JPH0428608B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides raw material transport control that can immediately respond to requests and maximize the usage efficiency of transport equipment in plants that store multiple brands of raw materials and blend and use them according to demand. Regarding the method. Steel works, thermal power plants, etc. have intermediate buffer means called raw material yards to temporarily store raw materials used for those purposes. In these plants, raw materials are transported in various ways and are once piled up in this raw material yard. When a supply request occurs in the production process, the required amount is cut out from the raw material yard and continuously supplied by conveyance means such as a belt conveyor. Usually the scale of these plants is much larger than their profitability,
This results in an increase in the types and amounts of raw materials and the complexity of conveyance means. The present invention focuses on and solves the problems related to the transportation and blending of various kinds of raw materials, which are essential elements in plants as described above. Figure 1 shows a plant to which the present invention is applied.
This shows an example of a raw material transportation process in a steelworks. The amount of work, time, and energy consumed in this process is greater than expected. This process is located at the most upstream stage of the steel production process, and in order to supply various raw materials such as coal and ore to blast furnaces and coke plants according to demand, the process that generates supply demands must secure a large number of raw material tanks. , we always stock more than a certain level of raw materials. As shown in FIG. 1, raw materials are transported by being cut out from a raw material pile 101 by a cutting device 102 such as a reclaimer, placed on a belt conveyor 103 extending several kilometers, and arriving at a raw material distribution device 104. In the raw material distributing device 104, the direction is changed in order to distribute the raw material among multiple tanks, and the raw material is received into a raw material tank 105 to which a brand is assigned in advance. Raw materials are cut out at a predetermined ratio from the raw material tank 105 and finally mixed on a belt conveyor 106 to obtain raw materials. 2 and 3 show the detailed configuration of the raw material distribution device 104. Normally, one type of raw material is conveyed continuously along one route, while a plurality of raw material tanks 105 are assigned to the corresponding brand, so a continuous route switching function is required. The material distributing device 104 realizes this, and as shown in FIG.
), a tank-top belt conveyor 108 (hereinafter referred to as SBj (j = 1 to 8)) arranged at right angles to the receiving belt conveyor UKi, and a tank-top belt conveyor 108 (hereinafter referred to as SBj (j = 1 to 8)), at the intersection of the receiving belt conveyor UKi and the tank-top belt conveyor SBj. scraper 109 and each raw material tank 10 arranged in
It is composed of a direction changing device called a scraper 110 placed on top of the scraper 110. In the figure, brand A (hereinafter, the type of raw material will be indicated with one capital letter) is being conveyed on receiving belt conveyor UK1, and scraper 1 is at the intersection with tank belt conveyor SB6.
09 is DOWN (hereinafter, the state in which the direction change is being performed is referred to as DOWN, and the state in which the direction is not being changed is referred to as UP), which indicates that the state is being conveyed to the above-tank belt conveyor SB6. The receiving belt conveyor UKi and the tank-top belt conveyor SBj intersect three-dimensionally, and it is possible to change direction from any receiving belt conveyor UKi to all the tank-top belt conveyors SBj. Figure 3 shows raw material tank 1 below the tank belt conveyor SBj.
This shows the arrangement of the 05 group. Each raw material tank 10
5 is also provided with a scraper 110, and can be received in any of the raw material tanks 105. In this figure, the capital letters in the raw material tank 105 are assigned brand names. Note that there is a type of direction changing device called a tripper. Regarding the reception of raw materials into the raw material tanks as described above, the biggest goals are (1) to maintain the inventory level of each raw material tank 105 at a high level in order to realize stable operation of the production process (sintering, coke, blast furnace, etc.); . (2) Stabilize raw material receiving operations to improve overall production efficiency. There are two points. Conventionally, the method used to achieve these two goals is to
This is a method of generating transportation work for items of 05 that reach the lowest inventory level within a certain time range. In other words, a computer or the like was used to constantly predict the changes in the amount of inventory, draw up a transportation work plan, and operate the system in accordance with the plan.
