Stainless steel steelmaking scheduling system

Abstract

The invention relates to the field of stainless steel smelting. The invention discloses a stainless steel making scheduling system, which intuitively simulates field production and scheduling conditions, defines the specific production process of a pre-solution of each furnace through interval variables, and comprises the following steps of: firstly, creating the interval variable of the sum of preparation time, production time and transfer time of each alloy melting furnace station; secondly, creating a preparation + production time interval variable between each alloy melting furnace station and an adjacent alloy melting furnace station, establishing a series of production non-overlapping constraints of the alloy melting furnace stations, adopting a constraint planning modeling method based on the interval variables to complete AOD preorder process scheduling modeling, solving an AOD preorder process scheduling modeling model, and establishing a production non-overlapping series of alloy melting furnace station production non-overlapping series of alloy melting furnace station production non-overlapping series of alloy melting furnace station production non-overlapping series of alloy melting furnace station production non-overlapping series constraints; and if no feasible solution exists, returning a no-solution prompt, adjusting model input, then carrying out solution again, generating a plan result file, namely model output, after successful solution is finished, and carrying out stainless steel AOD smelting pre-solution scheduling generation according to the plan result file.

Description

Technical Field

[0001] The invention relates to the field of stainless steel smelting. Background Art

[0002] The stainless steel steelmaking scheduling system is responsible for receiving the daily production plan and converting it into a feasible furnace plan to maximize output, optimize costs and achieve just-in-time production. However, the stainless steel production process faces the problems of many processes and long smelting time, making production organization difficult. The variety structure and material structure of stainless steel are complex and changeable. The materials used in the alloy melting furnace smelting process are not universal, and there are large differences in smelting time. Due to inaccurate calculation of production scheduling time, the residence time of the pre-melt in the ladle is different. The alloy melting furnace and AOD production rhythm do not match, resulting in the pre-melt staying in the ladle for a long time, causing energy waste and increased smelting costs, or the pre-melt tapping time is delayed, and the AOD process frequently waits for the pre-melt, resulting in low production efficiency.

[0003] The process mode of stainless steel production based on scrap steel and alloys mainly relies on electric furnaces and alloy melting furnaces to convert solids into liquid pre-solutions, and then add AOD through ladles for production. The alloy melting furnace has a small tonnage and the electric furnace smelting cost is high, so alloy melting furnaces should be used first. In the production process, a variety of production process routes such as high silicon, electric furnace one-to-one, medium desulfurization and three desulfurization are summarized. From the first tank of pre-solution from the alloy melting furnace to the addition of AOD, the interval in between is very long, and production relies on intercom command at this stage. Due to the lack of intelligent means and the complexity of stainless steel smelting, the process time span is long, and the production organization of stainless steel lines is very poor. As the solid-to-liquid process of stainless steel smelting, due to many constraints, it is difficult for dispatchers to schedule production. The overall command is manual intercom, and it is difficult to ensure production punctuality and maximize the number of smelting furnaces per day. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the multi-objective, multi-constraint, multi-interference and other characteristics of stainless steel AOD smelting pre-solution, how to provide a stainless steel steelmaking scheduling system to achieve planned optimized production scheduling, real-time dynamic adjustment of the process and maximization of the number of daily smelting furnaces.

[0005] The technical scheme adopted by the present invention is: a stainless steel steelmaking scheduling system, which intuitively simulates on-site production and scheduling conditions, defines the specific production process of each furnace pre-solution by interval variables, first creates an interval variable of the sum of the preparation time, production time and transfer time of each alloy melting furnace station, and then creates an interval variable of the preparation + production time between each alloy melting furnace station and the adjacent alloy melting furnace station, establishes a series of constraints on the non-overlapping production of the alloy melting furnace station, and adopts a constraint programming modeling method based on interval variables to complete the AOD pre-process scheduling modeling, solves the AOD pre-process scheduling modeling model, and returns a no-solution prompt if there is no feasible solution, adjusts the model input and solves again, generates a plan result file, i.e., a model output, after the successful solution, generates the stainless steel AOD smelting pre-solution scheduling according to the plan result file. The interval variable for creating the sum of the preparation time, production time, and transfer time of each alloy melting furnace station is, according to the number of AOD furnaces specified for each smelting mode, the AOD plan to be scheduled, the preparation time of different smelting modes of each steel grade at each station, the production time, and the transfer time data between different stations, check whether each station is under maintenance and whether there is an unfinished plan. The end time of the unfinished plan is the earliest start time of the subsequent planned production scheduling, and check the assigned quantity requirements of each smelting mode at the same time; check the information related to the AOD plan to be scheduled, including the plan number, steel grade, AOD station code, AOD plan start time, and determine whether the converter / electric furnace plan has been arranged. For the converter / electric furnace plan, update the plan start and end time based on whether there is actual performance; check the smelting modes that can be used for each steel grade and the preparation time and production time of each steel grade under different smelting modes at different stations, and check the transfer time between each equipment, and then establish an interval variable for the sum of the preparation time, production time, and transfer time of each alloy melting furnace station corresponding to different AOD furnace numbers, AOD plans to be scheduled, steel types, stations, and smelting modes.

