Interaction model of steel ladle of continuous caster in steel works

Abstract. For further research on the precondition and interoperability model of interaction ladles among continuous caster, this article takes steel ladle of Y steel works as the object of research. On the basis of turnover number calculation model of single cast steel ladle, the relationship between cast number and the turnover number and turnover times and last turnover number are further analyzed. The simulation of steel ladle turnover rules was taken on the 2 continuous casters with Gantt chart. After that, the relationships between turnover number and last turnover number and non-turnover number are researched deeply. Combining with the Gantt chart, the expressions of start casting time and empty ladle ending time and heavy ladle starting time were put forward. The precondition of steel ladle interaction is obtained, which means the exchange ladle should not undertaking transport task in first stop continuous caster, and the empty ladle end time of exchange ladle of first stop continuous caster should early than the heavy ladle start time of last stop continuous caster. After applying the model to practice, 3 steel ladles of No.2 continuous caster can be reduced. This research results is supplying theoretical basis for steel ladle controlling and production organization optimization, and enriches the theory and method of metallurgical process integration.


Forward
As the interface technique between blast furnace and basic oxygen furnace continuous improvement, steel ladle is the vessel of liquid steel transporting between basic oxygen furnace(BOF) and continuous caster(CC) interface, and is the main tool of control steel temperature and production rhythm [1][2] .Besides, steel ladle is the buffer [3] of production rhythm.Its turnover number and operation efficiency and buffer capability are the key factors of control production and matching procedures.In a certain period of time, the less turnover number of steel ladle represents the higher turnover ratio and hot tapping ratio.At the same time, reducing turnover number has practical significance for reducing tapping temperature and keeping stabilization casting in CC [4] .However, how to reduce turnover number of steel ladle?Reducing number is the hot and difficult of production scheduling in steel works.Studies have shown that steel ladle interaction is an effective way to reduce the turnover number.What is the precondition and model of steel ladle interaction?Nowadays, the existing research results of steel ladle interaction is rare in reference.
Among the existing research results, the number of steel ladle is focused on calculation method, such as production method, time calculation method and turnover period matching method [5] .The result of the study is only applicable to the ideal state of single equipment and has more limited conditions.The turnover rule of steel ladle is simulated by Gantt chart under the condition of singlecast and multi-casts [6] .Furthermore, the calculation The model is under the different overlapping time of casts [7][8][9] .Moreover, the revolving model under the condition of saving ladle of steel also carried on through research [10][11] .The ladle number calculation model was also put forward based on smelting cycle of basic oxygen furnace single heat bigger than or less than the casting time of continuous caster single heat.From the existing research, we can see that the precondition and influence factor of steel ladle interaction are not discussed.
Therefore, using existing theory or method of ladle interaction, the application effect is apparently not good.

Operation process analysis of steel ladle
In order to research the model of steel ladle interaction between CCs, the operation process and time should be controlled firstly [12] .There has 3 basic oxygen All the above operation time can be measured and statistics and inductive.As shown in Table 1.According to table 1, by using Eq. ( 1

Number calculation model of single cast steel ladle
In order to research the precondition of steel ladle interaction, the ladle turnover number of single cast need to be confirmed.The existing research has mature research results of number calculation model [6][7][8] .As shown in formula ( 2) and (3).

Model of steel ladle interaction
The steel ladle will be exchange to other continuous  Gantt chart is an effective tool for planning production scheduling, and the relationship between production plan and each procedure can be vivid shown [13].The Gantt chart of operation rules of 2 CC's steel ladle are simulated, the operation process of steel ladle in various segment of time process can be shown.
Based on the results above, the precondition and model of steel ladle interaction can be in-depth studied.Gantt chart is a set of lines chart, which horizontal axis represents time and vertical axis represents activities and lines represents project performance [14][15][16]   The relationship between last need turnover number and non turnover ladle is expressed by Eq.( 5) and Eq.(6)   and Eq.(7).7Where g represents the last non turnover ladle of CC's cast.
According to Eq.( 5) and Eq.( 6) and Eq.( 7), the serial number of last non turnover and exchange ladle can express by Eq.( 8).Based on Eq.( 1) and Eq.( 9), the end time of No. k empty steel ladle can be expressed as shown in Eq. (10).8) and Eq.( 10), the end time of No.1 CC's empty steel ladle can be expressed as shown in Eq.( 11) and Eq.(12).
With similar to Eq.( 10), the start time of No. k heavy ladle can be expressed by Eq.( 13).11) and Eq.( 14) into Eq.(15), it can be gained Eq. (16)  15) and Eq.( 16), the feasibility of steel ladle interaction between No.1 CC and No.2 CC can be analyzed.This interaction condition can supply scientific basis for reducing turnover number of steel ladle.

