Method for controlling total pressure and ethylene partial pressure in polymerization reaction of gas phase fluidized bed pe device

Abstract

This invention provides a method for controlling the total pressure and ethylene partial pressure of a gas-phase fluidized bed PE (polyethylene) reactor. The method includes: influencing the ethylene partial pressure and total pressure by adjusting the catalyst; obtaining the maximum and minimum values ​​of the ethylene partial pressure within time T1, and the maximum and minimum values ​​of the total pressure filtration value within time T2; predicting the changing trends of the ethylene partial pressure and total pressure filtration values, and determining a catalyst adjustment strategy based on these trends; and stabilizing the ethylene partial pressure and total pressure according to the adjustment strategy under varying load conditions. This invention improves the robustness of total pressure and ethylene partial pressure control, significantly reduces the workload of on-site operators, avoids numerous operational errors, effectively ensures safe plant operation, reduces overshoot caused by cumulative catalyst addition, and the method can be implemented on a host computer, effectively reducing the system's operating load.

Description

Technical Field

[0001] This invention relates to the field of polymerization reaction control technology, specifically to a method for controlling the total pressure and ethylene partial pressure of a polymerization reaction in a gas-phase fluidized bed PE plant. Background Technology

[0002] In the conventional control of a gas-phase fluidized bed PE unit, the total pressure is the pressure required for the polymerization reaction. The ethylene partial pressure is the product of the ethylene concentration and the total pressure. Polyethylene production consumes a large amount of ethylene, and maintaining a certain ethylene partial pressure is crucial for reaction stability, ensuring the continuous and stable polymerization process. Total pressure is also critical to production; high total pressure increases the fluidizing gas velocity, leading to higher compressor shaft power and potential equipment safety hazards.

[0003] Currently, catalysts are generally used to coordinate the control of ethylene partial pressure and total pressure. However, the control characteristics of total pressure and ethylene partial pressure exhibit typical problems such as large cycles, multiple disturbances, large hysteresis, and nonlinearity. Furthermore, ethylene partial pressure and reactor total pressure often show inverse characteristics, significantly increasing the difficulty of control. Existing systems cannot achieve automated control using conventional or advanced control methods, while manual operation is limited by the skill and energy of operators, easily leading to untimely adjustments or severe overshoot, resulting in large fluctuations in relevant process parameters. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE plant.

[0005] In a first aspect, this application provides a method for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE plant, including:

[0006] The partial pressure and total pressure of ethylene can be influenced by adjusting the catalyst.

[0007] Obtain the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2;

[0008] Predict the changing trends of ethylene partial pressure and total pressure filtration values, and determine the catalyst adjustment strategy based on the changing trends;

[0009] Under load variations, the ethylene partial pressure and total pressure are stabilized according to the aforementioned adjustment strategy.

[0010] Optionally, the total pressure filter value within ten minutes is used as the controlled variable to obtain the maximum and minimum values ​​of the total pressure filter value within time T2.

[0011] Optionally, the changing trends of the filtration values ​​of ethylene partial pressure and total pressure are predicted, and the catalyst adjustment strategy is determined based on the changing trends, including:

[0012] Obtain the current value of ethylene partial pressure. If the maximum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is upward.

[0013] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the upper limit range, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0014] If the minimum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is downward.

[0015] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0016] Optionally, the changing trends of the filtration values ​​of ethylene partial pressure and total pressure are predicted, and the catalyst adjustment strategy is determined based on the changing trends, including:

[0017] Obtain the current total pressure filter value. If the maximum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of total pressure change is upward.

[0018] If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0019] If the minimum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of the total pressure change is downward.

[0020] If the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second partial pressure counter is less than the preset value and the fourth total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0021] Optionally, under load variations, stabilizing the ethylene partial pressure and total pressure according to the aforementioned adjustment strategy includes:

[0022] Data on the changes of ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into the written program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure.

[0023] The partial pressure and total pressure of ethylene are stabilized by a catalyst control strategy based on the partial pressure and total pressure of ethylene.