[0006] The detailed process of AOD pre-process scheduling modeling is as follows:

[0007] The input of the AOD pre-process scheduling model is all alloy melting furnace plans to be scheduled, the available smelting modes of the corresponding steel grades, preparation time, production time and the transfer time between the upper and lower processes. The model output is the smelting mode of all alloy melting furnace plans, the start and end time of the designated workstations and plans;

[0008] The model objective function is defined as minimizing the difference between the start time of each AOD and the end time of its corresponding alloy melting furnace plan:

[0009]

[0010] Where nbAod is the number of AOD plans, Smelti is the available smelting mode for the steel grade corresponding to the i-th AOD plan, nbZ is the number of alloy melting furnace stations, TsAod i is the planned production start time of the i-th AOD plan, EndOF(Zi, j, k) is the end time of the obtained interval variable, PresenceOf is the existence state of the obtained interval variable, j is the workstation, k is the smelting mode, and i=1...nbAod,j=1...nbZ,k∈Smelt i ;

[0011] Define interval variables. The length of any interval variable is preparation time + production time + transmission time. Whether it exists is determined by the model.

[0012]

[0013] Among them, optional represents whether the interval variable exists. is the preparation time of the steel grade corresponding to the i-th AOD plan at workstation j and smelting mode k, is the production time of the steel type corresponding to the i-th AOD plan at station j and smelting mode k, move da，db is the transportation time from device da to device db;

[0014] For a plan number indicating a pre-scheduled converter or electric furnace plan, if an alloy melting furnace plan is to be scheduled, the end time of the alloy melting furnace must be earlier than the production end time of the pre-scheduled converter or electric furnace plan;

[0015]

[0016] Among them, Z i，j，k is the interval variable of the alloy melting furnace plan, TeBE i When the ith AOD plan schedules the converter / electric furnace plan, it indicates the planned production end time of the converter / electric furnace. dev∈{E, B} indicates that this constraint exists only when the destination device of the alloy melting furnace is an electric furnace or a converter. E is the converter, B is the electric furnace, and EndOf is used to obtain the end time of the interval variable.

[0017] For the plan number without pre-arranged converter or electric furnace plan, if the alloy melting furnace plan is to be arranged, the end time of the alloy melting furnace must be earlier than the AOD planned production start time;

[0018]

[0019] in, This constraint exists when there is no pre-arranged alloy melting furnace plan for the electric furnace or converter before its corresponding AOD;

[0020] The interval variables of any alloy melting furnace station do not overlap, and the production process times of all plans on it do not overlap;

[0021]

[0022] Construct a non-overlapping constraint on the dual-station production tasks of any alloy melting furnace, that is, the preparation time and production time do not overlap;

[0023]

[0024] IfThen(PresenceOf(Z i，j，k ), StartOf(temp i，j，k )=StartOf(Z i，j，k )) (8)

[0025]

[0026] Among them, PresenceOf is used to obtain the existence status of interval variables. represents the set of interval variables of all plans on the alloy melting furnace station j, lntervalVar is used to define interval variables, tempi.j,k represents the production process interval variable including preparation time and production time, The interval variable temp does not allow overlap i，j，k A collection of IfThen is used to define causal constraints, NoOverlap is used to specify interval variables that do not allow overlap, and StartOf is used to obtain the start time of the interval variable;

[0027] Define model assignment constraints: any plan can only be produced using one smelting mode; the interval variable corresponding to the three-desulfurization smelting mode cannot exist; if the plan number cannot be produced using a certain smelting mode, the corresponding interval variable cannot exist either; let the number of times a certain smelting mode is selected by the model assignment be equal to the number of furnaces corresponding to the smelting mode set by the planner;

[0028]

[0029] Among them, ProcMode i is a set of Boolean variables that record all optional smelting modes of the i-th AOD plan, x is a Boolean variable, Z i，j，k is the interval variable of the alloy melting furnace plan, nbZ is the number of alloy melting furnace stations, Ndev k is the number of alloy melting furnace stations that can be selected by smelting mode k. ExprArray is used to define expression arrays, BoolVar is used to define Boolean variables, and PresenceOf is used to obtain the existence status of interval variables;

