Polymer production brand automatic switching control method, electronic device, and storage medium

Abstract

The application discloses a polymer production brand automatic switching control method, an electronic device and a storage medium. The method comprises the following steps: when it is judged that a production brand switching transition process occurs, the mass proportion of new production brand material in products is calculated every interval of a preset time interval; the production brand switching transition process is a process of switching from old production brand raw material ratio to new production brand raw material ratio during polymer production; whether the cut bin point requirement is met is judged according to the mass proportion of new production brand material in products; when the cut unqualified bin point requirement is met, the product is switched from the old production brand qualified bin to the unqualified bin; and when the cut qualified bin point requirement is met, the product is switched from the unqualified bin to the new production brand qualified bin. The mass proportion of new production brand material in products is predicted, whether the cut bin point requirement is met is automatically judged, the cut bin point requirement is reminded when the cut bin point requirement is met, and the generation of transition material is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of polymer production processes, and in particular to an automatic switching control method, electronic device, and storage medium for polymer production grades. Background Technology

[0002] In polymer production, such as polycarbonate production, product grades are typically classified using viscosity-average molecular weight (MAW). During production, it's necessary to switch between product grades based on customer requirements. Switching product grades in polymer production requires altering the raw material ratios at the reaction stage, involving a lengthy process. This switching process generates transition material, resulting in waste. During the switchover, operators predict the replacement progress based on experience and sampling analysis data. However, sampling analysis has a lag; to ensure transition material doesn't mix into the product silo, the switch is often initiated prematurely from the product silo to the transition silo, and delayed from the transition silo to the qualified silo. This results in a large quantity of transition material and significant batch-to-batch variations. Different product grades also have different critical process parameters. Therefore, during product grade switching, operators need to adjust these parameters based on on-site observations of the production status, making the operation both difficult and labor-intensive. Summary of the Invention

[0003] Therefore, it is necessary to provide an automatic switching control method, electronic equipment, and storage medium for polymer production grades, addressing the technical problems in existing polymer production where the switching of production grades relies on manual operation experience, resulting in large amounts of transition material and significant batch-to-batch differences, as well as a large amount of manual operation during the transition process.

[0004] This invention provides a method for automatic switching control of polymer production grades, comprising:

[0005] When it is determined that a production grade switching transition process has occurred, the mass ratio of the new production grade material in the product is calculated at each preset time interval. The production grade switching transition process is the process of switching from the old production grade raw material ratio to the new production grade raw material ratio during polymer production.

[0006] Based on the mass percentage of the new production grade material in the product, it is determined whether the cut-off point requirements are met. The cut-off points include cut-off points for unqualified materials and cut-off points for qualified materials. When the cut-off point requirement is met, a prompt is made to switch the product from the qualified material silo of the old production grade to the unqualified material silo. When the cut-off point requirement is met, a prompt is made to switch the product from the unqualified material silo to the qualified material silo of the new production grade.

[0007] Furthermore, before calculating the mass percentage of the new production grade material in the product at preset time intervals when a production grade switching transition process is determined to have occurred, the method further includes:

[0008] The start-up time is calculated based on the planned switching time for production grades and the equipment liquid level drop time. The planned switching time for production grades is the planned time to switch the old production grade raw material ratio to the new production grade raw material ratio.

[0009] When the start-up time is reached, the liquid level of one or more first devices is lowered to the target liquid level corresponding to that device. The liquid level drop time of the device is the maximum drop time required for the liquid level of the multiple first devices to drop to the target liquid level corresponding to that device.

[0010] Furthermore, it also includes:

[0011] When the start-up time is reached, monitor the raw material ratio of the reaction process;

[0012] If the raw material ratio changes, it is determined that a production grade switching transition process has occurred;

[0013] Switch the polymer production control mode from viscosity control to concentration control;

[0014] The liquid level of one or more second devices is lowered to the target liquid level corresponding to the device, the second devices being located downstream of the first device in the polymer production process.

[0015] Furthermore, the calculation of the mass percentage of newly produced grade material in the product at each preset time interval specifically includes:

[0016] At each preset time interval ΔT, the mass percentage of newly produced grade material in the discharge of each key equipment at time T in the polymer production process is calculated sequentially:

[0017] X2 T =F1 T △T(X1 T +X1 T-1 ) / (2V1L1+F1 T △T)+(2V1L1-F1 T △T) / (2V1L1+F1 T △T)X2 T-1 ,

[0018] Among them, X2 T F1 represents the mass percentage of newly produced grade material in the equipment discharge at time T. T Let X1 be the feed flow rate of the equipment at time T. T The mass percentage of newly produced grade material in the equipment feed at time T, V1 is the equipment volume, L1 is the current liquid level of the equipment at time T, and X1 is the mass percentage of newly produced grade material in the equipment feed. T-1 The mass percentage of newly produced grade material in the equipment feed at time T-1, X2 T-1The mass percentage of newly produced grade material in the equipment discharge at time T-1, where T is the current time, T-1 is the time when the mass percentage of newly produced grade material in the equipment discharge was last calculated, and △T is the time interval between time T and time T-1.

[0019] The mass percentage of newly produced grade materials in the discharge of key equipment outputting the product in the polymer production process is used as the mass percentage of newly produced grade materials in the product.

[0020] Furthermore, it also includes: calculating the linear region of viscosity-average molecular weight change during the transition process of switching production grades, wherein the linear region of viscosity-average molecular weight change is the region in which the viscosity-average molecular weight of the product changes linearly from the viscosity-average molecular weight of the old production grade product to the viscosity-average molecular weight of the new production grade product.