[0024] Secondly, embodiments of this application provide a device for controlling the total polymerization pressure and ethylene partial pressure of a gas-phase fluidized bed PE plant, comprising:

[0025] The adjustment module is used to influence the partial pressure and total pressure of ethylene by adjusting the catalyst;

[0026] The acquisition module is used to acquire the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2.

[0027] The prediction module is used to predict the changing trends of the filtration values ​​of ethylene partial pressure and total pressure, and to determine the catalyst adjustment strategy based on the changing trends.

[0028] The control module is used to stabilize the ethylene partial pressure and total pressure according to the adjustment strategy under load changes.

[0029] Optionally, the acquisition module is specifically used to: take the total pressure filter value within ten minutes as the controlled variable, and acquire the maximum and minimum values ​​of the total pressure filter value within time T2.

[0030] Optionally, the prediction module is specifically used for:

[0031] Obtain the current value of ethylene partial pressure. If the maximum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is upward.

[0032] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the upper limit range, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0033] If the minimum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is downward.

[0034] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0035] Optionally, the prediction module is specifically used for:

[0036] Obtain the current total pressure filter value. If the maximum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of total pressure change is upward.

[0037] If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0038] If the minimum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of the total pressure change is downward.

[0039] If the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second partial pressure counter is less than the preset value and the fourth total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0040] Optionally, the control module is specifically used for:

[0041] Data on the changes of ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into the written program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure.

[0042] The partial pressure and total pressure of ethylene are stabilized by a catalyst control strategy based on the partial pressure and total pressure of ethylene.

[0043] Thirdly, embodiments of this application provide a device for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE plant, comprising: a processor and a memory, wherein the memory stores executable program instructions, and when the processor calls the program instructions in the memory, the processor is used to:

[0044] The steps of the method for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE plant as described in any one of the first aspects.

[0045] Fourthly, embodiments of this application provide a computer-readable storage medium for storing a program, which, when executed, implements the steps of the method for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE apparatus as described in any one of the first aspects.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This invention addresses the typical drawbacks of total pressure and ethylene partial pressure control characteristics, such as large cycles, multiple disturbances, large hysteresis, and nonlinearity. Based on process analysis of the polymerization reaction system of a gas-phase fluidized bed PE unit, a more robust control strategy is designed through autonomous programming of intelligent control software, utilizing data mining and online data iteration techniques. This control scheme aims to achieve stable control of both total pressure and ethylene partial pressure, while also ensuring a rapid response and preventing system divergence after load changes, thus providing the control loop with better robustness. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0049] Figure 1 This is a schematic diagram illustrating the principle of the PE polymerization reaction in an embodiment of the present invention;

[0050] Figure 2 A flowchart of a method for controlling the total pressure of polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE device is provided for embodiments of this application;

[0051] Figure 3 This is a flowchart of the method for controlling the partial pressure of ethylene in the embodiments of this application;

[0052] Figure 4 This is a flowchart of the total pressure control method in an embodiment of this application;

[0053] Figure 5 This diagram illustrates the changing trends of ethylene partial pressure and total pressure when the load is increased. Figure 1 ;

[0054] Figure 6 This diagram illustrates the changing trends of ethylene partial pressure and total pressure when the load is increased. Figure 2 .

[0055] In the picture:

[0056] 1. PE polymerization reactor; 2. Heat exchanger; 3. Circulating gas compressor; 4. Total pressure; 5. Ethylene partial pressure. Detailed Implementation

[0057] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. 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. These all fall within the scope of protection of the present invention.

[0058] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be for both fixing and circuit connection purposes.

[0059] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] Figure 1 This is a schematic diagram illustrating the principle of the PE polymerization reaction in an embodiment of the present invention, as shown below. Figure 1 As shown, raw materials ethylene, butene, and hydrogen, under the action of a catalyst, enter the reactor simultaneously with nitrogen and refrigerant ICA (isopentane). A polymerization reaction occurs at a temperature of 85℃-95℃ and a pressure of 2.2-2.5 MPa. The powder produced by the polymerization reaction is discharged from the bottom of the reactor, while the unreacted circulating gas is sent from the top of the reactor to a circulating gas compressor, cooled, and then returned to the reactor for reuse. CO is used as an inactivating agent; it is added promptly if any abnormalities occur in the reaction to terminate the reaction and prevent explosive polymerization. Under normal circumstances, CO is kept off.