[0030] Define the number constraints of smelting modes, so that the interval variable assigned by the model to select any smelting mode multiplied by the number of alloy melting furnaces required for the corresponding smelting mode is equal to the parameter set by the planner;

[0031]

[0032] k=Type, Type∈{Z, ZZ, ZZZ}

[0033] Sum(Modeused Type )=N Type *C Type (16)

[0034] Among them, Modeused Type It is an array that records the total number of alloy melting furnaces used under the smelting mode type Type. i，j，k is the interval variable of the alloy melting furnace plan, nbAod is the number of AOD plans, nbZ is the number of alloy melting furnace stations, N Type It is the constant of the number of furnaces used by the smelting mode type Type set by the planner, C Type It is a constant for the number of alloy melting furnaces required by the smelting mode type Type. ExprArray is used to define the expression array, and PresenceOf is used to obtain the existence status of the interval variable.

[0035] The beneficial effects of the present invention are: on the one hand, a specific pre-solution equipment operation plan can be generated according to the continuous casting production plan, process requirements and equipment capacity to guide production. On the other hand, the operation execution status and execution deviation can be timely grasped by obtaining production performance and abnormal working conditions in real time. When the deviation is large, the operation plan can be dynamically adjusted in real time to achieve dynamic scheduling.

[0036] The present invention automatically recommends different pre-solution process routes through a model, and comprehensively considers both cost and efficiency in the recommendation process. When selecting the pre-solution process route for each furnace of steel, priority is given to ensuring the production rhythm of AOD, maximizing the production capacity of the alloy melting furnace, and considering the number of smelting furnaces of the electric furnace. Under the premise of meeting the AOD production efficiency, the electric furnace smelting is used as little as possible. The model receives the AOD production plan, automatically recommends the furnace plan of the pre-solution, and produces a real-time Gantt chart. The present invention automatically generates a pre-solution furnace plan by receiving the AOD real-time plan, providing production personnel with a practical Gantt chart plan, realizing scientific planning before production of the pre-solution, and accurate tracking after production, laying the foundation for improving quality and efficiency. DETAILED DESCRIPTION

[0037] The present invention provides a just-in-time production that realizes full-process tracking and maximizes output through a scheduling system in the face of problems such as difficulty in scheduling alloy melting furnaces, disconnection from AOD production, long unplanned waiting time for steel, and low production efficiency in stainless steel smelting production. By adopting a constraint programming model based on interval variables, the planner specifies the process of AOD predecessor equipment under several smelting modes, and the model decides which smelting method to use for each AOD predecessor process (there are optional smelting mode restrictions for the predecessor process), as well as assigning specific workstations and times. When the production plan is adjusted, the dispatcher is allowed to manually adjust the steel type and standard smelting time of each alloy melting furnace.

[0038] The present invention adopts a constraint programming modeling method based on interval variables. According to the intuitive simulation of on-site production and scheduling, the specific production process of each furnace pre-solution is defined through interval variables. In order to achieve the actual production restrictions of adjacent alloy melting furnace stations, that is, the preparation + production time of all furnace plans produced at two stations are not allowed to overlap, a series of non-overlapping constraints on the production of alloy melting furnace stations are established. First, an interval variable of the preparation + production + transfer time of each alloy melting furnace plan is created, and then an interval variable of the preparation + production time corresponding to it is created, and the corresponding relationship between the two interval variables is established through the method provided by the constraint programming optimization algorithm. The non-overlapping constraint of the preparation + production time interval variable between adjacent station furnaces is set to meet the production restriction.

[0039] A general rule for model solution is established. For the planned production sequence of a certain alloy melting furnace station, the planned start time of the furnace with an earlier start time for the subsequent process must be earlier than that of the alloy melting furnace station. This rule has a certain effect of speeding up the model solution.

[0040] On this basis, in order to achieve the constraint propagation effect in the CP model, that is, if a certain constraint is not satisfied, some other related constraints must also be not satisfied. Boolean variables are coupled in some constraints, and the values ​​of the Boolean variables can be mapped to the values ​​when the constraints are satisfied, so as to achieve the effect of efficient model solving.

[0041] Using the constraint programming model, the specific implementation steps are as follows:

[0042] First, the input data of the model is sorted out, mainly including the number of AOD furnaces for each smelting mode, data related to the AOD plan to be scheduled, preparation time for different smelting modes of each steel grade at each station, production time, transfer time between different stations and other parameters. Then the data is processed according to the following steps:

[0043] Check whether each workstation is under maintenance and whether there are any unfinished plans. The end time of the unfinished plan is the earliest start time of the subsequent production schedule. At the same time, check the assigned quantity requirements of each smelting mode.