[0021] Furthermore, the linear variation region is the minimum of the viscosity-average molecular weight of the old production grade product and the viscosity-average molecular weight of the new production grade product plus a preset upper limit to the maximum of the viscosity-average molecular weight of the old production grade product and the viscosity-average molecular weight of the new production grade product minus a preset lower limit.

[0022] Furthermore, determining whether the cut-off point requirement is met based on the mass percentage of the newly produced material in the product specifically includes:

[0023] Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product. If the predicted viscosity-average molecular weight is within the linear range of viscosity-average molecular weight change, then prompt the user to perform multiple viscosity-average molecular weight samplings on the current product.

[0024] Calculate the results of multiple viscosity-average molecular weight samplings, and calculate the slope of the viscosity-average molecular weight change.

[0025] Based on the sampling start time and the slope of the viscosity-average molecular weight change, the cut-off point time for reaching the viscosity-average molecular weight of the qualified warehouse is calculated. The cut-off point time includes the cut-off point time for the unqualified warehouse and the cut-off point time for the qualified warehouse. The viscosity-average molecular weight at the cut-off point includes the viscosity-average molecular weight of the unqualified warehouse and the viscosity-average molecular weight of the qualified warehouse. The viscosity-average molecular weight of the unqualified warehouse is the viscosity-average molecular weight of the old production brand product, and the viscosity-average molecular weight of the qualified warehouse is the viscosity-average molecular weight of the new production brand product.

[0026] Determine whether the current time has reached the cut-off point time.

[0027] Furthermore, determining whether the cut-off point requirement is met based on the mass percentage of the newly produced material in the product specifically includes:

[0028] Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product, and determine whether the predicted viscosity-average molecular weight reaches the cut-off viscosity-average molecular weight. The cut-off viscosity-average molecular weight includes the cut-off unqualified silo viscosity-average molecular weight and the cut-off qualified silo viscosity-average molecular weight. The cut-off unqualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the old production grade product, and the cut-off qualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the new production grade product.

[0029] This invention provides an electronic device, comprising:

[0030] At least one processor; and,

[0031] A memory communicatively connected to at least one of the processors; wherein,

[0032] The memory stores instructions that can be executed by at least one of the processors to enable at least one of the processors to perform the polymer production grade automatic switching control method as described above.

[0033] The present invention provides a storage medium that stores computer instructions, which, when executed by a computer, are used to perform all steps of the polymer production grade automatic switching control method as described above.

[0034] This invention automatically determines whether the production cut-off point requirement is met by predicting the mass percentage of the new production grade material in the product. If the requirement is met, it alerts the user to cut the material. This automates the production grade switching process, reduces transitional materials, decreases manual workload, and lowers the error rate. Finally, it reduces transitional material generation through two methods: reducing system inventory and accurately predicting the cut-off point. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the automatic switching control method for polymer production grades according to the present invention.

[0036] Figure 2 This is a flowchart of an automatic switching control method for polymer production grades according to an embodiment of the present invention.

[0037] Figure 3 This is a flowchart illustrating the automatic switching control method for polymer production grades in the preferred embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram of the hardware structure of an electronic device according to the present invention. Detailed Implementation

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0040] In polycarbonate production, different production grades are distinguished by viscosity-average molecular weight. Production grades need to be switched according to market demand. The switching method is to change the ratio of reaction raw materials. Then, the new production grade material gradually replaces the old production grade material. When the mixture cannot meet the quality requirements, the product is sent to the unqualified material silo. When the mixture meets the quality requirements of the new production grade, the product is sent to the new production grade material silo.

[0041] In existing technologies, operators determine the cut-off point based on experience and quality inspection results. To prevent unqualified products from entering qualified material silos, a large margin is usually reserved for the cut-off time. At the same time, due to the long production process and large amount of material stored in the system, the switching of production grades will generate a lot of transition material, and the output of transition material varies greatly between batches.

[0042] like Figure 1 As shown, the present invention provides an automatic switching control method for polymer production grades, comprising:

[0043] Step S101: When it is determined that a production grade switching transition process has occurred, the mass ratio of the new production grade material in the product is calculated at each preset time interval. The production grade switching transition process is the process of switching from the old production grade raw material ratio to the new production grade raw material ratio during polymer production.

[0044] Specifically, polymer production, such as polycarbonate production, involves multiple processes, each with several pieces of equipment. After raw materials enter the polymer production line, they undergo multiple processes to ultimately output the product. The term "materials" refers to the discharged output of raw materials after passing through various processes in the polymer production line. The form of these materials may change in different processes and on different equipment. Materials include the raw materials entering the polymer production line, intermediate products in each process of the polymer flow, and the final output product.

[0045] A product designation is used to indicate the product being manufactured. Different products correspond to different product designations. Different products are made from raw materials with different proportions, therefore different product designations also correspond to different raw materials.

[0046] When it is determined that a production grade switching transition process has occurred, that is, when it is determined that the ratio of reaction raw materials has changed, step S101 is triggered. At each preset time interval, the mass ratio of the new production grade material in the product is calculated, and then step S102 is executed.

[0047] Step S102: Based on the mass ratio of the new production grade material in the product, determine whether the cut-off point requirements are met. The cut-off point includes the cut-off point for unqualified materials and the cut-off point for qualified materials. If the cut-off point requirement is met, prompt the user to switch the product from the qualified material silo of the old production grade to the unqualified material silo. If the cut-off point requirement is met, prompt the user to switch the product from the unqualified material silo to the qualified material silo of the new production grade.