[0062] Figure 2 A flowchart illustrating a method for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE unit, as provided in this application embodiment, is shown below. Figure 2 As shown, the method in this embodiment may include:

[0063] Step S201: Affect the partial pressure and total pressure of ethylene by adjusting the catalyst.

[0064] In this embodiment, by analyzing the process characteristics of the polymerization reaction system of the gas-phase fluidized bed PE unit, the catalyst is manipulated to control the reaction rate and thus affect the change of ethylene partial pressure. After the catalyst adjustment causes the gas phase composition in the reactor to change, the total pressure will also change. That is, the catalyst affects both the ethylene partial pressure and the total pressure.

[0065] Step S202: Obtain the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2.

[0066] In this embodiment, since the total pressure is affected by the reaction temperature, in order to reduce the fluctuation caused by the temperature, the filtered value of the total pressure within ten minutes can be selected, and the filtered value of the total pressure within this time period can be used as the controlled variable; the ethylene partial pressure is not processed and is directly selected as the controlled variable.

[0067] It should be noted that this embodiment does not limit the specific values ​​of T1 and T2, and those skilled in the art can set them according to actual requirements.

[0068] Step S203: Predict the changing trends of the filtration values ​​of ethylene partial pressure and total pressure, and determine the catalyst adjustment strategy based on the changing trends.

[0069] In this embodiment, Zhejiang Zhongkong Intelligent Control Software can be used to select the maximum and minimum values ​​of ethylene partial pressure within time T1 based on the polymerization reaction characteristics and process production features; and select the maximum and minimum values ​​of the total pressure filter value within time T2. Then, artificial intelligence-inspired trend prediction is used to control the total pressure and ethylene partial pressure through interval constraints.

[0070] For example, Figure 3 This is a flowchart of the method for controlling the partial pressure of ethylene in an embodiment of this application, as shown below. Figure 3 As shown, the current value of ethylene partial pressure is obtained. If the maximum value of ethylene partial pressure within time T2 is equal to the current value, the predicted trend of ethylene partial pressure change is upward. If the current value of ethylene partial pressure is within the upper or lower limit range or outside the upper limit range, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for a preset duration. If the minimum value of ethylene partial pressure within time T2 is equal to the current value, the predicted trend of ethylene partial pressure change is downward. If the current value of ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for a preset duration.

[0071] For example, Figure 4 This is a flowchart of the total pressure control method in an embodiment of this application, as shown below. Figure 4As shown, the current total pressure filter value is obtained. If the maximum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of total pressure change is upward. If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for the preset duration. If the minimum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of total pressure change is downward. If the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second partial pressure counter is less than the preset value and the fourth total pressure timer is zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0072] Step S204: Under load changes, stabilize the ethylene partial pressure and total pressure according to the adjustment strategy.

[0073] Because changes in load can cause an increase in ethylene partial pressure, during normal production, the catalyst needs to be adjusted promptly when the load changes to avoid lag in later adjustments and production fluctuations. The amount of catalyst to adjust when the load is changed is determined using a nonlinear model based on the relationship curves between ethylene partial pressure, total pressure, load, and catalyst activity.

[0074] In this embodiment, a catalyst change adjustment program was written using Zhejiang Zhongkong Intelligent Control Software. The program controls catalyst addition during load changes, coordinating with normal control to achieve stable ethylene partial pressure and total pressure under varying load conditions.

[0075] Optionally, the above method may further include the following steps:

[0076] Data on the changes in ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into a program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure.

[0077] In this embodiment, the above objectives can be achieved through data acquisition, programming, and on-site debugging in the Zhejiang Zhongkong APC-Suite series software.

[0078] Specifically, when the load is increased, the catalyst is increased by C kg / t; similarly, when the load is decreased, the catalyst is decreased by C kg / t. The maximum step limit for catalyst adjustment is set to 0.2 kg / t. Simultaneously, adjustments are made according to the above control method after changes in total pressure and ethylene partial pressure, achieving the desired effect through comprehensive adjustment.