[0044] Check the information related to the AOD plan, including the plan number, steel type, AOD station code, and AOD plan start time. At the same time, determine whether the converter / electric furnace plan has been arranged. For plans that have been arranged for the converter / electric furnace, update the plan start and end times based on whether there is actual performance.

[0045] Check the available smelting modes for each steel grade and the preparation time and production time for each steel grade under different smelting modes at different workstations, and also check the transfer time between each equipment.

[0046] Once the input data file has been processed, follow these steps to build and solve the model:

[0047] Check whether the number of plans that can be assigned to each mode in the input data is less than the specified number entered by the system. If the number is insufficient, an error prompt will be returned;

[0048] Create interval variables of constraint programming model according to three indexes: steel type, work station and smelting mode, and list all available smelting modes according to plan number and steel type;

[0049] Add the assigned quantity constraints for each mode according to the parameter values ​​of each mode specified by the system;

[0050] Arrange the constraints of adjacent stations in the alloy melting furnace and the constraints of no conflict in the arbitrary processing time and furnace of each station;

[0051] Finally, minimizing the time difference between the preceding process and the AOD station is set as the objective function.

[0052] Smelting mode code details

[0053] Smelting code Specific description Workstation Assignment 2 EAF+IF (one-to-one) Z 3 High silicon (two to one) ZZ 4 Three Take-offs none 6 BOF+IF(one to one) Z

[0054] Detailed explanation of model symbols and formulas

[0055]

[0056]

[0057] A stainless steel steelmaking scheduling system intuitively simulates on-site production and scheduling conditions, defines the specific production process of each furnace pre-solution by interval variables, firstly creates an interval variable of the sum of the preparation time, production time and transfer time of each alloy melting furnace station, then creates an interval variable of the preparation + production time between each alloy melting furnace station and the adjacent alloy melting furnace station, establishes a series of constraints for non-overlapping production of alloy melting furnace stations, adopts a constraint programming modeling method based on interval variables to complete AOD pre-process scheduling modeling, solves the AOD pre-process scheduling modeling model, returns a no solution prompt if there is no feasible solution, adjusts the model input and solves again, generates a plan result file, i.e., model output, after successful solution, generates stainless steel AOD smelting pre-solution scheduling according to the plan result file.

[0058] The interval variable for creating the sum of the preparation time, production time, and transfer time of each alloy melting furnace station is, according to the number of AOD furnaces specified for each smelting mode, the AOD plan to be scheduled, the preparation time of different smelting modes of each steel grade at each station, the production time, and the transfer time data between different stations, check whether each station is under maintenance and whether there is an unfinished plan. The end time of the unfinished plan is the earliest start time of the subsequent planned production scheduling, and check the assigned quantity requirements of each smelting mode at the same time; check the information related to the AOD plan to be scheduled, including the plan number, steel grade, AOD station code, AOD plan start time, and determine whether the converter / electric furnace plan has been arranged. For the converter / electric furnace plan, update the plan start and end time based on whether there is actual performance; check the smelting modes that can be used for each steel grade and the preparation time and production time of each steel grade under different smelting modes at different stations, and check the transfer time between each equipment, and then establish an interval variable for the sum of the preparation time, production time, and transfer time of each alloy melting furnace station corresponding to different AOD furnace numbers, AOD plans to be scheduled, steel types, stations, and smelting modes.

[0059] The detailed process of AOD pre-process scheduling modeling is as follows:

[0060] The input of the AOD pre-process scheduling model is all alloy melting furnace plans to be scheduled, the available smelting modes of the corresponding steel grades, preparation time, production time and the transfer time between the upper and lower processes. The model output is the smelting mode of all alloy melting furnace plans, the start and end time of the designated workstations and plans;

[0061] The model objective function is defined as minimizing the difference between the start time of each AOD and the end time of its corresponding alloy melting furnace plan:

[0062]

[0063] Where nbAod is the number of AOD plans, Smelt i is the available smelting mode for the steel grade corresponding to the i-th AOD plan, nbZ is the number of alloy melting furnace stations, TsAod i is the planned production start time of the i-th AOD plan, EndOF(Zi, j, k) is the end time of the obtained interval variable, PresenceOf is the existence state of the obtained interval variable, j is the workstation, k is the smelting mode, and i=1...nbAod,j=1...nbZ,k∈Smelt i ;

[0064] Define interval variables. The length of any interval variable is preparation time + production time + transmission time. Whether it exists is determined by the model.