[0048] The cut-off point includes both the cut-off point for non-conforming materials and the cut-off point for conforming materials. Therefore, the cut-off point requirements include requirements for both non-conforming and conforming materials. During the process of switching from the old production grade raw material ratio to the new production grade raw material ratio, due to the long production line, old production grade materials will remain in various processes and equipment on the production line. The new production grade materials will gradually replace the old production grade materials. Therefore, a mixture of new and old production grade materials will be generated. When the mixture fails to meet the quality requirements, i.e., when the cut-off point for non-conforming materials is met, the product should be moved to the non-conforming material silo. When the mixture meets the quality requirements of the new production grade, i.e., when the cut-off point for conforming materials is met, the product should be moved to the new production grade material silo.

[0049] This invention predicts the mass percentage of newly produced materials in the product and automatically determines whether the cut-off point requirements are met. If the requirements are met, it alerts the user to cut the material. This enables automatic detection of the production process, reduces excess material, decreases manual workload, and lowers the error rate. Finally, it reduces excess material generation through two methods: reducing system inventory and accurately predicting the cut-off point.

[0050] like Figure 2 The diagram shown is a flowchart of an automatic switching control method for polymer production grades according to an embodiment of the present invention, comprising:

[0051] Step S201: Calculate the start-up time based on the planned switching time for the production grade and the equipment liquid level drop time; calculate the linear region of viscosity-average molecular weight change during the production grade switching transition process; the planned switching time for the production grade is the planned time for switching the raw material ratio of the old production grade to the raw material ratio of the new production grade; the linear region of viscosity-average molecular weight change is the linear change region of the viscosity-average molecular weight in the product from the viscosity-average molecular weight of the old production grade product to the viscosity-average molecular weight of the new production grade product.

[0052] According to some embodiments, the calculation is performed before the production grade switch:

[0053] Enter the production grade switching time and target production grade according to the production plan, set the target value for low liquid level operation of key equipment and the liquid level raising and lowering speed, and click the "Parameter Input Complete" button after the input is completed.

[0054] The program starts at the time of input and the current load, and calculates the linear region of viscosity-average molecular weight.

[0055] If the current time reaches the program startup time, the operator will be prompted to start the program.

[0056] In one embodiment, the linear variation region is the minimum of the viscosity-average molecular weight of the old production grade product and the viscosity-average molecular weight of the new production grade product plus a preset upper limit to the maximum of the viscosity-average molecular weight of the old production grade product and the viscosity-average molecular weight of the new production grade product minus a preset lower limit.

[0057] Step S202: When the start-up time is reached, the liquid level of one or more first devices is lowered to the target liquid level corresponding to the device, and the raw material ratio of the reaction process is monitored. The liquid level drop time of the device is the maximum drop time required for the liquid level of multiple first devices to be lowered to the target liquid level corresponding to the device.

[0058] According to some embodiments, the production grade switching procedure runs as follows:

[0059] After receiving the program start command, the process of lowering the liquid level begins, specifically including:

[0060] Determine if the critical liquid level control loop is under PID control or Advanced Process Control (APC) control. If controllable, lower the liquid level of the first equipment, for example, lower the liquid level of equipment A. Specifically, the operator manually increases the load on the refining system. After confirming the load has reached the target value, lower the liquid level of the next first equipment, for example, the liquid level of equipment B. Specifically, set the upper and lower limits of the controlled variable of the liquid level APC according to the target value. If the actual liquid levels of the first equipment A and B drop to the target value, restore the load to the original load.

[0061] Step S203: If the raw material ratio changes, it is determined that a production grade switching transition process has occurred. The production grade switching transition process is the process of switching from the old production grade raw material ratio to the new production grade raw material ratio during polymer production. Steps S204 and S206 are executed respectively.

[0062] In some embodiments, the program continuously monitors the ratio of reaction raw materials. If the ratio of reaction raw materials is adjusted to a new production grade (target production grade), the replacement progress prediction program is initiated.

[0063] The grade switching process includes changing the raw material ratio, lowering the liquid level, changing the flash evaporation control mode, and shutting down the storage compartments. The method for changing the raw material ratio during the grade switching process utilizes existing technology. When it is detected that the reaction raw material ratio has been adjusted to the new production grade, a grade switching transition process is determined to have occurred, and the method of this embodiment is executed to perform the relevant operations of the grade switching process.

[0064] Step S204: Switch the polymer production control mode from viscosity control to concentration control.

[0065] In some embodiments, the flash control mode for polymer production is switched from viscosity control to concentration control.

[0066] In some embodiments, after initiating the replacement progress prediction program, a 30-minute timer is started. After 30 minutes, the PC liquid viscosity control is exited, and the PC liquid concentration control is further initiated. Since the PC concentration cannot be directly measured after flash evaporation, the concentration in this concentration control is calculated by a software instrument. The calculation formula is:

[0067] CI = (F in *C in ) / (F in -F out In the formula, CI represents the polymer solution concentration, F in Indicates feed flow rate, C in Indicates the feed polymer concentration, F out This indicates the impurity extraction flow rate. The polymer is preferably polycarbonate (PC).

[0068] Step S205: Lower the liquid level of one or more second devices to the target liquid level corresponding to the device. The second devices are located downstream of the first device in the polymer production process.

[0069] In some embodiments, the second device is downstream of the first device, and in the polymer production process, the discharge from the upstream device serves as the feed for the downstream device. Because the second device is located downstream, it does not need to prematurely lower the target liquid level.

[0070] In some embodiments, the first device and the second device are devices with a large quantity in the polymer production process, such as buffer tanks.

[0071] In some embodiments, the liquid level of the second device is lowered, for example, the liquid level of device C is lowered. Specifically, the PID control of the liquid level of the second device is set to automatic, and then the liquid level set value is gradually reduced at a set speed until the liquid level set value reaches the target value. If the actual liquid level of the second device reaches the target value, the production grade switching procedure enters a waiting mode.