However, in many cases, raw material tanks 105 that are below the inventory minimum level no longer occur, and the operation of the production process becomes stable. However, because the focus is only on low-level raw material tanks 105, many brands and 105
When the lower limit is reached, it becomes impossible to formulate and control a plan for receiving the raw material into the raw material tank 105. Also, for the same reason, it does not function satisfactorily to meet the advanced demands of factories that use raw materials, such as maintaining the inventory level in the raw material tank 105 at a higher level. In order to solve this problem, it is necessary to formulate a work plan that will eliminate the occurrence of the raw material tank 105 reaching the lowest inventory level and allow the raw material conveyance work to be carried out as continuously as possible. The reason this has not been achieved in the past is that other planning methods could not be applied due to the uniqueness of this problem. That is, there are major restrictions on changing the route due to operational constraints of the raw material distribution device 104, and the number of target raw material tanks 105 is tens to hundreds. Job scheduling using dynamic programming can be considered as a solution to this problem, but since there are a huge number of targets (5 in this problem) that must be considered at the same time, it is not practical due to processing time constraints. Not on point. Furthermore, it is difficult to directly apply linear programming to this problem because there are many nonlinear elements. The present invention is applicable to plants where multiple types of raw materials each have many raw material tanks, and the inventory level of these must always be kept above a certain level.
Providing a work plan that satisfies these requirements and stabilizes raw material transportation work and raw material receiving work into the raw material tank, and provides a control method based on the work plan, thereby improving production efficiency in the relevant plant. With the goal. The feature of the present invention is to replace the raw material blending equipment with a mathematical model, generate planning consideration points as route switching points of the raw material distribution device 104, and create a decision tree whose root is the raw material tank to be switched for each switching point. (Decision Tree),
The purpose is to perform a search for all possible switching patterns, obtain an efficient raw material tank receiving plan, and perform transport control. As is well known, in general network theory, when the number of stations and paths becomes large, it is impossible to find the optimal solution within a finite time, but in this solution method, all possible solutions are considered as determined above. The biggest feature is that the processing time is so small that it can be ignored because it is possible to do this by just examining the tree.This makes it possible to re-plan and control at any time during control. The details of the present invention will be explained by taking as an example the case where the present invention is applied to the raw material tank receiving step in the ironmaking raw material treatment process shown in FIG. FIG. 4 shows an example of the configuration of a raw material tank receiving planning device according to the present invention. This device is started by a timer 114 at regular intervals and by a change in the state of the process 113 (equipment failure, schedule change, etc.), and is started by a control device 115 that gives a control command signal to the process 113 and the state of the process 113. The situation understanding device 116 grasps the situation and converts it into a mathematical model.
A switching point generating device 117 that generates an operation direction switching time of 0, and a switching pattern determining device 1 that develops a switching pattern into a decision tree based on the results of the switching point generating device 117 and determines an efficient switching pattern.
18, a switching pattern memory 119 that stores the results of the switching pattern determination device 118. Here, the switching point generating device 117 and the switching pattern determining device 118 operate recursively, that is, the switching point generating device 117 generates a new switching point again according to the result of the switching pattern determining device 118, and starts the switching pattern determining device 118. do. Further, the control device 115 operates to extract a switching command from the switching pattern memory 119 from the timer 114 every time the switching pattern memory 119 is activated, and to provide a control signal to the process 113. The detailed operation of each device will be explained below with reference to FIG. 5 and the following figures. 5 and 6 show the operation of the situation grasping device 116. The situation understanding device 116 replaces the internal structure of the raw material distributing device 104 with a mathematical model, and uses the physical equipment situation as a logical value. The raw material dispensing device 104 has a logical structure that is different from other conveyance devices due to its nature. That is, when attempting to receive raw material into a certain raw material tank 105, the scraper above it (tank scraper 110) must be set to DOWN, and all tank scrapers 110 upstream thereof must be set to UP. On the contrary, DOWN
When there is a tank scraper 110 in the tank, it is impossible to transport the raw material downstream from it. Therefore, when one scraper malfunctions, it affects not only the relevant point but also the downstream side thereof. Fifth
The figure is a model of the equipment shown in Figures 2 and 3, including the receiving belt conveyor UKi and the tank belt conveyor.