[0065]

[0066] i=1...nbAod,j=1...nbZ,k∈Smelt i

[0067] Among them, optional represents whether the interval variable exists. is the preparation time of the steel grade corresponding to the i-th AOD plan at workstation j and smelting mode k, is the production time of the steel type corresponding to the i-th AOD plan at station j and smelting mode k, move da，db is the transportation time from device da to device db;

[0068] da∈{Z},db∈{E,B,A},nbAod is the number of AOD plans, nbZ is the number of medium frequency furnace stations, Smelt i It is the available smelting mode for the steel grade corresponding to the ith AOD plan. IntervalVar is a method for defining interval variables, and optional represents a method for defining whether interval variables exist.

[0069] For a plan number indicating a pre-scheduled converter or electric furnace plan, if an alloy melting furnace plan is to be scheduled, the end time of the alloy melting furnace must be earlier than the production end time of the pre-scheduled converter or electric furnace plan;

[0070]

[0071] Among them, Z i，j，k is the interval variable of the alloy melting furnace plan, TeBE iWhen the ith AOD plan schedules the converter / electric furnace plan, it indicates the planned production end time of the converter / electric furnace. dev∈{E, B} indicates that this constraint exists only when the destination device of the alloy melting furnace is an electric furnace or a converter. E is the converter, B is the electric furnace, and EndOf is used to obtain the end time of the interval variable.

[0072] For the plan number without pre-arranged converter or electric furnace plan, if the alloy melting furnace plan is to be arranged, the end time of the alloy melting furnace must be earlier than the AOD planned production start time;

[0073]

[0074] in, This constraint exists when there is no pre-arranged alloy melting furnace plan for the electric furnace or converter before its corresponding AOD;

[0075] The interval variables of any alloy melting furnace station do not overlap, and the production process times of all plans on it do not overlap;

[0076]

[0077] Construct a non-overlapping constraint on the dual-station production tasks of any alloy melting furnace, that is, the preparation time and production time do not overlap;

[0078]

[0079] IfThen(PresenceOf(Z i，j，k ), StartOf(temp i，j，k )=StartOf(Z i，j，k )) (8)

[0080]

[0081] Among them, PresenceOf is used to obtain the existence status of interval variables. represents the set of interval variables of all plans on the intermediate frequency furnace station j, temp i,j，k Z represents the interval variable of the production process including preparation time and production time. i，j，k is the interval variable of the medium frequency furnace plan, is the preparation time of the steel grade corresponding to the i-th AOD plan at workstation j and smelting mode k, is the production time of the steel grade corresponding to the i-th AOD plan at station j and smelting mode k, The interval variable temp does not allow overlap i,j，kIntervalVar is used to define interval variables, PresenceOf is used to obtain the existence status of interval variables, IfThen is used to define causal constraints, NoOverlap is used to specify interval variables that do not allow overlap, and StartOf is used to obtain the start time of interval variables.

[0082] Define model assignment constraints: any plan can only be produced using one smelting mode; the interval variable corresponding to the three-desulfurization smelting mode cannot exist; if the plan number cannot be produced using a certain smelting mode, the corresponding interval variable cannot exist either; let the number of times a certain smelting mode is selected by the model assignment be equal to the number of furnaces corresponding to the smelting mode set by the planner;

[0083]

[0084] Among them, ProcMode i is a set of Boolean variables that record all optional smelting modes of the i-th AOD plan, x is a Boolean variable, Z i，j，k is the interval variable of the alloy melting furnace plan, nbZ is the number of alloy melting furnace stations, Ndev k is the number of alloy melting furnace stations that can be selected by smelting mode k. ExprArray is used to define expression arrays, BoolVar is used to define Boolean variables, and PresenceOf is used to obtain the existence status of interval variables;

[0085] Define the number constraints of smelting modes, so that the interval variable assigned by the model to select any smelting mode multiplied by the number of alloy melting furnaces required for the corresponding smelting mode is equal to the parameter set by the planner;

[0086]

[0087] k=Type, Type∈{Z, ZZ, ZZZ}

[0088] Sum(Modeused Type )=N Type *C Type (16)

[0089] Among them, Modeused Type It is an array that records the total number of alloy melting furnaces used under the smelting mode type Type. i，j，k is the interval variable of the alloy melting furnace plan, nbAod is the number of AOD plans, nbZ is the number of alloy melting furnace stations, N Type It is the constant of the number of furnaces used by the smelting mode type Type set by the planner, C TypeIt is a constant for the number of alloy melting furnaces required by the smelting mode type Type. ExprArray is used to define the expression array, and PresenceOf is used to obtain the existence status of the interval variable.