[0072] Step S206: When it is determined that a production grade switching transition process has occurred, the mass percentage of the new production grade material in the discharge of each key equipment at time T in the polymer production process is calculated sequentially at preset time intervals ΔT:

[0073] X2 T =F1T △T(X1 T +X1 T-1 ) / (2V1L1+F1 T △T)+(2V1L1-F1 T △T) / (2V1L1+F1 T △T)X2 T-1 ,

[0074] Among them, X2 T F1 represents the mass percentage of newly produced grade material in the equipment discharge at time T. T Let X1 be the feed flow rate of the equipment at time T. T The mass percentage of newly produced grade material in the equipment feed at time T, V1 is the equipment volume, L1 is the current liquid level of the equipment at time T, and X1 is the mass percentage of newly produced grade material in the equipment feed at time T. T-1 The mass percentage of newly produced grade material in the equipment feed at time T-1, X2 T-1 Let T be the mass percentage of newly produced grade material in the equipment discharge at time T-1, where T is the current time, T-1 is the time when the mass percentage of newly produced grade material in the equipment discharge was last calculated, and ΔT is the time interval between time T and time T-1.

[0075] In some embodiments, after receiving the start signal, the replacement progress prediction program begins calculation, and the calculation formula for the replacement progress of each device is as follows:

[0076] X2 T =F1 T △T(X1 T +X1 T-1 ) / (2V1L1+F1 T △T)+(2V1L1-F1 T △T) / (2V1L1+F1 T △T)X2 T-1 ,

[0077] Among them, X2 T F1 represents the mass percentage of newly produced grade material in the equipment discharge at time T. T Let X1 be the feed flow rate of the equipment at time T. T The mass percentage of newly produced grade material in the equipment feed at time T, V1 is the equipment volume, L1 is the current liquid level of the equipment at time T, and X1 is the mass percentage of newly produced grade material in the equipment feed at time T. T-1 The mass percentage of newly produced grade material in the equipment feed at time T-1, X2 T-1 Let T be the mass percentage of newly produced grade material in the equipment discharge at time T-1, where T is the current time, T-1 is the time when the mass percentage of newly produced grade material in the equipment discharge was last calculated, and ΔT is the time interval between time T and time T-1.

[0078] The above formula is calculated sequentially for each key piece of equipment in the polymer production process. The calculated mass percentage of newly produced grade material in the equipment discharge at time T of the upstream equipment is multiplied by 2. T This will be represented by the mass percentage of newly produced grade material in the feed of downstream equipment at time T, multiplied by 1. T By calculating sequentially, the mass percentage of newly produced grade materials in the discharge of each key piece of equipment in the polymer production process can be obtained.

[0079] Step S207: The mass percentage of newly produced grade material in the discharge of key equipment outputting the product in the polymer production process is used as the mass percentage of the newly produced grade material in the product.

[0080] Step S208: Based on the mass percentage of the new production grade material in the product, determine whether the cut-off point requirements are met. The cut-off point includes the cut-off point for unqualified products and the cut-off point for qualified products.

[0081] In some embodiments, the cut-off point requirements include cut-off point requirements for unqualified warehouses and cut-off point requirements for qualified warehouses.

[0082] In one embodiment, determining whether the cut-off point requirement is met based on the mass percentage of the newly produced material in the product specifically includes:

[0083] Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product. If the predicted viscosity-average molecular weight is within the linear range of viscosity-average molecular weight change, then prompt the user to perform multiple viscosity-average molecular weight samplings on the current product.

[0084] Calculate the results of multiple viscosity-average molecular weight samplings, and calculate the slope of the viscosity-average molecular weight change.

[0085] Based on the sampling start time and the slope of the viscosity-average molecular weight change, the cut-off point time for reaching the viscosity-average molecular weight of the qualified warehouse is calculated. The cut-off point time includes the cut-off point time for the unqualified warehouse and the cut-off point time for the qualified warehouse. The viscosity-average molecular weight at the cut-off point includes the viscosity-average molecular weight of the unqualified warehouse and the viscosity-average molecular weight of the qualified warehouse. The viscosity-average molecular weight of the unqualified warehouse is the viscosity-average molecular weight of the old production brand product, and the viscosity-average molecular weight of the qualified warehouse is the viscosity-average molecular weight of the new production brand product.

[0086] Determine whether the current time has reached the cut-off point time.

[0087] In some embodiments, the transition process is predicted to enter the linear region of viscosity-average molecular weight based on the mass percentage of the new production grade material in the product.

[0088] Furthermore, the operator is reminded to take samples to measure the viscosity-average molecular weight, with a minimum of two reminders. Preferably, the reminders are given three times, all within the linear variation range of the viscosity-average molecular weight.

[0089] In some embodiments, the predicted viscosity-average molecular weight N of the current product is calculated based on the mass percentage of the new production grade material in the product. 总 =X 新 N 新 +(1-X 新 )N 旧 X 新 N represents the mass percentage of the newly produced material in the product. 新 The viscosity-average molecular weight (N) corresponding to the new production grade. 旧 This represents the viscosity-average molecular weight corresponding to the old production grade.

[0090] If the predicted viscosity-average molecular weight of the current product is within the linear variation range of viscosity-average molecular weight, and is lower than the viscosity-average molecular weight of the non-conforming warehouse, two or more samples can be taken consecutively. The non-conforming warehouse cut-off point time is calculated based on the viscosity-average molecular weight of the sampling points. Here, "the predicted viscosity-average molecular weight of the current product is lower than the viscosity-average molecular weight of the non-conforming warehouse" means: if the viscosity-average molecular weight of the non-conforming warehouse is less than the viscosity-average molecular weight of the conforming warehouse, then the predicted viscosity-average molecular weight of the previous product is higher than that of the non-conforming warehouse; if the viscosity-average molecular weight of the non-conforming warehouse is greater than that of the conforming warehouse, then the predicted viscosity-average molecular weight of the previous product is higher than that of the non-conforming warehouse. Before the non-conforming warehouse cut-off point, the sampling points are evenly distributed according to the viscosity-average molecular weight variation range.