Model applying
The interaction feasibility of steel ladle under the condition of Fig. 1 is analyzed by applying interaction model.Based on analyzing result of Eq.( 4), the 4# and 5# and 6# ladle of No.1 CC is finished transport task after turnover 3 times.The  12).The result is shown in Table 2.The overlapping time between 2 CCs equals 46min.
the start casting time of No.2 CC's first heat is calculated and equals 626 min by using Eq.( 9).The start time of No.2 CC's 7 heavy ladles is calculated by using Eq.( 14).
As shown in Table 3.
furnaces(BOF) of 100t, 2 ladle furnace(LF), 1 RH and 2 continuous casters(CC) of slab in Y steel works.Besides, Y steel works has 3 online baking positions(ONBP), 2 offline baking positions(OFBP), 1 hot repair position(HRP) and 2 de-slagging positions(DP).Through analyzing the operation process of steel ladle, the operation phase includes heavy operation and CC casting and empty operation.Operation phase of heavy ladle has 2 operation routes, which includes BOF-LF-CC and BOF-LF-RH-CC.The liquid steel of BOF-LF-CC route can supply to No.1 CC and No.2 CC.The liquid steel of BOF-LF-RH-CC route is just supply to No.2 CC.Operation phase of empty ladle has 2 operation routes, which includes DP-HRP-ONBP-BOF and DP-HRP-OFBP-BOF.
), the steel ladle turnover cycle of No.1 CC can be calculated, which equals 173 min.The steel ladle turnover cycle of No.2 CC equals 164 min under the operation route of BOF-LF-CC.The steel ladle turnover cycle of No.2 CC equals 205 min under the operation route of BOF-LF-RH-CC.

n
represents steel ladle turnover number of single cast; ª º represents the symbol of round up to an integer.According to formula (2) and (3), the number calculation model of single cast turnover ladle means that CC can cast number of liquid steel during turnover cycle.According to single heat casting time equals 32 min and turnover cycle equals 173 min, by applying Eq. (2), the No.1 CC needs 5.4 steel ladles for single casting, the number is 6 for round up to an integer.According to single heat casting time equals 27 min and turnover cycle equals 164 min, by applying Eq. (2), the No.2 CC needs 6.1 steel ladles for single casting under the operation route of BOF-LF-CC, the number is 7 for round up to an integer.This works choose the heavy ladle of "BOF-LF-CC" route as the object of research.At the same time, empty ladle choose "DP-HRP-ONBP-BOF" route.
research, the single cast of No.1 CC needs 21 heats, it can be shown in the expression of 21=3 u 6+3 by using Eq.(4), the 21 heats of single cast needs 6 steel ladles turnover 3 times and the first 3 steel ladles turnover one more time again.Meanwhile, the single cast of No.2 CC needs 25 heats, the expression of 25=3 u 7+4 can be obtained, the 25 heats of single cast needs 7 steel ladles turnover 3 times and the first 4 steel ladles turnover one more time again.
. The Gantt chart sets No.1 CC first start and stopping casting, and No.2 CC last start casting.The overlapping time between 2 CCs is 46 min.According to the calculation results of Eq.(4), the Gantt chart is just simulated steel ladle turnover rules of No.1 CC's last 9 heats and No.2 CC's first 7 heats, the feasibility of steel ICEICE 2016 02014-p.3ladle interaction between CCs can be analyzed.As shown in Fig.1.