[0079] This embodiment improves the robustness of total pressure and ethylene partial pressure, ensuring stable and reliable unit operation. It significantly reduces the workload of on-site operators, avoids numerous operational errors, and effectively guarantees safe unit operation. This embodiment introduces the concepts of maximum and minimum values, allowing for large-scale adjustments when there is significant lag, enabling early intervention and reducing overshoot caused by cumulative additions to the unit. It utilizes a countdown cycle method to propose large-cycle adjustment of ethylene partial pressure and total pressure by the catalyst, and sets the adjustment step size for the ethylene partial pressure and total pressure ranges. All calculations in this embodiment can be performed on the host computer, reducing the operating load of the DCS (Distributed Control System) and improving its safety.

[0080] Specifically, the specific implementation and control effect of the control method in this invention are illustrated using the gas-phase fluidized bed PE polymerization reaction system as a case study.

[0081] 1. Trend Forecasting

[0082] (1) Ethylene partial pressure trend prediction

[0083] Take the maximum and minimum values ​​within time T1. When the current value coincides with the maximum value, it indicates that the ethylene partial pressure is currently in an upward trend; when the current value coincides with the minimum value, it indicates that the ethylene partial pressure is currently in a downward trend.

[0084] (2) Overall Pressure Trend Forecast

[0085] Take the maximum and minimum values ​​within time T2. When the current value coincides with the maximum value, it indicates that the total pressure is currently in an upward trend; when the current value coincides with the minimum value, it indicates that the total pressure is currently in a downward trend.

[0086] Weighting

[0087] Considering the importance of the fluidizing gas velocity, the catalyst adjustment is assigned a greater weight to the total pressure and has a larger adjustment range, while the ethylene partial pressure has a smaller weight and a smaller adjustment range. The adjustment period is T minutes. It should be noted that this embodiment does not limit the specific value of T, and those skilled in the art can set it according to actual requirements.

[0088] 3. The catalyst regulates the partial pressure of ethylene and coordinates the total pressure, which can be divided into two cases.

[0089] (1) When the ethylene partial pressure is within the upper and lower operating limits, based on the previous trend prediction, if it increases, both the partial pressure timer 1 and the total pressure timer 3 will be zero and the total pressure value will be above the lower limit constraint. At this time, the catalyst will adjust the step size upward by A and maintain it for T minutes. If it decreases, both the second partial pressure timer and the fourth total pressure timer will be zero and the total pressure value will be below the upper limit constraint. The catalyst will adjust the step size downward by A and maintain it for T minutes.

[0090] (2) If the ethylene partial pressure is outside the operating upper and lower limits, and continues to rise and exceeds the upper limit, with both the first partial pressure timer and the third total pressure timer at zero and the total pressure value above the lower limit constraint, the catalyst will be adjusted up by 1.5 times the A step and maintained for T minutes. If it continues to fall and exceeds the lower limit, with both the second partial pressure timer and the fourth total pressure timer at zero and the total pressure value below the upper limit constraint, the catalyst will be adjusted down by 1.5 times the A step and maintained for T minutes.

[0091] 4. The catalyst regulates the total pressure and coordinates the partial pressure of ethylene, which can be divided into two cases.

[0092] (1) When the total pressure is within the upper and lower limits of operation, based on the trend prediction above, if an increase occurs, when the first partial pressure timer is less than 5 and the total pressure timer 3 is zero, the catalyst will adjust the B step upward and maintain it for T minutes. If a decrease occurs, when the second partial pressure timer is less than 5 and the total pressure timer 4 is zero, the catalyst will adjust the B step downward and maintain it for T minutes.

[0093] (2) If the total pressure continues to rise outside the operating upper and lower limits, the catalyst will increase by 1.5 times the B step when the first partial pressure timer is less than 5 and the third total pressure timer is zero, and maintain this for T minutes. If the total pressure continues to fall, the catalyst will decrease by 1.5 times the B step when the second partial pressure timer is less than 5 and the fourth total pressure timer is zero, and maintain this for T minutes.