[0091] If the predicted viscosity-average molecular weight of the current product is within the linear variation range of viscosity-average molecular weight, and if the predicted viscosity-average molecular weight of the current product is between the viscosity-average molecular weight of the unqualified compartment and the viscosity-average molecular weight of the qualified compartment, two or more samples can be taken consecutively. The time to cut the qualified compartment is calculated based on the viscosity-average molecular weight of the sampling points. Before the qualified compartment is cut, the sampling points are evenly distributed according to the variation range of viscosity-average molecular weight.

[0092] In some embodiments, taking three sampling points as an example, the slope of the viscosity-average molecular weight change is calculated based on the results of the three samplings. The calculation formula is as follows:

[0093] K=((N2-N1) / T1)+(N3-N2) / T2) / 2

[0094] In the formula: K is the slope of the viscosity-average molecular weight change, N1, N2, and N3 are the viscosity-average molecular weights of the three sampling points, and T1 and T2 are the time intervals between two sampling points.

[0095] In some embodiments, taking two sampling points as an example, the slope of the viscosity-average molecular weight change is calculated based on the results of three samplings. The calculation formula is as follows:

[0096] K = (N2 - N1) / T, where: K is the slope of the change in viscosity-average molecular weight, N1 and N2 are the viscosity-average molecular weights of the three sampling points, and T is the time interval between two sampling points.

[0097] In some embodiments, the cut-off point is the cut-off time point, which includes the cut-off time point for unqualified bins and the cut-off time point for qualified bins. Specifically, the time corresponding to the viscosity-average molecular weight of the cut-off bins is calculated. If the time reaches the cut-off time point for unqualified bins, it is determined that the cut-off point requirement for unqualified bins is met; if the time reaches the cut-off time point for qualified bins, it is determined that the cut-off point requirement for qualified bins is met.

[0098] In one embodiment, determining whether the cut-off point requirement is met based on the mass percentage of the newly produced material in the product specifically includes:

[0099] Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product, and determine whether the predicted viscosity-average molecular weight reaches the cut-off viscosity-average molecular weight. The cut-off viscosity-average molecular weight includes the cut-off unqualified silo viscosity-average molecular weight and the cut-off qualified silo viscosity-average molecular weight. The cut-off unqualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the old production grade product, and the cut-off qualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the new production grade product.

[0100] In some embodiments, the predicted viscosity-average molecular weight of the current product can be calculated directly based on the mass percentage of the newly produced grade material in the product, and then compared with the cut-off viscosity-average molecular weight. The cut-off point is the cut-off adhesion molecular weight, including the cut-off viscosity-average molecular weight of unqualified silos and the cut-off viscosity-average molecular weight of qualified silos.

[0101] If the predicted viscosity-average molecular weight of the current product reaches the viscosity-average molecular weight of the unqualified storage point, then it is determined that the requirement to cut the unqualified storage point is met; if the predicted viscosity-average molecular weight of the current product reaches the viscosity-average molecular weight of the qualified storage point, then it is determined that the requirement to cut the qualified storage point is met.

[0102] Specifically, if the viscosity-average molecular weight of the unqualified storage point is less than that of the qualified storage point, then if the predicted viscosity-average molecular weight of the current product is greater than or equal to the viscosity-average molecular weight of the unqualified storage point, the requirement to remove the unqualified storage point is met; if the predicted viscosity-average molecular weight of the current product is greater than or equal to the viscosity-average molecular weight of the qualified storage point, the requirement to remove the qualified storage point is met.

[0103] If the viscosity-average molecular weight of the unqualified storage point is greater than that of the qualified storage point, then if the predicted viscosity-average molecular weight of the current product is less than or equal to the viscosity-average molecular weight of the unqualified storage point, then the requirement to remove the unqualified storage point is met; if the predicted viscosity-average molecular weight of the current product is less than or equal to the viscosity-average molecular weight of the qualified storage point, then the requirement to remove the qualified storage point is met.

[0104] Step S209: When the requirement to cut the non-conforming warehouse point is met, a prompt is made to switch the product from the old production grade qualified warehouse to the non-conforming warehouse. When the requirement to cut the qualified warehouse point is met, a prompt is made to switch the product from the non-conforming warehouse to the new production grade qualified warehouse.

[0105] In some embodiments, when the requirement to cut the non-conforming warehouse point is met, a reminder is triggered to the operator to cut the product from the conforming warehouse to the non-conforming warehouse (or transition warehouse), and when the requirement to cut the conforming warehouse point is met, a reminder is triggered to the operator to cut the product from the transition warehouse to the conforming warehouse.

[0106] In some embodiments, system recovery is also included:

[0107] The system restores part or all of the liquid level in the first equipment by setting the high and low limits of the controlled variable (APC) for the liquid level. Further, the system restores the liquid level in the second equipment by setting the PID controller for the second equipment to automatic and gradually increasing the PID setpoint according to the set recovery target and recovery speed. If the actual liquid level in the second equipment reaches the target value, the system restoration is complete, and production of the new product grade begins.

[0108] In some embodiments, the production grade switching procedure further includes:

[0109] If, during the process of lowering the liquid level, the actual liquid level of the first / second device is lower than the target value, or the difference between the liquid level of the first / second device and the interface level is too small, an alarm will be issued to remind the operator to pay attention.

