Logistics plan creation method and logistics plan creation apparatus

Abstract

A logistics planning method and a logistics planning apparatus are provided that can create a logistics plan that contributes to energy conservation while ensuring the success of operations. [Solution] The logistics plan creation method is a logistics plan creation method executed by a logistics plan creation device (10) that creates a logistics plan for slabs up to a predetermined future time, including the movement of slabs within the slab yard and up to the loading of slabs into the heating furnace, and includes: determining a pile in which slabs can be arranged based on the dispensing time constraint and decision rules; creating candidate logistics plans based on the dispensing time constraint and decision rules, taking into account the movement of slabs brought into the slab yard and slabs dispensed for loading into the heating furnace; selecting a logistics plan from the candidate logistics plans based on an evaluation of the combustion efficiency of the heating furnace and the load of combustion control; and creating a logistics plan by performing simulations at predetermined time intervals up to a predetermined future time.

Description

[Technical Field]

[0001] This disclosure relates to a method and apparatus for creating a logistics plan. In particular, this disclosure relates to a method and apparatus for creating a logistics plan that takes into account the state of the slab when it is loaded into a heating furnace before a rolling process in which hot rolling is performed. [Background technology]

[0002] Most slabs cast in the steelmaking process are stored in a yard (hereinafter referred to as a slab yard) where they are temporarily allowed to dissipate heat before being rolled. After being incorporated into the rolling plan, the slabs are reheated in a furnace to a temperature suitable for rolling before being rolled. While stored in the slab yard, the slabs dissipate heat through radiation and heat transfer, causing their temperature to drop. Reheating the slabs to the highest possible temperature is useful not only for improving manufacturing efficiency but also for saving energy by suppressing heat dissipation.

[0003] Patent Document 1 describes a method for calculating the temperature change of a slab from the torch cutting time of the slab, the slab temperature during continuous casting, the transport plan, and stacking information in the slab yard, and predicting the slab's heating furnace charging temperature.

[0004] The technology described in Patent Document 2 involves storing slabs that need to be cooled and slabs that need to be heated together in a slab yard, and when these steel billets are held in an overlapping manner, the difference between the current temperature of each steel billet and the target temperature is expressed as a cost function. The overlapping state of each steel billet is determined so as to minimize the cost function, and the arrangement of the steel billets is carried out according to the determined overlapping state. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6380510 [Patent Document 2] Patent No. 6354952 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the technology described in Patent Document 1 predicts the slab charging temperature, but does not provide any means to further improve the charging temperature. Furthermore, while the technology described in Patent Document 2 can implement transport planning guidance aimed at improving the temperature of the entire slab within the yard, its cost function does not take into account the transport load in the slab yard. Moreover, when considering multi-stage processes that include the operation of equipment outside the slab yard, formulating the process using a cost function is difficult. Additionally, the technology only aims to determine the handling for a single slab repositioning, and does not necessarily guarantee the creation of a plan that ensures timely completion for the next process (a feasible plan).

[0007] In light of these circumstances, the purpose of this disclosure is to provide a logistics planning method and a logistics planning apparatus that can create a logistics plan that contributes to energy conservation while ensuring the success of operations. [Means for solving the problem]

[0008] (1) A logistics plan creation method according to one embodiment of the present disclosure is: A logistics planning method executed by a logistics planning device, which creates a logistics plan for slabs up to the time they are loaded into a heating furnace, including the movement of slabs within a slab yard where slabs to be loaded into a heating furnace are stored, covering a predetermined future time, Based on a payout time constraint that ensures the lower slabs in multiple slab storage areas within the slab yard are paid out by the payout time, and a determination rule that determines which piles of slabs can be placed within the slab yard, a candidate logistics plan is created based on the payout time constraint and the determination rule, taking into account the movement of slabs brought into the slab yard and slabs paid out for loading into the heating furnace. Select a logistics plan from the candidates of the logistics plan based on the evaluation of the combustion efficiency of the heating furnace and the load of combustion control, and execute a simulation up to the predetermined future time at a predetermined time interval to create a logistics plan.

[0009] (2) As an embodiment of the present disclosure, in (1), including obtaining a charging plan of the slab into the heating furnace, The delivery time is calculated by subtracting the lead time from delivery to charging, which is the most frequent value of past performance, from the scheduled charging time of the slab included in the charging plan.