[0094] It should be noted that A and B in this embodiment are not limited to specific values; they are only used for distinction. In practical applications, those skilled in the art can set the adjustment range of the catalyst as needed.

[0095] Figure 5 , Figure 6 The trends of ethylene partial pressure and total pressure before and after commissioning are shown to verify the advantages of this method.

[0096] The method for stable control of total pressure and ethylene partial pressure in a gas-phase fluidized bed PE unit provided in this application proposes the concepts of maximum and minimum values ​​of total pressure and ethylene partial pressure over a period of time. Combined with model prediction and trend prediction control strategies, it better achieves decoupling of nonlinear multivariable control. After load changes, considering the characteristics of large lag, nonlinearity, and multiple disturbances in control, the catalyst is adjusted in advance to reduce later impacts, thus solving the multivariable coordination problem. Using a countdown zeroing cycle method, a one-to-two control decoupling with nonlinear, large lag, and multiple disturbance characteristics is achieved, enabling large-cycle control of ethylene partial pressure and total pressure by the catalyst. Using an interval adjustment method, the step size within and outside the adjustment interval is distinguished to achieve optimized regional control, enriching the optimization path of multivariable control.

[0097] This application embodiment also provides a device for controlling the total pressure of the polymerization reaction and the partial pressure of ethylene in a gas-phase fluidized bed PE plant. The device in this embodiment may include:

[0098] The adjustment module is used to influence the partial pressure and total pressure of ethylene by adjusting the catalyst;

[0099] The acquisition module is used to acquire the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2.

[0100] The prediction module is used to predict the changing trends of the filtration values ​​of ethylene partial pressure and total pressure, and to determine the catalyst adjustment strategy based on the changing trends.

[0101] The control module is used to stabilize the ethylene partial pressure and total pressure according to the adjustment strategy under load changes.

[0102] Optionally, the acquisition module is specifically used to: take the total pressure filter value within ten minutes as the controlled variable, and acquire the maximum and minimum values ​​of the total pressure filter value within time T2.

[0103] Optionally, the prediction module is specifically used for:

[0104] Obtain the current value of ethylene partial pressure. If the maximum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is upward.

[0105] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the upper limit range, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0106] If the minimum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is downward.

[0107] If the current value of ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0108] Optionally, the prediction module is specifically used for:

[0109] Obtain the current total pressure filter value. If the maximum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of total pressure change is upward.

[0110] If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step upward and maintain it for the preset duration.

[0111] If the minimum value of the current total pressure filter value within time T2 is equal to the current value, then the predicted trend of the total pressure change is downward.

[0112] If the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second partial pressure counter is less than the preset value and the fourth total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step downward and maintain it for the preset duration.

[0113] Optionally, the control module is specifically used for:

[0114] Data on the changes of ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into the written program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure.

[0115] The partial pressure and total pressure of ethylene are stabilized by a catalyst control strategy based on the partial pressure and total pressure of ethylene.

[0116] The device in this embodiment can achieve Figure 2 For details on the implementation process and technical effects of the method shown, please refer to [link / reference]. Figure 2 The relevant descriptions of the methods shown will not be repeated here.

[0117] The above is the core idea of ​​this invention. To make the above-mentioned objectives, features, and advantages of this invention more apparent and understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0118] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0119] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for controlling the total pressure and ethylene partial pressure in a gas phase fluidized bed process PE plant polymerization, characterized in that, include: The partial pressure and total pressure of ethylene can be influenced by adjusting the catalyst. Obtain the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2; Predict the changing trends of ethylene partial pressure and total pressure filtration values, and determine the catalyst adjustment strategy based on the changing trends; Obtain the current value of ethylene partial pressure. If the maximum value of ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of ethylene partial pressure change is upward. If the current value of ethylene partial pressure is within the upper or lower limit range or outside the upper limit range, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step upward and maintain it for the preset duration. If the minimum ethylene partial pressure within time T2 is equal to the current value, the predicted trend of ethylene partial pressure change is downward; if the current ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration; obtain the current total pressure filter value, and if the maximum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of total pressure change is upward; If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step upward and maintain it for the preset duration; If the minimum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of the total pressure change is downward; if the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second pressure counter is less than the preset value and the fourth total pressure timer is zero, the catalyst is controlled to adjust the step size B or 1.5B downward and maintain it for the preset duration. Under load variations, the ethylene partial pressure and total pressure are stabilized according to the aforementioned adjustment strategy.