[0090] A real-time scheduling problem for stainless steel smelting was solved by adopting the preceding process interval variable constraint programming model. When setting the interval variables, in order to intuitively simulate the on-site production and scheduling situation, the interval variables of each alloy melting furnace plan at each station were defined by subscripts, and the interval variables uniquely corresponded to a specific production process. In terms of setting the length of the interval variables, in order to accurately correspond to the time required for actual production, the length of the interval variable was defined as the sum of three parts: preparation time, production time, and transfer time.

[0091] In order to realize the actual production constraints of adjacent alloy melting furnace stations, that is, all the planned preparation time and production time of the production at the two stations are not allowed to overlap, a series of non-overlapping constraints for the production of alloy melting furnace stations are established. First, corresponding planning interval variables are created for each alloy melting furnace, and the lengths of these intervals are the preparation time and production time, respectively. Then, by designing constraints, the association between the two is guaranteed, and their starting times are ensured to be consistent. Finally, the non-overlapping constraints of the preparation + production time interval variables of adjacent stations are designed to meet this production constraint.

[0092] In order to improve the search and solution efficiency of the model, after the overall constraint design of the model is completed, the solution speed-up constraint is designed at the same time, with the purpose of conveying the scheduling rules to the model. For the planned sequence of a certain alloy melting furnace station, the subsequent process with an earlier start time must start earlier than the current process to make the objective function better. On the one hand, the solution speed-up constraint fundamentally optimizes the objective function, and on the other hand, it speeds up the solution of the model.

[0093] On this basis, in order to achieve a good constraint propagation effect in the model, that is, if a constraint is not satisfied, some other related constraints must also be not satisfied. Boolean variables are coupled in some constraints, and the values ​​of the Boolean variables can be mapped to the values ​​when the constraints are satisfied, so as to achieve the effect of efficient solution of the model.

[0094] AOD pre-process scheduling modeling adopts modern CP modeling methods. When setting interval variables, in order to intuitively reflect the on-site production and scheduling situation, the interval variables of each alloy melting furnace plan at each station are defined by subscripts. The interval variables uniquely correspond to a specific production process. In terms of setting the length of interval variables, in order to accurately correspond to the time required for actual production, the length of the interval variable is defined as the sum of three parts: preparation time, production time, and transfer time.

[0095] In order to realize the actual production constraints of adjacent alloy melting furnace stations, that is, all the planned preparation time and production time of the production at the two stations are not allowed to overlap, a series of non-overlapping constraints for the production of alloy melting furnace stations are established. First, corresponding planning interval variables are created for each alloy melting furnace, and the lengths of these intervals are the preparation time and production time, respectively. Then, by designing constraints, the association between the two is guaranteed, and their starting times are ensured to be consistent. Finally, the non-overlapping constraints of the preparation + production time interval variables of adjacent stations are designed to meet this production constraint.

[0096] In order to improve the search and solution efficiency of the model, after the overall constraint design of the model is completed, the solution speed-up constraint is designed at the same time, with the purpose of conveying the scheduling rules to the model. For the planned sequence of a certain alloy melting furnace station, the subsequent process with an earlier start time must start earlier than the current process to make the objective function better. On the one hand, the solution speed-up constraint fundamentally optimizes the objective function, and on the other hand, it speeds up the solution of the model.

[0097] On this basis, in order to achieve a good constraint propagation effect in the model, that is, if a constraint is not satisfied, some other related constraints must also be not satisfied. Boolean variables are coupled in some constraints, and the values ​​of the Boolean variables can be mapped to the values ​​when the constraints are satisfied, so as to achieve the effect of efficient solution of the model.

[0098] In one embodiment, the AOD plan scheduled according to the steelmaking continuous casting plan, the alloy melting furnace smelting cycle and the inter-unit transfer time are first obtained, and the production scheduling time period of the alloy melting furnace and the total number of furnaces in the corresponding smelting mode of the available equipment are set; the input data is preprocessed to identify whether the corresponding total number of furnaces in the non-one-to-one smelting mode meets the constraints, and if not, an error prompt is given; if the total number of furnaces corresponding to the smelting mode meets the requirements, it is checked whether there is an optional process path for the batch plan, and if not, an error prompt is given; if the process path meets the requirements, the input data is passed to the model, and the model outputs the scheduling results after calculation; the scheduling result data is organized into the data required by the Gantt chart, and the scheduling results are displayed.

[0099] In response to changes in AOD steel grades, manual intervention measures are provided to fine-tune the plans of some alloy melting furnaces in a targeted manner to ensure that the overall plan meets the just-in-time requirements.