The state function of the scraper 109 on the intersection of SBj is Sa
(i, j) (where i is the coordinate of the receiving belt conveyor UKi, j is the coordinate of the tank belt conveyor SBj), and the state function of the tank scraper 110 is expressed as Sb (j,
k) (where j is the coordinate of the tank belt conveyor SBj,
k indicates the coordinates of the raw material tank 105). Here, Sa (i, j) (or Sb (j, k) = 0: Normal state = 1: Failure at UP = 2: Failure at DOWN. In this example, for example, a scraper
Sa (1, 1) operates normally, but the scraper Sa
(2, 4) remains DOWN, indicating that it is in a failure state. Tank scraper 1 that is normal under this situation
It is difficult for an operator to accurately determine whether or not the raw material can be received below 10 by visual inspection because it is affected by the condition of the scraper on the conveyance path leading to it. In this apparatus, a scraper usability logical map as shown in FIG. 6 is created by the following procedure. (Step 1) <1> RSb (i, j) ← 0 (i = 1 to 4, j = 1
~8) <2> repeat while j=1~8, k=1~12 if Sb(j,k)=1 then RSb(j,k)←1 if Sb(j,k)=2 then RSb(j , n) ← 1 (n = k ~ 12) <3> repeat while i = 1 ~ 4 <3> - 1RSa (i, j, k) ← RSb (j, k) (j = 1 ~ 8, k = 1~12) <3>-2repeat while j=1~8 if Sa(i,j)=1 then RSa(i,j,n)←1(n=1~
12) if Sa (i, j) = 2 then RSa (i, m, n) ← 1 (m = j ~ 8, n = 1 ~ 12) <4> end However, in the above procedure description language, RSb is on the belt intersection The logical map RSa for the raw material tank 105 due to a failure of the scraper 109 is the scraper 109 on the belt intersection and the scraper 11 on the tank.
Logical map for raw material tank 105 due to failure of 0. Each language specification that defines RSb (or RSa) = 0: Acceptable = 1: Unacceptable is based on ALGOL. From Fig. 6 (1) to (4), for example, a certain raw material tank S (1,
1) Raw material tanks (hereinafter expressed as S(j, k)) can be received from receiving belt conveyors UK1, UK2, and UK3, but not from receiving belt conveyor UK4. The following schedule planning device operates based on the logical map created in this way. FIG. 7 and subsequent figures show detailed operations of the switching point generating device 117 and the switching pattern determining device 118. As mentioned above, the main purpose of planning this schedule is to maintain a high inventory level in all raw material tanks S (j, k) and to stabilize operations in raw material receiving work. However, it becomes more difficult to simultaneously satisfy these two objectives the more brands are tried to be stocked in the raw material tank S(j,k) during the same time period. The reason for this will be explained below using figures. FIG. 7 shows a raw material receiving schedule with time on the horizontal axis and the number of the receiving belt conveyor UKi on the vertical axis. For example, on receiving belt conveyor UK1, brand A is stored from time t ₀ to t ₂ , and brand A is stored at time t ₂ .
This indicates that warehousing is stopped from t6 to _t6 , and that brand E is scheduled to be transported from _t6 . Figure 8 shows the raw material tank S(j,
This figure shows an example of the stock allocation status and stock status of item k). Processes downstream from this process require mixed raw materials according to their purposes, so many types of brands are assigned under a single tank belt conveyor SBj. In Figure 8, the upper right number of the raw material tank S (j, k) indicates the inventory amount, the capital letters on the right indicate the brand name, and the upper limit value of all raw material tanks S (j, k) is 100, and the lower limit value is Assume 10. At this point, brand A on tank belt conveyor SB1 is raw material tank S (1, 1)
To, brand B on tank belt conveyor SB2 is receiving raw material tank S (2, 2), brand C on tank belt conveyor SB3 is receiving into raw material tank S (3, 3), on tank belt conveyor SB4. The brand C is the raw material tank S (4,
4). In this way, as shown in FIGS. 7 and 8, there occur discrete times (hereinafter referred to as switching points) at which the plant status, ie, the scraper status, must be changed and the storage destination of raw materials must be changed. In other words, work on one tank belt conveyor SBj can only be performed for one type of brand.