Figure 1 .
Figure 1.Gantt chart of 2 CCs' steel ladle.As show in Fig.1, a color of line section represents the same steel ladle of CC.The last 9 steel ladles of No.1 CC need the red ladle and black ladle and yellow ladle turnover one more time again after all of ladles turnover 3 times.However, the violet ladle and brown ladle and gray ladle are finished transport task after turnover 3 times.This simulation results is consistent to the calculation results by Eq.(4).For No.2 CC last casting, it is need to observe the 7 steel ladles, whether some ladle can exchange to No.1 for replacing 4#/5#/6# steel ladle.After that, the turnover number of No.2 CC's steel ladles can reduce.

kd d 1 .
represents serial number of non turnover ladle of CC's cast, r represents the serial number of exchang ladle in non turnover ladle, g r Through analyzing single cast's steel ladle, the start casting time can express by Eq.(9).

T
represents the start casting time of No. k steel ladle, min.CC s t 1 represents the start casting time of No.1 steel ladle, min.k represents the order number of continuous casting heats.

T
represents the end time of No. k empty steel ladle, min Based on Eq.( time of No. k heavy steel ladle, min In term of No.2 CC, the start time of No. k heavy ladle can be expressed by Eq.(14).
.1 and Eq.(11) and Eq.(14), steel ladle interaction from No.1 CC to No.2 CC need to satisfy the precondition as shown below.The exchange ladle should not undertaking transport task of liquid steel in No.1 CC.The empty ladle end time of No.1 CC's exchange ladle should early than the heavy ladle start time of No.2 CC's steel ladle.Based on above condition, the exchange time can be expressed by Eq.(15).
The end time of 4# and 5# and 6# empty ladle is calculated from Eq.(5) to Eq.(

From what has been 6 Figures and tables 1 02014-p. 5 MATEC
discussed above, the analyzing interaction feasibility of steel ladle between CCs should control the turnover rules and cycle and number firstly, and analyze the relationship between empty ladle end time and heavy ladle start time, and propose the optimal replaced plan.Studies have shown that the cast plan and casting time of rational control and matching can raise the non-turnover number and probability of steel ladle interaction.The turnover cycle and number of steel ladle is described under the condition of single CC.The relationship between turnover number and heavy ladle operation time and empty ladle operation time and casting time is analyzed.2 The operation rules of 2 CCs steel ladle is simulated under the condition of 46 min overlapping time by using Gantt chart.The relationship between heat number and turnover number and turnover times and non turnover number is analyzed.Based on start casting time and casting time of No.1 heat, the expression of empty ladle end time and heavy ladle start time is proposed by analyzing empty ladle and heavy ladle operation time.3 The precondition of steel ladle interaction is obtained, which means the exchange ladle has no need of ICEICE 2016 Web of Conferences undertaking transport task in first stop CC, and the empty ladle end time of exchange ladle of first stop CC should early than the heavy ladle start time of last stop CC. 4 The model is applied to practice.There has 3 steel ladles of No.2 CC that can be replaced by 4# and 5# and 6# ladle of No.1 CC. the optimal replaced plan is 2# and 3# and 4# ladle of No.1 CC replaced by No.2 CC's steel ladle.Besides, this research results is supplying theoretical basis for steel ladle controlling and production organization optimization.At the same time, it enriches the theory and method of metallurgical process integration.
DOI: 10.1051/ C Owned by the authors, published by EDP Sciences, 201

Table 1 .
Operation time of steel ladle.
Based on Table 1, turnover cycle of steel ladle can be calculated by follows equation: CC cast T represents single heat casting time of CC, min.ladle empty T represents operation time of empty ladle, min.02014-p.2 caster for new transportation task once it has finished turnover, which means the interoperability among different continuous casters are realized.In some cases, the turnover number of steel ladle in steel works can reduce under some condition. .

Table 3 .
Heavy ladle's start time of No.2 CC's steel ladle.