[0010] (3) As an embodiment of the present disclosure, in (1) or (2), The determination rule is to stack the slabs arriving at the slab yard on the pile with the highest temperature of the uppermost slab.

[0011] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The evaluation is performed using an evaluation formula including a term related to improving the charging temperature of the slab into the heating furnace and a term related to reducing the difference in the charging temperature of adjacent slabs in the heating furnace, targeting the slabs for which the charging plan into the heating furnace has been determined.

[0012] (5) As an embodiment of the present disclosure, in any one of (1) to (4), In the execution of the simulation, the temperature of the slabs stored in the slab yard is updated by calculation using a heat dissipation model formula of the slabs assuming no heat transfer between the slabs.

[0013] (6) A logistics plan creation device according to an embodiment of the present disclosure is A logistics plan creation device that targets up to a predetermined future time, includes the movement of slabs in a slab yard for storing slabs charged into a heating furnace, and creates a logistics plan for the slabs until they are charged into the heating furnace. Determine a stack where slabs can be arranged based on the payout time constraint that the slabs in the lower layer of multiple slab storage areas in the slab yard are paid out by the payout time, and the determination rule for determining the stack where the slabs are arranged in the slab yard. Create a candidate for the logistics plan based on the payout time constraint and the determination rule, taking into account the movement of the slabs carried into the slab yard and the slabs paid out for charging into the heating furnace. Select a logistics plan from the candidates for the logistics plan based on the evaluation of the combustion efficiency and combustion control load of the heating furnace, and include an arithmetic unit that executes a simulation up to a predetermined future time at a predetermined time interval to create a logistics plan.

Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a logistics plan creation method and a logistics plan creation device that can create a logistics plan that contributes to energy saving while ensuring the establishment of operations.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a diagram illustrating a production line to which a logistics plan creation method according to an embodiment of the present disclosure is applied. [Figure 2] FIG. 2 is a schematic diagram of a slab yard. [Figure 3] FIG. 3 is a diagram showing a configuration example of a logistics plan creation device and a flow of processing of a logistics plan creation method according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram showing a process of selecting a stack where slabs can be received. [Figure 5] FIG. 5 is a diagram for explaining the slab width difference. [Figure 6] FIG. 6 is a diagram showing an example of receiving and paying out slabs for a stack in a slab yard. [Figure 7] FIG. 7 is a diagram showing an example of receiving and paying out slabs for a stack in a slab yard. [Figure 8A] ​ [Figure 8B] Figure 8B is a diagram illustrating heat transfer in a slab. [Figure 8C] Figure 8C is a diagram illustrating heat transfer in a slab. [Figure 9] Figure 9 shows the distribution of arrival times at the slab yard. [Figure 10] Figure 10 shows the distribution of crane cycle times. [Figure 11] Figure 11 shows the distribution of lead times from dispensing to loading. [Figure 12] Figure 12 shows an example of the initial state of a slab yard pile. [Figure 13] Figure 13 shows the state of the slab yard piles in all plans. [Figure 14] Figure 14 shows the candidates when the constraints in Figure 13 are taken into consideration. [Figure 15] Figure 15 shows the candidate options when the temperature of the top slab is taken into consideration in Figure 14. [Figure 16] Figure 16 shows the change in average charging temperature due to differences in the decision rules. [Figure 17] Figure 17 shows information about the slabs within the yard. [Figure 18] Figure 18 shows information regarding the casting plan. [Figure 19] Figure 19 shows information regarding the installation plan. [Figure 20] Figure 20 is a diagram showing the equipment specifications. [Figure 21] Figure 21 is a reference table regarding stacking constraints within the yard. [Figure 22] Figure 22 is a table of physical properties based on carbon concentration. [Figure 23] Figure 23 shows the weighting coefficients based on carbon concentration. [Figure 24] Figure 24 is a table of physical properties. [Figure 25] Figure 25 shows the simulation results. [Figure 26] Figure 26 shows the charging plan created based on the simulation. [Figure 27] Figure 27 shows the installation record based on actual data. [Modes for carrying out the invention]

[0016] A logistics plan creation method and logistics plan creation apparatus 10 (see Figure 3) according to one embodiment of the present disclosure will be described below with reference to the drawings.