[0110] If the PC liquid viscosity remains within the target viscosity range for a preset time, such as 3 minutes, then the mass percentage of the newly produced grade is determined to be 100%. Further, the PC liquid concentration control is switched to viscosity control.

[0111] This embodiment automatically adjusts the liquid levels of key equipment based on the production plan and target liquid level, ensuring the system operates at a low liquid level before production grade switching. Since the liquids in the equipment of each process are mixed transitional liquids during the switching process, lowering the liquid level reduces the amount of defective products generated. The system automatically monitors the reaction raw material ratio, determines the start of the replacement progress prediction after production grade switching, and reminds the operator to take multiple samples within the linear range of viscosity-average molecular weight change. The viscosity-average molecular weight change trend is fitted based on the sampling results. The time to reach the two cut-off points is calculated based on the fitted curve, and the operator is reminded to perform the cut-off operation. After the cut-off is completed, the system returns to high liquid level operation. Finally, this embodiment automates the production grade switching operation, reduces the generation of transitional materials, reduces manual operation, reduces operational errors and differences in the quantity of transitional materials due to individual experience, improves the efficiency of production grade switching, and reduces the cost of production grade switching.

[0112] like Figure 3 The figure shown is a preferred embodiment of the present invention, which describes an automatic switching control method for polymer production grades. The polymer being produced is polycarbonate. The method includes:

[0113] Step S301: Set parameters such as target production grade, planned production grade switching time, target liquid level of key equipment, and liquid level adjustment speed;

[0114] Step S302: Calculate the program start time and the linear region of viscosity-average molecular weight;

[0115] Step S303: If the start time arrives, start the production grade switching procedure;

[0116] Step S304: Lower the liquid levels in equipment A and B to the target value;

[0117] Step S305: Simultaneously, monitor the raw material ratio of the reaction process;

[0118] Step S306: If a production grade change occurs, the PC liquid control mode is switched from viscosity control to concentration control;

[0119] Step S307: Simultaneously, start the replacement progress prediction program;

[0120] Step S308: Lower the liquid level C in the equipment to the target value;

[0121] Step S309: Predict the replacement progress to reach the sampling point and remind the user to take samples;

[0122] Step S310: Calculate the cut-off point based on the sampling data;

[0123] Step S311: If the stop-loss point is reached, notify the trader to close the position.

[0124] Step S312: After the chamber is cut off, restore the liquid levels in equipment B and C;

[0125] Step S313: During the switching process, monitor the viscosity value of the PC liquid. If it stabilizes within the target viscosity range within 3 minutes, the PC liquid control mode is switched from concentration control to viscosity control.

[0126] This embodiment is based on the DeltaV digital automation system. It uses a time-series function chart to design automatic control logic, automatically collects process parameters such as system liquid level and flow rate, and automatically adjusts the liquid level of each key equipment according to preset logic. It calculates the production grade switching progress in real time based on flow rate and liquid level, and predicts the cut-off point based on sampling results, thereby realizing the automated control of the production grade switching process.

[0127] Specifically, first, the expected production grade switching time, target production grade, low liquid level operation target for key equipment, and liquid level adjustment rate are set. Then, the program start-up time is calculated based on the input parameters, and the viscosity-average molecular weight linear region is defined. In this embodiment, the formula for calculating the program start-up time in step S302 is as follows:

[0128] ts = tc - L / V

[0129] In the formula, ts and tc are the program start time and the planned production grade switching time, respectively. L and V represent the target liquid level and the liquid level reduction speed, respectively. Since equipment A has the largest volume and the liquid level reduction speed is the slowest, the start time calculated by equipment A is taken as the program start time.

[0130] Simultaneously, the linear region, cut-off point, and recommended sampling points for the viscosity-average molecular weight change during this production grade transition process are calculated. The linear region is the typical viscosity-average molecular weight ±100. For example, if the goal of this production grade transition is to change the product's viscosity-average molecular weight from 20000±200 to 25000±200, then the linear region for this transition is 20100-24900. The cut-off point is the viscosity-average molecular weight boundary corresponding to each production grade. Here, 20000 is the viscosity-average molecular weight of the old production grade, and 25000 is the viscosity-average molecular weight of the new production grade. +200 is the value, and -200 is the lower limit. Recommended sampling points are set in the linear region before the cut-off point for qualified or unqualified products. The linear region before the cut-off point for unqualified products is divided into four equal parts to obtain three sampling points for determining the cut-off point for unqualified products. The linear region before the cut-off point for qualified products is also divided into four equal parts to obtain three sampling points for determining the cut-off point for qualified products.

[0131] In step S303, when the current time arrives, the program is started. When the time arrives, the operator is reminded to click the "Start" button. The reminder can be issued through pop-up reminders, sound and light alarms, or other means.

[0132] In step S304, the specific implementation method for lowering the liquid levels of equipment A and B to the target value is as follows: The operator is reminded to increase the load to lower the liquid level of equipment A. After confirming the load increase, the liquid level of equipment B is lowered, and the lower limit of the APC (Automatic Level Control) for equipment B is set to the target liquid level value. Once it is determined that the liquid levels of equipment A and B have reached the target value, the load is restored, and then the production grade switching judgment step is initiated.

[0133] The step S305, which involves monitoring the reaction process and adjusting the raw material ratio, specifically includes:

[0134] Since different reactant ratios correspond to different production grades, the ratio of the two key reactants is calculated to determine the current production grade. The current production grade is then compared with the production grade from the previous 5 seconds. If they are different, it indicates that the production grade has been switched. If the production grade has been switched, steps S306 and S307 are executed.