A situation arises in which it is necessary to switch to the raw material for the raw material tank S (j, k), which has a higher acceptance requirement. These are the following three depending on the factors that generate the request.
It can be roughly divided into types. Inventory level limit reached. The lower limit of inventory level has expired. Started receiving raw materials. FIG. 9 is an explanatory diagram of these. A situation where the upper limit level has been reached due to receiving work, such as the raw material tank S (4, 3) of brand C, is F (5, 3).
The situation in which the lower limit level is reached due to cutting out falls under 10). Or t ₁ in Figure 7,
It refers to the state after the acceptance start time, such as t ₄ and t ₆ . At these points, the acceptance state must be changed through some procedure. If 3
If no change is made at the two switching points,
In this case, the raw material will overflow from the raw material tank S (j, k) or the corresponding receiving belt conveyor UKi will have to be stopped, and in this case, it will be impossible to supply the raw material to the downstream process. As described above, planning an appropriate receiving schedule at each switching point will satisfy the first objective, reducing the number of switchings of the raw material tank S (j, k) and the number of stops of the receiving belt conveyor UKi. Doing so will satisfy the second purpose. However, the occurrence density of switching points with respect to time varies greatly depending on the schedule planning method. Particularly when the density is high, it becomes necessary to switch over-tank belts between a plurality of brands many times within a certain period of time. Considering this from an operational point of view, it is necessary to control the raw material distributing device 104 many times, and frequent switching due to its nature leads to undesirable mixing of raw materials, which is a major cause of equipment failure. In other words, for stable operation, it is most important to maximize the storage time for the same tank. In the present invention, these conflicting demands are resolved as follows using a minimum depth search method using a decision tree. The details of the present invention are shown in the example of FIG. 8, that is, the raw material tank S(1,1) of brand A.
The following description assumes that the switching point due to reaching the upper limit is determined by the switching point generation device 117. When brand A is continuously conveyed in FIG. 8, it is necessary to switch to a tank other than raw material tank S(1,1). However, at this time, the belt conveyor above the tank
Since work is being carried out on SB2, SB3, and SB4, it is easy to think that switching to the above-tank belt conveyor SB5 would be a good method, but there is a question as to whether this is the best option. For example, a belt conveyor above a tank
When switching to SB5, brand A will immediately reach the lower limit in raw material tank S (3, 1), so (raw material tank S (3, 1)
In 1), the stock amount of brand A is close to the lower limit. ) Immediately after this point, switching to the tank belt conveyor SB3 must be performed. Therefore, it may be better to switch to the tank-top belt conveyor SB3 rather than to switch to the tank-top belt conveyor SB5.
In this way, whether or not to switch to the above-tank belt conveyor SBj must be decided by taking into account the work on the switching destination above-tank belt conveyor SBj and the inventory status of the raw material tank S(j, k) in terms of time. In the present invention, the brand that requires switching at a certain point and the tank belt number j
Create a decision tree with the root as the root and determine the optimal schedule. In Figure 10, the upper half of the circle is the belt conveyor above the tank.
The number j in SBj is expressed using the vertex (-ⓓ sign) whose lower half means the stock name. That is,
Brand A (level 1) being worked on tank top belt conveyor SB1 is working on tank top belt conveyor SB2, SB3,
It is possible to switch to SB4 and SB5, and in that case, the corresponding belt work is performed with brands B, C, D, and b (b
indicates unworked). Since no work is being done on tank belt conveyor SB5, no further switching will occur, but further consideration is required for the other three belt conveyors, and the first
It is expressed as level 2 in Figure 0. If the same root (the apex of level 1) appears in level 2, this means that the switching source tank belt conveyor SBj and the switching destination tank belt conveyor SBj are switched alternately. It is called (〓mark). The reason will be explained later, but due to control difficulties, there is a possibility that high-quality raw materials cannot be obtained if this switching is performed, so this selection should be avoided as much as possible. Now, in level 2, the aforementioned open leaf (here
If we consider more deeply the vertices other than SB5) and the dead drop reef, the number of levels corresponding to the number of acceptance belts will be generated. Here, since it is physically difficult to switch between levels 3 and 4 without mixing the raw materials, this is an impossible solution in this scheduling. (This is called a closed leaf (ⓓ mark)) Therefore, the only impossible solutions are routes with open leaves and dead leaves. In this example, the total number of these is 10. The above is a method for extracting possible solutions, and FIG. 11 shows a method for selecting an optimal pattern from these. Figure 11 shows the target material tank S for each level.