[0017] Figure 1 illustrates a manufacturing line to which the logistics planning method according to this embodiment is applied. Slabs obtained by casting from molten steel in a continuous casting machine are transported by traverse carts to the hot rolling mill line. Each slab is heated in a heating furnace before being rolled in the hot rolling mill. Here, slabs arriving at the hot rolling mill are divided into direct-load materials that are loaded directly into the heating furnace via a transport table after arrival, and non-direct-load materials that are temporarily stored in the slab yard before being loaded. The slab yard can be used to temporarily store the arriving slabs.

[0018] Figure 2 is a schematic diagram of the slab yard. When non-direct materials are brought into (received) the slab yard for temporary storage, the slabs on the traverse trolley are lifted by a crane and then piled up inside the slab yard (hereinafter sometimes referred to as "the yard"). Hereafter, a group of slabs piled up in one place will be referred to as a "pile". There is one or more piles in the yard. The slabs in the yard are incorporated into the rolling plan and, when it is time to load them into the heating furnace, are unloaded from the yard onto a traverse trolley by a crane and loaded into the heating furnace. If the target slab is not on the top of the pile during unloading, a rearrangement operation is performed to move the slabs stacked above the target slab to another pile, and then the unloading operation is performed. Rearrangement makes it possible to load the slabs into the heating furnace in an order different from the order in which they arrived from the continuous casting machine. After being loaded into the heating furnace, the slabs are heated to the appropriate temperature and then removed from the heating furnace. In the heating furnace, slabs are drawn in a first-in, first-out order and then hot-rolled. In Figure 2, slabs that are not directly delivered and arrive at the slab yard are indicated as "arriving slabs." Also in Figure 2, slabs that are dispensed and charged into the heating furnace are indicated as "slabs to be charged." Furthermore, the slab stacked at the very top of each pile is sometimes referred to as the "top slab."

[0019] Figure 3 is a diagram showing an example configuration of the logistics planning device 10 according to this embodiment, and the arrows indicate the processing flow of the logistics planning method executed by the logistics planning device 10. The logistics planning device 10 creates a logistics plan in the rolling process in which a slab is hot-rolled in a hot rolling mill. The logistics plan covers a predetermined future time (for example, the next 24 hours from the present time) and includes the movement of slabs in the slab yard where slabs to be charged into the heating furnace are stored, and is a plan up to the time of charging into the heating furnace. In this embodiment, in the manufacturing line to which the logistics planning method is applied, the steelmaking process using a continuous casting machine and the rolling process in which slabs cast by the continuous casting machine are hot-rolled in a hot rolling mill are operated synchronously.

[0020] The logistics planning device 10 comprises an acquisition unit 11, a calculation unit 12, and an output unit 13. The logistics planning device 10 may be a computer as its hardware configuration. The logistics planning device 10 may also have the following software configuration: One or more programs used to control the operation of the logistics planning device 10 are stored in a storage device accessible from the logistics planning device 10. When the programs stored in the storage device are read by the processor (e.g., a CPU) of the logistics planning device 10, the processor is made to function as the acquisition unit 11, the calculation unit 12, and the output unit 13.

[0021] The logistics planning device 10 is configured to communicate with a higher-level system 20. The higher-level system 20 is a system that manages and controls a manufacturing line, including, for example, continuous casting and hot rolling, and may be composed of a different computer from the logistics planning device 10. The logistics planning device 10 acquires various data from the higher-level system 20, including the input information described later, which is necessary for calculations (simulation, slab temperature prediction using a model, etc.) for creating the logistics plan. The logistics planning device 10 also outputs the results of the calculations, including the created logistics plan, to the higher-level system 20.