[0135] In step S306, because PC solutions of the same concentration from different production brands have different viscosities, viscosity control of the PC concentration cannot be used during the transition process. Instead, concentration control must be performed directly using a concentration instrument. Therefore, the flash evaporation of APC switches from viscosity control to concentration control. The concentration instrument calculation formula is as follows:

[0136] CI = (F in *C in ) / (F in -F out In the formula, CI represents the concentration of PC solution, F in Indicates feed flow rate, C in Indicates the concentration of PC and F in the feed. out This indicates the flow rate of impurities extracted.

[0137] The PC liquid control mode switching process includes:

[0138] ① Remove the controlled and manipulated variables of viscosity APC;

[0139] ②The original controlled variable was controlled by PID;

[0140] ③ Set the upper and lower limits of the controlled variable for concentration APC;

[0141] ④ The controlled and manipulated variables of APC concentration.

[0142] Step S308 involves lowering the liquid level of device C to the target value by changing the set value of the liquid level control PID at the required speed until the actual liquid level reaches the target value.

[0143] The displacement progress prediction procedure described in step S307 establishes a fully mixed-flow model for key equipment in the reaction and refining processes, based on the formula:

[0144] X2T =F1 T △T(X1 T +X1 T-1 ) / (2V1L1+F1 T △T)+(2V1L1-F1 T △T) / (2V1L1+F1 T △T)X2 T-1

[0145] In the formula, X2 T F1 T X1 T V1, L1, X1 T-1 X2 T-1 ΔT and ΔT represent the following parameters: the mass percentage of newly produced grades in the equipment discharge at time T, the feed flow rate, the mass percentage of newly produced grades in the feed, the equipment volume, the current liquid level, the mass percentage of newly produced grades in the feed at time T-1, the mass percentage of newly produced grades in the discharge at time T-1, and the calculation time interval, respectively.

[0146] Step S310 involves calculating the cut-off point by inputting the sampling results to a specified location on the screen. Since all sampling points are located within the linear variation region of viscosity-average molecular weight, the slope of the viscosity-average molecular weight change can be calculated using the following formula:

[0147] K=((N2-N1) / T1)+(N3-N2) / T2) / 2

[0148] In the formula: K is the slope of the viscosity-average molecular weight change, N1, N2, and N3 are the viscosity-average molecular weights at the three sampling points, and T1 and T2 are the time intervals between two sampling points. Then, the cut-off point time can be calculated based on the starting time and the molecular weight at the cut-off point. As an example, if the first sampling point time is 0, the viscosity-average molecular weight is 30000, the calculated molecular weight change slope is -500 / h, and the cut-off molecular weight is 25000, then the cut-off point time is 10.

[0149] After switching to the qualified storage compartment, the replacement process is complete, and the system recovery procedure begins:

[0150] Step S312 is the reverse operation of steps S304 and S308.

[0151] In step S313, the PC liquid control mode is switched to viscosity control. During the replacement process, the viscosity monitoring module continuously reads the viscosity data. If the viscosity remains stable within the target viscosity range for a period of time, the PC liquid control mode is switched from concentration control to viscosity control.

[0152] like Figure 4 The diagram shown is a hardware structure schematic of an electronic device according to the present invention, comprising:

[0153] At least one processor 401; and,

[0154] A memory 402 is communicatively connected to at least one of the processors 401; wherein,

[0155] The memory 402 stores instructions that can be executed by at least one of the processors to enable the at least one processor to perform the polymer production grade automatic switching control method as described above.

[0156] Figure 4 Take a processor 401 as an example.

[0157] The electronic device may also include an input device 403 and a display device 404.

[0158] The processor 401, memory 402, input device 403 and display device 404 can be connected by a bus or other means. The figure shows an example of connection by bus.

[0159] Memory 402, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the polymer production grade automatic switching control method in the embodiments of this application, for example, Figure 1 , Figure 2 The method flow is shown. The processor 401 executes various functional applications and data processing by running non-volatile software programs, instructions, and modules stored in the memory 402, thereby realizing the automatic switching control method for polymer production grades in the above embodiments.

[0160] Memory 402 may include a program storage area and a data storage area. The program storage area may store an operating system and an application program required for at least one function. The data storage area may store data created based on the use of the automatic switching control method for polymer production grades. Furthermore, memory 402 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 402 may optionally include memory remotely located relative to processor 401, and this remote memory may be connected via a network to the apparatus performing the automatic switching control method for polymer production grades. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0161] The input device 403 can receive user clicks and generate signal inputs related to user settings and function control of the automatic switching control method for polymer production grades. The display device 404 may include a display screen or other display equipment.

[0162] When one or more modules are stored in the memory 402 and are run by one or more processors 401, the automatic switching control method for polymer production grades in any of the above method embodiments is executed.

[0163] This invention predicts the mass percentage of newly produced materials in the product and automatically determines whether the cut-off point requirements are met. If the requirements are met, it alerts the user to cut the material. This enables automatic detection of the production process, reduces excess material, decreases manual workload, and lowers the error rate. Finally, it reduces excess material generation through two methods: reducing system inventory and accurately predicting the cut-off point.

[0164] One embodiment of the present invention provides a storage medium that stores computer instructions, which, when executed by a computer, are used to perform all steps of the polymer production grade automatic switching control method described above.