[0100] The Gantt chart provides the function of counting the total number of alloy melting furnaces by shift, ensuring the completion of the smelting plan for the shift and reducing the AOD waiting time.

[0101] Take a stainless steel smelting plant of a large domestic steel enterprise as an example of a stainless steel steelmaking scheduling system provided by the present invention. The steel plant has 3 AODs, 3 converters, 1 three-dephosphorization station, and 4 double-station alloy melting furnaces. Due to the mixed production of nickel-based and chromium-based stainless steels, the tonnage of the alloy melting furnace is small, and 1, 2 or 3 furnaces are required to meet the production needs of AOD. The alloy melting furnace and the electric furnace can also be combined; in some special cases, the converter dephosphorized iron water is also added to the AOD as a supplement to smelt chromium steel; in addition, since the number of AODs and continuous casting machines in the steel plant is not equal, the traditional "furnace machine matching" rule is not applicable here, and it is difficult to coordinate AOD and continuous casting machines. It is precisely because of the above two reasons that the steel plant has high requirements for the steelmaking scheduling system. The steelmaking scheduling system needs to consider various process routes, regular replacement of furnace shells of AOD, equipment maintenance, power changes of alloy melting furnaces, and other factors to achieve comprehensive control of production organization.

[0102] Take the production plan of the steel plant's day shift (8-hour work system) for example. In the shift plan, there are 17 AOD smelting furnaces, 4 types of steel, 15 alloy melting furnaces, 6 electric furnaces, and 6 three-thickness furnaces. This is a typical multi-variety small-batch contract production, so the calculation and tracking requirements of smart scheduling are relatively high. The specific production plan is shown in the following table

[0103]

[0104] According to the smelting procedures of the steel grades, 5 furnaces with high silicon process, 6 furnaces with one-for-one electric furnace process and 6 furnaces with three-desulfurization stations were preliminarily determined. Through the calculation of the model, it was confirmed whether the production rhythm of the shift could meet the continuous production of AOD.

[0105] If the process route meets the requirements, the process route, total number of furnaces and other related parameters will be passed to the model, and the model will plan the specific smelting time nodes for each equipment.

[0106] The Gantt chart module receives the model output and displays it in the specified format.

[0107] If the AOD composition is not suitable and the steel grade needs to be changed, the subsequent AOD plan for the shift needs to be adjusted. At this time, the model can automatically recommend the smelting arrangement of the alloy melting furnace and allow the dispatcher to fine-tune the plan according to the on-site conditions.

Claims

1. A stainless steel steelmaking scheduling system, characterized by: The on-site production and scheduling conditions are intuitively simulated, and the specific production process of each furnace pre-liquid solution is defined through interval variables. First, an interval variable of the sum of the preparation time, production time, and transfer time of each alloy melting furnace station is created. Secondly, an interval variable of the preparation + production time between each alloy melting furnace station and the adjacent alloy melting furnace station is created. A series of constraints on non-overlapping production of alloy melting furnace stations are established, and the constraint programming modeling method based on interval variables is used to complete the AOD pre-process scheduling modeling. The AOD pre-process scheduling modeling model is solved. If there is no feasible solution, a no solution prompt is returned. After adjusting the model input, the solution is performed again. After the successful solution is completed, a plan result file, i.e., model output, is generated, and the stainless steel AOD smelting pre-solution scheduling is generated according to the plan result file.

2. A stainless steel steelmaking scheduling system according to claim 1, characterized in that: The interval variable for creating the sum of the preparation time, production time, and transfer time of each alloy melting furnace station is, according to the number of AOD furnaces specified for each smelting mode, the AOD plan to be scheduled, the preparation time of different smelting modes of each steel grade at each station, the production time, and the transfer time data between different stations, check whether each station is under maintenance and whether there is an unfinished plan. The end time of the unfinished plan is the earliest start time of the subsequent planned production scheduling, and check the assigned quantity requirements of each smelting mode at the same time; check the information related to the AOD plan to be scheduled, including the plan number, steel grade, AOD station code, AOD plan start time, and determine whether the converter / electric furnace plan has been arranged. For the converter / electric furnace plan, update the plan start and end time based on whether there is actual performance; check the smelting modes that can be used for each steel grade and the preparation time and production time of each steel grade under different smelting modes at different stations, and check the transfer time between each equipment, and then establish an interval variable for the sum of the preparation time, production time, and transfer time of each alloy melting furnace station corresponding to different AOD furnace numbers, AOD plans to be scheduled, steel types, stations, and smelting modes.