(j, k) at each level.
HS indicates a tank to be switched, and HE indicates a tank to be switched. For example, the leftmost route in Figure 10

In the case of [Formula], the raw material tank S(1,1) of brand A (hereinafter expressed as A-S(1,1)) goes to A-S(2,1),
1) expresses a state in which B-S (2, 2) is changed to B-S (1, 2). Since this means that the tank belt conveyors SB1 and SB2 are interchanged, a check mark is placed in the DEAD LOCK column in Fig. 11. In this way, HS, HE, and DEAD ROCK for all routes are first extracted, and then each route is evaluated. In order to simultaneously satisfy the above-mentioned two objectives, the evaluation standard is, for example, a value obtained by superimposing the inventory ratios of the switching source tank and switching destination tank of the same brand. Formulating this, the overall evaluation E of a certain route is E= ₃ Σ ^LEVEL=0 E _LEVEL +E _DL However, E _LEVEL = (ZK _S / ZK _M ) _LEVEL → _LEVEL+1 ×100 ZK _M : Switching source tank inventory level ZK _S : Switchover tank inventory level E _DL : Predetermined value when deadlock is present (in this example
100). 0 otherwise. It is expressed as For example, in the leftmost route in Figure 10, A-S (1, 1) is ZK _M and A-S (2, 1) is
Since ZK _S , E ₀ = (ZK _S /ZK _M ) ₀ → ₁ ×100 = 97. Similarly, when LEVEL=1, B−S(2,
2) is ZK _M and B-S (1, 2) is ZK _S , so E ₁ =90. In this way, the overall evaluation E of the leftmost route is E=E ₀ +E ₁ +E _D

Claims (1)

[Scope of Claims] 1. Raw materials of a plurality of brands are transferred to a plurality of tank rows in which raw material tanks for each of a plurality of brands are arranged using a plurality of conveying means, and the raw material inventory amount in the raw material tanks is within a predetermined range. In a device that controls the conveyance so that the raw material is maintained at a plurality of tank-top belt conveyors for transporting the raw material to a plurality of tank rows in which raw material tanks are arranged; and a scraper for changing the transport path of the raw material from the transport means to the tank-top belt conveyor. It has a conveyance path diversion device and a control device that controls the conveyance path diversion device, and when the raw material stock amount of a raw material tank that stores a specific brand of raw material in a certain tank row reaches its maximum value, the When operating the conveyance path switching device to carry a specific brand of raw material into the raw material receiving tank that stores the specific brand, it is necessary to make a changeover at a certain point regarding the possible replacement of each brand to the above-mentioned tank belt conveyor. Create a decision tree with the combination of the required brand and tank belt conveyor number as the root, and for each replacement route on the decision tree, calculate the inventory ratio (E _LEVEL ) of the same brand between the switching source tank and the switching destination tank. The evaluation function E = _L 〓 ^{LEVEL E LEVEL} + E _DL LEVEL = 0 is calculated by superimposing the evaluation function E _LEVEL + E _{DL LEVEL} = 0, and the route that minimizes the value of the evaluation function E is calculated. A raw material conveyance control method characterized by determining the brand of raw material to be selected and transferred by a plurality of tank belt conveyors. 2. Claim 1 is characterized in that when creating the decision tree, the presence of a faulty scraper in the conveyance path diversion device is detected, and the decision tree is created by excluding the faulty scraper. A raw material transport control method.