[0022] The acquisition unit 11 acquires input information. The input information includes inventory information, casting information, heating information, rolling information, and equipment information. The inventory information includes information on slabs in the slab yard and slabs in transit. The inventory information includes initial inventory information, which is information on the inventory in the slab yard at the start of the calculation for creating the logistics plan performed by the calculation unit 12. The casting information includes information such as the dimensions and steel type of the cast slabs. The casting information may also include information on the surface temperature of the slab at the time of torch cutting. The surface temperature at the time of torch cutting is the surface temperature of the slab that has been cast in a continuous casting machine and torch-cut to a predetermined length. Here, the casting information may include not only actual data but also planned data for castings scheduled for a certain period in the future. For example, for a casting plan up to 24 hours in advance, the casting information may include planned values ​​such as slab dimensions and steel type, planned torch cutting time, and planned slab surface temperature. The heating information includes information on the slabs in the heating furnace and the heating status. The heating information includes the planned time for charging into the heating furnace (the planned time for charging the slabs into the heating furnace), which constitutes part of the plan for charging into the heating furnace. Furthermore, the heating information may include the actual temperature value (measured temperature) of the slab before charging into the heating furnace. The rolling information includes the rolling plan and rolling constraints. The plan for charging into the heating furnace may constitute a part of the rolling plan. The rolling plan may be created, for example, by a known planning method by the higher-level system 20. The logistics planning device 10 can extract the plan for charging into the heating furnace from the rolling plan and create a logistics plan for the slab yard in accordance with the plan for charging into the heating furnace and in an operational manner. The equipment information includes whether each piece of equipment is faulty, equipment capacity specifications, and space constraints.

[0023] The calculation unit 12 receives input information from the acquisition unit 11 and performs calculations to create a logistics plan. The logistics plan is created as a plan for a predetermined period in advance, using future casting plans, heating plans in the heating furnace, etc. In this embodiment, commands for slab movement or transport, or temperature, etc., are calculated (recalculated) at a fixed pitch for the predetermined period in advance. In this embodiment, the calculations include simulations. The simulations include both slab logistics simulations and slab temperature simulations. The calculation unit 12 may determine whether the operation is feasible based on the simulation and exclude candidates that are determined not to be feasible. The calculations performed by the calculation unit 12 are not limited to simulations and may perform various calculations, judgments, and decisions related to the creation of the logistics plan. In this embodiment, the calculation unit 12 predicts (calculates) and updates the slab temperature using a model (calculation formula). In this embodiment, the calculation unit 12 determines the piles where the slabs can be placed based on the dispensing time constraints and decision rules. The calculation unit 12 creates candidate logistics plans based on the timing constraints and decision rules, taking into account the movement of slabs brought into the slab yard and slabs discharged for charging into the heating furnace. The calculation unit 12 selects a logistics plan from the candidate logistics plans based on an evaluation of the combustion efficiency of the heating furnace and the load of combustion control, and creates the logistics plan by performing simulations at predetermined time intervals (e.g., a fixed pitch of 2 minutes) up to a predetermined future time (e.g., 24 hours ahead).

[0024] The output unit 13 outputs the results of calculations performed by the calculation unit 12. The results include a logistics plan selected from the candidates created by the calculation unit 12. By receiving the logistics plan selected by the calculation unit 12 and controlling the manufacturing line according to that logistics plan, it is possible to improve manufacturing efficiency and save energy by suppressing heat dissipation. The received logistics plan may be adopted as is as the subsequent plan and used for slab transport commands. Alternatively, the plan may be modified after recalculation, and as described in the simulation explanation above, the plan may be reviewed at a constant pace.

[0025] The following describes the processing performed by the calculation unit 12. The calculation unit 12 selects a pile of slabs that can be accepted by the process shown in Figure 4, targeting slabs up to a predetermined time in the future. The flowchart in Figure 4 explains the processing performed for each target slab, starting from the time of arrival at the slab yard. First, the calculation unit 12 calculates the arrival time of non-direct materials at the slab yard based on the casting information. The arrival time is obtained by adding the slab yard arrival time to the time the slab is torch-cut. The slab yard arrival time is the time from when the slab is torch-cut until it arrives at the slab yard via the traverse trolley. In this embodiment, the slab yard arrival time is determined by the most frequent value from past performance (see Figure 9).

[0026] After the arrival time is determined, the calculation unit 12 decides which pile in the yard the arriving slab will be received into. The calculation unit 12 cyclically (for example, every few minutes) decides which slab to rearrange with the crane to which pile, whether to unload (remove) the top slab, or whether to not rearrange or unload it. Here, the time interval at which the cyclic decision is made may be determined based on the mode or maximum value in past performance data of transport time for slab transport within the yard. In this embodiment, this time interval is determined by the mode in past performance data of the crane cycle time (the time from the command to operate the crane to the next command) within the yard (see Figure 10). As an example, the calculation unit 12 decides whether to accept, rearrange, or unload the slab every two minutes.