3. A stainless steel steelmaking scheduling system according to claim 1, characterized in that: The detailed process of AOD pre-process scheduling modeling is as follows: The input of the AOD pre-process scheduling model is all alloy melting furnace plans to be scheduled, the available smelting modes of the corresponding steel grades, preparation time, production time and the transfer time between the upper and lower processes. The model output is the smelting mode of all alloy melting furnace plans, the start and end time of the designated workstations and plans; The model objective function is defined as minimizing the difference between the start time of each AOD and the end time of its corresponding alloy melting furnace plan: Where nbAod is the number of AOD plans, Smelt i is the available smelting mode for the steel grade corresponding to the i-th AOD plan, nbZ is the number of alloy melting furnace stations, TsAod i is the planned production start time of the i-th AOD plan, EndOF(Zi, j, k) is the end time of the obtained interval variable, PresenceOf is the existence state of the obtained interval variable, j is the workstation, k is the smelting mode, and i=1...nbAod,j=1...nbZ,k∈Smelt i ; Define interval variables. The length of any interval variable is preparation time + production time + transmission time. Whether it exists is determined by the model. Among them, optional represents whether the interval variable exists. is the preparation time of the steel grade corresponding to the i-th AOD plan at workstation j and smelting mode k, is the production time of the steel type corresponding to the i-th AOD plan at station j and smelting mode k, move da，db is the transportation time from device da to device db; For a plan number indicating a pre-scheduled converter or electric furnace plan, if an alloy melting furnace plan is to be scheduled, the end time of the alloy melting furnace must be earlier than the production end time of the pre-scheduled converter or electric furnace plan; Among them, Z i，j，k is the interval variable of the alloy melting furnace plan, TeBE i When the ith AOD plan schedules the converter / electric furnace plan, it indicates the planned production end time of the converter / electric furnace. dev∈{E, B} indicates that this constraint exists only when the destination device of the alloy melting furnace is an electric furnace or a converter. E is the converter, B is the electric furnace, and EndOf is used to obtain the end time of the interval variable. For the plan number without pre-arranged converter or electric furnace plan, if the alloy melting furnace plan is to be arranged, the end time of the alloy melting furnace must be earlier than the AOD planned production start time; in, This constraint exists when there is no pre-arranged alloy melting furnace plan for the electric furnace or converter before its corresponding AOD; The interval variables of any alloy melting furnace station do not overlap, and the production process times of all plans on it do not overlap; Construct a non-overlapping constraint on the dual-station production tasks of any alloy melting furnace, that is, the preparation time and production time do not overlap; IfThen(PresenceOf(Z i，j，k ),StartOf(temp i，j，k )=StartOf(Z i，j，k )) (8) Among them, PresenceOf is used to obtain the existence status of interval variables. represents the set of interval variables of all plans on the alloy melting furnace station j. IntervalVar is used to define interval variables, temp i，j，k represents the interval variable of the production process including preparation time and production time, The interval variable temp does not allow overlap i，j，k A collection of lfThen is used to define causal constraints, NoOverlap is used to specify interval variables that do not allow overlap, and StartOf is used to obtain the start time of the interval variable; Define model assignment constraints: any plan can only be produced using one smelting mode; the interval variable corresponding to the three-desulfurization smelting mode cannot exist; if the plan number cannot be produced using a certain smelting mode, the corresponding interval variable cannot exist either; let the number of times a certain smelting mode is selected by the model assignment be equal to the number of furnaces corresponding to the smelting mode set by the planner; Among them, ProcMode i is a set of Boolean variables that record all optional smelting modes of the i-th AOD plan, x is a Boolean variable, Z i，j，k is the interval variable of the alloy melting furnace plan, nbZ is the number of alloy melting furnace stations, Ndev k is the number of alloy melting furnace stations that can be selected by smelting mode k. ExprArray is used to define expression arrays, BoolVar is used to define Boolean variables, and PresenceOf is used to obtain the existence status of interval variables; Define the number constraints of smelting modes, so that the interval variable assigned by the model to select any smelting mode multiplied by the number of alloy melting furnaces required for the corresponding smelting mode is equal to the parameter set by the planner; k=Type, Type∈{Z, ZZ, ZZZ} Sum(Modeused Type )=N Type *C Type (16) Among them, Modeused Type It is an array that records the total number of alloy melting furnaces used under the smelting mode type Type. i，j，k is the interval variable of the alloy melting furnace plan, nbAod is the number of AOD plans, nbZ is the number of alloy melting furnace stations, N Type It is the constant of the number of furnaces used by the smelting mode type Type set by the planner, C Type It is a constant for the number of alloy melting furnaces required by the smelting mode type Type. ExprArray is used to define the expression array, and PresenceOf is used to obtain the existence status of the interval variable.

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