[0165] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for automatic switching control of polymer production grades, characterized in that, include: When it is determined that a production grade switching transition process has occurred, the mass ratio of the new production grade material in the product is calculated at each preset time interval. The production grade switching transition process is the process of switching from the old production grade raw material ratio to the new production grade raw material ratio during polymer production. Calculate the linear region of viscosity-average molecular weight change during the transition process of switching production grades. The linear region of viscosity-average molecular weight change is the region in which the viscosity-average molecular weight of the product changes linearly from the viscosity-average molecular weight of the old production grade product to the viscosity-average molecular weight of the new production grade product. Based on the mass percentage of the new production grade material in the product, it is determined whether the cut-off point requirements are met. These cut-off points include cut-off points for non-conforming materials and cut-off points for conforming materials. If the cut-off point requirement is met, a notification is sent to switch the product from the old production grade conforming material silo to the non-conforming material silo. If the cut-off point requirement is met, a notification is sent to switch the product from the non-conforming material silo to the new production grade conforming material silo. The determination of whether the cut-off point requirements are met based on the mass percentage of the new production grade material in the product specifically includes: Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product. If the predicted viscosity-average molecular weight is within the linear range of viscosity-average molecular weight change, then prompt the user to perform multiple viscosity-average molecular weight samplings on the current product. Calculate the results of multiple viscosity-average molecular weight samplings, and calculate the slope of the viscosity-average molecular weight change. Based on the sampling start time and the slope of the viscosity-average molecular weight change, the cut-off point time for reaching the viscosity-average molecular weight of the qualified warehouse is calculated. The cut-off point time includes the cut-off point time for the unqualified warehouse and the cut-off point time for the qualified warehouse. The viscosity-average molecular weight at the cut-off point includes the viscosity-average molecular weight of the unqualified warehouse and the viscosity-average molecular weight of the qualified warehouse. The viscosity-average molecular weight of the unqualified warehouse is the viscosity-average molecular weight of the old production brand product, and the viscosity-average molecular weight of the qualified warehouse is the viscosity-average molecular weight of the new production brand product. Determine whether the current time has reached the cut-off point time.

2. The automatic switching control method for polymer production grades according to claim 1, characterized in that, Before calculating the mass percentage of the new production grade material in the product at preset time intervals when a production grade switching transition process is determined to have occurred, the method further includes: The start-up time is calculated based on the planned switching time for production grades and the equipment liquid level drop time. The planned switching time for production grades is the planned time to switch the old production grade raw material ratio to the new production grade raw material ratio. When the start-up time is reached, the liquid level of one or more first devices is lowered to the target liquid level corresponding to that device. The liquid level drop time of the device is the maximum drop time required for the liquid level of the multiple first devices to drop to the target liquid level corresponding to that device.

3. The automatic switching control method for polymer production grades according to claim 2, characterized in that, Also includes: When the start-up time is reached, monitor the raw material ratio of the reaction process; If the raw material ratio changes, it is determined that a production grade switching transition process has occurred; Switch the polymer production control mode from viscosity control to concentration control; The liquid level of one or more second devices is lowered to the target liquid level corresponding to the device, the second devices being located downstream of the first device in the polymer production process.

4. The automatic switching control method for polymer production grades according to claim 1, characterized in that, The calculation of the mass percentage of newly produced grade materials in the product at each preset time interval specifically includes: At each preset time interval ΔT, the mass percentage of newly produced grade material in the discharge of each key equipment at time T in the polymer production process is calculated sequentially: X2 T =F1 T △T(X1 T +X1 T-1 ) / (2V1L1+F1 T △T)+(2V1L1-F1 T △T) / (2V1L1+F1 T △T)X2 T-1 , where X2 T F1 represents the mass percentage of newly produced grade material in the equipment discharge at time T. T Let X1 be the feed flow rate of the equipment at time T. T The mass percentage of newly produced grade material in the equipment feed at time T, V1 is the equipment volume, L1 is the current liquid level of the equipment at time T, and X1 is the mass percentage of newly produced grade material in the equipment feed at time T. T-1 The mass percentage of newly produced grade material in the equipment feed at time T-1, X2 T-1 The mass percentage of newly produced grade material in the equipment discharge at time T-1, where T is the current time, T-1 is the time when the mass percentage of newly produced grade material in the equipment discharge was last calculated, and △T is the time interval between time T and time T-1. The mass percentage of newly produced grade materials in the discharge of key equipment outputting the product in the polymer production process is used as the mass percentage of newly produced grade materials in the product.

5. The automatic switching control method for polymer production grades according to claim 1, characterized in that, The linear variation region is the minimum of the viscosity-average molecular weight of the old production brand and the viscosity-average molecular weight of the new production brand plus a preset upper limit, up to the maximum of the viscosity-average molecular weight of the old production brand and the viscosity-average molecular weight of the new production brand minus a preset lower limit.

6. The automatic switching control method for polymer production grades according to claim 1, characterized in that, The determination of whether the cut-off point requirement is met based on the mass percentage of the newly produced material in the product specifically includes: Based on the mass percentage of the new production grade material in the product, calculate the predicted viscosity-average molecular weight of the current product, and determine whether the predicted viscosity-average molecular weight reaches the cut-off viscosity-average molecular weight. The cut-off viscosity-average molecular weight includes the cut-off unqualified silo viscosity-average molecular weight and the cut-off qualified silo viscosity-average molecular weight. The cut-off unqualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the old production grade product, and the cut-off qualified silo viscosity-average molecular weight is the viscosity-average molecular weight of the new production grade product.

7. An electronic device, characterized in that, include: At least one processor; as well as, A memory communicatively connected to at least one of the processors; wherein, The memory stores instructions executable by at least one of the processors, which enable the at least one processor to perform the automatic switching control method for polymer production grades as described in any one of claims 1 to 6.

8. A storage medium, characterized in that, The storage medium stores computer instructions, which, when executed by the computer, are used to perform all steps of the automatic switching control method for polymer production grades as described in any one of claims 1 to 6.

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