[0027] Here, the calculation unit 12 also calculates the time when the slabs in the yard are released from the slab yard (release time). The release time is determined so as to be in time for the scheduled furnace charging time obtained from the furnace charging plan. For example, the release time is calculated by subtracting the lead time from release to charging from the scheduled furnace charging time. In this embodiment, the lead time from release to charging is determined by the mode of past performance (see Figure 11).

[0028] The calculation unit 12 considers stacking constraints when deciding which stack in the yard to accept the arriving slabs into. In this embodiment, the stacking constraints include stacking height constraints, stacking width constraints, and stacking length constraints, which are constraints on the height, width, and length of the slabs when stacking them, respectively. For example, the slab width difference is determined as ω1-ω2 by comparing the width ω1 of the uppermost slab in the stack with the width ω2 of the smallest slab in the lowermost slab, as shown in Figure 5. The width constraint is that this width difference must be less than or equal to the given maximum allowable width difference. Similar constraints apply to length. In addition, there is a constraint that the height must be less than or equal to the maximum allowable height. The calculation unit 12 reads a reference table related to stacking constraints (see Figure 21) and narrows down the acceptance candidates by considering the stacking constraints. Stacks that do not satisfy the constraints are excluded from acceptance. Here, the stacking constraints may further include constraints such as the number of slabs, steel type, or weight.

[0029] The calculation unit 12 considers the dispensing time constraint when deciding which pile in the yard to accept the arriving slabs into. The dispensing time constraint is a constraint that ensures that even if the arriving slabs are loaded into a candidate pile of slabs, the dispensing of the lower layers of inventory (lower layers of slabs) into that pile can be completed in time for the scheduled furnace charging time. In other words, the dispensing time constraint is a constraint that ensures that the lower layers of slabs in multiple slab storage areas within the slab yard are dispensing by the dispensing time. The calculation unit 12 removes (excludes) from the candidates any logistics plans that do not satisfy the dispensing time constraint (hereinafter simply referred to as "plans"), i.e., plans in which loading the arriving slabs would prevent the dispensing of the lower layers of slabs from being completed in time for the scheduled furnace charging time.

[0030] Figures 6 and 7 illustrate examples of slab acceptance and disbursement in a slab yard. The times indicated on the slabs are disbursement times. The time (t) is also shown, and the decision to accept, rearrange, or disburse is made every two minutes. In the example in Figure 6, the third pile from the left accepts the arriving slab, but the third slab from the bottom of the same pile (disbursement time 21:10) cannot be disbursed by 21:10, so it is removed from the list of candidates. Similarly, in the example in Figure 7, the third pile from the left accepts the arriving slab, but the first slab from the bottom of the leftmost pile (disbursement time 21:08) cannot be disbursed by 21:08, so it is removed from the list of candidates. In Figures 6 and 7, slabs whose disbursement will not be completed in time for the scheduled furnace charging time are marked "NG," and slabs that will be completed in time are marked "OK."

[0031] Furthermore, in determining which pile in the yard to accept the arriving slabs, the calculation unit 12 considers a decision rule for determining which pile to place the slabs in within the slab yard. Multiple decision rules can be adopted, but in this embodiment, the rule "place the arriving slabs on the pile with the highest temperature of the top layer slabs" is adopted. Here, a high temperature of the top layer slab may mean that it is above a standard temperature determined based on past performance values, or, as in this embodiment, that it is relatively the highest temperature of the top layer slabs. By stacking the slabs on the pile with the highest temperature of the top layer slabs, a decrease in slab temperature due to heat dissipation can be prevented. Specific examples of other rules that can be adopted as decision rules will be described later (see Examples).

[0032] Furthermore, the calculation unit 12 can calculate the slab temperature (slab surface temperature) using the following equations (1) to (3).

[0033]

number

[0034] Here, T tis the slab surface temperature (°C) at time t. T t-τ is the slab surface temperature (°C) at time t - τ. Δτ is the time step for temperature update (seconds). C p is the specific heat of the slab (kJ / (kg·K)). W is the weight of the slab (kg). S is the surface area of the slab (m 2 ). θ is the slab surface temperature (°C). T a is the slab ambient temperature (°C). σ is the Stefan - Boltzmann constant (5.67×10 -8 E / (m 2 K 4 )). ε is the emissivity of the slab. α is the heat transfer coefficient between the slab and the atmosphere (W / (m 2 K)). D is the slab thickness (m). λ is the thermal conductivity (W / (mK)). T is the cross - sectional average temperature of the slab (°C).

