control point in stages for different working conditions; a calculation module for reading the actual measurement value of the pressure variable, setting the algorithm detection interval time, and obtaining the pressure change rate through differential calculation; The processing module is configured to take the pressure control point as a target value, take an actual pressure measurement value as a feedback value, calculate a deviation between the two values, process the deviation through a PID algorithm, and output an opening degree instruction of an ethylene reflux flow valve.

7. The apparatus of claim 6, wherein, The determining module is specifically configured to: By analyzing the process characteristics of the ethylene unloading compressor, the unloading compressor lubricating oil temperature, the lubricating oil pressure, and the exhaust gas temperature are selected as the discrimination parameters; In a case where the unloading compressor lubricating oil temperature, the lubricating oil pressure, and the exhaust gas temperature are all greater than respective preset determination values, it is determined that the compressor is in the unloading working condition; In a case where any one of the unloading compressor lubricating oil temperature, the lubricating oil pressure, and the exhaust gas temperature is not greater than the respective preset determination value, it is determined that the compressor is in the non-unloading working condition.

8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, The computer program, when executed by the processor, implements the steps of the method of any one of claims 1 to 5.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program, when executed by the processor, implements the steps of the method of any one of claims 1 to 5.

10. A computer program product comprising a computer program, characterized in that, The computer program, when executed by the processor, implements the steps of the method of any one of claims 1 to 5.

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