2. The control method of total pressure and ethylene partial pressure in the polymerization reaction of a gas phase fluidized bed method PE apparatus according to claim 1, characterized by, Using the total pressure filter value within ten minutes as the controlled variable, obtain the maximum and minimum values ​​of the total pressure filter value within time T2.

3. The control method of total pressure and ethylene partial pressure in the polymerization reaction of a gas phase fluidized bed method PE device according to claim 1 or 2, characterized by, Under load variations, the adjustment strategy described above is used to stabilize the ethylene partial pressure and total pressure, including: Data on the changes of ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into the written program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure. The partial pressure and total pressure of ethylene are stabilized by a catalyst control strategy based on the partial pressure and total pressure of ethylene.

4. A control device for the total pressure and ethylene partial pressure of a polymerization reaction in a gas phase fluidized bed process PE device, characterized in that, include: The adjustment module is used to influence the partial pressure and total pressure of ethylene by adjusting the catalyst; The acquisition module is used to acquire the maximum and minimum values ​​of ethylene partial pressure during time T1, and the maximum and minimum values ​​of the total pressure filter value during time T2. The prediction module is used to predict the changing trends of the ethylene partial pressure and total pressure, and to determine the catalyst adjustment strategy based on the changing trends. Specifically, the prediction module is used to: obtain the current value of the ethylene partial pressure; if the maximum value of the ethylene partial pressure within time T2 is equal to the current value, then the predicted trend of the ethylene partial pressure is upward; if the current value of the ethylene partial pressure is within the upper and lower limits or outside the upper limit, and the total pressure is greater than the lower limit, and the first partial pressure timer and the third total pressure timer are both zero, then the catalyst is controlled to adjust upward by step B or step 1.5B and maintained for a preset duration. If the minimum ethylene partial pressure within time T2 is equal to the current value, the predicted trend of ethylene partial pressure change is downward; if the current ethylene partial pressure is within the upper or lower limit range or outside the lower limit range, and the total pressure is less than the lower limit, and the second partial pressure timer and the fourth total pressure timer are both zero, the catalyst is controlled to adjust the B step or 1.5B step downward and maintain it for the preset duration; obtain the current total pressure filter value, and if the maximum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of total pressure change is upward; If the current total pressure filter value is within the upper or lower limit range or outside the upper limit range, and the first partial pressure counter is less than the preset value and the third total pressure timer is zero, control the catalyst to adjust the B step or 1.5B step upward and maintain it for the preset duration; If the minimum value of the current total pressure filter value within time T2 is equal to the current value, the predicted trend of the total pressure change is downward; if the current total pressure filter value is within the upper or lower limit range or outside the lower limit range, and the second pressure counter is less than the preset value and the fourth total pressure timer is zero, the catalyst is controlled to adjust the step size B or 1.5B downward and maintain it for the preset duration. The control module is used to stabilize the ethylene partial pressure and total pressure according to the adjustment strategy under load changes.

5. The device for controlling the total polymerization pressure and ethylene partial pressure of a gas-phase fluidized bed PE unit according to claim 4, characterized in that, The acquisition module is specifically used to: take the total pressure filter value within ten minutes as the controlled variable, and obtain the maximum and minimum values ​​of the total pressure filter value within time T2.

6. The apparatus for controlling the total pressure and the partial pressure of ethylene in the polymerization reaction of a gas phase fluidized bed method PE according to claim 4 or 5, characterized by, The control module is specifically used for: Data on the changes of ethylene partial pressure and total pressure over time under different loads and catalyst conditions were collected and substituted into the written program for simulation and debugging to obtain the catalyst control strategy for ethylene partial pressure and total pressure. The partial pressure and total pressure of ethylene are stabilized by a catalyst control strategy based on the partial pressure and total pressure of ethylene.

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