[0035] Equations (1) and (2) are the heat dissipation model equations of the slab, which are obtained based on the equation of steady - state heat conduction, Fourier's law, or Newton's cooling law. Equation (3) is the equation for converting the slab surface temperature and the cross - sectional average temperature. Here, it is assumed that there is no heat transfer between slabs, and the surface area S of the slab changes as shown in FIGS. 8A - 8C depending on the position of the stacked slabs. FIG. 8A shows that the slab is within the yard, located in the middle of the stack, and heat transfer occurs from the four lateral sides. D is the length of the slab in the stacking direction (height direction) of the mountain, which is the above - mentioned slab thickness. W is the length in the width direction of the slab, that is, the slab width. L is the length in the direction orthogonal to the height and width directions of the slab, that is, the slab length. FIG. 8B shows that the slab is within the yard, located at the top or bottom of the stack, and heat transfer occurs from a total of five surfaces including the four lateral sides and the upper or lower one surface. FIG. 8C shows that the slab forms a mountain alone within the yard, and heat transfer occurs from a total of six surfaces including the four lateral sides and the upper and lower two surfaces.

[0036] Also, the slab ambient temperature (T a ) is given as a constant, such as an estimated value based on past performance. The specific heat of the slab (C pThe specific heat (C) and thermal conductivity (λ) of a slab are generally known to depend on the carbon concentration and temperature. p The specific heat (C) and thermal conductivity (λ) of the slab are determined using a physical property table summarized for each carbon concentration of the slab, as shown in Figure 22. Here, the specific heat (C) of the slab is determined. p The temperature (λ) and thermal conductivity (λ) may be determined by linear interpolation when the temperature or carbon concentration is not found in the material properties table. When the mean cross-sectional temperature (T) of the slab lies between T1 and T2, the weighting coefficients q1 and q2 used in the interpolation are determined using equations (4) and (5).

[0037]

number

[0038] Furthermore, a table like the one in Figure 22 shows the carbon concentration c A , c B , c C If present for, the weight coefficient p A , p B , p C This is represented as shown in Figure 23. For example, the interpolation formula for the thermal conductivity λ is expressed as (6).

[0039]

number

[0040] Here, .'' n1 (n=A, B, C) represents the carbon concentration c n This is the value of the thermal conductivity at temperature T1 in the table. Also, λ n2 (n=A, B, C) represents the carbon concentration c n This is the value of the thermal conductivity at temperature T2 in the table. The slab temperature is updated by performing such temperature calculations at the time the slab is torch-cut, at the scheduled time of furnace charging, or cyclically (for example, every 2 minutes).

[0041] If there are multiple acceptable mountains to choose from, multiple feasible plans are created. If all of the acceptable mountains are empty, i.e., mountains without a lower slab, the calculation unit 12 only needs to select one. Otherwise, the calculation unit 12 can select the optimal plan from the multiple feasible plans using the following method.

[0042] The calculation unit 12 uses the evaluation formula shown in equation (7) below to select a plan that can maximize the charging temperature of each slab and reduce the load on combustion control. The evaluation is performed on slabs for which the charging plan to the heating furnace has been determined. Here, when using the evaluation formula in equation (7), a near-optimal solution may be evaluated as the optimal value. In other words, even if it is not necessarily the maximum or minimum value, if the value of the evaluation formula is near the maximum or minimum value, it may be evaluated as the optimal value. In this way, the optimal plan is selected based on the evaluation formula. The first term of equation (7) is a term related to reducing the difference in charging temperature between adjacent slabs in the heating furnace. If the difference in charging temperature between adjacent slabs is small, it is possible to avoid control that changes the temperature of the heating furnace in a short time (high-load control). In other words, the first term is a term that evaluates the load on combustion control. The second term of equation (7) is a term related to improving the charging temperature of the slabs to the heating furnace. In other words, the second term is a term that evaluates the combustion efficiency of the heating furnace.

[0043]

number

[0044] Here, I represents the set of slabs whose installation order has been determined. Also, T i is the charging temperature (°C) of slab "i". The calculation unit 12 can calculate all slab temperatures for each plan and derive the best solution through exhaustive search. By this method, the optimal plan can be selected while taking logistics into consideration, and it becomes possible to improve manufacturing efficiency and achieve energy savings by suppressing heat dissipation.

[0045] The effects of this disclosure will be described in detail below based on the examples, but this disclosure is not limited to these examples.

[0046] Figure 17 shows the slab attributes and location information of the slabs placed in the yard when the input information is read. Figure 17 corresponds to the initial inventory information in the slab yard. Slabs are distinguished by a slab number, which is a unique number for each slab. For example, a slab with slab number 5 is written as slab "5". There are a maximum of 7 stacks in the yard, and the names of the stacks are designated as D1, D2, ..., D7 from the traverse trolley side. A maximum of 9 slabs are stacked in one stack. The stacking order of slabs in a stack is such that the bottom layer is 1. For example, in a certain stack, the stacking order of the third slab from the bottom is 3. The ambient temperature in the yard (slab ambient temperature) is set to a constant value. The transport tables are managed in sections, and the sectioned transport tables have names such as TB1, TB2, ...

[0047] Figure 18 shows information regarding the planned casting schedule at 8:00:00 on August 1, 2021, which is the starting point for the plan update. Figure 19 shows information regarding the charging schedule at the starting point for the plan update. Directly shipped materials are indicated as "Direct" in the Directly Shipped Materials (Direct / Non-Direct) column. Non-directly shipped materials are indicated as "Non-Direct" in the Directly Shipped Materials (Direct / Non-Direct) column.

[0048] Figure 20 shows the equipment specifications. Figure 21 shows the standard table for stacking constraints within the yard. The slab yard arrival time was set to 12 minutes based on the mode in Figure 9. The crane cycle time was set to 2 minutes based on the mode in Figure 10, and a decision was made every 2 minutes whether to accept, reposition, or unload the slab. The lead time from unloading to loading was set to 0.5 minutes based on the mode in Figure 11.

[0049] Figure 12 shows an example of the initial state of the slab yard pile in this embodiment. The state after the next cycle time (2 minutes later) from the initial state branches into the plans listed in Figure 13, provided that the dispensing time constraint and decision rule are not applied. Here, the decision rule is a constraint based on the temperature of the top slab. Specifically, the decision rule adopted in this embodiment is the constraint to select a plan in which the arriving slab is loaded onto the pile with the highest temperature of the top slab. In other words, Figure 13 shows multiple plans that satisfy only the stacking constraint.

[0050] When the dispensing time constraint is applied to the multiple plans in Figure 13, plans 5 and 8 are eliminated from the candidates, as shown in Figure 14. Furthermore, when the decision rule is applied to the multiple plans in Figure 14, the candidates are narrowed down to plans 1, 3, or 6, enclosed in a frame, as shown in Figure 15. One of these three plans is selected and the simulation proceeds, and the same narrowing and selection process is repeated in the next cycle time (after another 2 minutes). At this time, the slab temperature is updated using the physical property tables in Figures 22, 23, and 24. Ultimately, all slabs should be successfully loaded (successfully completed); if dispensing or acceptance becomes impossible midway through, a re-simulation with a different plan may be performed.

[0051] Figure 25 shows an example of a simulation result indicating a successful completion. Figure 26 shows the charging plan created using the method of this embodiment based on the simulation. Figure 27 shows the actual charging results based on data from the conventional method. The predicted insertion temperature for slab "4" in Figure 26 is higher than that in Figure 27, indicating that a plan was created that allows for charging at a higher temperature.

[0052] Here, Figure 16 shows approximately 25 feasible plans obtained from simulations with a 24-hour planning period and varying decision rules, sorted in descending order of average charging temperature. The plan with the number "0" has the highest average charging temperature, and the average charging temperature decreases as the number increases. As described above, multiple decision rules can be adopted. First, decision rule (a) is to select a plan in which the arrival slab is placed on the mountain with the highest temperature of the uppermost slab, as described above. Decision rule (b) is to select a plan in which the arrival slab is placed on the mountain with the greatest height. Decision rule (c) is to select a plan in which the arrival slab is placed on the mountain that contains the most recently moved slab. Decision rule (d) is to select a plan in which the arrival slab is placed on the mountain with the lowest height. Decision rule (e) is to select a plan in which the arrival slab is placed on the mountain with the latest charging time when comparing the slabs with the earliest charging times on each mountain. The decision rules (a) to (c) allowed us to create a plan with a higher average charging temperature than the actual results (dashed line in Figure 16). As is clear from the comparison in Figure 16, by using the decision rule (a), as in this embodiment, it is possible to create a plan that allows for charging at a higher temperature.

[0053] As described above, the logistics planning method and logistics planning apparatus 10 according to this embodiment can create a logistics plan that contributes to energy saving while ensuring the feasibility of operations through the above-described process and configuration. By following a plan whose feasibility of operations, including multi-stage processes, is ensured through verification by logistics simulation, it is possible to avoid execution adjustments due to logistics capacity bottlenecks during actual operation, and efficient steel product manufacturing becomes possible. Furthermore, a suitable plan can be selected from multiple candidates to improve the charging temperature to the heating furnace and to provide a low-load heating pattern operation for the heating furnace.

[0054] While embodiments relating to this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art will find it easy to make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are included within the scope of this disclosure. For example, the functions included in each component or step can be rearranged in a logically consistent manner, and multiple components or steps can be combined into one or divided. Embodiments relating to this disclosure can also be realized as programs executed by a processor in the device or as storage media recording such programs. These should also be understood to be included within the scope of this disclosure. [Explanation of Symbols]

[0055] 10 Logistics planning device 11 Acquisition Department 12 Arithmetic section 13 Output section 20 Higher-level systems

Claims

1. A logistics planning method executed by a logistics planning device, which creates a logistics plan for slabs up to the time they are loaded into a heating furnace, covering a predetermined future time, including the movement of slabs within a slab yard where slabs to be loaded into a heating furnace are stored, Based on a payout time constraint that ensures the lower slabs in multiple slab storage areas within the slab yard are paid out by the payout time, and a determination rule that determines which piles of slabs can be placed within the slab yard, a candidate logistics plan is created based on the payout time constraint and the determination rule, taking into account the movement of slabs brought into the slab yard and slabs paid out for loading into the heating furnace. A method for creating a logistics plan, comprising: selecting a logistics plan from the candidate logistics plans based on an evaluation of the combustion efficiency and combustion control load of the heating furnace; and creating the logistics plan by performing simulations at predetermined time intervals up to a predetermined future time.

2. This includes obtaining a plan for charging the slab into the heating furnace, The method for creating a logistics plan according to claim 1, wherein the dispensing time is calculated by subtracting the lead time from dispensing to charging, which is determined by the most frequent value of past performance, from the scheduled time for charging the slab into the heating furnace included in the charging plan.

3. The method for creating a logistics plan according to claim 1 or 2, wherein the decision rule is to stack the slabs that have arrived at the slab yard on the pile with the highest temperature of the uppermost slab.

4. The logistics planning method according to claim 1 or 2, wherein the evaluation is performed using an evaluation formula that includes a term relating to improving the charging temperature of the slab into the heating furnace and a term relating to reducing the difference in charging temperatures between adjacent slabs in the heating furnace, for which the charging plan into the heating furnace has been decided.

5. The logistics planning method according to claim 1 or 2, wherein in the execution of the simulation, the temperature of the slabs stored in the slab yard is updated by a calculation using a slab heat dissipation model equation that assumes there is no heat transfer between slabs.

6. A logistics planning device that creates a logistics plan for slabs up to a predetermined future time, including the movement of slabs within a slab yard where slabs to be loaded into a heating furnace are stored, until the slabs are loaded into the heating furnace, Based on a payout time constraint that ensures the lower slabs in multiple slab storage areas within the slab yard are paid out by the payout time, and a decision rule that determines which piles of slabs can be placed within the slab yard, a pile where slabs can be placed is determined, and a candidate logistics plan is created based on the payout time constraint and the decision rule, taking into account the movement of slabs brought into the slab yard and slabs paid out for loading into the heating furnace. A logistics planning device comprising a calculation unit that selects a logistics plan from the candidate logistics plans based on an evaluation of the combustion efficiency and combustion control load of the heating furnace, and creates a logistics plan by performing simulations up to a predetermined future time at predetermined time intervals.

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